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Background: According to some recent observational studies, the gut microbiota influences atherosclerosis via the gut microbiota-artery axis. However, the causal role of the gut microbiota in atherosclerosis remains unclear. Therefore, we used a Mendelian randomization (MR) strategy to try to dissect this causative link. Methods: The biggest known genome-wide association study (GWAS) (n = 13,266) from the MiBioGen collaboration was used to provide summary data on the gut microbiota for a two-sample MR research. Data on atherosclerosis were obtained from publicly available GWAS data from the FinnGen consortium, including cerebral atherosclerosis (104 cases and 218,688 controls), coronary atherosclerosis (23,363 cases and 187,840 controls), and peripheral atherosclerosis (6631 cases and 162,201 controls). The causal link between gut microbiota and atherosclerosis was investigated using inverse variance weighting, MR-Egger, weighted median, weighted mode, and simple mode approaches, among which inverse variance weighting was the main research method. Cochran's Q statistic was used to quantify the heterogeneity of instrumental variables (IVs), and the MR Egger intercept test was used to assess the pleiotropy of IVs. Results: Inverse-variance-weighted (IVW) estimation showed that genus Ruminiclostridium 9 had a protective influence on cerebral atherosclerosis (OR = 0.10, 95% CI: 0.01-0.67, P = 0.018), while family Rikenellaceae (OR = 5.39, 95% CI: 1.50-19.37, P = 0.010), family Streptococcaceae (OR = 6.87, 95% CI: 1.60-29.49, P = 0.010), genus Paraprevotella (OR = 2.88, 95% CI: 1.18-7.05, P = 0.021), and genus Streptococcus (OR = 5.26, 95% CI: 1.28-21.61, P = 0.021) had pathogenic effects on cerebral atherosclerosis. For family Acidaminococcaceae (OR = 0.87, 95% CI: 0.76-0.99, P = 0.039), the genus Desulfovibrio (OR = 0.89, 95% CI: 0.80-1.00, P = 0.048), the genus RuminococcaceaeUCG010 (OR = 0.80, 95% CI: 0.69-0.94, P = 0.006), and the Firmicutes phyla (OR = 0.87, 95% CI: 0.77-0.98, P = 0.023) were protective against coronary atherosclerosis. However, the genus Catenibacterium (OR = 1.12, 95% CI: 1.00-1.24, P = 0.049) had a pathogenic effect on coronary atherosclerosis. Finally, class Actinobacteria (OR = 0.83, 95% CI: 0.69-0.99, P = 0.036), family Acidaminococcaceae (OR = 0.76, 95% CI: 0.61-0.94, P = 0.013), genus Coprococcus2 (OR = 0.76, 95% CI: 0.60-0.96, P = 0.022), and genus RuminococcaceaeUCG010 (OR = 0.65, 95% CI: 0.46-0.92, P = 0.013), these four microbiota have a protective effect on peripheral atherosclerosis. However, for the genus Lachnoclostridium (OR = 1.25, 95% CI: 1.01-1.56, P = 0.040) and the genus LachnospiraceaeUCG001 (OR = 1.22, 95% CI: 1.04-1.42, P = 0.016), there is a pathogenic role for peripheral atherosclerosis. No heterogeneity was found for instrumental variables, and no considerable horizontal pleiotropy was observed. Conclusion: We discovered that the presence of probiotics and pathogens in the host is causally associated with atherosclerosis, and atherosclerosis at different sites is causally linked to specific gut microbiota. The specific gut microbiota associated with atherosclerosis identified by Mendelian randomization studies provides precise clinical targets for the treatment of atherosclerosis. In the future, we can further examine the gut microbiota's therapeutic potential for atherosclerosis if we have a better grasp of the causal relationship between it and atherosclerosis. [ABSTRACT FROM AUTHOR]

Background: Until now, few articles have revealed the potential roles of innate lymphoid cells (ILCs) in cardiovascular diseases. However, the infiltration of ILC subsets in ischemic myocardium, the roles of ILC subsets in myocardial infarction (MI) and myocardial ischemia-reperfusion injury (MIRI) and the related cellular and molecular mechanisms have not been described with a sufficient level of detail. Method: In the current study, 8-week-old male C57BL/6J mice were divided into three groups: MI, MIRI and sham group. Single-cell sequencing technology was used to perform dimensionality reduction clustering of ILC to analyze the ILC subset landscape at a single-cell resolution, and finally flow cytometry was used to confirm the existence of the new ILC subsets in different disease groups. Results: Five ILC subsets were found, including ILC1, ILC2a, ILC2b, ILCdc and ILCt. It is worth noting that ILCdc, ILC2b and ILCt were identified as new ILC subclusters in the heart. The cellular landscapes of ILCs were revealed and signal pathways were predicted. Furthermore, pseudotime trajectory analysis exhibited different ILC statuses and traced related gene expression in normal and ischemic conditions. In addition, we established a ligand–receptor–transcription factor– target gene regulatory network to disclose cell communications among ILC clusters. Moreover, we further revealed the transcriptional features of the ILCdc and ILC2a subsets. Finally, the existence of ILCdc was confirmed by flow cytometry. Conclusion: Collectively, by characterizing the spectrums of ILC subclusters, our results provide a new blueprint for understanding ILC subclusters’ roles in myocardial ischemia diseases and further potential treatment targets. [ABSTRACT FROM AUTHOR]

