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Circ Res. 2009 Nov 20;105(11):1149-58. doi: 10.1161/CIRCRESAHA.109.208199. Epub 2009 Oct 15.

Pressure-mediated hypertrophy and mechanical stretch induces IL-1 release and subsequent IGF-1 generation to maintain compensative hypertrophy by affecting Akt and JNK pathways.

Author information

1
Department of Cardiovascular Medicine, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto, 602-8566 Japan.

Abstract

RATIONALE:

It has been reported that interleukin (IL)-1 is associated with pathological cardiac remodeling and LV dilatation, whereas IL-1beta has also been shown to induce cardiomyocyte hypertrophy. Thus, the role of IL-1 in the heart remains to be determined.

OBJECTIVE:

We studied the role of hypertrophy signal-mediated IL-1beta/insulin-like growth factor (IGF)-1 production in regulating the progression from compensative pressure-mediated hypertrophy to heart failure.

METHODS AND RESULTS:

Pressure overload was performed by aortic banding in IL-1beta-deficient mice. Primarily cultured cardiac fibroblasts (CFs) and cardiac myocytes (CMs) were exposed to cyclic stretch. Heart weight, myocyte size, and left ventricular ejection fraction were significantly lower in IL-1beta-deficient mice (20%, 23% and 27%, respectively) than in the wild type 30 days after aortic banding, whereas interstitial fibrosis was markedly augmented. DNA microarray analysis revealed that IGF-1 mRNA level was markedly (approximately 50%) decreased in the IL-1beta-deficient hypertrophied heart. Stretch of CFs, rather than CMs, abundantly induced the generation of IL-1beta and IGF-1, whereas such IGF-1 induction was markedly decreased in IL-1beta-deficient CFs. IL-1beta released by stretch is at a low level unable to induce IL-6 but sufficient to stimulate IGF-1 production. Promoter analysis showed that stretch-mediated IL-1beta activates JAK/STAT to transcriptionally regulate the IGF-1 gene. IL-1beta deficiency markedly increased c-Jun N-terminal kinase (JNK) and caspase-3 activities and enhanced myocyte apoptosis and fibrosis, whereas replacement of IGF-1 or JNK inhibitor restored them.

CONCLUSIONS:

We demonstrate for the first time that pressure-mediated hypertrophy and mechanical stretch generates a subinflammatory low level of IL-1beta, which constitutively causes IGF-1 production to maintain adaptable compensation hypertrophy and inhibit interstitial fibrosis.

PMID:
19834007
DOI:
10.1161/CIRCRESAHA.109.208199
[Indexed for MEDLINE]

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