Functional drug-delivery hydrogels for oral and maxillofacial wound healing

The repair process for oral and maxillofacial injuries involves hemostasis, inflammation, proliferation, and remodeling. Injury repair involves a variety of cells, including platelets, immune cells, fibroblasts, and various cytokines. Rapid and adequate healing of oral and maxillofacial trauma is a major concern to patients. Functional drug-delivery hydrogels play an active role in promoting wound healing and have shown unique advantages in wound dressings. Functional hydrogels promote wound healing through their adhesive, anti-inflammatory, antioxidant, antibacterial, hemostatic, angiogenic, and re-epithelialization-promoting properties, effectively sealing wounds and reducing inflammation. In addition, functional hydrogels can respond to changes in temperature, light, magnetic fields, pH, and reactive oxygen species to release drugs, enabling precise treatment. Furthermore, hydrogels can deliver various cargos that promote healing, including nucleic acids, cytokines, small-molecule drugs, stem cells, exosomes, and nanomaterials. Therefore, functional drug-delivery hydrogels have a positive impact on the healing of oral and maxillofacial injuries. This review describes the oral mucosal structure and healing process and summarizes the currently available responsive hydrogels used to promote wound healing.

The Role of Increased Connective Tissue Growth Factor in the Pathogenesis of Oral Submucous Fibrosis and its Malignant Transformation-An Immunohistochemical Study

Connective tissue growth factor (CTGF), a matricellular protein of the CCN family of extracellular matrix-associated heparin-binding proteins, is highly expressed in various organ fibrosis and several malignant tumors. Although a few studies have been conducted using CTGF in oral submucous fibrosis (OSF) and oral squamous cell carcinoma, no study has demonstrated its relation with various stages of OSF and its malignant transformation. The present study investigated the possible role of CTGF in the pathogenesis of OSF and its malignant transformation by using immunohistochemistry. Ten formalin-fixed paraffin-embedded tissue blocks, each of Stage 1 OSF, Stage 2 OSF, Stage 3 OSF, Stage 4 OSF, well- differentiated squamous cell carcinoma (WDSCC) with OSF and WDSCC without OSF were stained for CTGF by immunohistochemistry. Ten cases of healthy buccal mucosa (NOM) were included as controls. The present study demonstrated a statistically significant expression of CTGF in the epithelium and connective tissue of OSF and WDSCC with and without OSF cases against its complete absence in NOM. We observed an upregulation of CTGF expression from NOM to various stages of OSF to WDSCC with or without OSF. A gradual upregulation of the CTGF expression in various stages of OSF to WDSCC (with and without OSF) against its complete absence in NOM suggests that CTGF plays an important role in the pathogenesis of OSF and its malignant transformation.

Toll‑like receptor 2 mediates deposition of collagen I in adipose tissue of high fat diet‑induced obese mice

Obesity is marked by deposition of collagen I in adipose tissue. Toll like receptor (TLR)2 is involved in lipid metabolism, however the association between TLR2 and collagen I remains unclear. The present study was designed to investigate the effect of TLR2 knockout on collagen I in adipose tissue in obese mice. TLR2 knockout and C57BL/6J mice (aged 4 weeks) were fed normal chow or a high‑fat‑diet for 16 weeks. Compared with adipose tissue from lean controls, that from C57BL/6J mice fed a high‑fat diet had increased levels of collagen I, TIMP1 and TGFβ1 and lower levels of MMP1. However, adipose tissue from TLR2 knockout mice fed a high‑fat diet revealed decreased levels of collagen I, TIMP metallopeptidase inhibitor (TIMP)1, and transforming growth factor (TGF)β1, in addition to increased levels of matrix metallopeptidase (MMP)1. These findings suggest that, in the adipose tissue of obese mice, TLR2 is involved in the metabolism of collagen I and may exhibit a role in the metabolism of MMP1, TIMP1 and TGFβ1.

Expression of CD163 in hereditary gingival fibromatosis: A possible association with TGF-β1

BACKGROUND

Although several studies have discussed some of the molecular and cellular changes associated with hereditary gingival fibromatosis (HGF), its pathogenesis is still largely unclear. This study was directed to detect and outline the degree of relationship between the immunophenotyped macrophages (M2) expressing CD163 and TGF-β1 in patients with gingival overgrowth due to HGF.

METHODS

Biopsies from 20 patients suffering from HGF and 20 normal control subjects were harvested, histologically and immunohistochemically stained then, analyzed and statistically compared and correlated for CD163 immunoexpression and TGF-β1.

RESULTS

All HGF specimens expressed TGF-β1 by most of the connective tissue fibroblasts, with statistically high significant mean of area % (2.61 ± 0.41) compared to normal controls (0.11 ± 0.06; P = .001). All control specimens revealed negligible CD163 immunostaining of the few inflammatory cells found with a mean area of % (0.69 ± 0.12), while the specimens of HGF cases showed statistically significant higher CD163 expression (3.39 ± 0.75) at (P = .007). A statistically significant higher mean % of M2 cells expressing CD163 in relation to the total number of the inflammatory cells was revealed in HGF (34.46 ± 2.04) compared to the control group (16.36 ± 2.39; P-value ≤ .05). Moderate correlation between CD163 and TGF-β1 was detected in HGF (r = .451; P-value < .05).

CONCLUSIONS

CD163 and TGF-β1 were clearly expressed in HGF cases compared to healthy control patients, with significant correlation. In HGF, the increase in CD 163-positive cells was specific and not dependent on the chronic gingival inflammation.

The role of TGFβ‑HGF‑Smad4 axis in regulating the proliferation of mouse airway progenitor cells

The interaction between airway epithelial progenitor cells and their microenvironment is critical for maintaining lung homeostasis. This microenvironment includes fibroblast cells, which support the growth of airway progenitor cells. However, the mechanism of this support is not fully understood. In the present study, the authors observed that inhibition of transforming growth factor (TGF)‑β signal with SB431542 promotes the expression of hepatocyte growth factor (HGF) in fibroblast cells. The HGF receptor, c‑Met, is expressed on airway progenitor cells; HGF promotes the colony‑forming ability of airway progenitor cells. The deletion of Smad4 in airway progenitor cells increases the colony‑forming ability, suggesting that Smad4 plays a negative role in the regulating the proliferation of airway progenitor cells. These data demonstrated that the regulation of airway progenitor cells by TGF‑β depends on TGF‑βR1/2 on stromal cells, rather than on epithelial progenitor cells. These data suggested a role for the TGF‑β‑TGF‑βR1/2‑HGF‑Smad4 axis in airway epithelial homeostasis and sheds new light on the interaction between airway progenitor cells and their microenvironment.

