Associations between intra-pancreatic fat deposition and circulating levels of cytokines

Abstract

While a plethora of studies have been conducted to investigate the associations between pro-inflammatory cytokines and obesity, the inter-relationship between pro-inflammatory cytokines and intra-pancreatic fat deposition (IPFD) has been poorly investigated. In the present study, circulating levels of C-C motif chemokine ligand 2 (CCL2), interleukin-6 (IL-6), leptin, and tumor necrosis factor-alpha (TNFα) were measured in 90 individuals after acute pancreatitis (AP) as well as 21 healthy non-obese individuals. Magnetic resonance imaging was used to quantify IPFD and visceral-to-subcutaneous fat volume ratio by two independent raters. Linear regression analyses were performed to investigate the associations between IPFD and each cytokine, adjusting for demographic, metabolic, and pancreatitis-related factors, as well as abdominal fat distribution. In healthy non-obese individuals, IPFD was not significantly associated with any of the studied cytokines in both the unadjusted and adjusted models. In individuals after AP, IPFD was significantly associated with leptin in the models adjusted for age and sex (β = 0.063 [95% confidence interval: 0.007, 0.119], P = 0.026); age, sex, visceral-to-subcutaneous fat volume ratio, glycated hemoglobin, and pancreatitis-related factors (β = 0.056 [95% confidence interval: 0.000, 0.111], P = 0.049). Also, IPFD was significantly associated with TNFα in the unadjusted model (β = 0.102 [95% confidence interval: 0.002, 0.202], P = 0.045) and the model adjusted for age, sex, visceral-to-subcutaneous fat volume ratio, glycated hemoglobin, and pancreatitis-related factors (β = 0.128 [95% confidence interval: 0.034, 0.223], P = 0.008). The associations between IPFD and IL-6, CCL2 were not statistically significant, in both the unadjusted and adjusted models. These findings indicate that leptin and TNFα are associated with IPFD independent of abdominal fat distribution and other covariates in individuals after AP. The role of IPFD in low-grade inflammation warrants further investigations.

Keywords: Abdominal fat distribution; C-C motif chemokine ligand 2; Interleukin-6; Intra-pancreatic fat; Leptin; Tumor necrosis factor-alpha.