Th17 cells contribute to viral replication in coxsackievirus B3-induced acute viral myocarditis

Qiliqiangxin Alleviates Imbalance of Inflammatory Cytokines in Patients with Dilated Cardiomyopathy: A Randomized Controlled Trial

OBJECTIVE

Qiliqiangxin (QLQX) capsule- a traditional Chinese medicine used for treating heart failure (HF), can modulate inflammatory cytokines in rats with myocardial infarction. However, its immune-regulating effect on dilated cardiomyopathy (DCM) remains unknown. The aim of this study was to investigate whether QLQX has a unique regulatory role in the imbalance of pro- and anti-inflammatory cytokines in patients with DCM.

METHODS

The QLQX-DCM is a randomized- double-blind trial conducted at 24 tertiary hospitals in China. A total of 345 patients with newly diagnosed virus-induced DCM were randomly assigned to receive QLQX capsules or placebo while receiving optimal medical therapy for HF. The primary endpoints were changes in plasma inflammatory cytokines and improvements in left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDd) over the 12-month treatment.

RESULTS

At the 12-month follow-up, the levels of IFN-γ, IL-17, TNF-α, and IL-4 decreased significantly, while the level of IL-10 increased in both groups compared with baselines (all P<0.0001). Furthermore-these changes, coupled with improvements in LVEF, NT-proBNP and New York Heart Association (NYHA) functional classification, excluding the LVEDd in the QLQX group, were greater than those in the placebo group (all P<0.001). Additionally, compared with placebo, QLQX treatment also reduced all-cause mortality and rehospitalization rates by 2.17% and 2.28%, respectively, but the difference was not statistically significant.

CONCLUSION

QLQX has the potential to alleviate the imbalance of inflammatory cytokines in patients with DCM, potentially leading to further improvements in cardiac function when combined with anti-HF standard medications.

Puerarin inhibits macrophage M1 polarization by combining STAT1 to reduce myocardial damage in EAM model mice

Myocarditis is an inflammatory lesion of the myocardium that is caused by a variety of factors. At present, treatment of symptoms remains the main clinical intervention, but it cannot reduce the myocarditis damage caused by inflammation. M1 macrophages are thought to contribute significantly to the occurrence and development of inflammation by secreting a large number of proinflammatory factors. Puerarin is an isoflavone derivative isolated from pueraria that can be used as a dietary supplement and exerts wide range of anti-inflammatory and antioxidant effects. However, the mechanism underlying its anti-inflammatory effects needs to be further studied. The objective of this study was to investigate whether puerarin inhibited M1 polarization by affecting the JAK-STAT signaling pathway in a mouse model of autoimmune myocarditis, thus inhibiting the occurrence of inflammation in experimental autoimmune myocarditis (EAM) model mice. The results showed that EAM model mice treated with puerarin showed milder clinical symptoms and inflammatory infiltration than EAM model mice. Puerarin suppressed the in vivo and in vitro JAK1/2-STAT1 signal transduction in macrophages, thus inhibiting M1 polarization, reducing the secretion of proinflammatory factors, and ultimately decreasing IFN-γ and TNF-α levels in vivo, which led to myocardial apoptosis. Thus, puerarin could alleviate myocardial damage caused by inflammation. The conclusion of this study was that puerarin reduced myocardial damage in EAM model mice by regulating the polarization of macrophages toward M1, and this inhibitory effect may be achieved by inhibiting JAK1/2-STAT1 signaling.

Interleukin-6 classic and trans-signaling utilize glucose metabolism reprogramming to achieve anti- or pro-inflammatory effects

Interleukin (IL)-6 has anti- and pro-inflammatory functions, controlled by IL-6 classic and trans-signaling, respectively. Differences in the downstream signaling mechanism between IL-6 classic and trans-signaling have not been identified. Here, we report that IL-6 activates glycolysis to regulate the inflammatory response. IL-6 regulates glucose metabolism by forming a complex containing signal-transducing activators of transcription 3 (STAT3), hexokinase 2 (HK2), and voltage-dependent anion channel 1 (VDAC1). The IL-6 classic signaling directs glucose flux to oxidative phosphorylation (OxPhos), while IL-6 trans-signaling directs glucose flux to anaerobic glycolysis. Classic IL-6 signaling promotes STAT3 translocation into mitochondria to interact with pyruvate dehydrogenase kinase-1 (PDK1), leading to pyruvate dehydrogenase α (PDHA) dissociation from PDK1. As a result, PDHA is dephosphorylated, and STAT3 is phosphorylated at Ser727. By contrast, IL-6 trans-signaling promotes the interaction of sirtuin 2 (SIRT2) and lactate dehydrogenase A (LDHA), leading to the dissociation of STAT3 from SIRT2. As a result, LDHA is deacetylated, and STAT3 is acetylated and phosphorylated at Tyr705. IL-6 classic signaling promotes the differentiation of regulatory T cells via the PDK1/STAT3/PDHA axis, whereas IL-6 trans-signaling promotes the differentiation of Th17 cells via the SIRT2/STAT3/LDHA axis. Conclusion: IL-6 classic signaling generates anti-inflammatory functions by shifting energy metabolism to OxPhos, while IL-6 trans-signaling generates pro-inflammatory functions by shifting energy metabolism to anaerobic glycolysis.

Immune mechanisms of group B coxsackievirus induced viral myocarditis

Viral myocarditis is known to be a primary cause of dilated cardiomyopathy (DCM) that can lead to heart failure and sudden cardiac death and is invariably caused by myocardial viral infection following active inflammatory destruction of the myocardium. Although acute viral myocarditis frequently recovers on its own, current chronic myocarditis therapies are unsatisfactory, where the persistence of viral or immunological insults to the heart may play a role. Cellular and mouse experimental models that utilized the most prevalent Coxsackievirus group B type 3 (CVB3) virus infection causing myocarditis have illustrated the pathophysiology of viral myocarditis. In this review, immunological insights into the different stages of development of viral myocarditis were discussed, concentrating on the mechanisms of innate and adaptive immunity in the development of CVB3-induced myocarditis.

Controlling viral inflammatory lesions by rebalancing immune response patterns

In this review, we discuss a variety of immune modulating approaches that could be used to counteract tissue-damaging viral immunoinflammatory lesions which typify many chronic viral infections. We make the point that in several viral infections the lesions can be largely the result of one or more aspects of the host response mediating the cell and tissue damage rather than the virus itself being directly responsible. However, within the reactive inflammatory lesions along with the pro-inflammatory participants there are also other aspects of the host response that may be acting to constrain the activity of the damaging components and are contributing to resolution. This scenario should provide the prospect of rebalancing the contributions of different host responses and hence diminish or even fully control the virus-induced lesions. We identify several aspects of the host reactions that influence the pattern of immune responsiveness and describe approaches that have been used successfully, mainly in model systems, to modulate the activity of damaging participants and which has led to lesion control. We emphasize examples where such therapies are, or could be, translated for practical use in the clinic to control inflammatory lesions caused by viral infections.

A new method for the treatment of myocardial ischemia-reperfusion injury based on γδT cell-mediated immune response

Acute myocardial ischemia is a disease with high morbidity and mortality, and re-perfusion is currently the best intervention. However, re-perfusion may lead to further myocardial injury and increase the area of myocardial infarction. The mechanism of myocardial ischemia-re-perfusion injury is complex, but with more in-depth study, it has been proved that the immune system plays an important role in the process of MIRI. Among them, the γδT cell population has received increasing attention as the main early source of IL-17A in many immune response models. Because γδT cells have the characteristics of linking innate immunity and adaptive immunity,they can rapidly produce IL-17A and produce subsequent immune killing of cardiomyocytes. It can be seen that γδT cells play an important role in MIRI. Therefore, here we review the research progress of immune response in myocardial ischemia-re-perfusion injury, the key characteristics of γδT cells and the role of rapidly produced IL-17 in myocardial ischemia-re-perfusion injury, and propose relevant treatment strategies and prospects for myocardial repair, in order to provide new ideas and methods for clinical treatment of myocardial ischemia-re-perfusion injury.

