Alteration of Apolipoprotein A2 Isoforms is Associated With the Progression of Chronic Pancreatitis

Objectives: Alteration in plasma apolipoprotein A2 isoforms (apoA2-i) has been reported in patients with pancreatic cancer; however, data on apoA2-i in chronic pancreatitis (CP) remain limited. This study aimed to clarify the alteration in apoA2-i in patients with CP, focusing on its association with disease progression. Methods: A total of 165 patients with CP (27 early-stage, 40 compensated-stage, 61 transitional-stage, and 37 decompensated-stage) were enrolled. Plasma concentrations of apoA2-AT and apoA2-ATQ isoforms were measured. The apoA2-i index was calculated as √(ATQ×AT), and an index <59.5 µg/mL was considered positive. ApoA2 processing type was classified as hyper-processing (AT>ATQ) or hypo-processing (AT<ATQ). We assessed the association of the apoA2-i index and apoA2 processing type with clinical characteristics and imaging findings. Results: The apoA2-i index was positive in 86 patients (52.1%), including 33 (38.4%) with the hyper-processing type and 53 (61.6%) with the hypo-processing type. As CP progressed, the proportion of patients with a positive apoA2-i index increased, and the processing type shifted from hyper-processing to hypo-processing. Patients with a positive apoA2-i index had longer disease duration, more advanced disease stages, higher controlling nutritional status scores, and lower serum lipase levels, suggesting worse nutritional status and impaired pancreatic exocrine function. On CT, these patients exhibited thinner pancreatic parenchyma and greater main pancreatic duct dilation. Conclusions: A positive apoA2-i index was associated with CP progression. Further studies are warranted to determine whether it could serve as a surrogate marker for pancreatic exocrine dysfunction.