Treatments of Mycobacterium tuberculosis and Toxoplasma gondii with Selenium Nanoparticles

Abstract  Toxoplasma gondii and Mycobacterium tuberculosis are pathogens that are harmful to humans. When these diseases interact in humans, the result is typically fatal to the public health. Several investigations on the relationship between M. tuberculosis and T. gondii infections have found that there is a strong correlation between them with each infection having a reciprocal effect on the other. TB may contribute to the reactivation of innate toxoplasmosis or enhance susceptibility to a new infection, and toxoplasma co-infection may worsen the severity of pulmonary tuberculosis. As a consequence, there is an earnest and urgent necessity to generate novel therapeutics that can subdue these challenges. Selenium nanostructures’ compelling properties have been shown to be a successful treatment for Mycobacterium TB and Toxoplasma gondii. Despite the fact that selenium (Se) offers many health advantages for people, it also has a narrow therapeutic window; therefore, consuming too much of either inorganic or organic compounds based on selenium can be hazardous. Compared to both inorganic and organic Se, Se nanoparticles (SeNPs) are less hazardous. They are biocompatible and excellent in selectively targeting specific cells. As a consequence, this review conducted a summary of the efficacy of biogenic Se NPs in the treatment of tuberculosis (TB) and toxoplasmosis. Mycobacterium tuberculosis, Toxoplasma gondii, and their co-infection were all briefly described.


Introduction
Contagious infections, caused by cadaverous pathogens such as toxoplasma gondii parasite, COVID-19, Mycobacterium tuberculosis, and Staphylococcus aureus (S. aureus), have been established as a major inducer of public health challenges associated with increased mortality and infectivity globally [1]. However, this study shall only focus on Mycobacterium tuberculosis and Toxoplasma gondii parasite which induces tuberculosis (TB) and toxoplasmosis infectious diseases, respectively.
Despite the tremendous effort invested in eradicating tuberculosis (TB), it is still one of the primary reasons of mortality and morbidity globally [2]. Tuberculosis (TB) is a chronic transmittable disease disseminated aerially via discharged droplets from someone that is infected [3]. The slow-growing tubercle bacillus Mycobacterium tuberculosis (Mtb) has been reported as one of the major causes of the disease [4]. TB is among the greatest cause of death induced by infection universally, with about 1.4 million recorded deaths in 2018 [5] and an evaluated 75 million individuals passing from TB in successive 35 years. TB is among the greatest cause of death induced by infection universally, with about 1.4 million recorded deaths in 2018 [5] and an evaluated 75 million individuals passing from TB in successive 35 years. Fresh TB patients were reported in 2018 alone, to be approximately 10.4 million universally [5]. Nowadays, TB therapy needs a 6-month administration of four firstline medicines, which are inefficient at curing the infection causing diseases due to strains of multidrug-resistant (MDR) Mtb [6]. According to the TB alliance, the rapid spreading of these strains has been reported worldwide as more than 480,000 cases were registered 2019 alone [7]. The cost of combating this infection could amount to $16 trillion over the next 35 years [7]. The increase in microbial resistance to antibiotics has led to a call for a non-antibiotic treatment approach that can effectively substitute antibiotics in combating bactericidal infections [8]. Recently, nanotechnology has been demonstrated to be an optimistic solution for treating communicable infections [9][10][11].
Toxoplasmosis is a parasitical infection instigated by Toxoplasma gondii that infects human beings and several kinds of birds and mammals [12]. The sexual life cycle of the parasite usually manifests in the cat's small intestine and a nonsexual cycle that occurs in humans and animals that are warm [13,14]. Infection in humans takes place by consuming undercooked and uncooked meat and also via the consumption of polluted fruits and vegetables. Different potential pathways of transmission can be from the placenta to the embryo during pregnancy in humans, which can induce severe health issues [15,16]. The signs of toxoplasmosis are multifarious, although light symptoms may be experienced in immunocompetent patients such as fever, muscle pain, headache, or being asymptomatic. Nevertheless, immunocompromised patients can also experience weighty clinical symptoms such as central nervous system involvement [17][18][19][20]. Currently, in the therapy of toxoplasmosis in animals and humans, there is no suitable known vaccine [21]. The joint administration of sulfadiazine and pyrimethamine is still the most preferred choice of remedy option for toxoplasmosis. However, unfavorable side effects such as teratogenic and osteoporosis effects have been demonstrated in immunocompromised people when the aforementioned combination was employed as a treatment option [16,20]. As such, there is an urgent need for the development of a more efficient substitute therapeutic agents that can combat toxoplasmosis with fewer or no side-effects.
Due to their numerous properties, such as increased strength, chemical reactivity, or conductivity due to high surface to volume ratios, altered electronic bandgap energy (optical properties), and tailored functionality, nanostructures are a product of the industrial revolution era and have led to an explosion of hundreds of new products. These properties enable their use in a wide range of inventive applications [22][23][24][25][26][27][28][29][30][31][32][33]. Particularly, metallic NPs have been established to be a promising biomedical therapeutic antibacterial agent as they function by directly impacting the bacterial cell wall without condition of endocytosis [33][34][35][36]. Furthermore, they have also been shown to possess magnetic or even optical features [37]. Several types of nanoparticles such as organic, metals, and oxides of metal nanoparticles involving multiple modes of action have been used as antimicrobial agents [10,24,38,39]. Nonetheless, nanoparticles influence bacteria in two primary lethal mechanistic pathways, which occurs concurrently, disrupting membrane prospect and production or cohesion of reactive oxygen species (ROS) [40].
Several studies have demonstrated the use of selenium nanoparticles (SeNPs) in numerous biomedical applications due to attributes such as high surface-to-volume ratio, bioavailability, low toxicity, antioxidant features, and biocompatibility [41]. Due to their decreased toxicity and capacity to release selenium gradually after ingestion, selenium nanoparticles (SeNPs) represent what we think to be a novel option for nutritional supplementation [42]. Furthermore, SeNPs have been proven by several studies to have antimicrobial action against diverse classes of bacteria ( Fig. 1) [42] as they significantly inhibit the development of some microbial pathogenic strains such as Escherichia coli, Staphylococcus aureus, and Leishmania spp. [43]. Earlier examinations have shown that the adaptable and intrinsic immune reactions against parasitic and microbial diseases depend on selenium for annihilating these micro-organisms; consequently, selenium deficit has been demonstrated to damage developed and intrinsic immunity and facilitate vulnerability to a broad spectrum of bacterial (Mycobacterium tuberculosis infection, Listeria monocytogenes), parasitic (Heligmosomoides bakeri infection, Nippostrongylus brasiliensis, and Trypanosoma cruzi), and viral (HIV infection and hepatitis C virus) conditions [7,44].
The major antimicrobial mechanistic pathways of these NPs are still undefined, several researchers have documented the powerful antimicrobial impacts exhibited by some form of selenium via reaction with membrane peroxidases and, thereafter, induce the generation of oxygen-free radicals comprising of superoxide anion [46]. On the contrary, some studies have tried to explain the biogenic Se NP antimicrobial mechanism of action by triggering apoptosis in the Leishmania main promastigotes and diverse eukaryotic cells [47,48].
Despite the numbers of studies on the efficacy of employing biogenic Se NPs to treat tuberculosis (TB) and toxoplasmosis, no comprehensive assessment of the numerous research studies conducted over the years on this topic has been reported. As a result, the efficiency of biogenic Se NPs against tuberculosis (TB) and toxoplasmosis was examined in this study. A concise description of Mycobacterium tuberculosis and toxoplasma gondii and co-infection of both pathogens were also highlighted.

