Unraveling the Immune Response Dynamics of Leishmaniasis: Insights, Challenges, and Vaccine Development

Leishmaniasis, caused by Leishmania parasites transmitted through sandfly bites, encompasses various clinical forms with distinct immune responses. Mucocutaneous leishmaniasis (ML) exhibits a delicate balance between IFN-γ and IL-10, influencing disease severity. Conversely, cutaneous leishmaniasis (CL) presents varied IFN-γ/IL-10 ratios, affecting prognosis. Leishmania RNA virus 1 (LRV1) and extracellular vesicles modulate ML immunity. In visceral leishmaniasis (VL), severe immune defects necessitate combined host immunity and drug treatment for cure. Cytokines and chemokines serve as diagnostic and prognostic markers in CL. Neutrophils' dual role in leishmaniasis pathogenesis is extensively studied, alongside the NLRP3 inflammasome's regulation of Th1/Th2 responses. Live attenuated LdCen-/- parasites offer promising VL vaccine candidates, with biomarkers like miR-21 aiding efficacy assessment. Neutrophil-DC interactions play pivotal roles in vaccine-induced immunity. Genetically modified live attenuated vaccines and novel formulations elicit robust cellular responses against VL. Understanding cytokine networks is crucial for treatment strategy development. Ongoing research strives to overcome vaccine development challenges and ensure long-term protection against leishmaniasis.