IL-17A and IFN-α associated with female genital schistosomiasis lesions

Female genital schistosomiasis (FGS) remains an underdiagnosed consequence of Schistosoma haematobium (S. haematobium) infection, with limited understanding of its associated immunological responses. This study investigated the prevalence of FGS-related cervical lesions and their relationship with systemic cytokine profiles, as well as soluble immune activation biomarkers, among women living in endemic areas of Cameroon.

A cross-sectional study was conducted between November-December 2023 and May-June 2024, in two endemic municipalities in Cameroon. Sexually active women were screened for S. haematobium infection using urine filtration microscopy. Cervical examination and digital imaging were performed to document FGS-associated lesions, which were classified into neovascularization (NVA), grainy sandy patches (GS), yellow sandy patches (YS), and rubbery papules (RP). Blood samples were collected and plasma concentrations of cytokines (IFN-α, TNF-α, IL-10, IL-13, IL-17A, IL-33) and soluble immune activation biomarkers (sCD25, sCD163) were quantified using a magnetic Luminex assay.

A total of 218 women agreed to participate in this study, of whom 54 (24.8%) were infected with S. haematobium. Infected women presented significantly higher proportions of FGS (81.5%), NVA (53.7%), GS (42.6%), YS (7.4%), and RP (9.3%) compared with uninfected women (0.61%-13.4%; p ≤ 0.014). Itching and pelvic pain were not associated with the presence of FGS-related cervical lesions. S. haematobium infection was associated with increased plasma levels of IL-17A (p = 0.039). Women with FGS, NVA, and GS lesions exhibited significantly higher IL-17A and IFN-α concentrations (0.0001 ≤ p ≤ 0.039). IL-17A levels strongly correlated positively with NVA (r_s = 0.568, p < 0.0001), while levels of IFN-α correlated with both NVA (r_s = 0.390, p < 0.0001) and GS (r_s = 0.500, p < 0.0001). Interesting, the immune activation biomarker sCD25 negatively and significantly correlated with RP (r_s=-0,228, p = 0,042).

S. haematobium infection is associated with FGS-related cervical lesions, which occur independently of common symptoms such as itching or pelvic pain. Elevated IL-17A and IFN-α levels and their strong correlation with lesion types suggest that these cytokines may play key roles in FGS immunopathogenesis. These findings highlight the need to improve screening strategies by taking into account immunological markers to better detect and manage FGS in endemic areas.