Background/Aims: Recently, studies have shown that interleukin-37 (IL-37) is involved in atherosclerosis-related diseases. However, the regulatory mechanisms of IL-37 in atherosclerosis remain unknown. This study aims to determine the role of IL-37 in atherosclerosis and to investigate the underlying mechanisms involved. Methods: IL-37 expression in human atherosclerotic plaques was detected by immunohistochemical staining and real-time reverse transcription polymerase chain reaction (RT-PCR). Oil Red O staining was used to measure the size of plaques. Cell apoptosis in vitro and in vivo was tested by flow cytometric analysis and terminal deoxynucleotidyl-transferase mediated dUTP nick-end labeling (TUNEL) staining, respectively. Protein expression levels of IL-37, IL-18Ra and p-Smad3 were measured by Weston blotting. Results: Immunohistochemical staining revealed that IL-37 was highly expressed in human atherosclerotic plaques. Intracellular cytokine staining revealed that infiltrated CD4+ T lymphocytes and vascular smooth muscle cells (VSMCs), but not macrophages, were the major sources of IL-37. Mice that overexpressed IL-37 exhibited significant improvements in their atherosclerotic burden, as demonstrated by reduced plaque size, increased collagen levels, and reduced numbers of apoptotic cells in vivo. Subsequently, mechanistic studies showed that IL-37 played an anti-atherosclerotic role, at least partially, through reducing inflammation by promoting the differentiation of the T helper cell anti-inflammatory phenotype, and through increasing plaque stability by decreasing matrix metalloproteinase (MMP)-2/13-mediated degradation of collagen and inhibiting VSMCs apoptosis. Conclusion: IL-37 may be a novel potential therapeutic target in patients with atherosclerotic heart disease. [ABSTRACT FROM AUTHOR]

Myocardial infarction (MI) triggers an intense inflammatory response that is essential for dead tissue clearance but also detrimental to cardiac repair. Macrophages are active and critical players in the inflammatory response after MI. Understanding the molecular mechanisms by which macrophage-mediated inflammatory response is regulated is important for designing new therapeutic interventions for MI. In the current study, we examined the role of Sestrin2, which is a stress-inducible protein that regulate metabolic homeostasis, in the regulation of inflammatory response of cardiac macrophages after MI. We found that cardiac macrophages upregulated Sestrin2 expression in a mouse MI model. Using a lentiviral transduction system to overexpress Sestrin2 in polarized M1 and M2 macrophages, we revealed that Sestrin2 predominantly functioned on M1 rather than M2 macrophages. Sestrin2 overexpression suppressed inflammatory response of M1 macrophages both in vitro and in vivo. Furthermore, in the mouse MI model with selective depletion of endogenous macrophages and adoptive transfer of exogenous Sestrin2-overexpressing macrophages, the anti-inflammatory and repair-promoting effect of Sestrin2-overexpressing macrophages was demonstrated. Furthermore, Sestrin2 significantly inhibited mTORC1 signaling in M1 macrophages. Taken together, our study indicates the importance of Sestrin2 for suppression of M1 macrophage-mediated cardiac inflammation after MI. [ABSTRACT FROM AUTHOR]

CD4+CD25+ regulatory T cells (Tregs) exert a suppressive activity on atherosclerosis but the underlying mechanism remains unclear. Here, we investigated whether and how Tregs affect oxLDL-induced proinflammatory response in macrophages. Tregs were isolated by magnetic cell sorting-column and analyzed by flow cytometry. Macrophages were cultured with or without Tregs in the presence of oxLDL for 48 hours to induce proinflammatory response. Our data showed that with oxLDL challenge, the Treg-modulated macrophages have decreased NO production and iNOS expression, decreased HLA-DR and CD86 expression, and down-regulated proinflammatory cytokine/chemokine production. Tregs can inhibit the pro-inflammatory properties of macrophages and steer macrophage differentiation toward an anti-inflammatory cytokine producing phenotype. Mechanistic studies reveal that Treg-mediated suppression of the monocyte response to oxLDL was reflected by a reduction in the up-regulation of NF-κB activity accompanied by a decreased expression of TLR2 but not TLR4 at the transcriptional level. These results suggest that CD4+CD25+Foxp3+ regulatory T cells may exert its suppressive functions on pro-inflammatory properties of OxLDL induced-macrophages partly through TLR2-NF-κB signaling pathway. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]