Inhibition of experimental autoimmune myocarditis: peripheral deletion of TcR Vβ 8.1, 8.2+ CD4+ T cells in TLR-4 deficient mice

ω-3 fatty acid alleviates virus-induced myocardial injury by regulating TLR4 and TLR3 expression

The specific pathogenesis of viral-induced myocardial injury is unclear. TLR regulation plays an important role in virus-induced myocardial injury. The therapeutic effect and possible mechanism of omega-3 fatty acids in patients with viral-induced myocardial injury must be investigated. The study population was randomly divided into three groups: a healthy control group (n = 50); general treatment group (n = 40); and general treatment with ω-3 polyunsaturated fatty acid group (n = 36). We detected the mRNA levels of TLR3 and TLR4, downstream signal pathway proteins, inflammatory factors, oxidative stress markers, and myocardial enzymes in patients and healthy controls. ω-3 fatty acid therapy in patients with virus-induced myocardial injury significantly regulates the expression of TLR3 and TLR4 and their downstream signal protein, increases antioxidant expression, reduces the secretion of inflammatory factors, alleviates myocardial injury, and improves cardiac function. This provides a new strategy to treat virus-induced myocardial injury.

[Glucosides of chaenomeles speciosa attenuate ischemia/reperfusion-induced brain injury by regulating NF-κB P65/TNF-α in mouse model]

OBJECTIVE

To investigate the effect and mechanism of glucosides of chaenomeles speciosa (GCS) on ischemia/reperfusion-induced brain injury in mouse model.

METHODS

Fifty 8-week C57BL/C mice were randomly divided into five groups with 10 in each group:sham group, model group, GCS 30 mg/kg group, GCS 60 mg/kg group and GCS 90 mg/kg group, and the GCS was administrated by gavage (once a day) for 14 d. HE staining was performed to investigate the cell morphology; the Zea-Longa scores were measured for neurological activity; TUNEL staining was performed to investigate the cell apoptosis; ELISA was used to detected the oxidative stress and inflammation; Western Blot was performed to investigate the key pathway and neurological functional molecules.

RESULTS

Compared with the sham group, the brain tissues in model group were seriously damaged, presenting severe cell apoptosis, oxidative stress and inflammation, associated with increased NF-κB P65 and TNF-α levels as well as decreased myelin associate glycoprotein (MAG) and oligodendrocyte-myelin glycoprotein (OMgp)levels (all P<0.01). Compared with the model group, the brain tissues in GCS groups were ameliorated, and cell apoptosis, oxidative stress and inflammation were inhibited, associated with decreased NF-κB P65 and TNF-α levels as well as increased MAG and OMgp levels (all P<0.01), which were more markedly in GCS 60 mg/kg group.

CONCLUSIONS

GCS can inhibit the NF-κB P65 and TNF-α, reduce the oxidative stress and inflammation, decrease the cell apoptosis in mouse ischemia/reperfusion-induced brain injury model, and 60 mg/kg GCS may be the optimal dose.

The importance of the Non Obese Diabetic (NOD) mouse model in autoimmune diabetes

Type 1 Diabetes (T1D) is an autoimmune disease characterized by the pancreatic infiltration of immune cells resulting in T cell-mediated destruction of the insulin-producing beta cells. The successes of the Non-Obese Diabetic (NOD) mouse model have come in multiple forms including identifying key genetic and environmental risk factors e.g. Idd loci and effects of microorganisms including the gut microbiota, respectively, and how they may contribute to disease susceptibility and pathogenesis. Furthermore, the NOD model also provides insights into the roles of the innate immune cells as well as the B cells in contributing to the T cell-mediated disease. Unlike many autoimmune disease models, the NOD mouse develops spontaneous disease and has many similarities to human T1D. Through exploiting these similarities many targets have been identified for immune-intervention strategies. Although many of these immunotherapies did not have a significant impact on human T1D, they have been shown to be effective in the NOD mouse in early stage disease, which is not equivalent to trials in newly-diagnosed patients with diabetes. However, the continued development of humanized NOD mice would enable further clinical developments, bringing T1D research to a new translational level. Therefore, it is the aim of this review to discuss the importance of the NOD model in identifying the roles of the innate immune system and the interaction with the gut microbiota in modifying diabetes susceptibility. In addition, the role of the B cells will also be discussed with new insights gained through B cell depletion experiments and the impact on translational developments. Finally, this review will also discuss the future of the NOD mouse and the development of humanized NOD mice, providing novel insights into human T1D.

