Expression of platelet-derived growth factor-AA and platelet-derived growth factor-α receptor in ameloblastomas

Background:  Platelet-derived growth factor (PDGF)-AA isoform and its receptor, PDGF-α receptor (PDGFRA) regulate tooth development and growth. We investigated the expression of both proteins in ameloblastomas, to contribute the understanding of the potential role of the PDGF/PDGFR system in this odontogenic neoplasm.
Method:  Twenty-nine specimens of ameloblastoma were analyzed for PDGF-AA and PDGFRA expression using immunohistochemistry. The proliferation activity was investigated with the MIB-1 antibody. Additionally, capillary sequencing of genomic DNA was performed to search for mutations in therapeutically relevant exons 12 and 18 of the PDGFRA gene.
Results:  PDGF-AA and PDGFRA expression were detectable in all cases with the exception of one tumor. However, protein expression levels did neither correlate with each other nor with MIB-1 expression. Unicystic ameloblastomas did not differ from solid tumors with regard to PDGF-AA, PDGFRA, and MIB-1 expression. One tumor revealed a somatic mutation of exon 12 of the PDGFRA gene.
Conclusion:  PDGF-AA and PDGFRA proteins are regularly expressed in variable levels in ameloblastomas, and somatic mutations of exon 12 and exon 18 of the PDGFRA gene are rare findings.     

A combination of platelet-derived and insulin-like growth factors enhances periodontal regeneration

Abstract The combination of platelet-derived growth factor (PDGF) and insulin-like growth factor one (IGF-1) has previously been shown to enhance repair of soft tissue wounds. Here we report initial observations following application of PDGF and IGF-1 to periodontitis-affected teeth in beagle dogs, 1 μg of PDGF and IGF-1 in an aqueous gel was applied to the root surfaces of test teeth following open flap debridement. Control sites received the gel alone. Block biopsies of the teeth and surrounding bone were taken 2 weeks after treatment. Histologic analyses of control specimens revealed a long junctional epithelial attachment, and no new bone or cementum formation. In contrast, growth factor treated sites exhibited significant amounts of new bone and cementum formation. A nearly continuous layer of osteoblasts lined the newly formed bone, and there was a dense cellular “front” at the coronal extent of the new bone. These preliminary results suggest that in vivo application of the combination of PDGF and IGF-1 may enhance regeneration of the periodontal structures.     

血小板衍化生长因子受体在人牙髓组织中表达的分析

目的：观察血小板衍化生长因子（platelet-derived growth factor,PDGF）受体在人牙髓组织中的表达和分布情况，探讨PDGF在牙髓组织中的作用。方法：制备人牙髓组织标本、采用免疫组织化学方法观察PDGFβ受体在人牙髓组织中的表达与分布情况。结果：在人牙髓组织中的牙髓细胞、微血管内皮细胞表达PDGFβ受体。结论：在正常牙髓组织中牙髓细胞、微血管内皮细胞表达PDGFβ受体，提示PDGF有可能在牙髓组织的生长、发育等正常生理过程和创伤修复过程中起着重要的作用。     

Immunohistochemical detection of insulin-like growth factors, platelet-derived growth factor, and their receptors in ameloblastic tumors

BACKGROUND: To evaluate the roles of growth factors in oncogenesis and cytodifferentiation of odontogenic tumors, expression of insulin-like growth factors (IGFs), platelet-derived growth factor (PDGF), and their receptors was analyzed in ameloblastic tumors as well as in tooth germs. METHODS: Tissue specimens of 10 tooth germs, 47 ameloblastomas, and five malignant ameloblastic tumors were examined immunohistochemically with the use of antibodies against IGF-I, IGF-II, IGF-I receptor (IGF-IR), PDGF A-chain, PDGF B-chain, PDGF alpha-receptor, and PDGF beta-receptor. RESULTS: Immunohistochemical reactivity for IGFs, PDGF chains, and their receptors was detected predominantly in odontogenic epithelial cells near the basement membrane in tooth germs and in benign and malignant ameloblastic tumors. The expression levels of IGF-II and PDGF chains were significantly higher in ameloblastic tumors than in tooth germs. Malignant ameloblastic tumors showed higher reactivity for PDGF chains than benign ameloblastomas and higher reactivity for platelet-derived growth factor receptors than tooth germs. The expression levels of PDGF chains were significantly higher in follicular ameloblastomas than in plexiform ameloblastomas. Desmoplastic ameloblastomas showed higher expression of IGFs and IGF-IR when compared with other ameloblastoma subtypes. CONCLUSION: Expression of IGFs, PDGF, and their receptors in tooth germs and ameloblastic tumors suggests that these growth factor signals contribute to cell proliferation or survival in both normal and neoplastic odontogenic tissues. Expression of these molecules in odontogenic tissues possibly affects interactions with the bone microenvironment during tooth development and intraosseous progression of ameloblastic tumors. Altered expression of the ligands and receptors in ameloblastic tumors may be involved in oncogenesis, malignant potential, and tumor cell differentiation.     

