Regulatory T cells in atherosclerosis and strategies to induce the endogenous atheroprotective immune response

Subpopulations of regulatory T cells are associated with subclinical atherosclerotic plaques, levels of LDL, and cardiorespiratory fitness in the elderly

BACKGROUND

Atherosclerosis forms the pathological basis for the development of cardiovascular disease. Since pathological processes initially develop without clinically relevant symptoms, the identification of early markers in the subclinical stage plays an important role for initiating early interventions. There is evidence that regulatory T cells (Tregs) are involved in the development of atherosclerosis. Therefore, the present study aimed to identify and investigate associations with Tregs and their subsets in a cohort of healthy elderly individuals with and without subclinical atherosclerotic plaques (SAP). In addition, various lifestyle and risk factors, such as cardiorespiratory fitness, were investigated as associated signatures.

METHODS

A cross-sectional study was performed in 79 participants (male: n = 50; age = 63.6 ± 3.7 years; body mass index = 24.9 ± 3.1 kg/m²; mean ± SD) who had no previous diagnosis of chronic disease and were not taking medication. Ultrasound of the carotids to identify SAP, cardiovascular function measurement for vascular assessment and a cardiorespiratory fitness test to determine peak oxygen uptake were performed. Additionally, tests were conducted to assess blood lipids and determine glucose levels. Immunophenotyping of Tregs and their subtypes (resting (rTregs) and effector/memory (mTregs)) was performed by 8-chanel flow cytometry. Participants were categorized according to atherosclerotic plaque status. Linear and logistic regression models were used to analyze associations between parameters.

RESULTS

SAP was detected in a total of 29 participants. The participants with plaque were older (64.8 ± 3.6 years vs. 62.9 ± 3.5 years) and had higher peripheral systolic blood pressure (133.8 ± 14.7 mmHg vs. 125.8 ± 10.9 mmHg). The participants with SAP were characterized by a lower percentage of rTregs (28.8% ± 10.7% vs. 34.6% ± 10.7%) and a higher percentage of mTregs (40.3% ± 14.7% vs. 30.0% ± 11.9%). Multiple logistic regression identified age (odds ratio (OR) = 1.20 (95% confidence interval (95%CI): 1.01-1.42)) and mTregs (OR = 1.05 (95%CI: 1.02-1.10)) as independent risk factors for SAP. Stepwise linear regression could reveal an association of peak oxygen uptake (β = 0.441), low-density lipoprotein (LDL) (β = -0.096), and SAP (β = 6.733) with mTregs and LDL (β = 0.104) with rTregs.

CONCLUSION

While at an early stage of SAP, the total proportion of Tregs gives no indication of vascular changes, this is indicated by a shift in the Treg subgroups. Factors such as serum LDL or cardiopulmonary fitness may be associated with this shift and may also be additional diagnostic indicators. This could be used to initiate lifestyle-based preventive measures at an early stage, which may have a protective effect against disease progression.

T-cell lymphocytes' aging clock: telomeres, telomerase and aging

Aging is the decline of physiological capabilities required for life maintenance and reproduction over time. The human immune cells, including T-cells lymphocytes, undergo dramatic aging-related changes, including those related to telomeres and telomerase. It was demonstrated that telomeres and telomerase play crucial roles in T-cell differentiation, aging, and diseases, including a well-documented link between short telomeres and telomerase activation demonstrated in several T-cells malignancies. Herein, we provide a comprehensive review of the literature regarding T-cells' telomeres and telomerase in health and age related-diseases.

Sialic acid as the potential link between lipid metabolism and inflammation in the pathogenesis of atherosclerosis

In the modern world, cardiovascular diseases have a special place among the most common causes of death. Naturally, this widespread problem cannot escape the attention of scientists and researchers. One of the main conditions preceding the development of fatal cardiovascular diseases is atherosclerosis. Despite extensive research into its pathogenesis and possible prevention and treatment strategies, many gaps remain in our understanding of this disease. For example, the concept of multiple low-density lipoprotein modifications was recently stated, in which desialylation is of special importance. Apart from this, sialic acids are known to be important contributors to processes such as endothelial dysfunction and inflammation, which in turn are major components of atherogenesis. In this review, we have collected information on sialic acid metabolism, analyzed various aspects of its implication in atherosclerosis at different stages, and provided an overview of the role of particular groups of enzymes responsible for sialic acid metabolism in the context of atherosclerosis.

Identification of key genes and pathways in atherosclerosis using integrated bioinformatics analysis

BACKGROUND

Atherosclerosis (AS) is a chronic inflammatory disease that might induce severe cardiovascular events, such as myocardial infarction and cerebral infarction. These risk factors in the pathogenesis of AS remain uncertain and further research is needed. This study aims to explore the potential molecular mechanisms of AS by bioinformatics analyses.

METHODS

GSE100927 gene expression profiles, including 69 AS samples and 35 healthy controls, were downloaded from Gene Expression Omnibus database and indenfied for key genes and pathways in AS.

RESULTS

A total of 443 differentially expressed genes (DEGs) between control and AS were identified, including 323 down-regulated genes and 120 up-regulated genes. The Gene ontology terms enriched by the up-regulated DEGs were associated with the regulation of leukocyte activation, endocytic vesicle, and cytokine binding, while the down-regulated DEGs were associated with negative regulation of cell growth, extracellular matrix, and G protein-coupled receptor binding. KEGG pathway analysis showed that the up-regulated DEGs were enriched in Osteoclast differentiation and Phagosome, while the down-regulated DEGs were enriched in vascular smooth muscle contraction and cGMP-PKG signaling pathway. Using the modular analysis of Cytoscape, we identified 3 modules mainly involved in Leishmaniasis and Osteoclast differentiation. The GSEA analysis showed the up-regulated gene sets were enriched in the ribosome, ascorbated metabolism, and propanoate metabolism. The LASSO Cox regression analysis showed the top 3 genes were TNF, CX3CR1, and COL1R1. Finally, we found these immune cells were conferred significantly higher infiltrating density in the AS group.

CONCLUSIONS

Our data showed the pathway of Osteoclast differentiation and Leishmaniasis was involved in the AS process and we developed a three-gene model base on the prognosis of AS. These findings clarified the gene regulatory network of AS and may provide a novel target for AS therapy.