Mycobacterium tuberculosis
Mycobacterium tuberculosis (M. tb) originates from the family of Mycobacteriaceaeis and is a pathogenic bacteria species that causes tuberculosis. M. tuberculosis was uncovered in 1882 by a scientist known as Robert Koch [49]. The presence of mycolic acid in it induces a waxy, uncommon cell coating surface. This coating induces cells impermeability to gram staining, making M. tuberculosis seem as a weak gram-positive pathogen [50]. The physiology of M. tuberculosis has been shown to be favorably aerobic and needs elevated amount of oxygen. Primarily, a pathogen of the mammalian respiratory system infects the lungs. The most often utilized diagnostic approaches for tuberculosis are the acid-fast stain, tuberculin skin test, polymerase, and culture, chain reaction [50,51]. The sequencing of M. tuberculosis genome was successfully carried out for the first time in 1998 [51]. About 10.4 million TB cases comprising 490,000 multidrug-resistant TB (MDR-TB) and 600,000 rifampicinresistant TB (RR-TB) were reported in 2016 (WHO, 2017) [52]. M. tuberculosis is an exceptional paradigm of intracellular pathogens that displays some very different classical virulence characteristics from the several other bacterial pathogens that secrete diverse toxins types, inducing intense tissue impairment and critical inflammation [53]. M. tuberculosis can survive in the host during prolonged latency period without inducing any substantial impairment on the host immunity except it is vulnerable by a number of factors. For instance, the host becomes compromised when it is simultaneously infected with the pathogen and human immunodeficiency virus type-1 (HIV-1) or treated with TNF-a blockers [54,55]. The host immune system is destabilized by the secretion of a variety of effector proteins by M. tuberculosis, reforming its way of life and enabling its intracellular existence to persevere in granulomas in the course of the infection latency phase [56].
Other than inducing TB, several evidences have linked M. tuberculosis to other human infections, such as autoimmune ailments, pulmonary intricacies, and metabolic syndromes [57]. Similarly, M. tuberculosis infection has been reported to interact with the human microbiome, which is associated with health conditions and immune balance [58].
A collection of host pattern recognition receptors (PRRs) has been demonstrated by several studies to mediate phagocytosis of M. tuberculosis [61]. They include complement receptors, mannose receptors, C-type lectin receptors, and Fc receptors, including dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) and macrophage inducible C-type lectin (Mincle) [62,63]. Some molecular constituents from M. tuberculosis have been pinpointed to promote this occurrence with precise mechanistic pathways [64,65]. The foremost characterized adhesion in M. tuberculosis that is vital for extrapulmonary dissemination of M. tuberculosis is the heparin-binding hemagglutinin adhesion (HBHA) [64,65]. The invasion of epithelial cells other than macrophages and a reduction in mycobacterial adhesion have been demonstrated by several studies whenever there is a loss of HBHA [65]. Lately, Ramsugit et al. (2016) proposed that M. tuberculosis pili (MTP) can also operate as essential adhesion molecules influencing the interactions of the mycobacteria-host cell [66]. Another group of bacterial exposed molecules-surface linked with the host cell entrance is known as mammalian cell entry (Mce). The recombination of the mce 1 gene into Escherichia coli confer on the bacteria the capability to intrude on the epithelial cells [67].

Epidemiology
The microorganisms that cause tuberculosis (TB), most usually affecting the lungs, are called Mycobacterium tuberculosis [68]. TB can be prevented and treated. By inhaling contaminated air, a person can develop tuberculosis [68]. By coughing, sneezing, or spitting, those who have lung TB can release the TB bacteria into the air. One only needs to breathe in a small number of these bacteria to become unwell [69]. One-fourth of the world's population has TB infection, meaning they have the germs in their systems but are not (yet) ill and are unable to spread the disease. Between 5 and 10% of people will develop TB in their lives [70]. When a person's immune system is compromised, such as when they smoke, are malnourished, have diabetes or HIV, or are fat, they are more likely to get sick. It may take several months for a person to experience the symptoms of active TB disease, such as a cough, fever, night sweats, or weight loss [70]. As a result, getting medical help may take longer, and the virus may spread to more people. Through intimate contact, people with active TB can infect 5-15 more people over the course of a year. Virtually, all HIV-positive and 45% of HIV-negative TB patients will die in the absence of appropriate therapy [70].
Globally, 1.6 million individuals died of TB in 2021. TB is the 13th most common cause of mortality worldwide and the second most fatal infectious disease (after COVID-19, above HIV/AIDS) [71]. 10.6 million tuberculosis (TB) infections are expected to exist globally in 2021. 6 million males, 3.4 million women, and 1.2 million children live in the world [71]. TB is contagious across all continents and age groups. Nevertheless, TB can be avoided and treated. In 2021, 1.2 million children worldwide acquired TB. The diagnosis and management of child and adolescent TB, which is commonly disregarded by medical experts, can be difficult. Eighty-seven percent of new TB cases in that year were from the 30 countries with the greatest TB burden. Multidrug-resistant tuberculosis (MDR-TB) continues to be a problem for public health and a risk to health security. Approximately one-third of those with drug-resistant TB received treatment in 2020 [72]. The prevalence of tuberculosis is decreasing globally at a rate of about 2% annually; between 2015 and 2020, this decline totaled 11%. With this, we have already surpassed the End TB Strategy's 20% reduction target for the period between 2015 and 2020. It is projected that TB screening and treatment will save 66 million lives between 2000 and 2020. The most recent national TB patient cost survey found that more than one in two TB-affected households have costs that exceed 20% of their family income [73]. The global target of eliminating catastrophic expenditures associated with TB for patients or their households by 2020 was not achieved. By 2022, it will be necessary to spend US$ 13 billion per year on TB prevention, diagnosis, treatment, and care in order to fulfill the global objective set at the UN high-level meeting on TB in 2018 [73]. Ninety-eight percent of tuberculosis (TB) cases that are recorded take place in low-and middle-income countries (LMICs), where financing is much less than what is required. Spending of US$ 5.3 billion in 2020 represented less than half (41%) of the global spending goal. In order to return TB funding to 2016 levels in 2020, the amount spent between 2019 and 2020 dropped by 8.7% (from US$ 5.8 billion to US$ 5.3 billion). Ending the TB epidemic by 2030 is one of the Sustainable Development Goals of the United Nations (SDGs) [74].
The majority of tuberculosis patients are in their peak years of employment. But there is risk for people of all ages. More than 80% of cases and deaths occur in low-and middle-income countries [74]. HIV-positive individuals have an 18 times higher risk of developing active TB (see TB and HIV section below). Those who have active TB are also more prone to have other immune-system weakening diseases [75]. People who are undernourished are three times more vulnerable. Globally, 2.2 million new TB cases that may have been caused by malnutrition were reported in 2021. Problematic alcohol usage and smoking both increase the risk of TB. In 2021, alcohol use disorders were the primary factor in 0.74 million of the world's 0.63 million new cases of tuberculosis (TB) [75].

Eradication and Prevention Tools of M. tuberculosis
Theoretically, all infectious illnesses, including TB, might be eradicated with sufficient resources, the right instruments, and political will. The presence of realistic, accessible, and implementable diagnoses, prevention methods, treatment options, and enough finance are among the crucial indications of eradicability [76]. Only smallpox and rinderpest have been completely eliminated to this point [77,78]. These techniques were accessible for both illnesses, together with a significant political commitment to effectively stop transmission and bring prevalence to zero. There are currently six continuing initiatives running to combat yellow fever, hookworm, malaria, dracunculiasis, poliomyelitis, and yaws [79]. Leprosy, trachoma, lymphatic filariasis, onchocerciasis, and newborn tetanus have also been named as prospective candidates for eradication by the International Task Force for Disease Eradication at the Carter Center [79]. Scientifically, the feasibility of eliminating a disease depends on three key preconditions: epidemiological vulnerability, efficacy of therapies, and elimination feasibility [80]. The following factors make TB resistant to eradication: it is easily transmitted; transmission occurs all year long and is not connected to a cyclical disease cycle (like influenza); there is no innate immunity to prevent reinfection; it is difficult to diagnose (current estimates from the WHO suggest that nearly one third of all TB cases are not detected); disease relapse is documented in a percentage of patients who complete treatment [80]. Further evidence that there is a slim chance of attaining worldwide TB eradication comes from the fact that TB removal has never been recorded from any nation in the world.
Effective preventive measures include a secure and efficient M. Despite significant research efforts over the past 20 years, there is no vaccine for tuberculosis. The existing bacille Calmette-Guérin (BCG) vaccination may lower mortality in young recipients but does not prevent infection. Despite the fact that BCG has been widely used for almost a century, TB is still a significant global issue [81], a vaccination against M. The complicated biology of M. tuberculosis continues to make the infection or disease a valuable instrument for eradication, but the creation of a vaccine to prevent it is severely hampered, the dearth of fundamental knowledge regarding immune system defenses and TB [82]. As of right now, no correlation between a vaccination's ability to provide protection has been found, and it is unclear what kind of protective host responses the vaccine should elicit or how strong those responses must be. Additionally, to treat or stop M, mucosal surfaces may need to be stimulated by immune responses, lung infection from tuberculosis, as the lung is the site of the illness. The comprehension of M has, surprisingly, received very little study, lung immunological reactions to TB mucosa [82]. It is impossible to move further without this crucial information, and a timetable for the creation of a potent preventative TB vaccine is therefore not possible [83]. The requisite clinical trials will take another 10 years to complete, even if a correlate of protection is found and a good vaccine formulation is found. As a result, by 2022, it will be impossible to anticipate a vaccination [84].

