Lerman, Amir

Autologous mesenchymal stem/stromal cells (MSCs) have demonstrated important therapeutic effects in several diseases. Cardiovascular risk factors may impair MSC mitochondrial structure and function, but the underlying mechanisms remain unknown. We hypothesized that metabolic syndrome (MetS) induces epigenetic alterations in mitochondria-related genes in swine MSCs. Pigs were fed a Lean or MetS diet (n = 6 each) for 16 weeks. MSCs were collected from subcutaneous abdominal fat, and DNA hydroxymethylation (5 hmC) profiles of mitochondria-related genes (MitoCarta-2.0) were analyzed by hydroxymethylated DNA immunoprecipitation and next-generation sequencing (hMeDIP-seq) in Lean- and MetS-MSCs untreated or treated with the epigenetic modulator vitamin (Vit)-C (n = 3 each). Functional analysis of genes with differential 5 hmC regions was performed using DAVID6.8. Mitochondrial structure (electron microscopy), oxidative stress, and membrane potential were assessed. hMeDIP-seq identified 172 peaks (associated with 103 mitochondrial genes) with higher and 416 peaks (associated with 165 mitochondrial genes) with lower 5 hmC levels in MetS-MSCs versus Lean-MSCs (≥2-fold, p < 0.05). Genes with higher 5 hmC levels in MetS + MSCs were primarily implicated in fatty acid metabolism, whereas those with lower 5 hmC levels were associated with electron transport chain activity. Vit-C increased 5 hmC levels in mitochondrial antioxidant genes, improved mitochondrial structure and membrane potential, and decreased oxidative stress. MetS alters 5 hmC levels of mitochondria-related genes in swine MSCs. Vit-C modulated 5 hmC levels in these genes and preserved mitochondrial structure and function in MetS-MSCs. These observations may contribute to development of strategies to overcome the deleterious effects of MetS on MSCs.

Abstract:Coronary artery disease is the leading cause of morbidity and mortality worldwide, espe-cially in developed countries, with an increasing incidence in developing countries. Despite the ad-vances in cardiology, there are yet many unanswered questions about the natural history of coronary atherosclerosis. However, it has not been fully explained why some coronary artery plaques remain quiescent over time, whereas others evolve to a high-risk, “vulnerable” plaque with a predisposition to destabilize and induce a cardiac event. Furthermore, approximately half of the patients with acute coronary syndromes demonstrate no prior symptoms of ischemia or angiographically evident dis-ease. Recent findings have indicated that apart from cardiovascular risk factors, genetics, and other unknown factors, local hemodynamic forces, such as endothelial shear stress, blood flow patterns, and endothelial dysfunction of the epicardial and microvascular coronary arteries, are associated with the progression of coronary plaque and the development of cardiovascular complications with complex interactions. In this review article, we summarize the mechanisms that affect coronary ar-tery plaque progression, indicating the importance of endothelial shear stress, endothelial dysfunc-tion of epicardial and microvascular vessels, inflammation, and their complex associations, underly-ing in parallel the clinical perspectives of these findings.

Background: Clonal hematopoiesis (CH) of indeterminate potential (CHIP) is a risk factor for cardiovascular disease. The relationship between CHIP and coronary microvascular dysfunction (CMD) is unknown. The current study examines the association between CHIP and CH with CMD and the potential relationships in risk for adverse cardiovascular outcomes. Methods: In this retrospective observational study, targeted next-generation sequencing was performed for 177 participants with no coronary artery disease who presented with chest pain and underwent routine coronary functional angiogram. Patients with somatic mutations in leukemia-associated driver genes in hematopoietic stem and progenitor cells were examined; CHIP was considered at a variant allele fraction ≥2%; CH was considered at a variant allele fraction ≥1%. CMD was defined as coronary flow reserve to intracoronary adenosine of ≤2. Major adverse cardiovascular events considered were myocardial infarction, coronary revascularization, or stroke. Results: A total of 177 participants were examined. Mean follow-up was 12±7 years. A total of 17 patients had CHIP and 28 had CH. Cases with CMD (n=19) were compared with controls with no CMD (n=158). Cases were 56±9 years, were 68% women, and had more CHIP (27%; P =0.028) and CH (42%; P =0.001) than controls. CMD was associated with independent risk for major adverse cardiovascular events (hazard ratio, 3.89 [95% CI, 1.21–12.56]; P =0.023), and 32% of this risk was mediated by CH. The risk mediated by CH was ≈0.5× as large as the direct effect of CMD on major adverse cardiovascular events. Conclusions: In humans, we observe patients with CMD are more likely to have CHIP, and nearly one-third of major adverse cardiovascular events in CMD are mediated by CH.

Background Mechanisms underlying bioprosthetic valve deterioration are multifactorial and incompletely elucidated. Reparative circulating progenitor cells, and conversely calcification‐associated osteocalcin expressing circulating progenitor cells, have been linked to native aortic valve deterioration. However, their role in bioprosthetic valve deterioration remains elusive. This study sought to evaluate the contribution of different subpopulations of circulating progenitor cells in bioprosthetic valve deterioration. Methods and Results This single‐center prospective study enrolled 121 patients who had peripheral blood mononuclear cells isolated before bioprosthetic aortic valve replacement and had an echocardiographic follow‐up ≥2 years after the procedure. Using flow cytometry, fresh peripheral blood mononuclear cells were analyzed for the surface markers CD34, CD133, and osteocalcin. Bioprosthetic valve deterioration was evaluated by hemodynamic valve deterioration (HVD) using echocardiography, which was defined as an elevated mean transprosthetic gradient ≥30 mm Hg or at least moderate intraprosthetic regurgitation. Sixteen patients (13.2%) developed HVD during follow‐up for a median of 5.9 years. Patients with HVD showed significantly lower levels of reparative CD34 + CD133 + cells and higher levels of osteocalcin‐positive cells than those without HVD (CD34 + CD133 + cells: 125 [80, 210] versus 270 [130, 420], P =0.002; osteocalcin‐positive cells: 3060 [523, 5528] versus 670 [180, 1930], P =0.005 respectively). Decreased level of CD34 + CD133 + cells was a significant predictor of HVD (hazard ratio, 0.995 [95% CI, 0.990%–0.999%]). Conclusions Circulating levels of CD34 + CD133 + cells and osteocalcin‐positive cells were significantly associated with the subsequent occurrence of HVD in patients undergoing bioprosthetic aortic valve replacement. Circulating progenitor cells might play a vital role in the mechanism, risk stratification, and a potential therapeutic target for patients with bioprosthetic valve deterioration.

