Effects of periodontopathic bacteria on IL-1 and IL-1 inhibitor production by human polymorphonuclear neutrophils

Innate immune response to oral bacteria and the immune evasive characteristics of periodontal pathogens

Periodontitis is a chronic inflammation of periodontal tissue caused by subgingival plaque-associated bacteria. Periodontitis has long been understood to be the result of an excessive host response to plaque bacteria. In addition, periodontal pathogens have been regarded as the causative agents that induce a hyperinflammatory response from the host. In this brief review, host-microbe interaction of nonperiodontopathic versus periodontopathic bacteria with innate immune components encountered in the gingival sulcus will be described. In particular, we will describe the susceptibility of these microbes to antimicrobial peptides (AMPs) and phagocytosis by neutrophils, the induction of tissue-destructive mediators from neutrophils, the induction of AMPs and interleukin (IL)-8 from gingival epithelial cells, and the pattern recognition receptors that mediate the regulation of AMPs and IL-8 in gingival epithelial cells. This review indicates that true periodontal pathogens are poor activators/suppressors of a host immune response, and they evade host defense mechanisms.

Ability of oral bacteria to induce tissue-destructive molecules from human neutrophils

AIM

The induction of tissue-destructive molecules from neutrophils by periodontopathic bacteria has been suggested as one of the mechanisms of periodontal destruction. The aim of this study was to determine whether the ability to stimulate neutrophils is an authentic characteristic of periodontopathic bacteria.

METHODS

We evaluated, along with phagocytosis, the production of reactive oxygen species (ROS), matrix metalloproteinase-8 (MMP-8), and interleukin-1beta by neutrophils in response to non-periodontopathic Streptococcus sanguinis and periodontopathic bacteria Fusobacterium nucleatum and Treponema denticola, in the absence or presence of antibodies. Phagocytosis, the death of neutrophils, and intracellular ROS production were measured by flow cytometry and the concentrations of MMP-8 and interleukin-1beta secreted into medium were determined by enzyme-linked immunosorbent assay.

RESULTS

S. sanguinis and F. nucleatum induced greater production of ROS, MMP-8, and interleukin-1beta than did T. denticola. The levels of tissue-destructive molecules produced by neutrophils had a positive correlation with phagocytosis. Opsonization of bacteria with antibodies significantly increased phagocytosis and ROS production and release, thus increasing both bacterial clearance and potential tissue damage.

CONCLUSION

The ability of oral bacteria to induce tissue-destructive molecules from neutrophils is not an inherent characteristic of periodontopathic bacteria, which would provide a new insight into the role of neutrophils in periodontal destruction.

Secretion of IL-1 beta, TNF-alpha, IL-8 and IL-1ra by human polymorphonuclear leukocytes in response to lipopolysaccharides from periodontopathic bacteria

Polymorphonuclear leukocytes (PMN) are the first cells that migrate into periodontal tissues and gingival crevices in response to invading pathogens. It was recently demonstrated that PMN have the ability to synthesize and release cytokines following appropriate stimulation, while it is not clear whether these capacities are directly related to periodontal destructive processes. We therefore investigated the amounts of the cytokines interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), IL-8 and IL-1 receptor antagonist (IL-1ra) secreted by PMN from healthy donors following stimulation with lipopolysaccharide (LPS) from 4 periodontopathic bacteria, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Capnocytophaga ochracea and Fusobacterium nucleatum, and the non-oral bacterium Escherichia coli. A actinomycetemcomitans, F. nucleatum and E. coli LPS stimulated the release of significantly greater amounts of IL-1 beta, TNF-alpha and IL-8 than the control unstimulated PMN (p < 0.01). The levels of IL-1 beta, TNF-alpha and IL-8 released from cells stimulated with P. gingivalis or C. ochracea LPS were significantly lower than those of cells stimulated with A. actinomycetemcomitans or E. coli LPS (p < 0.05). On the other hand, substantially greater amounts of IL-1ra were released from PMN stimulated with each LPS and from control unstimulated PMN during the first 6 h, and then significantly greater amounts of IL-1ra were secreted by PMN stimulated with A. actinomycetemcomitans and E.coli LPS during the following 12 h (p < 0.01). The inhibitory effects of IL-1ra on the biological activity of IL-1 in the supernatants of PMN were examined by the thymocyte comitogen proliferation assay. The supernatants of PMN stimulated with each LPS showed less biological IL-1 activity as compared with the same doses of recombinant human IL-1 beta detected by enzyme-linked immunosorbent assay. Furthermore, no activity was detected in the supernatants of PMN stimulated with P. gingivalis or C. ochracea LPS. These findings demonstrated that LPS from periodontopathic bacteria were capable of stimulating PMN to release not only pro-inflammatory cytokines but also their inhibitors such as IL-1ra. Different secretion levels of these cytokines and their biological activities induced by the various LPS might be important in the onset and progression of periodontal diseases.