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

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

Periodontal bacteria aggravate experimental autoimmune myocarditis in mice

Periodontitis is one of the most common infections in humans. Recently, published reports assert that periodontitis is associated with cardiovascular disease. Although it is said that viral, bacterial infections and autoimmune diseases may be the cause of myocarditis, the pathogenesis of it remains unclear. The aim of this study was to investigate the influence of a periodontal pathogen on experimental autoimmune myocarditis (EAM). Porphyromonas gingivalis (P.g.), PBS as a control, were injected into the mice. Histopathological and immunohistochemical analyses were performed. We examined heart mRNA levels using quantitative RT-PCR. The anti-P.g. IgG antibody level in plasma samples of the P.g.-injected group significantly increased compared with the PBS-injected group. Histopathological analysis detected that the myocarditis-affected areas and the fibrotic area in the P.g.-injected EAM group significantly increased compared with the PBS-injected EAM group (P < 0.05). Immunohistochemical analysis detected that more CD11b-positive cells were shown in the heart of the P.g.-injected EAM group compared with the PBS EAM-injected group (P < 0.05). Hearts from the P.g.-injected EAM group showed significantly increased expression of monocyte chemoattractant protein-1, IFN-γ, and matrix metalloproteinase-9 (MMP-9) mRNA compared with the hearts from the PBS-injected EAM group (P < 0.05). On day 7, serum levels of IL-6 were significantly enhanced in the P.g.-injected EAM group compared with the PBS-injected EAM group (P < 0.05). These results showed that P.g. injection could deteriorate EAM in mice through CD11b-positive cells, cytokines, and MMP-9 expression.

Toll-like receptors promote inflammation in idiopathic inflammatory myopathies

The roles of Toll-like receptors (TLRs) and their myeloid differentiation response gene 88 (MyD88)-dependent and MyD88-independent signaling cascade particularly with regard to the pathogenesis and regulation of immune responses in idiopathic inflammatory myopathies are unclear. We investigated these pathways in muscle biopsies from 5 cases each of polymyositis, inclusion body myositis, dermatomyositis, vasculitis-associated interstitial myositis, and noninflammatory neurogenic atrophy. Toll-like receptor 2, TLR4, TLR9, and MyD88 mRNA transcripts and protein expression were increased in all subtypes of idiopathic inflammatory myopathies. Upregulation of MyD88 was associated with increased mRNA levels of interferon-γ, interleukin 12p40, and interleukin 17, suggesting NF-κB activation via the MyD88-dependent pathway in early stages. The costimulatory molecules CD80 and CD86 were expressed on inflammatory infiltrates in idiopathic inflammatory myopathies and may additionally contribute to activation of the MyD88-independent pathway, leading to nuclear factor-κB activation in late stages. Our data suggest that nuclear factor-κB activation via both the MyD88-dependent and the MyD88-independent pathways contributes to the proinflammatory milieu in idiopathic inflammatory myopathies.

