C protein-induced myocarditis and subsequent dilated cardiomyopathy: rescue from death and prevention of dilated cardiomyopathy by chemokine receptor DNA therapy

QiShenYiQi pill improves the reparative myocardial fibrosis by regulating autophagy

QiShenYiQi pill (QSYQ), a traditional Chinese medicine, is well known for improving the myocardial remodelling, but the dose‐effect relationship of its intervention in the reparative myocardial fibrosis is still unclear. We investigated the effect of QSYQ on the reparative myocardial fibrosis in cardiac myosin‐induced rats and explored its mechanism of action by regulating autophagy. The results indicated that QSYQ increased LVEF and LVFS, and decreased the LVEDD, LVESD, HMI, LVMI, myocardial inflammation histology score, and collagen volume fraction in a dose‐dependent manner. In addition, QSYQ declined the number of autophagosomes, down‐regulated the expression of myocardial Beclin‐1 and LC3B, up‐regulated the expression of myocardial p62 and increased the ratios of myocardial p‐PI3K/PI3K, p‐Akt/Akt and p‐mTOR/mTOR. We provided evidence for that QSYQ could inhibit excessive myocardial autophagy by regulating the PI3K/Akt‐mTOR pathway and can be a potential therapeutic approach in treating the cardiovascular diseases such as myocarditis and dilated cardiomyopathy.

Biomimetic collagen biomaterial induces in situ lung regeneration by forming functional alveolar

In situ restoration of severely damaged lung remains difficult due to its limited regeneration capacity after injury. Artificial lung scaffolds are emerging as potential substitutes, but it is still a challenge to reconstruct lung regeneration microenvironment in scaffold after lung resection injury. Here, a 3D biomimetic porous collagen scaffold with similar structure characteristics as lung is fabricated, and a novel collagen binding hepatocyte growth factor (CBD-HGF) is tethered on the collagen scaffold for maintaining the biomimetic function of HGF to improve the lung regeneration microenvironment. The biomimetic scaffold was implanted into the operative region of a rat partial lung resection model. The results revealed that vascular endothelial cells and endogenous alveolar stem cells entered the scaffold at the early stage of regeneration. At the later stage, inflammation and fibrosis were attenuated, the microvascular and functional alveolar-like structures were formed, and the general morphology of the injured lung was restored. Taken together, the functional 3D biomimetic collagen scaffold facilitates recovery of the injured lung, alveolar regeneration, and angiogenesis after acute lung injury. Particularly, this is the first study of lung regeneration in vivo guided by biomimetic collagen scaffold materials, which supports the concept that tissue engineering is an effective strategy for alveolar regeneration.

Cardiac Myosin Binding Protein-C Autoantibodies are Potential Early Indicators of Cardiac Dysfunction and Patient Outcome in Acute Coronary Syndrome

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ACS remains a leading cause of death worldwide.

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cMyBP-C-AAbs were detected in ACS patients' sera upon arrival to the emergency department.

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The presence of cMyBP-C-AAbs was negatively associated with cardiovascular function and positively associated with the degree of myocardial injury as determined by circulating levels of serum proteins in ACS patients.

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The development of novel indicators to predict infarction severity and cardiovascular function following ischemic injury may provide early treatment recommendations for ACS patients to limit myocardial damage.

The degradation and release of cardiac myosin binding protein-C (cMyBP-C) upon cardiac damage may stimulate an inflammatory response and autoantibody (AAb) production. We determined whether the presence of cMyBP-C-AAbs associated with adverse cardiac function in cardiovascular disease patients. Importantly, cMyBP-C-AAbs were significantly detected in acute coronary syndrome patient sera upon arrival to the emergency department, particularly in ST-segment elevation myocardial infarction patients. Patients positive for cMyBP-C-AAbs had reduced left ventricular ejection fraction and elevated levels of clinical biomarkers of myocardial infarction. We conclude that cMyBP-C-AAbs may serve as early predictive indicators of deteriorating cardiac function and patient outcome in acute coronary syndrome patients prior to the infarction.

