IL-22 exacerbates the severity of CVB3-induced acute viral myocarditis in IL-17A-deficient mice

Myocarditis: A multi-omics approach

Myocarditis, an inflammatory condition of weakened heart muscles often triggered by a variety of causes, that can result in heart failure and sudden death. Novel ways to enhance our understanding of myocarditis pathogenesis is available through newer modalities (omics). In this review, we examine the roles of various biomolecules and associated functional pathways across genomics, transcriptomics, proteomics, and metabolomics in the pathogenesis of myocarditis. Our analysis further explores the reproducibility and variability intrinsic to omics studies, underscoring the necessity and significance of employing a multi-omics approach to gain profound insights into myocarditis pathogenesis. This integrated strategy not only enhances our understanding of the disease, but also confirms the critical importance of a holistic multi-omics approach in disease analysis.

Cytokines and their role in cardiovascular diseases

The evaluation of diagnostic and prognostic biomarkers has always been a hot topic in various diseases. Considering that cardiovascular diseases (CVDs) have the highest mortality and morbidity rates in the world, various studies have been conducted so far to find CVD associated biomarkers, including cardiac troponin (cTn) and NT-proBNP. Cytokines are components of the immune system that are involved in the pathogenesis of CVD due to their contribution to the inflammation process. The level of cytokines varies in many cardiovascular diseases. For instance, the plasma level of IL-1α, IL-18, IL-33, IL-6 and IL-8 is positively correlated with atherosclerosis and that of some other interleukins such as IL-35 is negatively correlated with acute myocardial infarction or cardiac angina. Due to its pivotal role in the inflammation process, IL-1 super family is involved in many CVDs, including atherosclerosis. IL-20 among the interleukins of IL-10 family has a pro-atherogenic role, while others, such as IL-10 and IL-19, play an anti-atherogenic role. In the present review, we have collected the latest published evidence in this respect to discuss valuable cytokines from the diagnostic and prognostic stand point in CVDs.

Current Knowledge of Th22 Cell and IL-22 Functions in Infectious Diseases

T helper 22 (Th22) cells, a newly defined CD4+ T-cell lineage, are characterized by their distinct cytokine profile, which primarily consists of IL-13, IL-22 and TNF-α. Th22 cells express a wide spectrum of chemokine receptors, such as CCR4, CCR6 and CCR10. The main effector molecule secreted by Th22 cells is IL-22, a member of the IL-10 family, which acts by binding to IL-22R and triggering a complex downstream signaling system. Th22 cells and IL-22 have been found to play variable roles in human immunity. In preventing the progression of infections such as HIV and influenza, Th22/IL-22 exhibited protective anti-inflammatory characteristics, and their deleterious proinflammatory activities have been demonstrated to exacerbate other illnesses, including hepatitis B and Helicobacter pylori infection. Herein, we review the current understanding of Th22 cells, including their definition, differentiation and mechanisms, and the effect of Th22/IL-22 on human infectious diseases. According to studies on Th22 cells, Th22/IL-22 may be a promising therapeutic target and an effective treatment strategy for various infections.

Interleukin-17-A multifaceted cytokine in viral infections

Viral infections are a major threat to the human population due to the lack of selective therapeutic measures. The morbidity and mortality reported worldwide are very alarming against viral pathogens. The proinflammatory environment is required for viral inhibition by initiating the host immune response. The host immune response fights these pathogens by secreting different cytokines. Interleukin-17 (IL-17) a proinflammatory cytokine mainly produced by T helper type 17 cells, plays a vital role in the regulation of host immune response against various pathogens, including viruses. However, dysregulated production of IL-17 induces chronic inflammation, autoimmune disorders, and may lead to cancer. Recent studies suggest that IL-17 is not only involved in the antiviral immune response but also promotes virus-mediated illnesses. In this review, we discuss the protective and pathogenic role of IL-17 against various viral infections. A detailed understanding of IL-17 during viral infections could contribute to improve therapeutic measures and enable the development of an efficient and safe IL-17 based immunotherapy.