Effect of Pre-Treatment with a Recombinant Chicken Interleukin-17A on Vaccine Induced Immunity against a Very Virulent Marek's Disease Virus

The host response to pathogenic microbes can lead to expression of interleukin (IL)-17, which has antimicrobial and anti-viral activity. However, relatively little is known about the basic biological role of chicken IL-17A against avian viruses, particularly against Marek's disease virus (MDV). We demonstrate that, following MDV infection, upregulation of IL-17A mRNA and an increase in the frequency of IL-17A+ T cells in the spleen occur compared to control chickens. To elaborate on the role of chIL-17A in MD, the full-length chIL-17A coding sequence was cloned into a pCDNA3.1-V5/HIS TOPO plasmid. The effect of treatment with pcDNA:chIL-17A plasmid in combination with a vaccine (HVT) and very virulent(vv)MDV challenge or vvMDV infection was assessed. In combination with HVT vaccination, chickens that were inoculated with the pcDNA:chIL-17A plasmid had reduced tumor incidence compared to chickens that received the empty vector control or that were vaccinated only (66.6% in the HVT + empty vector group and 73.33% in HVT group versus 53.3% in the HVT + pcDNA:chIL-17A). Further analysis demonstrated that the chickens that received the HVT vaccine and/or plasmid expressing IL-17A had lower MDV-Meq transcripts in the spleen. In conclusion, chIL-17A can influence the immunity conferred by HVT vaccination against MDV infection in chickens.

Inhibitor of CD147 Suppresses T Cell Activation and Recruitment in CVB3-Induced Acute Viral Myocarditis

Viral myocarditis (VMC) is a common disease characterized by cardiac inflammation. AC-73, an inhibitor of CD147, disrupts the dimerization of CD147, which participates in the regulation of inflammation. To explore whether AC-73 could alleviate cardiac inflammation induced by CVB3, mice were injected intraperitoneally with AC-73 on the fourth day post-infection (dpi) and sacrificed on the seventh dpi. Pathological changes in the myocardium, T cell activation or differentiation, and expression of cytokines were analyzed using H&E staining, flow cytometry, fluorescence staining and multiplex immunoassay. The results showed that AC-73 alleviated cardiac pathological injury and downregulated the percentage of CD45⁺CD3⁺ T cells in the CVB3-infected mice. The administration of AC-73 reduced the percentage of activated CD4⁺ and CD8⁺ T cells (CD69⁺ and/or CD38⁺) in the spleen, while the percentage of CD4⁺ T cell subsets in the spleen was not changed in the CVB3-infected mice. In addition, the infiltration of activated T cells (CD69⁺) and macrophages (F4/80⁺) in the myocardium also decreased after the AC-73 treatment. The results also showed that AC-73 inhibited the release of many cytokines and chemokines in the plasma of the CVB3-infected mice. In conclusion, AC-73 mitigated CVB3-induced myocarditis by inhibiting the activation of T cells and the recruitment of immune cells to the heart. Thus, CD147 may be a therapeutic target for virus-induced cardiac inflammation.

Leveraging Exosomes as the Next-Generation Bio-Shuttles: The Next Biggest Approach against Th17 Cell Catastrophe

In recent years, the launch of clinical-grade exosomes is rising expeditiously, as they represent a new powerful approach for the delivery of advanced therapies and for diagnostic purposes for various diseases. Exosomes are membrane-bound extracellular vesicles that can act as biological messengers between cells, in the context of health and disease. In comparison to several lab-based drug carriers, exosome exhibits high stability, accommodates diverse cargo loads, elicits low immunogenicity and toxicity, and therefore manifests tremendous perspectives in the development of therapeutics. The efforts made to spur exosomes in drugging the untreatable targets are encouraging. Currently, T helper (Th) 17 cells are considered the most prominent factor in the establishment of autoimmunity and several genetic disorders. Current reports have indicated the importance of targeting the development of Th17 cells and the secretion of its paracrine molecule, interleukin (IL)-17. However, the present-day targeted approaches exhibit drawbacks, such as high cost of production, rapid transformation, poor bioavailability, and importantly, causing opportunistic infections that ultimately hamper their clinical applications. To overcome this hurdle, the potential use of exosomes as vectors seem to be a promising approach for Th17 cell-targeted therapies. With this standpoint, this review discusses this new concept by providing a snapshot of exosome biogenesis, summarizes the current clinical trials of exosomes in several diseases, analyzes the prospect of exosomes as an established drug carrier and delineates the present challenges, with an emphasis on their practical applications in targeting Th17 cells in diseases. We further decode the possible future scope of exosome bioengineering for targeted drug delivery against Th17 cells and its catastrophe.

The Heart–Brain Interplay in Multiple Sclerosis from Pathophysiology to Clinical Practice: A Narrative Review

Multiple sclerosis (MS) is a chronic neurological disorder characterized by inflammation in the central nervous system (CNS) that leads to neurodegeneration. The clinical course is highly variable, but its prevalence is rising worldwide, partly thanks to novel disease-modifying therapies. Additionally, the lifespan of people with MS is increasing, and for this reason, it is fundamental to have a multidisciplinary approach to MS. MS may be associated with cardiovascular diseases (CVD), but there is scarce attention on this issue. In particular, CNS is essential in regulating the autonomic system and heart activity. Moreover, cardiovascular risk factors show a higher prevalence in MS patients. On the other hand, conditions like Takotsubo syndrome are rare complications of MS. The parallelism between MS and myocarditis is also interesting. Finally, cardiac toxicity represents a not infrequent adverse reaction to MS drugs. This narrative review aims to provide an overview of cardiovascular complications in MS and their management to prompt further clinical and pre-clinical research on this topic.

The role of IL17 and IL17RA polymorphisms in lethal pandemic acute viral pneumonia (Influenza A virus H1N1 subtype)

Background

The cytokines play an essential role in acute inflammatory processes, and the IL-17 may be responsible for ambiguous aspects, and the correlation with genetic polymorphisms could improve the search for this critical biomarker. Thus, this study aimed to evaluate the IL-17A and IL-17RA tissue expression and the polymorphisms that codified these proteins in a population that died of pandemic Influenza A virus H1N1 subtype compared to a non-pandemic Influenza virus population.

Methods

Necropsy lung samples immunohistochemistry was performed to assess the presence of IL-17A and IL-17RA in the pulmonary tissue. Eight single nucleotide polymorphisms were genotyped using TaqMan® technology.

Results

The Influenza A H1N1 pandemic group had higher tissue expression of IL-17A, higher neutrophil recruitment and shorter survival time between admission and death. Three single nucleotide polymorphisms conferred risk for pandemic influenza A H1N1, the AA genotype of rs3819025 G/A, the CC genotype of rs2241044 A/C, and the TT genotype of rs 2,241,043 C/T.

Conclusions

One IL17A polymorphism (rs381905) and two IL17RA polymorphisms (rs2241044 and rs2241043) represented biomarkers of worse prognosis in the population infected with pandemic influenza A H1N1. The greater tissue expression of IL-17A shows a Th17 polarization and highlights the aggressiveness of the pandemic influenza virus with its duality in the protection and pathogenesis of the pulmonary infectious process.

IL-17 and IL-17-producing cells in protection versus pathology

IL-17 cytokine family members have diverse biological functions, promoting protective immunity against many pathogens but also driving inflammatory pathology during infection and autoimmunity. IL-17A and IL-17F are produced by CD4⁺ and CD8⁺ T cells, γδ T cells, and various innate immune cell populations in response to IL-1β and IL-23, and they mediate protective immunity against fungi and bacteria by promoting neutrophil recruitment, antimicrobial peptide production and enhanced barrier function. IL-17-driven inflammation is normally controlled by regulatory T cells and the anti-inflammatory cytokines IL-10, TGFβ and IL-35. However, if dysregulated, IL-17 responses can promote immunopathology in the context of infection or autoimmunity. Moreover, IL-17 has been implicated in the pathogenesis of many other disorders with an inflammatory basis, including cardiovascular and neurological diseases. Consequently, the IL-17 pathway is now a key drug target in many autoimmune and chronic inflammatory disorders; therapeutic monoclonal antibodies targeting IL-17A, both IL-17A and IL-17F, the IL-17 receptor, or IL-23 are highly effective in some of these diseases. However, new approaches are needed to specifically regulate IL-17-mediated immunopathology in chronic inflammation and autoimmunity without compromising protective immunity to infection.

