The effect of interleukin-1 beta on hyaluronic acid synthesized by adult human gingival fibroblasts in vitro

The role of endoplasmic reticulum stress in the pathophysiology of periodontal disease

The endoplasmic reticulum (ER) is a principal organelle for folding, post-translational modifications and transport of secretory, luminal, and membrane proteins. ER stress is a condition induced by the accumulation of unfolded or misfolded proteins owing to a variety of physiological and pathological phenomena. To overcome the deleterious effects of ER stress, unfolded protein response (UPR) is initiated to translocate and remove the misfolded and accumulated proteins. Plenty of evidence shows the correlation between ER stress/UPR and the pathology of inflammatory disease. Periodontal disease is a chronic inflammatory disease characterized by the irreversible destruction of periodontal tissues, which associates with the onset and progress of several systemic diseases. Periodontopathic bacterium and pro-inflammatory mediators play a pivotal role in the progress of periodontal disease. Besides, cigarette smoke has long been associated with periodontal disease. As an inflammatory disorder of the periodontium, periodontal disease is highly related to ER stress. In this review, we provide an overview of the pathophysiological effect of ER stress on periodontal disease through five aspects as follow: ER stress and periodontal tissue remodeling, including both soft tissue and hard tissue; ER stress and the inflammation; ER stress and systematic effect during the periodontal disease; last but not least, ER stress and the autophagic apoptosis in cells.

Hyaluronan-mediated mononuclear leukocyte binding to gingival fibroblasts

OBJECTIVES

Binding of mononuclear leukocytes to hyaluronan cable structures is a well-known pathomechanism in several chronic inflammatory diseases, but has not yet described for chronic oral inflammations. The aim of this study was to evaluate if and how binding of mononuclear leukocytes to pathologic hyaluronan cable structures can be induced in human gingival fibroblasts.

MATERIAL AND METHODS

Experiments were performed with human gingival fibroblasts and peripheral blood mononuclear cells (PBMCs) from three healthy blood donors. Gingival fibroblasts were stimulated with (1) tunicamycin, (2) polyinosinic/polycytidylic acid (Poly:IC), and (3) lipopolysaccharides (LPS) to simulate (1) ER stress and (2) viral and (3) bacterial infections, respectively. Fibroblasts were then co-incubated with PBMCs, and the number of bound and fluorescently labeled PBMCs was assessed using a fluorescence reader and microscopy. For data analysis, a linear mixed model was used.

RESULTS

Hyaluronan-mediated binding of PBMCs to gingival fibroblasts was increased by tunicamycin and Poly(I:C) but not by LPS. Hyaluronidase treatment and co-incubation with hyaluronan transport inhibitors reduced this binding.

CONCLUSIONS

Results suggest that hyaluronan-mediated binding of blood cells might play a role in oral inflammations. A potential superior role of viruses needs to be confirmed in further clinical studies.

CLINICAL RELEVANCE

The linkage between pathological hyaluronan matrices and oral infections opens up potential applications of hyaluronan transport inhibitors in the treatment of chronic oral inflammations.

Phenytoin-induced gingival overgrowth

Gingival overgrowth is a common adverse effect of therapy with Phenytoin, having important medical and cosmetic implications. Poor periodontal hygiene is an important risk factor for severity of Phenytoin-induced gingival overgrowth (PIGO), which is a time-dependent process. There is complex interplay of altered fibroblast biology, connective tissue turnover, inflammatory processes, and growth factors on a background of genetic susceptibility to produce increase in various components of interstitial matrix in PIGO tissue. Treatment options have included change of PHT to another anti-seizure drug, measures to improve periodontal hygiene and gingivectomy. There is conclusive evidence that folic acid supplementation significantly decreases the incidence of PIGO.

Phenytoin-mediated androgen metabolism in gingival fibroblasts. Effects of the antiandrogen finasteride and the alkaline phosphatase inhibitor levamisole

OBJECTIVES

This investigation attempts to identify the role of the alkaline phosphatase inhibitor levamisole (L) and the antiandrogen finasteride (F) on 5alpha-reductase activity in gingival fibroblasts, to elucidate mechanisms for phenytoin-induced gingival overgrowth.

MATERIAL AND METHODS

Human gingival fibroblasts were incubated with Eagle's MEM and 14C-testosterone/14C-4-androstenedione as substrates; effective concentrations of phenytoin (Ph), levamisole (L) and finasteride (F), alone and in combinations of (Ph + F) (Ph + L) were added to the incubate. After 24 h, the medium was analysed for steroid metabolites and quantified using a radioisotope scanner.

