In the different phases of the inflammatory process, the upregulation of PD-1 in the Th1 or Th17 CD4+ T cells leads to the resolution of inflammation, whereas the overexpression of PD-1 in the Th22 or Treg CD4+ T cells amplifies the pro-inflammatory status, which, together with CD8+ T cells, is responsible for the progression from MASLD to NASH [63]. This evidence concerns the gene PDCD1 and metabolic dysfunction-associated steatohepatitis.