Serum Cytokines and TGF-β1: A Window into Syphilis Among People Living with HIV

Treponema pallidum is the etiological cause of syphilis, and in recent years, reemergence has been reported, especially among men who have sex with men and people living with HIV (PLWH). Certain cytokines may act as hallmark biomarkers in the progression of syphilis in PLWH, and studying how the immune system works against T. pallidum is important, especially in PLWH, whose immune system is compromised. We evaluated the serum expressions of IFN, TNF, IL-10, TGF-β1 and IL-17 in men living with HIV (MLWH) and their association with distinct stages of syphilis. We recruited MLWH from March to October 2022. A blood sample was requested, syphilis was detected using the reverse algorithm, and antibodies were titrated to determine the stage. Each of the cytokines studied was quantified using commercial ELISA kits. The following groups were formed: active syphilis (n = 217), cured syphilis (n = 134), and without syphilis (n = 159). The prevalence of elevated TGF-β1 differed between groups, being highest in individuals with active syphilis (51.6%; median 319 pg/mL), followed by those with cured syphilis (41.0%; median 137.0 pg/mL). Younger participants and persons without a history of sexually transmitted infections were more likely to present with high TGF-β1 levels. TGF-β1 may act as a biomarker in active syphilis and could suppress the inflammatory response against spirochetes.