The Double Game Played by Th17 Cells in Infection: Host Defense and Immunopathology

T-helper 17 (Th17) cells represent a subpopulation of CD4+ T lymphocytes that play an essential role in defense against pathogens. Th17 cells are distinguished from Th1 and Th2 cells by their ability to produce members of the interleukin-17 (IL-17) family, namely IL-17A and IL-17F. IL-17 in turn induces several target cells to synthesize and release cytokines, chemokines, and metalloproteinases, thereby amplifying the inflammatory cascade. Th17 cells reside predominantly in the lamina propria of the mucosa. Their main physiological function is to maintain the integrity of the mucosal barrier against the aggression of infectious agents. However, in an appropriate inflammatory microenvironment, Th17 cells can transform into immunopathogenic cells, giving rise to inflammatory and autoimmune diseases. This review aims to analyze the complex mechanisms through which the interaction between Th17 and pathogens can be on the one hand favorable to the host by protecting it from infectious agents, and on the other hand harmful, potentially generating autoimmune reactions and tissue damage.

SGLT2 inhibitor, canagliflozin, ameliorates cardiac inflammation in experimental autoimmune myocarditis

Myocarditis is an inflammatory cardiovascular disease which contributes to dilated cardiomyopathy (DCM) and heart failure. Canagliflozin (CANA) exerts anti-inflammatory and cardioprotective effects in heart failure besides its hypoglycemic effect. However, the role of CANA in myocarditis has not been elucidated. In this work, CANA treatment markedly alleviated cardiac inflammation and improved cardiac function in experimental autoimmune myocarditis (EAM) mice induced by α-myosin-heavy chain peptides. The expressions of NLRP3 inflammasome complexes (NLRP3, ASC, and Caspase-1) and their downstream molecules (IL-1β, IL-18) were significantly downregulated by CANA, accompanied with reduced Th17 cell infiltration in hearts. Furthermore, Bax/Bcl-2 ratio, Cleaved Caspase-3 protein level and the percentage of TUNEL-positive myocardial cells, which usually indicated apoptosis, were reduced by CANA treatment. These findings suggest CANA could be a valuable medication for myocarditis treatment.

The therapeutic potential of regulatory T cells in reducing cardiovascular complications in patients with severe COVID-19

The SARS coronavirus 2 (SARS CoV-2) causes Coronavirus Disease (COVID-19), is an emerging viral infection. SARS CoV-2 infects target cells by attaching to Angiotensin-Converting Enzyme (ACE2). SARS CoV-2 could cause cardiac damage in patients with severe COVID-19, as ACE2 is expressed in cardiac cells, including cardiomyocytes, pericytes, and fibroblasts, and coronavirus could directly infect these cells. Cardiovascular disorders are the most frequent comorbidity found in COVID-19 patients. Immune cells such as monocytes, macrophages, and T cells may produce inflammatory cytokines and chemokines that contribute to COVID-19 pathogenesis if their functions are uncontrolled. This causes a cytokine storm in COVID-19 patients, which has been associated with cardiac damage. Tregs are a subset of immune cells that regulate immune and inflammatory responses. Tregs suppress inflammation and improve cardiovascular function through a variety of mechanisms. This is an exciting research area to explore the cellular, molecular, and immunological mechanisms related to reducing risks of cardiovascular complications in severe COVID-19. This review evaluated whether Tregs can affect COVID-19-related cardiovascular complications, as well as the mechanisms through which Tregs act.

Correlation of serum interleukin 17 and macrophage migration inhibitory factor levels with clinical response to intralesional Candida antigen and their potential use as predictors of clinical outcome in patients with multiple common warts

BACKGROUND

Candida antigen injection is one of the most widely used intralesional immunotherapy in the treatment of warts. It acts through the induction of systemic immune response. The pattern of cytokines production may play an integral role in its mechanism of action.

AIM

To investigate the possible relation between serum levels of IL17 and MIF, and the clinical response to intralesional Candida antigen in multiple common warts.

METHODS

A total of 90 patients with multiple common warts were divided into 2 groups. Sixty patients received intralesional Candida antigen injection into the largest wart, controlled against thirty patients who had intralesional saline, as placebo. The injection was done at a 2-week interval for 5 doses. Blood samples were obtained from both groups, and serum levels of IL17A and MIF were estimated at baseline and 2 weeks after the last session using ELISA kits.

RESULTS

Complete clearance of warts was statistically higher in the Candida antigen group (40% of the patients) compared to the saline group (p < 0.05). The serum levels of IL17 had significantly declined from baseline, while the level of MIF had risen after intralesional Candida antigen injection, but not in the saline group. At a cutoff level of 316 pg/ml, IL17 had a sensitivity of 83.3% to predict therapeutic response.

CONCLUSION

IL17A and MIF may have possible roles in the mechanism of action of Candida antigen in the treatment of common warts. At a certain level, serum IL17A may be a potential predictor of response to treatment.

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.

Neutralization of interleukin-38 exacerbates coxsackievirus B3-induced acute myocarditis in mice

Background

Interleukin (IL)-38, a novel member of the IL-1 family, has been reported to be involved in several diseases associated with viral infection. However, the expression and functional role of IL-38 in acute viral myocarditis (AVMC) have not been investigated.

Methods

Male BALB/c mice were treated with intraperitoneal (i.p.) injection of coxsackievirus B3 (CVB3) for establishing AVMC models. On day 7 post-injection, the expression of IL-38 and IL-36R (IL-36 receptor) were measured. Mice were then treated with i.p. injection of mouse Anti-IL-38 Antibodies (Abs) for neutralization of IL-38. The survival, bodyweight loss, cardiac function, and myocarditis severity of mice were recorded. The percentages of splenic Th1 and Th17 cells, the expression levels of Th1/Th17-related master transcription factors (T-bet and RORγt) and cytokines were determined by flow cytometry, RT-qPCR, and ELISA, respectively. Cardiac viral replication was further detected.

Results

The mRNA and protein expression levels of IL-38 in myocardium and serum, as well as cardiac IL-36R mRNA levels were significantly elevated in mice with AVMC. Increased IL-38 levels were negatively correlated with the severity of AVMC. Neutralization of IL-38 exacerbated CVB3-induced AVMC, as verified by the lower survival rate, impaired cardiac function, continuous bodyweight loss, and higher values of HW/BW and cardiac pathological scores. In addition, neutralization of IL-38 suppressed Th1 cells differentiation while promoted Th17 cells differentiation, accompanied by decreased T-bet mRNA expression and increased RORγt expression. Down-regulation of IFN-γ and up-regulation of IL-17, TNF-α, and IL-6 mRNA and protein expression levels in myocardium and serum were also observed in the IL-38 neutralization group. Furthermore, neutralization of IL-38 markedly promoted cardiac viral replication.

Conclusions

Neutralization of IL-38 exacerbates CVB3-induced AVMC in mice, which may be attributable to the imbalance of Th1/Th17 cells and increased CVB3 replication. Thus, IL-38 can be considered as a potential therapeutic target for AVMC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01687-w.

Sacubitril/Valsartan Alleviates Experimental Autoimmune Myocarditis by Inhibiting Th17 Cell Differentiation Independently of the NLRP3 Inflammasome Pathway

Sacubitril/valsartan (Sac/Val) is a recently approved drug that is commonly used for treatment of heart failure. Several studies indicated that Sac/Val also regulated the secretion of inflammatory factors. However, the effect and mechanism of this drug modulation of inflammatory immune responses are uncertain. In this study, an experimental autoimmune myocarditis (EAM) mouse model was established by injection of α-myosin-heavy chain peptides. The effect of oral Sac/Val on EAM was evaluated by histological staining of heart tissues, measurements of cardiac troponin T and inflammatory markers (IL-6 and hsCRP). The effects of Sac/Val on NLRP3 inflammasome activation and Th1/Th17 cell differentiation were also determined. To further explore the signaling pathways, the expressions of cardiac soluble guanylyl cyclase (sGC) and NF-κB p65 were investigated. The results showed that Sac/Val downregulated the inflammatory response and attenuated the severity of EAM, but did not influence NLRP3 inflammasomes activation. Moreover, Sac/Val treatment inhibited cardiac Th17 cell differentiation, and this might be associated with sGC/NF-κB p65 signaling pathway. These findings indicate the potential use of Sac/Val for treatment of myocarditis.

