Ting-Ting Tang

The Th17/Treg imbalance in patients with acute coronary syndrome.

Atherosclerosis is a chronic inflammatory disease regulated by T lymphocyte subsets. Recently, CD4+CD25+Foxp3+ regulatory T (Treg) cells and Th17 cells have been described as two distinct subsets from Th1 and Th2 cells and have the opposite effects on autoimmunity. Th17/Treg balance controls inflammation and may be important in the pathogenesis of plaque destabilization and the onset of acute coronary syndrome [ACS, including unstable angina (UA) and acute myocardial infarction (AMI)]. To assess whether this balance was broken in patients with coronary heart disease, we detected Th17/Treg functions on different levels including cell frequencies, related cytokine secretion and key transcription factors in patients with AMI, UA, stable angina (SA) and controls. The results demonstrated that patients with ACS revealed significant increase in peripheral Th17 number, Th17 related cytokines (IL-17, IL-6 and IL-23) and transcription factor (RORgammat) levels and obvious decrease in Treg number, Treg related cytokines (IL-10 and TGF-beta1) and transcription factor (Foxp3) levels as compared with patients with SA and controls. Results indicate that Th17/Treg functional imbalance exists in patients with ACS, suggesting a potential role for Th17/Treg imbalance in plaque destabilization and the onset of ACS.

Interleukin-17A contributes to myocardial ischemia/reperfusion injury by regulating cardiomyocyte apoptosis and neutrophil infiltration.

OBJECTIVES This study tested whether interleukin (IL)-17A is involved in the pathogenesis of mouse myocardial ischemia/reperfusion (I/R) injury and investigated the mechanisms. BACKGROUND Inflammatory processes play a major role in myocardial I/R injury. We recently identified IL-17A as an important cytokine in inflammatory cardiovascular diseases such as atherosclerosis and viral myocarditis. However, its role in myocardial I/R injury remains unknown. METHODS The involvement of IL-17A was assessed in functional assays in mouse myocardial I/R injury by neutralization/repletion or genetic deficiency of IL-17A, and its mechanism on cardiomyocyte apoptosis and neutrophil infiltration were further studied in vivo and in vitro. RESULTS Interleukin-17A was elevated after murine left coronary artery ligation and reperfusion. Intracellular cytokine staining revealed that γδT lymphocytes but not CD4(+) helper T cells were a major source of IL-17A. Anti-IL-17A monoclonal antibody treatment or IL-17A knockout markedly ameliorated I/R injury, as demonstrated by reduced infarct size, reduced cardiac troponin T levels, and improved cardiac function. This improvement was associated with a reduction in cardiomyocyte apoptosis and neutrophil infiltration. In contrast, repletion of exogenous IL-17A induced the opposite effect. In vitro study showed that IL-17A mediated cardiomyocyte apoptosis through regulating the Bax/Bcl-2 ratio, induced CXC chemokine-mediated neutrophil migration and promoted neutrophil-endothelial cell adherence through induction of endothelial cell E-selectin and inter-cellular adhesion molecule-1 expression. CONCLUSIONS IL-17A mainly produced by γδT cells plays a pathogenic role in myocardial I/R injury by inducing cardiomyocyte apoptosis and neutrophil infiltration.