Interleukin-22: a potential therapeutic target in atherosclerosis

BACKGROUND

Atherosclerosis is recognized as a chronic immuno-inflammatory disease that is characterized by the accumulation of immune cells and lipids in the vascular wall. In this review, we focus on the latest advance regarding the regulation and signaling pathways of IL-22 and highlight its impacts on atherosclerosis.

MAIN BODY

IL-22, an important member of the IL-10 family of cytokines, is released by cells of the adaptive and innate immune system and plays a key role in the development of inflammatory diseases. The binding of IL-22 to its receptor complex can trigger a diverse array of downstream signaling pathways, in particular the JAK/STAT, to induce the expression of chemokines and proinflammatory cytokines. Recently, numerous studies suggest that IL-22 is involved in the pathogenesis of atherosclerosis by regulation of VSMC proliferation and migration, angiogenesis, inflammatory response, hypertension, and cholesterol metabolism.

CONCLUSION

IL-22 promotes the development of atherosclerosis by multiple mechanisms, which may be a promising therapeutic target in the pathogenesis of atherosclerosis.

Friend or foe of innate lymphoid cells in inflammation-associated cardiovascular disease

As a distinctive population of leucocytes, innate lymphoid cells (ILCs) participate in immune-mediated diseases and play crucial roles in tissue remodelling after injury. ILC lineages can be divided into helper ILCs and cytotoxic ILCs. Most helper ILCs are integrated into the fabric of tissues and produce different types of cytokines involving in the pathogenesis of many kinds of cardiovascular disease and form intricate response circuits with adaptive immune cells. However, the specific phenotype and function of helper ILC subsets in cardiovascular diseases are still poorly understood. In this review, we firstly highlight the distribution of helper ILCs in cardiovascular system and further discuss the potential contribution of helper ILCs in inflammation-associated cardiovascular disease.

Interleukin-22 is elevated in the atrium and plasma of patients with atrial fibrillation and increases collagen synthesis in transforming growth factor-β1-treated cardiac fibroblasts via the JNK pathway

Our previous studies demonstrated that interleukin (IL)-22 is involved in cardiovascular diseases such as hypertension, cardiac fibrosis and aortic dissection. The purpose of the present study was to detect IL-22 expression in patients with atrial fibrillation (AF). Atrial tissue was collected from donors with sinus rhythm and patients with permanent AF, and the expression level of IL-22 and its receptors (IL-22R1 and IL-10R2) in both the left atrium (LA) and right atrium (RA) of each sample was detected. Blood samples were also obtained from donors with paroxysmal, persistent and permanent AF and from donors without AF history, and IL-22 levels were measured. In addition, the effects of IL-22 on collagen synthesis in TGF-β1-treated cardiac fibroblasts were investigated. IL-22R1, IL-10R2 and IL-22 expression was elevated in both the LA and RA in permanent AF patients. Elevated IL-22 expression positively correlated with the collagen areas and fibrosis marker levels in the atria of these patients. Plasma IL-22 levels were higher in AF patients compared with healthy donors and increased with increasing AF duration (from paroxysmal to persistent to permanent AF). A positive correlation was observed between IL-22 levels and TGF-β1 levels in AF patients. In vitro, recombinant mouse IL-22 treatment upregulated α-SMA, collagen I and collagen III expression in TGF-β1-treated cardiac fibroblasts. These effects were reversed by SP600125, an inhibitor of the JNK pathway. To conclude, IL-22 levels are elevated in patients with AF and may exacerbate collagen synthesis in TGF-β1-induced cardiac fibroblasts. IL-22 may also influence AF by activating the JNK pathway.

Effects of IL-22 on cardiovascular diseases

Interleukin-22 (IL-22), which belongs to the IL-10 family, is an alpha helix cytokine specifically produced by many lymphocytes, such as Th1, Th17, Th22, ILCs, CD4+ and CD8+ T cells. In recent years, more and more studies have demonstrated that IL-22 has an interesting relationship with various cardiovascular diseases, including myocarditis, myocardial infarction, atherosclerosis, and other cardiovascular diseases, and IL-22 signal may play a dual role in cardiovascular diseases. Here, we summarize the recent progress on the source, function, regulation of IL-22 and the effects of IL-22 signal in cardiovascular diseases. The study of IL-22 will suggest more specific strategies to maneuver these functions for the effective treatment of cardiovascular diseases and future clinical treatment.

