OX40, a costimulatory receptor upregulated upon T-cell activation, has been described to promote cell proliferation, survival, and effector function.30 We found that OX40 is selectively upregulated on intrahepatic CD4+ T cells, but not CD8+ T cells, in MASH and that therapeutic blockade of the OX40L-OX40 axis significantly reduces liver inflammation associated with monocyte-derived macrophages and fibrosis, without affecting steatosis or body weight. The gene discussed is CD8A; the disease is steatosis.