The role of myeloid-derived immunosuppressive cells in cardiovascular disease

CCR5-mediated homing of regulatory T cells and monocytic-myeloid derived suppressor cells to dysfunctional endothelium contributes to early atherosclerosis

A disbalance between immune regulatory cells and inflammatory cells is known to drive atherosclerosis. However, the exact mechanism is not clear. Here, we investigated the homing of immune regulatory cells, mainly, regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) subsets in asymptomatic coronary artery disease (CAD) risk factor-exposed young individuals (dyslipidemia [DLP] group) and stable CAD patients (CAD group). Compared with healthy controls (HCs), Tregs frequency was reduced in both DLP and CAD groups but expressed high levels of CCR5 in both groups. The frequency of monocytic-myeloid-derived suppressor cells (M-MDSCs) was increased while polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) were decreased in CAD patients only. Interestingly, although unchanged in frequency, M-MDSCs of the DLP group expressed high levels of CCR5. Serum levels of chemokines (CCL5, CX3CL1, CCL26) and inflammatory cytokines (IL-6, IL-1β, IFN-γ, TNF-α) were higher in the DLP group. Stimulation with inflammatory cytokines augmented CCR5 expression in Tregs and M-MDSCs isolated from HCs. Activated endothelial cells showed elevated levels of CX3CL1 and CCL5 in vitro. Blocking CCR5 with D-Ala-peptide T-amide (DAPTA) increased Treg and M-MDSC frequency in C57Bl6 mice fed a high-fat diet. In accelerated atherosclerosis model, DAPTA treatment led to the formation of smooth muscle-rich plaque with less macrophages. Thus, we show that CCR5-CCL5 axis is instrumental in recruiting Tregs and M-MDSCs to dysfunctional endothelium in the asymptomatic phase of atherosclerosis contributing to atherosclerosis progression. Drugs targeting CCR5 in asymptomatic and CAD risk-factor/s-exposed individuals might be a novel therapeutic regime to diminish atherogenesis.

Increased CD14+HLA-DR-/low myeloid-derived suppressor cells can be regarded as a biomarker on disease severity and response to therapy in acute coronary syndrome

Purpose

This study aimed to investigate the dynamic changes in monocytic myeloid-derived suppressor cells (M-MDSCs) and their implications in the pathogenesis of acute coronary syndrome (ACS), shedding light on potential therapeutic targets.

Experimental Design

Peripheral blood samples were collected from 68 ACS patients, 35 stable angina pectoris (SAP) patients, and 30 healthy controls (HC). Multi-parameter flow cytometry was employed for analysis of M-MDSCs, explored with disease characteristics and progression.

Results

ACS patients exhibited an increased frequency of circulating M-MDSCs compared to SAP patients and HC. M-MDSCs levels demonstrated associations with ACS type, coronary artery lesions, multi-vessel disease, and cardiac dysfunction severity. Higher M-MDSCs levels were found in obese patients. Notably, therapy led to a significant decrease in M-MDSCs frequency. Furthermore, ACS patients exhibited elevated levels of interleukin (IL)-6, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-α (TNF-α) in the cytokine profile associated with M-MDSCs. Increased expression of arginase-1(Arg-1) was observed in ACS patients, with positive correlations between M-MDSCs levels and IL-6, GM-CSF, and Arg-1 expression. The diagnostic performance of triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and M-MDSCs levels varied in predicting the severity of coronary artery stenosis, with TG showing higher specificity, HDL-C displaying higher sensitivity, and M-MDSCs levels demonstrating balanced sensitivity and specificity.

Conclusions

Assessment of M-MDSCs frequency holds promise as a predictive marker for disease progression and therapy response of coronary artery stenosis. The elevated presence of M-MDSCs suggests their potential role in modulating ACS-related inflammation.

The Role of Alarmins in the Pathogenesis of Atherosclerosis and Myocardial Infarction

Atherosclerosis is a condition that is associated with lipid accumulation in the arterial intima. Consequently, the enlarging lesion, which is also known as an atherosclerotic plaque, may close the blood vessel lumen, thus leading to organ ischaemia. Furthermore, the plaque may rupture and initiate the formation of a thrombus, which can cause acute ischaemia. Atherosclerosis is a background pathological condition that can eventually lead to major cardiovascular diseases such as acute coronary syndrome or ischaemic stroke. The disorder is associated with an altered profile of alarmins, stress response molecules that are secreted due to cell injury or death and that induce inflammatory responses. High-mobility group box 1 (HMGB1), S100 proteins, interleukin-33, and heat shock proteins (HSPs) also affect the behaviour of endothelial cells and vascular smooth muscle cells (VSMCs). Thus, alarmins control the inflammatory responses of endothelial cells and proliferation of VSMCs, two important processes implicated in the pathogenesis of atherosclerosis. In this review, we will discuss the role of alarmins in the pathophysiology of atherosclerosis and myocardial infarction.

Modulation of myeloid-derived suppressor cell functions by oral inflammatory diseases and important oral pathogens

The oral cavity presents a diverse microbiota in a dynamic balance with the host. Disruption of the microbial community can promote dysregulation of local immune response which could generate oral diseases. Additionally, alterations in host immune system can result in inflammatory disorders. Different microorganisms have been associated with establishment and progression of the oral diseases. Oral cavity pathogens/diseases can modulate components of the inflammatory response. Myeloid-derived suppressor cells (MDSCs) own immunoregulatory functions and have been involved in different inflammatory conditions such as infectious processes, autoimmune diseases, and cancer. The aim of this review is to provide a comprehensive overview of generation, phenotypes, and biological functions of the MDSCs in oral inflammatory diseases. Also, it is addressed the biological aspects of MDSCs in presence of major oral pathogens. MDSCs have been mainly analyzed in periodontal disease and Sjögren's syndrome and could be involved in the outcome of these diseases. Studies including the participation of MDSCs in other important oral diseases are very scarce. Major oral bacterial and fungal pathogens can modulate expansion, subpopulations, recruitment, metabolism, immunosuppressive activity and osteoclastogenic potential of MDSCs. Moreover, MDSC plasticity is exhibited in presence of oral inflammatory diseases/oral pathogens and appears to be relevant in the disease progression and potentially useful in the searching of possible treatments. Further analyses of MDSCs in oral cavity context could allow to understand the contribution of these cells in the fine-tuned balance between host immune system and microorganism of the oral biofilm, as well as their involvement in the development of oral diseases when this balance is altered.