Identification of key transcription factors and their functional role involved in Salmonella typhimurium infection in chicken using integrated transcriptome analysis and bioinformatics approach

Salmonella enterica serovar typhimurium is the cause of significant morbidity and mortality worldwide that causes economic losses to poultry and is able to cause infection in humans. Indigenous chicken breeds are a potential source of animal protein and have the added advantage of being disease resistant. An indigenous chicken, Kashmir favorella and commercial broiler were selected for understanding the mechanism of disease resistance. Following infection in Kashmir favorella, three differentially expressed genes Nuclear Factor Kappa B (NF-κB1), Forkhead Box Protein O3 (FOXO3) and Paired box 5 (Pax5) were identified. FOXO3, a transcriptional activator, is the potential marker of host resistance in Salmonella infection. NF-κB1 is an inducible transcription factor which lays the foundation for studying gene network of the innate immune response of Salmonella infection in chicken. Pax5 is essential for differentiation of pre-B cells into mature B cell. The real time PCR analysis showed that in response to Salmonella Typhimurium infection a remarkable increase of NF-κB1 (P˂0.01)_, FOXO3 (P˂0.01) gene expression in liver and Pax5 (P˂0.01) gene expression in spleen of Kashmir favorella was observed. The protein-protein interaction (PPI) and protein-TF interaction network by STRINGDB analysis suggests that FOXO3 is a hub gene in the network and is closely related to Salmonella infection along with NF-κB1. All the three differentially expressed genes (NF-κB1, FOXO3 and PaX5) showed their influence on 12 interacting proteins and 16 TFs, where cyclic adenosine monophosphate Response Element Binding protein (CREBBP), erythroblast transformation-specific (ETSI), Tumour-protein 53(TP53I), IKKBK, lymphoid enhancer-binding factor-1 (LEF1), and interferon regulatory factor-4 (IRF4) play role in immune responses. This study shall pave the way for newer strategies for treatment and prevention of Salmonella infection and may help in increasing the innate disease resistance.

EndMT-derived mesenchymal stem cells: a new therapeutic target to atherosclerosis treatment

Cardiovascular diseases, such as coronary artery disease and stroke, are the main threats to human health worldwide. Atherosclerosis, a chronic inflammatory disorder, plays a role as an initiator of all of the above-mentioned diseases. Cell therapy for diseases has attracted widespread attention. Mesenchymal stem cells (MSCs) are a type of stem cell that still exist in adults and have the characteristics of self-renewal ability, pluripotent differentiation potential, immunomodulation, tissue regeneration, anti-inflammation and low immunogenicity. In light of the properties of MSCs, some researchers have begun to target MSCs to create a possible way to alleviate atherosclerosis. Most of these studies are focused on MSC transplantation, injecting MSCs to modulate macrophages, the key inflammatory cell in atherosclerosis plaque. According to recent studies, researchers found that endothelial-to-mesenchymal transition (EndMT) has something to do with atherosclerosis development. A new cell type MSC might also appear during the EndMT process. In this article, we summarize the characteristics of MSCs, the latest progress of MSC research and its application prospects, and in view of the process of EndMT occurring in atherosclerosis, we propose some new ideas for the treatment of atherosclerosis by targeting MSCs.

Interleukin-35 ameliorates cardiovascular disease by suppressing inflammatory responses and regulating immune homeostasis

The immune response is of great significance in the initiation and progression of a diversity of cardiovascular diseases involving pro-and anti-inflammatory cytokines. Interleukin-35 (IL-35), a cytokine of the interleukin-12 family, is a novel anti-inflammation and immunosuppressive cytokine, maintaining inflammatory suppression and regulating immune homeostasis. The role of IL-35 in cardiovascular diseases (CVDs) has aroused enthusiastic attention, a diversity of experimental or clinical evidence has indicated that IL-35 potentially has a pivot role in protecting against cardiovascular diseases, especially atherosclerosis and myocarditis. In this review, we initiate an overview of the relationship between Interleukin-35 and cardiovascular diseases, including atherosclerosis, acute coronary syndrome, pulmonary hypertension, abdominal aortic aneurysm, heart failure, myocardial ischemia-reperfusion, aortic dissection and myocarditis. Although the specific molecular mechanisms entailing the protective effects of IL-35 remain an unsolved issue, targeted therapies with IL-35 might provide a promising and effective solution to prevent and cure cardiovascular diseases.

Lactococcus lactis‑fermented spinach juice suppresses LPS‑induced expression of adhesion molecules and inflammatory cytokines through the NF‑κB pathway in HUVECs

Spinach (Spinacia oleracea L.), a green leafy vegetable, is widely regarded as a functional food due to its biological activities; however, to the best of our knowledge, there are no previous studies that have investigated the protective effects of fermented spinach against endothelial dysfunction and its underlying mechanisms. Therefore, this study investigated the effects and possible mechanisms of action of fresh spinach juice (S.juice) and fermented S.juice on lipopolysaccharide (LPS)-induced inflammatory responses in human umbilical vein endothelial cells (HUVECs). The HUVECs were treated with S.juice and fermented S.juice for 18 h before LPS exposure, and the levels of cytokines and chemokines, such as monocyte chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6), were detected using enzyme-linked immunosorbent assays (ELISA). Furthermore, to examine the changes in inflammatory responses to the two treatments, immunofluorescence analysis was used to visualize the nuclear translocation of nuclear factor-κB (NF-κB). Western blot analysis was also performed to detect the differences in the expression of endothelial cell adhesion molecules, specifically vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1). Both S.juice and fermented S.juice inhibited the LPS-induced expression of MCP-1 and IL-6, and suppressed VCAM-1 and ICAM-1. Additionally, fermented S.juice inhibited the LPS-induced activation of NF-κB and degradation of the inhibitor of NF-κB (IκBα) in an LPS dose-dependent manner. These results suggest that the anti-inflammatory effect of vitamin K₂-enriched fermented S.juice is mediated by the suppression of the NF-κB pathway, suggesting its potential as a novel therapeutic candidate for inflammatory cardiovascular disease.

Targeting Cell-Specific Molecular Mechanisms of Innate Immunity in Atherosclerosis

Mechanisms of innate immunity contribute to inflammation, one of the major underlying causes of atherogenesis and progression of atherosclerotic vessel disease. How immune cells exactly contribute to atherosclerosis and interact with molecules of cholesterol homeostasis is still a matter of intense research. Recent evidence has proposed a potential role of previously underappreciated cell types in this chronic disease including platelets and dendritic cells (DCs). The pathophysiology of atherosclerosis is studied in models with dysfunctional lipid homeostasis and several druggable molecular targets are derived from these models. Specific therapeutic approaches focussing on these immune mechanisms, however, have not been successfully introduced into everyday clinical practice, yet. This review highlights molecular insights into immune processes related to atherosclerosis and potential future translational approaches targeting these molecular mechanisms.

