Inhibition of mast cells by interleukin-10 gene transfer contributes to protection against acute myocarditis in rats

Aggravation of TGFβ1-Smad Pathway and Autoimmune Myocarditis by Fungicide (Tebuconazole) Exposure

Myocarditis is an inflammatory cardiac disorder and the primary cause of heart failure in young adults. Its origins can be attributed to various factors, including bacterial or viral infections, exposure to toxins or drugs, endocrine disruptors (EDs), and autoimmune processes. Tebuconazole (TEB), which is a member of the triazole fungicide family, is utilized to safeguard agricultural crop plants against fungal pathogens. Although TEB poses serious threats to mammal health, the information about how it induces toxic effects through various pathways, particularly in autoimmune diseases, are still limited. Thus, the aim of this paper was to evaluate the effect of TEB exposure in autoimmune myocarditis (AM). To induce AM, rats were immunized with porcine cardiac myosin and exposed to TEB for 21 days. Thereafter, animals were sacrificed, and histological, biochemical, and molecular analyses were performed. TEB exposure increased heart weight, systolic blood pressure and heart rate already augmented by AM. Additionally, it significantly increased creatine phosphokinase heart (CK-MB), creatine phosphokinase (CPK), cardiac troponin T (cTnT), and cardiac troponin I (cTnI), as compared to the control. From the histological perspective, TEB exacerbates the histological damage induced by AM (necrosis, inflammation and cell infiltration) and increased fibrosis and collagen deposition. TEB exposure strongly increased pro-inflammatory cytokines and prooxidant levels (O2^-, H₂O₂, NO₂^-, lipid peroxidation) and reduced antioxidant enzyme levels, which were already dysregulated by AM. Additionally, TEB increased NOX-4 expression and the TGFβ1-Smads pathway already activated by AM. Overall, our results showed that TEB exposure strongly aggravated the cardiotoxicity induced by AM.

Mast Cell Desensitization in Allergen Immunotherapy

Allergen immunotherapy (AIT) is the only treatment with disease-transforming potential for allergic disorders. The immunological mechanisms associated with AIT can be divided along time in two phases: short-term, involving mast cell (MC) desensitization; and long-term, with a regulatory T cell (Treg) response with significant reduction of eosinophilia. This regulatory response is induced in about 70% of patients and lasts up to 3 years after AIT cessation. MC desensitization is characteristic of the initial phase of AIT and it is often related to its success. Yet, the molecular mechanisms involved in allergen-specific MC desensitization, or the connection between MC desensitization and the development of a Treg arm, are poorly understood. The major AIT challenges are its long duration, the development of allergic reactions during AIT, and the lack of efficacy in a considerable proportion of patients. Therefore, reaching a better understanding of the immunology of AIT will help to tackle these short-comings and, particularly, to predict responder-patients. In this regard, omics strategies are empowering the identification of predictive and follow-up biomarkers in AIT. Here, we review the immunological mechanisms underlying AIT with a focus on MC desensitization and AIT-induced adverse reactions. Also, we discuss the identification of novel biomarkers with predictive potential that could improve the rational use of AIT.

Mechanisms of allergen-specific immunotherapy for allergic rhinitis and food allergies

Allergen-specific immunotherapy (AIT) is currently the only potential treatment for allergies including allergic rhinitis (AR) and food allergies (FA) that can modify the underlying course of the diseases. Although AIT has been performed for over a century, the precise and detailed mechanism for AIT is still unclear. Previous clinical trials have reported that successful AIT induces the reinstatement of tolerance against the specific allergen. In this review, we aim to provide an updated summary of the knowledge on the underlying mechanisms of IgE-mediated AR and FA as well as the immunological changes observed after AIT and discuss on how better understanding of these can lead to possible identification of biomarkers and novel strategies for AIT.

Decellularized Aortic Scaffold Alleviates H2O2-Induced Inflammation and Apoptosis in CD34+ Progenitor Cells While Driving Neovasculogenesis

Bone marrow-derived stem/progenitor cells have been utilized for cardiac or vascular repair after ischemic injury, but they are subject to apoptosis and immune rejection in the ischemic site. Multiple scaffolds were used as delivery tools to transplant stem/progenitor cells; however, these scaffolds did not show intrinsically antiapoptotic or anti-inflammatory properties. Decellularized aortic scaffolds that facilitate cell delivery and tissue repair were prepared by removing cells of patient-derived aortic tissues. Scanning electron microscopy (SEM) showed cells attached well to the scaffold after culturing for 5 days. Live/dead staining showed most seeded cells survived at day 7 on a decellularized aortic scaffold. Ki67 staining demonstrated that decellularized aortic scaffold promoted proliferation of bone marrow-derived CD34+ progenitor cells. Apoptosis of CD34+ progenitor cells induced by H₂O₂ at high concentration was significantly alleviated in the presence of decellularized aortic scaffolds, demonstrating a protective effect against oxidative stress-induced apoptosis. Furthermore, decellularized aortic scaffolds significantly reduced the expression of proinflammatory cytokines (IL-8, GM-CSF, MIP-1β, GRO-α, Entoxin, and GRO) concurrently with an increase in anti-inflammatory cytokines (IL-2 and TGF-β) released from CD34+ progenitor cells when exposed to H₂O₂ at low concentration. Finally, neovascularization was observed by H&E and immunohistochemical staining 14 days after the decellularized aortic scaffolds were subcutaneously implanted in nude mice. This preclinical study demonstrates that the use of a decellularized aortic scaffold possessing antiapoptotic and anti-inflammatory properties may represent a promising strategy for cardiovascular repair after ischemic injury.

[From a Ph.D. Thesis: Understanding the Past, Predicting the Future]

　Posey et al. have reported multiple molecular diagnoses in 4.5% of cases (101/2076) in which whole-exome sequencing was informative. Distinct disease phenotypes affect different organ systems, whereas overlapping disease phenotypes are more likely to be caused by two genes encoding proteins that interact within the same pathway. My research projects at the Niigata University of Pharmacy have investigated underlying mechanisms involved in human disease, including fatty acid metabolism, diabetic cardiomyopathy, atopic dermatitis, colitis, hepatitis, etc. Three students from abroad graduated this year from the Department of Clinical Pharmacology, Niigata University of Pharmacy and Applied Life Sciences. These students reported on treatments for heart disease, non-alcoholic steatohepatitis and atopic dermatitis, as well as the underlying mechanisms involved in each. The titles of these reports are "Study of the role of cardiac 14-3-3η protein in cardiac inflammation and adverse cardiac remodeling during heart failure in mice", "Non-alcoholic steatohepatitis: onset of mechanisms under diabetic background and treatment strategies" and "The role of HMGB1 and its cascade signaling pathway in atopic dermatitis". It can be concluded from these three theses that oxidative stress and inflammation are among the principal mechanisms underlying these diseases.

Mast Cells: Key Contributors to Cardiac Fibrosis

Historically, increased numbers of mast cells have been associated with fibrosis in numerous cardiac pathologies, implicating mast cells in the development of cardiac fibrosis. Subsequently, several approaches have been utilised to demonstrate a causal role for mast cells in animal models of cardiac fibrosis including mast cell stabilising compounds, rodents deficient in mast cells, and inhibition of the actions of mast cell-specific proteases such as chymase and tryptase. Whilst most evidence supports a pro-fibrotic role for mast cells, there is evidence that in some settings these cells can oppose fibrosis. A major gap in our current understanding of cardiac mast cell function is identification of the stimuli that activate these cells causing them to promote a pro-fibrotic environment. This review will present the evidence linking mast cells to cardiac fibrosis, as well as discuss the major questions that remain in understanding how mast cells contribute to cardiac fibrosis.