Immunohistochemical Expression of CD105 and TGF-β1 in Oral Squamous Cell Carcinoma and Adjacent Apparently Normal Oral Mucosa and its Correlation With Clinicopathologic Features

Angiogenesis in oral squamous cell carcinomas (OSCC) is essential for its growth, invasion, and metastasis. This entails a shift in the balance between proangiogenic and antiangiogenic factors. CD105 and TGF-β1 are 2 such proangiogenic factors wherein CD105 exerts its angiogenic effect by binding to and modulating the TGF-β1 pathway. A total of 50 resected specimens of OSCC were considered. One tissue specimen was taken from tumor proper and another specimen from adjacent apparently normal mucosa (AANM). Both tissues were immunohistochemically stained using CD105 and TGF-β1 antibodies. The expression of each antibody was individually assessed and then compared. Pearson χ test was used for statistical comparison of expression. CD105 was significantly expressed in OSCC as compared with AANM and also correlated with increasing TNM stage. The mean microvessel density was higher in OSCC. TGF-β1 was significantly expressed in epithelium of OSCC as compared with AANM. On comparing expression of TGF-β1 and CD105, 79.54% of endothelial cells expressed positivity for both molecules. Both CD105 and TGF-β1 were increased in OSCC, although based on our results CD105 alone can be used as a prognostic marker. On the basis of immunohistochemical expression of CD105 and TGF-β1 in endothelial cells, our results demonstrate that CD105 acts as one of the receptors of TGF-β1 on endothelial cells and induces the angiogenic pathway in OSCC.

Association of genetic polymorphisms in interferon-γ, interleukin-6 and transforming growth factor-β1 gene with oral lichen planus susceptibility

BACKGROUND

Oral lichen planus (OLP) is a premalignant mucocutaneous disease in which genetic factors and immune responses play a major role. Cytokines play an important role in the pathogenesis and disease progression of OLP. The aim of this study was to investigate the impact of gene polymorphisms of T helper cell subtype Th1 and Th2 cytokines, interferon-gamma (IFN-γ), interleukin-6 (IL-6) and transforming growth factor (TGF)-β1 on OLP susceptibility in a Saudi cohort.

METHODS

Forty two unrelated patients with OLP and 195 healthy controls were genotyped for IFN-γ (874A/T), IL-6 (174G/C) and TGF-β1 (509C/T) polymorphisms.

RESULTS

The frequency of genotype AT of IFN-γ (874A/T) was significantly higher while genotype AA was lower in OLP patients as compared to controls (P < 0.05). The frequency of T containing genotypes (AT + TT) was also higher in OLP patients as compared to that in controls (P = 0.003). The frequencies of allele T was higher while that of allele A lower in patients than the controls however the difference was not statistically significant (P = 0.07). There was no significant difference in the frequencies of alleles and genotypes of IL-6 (174G/C) and TGF-β1 (509C/T) polymorphisms between patient and control groups. These results indicated that genotype AT of IFN-γ (874A/T) polymorphism is associated with OLP risk and genotype AA is protective to OLP. On the other hand the polymorphisms IL-6 (174G/C) and TGF-β1 (509C/T) may not be associated with OLP risk in our population.

CONCLUSION

It is concluded that IFN-γ (874A/T) polymorphism is associated with the susceptibility of OLP, however further studies with large sample size involving different ethnic populations should be conducted to strengthen our results.

Disruption of Calcium Signaling in Fibroblasts and Attenuation of Bleomycin-Induced Fibrosis by Nifedipine

Fibrotic lung disease afflicts millions of people; the central problem is progressive lung destruction and remodeling. We have shown that external growth factors regulate fibroblast function not only through canonical signaling pathways but also through propagation of periodic oscillations in Ca(2+). In this study, we characterized the pharmacological sensitivity of the Ca(2+)oscillations and determined whether a blocker of those oscillations can prevent the progression of fibrosis in vivo. We found Ca(2+) oscillations evoked by exogenously applied transforming growth factor β in normal human fibroblasts were substantially reduced by 1 μM nifedipine or 1 μM verapamil (both L-type blockers), by 2.7 μM mibefradil (a mixed L-/T-type blocker), by 40 μM NiCl2 (selective at this concentration against T-type current), by 30 mM KCl (which partially depolarizes the membrane and thereby fully inactivates T-type current but leaves L-type current intact), or by 1 mM NiCl2 (blocks both L- and T-type currents). In our in vivo study in mice, nifedipine prevented bleomycin-induced fibrotic changes (increased lung stiffness, overexpression of smooth muscle actin, increased extracellular matrix deposition, and increased soluble collagen and hydroxyproline content). Nifedipine had little or no effect on lung inflammation, suggesting its protective effect on lung fibrosis was not due to an antiinflammatory effect but rather was due to altering the profibrotic response to bleomycin. Collectively, these data show that nifedipine disrupts Ca(2+) oscillations in fibroblasts and prevents the impairment of lung function in the bleomycin model of pulmonary fibrosis. Our results provide compelling proof-of-principle that interfering with Ca(2+) signaling may be beneficial against pulmonary fibrosis.

Transforming growth factor-β1 and TGF-β2 act synergistically in the fibrotic pathway in oral submucous fibrosis: An immunohistochemical observation

Background and objectives:

Oral Submucous Fibrosis (OSF) is a potentially malignant oral disorder which leads to fibrosis of the oral mucosa and has a high rate of malignant transformation. The consumption of various forms of areca nut is causatively linked to the condition. The constituents of areca nut activate several pro-fibrotic cytokines, chiefly transforming growth factor-β1, β2, which leads to an increased deposition and decreased degradation of extracellular matrix and collagen. TGF-β1, β2 probably represent the major pathway in the deposition of collagen fibres in this condition. The present study aims to identify and correlate the expressions of TGF-β1 and TGF-β2 immunohistochemically on paraffin sections of various stages of OSF. A comparison was also made between normal oral mucosa and scar tissue and OSF to judge the mode, extent and type of expression of TGF β1, β2.

Methods:

The expression of TGF-β1 antibody (8A11, NovusBio, USA) and TGF-β2 antibody (TB21, NovusBio, USA) was detected immunohistochemically on paraffin sections of 58 and 70 cases of OSF respectively, 10 cases of normal oral mucosal tissue and 4 cases of scar tissue. A mapping of the positivity of the two cytokines was done using JenOptik camera and ProReg image analysis software. The results were statistically analysed using one way ANOVA and students “t” test.

Results:

Expression of TGF-β1 and TGF-β2 was more in OSF as compared with normal oral mucosa, scar/keloid tissue showing highest values. Positivity for both the markers was seen in epithelium, around the blood vessels, in areas of inflammatory infiltrate, fibroblasts and in muscles. TGF-β1 expression was higher and more intense than that of TGF-β2 in all the cases. TGF-β2 was restricted in its expression to submucosal area with minimal involvement of the epithelium and the deeper muscle tissue.

Conclusion:

TGF-β1 is the most prominent cytokine in the fibrotic pathway and TGF-β2 plays a contributory role.

Biomarkers of Orthodontic Tooth Movement in Gingival Crevicular Fluid: A Systematic Review

BACKGROUND

The analysis of gingival crevicular fluid (GCF) may be an acceptable way to examine the ongoing biochemical processes associated with bone turnover during orthodontic tooth movement. If it is possible to biologically monitor and predict the outcome of orthodontic forces, then the management of appliances could be based on individual tissue responses, and the effectiveness of the treatment could be improved.

METHODOLOGY

A literature search was carried out in major databases, such as medline, EMBASE, cochrane library, web of science, google scholar and scopus for relevant studies. Publications in English between 2000 and 2014 which estimated GCF markers as indicators of orthodontic tooth movement were included.

RESULTS

The list of biomarkers available to date was compiled and presented in table format. Each biomarker is discussed separately based on the available evidence.

