T helper (CD4+ T) cells can be activated by several self-produced components and are involved in autoimmune diseases.19,20 Dysfunctions of CD4+ T cells guided by antigen-processing cells and/or an inflammatory microenvironment contribute to liver inflammation, fibrosis and fatty liver disease.21 Therefore, it is possible that CD4+ T cells are activated by self-produced sCOL II during arthropathy and then cause liver disease. This evidence concerns the gene CD4 and fatty liver disease.