RESULTS

The metabolites isolated were 5alpha-dihydrotestosterone (DHT), 4-androstenedione (4-A) or testosterone (T) from each substrate. With 14C-T as substrate, Ph stimulated DHT synthesis by 1.7-fold, while F and L inhibited this activity by 1.8-fold and 34%, respectively (n = 6; P < 0.001). The combination of Ph + F reduced yields by 2.7-fold compared with Ph alone and Ph + L reduced DHT synthesis by 2.4-fold compared with Ph alone (n = 6; P < 0.001). When 14C-4-androstenedione was used as substrate, similar trends were identified.

CONCLUSION

These results suggest that the alkaline phosphatase inhibitor levamisole and the 5alpha-reductase inhibitor finasteride can substantially decrease the yields of DHT in fibroblasts, stimulated by phenytoin. This could be a potential target for reducing the gingival overgrowth caused by phenytoin.

Proinflammatory cytokines regulate the gene expression of hyaluronic acid synthetase in cultured rabbit synovial membrane cells

To elucidate the mechanism of accumulation and fragmentation of hyaluronic acid (HA) under inflammatory conditions, we investigated the effect of proinflammatory cytokines on hyaluronic acid synthetase (HAS) mRNA expression using cultured rabbit synovial membrane cells. HASs mRNA levels were determined by real-time PCR. HAS2 mRNA expression was maximally enhanced 3.3- and 2.8-fold after 3-hour stimulation with IL-1beta (1 ng/ml) and after 1-hour stimulation with TNF-alpha (10 ng/ml). HAS3 mRNA expression was increased by a maximum of 4.3 times after 3-hour stimulation with IL-1beta (10 ng/ml), whereas 1-hour stimulation with TNF-alpha (10 ng/ml) and IFN-gamma (10 ng/ml) induced around a 2.5-fold increase in HAS3 mRNA. Although IFN-gamma (1-100 ng/ml) alone showed little effect on HAS2 mRNA expression, the effect was synergized by combined with both IL-1beta and TNF-alpha, substantially increasing HAS2 mRNA expression. These results suggest that proinflammatory cytokines regulate the HAS expression, and consequently may contribute to the accumulation and fragmentation of HA.

The effects of human mast-cell products and of phenytoin on androgen 5alpha-reductase expression in human gingival fibroblasts

The aim was to elucidate mechanisms for phenytoin-induced gingival overgrowth, using effects of type 1 human mast cell (HMC-1) supernatant and histamine on the expression of 5alpha-reductase in human gingival fibroblasts (HGF), and the effects of phenytoin on this activity. Duplicate incubations of HGF in Eagle's minimum essential medium (MEM) were performed with [14C] testosterone and serial concentrations of mast-cell histamine (1-100 microgram/ml)/HMC-1 culture supernatant at serial dilutions of 1-100 microl/ml for 24 h. Other experiments employed optimal concentrations of HMC-1 supernatant (10 microl/ml) or histamine (8 microgram/ml) and phenytoin (1 and 5 microgram/ml), alone and in combination, using two androgen substrates, [14C] testosterone and [14C] 4-androstenedione. At the end of a 24-h incubation the medium was solvent-extracted for steroid metabolites, analysed and quantified in a radioisotope scanner. HMC-1, histamine (n=3) and phenytoin (n=6) significantly increased the synthesis of dihydrotestosterone and 4-androstenedione by up to 80% (P<0.01); the combination of HMC-1 and phenytoin caused two-fold increases (n=6; P<0.01). The incubations with histamine alone and in combination with phenytoin showed significant stimulation of dihydroxytestosterone and the diols alone and in combination, which was less pronounced in combination. This investigation demonstrates significant stimulation of 5alpha-reductase activity in human gingival fibroblasts by mast-cell supernatant and a specific product histamine, alone and in combination with phenytoin. Androgen 5alpha-reductase-mediated anabolic actions in connective tissue are well documented. The findings suggest a novel hypothesis that mast-cell mediated androgen action in the gingiva in response to phenytoin could contribute to gingival overgrowth.

