Opiorphin in burning mouth syndrome patients: a case-control study
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Opiorphin is a pentapeptide isolated from human saliva that suppresses pain from chemically induced inflammation and acute physical pain. Burning mouth syndrome (BMS) is a chronic condition of a burning sensation in the mouth, where no underlying dental or medical cause can be identified. We aimed to measure the level of opiorphin in whole unstimulated (UWS) and stimulated (SWS) saliva of patients with BMS.
Materials and methods
Originally developed and validated LC-MS/MS method was used for opiorphin quantification. Samples were obtained from 29 BMS patients and 29 age- and sex-matched controls.
The average concentration of opiorphin in UWS and SWS in the BMS group was 8.13 ± 6.45 and 5.82 ± 3.59 ng/ml, respectively. Opiorphin in BMS patients’ UWS was significantly higher, compared to the control group (t = 2.5898; p = 0.0122). SWS opiorphin levels were higher, but not significantly, in BMS patients than in controls.
Our results indicate that higher quantities of salivary opiorphin in BMS may be a consequence of chronic pain, but we cannot exclude that they occur as a result of emotional and behavioral imbalances possibly associated with BMS. To our knowledge, this is the first original article measuring opiorphin in a pain disorder.
Opiorphin may be a measurable biomarker for chronic pain, which could help in objectifying otherwise exclusively a subjective experience. Increased opiorphin could serve as a universal objective indicator of painful conditions. Since opiorphin may also reflect emotional and socio-relational imbalances occurring with BMS, it could as well represent a biomarker for BMS. Knowledge on opiorphin’s involvement in pain pathways could contribute to developing new clinical diagnostic methods for BMS.
KeywordsOpiorphin Burning mouth syndrome Saliva Chromatography, Liquid Spectrometry, Mass
We thank Lidija Brkljačić for her assistance with sample processing and LC-MS/MS analysis.
Compliance with ethical standards
Conflict of interest
Author Ivan Salarić declares that he has no conflict of interest. Author Maja Sabalić declares that she has no conflict of interest. Author Ivan Alajbeg declares that he has no conflict of interest.
The work was supported by the Croatian Science Foundation grant no. 3070 (“The role of oxidative stress and opiorphin in temporomandibular disorders,” PI: Assoc. Prof. Iva Alajbeg).
All procedures performed in studies involving human participants were in accordance with the ethical standards of the Institutional Ethical Committee and with the 1964 Helsinki Declaration and its later amendments.
Informed consent was obtained from all individual participants included in the study. All pertaining data (de-identified medical data on study subjects, institutional ethical committee approval, copies of signed informed consent forms, laboratory results) can be obtained from the authors on request.
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