Effect and Mechanism of QiShenYiQi Pill on Experimental Autoimmune Myocarditis Rats

Background

To observe the effect of QiShenYiQi pill (QSYQ) on experimental autoimmune myocarditis rats, and to explore its mechanism of action.

Material/methods

Lewis rats underwent the injection of myocardial myosin mixed with Freund’s complete adjuvant were randomized into 3 groups: model, valsartan, and QSYQ groups. Rats injected with phosphate-buffered saline (PBS) mixed with Freund’s complete adjuvant were used as the control group. Rats were euthanized at 4 and 8 weeks, and we weighed rat body mass, heart mass, and left ventricular mass. Myocardium sections were stained with hematoxylin and eosin (H&E) and Masson trichrome. Myocardial TGF-β1 and CTGF protein expression was detected by immunohistochemistry, and myocardial TGF-β1 and CTGF mRNA expression was detected by real-time qPCR.

Results

QSYQ reduced HMI and LVMI, as well as the histological score of hearts and CVF, which further decreased over time, and its effect was significantly greater than that of valsartan at 4 and 8 weeks. After 4 weeks, QSYQ inhibited the protein and mRNA expression of TGF-β1 and CTGF, and its effect on lowering CTGF was significantly greater than that of valsartan. In addition, after 8 weeks, QSYQ also inhibited the protein and mRNA expression of CTGF, whereas there was no significant difference in the expression of myocardial TGF-β1.

Conclusions

This study provides evidence that QSYQ can improve cardiac remodeling of experimental autoimmune myocarditis rats. It also effectively improved the degree of myocardial fibrosis, which is related to the mechanism of regulation of TGF-β1 CTGF.

Circulating chemerin levels elevated in dilated cardiomyopathy patients with overt heart failure

BACKGROUND

Recent evidence demonstrated that the circulating concentrations of adipokine are related to the presence of heart failure secondary to ischemic heart disease and dilated cardiomyopathy (DCM). However, the plasma concentrations of chemerin in patients with DCM have yet to be investigated.

METHODS

The present study enrolled 109 DCM patients with typical symptoms of heart failure and 60 healthy controls and measured plasma concentrations of chemerin, IL-6 and TNF-α using enzyme-linked immunosorbent assay. Left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF) were measured using a GE ViVid E7 ultrasonography machine.

RESULTS

Plasma chemerin, IL-6 and TNF-α concentrations were significantly higher in DCM patients compared to the control group. A correlation analysis revealed that plasma chemerin concentrations were positively correlated with the concentrations of IL-6 (R=0.270, P=0.004), TNF-α (R=0.302, P=0.001), C-reactive protein (CRP) (R=0.256, P=0.004), N-terminal pro-brain natriuretic peptide (NT-proBNP) (R=0.386, P=0.000), and LVEDD (R=0.212, P=0.027) but negatively correlated with LVEF (R=-0.543, P=0.000). Furthermore, chemerin (OR 1.102, 95% CI 1.052 to 1.153; p=0.000) was independently associated with the presence of DCM before NT-proBNP was added in the multivariable regression model.

CONCLUSIONS

The results indicate that chemerin is a novel biomarker of DCM.

Surviving the infarct: A profile of cardiac myosin binding protein-C pathogenicity, diagnostic utility, and proteomics in the ischemic myocardium