CONCLUSION

Several sensitive GCF markers are available to detect the biomechanical changes occurring during orthodontic tooth movement. Further focused research might help to analyze the sensitivity and reliability of these indicators, which in turn can lead to the development of chairside tests to assess the outcome of orthodontic therapy.

Leptin effects on the regenerative capacity of human periodontal cells

Obesity is increasing throughout the globe and characterized by excess adipose tissue, which represents a complex endocrine organ. Adipose tissue secrets bioactive molecules called adipokines, which act at endocrine, paracrine, and autocrine levels. Obesity has recently been shown to be associated with periodontitis, a disease characterized by the irreversible destruction of the tooth-supporting tissues, that is, periodontium, and also with compromised periodontal healing. Although the underlying mechanisms for these associations are not clear yet, increased levels of proinflammatory adipokines, such as leptin, as found in obese individuals, might be a critical pathomechanistic link. The objective of this study was to examine the impact of leptin on the regenerative capacity of human periodontal ligament (PDL) cells and also to study the local leptin production by these cells. Leptin caused a significant downregulation of growth (TGFβ1, and VEGFA) and transcription (RUNX2) factors as well as matrix molecules (collagen, and periostin) and inhibited SMAD signaling under regenerative conditions. Moreover, the local expression of leptin and its full-length receptor was significantly downregulated by inflammatory, microbial, and biomechanical signals. This study demonstrates that the hormone leptin negatively interferes with the regenerative capacity of PDL cells, suggesting leptin as a pathomechanistic link between obesity and compromised periodontal healing.

Beneficial effects of adiponectin on periodontal ligament cells under normal and regenerative conditions

Type 2 diabetes and obesity are increasing worldwide and linked to periodontitis, a chronic disease which is characterized by the irreversible destruction of the tooth-supporting tissues, that is, periodontium. The mechanisms underlying the association of diabetes mellitus and obesity with periodontal destruction and compromised periodontal healing are not well understood, but decreased plasma levels of adiponectin, as found in diabetic and obese individuals, might be a critical mechanistic link. The aim of this in vitro study was to examine the effects of adiponectin on periodontal ligament (PDL) cells under normal and regenerative conditions, and to study the regulation of adiponectin and its receptors in these cells. Adiponectin stimulated significantly the expression of growth factors and extracellular matrix, proliferation, and in vitro wound healing, reduced significantly the constitutive tumor necrosis factor-α expression, and caused a significant upregulation of its own expression. The beneficial actions of enamel matrix derivative on a number of PDL cell functions critical for periodontal regeneration were partially enhanced by adiponectin. The periodontopathogen Porphyromonas gingivalis inhibited the adiponectin expression and stimulated the expression of its receptors. In conclusion, reduced levels of adiponectin, as found in type 2 diabetes and obesity, may compromise periodontal health and healing.

Foxp3 gene expression in oral lichen planus: a clinicopathological study

CD4+CD25+ Forkhead‑box protein 3 (Foxp3+) regulatory T cells are important in oral lichen planus (OLP). The present study aimed to investigate Foxp3 expression in CD4+CD25+ T cells of peripheral blood mononuclear cells and oral lesions in patients diagnosed with OLP, who were grouped as OLP subtype, duration and relapse. Using quantitative polymerase chain reaction (qPCR), western blotting and immunohistochemistry, Foxp3 expression levels in explants of oral lesions and CD4+CD25+ T cells from 32 patients with OLP were measured and compared, with 10 healthy subjects as the control group. Foxp3 mRNA expression levels in the explants of oral lesions and circulating CD4+CD25+ T cells in patients with OLP were significantly higher than those in the control group (P<0.05). In patients with clinically erosive lesions, Foxp3 mRNA expression was significantly lower in circulating CD4+CD25+ T cells and tissue explants compared to patients with reticular lesions (P<0.01 and P<0.05, respectively), and lowest in patients with a history of OLP of >1 year or with a history of relapse (P<0.05 and P<0.01, respectively). Foxp3 protein levels in reticular OLP were significantly higher than those in erosive OLP and the control group. The incidence of Foxp3 protein expression in OLP tissues was 36.24±18.92 and 10.44±6.51% in normal oral mucosa (P=0.019). Atrophic/erosive OLP lesions showed a higher proportion of Foxp3‑expressing cells than that of reticular OLP lesions (P<0.05). This study indicated that Foxp3 expression in patients with OLP is associated with the severity and duration of the disorder, suggesting altered immune suppression in the development, clinical course and responsiveness to treatment.

Inflammation-related cytokines in oral lichen planus: an overview

Cytokines are powerful mediators which play a central role in both innate and adapted immune responses. Aberrant productions of cytokines may lead to the onset of immune deficiency, allergy or autoimmunity, which are involved in the mechanisms of various immune-mediated inflammatory diseases. Oral lichen planus (OLP) is a chronic inflammation disease affecting the oral mucosa with unknown aetiology. Previous studies have described the abnormal expression patterns of various inflammation-related cytokines, such as IL-1, 2, 4, 5, 6, 8, 10, 12, 17, 18, TGF-β, IFN-γ and TNF-α, in lesions, saliva, serum and peripheral blood mononuclear cells from patients with OLP, which may reflect the immune dysregulation status and emerge as central players in the immunopathogenesis of OLP. Besides, the gene polymorphisms of several cytokines such as IFN-γ, TNF-α, IL-4, IL-10 have been found to be involved in the susceptibility of OLP. In this review, we gave a brief introduction of the characteristics and biological functions of these inflammation-related cytokines and summarized for the first time the current knowledge on the involvement of inflammation-related cytokines in OLP. Further research on the exact roles of these cytokines will aid the understanding of the pathogenesis and the identification of novel therapeutic approaches of OLP.

TGF-ß regulates enamel mineralization and maturation through KLK4 expression

Transforming growth factor-ß (TGF-ß) signaling plays an important role in regulating crucial biological processes such as cell proliferation, differentiation, apoptosis, and extracellular matrix remodeling. Many of these processes are also an integral part of amelogenesis. In order to delineate a precise role of TGF-ß signaling during amelogenesis, we developed a transgenic mouse line that harbors bovine amelogenin promoter-driven Cre recombinase, and bred this line with TGF-ß receptor II floxed mice to generate ameloblast-specific TGF-ß receptor II conditional knockout (cKO) mice. Histological analysis of the teeth at postnatal day 7 (P7) showed altered enamel matrix composition in the cKO mice as compared to the floxed mice that had enamel similar to the wild-type mice. The µCT and SEM analyses revealed decreased mineral content in the cKO enamel concomitant with increased attrition and thinner enamel crystallites. Although the mRNA levels remained unaltered, immunostaining revealed increased amelogenin, ameloblastin, and enamelin localization in the cKO enamel at the maturation stage. Interestingly, KLK4 mRNA levels were significantly reduced in the cKO teeth along with a slight increase in MMP-20 levels, suggesting that normal enamel maturation is regulated by TGF-ß signaling through the expression of KLK4. Thus, our study indicates that TGF-ß signaling plays an important role in ameloblast functions and enamel maturation.

