Enhanced cytokine production and collagen synthesis of gingival fibroblasts from patients with denture fibromatosis

Antioxidants protect against gingival overgrowth induced by cyclosporine A

OBJECTIVE

We investigated the importance of reactive oxygen species (ROS) on developing gingival overgrowth (GO) and then introduced the antioxidant strategy to prevent, or even reduce GO.

BACKGROUND

Gingival overgrowth is a common side effect of the patients receiving cyclosporine A (CsA), an immune suppressant. Although it has been broadly investigated, the exact pathogenesis of the induced GO is still uncertain.

METHODS

We cultured human primary gingival fibroblasts and used animal model of GO to investigate the ameliorative effects of antioxidants on CsA-induced GO. To examine the CsA-induced oxidative stress, associated genes and protein expression, and the overgrown gingiva of rats by using immunocytochemistry, confocal laser scanning microscopy, real-time PCR, ELISA, gelatin zymography, gingival morphological, and immunohistochemical analysis.

RESULTS

We found for the first time that ROS was responsible for the CsA-induced oxidative stress and TGF-β1 expression in human primary gingival fibroblasts, as well as the GO of rats. The antioxidants (oxidative scavenger of vitamin E and an antioxidative enzyme inducer of hemin) ameliorated CsA-induced pathological and morphological alterations of GO without affected the CsA-suppressed il-2 expression in rats. CsA-induced oxidative stress, HO-1, TGF-β1, and type II EMT were also rescued by antioxidants treatment.

CONCLUSIONS

We concluded that CsA repetitively stimulating the production of ROS is the cause of CsA-GO which is ameliorated by treating antioxidants, including vitamin E and sulforaphane. Furthermore, the immunosuppressive effect of CsA is not interfered by antioxidant treatments in rats. This finding may thus help the clinician devise better prevention strategies in patients susceptible to GO.

Mechanism of Cyclosporine-induced Overgrowth in Gingiva

Cyclosporine A (CsA) is a widely used immunosuppressant but with significant side-effects, such as gingival overgrowth. This study investigates how CsA induces gingival proliferation and shows the effects of the CsA-associated signaling messengers, IL-6 and TGF-β1, on gingival proliferation. CsA increased both IL-6 and TGF-β1 levels. In addition to CsA, an IL-6 or TGF-β1 treatment also induced gingival fibroblast proliferation. Inhibiting the cytokine resulted in the suppression of CsA-induced proliferation. MAPKs and PI3K are known to be involved in cell proliferation. Therefore, the effect of CsA on the kinase activities was examined. The results showed that both p38 MAPK and PI3K are essential for gingival fibroblast proliferation. TGF-β1 and IL-6 and their associated signaling transduction may be novel bona fide molecular targets for the prevention of gingival overgrowth in CsA-treated patients. (Abbreviations: MAPK, mitogen-activated protein kinase; PI3K, phosphatidylinositol 3-kinase.)

Proliferative and inductive effects of Cyclosporine a on gingival fibroblast of child and adult

Background:

Gingival overgrowth is a serious side-effect that accompanies the use of Cyclosporin A (CsA). Up to 97% of the transplant recipient children, who were submitted to CsA therapy, have been reported to suffer from this side-effect. Several conflicting theories have been proposed to explain the fibroblast's function in CsA-induced gingival overgrowth. The aim of this study is to assess the proliferation of gingival fibroblasts and levels of released cytokines after being exposed to CsA, in both adults and pediatric groups, and to make a comparison between the results of the two groups.

Materials and Methods:

The adult fibroblast samples were derived from four healthy adults, aged 35 to 42 years and pediatric samples were obtained from four healthy children, age between four and eleven years. Tissue samples were plated in Dulbecco's Modified Eagle Medium (DMEM) containing 10% fetal bovine serum (FBS), Streptomycin and Penicillin. The samples were cultured in 25 cm² plates containing 5% CO2, and incubated at 37°C. The cells used for all the experiments were at the fourth passage. The concentration of PGE₂, IL-1β, IL-6, IL-8, TNF-α, and TGF-β₁ was determined by the enzyme-linked immunosorbent assay (ELISA) and the proliferation rate was assessed by the MTT assay. Alpha error levels were set as 0.05.

