IL-37 ameliorates myocardial fibrosis by regulating mtDNA-enriched vesicle release in diabetic cardiomyopathy mice.

BACKGROUND: Diabetic cardiomyopathy (DCM), a serious complication of diabetes, leads to structural and functional abnormalities of the heart and ultimately evolves to heart failure. IL-37 exerts a substantial influence on the regulation of inflammation and metabolism. Whether IL-37 is involved in DCM is unknown. METHODS: The plasma samples were collected from healthy controls, diabetic patients and DCM patients, and the level of IL-37 and its relationship with heart function were observed. The changes in cardiac function, myocardial fibrosis and mitochondrial injury in DCM mice with or without IL-37 intervention were investigated in vivo. By an in vitro co-culture approach involving HG challenge of cardiomyocytes and fibroblasts, the interaction carried out by cardiomyocytes on fibroblast profibrotic activation was studied. Finally, the possible interactive mediator between cardiomyocytes and fibroblasts was explored, and the intervention role of IL-37 and its relevant molecular mechanisms. RESULTS: We showed that the level of plasma IL-37 in DCM patients was upregulated compared to that in healthy controls and diabetic patients. Both recombinant IL-37 administration or inducing IL-37 expression alleviated cardiac dysfunction and myocardial fibrosis in DCM mice. Mechanically, hyperglycemia impaired mitochondria through SIRT1/AMPK/PGC1α signaling, resulting in significant cardiomyocyte apoptosis and the release of extracellular vesicles containing mtDNA. Fibroblasts then engulfed these mtDNA-enriched vesicles, thereby activating TLR9 signaling and the cGAS-STING pathway to initiate pro-fibrotic process and adverse remodeling. However, the presence of IL-37 ameliorated mitochondrial injury by preserving the activity of SIRT1-AMPK-PGC1α axis, resulting in a reduction in release of mtDNA-enriched vesicle and ultimately attenuating the progression of DCM. CONCLUSIONS: Collectively, our study demonstrates a protective role of IL-37 in DCM, offering a promising therapeutic agent for this disease.

GSDMD-Mediated Cardiomyocyte Pyroptosis Promotes Myocardial I/R Injury.

[Figure: see text].

Current knowledge of pyroptosis in heart diseases.

Pyroptosis is a form of pro-inflammatory, necrotic cell death mediated by proteins of the gasdermin family. Various heart diseases, including myocardial ischemia/reperfusion injury, myocardial infarction, and heart failure, involve cardiomyocyte and non-myocyte pyroptosis. Cardiomyocyte pyroptosis also causes the release of pro-inflammatory cytokines. Recent studies have confirmed that pyroptosis is predominantly triggered by both the canonical and non-canonical inflammasome pathways, which independently facilitate caspase-1 or caspase-11/4/5 activation and gasdermin D (GSDMD) cleavage. Cardiac fibroblast and myeloid cell pyroptosis also contributes to the pathogenesis and development of heart diseases. This review summarizes the recent studies on pyroptosis in heart diseases and discusses the associated therapeutic targets.

Neutrophil-derived advanced glycation end products-Nε-(carboxymethyl) lysine promotes RIP3-mediated myocardial necroptosis via RAGE and exacerbates myocardial ischemia/reperfusion injury.

Nε-(carboxymethyl) lysine (CML), the major member of advanced glycation end products, was widely studied in diabetic complications and aging-associated diseases. However, the impact of CML on myocardial ischemia/reperfusion injury (MI/RI) was rarely reported. In the present study, CML was increased in both patients with acute myocardial infarction (53.4 ± 7.8 vs. 28.1 ± 4.4 ng; P = 0.017), and mice underwent MI/RI (16.4 ± 1.4 vs. 10.8 ± 0.9 ng; P = 0.006). Depletion of neutrophils reduced CML (17.8 ± 1.0 vs. 9.9 ± 0.3 ng; P < 0.001), indicating neutrophils were the major cells contributing to CML formation during MI/RI. CML treatment exacerbated MI/RI by elevating myocardial injury marker (274.3 ± 18.0 vs. 477.2 ± 34.3 pg; P < 0.001), enlarging myocardial infarct size (32.9 ± 3.6 vs. 45.2 ± 3.8%; P = 0.03), increasing myocardial fibrosis (17.5 ± 1.6 vs. 29.7 ± 2.2%; P < 0.001) and impairing cardiac function (59.4 ± 2.4% vs. 46.0 ± 1.3%; P = 0.001). Further study revealed that CML increased the phosphorylation of receptor interacting protein (RIP) 3, an important initiator of necroptosis, and its downstream proteins. Receptor for advanced glycation end product (RAGE) deficiency effectively blocked RIP3 phosphorylation induced by CML and rescued CML-mediated MI/RI, indicating CML promoted RIP3-mediated necroptosis through RAGE. In addition, glyoxalase-1 overexpression could effectively attenuate MI/RI by reducing CML formation, providing a potential therapeutic target for MI/RI.-Yang, J., Zhang, F., Shi, H., Gao, Y., Dong, Z., Ma, L., Sun, X., Li, X., Chang, S., Wang, Z., Qu, Y., Li, H., Hu, K., Sun, A., Ge, J. Neutrophil-derived advanced glycation end products-Nε-(carboxymethyl) lysine promotes RIP3-mediated myocardial necroptosis via RAGE and exacerbates myocardial ischemia/reperfusion injury.