Cytokine-inducing components of periodontopathogenic bacteria

Pro-inflammatory cytokines such as interleukin (IL)-1, IL-6, IL-8 and tumour necrosis factor (TNF) are believed to be the major pathological mediators of inflammatory diseases ranging from arthritis to the periodontal diseases. The stimuli inducing proinflammatory cytokine induction in the former disease is unclear but in the periodontal diseases it is obvious that the stimulus is the accumulation of bacteria in the subgingival region. As these bacteria do not invade the lesional tissues in large numbers, it is believed that their soluble components or products interact with host tissues to induce cytokine gene transcription. The paradigm is that lipopolysaccharide is the key bacterial component inducing pro-inflammatory cytokine gene expression. However, over the past decade a growing number of reports on non-oral bacteria have established that many other bacterial components, as well as secretory products, have the capacity to induce cytokine synthesis. Some of these, such as the protein pneumolysin from Streptococcus pneumoniae, are incredibly potent (in this case inducing cytokine synthesis at femtomolar concentrations). This review surveys the range of bacterial components and products which have been shown to stimulate cytokine synthesis with particular emphasis on the hypothesis that these components play a role in the pathology of the periodontal diseases.

Production of interleukin-1 by polymorphonuclear leukocytes resident in periradicular tissue

Twenty-one patients undergoing endodontic surgery were identified. Periradicular tissue samples were recovered, and those showing significant numbers of polymorphonuclear leukocyte (PMN) infiltration were prepared for immunoperoxidase identification of interleukin (IL)-1 alpha and IL-1 beta-producing cells using specific polyclonal antibodies. In selected tissue specimens, 90% or more of the PMN's were found to stain positively for IL-1 alpha and IL-1 beta. In addition, significant numbers of plasma cells and tissue histiocytes stained positively for these IL's. Cell suspensions from selected periapical granuloma specimens, as well as from purified peripheral blood PMN's and peripheral blood mononuclear cells, were also subjected to IL-1 quantitation using a commercial ELISA procedure. Such cell suspensions were found to produce significant levels of IL and could be stimulated to produce increased levels after coculture with lipopolysaccharide. These results suggest that PMN's in inflammatory periradicular tissues may be a significant source of IL-1, and their possible roles in the establishment and resolution of periradicular lesions need to be re-evaluated.

Physiopathology of primary periodontitis associated with plaque. Microbial and host factors. A review. Part 2

To a considerable extent, host factors condition the initiation and progression of periodontitis. The integrity of the periodontal structures and the immune elements in the gingival fluid may act as a defensive barrier against microorganisms. However, immune over-response may lead to tissue damage and bone resorption from anaphylactic reactions, immunocomplex reactions, type IV hypersensitivity, complement hyperactivation via the alternative pathway, or direct action of leukocytes and macrophages. Moreover, insufficient host response allows bacteria to escape control, allowing more rapid progression of the disease.

Cytokines and T cell switching

In recent years, the phenotypic characterization of T cell subsets has given way to a functional dichotomy based essentially on their cytokine profiles. In this context, the CD4+ helper T cell subset has been shown to consist of two types, termed Th1 and Th2. In general, Th1 cells produce interleukin (IL)-2 and interferon (IFN)-gamma, while Th2 cells characteristically produce IL-4, IL-5, and IL-6. The major function of the Th1 subset is to mediate delayed-type hypersensitivity reactions and their secondary function is suppression of B cell activity. In contrast, the major function of the Th2 subset is to provide B cell help, while their secondary function is cell-mediated immune suppression. A similar dichotomy has also been described for CD8+ T cells. The role that these functional T cell subsets and their cytokines play in terms of their protective and nonprotective outcomes in a variety of infectious and oral diseases is reviewed.

