Cardiac Macrophage Density in Covid-19 Infection: Relationship to Myocyte Necrosis and Acute Lung Injury

Immune modulation: the key to combat SARS-CoV-2 induced myocardial injury

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which caused the Coronavirus disease 2019 (COVID-19) pandemic, has posed significant healthcare challenges. In addition to respiratory complications, it has led to severe damage in other organs, particularly the cardiovascular system. Of which, myocardial injury is increasingly recognized as a most significant complication, contributing to the high mortality. Recent research indicates the pivotal role of immune dysregulation in mediating myocardial injury in patients infected with SARS-CoV-2. In this review, we provide a comprehensive analysis of the immune mechanisms involved in SARS-CoV-2-induced myocardial damage, focusing on the roles of key immune cells and molecules that contribute to this pathological process. Aiming at mitigating the myocardial injury of COVID-19, we review immune-based treatments under evaluation in preclinical and clinical trials. Along with talking about the similarities and differences in myocardial injury resulting from SARS-CoV-2, the Middle East respiratory syndrome coronavirus (MERS-CoV) and the severe acute respiratory syndrome coronavirus (SARS-CoV). This article provides a unique perspective on using past experiences to prevent myocardial injury in the face of ongoing virus mutations.

Single Center-Based Real-World Experience on Anti-IL 1 Biological Response Modifiers: A Case Series and Literature Review

BACKGROUND

This communication summarizes our single-center experience with the use of anti-IL-1 biologic response modifiers for treating autoimmune and autoinflammatory conditions in children.

METHODS

We outline our rationale for the off-label use of anakinra and discuss emerging treatment paradigms that necessitate further research and validation.

RESULTS

Anakinra has enabled personalized treatment, whether used as a single agent on an as-needed basis, as part of a background treatment regimen, or in combination with colchicine. Our data also highlight the significance of anakinra in treating post-infectious inflammatory diseases, demonstrating its high efficacy in novel applications such as rheumatic fever and post-viral arthritis. Canakinumab, on the other hand, has provided long-term remission. Both medications were well-tolerated, with no serious adverse effects reported.

CONCLUSIONS

Based on our observations and successful outcomes, we advocate for future collaborative efforts to improve access to anti-IL-1 medications to better manage excessive and harmful inflammation in children.

New insights gained from cellular landscape changes in myocarditis and inflammatory cardiomyopathy

Advances in the etiological classification of myocarditis and inflammatory cardiomyopathy (ICM) have reached a consensus. However, the mechanism of myocarditis/ICM remains unclear, which affects the development of treatment and the improvement of outcome. Cellular transcription and metabolic reprogramming, and the interactions between cardiomyocytes and non-cardiomyocytes, such as the immune cells, contribute to the process of myocarditis/ICM. Recent efforts have been made by multi-omics techniques, particularly in single-cell RNA sequencing, to gain a better understanding of the cellular landscape alteration occurring in disease during the progression. This article aims to provide a comprehensive overview of the latest studies in myocarditis/ICM, particularly as revealed by single-cell sequencing.

Effectiveness and Safety of Shengmai San for Viral Myocarditis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Shengmai San (SMS) is a traditional Chinese medicine formula used for supplementing Qi and Yin and can mitigate symptoms related to malignant arrhythmia and heart failure. This systematic review aimed at exploring the effectiveness and safety of SMS for viral myocarditis (VMC). Methods: Eight databases from their inception to June 2023 were searched to identified randomized controlled trials (RCTs) focusing on SMS for VMC. The Cochrane Risk of Bias Tool was used to assess methodological quality. Mean difference (MD), standardized mean difference (SMD), and risk ratio (RR) with 95% confidence interval (CI) were calculated and input into the meta-analysis using RevMan 5.4. Results: Forty-four RCTs were included involving 4298 participants. The interventions included 29 types of modified SMS decoctions and 15 patent medicines. Overall study quality was low. Compared with western medicine (WM), SMS was associated with higher recovery rate from palpitations (RR 2.3, 95% CI 1.59, 3.33, 2 RCTs, n = 89), chest pain (RR 1.57, 95% CI [1.17, 2.09], 2 RCTs, n = 89), and lower cTnI (MD -0.82 ng/ml, 95% CI -0.98, -0.66, 1 RCT, n = 60). SMS plus WM was more effective than WM in palpitation recovery rate (RR 1.52, 95% CI 1.21, 1.92, 3 RCTs, n = 136), dyspnea recovery rate (RR 1.47, 95% CI 1.12, 1.94, 3 RCT, n = 267), ECG (RR 1.43, 95% CI 1.32, 1.55, 20 RCT, n = 2035), CK-MB (MD -6.36, 95% CI -8.43, -4.28, 8 RCT, n = 946), and cTnI (MD -0.06, 95% CI -0.06, -0.05, 3 RCT, n = 307). No serious adverse events were reported using SMS alone or in combination with WM. Conclusion: SMS used alone or combined with WM may have potential effectiveness on symptom alleviation, ECG recovery rate, myocardial injury markers, and cardiac function, but the effectiveness is uncertain due to the low quality and absence of placebo-controlled trials. The exact efficacy of SMS for VMC needs to be confirmed by high-quality double-blind RCTs in the future.

