2. Leveraging the liver tolerance-teaching mechanism. The liver has specialized cells that present self-antigens to T cells and teach them to tolerate those molecules as "self" rather than attack them (Figure ). The inverse vaccine couples the target autoimmune antigen with a molecule, N-acetylgalactosamine (pGal), that the liver recognizes as "safe", tricking the tolerance-teaching liver cells into reprogramming T cells to leave that antigen alone. Figure . The liver is a potential ultimate regular pathway for immune tolerance. Vaccine is represented as being delivered through lipid nanoparticles (LNP), even though other delivery modes can be employed. (Created with BioRender.com) A phenomenon known as peripheral immune tolerance, which is carried out in the liver, ensures that immune reactions do not take place in response to every damaged cell in the body. It has been discovered that tagging molecules with a sugar known as N-acetylgalactosamine (pGal) could mimic this process, sending the molecules to the liver where tolerance to them has been acquired. Attaching pGal to any molecule would teach the immune system to tolerate it. This way, researchers have developed an approach that can reverse autoimmune diseases by "erasing" the immune system memory of the molecule it mistakenly attacks, rather than broadly silencing the immune system.