The Th17/Treg functional imbalance during atherogenesis in ApoE−/− mice

OBJECTIVE Atherosclerosis is a chronic inflammatory disease regulated by T lymphocyte subsets. Recently, CD4(+) CD25(+) Foxp3(+) regulatory T (Treg) cells and Th17 cells have been described as two distinct subsets and have the opposite effects on autoimmunity. Clinical observation has revealed that the Th17/Treg imbalance exists in patients with acute coronary syndrome. We investigated whether the Th17/Treg functional imbalance existed during atherogenesis in ApoE(-/-) mice. METHODS AND RESULTS Th17/Treg functions at different levels including cell frequencies, related cytokine secretion and key transcription factors were investigated comparatively between ApoE(-/-) mice and their age-matched C57BL/6J mice. The results demonstrated that ApoE(-/-) mice revealed significantly increased secretion of Th17 related cytokines (IL-17 and IL-6) and expression of transcription factor (RORgammat) levels and obviously decreased number in Treg cells, secretion of Treg related cytokines (TGF-beta(1)) and expression of transcription factor (Foxp3) levels as compared with age-matched C57BL/6J mice. Th17 related mediators reached their maximum expression values at the early stage (8-16weeks of age) in ApoE(-/-) mice, and then followed by continuous depression of their expression levels. Meanwhile, the expression of Treg related mediators was much lower in ApoE(-/-) mice than in their age-matched wild-type littermates. CONCLUSIONS Th17/Treg functional imbalance exists during atherogenesis in ApoE(-/-) mice, suggesting a potential role of Th17/Treg imbalance in the formation and progression of atherosclerosis.

Regulatory T cells ameliorate cardiac remodeling after myocardial infarction

Persistent inflammatory responses participate in the pathogenesis of adverse ventricular remodeling after myocardial infarction (MI). We hypothesized that regulatory T (Treg) cells modulate inflammatory responses, attenuate ventricular remodeling and subsequently improve cardiac function after MI. Acute MI was induced by ligation of the left anterior descending coronary artery in rats. Infiltration of Foxp3+ Treg cells was detected in the infarcted heart. Expansion of Treg cells in vivo by means of adoptive transfer as well as a CD28 superagonistic antibody (JJ316) resulted in an increased number of Foxp3+ Treg cells in the infarcted heart. Subsequently, rats with MI showed improved cardiac function following Treg cells transfer or JJ316 injection. Interstitial fibrosis, myocardial matrix metalloproteinase-2 activity and cardiac apoptosis were attenuated in the rats that received Treg cells transfer. Infiltration of neutrophils, macrophages and lymphocytes as well as expression of tumor necrosis factor (TNF)-α and interleukin (IL)-1β were also significantly decreased, and the CD8+ cardiac-specific cytotoxic T lymphocyte response was inhibited. Expression of interleukin (IL)-10 in the heart, however, was increased. Additional studies in vitro indicated that Treg cells directly protect neonatal rat cardiomyocytes against LPS-induced apoptosis, and this protection depends on the cell–cell contact and IL-10 expression. Furthermore, Treg cells inhibited proinflammatory cytokines production by cardiomyocytes. These data demonstrate that Treg cells serve to protect against adverse ventricular remodeling and contribute to improve cardiac function after myocardial infarction via inhibition of inflammation and direct protection of cardiomyocytes.

IgE stimulates human and mouse arterial cell apoptosis and cytokine expression and promotes atherogenesis in Apoe–/– mice

IgE has a key role in the pathogenesis of allergic responses through its ability to activate mast cells via the receptor FcεR1. In addition to mast cells, many cell types implicated in atherogenesis express FcεR1, but whether IgE has a role in this disease has not been determined. Here, we demonstrate that serum IgE levels are elevated in patients with myocardial infarction or unstable angina pectoris. We found that IgE and the FcεR1 subunit FcεR1α were present in human atherosclerotic lesions and that they localized particularly to macrophage-rich areas. In mice, absence of FcεR1α reduced inflammation and apoptosis in atherosclerotic plaques and reduced the burden of disease. In cultured macrophages, the presence of TLR4 was required for FcεR1 activity. IgE stimulated the interaction between FcεR1 and TLR4, thereby inducing macrophage signal transduction, inflammatory molecule expression, and apoptosis. These IgE activities were reduced in the absence of FcεR1 or TLR4. Furthermore, IgE activated macrophages by enhancing Na+/H+ exchanger 1 (NHE1) activity. Inactivation of NHE1 blocked IgE-induced macrophage production of inflammatory molecules and apoptosis. Cultured human aortic SMCs (HuSMCs) and ECs also exhibited IgE-induced signal transduction, cytokine expression, and apoptosis. In human atherosclerotic lesions, SMCs and ECs colocalized with IgE and TUNEL staining. This study reveals what we believe to be several previously unrecognized IgE activities that affect arterial cell biology and likely other IgE-associated pathologies in human diseases.

