Mannose-binding lectin concentrations in people living with HIV/AIDS infected by HHV-8
Mannose-binding lectin (MBL) plays an important role in the innate immune response by activating the complement system via the lectin pathway, and it has been studied in several viral infections; however, the influence of MBL in PLWHA infected with HHV-8 is unknown. The objective of this study was to verify the association of MBL deficient plasma concentrations in HIV/HHV-8 coinfected and HIV monoinfected patients and to correlate these concentrations with HIV viral load and CD4 counts in both groups.
This was an analytical study of case-controls consisting of PLWHA monitored at the medical outpatient of Infectious and Parasitic Diseases of the clinical hospital in the Federal University of Pernambuco. Plasma concentrations of MBL were obtained by an enzyme-linked immunosorbent assay (ELISA) using a commercial Human Mannose Binding Lectin kit (MyBioSource, Inc.) that was performed according to the manufacturer’s guidelines, with values < 100 ng/ml considered deficient. A total of 245 PLWHA samples were analysed; 118 were HIV/HHV-8 coinfected and 127 were HIV monoinfected; 5.1% (6/118) of the coinfected patients and 3.2% (4/127) of the monoinfected patients (p = 0.445) were considered plasma concentration deficient. The median of the plasma concentrations of MBL in the coinfected patients was 2803 log10 ng/ml and was 2.959 log10 ng/ml in the monoinfected patients (p = 0.001). There was an inverse correlation between the plasma concentrations of MBL and the HIV viral load in both groups, but no correlation with the CD4 count.
Although the plasma concentrations considered deficient in MBL were not associated with HHV-8 infection in PLWHA, the coinfected patients showed lower MBL concentrations and an inverse correlation with HIV viral load, suggesting that there may be consumption and reduction of MBL due to opsonization of HIV and HHV-8, leading to the reduction of plasma MBL and non-accumulation in the circulation.
KeywordsHIV/HHV8 coinfection MBL Deficient concentrations Human herpesvirus 8
Enzyme-linked immunosorbent assay
Hepatitis B virus
Hepatitis C virus
Human herpesvirus 2
Human herpesvirus 8
Human T-cell leukemia-lymphoma virus
People living with HIV/AIDS
The incidence of Kaposi’s sarcoma (KS) associated with human herpesvirus 8 (HHV-8) has increased in people living with HIV/AIDS (PLWHA), with a more aggressive clinical course and progression to death [1, 2, 3, 4, 5, 6]. KS is one of the most common cancers in PLWHA, even when the individuals are treated with antiretroviral therapy (ART) and have an undetectable HIV viral load and CD4 + T cell counts that are above 350 cells/mm3 [7, 8, 9].
The control of HHV-8, just as in the early stages of the development of KS, is mediated by the innate and adaptive immunity [10, 11, 12]. In this context, mannose-binding lectin (MBL) plays a key role in innate immunity as a standard recognition receptor, binding with a high affinity to the residue patterns of carbohydrates present on the surface of viruses or virus-infected cells, especially when the humoral immunity is not fully functional, such as in childhood or in immunosuppressed or immunocompromised populations [13, 14, 15]. Thus, MBL contributes to the defence of the innate immune system by initiating the activation of the lectin-complement pathway, which promotes opsonophagocytosis, modulates inflammation and induces cellular lysis [16, 17, 18].
Regarding PLWHA, some studies have shown an association between MBL plasma concentration deficiency and HIV infection or a more rapid disease progression [19, 20, 21, 22, 23], and others found no association with this infection, the HIV viral load or the CD4 count [18, 24]. However, the influence of MBL on HHV-8 infection is not known, but for other herpes viruses, studies suggest that MBL deficiency may be a risk factor for the symptomatic development of human herpesvirus 2 (HHV-2)  and for cytomegalovirus reactivation (CMV) [14, 26]. Although MBL plays an important role in the innate immune response, it is still unknown whether a deficiency in the MBL plasma concentration is associated with HHV-8 infection in PLWHA. In view of the above, the objective of this study was to verify the association of MBL deficient plasma concentrations in HIV/HHV-8 coinfected and HIV monoinfected patients and correlate the concentration with the HIV viral load and CD4 counts in both groups.
We analysed 245 samples from PLWHA, including 118 HIV/HV-8 coinfected patients, with a mean age of 42.5 (± 11.8), and 127 patients monoinfected with HIV, with mean age of 42.8 (± 10.6), and the majority of these patients were males 71% (84/118) and 59% (75/127), respectively. The median TCD4 count was 2.713 log10 cells/mm3 (1.301–3.224) in the coinfected patients and 2.736 log10 cells /mm3 (1.176–3.269) in the monoinfected patients (p = 0.872). The HIV viral load was detectable in 42% (50/118) of the coinfected patients and in 44% (56/127) in the monoinfected patients, with a median of 2.057 log10 copies/ml (1.672–5.539) and 2.363 log10 copies/ml (1.602–6.273), respectively, with p = 0.595.
