Regulatory T cells and cardiovascular diseases

Regulatory T cells: a promising new therapeutic target in ventricular remodeling after myocardial infarction

Myocardial infarction (MI) is one of the leading causes of death worldwide. It is triggered by thrombosis or vascular occlusion. After MI, damaged cardiomyocytes are replaced by scar tissue, leading to systolic and diastolic dysfunction, followed by adverse remodeling. Regulatory T cells (Tregs), as major immune cells, play a crucial role in post-MI inflammation and immunomodulation. Tregs improve cardiac remodeling after MI through various mechanisms, including inhibiting inflammatory cell infiltration, inducing anti-inflammatory macrophages, suppressing cell apoptosis, regulating fibroblast function, and promoting angiogenesis. The modulation of Tregs number or function may provide novel methods for improving post-MI remodeling. This review describes the immunoregulatory roles of Tregs, their regulatory mechanisms in post-MI ventricular remodeling, and the prospects and challenges for clinical application. However, the exact molecular mechanisms of Tregs in ventricular remodeling remain to be investigated. Although most of the current studies are at the preclinical stage, they hold great potential for further application in the future.

Longitudinal Variations in Th and Treg Cells Before and After Percutaneous Coronary Intervention, and Their Intercorrelations and Prognostic Value in Acute Syndrome Patients

T helper (Th) and regulatory T (Treg) cells regulate atherosclerosis, plaque, inflammation to involve in acute coronary syndrome (ACS). The current study aimed to investigate the clinical implications of Th and Treg cells in ACS patients receiving percutaneous coronary intervention (PCI). Blood Th1, Th2, Th17 and Treg cells were detected in 160 ACS patients before PCI, after PCI, at 1 month (M). Short physical performance battery (SPPB) at M1/M3 and major adverse cardiac event (MACE) during follow-ups were evaluated. Th1 and Th17 both showed upward trends during PCI, then greatly declined at M1 (P < 0.001). Th2 exhibited an upward trend during PCI but decreased slightly at M1 (P < 0.001). Treg remained stable during PCI but elevated at M1 (P < 0.001). Moreover, a positive correlation between Th1 and Th17, a negative correlation between Th17 and Treg, were discovered at several timepoints (most P < 0.050). Interestingly, the receiver operating curve (ROC) analyses revealed that Th1 [area under curve (AUC) between 0.633-0.645] and Th17 (AUC between 0.626-0.699) exhibited values estimating SPPB score <= 6 points at M1 or M3 to some extent. Importantly, Th1 (AUC between 0.708-0.710), Th17 (AUC between 0.694-0.783), and Treg (AUC between 0.706-0.729) predicted MACE risk. Multivariate models involving Th and Treg cells along with other characteristics revealed acceptable values estimating SPPB score <= 6 points at M1 or M3 (AUC between 0.690-0.813), and good values predicting MACE risk (AUC between 0.830-0.971). Dynamic variations in Th and Treg cells can predict the prognosis of ACS patients receiving PCI.

Causal relationship between immune cells and risk of heart failure: evidence from a Mendelian randomization study

Background

Heart failure (HF) is a clinical syndrome resulting from structural damage or dysfunction of the heart. Previous investigations have highlighted the critical involvement of immune cells in the progression of heart failure, with distinct roles attributed to different types of immune cells. The objective of the current research was to explore the potential connections between immune characteristics and the development of HF, as well as to ascertain the nature of the causality between these factors.

Methods

To assess the causal association of immunological profiles with HF based on publicly available genome-wide studies, we employed a two-sample Mendelian randomization technique, utilizing the inverse variance weighted (IVW) method as our primary analytical approach. In addition, we assessed heterogeneity and cross-sectional pleiotropy through sensitivity analyses.

Results

A two-sample Mendelian randomization (MR) analysis was conducted using IVW as the primary method. At a significance level of 0.001, we identified 40 immunophenotypes that have a significant causal relationship with HF. There is a significant causal relationship between these phenotypes and heart failure. These immunophenotypes, 8 of which were in B cells, 5 in cDC, 2 in T cell maturation stage, 2 in monocytes, 3 in myeloid cells, 7 in TBNK and 13 in Treg. Sensitivity analyses were conducted to validate the strength and reliability of the MR findings.

Conclusions

Our study suggests that there appears to be a causal effect between multiple immune cells on heart failure. This discovery provides a new avenue for the development of therapeutic treatments for HF and a new target for drug development.

Establishment and evaluation of a risk prediction model for coronary heart disease in primary Sjögren's syndrome based on peripheral blood IL-6 and Treg percentages

Objective

This study aims to establish and evaluate a risk prediction model for coronary heart disease (CHD) in patients with primary Sjögren's syndrome (pSS) based on peripheral blood levels of interleukin-6 (IL-6) and the percentage of regulatory T cells (Treg%). This model is intended to facilitate the timely identification of high-risk patients and the implementation of preventive measures.

Methods

Clinical data were collected from 120 pSS patients who visited the Second Hospital of Shanxi Medical University between November 2021 and September 2023. Patients were classified into pSS and pSS-CHD groups according to CHD diagnostic criteria. Peripheral blood lymphocyte subsets and cytokine levels were assessed using flow cytometry. Univariate and multivariate logistic regression analyses were employed to identify independent risk factors, and a nomogram was constructed based on these factors. The model's discriminatory ability, calibration, and clinical utility were evaluated using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis.