The effect of fingolimod on regulatory T cells in a mouse model of brain ischaemia

Background

The role of the immune system in stroke is well-recognised. Fingolimod, an immunomodulatory agent licensed for the management of relapsing-remitting multiple sclerosis, has been shown to provide benefit in rodent models of stroke. Its mechanism of action, however, remains unclear. We hypothesised fingolimod increases the number and/or function of regulatory T cells (Treg), a lymphocyte population which promotes stroke recovery. The primary aim of this study was to rigorously investigate the effect of fingolimod on Tregs in a mouse model of brain ischaemia. The effect of fingolimod in mice with common stroke-related comorbidities (ageing and hypercholesteremia) was also investigated.

Methods

Young (15–17 weeks), aged C57BL/6 mice (72–73 weeks), and ApoE^−/− mice fed a high-fat diet (20–21 weeks) underwent permanent electrocoagulation of the left middle cerebral artery. Mice received either saline or fingolimod (0.5 mg/kg or 1 mg/kg) at 2, 24, and 48 h post-ischaemia via intraperitoneal injection. Another cohort of young mice (8–9, 17–19 weeks) received short-term (5 days) or long-term (10 days) fingolimod (0.5 mg/kg) treatment. Flow cytometry was used to quantify Tregs in blood, spleen, and lymph nodes. Immunohistochemistry was used to quantify FoxP3+ cell infiltration into the ischaemic brain.

Results

Fingolimod significantly increased the frequency of Tregs within the CD4+ T cell population in blood and spleen post-ischaemia in all three mouse cohorts compared to untreated ischemic mice. The highest splenic Treg frequency in fingolimod-treated mice was observed in ApoE^−/− mice (9.32 ± 1.73% vs. 7.8 ± 3.01% in young, 6.09 ± 1.64% in aged mice). The highest circulating Treg frequency was also noted in ApoE^−/− mice (8.39 ± 3.26% vs. 5.43 ± 2.74% in young, 4.56 ± 1.60% in aged mice). Fingolimod significantly increased the number of FoxP3+ cells in the infarct core of all mice. The most pronounced effects were seen when mice were treated for 10 days post-ischaemia.

Conclusions

Fingolimod increases Treg frequency in spleen and blood post-ischaemia and enhances the number of FoxP3+ cells in the ischaemic brain. The effect of fingolimod on this regulatory cell population may underlie its neuroprotective activity and could be exploited as part of future stroke therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02083-5.

Downregulation of G3BP2 reduces atherosclerotic lesions in ApoE-/- mice

BACKGROUND AND AIMS

Atherosclerosis is mainly caused by stress in arterial microenvironments, which results in the formation of stress granules as a consequence of the stress response. As the core protein of stress granules, GTPase-activating protein (SH3 domain)-binding protein 2 (G3BP2) is known to play pivotal roles in tumour initiation, viral infection and Alzheimer's disease, but the role of G3BP2 in atherosclerosis development is poorly understood. Previous studies have shown that vaccination with epitopes from self-antigens could reduce atherosclerotic lesions. Here, we investigated the effect of immunizing ApoE^-/- mice with G3BP2 peptides, and whether this immunization exerted an anti-atherogenic effect.

METHODS AND RESULTS

In our study, ApoE^-/- mice were fed a high-fat diet for 12 weeks from 8 to 20 weeks of age. Then, using a repetitive multiple site strategy, the mice were immunized with a Keyhole limpet haemocyanin (KLH) conjugated G3BP2 peptide for 2 weeks from weeks 16 to 18. High levels of G3BP2 antibodies were detectable before sacrifice. Histological analyses showed that the number of atherosclerotic lesions in ApoE^-/- mice was significantly reduced following G3BP2 immunotherapy. The levels of pro-inflammatory cytokines and macrophages were also greatly decreased, while the collagen content of the plaques showed significant increase. Furthermore, knocking down G3BP2 in ApoE^-/- mice reduced the number of lesions compared to ApoE^-/- mice fed a high-fat diet for eight weeks. In vitro studies demonstrated that G3BP2 regulated ox-LDL-induced inflammation in HUVECs via controlling the localization of IκBα.

CONCLUSIONS

Immunization with the G3BP2 peptide antigen or knocking down of G3BP2 significantly decreased early atherosclerotic plaques in the ApoE^-/- mouse model of atherosclerosis. G3BP2 is a promising potential target for atherosclerosis therapy.

An Injectable Hydrogel Platform for Sustained Delivery of Anti-inflammatory Nanocarriers and Induction of Regulatory T Cells in Atherosclerosis

Chronic unresolved vascular inflammation is a critical factor in the development of atherosclerosis. Cardiovascular immunotherapy has therefore become a recent focus for treatment, with the objective to develop approaches that can suppress excessive inflammatory responses by modulating specific immune cell populations. A benefit of such immunomodulatory strategies is that low dosage stimulation of key immune cell populations, like antigen presenting cells, can subsequently propagate strong proliferation and therapeutic responses from effector cells. We have previously demonstrated that intravenous injections of anti-inflammatory nanocarriers provided atheroprotection that was mediated by regulatory T cells (Tregs) upregulated in lymphoid organs and atherosclerotic lesions. Here, we demonstrate an injectable filamentous hydrogel depot (FM-depot) engineered for low dosage, sustained delivery of anti-inflammatory nanocarriers. The bioactive form of vitamin D (aVD; 1, 25-Dihydroxyvitamin D3), which inhibits pro-inflammatory transcription factor NF-κB via the intracellular nuclear hormone receptor vitamin D receptor (VDR), was stably loaded into poly(ethylene glycol)-block-poly(propylene sulfide) (PEG-b-PPS) filomicelles. These aVD-loaded filaments underwent morphological transitions to release monodisperse drug-loaded micelles upon oxidation. This cylinder-to-micelle transition was characterized in vitro by cryogenic transmission electron microscopy (CryoTEM) and small angle X-ray scattering (SAXS). Following crosslinking with multi-arm PEG for in situ gelation, aVD-loaded FM-depots maintained high levels of Foxp3⁺ Tregs in both lymphoid organs and atherosclerotic lesions for weeks following a single subcutaneous injection into ApoE^-/- mice. FM-depots therefore present a customizable delivery platform to both develop and test nanomedicine-based approaches for anti-inflammatory cardiovascular immunotherapy.

