Increased IL-37 in Atherosclerotic Disease could be Suppressed by Atorvastatin Therapy

Anti-Inflammatory Effect of Atorvastatin and Rosuvastatin on Monosodium Urate-Induced Inflammation through IL-37/Smad3-Complex Activation in an In Vitro Study Using THP-1 Macrophages

Objective: The pleiotropic effect of hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) is responsible for potent defense against inflammatory response. This study evaluated the inhibitory effects of HMG-CoA reductase inhibitors on the monosodium urate (MSU)-induced inflammatory response through the regulation of interleukin-37 (IL-37) expression. Methods: Serum was collected from patients with gout (n = 40) and from healthy controls (n = 30). The mRNA and protein expression of the target molecules IL-1β, IL-37, caspase-1, and Smad3 were measured in THP-1 macrophages stimulated with MSU, atorvastatin, or rosuvastatin using a real-time quantitative polymerase chain reaction and Western blot assay. Transfection with IL-1β or Smad3 siRNA in THP-1 macrophages was used to verify the pharmaceutical effect of statins in uric-acid-induced inflammation. Results: Serum IL-37 levels in gout patients were significantly higher than in controls (p < 0.001) and was associated with the serum uric acid level (r = 0.382, p = 0.008). THP-1 cells stimulated with MSU markedly induced IL-37 mRNA expression and the transition of IL-37 from the cytoplasm to the nucleus. Recombinant IL-37 treatment dose-dependently inhibited activation of caspase-1 and IL-1β in MSU-induced inflammation. Atorvastatin and rosuvastatin attenuated caspase-1 activation and mature IL-1β expression but augmented translocation of IL-37 from the cytoplasm to the nucleus. Atorvastatin and rosuvastatin induced phosphorylation of Smad3 in THP-1 cells treated with MSU crystals. Statins potently attenuated translocation of IL-37 from the cytoplasm to the nucleus in THP-1 macrophages transfected with Smad3 siRNA compared to cells with negative control siRNA. Conclusions: This study revealed that statins inhibit the MSU-induced inflammatory response through phosphorylated Smad3-mediated IL-37 expression in THP-1 macrophages.

The effect of lipid-lowering therapies on the pro-inflammatory and anti-inflammatory properties of vascular endothelial cells

Atherosclerosis and cardiovascular events can be prevented, or treated, using statin therapy, either alone or in combination with ezetimibe. Chronic inflammation, vascular proliferation, and the development of atherosclerosis are also influenced by 25-hydroxycholesterol (25-OHC). The aim of the study was to compare the direct pleiotropic effects of two commonly-used statins (atorvastatin, rosuvastatin), ezetimibe, and their combinations, on the mRNA expression of pro-inflammatory IL1β, IL-18 and IL-23 and anti-inflammatory TGFβ, IL-35 (EBI3, IL-12 subunits), IL-10 and IL-37, in endothelial cells damaged by 25-OHC. It also analyzed IL-35 expression at the protein level. HUVECs were stimulated with atorvastatin (5 μM), rosuvastatin (10 μM), ezetimibe (1.22 μM), atorvastatin-ezetimibe (5 μM + 1.22 μM) or rosuvastatin-ezetimibe (10 μM + 1.22 μM), with or without pre-incubation with 10 μg/mL 25-OHC. mRNA expression was analyzed by real-time PCR. The protein level of IL-35 was analyzed by ELISA. In the pre-stimulated HUVECs, atorvastatin and rosuvastatin decreased mRNA expression of IL1β, IL-18, IL-23, TGFβ, IL35 and increased mRNA expression of IL-10 and IL-37 compared to 25-OHC. Furthermore, only incubation with rosuvastatin and rosuvastatin-ezetimibe decreased IL-35 mRNA and protein levels. Ezetimibe down-regulated only IL1β. Treatment with rosuvastatin-ezetimibe and atorvastatin-ezetimibe reversed the effect of 25-OHC in IL1β, IL-18 and IL-35 mRNA expression. In conclusion, rosuvastatin has the strongest anti-inflammatory effects and is the best at reducing the effect of oxysterols. Both statins exert a greater anti-inflammatory effect than ezetimibe. The anti-inflammatory effect of the combination therapies appears to be based on the effects of the statins alone and not their combination with ezetimibe.