Natural products with anti-inflammatory and immunomodulatory activities against autoimmune myocarditis

Myocarditis is an inflammatory disease of the myocardium associated with immune dysfunction which may frequently lead to the development of dilated cardiomyopathy. Experimental autoimmune myocarditis is an animal model which mimics myocarditis in order to allow assessment of the therapeutic effects of different molecules on this disease. We aimed to review the inflammatory and immunological mechanisms involved in the pathogenesis of the myocarditis and finding natural products and phytochemicals with anti-myocarditis activities based on studies of cardiac myosin-induced experimental autoimmune myocarditis in rodents. A number of natural molecules (e.g. apigenin, berberine and quercetin) along with some plant extracts were found to be effective in alleviating experimental autoimmune myocarditis. Upregulation of Th1-type cytokines and elevation of the Th2-type cytokines (IL-4 and IL-10), mitigation of oxidative stress, modulation of mitogen-activated protein kinase signaling pathways and increasing Sarco-endoplasmic reticulum Ca²⁺-ATPase levels are among the most important anti-myocarditis mechanisms for the retrieved molecules and extracts. Interestingly, there are structural similarities between the anti-EAM compounds, suggesting the presence of similar pharmacophore and enzymatic targets for these molecules. Naturally occurring molecules discussed in the present article are potential anti-myocarditis drugs and future additional animal studies and clinical trials would shed more light on their effectiveness in the treatment of myocarditis and prevention of dilated cardiomyopathy.

Post-sensitization administration of non-digestible oligosaccharides and Bifidobacterium breve M-16V reduces allergic symptoms in mice

To support dietary management of severe cow's milk allergic infants, a synbiotic mixture of non-digestible oligosaccharides and Bifidobacterium breve M-16V (B. breve) was designed from source materials that are completely cow's milk-free. It was investigated whether this specific synbiotic concept can reduce an established food allergic response in a research model for hen's egg allergy. Mice were orally sensitized once a week for 5 weeks to ovalbumin (OVA) using cholera toxin (CT) as an adjuvant. Non-sensitized mice received CT in PBS only. Sensitized mice were fed a control diet or a diet enriched with short-chain- (scFOS) and long-chain fructo-oligosaccharides (lcFOS), B. breve or scFOSlcFOS + B. breve for 3 weeks starting after the last sensitization. Non-sensitized mice received the control diet. Anaphylactic shock symptoms, acute allergic skin responses and serum specific IgE, mMCP-1 and galectin-9 were measured upon OVA challenge. Activated Th2-, Th1-cells and regulatory T-cells were quantified in spleen and mesenteric lymph nodes (MLN) and cytokine profiles were analyzed. Short chain fatty acids (SCFA) were measured in ceacal samples. The acute allergic skin response was reduced in mice fed the scFOSlcFOS + B. breve diet compared to mice fed any of the other diets. A reduction in mast cell degranulation (mMCP-1) and anaphylactic shock symptoms was also observed in these mice. Unstimulated splenocyte cultures produced increased levels of IL10 and IFNg in mice fed the scFOSlcFOS + B. breve diet. Correspondingly, increased percentages of activated Th1 cells were observed in the spleen. Allergen-specific re-stimulation of splenocytes showed a decrease in IL5 production. In summary; post-sensitization administration of scFOSlcFOS + B. breve was effective in reducing allergic symptoms after allergen challenge. These effects coincided with changes in regulatory and effector T-cell subsets and increases in the SCFA propionic acid. These results suggest immune modulatory benefits of dietary intervention with a unique combination of scFOSlcFOS + B. breve in established food allergy. Whether these effects translate to human applications is subject for ongoing clinical studies.

VTX-1463, a novel TLR-8 agonist, attenuates nasal congestion after ragweed challenge in sensitized beagle dogs

VTX‐1463 is a selective toll‐like receptor (TLR) 8 agonist that activates a subset of innate immune cells to produce a unique cytokine profile. Delivery of VTX‐1463 via nasal spray may modulate the nasal response in allergic rhinitis. The aim of this study was to determine the effects of VTX‐1463 on the nasal response in a dog model of allergic rhinitis. Ragweed (RW)‐sensitized dogs were pretreated with increasing doses of VTX‐1463 1 day prior to RW challenge or with two doses (4 or 8 days and 1 day prior to RW). Changes in nasal cavity volume (NV) were determined by acoustic rhinometry and nasal lavage fluid was assessed for histamine, lipid mediators, and cellular infiltrates at sequential times following RW challenge. VTX‐1463 pretreatment significantly preserved NV during the acute response to RW challenge for all doses tested. The area under the curve (AUC) for NV over the 1.5 h assessment period in RW challenged vehicle controls averaged 51.5% (SEM: ±2.12%) of the baseline NV over all studies. A single 100 µg dose of VTX‐1463 given 1 day prior to RW yielded an AUC for NV of 69.3% (±6.59%) of baseline, while a 1000 µg dose administered twice (8 days and 1 day prior to RW) resulted in an AUC for NV of 85.4% (±4.74%, P < 0.05) of baseline. For a single 1000 µg VTX‐1463 dose 1 day prior to RW, multiple mediators produced by mast cells, including histamine, PGE2, PGD2, and cysteinyl LTs, were significantly reduced relative to the vehicle control. The selective TLR8 agonist, VTX‐1463, preserved NV in a dose‐dependent manner in the acute phase of a nasal allergic response. The therapeutic effect appears to result from attenuated mast cell mediator release. Modulating the local cytokine response via TLR8 agonism appears to have a therapeutic effect on the acute allergic nasal response.

Toxicological effect of TiO2 nanoparticle-induced myocarditis in mice

Currently, impacts of exposure to TiO2 nanoparticles (NPs) on the cardiovascular system are not well understood. The aim of this study was to investigate whether TiO2 NPs induce myocarditis and its underlying molecular mechanism in the cardiac inflammation in mice. Mice were exposed to TiO2 NPs for 6 months; biochemical parameters of serum and expression of Th1-related and Th2-related cytokines in the heart were investigated. The results showed that TiO2 NP exposure resulted in cardiac lesions coupling with pulmonary inflammation; increases of aspartate aminotransferase (AST), creatine kinase (CK), C-reaction protein (CRP), lactate dehydrogenase (LDH), alpha-hydroxybutyrate dehydrogenase (HBDH), adhesion molecule-1 (ICAM-1), and monocyte chemoattractant protein-1 (MCP-1) levels; and a reduction of nitric oxide (NOx) level in the serum. These were associated with increases of nuclear factor-κB (NF-κB), tumor necrosis factor-α (TNF-α), interleukin (IL)-4, IL-6, transforming growth factor-β (TGF-β), creatine kinase, CRP, adhesion molecule-1, and monocyte chemoattractant protein-1, interferon-γ (IFN-γ), signal transducers and activators of transcription (STAT)1, STAT3, or STAT6, GATA-binding domain-3, GATA-binding domain-4, endothelin-1 expression levels, and T-box expressed in T cells expression level that is the master regulator of pro-inflammatory cytokines and transcription factors in the heart. These findings imply that TiO2 NP exposure may increase the occurrence and development of cardiovascular diseases.

