Inflammatory signaling in skeletal muscle insulin resistance: green signal for nutritional intervention?
OBJECTIVE
To review the evidence implying a role of inflammatory signaling pathways, specifically nuclear factor-κB and c-Jun NH2-terminal kinase, in fatty acid-induced skeletal muscle insulin resistance and to discuss the potential of dietary interventions to interfere with these processes.


RESULTS
Fatty acids can induce skeletal muscle insulin resistance via inflammatory signaling after binding Toll-like receptors at the cell membrane of muscle cells or after accumulating as intramyocellular lipid metabolites. In both processes, activation of intracellular inflammatory signaling is involved. The majority of literature addressing the causality of muscle nuclear factor-κB activation in skeletal muscle insulin resistance suggests that insulin resistance does not require muscle nuclear factor-κB activation. Recently, strong evidence was given that c-Jun NH2-terminal kinase signaling is an important inflammatory pathway involved in skeletal muscle insulin resistance. Furthermore, it is well established that proinflammatory cytokines originating from the enlarged adipose tissue or from activated adipose tissue macrophages can cause muscle insulin resistance. Recently, also macrophages resided in the muscle have been proposed to play an important role in muscle insulin resistance. Because of their anti-inflammatory characteristics, several dietary components like polyphenols may be interesting candidates for manipulating skeletal muscle insulin resistance.


CONCLUSIONS
Several dietary components, like polyphenols, have been reported to interfere with inflammatory signaling. To test whether these compounds can be used to prevent or reverse insulin resistance, well controlled human intervention studies have to be designed.
Hommelberg
Pascal P H
PP
Department of Human Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
Langen
Ramon C J
RC
Schols
Annemie M W J
AM
Mensink
Ronald P
RP
Plat
Jogchum
J
D000273:Adipose Tissue / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D016207:Cytokines / Q000378:metabolism*; D004041:Dietary Fats / Q000009:adverse effects; D005227:Fatty Acids / Q000009:adverse effects; D005419:Flavonoids / Q000627:therapeutic use*; D006801:Humans; D007249:Inflammation / Q000178:diet therapy / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D010636:Phenols / Q000627:therapeutic use*; D059808:Polyphenols; D015398:Signal Transduction / Q000502:physiology; D051193:Toll-Like Receptors / Q000378:metabolism
D016207:Cytokines; D004041:Dietary Fats; D005227:Fatty Acids; D005419:Flavonoids; D016328:NF-kappa B; D010636:Phenols; D059808:Polyphenols; D051193:Toll-Like Receptors; D048031:JNK Mitogen-Activated Protein Kinases