The potential HLA Class I-restricted epitopes derived from LeIF and TSA of Leishmania donovani evoke anti-leishmania CD8+ T lymphocyte response.

To explore new protective measure against visceral leishmaniasis, reverse vaccinology approach was employed to identify key immunogenic regions which can mediate long-term immunity. In-depth computational analysis revealed nine promiscuous epitopes which can possibly be presented by 46 human leukocyte antigen, thereby broadening the worldwide population up to 94.16%. This is of reasonable significance that most of the epitopes shared 100% sequence homology with other Leishmania species and could evoke a common pattern of protective immune response. Transporter associated with antigen processing binding affinity, molecular docking approach followed by dynamics simulation and human leukocyte antigen stabilization assay suggested that the best five optimal set of epitopes bind in between α1 and α2 binding groove with sufficient affinity and stability which allows the translocation of intact epitope to the cell surface. Fascinatingly, the human leukocyte antigen stabilization assay exhibited a modest correlation with the positive immunogenicity score predicted by class I pMHC immunogenicity predictor. A support for this notion came from ELISA and FACS analysis where the epitopes as a cocktail induced CD8+ IFN-γ and Granzyme B levels significantly in treated visceral leishmaniasis subject which suggests the immunogenic ability of the selected epitopes.

Cytokines and chemokines differentially regulate innate immune cell trafficking during post kala-azar dermal leishmaniasis.

Post kala-azar dermal leishmaniasis (PKDL) is often considered to be the anthroponotic reservoir of visceral leishmaniasis (VL) in India. A better understanding of the host immune-response in dermal lesions of PKDL patients is therefore of utmost significance to minimize such patients and to restrict VL transmission. Although the innate immune response is known to play an important role in parasite clearance from dermal lesions, the actual contribution of innate cells to the pathogenicity of PKDL is poorly understood. The present study explored the immune-pathogenesis of PKDL patients to understand the expression of CD62L, CD11b, CXCL8/IL-8, and MIP1-α and their contribution in signaling during innate cell trafficking. Twenty-five individuals were enrolled, who comprised eight active and untreated macular cases, seven active and untreated cases with papulo-nodular PKDL manifestations, five successfully treated post PKDL cases and five healthy individuals from a non-endemic region of Bihar, India. The immunological investigation was performed on biopsy specimens prepared with a disaggregation technique and blood samples. We observed that the PMNs in nodular patients displayed decreased L-selectin (CD62L) levels and increased integrin (CD11b) expression compared with those in macular patients. Further analysis showed that lower PMN extravasation in macular patients occurred because of inadequate CXCL8/ IL-8 release. In summary, Leishmania donovani (L. donovani) infection in macular PKDL patients decreased leucocyte rolling (L-selectin shedding) and induced up-regulation of the cellular signaling factors involved in pathogenesis (ERK1/2) as well as down regulated the signaling elements (p38 MAPK) involved in the Th1 response, especially in PMNs.

Identification of Clinical Immunological Determinants in Asymptomatic VL and Post Kala-azar Dermal Leishmaniasis Patients.

BACKGROUND: Visceral Leishmaniasis (VL) caused by protozoa belonging to the genus Leishmania, usually have anthroponotic mode of transmission and is issue of great public health importance in Indian subcontinent. Asymptomatic cases of VL and PKDL are subject of keen interest to find their role in the transmission of VL in epidemic areas. We evaluated the immunological cytokine determinants expressed in most clinical suspects of asymptomatic VL and PKDL (IL-10, IFN-γ, and TNF-α). METHODS: Eighty-four participants were included at RMRIMS, Patna, India in 2016-17 out of which 64 asymptomatic individual positive for rK-39, without sign and symptoms of VL; 15 PKDL patient's with past history of VL and 5 endemic healthy subjects were recruited from VL endemic areas. DAT and quantitative assessment of plasma cytokines was determined from the blood samples collected in a plain and sodium-EDTA vacutainer respectively from the subjects. RESULTS: The mean level of IL-10 in DATpos LOW of asymptomatic VL and PKDL was significantly higher than endemic healthy (P<0.05). The cytokine polarization index (IFN-γ versus IL-10) was significantly low in PKDL cases compared with asymptomatic VL cases in DATpos LOW titre (P<0.05). This index was low again but statistically not significant in PKDL than in asymptomatic VL when TNF-α was considered against IL-10. The ratio of IFN-γ: IL-10 and TNF-α: IL-10 was observed decreased both in asymptomatic VL and PKDL cases than in healthy from endemic areas. CONCLUSION: Collectively we surmise from our data that asymptomatic VL can also play an important role like PKDL in transmission of VL.