Evidence of an association between functional abnormalities and defective diacylglycerol kinase activity in peripheral blood neutrophils from patients with localized juvenile periodontitis

Abstract

Peripheral neutrophils from patients with localized juvenile periodontitis (LJP) show functional abnormalities, such as impaired locomotion and enhanced respiratory burst activity. A defect in intracellular signalling mechanism has been proposed to be responsible for some changes, but direct evidence is lacking. In this study we have determined the activity of diacylglycerol (DAG) kinase, an enzyme controlling the DAG/protein kinase C (PKC) pathway, in crude cytosolic and membrane fractions of neutrophils from 5L JP patients and age and gender-matched normal individuals. No difference was observed in the DAG kinase activity in subcellular fractions from unstimulated cells between the 2 groups. When normal neutrophils were stimulated with N formyl-methionyl-leucyl-phenylalanine (FMLP), the enzyme activity was markedly increased in both subcellular fractions. In contrast, neutrophils from 3 of the 5 LJP patients tested completely failed to rise the DAG kinase activity upon chemoattractant stimulation. These data indicate that in some LJP patients the neutrophil DAG kinase may be defective. To examine whether a decrease in DAG kinase activity could account for some neutrophil abnormalities seen in LJP, normal neutrophils were treated with R59022, a DAG kinase inhibitor, that has been shown to reduce DAG kinase activity in human neutrophils. Upon stimulation with FMLP, R59022-treated normal neutrophils showed significantly reduced chemotactic response and enhanced respiratory burst activity, two typical functional abnormalities featured by LJP cells. It is concluded that a defect in DAG kinase may cause, through an abnormal accumulation of the endogenous PKC activator DAG some of the functional changes observed in neutrophils from LJP patients.

Simultaneous measurements of cytoplasmic Ca2+ responses and intracellular pH in neutrophils of localized aggressive periodontitis (LAP) patients

“…These findings are in concordance with the reports of elevated levels of the PKC activator DAG in LAP-PMN [13,16,17]. More recent reports mention that an additional fMLP-mediated IP 3 -independent signal propagation, downstream of the receptor-ligand binding signal of the formyl peptide receptor-like 1, through CD38 and activation of the ryanodine receptor at calcium stores, initiates a cytoplasmic calcium response [18].…”

A Molecular Defect in Intracellular Lipid Signaling in Human Neutrophils in Localized Aggressive Periodontal Tissue Damage

“…27. Moreover, DAGK inhibition or treatment with synthetic DAG species leads to alterations in normal PMN motility (35)(36)(37). Therefore, defective DAGK expression provides a potential molecular basis that may explain disparate functional responses in PMN from patients with LAP, namely, agonist-specific reduced motility and enhanced production of superoxide anions and related reactive oxygen species.…”

Myricetin blocks lipoteichoic acid-induced COX-2 expression in human gingival fibroblasts

“…It associates with TLR-2 and is responsible for septic shock via its promotion of the expression of proinflammatory cytokines. The premise that periodontal pathogens or their components are associated with the development of periodontal disease has spurred extensive research into ways to control the disease by regulating activated intracellular signaling pathways [16][17][18][19]. There is growing evidence that plant-derived foods and beverages contribute to the healthy development and status of blood vessels and connective tissues.…”