Cardiac myosin binding protein-C (cMyBP-C) is a regulatory protein of the contractile apparatus within the cardiac sarcomere. Ischemic injury to the heart during myocardial infarction (MI) results in the cleavage of cMyBP-C in a phosphorylation-dependent manner and release of an N-terminal fragment (C0C1f) into the circulation. C0C1f has been shown to be pathogenic within cardiac tissue, leading to the development of heart failure. Based on its high levels and early release into the circulation post-MI, C0C1f may serve as a novel biomarker for diagnosing MI more effectively than current clinically used biomarkers. Over time, circulating C0C1f could trigger an autoimmune response leading to myocarditis and progressive cardiac dysfunction. Given the importance of cMyBP-C phosphorylation state in the context of proteolytic cleavage and release into the circulation post-MI, understanding the posttranslational modifications (PTMs) of cMyBP-C would help in further elucidating the role of this protein in health and disease. Accordingly, recent studies have implemented the latest proteomics approaches to define the PTMs of cMyBP-C. The use of such proteomics assays may provide accurate quantitation of the levels of cMyBP-C in the circulation following MI, which could, in turn, demonstrate the efficacy of using plasma cMyBP-C as a cardiac-specific early biomarker of MI. In this review, we define the pathogenic and potential immunogenic effects of C0C1f on cardiac function in the post-MI heart. We also discuss the most advanced proteomics approaches now used to determine cMyBP-C PTMs with the aim of validating C0C1f as an early biomarker of MI.

Fractalkine depresses cardiomyocyte contractility

Background

Our laboratory reported that male mice with cardiomyocyte-selective knockout of the prostaglandin E₂ EP4 receptor sub-type (EP4 KO) exhibit reduced cardiac function. Gene array on left ventricles (LV) showed increased fractalkine, a chemokine implicated in heart failure. We therefore hypothesized that fractalkine is regulated by PGE₂ and contributes to depressed contractility via alterations in intracellular calcium.

Methods

Fractalkine was measured in LV of 28–32 week old male EP4 KO and wild type controls (WT) by ELISA and the effect of PGE₂ on fractalkine secretion was measured in cultured neonatal cardiomyocytes and fibroblasts. The effect of fractalkine on contractility and intracellular calcium was determined in Fura-2 AM-loaded, electrical field-paced cardiomyocytes. Cardiomyocytes (AVM) from male C57Bl/6 mice were treated with fractalkine and responses measured under basal conditions and after isoproterenol (Iso) stimulation.

Results

LV fractalkine was increased in EP4 KO mice but surprisingly, PGE₂ regulated fractalkine secretion only in fibroblasts. Fractalkine treatment of AVM decreased both the speed of contraction and relaxation under basal conditions and after Iso stimulation. Despite reducing contractility after Iso stimulation, fractalkine increased the Ca²⁺ transient amplitude but decreased phosphorylation of cardiac troponin I, suggesting direct effects on the contractile machinery.

Conclusions

Fractalkine depresses myocyte contractility by mechanisms downstream of intracellular calcium.

Role of various proteases in cardiac remodeling and progression of heart failure

It is believed that cardiac remodeling due to geometric and structural changes is a major mechanism for the progression of heart failure in different pathologies including hypertension, hypertrophic cardiomyopathy, dilated cardiomyopathy, diabetic cardiomyopathy, and myocardial infarction. Increases in the activities of proteolytic enzymes such as matrix metalloproteinases, calpains, cathepsins, and caspases contribute to the process of cardiac remodeling. In addition to modifying the extracellular matrix, both matrix metalloproteinases and cathepsins have been shown to affect the activities of subcellular organelles in cardiomyocytes. The activation of calpains and caspases has been identified to induce subcellular remodeling in failing hearts. Proteolytic activities associated with different proteins including caspases, calpain, and the ubiquitin-proteasome system have been shown to be involved in cardiomyocyte apoptosis, which is an integral part of cardiac remodeling. This article discusses and compares how the activities of various proteases are involved in different cardiac abnormalities with respect to alterations in apoptotic pathways, cardiac remodeling, and cardiac dysfunction. An imbalance appears to occur between the activities of some proteases and their endogenous inhibitors in various types of hypertrophied and failing hearts, and this is likely to further accentuate subcellular remodeling and cardiac dysfunction. The importance of inhibiting the activities of both extracellular and intracellular proteases specific to distinct etiologies, in attenuating cardiac remodeling and apoptosis as well as biochemical changes of subcellular organelles, in heart failure has been emphasized. It is suggested that combination therapy to inhibit different proteases may prove useful for the treatment of heart failure.

