Identification of nitrated immunoglobulin variable regions in the HIV-infected human brain: implications in HIV infection and immune response.
HIV can infiltrate the brain and lead to HIV-associated neurocognitive disorders (HAND). The pathophysiology of HAND is poorly understood, and there are no diagnostic biomarkers for it. Previously, an increase in inducible nitric oxide synthase levels and protein tyrosine nitration in the brain were found to correlate with the severity of HAND.1,2 In this study, we analyzed human brains from individuals who had HIV infection without encephalitis and with encephalitis/HAND and compared them to the brains of healthy individuals. We identified the nitrated proteins and determined the sites of modification using affinity enrichment followed by high-resolution and high-mass-accuracy nanoLC-MS/MS. We found that nitrated proteins were predominantly present in the HIV-infected individuals with encephalitis, and, interestingly, the modifications were predominantly located on immunoglobulin variable regions. Our molecular model indicated potential interactions with HIV envelope proteins and changes on the heavy and light chain interface upon the nitration and nitrohydroxylation of these residues. Therefore, our findings suggest a role for these modifications in the immune response, which may have implications in disease pathogenesis.
Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.
Lerna
L
Uzasci
Mario A
MA
Bianchet
Robert J
RJ
Cotter
Avindra
A
Nath
D000595:Amino Acid Sequence; D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D001921:Brain / Q000276:immunology* / Q000473:pathology / Q000821:virology; D001923:Brain Chemistry; D018792:Encephalitis, Viral / Q000150:complications / Q000276:immunology* / Q000473:pathology / Q000821:virology; D015658:HIV Infections / Q000150:complications / Q000276:immunology* / Q000473:pathology / Q000821:virology; D015497:HIV-1 / Q000502:physiology; D006801:Humans; D007113:Immunity, Innate; D007135:Immunoglobulin Variable Region / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009566:Nitrates; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D000906:Antibodies; D007135:Immunoglobulin Variable Region; D009566:Nitrates; C002744:3-nitrotyrosine; D014443:Tyrosine