Trichloroethylene activates CD4+ T cells: potential role in an autoimmune response

Trichloroethylene is an industrial solvent and has become a major environmental contaminant. Autoimmune-prone MRL +/+ mice were treated for up to 22 weeks with trichloroethylene in the drinking water (0, 2.5, and 5.0 mg/mL) in order to study the immunoregulatory effects of this environmental toxicant. After only 4 weeks of treatment, trichloroethylene was shown to promote the expansion of CD4+ T cells that expressed a memory/activation phenotype (i.e., CD44hi CD45RBlo) and secreted high levels of IFN-gamma, but not IL-4. In addition, trichloroethylene treatment accelerated the development of an autoimmune response in the MRL +/+ mice as evidenced by an earlier appearance of antinuclear antibodies and increased levels of total IgG2a. MRL +/+ mice treated with trichloroethylene for 22 weeks also contained antibodies specific for trichloroethylene adducts, suggesting the activation of trichloroethylene-specific T cells. The results suggest that trichloroethylene can stimulate antigen nonspecific as well as specific T cells that are capable of promoting autoimmunity in genetically predisposed individuals.

Medication induced gingival overgrowth

A number of idiopathic, pathological and pharmacological reactions may result in an overgrowth of the gingiva. This review concentrates on those overgrowths associated with various pharmacological agents. The pharmaco-kinetics and side effects of each drug associated with gingival overgrowth are discussed along with the clinical and histological features and treatment. By examining the possible pathogeneses for these overgrowths we propose a unifying hypothesis for the causation based around inhibition of apoptosis and decreased collagenase activity modulated by cytoplasmic calcium.

Immunoregulatory roles of adhesive interactions between lymphocytes and gingival fibroblasts

Chronic adult periodontitis is usually characterized by inflammatory cell accumulation in the extravascular periodontal connective tissue. In order to reveal how the lymphocyte migration and retention in periodontal lesions is regulated, we have focused on the molecular basis for the adhesive interactions between lymphocytes and human gingival fibroblasts (HGF). In this study, we investigated the involvement of cell adhesion molecules in adhesive interactions between lymphocytes and HGF. We found that activated lymphocytes bound strongly to HGF and VLA integrins, extracellular matrix receptors, play crucial roles in the binding. Interestingly, we first revealed that CD44 molecules (hyaluronate receptor) on lymphocytes also participated in lymphocyte-HGF interactions and that hyaluronate anchored on the surface of HGF functioned as the ligand for CD44. In addition, when HGF were stimulated with inflammatory cytokines such as IL-1, TNF alpha and IFN gamma, the binding avidity between lymphocytes and HGF was significantly increased and the adhesion was mainly mediated by LFA-1/ICAM-1 pathway. We then examined the possibility whether lymphocyte-HGF interaction may cause activation of HGF. When HGF directly interacted with lymphocytes for 3 h, IL-1 beta mRNA expression was clearly increased in HGF. These findings suggested that the adhesive interactions between lymphocytes and HGF was mediated at least by VLA integrins, LFA-1/ICAM-1 and CD44/hyaluronate and that the heterotypic cell-cell interactions could mutually cause intracellular signal transduction.

Lymphocyte-fibroblast interactions

Chronic inflammatory reactions are usually characterized by inflammatory cell accumulation in the extravascular connective tissue. In such sites, inappropriate activation of circulating or resident lymphocytes becomes self-perpetuating and can lead to chronic tissue destruction. In addition to that, the locally infiltrated lymphocytes should have an opportunity to interact directly with fibroblasts composing the connective tissue. The direct interactions of those different cell types seem to play important roles in lymphocyte lodging and retention in such sites. Thus, for clarification of the immunopathogenesis of the chronic inflammatory diseases, including periodontitis, it is important that the molecular mechanisms involved in the heterotypic cell-cell interactions be revealed. In fact, it has been demonstrated that lymphocytes interact with various non-hematopoietic cells, such as epithelial cells and endothelial cells. Regarding interactions with fibroblasts, it has been shown that IFN gamma-stimulated fibroblasts can regulate the proliferative responses of T-lymphocytes both positively and negatively. Furthermore, activated lymphocytes have demonstrated strong binding ability to various fibroblast cell lines. Blocking experiments utilizing monoclonal antibodies specific to various cell adhesion molecules revealed that very late antigen (VLA) integrins, lymphocyte-function-associated antigen (LFA-1)/intercellular adhesion molecule-1 (ICAM-I), CD44/hyarulonate are, at least in part, involved in lymphocyte-fibroblast interactions. In addition, recent findings raised the possibility that the adhesive interactions between lymphocytes and fibroblasts influenced the various cellular functions of each cell type. In fact, it was recently demonstrated that the adhesive interactions stimulated fibroblasts to increase expression of inflammatory cytokine mRNA. These results strongly suggest that fibroblasts are not merely innocent bystanders but actively participate in local inflammatory reactions by directly interacting with locally infiltrated lymphocytes.