Anti-Interleukin-22-Neutralizing Antibody Attenuates Angiotensin II-Induced Cardiac Hypertrophy in Mice

BACKGROUND

Interleukin- (IL-) 22 is considered a proinflammatory cytokine. Recent evidence has demonstrated that it plays a role in cardiovascular diseases. In the recent study, we investigate whether IL-22 is involved in cardiac hypertrophy.

METHODS

Angiotensin II was used to build hypertrophy model and the IL-22 and IL-22 receptor 1 (IL-22R1) levels in heart tissue were measured. In addition, angiotensin II-treated mice received an injection of anti-IL-22-neutralizing antibody (nAb) to investigate the effects of IL-22 nAb on myocardial hypertrophy, cardiac function, and cardiac fibrosis; the activation of the signaling pathway and the prohypertrophic inflammatory cytokine mRNA levels was detected. Furthermore, the effect of IL-22 nAb on angiotensin II-induced hypertrophy in vitro was also determined.

RESULTS

IL-22 and IL-22R1 levels were significantly increased after angiotensin II infusion. Anti-IL-22 nAb significantly alleviated the severity of hypertrophy, prevented systolic and diastolic abnormalities, reduced cardiac fibrosis, STAT3 and ERK phosphorylation, and downregulated the mRNA expression of IL-17, IL-6, IL-1β, IFN-γ, and TNF-α. In addition, IL-22 nAb attenuated angiotensin II-induced hypertrophy in H9C2 cells.

CONCLUSION

Our data demonstrated that neutralization of IL-22 alleviated angiotensin II-induced cardiac hypertrophy. The downregulation of IL-22 may be a novel therapeutic strategy to prevent cardiac hypertrophy.

Interleukin 22 Promotes Blood Pressure Elevation and Endothelial Dysfunction in Angiotensin II-Treated Mice

BACKGROUND

CD4+ T helper (Th) cells, including Th1, Th2, and Th17 cells, play critical roles in angiotensin II-induced hypertension. Th22 cells, a novel subset of Th cells, take part in cardiovascular diseases by producing IL-22 (interleukin 22). This study aimed to investigate whether IL-22 is involved in hypertension.

METHODS AND RESULTS

Th22 cells and IL-22 levels were detected in angiotensin II-infused mice, and the results showed that Th22 cells and IL-22 levels significantly increased. To determine the effect of Th22/IL-22 on blood pressure regulation, angiotensin II-infused mice were treated with recombinant mouse IL-22, an anti-IL-22 neutralizing monoclonal antibody, or control. Treatment with recombinant IL-22 resulted in increased blood pressure, amplified inflammatory responses, and aggravated endothelial dysfunction, whereas the anti-IL-22 neutralizing monoclonal antibody decreased blood pressure, reduced inflammatory responses, and attenuated endothelial dysfunction. To determine whether the STAT3 (signal transducer and activator of transcription 3) pathway mediates the effect of IL-22 on blood pressure regulation, the special STAT3 pathway inhibitor S31-201 was administered to mice treated with recombinant IL-22. S31-201 treatment significantly ameliorated the IL-22 effects of increased blood pressure and endothelial dysfunction. In addition, serum IL-22 levels were significantly increased in hypertensive patients compared with healthy persons. Correlation analysis showed a positive correlation between IL-22 levels and blood pressure.

CONCLUSIONS

IL-22 amplifies the inflammatory response, induces endothelial dysfunction and promotes blood pressure elevation in angiotensin II-induced hypertensive mice. The STAT3 pathway mediates the effect of IL-22 on hypertension. Blocking IL-22 may be a novel therapeutic strategy to prevent and treat hypertension.

