•  
  •  
 

Abstract

ABSTRACT

Omega-3 polyunsaturated fatty acids (w-3 FA) have shown to possess anti-inflammatory properties; however, it remains unclear if w-3 FA can provide protection against LPS induced inflammation in hepatic tissue. PURPOSE: To determine the effects of dietary fat on hepatic cytokine gene expression and secretion following LPS stimulation. METHODS: Male C57Bl/6J mice were randomly assigned to one of four diet groups for 32 weeks: low-fat lard (LFL, 10% fat), low-fat fish-oil (LFFO, 10% fat), high-fat lard (HFL, 41% fat), or high-fat fish-oil (HFFO, 41% fat). Hepatic gene expression and release of cytokines were induced by incubating liver tissue (100 mg) with or without LPS (25 mg/mL media) for 20 hours. The cytokines interferon-g (IFN-g), interleukin-1b (IL-1b), IL-6, IL-10, monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor-a (TNF-a) were evaluated. A 2-way factorial ANOVA was performed to identify significant (pRESULTS: In samples without LPS, only IL-1b expression was significantly (p=0.044) greater (2-fold) in high-fat compared to low-fat diets, matching a 2.7-fold higher (p=0.004) IL-1b media concentration. When comparing fat type in samples without LPS, IL-10 and TNF-a expression were 5-fold (p=0.006) and 2-fold higher (p=0.014), respectively, in lard-based diets leading to 1.5-fold (p=0.007) and 2-fold (p=0.014) higher media concentrations compared to fish-oil diets. Following LPS stimulation, MCP-1 and TNF-a mRNA expression were 3-fold (p=0.045) and 71% (p=0.023) higher, respectively, in high-fat when compared to low-fat groups. In contrast to samples without LPS, LPS stimulation increased the mRNA expression of IL-1b such that it was 47% higher (p=0.008) in the low-fat groups when compared to the high-fat groups. When comparing fat type following LPS, expression of IFN-g and TNF-a were 2.3-fold (p=0.033) and 2-fold (p=0.007) lower, respectively, in the fish-oil diets when compared to lard diets. In contrast, IL-6 mRNA expression was 5-fold (p=0.044) higher in fish-oil diets following LPS stimulation. No difference in media concentrations of IFN-g, TNF-a, and IL-6 were observed between diet types. CONCLUSION: The higher basal (untreated LPS samples) cytokine gene expression and secretion of IL-1b in high-fat diets showed that IL-1b response is independent to fat type. In contrast, IFN-g and TNF-a expression were more sensitive to fat type versus amount of fat consumed, exemplified by lower cytokine activities post-LPS stimulation. These results display the protective role of fish-oils against chronic hepatic inflammation associated with obesity.

Share

COinS
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.