Cyclosporin A upregulates prostaglandin E2 production in human gingival fibroblasts challenged with tumor necrosis factor alpha in vitro

The effect of cyclosporin A (CsA) on prostaglandin E2 (PGE2) production in human gingival fibroblasts challenged with tumor necrosis factor alpha (TNF-alpha) was studied. TNF-alpha (1-100 ng/ml) dose-dependently stimulated PGE2 formation in 24 h cultures. CsA (1-100 ng/ml) did not induce PGE2 formation itself but potentiated TNF-alpha induced PGE2 formation in gingival fibroblasts in a manner dependent on the concentrations of both CsA and TNF-alpha. TNF-alpha (10 ng/ml) stimulated the release of [3H]-arachidonic acid (AA) from prelabelled fibroblasts that was potentiated by CsA (100 ng/ml). Addition of exogenous unlabelled AA (5-20 microM/ml) to the cells resulted in enhanced PGE2 formation that was not potentiated by CsA (100 ng/ml). Furthermore, CsA (100 ng/ml) did not further increase the level of cyclooxygenase-2 mRNA induced by TNF-alpha (10 ng/ml), although PGE2 formation was enhanced. The results indicate that CsA and TNF-alpha act in concert on PGE2 formation in gingival fibroblasts, which may be of importance in the pathogenesis of gingival overgrowth induced by the drug.

Interleukin-1 beta and phenytoin reduce alpha 1 (I) procollagen mRNA expression in human gingival fibroblasts

Effects of and interactions between interleukin-1 beta (IL-1 beta) and phenytoin (PHT) on alpha 1 (I) procollagen gene and protein expression in human gingival fibroblasts and its relation to prostaglandin E2 (PGE2) formation were studied. IL-1 beta (300 pg/ ml) reduced the steady-state level of alpha 1 (I) procollagen mRNA by 50% and decreased the amount of procollagen I by 35%. PHT (10 micrograms/ml) reduced the level of alpha 1 (I) procollagen mRNA by 40% but the amount of procollagen I in the medium was unchanged. In combination with IL-1 beta, PHT potentiated the inhibitory effect of IL-1 beta on alpha 1 (I) procollagen mRNA level that was accompanied by an increased PGE2 formation. Preincubation with indomethacin (10(-6) M) partially reduced the inhibitory effect of IL-1 beta as well as of IL-1 beta in combination with PHT on the mRNA level of alpha 1 (I) procollagen. The inhibitory effect of PHT was unaffected by indomethacin treatment. Addition of exogenous PGE2 (> or = 10 nM) dose-dependently reduced steady-state level of alpha 1 (I) procollagen mRNA as well as the amount of procollagen 1. The study indicates that IL-1 reduces the expression of alpha 1 (I) procollagen mRNA in human gingival fibroblasts partly by a prostaglandin endoperoxide (PGH) synthase-mediated pathway and partly by a PGH-synthase independent pathway, whereas PHT reduces alpha 1 (I) procollagen gene expression by a PGH-synthase independent pathway. The potentiation of the inhibitory effect of IL-1 induced by PHT was mediated mainly by a PGH-synthase dependent pathway.

CD44-hyaluronate interaction participates in the adherence of T-lymphocytes to gingival fibroblasts

It has already been clarified that peripheral blood T-lymphocytes which had been activated with phorbol 12-myristate 13-acetate (PMA) acquired the ability to bind to human gingival fibroblasts (HGF) and that the adherence was mediated by VLA integrins. However, these studies also raised the possibility that molecules other than VLA integrins should be involved in the adherence between T-lymphocytes and HGF. In this study, the possible involvement of CD44, a hyaluronate receptor, in heterotypic cell-cell interactions was investigated. It was confirmed that PMA-activated T-lymphocytes strongly adhered to plate-coated hyaluronate and that the hyaluronate binding was clearly inhibited by the addition of OS/37, a newly established mAb specific for the hyaluronate-binding epitope on CD44. Interestingly, OS/37 also blocked the HGF binding of the activated T-lymphocytes when the adherence to HGF was assessed at 4 degrees C, at which temperature the adhesion of integrin molecules diminished, while that of CD44 functioned normally. Immunofluorescence staining revealed that hyaluronate was anchored along the cell surface of HGF. Furthermore, the binding of activated T-lymphocytes to HGF was significantly inhibited by the treatment of HGF with hyaluronidase. These results clearly demonstrated that CD44-hyaluronate interactions participated at least in part in the adhesiveness of T-lymphocytes to HGF.