Median plasma concentrations of MBL according to sex, age, HIV viral load and CD4 count in HIV/HHV-8 coinfected and HIV monoinfected patients
Median of MBL (log10 ng/ml) (range)1
HIV viral load
MBL plays an important role in the innate immune response by activating the complement system via the lectin pathway in an antibody-independent mechanism [15, 17, 23]. This protein has been studied in several infections [26, 27, 28, 29, 30]; however, this is the first study to evaluate the plasma concentrations of functional MBL in PLWHA coinfected with HHV-8 and correlate the concentrations with HIV viral load and CD4 counts.
The study population did not differ in age and sex when compared to other studies evaluating PLWHA infected with HHV-8 [4, 8, 31, 32, 33]. Similarly, the median HIV viral load and TCD4 count did not show a statistically significant difference between the HIV/HHV-8 coinfected and the HIV monoinfected patients, corroborating works that also evaluated these clinical characteristics [31, 32, 34].
It is still unknown how MBL aids in the control or elimination of HHV-8 infection; however, in relation to HIV infection, studies show that MBL binds to HIV gp120 glycoprotein, helping to clear this virus through the activation of the complement system [22, 35, 36, 37, 38]. In addition, when MBL is bound to HIV it can also be eliminated from the circulation by the C1q receptor, which has a structural and functional affinity for MBL [30, 39, 40], suggesting the consumption and reduction of MBL during HIV infection [26, 30].
In relation to the Herpesviridae family there are few studies performed. The data of a research show that MBL modulates the response to HSV-2 in mice by affecting neutralization of the virus. Furthermore, reported that the frequency of the MBL deficient (< 100 ng/ml) was higher in the symptomatic group (people with recurrent HSV-2 infections) . In other research the MBL deficient levels were linked to CMV reactivation after lung transplantation . These authors suggest that lack of MBL mediated complement activation increases susceptibility to infections by these viruses.
Studies use different cut-off points, including < 100, < 300 and < 500 ng/ml, to define MBL deficient plasma concentrations [14, 18, 25, 26, 30]. In our study, we defined deficient concentrations as < 100 ng/ml and found no association with HHV-8 infection in PLWHA, the HIV viral load or the CD4 count; however, the median of these concentrations was significantly lower in the HIV/HHV-8 coinfected patients compared to the HIV monoinfected patients. However, the median concentrations found in both groups were higher than the values considered deficient by these authors [14, 18, 19, 25, 26, 30]. A possible explanation for the lower concentrations of MBL in coinfected patients would be the consumption and reduction of this protein, involving the opsonization of HIV and HHV-8, leading to the reduction of plasma MBL and its non-accumulation in the circulation .
On the other hand, considering the cut-off point established by Manuel et al. (2007) to characterize the deficient plasma concentration of MBL (< 500 ng/ml), in our study, four coinfected patients who developed KS showed a deficient MBL concentration 2.519 log10 ng/ml (data not shown). These same four patients were genetically characterized for the polymorphisms − 550, − 221 and exon 1 of the MBL2 gene in the research conducted by Morais et al. (2018), the authors reported that these coinfected were characterized as intermediate expression haplotypes for the production of the MBL protein, being three HYA/LXA and one LYA/LYO . Because of these results, studies related to MBL plasma concentrations and MBL2 gene polymorphisms become essential and may help to understand the role of MBL in the development of KS in HIV/HHV-8 coinfected patients.
In relation to CD4, the counts above or below 200 cells/mm3 did not influence the MBL plasma concentrations, because the medians remained smaller in the coinfected patients in relation to the monoinfected patients. However, considering the use of a continuous numerical scale, it was possible to establish an inverse correlation between the plasma MBL concentrations and the HIV viral load in the coinfected and monoinfected patients, suggesting that MBL plasma concentrations might also modulate coinfection.
Other factors may influence the MBL concentration, such as polymorphisms in the MBL2 gene, resulting in defects in the polymerization of the molecule, leading to functional deficiency and protein expression and reducing the activation capacity of the complement system [42, 43, 44]. Furthermore, the drugs used in the treatment of infections, such as those of ART [45, 46, 47], are metabolized in the liver and may affect the concentration of MBL because this protein is mainly synthesized in the liver .
Our research has some limitations, such as the absence of investigation of the HHV-8 latent or latent cycle, quantify of the HHV-8 viral load, evaluate functionality of MBL by measuring the activity of MBL in the complement system through C4b binding or measure aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzyme levels in the blood as a measure of liver toxicity. We suggest that future prospective studies evaluate these variables by associating or correlating them with plasma MBL concentrations in HIV/HHV-8 coinfected patients, especially in those who developed KS.
Therefore, although the plasma concentrations considered deficient of MBL were not associated with HHV-8 infection in PLWHA, the coinfected patients had lower concentrations of MBL and an inverse correlation with the HIV viral load, suggesting that MBL might also be modulating HIV/HHV-8 coinfection.
