Butyric acid alleviated chronic intermittent hypoxia-induced lipid formation and inflammation through up-regulating HuR expression and inactivating AMPK pathways.

Miaoshang Su,Jueke Yu,Manhuan Xu,Nan Huang,Xikai Ren,Sichen Xue,Rukkaiya Abdullahi,Yifan He

doi:10.1042/bsr20203639

Abstract

To investigate whether butyric acid could alleviate chronic intermittent hypoxia (CIH)-induced lipid formation in human preadipocytes-subcutaneous (HPA-s) through accumulation of human antigen R (HuR) and inactivation of AMP-activated protein kinase (AMPK) pathway, HPA-s were obtained and divided into three groups: Control group: cells were cultured under normal conditions; CIH group: cells were cultured in a three-gas incubator (10% O2); Butyric acid group: 10 mmol/l butyric acid added into cell culture medium. HuR-siRNA was futher transfected into CIH group for verification the function of HuR. Oil Red O was implemented for observation of lipid droplets within cells. Cell Counting Kit-8 (CCK8) assay was used for detecting cell viability. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-nick end labeling (TUNEL) assay as well as flow cytometry analysis was employed for determining cell apoptosis. Western blotting was used for measurement of protein expression levels. RT-qPCR analysis was used for detecting mRNA expression. CIH treatment increased adipocytes proliferation, while butyric acid inhibited cell proliferation and promoted cell apoptosis. The treatment of butyric acid in CIH group down-regulated expression of inflammatory factors and increased cell apoptotic rate. Butyric acid treatment increased HuR expression in both cytoplasm and nucleus and decreased the level of p-AMPK and p-ACC, while transfection of AMPK activator or HuR-siRNA would down-regulate HuR expression. Moreover, butyric acid alleviated CIH-induced cell proliferation, lipid formation and inflammatory status and promoted cell apoptosis through regulating related genes including p21, PPARγ, C/EBPa, IL-1β, IL-6, TLR4, caspase-8 and caspase-3. In conclusion, butyric acid could alleviate CIH-induced inflammation, cell proliferation and lipid formation through accumulation of HuR and inactivation of AMPK pathway.

Highlights

Butyric acid, as one of saturated short-chain fatty acids, which is the main component of fats in the foods and lipids, affords health benefits against lipid disorders [1]
For determining the appropriate concentration of butyric acid, 1, 2.5, 5 and 10 mmol/l of butyric acid were added into adipocytes, after which cells were cultured at 37◦C in a 5% CO2 incubator for 24 h
These results suggested that hypoxia treatment had no significant effect on apoptosis and could promote the proliferation of adipocyte, while butyric acid treatment would induce adipocyte apoptosis and suppress cell proliferation

Summary

Introduction

As one of saturated short-chain fatty acids, which is the main component of fats in the foods and lipids, affords health benefits against lipid disorders [1]. Obesity, a systemic inflammatory disease, characterized by excessive lipid storage in adipose tissue, has been an increasingly significant public health problem [2,3]. People suffering from obesity have a higher prevalence of metabolic disorders such as cardiovascular disease, diabetes and some types of cancer [4]. Indicated that children with obesity had a shorter sleep time and a higher incidence of obstructive sleep apnea [5], which leads to chronic intermittent hypoxia (CIH). Recent evidence suggests that butyric acid is beneficial to the lipid disorders [6] and exerts a dramatic hypotensive effect at a dose [7]. Little attention has been paid to the mechanism of inhibiting lipogenesis by butyric acid

Methods

Results

Conclusion