Clec4e-Receptor Signaling in Myocardial Repair After Ischemia-Reperfusion Injury

Heterogeneity of immune cells and their communications unveiled by transcriptome profiling in acute inflammatory lung injury

Background

Acute Respiratory Distress Syndrome (ARDS) or its earlier stage Acute lung injury (ALI), is a worldwide health concern that jeopardizes human well-being. Currently, the treatment strategies to mitigate the incidence and mortality of ARDS are severely restricted. This limitation can be attributed, at least in part, to the substantial variations in immunity observed in individuals with this syndrome.

Methods

Bulk and single cell RNA sequencing from ALI mice and single cell RNA sequencing from ARDS patients were analyzed. We utilized the Seurat program package in R and cellmarker 2.0 to cluster and annotate the data. The differential, enrichment, protein interaction, and cell-cell communication analysis were conducted.

Results

The mice with ALI caused by pulmonary and extrapulmonary factors demonstrated differential expression including Clec4e, Retnlg, S100a9, Coro1a, and Lars2. We have determined that inflammatory factors have a greater significance in extrapulmonary ALI, while multiple pathways collaborate in the development of pulmonary ALI. Clustering analysis revealed significant heterogeneity in the relative abundance of immune cells in different ALI models. The autocrine action of neutrophils plays a crucial role in pulmonary ALI. Additionally, there was a significant increase in signaling intensity between B cells and M1 macrophages, NKT cells and M1 macrophages in extrapulmonary ALI. The CXCL, CSF3 and MIF, TGFβ signaling pathways play a vital role in pulmonary and extrapulmonary ALI, respectively. Moreover, the analysis of human single-cell revealed DCs signaling to monocytes and neutrophils in COVID-19-associated ARDS is stronger compared to sepsis-related ARDS. In sepsis-related ARDS, CD8+ T and Th cells exhibit more prominent signaling to B-cell nucleated DCs. Meanwhile, both MIF and CXCL signaling pathways are specific to sepsis-related ARDS.

Conclusion

This study has identified specific gene signatures and signaling pathways in animal models and human samples that facilitate the interaction between immune cells, which could be targeted therapeutically in ARDS patients of various etiologies.

Identification of diagnostic signatures for ischemic stroke by machine learning algorithm

OBJECTIVE

Ischemic stroke (IS) is one of the major diseases threatening human health and survival and a leading cause of acquired mortality and disability in adults. The aim of this study was to screen diagnostic features of IS and to explore the characteristics of immune cell infiltration in IS pathogenesis.

METHODS

The microarray data of IS (GSE16561, GSE58294, GSE37587, and GSE124026) in the GEO database were merged after removing the batch effect. Then integrated bioinformatic analysis and machine-learning strategies were adopted to analyze the functional correlation and select diagnostic signatures. The WGCNA was used to identify the co-expression modules related to IS. The CIBERSORT algorithm was performed to assess the inflammatory state of IS and to investigate the correlation between diagnostic signatures and infiltrating immune cells.

RESULTS

Functional analysis of dysregulated genes showed that immune response-regulating signaling pathway and pattern recognition receptor activity were enriched in the pathophysiology of IS. The turquoise module was identified as the significant module with IS. By using Lasso and SVM-RFE learning methods, we finally obtained four diagnostic genes, including LAMP2, CR1, CLEC4E, and F5. The corresponding results of AUC of ROC prediction model in training and validation cohort were 0.954 and 0.862, respectively. The immune cell infiltration analysis suggested that plasma cells, resting and activated NK cells, activated dendritic cells, memory B cells, CD8+ T cells, naïve CD4+ T cells, and resting mast cells may be involved in the development of IS. Additionally, these diagnostic signatures might be correlated with multiple immune cells in varying degrees.

CONCLUSION

We identified four biologically relevant genes (LAMP2, CR1, CLEC4E, and F5) with diagnostic effects for IS, our results further provide novel insights regarding molecular mechanisms associated with various immune cells that related to IS for future investigations.

Macrophage mediators and mechanisms in cardiovascular disease

Macrophages are major players in myocardial infarction (MI) and atherosclerosis, two major cardiovascular diseases (CVD). Atherosclerosis is caused by the buildup of cholesterol-rich lipoproteins in blood vessels, causing inflammation, vascular injury, and plaque formation. Plaque rupture or erosion can cause thrombus formation resulting in inadequate blood flow to the heart muscle and MI. Inflammation, particularly driven by macrophages, plays a central role in both atherosclerosis and MI. Recent integrative approaches of single-cell analysis-based classifications in both murine and human atherosclerosis as well as experimental MI showed overlap in origin, diversity, and function of macrophages in the aorta and the heart. We here discuss differences and communalities between macrophages in the heart and aorta at steady state and in atherosclerosis or upon MI. We focus on markers, mediators, and functional states of macrophage subpopulations. Recent trials testing anti-inflammatory agents show a major benefit in reducing the inflammatory burden of CVD patients, but highlight a necessity for a broader understanding of immune cell ontogeny and heterogeneity in CVD. The novel insights into macrophage biology in CVD represent exciting opportunities for the development of novel treatment strategies against CVD.

