A MOLECULAR AND IMMUNOLOGICAL SIGNATURE OF CD4 + T CELLS IN POST KALA-AZAR DERMAL LEISHMANIASIS

Abstract

Intro: Post kala-azar dermal leishmaniasis (PKDL), which is a late cutaneous manifestation of visceral leishmaniasis (VL), represents an important but largely neglected reservoir of infection and considered as an important source for transmission of the disease. In efforts to eliminate VL, we also need to understand how parasites and immune system interact to reconcile, how disease is controlled and immunity develops in PKDL patients. CD4+ T cells play crucial roles in coordinating immune responses caused by intracellular protozoan parasites such as Leishmania donovani. In this study, we examined transcriptional signature of CD4+ T cells that could distinguish PKDL patients from endemic controls and visceral leishmaniasis (VL) patients. Methods: Blood samples were collected from clinically confirmed PKDL and VL patients as well as healthy endemic control (HEC) individuals to isolate PBMCs and enrich CD4+ T cells. RNA was isolated, libraries were prepared and RNA- sequencing was employed to identify differentially expressed genes (DEGs). Findings: We observed a number of differentially expressed genes (DEGs) unique to PKDL including CD68, IL-13RA, Galectin-2 (LGALS2), Death Receptor- 6/TNFRSF21 (which activates JNK and NF-κβ pathway), CCR1 as well as CXCR1 and CXCR2. NLRP-3 inflammasome as well as skin homing markers CCR4, CCR8 and CCR10 were also differentially up regulated in PKDL While notable downregulated DEGs in CD4+ T cells from PKDL compared to VL patients were LAG3 and IL-10, both with important functional roles in VL. Most importantly, NLRP-3 inflammasome and transcription factors EGR-1/2 distinguished the nodular PKDL from macular PKDL. Conclusion: In summary, CD4+ T cells from PKDL patients have unique gene signatures which differs them from VL patients and HEC. Our results also showed that canonical NLRP3 inflammasome function is not confined to innate immune cells but is operative in adaptive CD4+T cells.