The significance of Agaricus blazei as an immunomodulator of the level of IL-17 in Balb/C mice with atherosclerosis

Atherosclerosis is a disease caused by an inflammatory response which involved the interaction between endothelial cells, macrophages and lymphocytes, and is closely related to IL-17 regulation. This study is important to investigate the activity of Agaricusblazei in modulating the immunological activity based on the profile of CD4⁺IL-17⁺, CD8⁺IL-17⁺, and CD11b⁺ IL-17⁺ in high-fat diet (HFD)-induced Balb/c mice. Mice in dietary groups were fed with HFD and then fed with A. blazei extract with three different doses including D1 (100 mg/kg BW), D2 (200 mg/kg BW), and D3 (400 mg/kg BW) once a day for 12 weeks. The cells were analyzed using flow cytometry and tested statistically with one-way ANOVA with α = 0.05 by using SPSS 16.00 software. The results showed that mice with HFD treatment had a higher level of Lp-PLA2 (atherosclerosis marker) compared with the control group (data not shown). The level of IL-17 in the atherosclerotic mice in the D1 group was significantly depleted compared to the control group. Of the three doses above, D1 may be an optimal dose to minimize or prevent the damage from atherosclerosis than the other doses.

Immune-Inflammatory Responses in Atherosclerosis: The Role of Myeloid Cells

Inflammation plays a key role in the initiation and progression of atherosclerosis and can be caused by multiple agents, including increased concentration of circulating low-density lipoprotein (LDL) cholesterol. Areas of the arterial wall affected by atherosclerosis are enriched with lymphocytes and dendritic cells (DCs). Atherosclerotic plaques contain a variety of proinflammatory immune cells, such as macrophages, DCs, T cells, natural killer cells, neutrophils and others. Intracellular lipid accumulation in atherosclerotic plaque leads to formation of so-called foam cells, the cytoplasm of which is filled with lipid droplets. According to current understanding, these cells can also derive from the immune cells that engulf lipids by means of phagocytosis. Macrophages play a crucial role in the initial stages of atherogenesis by engulfing oxidized LDL (oxLDL) in the intima that leads to their transformation to foam cells. Dying macrophages inside the plaque form a necrotic core that further aggravates the lesion. Proinflammatory DCs prime differentiation of naïve T cells to proinflammatory Th1 and Th17 subsets. In this review, we discuss the roles of cell types of myeloid origin in atherosclerosis-associated inflammation.

Sialic acid metabolism as a potential therapeutic target of atherosclerosis

Sialic acid (Sia), the acylated derivative of the nine-carbon sugar neuraminic acid, is a terminal component of the oligosaccharide chains of many glycoproteins and glycolipids. In light of its important biological and pathological functions, the relationship between Sia and coronary artery disease (CAD) has been drawing great attentions recently. Large-scale epidemiological surveys have uncovered a positive correlation between plasma total Sia and CAD risk. Further research demonstrated that N-Acetyl-Neuraminic Acid, acting as a signaling molecule, triggered myocardial injury via activation of Rho/ROCK-JNK/ERK signaling pathway both in vitro and in vivo. Moreover, there were some evidences showing that the aberrant sialylation of low-density lipoprotein, low-density lipoprotein receptor and blood cells was involved in the pathological process of atherosclerosis. Significantly, the Sia regulates immune response by binding to sialic acid-binding immunoglobulin-like lectin (Siglecs). The Sia-Siglecs axis is involved in the immune inflammation of atherosclerosis. The generation of Sia and sialylation of glycoconjugate both depend on many enzymes, such as sialidase, sialyltransferase and trans-sialidase. Abnormal activation or level of these enzymes associated with atherosclerosis, and inhibitors of them might be new CAD treatments. In this review, we focus on summarizing current understanding of Sia metabolism and of its relevance to atherosclerosis.

The Role of Mesenchymal Stem Cells in Atherosclerosis: Prospects for Therapy via the Modulation of Inflammatory Milieu

Atherosclerosis is a chronic, inflammatory disease that mainly affects the arterial intima. The disease is more prevalent in middle-age and older individuals with one or more cardiovascular risk factors, including dyslipidemia, hypertension, diabetes, smoking, obesity, and others. The beginning and development of atherosclerosis has been associated with several immune components, including infiltration of inflammatory cells, monocyte/macrophage-derived foam cells, and inflammatory cytokines and chemokines. Mesenchymal stem cells (MSCs) originate from several tissue sources of the body and have self-renewal and multipotent differentiation characteristics. They also have immunomodulatory and anti-inflammatory properties. Recently, it was shown that MSCs have a regulatory role in plasma lipid levels. In addition, MSCs have shown to have promising potential in terms of treatment strategies for several diseases, including those with an inflammatory component. In this regard, transplantation of MSCs to patients with atherosclerosis has been proposed as a novel strategy in the treatment of this disease. In this review, we summarize the current advancements regarding MSCs for the treatment of atherosclerosis.

Interleukin-17 production by CD4+CD45RO+Foxp3+ T cells in peripheral blood of patients with atherosclerosis

Introduction

T regulatory cells (Tregs) are known as immunoregulatory cells that are reduced in atherosclerosis. Tregs are a part of crosstalk between the immune system and lipoprotein metabolism, both of which are involved in atherosclerotic processes. Depletion of Tregs leads to impaired clearance of low density lipoprotein (LDL), and intracellular cholesterol homeostasis affects Treg cell development. Furthermore, the atherosclerotic environment affects the Treg cells’ phenotype and plasticity. Plasticity between Tregs and Th17 cells has been a matter of investigation lately. We investigated the frequency of interleukin-17 (IL-17)-producing Tregs in the peripheral blood of patients with atherosclerosis.

Material and methods

We studied 10 non-diabetic patients with significant coronary artery disease (CAD) as the patient group, and seven non-diabetic individuals with normal coronary angiography/insignificant CAD as the control group. Peripheral blood mononuclear cells were stained with fluorescent antibodies to detect CD4, CD45RO, IL-17, and Foxp3 expression both before and after stimulation with PMA/Ionomycin. Cell enumeration was performed using flowcytometry and analysed using Mann-Whitney test.

Results

CD4+IL-17+Foxp3+ and CD4+IL-17+Foxp3- subsets showed higher frequencies in patients than in controls both before (p = 0.0031, p = 0.033, respectively) and after stimulation (p = 0.0027 and p = 0.0013, respectively). Interestingly, CD4+IL-17+Foxp3+ cells were almost exclusively CD45RO+ with a much higher frequency in patients than in controls (p = 0.0027, p = 0.0007). After stimulation, the frequency of CD4+CD45RO+IL-17+Foxp3+ lymphocytes increased to a greater extent in patients (p < 0.0001) than in controls.

Conclusions

Interleukin-17 production by an intermediate population with an activated Treg phenotype in our patients may point to the population heterogeneity or plasticity in Tregs during atherosclerotic inflammation.