Immunopathogenesis of chronic inflammatory periodontal disease: cellular and molecular mechanisms

Recent studies of the cellular mechanisms involved in chronic inflammatory periodontal disease (CIPD) have contributed significantly to our understanding of the pathogenesis of the disease process. Functional studies have demonstrated polymorphonuclear neutrophil (PMN) chemotactic defects in some 70% of subjects with localized juvenile periodontitis while chemiluminescence data have suggested that peripheral blood PMNs from young subjects with adult periodontitis (AP) may be in a metabolically active state. Further studies have shown that stimulation of PMNs with a number of periodontopathic bacteria resulted in the production of an IL-1 inhibitor suggesting a possible regulatory role for PMNs in CIPD in addition to their established protective role. Most work on the immunoregulation of CIPD has, however, concentrated on T-cells. Recent limit dilution analysis has demonstrated the presence of periodontopathic bacteria-specific T cells in peripheral blood and the involvement and homing of these cells to the local lesions of CIPD is currently the focus of many studies. In animal studies, Actinobacillus actinomycetemcomitans (Aa)-specific T-cell clones home to the gingival tissues where they may exert a protective role. Homing and retention of lymphocytes to and in specific sites is dependent upon the expression of adhesion molecules. Recent data indicate however, that while there are increasing levels of ICAM-1, LECAM-1 and PECAM-1 expression with increasing degrees of inflammation, there are no differences between gingivitis and periodontitis lesions. Cytokine profiles may be related to the role of T-cell clones homing to the gingiva in CIPD.(ABSTRACT TRUNCATED AT 250 WORDS)

Marginal periodontitis and cytokines: a review of the literature

Recent research on the immunopathogenesis of marginal periodontitis has focused on cytokines, because these mediators govern biological activities in inflammatory tissue destruction. Several studies have been carried out to elucidate the involvement of cytokines in periodontitis, including cytokine measurements in samples from gingival tissue, gingival crevicular fluid, and in supernatants of stimulated in vitro grown cells from gingival tissue and peripheral blood. The results, summarized in this review, suggest that cytokines are involved in the progress of periodontitis. Furthermore, cytokines may be valuable as markers of tissue breakdown. At the present stage, however, there are difficulties in detecting and quantifying cytokines by immunochemical methods and, in particular, by bioassays. Increased knowledge of the cytokine network may open new pathways of periodontitis treatment by controlling processes involved in tissue breakdown.

Zinc in etiology of periodontal disease

Microbial plaque is the main etiological factor of periodontal disease. The bacterial polysaccharides stimulate gingival neutrophils and macrophages to interleukin-1 (IL-1) production. IL-1 causes a complex of redistribution processes with liver as the central organ. Accumulation of zinc in liver and their copper and ceruloplasmin production also elicits increase of copper and decrease of zinc in gingiva. The elevated level of copper in connection with zinc deficiency in gingiva causes the increase of permeability of gingival epithelium for bacteria. The stimulated inflammatory infiltrate produces more IL-1 and the vicious circle is complete.

Interleukin-1 beta (IL-1 beta) levels in gingival crevicular fluid from adults with previous evidence of destructive periodontitis. A cross sectional study

We have estimated the levels of Interleukin-1 beta (IL-1 beta) by ELISA in gingival crevicular fluid (GCF) at 58 sites from 37 patients with adult periodontitis. GCF was collected for 5 s on filter papers and a 2nd sample was collected for 30 s 1 min later. 68/116 strips yielded detectable levels of IL-1 beta. IL-1 beta was present in both the 1st and 2nd samples at 28 sites, in the 1st only at 4 sites and in the 2nd only at 8 sites; 18 sites were below the level of detection for the assay. When the concentrations of IL-1 beta were calculated in the original volume of GCF on each strip, the mean value for positive strips was 34.16 +/- 29.45 (SD) pg/microliters with a range from 1.75 to 97.13 pg/microliters. There were no statistically significant correlations with the plaque index, bleeding index or probable crevice depth (pocket depth). The results indicate that IL-1 is present in the GCF from a proportion of sites with evidence of previous periodontal destruction.