Acetaldehyde dehydrogenase 2 deficiency exacerbates cardiac fibrosis by promoting mobilization and homing of bone marrow fibroblast progenitor cells.

Cardiac fibrosis is a common feature of various cardiovascular diseases. Previous studies showed that acetaldehyde dehydrogenase 2 (ALDH2) deficiency exacerbated pressure overload-induced heart failure. However, the role and mechanisms of cardiac fibrosis in this process remain largely unknown. This study aimed to investigate the effect of ALDH2 deficiency on cardiac fibrosis in transverse aortic constriction (TAC) induced pressure overload model in mice. Echocardiography and histological analysis revealed cardiac dysfunction and enhanced cardiac fibrosis in TAC-operated animals; ALDH2 deficiency further aggravated these changes. ALDH2 chimeric mice were generated by bone marrow (BM) transplantation of WT mice into the lethally irradiated ALDH2KO mice. The proportion of circulating fibroblast progenitor cells (FPCs) and ROS level in BM after TAC were significantly higher in ALDH2KO mice than in ALDH2 chimeric mice. Furthermore, FPCs were isolated and cultured for in vitro mechanistic studies. The results showed that the stem cell-derived factor 1 (SDF-1)/C-X-C chemokine receptor 4 (CXCR4) axis played a major role in the recruitment of FPCs. In conclusion, our research reveals that increased bone marrow FPCs mobilization and myocardial homing contribute to the enhanced cardiac fibrosis and dysfunction induced by TAC in ALDH2 KO mice via exacerbating accumulation of ROS in BM and myocardial SDF-1 expression.

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.

Metabolites of Hypoxic Cardiomyocytes Induce the Migration of Cardiac Fibroblasts.

BACKGROUND: The migration of cardiac fibroblasts to the infarct region plays a major role in the repair process after myocardial necrosis or damage. However, few studies investigated whether early hypoxia in cardiomyocytes induces the migration of cardiac fibroblasts. The purpose of this study was to assess the role of metabolites of early hypoxic cardiomyocytes in the induction of cardiac fibroblast migration. METHODS: Neonatal rat heart tissue was digested with a mixture of trypsin and collagenase at an appropriate ratio. Cardiomyocytes and cardiac fibroblasts were cultured via differential adhesion. The cardiomyocyte cultures were subjected to hypoxia for 2, 4, 6, 8, 10, and 12 h. The supernatants of the cardiomyocyte cultures were collected to determine the differences in cardiac fibroblast migration induced by hypoxic cardiomyocyte metabolites at various time points using a Transwell apparatus. Meanwhile, ELISA was performed to measure TNF-α, IL-1ß and TGF-ß expression levels in the cardiomyocyte metabolites at various time points. RESULTS: The metabolites of hypoxic cardiomyocytes significantly induced the migration of cardiac fibroblasts. The induction of cardiac fibroblast migration was significantly enhanced by cardiomyocyte metabolites in comparison to the control after 2, 4, and 6 h of hypoxia, and the effect was most significant after 2 h. The expression levels of TNF-α, IL-1ß, IL-6, and TGF-ß were substantially increased in the metabolites of cardiomyocytes, and neutralization with anti-TNF-α and anti-IL-1ß antibodies markedly reduced the induction of cardiac fibroblast migration by the metabolites of hypoxic cardiomyocytes. CONCLUSION: The metabolites of early hypoxic cardiomyocytes can induce the migration of cardiac fibroblasts, and TNF-α and IL-1ß may act as the initial chemotactic inducers.

