CD36 aggravates ferroptosis in NK cells and dampens their anti-fibrotic activity in the liver

Liver fibrosis is a major global health challenge, and it is an independent risk factor for the development of hepatocellular carcinoma (HCC). Several methods have been explored to improve liver fibrosis progression, but effective preventive and therapeutic strategies remain limited. Natural killer (NK) cells can limit the activation of hepatic stellate cells (HSCs), but they have exhibited impaired antifibrotic properties in liver fibrosis, and the underlying mechanisms are not well understood. In this study, we found that CD36 was markedly upregulated in NK cells from mice with liver fibrosis. The CD36 expression was negatively correlated with activation markers of NK cells. The CD36^- NK cells exhibited elevated cytotoxic cytokine production and enhanced antifibrotic activity against HSCs. The adoptive transfer of CD36^- NK cells alleviated liver fibrosis progression. Mechanistically, CD36 induced reactive oxygen species (ROS) and lipid peroxidation. These consequently triggered ferroptosis in NK cells. The blockage of CD36 or inhibition of ferroptosis in NK cells effectively restored their antifibrotic properties against HSCs. In summary, our findings demonstrated that the antifibrotic properties of NK cells were regulated by CD36. These results provide evidence that targeting CD36 could restore NK cell function for liver fibrosis immunotherapy.