Addo S, Harris RA, Lucas R, Csányi G. SARS-CoV-2 Spike Protein Stimulates Macropinocytosis in Murine and Human Macrophages via PKC-NADPH Oxidase Signaling

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). While recent studies have demonstrated that SARS-CoV-2 may enter kidney and colon epithelial cells by inducing receptor-independent macropinocytosis, it remains unknown whether this process also occurs in cell types directly relevant to SARS-CoV-2-associated lung pneumonia, such as alveolar epithelial cells and macrophages. The goal of our study was to investigate the ability of SARS-CoV-2 spike protein subunits to stimulate macropinocytosis in human alveolar epithelial cells and primary human and murine macrophages. Flow cytometry analysis of fluid-phase marker internalization demonstrated that SARS-CoV-2 spike protein subunits S1, the receptor-binding domain (RBD) of S1, and S2 stimulate macropinocytosis in both human and murine macrophages in an angiotensin-converting enzyme 2 (ACE2)-independent manner. Pharmacological and genetic inhibition of macropinocytosis substantially decreased spike-protein-induced fluid-phase marker internalization in macrophages both in vitro and in vivo. High-resolution scanning electron microscopy (SEM) imaging confirmed that spike protein subunits promote the formation of membrane ruffles on the dorsal surface of macrophages. Mechanistic studies demonstrated that SARS-CoV-2 spike protein stimulated macropinocytosis via NADPH oxidase 2 (Nox2)-derived reactive oxygen species (ROS) generation. In addition, inhibition of protein kinase C (PKC) and phosphoinositide 3-kinase (PI3K) in macrophages blocked SARS-CoV-2 spike-protein-induced macropinocytosis. To our knowledge, these results demonstrate for the first time that SARS-CoV-2 spike protein subunits stimulate macropinocytosis in macrophages. These results may contribute to a better understanding of SARS-CoV-2 infection and COVID-19 pathogenesis.

The Influence of COVID-19 in Endocrine Research: Critical Overview, Methodological Implications and a Guideline for Future Designs

The COVID-19 pandemic has changed many aspects of people's lives, including not only individual social behavior, healthcare procedures, and altered physiological and pathophysiological responses. As a result, some medical studies may be influenced by one or more hidden factors brought about by the COVID-19 pandemic. Using the literature review method, we are briefly discussing the studies that are confounded by COVID-19 and facemask-induced partiality and how these factors can be further complicated with other confounding variables. Facemask wearing has been reported to produce partiality in studies of ophthalmology (particularly dry eye and related ocular diseases), sleep studies, cognitive studies (such as emotion-recognition accuracy research, etc.), and gender-influenced studies, to mention a few. There is a possibility that some other COVID-19 related influences remain unrecognized in medical research. To account for heterogeneity, current and future studies need to consider the severity of the initial illness (such as diabetes, other endocrine disorders), and COVID-19 infection, the timing of analysis, or the presence of a control group. Face mask-induced influences may confound the results of diabetes studies in many ways.

Injury mechanism of COVID-19-induced cardiac complications

Heart dysfunction is one of the most life-threatening organ dysfunctions caused by coronavirus disease 2019 (COVID-19). Myocardial or cardiovascular damage is the most common extrapulmonary organ complication in critically ill patients. Understanding the pathogenesis and pathological characteristics of myocardial and vascular injury is important for improving clinical diagnosis and treatment approach. Herein, the mechanism of direct damage caused by severe acute respiratory syndrome coronavirus 2 to the heart and secondary damage caused by virus-driven inflammation was reviewed. The pathological mechanism of ischemia and hypoxia due to microthrombosis and inflammatory injury as well as the injury mechanism of tissue inflammation and single myocardial cell necrosis triggered by the viral infection of pericytes or macrophages, hypoxia, and energy metabolism disorders were described. The latter can provide a novel diagnosis, treatment, and investigation strategy for heart dysfunctions caused by COVID-19 or the Omicron variant.

