Latency-associated peptide (LAP)+CD4+ regulatory T cells prevent atherosclerosis by modulating macrophage polarization.

RATIONALE: A persistent autoimmune and inflammatory response plays a critical role in the progression of atherosclerosis. The transcription factor forkhead box P3 (Foxp3)+CD4+ regulatory T cells (Foxp3+ Tregs) attenuate atherosclerosis. Latency-associated peptide (LAP)+CD4+ T cells are a new class of Tregs whose role in atherosclerosis is unknown. OBJECTIVE: To investigate the function of CD4+LAP+ Tregs in inhibiting inflammation and preventing atherosclerosis. METHODS AND RESULTS: Depletion of CD4+LAP+ Tregs results in aggravated inflammation and atherosclerotic lesions. Mechanistically, CD4+LAP+ Treg depletion was associated with decreased M2-like macrophages and increased Th1 and Th17 cells, characterized by increased unstable plaque promotion and decreased expression of inflammation-resolving factors in both arteries and immune organs. In contrast, adoptive transfer of CD4+LAP+ Tregs to ApoE-/- mice or CD4-/-ApoE-/- mice led to decreased atherosclerotic lesions. Compared with control animals, adoptive transfer of CD4+LAP+ Tregs induced M2-like macrophage differentiation within the atherosclerotic lesion and spleen, associated with increased collagen and α-SMA in plaques and decreased expression of MMP-2 and MMP-9. Mechanistic studies reveal that isolated CD4+LAP+ Tregs exhibit a tolerance phenotype, with increased expression of inhibitory cytokines and coinhibitory molecules. After coculture with CD4+LAP+ Tregs, monocytes/macrophages display typical features of M2 macrophages, including upregulated expression of CD206 and Arg-1 and decreased production of MCP-1, IL-6, IL-1ß and TNF-α, which was almost abrogated by transwell and partially TGF-ß1 neutralization. RNA-seq analysis showed different gene expression profiles between CD4+LAP+ Tregs and LAP-CD4+ T cells and between CD4+LAP+ Tregs of ApoE-/- mice and CD4+LAP+ Tregs of C57BL/6 mice, of which Fancd2 and IL4i1 may contribute to the powerful inhibitory properties of CD4+LAP+ Tregs. Furthermore, the number and the suppressive properties of CD4+LAP+ Tregs were impaired by oxLDL. CONCLUSIONS: Our data indicate that the remaining CD4+LAP+ Tregs play a protective role in atherosclerosis by modulating monocyte/macrophage differentiation and regulatory factors, which may partly explain the protective effect of T cells tolerance in atherosclerosis. Moreover, adoptive transfer of CD4+LAP+ Tregs constitutes a novel approach to treat atherosclerosis.

Interleukin-27 Ameliorates Atherosclerosis in ApoE-/- Mice through Regulatory T Cell Augmentation and Dendritic Cell Tolerance.

Atherosclerosis, which is characterized by chronic inflammation in the arterial wall, is driven by immune cells and cytokines. Recent evidence indicated that interleukin (IL)-27 showed pleiotropic properties in immune diseases. However, precise mechanisms of IL-27, especially in atherosclerosis remains unknown. In our research, we examined the influence of the administration of IL-27 and an anti-IL-27p28 antibody (anti-IL-27p28-Ab) on both the initiation and the progression of atherosclerosis. In the groups (both the initiation and the progression) receiving recombinant IL-27 administration, the formation of atherosclerotic plaques was suspended, and the percentage of regulatory T cells (LAP+ or Foxp3+) in the spleen and peripheral blood was increased. Meanwhile, the number of T helper 1 (Th1) and T helper 17 (Th17) cells was decreased. In the peripheral blood plasma, TGF-ß and IL-10 expression were increased, while the levels of IFN-γ and IL-17 were reduced. As for lesions, the mRNA expression of Foxp3, TGF-ß, and IL-10 was increased, while that of IFN-γ and IL-17 was reduced. In the anti-IL-27p28 antibody groups, we obtained opposite results. We also observed that DCs treated with IL-27 display a tolerogenic phenotype and that IL-27-treated tolerogenic DCs (tDCs) are likely to play a protective role during atherosclerosis. Our study indicates that IL-27 or adoptive transfer of IL-27 loaded tDCs may be a new therapeutic approach in atherosclerosis.

