Induction of intracellular interleukin-1 beta signals via type II interleukin-1 receptor in human gingival fibroblasts

Biological Roles of Fibroblasts in Periodontal Diseases

Periodontal diseases include periodontitis and gingival overgrowth. Periodontitis is a bacterial infectious disease, and its pathological cascade is regulated by many inflammatory cytokines secreted by immune or tissue cells, such as interleukin-6. In contrast, gingival overgrowth develops as a side effect of specific drugs, such as immunosuppressants, anticonvulsants, and calcium channel blockers. Human gingival fibroblasts (HGFs) are the most abundant cells in gingival connective tissue, and human periodontal ligament fibroblasts (HPLFs) are located between the teeth and alveolar bone. HGFs and HPLFs are both crucial for the remodeling and homeostasis of periodontal tissue, and their roles in the pathogenesis of periodontal diseases have been examined for 25 years. Various responses by HGFs or HPLFs contribute to the progression of periodontal diseases. This review summarizes the biological effects of HGFs and HPLFs on the pathogenesis of periodontal diseases.

Interleukin-1 receptor gene variants are associated with aggressive periodontitis in the Japanese

OBJECTIVE

Previous studies have indicated that type-1 and type-2 interleukin-1 (IL-1) receptors (IL-1R1 and IL-1R2) play important roles in periodontitis progression. We investigated the association between periodontitis and polymorphisms in the IL-1R1 and IL-1R2 genes (IL1R1 and IL1R2).

DESIGN

We searched for genetic variants in IL1R1 and IL1R2 in 24 Japanese patients with aggressive periodontitis (AgP) and 24 periodontally healthy controls. Thirty-eight single nucleotide polymorphisms (SNPs) were identified within genomic regions containing all exons and relevant exon-intron boundaries in IL1R1 and IL1R2. Possible associations of each gene locus with AgP were investigated in 119 AgP patients and 102 periodontally healthy controls using allelotypes, genotypes, and haplotypes.

RESULTS

Significant differences were noted in the frequencies of 3 SNPs in IL1R2 (rs3819370, rs3218974 and rs3218977) for AgPs and controls (p=0.012, p=0.008, and p=0.038, respectively), after adjustment for gender and smoking status in the additive model (p=0.016, p=0.007, and p=0.027, respectively) and 2 haplotypes (p=0.010 and p=0.011, respectively) constructed from 2 SNPs (rs3819370 and rs3218974) that showed the lowest p-values after adjustment of covariates in additive models.

CONCLUSION

A genetic susceptibility locus for AgP may lie within or close to the IL1R2 locus. Further studies in other populations are necessary to confirm these results.

The role of Desulfovibrio desulfuricans lipopolysaccharides in modulation of periodontal inflammation through stimulation of human gingival fibroblasts

OBJECTIVE

Periodontitis is a destructive disease which is likely to be the result of the activities of different microbial complexes. Recently, sulphate-reducing bacteria (SRB) have been detected in the oral cavity, and they have been found to be common inhabitants of sites showing periodontal destruction. The aim of study was to evaluate the influence of endotoxins of Desulfovibrio desulfuricans bacteria on human gingival fibroblast HGF-1 line.

METHODS

The immunological response of gingival fibroblasts was evaluated by determination of their IL-6 and IL-8 secretion upon treatment with D. desulfuricans intestinal and type strain LPS, sodium butyrate (NaB) and IL-1beta. The amounts of cytokines were estimated by ELISA immunoassay. The influence of LPS and NaB on fibroblast proliferation was determined using the CyQUANT Cell Proliferation Assay Kit.

RESULTS

No significant growth inhibition of cells exposed to LPS was observed, except for the culture growing in the presence of intestinal strain endotoxin at the highest concentration (100 microg/ml). The secretion of IL-6 and IL-8 by fibroblasts was increased by D. desulfuricans endotoxins. Cells stimulated with proinflammatory cytokine 1L-1beta showed very high levels of both cytokines secretion. The release of IL-6 and IL-8 by cells in response to LPS and 1L-1beta was modulated by butyric acid.

CONCLUSIONS

The observed response of gingival fibroblasts to stimulation by endotoxin suggests that D. desulfuricans can be involved in the pathogenesis of periodontitis. Moreover, butyrate present in the oral cavity seems to have immunoregulatory effect on cytokine production by gingival fibroblasts under physiological conditions and during microbe-induced inflammation.

Ovarian cancer cells stimulate uPA gene expression in fibroblastic stromal cells via multiple paracrine and autocrine mechanisms

OBJECTIVES

Expression of uPA mRNA is massively up-regulated in the stroma of poorly differentiated ovarian tumors. We hypothesized that this expression was induced by paracrine signals from the epithelial tumor cells, and established an in vitro model of ovarian cancer microenvironment to study intercellular cross-talk.

METHODS

ES-2 clear cell carcinoma cells were grown in tissue culture inserts in a double-chamber system with fibroblastic stromal LEP cells embedded in Matrigel. Binding-site directed antibodies were used to neutralize soluble cytokines in ES-2 conditioned medium (CM) before incubation with LEP cells. Real time PCR measured uPA mRNA in LEP cells, as well as mRNA for cytokines in both cell types.

RESULTS

Co-culture with ES-2 cells as well as incubation with ES-2 CM induced uPA mRNA in LEP cells about two-fold. In short time (12 h) incubation of LEP cells with CM, antibodies to EGF and bFGF reduced induction of uPA mRNA, suggesting that these cytokines function as paracrine signals. EGF mRNA and bFGF mRNA were also found in ES-2 cells. At longer incubation (24 h) antibodies to bFGF, HB-EGF, HGF, IGF-1, and IL-1alpha reduced uPA mRNA induction, suggesting an autocrine function for these cytokines in LEP cells. In fact, expression of the same five cytokines was up-regulated in LEP cells exposed to CM.