The effect of interleukin-1 (IL-1) on androgen metabolism in human gingival tissue (HGT) and periodontal ligament (PDL)

Due to the potent anabolic effects of the androgenic metabolite 5 alpha- dihydrotestosterone (DHT) on matrix synthesis by connective tissue and bone, it was pertinent to investigate the effects of interleukin-1 (IL-1) on androgen metabolism by chronically inflamed human gingival tissue (HGT) and periodontal ligament (PDL). Duplicate incubations of HGT and PDL derived from 6 subjects (age- and sex-matched) were performed in Eagle's MEM+FCS with 14C-testosterone to study baseline conversion to DHT and 4-androstenedione. Similarly further incubations were performed for 24 h in a 5% CO2 in air incubator, with HGT and PDL from 4 comparable patients to study the effect of IL-1 on this conversion. The medium was extracted radioactive metabolites separated by thin-layer chromatography and quantified. When baseline metabolism of HGT was compared with that of PDL, both tissues metabolised 14C-testosterone to DHT and 4-androstenedione. There was a 2.4-fold increase in DHT synthesis by PDL over that of HGT (n = 6; p < 0.005) and a 2.5-fold increase in 4-androstenedione formation by PDL compared with HGT (n = 6; p < 0.01). In response to IL-1, HGT demonstrated a 2-fold increase in DHT synthesis (n = 4; p < 0.005) and a 3.5-fold increase in 4-androstenedione formation (p < 0.01) over control gingival tissue; PDL showed a 9-fold increase in DHT synthesis in response to IL-1 (n = 4; p < 0.005) and a 6-fold increase in 4-androstenedione formation (p < 0.005) over control ligament tissue. The increased androgen metabolic capacity of PDL over HGT, both at baseline and in response to IL-1 is in keeping with protein studies and may be relevant to repair processes during inflammatory periodontal disease.

Effect of phenytoin on interleukin-1 beta production in human gingival fibroblasts challenged to tumor necrosis factor alpha in vitro

Effects and interaction of tumor necrosis factor alpha (TNF alpha) and the antiepileptic drug phenytoin (PHT) on interleukin-1 beta (IL-1 beta) production as well as on prostaglandin E2 (PGE2) formation were studied in gingival fibroblasts in vitro. TNF alpha, in contrast to PHT, dose-dependently stimulated the production of cell-associated IL-1 beta. The stimulatory effect of TNF alpha on IL-1 beta production was accompanied by enhanced PGE2 formation. When PHT and TNF alpha were added simultaneously, the drug potentiated the stimulatory effect of TNF alpha on both IL-1 beta production and PGE2 formation. The major PHT metabolite, p-HPPH, did not affect IL-1 beta production, either alone or in combination with TNF alpha. The production of IL-1 beta induced by TNF alpha and the combination of TNF alpha and PHT was further enhanced in the presence of the prostaglandin endoperoxide (PGH) synthase inhibitors, indomethacin and flurbiprofen. The PHT-mediated enhancement of TNF alpha-induced IL-1 beta production and PGE2 formation in gingival fibroblasts may be an important link in the pathogenesis of gingival overgrowth induced by PHT.

Prostaglandin E2 inhibits interleukin-6 release but not its transcription in human gingival fibroblasts stimulated with interleukin-1 beta or tumor necrosis factor-alpha

Inflammatory mediators produced by human gingival fibroblasts (HGF) have been implicated in the initiation and progression of periodontal disease. The purpose of this study was to examine whether prostaglandin E2 (PGE2), which is produced in abundance from HGF after stimulation with interleukin (IL)-1 beta or tumor necrosis factor-alpha (TNF-alpha), could regulate IL-6 production by HGF. HGF stimulated with either IL-1 beta or TNF-alpha showed a rapid and dose-dependent increase in IL-6 mRNA accumulation and IL-6 secretion, as demonstrated by reverse transcription-polymerase chain reaction analysis and bioassay. IL-6 secretion from either IL-1 beta- or TNF-alpha-stimulated HGF was enhanced by the inhibition of PGE2 synthesis with indomethacin. Furthermore, the addition of PGE2 inhibited IL-6 secretion from these cells. In contrast, indomethacin or PGE2 did not affect the accumulation of IL-6 mRNA in IL-1 beta-stimulated HGF. These data indicate that IL-6 production by HGF is up-regulated by specific cytokines, IL-1 beta and TNF-alpha, and suggest that this production may be partially down-regulated by endogenous and exogenous PGE2 at the post-transcriptional level.

