Nitration of tyrosines in complement factor H domains alters its immunological activity and mediates a pathogenic role in age related macular degeneration.
Nitrosative stress has been implicated in the pathogenesis of age related macular degeneration (AMD). Tyrosine nitration is a unique type of post translational modification that occurs in the setting of inflammation and nitrosative stress. To date, the significance and functional implications of tyrosine nitration of complement factor H (CFH), a key complement regulator in the eye has not been explored, and is examined in this study in the context of AMD pathogenesis.Sections of eyes from deceased individuals with AMD (n = 5) demonstrated the presence of immunoreactive nitrotyrosine CFH. We purified nitrated CFH from retinae from 2 AMD patients. Mass spectrometry of CFH isolated from AMD eyes revealed nitrated residues in domains critical for binding to heparan sulphate glycosaminoglycans (GAGs), lipid peroxidation by-products and complement (C) 3b.Functional studies revealed that nitrated CFH did not bind to lipid peroxidation products, nor to the GAG of perlecan nor to C3b. There was loss of cofactor activity for Factor I mediated cleavage of C3b with nitrated CFH compared to non-nitrated CFH. CFH inhibits, but nitrated CFH significantly potentiates, the secretion of the pro-inflammatory and angiogenic cytokine IL-8 from monocytes that have been stimulated with lipid peroxidation by-products. AMD patients (n = 30) and controls (n = 30) were used to measure plasma nitrated CFH using a novel ELISA. AMD patients had significantly elevated nitrated CFH levels compared to controls (p = 0.0117). These findings strongly suggest that nitrated CFH contributes to AMD progression, and is a target for therapeutic intervention.
Save Sight Institute, University of Sydney and Sydney Eye Hospital, Sydney, NSW, Australia.
Matthew
M
Krilis
Department of Infectious Diseases, Immunology and Sexual Health and Department of Medicine, St George Hospital, University of New South Wales, Sydney, NSW, Australia.
Miao
M
Qi
Save Sight Institute, University of Sydney and Sydney Eye Hospital, Sydney, NSW, Australia.|School of Optometry and Vision Science, University of New South Wales, Sydney, NSW, Australia.
Michele C
MC
Madigan
Prince of Wales Clinical School, University of New South Wales, Lowy Cancer Research Centre, Sydney, NSW, Australia.
Jason W H
JWH
Wong
Department of Infectious Diseases, Immunology and Sexual Health and Department of Medicine, St George Hospital, University of New South Wales, Sydney, NSW, Australia.
Mahmoud
M
Abdelatti
Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Victoria, Australia.
Robyn H
RH
Guymer
Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, Australia.
John
J
Whitelock
Save Sight Institute, University of Sydney and Sydney Eye Hospital, Sydney, NSW, Australia.
Peter
P
McCluskey
Department of Infectious Diseases, Immunology and Sexual Health and Department of Medicine, St George Hospital, University of New South Wales, Sydney, NSW, Australia.|Department of Cardiothoracic Surgery, Tianjin Medical University General Hospital, Tianjin, China.
Peng
P
Zhang
Department of Infectious Diseases, Immunology and Sexual Health and Department of Medicine, St George Hospital, University of New South Wales, Sydney, NSW, Australia.
Jian
J
Qi
Save Sight Institute, University of Sydney and Sydney Eye Hospital, Sydney, NSW, Australia.
Alex P
AP
Hunyor
Department of Infectious Diseases, Immunology and Sexual Health and Department of Medicine, St George Hospital, University of New South Wales, Sydney, NSW, Australia.
Steven A
SA
Krilis
Department of Infectious Diseases, Immunology and Sexual Health and Department of Medicine, St George Hospital, University of New South Wales, Sydney, NSW, Australia.|Department of Rheumatology, St George Hospital, Sydney, NSW, Australia.
Bill
B
Giannakopoulos
D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D015415:Biomarkers; D016022:Case-Control Studies; D002829:Choroid / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D003179:Complement C3b / Q000276:immunology / Q000378:metabolism; D017242:Complement Factor H / Q000737:chemistry / Q000378:metabolism*; D004198:Disease Susceptibility; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism; D006801:Humans; D056747:Immunomodulation; D008268:Macular Degeneration / Q000175:diagnosis / Q000209:etiology* / Q000378:metabolism*; D008297:Male; D009000:Monocytes / Q000276:immunology / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D059748:Proteolysis; D026361:Reactive Nitrogen Species / Q000378:metabolism; D012160:Retina / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D012720:Severity of Illness Index; D053719:Tandem Mass Spectrometry; D014443:Tyrosine / Q000235:genetics*
D015415:Biomarkers; D019812:Heparan Sulfate Proteoglycans; D010446:Peptide Fragments; D026361:Reactive Nitrogen Species; D014443:Tyrosine; D003179:Complement C3b; D017242:Complement Factor H
complement factor H; macular degeneration; nitrosative stress; retina