title: Inhibition of experimental autoimmune myocarditis: peripheral deletion of TcR Vbeta 8.1, 8.2+ CD4+ T cells in TLR-4 deficient mice.
abstract: Toll-like receptors (TLR) are pattern recognition receptors that are an essential feature of host defense against pathogens. Expression of TLR-4 on dendritic cells was reported to be required for initiation of experimental autoimmune myocarditis (EAM) but the mechanism by which TLR-4 signaling affects autoimmunity is incompletely understood. To determine the role of TLR-4 in EAM, wild type and TLR-4-/- mice were immunized with myosin peptide (614-629) in CFA. TLR-4-/- mice demonstrated decreased myosin specific proliferation and decreased production of INF-gamma and IL-2. Immunization with myosin induced greater severity of myocarditis in wild type compared to TLR-4-/- mice as evidenced by lesions in the myocardium. TcR Vbeta 8.1, 8.2+ CD4+ T cells, detected in lesions were isolated from splenocytes by flow cytometry and found to undergo increased apoptosis in TLR-4-/- mice. In situ immunohistochemistry showed increased colocalization of cleaved caspase 3 and TcR Vbeta 8.1, 8.2+ CD4+ T cells in TLR-4-/- mice compared to wild type. Increased apoptosis was associated with impaired activation of NF-kB p65 and decreased cell viability in the presence of TNF-alpha. These results demonstrate that infiltrating TcR Vbeta 8.1, 8.2+ CD4+ T cells are deleted by the mechanism of apoptosis in TLR-4-/- mice with EAM.
authors: Department of Anesthesiology, Children's Hospital and Harvard Medical School, 320 Longwood Ave., Boston, MA 02115, USA. pgonnell@bigmc.harvard.edu
authors: Patricia A
authors: PA
authors: Gonnella
authors: Hanspeter
authors: H
authors: Waldner
authors: Pedro J
authors: PJ
authors: Del Nido
authors: Francis X
authors: FX
authors: McGowan
mesh_terms: D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002470:Cell Survival; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005260:Female; D005434:Flow Cytometry; D017353:Gene Deletion; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D009205:Myocarditis / Q000235:genetics / Q000276:immunology*; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000276:immunology*; D012720:Severity of Illness Index; D013154:Spleen / Q000166:cytology; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology*
chemical_list: D010446:Peptide Fragments; D016693:Receptors, Antigen, T-Cell, alpha-beta; C109168:T-cell receptor Vbeta 8.2; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4