Characterization of fibrosis-promoting factors and siRNA-mediated therapies in C-protein-induced experimental autoimmune myocarditis

Due to poor proliferation abilities of cardiomyocytes, the repair process in the heart after insults is often associated with fibrosis formation. In this study, we characterized inflammation and/or fibrosis-related molecules in the heart with experimental autoimmune carditis. Immunohistochemical examinations reveled that expression of tenascin-C (TNC), matrix metalloproteinase-9 (MMP-9), transforming growth factorβ1 (TGF-β1), connective tissue growth factor (CTGF) and α smooth muscle cell actin (αSMA) peaked at 2 weeks post-immunization but only TGF-β1 expression was sustained at 8 weeks. Administration of siRNAs for MMP-2 (siMMP-2) and for MMP-9 (siMMP-9) alone did not modulate inflammation and fibrosis. In contrast, simultaneous administration of siMMP-2 and siMMP-9 significantly reduced inflammation and fibrosis. Of note, siRNA treatment for TGF-β1, which is an anti-inflammatory cytokine, increased inflammation and decreased fibrosis. These findings suggest that in case of diseases characterized by initial inflammation and subsequent fibrosis, immunotherapies should target inflammation, not fibrosis, because the latter therapies exacerbate inflammation.

Role of MCP-1 in cardiovascular disease: molecular mechanisms and clinical implications

Many of the major diseases, including cardiovascular disease, are widely recognized as inflammatory diseases. MCP-1 (monocyte chemotactic protein-1) plays a critical role in the development of cardiovascular diseases. MCP-1, by its chemotactic activity, causes diapedesis of monocytes from the lumen to the subendothelial space where they become foam cells, initiating fatty streak formation that leads to atherosclerotic plaque formation. Inflammatory macrophages probably play a role in plaque rupture and the resulting ischaemic episode as well as restenosis after angioplasty. There is strong evidence that MCP-1 plays a major role in myocarditis, ischaemia/reperfusion injury in the heart and in transplant rejection. MCP-1 also plays a role in cardiac repair and manifests protective effects under certain conditions. Such protective effects may be due to the induction of protective ER (endoplasmic reticulum) stress chaperones by MCP-1. Under sustained ER stress caused by chronic exposure to MCP-1, the protection would break down resulting in the development of heart failure. MCP-1 is also involved in ischaemic angiogenesis. The recent advances in our understanding of the molecular mechanisms that might be involved in the roles that MCP-1 plays in cardiovascular disease are reviewed. The gene expression changes induced by the signalling events triggered by MCP-1 binding to its receptor include the induction of a novel zinc-finger protein called MCPIP (MCP-1-induced protein), which plays critical roles in the development of the pathophysiology caused by MCP-1 production. The role of the MCP-1/CCR2 (CC chemokine receptor 2) system in diabetes, which is a major risk factor for cardiovascular diseases, is also reviewed briefly. MCP-1/CCR2- and/or MCPIP-targeted therapeutic approaches to intervene in inflammatory diseases, including cardiovascular diseases, may be feasible.

Characterization of CD8-positive macrophages infiltrating the central nervous system of rats with chronic autoimmune encephalomyelitis