Pioglitazone combined with atorvastatin promotes plaque stabilization in a rabbit model

OBJECTIVE

It is not yet clear whether plaque inflammation and cardiovascular events are reduced further when pioglitazone and atorvastatin are combined. Our study aimed to determine whether pioglitazone combined with atorvastatin can restrain the progression of atherosclerosis and promote plaque stabilization in a rabbit model.

METHOD AND RESULT

Thirty rabbits were randomly divided into an atherosclerosis group, an atorvastatin group, and an atorvastatin plus pioglitazone group. The atherosclerosis model was induced using balloon injury and feeding a high-fat diet. Plasma samples were then used to analyze glucose, triglycerides (TG), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), high-sensitivity C-reactive protein (hs-CRP), and matrix metalloproteinase-9 (MMP-9). The area percentage of atherosclerotic plaques was analyzed by hematoxylin-eosin staining. The relative reductions in TG and LDL-C and the increase in HDL-C levels were significantly greater in the combination therapy group than in the atorvastatin monotherapy group (TG: -33.60 ± 7.17% vs -24.16 ± 8.04%, p < 0.001; LDL-C: -42.89 ± 1.63% vs -37.13 ± 1.35%, p < 0.001; and HDL-C: 25.18 ± 5.53% vs 10.43 ± 6.31%, p < 0.001). The relative reductions in hs-CRP and MMP-9 levels were significantly greater in the combination therapy group than in the atorvastatin monotherapy group (-69.38 ± 1.06% vs-53.73 ± 1.92%, p < 0.001; -32.77 ± 2.49% vs -13.36 ± 1.66%, p < 0.001). The area percentage of atherosclerotic plaques was significantly smaller in the atorvastatin group (47.75%, p < 0.05) and in the atorvastatin plus pioglitazone group (22.57%, p < 0.05) than in the atherosclerosis group (84.08%, p < 0.05).

CONCLUSION

We can thus conclude that the combination treatment of atorvastatin and pioglitazone provided additive benefits on inflammatory parameters and lipid metabolism. Pioglitazone combined with atorvastatin can further restrain the progression of atherosclerosis and promote plaque stabilization in a rabbit model.

Clinical Implications of IL-32, IL-34 and IL-37 in Atherosclerosis: Speculative Role in Cardiovascular Manifestations of COVID-19

Atherosclerosis, which is a primary cause of cardiovascular disease (CVD) deaths around the world, is a chronic inflammatory disease that is characterised by the accumulation of lipid plaques in the arterial wall, triggering inflammation that is regulated by cytokines/chemokines that mediate innate and adaptive immunity. This review focuses on IL-32, -34 and -37 in the stable vs. unstable plaques from atherosclerotic patients. Dysregulation of the novel cytokines IL-32, -34 and -37 has been discovered in atherosclerotic plaques. IL-32 and -34 are pro-atherogenic and associated with an unstable plaque phenotype; whereas IL-37 is anti-atherogenic and maintains plaque stability. It is speculated that these cytokines may contribute to the explanation for the increased occurrence of atherosclerotic plaque rupture seen in patients with COVID-19 infection. Understanding the roles of these cytokines in atherogenesis may provide future therapeutic perspectives, both in the management of unstable plaque and acute coronary syndrome, and may contribute to our understanding of the COVID-19 cytokine storm.

The emerging role of Interleukin 37 in bone homeostasis and inflammatory bone diseases

Interleukin 37 (IL-37) is a newly identified cytokine that belongs to the IL-1 family. Unlike other members of the IL-1 family, it has been demonstrated that IL-37 possesses anti-inflammatory characteristics in both innate and acquired immune responses. Recently, significant progress has been made in understanding the role of IL-37 in inflammatory signaling pathways. Meanwhile, IL-37 has also attracted more and more attention in bone homeostasis and inflammatory bone diseases. The latest studies have revealed that IL-37 palys an essential role in the regulation of osteoclastogenesis and osteoblastogenesis. The levels of IL-37 are abnormal in patients with inflammatory bone diseases such as rheumatoid arthritis (RA), osteoarthritis (OA), ankylosing spondylitis (AS), and periodontitis. In addition, in vivo studies have further confirmed that recombinant IL-37 treatment displayed therapeutic potential in these diseases. The present review article aims to provide an overview describing the biological functions of IL-37 in bone homeostasis and inflammatory bone diseases, thus shedding new light on a novel therapeutic strategy in the future.

