Haptoglobin (Hp), also known as zonulin, is an important member of the peptidase S1 family and a glycoprotein widely present in plasma. The core biological function of Hp is to bind free hemoglobin in plasma: on the one hand, Hp hemoglobin complex can be recognized and broken down by degrading enzymes, achieving the recycling of heme iron; On the other hand, the complex can prevent iron loss through the kidneys and avoid direct damage to the kidneys caused by free hemoglobin. Hp also has antioxidant activity and can eliminate reactive oxygen species in the body; Meanwhile, Hp, as an acute phase response protein, participates in regulating multiple aspects of acute inflammatory response. The glycosylation modification mode of Hp is closely related to the disease status, and there are significant differences in the dominant glycosylation structure of Hp in different diseases: highly fucosylated Hp is dominant in patients with breast cancer and ovarian cancer, the proportion of highly sialylated Hp is increased in patients with Crohn's disease, and highly branched glycosylation structure is dominant in patients with alcoholic liver disease; Among them, fucosylated Hp is a potential serum marker of pancreatic cancer.
