Interactions of Entamoeba histolytica peroxiredoxin with the TLR4/MD2 complex trigger ferroptosis in host cells

Amoebiasis is a critical global parasitic disease caused by Entamoeba histolytica. It includes amoebic colitis and extraintestinal abscesses. E. histolytica peroxiredoxin (EhPrx) is a crucial antioxidant enzyme that maintains redox homeostasis and participates in counteracting oxidative stress, supporting trophozoite survival and pathogenicity in the host. We observed the EhPrx structure to be a decameric ring formed through the polymerization of five dimers. EhPrx had a unique α-helical structure at its N-terminus. Protein-protein docking and surface plasmon resonance (SPR) assay results suggest that EhPrx may bind to myeloid differentiation factor 2 (MD2), the ligand protein of toll-like receptor 4 (TLR4), rather than directly to TLR4. Furthermore, EhPrx was crucial in the induction of cellular ferroptosis by E. histolytica trophozoites and regulated ferroptosis in host cells through the TLR4/MD2 pathway. These findings may hold a solid structural basis and promising concepts for investigating the pathogenic mechanisms and drug targets of E. histolytica.

Entamoeba histolytica is the causative agent of amoebiasis, a significant global health concern. Within this parasite, E. histolytica peroxiredoxin (EhPrx) plays a pivotal role in mitigating oxidative stress, a critical survival mechanism in the hostile environment of the human host. EhPrx belongs to a family of antioxidant enzymes responsible for detoxifying peroxides, which are deleterious byproducts of cellular metabolism and host-derived immune responses. By neutralizing reactive oxygen species (ROS), EhPrx safeguards the parasite's cellular integrity, ensuring its survival, proliferation, and pathogenicity. Despite its functional importance, the precise structural details of EhPrx remain elusive, hindering a comprehensive understanding of its molecular mechanisms. Cryo-electron microscopy (cryo-EM) offers a promising avenue for elucidating the high-resolution structure of EhPrx, which could reveal critical insights into its biological functions and inter- or intramolecular interactions. Such structural characterization may be indispensable for advancing our knowledge of E. histolytica biology and identifying novel diagnostic markers to combat amoebiasis effectively.