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.

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.

CCL11 released by GSDMD-mediated macrophage pyroptosis regulates angiogenesis after hindlimb ischemia.

Peripheral vascular disease (PVD) is an emerging public health burden with a high rate of disability and mortality. Gasdermin D (GSDMD) has been reported to exert pyroptosis and play a critical role in the pathophysiology of many cardiovascular diseases. We ought to determine the role of GSDMD in the regulation of perfusion recovery after hindlimb ischemia (HLI). Our study revealed that GSDMD-mediated pyroptosis occurred in HLI. GSDMD deletion aggravated perfusion recovery and angiogenesis in vitro and in vivo. However, how GSDMD regulates angiogenesis after ischemic injury remains unclear. We then found that GSDMD-mediated pyroptosis exerted the angiogenic capacity in macrophages rather than endothelial cells after HLI. GSDMD deletion led to a lower level of CCL11 in mice serum. GSDMD knockdown in macrophages downregulated the expression and decreased the releasing level of CCL11. Furthermore, recombinant CCL11 improved endothelial functions and angiogenesis, which was attenuated by CCL11 antibody. Taken together, these results demonstrate that GSDMD promotes angiogenesis by releasing CCL11, thereby improving blood flow perfusion recovery after hindlimb ischemic injury. Therefore, CCL11 may be a novel target for prevention and treatment of vascular ischemic diseases.

Soluble interleukin-2 receptor predicts acute kidney injury and in-hospital mortality in patients with acute myocardial infarction.

BACKGROUND: Acute kidney injury (AKI) is the most common and critical complication in patients with acute myocardial infarction (AMI). This study aims to evaluate the significance of elevated soluble interleukin 2 receptor (sIL-2R) levels in predicting AKI and mortality. METHODS: A total of 446 patients with AMI were enrolled between January 2020 and July 2022, including 58 patients with AKI and 388 without AKI. The sIL-2R levels were measured using a commercially available chemiluminescence enzyme immunoassay. Logistic regression analysis was used to examine the risk factors for AKI. Discrimination was assessed based on the area under the receiver operating characteristic curve. The model was internally validated using 10-fold cross-validation. RESULTS: During hospitalization, 13% of patients developed AKI following AMI, with higher sIL-2R levels (0.61 ± 0.27 U/L vs. 0.42 ± 0.19 U/L, p = 0.003) and in-hospital all-cause mortality (12.1% vs. 2.6%, P < 0.001). The sIL-2R levels emerged as an independent risk factor for both AKI (OR = 5.08, 95% CI (1.04-24.84, p < 0.045) and in-hospital all-cause mortality (OR = 73.57,95% CI 10.24-528.41, p < 0.001) in AMI patients. The sIL-2R levels were found to be useful biomarkers in prediction of AKI and in-hospital all-cause mortality in patients with AMI (AUC: 0.771 and 0.894, respectively). The respective cutoff values for sIL-2R levels in predicting AKI and in-hospital all-cause mortality were determined to be 0.423 U/L and 0.615 U/L. CONCLUSIONS: The level of sIL-2R was an independent risk factor and predictor for both AKI and in-hospital all-cause mortality in patients with AMI. These findings highlight the potential of sIL-2R as a valuable tool for identifying high-risk patients regarding AKI and in-hospital mortality.

Aldehyde Dehydrogenase 2 (ALDH2) Elicits Protection against Pulmonary Hypertension via Inhibition of ERK1/2-Mediated Autophagy.