Regulation of regenerative periodontal healing by NAMPT

Periodontitis is an inflammatory disease characterized by destruction of the tooth-supporting tissues. Obese individuals have an increased risk of periodontitis, and elevated circulating levels of nicotinamide phosphoribosyltransferase (NAMPT) may be a pathomechanistic link between both diseases. Recently, increased levels of NAMPT have also been found in patients with periodontitis, irrespective of the presence of obesity. This in vitro study sought to examine the effects of NAMPT on the regenerative capacity of human periodontal ligament (PDL) cells and, thereby, periodontal healing. PDL cells treated with enamel matrix derivative (EMD), which was used to mimic regenerative healing conditions in vitro, were grown in the presence and absence of NAMPT for up to 14 d. EMD stimulated significantly (P < 0.05) the expression of growth factors and their receptors, matrix molecules, osteogenesis-associated factors, and wound closure and calcium accumulation. In the presence of NAMPT, all these stimulatory effects were significantly (P < 0.05) reduced. In conclusion, the beneficial effects of EMD on a number of PDL cell functions critical for periodontal regeneration are counteracted by NAMPT. Enhanced levels of NAMPT, as found in obesity and periodontal inflammation, may compromise the regenerative capacity of PDL cells and, thereby, periodontal healing in the presence of EMD.

Expression of transforming growth factor β and its correlation with lipodystrophy in oral submucous fibrosis: an immunohistochemical study

OBJECTIVE

In our routine review of Oral Submucous Fibrosis (OSMF) biopsies, we observed decreased adipose tissue even though most are from buccal mucosa. Pathogenesis of OSMF has demonstrated the role of Transforming Growth Factor β (TGF β), in causing fibrosis. This study aims to correlate the role of TGF β with loss of adipose tissue in OSMF.

STUDY DESIGN

From our archives, 84 OSMF cases (24 early and 60 advanced OSMF) were screened for adipose tissue. Immunoexpression of TGF β in these cases were investigated.

RESULTS

Adipose tissue was seen in 67% of early OSMF and in 13% of advanced cases. Early cases showed more intense TGF β staining of epithelium, fibroblast, macrophages and inflammatory cells than the advanced cases.

CONCLUSION

These findings suggest that TGF β plays a key role in causing lipodystrophy in OSMF and is secreted more during early course of the disease than in advanced stage.

TGF-β1, Smad-2/-3, Smad-1/-5/-8, and Smad-4 signaling factors are expressed in ameloblastomas, adenomatoid odontogenic tumors, and calcifying cystic odontogenic tumors: an immunohistochemical study

OBJECTIVES

The TGF-β/Smad signaling pathway regulates diverse cellular functions, including tooth development, and is involved in numerous pathological processes such as tumorigenesis. The aim of this study was to investigate the immunoexpression of the TGF-β/Smad signaling pathway members in ameloblastoma (AM), calcifying cystic odontogenic tumor (CCOT), and adenomatoid odontogenic tumor (AOT).

MATERIALS AND METHODS

This retrospective cross-sectional study included 65 tissue specimens: 34 AMs, 13 CCOTs, and 18 AOTs. Serial sections were immunohistochemically stained with TGF-β1, Smad-4, Smad-1/-5/-8, and Smad-2/-3 antibodies, and a semiquantitative measurement of the positive cells was carried out by two oral pathologists using a 0-3 scale (0: no immunoreactivity, 1: <20% positive cells, 2: 20-50% positive cells, 3: >50% positive cells).

RESULTS

All biomarkers studied were found significantly decreased in AM compared to CCOT and AOT. AOT and CCOT expressed Smad-1/-5/-8 more strongly compared to AM (OR = 11.66, P < 0.001 and OR = 5.34, P = 0.013, respectively), and Smad-2/-3 immunostaining was found significantly increased in CCOT (OR = 10.42, P = 0.001) and AOT (OR = 5.16, P < 0.004) compared to AM. Similarly, Smad-4 was expressed more strongly in AOT and CCOT compared to AM (P = 0.001), while AOT demonstrated a fivefold higher chance to express TGF-β1 compared to AM (P = 0.011).

CONCLUSION

TGF-β/Smad signaling pathway is activated in AM, AOT, and CCOT. The statistically significant reduced TGF-β1/Smad immunoexpression in AM compared to AOT/CCOT could be associated with the more aggressive biological behavior of AM including increased cell proliferation and reduced apoptosis and differentiation. Thus, the biomarkers TGF-β, Smad-4, Smad-1/-5/-8, and Smad-2/-3 could serve as supplementary diagnostic indices between odontogenic tumors of high and low neoplastic dynamics.

Evaluation of Serum TNF-α and TGF-β in Patients with Oral Lichen Planus

Background and aims

The role of cytokines in the immunopathogenesis of oral lichen planus (OLP) has received much attention. The aim of this study was to evaluate the serum levels of TNF-α and TGF-β in patients with OLP in an Iranian population.

Materials and methods

Thirty-two patients with OLP and 32 age-matched healthy volunteers as a control group were included in this study. Serum tests including TNF-α and TGF-β was performed in both groups. Data analysis was performed using descriptive statistics and Mann–Whitney U test using SPSS software version 16.0.

Results

The mean of TNF-α in study and control groups were 157 ± 115 pg/ml and 14 ± 10 pg/ml, respectively. The difference between the two means was statistically significant (P < 0.001). Moreover, the mean of TGF-β in study and control groups were 155 ± 26 pg/ml and 175 ± 57 pg/ml, respectively. The difference between the two means was statistically significant (P = 0.03).

Conclusion

According to the results of the present study, there was a significant decrease in the serum levels of TGF-β and a significant increase in the serum levels of TNF-α in patients with oral lichen planus. The increase in TNF-α serum levels in patients with OLP explains the inflammatory process in the course of the disease.

Novel non-canonical TGF-β signaling networks: emerging roles in airway smooth muscle phenotype and function

The airway smooth muscle (ASM) plays an important role in the pathophysiology of asthma and chronic obstructive pulmonary disease (COPD). ASM cells express a wide range of receptors involved in contraction, growth, matrix protein production and the secretion of cytokines and chemokines. Transforming growth factor beta (TGF-β) is one of the major players in determining the structural and functional abnormalities of the ASM in asthma and COPD. It is increasingly evident that TGF-β functions as a master switch, controlling a network of intracellular and autocrine signaling loops that effect ASM phenotype and function. In this review, the various elements that participate in non-canonical TGF-β signaling, including MAPK, PI3K, WNT/β-catenin, and Ca(2+), are discussed, focusing on their effect on ASM phenotype and function. In addition, new aspects of ASM biology and their possible association with non-canonical TGF-β signaling will be discussed.

EGCG blocks TGFβ1-induced CCN2 by suppressing JNK and p38 in buccal fibroblasts

OBJECTIVES

Transforming growth factor β (TGFβ) has been suggested as the main trigger for the increased collagen production and decreased matrix degradation pathways in oral submucous fibrosis (OSF). Connective tissue growth factor (CTGF/CCN2) and cyclooxygenase-2 (COX-2) were found to overexpress in OSF. The aim of this study was to investigate the molecular mechanism underlying the TGFβ-induced CCN2 expressions in human buccal mucosal fibroblasts (BMFs) to identify the potential targets for drug intervention or chemoprevention of OSF.

MATERIALS AND METHODS

TGFβ-induced CCN2 expression and its signaling pathways were assessed by Western blot analyses in BMFs.

