Although most risk factors for cardiac valve calcification (VC) are similar to those for coronary artery disease (CAD), they differ regarding lesions and clinical symptoms. Recently, increasing evidence suggests that intestinal bacteria play essential roles in cardiovascular disease (CVD). It is plausible that the gut microbiota is linked to the occurrence of different CVDs under similar risk factors. Thus, we aimed to explore the gut microbiomes in patients with VC or CAD and determine their underlying connections. We collected samples from 119 subjects and performed 16S rRNA gene sequencing to analyze the gut microbiomes in VC and CAD patients and in control volunteers. The gut microbiomes of VC and CAD patients were significantly different in terms of beta-diversity. Bacteria from Veillonella dispar, Bacteroides plebeius and Fusobacterium were enriched in the VC group, while members of Collinsella aerofaciens, Megamonas, Enterococcus, Megasphaera, Dorea and Blautia were decreased. According to the association with dyslipidemia, seven operational taxonomic units (OTUs), including Parabacteroides distasonis, Megamonas, Fusobacterium, Bacteroides sp., Bacteroides plebeius, Lactobacillus and Prevotella copri, were regarded as potential pathogens for CVDs. Additionally, Prevotella copri might be a keystone of CVDs, especially in VC patients, while Collinsella aerofaciens is a possible keystone of CAD, based on the multi-correlations of these bacteria with other OTUs in microbial communities. Patients with VC and CAD suffer from different gut microbial dysbiosis. The gut microbiomes are associated with the clinical characteristics in these diseases and might be potential therapeutic targets.

Hemodynamic overload and dysregulation of cellular metabolism are involved in development of calcific aortic valve disease (CAVD). However, how mechanical stress relates to metabolic changes in CAVD remains unclear. Here, we show that Piezo1, a mechanosensitive ion channel, regulated glutaminase 1 (GLS1)–mediated glutaminolysis to promote osteogenic differentiation of valve interstitial cells (VICs). In vivo, two models of aortic valve stenosis were constructed by ascending aortic constriction (AAC) and direct wire injury (DWI). Inhibition of Piezo1 and GLS1 in these models respectively mitigated aortic valve lesion. In vitro, Piezo1 activation induced by Yoda1 and oscillatory stress triggered osteogenic responses in VICs, which were prevented by Piezo1 inhibition or knockdown. Mechanistically, Piezo1 activation promoted calcium-dependent Yes-associated protein (YAP) activation. YAP modulated GLS1-mediated glutaminolysis, which enhanced osteogenic differentiation through histone acetylation of runt-related transcription factor 2 (RUNX2) promoters. Together, our work provided a cross-talk between mechanotransduction and metabolism in the context of CAVD.

Aims: Sterile inflammation is implicated in the development of heart failure (HF). Mitochondria play important roles in triggering and maintaining inflammation. Mitophagy is important for regulation of mitochondrial quality and maintenance of cardiac function under pressure overload. The association of mitophagy with inflammation in HF is largely unclear. As PINK1 is a central mediator of mitophagy, our objective was to investigate its involvement in cardiac hypertrophy, and the effect of PINK1-mediated mitophagy on cGAS-STING activation during cardiac hypertrophy. Methods and results: PINK1 knockout and cardiac-specific PINK1-overexpressing transgenic mice were created and subsequently subjected to transverse aortic constriction (TAC) surgery. In order to explore whether PINK1 regulates STING-mediated inflammation during HF, PINK1/STING (stimulator of interferon genes) double-knockout (DKO) mice were created. Pressure overload was induced by TAC. Our findings indicate a significantly decline in PINK1 expression in TAC-induced hypertrophy. Cardiac hypertrophic stimuli caused the release of mitochondrial DNA (mtDNA) into the cytosol, activating the cGAS-STING signalling, which in turn initiated cardiac inflammation and promoted the progression of cardiac hypertrophy. PINK1 deficiency inhibited mitophagy activity, promoted mtDNA release, and then drove the overactivation of cGAS-STING signalling, exacerbating cardiac hypertrophy. Conversely, cardiac-specific PINK1 overexpression protected against hypertrophy thorough inhibition of the cGAS-STING signalling. DKO mice revealed that the effects of PINK1 on hypertrophy were dependent on STING. Conclusion: Our findings suggest that PINK1-mediated mitophagy plays a protective role in pressure overload-induced cardiac hypertrophy via inhibiting the mtDNA-cGAS-STING pathway.