Interleukin-38 alleviates cardiac remodelling after myocardial infarction.

Excessive immune-mediated inflammatory reaction plays a deleterious role in ventricular remodelling after myocardial infarction (MI). Interleukin (IL)-38 is a newly characterized cytokine of the IL-1 family and has been reported to exert a protective effect in some autoimmune diseases. However, its role in cardiac remodelling post-MI remains unknown. In this study, we found that the expression of IL-38 was increased in infarcted heart after MI induced in C57BL/6 mice by permanent ligation of the left anterior descending artery. In addition, our data showed that ventricular remodelling after MI was significantly ameliorated after recombinant IL-38 injection in mice. This amelioration was demonstrated by better cardiac function, restricted inflammatory response, attenuated myocardial injury and decreased myocardial fibrosis. Our results in vitro revealed that IL-38 affects the phenotype of dendritic cells (DCs) and IL-38 plus troponin I (TNI)-treated tolerogenic DCs dampened adaptive immune response when co-cultured with CD4+ T cells. In conclusion, IL-38 plays a protective effect in ventricular remodelling post-MI, one possibility by influencing DCs to attenuate inflammatory response. Therefore, targeting IL-38 may hold a new therapeutic potential in treating MI.

IL-37 Plays a Beneficial Role in Patients with Acute Coronary Syndrome.

BACKGROUND: Interleukin-37 (IL-37) acts as an inhibitor of innate and adaptive immunity. However, the exact role of IL-37 in the patients with acute coronary syndrome (ACS) remains to be elucidated. METHODS: Patients were classified into 4 groups: normal coronary artery (NCA), stable angina (SA), unstable angina (UA), and acute myocardial infarction (AMI). The circulating Treg, Th1, and Th17 frequencies were measured. The effect of IL-37 on stimulated peripheral blood mononuclear cells (PBMCs) and the influence of IL-37 on DCs were explored. In addition, the role of IL-37-treated tDCs on Treg cell expansion and the stability of these tDCs were also tested. RESULTS: Our results showed that the circulating Treg frequencies were decreased, while Th1 and Th17 frequencies were increased in ACS patients, and that IL-37 expanded Tregs but suppressed Th1 and Th17 cells in activated PBMCs derived from ACS patients. Of note, IL-37-treated human DCs obtained a tolerogenic phenotype, and such tDCs promoted expansion of Tregs and decreased the Th1 and Th17 populations when cocultured with CD4+ T cells. Interestingly, IL-37-treated DCs from patients with ACS are phenotypically and functionally comparable to IL-37-treated DCs from NCA patients, and tolerogenic properties of IL-37-treated DCs were highly stable. CONCLUSION: In conclusion, our results reveal a beneficial role of IL-37 in the patients with ACS and suggest that autologous IL-37-treated tDCs may be a novel therapeutic strategy for the patients with ACS.

CD4+ CD25+ GARP+ regulatory T cells display a compromised suppressive function in patients with dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is a lethal inflammatory heart disease and closely connected with dysfunction of the immune system. Glycoprotein A repetitions predominant (GARP) expressed on activated CD4+ T cells with suppressive activity has been established. This study aimed to investigate the frequency and function of circulating CD4+  CD25+  GARP+ regulatory T (Treg) cells in DCM. Forty-five DCM patients and 46 controls were enrolled in this study. There was a significant increase in peripheral T helper type 1 (Th1) and Th17 number and their related cytokines [interferon-γ (IFN-γ), interleukin (IL-17)], and an obvious decrease in Treg number, transforming growth factor-ß1 (TGF-ß1 ) levels and the expression of forkhead box P3 (FOXP3) and GARP in patients with DCM compared with controls. In addition, the suppressive function of CD4+  CD25+  GARP+ Treg cells was impaired in DCM patients upon T-cell receptor stimulation detected using CFSE dye. Lower level of TGF-ß1 and higher levels of IFN-γ and IL-17 detected using ELISA were found in supernatants of the cultured CD4+  CD25+  GARP+ Treg cells in DCM patients compared with controls. Together, our results indicate that CD4+  CD25+  GARP+ Treg cells are defective in DCM patients and GARP seems to be a better molecular definition of the regulatory phenotype. Therefore, it might be an attractive stategy to pay more attention to GARP in DCM patients.