Pulmonary hypertension (PH) is caused by chronic hypoxia that induces the migration and proliferation of pulmonary arterial smooth muscle cells (PASMCs), eventually resulting in right heart failure. PH has been related to aberrant autophagy; however, the hidden mechanisms are still unclear. Approximately 40% East Asians, equivalent to 8% of the universal population, carry a mutation in Aldehyde dehydrogenase 2 (ALDH2), which leads to the aggregation of noxious reactive aldehydes and increases the propensity of several diseases. Therefore, we explored the potential aspect of ALDH2 in autophagy associated with PH. In vitro mechanistic studies were conducted in human PASMCs (HPASMCs) after lentiviral ALDH2 knockdown and treatment with platelet-derived growth factor-BB (PDGF-BB). PH was induced in wild-type (WT) and ALDH2-knockout (ALDH2-/-) mice using vascular endothelial growth factor receptor inhibitor SU5416 under hypoxic conditions (HySU). Right ventricular function was assessed using echocardiography and invasive hemodynamic monitoring. Histological and immunohistochemical analyses were performed to evaluate pulmonary vascular remodeling. EdU, transwell, and wound healing assays were used to evaluate HPASMC migration and proliferation, and electron microscopy and immunohistochemical and immunoblot assays were performed to assess autophagy. The findings demonstrated that ALDH2 deficiency exacerbated right ventricular pressure, hypertrophy, fibrosis, and right heart failure resulting from HySU-induced PH. ALDH2-/- mice exhibited increased pulmonary artery muscularization and 4-hydroxynonenal (4-HNE) levels in lung tissues. ALDH2 knockdown increased PDGF-BB-induced PASMC migration and proliferation and 4-HNE accumulation in vitro. Additionally, ALDH2 deficiency increased the number of autophagosomes and autophagic lysosomes together with autophagic flux and ERK1/2-Beclin-1 activity in lung tissues and PASMCs, indicating enhanced autophagy. In conclusion, the study shows that ALDH2 has a protective role against the migration and proliferation of PASMCs and PH, possibly by regulating autophagy through the ERK1/2-Beclin-1 pathway.

Gasdermin D mediates endoplasmic reticulum stress via FAM134B to regulate cardiomyocyte autophagy and apoptosis in doxorubicin-induced cardiotoxicity.

Cardiomyocyte pyroptosis and apoptosis play a vital role in the pathophysiology of several cardiovascular diseases. Our recent study revealed that gasdermin D (GSDMD) can promote myocardial I/R injury via the caspase-11/GSDMD pathway. We also found that GSDMD deletion attenuated myocardial I/R and MI injury by reducing cardiomyocyte apoptosis and pyroptosis. However, how GSDMD mediates cardiomyocyte apoptosis and protects myocardial function remains unclear. Here, we found that doxorubicin (DOX) treatment resulted in increased apoptosis and pyroptosis in cardiomyocytes and that caspase-11/GSDMD could mediate DOX-induced cardiotoxicity (DIC) injury. Interestingly, GSDMD overexpression promoted cardiomyocyte apoptosis, which was attenuated by GSDMD knockdown. Notably, GSDMD overexpression exacerbated DIC injury, impaired cardiac function in vitro and in vivo, and enhanced DOX-induced cardiomyocyte autophagy. Mechanistically, GSDMD regulated the activity of FAM134B, an endoplasmic reticulum autophagy receptor, by pore formation on the endoplasmic reticulum membrane via its N-terminus, thus activating endoplasmic reticulum stress. In turn, FAM134B interacted with autophagic protein LC3, thus inducing cardiac autophagy, promoting cardiomyocyte apoptosis, and aggravating DIC. These results suggest that GSDMD promotes autophagy and induces cardiomyocyte apoptosis by modulating the reaction of FAM134B and LC3, thereby promoting DIC injury. Targeted regulation of GSDMD may be a new target for the prevention and treatment of DIC.

Apelin protects against ischemia-reperfusion injury in diabetic myocardium via inhibiting apoptosis and oxidative stress through PI3K and p38-MAPK signaling pathways.

Among all diabetes mellitus-associated cardiovascular diseases, morbidity of diabetic myocardium with ischemia reperfusion injury (D-IRI) is increasing year by year. We aimed to discover a therapeutic biomarker and investigate its mechanism in D-IRI. High-fat diet and streptozotocin-induced diabetes rats were operated with IRI or sham. Recombined lentiviral vector encoding Apelin was injected into D-IRI rat via tail vein. Cardiac function, infarct size, cellular death and oxidative stress were major outcome measures. Cardiomyocyte ischemia reperfusion injury was more serious in D-IRI rats than in non-diabetes ischemia reperfusion injury (ND-IRI) rats. The secretion of NTproBNP was increased in D-IRI compared with ND-IRI. Bcl-2 expression was decreased, and Bax and cleaved caspase-3 expression was increased in D-IRI rats compared with ND-IRI rats, which were reversed after treatment with Apelin. Apelin-upregulation improved cardiomyocyte ischemia reperfusion injury and decreased NT-proBNP levels in D-IRI rats. Apelin overexpression enhanced PI3K and eNOS levels while reduced those of p38-MAPK and iNOS in D-IRI rats. Apelin overexpression protected against D-IRI through inhibiting apoptosis and oxidative stress via PI3K and p38MAPK signaling pathways in D-IRI rats. These findings provide critical new insight into understanding of Apelin's cardio-protective effects, which may become a novel therapeutic target for the diabetic IRI patients.