IL-35 promoted STAT3 phosphorylation and IL-10 production in B cells, but its production was reduced in patients with coronary artery diseases

Interleukin (IL)-35 is a heterodimeric cytokine composed of the IL-12A subunit and the Epstein-Barr virus induced gene 3 (EBI3) subunit. Binding of IL-35 with IL-12 receptor subunit beta 2 (IL-12RB2) and IL-6 signal transducer (IL-6ST) occupies the binding sites of IL-6, IL-12, and IL-27 and prevents their signal transduction. IL-35 is also shown to promote the development of regulatory T cells (Tregs) and regulatory B cells (Bregs). In this study, we investigated B cell-mediated IL-35 production in patients with coronary artery disease (CAD). The expression levels of IL-35 subunits and IL-10 were significantly lower in B cells from CAD patients than in B cells from healthy control individuals. Exogenous IL-35 could effectively increase the IL-10 production by B cells in a concentration-dependent manner. IL-35 promoted the phosphorylation of STAT1 and STAT3 in B cells, and the inhibition of STAT3 phosphorylation suppressed IL-10 production. Raising the IL-35 concentration in cell culture eliminated the difference in IL-10 expression between CAD B cells and healthy B cells. We also demonstrated that B cells from CAD patients presented lower capacity to suppress interferon gamma (IFNG) and tumor necrosis factor (TNF) expression by T cells than B cells from healthy controls. Exogenous IL-35 could significantly improve the suppressive capacity of B cells in both healthy controls and CAD patients. Together, these results demonstrated that a reduction in IL-35 production was associated with Breg defects in CAD patients. IL-35 and IL-35 targets may serve as therapeutic candidates in the treatment of CAD and related diseases.

Evolving targets for the treatment of atherosclerosis

Atherosclerosis is a progressive disease of large arteries and a leading cause of cardiovascular diseases and stroke. Chronic inflammation, aberrant immune response, and disturbances to key enzymes involved with lipid metabolism are characteristic features of atherosclerosis. Apart from targeting the derangements in lipid metabolism, therapeutic modulation to regulate chronic inflammation and the immune system response may prove to be very promising strategies in the management of atherosclerosis. In recent years, various targets have been studied for the treatment of atherosclerosis. PCSK9, a serine protease, actively targets the LDL-R and causes lysosomal degradation, which leads to excessive accumulation of LDL-C. Regulatory T cells (Tregs) and Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) affects the adaptive and innate immune response, respectively, and thus, therapeutic intervention of either of these targets would directly modulate disease progression. Advanced atherosclerotic lesions are characterized by an accumulation of apoptotic cells. Cluster of differentiation-47 (CD47), an anti-phagocytic known as the "don't eat me" signaling molecule, inhibits efferocytosis, which causes accumulation of cell debris in plaque. ADAMTS and Notch signaling potentially affect the formation of neointima by modulation of extracellular matrix components such as macrophages and vascular smooth muscle cells. This review provides insights on the molecular targets for therapeutic intervention of atherosclerosis, their effect at various stages of atherosclerosis development, and the therapies that have been designed and currently being evaluated in clinical trials.

The Pivotal Role of Thymus in Atherosclerosis Mediated by Immune and Inflammatory Response

Atherosclerosis is one kind of chronic inflammatory disease, in which multiple types of immune cells or factors are involved. Data from experimental and clinical studies on atherosclerosis have confirmed the key roles of immune cells and inflammation in such process. The thymus as a key organ in T lymphocyte ontogenesis has an important role in optimizing immune system function throughout the life, and dysfunction of thymus has been proved to be associated with severity of atherosclerosis. Based on previous research, we begin with the hypothesis that low density lipoprotein or cholesterol reduces the expression of the thymus transcription factor Foxn1 via low density lipoprotein receptors on the membrane surface and low density lipoprotein receptor related proteins on the cell surface, which cause the thymus function decline or degradation. The imbalance of T cell subgroups and the decrease of naive T cells due to thymus dysfunction cause the increase or decrease in the secretion of various inflammatory factors, which in turn aggravates or inhibits atherosclerosis progression and cardiovascular events. Hence, thymus may be the pivotal role in coronary heart disease mediated by atherosclerosis and cardiovascular events and it can imply a novel treatment strategy for the clinical management of patients with atherosclerosis in addition to different commercial drugs. Modulation of immune system by inducing thymus function may be a therapeutic approach for the prevention of atherosclerosis. Purpose of this review is to summarize and discuss the recent advances about the impact of thymus function on atherosclerosis by the data from animal or human studies and the potential mechanisms.

The alternation of autophagy/apoptosis in CD4+CD25+Foxp3+ Tregs on the developmental stages of atherosclerosis

Naturally regulatory T cells (Tregs) play a critical role in the regulation of T cell-mediated immune responses in atherosclerosis. However, the regulatory mechanism underlying Tregs upon long-term development of atherosclerosis remains unknown. Therefore, in this study, atherosclerotic model was induced in ApoE-/- mice by feeding fat-diet for 10 weeks. Quantification of atherosclerotic lesions was done by calculating the lesion size in the aortic sinus every 2 weeks. The lipid levels and inflammatory mediators were detected in serum sample. The populations of CD4+CD25+Foxp3+ Tregs were compared between ApoE-/- mice (ApoE-/-) and wild type C57BL/6 littermates (WT). The expression levels of autophagy and apoptosis signaling related regulators were determined by flow cytomery, RT-qPCR, and western blot assays in the CD4+CD25+Foxp3+ Tregs isolated from ApoE-/- and WT. We found that the sizes of plaque lesions in atherosclerotic ApoE-/- mice were larger than those in WT group during 10 weeks' detection (all P<0.05); Whereas, flow cytometry assay showed that the populations of CD4+CD25+Foxp3+ Tregs were significantly reduced in atherosclerotic ApoE-/- mice compared with those in corresponding WT group from the 4th weeks' detection (all P<0.05). The lipid accumulation and increased pro-inflammatory mediators were correlated with the developmental progression of atherosclerosis. Furthermore, compared to WT group, the functional properties of CD4+CD25+Foxp3+ Tregs from ApoE-/- mice showed a gradually decreased autophagic activity with aberrant expressions of LC3, Beclin1, ATG5, ATG7, p62 (all P<0.05), and a gradually increased apoptotic activity with abnormal expressions of cleaved caspase 3, Bim, Bcl-2 (all P<0.05) during the 10 weeks' detection period. Taken together, our data demonstrated that the population of CD4+CD25+Foxp3+ Tregs was reversely correlated with plaque forming in atherosclerotic ApoE-/- mice during atherosclerosis development. And the autophagy/apoptosis-dependent Tregs might play a crucial role for the maintenance of CD4 9+CD25+Foxp3+ Tregs survival during atherosclerosis progression.

