Our recent studies have demonstrated that aldose reductase (AR), plays a pivotal rote in the detoxification of lipid peroxidation-generated lipid derived aldehydes (LDAs) and their conjugates with GSH. 4-hydroxy trans-2-nonenal (HNE), one of the most toxic and abundant LDA generated during lipid peroxidation and GS-HNE are efficiently reduced by AR. We have further demonstrated that AR mediates the mitogenic and cytotoxic signals of reactive oxygen species (ROS) generated by TNF-alpha, growth factors and hyperglycemia leading to proliferation and apoptosis of vascular smooth muscle cells and vascular endothelial cells, respectively. We have also observed that inhibition of AR by specific inhibitors or ablation of AR by antisense or RNAi attenuates the activation of PKC and MAPK, phosphorylation and degradation of IkappaB-alpha and activation of NF-kappaB and API. Also, AR inhibition attenuates lipopolysaccharide (LPS)-induced secretion of cytokines such as TNF-alpha, IL-6, and IL-10, secondary messenger cAMP and prostaglandin E2 in mouse peritoneal macrophages. Our hypothesis is that AR plays a pivotal role in the transduction of LPS-induced inflammatory responses mediated via ROS. We will now systematically examine our hypothesis by investigating the release of LPS-induced cytokines and chemokines by mouse peritoneal macrophages and RAW246.7 cells and identify the mechanism(s) of inhibition of these cytotoxic signals by AR ablation. Attenuation of LPS-induced inflammatory cytokines and chemokines by AR inhibition will be investigated in the liver, spleen, small intestine, kidney, heart and serum, and correlated with attenuation of inflammation in tissues of mice. Thus our aims are to 1) Delineate the involvement of AR in bacterial endotoxin (LPS)-induced cytotoxic signals in macrophages, 2) Investigate the role of AR in LPS-induced expression of proinflammatory cytokines and chemokines in mouse macrophages, 3) Identify the molecular mechanisms and possible targets of AR and 4) Investigate the in vivo role of AR in the regulation of cytokine and chemokine generation and inflammation in mice. Completion of these studies will demonstrate how AR inhibitors attenuate the ROS-mediated LPS and cytokine signals, provide a novel therapeutic approach for preventing inflammation-induced toxicity and elucidate the molecular mechanism(s) of AR's involvement in these complications.
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