RESULTS

TGFβ1 stimulated CCN2 synthesis in BMFs. Pretreatment with c-Jun NH(2)-terminal kinase (JNK) inhibitor SP600125, p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580, and activin receptor-like kinase 5 (ALK5) inhibitor SB431542 significantly reduced TGFβ1-induced CCN2 synthesis. Epigallocatechin-3-gallate (EGCG) completely blocked TGFβ1-induced CCN2 synthesis by inhibiting the phosphorylation of JNK and p38 MAPK. Prostaglandin E(2) (PGE(2)) inhibited the TGFβ1-induced CCN2 synthesis in human fetal lung fibroblasts IMR90 but not in BMFs.

CONCLUSIONS

The TGFβ1-induced CCN2 synthesis in BMFs could be mediated by the ALK5, JNK, and p38 MAPK pathways. EGCG blocks TGFβ1-induced CCN2 by suppressing JNK and p38 in BMFs.

CLINICAL RELEVANCE

The exceptional signal transduction pathways of TGFβ1-induced CCN2 production in BMFs contribute to the resistance of PGE(2) downregulation of CCN2 expression; therefore, the CTGF/CCN2 levels are maintained in the OSF tissues in the presence of COX-2. EGCG may serve as a useful agent in controlling OSF.

Transforming growth factor-β evokes Ca2+ waves and enhances gene expression in human pulmonary fibroblasts

Fibroblasts maintain the structural framework of animal tissue by synthesizing extracellular matrix molecules. Chronic lung diseases are characterized in part by changes in fibroblast numbers, properties, and more. Fibroblasts respond to a variety of growth factors, cytokines, and proinflammatory mediators. However, the signaling mechanisms behind these responses have not been fully explored. We sought to determine the role of Ca(2+) waves in transforming growth factor-β (TGF-β)-mediated gene expression in human pulmonary fibroblasts. Primary human pulmonary fibroblasts were cultured and treated with TGF-β and different blockers under various conditions. Cells were then loaded with the Ca(2+) indicator dye Oregon green, and Ca(2+) waves were monitored by confocal [Ca(2+)](i) fluorimetry. Real-time PCR was used to probe gene expression. TGF-β (1 nM) evoked recurring Ca(2+) waves. A 30-minute pretreatment of SD 208, a TGF-β receptor-1 kinase inhibitor, prevented Ca(2+) waves from being evoked by TGF-β. The removal of external Ca(2+) completely occluded TGF-β-evoked Ca(2+) waves. Cyclopiazonic acid, an inhibitor of the internal Ca(2+) pump, evoked a relatively slowly developing rise in Ca(2+) waves compared with the rapid changes evoked by TGF-β, but the baseline fluorescence was increased. Ryanodine (10(-5) M) also blocked TGF-β-mediated Ca(2+) wave activity. Real-time PCR showed that TGF-β rapidly and dramatically increased the gene expression of collagen A1 and fibronectin. This increase was blocked by ryanodine treatment and cyclopiazonic acid. We conclude that, in human pulmonary fibroblasts, TGF-β acts on ryanodine-sensitive channels, leading to Ca(2+) wave activity, which in turn amplifies extracellular matrix gene expression.

Model of the initiation of signal transduction by ligands in a cell culture: simulation of molecules near a plane membrane comprising receptors

Cell communication is a key mechanism in tissue responses to radiation. Several molecules are implicated in radiation-induced signaling between cells, but their contributions to radiation risk are poorly understood. Meanwhile, Green's functions for diffusion-influenced reactions have appeared in the literature, which are applied to describe the diffusion of molecules near a plane membrane comprising bound receptors with the possibility of reversible binding of a ligand and activation of signal transduction proteins by the ligand-receptor complex. We have developed Brownian dynamics algorithms to simulate particle histories in this system which can accurately reproduce the theoretical distribution of distances of a ligand from the membrane, the number of reversibly bound particles, and the number of receptor complexes activating signaling proteins as a function of time, regardless of the number of time steps used for the simulation. These simulations will be of great importance to model interactions at low doses where stochastic effects induced by a small number of molecules or interactions come into play.

Interactions of enamel matrix derivative and biomechanical loading in periodontal regenerative healing

BACKGROUND

Although enamel matrix derivative (EMD) has been shown to promote periodontal regeneration, it is unknown whether the actions of EMD are modulated by occlusal loading. This in vitro study was performed to investigate whether biomechanical forces regulate the response of periodontal ligament (PDL) cells to EMD.

METHODS

Human PDL cells were treated with EMD in the presence and absence of cyclic tensile strain (CTS) of various magnitudes for ≤ 14 days. Synthesis of transforming growth factor (TGF)-β1, vascular endothelial growth factor (VEGF), growth factor receptors, collagen, and runt-related transcription factor 2- (RUNX2), cell numbers and adhesion, wound fill rate, and calcium accumulation were analyzed by real-time polymerase chain reaction, enzyme-linked immunosorbent assay, a wound healing assay, and alizarine red S staining.

RESULTS

Wound fill rate, cell numbers and adhesion, and expression of TGF-β1, VEGF, collagen, and RUNX2 were significantly increased by EMD. In the presence of CTS, the EMD-induced effects were significantly reduced. The inhibition of the EMD-upregulated VEGF expression by CTS was blocked by a specific inhibitor of nuclear factor-kappa B signaling. Moreover, CTS downregulated receptors for growth factors involved in the actions of EMD. CTS also antagonized significantly the EMD-induced calcium deposition.

CONCLUSIONS

These in vitro findings suggest that the beneficial actions of EMD on PDL cell functions critical for periodontal regeneration are jeopardized by biomechanical loading. Clinical studies should clarify whether protection of teeth against occlusal forces in the early healing stage may positively affect the outcome of regenerative therapy with EMD.

Aberrant expression in multiple components of the transforming growth factor-β1-induced Smad signaling pathway during 7,12-dimethylbenz[a]anthracene-induced hamster buccal-pouch squamous-cell carcinogenesis

Transforming growth factor (TGF)-β1 signaling controls a plethora of cellular processes including tumorigenesis. The TGF-β1 ligand initiates signaling by binding to TGF-βreceptor II (TβRII) and allowing heterodimerization with TGF-βreceptor I (TβRI); thus, TβRI is phosphorylated by TβRII. After phosphorylation, Smad2 and Smad3 heterodimerize with Smad4, and this complex migrates to the nucleus to regulate the expression of specific target genes. However, Smad7 interrupts above signal transduction by preventing phosphorylation of Smad2 or Smad3. The objective of this study was to examine the TGF-β1-induced Smad signaling pathway during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal-pouch squamous-cell carcinogenesis. Fifty 6-week-old male Syrian golden hamsters were divided into three experimental and two control groups (10 animals in each). Both pouches of each animal in the experimental groups were painted with 0.5% DMBA solution, and both pouches of each animal of one of the control groups were similarly treated with mineral oil; the other control group remained untreated throughout the experiment. Animals from three experimental groups were sacrificed at the end of 3rd, 9th, and 14th-weeks after DMBA treatment, respectively, and animals from two control groups were all sacrificed at 14th-weeks after the treatment. Immunohistochemical staining for TGF-β1, TβRI, TβRII, Smad2-4 and Smad7 were performed.

