Objectives.
Premature activation of the digestive protease trypsin within the pancreatic parenchyma is a critical factor in the pathogenesis of pancreatitis. Alterations in genes that affect intra-pancreatic trypsin activity are associated with chronic pancreatitis (CP). Recently, carboxyl ester lipase (CEL) emerged as a trypsin-independent risk gene. Here, we evaluated PNLIP encoding pancreatic lipase as a potential novel susceptibility gene for CP.
Methods.
We analyzed all 13 PNLIP exons in 429 German non-alcoholic CP patients and in 600 German control subjects, in 632 patients and 957 controls from France, and in 223 patients and 1070 controls from Japan by DNA sequencing. Additionally, we analyzed selected exons in further 545 CP patients and 1849 controls originating from Germany, USA and India. We assessed the cellular secretion, lipase activity and proteolytic stability of recombinant PNLIP variants.
Results.
In the German discovery cohort, 8/429 (1.9%) patients and 2/600 (0.3%) controls carried a PNLIP missense variant (P=0.02, OR=5.7, 95% CI=1.1–38.9). Variants detected in patients were prone to proteolytic degradation by trypsin and chymotrypsin. In the French replication cohort, protease-sensitive variants were also enriched in patients with early-onset CP (5/632 [0.8%]) versus controls (1/957 [0.1%]) (P=0.04, OR=7.6, 95% CI=0.9–172.9). In contrast, we detected no protease-sensitive variants in the non-European populations. In the combined European data, protease-sensitive variants were found in 13/1163 cases (1.1%) and in 3/3000 controls (0.1%) (OR=11.3, 95% CI=3.0–49.9, P<0.0001).
Conclusions.
Our data indicate that protease-sensitive PNLIP variants are novel genetic risk factors for the development of chronic pancreatitis.