Small interfering RNA therapy against carbohydrate sulfotransferase 15 inhibits cardiac remodeling in rats with dilated cardiomyopathy

Carbohydrate sulfotransferase 15 (CHST15) is a sulfotransferase responsible for biosynthesis of chondroitin sulfate E (CS-E), which plays important roles in numerous biological events such as biosynthesis of proinflammatory cytokines. However, the effects of CHST15 siRNA in rats with chronic heart failure (CHF) after experimental autoimmune myocarditis (EAM) have not yet been investigated. CHF was elicited in Lewis rats by immunization with cardiac myosin, and after immunization, the rats were divided into two groups and treated with either CHST15 siRNA (2μg/week) or vehicle. Age matched normal rats without immunizations were also included in this study. After 7weeks of treatment, we investigated the effects of CHST15 siRNA on cardiac function, proinflammatory cytokines, and cardiac remodeling in EAM rats. Myocardial functional parameters measured by hemodynamic and echocardiographic studies were significantly improved by CHST15 siRNA treatment in rats with CHF compared with that of vehicle-treated CHF rats. CHST15 siRNA significantly reduced cardiac fibrosis, and hypertrophy and its marker molecules (left ventricular (LV) mRNA expressions of transforming growth factor beta1, collagens I and III, and atrial natriuretic peptide) compared with vehicle-treated CHF rats. CHF-induced increased myocardial mRNA expressions of proinflammatory cytokines [interleukin (IL)-6, IL-1β], monocyte chemoattractant protein-1, and matrix metalloproteinases (MMP-2 and -9), and CHST15 were also suppressed by the treatment with CHST15 siRNA. Western blotting study has confirmed the results obtained from mRNA analysis as CHST15 siRNA treated rats expressed reduced levels of inflammatory and cardiac remodeling marker proteins. Our results demonstrate for the first time, that CHST15 siRNA treatment significantly improved LV function and ameliorated the progression of cardiac remodeling in rats with CHF after EAM.

Disruption of histamine H2 receptor slows heart failure progression through reducing myocardial apoptosis and fibrosis

Histamine H2 receptor (H2R) blockade has been reported to be beneficial for patients with chronic heart failure (CHF), but the mechanisms involved are not entirely clear. In the present study, we assessed the influences of H2R disruption on left ventricular (LV) dysfunction and the mechanisms involved in mitochondrial dysfunction and calcineurin-mediated myocardial fibrosis. H2R-knockout mice and their wild-type littermates were subjected to transverse aortic constriction (TAC) or sham surgery. The influences of H2R activation or inactivation on mitochondrial function, apoptosis and fibrosis were evaluated in cultured neonatal rat cardiomyocytes and fibroblasts as well as in murine hearts. After 4 weeks, H2R-knockout mice had higher echocardiographic LV fractional shortening, a larger contractility index, a significantly lower LV end-diastolic pressure, and more importantly, markedly lower pulmonary congestion compared with the wild-type mice. Similar results were obtained in wild-type TAC mice treated with H2R blocker famotidine. Histological examinations showed a lower degree of cardiac fibrosis and apoptosis in H2R-knockout mice. H2R activation increased mitochondrial permeability and induced cell apoptosis in cultured cardiomyocytes, and also enhanced the protein expression of calcineurin, nuclear factor of activated T-cell and fibronectin in fibroblasts rather than in cardiomyocytes. These findings indicate that a lack of H2R generates resistance towards heart failure and the process is associated with the inhibition of cardiac fibrosis and apoptosis, adding to the rationale for using H2R blockers to treat patients with CHF.

Stress triggers coronary mast cells leading to cardiac events

OBJECTIVE

Stress precipitates and worsens not only asthma and atopic dermatitis but also acute coronary syndromes (ACSs), which are associated with coronary inflammation. Evidence linking stress to ACS was reviewed and indicated that activation of coronary mast cells (MCs) by stress, through corticotropin-releasing hormone (CRH) and other neuropeptides, contributes to coronary inflammation and coronary artery disease.

DATA SOURCES

PubMed was searched (2005-2013) for articles using the following keywords: allergies, anaphylaxis, anxiety, coronary arteries, coronary artery disease, C-reactive protein, cytokines, chymase, histamine, hypersensitivity, interleukin-6 (IL-6), inflammation, mast cells, myocardial ischemia, niacin, platelet-activating factor, rupture, spasm, statins, stress, treatment, tryptase, and uroctortin.

STUDY SELECTIONS

Articles were selected based on their relevance to how stress affects ACS and how it activates coronary MCs, leading to coronary hypersensitivity, inflammation, and coronary artery disease.

RESULTS

Stress can precipitate allergies and ACS. Stress stimulates MCs through the activation of high-affinity surface receptors for CRH, leading to a CRH-dependent increase in serum IL-6. Moreover, neurotensin secreted with CRH from peripheral nerves augments the effect of CRH and stimulates cardiac MCs to release IL-6, which is elevated in ACS and is an independent risk factor for myocardial ischemia. MCs also secrete CRH and uroctortin, which induces IL-6 release from cardiomyocytes. The presence of atherosclerosis increases the risk of cardiac MC activation owing to the stimulatory effect of lipoproteins and adipocytokines. Conditions such as Kounis syndrome, mastocytosis, and myalgic encephalopathy/chronic fatigue syndrome are particularly prone to coronary hypersensitivity reactions.

CONCLUSION

Inhibition of cardiac MCs may be a novel treatment approach.

CD25+ regulatory T cells transfer n-3 long chain polyunsaturated fatty acids-induced tolerance in mice allergic to cow's milk protein

BACKGROUND

Recently, we have shown that dietary long-chain n-3 polyunsaturated fatty acids (n-3 LCPUFA) largely prevent allergic sensitization in a murine model for cow's milk allergy. The aim of this study was to assess the contribution of regulatory T cells (Treg) in the prevention of food allergy by n-3 LCPUFA.

METHODS

C3H/HeOuJ female donor mice were fed a control or fish oil diet before and during oral sensitization with cow's milk protein whey. Acute allergic skin response (ASR), anaphylaxis, body temperature, serum immunoglobulins, and mouse mast cell protease-1 (mmcp-1) were assessed. Splenocytes of sham- or whey-sensitized donor mice fed either control or fish oil diet were adoptively transferred to naïve recipient mice. Recipient mice received a whole splenocyte suspension, splenocytes ex vivo depleted of CD25+ cells, or MACS-isolated CD4+ CD25+ Treg. Recipient mice were sham- or whey-sensitized and fed control diet.

RESULTS

The ASR as well as whey-specific IgE and whey-specific IgG1 levels were reduced in whey-sensitized donor mice fed the fish oil diet as compared to the control diet. Splenocytes of control-diet-fed whey-sensitized donors transferred immunologic memory. By contrast, splenocytes of fish-oil-fed whey-sensitized - but not sham-sensitized - donors transferred tolerance to recipients as shown by a reduction in ASR and serum mmcp-1, and depletion of CD25+ Treg abrogated this. Transfer of CD25+ Treg confirmed the involvement of Treg in the suppression of allergic sensitization.