Results:

CsA stimulated significantly higher levels of IL-6, IL-8 and TGF-β₁ in adult gingival fibroblasts than it did in the control group; whereas, the expression of IL-1β and PGE₂ in the fibroblasts exposed to CsA was significantly weaker (P < 0.05). The fibroblasts in the two groups did not reveal any noticeable difference in the production of TNF-α. Furthermore, cell proliferation in the CsA group was not significantly higher than that in the control group. No significant differences in cytokines TNF-α and IL-1β were noted between the two groups. The results indicated that CsA stimulated cell proliferation in the pediatric fibroblast cell line. Comparison between the results in the adult and pediatric groups demonstrated that the levels of IL-1β, IL-6, IL-8, and PGE₂ were significantly higher in the pediatric group than in the adult group; however, statistics showed no significant difference in the levels of TNF-α and TGF-β₁ and CsA-induced proliferation between these two groups.

Conclusions:

The mechanism of a CsA-induced fibroblast overgrowth may converge on the steps involving fibroblast proliferation and cytokine network including IL-6, IL-8, IL-1β, TGF-β₁, and PGE₂, in both adults and pediatrics. As the prevalence and intensity of drug-induced gingival overgrowth is more serious in the pediatrics. As group than in adults, we suggest that more studies be conducted on the pediatric group.

Peripheral blood mononuclear cells enhance the anabolic effects of platelet-rich plasma on anterior cruciate ligament fibroblasts

Use of platelet-rich plasma (PRP) has shown promise in various orthopaedic applications, including treatment of anterior cruciate ligament (ACL) injuries. However, various components of blood, including peripheral blood mononuclear cells (PBMCs), are removed in the process of making PRP. It is yet unknown whether these PBMCs have a positive or negative effect on fibroblast behavior. To begin to define the effect of PBMCs on ACL fibroblasts, ACL fibroblasts were cultured on three-dimensional collagen scaffolds for 14 days with and without PBMCs. ACL fibroblasts exposed to PBMCs showed increased type I and type III procollagen gene expression, collagen protein expression, and cell proliferation when the cells were cultured in the presence of platelets and plasma. However, addition of PBMCs to cells cultured without platelets had no effect. The increase in collagen gene and protein expression was accompanied by an increase in IL-6 expression by the PBMCs with exposure to the platelets. Our results suggest that the interaction between platelets and PBMCs leads to an IL-6 mediated increase in collagen expression by ACL fibroblasts.

Expression of TNF-α and RANTES in drug-induced human gingival overgrowth

Objectives:

Regulated on activation, normal T cell expressed and secreted (RANTES) is a chemokine that is produced by fibroblasts, lymphoid and epithelial cells of the mucosa in response to various external stimuli. RANTES expression has been demonstrated in a variety of diseases characterized by inflammation, including asthma, transplantationassociated accelerated atherosclerosis, endometriosis and fibrosis. RANTES mRNA is quickly up-regulated by tumor necrosis factor (TNF)-α stimulation. Cyclosporine A (CsA) is widely used in organ transplant patients, often causing various side-effects including gingival overgrowth, which is fibrotic in nature. This study was carried out to assess the mRNA expression of TNF-α and RANTES in healthy individual, chronic periodontitis and CsAinduced gingival overgrowth tissues.

Materials and Methods:

Gingival tissue samples were collected from chronic periodontitis, CsAinduced gingival overgrowth patients and healthy individuals. Total RNA was isolated and reverse transcription polymerase chain reaction (RT-PCR) was performed for TNF-α and RANTES expression.

Results:

The results suggest that CsAinduced gingival overgrowth tissues expressed significantly increased TNF-α and RANTES compared to control and chronic periodontitis.