RESULTS

A significant increase in the expression of Smad7 and significant decreases in the expression of TβRII, Smad 2, Smad3 and Smad4 were noted during hamster buccal-pouch carcinogenesis induced by DMBA. Our findings indicate that a disruption in TGF-β1-induced Smad signaling occurs as a result of aberrant expression of multiple components in the TGF-β1 signaling pathway during DMBA-induced hamster buccal-pouch carcinogenesis, leading to loss of TGF-β1 growth-suppressive effects on transformed pouch keratinocytes.

Betel-derived alkaloid up-regulates keratinocyte alphavbeta6 integrin expression and promotes oral submucous fibrosis

Oral submucous fibrosis (OSF) is a premalignant, fibrosing disorder of the mouth, pharynx, and oesophagus, with a malignant transformation rate of 7-13%. OSF is strongly associated with areca (betel) nut chewing and worldwide, over 5 million people are affected. As αvβ6 integrin is capable of promoting both tissue fibrosis and carcinoma invasion, we examined its expression in fibroepithelial hyperplasia and OSF. αvβ6 was markedly up-regulated in OSF, with high expression detected in 22 of 41 cases (p < 0.001). We investigated the functional role of αvβ6 using oral keratinocyte-derived cells genetically modified to express high αvβ6 (VB6), and also NTERT-immortalized oral keratinocytes, which express low αvβ6 (OKF6/TERT-1). VB6 cells showed significant αvβ6-dependent activation of TGF-β1, which induced transdifferentiation of oral fibroblasts into myofibroblasts and resulted in up-regulation of genes associated with tissue fibrosis. These experimental in vitro findings were confirmed using human clinical samples, where we showed that the stroma of OSF contained myofibroblasts and that TGF-β1-dependent Smad signalling was detectable both in keratinocytes and in myofibroblasts. We also found that arecoline, the major alkaloid of areca nuts, up-regulated keratinocyte αvβ6 expression. This was modulated through the M(4) muscarinic acetylcholine receptor and was suppressed by the M(4) antagonist, tropicamide. Arecoline-dependent αvβ6 up-regulation promoted keratinocyte migration and induced invasion, raising the possibility that this mechanism may support malignant transformation. Over 80% of OSF-related oral cancers examined had moderate/high αvβ6 expression. These data suggest that the pathogenesis of OSF may be epithelial-driven and involve arecoline-dependent up-regulation of αvβ6 integrin.

Increased expression of Smad proteins, and in particular Smad3, in oral lichen planus compared to normal oral mucosa

BACKGROUND

Oral lichen planus (OLP) is a chronic inflammatory disease of the oral mucosa which the World Health Organisation (WHO) considers a premalignant condition. One step in malignant development is so called epithelial mesenchymal transition (EMT), a process whereby epithelial cells acquire mesenchymal characteristics. EMT occurs during embryogenesis and wound healing but also in some human diseases such as cancer and fibrosis. A factor known to induce EMT is transforming growth factor-β (TGF-β), which uses the Smad proteins as mediators for its signalling. TGF-β is also often over-expressed in squamous cell carcinoma of the head and neck (SCCHN).

METHODS

In the present study we mapped expression of Smad proteins in OLP lesions by immunohistochemistry, and compared to expression in normal and sensitive oral mucosa. The latter group of patients had developed SCCHN after shorter or longer periods of diffuse oral symptoms. The aim was to see if there were any signs of EMT related changes in the OLP lesions, as judged by changes in the TGF-β pathway.

CONCLUSION

Changes in the TGF-β pathway related to EMT are seen in the very earliest stages of oral malignancy and become more severe as lesions progress.

The effects of one-step self-etch adhesives on the induction of oxidative stress and production of TGF-beta1 and BMP-2 by human gingival fibroblasts

The aim of this study was to evaluate and compare the effects of two self-etch adhesive materials on the induction of oxidative stress and production of transforming growth factor-beta1 (TGF-beta1) and bone morphogenetic protein-2 (BMP-2) by cultured human gingival fibroblasts (HGF). Inflammation-free attached gingiva was obtained from healthy donors under informed consent. Following 24- and 72-h exposure of HGF to two different elutes of the test materials, cell viability was determined using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Lipid peroxidation, a major indicator of oxidative stress, was measured by the thiobarbituric acid reactive substance (TBARS) assay. TGF-beta1 and BMP-2 levels in cell-free culture media were determined by enzyme-linked immunosorbent assay (ELISA). Cell viability of the test groups was significantly lower than those of control at 24 and 72 h (P < 0.001), but showed an increase at 72 h (P < 0.001). The TBARS levels of both test groups were significantly greater than that of control (P < 0.05), and displayed similar values at 72 h (P > 0.05). For both materials, the levels of TGF-beta1 and BMP-2 were significantly greater than that of control (P < 0.05). Both test groups showed increased TGF-beta1 levels. These results indicate that the tested self-etch adhesives might be capable of inducing production of TGF-beta1 and BMP-2 in cultured HGF, despite their cytotoxic and oxidative stress-producing potential.

Regulation of TGF-beta signalling by Fbxo11, the gene mutated in the Jeff otitis media mouse mutant

Background

Jeff is a dominant mouse mutant displaying chronic otitis media. The gene underlying Jeff is Fbxo11, a member of the large F-box family, which are specificity factors for the SCF E3 ubiquitin ligase complex. Jeff homozygotes die shortly after birth displaying a number of developmental abnormalities including cleft palate and eyes open at birth. TGF-β signalling is involved in a number of epithelial developmental processes and we have investigated the impact of the Jeff mutation on the expression of this pathway.

Results

Phospho-Smad2 (pSmad2) is significantly upregulated in epithelia of Jeff homozygotes. Moreover, there was a significant increase in nuclear localization of pSmad2 in contrast to wild type. Mice heterozygous for both Jeff and Smad2 mutations recapitulate many of the features of the Jeff homozygous phenotype. However, tissue immunoprecipitations failed to detect any interaction between Fbxo11 and Smad2. Fbxo11 is known to neddylate p53, a co-factor of pSmad2, but we did not find any evidence of genetic interactions between Jeff and p53 mutants. Nevertheless, p53 levels are substantially reduced in Jeff mice suggesting that Fbxo11 plays a role in stabilizing p53.

Conclusion

Overall, our findings support a model whereby Fbxo11, possibly via stabilization of p53, is required to limit the accumulation of pSmad2 in the nucleus of epithelial cells of palatal shelves, eyelids and airways of the lungs. The finding that Fbxo11 impacts upon TGF-β signalling has important implications for our understanding of the underlying disease mechanisms of middle ear inflammatory disease.