Viruses in the Heart: Direct and Indirect Routes to Myocarditis and Heart Failure

Viruses are an underappreciated cause of heart failure. Indeed, several types of viral infections carry cardiovascular risks. Understanding shared and unique mechanisms by which each virus compromises heart function is critical to inform on therapeutic interventions. This review describes how the key viruses known to lead to cardiac dysfunction operate. Both direct host-damaging mechanisms and indirect actions on the immune systems are discussed. As viral myocarditis is a key pathologic driver of heart failure in infected individuals, this review also highlights the role of cytokine storms and inflammation in virus-induced cardiomyopathy.

Myocardial Damage by SARS-CoV-2: Emerging Mechanisms and Therapies

Evidence is emerging that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect various organs of the body, including cardiomyocytes and cardiac endothelial cells in the heart. This review focuses on the effects of SARS-CoV-2 in the heart after direct infection that can lead to myocarditis and an outline of potential treatment options. The main points are: (1) Viral entry: SARS-CoV-2 uses specific receptors and proteases for docking and priming in cardiac cells. Thus, different receptors or protease inhibitors might be effective in SARS-CoV-2-infected cardiac cells. (2) Viral replication: SARS-CoV-2 uses RNA-dependent RNA polymerase for replication. Drugs acting against ssRNA(+) viral replication for cardiac cells can be effective. (3) Autophagy and double-membrane vesicles: SARS-CoV-2 manipulates autophagy to inhibit viral clearance and promote SARS-CoV-2 replication by creating double-membrane vesicles as replication sites. (4) Immune response: Host immune response is manipulated to evade host cell attacks against SARS-CoV-2 and increased inflammation by dysregulating immune cells. Efficiency of immunosuppressive therapy must be elucidated. (5) Programmed cell death: SARS-CoV-2 inhibits programmed cell death in early stages and induces apoptosis, necroptosis, and pyroptosis in later stages. (6) Energy metabolism: SARS-CoV-2 infection leads to disturbed energy metabolism that in turn leads to a decrease in ATP production and ROS production. (7) Viroporins: SARS-CoV-2 creates viroporins that lead to an imbalance of ion homeostasis. This causes apoptosis, altered action potential, and arrhythmia.

Interference with the expression of S1PR1 or STAT3 attenuates valvular damage due to rheumatic heart disease

Rheumatic heart disease (RHD) affects numerous individuals annually; however, its pathogenesis remains unclear. The sphingosine 1‑phosphate receptor 1 (S1PR1) and signal transducer and activator of transcription 3 (STAT3) have recently been shown to be involved in valvular damage via the promotion of the differentiation of T helper 17 (Th17) cells during the development of RHD‑induced valvular damage. The present study investigated whether altering the expression of S1PR1 or STAT3 attenuates valvular damage due to RHD. Inactivated group A streptococcus (GAS) was used to establish a rat model of RHD. Recombinant adeno‑associated viral vectors carrying an S1PR1 overexpression sequence were used to overexpress S1PR1. STAT3 small interfering RNA (STAT3‑siRNA) was used to inhibit STAT3 expression. Reverse transcription‑quantitative PCR (RT‑qPCR) was performed to detect the mRNA expression of S1PR1, STAT3, collagen type III α1 chain (Col3a1) and fibroblast‑specific protein 1. Western blotting (WB) and immunohistochemistry were used to detect the levels of S1PR1, STAT3, phosphorylated (p‑) STAT3, and retinoic acid‑related orphan receptor γT (RORγt) proteins. Enzyme‑linked immunosorbent assays (ELISAs) and immunohistochemistry were used to detect the levels of interleukin (IL)‑6 and IL‑17. Hematoxylin and eosin (H&E) staining and Sirius Red staining were performed to evaluate the degree of inflammation and fibrosis in the valvular tissues. S1PR1 expression was decreased in the valvular tissues of the rats with RHD. The levels of IL‑6, IL‑17 and p‑STAT3 in the rats with RHD were increased. The degree of valvular inflammation and fibrosis in the rats with RHD was also increased. The overexpression of S1PR1 and the inhibition of STAT3 reduced the total p‑STAT3 level, resulting in decreased levels of IL‑6, IL‑17 and RORγt, and a reduced degree of valvular inflammation and fibrosis. These results suggest that the expression of S1PR1 and STAT3 may be involved in valvular tissue damage due to RHD. Thus, strategies designed to interfere with the expression of S1PR1 or STAT3 may affect the expression of Th17 cell‑related cytokines and may thus attenuate valvular damage due to RHD.

Th17 Cells in Viral Infections-Friend or Foe?

Th17 cells are recognized as indispensable in inducing protective immunity against bacteria and fungi, as they promote the integrity of mucosal epithelial barriers. It is believed that Th17 cells also play a central role in the induction of autoimmune diseases. Recent advances have evaluated Th17 effector functions during viral infections, including their critical role in the production and induction of pro-inflammatory cytokines and in the recruitment and activation of other immune cells. Thus, Th17 is involved in the induction both of pathogenicity and immunoprotective mechanisms seen in the host's immune response against viruses. However, certain Th17 cells can also modulate immune responses, since they can secrete immunosuppressive factors, such as IL-10; these cells are called non-pathogenic Th17 cells. Here, we present a brief review of Th17 cells and highlight their involvement in some virus infections. We cover these notions by highlighting the role of Th17 cells in regulating the protective and pathogenic immune response in the context of viral infections. In addition, we will be describing myocarditis and multiple sclerosis as examples of immune diseases triggered by viral infections, in which we will discuss further the roles of Th17 cells in the induction of tissue damage.

Immunomodulatory Effects of Rhinovirus and Enterovirus Infections During the First Year of Life

Early childhood infections have been implicated in the development of immune-mediated diseases, such as allergies, asthma, and type 1 diabetes. We set out to investigate the immunomodulatory effects of early viral infections experienced before the age of one year on the peripheral regulatory T cell population (Treg) and circulating cytokines in a birth-cohort study of Estonian and Finnish infants. We show here a temporal association of virus infection with the expression of FOXP3 in regulatory T cells. Infants with rhinovirus infection during the preceding 30 days had a higher FOXP3 expression in Treg cells and decreased levels of several cytokines related to Th1 and Th2 responses in comparison to the children without infections. In contrast, FOXP3 expression was significantly decreased in highly activated (CD4+CD127-/loCD25+FOXP3high) regulatory T cells (TregFOXP3high) in the infants who had enterovirus infection during the preceding 30 or 60 days. After enterovirus infections, the cytokine profile showed an upregulation of Th1- and Th17-related cytokines and a decreased activation of CCL22, which is a chemokine derived from dendritic cells and associated with Th2 deviation. Our results reveal that immunoregulatory mechanisms are up-regulated after rhinovirus infections, while enterovirus infections are associated with activation of proinflammatory pathways and decreased immune regulation.

Interleukin-17A Facilitates Chikungunya Virus Infection by Inhibiting IFN-α2 Expression

Interferons (IFNs) are the key components of innate immunity and are crucial for host defense against viral infections. Here, we report a novel role of interleukin-17A (IL-17A) in inhibiting IFN-α2 expression thus promoting chikungunya virus (CHIKV) infection. CHIKV infected IL-17A deficient (Il17a^-/- ) mice expressed a higher level of IFN-α2 and developed diminished viremia and milder footpad swelling in comparison to wild-type (WT) control mice, which was also recapitulated in IL-17A receptor-deficient (Il17ra^-/- ) mice. Interestingly, IL-17A selectively blocked IFN-α2 production during CHIKV, but not West Nile virus (WNV) or Zika virus (ZIKV), infections. Recombinant IL-17A treatment inhibited CHIKV-induced IFN-α2 expression and enhanced CHIKV replication in both human and mouse cells. We further found that IL-17A inhibited IFN-α2 production by modulating the expression of Interferon Regulatory Factor-5 (IRF-5), IRF-7, IFN-stimulated gene 49 (ISG-49), and Mx1 expression during CHIKV infection. Neutralization of IL-17A in vitro leads to the increase of the expression of these antiviral molecules and decrease of CHIKV replication. Collectively, these results suggest a novel function of IL-17A in inhibiting IFN-α2-mediated antiviral responses during CHIKV infection, which may have broad implications in viral infections and other inflammatory diseases.