Right Cervical Vagotomy Aggravates Viral Myocarditis in Mice Via the Cholinergic Anti-inflammatory Pathway

The autonomic nervous system dysfunction with increased sympathetic activity and withdrawal of vagal activity may play an important role in the pathogenesis of viral myocarditis. The vagus nerve can modulate the immune response and control inflammation through a ‘cholinergic anti-inflammatory pathway’ dependent on the α7-nicotinic acetylcholine receptor (α7nAChR). Although the role of β-adrenergic stimulation on viral myocarditis has been investigated in our pervious studies, the direct effect of vagal tone in this setting has not been yet studied. Therefore, in the present study, we investigated the effects of cervical vagotomy in a murine model of viral myocarditis. In a coxsackievirus B3 murine myocarditis model (Balb/c), effects of right cervical vagotomy and nAChR agonist nicotine on echocardiography, myocardial histopathology, viral RNA, and proinflammatory cytokine levels were studied. We found that right cervical vagotomy inhibited the cholinergic anti-inflammatory pathway, aggravated myocardial lesions, up-regulated the expression of TNF-α, IL-1β, and IL-6, and worsened the impaired left ventricular function in murine viral myocarditis, and these changes were reversed by co-treatment with nicotine by activating the cholinergic anti-inflammatory pathway. These results indicate that vagal nerve plays an important role in mediating the anti-inflammatory effect in viral myocarditis, and that cholinergic stimulation with nicotine also plays its peripheral anti-inflammatory role relying on α7nAChR, without requirement for the integrity of vagal nerve in the model. The findings suggest that vagus nerve stimulation mediated inhibition of the inflammatory processes likely provide important benefits in myocarditis treatment.

Elevated plasma levels of Th17-related cytokines are associated with increased risk of atrial fibrillation

We performed a matched case-control study using a propensity score matching, to assess the association of Th17-related cytokines, including interleukin (IL) 17A (IL-17A), IL-17F, IL-21, IL-22 and IL-6, along with interferon-γ (IFN-γ), IL-10, IL-9, and IL-4, with the risk of AF. A total of 336 patients with AF were matched 1:1 with patients without AF. Plasma levels of cytokines were measured using Luminex xMAP assays. The plasma levels of all examined cytokines were significantly higher in AF patients than controls (P < 0.05), and these cytokines were highly correlated with each other (P < 0.01). A multivariate conditional logistic regression analysis showed that elevated plasma levels of IL-17A, IL-17F, IL-21, IL-22, IFN-γ, IL-10, IL-9 and IL-6 were significantly associated with AF risk independently of potential confounders. There were no significant differences in plasma levels of examined cytokines between paroxysmal and chronic AF patients. IL-17A, IL-21, IL-10 and IL-6 levels were positively correlated with left atrial diameter; IL-17F level was negatively correlated with left ventricle ejection fraction among AF patients (P < 0.05). Elevated plasma levels of Th17-related cytokines were independently associated with increased an risk of AF; hence, Th17-related cytokines may be involved in the pathogenesis of AF.

Interleukin-27 ameliorates coxsackievirus-B3-induced viral myocarditis by inhibiting Th17 cells

Background

Interleukin (IL)-27, which has both pro and anti- inflammatory properties, is a new discovered heterodimeric cytokine that belongs to IL-12 family. However, the expression pattern and functional role of IL-27 in viral myocarditis (VMC) has not been investigated.

Methods

BALB/c mice were intraperitoneally (i.p) infected with Coxsackie virus B3 (CVB3) for establishing VMC models. Mice were then injected i.p. with Anti-Mouse IL-27 p28Ab or recombinant IL-27 for neutralization and overexpression of IL-27. The survival rates of mice were recorded and the kinetics of IL-27 expression, the frequencies of Th17 cells and the expression of inflammatory cytokine in CVB3-infected mice were determined by ELISA, real-time PCR and flow cytometry.

