Single-cell transcriptomics reveals lipid metabolism reprogramming in macrophages in vitro during early stages of Leishmania donovani infection

Abstract Background Leishmania donovani can cause visceral leishmaniasis, clinically manifested as fever, hepatosplenomegaly, and anemia. If left untreated, it may lead to death owing to complications from other diseases and infections. However, the pathogenesis of L. donovani infection remains unclear. Methods In this study, we utilized single-cell transcriptomic sequencing technology to analyze the transcriptomic landscape of macrophages infected with L. donovani in mice. Results The results showed that the parasite infection rate within macrophages gradually decreased over time. By comparing the transcriptomic profiles of infected cells, bystander cells, and unexposed cells, we identified precise modulation of several key pathways: first, the “ Fabp4 / Cd36 lipid metabolism pathway” is activated during early infection. Significant changes in genes such as Fabp4 are observed in infected cells, suggesting that the parasite hijacks the host lipid metabolic pathway to create a lipid sanctuary. Additionally, as the duration of infection increases, aging-related genes Plk1 , Cenpa , Bub1b , H2afx , and Cdkn2d were activated, suggesting that infection may initiate cellular senescence. Meanwhile, infected cells mediated coordinated immune responses in bystander cells through secretory signals, as evidenced by concurrent expression trends of genes such as Il1rn , Ccl3 , and Hmox1 in both cell types. Further analysis revealed that parasite gene expression levels were significantly higher in M2 macrophages than in M1 macrophages, indicating that an M2-polarized microenvironment is more conducive to intracellular parasite survival. Additionally, parasite gene expression profiling revealed transcriptional remodeling characteristics during the transition from promastigotes to amastigotes, manifested as a significant decrease in the total number of expressed genes over time. Conclusions This study analyzed the host immune response process and the characteristics of parasite–host interactions during L. donovani infection, which may provide a theoretical basis for the development of novel anti-infective treatment strategies in the future. Graphical Abstract