Elevated IL-10 serum levels are associated with slower serological response following syphilis treatment during pregnancy

BackgroundApproximately 50% of pregnant individuals treated for syphilis do not achieve a decline in non-treponemal titers by delivery. The serological response in pregnant persons is significantly slower compared to non-pregnant individuals, with unclear pathogenesis and clinical significance. This study aimed to determine the association between the host immune response and serological outcome in pregnant individuals with syphilis.MethodsTwenty-four females with early syphilis, including 14 pregnant individuals, were included. Pro-inflammatory and regulatory cytokines (IFN-γ, TNF-α, IL-4, IL-1β, IL-10, TGF-β) were measured before treatment and 6 months after penicillin injection.ResultsThe median time to serological cure was 5 months for pregnant individuals and 2 months for non-pregnant females. Pregnant individuals had significantly higher serum levels of IL-10 and TGF-β at baseline and at 6 months post-treatment compared to non-pregnant individuals (<i>p</i> < .05).ConclusionsA robust regulatory immune response to syphilis may be associated with a slower serological response to therapy during pregnancy.