Inhibition of IL-17A in atherosclerosis

OBJECTIVE To determine the effects of interleukin (IL)-17A inhibition on experimental atherosclerosis. METHODS AND RESULTS ApoE(-/-) mice were treated with either rat anti-mouse IL-17A, mouse anti-mouse IL-17A or isotype-matched control antibodies for 12 weeks (n=8-10 per group). Ldlr(-/-) mice were transplanted with IL-17A-deficient or wild type bone marrow (n=8 per group). Rat anti-mouse IL-17A treatment obviously reduced plaque size by 43% (p<0.01) without evidence of reduced IL-17A signaling. In contrast, mouse anti-mouse IL-17A treatment and IL-17A deficiency in bone marrow cells did not alter lesion size despite significant reduction of IL-17A production. CONCLUSIONS Inhibition of IL-17A signaling does not alter lesion development in Th1-biased C57BL/6 ApoE(-/-) and Ldlr(-/-) mice with already low levels of IL-17A production. Alteration of lesion development after repeated injections of rat anti-mouse IL-17A antibody in ApoE(-/-) mice could not be attributed to blockade of IL-17A signaling.

Atorvastatin upregulates regulatory T cells and reduces clinical disease activity in patients with rheumatoid arthritis.

In this study, we investigated the hypothesis that regulatory T cells (Treg) are involved in the immunomodulatory effects of statins on rheumatoid arthritis (RA) patients. The 12-week study cohort consisted of 55 RA patients and 42 control subjects allocated to either a group treated with atorvastatin (AT) (20 mg/day) or a non-AT group. Treg numbers, suppressive function, serum inflammatory markers, and disease activity were evaluated before and after the therapy. Furthermore, the effects of AT on the frequency and suppressive function of Treg were determined in vitro. Our data revealed that the suppressive function of Treg from RA patients significantly decreased compared with that of control subjects. AT significantly reduced erythrosedimentation, C-reactive protein, and disease activity. Concomitantly, Treg numbers and suppressive functions were significantly improved by AT. Consistent with the in vivo experiments, AT promoted the generation of Treg from primary T cells and enhanced preexisting Treg function in vitro. Moreover, we showed that PI3K-Akt-mTOR and ERK signal pathways were involved in the induction of Treg by AT. In conclusion, AT significantly increased Treg numbers and restored their suppressive function in the RA patients, and this may be relevant in the modulation of uncontrolled inflammation in this disorder.

Defective Circulating CD4+CD25+Foxp3+CD127low Regulatory T-cells in Patients with Chronic Heart Failure

Aims: Increasing evidences confirm the role of immune activation in the pathogenesis of chronic heart failure (CHF). Regulatory T cells appear central to the control of immune homeostasis. We assessed the hypothesis that the circulating frequency and function of CD4+CD25+ Foxp3+CD127low T regulatory cells (Tregs) would be deranged in patients with CHF. Methods: Ninety-nine CHF patients due to non-ischemic (NIHF) or ischemic etiology (IHF) and 24 control donors were enrolled in the study. Frequency of circulating Tregs was evaluated by flow cytometry. Foxp3 in peripheral blood mononuclear cells (PBMCs) was assayed at the mRNA level by real-time PCR. Functional properties of Tregs to suppress proliferation and pro-inflammatory cytokines secretion of activated CD4+CD25- T cells were measured by proliferation assay and ELISA. Results: The results demonstrated that CHF patients had significantly lower frequency of circulating Tregs and reduced Foxp3 expression in PBMCs compared with control donors. Moreover, Tregs from CHF patients showed compromised function to suppress CD4+CD25- T cells proliferation and pro-inflammatory cytokines secretion. A similar pattern with reduced Tregs frequency and compromised function was found in both NIHF and IHF patients. Correlation analysis suggested that Tregs frequency and function positively correlated with LVEF, whereas negatively correlated with LVEDD and NT-proBNP in patients with CHF. Conclusions: Our data are the first to demonstrate that frequencies of circulating Tregs in patients with CHF are reduced and their suppressive function compromised independently of the etiology. Defective Tregs may be an underlying mechanism of immune activation in CHF patients.