Different toll-like receptor stimuli have a profound impact on cytokines required to break tolerance and induce autoimmunity

Although toll-like receptor (TLR) signals are critical for promoting antigen presenting cell maturation, it remains unclear how stimulation via different TLRs influence dendritic cell (DC) function and the subsequent adaptive response in vivo. Furthermore, the relationship between TLR-induced cytokine production by DCs and the consequences on the induction of a functional immune response is not clear. We have established a murine model to examine whether TLR3 or TLR4 mediated DC maturation has an impact on the cytokines required to break tolerance and induce T-cell-mediated autoimmunity. Our study demonstrates that IL-12 is not absolutely required for the induction of a CD8 T-cell-mediated tissue specific immune response, but rather the requirement for IL-12 is determined by the stimuli used to mature the DCs. Furthermore, we found that IFNα is a critical pathogenic component of the cytokine milieu that circumvents the requirement for IL-12 in the induction of autoimmunity. These studies illustrate how different TLR stimuli have an impact on DC function and the induction of immunity.

Toll-like receptors as potential therapeutic targets in cardiac dysfunction

INTRODUCTION

The innate immune system can detect the highly conserved, relatively invariant structural motifs of pathogens. The most important innate immune receptors, Toll-like receptors (TLRs), represent a first line of defense against infectious pathogens, and play a pivotal role in initiating and shaping innate and adaptive immune responses. TLRs are not only expressed in immune cells, but also in cardiovascular cells. In addition to their role in response to microbial infections, evidence suggests that TLRs can also recognize endogenous ligands and may play a role in mediating cardiomyocyte cell death and survival after non-infectious injury.

AREAS COVERED

TLRs could be a link between cardiovascular diseases and the immune system. Experimentally, there is good evidence that TLR activation contributes to development and progression of both acute cardiac injury and chronic heart failure. The role of TLRs in myocardial ischemia-reperfusion, remodeling, septic cardiomyoparthy, autoimmune- and viral myocarditis, anthracycline-induced cardiomyopathy and cardiac hypertrophy, in basic as well as clinical science are discussed.

EXPERT OPINION

Evidence, mainly from animal experiments, indicates that TLRs contribute to all of the myocardial disease states reviewed in this paper. However, the relevance of TLRs as therapeutic targets remains to be defined as clinical data is sparse.

The role of TLR2, TRL3, TRL4, and TRL9 signaling in the pathogenesis of autoimmune disease in a retinal autoimmunity model

PURPOSE

Induction of tissue-specific experimental autoimmune diseases involves the use of complete Freund adjuvant containing Mycobacterium tuberculosis, whose recognition by the innate immune system depends on Toll-like receptors (TLRs) that signal through the adaptor molecule MyD88. The authors' previous study showed that MyD88(-/-) mice, but not TLR2(-/-), TLR4(-/-), or TLR9(-/-) mice, were resistant to experimental autoimmune uveitis (EAU).

METHODS

The EAU induction in mice deficient in TLR3 or mice double deficient in TLR2+4, TLR2+9, and TLR4+9 was examined and the role of the TLR agonists in the adjuvant effect involved in the induction of EAU was assessed.

RESULTS

TLR3-deficient and TLR2+4, TLR2+9, and TLR4+9 double-deficient mice were as susceptible to EAU as their control littermates. However, in mice immunized with a low-dose EAU regimen, TLR4 agonist lipopolysaccharide (LPS) enhanced EAU scores, delayed-type hypersensitivity responses, and antigen-specific T-cell proliferation. Antigen-specific IL-17 and IFN-gamma production by T lymphocytes was markedly increased in the LPS-treated group. The effects of LPS on EAU were abolished by treatment with an LPS deactivator polymyxin B. Inclusion of agonists for TLR2, TRL3, or TRL9 in immunization also enhanced EAU scores.

CONCLUSIONS

These results suggest that signaling of TLR2, TRL3, TRL4, and TRL9 is highly redundant in the adjuvant effect needed to induce EAU and that diverse microbial infections may contribute to the pathogenesis of diseases such as uveitis.

