Humoral immune responses in periodontal disease may have mucosal and systemic immune features.
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The humoral immune response, especially IgG and IgA, is considered to be protective in the pathogenesis of periodontal disease, but the precise mechanisms are still unknown. Immunoglobulins arriving at the periodontal lesion are from both systemic and local tissue sources. In order to understand better the local immunoglobulin production, we examined biopsy tissue from periodontitis lesions for the expression of IgM, IgG, IgA, IgE and in addition the IgG and IgA subclasses and J-chain by in situ hybridization. Tissues examined were superficial inflamed gingiva and the deeper granulation tissue from periodontal sites. These data confirm that IgM, and IgG and IgA subclass proteins and J-chain can be locally produced in the periodontitis tissues. IgG1 mRNA-expressing cells were predominant in the granulation tissues and in the gingiva, constituting approx. 65% of the total IgG-expressing plasma cells. There was a significantly increased proportion of IgA-expressing plasma cells in the gingiva compared with the granulation tissue (P < 0.01). Most of the IgA-expressing plasma cells were IgA1, but a greater proportion expressed IgA2 mRNA and J-chain mRNA in the gingival tissues (30.5% and 7.5%, respectively) than in the periodontal granulation tissues (19% and 0-4%, respectively). The J-chain or dimeric IgA2-expressing plasma cells were located adjacent to the epithelial cells, suggesting that this tissue demonstrates features consistent with a mucosal immune response. Furthermore, we were able to detect the secretory component in gingival and junctional epithelial cells, demonstrating that the periodontal epithelium shares features with mucosal epithelium. In contrast, deeper tissues had more plasma cells that expressed IgM, and less expressing IgA, a response which appears more akin to the systemic immune response. In conclusion, this study suggests that immune mechanisms involved in the pathogenesis of periodontitis may involve features of both the mucosal and systemic immune systems, dependent on tissue location. (+info)
Neutrophil dysfunctions, IL-8, and soluble L-selectin plasma levels in rapidly progressive versus adult and localized juvenile periodontitis: variations according to disease severity and microbial flora.
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We used flow cytometry to analyze the expression of adhesion molecules and the oxidative burst of whole-blood polymorphonuclear neutrophils (PMN) from 26 patients with periodontitis. Three different clinical entities were studied: adult periodontitis (AP), localized juvenile periodontitis (LJP), and rapidly progressive periodontitis (RPP). Unstimulated PMN from the patients showed reduced Lewis x, sialyl-Lewis x, and L-selectin expression relative to those from healthy control subjects. These alterations were present whatever the severity of periodontal disease. However, PMN from RPP patients showed increased basal H2O2 production and decreased L-selectin shedding. These latter impairments, which correlated with increased IL-8 plasma levels, could contribute to initial vascular damage. In addition, decreased IL-8 priming of H2O2 production by PMN from RPP patients could account for a lower bactericidal capacity of PMN, leading to the large number of bacteria in the subgingival region of RPP patients. Soluble L-selectin plasma levels were also decreased in the RPP group, indicating more severe or diffuse endothelial damage. These abnormalities were not found in the patients with less destructive forms of periodontitis (AP and LJP). Porphyromonas gingivalis, a bacterial pathogen known to increase IL-8 production by PMN, was found in the periodontal pockets of RPP patients only. These results show links among PMN abnormalities, the clinical form of periodontitis, and the gingival bacterial flora. (+info)
Localisation of a gene for prepubertal periodontitis to chromosome 11q14 and identification of a cathepsin C gene mutation.