The IL-2/Anti-IL-2 Complex Attenuates Cardiac Ischaemia-Reperfusion Injury Through Expansion of Regulatory T Cells.

BACKGROUND/AIMS: Regulatory T cells (Tregs) can suppress immunologic damage in myocardial ischaemia/reperfusion injury (MIRI), however, the isolation and ex vivo expansion of these cells for clinical application remains challenging. Here, we investigated whether the IL-2/anti-IL-2 complex (IL-2C), a mediator of Treg expansion, can attenuate MIRI in mice. METHODS: Myocardial I/R was surgically induced in male C57BL/6 mice, aged 8-10 weeks, that were randomly assigned to 1) sham group (Sham), 2) Phosphate Buffered Saline (PBS), 3) IL-2-anti-IL-2 Ab complex (IL-2C), or 4) sham group, 5) PBS, 6) IL-2C after MIRI, or 7) IL-2C, 8) IL-2C+anti-CD25 mAbs, or 9) IL-2C; 10) IL-2C+anti-TGF-ß1 mAbs, 11) IL-2C+anti-IL-10 mAbs. The following parameters were measured at different time points: infarct area, myocardial apoptosis, splenocytes, the inhibitory function of Tregs, and presence of inflammatory factors. In addition, immunohistochemistry analysis was performed. RESULTS: We observed that Tregs were activated in response to MIRI. IL-2C administered before MIRI induced Treg expansion in both spleen and heart, attenuated Th1 and Th17 cell numbers, improved myocardial function, and attenuated both infiltration of inflammatory cells and apoptosis after MIRI. Furthermore, IL-2C administration reduced expression of inflammatory cytokines in the heart and attenuated proliferation of splenic cells. Depletion of Tregs with anti-CD25 mAb abrogated the beneficial effects of IL-2C. However, IL-2C-mediated myocardial protection was not dependent on either IL-10 or TGF-ß. In addition, IL-2C administration after MIRI did not reduce infarct area, but did improve myocardial function slightly and reduced myocardial fibrosis. CONCLUSION: Our results demonstrate that IL-2C-induced Treg expansion attenuates MIRI and improves myocardial recovery in vivo, suggesting that IL-2C is a promising therapeutic target for myocardial IRI.

Valsartan Attenuates Atherosclerosis via Upregulating the Th2 Immune Response in Prolonged Angiotensin II-Treated ApoE(-/-) Mice.

Valsartan has a protective effect against hypertension and atherosclerosis in humans and experimental animal models. This study aimed to determine the effect of prolonged treatment with angiotensin II (Ang II) on atherosclerosis and the effect of valsartan on the activity of CD4(+) T lymphocyte subsets. The results showed that prolonged treatment (8 wks) with exogenous Ang II resulted in an increased atherosclerotic plaque size and a switch of stable-to-unstable plaque via modulating on CD4(+) T lymphocyte activity, including an increase in the T helper cell type 1 (Th1) and Th17 cells and a decrease in Th2 and regulatory T (Treg) cells. In contrast, valsartan treatment efficiently reversed the imbalance in CD4(+) T lymphocyte activity, ameliorated atherosclerosis and elicited a stable plaque phenotype in addition to controlling blood pressure. In addition, treatment with anti-interleukin (IL)-5 monoclonal antibodies weakened the antiatherosclerotic effects of valsartan without affecting blood pressure.