The worldwide gradient of autoimmune conditions

Among the numerous consequences of globalization, the dissemination of scientific research allows real-time comparisons of clinical and basic experimental data between different geographical areas. As a result, the field of geoepidemiology is now vigorously supported by multiple lines of evidence. This special issue of Autoimmunity Reviews is dedicated to the 2010 International Congress on Autoimmunity and aims to provide a state-of-the-art representation of what is currently known in the field of geoepidemiology for autoimmune diseases. The obvious implications of these observations is a role for environmental factors. We will herein review selected publications from prominent scientific journals to provide the bases to understand some of the lines of evidence proposed in the subsequent papers of this comprehensive volume. The ultimate goal is thus to define whether geoepidemiology should be considered a new challenge for autoimmunologists.

Incidence and nature of infectious disease in patients treated with anti-TNF agents

Tumor necrosis factor alpha (TNF-alpha) inhibitors offer a targeted therapeutic strategy that contrasts with the nonspecific immunosuppressive agents traditionally used to treat most inflammatory diseases. These biologic agents have had a significant impact in ameliorating the signs and symptoms of inflammatory rheumatoid disease and improving patient function. From the onset of clinical trials, a central concern of cytokine blockade has been a potential increase in susceptibility to infections. Not surprisingly, a variety of infections have been reported in association with the use of TNF-alpha inhibitor agents. In particular, there is evidence suggesting an increased rate of granulomatous infections in patients treated with monoclonal TNF-alpha inhibitors. This review provides the incidence and nature of infections in patients treated with TNF-alpha inhibitor agents and reminds the clinician of the required vigilance in monitoring patients.

Autoimmune myocarditis: past, present and future

Heart failure has become an increasingly prevalent disorder with considerable morbidity and mortality. While many causal mechanisms such as inherited cardiomyopathies, ischemic cardiomyopathy or muscular overload are easily identified in clinical practice, the molecular mechanisms that determine the progression of heart failure or ventricular remodelling are largely unknown. Autoimmune responses and inflammation are involved in the pathogenesis of many cardiovascular diseases. There is compelling evidence that inflammatory mechanisms may contribute to progressive heart failure. Thus, myocardial infiltration of lymphocytes and mononuclear cells, increased expression of pro-inflammatory chemokines and cytokines and circulating autoantibodies are frequently observed in myocarditis and dilated cardiomyopathy. In this review we give an overview on myocarditis and describe why diagnosis and treatment of myocarditis in the clinic can be difficult. We present current animal models and describe possible experimental approaches to improve diagnosis. Finally, we give an outlook on possible drug targets by describing the latest findings in the animal models focussing on chemokines and cytokines, T cell responses and interactions, tolerance induction and the development of autoantibodies.

Oral tolerization with cardiac myosin peptide (614-629) ameliorates experimental autoimmune myocarditis: role of STAT 6 genes in BALB/CJ mice

INTRODUCTION

Experimental autoimmune myocarditis (EAM) is mediated by myocardial infiltration by myosin-specific T cells secreting inflammatory cytokines.

MATERIALS AND METHODS

To clarify the role of cytokines in EAM, we compared STAT 6-deficient ((-/-)) with STAT 4(-/-) and wild-type (BALB/CJ) mice following immunization with cardiac myosin peptide (614-629).

RESULTS

Wild-type mice developed severe disease with a small increase in severity in STAT 6(-/-) mice, while STAT 4(-/-) mice were resistant to EAM. STAT 6(-/-) mice had increased splenocyte proliferation and INF-gamma production versus wild type, while STAT 4(-/-) mice had decreased proliferation and INF-gamma. Following oral administration of myosin (614-629), tolerization was induced in wild-type mice evidenced by amelioration of myocarditis and up-regulation of IL-4. Adoptive transfer of splenocytes from orally tolerized mice resulted in inhibition of disease in STAT 6(-/-) mice.

CONCLUSION

These results demonstrate that oral tolerization ameliorates EAM in BALB/CJ mice and indicate a down-regulatory role for STAT 6 genes.