TIR/BB-loop mimetic AS-1 attenuates cardiac ischemia/reperfusion injury via a caveolae and caveolin-3-dependent mechanism

Compound c17 alleviates inflammatory cardiomyopathy in streptozotocin-induced diabetic mice by targeting MyD88

BACKGROUND

Diabetic cardiomyopathy (DCM) is a common complication of diabetes mellitus and is associated with increased morbidity and mortality due to cardiac dysfunction. Chronic inflammation plays a significant role in the development of DCM, making it a promising target for novel pharmacological strategies. Our previous study has synthesized a novel compound, c17, which exhibited strong anti-inflammatory activity by specifically targeting to myeloid differentiation primary response 88 (MyD88). In this study, we evaluated the therapeutic effect of c17 in DCM.

METHODS

The small molecular selective MyD88 inhibitor, c17, was used to evaluate the effect of MyD88 on DCM in both high concentration of glucose- and palmitic acid-stimulated macrophages and streptozotocin (STZ)-induced type 1 diabetes mellitus (T1DM) mice.

RESULTS

The treatment of c17 in T1DM mice resulted in improved heart function and reduced cardiac hypertrophy, inflammation and fibrogenesis. RNA sequencing analysis of the heart tissues revealed that c17 effectively suppressed the inflammatory response by regulating the MyD88-dependent pathway. Co-immunoprecipitation experiments further confirmed that c17 disrupted the interaction between MyD88 and Toll-like receptor 4 (TLR4), consequently inhibiting downstream NF-κB activation. In vitro studies demonstrated that c17 exhibited similar anti-inflammatory activity by targeting MyD88 in macrophages, which are the primary regulators of cardiac inflammation. Furthermore, conditioned medium derived from c17-treated macrophages showed reduced capacity to induce hypertrophy, pro-fibrotic reactions, and secondary inflammation in cardiomyocytes.

CONCLUSIONS

In conclusion, the small-molecule MyD88 inhibitor, c17, effectively combated the inflammatory DCM, therefore could be a potential candidate for the treatment of this disease.

Pathophysiology and molecular mechanism of caveolin involved in myocardial protection strategies in ischemic conditioning

Multiple pathophysiological pathways are activated during the process of myocardial injury. Various cardioprotective strategies protect the myocardium from ischemia, infarction, and ischemia/reperfusion (I/R) injury through different targets, yet the clinical translation remains limited. Caveolae and its structure protein, caveolins, have been suggested as a bridge to transmit damage-preventing signals and mediate the protection of ultrastructure in cardiomyocytes under pathological conditions. In this review, we first briefly introduce caveolae and caveolins. Then we review the cardioprotective strategies mediated by caveolins through various pathophysiological pathways. Finally, some possible research directions are proposed to provide future experiments and clinical translation perspectives targeting caveolin based on the investigative evidence.

The TIR/BB-loop mimetic AS-1 prevents Ang II-induced hypertensive cardiac hypertrophy via NF-κB dependent downregulation of miRNA-143

Untreated pathological cardiac hypertrophy, which can be caused by sustained systemic hypertension, may lead to heart failure. In the present study, we investigated whether AS-1 had attenuating effects on hypertension-induced cardiac hypertrophy, and whether this process was mediated by the regulation of miRNA-143. To induce the hypertrophic response in vitro, cardiomyocytes were stimulated with Ang II for 24hs. AS-1 administration strongly attenuated Ang II-induced hypertrophic response of cardiomyocytes. Chronical infusion of Ang II via implanted osmotic mini-pump induced increased blood pressure and cardiac hypertrophy in vivo. AS-1 administration attenuated hypertension-induced cardiac hypertrophy by, at least in part, inhibin of MAPK signaling. We observed, for the first time, upregulated expression of miRNA-143 in Ang II-induced cardiomyocytes, and inhibition of miRNA-143 significantly reduced the Ang II-induced hypertrophic responses. Importantly, AS-1 administration diminished the Ang II-induced upregulation of miRNA-143. Overexpression of miRNA-143 abolished the attenuating effects of AS-1 on Ang II-induced hypertrophic response of cardiomyocytes. Additionally, AS-1 administration abrogates Ang II-induced nuclear translocation of p50 NF-κB subunit in hypertrophic cardiomyocytes. Application of NF-κB inhibitor significantly suppressed Ang II-induced upregulation of miRNA-143. Our data suggest a novel mechanism by which AS-1 attenuates Ang II-induced hypertrophic response through downregulation miRNA-143 expression in a NF-κB-dependent manner.