Macrophage-orchestrated chronic inflammation plays an important role in cardiovascular disease, including accelerating the development of calcific aortic valve disease (CAVD). M1 and M2 macrophage polarization imbalances can alter intensity of inflammatory responses. Recombinant human interleukin 37 (IL-37) could be involved in regulating immune cell function to attenuate inflammation. This study aimed to identify IL-37 specifically modulates M1 polarization and investigate the underlying mechanism. Compared with normal valves, there are more M1 macrophages accumulation and less IL-37 expression in calcific aortic valves, which may indicate a negative relationship between IL-37 and M1 polarization. THP-1 cells could differentiate into resting macrophages with phorbol-12-myristate-13-acetate (PMA) and then polarize into M1 macrophages following treatment with lipopolysaccharide (LPS) and interferon gamma (IFN-γ). In vitro, recombinant human IL-37 attenuated the expression of inducible nitric oxide synthase (iNOS), CD11c, IL-6 and monocyte chemoattractant protein 1 (MCP-1) in M1 but augmented the expression of CD206 and IL-10 in M2. The suppression of M1 polarization was associated with the inhibition of the activation of the nuclear factor kappa B (NF-κB) and Notch1 signaling pathways. These results demonstrated that IL-37 inhibits the macrophages polarizing into M1 type via the inhibition of the Notch1 and nuclear factor kappa B pathways. In summary, IL-37 could be a potential therapeutic candidate for progressive CAVD by modulating M1 polarization and its orchestrated inflammation.

Elevated myocardial energy expenditure (MEE) is related with reduced left ventricular ejection fraction, and has also been documented as an independent predictor of cardiovascular mortality. However, the serum small-molecule metabolite profiles and pathophysiological mechanisms of elevated MEE in heart failure (HF) are still lacking. Herein, we used 1H-NMR-based metabolomics analysis to screen for potential biomarkers of MEE in HF. A total of 61 subjects were enrolled, including 46 patients with heart failure and 15 age-matched controls. Venous serum samples were collected from subjects after an 8-hour fast. An INOVA 600 MHz nuclear magnetic resonance spectrometer with Carr-Purcell-Melboom-Gill (CPMG) pulse sequence was employed for the metabolomics analysis and MEE was calculated using colored Doppler echocardiography. Metabolomics data were processed using orthogonal signal correction and regression analysis was performed using the partial least squares method. The mean MEE levels of HF patients and controls were 139.61±58.18 cal/min and 61.09±23.54 cal/min, respectively. Serum metabolomics varied with MEE changed, and 3-hydroxybutyrate, acetone and succinate were significantly elevated with the increasing MEE. Importantly, these three metabolites were independent of administration of angiotensin converting enzyme inhibitor, β-receptor blockers, diuretics and statins (P>0.05). These results suggested that in patients with heart failure, MEE elevation was associated with significant changes in serum metabolomics profiles, especially the concentration of 3-hydroxybutyrate, acetone and succinate. These compounds could be used as potential serum biomarkers to study myocardial energy mechanism in HF patients.

Objective—: Calcific aortic valve disease is a leading cardiovascular disease in the elderly, and progressive calcification results in the failure of valvular function. Aortic valve interstitial cells (AVICs) from stenotic valves express higher levels of bone morphogenetic protein-2 in response to Toll-like receptor 4 stimulation. We recently found that Toll-like receptor 4 interacts with Notch1 in human AVICs. This study tests the hypothesis that Notch1 promotes the pro-osteogenic response of human AVICs. Approach and Results—: AVICs isolated from diseased human valves expressed higher levels of bone morphogenetic protein-2 and alkaline phosphatase after lipopolysaccharide stimulation. The augmented pro-osteogenic response is associated with elevated cellular levels of Notch1 and enhanced Notch1 cleavage in response to lipopolysaccharide stimulation. Inhibition or silencing of Notch1 suppressed the pro-osteogenic response in diseased cells, and the Notch 1 ligand, Jagged1, enhanced the response in AVICs isolated from normal human valves. Interestingly, extracellular signal-regulated protein kinases 1/2 (ERK1/2) and nuclear factor-κB phosphorylation induced by lipopolysaccharide was markedly reduced by inhibition or silencing of Notch1 and enhanced by Jagged1. Inhibition of ERK1/2 or nuclear factor-κB also reduced bone morphogenetic protein-2 and alkaline phosphatase expression induced by lipopolysaccharide. Conclusions—: Notch1 mediates the pro-osteogenic response to Toll-like receptor 4 stimulation in human AVICs. Elevated Notch1 levels and enhanced Notch1 activation play a major role in augmentation of the pro-osteogenic response of AVICs of stenotic valves through modulation of ERK1/2 and nuclear factor-κB activation. These pathways could be potential therapeutic targets for prevention of the progression of calcific aortic valve disease.