The aim of this study was to verify the association of MBL deficient plasma concentrations in HIV/HHV-8 coinfected and HIV monoinfected patients and correlate the concentration with the HIV viral load and CD4 counts in both groups.
Design and study population
MBL plasma concentrations
The plasma concentrations of MBL were obtained by an enzyme-linked immunosorbent assay (ELISA) using a commercial Human Mannose Binding Lectin kit (MyBioSource, Inc.), with a detection threshold of 0.05 ng/ml. The samples were diluted at 1:100, and the protocol for the ELISA was performed following the manufacturer’s guidelines. The readings were performed on a spectrophotometer (Thermoplate®) with a wavelength of 450/630 nm. The plasma concentrations were considered deficient when they were < 100 ng/ml [18, 19, 25].
To evaluate the deficiency of the concentrations, we used the odds ratios (ORs) and 95% confidence intervals (CIs), and the Mann-Whitney test was used to associate the MBL plasma concentrations in the HIV/HHV-8 coinfected and HIV monoinfected patients. The Spearman test was used to correlate the plasma MBL concentrations with HIV viral load and CD4 count, and these variables were included in the statistical models as units transformed into log10. For the statistical analyses and the construction of the graphs, we used GraphPad Prism software version 6.1 (GraphPad Software, USA) and Epi Info version 7.1.5 (CDC, Atlanta, GA, USA). Statistically significant values were indicated by p < 0.05.
The authors thank all patients and technical support from the Virology Laboratory of the Tropical Medicine Institute (LIM-52-IMT) of the University of São Paulo for the realization of HHV-8 serology. The Fundação de Amparo à Ciência e Tecnologia de Pernambuco (FACEPE) by the support to Viviane Martha Santos de Morais, according BCT-0187-4.01/18.
The authors received no specific funding for this work.
Availability of data and materials
The datasets used and/or analyzed during the current study available from the corresponding author upon reasonable request.
VMSM: designed the study, did the experimental work, analyzed the data statistically, interpretation the data and drafted the manuscript. JPG, GGOMC, TRTM: collected the samples, acquired data or revised the manuscript. MRCDC: obtained the funding and revised the manuscript critically for important intellectual content. All the authors read and approved the final manuscript.
Ethics approval and consent to participate
The study was approved by the Research Ethics Committee of the Federal University of Pernambuco (number: 22428813.5.0000.5208). We declare that this study involved human patients and all patients gave consent to participate in the research, in accordance with the ethical, consent and permission rules of the Research Ethics Committee of the Federal University of Pernambuco.
Consent for publication
This study obtained the consent of the participant to publish the refferent data to each patient.
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
- 2.Sullivan RJ, Pantanowitz L, Casper C, Stebbing J, Dezube BJ. HIV/AIDS: epidemiology, pathophysiology, and treatment of Kaposi sarcoma-associated herpesvirus disease: Kaposi sarcoma, primary effusion lymphoma, and multicentric Castleman disease. Clin Infect Dis. 2008;47:1209–15.CrossRefGoogle Scholar
- 6.Dittmer DP, Damania B. Kaposi sarcoma – associated herpesvirus : immunobiology , oncogenesis , and therapy. 2016;126:3165–3175.Google Scholar
- 16.Auriti C, Prencipe G, Moriondo M, Bersani I, Bertaina C, Mondì V, et al. Mannose-binding lectin: biologic characteristics and role in the susceptibility to infections and ischemia-reperfusion related injury in critically ill neonates. J Immunol Res. 2017.Google Scholar
- 19.Egli A, Schäfer J, Osthoff M, Thiel S, Mikkelsen C, Rauch A, et al. Low levels of Mannan-binding lectin or Ficolins are not associated with an increased risk of cytomegalovirus disease in HIV-infected patients. PLoS One. 2013;8.Google Scholar
- 27.Figueiredo GG, Cezar RD, Freire NM, Teixeira VG, Baptista P, Cordeiro M, et al. Mannose-binding lectin gene (MBL2) polymorphisms related to the mannose-binding lectin low levels are associated to dengue disease severity. Hum Immunol American Society for Histocompatibility and Immunogenetics. 2016;77:571–5.Google Scholar
- 29.Rashidi E, Fazlollahi MR, Zahedifard S, Talebzadeh A, Kazemnejad A, Saghafi S, et al. Mannose-binding lectin deficiency in patients with a history of recurrent infections. Iran J allergy, Asthma Immunol. 2016;15:69–74.Google Scholar
- 40.Malhotra R, Sim RB, Reid KBM. Interaction of C1q, and other proteins containing collagen-like domains, with the C1q receptor. Biochem Soc Trans. 1990;18.Google Scholar
- 41.de Morais VMS, Lima ELS, Cahú GGOM, Lopes TRR, Gonçales JP, et al. MBL2 gene polymorphisms in HHV-8 infection in people living with HIV/AIDS. Retrovirology. 2018;15(75):01–9.Google Scholar
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.