Results

The univariate and multivariate logistic regression analyses identified several independent risk factors for CHD in pSS patients: erythrocyte sedimentation rate (ESR) (OR=1.10, P=0.019), triglycerides (TG) (OR=3.67, P=0.041), IL-6 (OR=1.29, P=0.048), and Treg% (OR=0.25, P=0.004). A nomogram incorporating these factors demonstrated an area under the curve (AUC) of 0.96, indicating excellent predictive performance, and showed good calibration (P=0.599), suggesting significant clinical applicability. Furthermore, Treg% exhibited a negative correlation with cholesterol (CHOL) and low-density lipoprotein cholesterol (LDL-C) levels, while IL-6 showed a positive correlation with CHOL and LDL-C levels. TG was positively correlated with C-reactive protein (CRP).

Conclusion

This study successfully developed a risk prediction model based on peripheral blood IL-6 and Treg% levels, providing critical evidence for the early identification and personalized prevention of CHD in pSS patients, with potential clinical implications.

Macrophages in vascular disease: Roles of mitochondria and metabolic mechanisms

Macrophages are a dynamic cell type of the immune system implicated in the pathophysiology of vascular diseases and are a major contributor to pathological inflammation. Excessive macrophage accumulation, activation, and polarization is observed in aortic aneurysm (AA), atherosclerosis, and pulmonary arterial hypertension. In general, macrophages become activated and polarized to a pro-inflammatory phenotype, which dramatically changes cell behavior to become pro-inflammatory and infiltrative. These cell types become cumbersome and fail to be cleared by normal mechanisms such as autophagy. The result is a hyper-inflammatory environment causing the recruitment of adjacent cells and circulating immune cells to further augment the inflammatory response. In AA, this leads to excessive ECM degradation and chemokine secretion, ultimately causing macrophages to dominate the immune cell landscape in the aortic wall. In atherosclerosis, monocytes are recruited to the vascular wall, where they polarize to the pro-inflammatory phenotype and induce inflammatory pathway activation. This leads to the development of foam cells, which significantly contribute to neointima and necrotic core formation in atherosclerotic plaques. Pro-inflammatory macrophages, which affect other vascular diseases, present with fragmented mitochondria and corresponding metabolic dysfunction. Targeting macrophage mitochondrial dynamics has proved to be an exciting potential therapeutic approach to combat vascular disease. This review will summarize mitochondrial and metabolic mechanisms of macrophage activation, polarization, and accumulation in vascular diseases.

Effects and mechanisms of the myocardial microenvironment on cardiomyocyte proliferation and regeneration

The adult mammalian cardiomyocyte has a limited capacity for self-renewal, which leads to the irreversible heart dysfunction and poses a significant threat to myocardial infarction patients. In the past decades, research efforts have been predominantly concentrated on the cardiomyocyte proliferation and heart regeneration. However, the heart is a complex organ that comprises not only cardiomyocytes but also numerous noncardiomyocyte cells, all playing integral roles in maintaining cardiac function. In addition, cardiomyocytes are exposed to a dynamically changing physical environment that includes oxygen saturation and mechanical forces. Recently, a growing number of studies on myocardial microenvironment in cardiomyocyte proliferation and heart regeneration is ongoing. In this review, we provide an overview of recent advances in myocardial microenvironment, which plays an important role in cardiomyocyte proliferation and heart regeneration.

Therapeutic potential of natural products and underlying targets for the treatment of aortic aneurysm

Aortic aneurysm is a vascular disease characterized by irreversible vasodilatation that can lead to dissection and rupture of the aortic aneurysm, a life-threatening condition. Thoracic aortic aneurysm (TAA) and abdominal aortic aneurysm (AAA) are two main types. The typical treatments for aortic aneurysms are open surgery and endovascular aortic repair, which are only indicated for more severe patients. Most patients with aneurysms have an insidious onset and slow progression, and there are no effective drugs to treat this stage. The inability of current animal models to perfectly simulate all the pathophysiological states of human aneurysms may be the key to this issue. Therefore, elucidating the molecular mechanisms of this disease, finding new therapeutic targets, and developing effective drugs to inhibit the development of aneurysms are the main issues of current research. Natural products have been applied for thousands of years to treat cardiovascular disease (CVD) in China and other Asian countries. In recent years, natural products have combined multi-omics, computational biology, and integrated pharmacology to accurately analyze drug components and targets. Therefore, the multi-component and multi-target complexity of natural products have made them a potentially ideal treatment for multifactorial diseases such as aortic aneurysms. Natural products have regained popularity worldwide. This review provides an overview of the known natural products for the treatment of TAA and AAA and searches for potential cardiovascular-targeted natural products that may treat TAA and AAA based on various cellular molecular mechanisms associated with aneurysm development.

Trained Innate Immunity in Animal Models of Cardiovascular Diseases

Acquisition of immunological memory is an important evolutionary strategy that evolved to protect the host from repetitive challenges from infectious agents. It was believed for a long time that memory formation exclusively occurs in the adaptive part of the immune system with the formation of highly specific memory T cells and B cells. In the past 10-15 years, it has become clear that innate immune cells, such as monocytes, natural killer cells, or neutrophil granulocytes, also have the ability to generate some kind of memory. After the exposure of innate immune cells to certain stimuli, these cells develop an enhanced secondary response with increased cytokine secretion even after an encounter with an unrelated stimulus. This phenomenon has been termed trained innate immunity (TI) and is associated with epigenetic modifications (histone methylation, acetylation) and metabolic alterations (elevated glycolysis, lactate production). TI has been observed in tissue-resident or circulating immune cells but also in bone marrow progenitors. Risk-factors for cardiovascular diseases (CVDs) which are associated with low-grade inflammation, such as hyperglycemia, obesity, or high salt, can also induce TI with a profound impact on the development and progression of CVDs. In this review, we briefly describe basic mechanisms of TI and summarize animal studies which specifically focus on TI in the context of CVDs.