CD8+ macrophages appear in the central nervous system (CNS) under various pathological conditions such as trauma and ischemia. Furthermore, macrophages expressing CD8 were found in CNS lesions of chronic, but not acute, experimental autoimmune encephalomyelitis (EAE). To further characterize cells with this phenotype, we examined CD8+ macrophages/monocytes in the CNS and peripheral organs during the course of acute and chronic EAE that had been induced by immunization of rats with myelin basic protein and myelin oligodendrocyte glycoprotein, respectively. Counting CD8+ macrophages in CNS lesions revealed that their numbers increased reaching about 60% of total infiltrating macrophages in chronic EAE, while CD8+ macrophages remained less than 5% throughout the course of acute EAE. Unexpectedly, however, higher abundance of CD8+ monocytes/macrophages in the peripheral blood was found in both acute and chronic EAE. Real-time polymerase chain reaction analysis revealed no significant difference in the levels of chemokines and chemokine receptors of blood CD8+ monocytes between acute and chronic EAE. mRNA expression of perforin, a cytotoxic substance, was up-regulated in CD8+ monocytes compared with that of CD8- monocytes in both acute and chronic EAE. These findings suggest that activated CD8+ macrophages may play a cytotoxic role in chronic EAE lesions and that cells other than CD8+ monocytes/macrophages determined the difference in CNS pathology between acute and chronic EAE. Analysis of CD8+ monocytes/macrophages may provide useful information to permit further dissect the pathomechanisms of multiple sclerosis and to develop effective immunotherapies against autoimmune diseases in the CNS.

Nonviral DNA vaccination augments microglial phagocytosis of beta-amyloid deposits as a major clearance pathway in an Alzheimer disease mouse model

Immunotherapies markedly reduce beta-amyloid (Abeta) burden and reverse behavioral impairment in mouse models of Alzheimer disease. We previously showed that new Abeta DNA vaccines reduced Abeta deposits in Alzheimer disease model mice without detectable side effects. Although they are effective, the mechanisms of Abeta reduction by the DNA vaccines remain to be elucidated. Here, we analyzed vaccinated and control Alzheimer disease model mice from 4 months to 15 months of age to assess which of several proposed mechanisms may underlie the beneficial effects of this vaccination. Immunohistochemical analysis revealed that activated microglial numbers increased significantly in the brains of vaccinated mice after DNA vaccination both around Abeta plaques and in areas remote from them. Microglia in treated mice phagocytosed Abeta debris more frequently than they did in untreated mice. Although microglia had an activated morphological phenotype, they did not produce significant amounts of tumor necrosis factor. Amyloid plaque immunoreactivity and Abeta concentrations in plasma increased slightly in vaccinated mice compared with controls at 9 but not at 15 months of age. Collectively, these data suggest that phagocytosis of Abeta deposits by microglia plays a central role in Abeta reduction after DNA vaccination.

Recombinant cardiac myosin fragment induces experimental autoimmune myocarditis via activation of Th1 and Th17 immunity

The specificity and function of T helper (Th) immune responses underlying the induction, progression, and resolution of experimental autoimmune myocarditis (EAM) in A/J mice are unclear. Published data suggest involvement of both Th1 and Th2 responses in EAM; however, the previous inability to assess antigen-specific in vivo and in vitro T-cell responses in cardiac myosin-immunized animals has confounded our understanding of this important model of autoimmune myocarditis. The goal of our study was to develop an alternative model of EAM based on a recombinant fragment of cardiac myosin, in hopes that the recombinant protein will permit measurement of functional T-cell responses that is not possible with purified native protein. A/J mice immunized with a recombinant fragment of cardiac myosin spanning amino acids 1074-1646, termed Myo4, developed severe myocarditis characterized by cardiac hypertrophy, massive mononuclear cell infiltration and fibrosis, three weeks post-immunization. The mice also developed an IgG1 dominant humoral immune response specific for both Myo4 and purified cardiac myosin. The in vitro stimulation of splenocytes harvested from Myo4-immunized animals with Myo4 resulted in cellular proliferation with preferential production of the Th1- and Th17-associated cytokines, IFN-gamma, IL-17, and IL-6, respectively. Production of IL-4 was negligible by comparison. This study describes a new model of EAM, inducible by immunization with a specific fragment of cardiac myosin, from which antigen-specific analyses reveal an importance for both Th1 and Th17 immunity.

Chagas heart disease pathogenesis: one mechanism or many?