CONCLUSION

We identified two cytokines as paracrine signals, and five cytokines as autocrine signals in ovarian cancer cell induced up-regulation of uPA mRNA in stromal fibroblastic cells. It is crucial to understand intra-tumoral cross-talk, since it can offer new therapeutic approaches.

Three Promoters Regulate Tissue- and Cell Type-specific Expression of Murine Interleukin-1 Receptor Type I

The type 1 interleukin-1 receptor (IL-1R1) mediates diverse functions of interleukin-1 (IL-1) in the nervous, immune, and neuroendocrine systems. It has been suggested previously that the versatile functions of IL-1 may in part be conferred by the multiple promoters of IL-1R1 that have been identified for the human IL-1R1 gene. Promoters for murine IL-1R1 (mIL-1R1) gene have not been studied in detail. We performed 5'-rapid amplification of cDNA ends to determine the transcription start sites (TSS) in mIL-1R1, using mRNAs derived from 24 different tissues. The results revealed three putative TSSs of mIL-1R1. Three full-length cDNAs containing these distinct TSSs were recovered in screens of cloned cDNA libraries. Translation of these cDNAs produced IL-1R1 proteins that were verified by Western blot analysis. IL-1 stimulation of the individual IL-1R1 proteins resulted in the activation of NF-kappaB. Promoter-reporter assay for genomic DNA sequences immediately upstream of the three TSSs validated that the sequences possess promoter activity in a cell type-specific manner. These promoters are termed P1, P2, and P3 of the mIL-1R1, in 5' to 3' order. Quantitative PCR analysis of P1-, P2-, and P3-specific mIL-1R1 mRNAs showed that there is tissue-specific distribution of these mRNAs in vivo, and there are distinct patterns of P1, P2, and P3 mRNA expression in different cell lines. In the brain, P3 mRNA is expressed preferentially in the dentate gyrus. Further, glucocorticoids differentially regulate these promoters in a cell type-specific manner. Together, these results suggest that the different IL-1R1 promoters contribute to the discrete and diverse actions of IL-1.

The contribution of interleukin-1 and tumor necrosis factor to periodontal tissue destruction

Interleukin (IL)-1 and tumor necrosis factor (TNF) represent proinflammatory cytokines that stimulate a number of events which occur during periodontal disease. These include the induction of adhesion molecules and other mediators that facilitate and amplify the inflammatory response, the stimulation of matrix metalloproteinase, and bone resorption. The activity of these cytokines coincides with the critical events that occur during periodontal disease, namely, loss of attachment and bone resorption. The use of antagonists to IL-1 and TNF in experimental periodontitis have demonstrated a cause-and-effect relationship between the activity of these cytokines and the spread of an inflammatory front to deeper areas in the connective tissue, loss of connective tissue attachment, osteoclast formation, and loss of alveolar bone. In addition, the loss of fibroblasts that occurs during infection with periodontal pathogens is, in part, mediated by TNF. Thus, much of the damage that occurs during periodontal tissue destruction can be attributed to IL-1 and TNF activity. This destruction may very well represent an overreaction of the host response to periodontal pathogens caused by excessive production of IL-1 and TNF.

Perspective of cytokine regulation for periodontal treatment: fibroblast biology

Efforts to understand the pathogenesis of periodontal diseases have been underway for decades. Studies of immunological aspects in addition to the structural components of gingival fibroblasts showed that the fibroblasts actively participate in immune and inflammatory events in periodontal diseases. Future strategies for the prevention and treatment of periodontal diseases should biologically regulate fibroblast activities. These cells are surrounded by monocyte-derived proinflammatory cytokines such as interleukin-1 beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and lymphocyte-derived interleukin-6 (IL-6) in inflamed gingival tissue. Recent anti-cytokine therapy for inflammatory diseases including rheumatoid arthritis aimed to inhibit the binding of cytokines to targeted cells such as fibroblasts and condrocytes. IL-1beta and TNF-alpha are thought to be therapeutic targets because these cytokines are essential for the initiation of inflammatory immune reactions and are produced for prolonged periods in inflammatory diseases. IL-6 is also a target, because it is abundantly present in inflammatory lesions and activates fibroblasts in the presence of soluble IL-6 receptor. In addition, these cytokines accelerate gingival fibroblasts to produce collagenolytic enzymes, resulting in tissue destruction. Soluble receptors for IL-1beta and TNF-alpha are suggested to be candidates for therapeutic molecules, but soluble receptor for IL-6 is suggested to be a factor-stimulating fibroblast. This paper will review the utilization of soluble receptors specific to inflammatory cytokines which potentially stimulate fibroblasts to regulate biological events involved in the pathogenesis of periodontal diseases.

Cytokines and inflammatory pathways in the pathogenesis of multiple organ failure following abdominal aortic aneurysm repair

Multiple organ failure is a common mode of death following abdominal aortic aneurysm repair, particularly after rupture. Cytokines are the principal mediators of the inflammatory response to injury and high levels of circulating cytokines have been associated with poor outcome in major trauma and sepsis. Abdominal aortic aneurysm repair results in an ischaemia-reperfusion injury to the tissues distal to the site of aortic clamping. The inflammatory response in these tissues causes the release of cytokines, principally Interleukins 1-beta, 6, and 8, and Tumour Necrosis Factor alpha. If released in large enough concentrations, these cytokines may enter the circulation and gain access to organs distant to the site of initial injury. Circulating cytokines cause dysfunction of the renal, cardiovascular, respiratory, nervous and musculo-skeletal systems. The combination of these individual changes in organ function is the multiple-organ dysfunction syndrome, which may progress to multiple organ failure.