Michael J. Coronado

Th2 Regulation of Viral Myocarditis in Mice: Different Roles for TLR3 versus TRIF in Progression to Chronic Disease

Viral infections are able to induce autoimmune inflammation in the heart. Here, we investigated the role of virus-activated Toll-like receptor (TLR)3 and its adaptor TRIF on the development of autoimmune coxsackievirus B3 (CVB3) myocarditis in mice. Although TLR3- or TRIF-deficient mice developed similarly worse acute CVB3 myocarditis and viral replication compared to control mice, disease was significantly worse in TRIF compared to TLR3-deficient mice. Interestingly, TLR3-deficient mice developed an interleukin (IL)-4-dominant T helper (Th)2 response during acute CVB3 myocarditis with elevated markers of alternative activation, while TRIF-deficient mice elevated the Th2-associated cytokine IL-33. Treatment of TLR3-deficient mice with recombinant IL-33 improved heart function indicating that elevated IL-33 in the context of a classic Th2-driven response protects against autoimmune heart disease. We show for the first time that TLR3 versus TRIF deficiency results in different Th2 responses that uniquely influence the progression to chronic myocarditis.

Testosterone and interleukin-1β increase cardiac remodeling during coxsackievirus B3 myocarditis via serpin A 3n

Myocarditis and dilated cardiomyopathy (DCM) are often caused by viral infections and occur more frequently in men than in women, but the reasons for the sex difference remain unclear. The aim of this study was to assess whether gene changes in the heart during coxsackievirus B3 (CVB3) myocarditis in male and female BALB/c mice predicted worse DCM in males. Although myocarditis (P = 4.2 × 10(-5)) and cardiac dilation (P = 0.008) were worse in males, there was no difference in viral replication in the heart. Fibrotic remodeling genes, such as tissue inhibitor of metalloproteinase (TIMP)-1 and serpin A 3n, were upregulated in males during myocarditis rather than during DCM. Using gonadectomy and testosterone replacement, we showed that testosterone increased cardiac TIMP-1 (P = 0.04), serpin A 3n (P = 0.007), and matrix metalloproteinase (MMP)-8 (P = 0.04) during myocarditis. Testosterone increased IL-1β levels in the heart (P = 0.02), a cytokine known to regulate cardiovascular remodeling, and IL-1β in turn increased cardiac serpin A 3n mRNA (P = 0.005). We found that 39 of 118 (33%) genes identified in acute DCM patients were significantly altered in the heart during CVB3 myocarditis in mice, including serpin A 3n (3.3-fold change, P = 0.0001). Recombinant serpin A 3n treatment induced cardiac fibrosis during CVB3 myocarditis (P = 0.0008) while decreasing MMP-3 (P = 0.04) and MMP-9 (P = 0.03) levels in the heart. Thus, serpin A 3n was identified as a gene associated with fibrotic cardiac remodeling and progression to DCM in male myocarditis patients and mice.

Autoimmune heart disease: role of sex hormones and autoantibodies in disease pathogenesis

Cardiovascular disease (CVD) and autoimmune diseases (ADs) are the first and third highest causes of death in the USA, respectively. Men have an increased incidence of the majority of CVDs, including atherosclerosis, myocarditis, dilated cardiomyopathy and heart failure. By contrast, nearly 80% of all ADs occur in women. However, in one category of ADs, rheumatic diseases, CVD is the main cause of death. Factors that link rheumatic ADs to CVD are inflammation and the presence of autoantibodies. In this review we will examine recent findings regarding sex differences in the immunopathogenesis of CVD and ADs, explore possible reasons for the increased occurrence of CVD within rheumatic ADs and discuss whether autoantibodies, including rheumatoid factor, could be involved in disease pathogenesis.

The innate immune response to coxsackievirus B3 predicts progression to cardiovascular disease and heart failure in male mice

BackgroundMen are at an increased risk of dying from heart failure caused by inflammatory heart diseases such as atherosclerosis, myocarditis and dilated cardiomyopathy (DCM). We previously showed that macrophages in the spleen are phenotypically distinct in male compared to female mice at 12 h after infection. This innate immune profile mirrors and predicts the cardiac immune response during acute myocarditis.MethodsIn order to study sex differences in the innate immune response, five male and female BALB/c mice were infected intraperitoneally with coxsackievirus B3 (CVB3) or phosphate buffered saline and their spleens were harvested 12 h later for microarray analysis. Gene expression was determined using an Affymetrix Mouse Gene 1.0 ST Array. Significant gene changes were verified by quantitative real-time polymerase chain reaction or ELISA.ResultsDuring the innate immune response to CVB3 infection, infected males had higher splenic expression of genes which are important in regulating the influx of cholesterol into macrophages, such as phospholipase A2 (PLA2) and the macrophage scavenger receptor compared to the infected females. We also observed a higher expression in infected males compared to infected females of squalene synthase, an enzyme used to generate cholesterol within cells, and Cyp2e1, an enzyme important in metabolizing cholesterol and steroids. Infected males also had decreased levels of the translocator protein 18 kDa (TSPO), which binds PLA2 and is the rate-limiting step for steroidogenesis, as well as decreased expression of the androgen receptor (AR), which indicates receptor activation. Gene differences were not due to increased viral replication, which was unaltered between sexes.ConclusionsWe found that, compared to females, male mice had a greater splenic expression of genes which are important for cholesterol metabolism and activation of the AR at 12 h after infection. Activation of the AR has been linked to increased cardiac hypertrophy, atherosclerosis, myocarditis/DCM and heart failure in male mice and humans.

