Inhibition of advanced glycation end-products by the vitamin B6 vitamer pyridoxamine prevents systemic and skeletal muscle diet-induced metaflammation through modulation of S1P/RhoA/ROCK signalling

: The typical western diet contributes to the accumulation of Advanced Glycation End-products (AGEs), reactive compounds involved in metabolic alterations and low-grade inflammation, referred as metaflammation. AGEs affect sphingolipid metabolism increasing sphingosine-1-phosphate (S1P). S1P is in turn induces pro-inflammatory M1 macrophage polarization through activation of RhoA/ROCK. The current study seeks to determine whether inhibition of AGEs by the antiglycating vitamin B6 analog pyridoxamine prevents metaflammation via modulation of S1P/RhoA/ROCK signalling. Gastrocnemius muscle was obtained from mice fed a standard diet (SD) or a western diet (WD), supplemented or not with pyridoxamine (WD+PYR, 150mg/kg bw/day). Metabolic and inflammatory profiles have been investigated in plasma, while accumulation of AGE-modified proteins, expression of RAGE, S1P-synthesizing enzymes and S1P receptors, as well as activation of RhoA/ROCK/IRS-1 pathway have been analysed in gastrocnemius muscle. Markers of local inflammatory cells infiltration and macrophage polarization were also explored. In comparison to SD mice, WD mice developed obesity, glucose intolerance, and muscle lipid accumulation with increased plasma proinflammatory cytokines and muscle M1-polarized macrophage infiltration. WD mice muscle showed higher content of AGE-modified proteins with increased S1P synthesis and S1PR1 expression, paralleled by activation of RhoA/ROCK and impairment of insulin signalling. By inhibiting AGEs production through pyridoxamine supplementation, all the WD-induced metabolic and inflammatory signalling alterations were significantly reversed towards the SD state. The present findings confirm a relevant role for AGE/S1P/RhoA/ROCK signalling in diet-induced metaflammation, suggesting the formulation of pharmacological and nutraceutical tools to prevent AGEs accumulation as a useful strategy against obesity-related metabolic and inflammatory diseases.