Origin and the Relevance of Nanoselenium
The concept of nanomedicine has become a new rising star in the world of therapeutics as a result of the multiple advantages that this cutting-edge platform provides [85][86][87][88][89]. The numerous issues that can arise with traditional medication dosing forms are being addressed using nanomedicine-based strategies . Most people agree that one advantage of nanomedicine is the greater safety it provides [96][97][98][99][100][101]. The toxicity issues with Se have been greatly reduced by the use of Se in the form of nanoparticles, and the greatest obstacle to Se's translation from the bench to the bedside is its narrow therapeutic window and little margin of dosage error [44]. Numerous methods, including biological and synthetic methods, have been reported for the generation of SeNPs [102]. Many selenoenzymes, including GPXs, TXNRDS, and deiodinases (DIO), are essential for a number of biochemical processes, including the body's built-in antioxidant defense system [103]. Se is a key component of many of these selenoenzymes. It has diverse antioxidant and pro-oxidant actions based on dosage, duration, and oxidation state [104]. The use of SeNPs significantly reduces the death brought on by acute Se toxicity in a mouse model by up to four times [105]. Hepatotoxic indicators also demonstrate that SeNPs considerably reduce the liver damage caused by high dosages of Se [106]. The fundamental query, though surprising, is how SeNPs can lessen Se's toxicological effects. Since Se's oxidation state is what produces the observed biological effects and the toxicity it causes, understanding Se's redox state is essential for providing an answer to this question [106]. The most important Se organic forms are selenocysteine, selenomethionine, and methylselenocysteine, whereas the most important Se inorganic forms are selenite and selenate [107]. The oxidation states of selenium (Se) include selenate, (SeO 4 2− , + 6), selenite (SeO 3 2− , + 4), selenide (Se 2− , + 2), and the Se (Se°) [107]. The carefully controlled interplay of Se's several oxidation states may have contributed to its decreased toxicity after nanosizing [108].
Se's bioavailability and water solubility in various oxidation states determine the reaction's danger. However, the precise reason for SeNPs' apparent lower toxicity is yet unknown. SeNPs have compelling antitumor activity and less toxicityrelated problems when compared to other Se species. SeNPs have been utilized to treat a number of ailments, including cancer, diabetes, inflammatory disorders, liver fibrosis, druginduced toxicities, Mycobacterium TB, and Toxoplasma gondii, according to Huang et al. (2013) [109] and Kumar et al. (2014) [110]. SeNPs scavenge free radicals in vitro in a size-dependent manner (5-200 nm). According to studies by Bo Huang and colleagues, small (5-15 nm) SeNPs have a higher ability to scavenge free radicals and stop the oxidation of DNA. Compared to free Na 2 SeO 3 , which showed an IC50 > 2.5 mM, the SeNPs demonstrated stronger effects at concentrations as low as 0.5 mM [111]. SeNPs have higher bioavailability and biological activity when compared to inorganic and organic Se molecules [112]. SeNPs, however, have a basic issue with insufficient cellular absorption. Significant efforts have been made to resolve this problem by conjugating specific ligands on the exterior surface of nanoparticles. This is a useful starting point for the treatment of Toxoplasma gondii and Mycobacterium TB. Surface capping compounds can enhance SeNPs' size, stability, selectivity, toxicity, cellular uptake, bioavailability, and biological activity. SeNPs have the potential to be used as nanoscale delivery systems for drugs that treat disease.

Selenium Nanoparticles for the Treatment of Intracellular Mycobacterium tuberculosis
Among contagious infections, tuberculosis (TB), induced by Mycobacterium tuberculosis (Mtb), has been established as one of the leading killers of humans worldwide. The invention of novel substitute therapies outside the existing antibiotics strategies to improve the treatment efficacy of TB cases has become a necessity due to the occurrence of drug-resistant [108]. Estevez et al. (2020) synthesized chitosan-stabilized Se NPs and investigated their effect on Mtb and Mycobacterium smegmatis (Msm) [7]. Transmission electron microscopy images displayed a well-ordered dispersed Ch-Se NPs with spherically shaped particles and uniform diameters of about 60-80 nm (Fig. 2). They observed that the typical metamorphosis stages of Mtb were inhibited by exposing the bacteria to selenium nanoparticles by impairing the integrity of their cell envelope.
The efficiency of Se NPs on mycobactericidal was carried out against two types of the sluggish-growing Mtb and the rapid-growing Msm, with MIC digits of 0.195 μg/mL and 0.400 μg/mL, respectively. Also, the antibacterial efficacy of bovine serum albumin stabilized SeNPs (BSA-SeNPs) on the Mtb was evaluated to rule out the additional effect of the chitosan in the Ch-SeNPs' bactericidal action. The result revealed a more heightened inhibiting proficiency in the bacterial growth for BSA-SeNPs when compared to the Ch-SeNPs at similar concentrations (Fig. 3A). The authors concluded that the mycobactericidal outcome of the nanoparticles was not dependent on the stabilizing agent, chitosan but the SeNPs. This study proved that Se NPs possesses a considerable antibacterial potential that is capable of killing mycobacteria. They went further to confirm this finding by analyzing with TEM (3A) and cryo-EM ( Fig. 3B, C). The outcome of their analyses showed that the contact interaction of the SeNPs with Msm and Mtb cell walls initiated an extrusion of their cytoplasmic material and integrity destabilization. The results of this study are very vital because the prospect of developing remarkable nanosystems with high antimycobacterial potential with either Se NPs alone or in combination with antibiotics could be a major breakthrough in the remedy of multi-drug resistant tuberculosis strains. One of the biggest challenges for TB and drug-resistant TB therapies from time passed up until now is the immune escape of Mtb from phagolysosomal obliteration and restricted drug delivery into infected cells. Pi et al. (2020) resolved this problem by integrating TB immunology prowess and nanoscience to develop the macrophagetargeted Se NPs for synergetic bactericidal and antimicrobial obliteration of Mtb in host cells [75]. Apart from the instant extermination of Mtb, the mannosylated Se NPs could also function as an outstanding carrier for the precise delivering of isoniazid into macrophages for heightened intracellular Mtb elimination [57]. More notably, Se NPs was shown to hamper the escape of Mtb-lysosome and stimulate Mtb integration into lysosomes to instigate lysosomal clearance of intracellular Mtb. Moreover, the activation of several host cell antibacterial immunity against Mtb, comprising apoptosis, autophagy, and M1 anti-bacterial polarization for heightened elimination of intracellular Mtb was effectively achieved by Pi et al. (2020) [75]. This study shows the possibility of establishing Se NPs to macrophage aimed collaborative bactericidal approach with broad-series inherent immunity purpose and substantial reduced toxicity. Based on this finding, it can be proposed that Se NPs may possibly function as more active cure against TB and multidrug-resistant TB than several therapeutic agents that have been utilized in the past.
For thousands of years, Mtb still remains one of the most exceptional and intelligent bacterial pathogens on earth due to its numerous escape pathways from immunological clearance during its concurrent development with human beings [113,114]. One of the major challenges is to countercharge the immune escape of Mtb for medication-resistant TB or TB therapy. A previous study documented the regulatory capability of Se NPs toward host cell immunity for thwarting Mtb immune escape [75]. The bactericidal influence of Se NPs against Mtb was first investigated, and thereafter, an unexplored nanostructure-mediated anti-TB approach for controlling Ison@Man-Se NPs was instituted for phagolysosomal obliteration of Mtb and synergetic drug elimination (Scheme 1). Ison@Man-Se NPs conglomerate in lysosomes, speeding up the discharge of isoniazid and exercise collaborative bactericidal and antimicrobial annihilations of Mtb by favorably penetrating their macrophages. The Ison@Man-Se NPs/Man-Se NP-assisted antimicrobial immunity in host cells, comprising the autophagosome-lysosome sequestration/destruction of Mtb, phagosome-lysosomal fusion of Mtb, autophagy/apoptosis induction via PI3K/Akt/mTOR signaling, anti-TB M1 polarization, and ROS-mitochondria, was also demonstrated. Unexpectedly, isoniazid destructions of Mtb and the fusion of Mtb into lysosomes for synergetic lysosomal was stimulated by Ison@Man-Se/Man-Se NPs (Fig. 4). Ison@Man-Se/Man-Se NPs also caused autophagy isolation of Mtb simultaneously, developing into lysosomelinked autophagosomal Mtb degeneration connected to PI3K/Akt/mTOR and ROS-mitochondrial gesticulating route. This macrophage-targeted nanostructured-mediated interdependent bactericidal approach with inherent broadarray immunity roles and a significant decrease in cytotoxicity may function as a more efficacious medication against multi-drug resistant TB and TB itself. These outcomes vehemently indicate that Se NPs do not only function as an explicit bacteria-annihilating agent or drug delivery system but could also be utilized in the regulation of host immunity for improved intracellular bacteria clearance.
Thus, we have innovated the macrophage-targeted antimicrobial plus bactericidal strategy to circumvent two notorious dogmas of TB pathogenesis in therapy, namely, the Mtb escape from the reduction of TB therapy period and prevention of TB drug resistance, and the improvement of patient adherence has experienced a reasonable growth over the years due to the continuous hunt for substitute distinctive anti-TB drugs and enhanced drug delivery approaches to the existing drugs [115]. Researchers have observed considerable improvement from arising drug delivery technologies and improvement in the therapeutic index of drugs induced by nanoparticles (NPs). These observed improvements have led to the compliance patient enhancement and a significant reduction in the side effects of anti-TB drugs. There was an attempt to solve the setback experienced by other colloidal carriers by developing lipid NPs at the advent of the 1990s [115]. Lipid NPs typically offer greater stability and heightened drug-loading capability and absence of organic solvent, and they are cost-effective when compared with the aforementioned NPs [115,116]. In comparison to solid lipid NPs, nano-lipid carriers (NLCs) comprised a blend of solid and liquid lipids, forming a defective matrix, which improves the drug-loading capacity [116]. Also, the potential expulsion of NLC during storage is minimized by their higher drug retention capability [9]. As a result of the aforementioned benefits of NLCs, Vieira et al. (2017) generated a mannosylated nano lipid carrier (NLC) incorporated with rifampicin to enhance the therapy of tuberculosis [117].
They employed a functional targeting approach and, thereafter, characterized the nanoparticles. The examination of the impact of the nanoformulations on antimycobacterial action and cell viability was carried out. The formulated nanoparticles revealed a size of roughly 315 nm (Fig. 5) and polydispersity of < 0.2. The developed drug showed encapsulation efficacy that was greater than 90% whose discharge is responsive to pH. An effective uptake by bone marrowderived macrophages was demonstrated by the mannosylated NLCs. Also, a hampering in the intracellular blossoming of mycobacteria was observed to be efficiently induced by rifampicin-loaded mannosylated NLCs in comparison to the other formulated drugs. The formed NLCs can be employed as a favorable carrier for the more unassailable and efficacious control of tuberculosis.
In a separate study carried out by Kazemi et al. (2021), the impact of Se-NPs on the Mycobacterium tuberculosis H37Rv strain was investigated, and the formulated nanoparticles demonstrated a reasonable restriction in the development of Mycobacterium tuberculosis [118].
The various research works reviewed in this study show that Se-NPs can be used solely or in combination with other therapeutic agents to formulate drugs as an effective substitute to other multi-resistant drugs against Mycobacterium tuberculosis. It is surprising that with the immense antibacterial properties reported for selenium nanoparticles by several authors, studies on the effectiveness of treating tuberculosis with the NPs are not only limited but started very recently in 2017. Even though the reviewed studies established that selenium nanoparticles exhibited a high Mycobacterium tuberculosis strain inhibiting capability accompanied with minimal or zero multi-resistance and low side effects, we recommend that more studies be carried out to exhaustively establish these claims.

