The role of oxidative stress and CD154-mediated reactive oxygen species in regulating hepatocyte cell death during hypoxia and hypoxia-reoxygenation

Bhogal, Ricky Harminder (2013). The role of oxidative stress and CD154-mediated reactive oxygen species in regulating hepatocyte cell death during hypoxia and hypoxia-reoxygenation. University of Birmingham. Ph.D.

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Abstract

Hypoxia and hypoxia-reoxygenation (H-R) are pathogenic factors in many liver diseases and lead to hepatocyte death as a result of reactive oxygen species (ROS) accumulation. Activation of the Tumour Necrosis Factor-a (TNFa) super-family member CD40 by its cognate ligand CD 154 can induce hepatocyte apoptosis via induction of autocrine/paracrine F as Ligand/CD178 expression but the relationship between CD40 activation, ROS generation and hepatocyte cell death is poorly understood. Therefore, human hepatocytes were isolated from liver tissue and exposed to an in vitro model of hypoxia and H-R in the presence or absence of CD154 and/or various inhibitors. Hepatocyte ROS production, apoptosis, necrosis and autophagy were determined by a four-colour reporter flow cytometry assay. The in vivo regulation of liver injury by CD40 and CD 154 was determined using a murine model of partial liver ischaemia. Exposure of human hepatocytes to recombinant CD 154 or platelet-derived soluble CD 154 augmented ROS accumulation during H-R resulting in NADPH oxidase-dependent apoptosis and necrosis. The cyto-protectivc mechanism of autophagy limited apoptotic cell death during hypoxia and H-R. CD40 and CD 154 knockout mice but not wild type mice were protected from ischaemic liver injury. Hence, CD40:CD154 mediate hepatocytes cell death in vitro and in vivo during hypoxia and H-R.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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