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

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.

Increased respiratory burst activity is associated with normal expression of IgG-Fc-receptors and complement receptors in peripheral neutrophils from patients with juvenile periodontitis.

The respiratory burst activity in peripheral neutrophils from nine patients with localized juvenile periodontitis (LJP) and age- and sex-matched healthy controls was studied by measuring the intensity of luminol-enhanced chemiluminescence (CL) induced by unopsonized and three differently opsonized zymosan particles, formyl-methionyl-leucyl-phenylalanine (FMLP) or phorbol myristate acetate (PMA). The neutrophils from LJP patients showed in general more intense CL with all activators than did their controls. Particularly, the CL response induced by unopsonized zymosan particles and FMLP were significantly higher (p < 0.05 and 0.001). When comparisons were made between female LJP patients (n = 6) and matched controls, also serum-opsonized and IgG-opsonized zymosan particles produced CL was significantly increased (p < 0.05). In order to determine whether the elevated CL responses to zymosan particles were due to altered levels of the interacting receptors on neutrophil surface, an immunofluorescence analysis of the expression of IgG-Fc-receptors (FcR) and complement receptors (CR) was performed with flow cytometry. No significant difference in the expression of FcRII, FcRIII, CR1 and CR3 was detected in LJP group compared to controls. Since the elevated CL responses can not be explained by changes in receptor numbers it is hypothesized that the increased respiratory burst activity in LJP may be caused by altered post receptor signalling pathway.

Altered tissue metabolism of progesterone in pregnancy gingivitis and granuloma.

The metabolism of progesterone may play a special role in the gingival physiology. The lower the metabolism the higher its hormonal activity in the tissue. In healthy human gingiva, progesterone is metabolized only partially and is therefore in an active form. In the present study, gingival samples from pregnancy gingivitis (n = 1) and granulomas (n = 4) were studied histologically and biochemically. All samples were homogenized and then incubated with [4-14C]-progesterone and NADPH for 2 h at pH 7.4 and 37 degrees C. The metabolites were separated and characterized with column, solvent and thin-layer chromatographies as well as radioautography and quantified with liquid scintillation counting. The results showed low metabolism of progesterone, indicating active hormonal function as in healthy gingiva. It is suggested that progesterone functions as an immunosuppressant in the gingival tissues of pregnant women, preventing the rapid acute-type of inflammatory reaction against plaque, but allowing an increased chronic-type of tissue reaction, resulting clinically in an exaggerated appearance of inflammation.