The selective NLRP3-inflammasome inhibitor MCC950 reduces myocardial fibrosis and improves cardiac remodeling in a mouse model of myocardial infarction.

BACKGROUND/AIMS: Early inflammatory responses after myocardial infarction (MI) are likely to increase myocardial fibrosis and subsequent cardiac remodeling. MCC950, a specific NLRP3 inhibitor, was previously found to effectively inhibit the release of inflammatory factors IL-18 and IL-1ß. In this study, we evaluated the effect of MCC950, as a potential new treatment strategy for MI, on myocardial fibrosis and cardiac remodeling using an experimental mouse model. METHODS: Male C57BL/6 mice were subjected to left coronary artery ligation to induce MI and then treated with MCC950 (10 mg/kg) or PBS for 14 days. After 30 days, echocardiography was performed to assess cardiac function and myocardial fibrosis was evaluated using H&E- and Masson's Trichrome-stained sections. Myocardial expression of inflammatory factors and fibrosis markers was analyzed by western blotting, immunofluorescence, ELISA, and real-time quantitative PCR. RESULTS: The ejection fraction in the 10 mg/kg group (40.7 ±â€¯4.2%; N = 6, p = 0.0029) was statistically preserved compared to that in the control group (14.0 ±â€¯4.4%). Myocardial fibrosis was also reduced in MCC950-treated animals (MCC950, 23.2 ±â€¯3.0 vs PBS, 36.2 ±â€¯3.7; p < 0.05). Moreover, myocardial NLRP3, cleaved IL-1ß, and IL-18 levels were reduced in MCC950-treated animals. H&E and molecular examination revealed decreases in inflammatory cell infiltration and inflammatory factor expression in the heart. In vitro, MCC950 inhibited NLRP3, reduced caspase-1 activity, and further downregulated IL-1ß and IL-18. CONCLUSION: MCC950, as a specific NLRP3 inhibitor, can alleviate fibrosis and improve cardiac function in a mouse model by suppressing early inflammatory responses post-MI.

Naoxintong Retards Atherosclerosis by Inhibiting Foam Cell Formation Through Activating Pparα Pathway.

BACKGROUNDS: We recently reported that Naoxintong (NXT), a China Food and Drug Administration (FDA)-approved cardiac medicine, could reduce the plaque size, but the underlying mechanism remains elusive now. OBJECTIVE: In this study, we investigated the effects of NXT on foam cell accumulation both in vivo and in vitro and explored related mechanisms. METHOD: THP-1 cells and bone marrow-derived macrophages were incubated with oxidized low-density lipoprotein (ox-LDL) with/without Naoxintong. ApoE-/- mice fed an atherogenic diet were administered to receive NXT for eight weeks. Macrophage-derived foam cell formation in plaques was measured by immunohistochemical staining. Expression of proteins was evaluated by Western blot. Lentivirus was used to knockdown PPARα in THP-1 cells. RESULTS: After NXT treatment, foam cell accumulation was significantly reduced in atherosclerotic plaques. Further investigation revealed that oxidized low-density lipoprotein (ox-LDL) uptake was significantly decreased and expression of scavenger receptor class A (SR-A) and class B (SR-B and CD36) was significantly downregulated post-NXT treatment. On the other hand, NXT increased cholesterol efflux and upregulated ATP-binding cassette (ABC) transporters (ABCA-1 and ABCG-1) in macrophages. Above beneficial effects of NXT were partly abolished after lentiviral knockdown of PPARα. CONCLUSION: Our findings suggest that NXT could retard atherosclerosis by inhibiting foam cell formation through reducing ox-LDL uptake and enhancing cholesterol efflux and above beneficial effects are partly mediated through PPARα pathway.

Digoxin reduces atherosclerosis in apolipoprotein E-deficient mice.