Toxoplasma gondii
Toxoplasma gondii is a protozoan parasitic organism that transmits the infection to most species of endotherm animals, comprising humans, and induces the infection known as toxoplasmosis [119]. The life cycle of T. gondii as an apicomplexan protist which is an intracellular parasite is said to be completed within the small intestine of an animal like a cat, a widely known host for the production of oocysts induced from the sexual reproduction of the parasite [119]. These not sporulated oocysts which are expelled in the infested cat's defecation have diameters ranging from 11 to 13 μm. Due to sporulation, there is typically a discharge of sporozoites from the sporulated oocysts that get ingested by a transitional host. This ingestion infects the cells of lymph nodes and the intestine and transforms them into a fast-dividing asexual phase known as tachyzoite [120]. The tachyzoites spread to other body parts, and their speedy replication and related obliteration of host cells leads to acute toxoplasmosis, which is categorized by minor to serious clinical signs dependent on the host immune status and affected organ [119]. Subsequently, there will be the development of tissue cysts comprising a sluggish duplication of bradyzoite stage. The persistence of this tissue cysts which characteristically occur in the muscle, liver, and brain can exist for the rest of the intermediate host existence [120]. On ingestion by the animal, especially cat, tissue cyst tissue discharges bradyzoites which engage in asexual procreation inside the small intestine epithelium, accompanied by sexual procreation and oocysts generation [120]. Nevertheless, the acute phase of the life cycle, categorized by dissemination and replication of tachyzoite, is instigated if the tissue cysts is ingested by other intermediate hosts [121]. Tachyzoites can transfer perpendicularly to the fetus if infection takes place in the course of pregnancy [121]. Serious clinical consequences may result from their dependence on the infection duration and the involved host species [66]. Toxoplasma gondii has been established to be among the most "thriving" parasitic organisms ever since practically any endotherm animal can function as a paratenic host. Exposure in humans is recurrent, with projected rates of 30-35% in the overall populace [122]. Nevertheless, the rate of exposures is markedly determined by the activities and dietary operations ranging from 10 to 80% in definite inhabitants [123,124].

Prevalence of T. gondii Infections in Humans
Toxoplasmosis is a parasitic zoonose that is found all over the world. T. gondii infection in humans was initially discovered in the late 1930s [125]. Sabin was the first to demonstrate that Toxoplasma sequesters from humans and those acquired earlier from animals belonged to the identical species in 1939 [126]. Sabin and Feldman introduced the methylene blue dye test in 1948, which permitted seroepidemiological research in humans and a wide range of animal species, providing proof for T. gondii's widespread distribution and high prevalence in many parts of the world [127]. Since then, it has been estimated that the parasite has infected up to a third of the world's population [128,129]. Seroprevalence estimates for human populations, on the other hand, range significantly between countries, geographical locations within a country, and ethnic groups residing in the same area [130]. Consequently, antibodies to T. gondii have been identified in 0 to 100% of persons in various adult human populations throughout the last three decades [131]. When evaluating seroprevalence statistics for T. gondii infections, keep in mind that the numerous serological techniques utilized to help collect this data are not uniform [132]. The Sabin-Feldman dye test, which is still regarded the "global standard" for detecting T. gondii antibodies in people, is time-consuming and has the drawback of requiring a constant supply of live parasites [133]. As a result, alternative methods for antibody detection are currently used in most epidemiological investigations on T. gondii infections [122,123]. To detect antibodies to T. gondii in humans and animals, a variety of serological assays have been developed [39,133]. The sensitivity, specificity, and predictive results of these assays differ. As a result, even when performed in the same laboratory, no two tests provide the same findings in every case [134,135]. Furthermore, prevalence rates change over time and with the age of the participants in the study. [136]. As a result, the numbers presented here may not represent national prevalence and might even vary from the actual incidence of infection in different groups [136]. They are analogous, nonetheless, if they are understood as projections representing various levels of prevalence across similar groups, i.e., groups that are similar in terms of age, cultural traits, external conditions, or other variables that influence T. gondii infection epidemiology [136]. Seroprevalences in Central European nations such as Austria, France, Belgium, Germany, and Switzerland, for instance, were assessed to be around 37 and 58% among women of childbearing age without a prenatal record in the 1990s [81]. In Croatia, Slovenia, Poland, Australia, Northern Africa, and Poland, similar seroprevalences have been recorded in similar populations [136]. Seroprevalence is higher in several Latin American nations, including Argentina, Brazil, Cuba, Jamaica, and Venezuela (51-72%), as well as West African countries along the Gulf of Guinea, such as Benin, Cameroon, Congo, Gabon, and Togo (54-77%) [137,138]. Women of childbirth age in Southeast Asia, China, and Korea had lower seroprevalences (4-39%) [84,136]. Seroprevalences are also low in cold-climate areas, such as the Scandinavian countries (11-28%) [136,139]. However, there is absolute confidence that normal T. gondii infections are noticeably conventional in person human populations for the duration of the world (Fig. 6) [136].