CONCLUSIONS

CD25+ Treg are crucial in whey allergy prevention by n-3 LCPUFA.

Mast cell inhibition attenuates myocardial damage, adverse remodeling, and dysfunction during fulminant myocarditis in the rat

BACKGROUND

Myocarditis is a life-threatening heart disease characterized by myocardial inflammation, necrosis, and chronic fibrosis. While mast cell inhibition has been suggested to prevent fibrosis in rat myocarditis, little is known about its effectiveness in attenuating cardiac remodeling and dysfunction in myocarditis. Thus, we sought to test the hypothesis that mast cell inhibition will attenuate the inflammatory reaction and associated left ventricular (LV) remodeling and dysfunction after fulminant autoimmune myocarditis. Methods and

RESULTS

To induce experimental autoimmune myocarditis, we immunized 30 rats with porcine cardiac myosin (PCM) twice at a 7-day interval. On day 8 animals were randomized into treatment with either an intraperitoneal (IP) injection of 25mg/kg of cromolyn sodium (n = 13) or an equivalent volume (∼0.5 mL IP) of normal saline (n = 11). All animals were scanned by serial echocardiography studies before treatment (baseline echocardiogram) and after 20 days of cromolyn sodium (28 days after immunization). Furthermore, serial cardiac magnetic resonance was performed in a subgroup of 12 animals. After 20 days of treatment (28 days from first immunization), hearts were harvested for histopathological analysis. By echocardiography, cromolyn sodium prevented LV dilatation and attenuated LV dysfunction, compared with controls. Postmortem analysis of hearts showed that cromolyn sodium reduced myocardial fibrosis, as well as the number and size of cardiac mast cells in the inflamed myocardium, compared with controls.

CONCLUSIONS

Our study suggests that mast cell inhibition with cromolyn sodium attenuates adverse LV remodeling and dysfunction in myocarditis. This mechanism-based therapy is clinically relevant and could improve the outcome of patients at risk for inflammatory cardiomyopathy and heart failure.

Successful use of mRNA-nucleofection for overexpression of interleukin-10 in murine monocytes/macrophages for anti-inflammatory therapy in a murine model of autoimmune myocarditis

Background

Overexpression of interleukin-10 (IL-10) in murine CD11b⁺ monocytes/macrophages via GMP-adapted mRNA-nucleofection was expected to improve clinical outcome and reduce adverse side effects in autoimmune myocarditis. This study represents the proof of principle for a novel anti-inflammatory therapy using overexpression of IL-10 in murine monocytes/macrophages by mRNA-nucleofection for the treatment of autoimmune myocarditis.

Methods and Results

Autoimmune myocarditis was induced in A/J mice by subcutaneous immunization with troponin I. CD11b⁺ monocytes/macrophages were isolated from the peritoneum and IL-10 was overexpressed by mRNA-nucleofection. These cells were injected intravenously. Myocardial inflammation was assessed via histological and immunohistochemical examinations. Myocardial fibrosis was analyzed with Masson's trichrome staining. Antitroponin I antibodies were determined within the serum. Physical performance was evaluated using a running wheel and echocardiography. In vitro overexpression of IL-10 in CD11b⁺ monocytes/macrophages resulted in a 7-fold increased production of IL-10 (n=3). In vivo higher levels of IL-10 and less inflammation were detected within the myocardium of treated compared with control mice (n=4). IL-10–treated mice showed lower antitroponin I antibodies (n=10) and a better physical performance (n=10).

Conclusions

Application of IL-10–overexpressing CD11b⁺ monocytes/macrophages reduced inflammation and improved physical performance in a murine model of autoimmune myocarditis. Thus, the use of genetically modified monocytes/macrophages facilitated a targeted therapy of local inflammation and may reduce systemic side effects. Because the nucleofection technique is GMP adapted, an in vivo use in humans seems basically feasible and the transfer to other inflammatory diseases seems likely.

Systemic transplantation of allogenic fetal membrane-derived mesenchymal stem cells suppresses Th1 and Th17 T cell responses in experimental autoimmune myocarditis

We have reported that systemic administration of autologous bone marrow or allogenic fetal membrane (FM)-derived mesenchymal stem cells (MSCs) similarly attenuated myocardial injury in rats with experimental autoimmune myocarditis (EAM). Since rat EAM is a T-helper (Th) cell-mediated autoimmune disease, and recent evidence has indicated that both autologous and allogenic MSCs exert an immunosuppressive effect on Th cell activity, we focused on Th cell differentiation in allogenic FM-MSC administered EAM rats. EAM was induced in Lewis rats by injecting porcine cardiac myosin (day 0). Allogenic FM-MSCs, obtained from major histocompatibility complex mismatched ACI rats, were intravenously injected (5 × 10(5)cells/rat) on days 7, 10, or 14 (MSCd7, MSCd10, or MSCd14 groups, respectively). At day 21, echocardiography confirmed that reduced ejection fraction in the untreated EAM group (63 ± 2%) was significantly improved in the MSCd10 and MSCd14 groups (74 ± 1 and 75 ± 2%, respectively, P<0.01). CD68 immunostaining revealed that prominent macrophage infiltration in the myocardium of the EAM group (1466 ± 93 cells/mm(2)) was significantly decreased in the MSCd10 group (958 ± 139 cells/mm(2), P<0.05). To evaluate Th cell differentiation, we used flow cytometry to determine the percentage of interferon (IFN)-γ positive Th1 and interleukin (IL)-17 positive Th17 cells in peripheral CD4-positive Th cells. The percentage of Th1 cells at day 16 was significantly lower in the MSCd10 (1.3 ± 0.2%) and MSCd14 (1.6 ± 0.3%) groups compared to the EAM group (2.4 ± 0.3%, P<0.05), as was the percentage of Th17 cells in the MSCd10 group (1.9 ± 0.5%) compared to the EAM group (2.2 ± 0.9%, P<0.05). At day 21, infiltrating Th17 cells in myocardium were significantly decreased in the MSCd10 group (501 ± 132 cells/mm(2), P<0.05) compared to EAM (921 ± 109 cells/mm(2)). In addition, human CD4+ Th cells co-cultured with human FM-MSCs exhibited reduced Th1 and Th17 cell-differentiation and proliferation, with increased expression of immunosuppressive molecules including indoleamine 2,3-dioxygenase 2 and IL-6 in co-cultured FM-MSCs. These results suggest that intravenous administration of allogenic FM-MSCs ameliorates EAM via the suppression of Th1/Th17 immunity.

