[IL-10 gene modification on immature dendritic cells induces antigen-specific tolerance in experimental autoimmune myocarditis].

OBJECTIVE: To investigate whether IL-10 gene modification on immature dendritic cells (iDC) could induce autoimmune tolerance in rat experimental autoimmune myocarditis (EAM). METHODS: EAM was induced by cardiac myosin immunization on day 0 and day 7 in rats. A total of 2 x 10(6) mature DC (mDC), iDC, pcDNA3 transfected iDC, pcDNA3-IL-10 transfected iDC or PBS were injected intravenously at 5th immunization day. Three weeks later, echocardiography and HE staining were performed to observe the cardiac function and myocardial inflammation. Th1/Th2 cytokines were detected by ELISA and MHC-II molecules, costimulatory molecules were identified by flow cytometry. In vitro T lymphocyte proliferation assay and adoptive transfer of DCs were performed to determine the antigen specific tolerance induced by IL-10 gene modification on iDCs. RESULTS: EAM rats treated with pcDNA3-IL-10 transfected iDC showed improved cardiac function and reduced inflammatory cells infiltration into myocardium. Moreover, lower Th1 and higher Th2-type response was induced, MHC-II and costimulatory molecules down-regulated and antigen specific immunological responses towards cardiac myosin inhibited in pcDNA3-IL-10-iDC treated EAM rats. CONCLUSION: Treatment with IL-10 gene modified iDCs could ameliorates EAM by inducing Th2 polarization and down-regulation of MHC-II molecules and costimulatory molecule expressions.

Antigen-specific tolerance induced by IL-10 gene modified immature dendritic cells in experimental autoimmune myocarditis in rats.

BACKGROUND: Experimental autoimmune myocarditis (EAM) in rats is a T-cell-mediated disorder. The initiation and maintenance of autoimmune responses in EAM depend on the maturation state of dendritic cells. IL-10 is a pleiotrophic immunomodulatory cytokine that functions at different levels of the immune response, so it has emerged as a promising therapeutic factor for the treatment of autoimmune/inflammatory diseases. This study was designed to test the hypothesis that IL-10 gene modified bone marrow-derived immature dendritic cells (iDCs) ameliorate EAM and to explore the underlying mechanisms. METHODS: EAM was induced using the methods of cardiac myosin immunization on day 0 and day 7. Immature and mature bone marrow-derived dendritic cells (BMDCs) were generated without or with the stimulation by lipopolysaccharide (LPS) and the phenotype was analyzed by flow cytometry. Some of the iDCs were transfected by pcDNA3-IL-10 plasmid. 2 x 10(6)/per rat mature DC (mDC), immature DC (iDC), pcDNA3 transfected iDC, pcDNA3-IL-10 transfected iDC or phosphate buffered saline (PBS) were injected intravenously for treatment 5 days after the first immunization. On day 21, HE staining was performed to detect the myocardial inflammation and T lymphocyte proliferation assay was used to determine the effects of IL-10 gene transfected iDC on autoreactive T cell proliferation. Expression of IkappaB, the inhibitor of NF-kappaB pathway, was determined by Western blot. RESULTS: BMDCs generated in a medium supplemented with granulocyte-macrophage-colony-stimulating factor (GM-CSF) were relatively immature, as determined by flow cytometry. However, stimulation with LPS induced these cells to become mature (m) DCs with higher levels of surface major histocompatibility complex (MHC)-II and costimulatory molecules. Intravenous administration of iDCs, especially pcDNA3-IL-10 transfected iDC, ameliorated the histopathological severity of the myosin induced-EAM, and the effect was lost after the DCs underwent maturation induced by in vitro exposure to LPS. IL-10 gene modified iDC inhibited the antigen specific T cell responses towards cardiac myosin. IkappaB protein was up-regulated significantly in the IL-10 gene modified iDC group. CONCLUSIONS: IL-10 gene modified iDC induced antigen-specific tolerance in EAM. The underlying mechanisms may be related to costimulatory molecules down-regulation and NF-kappaB pathway inhibition.

Immunoregulatory effects of atorvastatin on experimental autoimmune myocarditis in Lewis rats.

Experimental autoimmune myocarditis (EAM) in rats is a T-cell-mediated disorder and has been shown to involve immune imbalance. The aim of this study was to examine the immunomodulatory effects of 3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitor, atorvastatin, on the expression of MHC class II molecules in the myocardium of rats with EAM, and to examine its therapeutic potential for EAM. EAM was induced in Lewis rats by injection of porcine cardiac myosin. High-dosage (10 mg/kg per day) or low-dosage (1 mg/kg per day) atorvastatin or vehicle was given orally for 3 weeks. On day 21 after immunization, echocardiography was carried out and the severity of myocarditis was evaluated by histopathological investigations. Immunohistochemistry techniques were used to examine the expression of MHC class II molecules in the myocardium. Type I, III and IV class II transactivator (CIITA) promoter transcription was evaluated by reverse transcription-PCR. Cardiomyocytes were isolated and the expression of MHC class II molecules by them was detected using cytometry. Serum Th1/Th2 cytokines were examined on day 21 by ELISA. Cardiac function was improved in the two atorvastatin-treated groups compared with the untreated one. In atorvastatin groups, the histopathological severity of myocarditis was attenuated and the expression of MHC class II molecules on the 'nonprofessional' APC, the cardiomyocytes, was reduced. mRNA level of type IV CIITA promoter was downregulated in the statin-treated groups in a dosage-dependent manner, but levels of type I and III CIITA mRNA did not differ between the groups statistically. Levels of IFN-gamma and IL-2 increased, whereas levels of IL-4 and IL-10 decreased, in immunized rats from day three through day 21. Atorvastatin reversed these trends in the treated groups. Atorvastatin improves cardiac function and histopathology of the myocardium in EAM by inducing Th2-biased immune responses, and thus 3-hydroxy-3-methyl-glutaryl coenzyme A reductase blockade may be a promising new strategy for the treatment of cardiac autoimmune impairments. The underlying mechanisms may be related to downregulation of MHC class II Ag expression due to silencing of the CIITA mRNA transcription.