Life Cycle of Toxoplasma gondii
T. gondii is an ever-present parasite that takes place in maximum regions of the world. It is able to infecting a strangely extensive variety of hosts and plenty of distinctive host cells [65]. The lifestyles cycle of T. gondii is facultatively heteroxenous (Fig. 7) [141]. Intermediate hosts are in all likelihood all warm-blooded animals along with maximum livestock and humans [142,143]. Definitive hosts are contributors of the own circle of relatives Felidae, for instance home cats (Fig. 8) [144]. T. gondii goes through two stages of asexual progression in intermediate hosts. Tachyzoites (or endozoites) multiply speedily in the first stage by repeating endodyogeny in a variety of host cells (Fig. 8) [144]. Last-generation tachyzoites begin the second progression stage, which leads to the generation of tissue cysts [145]. Endodyogeny allows bradyzoites (or cystozoites) to proliferate slowly within the tissue cyst [121]. The brain and muscular tissues are particularly attractive to tissue cyst. They are mostly found in the central nervous system (CNS), the eye, skeletal, and cardiac muscles [121]. They can also be found in visceral organs including the lungs, liver, and kidneys, but to a lesser amount [121]. Tissue cysts are the intermediate host's last phase and are instantly contagious [146]. They may live for the entirety of the host's life in some intermediate host species [146]. The mechanism behind this tenacity is unknown. Many researchers believe that tissue cysts break down on a regular basis, with bradyzoites converting into tachyzoites, which then reinvade host cells and turn back into bradyzoites within new tissue cysts [147].
If ingested by a host organism, the bradyzoites activate a further asexual sequence of growing number that comprised of initial endodyogeny multiplication accompanied by recurring endopolygeny in small intestine epithelial cells [148]. The sexual phase of the life cycle usually starts with the final stages of asexual multiplication [148]. Formation of gamogony and oocyst occurs in the small intestine epithelium as well. Unsporulated oocysts are distributed into the intestinal lumen and excreted into the surrounding [149]. Sporogony takes place outside of the host and results in the formation of contagious oocysts comprising two sporocysts, each involving four sporozoites [149]. T. gondii has three pathogenic stages: tachyzoites, bradyzoites enclosed in tissue cysts, and sporozoites enclosed in sporulated oocysts (Fig. 8) [144]. All three phases are contagious for both intermediate and final hosts, which can become infected with T. gondii primarily through one of the following pathways ( Fig. 9): (A) horizontally through oral intake of tissue cysts embedded in uncooked meat or main offal (viscera) of intermediate hosts (B) horizontally through oral ingestion of infective oocysts from the surrounding, or (C) vertically through transplacental transmission of tachyzoites [137]. Furthermore, in some hosts, tachyzoites may be transferred to offspring through the mother's milk [150]. T. gondii can therefore be transferred from intermediate to definitive hosts, factual to intermediate hosts and between definitive and intermediate hosts [150] (Figs. 7, 8, and 9). It is presently unclear which of the numerous modes of transmission is somewhat more significant in terms of epidemiology [123]. T. gondii infections, however, are not limited to the concentration of a particular host species [123]. Its life cycle can be extended indefinitely through the transfer of tissue cysts between intermediate hosts (usually when there is no definitive hosts) and also through the oocyst's transmission between definitive hosts (even when intermediate hosts is not present) [121].

Prevalence of T. gondii Infections in Humans
Toxoplasmosis is one of the most frequently occurring pathogenic zoonoses found throughout the world [151].
T. gondii-caused disease in humans was first identified in the late 1930s [152]. Sabin established for the first time in 1939 that Toxoplasma isolates from living beings and those originally collected from animals belonged to same lifeforms [126]. Sabin and Feldman's emergence of the methylene blue dye test in 1948 facilitated seroepidemiological research in living beings as well as a broad range of species of animals, providing proof for a ubiquitous dissemination and great occurrence of T. gondii across many regions of the world [127]. It is projected that up to one-third of the world's population has been compromised with the pathogen ever since [128]. Nevertheless, projections of seroprevalence in population groups differ considerably across countries, geographical location within a region, and ethnicities living in close proximity [128]. Thus, antibodies to T. gondii have been spotted in 0 to 100% of people from a variety of adult human populations during the last three decades [153,154]. When contrasting seroprevalence records for T. gondii infections, keep in mind that the distinctive serological techniques utilized for acquiring these data are not consistent [122]. The Sabin-Feldman dye experiment, which is also regarded the "gold standard" for detecting antibodies to T. gondii in humans, is time-consuming and requires a constant supply of live parasites [155]. As a result, other testing methods for antibody detection are now being used throughout many epidemiological investigations on T. gondii infections [155].
To detect antibodies to T. gondii in humans and animals, a variety of serological methods have been proposed [156]. The specificity, sensitivity, and predictive values of these testing methods tend to fluctuate [156]. As a result, no experiments yield the similar outcomes in every case, even when performed in the same research lab [156]. Furthermore, prevalence rates differ over time and with the age of the participants in the study [157]. As a result, the data presented here do not represent comprehensive national prevalence estimates and might even vary enormously from the accurate incidence of infection in population subgroups [157]. They are directly analogous, notwithstanding, if inferred as projections expressing differences in prevalence among roughly the same population, that is, populaces that are equivalent in terms of cultural habits, environmental elements, age, or other variables that impact the epidemiology of T. gondii infections [158]. In the 1990s, for example, seroprevalences in Central European countries such as Belgium, Austria, Germany, France, and Switzerland were predicted to be between 37 and 58% in women of childbearing age with no obstetric historical past [158]. Similar seroprevalences have been found in populations from Poland, Croatia, Australia, Slovenia, and Northern Africa [137]. Seroprevalences are significantly greater in many Latin American countries, comprising Brazil, Cuba, Argentina, Venezuela, and Jamaica (51-72%), as well as West African countries along the Gulf of Guinea, comprising Cameroon, Benin, Gabon, Congo, and Togo (54-77%) [137]. Relatively low seroprevalences (4-39%) have been disclosed for women of reproduction age in Southeast China, Asia, and Korea. Seroprevalence is also low in cold climate areas, such as the Scandinavian countries (11-28%). Nevertheless, there is no denying that T. gondii infectious diseases are extremely common in older population groups all over the world [137]. Molan et al. (2019) determined the universal prominence of disease transmission to assess any regional and geological patterns by critically analyzing the presently available epidemiological data on T. gondii infection prevalence (Fig. 10) [158]. Without regard to date or language, a holistic literature search was performed using several electronic databases. To find human T. gondii seroprevalence studies that selected subject areas from overall, seemingly healthy inhabitants, medically necessary subject heading terms were also used. The information was gathered and evaluated for both regional and global trends. The survey found 152 published studies comprising a total of 648,010 disciplines. 166,255 of these were seropositive for T. gondii infection, implying a global seroprevalence rate of 25.7% (95% CI: 25.6-25.8%). The cumulative seroprevalence spectrum was determined to be 0.5-87.7%. African countries had the greatest percent seroprevalence rate of 61.4%, accompanied by Oceania (38.5%), South America (31.2%), Europe (29.6%), the USA/Canada (17.5%), and Asia (16.4%). A wide range of environmental and human variables that impact the disparities in T. gondii seroprevalence rates was observed across global regions. Tracking the origin and transmission of T. gondii may assist health officials in specifying the threat contributing factors that would help them concentrate on instituting optimum solution for state-specific health guidelines targeted at T. gondii transmission management.

