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Increased isolevuglandin-modified proteins in glaucomatous astrocytes.

ABSTRACT: Lipid oxidation has been proposed to be a factor in the pathophysiology of glaucoma. We investigated whether elevated levels of isolevuglandin (iso[4]LGE(2)) protein adducts are associated with astrocytes derived from the glaucomatous optic nerve head. In addition, we examined whether the iso[4]LGE(2) protein adducts are altered following exposure of astrocytes to elevated pressure.Astrocytes were isolated from rat brain cortex and human optic nerve and were subjected to pressure treatments, western blot analyses, liquid chromatography tandem mass spectrometry, and immunocytochemistry.Elevated levels of isolevuglandin (iso[4]LGE(2)) protein adducts were associated with astrocytes derived from the glaucomatous (n=10) optic nerve head when compared to those from controls (n=6). Astrocytes subjected to in vitro pressure treatment resulted in increased levels of iso[4]LGE(2) protein adducts. Pressure exposure and the recovery period affect iso[4]LGE(2) protein modification, and pyridoxamine was effective in decreasing the appearance of iso[4]LGE(2) protein adduct immunoreactivity when applied immediately after pressure treatment.These results suggest that the elevated iso[4]LGE(2) protein adduct immunoreactivity observed in glaucomatous astrocytes may be due to chronic and/or prolonged exposure to pressure, and pyridoxamine may have prophylactic utility against such oxidative protein modification.

SUBMITTER: Govindarajan B

PROVIDER: S-EPMC2690965 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

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Increased isolevuglandin-modified proteins in glaucomatous astrocytes.

Govindarajan Bharathi B Junk Anna A Algeciras Mabel M Salomon Robert G RG Bhattacharya Sanjoy K SK

Molecular vision 20090601

<h4>Purpose</h4>Lipid oxidation has been proposed to be a factor in the pathophysiology of glaucoma. We investigated whether elevated levels of isolevuglandin (iso[4]LGE(2)) protein adducts are associated with astrocytes derived from the glaucomatous optic nerve head. In addition, we examined whether the iso[4]LGE(2) protein adducts are altered following exposure of astrocytes to elevated pressure.<h4>Methods</h4>Astrocytes were isolated from rat brain cortex and human optic nerve and were subje ...[more]

PMID: 19503745

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Project description:BackgroundDespite the well-established association between T-cell-mediated inflammation and nonischemic heart failure, the specific mechanisms triggering T-cell activation during the progression of heart failure and the antigens involved are poorly understood. We hypothesized that myocardial oxidative stress induces the formation of isolevuglandin (IsoLG)-modified proteins that function as cardiac neoantigens to elicit CD4+ T-cell receptor (TCR) activation and promote heart failure.MethodsWe used transverse aortic constriction in mice to trigger myocardial oxidative stress and T-cell infiltration. We profiled the TCR repertoire by mRNA sequencing of intramyocardial activated CD4+ T cells in Nur77GFP reporter mice, which transiently express GFP on TCR engagement. We assessed the role of antigen presentation and TCR specificity in the development of cardiac dysfunction using antigen presentation-deficient MhcII-/- mice and TCR transgenic OTII mice that lack specificity for endogenous antigens. We detected IsoLG protein adducts in failing human hearts. We also evaluated the role of reactive oxygen species and IsoLGs in eliciting T-cell immune responses in vivo by treating mice with the antioxidant TEMPOL and the IsoLG scavenger 2-hydroxybenzylamine during transverse aortic constriction, and ex vivo in mechanistic studies of CD4+ T-cell proliferation in response to IsoLG-modified cardiac proteins.ResultsWe discovered that TCR antigen recognition increases in the left ventricle as cardiac dysfunction progresses and identified a limited repertoire of activated CD4+ T-cell clonotypes in the left ventricle. Antigen presentation of endogenous antigens was required to develop cardiac dysfunction because MhcII-/- mice reconstituted with CD4+ T cells and OTII mice immunized with their cognate antigen were protected from transverse aortic constriction-induced cardiac dysfunction despite the presence of left ventricle-infiltrated CD4+ T cells. Scavenging IsoLGs with 2-hydroxybenzylamine reduced TCR activation and prevented cardiac dysfunction. Mechanistically, cardiac pressure overload resulted in reactive oxygen species-dependent dendritic cell accumulation of IsoLG protein adducts, which induced robust CD4+ T-cell proliferation.ConclusionsOur study demonstrates an important role of reactive oxygen species-induced formation of IsoLG-modified cardiac neoantigens that lead to TCR-dependent CD4+ T-cell activation within the heart.

Dataset Information

Increased isolevuglandin-modified proteins in glaucomatous astrocytes.

Publications

Increased isolevuglandin-modified proteins in glaucomatous astrocytes.

Similar Datasets

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