Chagas heart disease (CHD), caused by the protozoan parasite Trypanosoma cruzi, is the leading cause of infectious myocarditis in the world. The etiology of CHD is unclear and multiple mechanisms have been proposed to explain the pathogenesis of the disease. This review describes the proposed mechanisms of CHD pathogenesis and evaluates the historical significance and evidence supporting each. Although the majority of CHD-related pathologies are currently attributed to parasite persistence in the myocardium and autoimmunity, there is strong evidence that CHD develops as a result of additive and even synergistic effects of several distinct mechanisms rather than one factor.

Blood dendritic cell levels and phenotypic characteristics in relation to etiology of end-stage heart failure: implications for dilated cardiomyopathy

BACKGROUND

Dysregulation of dendritic cell (DC) mediated immune responses towards auto-antigens, is considered an important feature in the maintenance of experimentally induced heart failure (HF). In order to evaluate the role of blood DCs in cardiomyopathies of different origins, we examined myeloid (mDC) and plasmacytoid (pDC) subset levels and maturation characteristics, according to HF severity and etiology in humans.

METHODS

Absolute numbers of mDCs and pDCs in 12 New York Heart Association (NYHA) class-II, 28 NYHA class III-IV HF patients and 18 healthy controls, were studied by 4-colour whole blood flow cytometry.

RESULTS

End-stage (NYHA III-IV) HF patients had comparable circulating DC subset levels to NYHA-II patients and controls. However, within the NYHA III-IV group total DC levels in patients with non-ischemic dilated cardiomyopathy (DCM) were higher (P<0.001) than in patients with coronary artery disease (CAD), hypertrophic cardiomyopathy (HCM) or other HF etiology. This was due to a significant increase of primarily mDCs (P<0.0001) and to a lesser extent of pDCs (P<0.05) in idiopathic DCM patients, independent of systolic or diastolic cardiac dysfunction. Maturation marker CD83 and lymphoid homing chemokine receptor CCR7 surface expression was enhanced only on mDCs, but not pDCs from DCM patients (P<0.05), compared to patients with CAD, HCM or other underlying cardiac pathophysiology.

CONCLUSIONS

Total blood DC levels in end-stage HF are elevated in patients with DCM. Whole blood DC characterisation may lead to new insights into the pathophysiology of idiopathic DCM in humans.

Differential effects of decoy chemokine (7ND) gene therapy on acute, biphasic and chronic autoimmune encephalomyelitis: implication for pathomechanisms of lesion formation

Multiple sclerosis (MS) exhibits several clinical subtypes such as the relapsing-remitting (RR) and secondary progressive (SP) forms. In accordance with this, formation of demyelinating plaques in the central nervous system (CNS) occurs by different mechanisms. In the present study, we induced acute, biphasic and chronic (RR or SP) EAE in rats and examined the effects of decoy chemokine (7ND) gene therapy, which inhibits the migration of macrophages, to address the above issue. Interestingly, it was demonstrated that the clinical signs of acute EAE and the first attack of biphasic EAE were minimally affected, whereas chronic EAE and the relapse of biphasic EAE were completely suppressed with 7ND treatment. In the CNS, the number of infiltrating macrophages was reduced in all the stages of the three types of EAE. These findings suggest that in acute EAE and in the first attack of biphasic EAE, where anti-macrophage migration therapy was almost ineffective, pathogenic T cells are mainly involved in lesion formation. In contrast, the relapse of biphasic EAE and chronic EAE macrophages play a major role in the disease process. Thus, the mechanisms of lesion formation are not uniform and immunotherapy should be performed on the basis of information about the pathomechanisms of autoimmune diseases.