CARD9 mediates T cell inflammatory response in Coxsackievirus B3-induced acute myocarditis

Cardiac inflammation in Coxsackievirus B3 (CVB3)-induced myocarditis is a consequence of viral-related cardiac injury and immune response. Caspase-associated recruitment domain 9 (CARD9) is a critical adaptor protein involved in transduction of signals from various innate pattern recognition receptors. In this study, the role of CARD9 in acute viral myocarditis was evaluated. CARD9^-/- and C57BL/6 mice were infected with CVB3. On day 7 postinfection, myocardial tissue and blood samples were collected and examined. After CARD9 knockout, mRNA and protein levels of transforming growth factor-β(TGF-β), interleukin-17A(IL-17A), and CARD domain of B-cell CLL/lymphoma 10(BCL-10) in the myocardium were markedly lower in CARD9^-/- mice than in C57BL/6 mice with CVB3-induced viral myocarditis. This trend was similar for the pathological scores for inflammation and serum levels of cytokines interleukin-6(IL-6), interleukin-10(IL-10), interferon -γ(IFN-γ), TGF-β, and IL-17A. These results suggest that the CARD9-mediated secretion of pro-inflammatory cytokines plays an important role in the immune response to acute viral myocarditis.

Infection risk of dermatologic therapeutics during the COVID-19 pandemic: an evidence-based recalibration

Recommendations were made recently to limit or stop the use of oral and systemic immunotherapies for skin diseases due to potential risks to the patients during the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) COVID-19 pandemic. Herein, we attempt to identify potentially safe immunotherapies that may be used in the treatment of cutaneous diseases during the current COVID-19 pandemic. We performed a literature review to approximate the risk of SARS-CoV-2 infection, including available data on the roles of relevant cytokines, cell subsets, and their mediators in eliciting an optimal immune response against respiratory viruses in murine gene deletion models and humans with congenital deficiencies were reviewed for viral infections risk and if possible coronaviruses specifically. Furthermore, reported risk of infections of biologic and non-biologic therapeutics for skin diseases from clinical trials and drug data registries were evaluated. Many of the immunotherapies used in dermatology have data to support their safe use during the COVID-19 pandemic including the biologics that target IgE, IL-4/13, TNF-α, IL-17, IL-12, and IL-23. Furthermore, we provide evidence to show that oral immunosuppressive medications such as methotrexate and cyclosporine do not significantly increase the risk to patients. Most biologic and conventional immunotherapies, based on doses and indications in dermatology, do not appear to increase risk of viral susceptibility and are most likely safe for use during the COVID-19 pandemic. The limitation of this study is availability of data on COVID-19.

Continued Elevation of Plasma IL-4 and IL-17 Predicts the Progression from VMC to DCM

Objective

To investigate plasma cytokines (interferon gamma, interleukin-4, and interleukin-17) in patients with viral myocarditis (VMC) and evaluate their predictive value in the progression from VMC to dilated cardiomyopathy (DCM).

Methods

A prospective, multicenter, observational study included 536 patients with newly diagnosed VMC admitted in cardiology departments of 24 tertiary super specialised university-affiliated hospitals in the China registry from January 2012 to June 2016. Demographics and clinical characteristics at baseline and after three months were collected, including laboratory blood tests, ECG, echocardiography, and drug treatment in each participating site. The plasma anti-viral antibodies (Abs), anti-heart autoimmune Abs, and cytokines were detected by ELISA.

Results

Of the 536 patients, 534 were included for analysis after two patients died in less than a month. The plasma levels of IFN-γ, IL-4, and IL-17 were continually higher in patients with incident DCM than in those without incident DCM at baseline, from the 1st month and the 3rd month; all had a P value of <0.0001. There was a positive correlation between IL-4 and LVEDd (r = 0.30, P < 0.0001) and between IL-17 and LVEDd (r = 0.11, P = 0.02). When all these covariates have entered the model simultaneously, elevated IL-4 and IL-17 were still significantly associated with DCM incidence. The RR (95% CI) of DCM incidence were 1.04 (1.02-1.06) for IL-4 and 5.24 (2.81-9.79) for IL-17.

Conclusion

The continued elevation of plasma IL-4 and IL-17 in VMC patients were associated with a high incidence of DCM at three months, and these two cytokines were independent predictors for the progression from VMC to DCM.

PGE2 ameliorated viral myocarditis development and promoted IL-10-producing regulatory B cell expansion via MAPKs/AKT-AP1 axis or AhR signaling

B10 cells, a specific subset of regulatory B cells, are capable of regulating immune response and restricting inflammation and autoimmune disease progression by producing IL-10. B10 cells frequently change significantly during inflammation and autoimmunity. However, how B10 cell populations change in viral myocarditis (VMC) remains unclear. Therefore, this work was conducted to clarify the changes in B10 cells and their potential mechanisms. Our results showed that the B10 cell frequency significantly changed in the VMC model. Changes in prostaglandin E2 (PGE2) levels in VMC model hearts were consistent with B10 expansion. PGE2 induced B10 cell expansion via the MAPKs/AKT-AP1 axis or AhR signaling. Additionally, PGE2-pretreated B10 cells inhibited naïve CD4⁺ T cell differentiation into Th17 cells. In vivo, PGE2 treatment or adoptive B10 cell transfer significantly restricted VMC development. Our results provide sufficient evidence that PGE2-induced B10 cell expansion may become a promising therapeutic approach for VMC and acute inflammatory injury.

Pathogenic Role of an IL-23/γδT17/Neutrophil Axis in Coxsackievirus B3-Induced Pancreatitis

Coxsackievirus B is a common cause of viral myocarditis and pancreatitis. IL-17A is intensively involved in the pathogenesis of viral myocarditis. Whether IL-17A plays a role in Coxsackievirus B-induced pancreatitis, characterized by acinar cell destruction and immune infiltration, remains largely unknown. We found a significant, but transient, increase of IL-17A expression and γδT influx in the pancreas of C57BL/6J mice within 3 d following CVB3 infection. The pancreatic IL-17A was mainly produced by Vγ4 γδ T cells, to a lesser extent by CD4⁺ Th17 cells. IL-17A^-/- and TCRδ^-/- mice both reduced their susceptibility to CVB3 infection and pancreatitis severity when compared with the wild-type mice, without altering viral load. mAb depletion of Vγ4γδ T cells significantly improved mice survival and pancreatic pathology via decreasing Th17 expansion and neutrophil influx into the pancreas compared with isotype-treated mice. Transfer of Vγ4γδ T cells from wild-type, but not IL-17^-/-, mice reconstituted TCRδ^-/- mice to produce IL-17 and develop pancreatitis to the level of wild-type mice during CVB3 infection, indicating γδ T IL-17A is required for the onset of viral pancreatitis. IL-23 was robustly induced in the pancreas within the first day of infection. Administration of exogenous rIL-23 to mice increased CVB3 pancreatitis through in vivo expansion of IL-17⁺γδT17 cells at 12 h postinfection. Our findings reveal a key pathogenic role for early-activated γδT17 cells in viral pancreatitis via promoting neutrophil infiltration and Th17 induction. This IL-23/γδT17/neutrophil axis is critically involved in the onset of CVB3 pancreatitis and represents a potential treating target for the disease.

IL-17 stimulates the expression of CCL2 in cardiac myocytes via Act1/TRAF6/p38MAPK-dependent AP-1 activation

IL-17 participates in the development of many autoimmune diseases by promoting the expression of some chemokines. Chemokine C-C motif ligand 2 (CCL2) is an important factor at the infiltration of mononuclear cells in the myocardial tissue of viral myocarditis (VMC). It was found that IL-17 could aggravate myocardial injury by upregulating CCL2. But the underlying mechanism involved in CCL2 secretion induced by IL-17 in cardiac myocytes remains unclear. This study investigated the role of transcription factor AP-1 in IL-17 induced CCL2 expression. The results showed that IL-17 mediated the activation of Act1, TRAF6, p38MAPK and c-Jun/AP-1 not Wnt or PI3K signalling pathway to upregulate CCL2 expression in cardiac myocytes. After blocking Act1/TRAF6/p38MAPK cascade and interfering AP-1 with Curcumin or c-Jun siRNA, CCL2 expression induced by IL-17 was significantly attenuated at both mRNA and protein levels. Furthermore, the phosphorylation of c-Jun was suppressed when cardiac myocytes were treated with Act1 siRNA, TRAF6 siRNA, SB203580 (p38MAPK inhibitor) or SP600125 (JNK inhibitor) in cardiac myocytes. In conclusion, IL-17 could stimulate the expression of CCL2 in cardiac myocytes via Act1/TRAF6/p38MAPK-dependent AP-1 activation, which may provide a new target for the diagnosis and treatment of VMC.

