Analysis of phospholipase C and phospholipase D activity in neutrophils from localized periodontitis
Date
2003
DOI
Authors
Al-Harbi, Bandar
Version
OA Version
Citation
Abstract
Neutrophils from patients with Localized Aggressive Periodontitis (LAP) present enhanced function and activity. This excessive activity would lead to the increased and proIonged release of reactive oxygen species that could be involved in periodontal tissue destruction. Protein kinase C (PKC) the enzyme that regulates the generation of reactive oxygen species in neutrophils is activated by second lipid messengers, namely diacyglycerol (DAG) and phosphatidic acid (PA). It has been shown that DAG in neutrophils from individuals with LAP is increased and the activity of DAG kinase, the enzyme that is responsible of metabolizing DAG, is significantly reduced compared to healthy neutrophils from non-periodontitis and systemically healthy subjects. It is not known, however, if there is any alteration in the production of different DAG species through the enzymatic catalysis of various phospholipids. Phospholipase C (PLC) and Phospholipase D (PLD) are the two major enzymes that generate DAG moieties. The aim of this study was to evaluate the activities of PLC and PLD in LAP neutrophils. Peripheral blood neutrophils were isolated from LAP patients and age, race, and gender-matched control individuals. PLD activity was assayed spectrophotometrically by measuring the choline oxidase-mediated oxidation of Phosphatidylcholine (PC) into Phosphatidic acid (PA). Phosphoinositide-specific PLC (PI-PLC) activity was measured by hydrolysis of radioactively labeled phosphatidylinositol 4,5-phosphate (PIP2) into DAG while Phosphatidylcholine-specific PLC (PC-PLC) activity was also measured. PLD activity was significantly increased in LAP neutrophils compared to healthy cells. When the neutrophils were stimulated with N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), PC-PLC activity was significantly increased in LAP. Pl-PLC activity, on the other hand was delayed in response to fMLP stimulation in LAP neutrophils. These findings show that the major pathways of both the early and sustained phases of DAG generation in LAP neutrophils are altered suggesting that signal transduction mediated by phospholipase catalysis of lipid substrates in LAP is, at least in part, involved in neutrophil priming.
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Thesis (M.S.D.)--Boston University, Henry M. Goldman School of Dental Medicine, 2003 (Oral Biology).
Includes bibliographic references (leaves 69-90).
Thesis (M.S.D.)--Boston University, Henry M. Goldman School of Dental Medicine, 2003 (Oral Biology).
Includes bibliographic references (leaves 69-90).
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This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.