Crosstalk Between Enzyme Matrix Metalloproteinases 2 and 9 and Regulatory T Cell Immunity in the Global Burden of Atherosclerosis

Changes in immune and inflammatory responses may play a crucial role in the development and progression of atherosclerosis, as an autoimmune, chronic and progressive inflammatory disease. Immunological activity and vascular inflammation during atherosclerosis can be modulated by autoimmune responses against self-antigens, according to changeable risk factors (cholesterol, oxidized low-density lipoprotein (ox-LDL) in the vascular wall, fatty acids, etc.), and accompanied by accumulation of leucocytes and proinflammatory cytokines, which stimulate the transcription of matrix metalloproteinases (MMPs), whose concentration are increased in foam cell-rich regions. Regulatory T cells (Tregs) represent a unique subpopulation of T cells specialized in the regulation of immune response and in the suppression of proatherogenic T cells. The aim of our study was to examine the interactions between the concentration of enzyme matrix metalloproteinases 2 and 9 (MMP-2 and 9) in urine and the percentage of Tregs in peripheral blood of two groups of patients: with carotid artery stenosis (CAS), undergoing surgery and with mild atherosclerosis (A) from general practice. The method of enzyme immunoassay (ELISA) was used to determine enzyme MMP expression, and Tregs was examined by flow cytometric analysis. Our data have showed a large increase in the enzyme MMP-2 and 9 in the urine of CAS and A patients in comparison with healthy controls and indicated this method as an easy marker for the monitoring of the development of atherosclerosis. Simultaneously, the diminished number of Tregs in the same patients pointed the importance of these regulatory mechanisms in the etiopathogenesis of atherosclerosis and possible Tregs-mediated therapy.

Function and Therapeutic Potential of Mesenchymal Stem Cells in Atherosclerosis

Atherosclerosis is a complicated disorder and largely attributable to dyslipidaemia and chronic inflammation. Despite therapeutic advances over past decades, atherosclerosis remains the leading cause of mortality worldwide. Due to their capability of immunomodulation and tissue regeneration, mesenchymal stem cells (MSCs) have evolved as an attractive therapeutic agent in various diseases including atherosclerosis. Accumulating evidences support the protective role of MSCs in all stages of atherosclerosis. In this review, we highlight the current understanding of MSCs including their characteristics such as molecular markers, tissue distribution, migratory property, immune-modulatory competence, etc. We also summarize MSC functions in animal models of atherosclerosis. MSC transplantation is able to modulate cytokine and chemokine secretion, reduce endothelial dysfunction, promote regulatory T cell function, decrease dyslipidemia, and stabilize vulnerable plaques during atherosclerosis development. In addition, MSCs may migrate to lesions where they develop into functional cells during atherosclerosis formation. Finally, the perspectives of MSCs in clinical atherosclerosis therapy are discussed.

IL-35 improves Treg-mediated immune suppression in atherosclerotic mice

Interleukin (IL)-35 is an anti-inflammatory cytokine that may have a protective role in atherosclerosis (AS). However, the exact role of IL-35 in the disease, and the etiology of AS, remain incompletely understood. The present study aimed to investigate whether exogenous IL-35 was able to attenuate the formation of atherosclerotic lesions in apoE^-/^- mice, and analyze alterations in the expression levels of forkhead box protein 3 (Foxp3) in peripheral blood and the lesions during the progression of AS. ApoE^-/^- mice were randomly divided into two groups that received either a basal diet (negative control group) or a high-fat diet (HFD) for 4 weeks. The HFD group was further subdivided into groups that received IL-35, atorvastatin or no treatment for 12 weeks. Diagnostic enzyme assay kits were applied for the detection of plasma lipids, and hematoxylin and eosin staining was used to analyze the severity of atherosclerotic lesions in apoE^-/^- mice. Immunohistochemistry and flow cytometry were performed to analyze the expression of Foxp3 in the plasma and atherosclerotic plaques. As compared with the negative control group, the plasma lipids were significantly increased, and the lesions were obviously formed, in the HFD groups. Furthermore, the area of the lesion was reduced in IL-35- and atorvastatin-treated groups, as compared with the AS control group. In addition, Foxp3 expression was upregulated in the plasma and lesions of the IL-35- and atorvastatin-treated groups, as compared with the AS control group. The present study demonstrated that IL-35 improved T_reg-mediated immune suppression in atherosclerotic mice, thus suggesting that IL-35 may be a novel therapeutic target for AS.

Protective effects of agonistic anti-4-1BB antibody on the development of imiquimod-induced psoriasis-like dermatitis in mice

Agonistic anti-4-1BB antibodies (Abs) play a central role in immunomodulatory conditions that control the pathogenesis of immune-mediated autoimmune and allergic diseases. However, the effects of agonistic anti-4-1BB Abs have not been examined in an experimental mouse model of psoriasis. Therefore, we investigated the protective effects of agonistic anti-4-1BB Abs, using imiquimod (IMQ)-induced psoriasis-like dermatitis in mice, a condition histologically and clinically similar to human psoriasis. We found that administration of agonistic anti-4-1BB Abs (10mg/kg) significantly alleviated the severity of IMQ-induced psoriasis-like skin inflammation in mice, with reduced histologic symptoms, including inflammatory infiltration, parakeratosis, and hyperkeratosis. Subsequent analyses revealed that the production of Th17 cytokines (IL-17A and IL-23) in the serum and skin of IMQ-induced mice was significantly inhibited by agonistic anti-4-1BB Abs (10mg/kg), although Th1 cytokines (TNF-α and IFN-γ) were not. Moreover, administration of agonistic anti-4-1BB Abs (10mg/kg) induced a relative increase of CD4(+)FoxP3(+) regulatory T (Treg) cells in the spleen and draining lymph node (DLN). Taken together, our data provide evidence that agonistic anti-4-1BB Abs possesses immunosuppressive properties in IMQ-induced psoriasis-like skin inflammation, providing insight into the immunomodulatory effect of agonistic anti-4-1BB Abs for psoriasis immunotherapy.

Role of Telomerase in the Cardiovascular System

Aging is one major risk factor for the incidence of cardiovascular diseases and the development of atherosclerosis. One important enzyme known to be involved in aging processes is Telomerase Reverse Transcriptase (TERT). After the discovery of the enzyme in humans, TERT had initially only been attributed to germ line cells, stem cells and cancer cells. However, over the last few years it has become clear that TERT is also active in cells of the cardiovascular system including cardiac myocytes, endothelial cells, smooth muscle cells and fibroblasts. Interference with the activity of this enzyme greatly contributes to cardiovascular diseases. This review will summarize the findings on the role of TERT in cardiovascular cells. Moreover, recent findings concerning TERT in different mouse models with respect to cardiovascular diseases will be described. Finally, the extranuclear functions of TERT will be covered within this review.

