Pankreas associated protein

Pancreatitis-associated protein I (PAP) is a 16 kDa secretory stress protein that was first characterized in the pancreas during pancreatitis, but is also expressed in various tissues including liver, stomach, and colon cancer. Pancreatitis-associated protein-1 (PAP-1) expression serves as a marker for pancreatitis. The protein is elevated in the serum of patients with active inflammatory bowel disease (IBD) and its levels appear to be correlated with disease activity (Nunes Tet al. 2014). Furthermore, it is found elevated in the blood of newborns with cystic fibrosis and serves as a screening test.

PAP is structurally related to the C-type lectins. A classical lectin-related function has not yet been found. It has been shown that PAP expression in some tissues can be activated constitutively or in an injury- and inflammation-induced manner. Furthermore, PAP has been shown to act as an anti-inflammatory factor in vitro and in vivo.

Thus, PAP expression can be induced by various pro- and anti-inflammatory cytokines and by itself through a JAK/STAT3-dependent pathway. PAP is able to activate the expression of the anti-inflammatory factor SOCS3 via the JAK/STAT3-dependent pathway. The JAK/STAT3/SOCS3 pathway appears to be a common point between PAP and various cytokines. Yu JH et al (2019) postulate that PAP-1 inhibits cerulein-induced apoptosis in response to NADPH oxidase-mediated NF-κB activation in pancreatic acinar cells. PAP can modify adhesion and motility of normal and transformed melanocytes, suggesting a possible interaction with melanoma invasiveness (Valery C et al 2001).

PAT is established as a cystic fibrosis screening test. The cutoff is 2.1 µg/l. CF is suspected if PAP is ≥ the 87.5th percentile. If the PAP value is within the normal range, CF can be excluded; if the value is abnormal, affected families are invited to the recall IRT. If the second IRT value is also elevated, sweat testing is performed. For premature infants there are no PAP standard values, therefore they are excluded from the new examination scheme. In children with significantly elevated IRT (>130ng/ml), a sweat test is performed independently of the PAP value (from the 2nd week of life; also possible in adults with suspected CF).

Originally, the "pancreatitis-associated protein" was discovered in the pancreatic juice of rats with acute pancreatitis (Closa D et al.2007).