Interleukin-1α stimulates proinflammatory cytokine expression in human cardiac myofibroblasts

Abstract

Cardiac myofibroblasts (CMF) play a key role in infarct repair and scar formation following myocardial infarction (MI) and are also an important source of proinflammatory cytokines. We postulated that interleukin-1alpha (IL-1alpha), a potential early trigger of acute inflammation post-MI, could stimulate human CMF to express additional proinflammatory cytokines. Furthermore, we hypothesized that these effects may be modulated by the anti-inflammatory cytokine interleukin-10 (IL-10). Human CMF were cultured from atrial biopsies from multiple patients. Interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and cardiotrophin-1 (CT-1) mRNA expression and secretion were measured using quantitative real-time RT-PCR and enzyme-linked immunosorbent assay. IL-1alpha (0.001-10 ng/ml, 0-6 h) stimulated IL-1beta, TNF-alpha, and IL-6 mRNA expression with distinct temporal and concentration profiles, resulting in increased cytokine secretion. The response to IL-1alpha was much greater than with TNF-alpha. Neither IL-1alpha nor TNF-alpha treatment modulated CT-1 mRNA expression. Immunoblotting with phosphospecific antibodies revealed that IL-1alpha stimulated the extracellular signal-regulated kinase (ERK)-1/2, p38 mitogen-activated protein kinase (MAPK), c-Jun NH(2)-terminal kinase (JNK), phosphatidylinositol 3-kinase (PI 3-kinase)/protein kinase B (Akt), and nuclear factor (NF)-kappaB signaling pathways. Pharmacological inhibitor studies indicated roles for PI 3-kinase/Akt and NF-kappaB pathways in mediating IL-1beta expression, and for NF-kappaB and p38 MAPK pathways in mediating TNF-alpha expression. IL-1alpha-induced IL-6 mRNA expression was reduced by p38 MAPK inhibition, but increased by ERK and JNK pathway inhibitors. IL-10 produced a consistent but modest reduction in IL-1alpha-induced IL-6 mRNA levels (not IL-1beta or TNF-alpha), but this was not reflected by reduced IL-6 protein secretion. In conclusion, IL-1alpha stimulates human CMF to express IL-1beta, TNF-alpha, and IL-6 via specific signaling pathways, responses that are unaffected by IL-10 exposure.

Effects of interleukin-1 on cardiac fibroblast function: Relevance to post-myocardial infarction remodelling

“…Using a focused RT-PCR microarray we identified a number of inflammatory adhesion molecules that were also upregulated following IL-1 stimulation, including ICAM-1, VCAM-1, E-selectin and to a lesser extent the integrin β3 subunit and CD44 . Another important myocardial proinflammatory cytokine, TNF, was able to stimulate a similar profile of cytokines, chemokines and adhesion molecules in human CF; however it was consistently less potent than IL-1 (Turner et al, 2007;Turner et al, 2009;Turner et al, 2011). This relative sensitivity of CF to IL-1 is in agreement with previous reports that fibroblasts in the heart are particularly responsive to IL-1 compared with other cytokines, and compared with other sources of fibroblasts (Brown et al, 2005).…”

“…of specific genes in human CF to promote a pro-inflammatory, pro-angiogenic, promigratory, ECM degrading, non-differentiated fibroblast phenotype. Figure summarises results previously published by our group using human CF from multiple patients (Mughal et al, 2009;Turner et al, 2009;Turner et al, 2010;Turner et al, 2011;Maqbool et al, 2013;. See main text for details.…”

“…IL-1/β stimulates all the major canonical kinase signalling cascades in CF (Figure 1), including the ERK, JNK, p38, PI3K/Akt and NFB pathways (Xie et al, 2004;Mitchell et al, 2007;Turner et al, 2009). All of these pathways have also been shown to be activated in the myocardium early after experimental MI; see recent comprehensive reviews on NF-κB (Gordon et al, 2011), p38 (Marber et al, 2011;Turner, 2011), JNK (Turner, 2011), ERK and Akt; the latter being components of the reperfusion injury salvage kinase (RISK) pathway that is considered cardioprotective (Hausenloy et al, 2005).…”

Matrix Metalloproteinases: Drug Targets for Myocardial Infarction

“…In addition to ECM, fibroblasts and myofibroblasts synthesize many other factors relevant to LV remodeling, including interleukin (IL) -1, IL-6, TGF , connective tissue growth factor, tumor necrosis factor (TNF ), angiotensin II, endothelin I, MMPs, and TIMPs [33,[35][36][37][38]. Myofibroblasts, under certain stimuli, activate or express a number of MMP family subtypes, including MMP-1, -2, -9, -13, and membrane type MMP-14 [33].…”

Inflammatory and fibrotic responses of cardiac fibroblasts to myocardial damage associated molecular patterns (DAMPs)

“…IL-1 , IL-6, TNF-) and neutrophilattracting chemokines (e.g. CXCL-1, 2, 5 and 8), and express specific neutrophil-binding adhesion molecules including ICAM-1 and E-selectin [88,[90][91][92][93], as well as the matricellular protein TN-C [94]. Thus, CF may contribute to the inflammatory milieu that occurs in the myocardium early after MI [10,95].…”