TLR3 deficiency induces chronic inflammatory cardiomyopathy in resistant mice following coxsackievirus B3 infection: role for IL-4

Recent findings indicate that TLR3 polymorphisms increase susceptibility to enteroviral myocarditis and inflammatory dilated cardiomyopathy (iDCM) in patients. TLR3 signaling has been found to inhibit coxsackievirus B3 (CVB3) replication and acute myocarditis in mouse models, but its role in the progression from myocarditis to iDCM has not been previously investigated. In this study we found that TLR3 deficiency increased acute (P = 5.9 × 10(-9)) and chronic (P = 6.0 × 10(-7)) myocarditis compared with WT B6.129, a mouse strain that is resistant to chronic myocarditis and iDCM. Using left ventricular in vivo hemodynamic assessment, we found that TLR3-deficient mice developed progressively worse chronic cardiomyopathy. TLR3 deficiency significantly increased viral replication in the heart during acute myocarditis from day 3 through day 12 after infection, but infectious virus was not detected in the heart during chronic disease. TLR3 deficiency increased cytokines associated with a T helper (Th)2 response, including IL-4 (P = 0.03), IL-10 (P = 0.008), IL-13 (P = 0.002), and TGF-β(1) (P = 0.005), and induced a shift to an immunoregulatory phenotype in the heart. However, IL-4-deficient mice had improved heart function during acute CVB3 myocarditis by echocardiography and in vivo hemodynamic assessment compared with wild-type mice, indicating that IL-4 impairs cardiac function during myocarditis. IL-4 deficiency increased regulatory T-cell and macrophage populations, including FoxP3(+) T cells (P = 0.005) and Tim-3(+) macrophages (P = 0.004). Thus, TLR3 prevents the progression from myocarditis to iDCM following CVB3 infection by reducing acute viral replication and IL-4 levels in the heart.

IL-33 Independently Induces Eosinophilic Pericarditis and Cardiac Dilation: ST2 Improves Cardiac Function

Background— IL-33 through its receptor ST2 protects the heart from myocardial infarct and hypertrophy in animal models but, paradoxically, increases autoimmune disease. In this study, we examined the effect of IL-33 or ST2 administration on autoimmune heart disease. Methods and Results— We used pressure-volume relationships and isoproterenol challenge to assess the effect of recombinant (r) IL-33 or rST2 (eg, soluble ST2) administration on the development of autoimmune coxsackievirus B3 myocarditis and dilated cardiomyopathy in male BALB/c mice. The rIL-33 treatment significantly increased acute perimyocarditis (P=0.006) and eosinophilia (P=1.3×10−5), impaired cardiac function (maximum ventricular power, P=0.0002), and increased ventricular dilation (end-diastolic volume, P=0.01). The rST2 treatment prevented eosinophilia and improved heart function compared with rIL-33 treatment (ejection fraction, P=0.009). Neither treatment altered viral replication. The rIL-33 treatment increased IL-4, IL-33, IL-1&bgr;, and IL-6 levels in the heart during acute myocarditis. To determine whether IL-33 altered cardiac function on its own, we administered rIL-33 to undiseased mice and found that rIL-33 induced eosinophilic pericarditis and adversely affected heart function. We used cytokine knockout mice to determine that this effect was due to IL-33-mediated signaling but not to IL-1&bgr; or IL-6. Conclusions— We show for the first time to our knowledge that IL-33 induces eosinophilic pericarditis, whereas soluble ST2 prevents eosinophilia and improves systolic function, and that IL-33 independently adversely affects heart function through the IL-33 receptor.