Heme oxygenase-1 restores impaired GARPCD4⁺CD25⁺ regulatory T cells from patients with acute coronary syndrome by upregulating LAP and GARP expression on activated T lymphocytes.

BACKGROUND: Accumulating evidence shows that the pathological autoreactive immune response is responsible for plaque rupture and the subsequent onset of acute coronary syndrome (ACS). Naturally occurring CD4(+)CD25(+)regulatory T cells (nTregs) are indispensable in suppressing the pathological autoreactive immune response and maintaining immune homeostasis. However, the number and the suppressive function of glycoprotein-A repetitions predominant (GARP) (+) CD4(+) CD25(+) activated nTregs were impaired in patients with ACS. Recent evidence suggests that heme oxygenase-1 (HO-1) can regulate the adaptive immune response by promoting the expression of Foxp3. We therefore hypothesized that HO-1 may enhance the function of GARP(+) CD4(+) CD25(+)Tregs in patients with ACS and thus regulate immune imbalance. METHODS: T lymphocytes were isolated from healthy volunteers (control, n=30) and patients with stable angina (SA, n=40) or ACS (n=51). Half of these cells were treated with an HO-1 inducer (hemin) for 48 h, and the other half were incubated with complete RPMI-1640 medium. The frequencies of T-helper 1 (Th1), Th2, Th17 and latency-associated peptide (LAP) (+)CD4(+) T cells and the expression of Foxp3 and GARP by CD4(+)CD25(+)T cells were then assessed by measuring flow cytometry after stimulation in vitro. The suppressive function of activated Tregs was measured by thymidine uptake. The levels of transforming growth factor-1 (TGF-ß1) in the plasma were measured using enzyme-linked immunosorbent assay (ELISA). The expression levels of the genes encoding these proteins were analyzed by real-time polymerase chain reaction. RESULTS: Patients with ACS exhibited an impaired number and suppressive function of GARP(+) CD4(+) CD25(+)Tregs and a mixed Th1/Th17-dominant T cell response when compared with the SA and control groups. The expression of LAP in T cells was also lower in patients with ACS compared to patients with SA and the control individuals. Treatment with an HO-1 inducer enhanced the biological activity of GARP(+) CD4(+) CD25(+)Tregs and resulted in increased expression of LAP and GARP by activated T cells. CONCLUSIONS: The reduced number and impaired suppressive function of GARP(+) CD4(+) CD25(+)Tregs result in excess effector T cell proliferation, leading to plaque instability and the onset of ACS. HO-1 can effectively restore impaired GARP(+) CD4(+) CD25(+)Tregs from patients with ACS by promoting LAP and GARP expression on activated T cells.

Elevated Plasma IL-38 Concentrations in Patients with Acute ST-Segment Elevation Myocardial Infarction and Their Dynamics after Reperfusion Treatment.

OBJECTIVE: Recent studies suggest that IL-38 is associated with autoimmune diseases. Furthermore, IL-38 is expressed in human atheromatous plaque. However, the plasma levels of IL-38 in patients with ST-segment elevation myocardial infarction (STEMI) have not yet to be investigated. METHODS: On admission, at 24 h, at 48 h, and at 7 days, plasma IL-38, C-reactive protein (CRP), cardiac troponin I (cTNI), and N-terminal of the prohormone brain natriuretic peptide (NT-proBNP) levels were measured and IL-38 gene in peripheral blood mononuclear cells (PBMCs) was detected in STEMI patients. RESULTS: The results showed that plasma IL-38 levels and IL-38 gene expression in PBMCs were significantly increased in STEMI patients compared with control group and were time dependent, peaked at 24 h. In addition, plasma IL-38 levels were dramatically reduced in patients with reperfusion treatment compared with control group. Similar results were also demonstrated with CRP, cTNI, and NT-proBNP levels. Furthermore, IL-38 levels were found to be positively correlated with CRP, cTNI, and NT-proBNP and be weakly negatively correlated with left ventricular ejection fraction (LVEF) in STEMI patients. CONCLUSIONS: The results indicate that circulating IL-38 is a potentially novel biomarker for patients with STEMI and IL-38 might be a new target for MI study.