Interleukin-1 beta concentration of gingival crevicular fluid

The concentration of interleukin-1 beta is elevated in inflamed gingival tissue. Therefore a method for the measurement of interleukin-1 beta (Il-1 beta) in gingival crevicular fluid (GCF) using a commercially available Il-1 beta ELISA was developed. GCF was collected with periopaper strips and 4 protocols of sampling using filter paper strips were tested; the method with a recovery rate of 111.9% (SD: +/- 14.5%) was chosen for subsequent analysis of all samples. Il-1 beta concentration in GCF of periodontitis patients and a healthy control group was determined. Patients (n = 19, mean age: 29.3 years) had not been treated. The healthy control group (n = 14, mean age: 22.8 years) showed, after a hygiene regimen of 2 weeks, no clinical signs of gingival/periodontal inflammation. Probing depth, clinical attachment level, bleeding upon probing, and a modified plaque index were recorded. Il-1 beta could be detected in all GCF samples. The concentration ranged between 22.8 ng/ml and 150 ng/ml in the healthy control group and between 85.8 ng/ml and 882.2 ng/ml in the periodontitis patients. No sex-related differences were noted. According to our present results the determination of GCF Il-1 beta concentration is possible using commercially available test kits if the principle of sample preparation is adapted to the specific requirements of GCF analysis.

Epidermal growth factor potentiates interleukin 1 and tumor necrosis factor-induced prostaglandin biosynthesis in human gingival fibroblasts

The effects of and interactions between epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha) interleukin 1 (IL-1) and tumour necrosis factor alpha (TNF-alpha) on arachidonic acid release and prostaglandin biosynthesis in human gingival fibroblasts were studied. IL-1 alpha, IL-1 beta and TNF-alpha, but not EGF nor TGF-alpha, stimulated prostaglandin E2 (PGE2) formation in the gingival fibroblasts. The effect of IL-1 alpha, IL-1 beta and TNF-alpha on PGE2 formation was significantly potentiated by EGF in a dose-dependent manner. Similarly, TGF-alpha synergistically potentiated IL-1 beta stimulated PGE2 formation. IL-1 beta but not EGF stimulated the release of 3H-arachidonic acid (3H-AA) from prelabelled gingival fibroblasts. In contrast to the effect on PGE2 formation, no synergistic interaction between EGF and IL-1 was seen on arachidonic acid (AA) release. Addition of unlabelled exogenous AA, in the presence of EGF, resulted in a significant increase in PGE2 formation compared to that seen in fibroblasts not exposed to EGF. The results demonstrate that EGF and IL-1 as well as EGF and TNF-alpha act in concert to enhance prostanoid formation in gingival fibroblasts. Data indicates that EGF potentiates the IL-1 and TNF-alpha induced PGE2 formation at the level of prostaglandin endoperoxide synthase (cyclooxygenase). The synergistic effects of inflammatory cytokines and growth factors may be of physiological importance for regulation of regenerative tissue growth during inflammation and repair.

The phenytoin metabolite p-HPPH upregulates prostaglandin biosynthesis in human gingival fibroblasts challenged to interleukin-1

The effects of and interactions between the major phenytoin (PHT) metabolite 5-parahydroxyphenyl-5-phenylhydantoin (p-HPPH) and interleukin-1 (IL-1 alpha, IL-1 beta) or tumor necrosis factor alpha (TNF alpha) on prostaglandin biosynthesis in human gingival fibroblasts were studied. IL-1 alpha, IL-1 beta and TNF alpha, dose-dependently, stimulated PGE2 formation in gingival fibroblasts. The metabolite, p-HPPH (1.2-2.4 micrograms/ml), did not induce PGE2 formation itself but potentiated IL-1 alpha and IL1 beta induced PGE2 formation in the gingival fibroblasts in a manner dependent on the concentration of both IL-1 and p-HPPH. The metabolite also stimulated IL-1 induced formation of 6-Keto PGF1 alpha, the stable breakdown product of PGI2, in a dose dependent manner. IL-1 beta induces release of [3H]-arachidonic acid ([3H]-AA) from prelabelled fibroblasts, which was potentiated by p-HPPH (> or = 1.2 micrograms/ml). TNF alpha (> or = 1 ng/ml) significantly stimulated the biosynthesis of PGE2 by a process that was also potentiated by p-HPPH. Addition of exogenous, unlabelled AA (10 microM) caused an increase of PGE2 formation in the fibroblasts that was not potentiated by p-HPPH (1.6 micrograms/ml). The results indicate that treatment with p-HPPH results in upregulation of prostaglandin synthesis in gingival fibroblasts challenged to IL-1 or TNF alpha at the level of phospholipase A2.