Homeostatic role of transforming growth factor-beta in the oral cavity and esophagus of mice and its expression by mast cells in these tissues

Transforming growth factor-beta (TGF-beta) is a pleiotropic growth factor; its overexpression has been implicated in many diseases, making it a desirable target for therapeutic neutralization. In initial safety studies, mice were chronically treated (three times per week) with high doses (50 mg/kg) of a murine, pan-neutralizing, anti-TGF-beta antibody. Nine weeks after the initiation of treatment, a subset of mice exhibited weight loss that was concurrent with decreased food intake. Histopathology revealed a unique, nonneoplastic cystic epithelial hyperplasia and tongue inflammation, as well as dental dysplasia and epithelial hyperplasia and inflammation of both the gingiva and esophagus. In an effort to determine the cause of this site-specific pathology, we examined TGF-beta expression in these tissues and saliva under normal conditions. By immunostaining, we found higher expression levels of active TGF-beta1 and TGF-beta3 in normal tongue and esophageal submucosa compared with gut mucosal tissues, as well as detectable TGF-beta1 in normal saliva by Western blot analysis. Interestingly, mast cells within the tongue, esophagus, and skin co-localized predominantly with the TGF-beta1 expressed in these tissues. Our findings demonstrate a novel and restricted pathology in oral and esophageal tissues of mice chronically treated with anti-TGF-beta that is associated with basal TGF-beta expression in saliva and by mast cells within these tissues. These studies illustrate a previously unappreciated biological role of TGF-beta in maintaining homeostasis within both oral and esophageal tissues.

Memory encoded throughout our bodies: molecular and cellular basis of tissue regeneration

When a sheep loses its tail, it cannot regenerate it in the manner of lizards. On the other hand, it is possible to clone mammals from somatic cells, showing that a complete developmental program is intact in a wounded sheep's tail the same way it is in a lizard. Thus, there is a requirement for more than only the presence of the entire genetic code in somatic cells for regenerative abilities. Thoughts like this have motivated us to assemble more than just a factographic synopsis on tissue regeneration. As a model, we review skin wound healing in chronological order, and when possible, we use that overview as a framework to point out possible mechanisms of how damaged tissues can restore their original structure. This article postulates the existence of tissue structural memory as a complex distributed homeostatic mechanism. We support such an idea by referring to an extremely fragmented literature base, trying to synthesize a broad picture of important principles of how tissues and organs may store information about their own structure for the purposes of regeneration. Selected developmental, surgical, and tissue engineering aspects are presented and discussed in the light of recent findings in the field. When a sheep loses its tail, it cannot regenerate it in the manner of lizards. On the other hand, it is possible to clone mammals from somatic cells, showing that a complete developmental program is intact in a wounded sheep's tail the same way it is in a lizard. Thus, there is a requirement for more than only the presence of the entire genetic code in somatic cells for regenerative abilities. Thoughts like this have motivated us to assemble more than just a factographic synopsis on tissue regeneration. As a model, we review skin wound healing in chronological order, and when possible, we use that overview as a framework to point out possible mechanisms of how damaged tissues can restore their original structure. This article postulates the existence of tissue structural memory as a complex distributed homeostatic mechanism. We support such an idea by referring to an extremely fragmented literature base, trying to synthesize a broad picture of important principles of how tissues and organs may store information about their own structure for the purposes of regeneration. Selected developmental, surgical, and tissue engineering aspects are presented and discussed in the light of recent findings in the field.

Beyond good and evil in the oral cavity: insights into host-microbe relationships derived from transcriptional profiling of gingival cells

In many instances, the encounter between host and microbial cells, through a long-standing evolutionary association, can be a balanced interaction whereby both cell types co-exist and inflict a minimal degree of harm on each other. In the oral cavity, despite the presence of large numbers of diverse organisms, health is the most frequent status. Disease will ensue only when the host-microbe balance is disrupted on a cellular and molecular level. With the advent of microarrays, it is now possible to monitor the responses of host cells to bacterial challenge on a global scale. However, microarray data are known to be inherently noisy, which is caused in part by their great sensitivity. Hence, we will address several important general considerations required to maximize the significance of microarray analysis in depicting relevant host-microbe interactions faithfully. Several advantages and limitations of microarray analysis that may have a direct impact on the significance of array data are highlighted and discussed. Further, this review revisits and contextualizes recent transcriptional profiles that were originally generated for the specific study of intricate cellular interactions between gingival cells and 4 important plaque micro-organisms. To our knowledge, this is the first report that systematically investigates the cellular responses of a cell line to challenge by 4 different micro-organisms. Of particular relevance to the oral cavity, the model bacteria span the entire spectrum of documented pathogenic potential, from commensal to opportunistic to overtly pathogenic. These studies provide a molecular basis for the complex and dynamic interaction between the oral microflora and its host, which may lead, ultimately, to the development of novel, rational, and practical therapeutic, prophylactic, and diagnostic applications.

Gingival crevicular fluid transforming growth factor-beta1 in cyclosporine and tacrolimus treated renal transplant patients without gingival overgrowth

BACKGROUND

Gingival crevicular fluid (GCF) levels of transforming growth factor-beta(1) (TGF-beta(1)) have been previously investigated in relation to the pathogenesis of cyclosporine-A (CsA)-induced gingival overgrowth (GO) but no clinical data are available regarding the GCF levels of TGF-beta(1) in patients treated with tacrolimus (Tac). However, as gingival inflammation is pronounced at sites of GO and this consequently may lead to an elevation in TGF-beta(1) levels the present study aimed to evaluate gingival crevicular fluid (GCF) TGF-beta(1) levels in renal transplant patients using CsA or Tac without GO.

METHODS

GCF TGF-beta(1) levels were investigated in 30 renal transplant patients without GO medicated with either CsA (n=15) or Tac (n=15). Sixteen gingivitis patients and 15 periodontally healthy subjects were selected as controls. Periodontal status was evaluated by measuring probing depth, plaque index and papilla bleeding index. The TGF-beta(1) levels were analysed by enzyme-linked immunosorbent assay.

RESULTS

Both CsA and Tac groups had significantly elevated GCF TGF-beta(1) total amount compared to gingivitis and healthy groups (p<0.008). GCF TGF-beta(1) total amount of CsA and Tac groups was similar (p>0.008). Gingivitis and healthy groups had also similar GCF TGF-beta(1) total amount (p>0.008).

CONCLUSIONS

Within the limits of the present data it is unlikely that TGF-beta(1) is an exclusive mediator of CsA- or Tac-induced GO. However, pathogenesis of GO is multifactorial and contribution of TGF-beta(1) to the interrelations between cytokines and growth factors with fibrogenic potential cannot be disregarded.

Acidic fibroblast growth factor decreases α-smooth muscle actin expression and induces apoptosis in human normal lung fibroblasts

Fibroblast/myofibroblast expansion is critical in the pathogenesis of pulmonary fibrosis. To date, most research has focused on profibrotic mediators, whereas studies on antifibrotic factors are scanty. In this study, we explored the effects of acidic fibroblast growth factor (FGF-1) and FGF-1 plus heparin (FGF-1+H) on fibroblast growth rate, apoptosis, and myofibroblast differentiation. Heparin was used because it participates in FGF-1 signaling. Growth rate was evaluated by WST-1 colorimetric assay, DNA synthesis by [3H]thymidine incorporation, and apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and cleaved caspase 3. Expression of α-smooth muscle actin (α-SMA) was examined by immunocytochemistry, flow cytometry, real-time PCR, and immunoblotting. Despite the induction of DNA synthesis, FGF-1+H significantly reduced fibroblast growth rate. This correlated with a significant increase in apoptosis, evaluated by TUNEL (41.6 ± 1.4% vs. 12.5 ± 0.6% from controls; P < 0.01) and cleaved caspase 3 (295 ± 32 vs. 200 ± 19 ng/106cells from controls; P < 0.05). Double immunostaining (α-SMA-TUNEL) revealed that the levels of induced apoptosis were similar in fibroblasts and myofibroblasts. FGF-1+H inhibited the effect of TGF-β1 on myofibroblast differentiation. α-SMA-positive cells were reduced by immunocytochemistry from 44.5 ± 6.5% to 10.9 ± 1.9% and by flow cytometry from 30.6 ± 2.5% to 7.7 ± 0.6% ( P < 0.01). Also, FGF-1+H significantly inhibited the TGF-β1 induction of α-SMA quantified by real-time PCR and Western blot. This decrease was associated with a 35% reduction in TGF-β1-induced collagen gel contraction. The effect of FGF-1+H was mediated by a significant decrease of TGF-β1-induced Smad2 phosphorylation. FGF-1 alone exhibited similar but lower effects. These findings suggest that FGF-1 can have an antifibrogenic role, inducing apoptosis of fibroblasts and inhibiting myofibroblast differentiation.