The novel role of IL-37 to enhance the anti-inflammatory response of regulatory T cells in patients with peripheral atherosclerosis

OBJECTIVES

Regulatory T cells (Tregs) mediate immunomodulation and protect against atherosclerosis. It is considered that reducing the amount of pro-inflammatory mediators could be achieved by enhancing the anti-inflammatory response, and this may be considered one of the main targets for therapy development. The inhibitory cytokines secreted by Tregs mainly include interleukin-10 (IL-10) and transforming growth factor-beta (TGF-β). Based on its known immunosuppressive involvement with other inflammatory disorders, we hypothesized that the newly characterized cytokine interleukin-37 (IL-37) might be associated with the inhibitory functions of Treg in atherosclerosis. Immune regulatory functions of IL-37 have not been completely clarified. Accordingly, we speculated that IL-37 might play a regulatory role in the immunosuppression of Tregs in atherosclerotic disease.

METHODS

Real-time polymerase chain reaction and enzyme linked immunosorbent assay were used to test gene expression and protein levels of IL-37 in peripheral blood and localized freshly resected arterial tissues from 84 patients with peripheral arterial occlusive disease and 50 non-atherosclerotic subjects. Results were correlated to disease hallmarks. We also evaluated the ability of recombinant IL-37 to modulate Treg cytokine secretion and T cell inhibition in relation to atherosclerotic disorder in vitro.Results: Our results revealed that IL-37 was increased in patients with chronic lower limb atherosclerotic ischemia, compared to non-atherosclerotic controls. In addition, the expression levels of circulating IL-37 correlated with disease severity of chronic lower limb ischemia. Supplementation with rIL-37 augmented levels of released IL-10 and TGF-β in supernatants of T cells co-cultured with Tregs in the enrolled patients.Conclusions: Results suggest a role for IL-37 in mediating anti-inflammatory functions in the atherosclerotic process, potentially involving enhancement of Treg inhibitory function and anti-inflammatory cytokine secretion with a particularly marked direct response in severe disease.

Interleukin-37: The Effect of Anti-Inflammatory Response in Human Coronary Artery Endothelial Cells

Interleukin-37 (IL-37) is unique in the IL-1 family since it broadly suppresses innate immunity and elevates in humans with inflammatory and autoimmune diseases. IL-37 shows definite groups and transcripts for human IL37 gene, but it is still not completely understood the effect and mechanisms of inflammatory response in endothelial cells. It is well accepted that endothelial dysfunction caused by inflammation is a key initiating event in atherosclerotic plaque formation, which leads to the occurrence and development of the cardiovascular adverse events in clinical since the inflammatory responses of endothelial cells could induce and enhance the deposition of extensive lipid and the formation of atherosclerotic plaque in the intima. Thus, it is essential to investigate the role and potential mechanisms in endothelial inflammatory response to prevent the formation and development of many cardiovascular diseases including atherosclerosis. So far, the recent studies have revealed that IL-37 is able to inhibit inflammatory response by suppressing the TLR2-NF-κB-ICAM-1 pathway intracellularly in human coronary artery endothelial cells (HCAECs). Further, the role of IL-37 may be related to the IL-18 pathway extracellularly and involved in the adhesion and transmigration of neutrophils in HCAECs.

Atorvastatin, losartan and captopril may upregulate IL-22 in hypertension and coronary artery disease; the role of gene polymorphism

AIMS

Interleukin-22 (IL-22) may be considered as an important cytokine in maintenance and progression of hypertension and coronary artery disease (CAD). The aim of the present study was to investigate the effect of treatment of hypertension and CAD on serum levels of IL-22 and the possible association of IL-22-rs1179251 gene polymorphism with hypertension and CAD.