MicroRNA-208a Dysregulates Apoptosis Genes Expression and Promotes Cardiomyocyte Apoptosis during Ischemia and Its Silencing Improves Cardiac Function after Myocardial Infarction.

AIMS: miR-208a is associated with adverse outcomes in several cardiac pathologies known to have increased apoptosis, including myocardial infarction (MI). We investigated if miR-208a has proapoptotic effects on ischemic cardiomyocytes and if its silencing has therapeutic benefits in MI. METHODS AND RESULTS: The effect of miR-208a on apoptosis during ischemia was studied in cultured neonatal mice myocytes transfected with agomir or antagomir. Differential gene expression was assessed using microarrays. MI was induced in male C57BL/6 mice randomly assigned to antagomir (n = 6) or control group (n = 7), while sham group (n = 7) had sham operation done. Antagomir group received miR208a antagomir, while control and sham group mice received vehicle only. At 7 and 28 days, echocardiography was done and thereafter hearts were harvested for analysis of apoptosis by TUNEL method, fibrosis using Masson's trichrome, and hypertrophy using hematoxylin and eosin. miR-208a altered apoptosis genes expression and increased apoptosis in ischemic cardiomyocytes. Therapeutic inhibition of miR-208a decreased cardiac fibrosis, hypertrophy, and apoptosis and significantly improved cardiac function 28 days after MI. CONCLUSION: miR-208a alters apoptosis genes expression and promotes apoptosis in ischemic cardiomyocytes, and its silencing attenuates apoptosis, fibrosis, and hypertrophy after MI, with significant improvement in cardiac function.

Chemerin15-Ameliorated Cardiac Ischemia-Reperfusion Injury Is Associated with the Induction of Alternatively Activated Macrophages.

Chemerin15 (C15), an endogenous anti-inflammatory component, inhibits the activity of neutrophils and macrophages through G protein-coupled receptor ChemR23; however, its role as well as functional mechanism in mouse myocardial ischemia/reperfusion (I/R) injury remains unknown. Methods. Sham or I/R operations were performed on C57BL/6J mice. The I/R mice received an injection of C15 immediately before reperfusion. Serum troponin T levels, infarct size, cardiomyocyte apoptosis, reactive oxygen species (ROS) production, and infiltration of neutrophils were assessed 24 h after reperfusion, while the macrophage phenotypes, macrophage infiltration, and inflammatory cytokine levels were assessed 48 h after reperfusion. Results. Compared with the control group, the C15-treated mice showed an obvious amelioration of I/R injury and displayed less ROS, accompanied by reduced neutrophil recruitment. C15 decreased the tumor necrosis factor- (TNF-) α and interleukin- (IL-) 6 levels and increased the IL-10 levels in the serum of the I/R mice, which suggested a suppressed inflammatory response that could be related to elevated alternatively activated M2 macrophages with characteristic skewed expression of M2 markers and inhibition of classically activated M1 marker expression. Conclusion. C15 may induce alternatively activated M2 macrophage polarization and suppress the inflammatory response to protect against myocardial I/R injury in mice.

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-ß. 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-ß 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-ß1 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.

Impairment of Circulating CD4⁺CD25⁺GARP⁺ regulatory T cells in patients with acute coronary syndrome.

