Altered neutrophil function in localized juvenile periodontitis: intrinsic cellular defect or effect of immune mediators?

Polymorphisms within the IL-1 gene cluster: effects on cytokine profiles in peripheral blood and whole blood cell cultures of patients with aggressive periodontitis, juvenile idiopathic arthritis, and rheumatoid arthritis

BACKGROUND

Genetic polymorphisms of cytokines have been associated with the susceptibility, severity, and clinical outcome of inflammatory diseases, such as periodontitis and chronic arthritis. An important question to address is how interleukin (IL)-1 polymorphisms affect the cytokine profiles of patients with such diseases.

METHODS

The study population consisted of Danish white adults, <35 years of age, who were diagnosed with localized aggressive periodontitis (LAgP, n = 18), generalized aggressive periodontitis (GAgP, n = 27), juvenile idiopathic arthritis (JIA, n = 10), and rheumatoid arthritis (RA, n = 23) and healthy individuals with no systemic or oral diseases (n = 25). Genotypes of IL-1A-889, IL-1A+4845, IL-1B-511, and IL-1B+3954 were determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism, and IL-1RN variable number tandem repeat (VNTR) was detected by PCR amplification and fragment size analysis. Analysis of variance was used to evaluate the effects of IL-1 genotypes on the levels of IL-1alpha, -1beta, -1 receptor antagonist, -6, and -10; tumor necrosis factor-alpha (TNF-alpha); and lymphotoxin-alpha in peripheral blood (plasma) and in unstimulated and stimulated whole blood cell cultures from the same blood collection.

RESULTS

The frequencies of IL-1 genotypes investigated did not differ significantly between diseased and control individuals. In LAgP patients, allele 2 of IL-1RN VNTR was associated with significantly higher levels of IL-1alpha, -6, and -10 and TNF-alpha, whereas allele 2 of IL-1B+3954 was associated with significantly lower levels of the same cytokines. In GAgP patients, a general lack of association was found. In JIA and RA patients, IL-1RN VNTR also influenced the cytokine levels.

CONCLUSIONS

IL-1 genotypes were associated with cytokine levels in patients with aggressive periodontitis and chronic arthritis. No associations were observed in control individuals.

Position paper: periodontal diseases of children and adolescents

Children and adolescents are subject to several periodontal diseases. Although there is a much lower prevalence of destructive periodontal diseases in children than in adults, children can develop severe forms of periodontitis. In some cases, this destructive disease is a manifestation of a known underlying systemic disease. In other young patients, the underlying cause for increased susceptibility and early onset of disease is unknown. These diseases are often familial, suggesting a genetic predisposition for aggressive disease. Current modalities for managing periodontal diseases of children and adolescents may include antibiotic therapy in combination with non-surgical and/or surgical therapy. Since early diagnosis ensures the greatest chance for successful treatment, it is important that children receive a periodontal examination as part of their routine dental visits.

Single nucleotide polymorphisms of the N-formyl peptide receptor in localized juvenile periodontitis

BACKGROUND

Neutrophils from patients with localized juvenile periodontitis (LJP) exhibit decreased binding and responsiveness to various chemotactic agents, including N-formyl-1-methionyl-1-leucyl-1-phenylalanine (FMLP). This altered reaction of neutrophils is thought to account in part for the increased susceptibility of LJP patients to infections by periodontal organisms. Receptors for FMLP are involved in the activation and the subsequent response to certain chemotactic stimuli.

METHODS

In order to determine if this decreased response is due to a genetic variation in the receptor, we directly compared DNA encoding the FMLP receptor from controls matched for gender and race and LJP patients by single-strand conformation polymorphism analysis (SSCP).

RESULTS

Using this technique, we observed a characteristic SSCP pattern in 29 out of 30 patient samples in the FMLP receptor DNA. This pattern differed from those obtained from the 20 control subjects as well as 31 patients with adult periodontitis. DNA sequencing of 30 patients indicated single nucleotide polymorphisms (SNPs) in the FMLP receptor DNA from the LJP patients when compared to 20 controls (P = 0.0005). Two single nucleotide base alterations were consistently seen: either a thymine to cytosine substitution at base 329 in 17 LJP patients or a cytosine to guanine substitution at base 378 in 5 LJP patients. A combination of both alterations were seen in 7 LJP patients. Both alterations resulted in amino acid changes in the second intracellular loop of the receptor, specifically phenylalanine to serine at residue 110 and cysteine to tryptophan at residue 126. This region of the FMLP receptor has recently been shown to play a role in ligand binding and G-protein activation.

CONCLUSIONS

This study suggests that a molecular alteration in the second intracellular loop of the FMLP receptor molecules in LP patients may play a role in the decreased chemotactic activity reported for some LJP patients.