Selenium Nanoparticles for the Treatment of Toxoplasma gondii Infection
Selenium (Se) is a mineral that is necessary for human health. When this element is deficient in the human body, serious symptoms such as deficiency and immune system cognitive deficits can emerge [159]. This element is also found in favorable proteins with anti-cancer, anti-oxidant, and anti-microbial characteristics [160]. Furthermore, due to their large surface ratio, nanostructured materials have diverse bioactive advantages. One such biomedical advantage is that they enter the cell more easily than other particles [161]. Recent research has shown that SeNPs can inhibit the growth of a variety of bacterial pathogens, including Escherichia coli, Staphylococcus aureus, and Leishmania spp. [162]. Even though accurate antimicrobial mechanistic pathways of this element are still to be ascertained, new research has shown that the inorganic forms of this element can influence membrane peroxidases to generate oxygen free radicals such as superoxide radicals [163]. Notwithstanding, several researches have shown that SeNPs can induce apoptosis in a variety of eukaryotic cells [164]. Current findings have shown that SeNP therapy increases cellular immunomodulatory cytokines like IFN-, IL-12, IL-2, TNF-, and some inflammatory mediators including nitric oxide (NO) [34]. The Th1 immune response, as described by the generation of IL-12 and IFN-, is characteristic of pathogens with several intracellular microbial species, including T. gondii, and mice lacking either IL-12 or IFN-are unable to regulate the infection [43]. Based on this information and the substantiated antimicrobial and immune-modulating properties of selenium. The speculation that SeNPs as a powerful agent in fighting against T. gondii infections have gained so much relevance. For instance, Yazdi et al. (2015) investigated the therapeutic efficacy of Se NPs in a mouse model against chronic Toxoplasma gondii [46]. They infected mice with Toxoplasma gondii strain. Thereafter, the infected mice were injected with Se NPs per day at dosages of 2.5, 5, and 10 mg kg 1 . The mean number of brain tissue cysts and mRNA levels of TNF-, IL-12, IL-10, IFN, and inducible nitric oxide synthase (iNOS) in each group of mice were measured on the fifteenth day. Furthermore, serum clinical chemistry variables in induced rats were investigated to determine SeNP safety. In clinical chemistry parameters, the mean number of tissue cysts was considerably (P0.05) greater than the control subset of the population of mice compared to those treated with Se NPs. In comparison to several other related research, the SeNPs considerably decreased the number of brain cysts in murine models. Consequently, SeNPs' low toxicity, enhanced cellular immunity, and outstanding antitoxoplasma characteristics hold great promise for the future targeted therapy. They were able to demonstrate the therapeutic properties of SeNPs mainly by regulating the immune system via the increase of inflammatory cytokines and immune mediators like IFN-, TNF-, IL-12, and iNO (Fig. 11). The outcome of this study demonstrated the therapeutic efficacy of SeNPs against innate toxoplasmosis in an animal model with no significant toxicity. Nonetheless, more investigation is necessary to define the precise anti-toxoplasma mechanisms of SeNPs, identification of an active dose with minimal toxicity in heightened-risk persons will be an imperative next step toward the regulation of toxoplasmosis.
A similar study carried out by Keyhani et al. (2020) discovered that biogenic selenium nanoparticles (SeNPs) have a variety of therapeutic activities, including antimicrobial properties against latent toxoplasmosis [44]. Using a mouse model, the authors evaluated the effectiveness of biogenic selenium nanoparticles (SeNPs) as a possible generic drug against innate toxoplasmosis. Male BALB/c mice were given SeNPs orally per day at dosages of 2.5, 5, and 10 mg/kg for fourteen days. An intraperitoneal inoculum of 20-25 tissue cysts from the Toxoplasma gondii Tehran strain was used to infect the mice on the 15th day. In each tested group of mice, the mean number of brain tissue cysts and mRNA intensities of IL-12, TNF-, IFN-, IL-10, and inducible nitric oxide synthase (iNOS) were estimated. Furthermore, serum clinical chemistry factors in treated mice were studied to regulate safety of Se NPs. The average number of functional tissue cysts was remarkably (P 0.001) reduced in mice injected with Se NPs at dosages of 5 (n = 11), 2.5 (n = 37), and 10 mg/kg (n = 3) in comparison to the controls (n = 587). In mice treated with SeNPs at dosages of 10 mg/kg, mRNA levels of IFN-, TNF-, IL-12, and iNO were considerably greater than in control subgroups (P 0.05). There was no great disparity (P > 0.05) in clinical chemistry variables between the control subgroups and the groups medicated with Se NPs. The current study revealed that the injection of biogenic selenium NPs in concentrations of 2.5-10 mg/kg for 2 weeks was capable of preventing serious toxoplasmosis symptoms in a mouse model. This result demonstrated the prophylactic consequences of SeNPs against innate toxoplasmosis with no significant toxicity. However, as in the study of Yazdi et al. (2015) [46], the precise anti-Toxoplasma mechanisms of Se NPs remain unknown.
The efficacy of biogenic Se NPs against acute toxoplasmosis in mice was also determined by Shakibaie et al. (2020) [165]. The authors examined the in vitro cell safety and effectiveness of biologically active Se NPs against severe toxoplasmosis induced by Toxoplasma gondii (Sarcocystidae) in mice. NMRI male mice were medicated with ordinary saline (control) and Se NPs at dosages of 10 and 5 mg/kg every day for 14 days. The mice were infected with 104 T. gondii RH strain tachyzoites intraperitoneally on the 15th day. The fatality rate and parasite load in infected mice were determined. Quantitative real-time PCR was used to look at the mRNA levels of IL10, IFN-, IL12, and inducible nitric oxide synthase in infected mice. On the 9 and 10 days of administration, the mortality rate in the infected mice injected with Se NPs at dosages of 10 and 5 mg/kg was 100% in comparison to the mice in the control group (Fig. 12). Infected mice medicated with SeNPs had a significantly lower mean number of tachyzoites than the control groups. There was no substantial disparity (P > 0.05) in biochemical properties between cells injected with Se NPs and in the control group. The findings indicate that mRNA levels were considerably enhanced in the afflicted mice medicated with Se NPs in contrast to the control group (Fig. 13). The current study is in agreement with the outcomes of Yazdi et al.

Co-infection of Toxoplasma gondii and Tuberculosis
Numerous studies over the years have proposed that pathogenic infection might even increase the susceptibility to tuberculosis [166][167][168]. Human co-infection with tuberculosis and parasitic diseases is a major health issue in Fig. 11 Results of the study of the expression of genes producing IL10, TNF-α, IL12, IFN-γ, and iNO cytokines in mice treated with SeNPs (*P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001 were considered significantly different when compared with the control) [46] coendemic regions of developing nations [169]. Nevertheless, epidemiological research examining the relationship between T. gondii infection and tuberculosis are very few. Although the coexistence of tuberculosis (TB) and parasitosis in humans is a growing problem in coendemic areas especially in developing countries. In a case-control study carried out by Zhao   among TB patients should be conducted on a regular basis in order to avoid the potential serious toxoplasmosis. Several incidents of TB co-infection with intracellular pathogens, such as malaria [171], visceral leishmaniasis [172], and T. gondii [173], have been reported. Hwang et al. (2012) described a case of cerebral toxoplasmosis in a patient with promulgated tb disease [174]. Alteration of the immune system response has been proposed in rare situations of co-infection [175]. The immune system's response to infections includes the production of reactive oxygen species (free radicals), which are harmful to human cells and tissues. Malondialdehyde (MDA), a lipid peroxidation product, is thought to be a marker of oxidative stress, a pathway that causes protein and DNA damage within cells [176]. Oxidative stress has also been linked to the pathogenesis of both toxoplasmosis [177] and tuberculosis [178]. Nevertheless, for the first time, Mashaly et al. (2017) looked into the link between toxoplasmosis and tuberculosis in a community in Egypt [179]. The possible impact of Toxoplasma co-infection on the lethality of pulmonary tuberculosis by monitoring serum MDA levels as a marker of oxidative stress in TB/T. gondii co-infected patients versus toxoplasmosis-free TB control subjects was also studied.
Three hundred presumed pulmonary tuberculosis incidents were first tested for tuberculosis using Lowenstein Jensen culture and direct Ziehl Neelsen staining of their sputum. The Xpert MTB/RIF assay discovered rifampicin resistance. A control group of 30 age-and gender-matched healthy people who were TB-free was included for comparative purpose. Serum levels of malondialdehyde and anti-toxoplasma IgG antibodies were also measured in all subjects (MDA). There were 43 proven TB patients, including 10 (23.3%) rifampicin-resistant patients. Corresponding toxoplasmosis was reported to be strongly greater in TB patients (OR = 2.709; 95% CI: 1.034-7.099; P 0.05) and in rifampicin sensitive TB patients compared to rifampicin resistant TB patients (OR = 0.213; 95% CI: 0.048-0.951; P 0.05). Anti-Toxoplasma IgG antibodies and MDA levels in serum were way greater in TB patients than in the control group. Besides that, serum MDA found to be significantly higher in TB/Toxoplasma co-infected patients than in toxoplasmosis-free TB patients. In TB patients, there was a strong positive correlation between serum levels of anti-Toxoplasma IgG and MDA (r = 0.75, P = 0.001). Toxoplasmosis is common among Egyptian patients with pulmonary tuberculosis. Toxoplasma co-infection may worsen the serious nature of pulmonary tuberculosis. The identified risk factors associated with the co-infection of Toxoplasma gondii and Tuberculosis may aid in the establishment of prevention programs that may help in reducing and screening patients with Toxoplasma gondii/Tuberculosis co-infections for timely diagnosis and therapy to reduce complications in vulnerable group of patients.
A similar study was also carried out by Kita & Tume (2018) at the Bamenda Regional Hospital (BRH), North West Region, Cameroon, Tuberculosis Reference Laboratory and Treatment Centre from October 2015 to April 2016 [180]. To find out how common toxoplasmosis and tuberculosis co-infection is among (TB) patients, a cross-sectional survey was used to collect data on 147 sputum positive TB patients. An epidemiological questionnaire was used to collect data on optimistic pulmonary TB patients of male and female sex, after which some toxoplasma risk factors were investigated, accompanied by blood specimen collection. IgG antibodies and T. gondii IgM in sera samples were investigated using indirect ELISA. T. gondii antibodies were found in 83% of TB patients (122/147,. Toxoplasma infections were found in 85.25% of the study population, with up to 53.28% of patients reactivating. There was no substantial difference in incidence between HIV-negative and HIV-positive TB patients. The increased seroprevalence of toxoplasmosis among TB patients at the Bamenda Regional Hospital suggests co-infection. Co-infection of tuberculosis and toxoplasmosis are exploitative pathogens for HIV/AIDS, as well as life-threatening to TB patients, and may be the cause of mysterious mortalities within these patient populations on treatment.

