FABP4-dependent fatty acid oxidation-fueled mitochondrial ROS induces the mobilization of cellular iron and facilitates Trypanosoma cruzi proliferation in murine adipocytes.

Fatty acid-binding protein 4 (FABP4) is a cytosolic lipid chaperone predominantly expressed in adipocytes. It has been shown that Trypanosoma cruzi targets adipose tissues and resides in adipocytes. However, how T. cruzi manipulates adipocytes to redirect nutrients for its benefit remains unknown. Here, we uncover the role of FABP4 in facilitating T. cruzi infection in murine 3T3-L1 adipocytes. We demonstrate that pharmacological or genetic inhibition of FABP4, carnitine palmitoyltransferase I (CPT-1), or fatty acid oxidation (FAO) abrogates the intracellular growth of T. cruzi in adipocytes. We also found that inhibiting FABP4, CPT-1, or FAO eliminates the infection-induced elevation of mitochondrial and cellular reactive oxygen species (ROS) in adipocytes. Furthermore, T. cruzi infection-induced elevation of ROS in adipocytes increased the cytosolic Fe²⁺, which fueled T. cruzi proliferation. The treatment with antioxidants such as ROS scavenger N-acetyl cysteine (NAC) or mitochondrial ROS inhibitors MitoQ increased the expression level of mRNA for Ferroportin and Ferritin, leading to the decrease in cytosolic Fe²⁺ and the intracellular growth inhibition of T. cruzi in adipocytes. The addition of ferrous sulfate reversed the FABP4 inhibitor or antioxidant-induced decrease in adipocyte parasite burden. Our results demonstrate that T. cruzi exploits host FABP4 to facilitate fatty acid oxidation and elevate cellular ROS, increasing the labile iron pool for the intracellular replication of T. cruzi in adipocytes. These results highlight the therapeutic possibility of host FABP4 as a drug target for T. cruzi infection.IMPORTANCEPersistent infection with a protozoan parasite, Trypanosoma cruzi, causes Chagas disease. While it has been appreciated that adipose tissues are one of the sites of persistent infection, the mechanism of how the parasite survives in adipocytes remains to be established. Our study highlights FABP4, a key regulator of metabolic dysfunction and inflammation, as a therapeutic host target controlling T. cruzi infection in adipocytes. We uncover the importance of FABP4 for T. cruzi replication in mouse adipocytes through engagement with lipid droplet degradation and trafficking of liberated free fatty acids to the host cell's mitochondria, which are utilized for fatty acid oxidation (FAO). T. cruzi infection-induced FAO fuels reactive oxygen species, and the subsequent iron mobilization accelerates parasite replication. These results shed light on the mechanisms of T. cruzi persistent infection in adipocytes, raising the possibility of host FABP4 as a drug target for T. cruzi infection.