Dendritic cells and regulatory T cells expressing CCR4 provide resistance to coxsackievirus B5-induced pancreatitis

Type B coxsackieviruses (CVB) are enteroviruses responsible for a common infectious myocarditis and pancreatitis. DCs and regulatory T cells (Tregs) are key players in controlling virus replication and regulating the immune response and tissue damage, respectively. However, the mechanisms underlying cellular migration to target tissues remain unclear. In the present study, we found that CVB5 infection induced CCL17 production and controlled the migration of CCR4⁺ DCs and CCR4⁺ Tregs to the pancreatic lymph nodes (pLN). CVB5 infection of CCR4^-/- mice reduced the migration of the CD8α⁺ DC subset and reduced DC activation and production of IFN-β and IL-12. Consequently, CCR4^-/- mice presented decreased IFN-γ-producing CD4⁺ and CD8⁺ T cells, an increased viral load and more severe pancreatitis. In addition, CCR4^-/- mice had impaired Treg accumulation in pLN as well as increased T lymphocyte activation. Adoptive transfer of CCR4⁺ Tregs but not CCR4^- Tregs was able to regulate T lymphocyte activation upon CVB5 infection. The present data reveal a previously unknown role for CCR4 in coordinating immune cell migration to CVB-infected tissues and in controlling subsequent pancreatitis. These new insights may contribute to the design of future therapies for acute and chronic infection of non-polio enteroviruses.

The protective and pathogenic roles of IL-17 in viral infections: friend or foe?

Viral infections cause substantial human morbidity and mortality, and are a significant health burden worldwide. Following a viral infection, the host may initiate complex antiviral immune responses to antagonize viral invasion and replication. However, proinflammatory antiviral immune responses pose a great threat to the host if not properly held in check. Interleukin (IL)-17 is a pleiotropic cytokine participating in a variety of physiological and pathophysiological conditions, including tissue integrity maintenance, cancer progression, autoimmune disease development and, more intriguingly, infectious diseases. Abundant evidence suggests that while IL-17 plays a crucial role in enhancing effective antiviral immune responses, it may also promote and exacerbate virus-induced illnesses. Accumulated experimental and clinical evidence has broadened our understanding of the seemingly paradoxical role of IL-17 in viral infections and suggests that IL-17-targeted immunotherapy may be a promising therapeutic option. Herein, we summarize current knowledge regarding the protective and pathogenic roles of IL-17 in viral infections, with emphasis on underlying mechanisms. The various and critical roles of IL-17 in viral infections necessitate the development of therapeutic strategies that are uniquely tailored to both the infectious agent and the infection environment.

Recent Developments on the Crosstalk Between STAT3 and Inflammation in Heart Function and Disease

The transcription factor STAT3 has a protective function in the heart. Until recently, the role of STAT3 in hypertension-induced cardiac hypertrophy was unsettled. Earlier studies revealed that global reduction of STAT3 activity reduced cardiac hypertrophy with hypertension, but caused a disruption of myofilaments and increased contractile dysfunction. However, newer studies with cardiomyocyte-specific deletion of STAT3 indicate that STAT3 does not cause cardiac hypertrophy with increased blood pressure. Rather, cardiac STAT3 is important for maintaining metabolic homeostasis, and loss of STAT3 in cardiomyocytes makes the heart more susceptible to chronic pathological insult, for example by disrupting glucose metabolism and protective signaling networks via the upregulation of certain microRNAs. This scenario has implications for understanding peripartum cardiomyopathy as well. In viral myocarditis, STAT3 opposes the initiation of the dilated phenotype by maintaining membrane integrity via the expression of dystrophin. STAT3 signaling was also found to attenuate myocarditis by polarizing macrophages to a less inflammatory phenotype. On the other hand, STAT3 contributes to immune-mediated myocarditis due to IL-6-induced complement component C3 production in the liver, as well as the differentiation of Th17 cells, which play a role in initiation and development of myocarditis. Besides canonical signaling pathways, unphosphorylated STAT3 (U-STAT3) and redox-activated STAT3 have been shown to couple to transcription in the heart. In addition, tissue signaling cytokines such as IL-22 and IL-17 have been proposed to have actions on the heart that involve STAT3, but are not fully defined. Understanding the novel and often protective aspects of STAT3 in the myocardium could lead to new therapeutic approaches to treat heart disease.

Fasudil exerts a cardio-protective effect on mice with coxsackievirus B3-induced acute viral myocarditis

AIMS

To investigate whether there exists a cardio-protective effect of Fasudil, a selective Rho kinase (ROCK) inhibitor, in an experimental murine model of acute viral myocarditis.

METHODS

Male BALB/c mice were randomly assigned to three groups: control, myocarditis treated with placebo and myocarditis treated with Fasudil (n = 40 animals per group). Myocarditis was established by intraperitoneal injection with coxsackievirus B3 (CVB3). Twenty-four hours after infection, Fasudil was intraperitoneally administered for 14 consecutive days. Twenty mice were randomly selected from each group to monitor a 14-day survival rate. On day 7 and day 14, eight surviving mice from each group were sacrificed and their hearts and blood were obtained to perform serological and histological examinations. Expression of ROCKs, IL-17, IL-1b, TNFα, RORgt, and Foxp3 were quantified with RT-PCR. Plasma levels of TNF alpha, IL-1 beta, and IL-17 were measured by ELISA. In addition, protein levels of IL-17 and ROCK2 in cardiac tissues were analyzed with Western blot.

RESULTS

Fasudil treatment significantly increased survival, attenuated myocardial necrotic lesions, reduced CVB3 replication and expression of ROCK2 and IL-17 in the infected hearts. This treatment also imposed a T-cell subpopulation shift, from Th17 to Treg, in cardiac tissues.

CONCLUSIONS

ROCK pathway inhibition was cardio-protective in viral myocarditis with increased survival, decreased viral replication, and inflammatory response. These findings suggest that Fasudil might be a potential therapeutic agent for patients with viral myocarditis.

Regulatory Role of CD4+ T Cells in Myocarditis

Myocarditis is an important cause of heart failure in young patients. Autoreactive, most often, infection-triggered CD4⁺ T cells were confirmed to be critical for myocarditis induction. Due to a defect in clonal deletion of heart-reactive CD4⁺ T cells in the thymus of mice and humans, significant numbers of heart-specific autoreactive CD4⁺ T cells circulate in the blood. Normally, regulatory T cells maintain peripheral tolerance and prevent spontaneous myocarditis development. In the presence of tissue damage and innate immune activation, however, activated self-antigen-loaded dendritic cells promote CD4⁺ effector T cell expansion and myocarditis. So far, a direct pathogenic role has been described for both activated Th17 and Th1 effector CD4⁺ T cell subsets, though Th1 effector T cell-derived interferon-gamma was shown to limit myocarditis severity and prevent transition to inflammatory dilated cardiomyopathy. Interestingly, recent observations point out that various CD4⁺ T cell subsets demonstrate high plasticity in maintaining immune homeostasis and modulating disease phenotypes in myocarditis. These subsets include Th1 and Th17 effector cells and regulatory T cells, despite the fact that there are still sparse and controversial data on the specific role of FOXP3-expressing Treg in myocarditis. Understanding the specific roles of these T cell populations at different stages of the disease progression might provide a key for the development of successful therapeutic strategies.

