title: Cathepsin L is essential for onset of autoimmune diabetes in NOD mice.
abstract: Lysosomal proteases generate peptides presented by class II MHC molecules to CD4+ T cells. To determine whether specific lysosomal proteases might influence the outcome of a CD4+ T cell-dependent autoimmune response, we generated mice that lack cathepsin L (Cat L) on the autoimmune diabetes-prone NOD inbred background. The absence of Cat L affords strong protection from disease at the stage of pancreatic infiltration. The numbers of I-A(g7)-restricted CD4+ T cells are diminished in Cat L-deficient mice, although a potentially diabetogenic T cell repertoire persists. Within the CD4+ T cell compartments of Cat L-deficient mice, there is an increased proportion of regulatory T cells compared with that in Cat L-sufficient littermates. We suggest that it is this displaced balance of regulatory versus aggressive CD4+ T cells that protects Cat L-deficient mice from autoimmune disease. Our results identify Cat L as an enzyme whose activity is essential for the development of type I diabetes in the NOD mouse.
authors.affiliation: Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: René
authors.initials: R
authors.lastname: Maehr
authors.forename: Justine D
authors.initials: JD
authors.lastname: Mintern
authors.forename: Ann E
authors.initials: AE
authors.lastname: Herman
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Lennon-Duménil
authors.forename: Diane
authors.initials: D
authors.lastname: Mathis
authors.forename: Christophe
authors.initials: C
authors.lastname: Benoist
authors.forename: Hidde L
authors.initials: HL
authors.lastname: Ploegh
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D056668:Cathepsin L; D002403:Cathepsins / Q000235:genetics / Q000276:immunology*; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000276:immunology*; D003921:Diabetes Mellitus, Experimental / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D008247:Lysosomes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D016688:Mice, Inbred NOD; D018345:Mice, Knockout; D010179:Pancreas / Q000276:immunology / Q000473:pathology; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000473:pathology
chemical_list: D000949:Histocompatibility Antigens Class II; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D056668:Cathepsin L; C534278:Ctsl protein, mouse