Conclusion:

The findings of the present study suggest that CsA can modify the expression of TNF-α and RANTES in drug-induced human gingival overgrowth.

p38 MAPK and NF-κB on IL-6 Release in Human Gingival Fibroblasts

The induction of interleukin-6 (IL-6) using a proinflammatory cytokine (IL-1beta) was studied in human gingival fibroblasts (HGFs) in relation to p38 MAPK and NF-kappaB transcription factor. When added to HGFs, IL-1beta had a stimulatory effect on the production of IL-6, and this effect was significantly reduced by SB203580, a specific p38 MAPK inhibitor. In addition, the stimulation of IL-6 release also was reduced by the addition of pyrrolidine dithiocarbamate or NF-kappaB SN50, which has been reported as potent NF-kappaB inhibitor. Both the NF-kappaB inhibitors in the presence of SB203580 had more inhibitory effect on IL-6 release. IL-13 stimulated NF-kappaB binding affinity as well as p38 MAP kinase activation, leading to the release of IL-6. However, a specific inhibitor of p38 MAPK, SB203580, had no effect on the NF-kappaB activation, and both the NF-kappaB inhibitors failed to reduce the p38 MAPK activation in the IL-1beta-stimulated HGFs. These results strongly suggest that both p38 MAPK and NF-kappaB are required in IL-1beta-induced IL-6 synthesis and that these two IL-1beta-activated pathways can be primarily dissociated.

Retinoic acid-inducible gene-I is induced in gingival fibroblasts by lipopolysaccharide or poly IC: possible roles in interleukin-1beta, -6 and -8 expression

Retinoic acid-inducible gene-I (RIG-I) is a member of the DExH family of proteins, and little is known of its biological function in the oral region. We previously reported that interleukin 1beta (IL-1beta) induced RIG-I expression in gingival fibroblasts. In this study, we studied the mechanism of RIG-I expression induced by lipopolysaccharide (LPS) or double-stranded RNA (dsRNA) in gingival fibroblasts. We also addressed the role of RIG-I in the expression of IL-1beta, IL-6 and IL-8 in gingival fibroblasts stimulated with LPS or dsRNA. We stimulated cultured human gingival fibroblasts with LPS or dsRNA, and examined the expression of RIG-I mRNA and protein. The effect of cycloheximide, a protein synthesis inhibitor, on RIG-I induction by these stimuli was examined. The expression of IL-1beta, IL-6 and IL-8 in gingival fibroblasts transfected with RIG-I cDNA stimulated with LPS or dsRNA was examined. LPS or dsRNA induced the expression of mRNA and protein for RIG-I in concentration- and time-dependent manners. We also examined the localization of RIG-I, and found that it was expressed in cytoplasm. Cycloheximide did not suppress the LPS or dsRNA-induced RIG-I expression. Introduction of RIG-I cDNA into gingival fibroblasts resulted in enhanced expression of IL-1beta, IL-6 and IL-8; moreover, overexpression of RIG-I stimulated with LPS or dsRNA synergistically increased expression of IL-1beta, IL-6 and IL-8. RIG-I may have important roles in the innate immune response in the regulation of IL-1beta, IL-6 and IL-8 expression in gingival fibroblasts in response to LPS and dsRNA.

Alterations in the vascular extracellular matrix of granulocyte macrophage colony-stimulating factor (GM-CSF) -deficient mice

GM-CSF takes part in the cytokine network regulating the metabolism of extracellular matrix (ECM) during atherogenesis. Since data also point to an effect of GM-CSF on the vascular ECM in general, the vascular collagenous matrix was studied in wild-type and GM-CSF-deficient mice. Histological examination revealed a disorganized vascular ECM in GM-CSF-deficient mice involving the collagenous matrix and elastic fiber system. As shown by electron microscopy, collagen bundles were disrupted and reduced. The diameter of fibrils varied widely. mRNA expression of collagens and related molecules was studied. Fibrillar collagens were markedly reduced, alpha1(I)procollagen to 16.5% of control levels alpha1(III)procollagen was abolished whereas the expression level of network-forming alpha1(VIII)procollagen was not altered. As shown by in situ hybridization, the number of collagen-expressing cells was reduced. Matrix metalloproteinases and their inhibitor 1 were not affected by GM-CSF deficiency. Our studies demonstrate that GM-CSF plays a major role in the cytokine network regulating the metabolism of vascular collagens. GM-CSF deficiency leads to an altered composition of the vascular collagenous matrix, i.e., reduced amount of fibrillar collagen, altered ratio of fibrillar and network-forming collagen, and failures in the fibrillogenesis. We suggest that GM-CSF is a basic requirement for the maintenance of vessel wall integrity and resilience.