Characterization of pathogenic T cells and autoantibodies in C-protein-induced autoimmune polymyositis

Although autoimmune processes may take place in human polymyositis, little is known with regard to its pathogenesis due to the lack of appropriate animal models. In the present study, we developed experimental autoimmune myositis (EAM) in Lewis rats by immunization with recombinant skeletal C-protein and examined the role of pathogenic T cells and autoantibodies. Using recombinant proteins and synthetic peptides, we demonstrated that skeletal C-protein Fragment 2 (SC2) has the strongest myositis-inducing ability and that myositis-inducing epitope(s) reside within the residues 334-363 of SC2 (SC2P3). However, immunization with SC2P3 induced only mild EAM compared with SC2 immunization. Characterization of T cells and antisera revealed that SC2P3 and SC2P7 contain the B cell epitope, while the T cell epitope resides in SC2P5. Furthermore, anti-SC2, but not anti-SC2P3, antisera contained antibodies against the conformational epitope(s) in the SC2 molecule. However, SC2P3 or SC2P5 immunization plus anti-SC2 antibody transfer aggravated the disease only slightly. These findings suggest that C-protein-induced EAM is formed by activation of C-protein-specific T cells along with antibodies against conformational epitopes in C-protein but that there are undetermined factors related to the disease progression. Further analysis of C-protein-induced EAM will provide useful information to elucidate the pathomechanisms of human polymyositis.

Attenuation of Experimental Autoimmune Myositis by Blocking ICOS-ICOS Ligand Interaction

Polymyositis (PM) is an acquired, systemic, connective tissue disease characterized by the proximal muscle weakness and infiltration of mononuclear cells into the affected muscles. To understand its etiology and immunopathogenesis, appropriate animal model is required. It has been demonstrated that immunization with native human skeletal C protein induces severe and reproducible experimental autoimmune myositis (EAM) in Lewis rats, and that the muscle inflammatory lesions in the EAM mimic those of human PM. In the present study, we prepared recombinant skeletal C protein fragment and succeeded in inducing as severe EAM as that by native C protein. We found ICOS expression on muscle fiber-infiltrating T cells in the EAM rats, but not in normal rats. Treatment with anti-ICOS mAb reduced incidence and severity of myositis; decreased the number of muscle-infiltrating CD11b/c+, TCR+, and CD8a+ cells; and inhibited the expression of IL-1alpha and CCL2 in the hamstring muscles of the EAM rats. However, the treatment neither inhibited serum anti-C protein IgG level, C protein-induced proliferation of lymph node (LN) cells, or LN T cells, nor production of IFN-gamma by C protein-stimulated LN cells in EAM rats. These data indicate that analysis of C protein-induced EAM provides not only insights into pathogenesis of PM, but also useful information regarding development of effective immunotherapy against the disease. ICOS-ICOS ligand interaction would be a novel therapeutic target for PM.

B-cell epitope spreading is a critical step for the switch from C-protein-induced myocarditis to dilated cardiomyopathy

Repeated inflammation in the heart is one of the initiation factors of dilated cardiomyopathy (DCM). In a previous study, we established a new animal model for DCM by immunization of rats with recombinant cardiac C-protein fragment 2 (CC2). The present study examined factors involved in the development of DCM. Analysis using overlapping peptides revealed that the major carditogenic epitope resides only in the residue 615-647 [CC2 peptide 12 (CC2P12)]. However, immunization with CC2P12 induced moderate inflammation without subsequent DCM. CDR3 spectratyping analysis of the T-cell repertoire demonstrated that Vbeta4-positive T cells were preferentially expanded in both CC2- and CC2P12-immunized rats. Although there was no significant difference in the T-cell characteristics, examinations of the B-cell epitope revealed that marked epitope spreading occurred in CC2-immunized but not CC2P12-immunized rats from 4 weeks after immunization. Consistent with this finding, immunization with CC2P12 and simultaneous transfer of anti-peptide antisera induced significantly more severe inflammation and fibrosis than CC2P12 immunization alone. However, the transfer of the antisera without CC2P12 immunization did not induce any pathology. These findings suggest that T-cell activation and B-cell epitope spreading in the CC2 molecule is a key step for the switch from myocarditis to the development of DCM.