Immune-inflammatory responses in atherosclerosis: Role of an adaptive immunity mainly driven by T and B cells

Adaptive immune response plays an important role in atherogenesis. In atherosclerosis, the proinflammatory immune response driven by Th1 is predominant but the anti-inflammatory response mediated mainly by regulatory T cells is also present. The role of Th2 and Th17 cells in atherogenesis is still debated. In the plaque, other T helper cells can be observed such as Th9 and Th22 but is little is known about their impact in atherosclerosis. Heterogeneity of CD4(+) T cell subsets presented in the plaque may suggest for plasticity of T cell that can switch the phenotype dependening on the local microenvironment and activating/blocking stimuli. Effector T cells are able to recognize self-antigens released by necrotic and apoptotic vascular cells and induce a humoral immune reaction. Tth cells resided in the germinal centers help B cells to switch the antibody class to the production of high-affinity antibodies. Humoral immunity is mediated by B cells that release antigen-specific antibodies. A variety of B cell subsets were found in human and murine atherosclerotic plaques. In mice, B1 cells could spontaneously produce atheroprotective natural IgM antibodies. Conventional B2 lymphocytes secrete either proatherogenic IgG, IgA, and IgE or atheroprotective IgG and IgM antibodies reactive with oxidation-specific epitopes on atherosclerosis-associated antigens. A small population of innate response activator (IRA) B cells, which is phenotypically intermediate between B1 and B2 cells, produces IgM but possesses proatherosclerotic properties. Finally, there is a minor subset of splenic regulatory B cells (Bregs) that protect against atherosclerotic inflammation through support of generation of Tregs and production of anti-inflammatory cytokines IL-10 and TGF-β and proapoptotic molecules.

Relationship between regulatory T cells subsets and lipid profile in dyslipidemic patients: a longitudinal study during atorvastatin treatment

Background

The CD4+ T-lymphocytes and their subtype CD4 + CD25^highFoxP3+ regulatory T cells are receiving growing interest as major regulators of atherogenesis. We sought to investigate 1) whether the CD4 + cell subsets were expressed differently in dyslipidemic patients (Pts) and healthy subjects (HS) and 2) whether atorvastatin treatment could be associated in-vivo and in-vitro with cell changes in expression and functional response.

Methods

CD4+ subsets frequency (CD4 + CD25^highFoxP3+, CD4 + CD25-FoxP3+) and mRNA expression for FoxP3, IL-10 and TGF-β were evaluated in 30 consecutive Pts at baseline and after a 3-month atorvastatin therapy, and in 17 HS.

Results

The % of CD4 + cells did not differ between HS and Pts. The % of CD4 + CD25^highFoxP3+ was higher in Pts than HS and did not change during treatment. The CD4 + CD25-FoxP3+ cells were similar between the two groups and were lower in Pts at visit 2. Cytokine expression and FoxP3 did not differ in HS and Pts and no substantial change was observed during treatment. At visit 1, CD4 + CD25^highFoxP3+ cells were significantly correlated with both total-cholesterol (r = 0.570, P = 0.0002), LDL-cholesterol (r = 0.715, P = 0.0001), Apolipoprotein B (r = 0.590, P = 0.0001). In-vitro atorvastatin (up to 5 μM) failed to induce any significant modulation of cell functions.

Conclusion

CD4 + CD25^highFoxP3+ regulatory cells seem to be over-stimulated in the early pre-clinical phase of atherosclerosis and a relationship exists between their frequency and circulating lipids. A potential immuno-modulation by statin treatment is not achieved through a normalization in peripheral CD4 + cell subsets.

Serum Galectin-9 Levels Are Associated with Coronary Artery Disease in Chinese Individuals

Background. Recently, several studies suggest that galectin-9 (Gal-9) might play a pivotal role in the pathogenesis of autoimmune diseases. However, the exact role of Gal-9 in atherosclerosis remains to be elucidated. Methods. Serum Gal-9, high-sensitivity C-reactive protein (hs-CRP), interferon- (IFN-) γ, interleukin- (IL-) 4, IL-17, and transforming growth factor- (TGF-) β1 were measured. The effect of Gal-9 on peripheral blood mononuclear cells (PBMC) was investigated in patients with normal coronary artery (NCA). Results. The lowest level of Gal-9 was found in the ST-segment elevation myocardial infarction (STEMI) group, followed by the non-ST-segment elevation ACS (NSTEACS), the NCA, and the stable angina pectoris (SAP) groups, respectively. Additionally, Gal-9 was found to be independently associated with hs-CRP, lipoprotein(a), and creatinine. Notably, Gal-9 was also noted to be an independent predictor of the Gensini score. Moreover, Gal-9 suppressed T-helper 17 (Th17) and expanded regulatory T cells (Tregs), resulting in decreased IL-17 production and increased secretion of TGF-β1. Conclusions. Serum Gal-9 is associated with not only coronary artery disease (CAD), but also the severity of coronary arteries stenosis. Gal-9 can expand Tregs and suppress Th17 development in activated PBMC, implying that Gal-9 has the potential to dampen the development of atherosclerosis and may be a new therapy for CAD.

Biochanin A inhibits lipopolysaccharide-induced inflammation in human umbilical vein endothelial cells

AIM

Biochanin A, an isoflavone isolated from red clover, cabbage or alfalfa, has been reported to have anti-inflammatory activity. However, the effects of biochanin A on vascular inflammation have not been investigated. In this study, we investigate the anti-inflammatory effects of biochanin A on lipopolysaccharide (LPS)-induced inflammatory response in human umbilical vein endothelial cells (HUVEC cells).

MAIN METHODS

The HUVEC cells were treated with biochanin A for 12h before exposure to LPS. The expression of ECAMs, including VCAM-1, ICAM-1, E-selectin, NF-κB and PPAR-γ was detected by Western blotting. The expression of cytokines TNF-α and IL-8 was detected by ELISA.

KEY FINDINGS

The results showed that biochanin A inhibited LPS-induced TNF-α and IL-8 production. Meanwhile, biochanin A also suppressed VCAM-1, ICAM-1, and E-selectin expression induced by LPS. We also found that biochanin A inhibited NF-κB activation induced by LPS. Furthermore, biochanin A could activate PPAR-γ and the anti-inflammatory effects of biochanin A can be reversed by GW9662, a specific antagonist for PPAR-γ.

SIGNIFICANCE

In conclusion, the anti-inflammatory effect of biochanin A is associated with activating PPAR-γ, thereby attenuating NF-κB activation and LPS-induced inflammatory response. These findings suggest that biochanin A may be a therapeutic agent for inflammatory cardiovascular disease.