MATERIALS AND METHODS

A total of 286 subjects with suspected CAD were enrolled. Serum levels and gene polymorphism of IL-22 were investigated in hypertensive patients with no CAD (H-Tens), hypertensive patients with CAD (CAD + H-Tens); 3), CAD patients with no hypertension (CAD); and non-hypertensive with no CAD subjects as a control group (Ctr). The patients received routine medications for hypertension and CAD. Serum IL-22 levels and IL-22-rs1179251 gene polymorphism were evaluated using ELISA and RFLP-/PCR techniques, respectively.

KEY FINDINGS

Findings demonstrated that there were significantly higher levels of IL-22 in case groups (H-Tens, CAD + H-Tens, and CAD) compared to the Ctr group (P = 0.001, P = 0.014, and P < 0.001, respectively). Moreover, atorvastatin, losartan and captopril were administered significantly more in patients compared to the Ctr group. The results indicated a decreased risk of CAD + H-Tens of rs1179251 dominant genetic model (OR = 0.324; 95% CI = 0.121-0.873; P = 0.026).

SIGNIFICANCE

Atorvastatin, losartan and captopril may be led to upregulation of IL-22 in CAD and hypertensive patients. Meanwhile, higher levels of circulating IL-22 could contribute to alleviating the hypertension and CAD conditions. The G allele of IL-22 rs1179251 may be a protective factor for concomitant hypertension and CAD.

Elevated plasma interleukin-37 playing an important role in acute coronary syndrome through suppression of ROCK activation

OBJECTIVE

The plasma level of interleukin-37 is elevated in patients with acute coronary syndrome, however, its function during the onset and progress of the disease remains unclear. This study aimed to investigate the clinical significance of IL-37 in acute coronary syndrome and its underlying mechanism.

METHODS

124 patients with acute coronary syndrome and 40 healthy controls were recruited in this study. Plasma interleukin-37 levels were measured in 41 patients with ST elevation myocardial infarction (STEMI), 41 patients with non-STEMI, 42 patients with unstable angina, and 40 controls. Mortality was defined as an event.

RESULTS

In this study, the mean follow-up period was 824±306 days (2-1077 days). 22% (n=27) of patients died. The mortality rate was significantly lower in patients with interleukin-37 serum levels below the median (6.4 pg/mL) than those with interleukin-37 serum levels above 6.4 pg/mL at 36-month follow-up (16% vs. 24%, p=0.02, log rank X2=5.39). Highly concentration of the anti-inflammatory interleukin-37 exerted a protective effect by suppressing the activated Rho Kinase (ROCK) activity in the peripheral blood mononuclear cells in vivo and in vitro after ischemia/reperfusion injury and stimulation of the Rho activator, calpeptin.

CONCLUSIONS

The interleukin-37 level is significantly increased in acute coronary syndrome. Elevated baseline interleukin-37 levels in patients on admission are associated with poor outcomes. Thus, we propose that interleukin-37 could be a biomarker predictive of mortality in acute coronary syndrome. Moreover, this study reveals that the protective effect of interleukin-37 against atherosclerosis may involve the inhibition of ROCK activity.

Potential role of IL-37 in atherosclerosis

IL-37 is a member of the IL-1 family, but unlike most other members of this family of cytokines, it has wide-ranging anti-inflammatory properties. Initially shown to bind IL-18 binding protein and prevent IL-18-mediated inflammation, its known role has been expanded to include distinct pathways, both intracellular involving the transcription factor Smad3, and extracellular via binding to the orphan receptor IL-1R8. A number of recent publications investigating the role of IL-37 in atherosclerosis and ischemic heart disease have revealed promising therapeutic value of the cytokine. Although research concerning the role of IL-37 and its mechanism in atherosclerosis is relatively scant, there are a number of well-known atherosclerotic processes that this cytokine can mediate with the potential of modulating the disease progression itself. This review will probe in detail the effects of IL-37 on important pathological processes such as inflammation, dysregulated lipid metabolism, and apoptosis, by analyzing existing data as well as exploring the potential of this cytokine to influence these properties.