PKCβII inhibition attenuates myocardial infarction induced heart failure and is associated with a reduction of fibrosis and pro-inflammatory responses

Protein kinase C βII (PKCβII) levels increase in the myocardium of patients with end-stage heart failure (HF). Also targeted overexpression of PKCβII in the myocardium of mice leads to dilated cardiomyopathy associated with inflammation, fibrosis and myocardial dysfunction. These reports suggest a deleterious role of PKCβII in HF development. Using a post-myocardial infarction (MI) model of HF in rats, we determined the benefit of chronic inhibition of PKCβII on the progression of HF over a period of 6 weeks after the onset of symptoms and the cellular basis for these effects. Four weeks after MI, rats with HF signs that were treated for 6 weeks with the PKCβII selective inhibitor (βIIV5-3 conjugated to TAT(47-57) carrier peptide) (3 mg/kg/day) showed improved fractional shortening (from 21% to 35%) compared to control (TAT(47-57) carrier peptide alone). Formalin-fixed mid-ventricle tissue sections stained with picrosirius red, haematoxylin and eosin and toluidine blue dyes exhibited a 150% decrease in collagen deposition, a two-fold decrease in inflammation and a 30% reduction in mast cell degranulation, respectively, in rat hearts treated with the selective PKCβII inhibitor. Further, a 90% decrease in active TGFβ1 and a significant reduction in SMAD2/3 phosphorylation indicated that the selective inhibition of PKCβII attenuates cardiac remodelling mediated by the TGF-SMAD signalling pathway. Therefore, sustained selective inhibition of PKCβII in a post-MI HF rat model improves cardiac function and is associated with inhibition of pathological myocardial remodelling.

Curcumin ameliorates cardiac inflammation in rats with autoimmune myocarditis

Curcumin is a natural polyphenolic compound abundant in the rhizome of the perennial herb turmeric, Curcuma longa. It is commonly used as a dietary spice and coloring agent in cooking, and is used anecdotally as an herb in traditional Indian and Chinese medicine. It has been reported that curcumin has the potential to protect against cardiac inflammation through suppression of GATA-4 and nuclear factor-κB (NF-κB); however, no study to date has addressed the effect of curcumin on experimental autoimmune myocarditis (EAM) in rats. In this study, 8-week-old male Lewis rats were immunized with cardiac myosin to induce EAM. They were then divided randomly into a treatment or vehicle group and orally administrated curcumin (50 mg/kg/d) or 1% gum arabic, respectively, for 3 weeks after myosin injection. We performed hemodynamic, echocardiographic, hematoxylin and eosin staining, mast cell staining and Western blotting studies to evaluate the protective effect of curcumin in the acute phase of EAM. Cardiac functional parameters measured by hemodynamic and echocardiographic studies were significantly improved by curcumin treatment. Furthermore, curcumin reduced the heart weight-to-body weight ratio, area of inflammatory lesions and the myocardial protein level of NF-κB, interleukin (IL)-1β, tumor necrosis factor (TNF)-α and GATA-4. Our results indicate that curcumin has the potential to protect against cardiac inflammation through suppression of IL-1β, TNF-α, GATA-4 and NF-κB expresses, and may provide a novel therapeutic strategy for autoimmune myocarditis.

Modulation of endoplasmic reticulum stress and cardiomyocyte apoptosis by mulberry leaf diet in experimental autoimmune myocarditis rats

Mulberry is commonly used as silkworm diet and an alternative medicine in Japan and China, has recently reported to contain many antioxidative flavanoid compounds and having the free radical scavenging effects. Antioxidants reduce cardiac oxidative stress and attenuate cardiac dysfunction in animals with pacing-induced congestive heart failure. Hence we investigated the cardioprotective effect of mulberry leaf powder in rats with experimental autoimmune myocarditis. Eight-week-old Lewis rats immunized with cardiac myosin were fed with either normal chow or a diet containing 5% mulberry leaf powder and were examined on day 21. ML significantly decreased oxidative stress, myocyte apoptosis, cellular infiltration, cardiac fibrosis, mast cell density, myocardial levels of sarco/endo-plasmic reticulum Ca²⁺ ATPase2, p22^phox, receptor for advanced glycation end products, phospho-p38 mitogen activated protein kinase, phospho-c-Jun NH₂-terminal protein kinase, glucose regulated protein78, caspase12 and osteopontin levels in EAM rats. These results may suggest that mulberry diet can preserve the cardiac function in experimental autoimmune myocarditis by modulating oxidative stress induced MAPK activation and further afford protection against endoplasmic reticulum stress mediated apoptosis.

Immunological mechanisms of allergen-specific immunotherapy

The studies on the mechanisms of specific immunotherapy (SIT) point out its targets that decide on the efficacy of SIT and hence might be used for its further improvement. Several mechanisms have been proposed to explain the beneficial effects of immunotherapy. The knowledge of the mechanisms underlying allergic diseases and curative treatment possibilities has experienced exciting advances over the last three decades. Studies in several clinical trials in allergen-SIT have demonstrated that the induction of a tolerant state against allergens in many ways represents a key step in the development of a healthy immune response against allergens. Several cellular and molecular mechanisms have been demonstrated: allergen-specific suppressive capacities of both inducible subsets of CD4(+) CD25(+) forkhead box P3(+) T-regulatory and IL-10-secreting type 1 T-regulatory cells increase in peripheral blood; suppression of eosinophils, mast cells, and basophils; Ab isotype change from IgE to IgG4. This review aims at the better understanding of the observed immunological changes associated with allergen SIT.

Functionalized scaffold-mediated interleukin 10 gene delivery significantly improves survival rates of stem cells in vivo

While stem cell transplantation could potentially treat a variety of disorders, clinical studies have not yet demonstrated conclusive benefits. This may be partly because transplanted stem cells have low survival rates, potentially due to host inflammation. The system described herein used two different gene therapy techniques to improve retention of rat mesenchymal stem cells. In the first, stem cells were transfected with interleukin-10 (IL-10) before being loaded into a collagen scaffold. In the second, unmodified stem cells were loaded into a collagen scaffold along with polymer-complexed IL-10 plasmids. The scaffolds were surgically implanted into the dorsum of syngeneic rats. At each endpoint, the scaffolds were explanted and cell retention, IL-10 level and inflammatory response were quantified. All treatment groups had statistically significant increases in cell retention after 7 days, but the group treated with 2 µg of IL-10 polyplexes had a significant improvement even at 21 days. This cell retention was associated with increased IL-10 and decreased levels of proinflammatory cytokines and apoptosis. The primary effect on the inflammatory response appeared to be on macrophage differentiation, encouraging the regulatory phenotype over the cytotoxic lineage. Improving cell survival may be an important step toward realization of the therapeutic potential of stem cells.

Mechanisms of allergen-specific immunotherapy

Allergen-specific immunotherapy has been used for 100 years as a desensitizing therapy for allergic diseases and represents the potentially curative and specific method of treatment. The mechanisms of action of allergen-specific immunotherapy include the very early desensitization effects, modulation of T-and B-cell responses and related antibody isotypes, and migration of eosinophils, basophils, and mast cells to tissues, as well as release of their mediators. Regulatory T (Treg) cells have been identified as key regulators of immunologic processes in peripheral tolerance to allergens. Skewing of allergen-specific effector T cells to a regulatory phenotype appears as a key event in the development of healthy immune response to allergens and successful outcome in patients undergoing allergen-specific immunotherapy. Naturally occurring forkhead box protein 3-positive CD4(+)CD25(+) Treg cells and inducible T(R)1 cells contribute to the control of allergen-specific immune responses in several major ways, which can be summarized as suppression of dendritic cells that support the generation of effector T cells; suppression of effector T(H)1, T(H)2, and T(H)17 cells; suppression of allergen-specific IgE and induction of IgG4; suppression of mast cells, basophils, and eosinophils; and suppression of effector T-cell migration to tissues. New strategies for immune intervention will likely include targeting of the molecular mechanisms of allergen tolerance and reciprocal regulation of effector and Treg cell subsets.

