Doug Coster

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Browsing Doug Coster by Subject "Apoptosis"

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    Apoptosis is a prominent feature of acute anterior uveitis in the Fischer 344 rat
    (BMJ Publishing Group - http://bjo.bmjjournals.com/, 2000-02) Smith, Justine R; Hart, Prue; Standfield, Scott D; Coster, Douglas John; Wing, Sarah J; Williams, Keryn Anne
    AIMS: To examine the hypothesis that apoptosis of infiltrating cells contributes to spontaneous resolution of uveitis in clinically relevant rodent models. METHODS: Experimental melanin induced uveitis (EMIU) was induced in Fischer 344 rats by immunisation with 250 microg bovine ocular melanin. Endotoxin induced uveitis (EIU) was induced by injection of 200 microg Escherichia coli lipopolysaccharide. Formalin fixed, paraffin embedded ocular cross sections were stained by terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate biotin nick end labelling (TUNEL) to identify apoptotic cells. Indirect immunoperoxidase staining of paraformaldehyde lysine periodate fixed tissue cross sections was used to demonstrate expression of inducible nitric oxide synthase (iNOS). RESULTS: TUNEL positive mononuclear cells were observed in the anterior uvea during both EMIU and EIU at all selected time points. However, whereas the majority of mononuclear cells appeared apoptotic from the outset of disease, neutrophils were notably TUNEL negative at all time points examined. Many infiltrating neutrophils expressed iNOS. CONCLUSION: Apoptosis occurs early in the course of rat EMIU and EIU, and may contribute to resolution of these diseases. In general, infiltrating mononuclear cells die rapidly, while neutrophils survive, producing inducible nitric oxide synthase which may contribute to disease pathogenesis.
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    Corneal graft rejection occurs despite Fas ligand expression and apoptosis of infiltrating cells
    (BMJ Publishing Group - http://bjo.bmjjournals.com/, 2005-05) Williams, Keryn Anne; Standfield, Scott D; Smith, Justine R; Coster, Douglas John
    BACKGROUND/AIMS: Constitutive expression of Fas ligand (CD95L) protects the eye against cell mediated immune responses by inducing apoptosis in infiltrating Fas bearing T cells. This study was designed to examine Fas ligand expression on acutely rejecting rat corneal grafts and to investigate the kinetics of induction of apoptosis in infiltrating leucocytes. METHODS: Orthotopic penetrating corneal transplantation was performed between genetically disparate inbred rats. Fas ligand expression and the phenotype of infiltrating leucocytes were examined by immunohistochemistry. Apoptotic nuclei were visualised in sections of normal rat cornea, rejecting allografts, and time matched isografts by terminal deoxynucleotidyl transferase mediated dUTP biotin nick end labelling (TUNEL) and quantified by video image analysis. Staining with Hoechst dye 33258 was used to confirm the presence of apoptotic nuclei. RESULTS: Fas ligand was expressed on corneal endothelial and epithelial cells during acute corneal graft rejection. At all time points examined, including as early as the fifth postoperative day, the cells infiltrating both corneal isografts and allografts were TUNEL positive. By the 15th postoperative day, over 90% of all nuclei, many of which were T cells, were apoptotic. CONCLUSION: Expression of Fas ligand is not downregulated on the cornea during allograft rejection and infiltrating leucocytes in both isografts and allografts die rapidly in situ. Despite the death of the cells believed to be responsible for rejection, isografts survive indefinitely whereas allografts are irreparably damaged.