Immunomodulation by adoptive regulatory T-cell transfer improves Coxsackievirus B3-induced myocarditis

Regulatory T (Treg) cells offer new therapeutic options for controlling undesired systemic and local immune responses. The aim of the current study was to determine the impact of therapeutic Treg administration on systemic and cardiac inflammation and remodeling in coxsackievirus B3 (CVB3) -induced myocarditis. Therefore, syngeneic Treg cells were applied intravenously in CVB3-infected mice 3 d after infection. Compared with CVB3 + PBS mice, CVB3 + Treg mice exhibited lower left ventricular (LV) chemokine expression, accompanied by reduced cardiac presence of proinflammatory Ly6ChighCCR2highCx3Cr1low monocytes and higher retention of proinflammatory Ly6CmidCCR2highCx3Cr1low monocytes in the spleen. In addition, splenic myelopoiesis was reduced in CVB3 + Treg compared with CVB3 + PBS mice. Coculture of Treg cells with splenocytes isolated from mice 3 d post-CVB3 infection further demonstrated the ability of Treg cells to modulate monocyte differentiation in favor of the anti-inflammatory Ly6ClowCCR2lowCx3Cr1high subset. Treg-mediated immunomodulation was paralleled by lower collagen 1 protein expression and decreased levels of soluble and insoluble collagen in LV of CVB3 + Treg compared with CVB3 + PBS mice. In agreement with these findings, LV systolic and diastolic function was improved in CVB3 + Treg mice compared with CVB3 + PBS mice. In summary, adoptive Treg transfer in the inflammatory phase of viral-induced myocarditis protects the heart against inflammatory damage and fibrosis via modulation of monocyte subsets.-Pappritz, K., Savvatis, K., Miteva, K., Kerim, B., Dong, F., Fechner, H., Müller, I., Brandt, C., Lopez, B., González, A., Ravassa, S., Klingel, K., Diez, J., Reinke, P., Volk, H.-D., Van Linthout, S., Tschöpe, C. Immunomodulation by adoptive regulatory T-cell transfer improves Coxsackievirus B3-induced myocarditis.

Roles of Host Immunity in Viral Myocarditis and Dilated Cardiomyopathy

The pathogenesis of viral myocarditis includes both the direct damage mediated by viral infection and the indirect lesion resulted from host immune responses. Myocarditis can progress into dilated cardiomyopathy that is also associated with immunopathogenesis. T cell-mediated autoimmunity, antibody-mediated autoimmunity (autoantibodies), and innate immunity, working together, contribute to the development of myocarditis and dilated cardiomyopathy.

Progranulin ameliorates coxsackievirus-B3-induced viral myocarditis by downregulating Th1 and Th17 cells

Viral myocarditis, which is caused by Coxsackievirus B3 (CVB3) infection, is a leading reason of sudden cardiac death in young adults. Progranulin (PGRN), a pleiotropic growth factor, has been shown to exert anti-inflammatory function in a variety of inflammatory diseases. However, the expression and function of PGRN in the pathogenesis of viral myocarditis remain largely unknown. In this study, we found that PGRN levels in plasma and cardiac tissues were significantly upregulated post CVB3 infection, and negative correlated with disease severity. PGRN deficiency significantly exacerbated, whereas recombinant PGRN treatment attenuated CVB3-induced myocarditis in mice. PGRN downregulated Th1 and Th17 cell responses and cytokine production in vitro and in vivo, whereas its effect on viral myocarditis was Treg cell independent. Furthermore, PGRN regulated Th1 and Th17 cells differentiation through inhibition of the JAK/STAT pathway. Therefore, our findings reveal a critical role for PGRN in reducing CVB3-induced myocarditis and suggest that PGRN maybe a novel therapeutic treatment for viral myocarditis.

Role of gene polymorphisms/haplotypes and serum levels of interleukin-17A in susceptibility to viral myocarditis

Interleukin-17A (IL-17A) has been implicated in the pathogenesis of viral myocarditis (VMC). However, the role of IL-17A polymorphisms in susceptibility to VMC has not been reported to date. The aim of this study was to explore the association between IL-17A variants as well as serum IL-17 levels with VMC. Three single-nucleotide polymorphisms (SNPs) (rs2275913, rs3819025, and rs3748067) were analyzed by the polymerase chain reaction-restriction fragment length polymorphism method in 236 VMC patients and 259 controls from China. Serum IL-17A levels were measured by enzyme-linked immunosorbent assay kits. Multivariable logistic regression analysis that the rs2275913 AA genotype and the haplotype -197A/+45G/+1249G (AGG) were associated with an increased risk of VMC (all P < 0.05). Consistent with these findings, the rs2275913 AA genotype was linked to higher serum IL-17A compared to GG/AG genotype (all P < 0.001). We observed no associations between the other two SNPs and risk of VMC. Serum IL-17A levels were significantly higher in the VMC group than controls (P < 0.001) and gradually increased with the increase of New York Heart Association grade in VMC patients (P < 0.05). Spearman correlation test revealed that the serum IL-17A level was correlated with the cardiac damage and left ventricular systolic functions among VMC patients (all P < 0.05). Our study reveals that IL-17A expression may contribute to the development and severity of VMC. The SNP rs2275913 in the IL-17A gene might exert influence on susceptibility to VMC via linking with the serum IL-17A level.

Interleukin-37 Ameliorates Coxsackievirus B3-induced Viral Myocarditis by Modulating the Th17/Regulatory T cell Immune Response

Myocarditis is a heterogeneous group of disorders defined by inflammation of the heart muscle with an excessively activated immune response. Numerous interventions have been investigated for the treatment of myocarditis while success is limited. Interleukin-37 (IL-37), a novel member of the IL-1 cytokine family, is a natural inhibitor of innate immunity associated with autoimmune diseases. However, the modulatory effect of IL-37 in myocarditis is unknown. In this study, we investigated the immunological regulation of IL-37 in the coxsackievirus B3-induced model of murine viral myocarditis. The results show that IL-37 significantly ameliorates the signs of myocarditis with increased survival rate and bodyweight, improved histological changes, reduced activities of MB isoenzyme of creatine kinase and cardiac troponin I, and a suppressed response of Th17 cells and enhanced response of regulatory T cells (Tregs) in the spleen. Moreover, IL-37 down-regulates the expression of Th17-related cytokines IL-6 and IL-17A, while promoting Treg-related cytokine IL-10 levels in the heart. Therefore, IL-37 may exhibit anti-inflammatory activity in the murine model of myocarditis by regulating the balance between Th17 and Treg cells, thereby providing a possible novel therapeutic target in myocarditis.

TLR3 is required for survival following Coxsackievirus B3 infection by driving T lymphocyte activation and polarization: The role of dendritic cells

Type B coxsackievirus (CVB) is a common cause of acute and chronic myocarditis, meningitis and pancreatitis, often leading to heart failure and pancreatic deficiency. The polarization of CD4⁺ T lymphocytes and their cytokine milieu are key factors in the outcome of CVB-induced diseases. Thus, sensing the virus and driving the adaptive immune response are essential for the establishment of a protective immune response. TLR3 is a crucial virus recognition receptor that confers the host with resistance to CVB infection. In the current study, we found that TLR3 expression in dendritic cells plays a role in their activation upon CVB3 infection in vitro, as TLR3-deficient dendritic cells up-regulate CD80 and CD86 to a less degree than WT cells. Instead, they up-regulated the inhibitory molecule PD-L1 and secreted considerably lower levels of TNF-α and IL-10 and a higher level of IL-23. T lymphocyte proliferation in co-culture with CVB3-infected dendritic cells was increased by TLR3-expressing DCs and other cells. Furthermore, in the absence of TLR3, the T lymphocyte response was shifted toward a Th17 profile, which was previously reported to be deleterious for the host. TLR3-deficient mice were very susceptible to CVB3 infection, with increased pancreatic injury and extensive inflammatory infiltrate in the heart that was associated with uncontrolled viral replication. Adoptive transfer of TLR3⁺ dendritic cells slightly improved the survival of TLR-deficient mice following CVB3 infection. Therefore, our findings highlight the importance of TLR3 signaling in DCs and in other cells to induce activation and polarization of the CD4⁺ T lymphocyte response toward a Th1 profile and consequently for a better outcome of CVB3 infection. These data provide new insight into the immune-mediated mechanisms by which CVBs are recognized and cleared in order to prevent the development of myocarditis and pancreatitis and may contribute to the design of therapies for enteroviral infections.

Evaluation of a rapid detection for Coxsackievirus B3 using one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP)

Coxsackievirus B3 (CVB3) is a member of the genus Enterovirus within the family Picornaviridae and is an important pathogen of viral myocarditis, which accounts for more than 50% viral myocarditis cases. VP1 is major capsid protein that this region has a low homology in both amino acid and nucleotide sequences among Enteroviruses. Therefore we have chosen this region for designed a set of RT-LAMP primers for CVB3 detection. For this the total RNA was extracted from 24-h post infected-HeLa cells with complete cytopathic effect (CPE), and applied to a one-step reverse transcription loop-mediated isothermal amplification reaction (RT-LAMP) using CVB3-specific primers. The optimization of RT-LAMP reaction was carried out with three variables factors including MgSO₄ concentration, temperature and time of incubation. Amplification was analyzed by using 2% agarose gel electrophoresis and ethidium bromide and SYBR Green staining. Our results were shown the ladder-like pattern of the VP1 gene amplification. The LAMP reaction mix was optimized and the best result observed at 4mM MgSO₄ and 60°C for 90min incubation. RT-LAMP had high sensitivity and specificity for detection of CVB3 infection. This method can be used as a rapid and easy diagnostic test for detection of CVB3 in clinical laboratories.

