Overexpression of Il6 leads to hyperinsulinaemia, liver inflammation and reduced body weight in mice

• AIMS/HYPOTHESIS: IL-6 is released by the adipose tissue and increased circulating levels in obesity are associated with hyperinsulinaemia and insulin resistance. Short-term experiments suggest that increased IL-6 release by the skeletal muscle following exercise may improve insulin sensitivity. METHODS: In order to examine the effect of chronically elevated IL-6 levels, we overexpressed Il6 in skeletal muscle in mice using an electro-transfer procedure. RESULTS: Circulating IL-6 levels were increased and the animals rapidly lost both weight and body fat, but food intake was unchanged, which is consistent with the finding that IL-6 increased energy expenditure. Insulin levels were inappropriately elevated and combined with hypoglycaemia in spite of reduced 2-deoxy-D: -glucose uptake by skeletal muscle. Insulin-stimulated glucose uptake by skeletal muscles ex vivo was reduced, probably due to the decreased amounts of glucose transporter (GLUT)-4. Beta cell insulin content was increased, while apparent beta cell mass was unchanged. Circulating serum amyloid A cluster levels were increased tenfold due to a pronounced proinflammatory state in the liver with infiltration of inflammatory cells. However, no liver steatosis was found, which may be accounted for by concomitant AMP kinase activation. CONCLUSIONS/INTERPRETATION: Chronically elevated IL-6 levels lead to inappropriate hyperinsulinaemia, reduced body weight, impaired insulin-stimulated glucose uptake by the skeletal muscles and marked inflammation in the liver. Thus, the pleiotrophic effects of chronically elevated IL-6 levels preclude any obvious usefulness in treating obesity or its associated metabolic complications in man, despite the fact that weight reduction may be expected.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Endokrinologi och diabetes (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Endocrinology and Diabetes (hsv//eng)

Nyckelord

Adenylate Kinase/metabolism

Adipose Tissue/physiology

Animals

Body Weight/genetics

Chimera

Cytomegalovirus/genetics

Deoxyglucose/pharmacokinetics

Gene Expression/immunology

Glucose/metabolism

Glucose Transporter Type 4/metabolism

Hepatitis/*genetics/immunology/*physiopathology

Hyperinsulinism/*genetics/immunology/*physiopathology

Insulin Resistance/genetics/immunology

Interleukin-6/blood/*genetics

Mice

Mice

Inbred C57BL

Mice

Mutant Strains

Muscle

Skeletal/physiology

Phosphorylation

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