IRAK3 gene silencing prevents cardiac rupture and ventricular remodeling through negative regulation of the NF-κB signaling pathway in a mouse model of acute myocardial infarction

Cardiac rupture and ventricular remodeling are recognized as the severe complications and major risk factors of acute myocardial infarction (AMI). This study aims to evaluate the regulatory roles of interleukin-1 receptor-associated kinase 3 (IRAK3) and nuclear factor-κB (NF-κB) signaling pathway in cardiac rupture and ventricular remodeling. Microarray analysis was performed to screen AMI-related differentially expressed genes and IRAK3 was identified. The models of AMI were established in male C57BL/6 mice to investigate the functional role of IRAK3. Afterwards, lentivirus recombinant plasmid si-IRAK3 was constructed for IRAK3 silencing. Next, cardiac function parameters were measured in response to IRAK3 silencing. The regulatory effects that IRAK3 had on myocardial infarct size and the content of myocardial interstitial collagen were analyzed. The regulation of IRAK3 silencing on the NF-κB signaling pathway was further assayed. The obtained results indicated that highly expressed IRAK3 and activated NF-κB signaling pathway were observed in myocardial tissues of mouse models of AMI, accompanied by increased expression of matrix metalloproteinase (MMP)-2/9 and tissue inhibitor of metalloproteinase 2 (TIMP-2). Notably, IRAK3 gene silencing inhibited the activation of NF-κB signaling pathway. Furthermore, IRAK3 gene silencing led to the decreased thickness of infarct area and collagen content of myocardial interstitium, alleviated diastolic, and systolic dysfunctions, as well as, facilitated cardiac functions in mice with AMI, corresponding to decreased expression of MMP-2/9 expression and increased expression of TIMP-2. Taken together, silencing of IRAK3 inactivates the NF-κB signaling pathway, and thereby impeding the cardiac rupture and ventricular remodeling, which eventually prevents AMI progression.

Interleukin-1 receptor-associated kinase 3 downregulation in peripheral blood mononuclear cells attenuates immunosuppression in sepsis

Sepsis is the leading cause of mortality in intensive care units due to complex inflammatory immune responses and immunosuppression. Recent studies have indicated that the negative regulator of toll like receptors, interleukin-1 receptor-associated kinase 3 (IRAK-3/IRAK-M), serves an important role in immunosuppression during sepsis. In the current study, a cecal ligation puncture model was established in mice using lipopolysaccharide secondary challenge to simulate immunosuppression in sepsis. Peripheral blood mononuclear cells (PBMCs) from this model were then used to evaluate the expression and function of IRAK-M. The results demonstrated that silencing of IRAK-M expression in PBMCs from immunosuppressed mice partially restored the production of pro-inflammatory cytokines. By introducing PBMCs transfected with small-interfering RNA targeting IRAK-M into septic immunosuppressed mice, the survival rate was improved with an increase in splenic CD4⁺ and CD8⁺ T cells and a decrease in T cell apoptosis. In conclusion, downregulation of IRAK-M reversed the effects of sepsis on the production of inflammatory cytokines in PBMCs, and improved the survival of septic immunosuppressed mice. These results provide a basis for future studies investigating the immunological mechanisms underlying immune suppression in sepsis.

Regulation of the MIR155 host gene in physiological and pathological processes

MicroRNAs (miRNAs), a family of small nonprotein-coding RNAs, play a critical role in posttranscriptional gene regulation by acting as adaptors for the miRNA-induced silencing complex to inhibit gene expression by targeting mRNAs for translational repression and/or cleavage. miR-155-5p and miR-155-3p are processed from the B-cell Integration Cluster (BIC) gene (now designated, MIR155 host gene or MIR155HG). MiR-155-5p is highly expressed in both activated B- and T-cells and in monocytes/macrophages. MiR-155-5p is one of the best characterized miRNAs and recent data indicate that miR-155-5p plays a critical role in various physiological and pathological processes such as hematopoietic lineage differentiation, immunity, inflammation, viral infections, cancer, cardiovascular disease, and Down syndrome. In this review we summarize the mechanisms by which MIR155HG expression can be regulated. Given that the pathologies mediated by miR-155-5p result from the over-expression of this miRNA it may be possible to therapeutically attenuate miR-155-5p levels in the treatment of several pathological processes.