Synergistic enhancement of collagenous protein synthesis by human gingival fibroblasts exposed to nifedipine and TNF-alpha in vitro

BACKGROUND

Gingival overgrowth occurs in patients receiving nifedipine. Gingival inflammation may be an etiologic factor.

METHODS

Gingival fibroblasts were either exposed to (i) 0-500 ng/ml TNF-alpha or 10(-7) M nifedipine or (ii) 0-500 ng/ml TNF-alpha + 10(-7) M nifedipine for 7 days. 3H-proline was used to quantify collagenous protein synthesis.

RESULTS

Both TNF-alpha and 10(-7) M nifedipine significantly decreased cell proliferation, and 10(-7) M nifedipine + 500 ng/ml TNF-alpha reversed these effects. Collagenous protein synthesis was significantly reduced by TNF-alpha and was significantly enhanced by either 10(-7) M nifedipine or 5-500 ng/ml TNF-alpha + 10(-7) M nifedipine.

CONCLUSIONS

Our data report that nifedipine reverses the primary effects of TNF-alpha on collagenous protein synthesis. Patients with gingivitis could be susceptible to gingival overgrowth during nifedipine therapy as a result of synergistic effects of these agents on fibroblast metabolism, which occurs irrespective of reduced cell numbers.

Interleukin (IL)-1 and Porphyromonas gingivalis lipopolysaccharide stimulation of IL-6 production by fibroblasts derived from healthy or periodontally diseased human gingival tissue

BACKGROUND

Human gingival fibroblasts (HGF) play a key role in tissue repair and destruction. These cells express low levels of interleukin (IL)-6 constitutively and increased levels after stimulation with lipopolysaccharide (LPS) or the cytokines IL-1 and tumor necrosis factor-alpha (TNF-alpha). However, little information is available on IL-6 production by fibroblasts derived from diseased tissue. The present study compared constitutive and induced IL-6 production by human gingival fibroblasts (HGF) derived from healthy and diseased periodontal tissue. We also evaluated whether IL-1 acted in a synergistic manner with LPS in inducing IL-6 production by HGF and whether LPS acted via CD14.

METHODS

HGF derived from healthy and diseased tissue and foreskin fibroblasts were grown to confluency, photographed, and counted, and their constitutive IL-6 production was quantitated by ELISA. Healthy and diseased HGF were also pretreated with IL-1alpha, followed by incubation with Porphyromonas gingivalis or Escherichia coli LPS. Culture supernatants were assessed for IL-6 protein by ELISA and cell lysates for mRNA by reverse transcription-polymerase chain reaction (RT-PCR). In order to determine if LPS stimulation was mediated through the LPS receptor, CD14, surface receptors on HGF were assessed by flow cytometry and the total RNA CD14 mRNA was assessed.

RESULTS

Higher quantities of IL-6 were produced by the diseased HGF before and after stimulation than by the healthy HGF. Pretreatment with IL-1alpha followed by LPS stimulation of the healthy and diseased HGF cell lines resulted in an additive effect on IL-6 production. Pretreatment with IL-1alpha followed by a second incubation with the same stimulant produced higher amounts of IL-6 than cultures incubated with LPS alone or following IL-1alpha pretreatment. Similar amounts of IL-6 mRNA were present in unstimulated HGF from either diseased or healthy tissue and in those incubated with IL-1alpha only. After incubation with IL-1alpha and LPS, diseased HGF produced slightly more mRNA than healthy HGF. CD14 was not expressed by healthy or diseased HGF even after stimulation with either P. gingivalis or E. coli LPS. CD14 message was also undetectable.