Atorvastatin Improves Inflammatory Response in Atherosclerosis by Upregulating the Expression of GARP

Regulatory T cells play an important role in the progression of atherosclerosis. GARP is a newly biological membrane molecule existed on activated Tregs, which is related to the release of TGF-β. The antiatherosclerosis effects of statins partly depend on their multiple immune modulatory potencies. In this paper, we present that atorvastatin could upregulate the expression of GARP and TGF-β in CD4+ T cells and increase the numbers of CD4+LAP+ and CD4+Foxp3+ regulatory T cells in ApoE-/- mice. Also, we indicate that atorvastatin promotes the aggregation of GARP+ and Foxp3+ cells and secretory of the TGF-β1 in atherosclerotic plaques. Furthermore, we prove that atorvastatin could delay the procession of atherosclerosis and improve the stability of atherosclerotic plaques. Interestingly, we report that inhibition of GARP distinctly inhibits the anti-inflammatory effects of atorvastatin. We conclude that atorvastatin improves the inflammatory response in atherosclerosis partly by upregulating the expression of GARP on regulatory T cells.

Heterogeneity of Tregs and the complexity in the IL-12 cytokine family signaling in driving T-cell immune responses in atherosclerotic vessels

The importance of immune inflammation in the development and progression of atherosclerotic lesions is well recognized. Accumulated evidence shows striking features of heterogeneity of regulatory T cells (Tregs) and the importance of the IL-12 cytokine family in regulation of Tregs in atherogenesis. The present review briefly summarized the current knowledge about the impact of the IL-12 cytokine family in regulation of immune processes in atherogenesis.

Patients with chronic three-vessel disease in a 15-year follow-up study: genetic and non-genetic predictors of survival

Genetic and non-genetic predictors of 15-year survival in patients with chronic three-vessel disease (3VD) were investigated. Coronary angiography was performed on 810 subjects with symptoms of stable ischemic heart disease in 1998. The patients with 3VD were genotyped for 23 candidate polymorphisms covering the PPAR-RXR pathway, matrix metalloproteinase-2, renin-angiotensin-aldosterone system, endothelin-1, cytokine genes, MTHFR and APO E variants. Fifteen-year survival data were obtained from the national insurance registry. All data were available in the case of 150 patients with 3VD. Statistical analysis used stepwise Cox regression with dominant, recessive, or additive mode of genetic expression. Involved variables included age, sex, BMI, blood pressure, diabetes, ejection fraction, left main stenosis, previously diagnosed coronary stenosis, myocardial infarction in personal history, and coronary bypass along with polymorphisms pre-selected by log-rank tests. Out of the 23 polymorphisms, four were included in the model construction. SNP in the IL-6 gene rs1800795 (-174 G/C) has been found to be a significant predictor of survival. This SNP was in a linkage disequilibrium with rs1800797 (-597 G/A) in the same gene (D'=1.0), which was also found to constitute a significant predictor of survival when rs1800795 was not included in the model construction. Age, increased BMI, diabetes, low EF, and left main stenosis were also significant predictors in all models. Age, increased BMI, diabetes, low ejection fraction, left main stenosis, and genetic variation in the IL-6 promoter were established as significant independent risk factors for the survival of patients with three-vessel disease.

Mesenchymal stem cells alleviate atherosclerosis by elevating number and function of CD4(+)CD25 (+)FOXP3 (+) regulatory T-cells and inhibiting macrophage foam cell formation

Atherosclerosis is a chronic inflammatory disease characterized by the formation of plaques inside arteries, leading to narrowing and blockage. Potential therapeutic strategies include expanding the population of regulatory T-cells (Tregs) to enhance atheroprotective immunity, and inhibiting the formation of macrophage foam cells. Here, we studied the effect of bone marrow-derived mesenchymal stem cells (BM-MSCs) on atherosclerotic plaque formation in Apolipoprotein E(-/-) (ApoE-KO) mice, and elucidated the underlying mechanism. BM-MSCs isolated from 4 week-old ApoE-KO mice were evaluated by flow cytometry for expression of MSC-specific markers. Thirty eight week-old ApoE-KO mice were randomly divided into three experimental groups (n = 10 per group): 1. MSC group-received BM-MSCs intravenously; 2. Vehicle group-received DMEM; 3. Control group-did not receive any treatment. Administration of MSCs resulted in a marked decrease in the size of atherosclerotic plaques 3 months after treatment. In addition, the number and function of CD4(+)CD25(+)FOXP3(+) regulatory T-cells (Tregs) in cultured splenocytes, and the expression of FOXP3 at both mRNA and protein levels, was significantly increased in the MSC group. In vitro experiments further indicated that the formation of macrophage foam cells was inhibited by treatment with MSCs, accompanied by a significant downregulation in CD36 and scavenger receptor A (SRA). Our findings suggest that MSCs play an atheroprotective role by enhancing the number and function of Tregs and inhibiting the formation of macrophage foam cells. Hence, administration of MSCs to atherosclerotic patients might have significant clinical benefits.

Dendritic cells in atherosclerotic inflammation: the complexity of functions and the peculiarities of pathophysiological effects

Atherosclerosis is considered as a chronic disease of arterial wall, with a strong contribution of inflammation. Dendritic cells (DCs) play a crucial role in the initiation of proatherogenic inflammatory response. Mature DCs present self-antigens thereby supporting differentiation of naïve T cells to effector cells that further propagate atherosclerotic inflammation. Regulatory T cells (Tregs) can suppress proinflammatory function of mature DCs. In contrast, immature DCs are able to induce Tregs and prevent differentiation of naïve T cells to proinflammatory effector T cells by initiating apoptosis and anergy in naïve T cells. Indeed, immature DCs showed tolerogenic and anti-inflammatory properties. Thus, DCs play a double role in atherosclerosis: mature DCs are proatherogenic while immature DCs appear to be anti-atherogenic. Tolerogenic and anti-inflammatory capacity of immature DCs can be therefore utilized for the development of new immunotherapeutic strategies against atherosclerosis.

The second touch hypothesis: T cell activation, homing and polarization

The second touch hypothesis states that T cell activation, proliferation, induction of homing receptors and polarization are distinguishable and, at least in part, sequential. The second touch hypothesis maintains that full T cell polarization requires T cell interaction with antigen-presenting cells (DCs, macrophages, B cells and certain activated stromal cells) in the non-lymphoid tissue where the antigen resides. Upon initial antigen encounter in peripheral lymph nodes (PLN), T cells become activated, proliferate and express homing receptors that enable them to recirculate to the (inflamed) tissue that contains the antigen. Differentiation into the T helper lineages Th1, Th2, Th17 and induced regulatory T cells (iTreg) requires additional antigen presentation by tissue macrophages and other antigen presenting cells (APCs) in the inflamed tissue. Here, I present a conceptual framework for the importance of peripheral (non-lymphoid) antigen presentation to antigen-experienced T cells.