Atorvastatin Modulates Th1/Th2 Response in Patients With Chronic Heart Failure

BACKGROUND The T-helper (Th)1/Th2 imbalance has been demonstrated to be involved in chronic heart failure (CHF). We sought to determine whether atorvastatin exhibited any effect on CHF through modulating the Th1/Th2 response. METHODS AND RESULTS We measured serum concentrations of interleukin (IL)-12, -18, interferon (IFN)-gamma, IL-4, and IL-10 from 20 controls and 72 patients with nonischemic CHF by enzyme-linked immunosorbent assay. To investigate the effect of atorvastatin in vivo, CHF patients were either classified into a usual therapy group (n = 35) or usual therapy plus atorvastatin (10 mg/day) group (n = 37). Patient serum levels of IFN-gamma and IL-4 were measured at time of admission and 2 weeks after treatment. Peripheral blood mononuclear cells from patients of CHF group were cultured in the presence or absence of atorvastatin (0, 0.4, 1, and 4 micromol/L) in vitro, and IFN-gamma and IL-4 levels were detected. Serum levels of IL-12, IL-18, and IFN-gamma were significantly higher in the CHF group than in the control group. The levels of IFN-gamma and the ratios of IFN-gamma:IL-4 were significantly decreased with atorvastatin treatment both in vivo and in vitro, whereas levels of IL-4 did not differ significantly. CONCLUSIONS Th1 polarization exists in patients with CHF, and atorvastatin can modulate the Th1/Th2 response through inhibiting Th1 cytokine production.

The Same Chromosome 9p21.3 Locus Is Associated With Type 2 Diabetes and Coronary Artery Disease in a Chinese Han Population

OBJECTIVE Recent genome-wide association studies (GWAS) revealed that a 9p21.3 locus was associated with type 2 diabetes. In this study, we carried out a large-scale case-control study in the GeneID Chinese Han population to 1) further replicate the association of 9p21.3 type 2 diabetes GWAS single nucleotide polymorphisms (SNPs) and 2) assess the association of these SNPs with coronary artery disease. RESEARCH DESIGN AND METHODS Three SNPs (rs2383208, rs10811661, and rs10757283) were genotyped in two GeneID cohorts of 3,167 Chinese Han individuals. Case-control association design was used to determine the association of the SNPs with type 2 diabetes and coronary artery disease. Gensini scores were calculated in the coronary artery disease subjects and were tested for association with the variants. Multivariate logistic regressions were performed on association studies. RESULTS The association between two of the three SNPs and type 2 diabetes was replicated in the GeneID population (rs2383208, P = 0.936; rs10811661-T, P = 0.02, odds ratio [OR] = 1.23; rs10757283-C, P = 0.003, OR = 1.30). The same two SNPs also contributed to the risk of coronary artery disease (CAD) (rs10811661-T, P = 0.002, OR = 1.19; rs10757283-C, P = 0.003, OR = 1.18). In addition, rs10757283 was associated with severity of coronary atherosclerosis estimated by the Gensini scoring system (risk allele C, quantitative-trait regression adjusted P = 0.002). CONCLUSIONS For the first time to our knowledge, our results indicated that the same 9p21.3 locus, represented by SNPs rs10811661 and rs10757283, contributed to the risk of type 2 diabetes and coronary artery disease in our GeneID Chinese Han population.