CONCLUSIONS

Taken together, these results indicate heterogeneity among gingival fibroblasts and an additive effect of IL-1 and P. gingivalis LPS on IL-6 production by HGF. Furthermore, the LPS effect on HGF was not mediated by CD14.

Fibroblast heterogeneity of signal transduction mechanisms to complement-C1q. Analyses of calcium mobilization, inositol phosphate accumulation, and protein kinases-C redistribution

Fibroblasts of healthy and granulation gingiva are phenotypically heterogeneous with regard to binding C1q collagen-like (cC1qR) or C1q globular-heads (gC1qR) regions, respectively. Here, isolated fibroblast subsets, expressing either the cC1qR or the gC1qR phenotype, were stimulated with C1q, and assessed for changes in cytosolic free calcium [Ca2+]i, accumulation of inositol trisphosphate (IP3), and redistribution of Ca2+-dependent protein kinases-C (cPKCs) from cytosol to membranes. Changes in [Ca2+]i were determined using Indo-1 fluorescence in combination with adhering cell analysis and sorting (ACAS) cytometry. Accumulation of IP3 was quantified using a competitive radioreceptor binding assay. Redistribution of cPKCs was evaluated by immunoblotting with antibodies to PKCalpha/betaI-betaII/gamma. Subsets manifested different fluctuations in [Ca2+]i levels 20 seconds after C1q-stimulation in the presence of millimolar concentrations of external calcium. Whereas cC1qR fibroblasts responded with a 38% over baseline [Ca2+]i increase which was sustained for 20 to 30 minutes, gC1qR fibroblasts responded with a higher (264% over baseline) and more rapid (2 to 3 minutes) transient. Likewise, subsets exhibited different kinetics of IP3 accumulation. Whereas cC1qR fibroblasts responded with an IP3 increase of 32 +/- 3 pmol/10(4) cells over baseline after 5 seconds stimulation, gC1qR fibroblasts responded after 15 to 20 seconds with a lower increase (13 +/- 0.8 IP3 pmol/10(4) cells over baseline). Subsets differed in cPKCs redistribution which peaked in gC1qR-membranes 30 seconds after stimulation and remained sustained between 10 and 30 minutes. No cPKC redistribution was detectable in stimulated cC1qR-cells. We conclude that fibroblasts are heterogeneous in phosphoinositide-Ca2+ signaling and cPKC redistribution to C1q, and suggest that these differences may affect activities of normal and granulation gingiva.

The role of IL-6 in the pathogenesis of periodontal disease

The mechanisms underlying periodontal disease involve complex interactions between bacterial products, host cells and locally produced, biologically active factors. The umbrella term cytokine has been used to include a variety of such factors, including the interleukin family. The role of one cytokine, IL-1 beta, in periodontal disease pathogenesis has been widely reported. More recent studies have focused on a potential role for IL-6 in driving the destructive processes. Most of these reports have suggested a pro-inflammatory role for IL-6 alongside IL-1 and TNF-alpha. This manuscript reviews the biological functions of IL-6, specifically related to tissue destruction at the periodontal site. We would suggest that the activity of IL-6 in periodontal disease differs from IL-1 and TNF-alpha, and may, in part, play a protective role.

Effect of lipopolysaccharide and inflammatory cytokines on interleukin-6 production by healthy human gingival fibroblasts

