CD178

CD178, also known as Fas ligand (FasL) or Tumor necrosis factor ligand superfamily member 6 (TNFSF6), is a transmembrane protein that plays a crucial role in the immune system. It belongs to the TNF superfamily of cytokines. CD178 is primarily expressed on activated T cells, NK cells, and some other immune cells. Its main function is to interact with its receptor, CD95 (also known as Fas or APO-1), which is expressed on a wide range of cell types, including lymphocytes, hepatocytes, and epithelial cells.

The binding of CD178 to CD95 initiates a signaling cascade that leads to apoptosis, or programmed cell death. This mechanism is essential for maintaining immune homeostasis, eliminating autoreactive lymphocytes, and controlling inflammatory responses. For example, during an immune response, activated T cells express CD178 to induce apoptosis in target cells, such as virus-infected cells or tumor cells. It also plays a role in the elimination of activated T cells after the pathogen has been cleared, preventing excessive immune activation.

Dysregulation of the CD178/CD95 pathway has been implicated in various diseases. In some autoimmune diseases, a failure of apoptosis can lead to the accumulation of autoreactive immune cells. Conversely, excessive apoptosis mediated by CD178 can contribute to tissue damage in conditions like hepatitis or inflammatory bowel disease. Furthermore, cancer cells can exploit the CD178/CD95 pathway to evade immune surveillance by inducing apoptosis in tumor-infiltrating lymphocytes. Research into modulating this pathway is ongoing for therapeutic purposes in both autoimmune disorders and cancer.