Non-viral gene therapy for myocardial engineering

Despite significant advances in surgical and pharmacological techniques, myocardial infarction (MI) remains the main cause of morbidity in the developed world because no remedy has been found for the regeneration of infarcted myocardium. Once the blood supply to the area in question is interrupted, the inflammatory cascade, among other mechanisms, results in the damaged tissue becoming a scar. The goals of cardiac gene therapy are essentially to minimize damage, to promote regeneration, or some combination thereof. While the vector is, in theory, less important than the gene being delivered, the choice of vector can have a significant impact. Viral therapies can have very high transfection efficiencies, but disadvantages include immunogenicity, retroviral-mediated insertional mutagenesis, and the expense and difficulty of manufacture. For these reasons, researchers have focused on non-viral gene therapy as an alternative. In this review, naked plasmid delivery, or the delivery of complexed plasmids, and cell-mediated gene delivery to the myocardium will be reviewed. Pre-clinical and clinical trials in the cardiac tissue will form the core of the discussion. While unmodified stem cells are sometimes considered therapeutic vectors on the basis of paracrine mechanisms of action basic understanding is limited. Thus, only genetically modified cells will be discussed as cell-mediated gene therapy.

Rectal administration of tranilast ameliorated acute colitis in mice through increased expression of heme oxygenase-1

Mast cells play a key role in the pathophysiology of inflammatory bowel disease (IBD). Tranilast, a mast cell stabilizer, has been empirically used for IBD in Japan, but its precise role in the treatment of IBD is largely unknown. To investigate the role of tranilast for the treatment of IBD, tranilast was administered intrarectally to mice with dextran sulfate sodium (DSS)-induced colitis. Tranilast ameliorated DSS colitis clinically and pathologically, as demonstrated by decreased number and degranulation of mast cells in the colon. mRNA expression was increased for tumor necrosis factor-alpha, interferon-gamma and interleukin (IL)-6, and decreased for IL-10 in the colon of DSS colitis mice. In contrast, tranilast markedly decreased expression of mRNAs for the pro-inflammatory cytokines, and increased that of the anti-inflammatory cytokines. Moreover, tranilast increased heme oxygenase (HO)-1 expression on colonic epithelial cells as well as on colon-infiltrating cells of DSS colitis. In conclusion, tranilast ameliorated DSS colitis by regulating mast cell degranulation, decreasing inflammatory cytokines and increasing anti-inflammatory cytokines. Tranilast might exert these effects partly through enhanced HO-1 expression in the colon, suggesting a potential adjunctive therapy for IBD.

Therapeutic manipulation of immune tolerance in allergic disease

Immune tolerance - the adaptation of the immune system to external antigens or allergens - might be therapeutically manipulated to restore normal immunity in conditions such as allergy, asthma and autoimmune diseases. The field of allergen-specific immunotherapy is experiencing exciting and novel developments for the treatment of allergic and autoimmune diseases, and recent insights into the reciprocal regulation and counter-balance between different T-cell subsets is foreseen to facilitate new strategies for immunointervention. This Review highlights current knowledge of immunomodulatory therapies for the manipulation of immune tolerance and highlights recent approaches to improve allergen-specific immunotherapy for the treatment of allergic diseases.

Immune tolerance in allergy

Research on the mechanisms of immune regulation in allergy and asthma has shown substantial progress in recent years and has led to a variety of allergen-specific therapeutic and preventive approaches. Studies on the area of allergen-specific immunotherapy (allergen-SIT) have provided substantial knowledge on the mechanisms of allergic disease with novel developments for treatment and prevention. Several studies have demonstrated that increased numbers and the activation of allergen-specific T regulatory cells correlate with successful allergen-SIT. Particularly, targeting of the molecular mechanisms of immune tolerance and reciprocal regulation of effector and regulatory T-cell subsets are foreseen for the development of new strategies for immune intervention. This review focuses on current knowledge of immune tolerance to allergens in healthy immune response to allergens and allergen-SIT.

Loss of SOCS7 in mice results in severe cutaneous disease and increased mast cell activation

The Suppressor of Cytokine Signaling (SOCS) protein family plays a central role in the negative regulation of cytokine action and has been implicated in the development of atopic diseases. Lack of SOCS7 is associated with severe skin disease in mice. We sought to explore the underlying mechanisms resulting in this phenotype. Skin samples were analyzed and serum immunoglobulin production was measured. Cytokine production by bone marrow derived mast cells was determined by ELISA. Mast cell thymic stromal lymphopoietin (TSLP) production was assessed by quantitative real-time PCR. Data obtained revealed that Socs7(-/-) mice have increased serum IgE and IgG(1) production and exhibit an increased mast cell infiltrate, as well as un-provoked mast cell degranulation in the dermis as compared to controls. In vitro, bone marrow derived mast cells from Socs7(-/-) mice are hyperactive to IgE-mediated stimuli, with elevated production of pro-inflammatory cytokines (IL-13, IL-6, TNF-alpha). Further, activated Socs7(-/-) bone marrow derived mast cells have increased IL-7Ralpha transcript, which is part of the heterodimeric receptor for TSLP. Finally, lack of SOCS7 was accompanied by an increase in TSLP mRNA and protein production by mast cells following FcepsilonRI aggregation. These data implicate SOCS7 in the modulation of allergic inflammation and demonstrate that SOCS7 is involved in the regulation of TSLP signaling in mast cells.

Cardiac mast cells mediate left ventricular fibrosis in the hypertensive rat heart

Correlative data suggest that cardiac mast cells are a component of the inflammatory response that is important to hypertension-induced adverse myocardial remodeling. However, a causal relationship has not been established. We hypothesized that adverse myocardial remodeling would be inhibited by preventing the release of mast cell products that may interact with fibroblasts and other inflammatory cells. Eight-week-old male spontaneously hypertensive rats were treated for 12 weeks with the mast cell stabilizing compound nedocromil (30 mg/kg per day). Age-matched Wistar-Kyoto rats served as controls. Nedocromil prevented left ventricular fibrosis in the spontaneously hypertensive rat independent of hypertrophy and blood pressure, despite cardiac mast cell density being elevated. The mast cell protease tryptase was elevated in the spontaneously hypertensive rat myocardium and was normalized by nedocromil. Treatment of isolated adult spontaneously hypertensive rat cardiac fibroblasts with tryptase induced collagen synthesis and proliferation, suggesting this as a possible mechanism of mast cell-mediated fibrosis. In addition, nedocromil prevented macrophage infiltration into the ventricle. The inflammatory cytokines interferon-gamma and interleukin (IL)-4 were increased in the spontaneously hypertensive rat and normalized by nedocromil, whereas IL-6 and IL-10 were decreased in the spontaneously hypertensive rat, with nedocromil treatment normalizing IL-6 and increasing IL-10 above the control. These results demonstrate for the first time a causal relationship between mast cell activation and fibrosis in the hypertensive heart. Furthermore, these results identify several mechanisms, including tryptase, inflammatory cell recruitment, and cytokine regulation, by which mast cells may mediate hypertension-induced left ventricular fibrosis.