BACKGROUND: Atherosclerosis (AS) is an inflammatory and immune disease. Regulatory T cells (Tregs) suppress the activation of T cells and have been shown to play a protective role during the pathogenesis of AS. However, specific markers for Tregs are lacking. Recently, glycoprotein A repetitions predominant (GARP) was discovered as a specific marker of activated Tregs, and we therefore utilized GARP as a specific surface marker for Tregs in the current study. METHODS: To assess whether GARP(+) Tregs are downregulated in patients with acute coronary syndrome (ACS), we examined CD4(+)CD25(+)GARP(+) T cell frequencies as well as their associated cytokines and suppressive function. Additionally, we compared GARP expression to that of FOXP3, which may be more sensitive as a marker of activated Tregs in patients with ACS. RESULTS: Patients with ACS demonstrated a significant decrease in circulating CD4(+)CD25(+)GARP(+) Tregs. Moreover, the suppressive function of Tregs and levels of related cytokines were also impaired in ACS patients compared to those with stable angina (SA) or normal coronary artery (NCA). Additionally, after TCR stimulation, peripheral blood mononuclear cells (PBMCs) from patients with ACS exhibited a decrease in CD4(+)CD25(+)GARP(+) Tregs. CONCLUSIONS: These fnding indicate that circulating CD4(+)CD25(+)GARP(+) Tregs are impaired in patients withACS. Thus, targeting GARP may promote the protective function of Tregs in ACS.

Chemerin is a novel biomarker of acute coronary syndrome but not of stable angina pectoris.

BACKGROUND: Recent evidence demonstrated that the circulating adipokines were associated with the onset of acute coronary syndrome (ACS) including unstable angina pectoris (UAP) and acute myocardial infarction (AMI). As a novel adipokine, chemerin has been related to atherosclerosis and the presence of coronary artery disease. However, the plasma levels of chemerin in patients with ACS have yet to be investigated. METHODS: Plasma levels of chemerin and adiponectin were measured by an enzyme-linked immunosorbent assay (ELISA) in 60 patients with stable angina pectoris (SAP), 60 patients with UAP, 60 patients with AMI and 40 control patients. Left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF) were measured using a GE ViVid E7 ultrasonography machine, and the severity of coronary stenosis in patients was estimated with a Gensini coronary score following coronary angiography. RESULTS: Plasma chemerin levels were significantly higher in ACS patients than in the control and SAP groups, while plasma adiponectin levels were significantly lower in ACS patients than the control group. A correlation analysis revealed that plasma chemerin levels were positively correlated with the levels of C-reactive protein (CRP) (r = 0.29, P < 0.01) and LVEDD (r = 0.27, P < 0.01) but negatively correlated with LVEF (r = -0.45, P < 0.01) and that plasma adiponectin levels were positively correlated with LVEF (r = 0.53, P < 0.01) but negatively correlated with CRP (r = -0.33, P < 0.01) and LVEDD (r = -0.30, P < 0.01). Although significant correlations between chemerin, adiponectin and BMI or the Gensini coronary score were found in patients with SAP, neither chemerin nor adiponectin was correlated with BMI and the Gensini coronary score in patients with ACS. Furthermore, both chemerin (OR 1.103, 95% CI 1.065 to 1.142; P = 0.001) and adiponectin (OR 0.871, 95% CI 0.776 to 0.970; P = 0.018) were independently associated with the presence of ACS. CONCLUSIONS: Chemerin is a novel biomarker of acute coronary syndrome but not of stable angina pectoris.

Elevated plasma IL-37, IL-18, and IL-18BP concentrations in patients with acute coronary syndrome.

OBJECTIVE: More recently, evidence showed that the novel anti-inflammatory cytokine interleukin- (IL-) 37 was expressed in the foam-like cells of atherosclerotic coronary and carotid artery plaques, suggesting that IL-37 is involved in atherosclerosis-related diseases. However, the plasma levels of IL-37 in patients with acute coronary syndrome (ACS, including unstable angina pectoris and acute myocardial infarction) have yet to be investigated. METHODS: Plasma IL-37, IL-18, and IL-18BP levels were measured in 50 patients with stable angina pectoris (SAP), 75 patients with unstable angina pectoris (UAP), 67 patients with acute myocardial infarction (AMI), and 65 control patients. RESULTS: The plasma IL-37, IL-18, and IL-18BP levels were significantly increased in ACS patients compared to SAP and control patients. A correlation analysis showed that the plasma biomarker levels were positively correlated with each other and with the levels of C-reactive protein (CRP), N-terminal probrain natriuretic peptide (NT-proBNP), and left ventricular end-diastolic dimension (LVEDD) but negatively correlated with left ventricular ejection fraction (LVEF). Furthermore, the plasma IL-37, IL-18, and IL-18BP had no correlation with the severity of the coronary artery stenosis. CONCLUSIONS: The results indicate that the plasma IL-37 levels are associated with the onset of ACS.