Results

The IL-27 expression in heart tissues and serum in coxsackievirus B3 (CVB3)-induced myocarditis mice peaked on day 4 but then rapidly decreased during the late infectious stage of CVB3, high IL-27 levels were negatively correlated with bodyweight loss (r = −0.71, P = 0.021) and myocardial pathological score (r = −0.85, P = 0.0018). Additionally, neutralization of IL-27 with Anti-IL-27 Ab accelerated, whereas systemic administration of recombinant mouse IL-27 ameliorated CVB3-induced myocarditis. The protective role of IL-27 in VMC was reflected by an improved survival rate, increased bodyweights, and reduced pathological scores in Anti-IL-27 group compared with IgG control group. Mechanistic investigations showed that IL-27 inhibited Th17 cells frequencies and IL-17 production, as well as the Th17-related proinflammatory cytokines in heart tissues.

Conclusions

Our results demonstrate that that IL-27 effectively protects the myocardium from the pathogenesis of CVB3 induced myocarditis, which may be attributable to reduced Th17 production. IL-27 might serve as a novel therapeutic treatment for VMC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-015-0418-x) contains supplementary material, which is available to authorized users.

Panax Notoginseng Saponins Ameliorates Coxsackievirus B3-Induced Myocarditis by Activating the Cystathionine-γ-Lyase/Hydrogen Sulfide Pathway

This study is to determine the therapeutic effects of Panax notoginseng saponins (PNSs) on coxsackievirus B3 (CVB3)-induced myocarditis, and whether cystathionine-γ-lyase (CSE)/hydrogen sulfide (H2S) pathway is involved. Mouse model of myocarditis was induced by CVB3 infection, and the mice were subjected to vehicle (saline) or drug treatments (sodium bisulfide (NaHS), propargylglycine (PAG), or PNSs). The results showed that there were inflammatory cell infiltrations, interstitial edemas, and elevated inflammatory cytokines, in CVB3-induced myocarditis. PAG administration increased, whereas NaHS treatment decreased the severity of the myocarditis. PNS treatment dramatically alleviated these myocardial injuries and decreased the viral messenger RNA (mRNA) expression by the enhanced expression of CSE/H2S pathway. Moreover, the therapeutic effects of PNSs on myocarditis were stronger than those of NaHS. Finally, the effect of PNSs on CSE/H2S pathway and cardiac cell protection were verified in cultured cardiac cells. PNSs may be a promising medication for viral myocarditis therapy.

Interleukin-22: immunobiology and pathology

Interleukin-22 (IL-22) is a recently described IL-10 family cytokine that is produced by T helper (Th) 17 cells, γδ T cells, NKT cells, and newly described innate lymphoid cells (ILCs). Knowledge of IL-22 biology has evolved rapidly since its discovery in 2000, and a role for IL-22 has been identified in numerous tissues, including the intestines, lung, liver, kidney, thymus, pancreas, and skin. IL-22 primarily targets nonhematopoietic epithelial and stromal cells, where it can promote proliferation and play a role in tissue regeneration. In addition, IL-22 regulates host defense at barrier surfaces. However, IL-22 has also been linked to several conditions involving inflammatory tissue pathology. In this review, we assess the current understanding of this cytokine, including its physiologic and pathologic effects on epithelial cell function.

Natural killer cells limit cardiac inflammation and fibrosis by halting eosinophil infiltration

Myocarditis is a leading cause of sudden cardiac failure in young adults. Natural killer (NK) cells, a subset of the innate lymphoid cell compartment, are protective in viral myocarditis. Herein, we demonstrated that these protective qualities extend to suppressing autoimmune inflammation. Experimental autoimmune myocarditis (EAM) was initiated in BALB/c mice by immunization with myocarditogenic peptide. During EAM, activated cardiac NK cells secreted interferon γ, perforin, and granzyme B, and expressed CD69, tumor necrosis factor-related apoptosis-inducing ligand treatment, and CD27 on their cell surfaces. The depletion of NK cells during EAM with anti-asialo GM1 antibody significantly increased myocarditis severity, and was accompanied by elevated fibrosis and a 10-fold increase in the percentage of cardiac-infiltrating eosinophils. The resultant influx of eosinophils to the heart was directly responsible for the increased disease severity in the absence of NK cells, because treatment with polyclonal antibody asialogangloside GM-1 did not augment myocarditis severity in eosinophil-deficient ΔdoubleGATA1 mice. We demonstrate that NK cells limit eosinophilic infiltration both indirectly, through altering eosinophil-related chemokine production by cardiac fibroblasts, and directly, by inducing eosinophil apoptosis in vitro. Altogether, we define a new pathway of eosinophilic regulation through interactions with NK cells.