Selenium Nanoparticles for Co-infection of Toxoplasma gondii and Tuberculosis Therapy
The positive results of several studies on the therapeutic potency of Se NPs against Toxoplasma gondii and tuberculosis reviewed in this work suggest that Se NPs can also be an effective therapeutic agent in cases of TB co-infection with Toxoplasma gondii. There is, however, no mention of any studies in this regard. It is our recommendation that studies on the use of Se NPs in the treatment of the aforementioned co-infections be conducted.

Anti-Mycobacterium tuberculosis and Toxoplasma gondii Action of SeNPs' Mechanisms
SeNPs' antimicrobial activity has been evaluated against a variety of pathogens, including gram-negative, grampositive bacteria, and fungi [181][182][183], either alone or in conjunction with conventional antibiotics. The particular processes involved the anti-Mycobacterium tuberculosis and anti-Toxoplasma gondii activity of SeNPs have never been examined, in addition to the fact that studies about the mechanisms of antimicrobial action of SeNPs are sparse. As a result, since SeNPs can be categorized among them, we will talk about their potential antimicrobial effects on gramnegative, gram-positive, and fungal organisms. According to broad theories, certain nanoparticles can disrupt cell walls and membranes, penetrate into cells, or cause oxidative stress [184,185].

Cell Wall and Membrane Damage
Cell wall and membrane components could be involved in different adhesion path-ways for nanoparticles. One of the functions of the cell wall and membrane is to protect the microorganism against environmental threats while maintaining its homeostasis, allowing nutrients transport within the cell [186]. These characteristics are part of the bacterial classification, which is based on differences in cell wall structures. Thus, the cell wall of gram-negative bacteria has a thin layer of peptidoglycan with an additional outer membrane consisting of lipopolysaccharide [187]. On the other hand, the cell wall of gram-positive bacteria is typically thicker and is mainly composed of peptidoglycans [112,188]. Mycobacterium tuberculosis is a weakly grampositive, non-motile, rod-shaped bacterium. It is also a facultative intracellular parasite as well as an obligated aerobic [189]. This clarifies why tuberculosis often affects the lungs as a disease. Mycobacterium's cell walls primarily consist of lipids, in contrast to other bacteria whose cell walls are primarily made of peptidoglycan. It can only display grampositive or gram-negative bacteria because to the lipid layer's resistance to gram staining. Advanced techniques, such as acid-fast staining, are used to determine Mycobacterium function [190]. Toxoplasmosis is frequently linked to immunosuppression in the majority of animals. Both serologic testing and histological examination of the brain tissue can distinguish this condition from encephalitozoonosis. Although they are found as an associated lipopolysaccharides layer in gram-negative bacteria, they lack the thick peptidoglycan layer observed in gram-positive bacteria. These structures are transformed by the physical interaction between nanoparticles and the cell wall [191]. Both grampositive and gram-negative bacteria get a negative charge from the cell wall when the pH is neutral [192]. The group of microorganisms with the biggest negative charge, however, consists of gram-negative bacteria. Additionally, the lipopolysaccharides in the outer membrane of gram-negative bacteria are partly phosphorylated, which raises the negative charge of the cell envelope [193]. The interactions between the bacterial cell wall and the NPs or ions produced from it are thought to be affected by this negative charge [193]. SeNPs are drawn to the negatively charged cell wall by electrostatic interactions when they come into contact with positively charged bioorganic molecules like proteins or amino acids [194]. These nanoparticles cause cell walls to break and become permeable as a result of forming a solid link with membranes [195,196]. Thus, SeNPs' adherence to the cell wall and cell membrane is the first step in their interaction with Mycobacterium TB and Toxoplasma gondii. This binding is based on the electrostatic attraction between the positively or less negatively charged SeNPs and the negatively charged cell membrane [185]. Following their attraction to and contact with the microorganisms, SeNPs alter the structural and morphological features of the target cell, impairing membrane permeability and respiratory activity. Depolarization of the membrane, cellular integrity being compromised, and ultimately cell death is how this effect manifests [197]. Proteins, enzymes, DNA, ions, metabolites, and energy stores seep into the environment as a result of enhanced membrane permeability and cell wall breakdown [185]. Therefore, the primary mechanism of antibacterial action is the breakdown of Mycobacterium tuberculosis and toxoplasma gondii cell walls by the attachment of nanoparticles.
Using propidium iodide and cyanine diSC3-5 fluorescent dyes, Huang et al. [197] examined the impact of SeNPs on the cell membrane to illustrate this mechanism, S. coli and E. MDR cells of aureus. The rise in fluorescence for both dyes suggested membrane degradation. In this research, SeNPs coated with acetylcholine, quercetin, or a combination of the two were applied to E. coli and S. aureus MDR cells. When bacteria were cultured with Qu-Ach-SeNPs (25 g/mL) and Ach-SeNPs (25 g/mL), the fluorescence of dyes significantly increased (P < 0.01), demonstrating an increase in the membrane's overall permeability. When bacteria are exposed to SeNPs, as opposed to a control group of bacteria, they exhibit cellular contraction and take on an irregular shape, according to SEM and TEM examinations [90,198]. For instance, following E. coli incubation S. coli and E. Cell lysis and intracellular leakage were seen in S. aureus with coated SeNPs. E. coli, but not in S. aureus, there were disorganized cell walls as well as sunken cell walls and cytoplasmic leakage [197]. When S. aureus and B. subtilis comes into contact with SeNP-soluble starch, the cells contract and fragment, causing the cell shape to change and the size to differ noticeably [198]. The effects of bio-SeNPs on the cell walls of gram-positive bacteria (S. aureus, B. cereus, and B. subtilis) and gram-negative bacteria were assessed by Zhang et al. (2021) [185] in a different study (P. aeruginosa, E. coli, and V. parahemolyticus). gram-negative bacteria and B were both damaged to varying degrees in bio-SeNP-treated bacteria. Surface pits and holes might be seen in subtilis, while in S. aureus, it was discovered that some membranes were wrinkly, flattened, and surrounded by cytoplasm, which suggested intracellular content leaking. These scientists also showed that bio-SeNPs speed up the leaking of proteins and polysaccharides from bacterial cytoplasm. Furthermore, SeNPs harm bacteria by rapidly depolarizing their membranes, which is one of their mechanisms for doing so [191]. So, Huang et al. [90] looked into the impact of SeNPs on the polarity of S. aureus cell membranes. They thus discovered that bacteria treated with SeNPs resulted in a dose-dependent moderate membrane depolarization. SeNP (43 nm) concentrations of 6.25 and 12.5 g/mL resulted in 15 and 25%, respectively, of depolarized cells. However, 20 and 30% of the cells were achieved with higher SeNPs (81 nm) at the same doses. Finally, cells exposed to particles with a diameter greater than 124 nm kept their spherical shape and smooth cell wall. The modification of intracellular concentrations of adenosine triphosphate by SeNPs, on the other hand, has been suggested by Huang et al. [90] to be a related mechanism to metabolic interference (ATP). All living things need energy, and ATP is a substance that fuels this energy. Given that it is the primary source of energy for numerous enzyme activities, it is essential for both respiration and metabolism. As a result, these scientists investigated the impact of various SeNP concentrations and sizes on the ATP level of S. aureus. They discovered S. aureus colonies treated with SeNPs demonstrated a substantial reduction in ATP, with 81 nm particles inducing the largest caused depletion. This quick cellular ATP depletion is a sign of the energetic uncoupling effect.