Enhanced prostaglandin biosynthesis in human gingival fibroblasts isolated from patients treated with phenytoin

Prostaglandin E2 (PGE2) formation was studied in human gingival fibroblasts derived from three epileptic patients before and after 9 months of phenytoin (PHT) therapy. Interleukin 1 (IL-1 alpha; 0.3-6.0 ng/ml), (IL-1 beta; 10-1000 pg/ml) and tumour necrosis factor (TNF alpha; 0.01-0.1 microgram/ml) dose-dependently stimulated the formation of PGE2 in 24 h cultures. In fibroblasts, derived after 9 months of PHT therapy, IL-1 alpha, IL-1 beta and TNF alpha induced a significantly higher formation of PGE2 compared to that in fibroblasts derived before PHT therapy. IL-1 beta induced a significantly higher release also of 3H-arachidonic acid (3H-AA) from prelabelled PHT fibroblasts compared to that in prelabelled gingival fibroblasts isolated before the drug therapy. Addition of exogenous AA caused a spontaneous increase of PGE2 formation in PHT fibroblasts compared to that in fibroblasts isolated before the PHT treatment. The results indicate that PHT medication results in an upregulation of prostanoid formation in gingival fibroblasts partly due to an increased phospholipase A2 activity and partly due to an increased cyclooxygenase activity.

Phenytoin potentiates interleukin-1-induced prostaglandin biosynthesis in human gingival fibroblasts

1. The effect of phenytoin (PHT) on prostaglandin E2 (PGE2) biosynthesis in human gingival fibroblasts stimulated by interleukin-1 (IL-1 alpha, IL-1 beta) or by tumour necrosis factor alpha (TNF alpha) was studied. 2. IL-1 alpha (1.5-6.0 ng ml-1) and IL-1 beta (30-300 pg ml-1), dose-dependently, stimulated PGE2 formation, in 24 h cultures, with IL-beta being the most potent agonist. 3. PHT (2.5-20 micrograms ml-1) did not induce PGE2 formation itself but potentiated IL-1 alpha- and IL-1 beta-induced PGE2 formation in the gingival fibroblasts in a manner dependent on the concentrations of both IL-1 and PHT. 4. IL-1 beta (0.1-1.0 ng ml-1) induced release of [3H]-arachidonic acid ([3H]-AA) from prelabelled fibroblasts that was potentiated by PHT (20 micrograms ml-1). 5. TNF-alpha (greater than or equal to 0.01 micrograms ml-1) significantly stimulated the biosynthesis of PGE2 by a process that was potentiated by PHT. 6. Addition of exogenous arachidonic acid (AA) (greater than or equal to 1 microM) caused an increase of PGE2 formation in the fibroblasts that was not potentiated by PHT (20 micrograms ml-1). 7. The results indicate that treatment with PHT results in upregulation of prostaglandin biosynthesis in gingival fibroblasts challenged with IL-1 or TNF alpha, at least partly due to enhanced level of phospholipase A2 activity.

Lipopolysaccharide stimulation of hyaluronate synthesis by human gingival fibroblasts in vitro

Exposure of gingival fibroblasts to LPS caused a dose-dependent increase in hyaluronate synthesis. Stimulation of hyaluronate synthesis by LPS was significantly greater 24 h after exposure and by 48 h an approx. 50% increase was evident. In parallel, there was an increase in the activity of the hyaluronate synthetase enzyme. Inhibition of PGE2 synthesis by indomethacin abolished the stimulatory effect of LPS on hyaluronate synthesis. Thus, this stimulatory effect of LPS on hyaluronic acid synthesis may be a secondary response to the induction of PGE2. The molecular size of newly synthesized hyaluronate was not affected by LPS. The metabolic changes observed may be a primary response of the cells to bacterial toxins and may aid extracellular matrix repair.