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Prepubertal periodontitis (PPP) is a rare and rapidly progressive disease of young children that results in destruction of the periodontal support of the primary dentition. The condition may occur as part of a recognised syndrome or may occur as an isolated finding. Both autosomal dominant and recessive forms of Mendelian transmission have been reported for PPP. We report a consanguineous Jordanian family with four members affected by PPP in two nuclear sibships. The parents of the affected subjects are first cousins. We have localised a gene of major effect for PPP in this kindred (Zmax=3.55 for D11S901 at theta=0.00) to a 14 cM genetic interval on chromosome 11q14 flanked by D11S916 and D11S1367. This PPP candidate interval overlaps the region of chromosome 11q14 that contains the cathepsin C gene responsible for Papillon-Lefevre and Haim-Munk syndromes. Sequence analysis of the cathepsin C gene from PPP affected subjects from this Jordanian family indicated that all were homozygous for a missense mutation (1040A-->G) that changes a tyrosine to a cysteine. All four parents were heterozygous carriers of this Tyr347Cys cathepsin C mutation. None of the family members who were heterozygous carriers for this mutation showed any clinical findings of PPP. None of the 50 controls tested were found to have this Tyr347Cys mutation. This is the first reported gene mutation for non-syndromic periodontitis and shows that non-syndromic PPP is an allelic variant of the type IV palmoplantar ectodermal dysplasias. (+info)
Regulation of immunoglobulin G2 production by prostaglandin E(2) and platelet-activating factor.
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Patients with localized juvenile periodontitis (LJP) have elevated levels of immunoglobulin G2 (IgG2) in their sera. This is also observed in vitro when peripheral blood leukocytes from LJP patients are stimulated with pokeweed mitogen. In previous studies, we showed that lymphocytes from subjects with no periodontitis (NP subjects) produced substantial amounts of IgG2 when they were cultured with monocytes from LJP patients (LJP monocytes). These observations indicate that monocytes or monocyte-derived mediators are positive regulators of the production of IgG2. The present study was initiated to determine if secreted factors from LJP monocytes were capable of enhancing IgG2 production and to determine if prostaglandin E2 (PGE(2)), which LJP monocytes produce at elevated levels, enhances IgG2 production. Experiments in a transwell system and with monocyte-conditioned media indicated that cell-cell contact was not necessary for LJP monocytes to augment the production of IgG2 by T and B cells from NP subjects. Moreover, the production of IgG2 was selectively induced by the addition of PGE(2) or platelet-activating factor (PAF), another lipid cytokine, which can elevate PGE(2) synthesis. Furthermore, IgG2 production was abrogated when cells were treated with indomethacin, a cyclooxygenase inhibitor that blocks the synthesis of PGE(2), or the PAF antagonists CV3988 and TEPC-15. The effects of indomethacin were completely reversed by PGE(2), indicating that this is the only prostanoid that is essential for the production of IgG2. Similarly, PGE(2) reversed the effects of a PAF antagonist, suggesting that the effects of PAF are mediated through the induction of PGE(2) synthesis. Together, these data indicate that PGE(2) and PAF are essential for the production of IgG2. (+info)
Th1 and Th2 cytokine profile in patients with early onset periodontitis and their healthy siblings.
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Early onset periodontitis (EOP) is a chronic inflammatory periodontal disease with a strong genetic link affecting individuals aged 17 to 25. In the familial studies we tested the hypothesis about the role of Th1 and Th2 cytokines in the pathogenesis of EOP disease. The study involved 6 individuals with EOP disease and their 6 siblings with healthy periodontium. Actinobacillus actinomycetemcomitans (A. a), a bacterium typical for EOP, was detected in all people studied. Th1 and Th2 cytokine production was measured after in vitro stimulation. Peripheral blood mononuclear cells (PBMC) were isolated and cultivated for 24 h and 7 days with PWM, A. a. or Escherichia coli. The levels of IL-4, IFN-gamma, IgA, IgG and IgM were measured by ELISA methods. After in vitro stimulation of PBMC, a significantly higher production of IL-4 and significantly lower production of IFN-gamma were found in the group of patients compared with their healthy siblings. The increased level of IL-4 in patients was in good agreement with an increased level of IgM after stimulation of lymphocytes with E. coli. These results support Seymour's hypothesis according to which patients with progressive disease primarily activate Th2 lymphocytes while non-susceptible individuals activate Th1 lymphocytes. (+info)
Beyond the specific plaque hypothesis: are highly leukotoxic strains of Actinobacillus actinomycetemcomitans a paradigm for periodontal pathogenesis?