Intracellular Penetration and Damage
Since NPs can pass through the membrane, they can also disrupt the metabolic processes of Mycobacterium TB and toxoplasma gondii cells, particularly when they exhibit a specific level of damage and interact with DNA and proteins [199]. This effect exemplifies one of the ions-based suggested pathways for NPs' antibacterial activity [200]. In this way, numerous researchers have noted that SeO is soluble in trace amounts in aqueous conditions. As a result, the quantity of Se ions released from SeNPs is probably quite modest. In other cases, Se ions' antibacterial activities can be insufficient, suggesting that SeNPs' mechanism is inconsequential [90]. In one investigation, Gali c et al. [195] found that SeNPs with various coatings had an antibacterial impact against S. aureus was exclusively caused by the particles, and the release of Se ions is not thought to be responsible for the antibacterial effect. The reason for this was that the solubilized fractions of SeNPs had very low values, and the antibacterial effect of selenite was ineffective at high concentrations (MBC > 100 mg Se/L). Despite being somewhat new, the investigations indicate a trend in research suggestions that covers the full range of antimicrobial mechanisms connected to chemicals' penetration through bacteria's cell membranes and subsequent interactions with their metabolism.

Oxidative Stress
The term "reactive oxygen species" (ROS) refers to molecules that contain oxygen and have a high redox potential. The production of ROS and the cell's antioxidant capacity are balanced under normal circumstances. The redox balance of the cell, on the other hand, favors oxidation when there is an imbalance between the antioxidant system and the excessive generation of ROS, which results in oxidative stress. Additionally, oxidative stress is a cellular activity that is involved in numerous areas of cell signaling, but when it manifests excessively, it harms cell metabolism irreparably and impairs viability [184,201]. According to the research, SeNPs are absorbed on the surface of bacteria and cause cellular oxidative stress after being added [185,201]. Cells respond protectively to this stress by developing enzymatic or non-enzymatic defensive mechanisms [202]. The cell wall and biomolecules including proteins, lipids, and DNA are vulnerable to damage by ROS and free radicals such hypochlorous acid (HOCl), hydrogen peroxide (H 2 O 2 ), hydroxyl radical (OH), superoxide anion (O 2− ), and singlet oxygen ( 1 O 2 ) when oxidative stress outweighs defensive systems [37]. In this regard, Huang et al. [185] established that oxidative damage is the reason why bacteria like E. coli die. E. coli and S. aureus when given SeNPs. This study demonstrated that both cultures of bacteria treated with quercetin and acetylcholine SeNPs (Qu-Ach @ SeNPs) produced considerably more ROS when total ROS concentrations were evaluated. However, in the presence of SeNPs-quercetin and SeNPs-acetylcholine, no discernible rise in ROS generation was seen in the treated E. coli. This suggests that the production of ROS is connected to the antibacterial activity of Qu-Ach @ SeNPs. Huang et al. [90] reported that SeNPs enhanced ROS generation in another investigation S. aureus cells. These substances were identified by the amount of fluorescence they produced when 43 nm and 81 nm SeNPs were present in the media. The findings revealed an increase in ROS levels of between 8 and 10%. In contrast, when SeNPs are absent from the media, the generation of ROS is not greater than 2%.
Similar to this, when Bio-SeNPs were tested against gram-positive and gram-negative bacteria, Zhang et al. [185] demonstrated that ROS production is responsible for antibacterial action. A fluorescent microplate system was used to generate ROS, and 10,000 bacteria or less were emitting light without coming into touch with SeNPs. All of the studied bacteria showed an increase in intensity following the addition of SeNPs: 50,000 for P. aeruginosa and 23,000 for E. coli, 20,000 for S. aureus and V. parahemolyticus, subsequently, 150,000 for B. aureus. subtilis. According to earlier findings, one of the most significant antibacterial mechanisms would be the rise in ROS brought on by bio-SeNPs. Research has shown that ROS production has a substantial impact on cell death and that Se found in nanoparticles may increase it. This would demonstrate SeNPs' ability to fight off microorganisms, but more studies are needed to pinpoint the molecular mechanisms of action.

Challenges of Using Selenium Nanoparticles Against Bacterial Infections
As a type of unique nanostructured material, Se NPs have received much interest in tackling the problem of antibiotic resistance, demonstrating promising potentials for potential therapeutic contagious treatments [203]. Nevertheless, there are some unavoidable barriers that must be resolved before their pharmacological adaptations can begin. The most pressing concern is biocompatibility, which is a material's ability to be compatible with healthy cells. When introduced to the body or bodily fluids, suitable biocompatible nanomaterials would not cause unpredictable cytotoxic activity or immunological response [204]. The toxicity of excess selenium, on the other hand, is a risky implication that may be introduced by Se NPs [205]. Although the toxic effect of Se NPs for antitumor activity or anti-infection therapeutic interventions has been widely publicized, the toxic effect of Se NPs against standard cellular components has yet to be researched [206]. Thus, understanding the bridge between selenium and Se NPs is extremely crucial, particularly for the molecular pathways that are mainly accountable for pharmacotherapy disparities and toxic impacts that are pivotal for their biocompatibility [207]. Or else, the degradation of Se NPs in the body is unknown, which could lead to unknown toxicity after lengthy administration [207]. As a result, more attention should be paid to the degradation of Se NPs after long-term administration in order to confirm the safety of Se NPs for clinical applications. As a result, developing functional Se NPs with excellent biocompatibility and degradation qualities will be the most crucial challenges for prospective biomedical studies of Se NPs against pathogens. An even more significant problem for forthcoming Se NP investigation would be to examine their anti-infectious mechanistic pathways, particularly their impacts and mechanistic pathways on innate and adaptive immunity [208]. The decisive elimination impacts of Se NPs against pathogenic strains are the most extensively researched aspects of their prospective anti-infection uses. Nevertheless, as it is well established, among the most major concerns in contagious diseases is the response of immune cells to infection management. Selenium's immunity-regulating activities are presumed to be strongly linked to selenoproteins, which play essential roles in both metabolic activities and the immune function. Notwithstanding, it remains to be seen how selenium from Se NPs directly impacts immune function by controlling selenoprotein action. Furthermore, Se NPs, in our opinion, may have a significant impact on phagocyte activities that will further control immune function. As a result, it is critical to analyze the influence of Se NPs on phagocyte functions when used for the treatment of contagious pathogens, as they may also stimulate anti-infection body's immune system for infection prevention and control.

Conclusion
The parasite Toxoplasma gondii (T. gondii) is thought to infect one-third of the world's population. Tuberculosis (TB) is a major cause of morbidity and mortality globally, despite considerable efforts to eradicate it. It usually does not cause serious sickness in healthy adults, but it causes severe infections in immunocompromised patients. When these two illnesses are linked in people, the effect is frequently life-threatening to the public's health. A number of research studies on the association between M. tuberculosis and T. gondii infections in a specific region of China, Egypt, and Cameroon reveals that there is a strong link between M. tuberculosis and T. gondii infections with each infection having a reciprocal impact on the other. Toxoplasma co-infection may worsen the severity of pulmonary tuberculosis, and TB may contribute to the reactivation of a latent toxoplasmosis or increase susceptibility to a new infection.
To better understand the effects of these coupled illnesses on their outcomes, more research is needed. Because of the significant risk of toxoplasma infection in TB patients, we recommend toxoplasmosis screening. Because of its high bioavailability, low toxicity, low cost, and antimicrobial potential, the nanoform of selenium has been proven to be extremely effective by several studies in the treatment of toxoplasma gondii and tuberculosis. Selenium is an important functional element that affects the production and reproductive properties of organisms by interfering with many physiological mechanisms via selenoproteins. It is possible to fully prevent health problems created by selenium deficiency by including a sufficient supply of selenium in the diet. With the reported therapeutic potency against Toxoplasma gondii and tuberculosis, the number of studies on this aspect are limited, even to the point where there are no studies on the use of selenium nanoparticles to remedy the co-Infections of Toxoplasma gondii and tuberculosis. The research works reviewed in this study have shown that the deliberate use of selenium NPs for direct delivery on the cellular membranes of infectious pathogens interferes with essential biological pathways that can formulate distinct therapeutic mechanisms. If the problems connected with the use of selenium nanoparticles in treating toxoplasma gondii and tuberculosis can be overcome, its use in clinical medicine will be a major breakthrough in the coming future.  (3)