Mechanisms and treatment of allergic disease in the big picture of regulatory T cells

Various populations of regulatory T (Treg) cells have been shown to play a central role in the maintenance of peripheral homeostasis and the establishment of controlled immune responses. Their identification as key regulators of immunologic processes in peripheral tolerance to allergens has opened an important era in the prevention and treatment of allergic diseases. Both naturally occurring CD4+CD25+ Treg cells and inducible populations of allergen-specific, IL-10-secreting Treg type 1 (T(R)1) cells inhibit allergen-specific effector cells in experimental models. Skewing of allergen-specific effector T cells to a regulatory phenotype appears to be a key event in the development of healthy immune response to allergens and successful outcome in allergen-specific immunotherapy. Forkhead box protein 3-positive CD4+CD25+ Treg cells and T(R)1 cells contribute to the control of allergen-specific immune responses in several major ways, which can be summarized as suppression of dendritic cells that support the generation of effector T cells; suppression of effector T(H)1, T(H)2, and T(H)17 cells; suppression of allergen-specific IgE and induction of IgG4; suppression of mast cells, basophils, and eosinophils; interaction with resident tissue cells and remodeling; and suppression of effector T-cell migration to tissues. Current strategies for drug development and allergen-specific immunotherapy exploit these observations, with the potential for preventive therapies and cure for allergic diseases.

Mast cells and epsilonPKC: a role in cardiac remodeling in hypertension-induced heart failure

Heart failure (HF) is a chronic syndrome in which pathological cardiac remodeling is an integral part of the disease and mast cell (MC) degranulation-derived mediators have been suggested to play a role in its progression. Protein kinase C (PKC) signaling is a key event in the signal transduction pathway of MC degranulation. We recently found that inhibition of epsilonPKC slows down the progression of hypertension-induced HF in salt-sensitive Dahl rats fed a high-salt diet. We therefore determined whether epsilonPKC inhibition affects MC degranulation in this model. Six week-old male Dahl rats were fed with a high-salt diet to induce systemic hypertension, which resulted in concentric left ventricular hypertrophy at the age of 11 weeks, followed by myocardial dilatation and HF at the age of 17 weeks. We administered epsilonV1-2, an epsilonPKC-selective inhibitor peptide (3 mg/kg/day), deltaV1-1, a deltaPKC-selective inhibitor peptide (3 mg/kg/day), TAT (negative control; at equimolar concentration; 1.6 mg/kg/day) or olmesartan (angiotensin receptor blocker [ARB] as a positive control; 3 mg/kg/day) between 11 weeks and 17 weeks. Treatment with epsilonV1-2 attenuated cardiac MC degranulation without affecting MC density, myocardial fibrosis, microvessel patency, vascular thickening and cardiac inflammation in comparison to TAT- or deltaV1-1-treatment. Treatment with ARB also attenuated MC degranulation and cardiac remodeling, but to a lesser extent when compared to epsilonV1-2. Finally, epsilonV1-2 treatment inhibited MC degranulation in isolated peritoneal MCs. Together, our data suggest that epsilonPKC inhibition attenuates pathological remodeling in hypertension-induced HF, at least in part, by preventing cardiac MC degranulation.

Adeno-associated virus vector-mediated systemic interleukin-10 expression ameliorates hypertensive organ damage in Dahl salt-sensitive rats

BACKGROUND

Inflammation plays an important role in the pathogenesis of hypertension and hypertensive organ damage. Interleukin (IL)-10, a pleiotropic anti-inflammatory cytokine, exerts vasculoprotective effects in many animal models. In the present study, we examined the preventive effects of adeno-associated virus (AAV) vector-mediated sustained IL-10 expression against hypertensive heart disease and renal dysfunction in Dahl salt-sensitive rats.

METHODS

We injected the rats intramuscularly with an AAV type 1-based vector encoding rat IL-10 or enhanced green fluorescent protein (EGFP) at 5 weeks of age; subsequently, the rats were fed a high-sodium diet from 6 weeks of age.

RESULTS

Sustained IL-10 expression significantly improved survival rate of Dahl salt-sensitive rats compared with EGFP expression (62.5% versus 0%, p < 0.001); it also caused 26.0% reduction in systolic blood pressure at 15 weeks (p < 0.0001). Echocardiography exhibited a 22.0% reduction in hypertrophy (p < 0.0001) and a 26.3% improvement in fractional shortening (p < 0.0001) of the rat left ventricle in the IL-10 group compared to the EGFP group. IL-10 expression also caused a 21.7% decrease in the heart weight/body weight index and cardiac atrial natriuretic peptide levels. Histopathological studies revealed that IL-10 decreased inflammatory cell infiltration, fibrosis, and transforming growth factor-beta(1) levels in the failing heart. Furthermore, IL-10 expression significantly reduced urine protein excretion with increased glomerular filtration rates.

CONCLUSIONS

This is the first study to demonstrate that the anti-inflammatory cytokine IL-10 has a significant anti-hypertensive effect. AAV vector-mediated IL-10 expression potentially prevents the progression of refractory hypertension and hypertensive organ damage in humans.

IL-10 suppresses mast cell IgE receptor expression and signaling in vitro and in vivo

Mast cells are known for their roles in allergy, asthma, systemic anaphylaxis, and inflammatory disease. IL-10 can regulate inflammatory responses and may serve as a natural regulator of mast cell function. We examined the effects of IL-10 on in vitro-cultured mouse and human mast cells, and evaluated the effects of IL-10 on FcepsilonRI in vivo using mouse models. IgE receptor signaling events were also assessed in the presence or absence of IL-10. IL-10 inhibited mouse mast cell FcepsilonRI expression in vitro through a Stat3-dependent process. This down-regulation was consistent in mice tested in vivo, and also on cultured human mast cells. IL-10 diminished expression of the signaling molecules Syk, Fyn, Akt, and Stat5, which could explain its ability to inhibit IgE-mediated activation. Studies of passive systemic anaphylaxis in IL-10-transgenic mice showed that IL-10 overexpression reduced the IgE-mediated anaphylactic response. These data suggest an important regulatory role for IL-10 in dampening mast cell FcepsilonRI expression and function. IL-10 may hence serve as a mediator of mast cell homeostasis, preventing excessive activation and the development of chronic inflammation.

Chymase inhibition reduces the progression to heart failure after autoimmune myocarditis in rats

Chymase has been known as a local angiotensin II-generating enzyme in the cardiovascular system in dogs, monkeys, hamsters, and humans; however, recently it was reported that chymase also has various other functions. Therefore, we decided to examine whether the inhibition of chymase improves disease conditions associated with the pathophysiology of dilated cardiomyopathy in rats and its possible mechanism of action as rat chymase is unable to produce angiotensin II. We examined the effect of TY-51469, a novel chymase inhibitor (0.1 mg/kg/day [group CYI-0.1, n = 15] and 1 mg/kg/day [group CYI-1, n = 15]), in myosin-immunized postmyocarditis rats. Another group of myosin-immunized rats was treated with vehicle (group V, n = 15). Age-matched normal rats without immunization (group N, n = 10) were also included in the study. After 4 weeks of treatment, we evaluated cardiac function; area of fibrosis; fibrogenesis; levels of transforming growth factor (TGF)-beta1 and collagen III; hypertrophy and its marker, atrial natriuretic peptide (ANP); and mast cell activity. Survival rate and myocardial functions improved dose-dependently with chymase inhibitor treatment after myosin immunization. A reduction in the percent area of myocardial fibrosis, fibrogenesis, myocardial hypertrophy, and mast cell activity along with a reduction in TGF-beta1, collagen III, and ANP levels in the myocardium were noted in postmyocarditis rats that received chymase inhibitor treatment. The treatment also decreased myocardial aldosterone synthase levels in those animals. Inhibition of chymase reduces the pathogenesis of postmyocarditis dilated cardiomyopathy and progression to heart failure by preventing the pathological remodeling and residual inflammation in rats.