Cytokines are hormone-like proteins which mediate and regulate inflammatory and immune responses. The purpose of this study was to investigate the effect of lipopolysaccharide (LPS) and inflammatory cytokines on regulation of interleukin-6 (IL-6) production by human gingival fibroblasts (HGF). The HGF cell lines used in this study, H-CL and F-CL, were established by the explant technique from healthy gingival tissue. Cultured cells were grown to confluency and incubated with various concentrations of LPS from Escherichia coli or Porphyromonas gingivalis or with the recombinant human cytokine tumor necrosis factor alpha (TNF-alpha), IL-1alpha, or IL-1beta. Culture supernatants were collected at various times and assessed for IL-6 production by enzyme-linked immunosorbent assay. Total RNA was isolated from the harvested cells and used to assess levels of IL-6 mRNA by the RNase protection assay. Both LPS preparations induced IL-6 production (1 to 4 ng of IL-6 per ml) by both HGF cell lines. Although TNF-alpha stimulated IL-6 production by HGF, > 10-fold-larger amounts were induced with IL-1alpha and IL-1beta. Furthermore, the addition of both IL-1alpha and TNF-alpha to cultured cells resulted in approximately 600- to 800-fold-higher levels of IL-6 than seen in control cultures, suggesting that these cytokines synergistically induced IL-6 production by HGF. IL-6 message in cultured cells was upregulated 20-fold by TNF-alpha, 1,000-fold by IL-1alpha and IL-1beta, and 1,400-fold by IL-1alpha plus TNF-alpha. IL-1alpha and TNF-alpha alone upregulate IL-6 production in a dose- and time-dependent fashion. The addition of IL-1alpha and TNF-alpha to cultured HGF cells resulted in a synergistic induction of IL-6 after 8 h of incubation and when greater than 10 pg of this combination per ml was used. Our studies show that inflammatory cytokines are hundreds of times more potent than LPS in stimulating IL-6 production by HGF.

Subpopulations of fetal-like gingival fibroblasts: characterisation and potential significance for wound healing and the progression of periodontal disease

Wound healing in the adult is commonly compromised by excessive scar formation. In contrast, fetal wound healing is a regenerative process characterised by the conspicuous absence of scarring. Available evidence suggests that phenotypic differences between fetal and adult fibroblasts are important determinants of these distinct modes of tissue repair. In this context, a number of groups (including our own) have documented differences between fetal and adult fibroblasts with respect to such potentially relevant characteristics as migratory activity, motogenic response to cytokines and the synthesis of motility factors, cytokines and matrix macromolecules. The oral mucosa appears to be a privileged site in the adult in that it continues to display a fetal-like mode of wound healing. Data are presented in this review indicating that a subpopulation of gingival fibroblasts expresses several 'fetal-like' phenotypic characteristics. These observations are discussed in terms of both the continued expression of a fetal-like mode of wound healing in the oral mucosa and the possible differential involvement of distinct fibroblast subpopulations in the progression of periodontal disease.

Characteristic cytokines generated by keratinocytes and mononuclear infiltrates in oral lichen planus

Cytokine production was investigated in oral keratinocytes and tissue-infiltrated mononuclear cells (TIMC) obtained from patients with oral lichen planus (OLP). The numbers of cells producing interleukin (IL)-1 beta, IL-4, IL-6, granulocyte colony-stimulating factor, and tumor necrosis factor-alpha per 10(4) cells in keratinocytes from patients with OLP were determined by enzyme-linked immunospot assay. These levels were two to threefold greater than those in keratinocytes from chronically inflamed gingiva and 10 to 20-fold of those from the intact gingiva. The concentrations of these cytokines in the culture supernatants of keratinocytes were correlated with the number of cytokine-producing cells. Compared with TIMC in the gingiva and peripheral blood mononuclear cells, TIMC in OLP were more cytokine-productive, with larger numbers of cytokine-producing cells that expressed more cytokine messengers. More IL-6, IL-2, and IL-10 were generated from TIMC in OLP, whereas less granulocyte colony-stimulating factor was generated. After pretreatment with IL-2, TIMC from OLP patients generated more IL-6 than did peripheral blood mononuclear cells, and IL-4-pretreated TIMC from the patients released larger amounts of IL-2, IL-6, and IL-10. These results indicate that keratinocytes play a critical role in OLP through production of large amounts of cytokines, that TIMC are stimulated in situ and differentiated to produce cytokines characteristic of OLP, and that the inflammatory condition of OLP is determined by the local cytokine network.