Regression coefficient analysis of neutrophil chemotaxis in periodontitis

Micropore-filter techniques have been widely used to assess motility and chemotaxis of neutrophils. In some cases the results were impaired by inadequate methods of evaluation and failures of the test system. For clinical purposes the mode of test evaluation should be able to differentiate between failures of the test system (false-negative) and real functional defects (true-negative). A new method has been developed to check parallel assays for homogeneity. Based on earlier procedures this type of evaluation uses the comparison of regression coefficients to identify false-negative test results within the cell population of an individual. The newly developed method was used to study the chemotactic response in a group of 49 patients and 22 healthy volunteers. Intraclass correlation coefficients of the regression coefficient analysis and the leukotactic index were calculated and compared. It could be demonstrated that the regression coefficient analysis had the same sensitivity as the leukotactic index. Slight variations in the cell counts at a single plane of the chemotactic filter affecting the leukotactic index by 18% had no measurable influence on the calculated regression coefficient.

A potential role of an intracellular signaling defect in neutrophil functional abnormalities and promotion of tissue damage in patients with localized juvenile periodontitis

Localized juvenile periodontitis is a destructive form of periodontal inflammatory disease which has its onset at puberty. The etiopathology of the disease is still unclear but neutrophils have been suggested to play a major role both in the production and development of the disorder. About 70% of the patients with localized juvenile periodontitis exhibit neutrophil functional abnormalities, such as decreased chemotaxis and phagocytosis. Interestingly, it has been frequently reported that the same hypoactive cells show an enhanced respiratory burst response and increased adhesion. Several possible mechanisms explaining neutrophil anomalies in localized juvenile periodontitis have been proposed. These include the presence of soluble serum factors capable of modulating neutrophil function, altered cell-surface receptor expression and/or function, and a change in the post-receptor signaling events. Recently, a growing evidence has accumulated showing that the diacylglycerol metabolism could be altered in neutrophils from patients with localized juvenile periodontitis. This change, which may be due to a defect in a major diacylglycerol metabolizing enzyme, diacylglycerol kinase, results in enhanced accumulation of diacylglycerol in activated cells. Because diacylglycerol is an endogenous activator of protein kinase C, the increased and prolonged generation of diacylglycerol could lead to abnormal pattern of protein kinase C-regulated neutrophil functions, explaining the parallel hypo- and hyperactivities.

Neutrophil function in juvenile periodontitis: induction of adherence

Polymorphonuclear leukocytes (neutrophils) in patients with localized juvenile periodontitis with decreased chemotaxis exhibit increased adherence. The molecular basis of increased adherence of neutrophils in localized juvenile periodontitis is not clear. We show that the neutrophils from localized juvenile periodontitis patients with decreased neutrophil chemotaxis and increased adherence exhibit increased expression of the CD11/CD18 family of adherence molecules, Mac-1, leukocyte function-associated antigen (LFA-1) and p150,95, as compared with neutrophils obtained from systemically and periodontally healthy controls. Treatment of neutrophils obtained from healthy subjects with sera from localized juvenile periodontitis patients resulted in an increased expression of Mac-1, leukocyte function-associated antigen and p150,95 molecules. Sera obtained from health subjects, patients with adult periodontitis or localized juvenile periodontitis patients with normal chemotaxis did not increase the expression of CD11/CD18 molecules on the neutrophils obtained from healthy subjects. The ability of localized juvenile periodontitis sera to induce expression of adherence molecules was at least partially inhibited by pretreatment of localized juvenile periodontitis sera with anti-tumor necrosis factor and anti-interleukin-1 antibodies. Furthermore, increasing concentrations of rh-tumor necrosis factor-alpha and interleukin-1 beta also induced increased expression of the Mac-1 molecule on neutrophils from localized juvenile periodontitis patients and healthy subjects. The increased expression of adherence molecules on neutrophils from localized juvenile periodontitis patients was sustained and could not be reversed by treatment of localized juvenile periodontitis neutrophils with sera obtained from healthy subjects. The upregulation of adherence molecules on neutrophils by localized juvenile periodontitis sera in these experiments emphasizes the physiologic importance of quantitatively small but biologically significant levels of cytokines in the modulation of neutrophil functions in localized juvenile periodontitis.

Chemoluminescence generation and MTT dye reduction by polymorphonuclear leukocytes from periodontal disease patients

Alterations of polymorphonuclear leukocytes (PMNs) functions have been reported in patients with severe forms of some periodontal disease. In this study we evaluated the chemoluminescence generation and MTT dye reduction by human PMN in patients with juvenile periodontitis (JP), rapidly progressive periodontitis (RPP) and adult periodontitis (AP) during protein kinase C (PKC) activation or during the phagocytosis of opsonized zymosan. The results demonstrated that only PMNs of JP patients showed a decreased chemoluminescence generation and MTT dye reduction during the phagocytosis of opsonized zymosan (p < 0.05). The time to reach the maximal peak during the PKC activation on the chemoluminescence reaction was evaluated and JP PMNs patients demonstrated a depressed value (7.0 +/- 0.4 min) compared with healthy volunteers (13.8 +/- 0.5 min). The etiology and importance of such cellular alterations in the immunopathogenesis of the periodontal disease are discussed.