Mechanisms of allergen-specific immunotherapy

Allergen-specific immunotherapy (SIT) has been used for almost a century as a desensitizing therapy for allergic diseases and represents the only curative and specific method of treatment. Administration of appropriate concentrations of allergen extracts has been shown to be reproducibly effective when patients are carefully selected. The mechanisms by which allergen-SIT has its effects include the modulation of T-cell and B-cell responses and related antibody isotypes as well as effector cells of allergic inflammation, such as eosinophils, basophils, and mast cells. The balance between allergen-specific T-regulatory (Treg) and T(H)2 cells appears to be decisive in the development of allergic and healthy immune responses against allergens. Treg cells consistently represent the dominant subset specific for common environmental allergens in sensitized healthy individuals. In contrast, there is a high frequency of allergen-specific T(H)2 cells in patients with allergy. The induction of a tolerant state in peripheral T cells represents an essential step in allergen-SIT. Peripheral T-cell tolerance is characterized mainly by generation of allergen-specific Treg cells leading to suppressed T-cell proliferation and T(H)1 and T(H)2 cytokine responses against the allergen. This is accompanied by a significant increase in allergen-specific IgG(4), and also IgG(1) and IgA, and a decrease in IgE in the late stage of the disease. In addition, decreased tissue infiltration of mast cells and eosinophils and their mediator release including circulating basophils takes place. Current understanding of mechanisms of allergen-SIT, particularly the role of Treg cells in peripheral tolerance, may enable novel treatment strategies.

Erythropoietin attenuates the development of experimental autoimmune myocarditis

OBJECTIVE

Erythropoietin (EPO) has been shown to not only have cardioprotective effects but also attenuate autoimmune diseases. In the present study, we investigated the effect of EPO on cardiac inflammation and function, inflammatory cell infiltration, and cytokine expression in a rat model of experimental autoimmune myocarditis (EAM).

METHODS AND RESULTS

Male Lewis rats (6-8 weeks old) were immunized on day 0 with porcine cardiac myosin to establish EAM. The rats were subcutaneously administered either vehicle (saline) or human recombinant EPO (6,000 U/kg, 3 days/week) from day 0 to 20, and they were evaluated on day 21. In the EPO group, the inflammation area and heart weight/body weight ratio were significantly attenuated as compared with those in the vehicle group. Blood pressure and cardiac function were also improved in the EPO group. Immunohistochemistry revealed that EPO decreased the infiltration of macrophages and CD4 T cells, and degranulated mast cells in the myocardium. Real-time RT-PCR analysis demonstrated that inflammatory cytokine expression in the myocardium and lymphocytes was suppressed in the EPO group. However, in vitro experiments showed that EPO had no effect on antigen-induced proliferation and cytokine expression in lymphocytes.

CONCLUSION

EPO attenuates inflammatory cell infiltration and cytokine expression, and it improves cardiac function and reduces cardiac inflammation in EAM. This beneficial effect of EPO is unlikely to arise from a direct anti-inflammatory action on lymphocytes. These findings suggest the therapeutic potential of EPO for the treatment of myocarditis.

Sustained nitric oxide synthesis contributes to immunopathology in ongoing myocarditis attributable to interleukin-10 disorders

Ongoing coxsackievirus B3 (CVB3) myocarditis is characterized by persistence of viral RNA and chronic inflammation primarily mediated by macrophages and T cells. Activated macrophages produce anti-viral effector molecules comprising reactive nitrogen intermediates; however, reactive nitrogen intermediates also contribute to host tissue damage. Controlled activation of macrophages depends on interferon (IFN)-gamma and interleukin (IL)-10. To evaluate mechanisms involved in CVB3-induced pathogenesis of myocarditis, we determined the relationship of inducible nitric-oxide synthase (iNOS) mRNA expression with IFN-gamma and IL-10 secretion during CVB3 infection in different mouse strains. We found in susceptible A.BY/SnJ mice that develop ongoing myocarditis, a low and delayed IFN-gamma secretion and highly diminished IL-10 production compared with resistant C57BL/6 mice. Consequently, iNOS mRNA synthesis was delayed but clearly prolonged in susceptible mice. IL-10 gene-deficient mice confirmed the regulatory role of IL-10 in the outcome of CVB3 myocarditis. These mice did not establish a persistent cardiac infection and revealed IFN-gamma secretion kinetics similar to resistant mice but showed a slightly elongated cardiac iNOS mRNA expression resulting in extended myocarditis. We conclude that coordinated secretion of IFN-gamma and IL-10 is crucial for the effective resolution of CVB3 myocarditis. Moreover, lack of regulatory IL-10 leads to uncontrolled iNOS mRNA production, thus contributing to ongoing myocardial injury.

Heart- and skeletal muscle-specific antigens recognized by trichinellosis patient sera

The heart can be seriously affected in human trichinellosis, and cardiac involvement can cause death. Experimental infections in rats have suggested the possible participation of immunopathological processes. The aim of the present paper was to investigate the possible presence in trichinellosis patient sera of antibodies recognizing host tissues and particularly the myocardium. Nineteen sera from late period trichinellosis patients, who acquired infection in the Poznan region (Poland), were tested by immunoblot on extracts from normal rat or human heart ventricle wall, spleen, placenta, kidney and skeletal muscle. Patients' sera recognized several antigens that were not recognized by normal sera. On rat and human heart ventricle wall, a high proportion of sera (42%) reacted with a protein of 68 kDa (P < 0.05 compared to normal sera). The reactivity with this antigen, however, was not significantly different in patients with or without cardiac involvement. When sera were tested on skeletal muscle we found that 47% reacted with a protein of 27 kDa and 53% reacted with a protein of 41 kDa (P < 0.05 for both proteins, compared with normal sera). The reactivity against the 68 kDa antigen and against the 27 and 41 kDa skeletal muscle antigens was not observed on kidney, placenta and spleen extracts. Moreover, very few bands were observed on these tissues as compared to heart and skeletal muscle tissues, thus suggesting a high tissue specificity of the reactivity of trichinellosis sera. In conclusion, this study identifies organ-specific autoantibodies in trichinellosis patient sera, their role in the pathogenesis of cardiac involvement being still unclear.

Immunotherapy of hypersensitivity to hymenoptera venom

Insect sting allergy is a common condition with a risk of life-threatening anaphylaxis. After a severe reaction, the fear of being restung can significantly reduce quality of life. Venom immunotherapy (VIT) is a highly effective treatment of the underlying type I-sensitisation. This review addresses the mechanisms of immune modulation by VIT and outlines current clinical application. Although highly effective in the majority of patients, VIT fails in a few individuals. It can also cause systemic allergic side effects, restricting its application to physicians trained in the treatment of anaphylaxis. This review discusses several new strategies to overcome these problems, which are presently a promising focus of research. These include the use of new adjuvants, of recombinant and genetically engineered venom allergens, as well as vaccination with peptides.