krn-7000 and Myocarditis

Topics: Animals; Antigens, Ly; Autoimmune Diseases; Galactosylceramides; Immunity, Cellular; Mice; Mice, Inbred BALB C; Myocarditis; NK Cell Lectin-Like Receptor Subfamily B

There are two major haplotypes of signal lymphocytic activation molecule (Slam) in inbred mouse strains, with the Slam haplotype 1 expressed in C57Bl/6 mice and the Slam haplotype 2 expressed in most other commonly used inbred strains, including 129 mice. Because signaling through Slam family receptors can affect innate immunity [natural killer T cell (NKT) and γ-δ T-cell receptor], and innate immunity can determine susceptibility to coxsackievirus B3 (CVB3) infection, the present study evaluated the response of C57Bl/6 and congenic B6.129c1 mice (expressing the 129-derived Slam locus) to CVB3. CVB3-infected C57Bl/6 male mice developed increased myocarditis but reduced hepatic injury compared with infected B6.129c1 mice. C57Bl/6 mice also had increased γδ(+) and CD8(+)interferon-γ(+) cells but decreased numbers of NKT (T-cell receptor β chain + mCD1d tetramer(+)) and CD4(+)FoxP3(+) cells compared with B6.129c1 mice. C57Bl/6 mice were infected with CVB3 and treated with either α-galactosylceramide, an NKT cell-specific ligand, or vehicle (dimethyl sulfoxide/PBS). Mice treated with α-galactosylceramide showed significantly reduced myocarditis. Liver injuries, as determined by alanine aminotransferase levels in plasma, were increased significantly, confirming that NKT cells are protective for myocarditis but pathogenic in the liver.

Topics: Adaptive Immunity; Alanine Transaminase; Animals; Antigens, CD; Coxsackievirus Infections; Enterovirus B, Human; Galactosylceramides; Haplotypes; Hepatitis; Liver; Lymphocyte Activation; Lymphocyte Count; Male; Mice; Mice, Inbred C57BL; Myocarditis; Natural Killer T-Cells; Polymorphism, Genetic; Receptors, Antigen, T-Cell, gamma-delta; Receptors, Cell Surface; Signaling Lymphocytic Activation Molecule Family Member 1; Troponin I; Viral Load

This study was designed to investigate the role of α-galactosylceramide (α-GalCer) on experimental autoimmune myocarditis (EAM), and to explore the underlying mechanisms. Balb/c mice were immunized with porcine cardiac myosin to establish the EAM model. All the immunized mice were divided into two groups, the α-GalCer group and the EAM group. α-GalCer or vehicle was given intraperitoneally at the time of immunization. Then α-GalCer or PBS was injected on alternate days for 6 weeks. Myocardial inflammation was evaluated by H & E staining and the expression levels of C/EBPβ and α-SMA were determined by immunohistochemistry. CD4(+)CD25(+)Foxp3(+) Tregs and iNKT cells were analyzed and sorted by flow cytometry. Western blot analysis was performed to detect MMP-2 and MMP-9 protein expression. Following α-GalCer treatment for 6 weeks, myocardial inflammation improved significantly in the α-GalCer treated group compared to the EAM group. The proportions of CD4(+)CD25(+)Foxp3(+) regulatory T cells and NK1.1(+) iNKT cells were statistically increased in the α-GalCer treated group compared to the EAM and normal control groups. In contrast to the EAM group, α-GalCer treatment significantly increased myocardial MMP-2 and MMP-9 expression. Expression of C/EBPβ increased significantly in the EAM group compared to the other two groups. In contrast, the expression of α-SMA did not differ significantly among the three groups. This study demonstrated that α-GalCer alleviates EAM. Thus, α-GalCer represents a potential therapeutic target for autoimmune-inflammation mediated cardiac damage. α-GalCer protects EAM through upregulation of the proportion of iNKT and Tregs and increased expression of myocardial MMP-2 and MMP-9.

Topics: Actins; Animals; Autoimmune Diseases; Blotting, Western; CCAAT-Enhancer-Binding Protein-alpha; Disease Models, Animal; Forkhead Transcription Factors; Galactosylceramides; Interleukin-2 Receptor alpha Subunit; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Myocarditis; Myocardium; Natural Killer T-Cells; Severity of Illness Index; T-Lymphocytes, Regulatory

Myocarditis is an inflammation of the myocardium which often follows virus infections. Coxsackievirus B3 (CVB3), as a marker of the enterovirus group, is one of the most important infectious agents of virus-induced myocarditis. Using a CVB3-induced myocarditis model, we show that injection α-galactosylceramide (α-GalCer), a ligand for invariant natural killer (NK) T (iNK T) cells, can protect the mice from viral myocarditis. After the systemic administration of α-GalCer in CVB3 infected mice, viral transcription and titres in mouse heart, sera and spleen were reduced, and the damage to the heart was ameliorated. This is accompanied by a better disease course with an improved weight loss profile. Compared with untreated mice, α-GalCer-treated mice showed high levels of interferon (IFN)-γ and interleukin (IL)-4, and reduced proinflammatory cytokines and chemokines in their cardiac tissue. Anti-viral immune response was up-regulated by α-GalCer. Three days after CVB3 infection, α-GalCer-administered mice had larger spleens. Besides NK T cells, more macrophages and CD8(+) T cells were found in these spleens. Upon stimulation with phorbol myristate acetate plus ionomycin, splenocytes from α-GalCer-treated mice produced significantly more cytokines [including IFN-γ, tumour necrosis factor-α, IL-4 and IL-10] than those from untreated mice. These data suggest that administration of α-GalCer during acute CVB3 infection is able to protect the mice from lethal myocarditis by local changes in inflammatory cytokine patterns and enhancement of anti-viral immune response at the early stage. α-GalCer is a potential candidate for viral myocarditis treatment. Our work supports the use of anti-viral treatment early to reduce the incidence of virus-mediated heart damage.

Topics: Animals; Body Weight; Cells, Cultured; Coxsackievirus Infections; Cytokines; Enterovirus B, Human; Enzyme-Linked Immunosorbent Assay; Galactosylceramides; Heart; Host-Pathogen Interactions; Macrophages; Male; Mice; Mice, Inbred BALB C; Myocarditis; Myocardium; Natural Killer T-Cells; Reverse Transcriptase Polymerase Chain Reaction; RNA, Viral; Survival Rate; T-Lymphocytes; Transcription, Genetic; Viral Load