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Actinobacillus actinomycetemcomitans is a facultative anaerobe implicated in a variety of periodontal diseases. Its presence is most closely associated with localized juvenile periodontitis (LIP), although the exact role of the organism in this and other periodontal diseases is not entirely clear. While A. actinomycetemcomitans produces several different putative virulence factors, the most widely studied is the leukotoxin. The leukotoxin selectively kills polymorphonuclear leukocytes and macrophages in vitro, constituting the host's first line of defense. Interestingly, even though all strains of A. actinomycetemcomitans have the genes encoding the leukotoxin, there is variability in leukotoxin expression. Differences in the structure of the promoter region of the leukotoxin gene operon were shown to correlate directly with levels of leukotoxin production. Highly leukotoxic forms appear to exhibit increased pathogenic potential, as evidenced by recent studies that have shown a significant association between the prevalence of such strains and the occurrence of LIP in several different populations. This represents the first demonstration of an association between a particular subset of a pathogenic species and a specific periodontal disease. Early identification of A. actinomycetemcomitans by microbial and genetic assays to evaluate leukotoxicity may enhance the efficacy of preventive and/or therapeutic techniques. Future investigations should continue to evaluate pathogenic variations of additional virulence factors expressed in vivo, not only of A. actinomycetemcomitans, but also of other periodontal bacteria and infectious disease pathogens. (+info)
Defective Gi protein coupling in two formyl peptide receptor mutants associated with localized juvenile periodontitis.
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The formyl peptide receptor (FPR) is a prototypical chemoattractant receptor expressed in neutrophils. It is well known that the FPR couples to G(i) proteins to activate phospholipase C, chemotaxis, and cytotoxic cell functions, but the in vivo role of the FPR in man has remained elusive. Recently, F110S and C126W mutations of the FPR have been associated with localized juvenile periodontitis. We studied FPR-F110S and FPR-C126W in comparison with wild-type FPR (FPR-WT) by coexpressing epitope-tagged versions of these receptors with the G protein Galpha(i2)beta(1)gamma(2) in Sf9 insect cells. FPRs were efficiently expressed in Sf9 membranes as assessed by immunoblotting using the beta(2)-adrenoreceptor as a standard. FPR-C126W differed from FPR-WT and FPR-F110S in migration on SDS-polyacrylamide gels and tunicamycin-sensitive glycosylation. FPR-WT efficiently reconstituted high-affinity agonist binding and agonist- and inverse agonist-regulated guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) binding to Galpha(i2)beta(1)gamma(2). In contrast, FPR-F110S only weakly reconstituted agonist-stimulated GTPgammaS binding, and FPR-C126W was completely inefficient. Collectively, our data show almost complete and complete loss of G(i) protein coupling in FPR-F110S and FPR-C126W, respectively. The severe functional defects in FPR-F110S and FPR-C126W contrast with the discrete clinical symptoms associated with these mutations, indicating that loss of FPR function in host defense is, for the most part, readily compensated. (+info)
Population structure and genetic diversity of Actinobacillus actinomycetemcomitans strains isolated from localized juvenile periodontitis patients.
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The phylogeny of 20 Actinobacillus actinomycetemcomitans strains isolated from patients with localized juvenile periodontitis (LJP) was investigated by using partial sequence analysis of 16S rRNA genes, arbitrarily primed PCR (AP-PCR), and four additional PCR assays that amplified polymorphic regions in the leukotoxin (lkt), cytolethal distending toxin (cdt), major fimbrial subunit (flp-1), and serotype-specific O polysaccharide gene clusters. Our analysis also included four strains isolated from healthy subjects and nine reference strains. We found that A. actinomycetemcomitans strains comprised three major phylogenetic lineages. One lineage consisted of serotype b strains, a second lineage consisted of serotype c strains, and a third lineage consisted of serotype a, d, e, and f strains. 16S rRNA sequences within each lineage were highly conserved (<1% base substitutions), whereas sequences between lineages were exceptionally divergent (1.9 to 5.0% substitutions). Two strains exhibited 16S rRNA sequences that were even more distantly related to those of the three major lineages (2.7 to 6.7% substitutions), indicating that additional minor lineages or variants exist. The distribution of 16S rRNA sequences and lkt, cdt, flp-1, and AP-PCR genotypes was consistent with a clonal population structure, with little evidence of assortative recombination between strains of different serotypes. Strains from all three major lineages were recovered from LJP patients, suggesting that phylogenetically diverse strains of A. actinomycetemcomitans carry pathogenic potential. (+info)