Free Fatty Acid Species Differentially Modulate the Inflammatory Gene Response in Primary Human Skeletal Myoblasts

Abstract

Age-related loss of skeletal muscle is associated with obesity and inflammation. In animal models, intramuscular fat deposits compromise muscle integrity; however, the relevant fat components that mediate muscular inflammation are not known. Previously, we hypothesized that free fatty acids (FFAs) may directly induce inflammatory gene expression in skeletal muscle cells of obese rats. Here, we examined this hypothesis in primary human skeletal myoblasts (SkMs) using multiplex expression analysis of 39 inflammatory proteins in response to different FFA species. Multiplex mRNA quantification confirmed that the IL6, IL1RA, IL4, LIF, CXCL8, CXCL1, CXCL12 and CCL2 genes were differentially regulated by saturated and unsaturated C16 or C18 FFAs. Fluorescence staining revealed that only saturated C16 and C18 strongly interfere with myoblast replication independent of desmin expression, mitochondrial abundance and oxidative activity. Furthermore, we addressed the possible implications of 71 human receptor tyrosine kinases (RTKs) in FFA-mediated effects. Phosphorylated EphB6 and TNK2 were associated with impaired myoblast replication by saturated C16 and C18 FFAs. Our data suggest that abundant FFA species in human skeletal muscle tissue may play a decisive role in the progression of sarcopenic obesity by affecting inflammatory signals or myoblast replication.

Fibroblast Growth Factor 19 Improves LPS-Induced Lipid Disorder and Organ Injury by Regulating Metabolomic Characteristics in Mice

“…We suspected that LPS-induced LA metabolism disturbance is earlier than organ injury. Accumulated evidences indicated that USFA are substrates for the synthesis of multiple molecules that are active in inflammatory response [45][46][47][48]. Decreased Omega 6/Omega 3 FAs were proved to attenuate ethanol-induced liver injury [49].…”

Unsaturated Long-Chain Fatty Acids Activate Resident Macrophages and Stem Cells in a Human Skeletal Muscle Tissue Model

“…The remaining blocks were separately embedded in 1% ultrapure polysaccharide polymer low-melt agarose (Carl Roth GmbH, Karlsruhe, Germany) medium containing DMEM (Biological industries, Kibbutz Beit-Haemek, Israel), 10% fetal bovine serum (PAN Biotech GmbH, Aidenbach, Germany), 100 U/mL of penicillin, and 100 U/mL of streptomycin (PAN Biotech GmbH, Aidenbach, Germany), respectively. For stimulation, analytical-grade fatty acids C16[1]c, C18[2]c, C16, and C18 (all from Biotrend Chemikalien GmbH, Cologne, Germany, numbered as #1208, #1024, #1014, and #1020, respectively) were conjugated with bovine serum albumin (BSA) at a 1:2.5 ratio, as previously described [ 12 ]. C18[2]c solution was introduced to the agarose medium at a final concentration of 50 μm.…”

“…This results in the release of free fatty acids (FAs) that can differentially cause local inflammation [ 11 ]. Previously, we reported that saturated and unsaturated long-chain FAs (C16 or C18) differentially activate the expression of multiple cytokine/chemokine genes in human primary skeletal muscle myoblasts [ 12 ]. Previous in vitro experiments have demonstrated that FAs are important metabolic mediators of macrophage activation [ 13 ].…”

In Vitro Model of Human Skeletal Muscle Tissue for the Study of Resident Macrophages and Stem Cells

“…Obesity increases the risk of age-related decline in muscle mass, suggesting a direct link between the excessive accumulation of fat and fatty acids in muscle tissue and muscle degeneration [ 10 , 11 , 12 ]. Animal studies demonstrated that specific species of fatty acids can directly induce inflammatory gene expression in the skeletal muscle tissue of obese rats [ 11 ].…”

“…Obesity increases the risk of age-related decline in muscle mass, suggesting a direct link between the excessive accumulation of fat and fatty acids in muscle tissue and muscle degeneration [ 10 , 11 , 12 ]. Animal studies demonstrated that specific species of fatty acids can directly induce inflammatory gene expression in the skeletal muscle tissue of obese rats [ 11 ]. Recently, we reported that 18-carbon fatty acid with two unsaturated double bonds in cis configuration (C18[2]c) modulates the expression of eight chemokine genes (IL6, IL1RA, IL4, LIF, CXCL8, CXCL1, CXCL12, and CCL2) in primary human skeletal muscle myoblasts [ 13 ].…”