Blocking of the human ether-à-go-go-related gene channel by imatinib mesylate.

Imatinib mesylate (IM), a widely prescribed powerful tyrosine kinase inhibitor, has been associated with increased risk of heart failure and is known to induce cell apoptosis and death in isolated cardiomyocytes. In addition to acquired long QT syndrome, pharmacological inhibition of human ether-à-go-go-related gene (HERG) channel has been reported to involve in apoptosis. The present study was undertaken to characterize the biophysical properties of IM on HERG and the molecular determinants of HERG blockade using mutant channels (Y652A and F656A). Wild type (WT) and mutant HERG channels were expressed in HEK-293 cells and Xenopus oocytes and the currents (I(HERG)) were measured using patch-clamp and two-microelectrode voltage-clamp techniques. IM inhibited WT I(HERG) in a concentration-dependent manner with an IC(50) of 19.51±2.50 µmol/L and 44.76±1.54 µmol/L in HEK-293 cells and Xenopus oocytes, respectively. The IM-induced inhibition of WT I(HERG) followed a voltage- and time-dependent manner. The blockade was enhanced by further activation of currents, which were in accordance with an open-channel blockade. The V(1/2) for steady-state activation shifted from -15.48±1.21 to -26.66±2.98 mV (p<0.05, n=6). The inactivation kinetics and voltage dependence of steady-state inactivation of the WT HERG channel were not significantly altered by IM. Two S6 domain mutants, F652A and Y656A, attenuated IM-induced inhibition of WT I(HERG). Therefore, IM preferentially blocked the open HERG channel through F652 and Y656, providing a molecular mechanism for the cardiac side effects during the clinical administration of IM.

Case report: Malignant vasovagal reflex syndrome during percutaneous transcatheter closure of patent foramen ovale.

Malignant vasovagal reflex syndrome can be induced by pulling of cardiac tissue during percutaneous transcatheter closure of patent foramen ovale. In this case, a patient presented with a malignant vasovagal reflex syndrome characterized by decreased heart rate, cardiac arrest, and ventricular tachycardia. Therefore, it's particularly important to observe patients' heart rate and timely deal with vasovagal reflex syndrome during the operation.

Ablation of CXCR4 expression in cardiomyocytes exacerbates isoproterenol­induced cell death and heart failure.

CXCR4 is a seven­transmembrane­spanning Gi­coupled receptor for the SDF­1 chemokine and plays a critical role in cardiovascular development and post­injury repair. However, the specific role of CXCR4 in cardiomyocytes is incompletely understood. It was hypothesized that CXCR4 activation in cardiomyocytes antagonizes ß­adrenoceptor/Gs signaling­induced cardiac dysfunction. Cardiomyocyte­specific CXCR4 knockout (CXCR4­CMKO) mice were generated by crossing CXCR4fl/fl and MHC­Cre+/­ mice. Their cardiac structure and function in the basal state are equivalent to that of the control MHC­Cre+/­ littermates until at least 4 months old. However, following continuous subcutaneous administration of isoproterenol (Iso) via an osmotic mini­pump, the ventricular myocardial contractility, dilation, cardiomyocyte apoptosis, and interstitial fibrosis are worse in CXCR4­CMKO mice than in MHC­Cre+/­ littermates. In the cultured H9C2 cardiomyocytes, SDF­1 treatment markedly attenuated Iso­induced apoptosis and reduction in phospho­Akt, and this protective effect was lost by knockdown of CXCR4 or by co­treatment with Gi inhibitors. In conclusion, CXCR4 promotes cardiomyocyte survival and heart function during ß­adrenergic stress.

