Myocardial fibrosis and calcification associate with adverse outcomes in nonischemic heart failure. Cardiac fibroblasts (CF) transition into myofibroblasts (MF) and osteogenic fibroblasts (OF) to promote myocardial fibrosis and calcification. However, common upstream mechanisms regulating both CF-to-MF transition and CF-to-OF transition remain unknown. microRNAs are promising targets to modulate CF plasticity. Our bioinformatics revealed downregulation of miR–129-5p and upregulation of its targets small leucine–rich proteoglycan Asporin (ASPN) and transcription factor SOX9 as common in mouse and human heart failure (HF). We experimentally confirmed decreased miR–129-5p and enhanced SOX9 and ASPN expression in CF in human hearts with myocardial fibrosis and calcification. miR–129-5p repressed both CF-to-MF and CF-to-OF transition in primary CF, as did knockdown of SOX9 and ASPN. Sox9 and Aspn are direct targets of miR–129-5p that inhibit downstream β-catenin expression. Chronic Angiotensin II infusion downregulated miR–129-5p in CF in WT and TCF21-lineage CF reporter mice, and it was restored by miR–129-5p mimic. Importantly, miR–129-5p mimic not only attenuated progression of myocardial fibrosis, calcification marker expression, and SOX9 and ASPN expression in CF but also restored diastolic and systolic function. Together, we demonstrate miR–129-5p/ASPN and miR–129-5p/SOX9 as potentially novel dysregulated axes in CF-to-MF and CF-to-OF transition in myocardial fibrosis and calcification and the therapeutic relevance of miR–129-5p.

Mortality from myocardial infarction (MI) has declined over recent decades, which could be attributed in large part to improved treatment methods. Early reperfusion is the cornerstone of current MI treatment. However, reoxygenation via restored blood flow induces further damage to the myocardium, leading to ischemia-reperfusion injury (IRI). While experimental studies overwhelmingly demonstrate that females experience greater functional recovery from MI and decreased severity in the underlying pathophysiological mechanisms, the outcomes of MI with subsequent reperfusion therapy, which is the clinical correlate of myocardial IRI, are generally poorer for women compared with men. Distressingly, women are also reported to benefit less from current guideline-based therapies compared with men. These seemingly contradicting outcomes between experimental and clinical studies show a need for further investigation of sex-based differences in disease pathophysiology, treatment response, and a sex-specific approach in the development of novel therapeutic methods against myocardial IRI. In this literature review, we summarize the current knowledge on sex differences in the underlying pathophysiological mechanisms of myocardial IRI, including the roles of sex hormones and sex chromosomes. Furthermore, we address sex differences in pharmacokinetics, pharmacodynamics, and pharmacogenetics of current drugs prescribed to limit myocardial IRI. Lastly, we highlight ongoing clinical trials assessing novel pharmacological treatments against myocardial IRI and sex differences that may underlie the efficacy of these new therapeutic approaches.

Fibrosis is a hallmark of adverse cardiac remodeling, which promotes heart failure, but it is also an essential repair mechanism to prevent cardiac rupture, signifying the importance of appropriate regulation of this process. In the remodeling heart, cardiac fibroblasts (CFs) differentiate into myofibroblasts (MyoFB), which are the key mediators of the fibrotic response. Additionally, cardiomyocytes are involved by providing pro-fibrotic cues. Nuclear receptor Nur77 is known to reduce cardiac hypertrophy and associated fibrosis; however, the exact function of Nur77 in the fibrotic response is yet unknown. Here, we show that Nur77-deficient mice exhibit severe myocardial wall thinning, rupture and reduced collagen fiber density after myocardial infarction and chronic isoproterenol (ISO) infusion. Upon Nur77 knockdown in cultured rat CFs, expression of MyoFB markers and extracellular matrix proteins is reduced after stimulation with ISO or transforming growth factor–β (TGF-β). Accordingly, Nur77-depleted CFs produce less collagen and exhibit diminished proliferation and wound closure capacity. Interestingly, Nur77 knockdown in neonatal rat cardiomyocytes results in increased paracrine induction of MyoFB differentiation, which was blocked by TGF-β receptor antagonism. Taken together, Nur77-mediated regulation involves CF-intrinsic promotion of CF-to-MyoFB transition and inhibition of cardiomyocyte-driven paracrine TGF-β-mediated MyoFB differentiation. As such, Nur77 provides distinct, cell-specific regulation of cardiac fibrosis.

Background: Pulmonary arterial hypertension (PAH) presents as increased pressure in the pulmonary arteries (PA) leading to cardiac right ventricular (RV) failure and death. Pulmonary arterial (PA) remodeling characterized by enhanced proliferation of pulmonary arterial smooth muscle cells (PASMC) and fibroblasts (PAFB) underlies PAH. There are currently no cures and PAH mortality remains high. PAH has a striking female-predominant incidence – 4:1 ratio – indicating that males may have a protective factor. However, to date only a few sex-biased factors in PAH have been investigated. Methods: Analyses were performed on a publicly available microarray dataset (GSE117261), comprising human lung tissues from PAH patients and healthy controls, as well as publicly available single-cell lung atlases of humans and mice. Lung tissue, plasma, PASMC and PAFB were collected from male and female PAH patients. Cell proliferation was assessed after recombinant HGF protein stimulation. PH was induced in male and female rats by monocrotaline (MCT). Lung-specific knockdown was performed by intratracheal siRNA instillation the first two weeks after MCT injection. PA and RV function were assessed by echocardiography, RV systolic pressure by catheterization, and PA remodeling by histology. Results: HGF was only upregulated in lungs of male PAH patients compared to male control lungs, but not in female PAH patients vs. female controls. Elevated plasma HGF correlated with favorable clinical characteristics only in male PAH patients. HGF is highly expressed in vascular SMC and FB in the lung and recombinant HGF inhibited PASMC and PAFB proliferation to a greater extent in cells isolated from male PAH patients compared to female. Lung HGF expression is increased to a higher extent and longer duration at early stage of PH in male rats in MCT model vs. female rats. Finally, knockdown of HGF in the lungs in early disease stage exacerbated PH in male rats characterized by higher mortality, worsened RV and PA function as well as enhanced PA medial thickening and adventitial fibrosis. Conclusions: Lung HGF expression may be upregulated to counteract PAH disease progression by inhibiting proliferation of PASMC and PAFB. Elevated HGF in males might at least partially account for the lower incidence of male PAH patients.