BACKGROUND AND PURPOSE: Numerous in vitro studies have suggested that digoxin suppresses inflammation and alters lipid metabolism. However, the effect of dioxin on atherosclerosis is poorly understood. The present study was conducted to determine whether digoxin affects the development of atherosclerosis in a murine model of atherosclerotic disease. EXPERIMENTAL APPROACH: Apolipoprotein E-deficient mice maintained on a Western-type diet were administered PBS (control), low-dose digoxin (1 mg · kg(-1) · day(-1)) or high-dose digoxin (2 mg · kg(-1) · day(-1)) via i.p. injection for 12 weeks. KEY RESULTS: Digoxin dose-dependently reduced atherosclerotic lesion formation and plasma lipid levels (reductions of 41% in total cholesterol, 54% in triglycerides and 20% in low-density lipoprotein cholesterol in the high-dose digoxin-treated group). Moreover, treatment with digoxin markedly attenuated IL-17A expression and IL-17A-related inflammatory responses and increased the abundance of regulatory T cells (Tregs). CONCLUSIONS AND IMPLICATIONS: Our data demonstrate that digoxin acts as a specific antagonist of retinoid-related orphan receptor-γ to decrease atherosclerosis by suppressing lipid levels and IL-17A-related inflammatory responses.

Lanatoside C Promotes Foam Cell Formation and Atherosclerosis.

Lanatoside C's impact on atherosclerosis is poorly understood. The present study was conducted to determine whether lanatoside C affects the development of atherosclerosis in apolipoprotein E-deficient (ApoE(-/-)) mice. ApoE(-/-) mice were administered either phosphate-buffered saline (PBS) containing 0.1% DMSO (the vehicle control group) or lanatoside C at low (1 mg/kg per day) or high (2 mg/kg per day) doses, and fed a Western diet for 12 weeks. Lanatoside C dose-dependently aggravated the development of atherosclerosis in the ApoE(-/-) mice compared with the vehicle control group. In an effort to determine the mechanism by which lanatoside C increased atherosclerosis, we found that lanatoside C significantly promoted the uptake of oxidised low-density lipoprotein (oxLDL) and increased foam-cell formation by upregulation of scavenger receptor class A (SR-A) and the class B scavenger receptor (CD36) in macrophages. Meanwhile, the effects of lanatoside C were abolished using small interfering RNA (siRNA) inhibition of peroxisome proliferator-activated receptors ß/δ (PPARß/δ). Overall, our data demonstrate that lanatoside C aggravates the development of atherosclerosis by inducing PPARß/δ expression, which mediates upregulation of SR-A and CD36, and promotes oxLDL uptake and foam-cell formation.

Interleukin-37 and Dendritic Cells Treated With Interleukin-37 Plus Troponin I Ameliorate Cardiac Remodeling After Myocardial Infarction.

BACKGROUND: Excessive immune-mediated inflammatory reactions play a deleterious role in postinfarction ventricular remodeling. Interleukin-37 (IL-37) emerges as an inhibitor of both innate and adaptive immunity. However, the exact role of IL-37 and IL-37 plus troponin I (TnI)-treated dendritic cells (DCs) in ventricular remodeling after myocardial infarction (MI) remains elusive. METHODS AND RESULTS: MI was induced by permanent ligation of the left anterior descending artery. Our results showed that treatment with recombinant human IL-37 significantly ameliorated ventricular remodeling after MI, as demonstrated by decreased infarct size, better cardiac function, lower mortality, restricted inflammatory responses, decreased myocardial fibrosis, and inhibited cardiomyocyte apoptosis. In vitro, we examined the phenotype of IL-37 plus TnI-conditioned DCs of male C57BL/6 mice and their capacity to influence the number of regulatory T cells. Our results revealed that IL-37 plus TnI-conditioned DCs obtained the characteristics of tolerogenic DCs (tDCs) and expanded the number of regulatory T cells when co-cultured with splenic CD4+ T cells. Interestingly, we also found that adoptive transfer of these antigen-loaded tDCs markedly increased the number of regulatory T cells in the spleen, attenuated the infiltration of inflammatory cells in the infarct hearts, decreased myocardial fibrosis, and improved cardiac function. CONCLUSIONS: Our results reveal a beneficial role of IL-37 or tDCs treated with IL-37 plus TnI in post-MI remodeling that is possibly mediated by reestablishing a tolerogenic immune response, indicating that IL-37 or adoptive transfer of IL-37 plus TnI-treated tDCs may be a novel therapeutic strategy for ventricular remodeling after MI.