Interleukin-1 beta- and tumor necrosis factor-alpha-independent monocyte stimulation of fibroblast collagenase activity

To investigate the mechanism of cyclosporine (Cs)-induced fibrous gingival enlargement, the indirect effects of Cs on fibroblast collagenolysis via the drug's effect on the synthesis of the fibroblast regulatory monokines interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF alpha) have been studied. Peripheral blood monocytes stimulated with lipopolysaccharide (LPS) for 48 h produced conditioned media (MCM-LPS) that contained 665 pg/ml IL-1 beta and 16 pg/ml TNF alpha and significantly (P less than 0.001) enhanced the collagenase activity of a fibroblast strain (GN 23) derived from a healthy individual with clinically normal gingiva. The concurrent addition of Cs (50, 100, or 150 ng/ml) with LPS to the monocytes (MCM-LPS-Cs) significantly diminished their ability to enhance GN 23 collagenase activity in a dose-dependent manner, with MCM-LPS-Cs (150 ng/ml) causing the greatest effect. Cs also significantly inhibited IL-1 beta and TNF alpha production. Although the greatest inhibition of both cytokines was at 50 ng/ml Cs, the corresponding MCM-LPS-Cs caused the least diminution (16%) of the collagenase stimulation caused by MCM-LPS (no Cs). This suggested that factor(s) other than or in addition to IL-1 beta and TNF alpha might be responsible for the stimulation of GN 23 collagenase activity. MCM-LPS depleted of IL-1 beta by affinity chromatography retained its stimulatory effect on GN 23 collagenolysis, and human recombinant IL-1 beta and TNF alpha, when tested alone or together at levels found in the stimulatory MCM-LPS and MCM-LPS-Cs, did not stimulate GN 23 collagenase activity as did the crude conditioned media. This evidence suggested that the conditioned media contained the complex mixture of cytokines necessary to stimulate collagenase activity of this fibroblast strain and that IL-1 beta and TNF alpha were not necessarily involved. Cs may alter the synthesis of other collagenase-stimulating cytokines, accounting for the diminished ability of Cs-treated monocytes to enhance collagenase activity of susceptible fibroblast strains. Decreased collagenase activity, therefore, resulting from Cs suppression of monokine production, may be an important factor in the development of fibrous gingival enlargement seen in some susceptible patients treated with Cs.

Sera of children with renal tumours contain low-molecular-mass hyaluronic acid

The molecular mass of hyaluronic acid (HA) rather than its serum concentration alone may be a hallmark of certain types of malignancy. A radiometric assay was used to measure HA levels in 35 children with renal tumours [33 Wilms' tumours and 2 bone metastasizing renal tumours of childhood (BMRTC)] and 20 normal siblings of children with cancer. The HA level in the sera of normal children was barely detectable and had a molecular mass of 1-5 x 10(5). In both Wilms' and BMRTC patients, very high levels of HA were found in preoperative serum samples; these fell dramatically following surgical excision of the tumours. A novel finding of our study was the presence of low-molecular-mass HA (similar to the angiogenic fragments of HA) in the sera of BMRTC patients. In contrast, high-molecular-mass HA (which is not angiogenic) was found in the sera of Wilms' patients (2 x 10(6) kDa). Following surgery in BMRTC patients, not only did serum HA levels fall to a value within normal ranges, but also the HA which remained was of high molecular mass.

Effects of interleukin-1 on fibroblast extracellular matrix, using a 3-dimensional culture system

This study describes the alterations induced by Interleukin-1 alpha and -beta (IL-1 alpha and IL-1 beta) on fibroblast-synthesized extracellular matrix. Fibroblasts were grown between pieces of dentin or in collagen-coated Terasaki wells for 3 or 6-9 weeks to create 3-dimensional cell-containing matrices constituted primarily of proteoglycans and collagens, respectively. Following incubation with IL-1 alpha or IL-1 beta (10(-9) M) at 37 degrees C for 24 or 72 hr, samples were prepared for light and electron microscopy. Both IL-1 alpha and IL-1 beta induced collapse of the extracellular matrix by 72 hr, as manifested by a decrease of the cross-sectional area and an increased density of the matrices. Three-week matrices were reduced 26% and 45% by using IL-1 alpha and IL-1 beta, respectively. Comparable values obtained by using 6-week matrices were 14% and 30%. Cells within the matrix, normally stellate in shape with numerous extended processes, attained a more rounded or spindle shape with few and reduced processes and showed apparent alterations at cell matrix attachment sites and rearrangement of the cytoskeleton. Elongated cells at the top of the matrix appeared more compressed. The alterations were more pronounced in cultures incubated with IL-beta than with IL-1 alpha. Immunocytochemistry of extracellular matrix components revealed a decrease in staining intensity of chondroitin and dermatan sulfate in the 3-week matrix following IL-1 beta incubation. There was also a decrease in collagen type 1 staining of 9-week matrices treated with IL-1 alpha or IL-1 beta. These studies show that IL-1 has an effect on fibroblast-synthesized extracellular matrix and indicate that the effects of IL-1 alpha and IL-1 beta may differ. The resulting collapse of the matrix appears at least in part to be due to changes in proteoglycans and collagens.