Cell-Specific Mechanisms in the Heart of COVID-19 Patients

From the onset of the pandemic, evidence of cardiac involvement in acute COVID-19 abounded. Cardiac presentations ranged from arrhythmias to ischemia, myopericarditis/myocarditis, ventricular dysfunction to acute heart failure, and even cardiogenic shock. Elevated serum cardiac troponin levels were prevalent among hospitalized patients with COVID-19; the higher the magnitude of troponin elevation, the greater the COVID-19 illness severity and in-hospital death risk. Whether these consequences were due to direct SARS-CoV-2 infection of cardiac cells or secondary to inflammatory responses steered early cardiac autopsy studies. SARS-CoV-2 was reportedly detected in endothelial cells, cardiac myocytes, and within the extracellular space. However, findings were inconsistent and different methodologies had their limitations. Initial autopsy reports suggested that SARS-CoV-2 myocarditis was common, setting off studies to find and phenotype inflammatory infiltrates in the heart. Nonetheless, subsequent studies rarely detected myocarditis. Microthrombi, cardiomyocyte necrosis, and inflammatory infiltrates without cardiomyocyte damage were much more common. In vitro and ex vivo experimental platforms have assessed the cellular tropism of SARS-CoV-2 and elucidated mechanisms of viral entry into and replication within cardiac cells. Data point to pericytes as the primary target of SARS-CoV-2 in the heart. Infection of pericytes can account for the observed pericyte and endothelial cell death, innate immune response, and immunothrombosis commonly observed in COVID-19 hearts. These processes are bidirectional and synergistic, rendering a definitive order of events elusive. Single-cell/nucleus analyses of COVID-19 myocardial tissue and isolated cardiac cells have provided granular data about the cellular composition and cell type-specific transcriptomic signatures of COVID-19 and microthrombi-positive COVID-19 hearts. Still, much remains unknown and more in vivo studies are needed. This review seeks to provide an overview of the current understanding of COVID-19 cardiac pathophysiology. Cell type-specific mechanisms and the studies that provided such insights will be highlighted. Given the unprecedented pace of COVID-19 research, more mechanistic details are sure to emerge since the writing of this review. Importantly, our current knowledge offers significant clues about the cardiac pathophysiology of long COVID-19, the increased postrecovery risk of cardiac events, and thus, the future landscape of cardiovascular disease.

Persistent viral infections and their role in heart disease

Viral infections are the culprit of many diseases, including inflammation of the heart muscle, known as myocarditis. Acute myocarditis cases have been described in scientific literature, and viruses, such as parvovirus B19, coxsackievirus B3, or more recently, SARS-CoV-2, were the direct cause of cardiac inflammation. If not treated, myocarditis could progress to dilated cardiomyopathy, which permanently impairs the heart and limits a person's lifespan. Accumulated evidence suggests that certain viruses may persist in cardiac tissue after the initial infection, which could open up the door to reactivation under favorable conditions. Whether this chronic infection contributes to, or initiates, cardiac damage over time, remains a pressing issue in the field of virus-induced heart pathology, and it is directly tied to patients' treatment. Previously, large case studies found that a few viruses: parvovirus B19, coxsackievirus, adenovirus, human herpesvirus 6, cytomegalovirus and Epstein-Barr virus, are most commonly found in human endomyocardial biopsy samples derived from patients experiencing cardiac inflammation, or dilated cardiomyopathy. SARS-CoV-2 infection has also been shown to have cardiovascular consequences. This review examines the role of viral persistence in cardiac inflammation and heart disease, and discusses its implications for patients' outcomes.

Macrophage, a potential targeted therapeutic immune cell for cardiomyopathy

Cardiomyopathy is a major cause of heart failure, leading to systolic and diastolic dysfunction and promoting adverse cardiac remodeling. Macrophages, as key immune cells of the heart, play a crucial role in inflammation and fibrosis. Moreover, exogenous and cardiac resident macrophages are functionally and phenotypically different during cardiac injury. Although experimental evidence has shown that macrophage-targeted therapy is promising in cardiomyopathy, clinical translation remains challenging. In this article, the molecular mechanism of macrophages in cardiomyopathy has been discussed in detail based on existing literature. The issues and considerations of clinical treatment strategies for myocardial fibrosis has also been analyzed.

Resident cardiac macrophages: Heterogeneity and function in health and disease

Understanding tissue macrophage biology has become challenging in recent years due the ever-increasing complexity in macrophage-subset identification and functional characterization. This is particularly important within the myocardium, as we have come to understand that macrophages play multifaceted roles in cardiac health and disease, and heart disease remains the leading cause of death worldwide. Here, we review recent progress in the field, focusing on resident cardiac macrophage heterogeneity, origins, and functions at steady state and after injury. We stratify resident cardiac macrophage functions by the ability of macrophages to either directly influence cardiac physiology or indirectly influence cardiac physiology through orchestrating multi-cellular communication with cardiomyocytes and stromal and immune populations.