Evaluation of Cytokine Levels in Human Leptospirosis as Prognostic Indicator

Abstract

Purpose: Leptospirosis is a tropical zoonotic illness, in which the role of immune response in the pathogenesis is proven but poorly understood. Response of cytokines is said to play a key role in disease progression and pathogenesis. There are proven studies on pro-inflammatory cytokines like TNFα, IL-6 and anti-inflammatory like IL-10 in human leptospirosis however, the role of IL-2, IL-4, IL-15, GCSF and MCP-2 needs more comprehensive studies. Present study was conducted to evaluate the role of IL-2, IL-4, IL-15, GCSF and MCP-2 in human leptospirosis as prognostic indicator. Methods: Blood samples from patients meeting the inclusion criteria for leptospirosis were included in the study. PCR and IgM ELISA were carried out for diagnosis. Serum cytokine levels in Leptospira positive patients and in controls were estimated by ELISA. Statistical analysis was done using IBM SPSS Statistics 20 and Med Calc 16.1. software. Results: Out of 270, 45(16.7%) patients were confirmed as cases of leptospirosis. The mean level of the cytokines (IL-15, MCP-2, G-CSF) differed significantly between the patients and the control group (p < 0.001). GCSF, MCP-2, IL-15 and IL-4 were elevated in most cases. IL-2 level was depressed in 34 out of 45 cases. The AUCs for IL-2, IL-15, MCP-2 and GCSF were 0.906 (95% CI 0.341 to 0.665), 0.929 (95% CI 0.837 to 0.978), 0.909 (95% CI 0.812-0.966) and 0.881 (95% CI 0.777 to 0.948) respectively. On spearman rank correlation, GCSF level showed correlation with MCP-2 (rho = 0.415, p < 0.01). Conclusions: The study provided an understanding of cytokine patterns in leptospirosis, and concluded that IL-15, MCP-2 and GCSF can be used as an effective biomarker for leptospirosis and indicators of disease progressions.