IL-22-producing Th22 cells play a protective role in CVB3-induced chronic myocarditis and dilated cardiomyopathy by inhibiting myocardial fibrosis

BACKGROUND

A new subset of T helper (Th) cells, named IL-22-producing Th22 cells, was identified recently. Th22 cells have been implicated in immunity and inflammation. However, the role of these cells in the progression from acute viral myocarditis (AVMC) to dilated cardiomyopathy (DCM) and myocardial fibrosis remains unknown.

METHODS

BALB/c mice were repeatedly i.p. infected with Coxsackie virus B3 (CVB3) to establish models of AVMC, chronic myocarditis and DCM. On week 2, 12 and 24 post initial injection, the percentage of splenic Th22 cells, the levels of plasma IL-22, cardiac IL-22 receptor (IL-22R) expression, and indicators of myocardial fibrosis were measured. Further, mice with AVMC and chronic myocarditis were treated with an anti-IL-22 neutralizing antibody (Ab). The collagen volume fraction (CVF), the percentage of splenic Th22 cells, plasma IL-22 levels, cardiac IL-22R expression and indicators of myocardial fibrosis were then monitored.

RESULTS

Compared to control mice at the same time points, AVMC, chronic myocarditis and DCM mice have higher percentage of splenic Th22 cells, higher plasma IL-22 levels, increased cardiac IL-22R, as well as increased collagen typeI-A1 (COL1-A1), collagen type III-A1 (COL3-A1) and matrix metalloproteinase-9 (MMP9) expression. However, the expression of tissue inhibitor of metalloproteinase-1(TIMP-1) was decreased. Treatment of AVMC and chronic myocarditis mice with an anti-IL-22 Ab decreased the survival rate and exacerbated myocardial fibrosis. The percentage of splenic Th22 cells, plasma IL-22 levels and cardiac IL-22R expression also decreased in anti-IL-22 Ab treatment group as compared to IgG and PBS treated groups of AVMC and chronic myocarditis mice. Moreover, increased expression of COL1-A1, COL3-A1, MMP9 but decreased expression of TIMP-1 were observed in anti-IL-22 Ab mouse group.

CONCLUSIONS

Th22 cells play an important role in the pathogenesis of CVB3-induced mouse chronic myocarditis and DCM. IL-22 is a myocardium-protective cytokine by inhibiting myocardial fibrosis. Therefore, Th 22 cells may be considered as potential therapeutic targets for DCM.

Intricacies of cardiac damage in coxsackievirus B3 infection: implications for therapy

Heart disease is the leading cause of death in humans, and myocarditis is one predominant cause of heart failure in young adults. Patients affected with myocarditis can develop dilated cardiomyopathy (DCM), a common reason for heart transplantation, which to date is the only viable option for combatting DCM. Myocarditis/DCM patients show antibodies to coxsackievirus B (CVB)3 and cardiac antigens, suggesting a role for CVB-mediated autoimmunity in the disease pathogenesis; however, a direct causal link remains to be determined clinically. Experimentally, myocarditis can be induced in susceptible strains of mice using the human isolates of CVB3, and the disease pathogenesis of postinfectious myocarditis resembles that of human disease, making the observations made in animals relevant to humans. In this review, we discuss the complex nature of CVB3-induced myocarditis as it relates to the damage caused by both the virus and the host's response to infection. Based on recent data we obtained in the mouse model of CVB3 infection, we provide evidence to suggest that CVB3 infection accompanies the generation of cardiac myosin-specific CD4 T cells that can transfer the disease to naïve recipients. The therapeutic implications of these observations are also discussed.