IL-37 increased in patients with acute coronary syndrome and associated with a worse clinical outcome after ST-segment elevation acute myocardial infarction

BACKGROUND

IL-37 emerges as a natural suppressor of inflammatory responses. The potential role of IL-37 in the pathology of atherosclerosis is unclear. The purpose of this study was to assess IL-37 profile in acute coronary syndrome (ACS) and the prognostic role of this cytokine in patients with ST-segment elevation acute myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI).

METHODS

In a case-control study, we prospectively enrolled 216 patients undergoing the first coronary angiography, which consisted of 5 groups: normal (n=57), stable angina (SAP, n=36), unstable angina (UAP, n=42), non-STEMI (n=36), STEMI (n=45). Plasma IL-37, IL-6 and serum amyloid A (SAA) were measured using a commercially ELISA kit. Besides, in a prospective cohort study, 125 patients with STEMI of onset <12h undergoing PPCI were enrolled and divided into 2 groups according to the concentrations of IL-37 (<341.1pg/ml or ≥341.1pg/ml). In-hospital major adverse cardiac event (MACE) including nonfatal myocardial infarction (MI), target lesion revascularization, acute heart failure, and cardiac death were estimated for prognosis.

RESULTS

IL-37 was gradually increased in accordance with the severity of coronary artery disease. The circulating concentration of IL-37 was remarkably higher in the ACS patients than in either of the normal or SAP patients (p<0.05), and especially higher in the AMI patients including STEMI and non-STEMI than in the angina pectoris subjects no matter SAP or UAP (p<0.05). There was no statistical difference of IL-37 between normal and SAP patients, STEMI and non-STEMI patients (p>0.05). The trend of the change of IL-37 was consistent with that of SAA or IL-6. A higher circulating concentration of IL-37 before PPCI was accompanied with the decreased LVEF and the increased NT-proBNP concentrations, and independently predictive of in-hospital MACE rate in patients with STEMI undergoing PPCI (OR=3.652, 95% CI=1.113-11.983, p<0.05).

CONCLUSIONS

We demonstrated the IL-37 profile in patients with acute coronary syndrome and the increased IL-37 concentration was associated with a worse clinical in-hospital outcome in STEMI patients undergoing PPCI.

Interleukin-37 suppresses ICAM-1 expression in parallel with NF-κB down-regulation following TLR2 activation of human coronary artery endothelial cells

INTRODUCTION

The inflammatory receptor Toll-like receptors (TLRs) activation could induce endothelial inflammatory responses, which plays an important role in the development of many diseases including atherosclerosis. We already found that TLR2 activation of Peptidoglycan (PGN) stimulation could increase intercellular adhesion molecule-1 (ICAM-1) expression in HCAECs. Since anti-inflammatory cytokine interleukin (IL)-37 exhibits intra- and extracellular properties for suppressing innate inflammation, we want to investigate whether IL-37 suppresses ICAM-1 expression and this effect is in parallel with the inhibition of nuclear factor kappa B (NF-κB) activation upon PGN stimulation in HCAECs.

METHODS

HCAECs were treated with IL-37-transfection plasmid or silent mRNA or nothing for 24h, and we test IL-37 expression by immunoblotting. Same treatments prior to PGN stimulation (10μg/ml), we analyzed the expression of ICAM-1 and NF-κB mRNA at 0, 30min, 1 and 2h by real-time PCR. ICAM-1 protein at 24h and NF-κB activation at 0-2h were measured by immunoblotting.

RESULTS

IL-37 and silent IL-37 transfection change the expression of IL-37 protein. Stimulation of PGN increased both NF-κB activation and ICAM-1 expression at mRNA and protein level, but these inflammatory cytokines' expression was significantly decreased in IL-37-transfection cells. Interestingly, both NF-κB activation and ICAM-1 expression were significantly increased when IL-37 was silent.

CONCLUSIONS

As an anti-inflammatory cytokine, IL-37 could decrease both NF-κB and ICAM-1 expression upon TLR2 activation in HCAECs. The suppressed effect of IL-37 on ICAM-1 may be due to its inhibition on NF-κB.