Leishmania infantum triggers lipid peroxidation and non-canonical cell death in macrophages

Leishmania infantum is a causative agent of visceral leishmaniasis and survives as an obligate intracellular parasite within macrophages by modulating host cell death pathways. While preservation of host cell viability is critical for parasite replication, infected macrophages ultimately undergo cell death, although the mechanisms remain unclear. Here, we investigated the nature of L. infantum-induced cell death in murine bone marrow-derived macrophages (BMDMs). Using long-term live-cell imaging, we show that L. infantum induces delayed cell death in lipopolysaccharide (LPS)-primed macrophages. This process occurred independently of Gasdermin D (GSDMD) and was not associated with inflammasome activation, as evidenced by the absence of caspase-1 cleavage and IL-1β secretion. Consistently, GSDMD deficiency did not affect visceral parasite burden or systemic inflammation during L. infantum infections in mice. Combined genetic ablation of key mediators of apoptosis (caspase-8), necroptosis (RIPK3), and inflammasome signaling (caspase-1/11) failed to protect macrophages from L. infantum-induced cell death, indicating that classical lytic and apoptotic pathways were dispensable. Instead, L. infantum-induced non-canonical macrophage death was associated with robust lipid peroxidation, a hallmark of ferroptosis. However, pharmacological inhibition of lipid peroxidation using ferrostatin-1 did not rescue cell viability, while genetic ablation of the anti-ferroptotic enzyme GPX4 enhanced lipid peroxidation without further sensitizing infected macrophages to death. These findings suggest that L. infantum is capable of uncoupling lipid peroxidation from cell death in macrophages. Together, our results reveal that L. infantum induces lipid peroxidation without triggering ferroptosis and instead drives a non-canonical form of macrophage death independent of major known pathways.