Protozoan‐Derived Cytokine‐Transgenic Macrophages Reverse Hepatic Fibrosis

Abstract Macrophage therapy for liver fibrosis is on the cusp of meaningful clinical utility. Due to the heterogeneities of macrophages, it is urgent to develop safer macrophages with a more stable and defined phenotype for the treatment of liver fibrosis. Herein, a new macrophage‐based immunotherapy using macrophages stably expressing a pivotal cytokine from Toxoplasma gondii , a parasite that infects ≈ 2 billion people is developed. It is found that Toxoplasma gondii macrophage migration inhibitory factor‐transgenic macrophage (Mφ ^tgmif ) shows stable fibrinolysis and strong chemotactic capacity. Mφ ^tgmif effectively ameliorates liver fibrosis and deactivates aHSCs by recruiting Ly6C ^hi macrophages via paracrine CCL2 and polarizing them into the restorative Ly6C ^lo macrophage through the secretion of CX3CL1. Remarkably, Mφ ^tgmif exhibits even higher chemotactic potential, lower grade of inflammation, and better therapeutic effects than LPS/IFN‐γ‐treated macrophages, making macrophage‐based immune therapy more efficient and safer. Mechanistically, Tg MIF promotes CCL2 expression by activating the ERK/HMGB1/NF‐κB pathway, and this event is associated with recruiting endogenous macrophages into the fibrosis liver. The findings do not merely identify viable immunotherapy for liver fibrosis but also suggest a therapeutic strategy based on the evolutionarily designed immunomodulator to treat human diseases by modifying the immune microenvironment.