Myocardial knockdown of mRNA‐stabilizing protein HuR attenuates post‐MI inflammatory response and left ventricular dysfunction in IL‐10‐null mice

Abstract

Prolonged inflammatory response is associated with left ventricular (LV) dysfunction and adverse remodeling following myocardial infarction (MI). IL-10 inhibits inflammation by suppressing HuR-mediated mRNA stabilization of proinflammatory cytokines. Here we report that following MI, IL-10(-/-) mice showed exaggerated LV dysfunction, fibrosis, and cardiomyocyte apoptosis. Short-hairpin RNA (shRNA)-mediated knockdown of HuR in the myocardium significantly reversed MI-induced LV dysfunctions and LV remodeling. HuR knockdown significantly reduced MI-induced cardiomyocyte apoptosis concomitant with reduced p53 expression. Moreover, HuR knockdown significantly reduced infarct size and fibrosis area, which in turn was associated with decreased TGF-beta expression. In vitro, stable knockdown of HuR in mouse macrophage cell line RAW 264.7 corroborated in vivo data and revealed reduced mRNA expression of TNF-alpha, TGF-beta, and p53 following LPS challenge, which was associated with a marked reduction in the mRNA stability of these genes. Taken together, our studies suggest that HuR is a direct target of IL-10, and HuR knockdown mimics anti-inflammatory effects of IL-10.

Interleukin-10 overexpression improves the function of endothelial progenitor cells stimulated with TNF-α through the activation of the STAT3 signaling pathway

“…IL-10 is a 35-kDa homodimeric cytokine that is produced by a variety of cell types. IL-10, a potent anti-inflammatory cytokine, attenuates inflammatory response and suppresses various pro-inflammatory mediators (6). Thus, the aim of the present study was to observe the influence of IL-10 overexpression on EPCs and to clarify the possible mechanism.…”

“…The BM was flushed out of the tibias with sterile phosphate-buffered saline (PBS) using a syringe, and MNCs were isolated by Ficoll gradient centrifugation. Following washing twice with PBS, MNCs were seeded on a human fibronectin (FN; Sigma-Aldrich, St. Louis, MO, USA) coated 6-well plate at a density of 5x10 6 cell/well and cultured in endothelial cell growth medium-2 (EGM-2; Lonza, Walkersville, MD, USA) at 37˚C, 5% CO 2 . EGM-2 was changed every two days and non-adherent cells were removed.…”

“…Cells (1x10 6 ) were digested, re-suspended and added to ice-cold methanol for fixation and stored at 4˚C. Samples were warmed to room temperature and rehydrated by rinsing twice in PBS.…”

“…Interleukin-10 (IL-10), a potent anti-inflammatory cytokine, attenuates inflammatory response and suppresses various pro-inflammatory mediators (6)(7)(8). IL-10 plays a role not only in immunoregulation and inhibition of pro-inflammatory cytokine synthesis, but also in directly regulating the growth and survival of noninflammatory cells.…”

Activation of Natural Killer T Cells Ameliorates Postinfarct Cardiac Remodeling and Failure in Mice

“…These findings were consistent with a recent study by Krishnamurthy et al, in which LV dimension and function by echocardiography after MI did not differ between wild-type and IL-10-null mice. 24 …”