Interleukin-1β Enhanced Action of Kinins on Extracellular Matrix of Spontaneous Hypertensive Rat Cardiac Fibroblasts

Abstract

Interaction between an enhanced action of kinins and cytokines is accepted as important to the cardioprotective effect of angiotensin-converting-enzyme inhibitors. Kinins mediate their effects through B1 and B2 subtype receptors that may be modulated by cytokines including interleukin (IL)-1beta. We examined expression of kinin receptors and the effects of bradykinin (B2 agonist) and des-Arg10-kallidin (B1 agonist) on extracellular matrix components of adult rat cardiac fibroblasts with or without prior exposure to IL-1beta. We compared responses of cells cultured from spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) hearts. mRNA levels of kinin receptors, procollagens, promatrix metalloproteinases (proMMP-2 and proMMP-9), and tissue inhibitors of metalloproteinase (TIMP-1 and TIMP-2) were all assessed by a semiquantitative RT-PCR. In the absence of IL-1beta, SHR cells expressed more B2 receptor, procollagen alpha1(I), procollagen alpha1(III), and proMMP-9 mRNA than WKY cells. IL-1beta exposure enhanced B1, B2, proMMP-2, and proMMP-9 mRNA in cells of both strains to equivalent levels. Zymographic studies confirmed the results of proMMPs. Following IL-1beta treatment, bradykinin attenuated procollagens alpha1(I) and alpha1(III) mRNA expression in SHR but not WKY cells. In contrast, des-Arg10-kallidin did not show any significant effects in either SHR or WKY cells. Our findings indicate greater extracellular matrix turnover in cultured SHR cardiac fibroblasts than WKY under basal conditions, an IL-1beta stimulation of turnover in cells from both strains, and a strain-differential effect of bradykinin following cytokine treatment. These results imply a genetically determined response of cardiac extracellular matrix and the potential of direct enhancement of the efficacy of kinins by the local release of IL-1beta in hearts genetically programmed to exhibit excessive remodeling to injury.

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“…Stimulation of these receptors influences proliferation and protein synthesis directly and indirectly (via nitric oxide or prostacyclin) in various tissues [43]. It is therefore conceivable that bradykinin accumulation in the myocardium inhibits collagen synthesis by interstitial fibroblasts [44]. This idea is in line with increased PCNA positivity of interstitial cells indicating activation of fibroblasts and increased TGF-β expression in the heart of SNX animals compared to sham operated controls [10].…”