Systemic profiles of Strongyloides-specific IgG subclass, cytokine, and chemokine response in an eosinophilic Iranian population infected with Strongyloides stercoralis

Strongyloidiasis, a neglected tropical disease affecting an estimated 300–600 million people worldwide, remains insufficiently characterized in terms of antibody, cytokine, and chemokine responses across different human populations, particularly in Iran. To address this, we profiled these immune mediators in eosinophilic patients with Strongyloides stercoralis infection in southwestern Iran. We evaluated 82 individuals with confirmed S. stercoralis infection and 48 uninfected endemic controls using a newly established in-house ELISA- and bead-based cytokine/chemokine assays. Eighteen patients were reassessed at least six months after albendazole treatment to determine longitudinal changes. Infected individuals exhibited significantly elevated Strongyloides -specific IgG responses compared to endemic healthy controls, with IgG4 and IgG1 as the dominant subclasses, whereas IgG2 responses were minimal. Type 2-associated cytokines, including IL-9, IL-4, IL-5, and IL-13, were also significantly increased in infected individuals. Longitudinal analysis following albendazole treatment showed significant reductions in eosinophil counts, Strongyloides -specific IgG1, IgG2, and IgG4 levels, as well as IL-9 and IL-10 serum concentrations. In contrast, systemic IL-4 concentrations increased after treatment. We recorded a striking increase in CXCL9 in infected subjects, while the majority of Th1- and Th17-associated cytokines, as well as pro-inflammatory chemokines, were either reduced during infection and/or increased after albendazole treatment and parasite clearance. Our findings support a Strongyloides -associated type 2 immune profile during S. stercoralis infection, characterized by enhanced parasite-specific IgG1 and IgG4 responses and altered cytokine and chemokine profiles. Following albendazole treatment and parasite clearance, several infection-associated immune parameters decreased, including eosinophilia, parasite-specific antibody responses, type 2- and type 9-associated cytokine responses, and systemic IL-10 concentrations, with concurrent changes in chemokine profiles.