Coxsackievirus B3 Directly Induced Th17 Cell Differentiation by Inhibiting Nup98 Expression in Patients with Acute Viral Myocarditis

Th17 cells play a key role in the progression of coxsackievirus B3 (CVB3)-induced acute viral myocarditis (AVMC). However, the direct effect of virus on Th17 cell differentiation is still unknown. Recently, nucleoporin (Nup) 98 has been proved to be associated with lymphocyte differentiation. Therefore, we investigated whether Nup98 mediated Th17 cell differentiation in AVMC. In our study, patients with AVMC and healthy controls were recruited. The results showed that CVB3 could enter into the CD4⁺ T cells in AVMC patients and healthy controls. After transfecting purified CD4⁺ T cells with CVB3 in vitro, the Th17 cell frequency, IL-17 secretion, and RORγT synthesis were increased while the Nup98 levels were decreased. Furthermore, down-regulating Nup98 expression by siRNA-Nup98 in CD4⁺ T cells resulted in the elevated Th17 cell frequency and IL-17 secretion, along with enhanced levels of RORγT, dissociative p300/CBP, and acetylated Stat3. Up-regulation of Nup98 expression by pcDNA3.1-Nup98 showed the opposite effects. Our results suggested that CVB3 directly induced CD4⁺ T cell differentiation into Th17 cells by inhibiting Nup98 expression, representing a therapeutic target in AVMC.

Three immune-mediated disease models induced by Theiler's virus: Multiple sclerosis, seizures and myocarditis

Theiler's murine encephalomyelitis virus (TMEV) infection has been used as a viral model for multiple sclerosis (MS), as TMEV can induce chronic inflammatory demyelinating lesions with viral persistence in the spinal cord of SJL/J mice. In contrast, when C57BL/6 mice are infected with TMEV, the mice can clear the virus from the central nervous system (CNS), without viral persistence or demyelination, but develop seizures and hippocampal sclerosis, which has been used as a viral model for seizures/epilepsy. In the two TMEV-induced CNS disease models, not only viral infection, but also immune responses contribute to the pathogenesis. Interestingly, acquired immunity plays an effector role in the MS model, whereas innate immunity appears to contribute to the development of seizures. Recently, we have established the third TMEV-induced disease model, a mouse model for viral myocarditis, using C3H mice. TMEV-induced myocarditis is a triphasic disease, which mimics human myocarditis; phase I, mediated by viral replication in the heart and innate immunity; phase II, mediated by acquired immunity; and phase III, resulted from cardiac fibrosis. The genetic susceptibility to the aforementioned three models (MS, seizures and myocarditis) differs among mouse strains. We have compared and contrasted the three models induced by one single pathogen, TMEV, particularly in regard to the roles of T helper cells and natural killer T cells, which will give an insight into how interactions between the immune system and the host's genetic background determine the tissue tropism of virus and the development of virus-induced organ-specific immunopathology.

Valproic acid ameliorates coxsackievirus-B3-induced viral myocarditis by modulating Th17/Treg imbalance

Background

Viral myocarditis, which is often caused by coxsackievirus B3 (CVB3), is a serious clinical disorder characterized by excessive myocardial inflammation. Valproic acid (VPA) is described as a histone deacetylase inhibitor that has anti-inflammatory effects in several inflammatory diseases. However, the role and the detailed mechanism of VPA in viral myocarditis remain unclear.

Methods

Experimental CVB3-induced myocarditis was induced in mice by intraperitoneally (i.p.) infected with CVB3. VPA was i.p. administered from day 0 to day 7. The survival, body weight loss, and myocarditis severity of mice were recorded. Th17 and Treg cells in spleen were analyzed by flow cytometry. Th17/Treg cell-related cytokine expressions were quantified by ELISA. The effect of VPA on Th17 and Treg cells differentiation was examined in vitro and in vivo.

Results

Administration of VPA significantly attenuated the clinical severity of myocarditis, and the overall mortality from CVB3-induced myocarditis. The infiltration of Th17 and Treg cells, as well as the serum level of related cytokines (IL-17A and IL-10), were increased in CVB3 infected mice. In addition, VPA decreased the percentage of splenic Th17 cells while increased the percentage of Treg cells. Moreover, VPA downregulated the expression of IL-17A and upregulated IL-10 in serum and heart tissues of CVB3 infected mice. Additionally, VPA directly inhibited the differentiation of Th17 cells and promoted both the differentiation and suppressive function of Treg cells in vitro and in vivo.

Conclusions

Our results suggest that VPA may thus be a promising strategy in the therapy of viral myocarditis.

IL-9 Inhibits Viral Replication in Coxsackievirus B3-Induced Myocarditis

Myocardial injuries in viral myocarditis (VMC) are caused by viral infection and related autoimmune disorders. Recent studies suggest that IL-9 mediated both antimicrobial immune and autoimmune responses in addition to allergic diseases. However, the role of IL-9 in viral infection and VMC remains controversial and uncertain. In this study, we infected Balb/c mice with Coxsackievirus B3 (CVB3), and found that IL-9 was enriched in the blood and hearts of VMC mice on days 5 and 7 after virus infection. Most of IL-9 was secreted by CD8+ T cells on day 5 and CD4+ T cells on day 7 in the myocardium. Further, IL-9 knockout exacerbated cardiac damage following CVB3 infection, along with a sharp increase in viral replication and IL-17a expression, as well as a decrease in TGF-β. In contrast, the repletion of IL-9 in Balb/c mice with CVB infection induced the opposite effect. Studies in vitro further revealed that IL-9 directly inhibited viral replication in cardiomyocytes by reducing coxsackie and adenovirus receptor expression, which might be associated with upregulation of TGF-β autocrine effect in these cells. However, IL-9 had no direct effect on apoptosis in cardiomyocytes. Our data indicated that IL-9 played a protective role in disease progression by inhibiting CVB3 replication in the early stages of VMC.

Common variants in IL-17A/IL-17RA axis contribute to predisposition to and progression of congestive heart failure

Heart failure is characterized by immune activation leading to production and release of proinflammatory cytokines. Interleukin 17A (IL-17A) is a proinflammatory cytokine and multiple lines of evidence from animal and human studies suggest crucial roles of IL-17A in heart failure. Therefore, we investigated whether common polymorphisms of genes IL17A and IL17RA (coding interleukin 17 receptor A) contribute to genetic predisposition to heart failure and adverse clinical outcomes associated with it.A total of 1713 adult patients with congestive heart failure and 1713 age- and sex-matched controls were genotyped for promoter single nucleotide polymorphisms (SNPs), rs2275913 and rs8193037 in IL17A and rs4819554 in IL17RA, to assess the relationship between individual SNPs and the risk of congestive heart failure. Results showed that rs8193037 in IL17A was associated with the risk of congestive heart failure (odds ratio [OR] = 0.76; 95% confidence interval [CI] 0.63-0.90, adjusted P = 0.002) after adjustment for multiple cardiovascular risk factors including age, sex, smoking status, diabetes, hypertension, and dyslipidemia. This association was evident in both ischemic and nonischemic heart failure (P = 0.005 and P = 0.05, respectively). Furthermore, prospective follow-up of 12.7 months for the occurrence of adverse clinical outcomes showed that rs4819554 in IL17RA was significantly associated with cardiovascular mortality (hazard ratio [HR] = 1.28; 95% CI = 1.02-1.59, adjusted P = 0.03) after adjustments for multiple cardiovascular risk factors and New York Heart Association functional class.This study demonstrated associations of rs8193037 in the promoter of IL17A with the risk of congestive heart failure, and of rs4819554 in the promoter of IL17RA with the risk of cardiovascular mortality in patients with congestive heart failure. These data lend further support to the notion that immune activation and genetic polymorphisms contribute to heart failure pathogenesis and progression.