Decoding the Clinical Spectrum of Amoebiasis Immune Mechanisms: Cytokine Balance and Multi-Matrix SIgA (Saliva, Urine and Serum) as Prognostic Biomarkers.

Entamoeba histolytica infection exhibits a range of clinical consequences, spanning from asymptomatic carriage to severe symptomatic disease. Despite comprehensive research on symptomatic E. histolytica infection, limited attention has been given to asymptomatic cases, notably in interpreting the immune activation and regulatory pathways that allow parasite sustainability without observable disease. This study aimed to evaluate the participation of pro-inflammatory cytokines [tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ)], anti-inflammatory cytokines (interleukin-10 [IL-10], interleukin-4 [IL-4]) and mucosal antibodies (secretory IgA [SIgA]) in distinguishing sexes, symptomatic and asymptomatic infections and elucidating their role in amoebiasis. Only serum SIgA exhibited significant sex-based differences among all immune parameters, suggesting the impact of sex hormones on the systemic immune regulation rather than the localized immunity. Serum cytokine levels were assessed and statistically evaluated across symptomatic, asymptomatic and control groups. TNF-α and IFN-γ levels were significantly increased in the symptomatic group (p < 0.01), reflecting a robust inflammation associated with tissue destruction and clinical symptoms. Conversely, IL-10 was significantly greater in the asymptomatic group, indicating a protective role in dampening intense inflammation and sustaining parasite persistence without obvious clinical symptoms. IL-4 levels did not differ significantly among groups, suggesting limited involvement of this cytokine in the immunopathology of amoebiasis. Similarly, SIgA concentrations in saliva, urine and serum specimens were consistently heightened in the symptomatic group, indicating mucosal immune promotion. Receiver operating characteristic (ROC) curve analysis demonstrated that cytokine ratios (TNF-α/IL-10, IFN-γ/IL-10) with serum, urinary and salivary SIgA levels showed high discrimination between symptomatic and asymptomatic groups, thereby demonstrating strong prognostic accuracy. These findings emphasize the crucial role of cytokine balance and mucosal antibody reactions in determining the clinical trajectory of E. histolytica infection, highlighting the clinical utility of quantifying these biomarkers for the diagnosis and differentiation of amoebiasis.