Effect of platelet-rich plasma on migration and proliferation of SaOS-2 osteoblasts: role of platelet-derived growth factor and transforming growth factor-beta

Platelet-enriched plasma (PRP) is used in therapy as a source of growth factors in bone fracture and wound healing; however, few data exist on its role in the different aspects of the healing process. The effect of PRP and of the two main growth factors present in this preparation (platelet-derived growth factor [PDGF] and transforming growth factor-beta [TGF-beta]) was evaluated in vitro using the human osteoblastic cell line SaOS-2, which was shown by reverse transcription-polymerase chain reaction to express both PDGF-alpha and -beta receptors. Batroxobine-activated PRP was added in different concentrations to SaOS-2 cells to assess cell migration (by a microchemotaxis assay) and cell proliferation (by [3H]-thymidine incorporation into the DNA). Immunoneutralization with anti-PDGF-beta or anti-TGF-beta antibodies allowed the assessment of the specific role of these growth factors. The overall results obtained indicate that PRP dose-dependently stimulates both chemotaxis and cell proliferation. PDGF and TGF-beta appear to exert distinct effects on the two parameters, the former involved in stimulating cell migration and the latter in inhibiting cell proliferation. It is concluded that the different growth factors present in activated PRP can specifically contribute to the main processes of tissue regeneration.

Gingival crevicular fluid transforming growth factor-β1 in several forms of periodontal disease

BACKGROUND

Transforming growth factor-beta(1) (TGF-beta(1)) has significant effects on periodontal host response regulation. Limited knowledge on the role of TGF-beta(1) in various periodontal disease types and particularly in advanced periodontitis forms warranted the present study. The aim of the present study was to evaluate the gingival crevicular fluid (GCF) TGF-beta(1) levels in patients with different forms of periodontal disease.

METHODS

GCF TGF-beta(1) levels were investigated in 32 chronic periodontitis (CP), 30 generalized aggressive periodontitis (G-AgP), 15 gingivitis patients and 16 periodontally healthy subjects. Periodontal status was evaluated by measuring probing depth, clinical attachment loss, plaque and bleeding on probing. TGF-beta(1) levels were analyzed by enzyme-linked immunosorbent assay. The results were expressed in terms of total amount (pg) and concentration (pg/microl).

RESULTS

G-AgP and CP groups had significantly elevated GCF TGF-beta(1) total amount compared to healthy group (p<0.008). Moreover, GCF TGF-beta(1) total amount of G-AgP group was significantly higher than that of gingivitis group (p<0.008). G-AgP and CP groups had similar GCF TGF-beta(1) total amount (p>0.008). Significant correlation was found between GCF TGF-beta(1) total amount and all clinical periodontal parameters (p<0.05).

CONCLUSIONS

The results of the present study suggest contribution of TGF-beta(1) to the pathogenesis of advanced chronic and aggressive periodontitis. TGF-beta(1) may thus be one of the components modulating exaggerated host response together with other major mediators of inflammation.

Induction of the myofibroblastic phenotype in human gingival fibroblasts by transforming growth factor-β1: role of RhoA-ROCK and c-Jun N-terminal kinase signaling pathways

BACKGROUND AND OBJECTIVES

Myofibroblastic differentiation is an important event in gingival wound healing and chronic inflammation. Transforming growth factor-beta 1 (TGF-beta1) is a potent growth factor that has been implicated in this process. Gingival myofibroblasts have an increased ability to remodel the extracellular matrix and this feature has been associated with changes in the distribution of F-actin and the expression of the myofibroblast marker alpha-smooth muscle actin. In the present study we have analyzed the role of TGF-beta1 and the signaling routes activated by this factor in the cytoskeletal changes that characterize the myofibroblastic differentiation process in human gingival fibroblasts.

MATERIALS AND METHODS

The signalling pathways involved in myofibroblastic differentiation were studied in primary cultures of human gingival fibroblasts using several signal transduction inhibitors. RhoA activation was analyzed through a pull-down assay. Distribution of focal adhesions and actin cytoskeleton was assessed by means of immunofluorescence and western blot. A cell adhesion assay was performed in TGF-beta1-stimulated cells. Smooth muscle actin expression was studied through western blot and immunofluorescence. c-Jun N-terminal kinase phosphorylation was assessed through western blot.

RESULTS

Our observations show that TGF-beta1 activated the GTPase RhoA, a key regulator of the actin cytoskeleton. As a consequence of this event, this growth factor stimulated the generation of actin stress fibers and the reinforcement of vinculin-enriched focal adhesions. These responses were blocked after inhibiting ROCK, the main target of RhoA activation. TGF-beta1 also stimulated the adhesion of fibroblasts over fibronectin, an extracellular matrix molecule involved in myofibroblastic differentiation. Finally, induction of the myofibroblast marker alpha-smooth muscle actin by TGF-beta1 was abolished by the c-Jun N-terminal protein kinase inhibitor SP600125, suggesting a role for this signaling pathway during the induction of this phenotype.

CONCLUSIONS

We propose that TGF-beta1 may promote the differentiation of myofibroblasts through the stimulation of cell spreading and adhesion, the reinforcement of focal adhesions, the maturation of the actin cytoskeleton, and the induction of alpha-smooth muscle actin. Activity of RhoA-ROCK and c-Jun N-terminal protein kinase signaling pathways are probably involved in these cellular events.

Alphavbeta6 integrin in wound healing and cancer of the oral cavity

Integrins are a family of heterodimeric cell surface receptors, which are expressed on most cells where they mediate cell-cell and cell-extracellular matrix (ECM) interactions. The alphavbeta6 integrin is epithelial-specific and binds to the ECM proteins fibronectin, vitronectin and tenascin, and also to the latency associated peptide of TGF-beta. Unlike most epithelial integrins, alphavbeta6 is not expressed constitutively by healthy oral epithelia, but is up-regulated during tissue remodelling, including that accompanying wound healing and carcinogenesis. Although, the data at present have been generated principally from in vitro studies, there is increasing evidence to suggest that alphavbeta6 may promote carcinoma progression: alphavbeta6 has been shown to modulate invasion, inhibit apoptosis, regulate protease expression and activate TGF-beta1. This review examines the current literature, and discusses the possible role of alphavbeta6 in wound healing, and in the development and progression of oral squamous cell carcinoma.