Biomarkers of Heart Failure in Myocarditis and Dilated Cardiomyopathy

There are many reviews that discuss the role of biomarkers in cardiovascular disease (CVD) and heart failure (Braunwald, 2008; Chen et al., 2010; Hochholzer et al., 2010), but little information exists regarding the presence and usefulness of biomarkers for heart failure in myocarditis and dilated cardiomyopathy (DCM) patients. Heart failure (HF) is the end consequence of many CVDs including atherosclerosis, myocardial infarction, myocarditis and DCM. CVD is the leading cause of morbidity and mortality in Western nations (Roger et al., 2011), and a growing concern worldwide (Gaddam et al., 2011). As treatments for CVD prolong survival, the prevalence of chronic HF has increased. It is now estimated that 5.8 million people in the United States live with HF and over 23 million worldwide (Bui et al., 2011). Approximately 550,000 new cases of HF are diagnosed each year, with a lifetime risk for developing disease of one in five (Chen et al., 2010; Krumholz et al., 1997). Hospitalizations for HF have also increased dramatically in the United States from 402,000 in 1979 to 2.4 million in 2007 with the cost of treating HF patients estimated at

IL-33 Independently Induces Eosinophilic Pericarditis and Cardiac DilationClinical Perspective

39 billion annually (Bui et al., 2011; Chen et al., 2010; Roger et al., 2011). Biomarkers have become an increasingly important clinical tool for assessing CVD and progression to HF. Biomarkers are used in early detection of sub-clinical disease, diagnosis, risk stratification, monitoring disease state, and to determine therapies (Hochholzer et al., 2010). Many biomarkers are also risk factors directly involved in the pathogenesis of disease.

IL-33 Independently Induces Eosinophilic Pericarditis and Cardiac DilationClinical Perspective: ST2 Improves Cardiac Function

Background— IL-33 through its receptor ST2 protects the heart from myocardial infarct and hypertrophy in animal models but, paradoxically, increases autoimmune disease. In this study, we examined the effect of IL-33 or ST2 administration on autoimmune heart disease. Methods and Results— We used pressure-volume relationships and isoproterenol challenge to assess the effect of recombinant (r) IL-33 or rST2 (eg, soluble ST2) administration on the development of autoimmune coxsackievirus B3 myocarditis and dilated cardiomyopathy in male BALB/c mice. The rIL-33 treatment significantly increased acute perimyocarditis (P=0.006) and eosinophilia (P=1.3×10−5), impaired cardiac function (maximum ventricular power, P=0.0002), and increased ventricular dilation (end-diastolic volume, P=0.01). The rST2 treatment prevented eosinophilia and improved heart function compared with rIL-33 treatment (ejection fraction, P=0.009). Neither treatment altered viral replication. The rIL-33 treatment increased IL-4, IL-33, IL-1&bgr;, and IL-6 levels in the heart during acute myocarditis. To determine whether IL-33 altered cardiac function on its own, we administered rIL-33 to undiseased mice and found that rIL-33 induced eosinophilic pericarditis and adversely affected heart function. We used cytokine knockout mice to determine that this effect was due to IL-33-mediated signaling but not to IL-1&bgr; or IL-6. Conclusions— We show for the first time to our knowledge that IL-33 induces eosinophilic pericarditis, whereas soluble ST2 prevents eosinophilia and improves systolic function, and that IL-33 independently adversely affects heart function through the IL-33 receptor.

Gonadectomy of male BALB/c mice increases Tim-3+ alternatively activated M2 macrophages, Tim-3+ T cells, Th2 cells and Treg in the heart during acute coxsackievirus-induced myocarditis

Background— IL-33 through its receptor ST2 protects the heart from myocardial infarct and hypertrophy in animal models but, paradoxically, increases autoimmune disease. In this study, we examined the effect of IL-33 or ST2 administration on autoimmune heart disease. Methods and Results— We used pressure-volume relationships and isoproterenol challenge to assess the effect of recombinant (r) IL-33 or rST2 (eg, soluble ST2) administration on the development of autoimmune coxsackievirus B3 myocarditis and dilated cardiomyopathy in male BALB/c mice. The rIL-33 treatment significantly increased acute perimyocarditis (P=0.006) and eosinophilia (P=1.3×10−5), impaired cardiac function (maximum ventricular power, P=0.0002), and increased ventricular dilation (end-diastolic volume, P=0.01). The rST2 treatment prevented eosinophilia and improved heart function compared with rIL-33 treatment (ejection fraction, P=0.009). Neither treatment altered viral replication. The rIL-33 treatment increased IL-4, IL-33, IL-1&bgr;, and IL-6 levels in the heart during acute myocarditis. To determine whether IL-33 altered cardiac function on its own, we administered rIL-33 to undiseased mice and found that rIL-33 induced eosinophilic pericarditis and adversely affected heart function. We used cytokine knockout mice to determine that this effect was due to IL-33-mediated signaling but not to IL-1&bgr; or IL-6. Conclusions— We show for the first time to our knowledge that IL-33 induces eosinophilic pericarditis, whereas soluble ST2 prevents eosinophilia and improves systolic function, and that IL-33 independently adversely affects heart function through the IL-33 receptor.