Effects of IL-38 on Macrophages and Myocardial Ischemic Injury.

Macrophages play an important role in clearing necrotic myocardial tissues, myocardial ischemia-reperfusion injury, and ventricular remodeling after myocardial infarction. M1 macrophages not only participate in the inflammatory response in myocardial tissues after infarction, which causes heart damage, but also exert a protective effect on the heart during ischemia. In contrast, M2 macrophages exhibit anti-inflammatory and tissue repair properties by inducing the production of high levels of anti-inflammatory cytokines and fibro-progenitor cells. Interleukin (IL)-38, a new member of the IL-1 family, has been reported to modulate the IL-36 signaling pathway by playing a role similar to that of the IL-36 receptor antagonist, which also affects the production and secretion of macrophage-related inflammatory factors that play an anti-inflammatory role. IL-38 can relieve myocardial ischemia-reperfusion injury by promoting the differentiation of M1 macrophages into M2 macrophages, inhibit the activation of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome, and increase the secretion of anti-inflammatory cytokines, such as IL-10 and transforming growth factor-ß. The intact recombinant IL-38 can also bind to interleukin 1 receptor accessory protein-like 1 (IL-1RAPL1) to activate the c-jun N-terminal kinase/activator protein 1 (JNK/AP1) pathway and increase the production of IL-6. In addition, IL-38 regulates dendritic cell-induced cardiac regulatory T cells, thereby regulating macrophage polarization and improving ventricular remodeling after myocardial infarction. Accordingly, we speculated that IL-38 and macrophage regulation may be therapeutic targets for ameliorating myocardial ischemic injury and ventricular remodeling after myocardial infarction. However, the specific mechanism of the IL-38 action warrants further investigation.

IL-37 Expression in Patients with Abdominal Aortic Aneurysm and Its Role in the Necroptosis of Vascular Smooth Muscle Cells.

Background: Our previous studies have shown that interleukin- (IL-) 37 plays a protective role in patients and animal models with coronary artery disease. However, the role of IL-37 in patients with abdominal aortic aneurysm (AAA), another artery disease, is yet to be elucidated. Methods and Results: AAA tissues and plasma samples were obtained from patients with or without surgical intervention. Normal renal aortic tissues were collected from kidney transplant donors. Our findings established that in AAA, IL-37 was distributed in endothelial cells, macrophages, and vascular smooth muscle cells (VSMCs) and that it was chiefly concentrated in VSMCs. Furthermore, the expression was found to be downregulated compared with that in normal artery tissues. Immunofluorescence showed that, unlike normal arteries, IL-37 was translocated to the nucleus of VSMCs in AAA. Moreover, in patients with AAA, the expressions of IL-37, IL-6, and tumor necrosis factor- (TNF-) α were increased in the plasma in comparison with the healthy controls. Correlation analysis revealed that IL-37 was positively correlated with IL-6, TNF-α, age, aneurysm diameter, and blood pressure. Furthermore, human aortic vascular smooth muscle cells (HASMCs) were stimulated with angiotensin II (AngII) in vitro to simulate smooth muscle cell (SMC) damage in AAA. A decrease in IL-37 expression and an increase in receptor-interacting serine/threonine-protein kinase 3 (RIPK3) expression were observed in HASMCs stimulated with AngII. On this basis, inhibition of RIPK3 with GSK'872 significantly attenuated necroptosis. Moreover, the necroptosis rates were significantly lowered in HASMCs treated with recombinant IL-37, whereas the rates were enhanced when the cells were depleted of the interleukin. Immunoblotting results showed that both exogenous and endogenous IL-37 could affect the expressions of RIPK3, NLRP3, and IL-1ß. Also, the phosphorylation of RIPK3 and p65 was affected. Meanwhile, IL-37 promoted the transition of SMC from proliferative type to contractile type. Conclusions: The expression of IL-37 in VSMCs decreases in patients with AAA, whereas IL-37 supplementation suppresses RIPK3-mediated necroptosis and promotes the transition of VSMCs from proliferative to contractile type.