Nishant Joshi

Abstract Neuronal classification based on morphology, electrophysiology, and molecular markers is often considered static.

Author summary Leishmaniasis, a neglected tropical disease, has limited available treatments and is becoming more resistant to medications. In this study, we explored the therapeutic potential of PF-543, a potent Sphingosine Kinase 1 (SphK1) inhibitor (demonstrated anticancer effects in various preclinical models) against Leishmania donovani. We successfully cloned and purified both Leishmania and human SphK1 proteins and confirmed PF-543 binding through biochemical and biophysical and supporting computational (in silico) analyses. Overexpression of LdSphK1 in parasites enhanced their survival and infectivity. In vitro, PF-543 treatment of infected macrophages decreased amastigote burden, shifted cytokine profiles towards a pro-inflammatory state, and enhanced host cell apoptosis. Notably, PF-543 acted synergistically with Amphotericin B, the current clinical drug, both in vitro and in vivo in Swiss mice, drastically lowering parasite burden. This study identifies SphK1-dependent signalling as a biologically relevant axis at the host–parasite interface and highlight PF-543 as a proof-of-concept dual-acting modulator rather than a parasite-selective drug. This work supports host-directed and combination therapeutic strategies as promising avenues for improving leishmaniasis treatment.