T-bet Controls Pathogenicity of CTLs in the Heart by Separable Effects on Migration and Effector Activity

CD8+ CTL contribute to the pathogenesis of myocarditis and cardiac allograft rejection. Using a transgenic model of myocarditis, we examined the role of the transcription factor T-bet in the differentiation of pathogenic cardiac Ag-specific CTL. We demonstrate that T-bet-deficient CTL are significantly impaired in their ability to cause disease, despite intact proliferation and activation phenotypes. In the absence of T-bet, there is markedly reduced expression of the chemokine receptor CXCR3, and CXCR3-gene knockout CTL are significantly less pathogenic than control CTL. Retroviral-mediated CXCR3 expression in T-bet-deficient CD8+ T cells reconstitutes their ability to infiltrate but not to damage the heart, establishing that CD8+ T cell pathogenicity is related to T-bet-dependent CXCR3 expression, reduced cytotoxicity, and enhanced regulation. These findings highlight the potential therapeutic benefit of targeting T-bet-regulated gene expression and CXCR3-dependent migration in immune-mediated heart disease.

Chemokine expression by astrocytes plays a role in microglia/macrophage activation and subsequent neurodegeneration in secondary progressive multiple sclerosis

The pathological hallmarks of secondary progressive (SP) multiple sclerosis (MS) include slowly expanding demyelination and axonal damage with less inflammation. To elucidate the pathomechanisms of secondary progressive (SP) multiple sclerosis (MS), we have investigated the expression of chemokines, chemokine receptors, matrix metalloproteinase-9 (MMP-9) and immunoglobulins in the demyelinating plaques. Immunohistochemical analysis revealed that numerous hypertrophic astrocytes were observed at the rim, but not in the center, of the chronic active lesions. Microglia/macrophages phagocytosing myelin debris were also found at the lesion border. In contrast, T cell infiltration was minimal in these plaques. Characteristically, at the rim of the lesions, there were abundant immunoreactivities for monocyte chemoattractant protein-1 (MCP-1)/CCL2 and interferon-gamma inducible protein-10 (IP-10)/CXCL10 and their receptors, CCR2 and CXCR3, while these immunoreactivities were weak in the center, thus forming a chemokine gradient. Double immunofluorescense staining demonstrated that cellular sources of MCP-1/CCL2 and IP-10/CXCL10 were hypertrophic astrocytes and that both astrocytes and microglia/macrophages expressed CCR2 and CXCR3. MMP-9 was also present at the rim of the lesions. These results suggest that MCP-1/CCL2 and IP-10/CXCL10 produced by astrocytes may activate astrocytes in an autocrine or paracrine manner and direct reactive gliosis followed by migration and activation of microglia/macrophages as effector cells in demyelinating lesions. Targeting chemokines in SPMS may therefore be a powerful therapeutic approach to inhibit lesional expansion.

Characterization of relapsing autoimmune encephalomyelitis and its treatment with decoy chemokine receptor genes

To elucidate the pathomechanisms of relapses of autoimmune disorders and to develop immunotherapy against relapses, we induced acute monophasic and chronic relapsing (CR) experimental autoimmune encephalomyelitis (EAE) in DA rats. Immunopathological and cytokine-chemokine analyses demonstrated that the number of infiltrating macrophages was significantly elevated in the CR-EAE than in acute EAE lesions and that IFN-gamma and IP-10 in the spinal cord were significantly upregulated during the first attack and relapse of CR-EAE, respectively, than at the peak of acute EAE. In vivo administration of decoy chemokine receptor plasmid DNAs encoding the binding sites of CXCR3 and CCR2 suppressed the development of relapse of CR-EAE. Importantly, multiple injections of DNAs did not elicit the antibody production against chemokine receptors. Taken together, these findings demonstrated that neutralization therapy with decoy chemokine receptor DNAs is effective to control autoimmune diseases.