To address the ongoing shortage of organs available for replacement, xenotransplantation of hearts, corneas, skin, and kidneys has been attempted. However, a major obstacle facing xenotransplants is rejection due to a cycle of immune reactions to the graft. Both adaptive and innate immune systems contribute to this cycle, in which natural killer cells, macrophages, and T-cells play a significant role. While advancements in the field of genetic editing can circumvent some of these obstacles, biomarkers to identify and predict xenograft rejection remain to be standardized. Several T-cell markers, such as CD3, CD4, and CD8, are useful in both the diagnosis and prediction of xenograft rejection. Furthermore, an increase in the levels of various circulating DNA markers and microRNAs is also predictive of xenograft rejection. In this review, we summarize recent findings on the advancements in xenotransplantation, with a focus on pig-to-human, the role of immunity in xenograft rejection, and its biomarkers.

Background There is a scarcity of validated rapid dietary screening tools for patient use in the clinical setting to improve health and reduce cardiovascular risk. The Healthy Eating Index (HEI) 2015 measures compliance with the 2015 to 2020 Dietary Guidelines for Americans but requires completion of an extensive diet assessment to compute, which is time consuming and impractical. The authors hypothesize that a 19‐item dietary survey assessing consumption of common food groups known to affect health will be correlated with the HEI‐2015 assessed by a validated food frequency questionnaire and can be further reduced without affecting validity. Methods and Results A 19‐item Eating Assessment Tool (EAT) of common food groups was created through literature review and expert consensus. A cross‐sectional survey was then conducted in adult participants from a preventive cardiology clinic or cardiac rehabilitation and in healthy volunteers (n=661, mean age, 36 years; 76% women). Participants completed an online 156‐item food frequency questionnaire, which was used to calculate the HEI score using standard methods. The association between each EAT question and HEI group was analyzed by Kruskal‐Wallis test. Linear regression models were subsequently used to identify univariable and multivariable predictors for HEI score for further reduction in the number of items. The final 9‐item model of Mini‐EAT was validated by 5‐fold cross validation. The 19‐item EAT had a strong correlation with the HEI score ( r =0.73) and was subsequently reduced to the 9 items independently predictive of the HEI score: fruits, vegetables, whole grains, refined grains, fish or seafood, legumes/nuts/seeds, low‐fat dairy, high‐fat dairy, and sweets consumption, without affecting the predictive ability of the tool ( r =0.71). Conclusions Mini‐EAT is a 9‐item validated brief dietary screener that correlates well with a comprehensive food frequency questionnaire. Future studies to test the Mini‐EAT's validity in diverse populations and for development of clinical decision support systems to capture changes over time are needed.

In recent years, the importance of the gut microbiome in human health and disease has increased. Growing evidence suggests that gut dysbiosis might be a crucial risk factor for coronary artery disease (CAD). Therefore, we conducted a systematic review and meta-analysis to determine whether or not CAD is associated with specific changes in the gut microbiome. The V3–V4 regions of the 16S rDNA from fecal samples were analyzed to compare the gut microbiome composition between CAD patients and controls. Our search yielded 1181 articles, of which 21 met inclusion criteria for systematic review and 7 for meta-analysis. The alpha-diversity, including observed OTUs, Shannon and Simpson indices, was significantly decreased in CAD, indicating the reduced richness of the gut microbiome. The most consistent results in a systematic review and meta-analysis pointed out the reduced abundance of Bacteroidetes and Lachnospiraceae in CAD patients. Moreover, Enterobacteriaceae, Lactobacillus, and Streptococcus taxa demonstrated an increased trend in CAD patients. The alterations in the gut microbiota composition are associated with qualitative and quantitative changes in bacterial metabolites, many of which have pro-atherogenic effects on endothelial cells, increasing the risk of developing and progressing CAD.

The inflammatory response is a major pathological feature in most kidney diseases and often evokes compensatory mechanisms. Recent evidence suggests that TSG-6 (tumor necrosis factor-α-stimulated gene/protein-6) plays a pivotal role in anti-inflammation in various renal diseases, including immune-mediated and nonimmune-mediated renal diseases. TSG-6 has a diverse repertoire of anti-inflammatory functions: it potentiates antiplasmin activity of IαI (inter-α-inhibitor) by binding to its light chain, crosslinks hyaluronan to promote its binding to cell surface receptor CD44, and thereby regulate the migration and adhesion of lymphocytes, inhibits chemokine-stimulated transendothelial migration of neutrophils by directly interacting with the glycosaminoglycan binding site of CXCL8 (CXC motif chemokine ligand-8), and upregulates COX-2 (cyclooxygenase-2) to produce anti-inflammatory metabolites. Hopefully, further developments can target this anti-inflammatory molecule to the kidney and harness its remedial properties. This review provides an overview of the emerging role of TSG-6 in blunting renal inflammation.