NADPH oxidase modifies patterns of MHC class II-restricted epitopic repertoires through redox control of antigen processing.
The chemistries within phagosomes of APCs mediate microbial destruction as well as generate peptides for presentation on MHC class II. The antimicrobial effector NADPH oxidase (NOX2), which generates superoxide within maturing phagosomes, has also been shown to regulate activities of cysteine cathepsins through modulation of the lumenal redox potential. Using real-time analyses of lumenal microenvironmental parameters, in conjunction with hydrolysis pattern assessment of phagocytosed proteins, we demonstrated that NOX2 activity not only affects levels of phagosomal proteolysis as previously shown, but also the pattern of proteolytic digestion. Additionally, it was found that NOX2 deficiency adversely affected the ability of bone marrow-derived macrophages, but not dendritic cells, to process and present the I-A(b)-immunodominant peptide of the autoantigen myelin oligodendrocyte glycoprotein (MOG). Computational and experimental analyses indicated that the I-A(b) binding region of the immunodominant peptide of MOG is susceptible to cleavage by the NOX2-controlled cysteine cathepsins L and S in a redox-dependent manner. Consistent with these findings, I-A(b) mice that were deficient in the p47(phox) or gp91(phox) subunits of NOX2 were partially protected from MOG-induced experimental autoimmune encephalomyelitis and displayed compromised reactivation of MOG-specific CD4(+) T cells in the CNS, despite eliciting a normal primary CD4(+) T cell response to the inoculated MOG Ag. Taken together, this study demonstrates that the redox microenvironment within the phagosomes of APCs is a determinant in MHC class II repertoire production in a cell-specific and Ag-specific manner, which can ultimately impact susceptibility to CD4(+) T cell-driven autoimmune disease processes.
Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada; Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada;
Euan R O
ER
Allan
Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada; Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada;
Pankaj
P
Tailor
Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada; Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada;
Dale R
DR
Balce
Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada; Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada; Department of Chemistry, Faculty of Science, University of Calgary, Calgary, Alberta T2N 1N4, Canada; and.
Payman
P
Pirzadeh
Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada; Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada;
Neil T
NT
McKenna
Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada; Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada;
Bernard
B
Renaux
Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
Amy L
AL
Warren
Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada;
Frank R
FR
Jirik
Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada; Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada; rmyates@ucalgary.ca.
Robin M
RM
Yates
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000473:pathology; D001854:Bone Marrow Cells / Q000276:immunology* / Q000473:pathology; D015496:CD4-Positive T-Lymphocytes; D056668:Cathepsin L / Q000235:genetics / Q000276:immunology; D002403:Cathepsins / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000235:genetics / Q000276:immunology / Q000473:pathology; D018984:Epitopes, T-Lymphocyte / Q000235:genetics / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology*; D008264:Macrophages / Q000276:immunology* / Q000473:pathology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D063308:Myelin-Oligodendrocyte Glycoprotein / Q000235:genetics / Q000276:immunology; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000235:genetics / Q000276:immunology*; D010084:Oxidation-Reduction
D018984:Epitopes, T-Lymphocyte; D000949:Histocompatibility Antigens Class II; D008562:Membrane Glycoproteins; C571327:Mog protein, mouse; D063308:Myelin-Oligodendrocyte Glycoprotein; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D002403:Cathepsins; D056668:Cathepsin L; C534278:Ctsl protein, mouse; C028217:cathepsin S