Myocardial ischemia-reperfusion injury and the influence of inflammation

Acute myocardial infarction is caused by a sudden coronary artery occlusion and leads to ischemia in the corresponding myocardial territory which generally results in myocardial necrosis. Without restoration of coronary perfusion, myocardial scar formation will cause adverse remodelling of the myocardium and heart failure. Successful introduction of percutaneous coronary intervention and surgical coronary artery bypass grafting made it possible to achieve early revascularisation/reperfusion, hence limiting the ischemic zone of myocardium. However, reperfusion by itself paradoxically triggers an exacerbated and accelerated injury in the myocardium, called ischemia-reperfusion (I/R) injury. This mechanism is partially driven by inflammation through multiple interacting pathways. In this review we summarize the current insights in mechanisms of I/R injury and the influence of altered inflammation. Multiple pharmacological and interventional therapeutic strategies (ischemic conditioning) have proven to be beneficial during I/R in preclinical models but were notoriously unsuccessful upon clinical translation. In this review we focus on common mechanisms of I/R injury, altered inflammation and potential therapeutic strategies. We hypothesize that a dual approach may be of value because I/R injury patients are predestined with multiple comorbidities and systemic low-grade inflammation, which requires targeted intervention before other strategies can be fully effective.

Metabolic Acidosis Results in Sexually Dimorphic Response in the Heart Tissue

Metabolic acidosis (MA) is a highly prevalent disorder in a significant proportion of the population, resulting from imbalance in blood pH homeostasis. The heart, being an organ with very low regenerative capacity and high metabolic activity, is vulnerable to chronic, although low-grade, MA. To systematically characterize the effect of low-grade MA on the heart, we treated male and female mice with NH₄Cl supplementation for 2 weeks and analyzed their blood chemistry and transcriptomic signature of the heart tissue. The reduction of pH and plasma bicarbonate levels without an associated change in anion gap indicated a physiological manifestation of low-grade MA with minimal respiratory compensation. On transcriptomic analysis, we observed changes in cardiac-specific genes with significant gender-based differences due to MA. We found many genes contributing to dilated cardiomyopathy to be altered in males, more than in females, while cardiac contractility and Na/K/ATPase-Src signaling were affected in the opposite way. Our model presents a systems-level understanding of how the cardiovascular tissue is affected by MA. As low-grade MA is a common ailment with many dietary and pharmaceutical interventions, our work presents avenues to limit chronic cardiac damage and disease manifestation, as well as highlighting the sex differences in MA-induced cardiovascular damage.

Naringin administration mitigates oxidative stress, anemia, and hypertension in lead acetate-induced cardio-renal dysfunction in cockerel chicks

Lead is one of the major pollutants that is harmful to both animals and humans. It is found in every aspect of the environment such as the air, water, and soil. This pollutant affects both wild and domestic birds. Naringin has an active principle called flavonoid that has been found to have medicinal properties, mostly because of its antioxidant and metal chelating properties. This study was carried out to investigate the protective effect of naringin as an antioxidant against lead-induced anemia, cardio and nephrotoxicity, and hypertension. This study also aimed at elucidating the use of naringin as a heavy metal binder in poultry feed. Thirty-six cockerel chicks were used for this study, and randomly grouped into six groups per group; group A served as the control, group B received Pb-only (300 ppm), group C (Pb and naringin; 80 mg/kg), group D (Pb and naringin; 160 mg/kg), group E (naringin 80 mg/kg), and group F (naringin 160 mg/kg), respectively, for 8 weeks. Lead (Pb) was administered via drinking water, while naringin was administered via oral gavage. Lead acetate intoxication precipitated anemia as indicated by significant reductions in the values of PCV, RBC, and Hb concentration in lead-treated chicks when compared with the controls. Also, lead administration induced hypertension together with increased oxidative stress, depletion of the antioxidant defense system, reduced nitric oxide production, and an increase in high blood pressure. Immunohistochemistry indicated high expressions of cardiac troponin, renal angiotensin-converting enzymes, and renal neutrophil gelatinase-associated lipocalin. Treatment with naringin corrected anemia, reduced oxidative stress, improved antioxidant system, reduced high blood pressure, and offered protection against lead acetate-induced cardio-renal dysfunction in cockerel chicks. We recommend that naringin should be incorporated poultry feeds as a metal binder.

