The goal of this proposal is to determine the exact roles of certain lipid second messenger molecules [i.e., diacylglycerols (DAG's)] and endogenous mediators [resolvins, docosatrienes (DT), lipoxins] in periodontal inflammation, and to continue to develop novel molecular strategies to pharmacologically interrupt the inflammatory cascade. We will focus on Localized Aggressive Periodontitis (LAP, formerly known as localized juvenile periodontitis, LJP), which presents neutrophils with a classically """"""""primed"""""""" phenotype, i.e. hyper-responsiveness in superoxide production during cell stimulation. Neutrophils (PMN) isolated from peripheral blood of LAP patients exhibit a three fold elevation in cellular diacylglycerol and a two to three fold increase in membrane associated protein kinase (PKC) activity. A marked decrease in the alpha-isoform of DAG kinase (DGKalpha) activity occurs in these cells, which is likely to be responsible for the elevated levels of DAG and the priming phenomena. Work by our group (see Project 0001) has revealed new classes endogenous lipid mediators (LM), the resolvins and docosatrienes (DT), which are potent natural inhibitors of inflammation in a wide variety of animal models including the rabbit model of periodontal destruction. These compounds block superoxide production and chemotaxis in stimulated PMN with certain agonists. To accomplish our goals, we will evaluate the molecular mechanisms responsible for the dramatic decrease in DGKalpha activity in LAP PMN at the genetic and biochemical level, identify the isoforms of membrane-bound PKC that are elevated in LAP PMN due to increased DAG, and determine how these elevations in DAG/membrane bound PKC """"""""prime"""""""" the NADPH-oxidase complex to produce more superoxide/peroxide in LAP PMN. Finally, we will evaluate the beneficial effect of resolvins and docosatrienes on periodontal inflammation in situ and compare our results to those observed for lipoxins and their stable analogs. Techniques of molecular biology, biochemistry, and animal pathophysiology will be used in these studies.
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