Circulating levels of lipocalin-2 are associated with fatty pancreas but not fatty liver

Abstract

Lipocalin-2 (LCN-2), a peptide with diverse expression pattern, has been identified as a biomarker of various diseases as well as a factor contributing to inflammatory responses associated with excess adiposity and ensuing metabolic disorders. Although the inter-relationship between LCN-2 and excess adiposity is increasingly recognized, little is known about the inter-relationship between LCN-2 and ectopic fat deposition. The present study aimed to investigate the associations between LCN-2 and fatty pancreas as well as fatty liver. In addition, the associations between LCN-2 and pro-inflammatory cytokines were studied. Magnetic resonance imaging was used to quantify intra-pancreatic fat deposition and visceral-to-subcutaneous fat volume ratio whereas magnetic resonance spectroscopy was used to quantify liver fat deposition. Fasting venous blood was analyzed for LCN-2, C-C motif chemokine ligand 2, interleukin-6, leptin, tumor necrosis factor-α, glycated hemoglobin, glucose, and insulin. Binary logistic regression and linear regression analyses were conducted. Three statistical models were built to adjust for demographics, comorbidities, levels of glycated hemoglobin, insulin resistance, and abdominal fat distribution. A total of 79 individuals were studied, of whom 20 had fatty pancreas, 14 had fatty liver, and 4 had both. Lipocalin-2 was significantly associated with fatty pancreas in all the adjusted models (p = 0.014 in the most adjusted model) but was not significantly associated with fatty liver in any of the studied models. Lipocalin-2 was significantly associated with interleukin-6 and tumor necrosis factor-α, in both the unadjusted and adjusted models. Leptin and C-C motif chemokine ligand 2 were not significantly associated with LCN-2 in any of the studied models. These findings suggest that LCN-2 is a potential biomarker of fatty pancreas, independent of abdominal fat distribution, insulin resistance, and other covariates. The role of LCN-2 in intra-pancreatic fat deposition and related low-grade inflammation warrants further investigations.

Keywords: Abdominal fat distribution; Cytokines; Fatty liver; Fatty pancreas; Inflammation; Lipocalin-2.