Quo Vadis? Immunodynamics of Myeloid Cells after Myocardial Infarction

Myocardial infarction (MI), a major contributor to worldwide morbidity and mortality, is caused by a lack of blood flow to the heart. Affected heart tissue becomes ischemic due to deficiency of blood perfusion and oxygen delivery. In case sufficient blood flow cannot be timely restored, cardiac injury with necrosis occurs. The ischemic/necrotic area induces a systemic inflammatory response and hundreds of thousands of leukocytes are recruited from the blood to the injured heart. The blood pool of leukocytes is rapidly depleted and urgent re-supply of these cells is needed. Myeloid cells are generated in the bone marrow (BM) and spleen, released into the blood, travel to sites of need, extravasate and accumulate inside tissues to accomplish various functions. In this review we focus on the "leukocyte supply chain" and will separately evaluate different myeloid cell compartments (BM, spleen, blood, heart) in steady state and after MI. Moreover, we highlight the local and systemic kinetics of extracellular factors, chemokines and danger signals involved in the regulation of production/generation, release, transportation, uptake, and activation of myeloid cells during the inflammatory phase of MI.

A myocardial infarct border-zone-on-a-chip demonstrates distinct regulation of cardiac tissue function by an oxygen gradient

After a myocardial infarction, the boundary between the injured, hypoxic tissue and the adjacent viable, normoxic tissue, known as the border zone, is characterized by an oxygen gradient. Yet, the impact of an oxygen gradient on cardiac tissue function is poorly understood, largely due to limitations of existing experimental models. Here, we engineered a microphysiological system to controllably expose engineered cardiac tissue to an oxygen gradient that mimics the border zone and measured the effects of the gradient on electromechanical function and the transcriptome. The gradient delayed calcium release, reuptake, and propagation; decreased diastolic and peak systolic stress; and increased expression of inflammatory cascades that are hallmarks of myocardial infarction. These changes were distinct from those observed in tissues exposed to uniform normoxia or hypoxia, demonstrating distinct regulation of cardiac tissue phenotypes by an oxygen gradient. Our border-zone-on-a-chip model advances functional and mechanistic insight into oxygen-dependent cardiac tissue pathophysiology.

Arteriovenous Fistulae in Chronic Kidney Disease and the Heart: Physiological, Histological, and Transcriptomic Characterization of a Novel Rat Model

Background Arteriovenous fistulae (AVFs) are the gold standard for vascular access in those requiring hemodialysis but may put an extra hemodynamic stress on the cardiovascular system. The complex interactions between the heart, kidney, and AVFs remain incompletely understood. Methods and Results We characterized a novel rat model of five-sixths partial nephrectomy (NX) and AVFs. NX induced increases in urea, creatinine, and hippuric acid. The addition of an AVF (AVF+NX) further increased urea and a number of uremic toxins such as trimethylamine N-oxide and led to increases in cardiac index, left and right ventricular volumes, and right ventricular mass. Plasma levels of uremic toxins correlated well with ventricular morphology and function. Heart transcriptomes identified altered expression of 8 genes following NX and 894 genes following AVF+NX, whereas 290 and 1431 genes were altered in the kidney transcriptomes, respectively. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analysis revealed gene expression changes related to cell division and immune activation in both organs, suppression of ribosomes and transcriptional activity in the heart, and altered renin-angiotensin signaling as well as chronodisruption in the kidney. All except the latter were worsened in AVF+NX compared with NX. Conclusions Inflammation and organ dysfunction in chronic kidney disease are exacerbated following AVF creation. Furthermore, our study provides important information for the discovery of novel biomarkers and therapeutic targets in the management of cardiorenal syndrome.

Integrative Analysis of Multi-Omics and Genetic Approaches-A New Level in Atherosclerotic Cardiovascular Risk Prediction

Genetics and environmental and lifestyle factors deeply affect cardiovascular diseases, with atherosclerosis as the etiopathological factor (ACVD) and their early recognition can significantly contribute to an efficient prevention and treatment of the disease. Due to the vast number of these factors, only the novel "omic" approaches are surmised. In addition to genomics, which extended the effective therapeutic potential for complex and rarer diseases, the use of "omics" presents a step-forward that can be harnessed for more accurate ACVD prediction and risk assessment in larger populations. The analysis of these data by artificial intelligence (AI)/machine learning (ML) strategies makes is possible to decipher the large amount of data that derives from such techniques, in order to provide an unbiased assessment of pathophysiological correlations and to develop a better understanding of the molecular background of ACVD. The predictive models implementing data from these "omics", are based on consolidated AI best practices for classical ML and deep learning paradigms that employ methods (e.g., Integrative Network Fusion method, using an AI/ML supervised strategy and cross-validation) to validate the reproducibility of the results. Here, we highlight the proposed integrated approach for the prediction and diagnosis of ACVD with the presentation of the key elements of a joint scientific project of the University of Milan and the Almazov National Medical Research Centre.