Actinobacillus actinomycetemcomitans-induced expression of IL-1α and IL-1β in human gingival epithelial cells: role in IL-8 expression

Gingival epithelial cells (GEC) are the first cells of the host that encounter the periodontal pathogens. and therefore their role in the initiation of the inflammatory response is critical. We aimed to: 1) characterize the expression of interleukin (IL)- Ialpha and IL-Ibeta in human gingiva and cultured GEC: 2) demonstrate the ability of A. actinomycetemcomitans extracts to upregulate IL-1alpha, IL-1beta and IL-8 expression in GEC in vitro: and 3) characterize the role of IL-1alpha and IL-1beta in the induction of IL-8 expression in GEC in vitro. Ten gingival biopsies (5 inflamed and 5 controls) and cultured GEC were examined for IL-1alpha and IL-Ibeta using immunohistochemical techniques. GEC were also challenged with A. actinomycetemcomitans extracts or IL-1alpha, and secretion of IL-1 and IL-8 was determined by ELISA. In vivo, IL-lalpha and IL-1beta were localized in the gingival epithelium and the infiltrating leukocytes. In vitro, A. actinomycetemcomitans extracts induced a time-dependent expression of IL-1alpha, IL-1beta and IL-8 in GEC. IL-1 inhibitors did not affect A. actinomycetemcomitans-induced IL-8. although they inhibited IL-8 induced by IL-1alpha or IL-1beta. In conclusion, GEC are a major source of IL-1alpha and IL-1beta in the periodontium, which in turn induce additional inflammatory mediators such as IL-8. Therefore GEC can be a potential target for therapeutic intervention in the future.     

αvβ6 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.     

牛血小板衍化生长因子的高效液相色谱分析

目的：测定牛血小板衍化生长因子的分子量和纯度。方法：采用高效液相色谱法。结果：牛血小板衍化生长因子的分子量为２．７×１０４ｕ，纯度为８６．３４％。结论：与ＳＤＳ－ＰＡＧＥ的测定结果基本一致。     

人血小板源性生长因子-B基因转染犬牙龈成纤维细胞的瞬时表达检测

目的 检测携带人血小板源性生长因子-B(hPDGF-B)基因的真核表达质粒在Beagle犬牙龈成纤维细胞内的表达.方法 扩增和鉴定携带hPDGF-B基因的质粒EX-A0380-M03,脂质体介导的方法转染Bealge犬牙龈成纤维细胞,RT-PCR、免疫细胞化学、ELISA以及Western blot检测hPDGF-BB...     

Effects of transforming growth factor-β and platelet-derived growth factor on human gingival fibroblasts grown in serum-containing and serum-free medium

Abstract. Both transforming growth factor-β (TGF-ß) and platelet-derived growth factor (PDGF) have been shown to affect cell proliferation in vitro. The hypothesis being tested was that the effects of the 2 cytokines would be modulated by the presence of serum in the medium. Gingival fibroblasts, obtained from periodontally healthy patients, were maintained in primary culture. Dose response experiments were performed for each growth factor in serum-free medium and in medium containing natural or heat-inactivated fetal bovine serum (10% FBS). Changes in cell numbers were quantified by crystal violet staining. The optimal concentrations of the individual factors (10 ng/ml TGF-ßI, 20 ng/ml PDGF-BB) were then used when the 2 factors were tested in various sequences. In serum-free medium or in medium with 10% natural serum, the response to PDGF-BB was dose-dependent up to 40 ng/ml; however, with 10% heat-inactivated serum, the maximal response was seen at 20 ng/ml. The largest increase in cell numbers was produced by the simultaneous exposure to the two cytokines, rather than a sequential presentation. The findings suggest that the 48-h growth response of human gingival fibroblasts to 10 ng/ml TGF-ß1 or 20 ng/ml PDGF-BB in serum-free medium was equivalent to growth obtained in medium containing heat-inactivated 10% FBS without added growth factors.     

牛血小板衍化生长因子的氨基酸组成分析

目的：测定分析牛血小板衍化生长因子的氨基酸组成。方法：采用酸水解方法。结果：牛血小板衍化生长因子含有１７种不同量的氨基酸，其中含有相对较多的碱性氨基酸。结论：该因子与人血小板衍化生长因子的氨基酸组成基本相近。     

牛血小板衍化生长因子对人牙周膜成纤维细胞的生物学效应

目的：观察在牛血小板衍化生长因子作用下人牙周膜成纤维细胞ＤＮＡ和胶原蛋白合成的情况。方法：采用体外细胞培养技术和核素掺入法。结果：２０ｎｇ／ｍｌ～６０ｎｇ／ｍｌ牛血小板衍化生长因子可明显促进人牙周膜成纤维细胞ＤＮＡ合成，４０ｎｇ／ｍｌ浓度使细胞ＤＮＡ合成在２４ｈ达最高峰；对细胞的胶原蛋白合成无明显促进作用。结论：牛血小板衍化生长因子对人牙周膜成纤维细胞ＤＮＡ合成有促进作用，在牙周组织的创伤修复中可能起重要作用。     

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

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

Immunolocalization of β1 integrins in human gingival epithelium and cultured keratinocytes

Beta 1 integrins are cell surface receptors for extracellular matrix binding. We have recently shown that these receptors may also play a role in cell-cell binding of human epidermal keratinocytes. In this study we used immunofluorescence and confocal laser scanning microscopy to localize beta 1 integrins in frozen sections of human gingiva and cultures of human gingival keratinocytes. The results show that beta 1 integrin polypeptides, localized by monoclonal and polyclonal antibodies, were detected mainly in the basal layer of the keratinized epithelium. There was also scattered staining in connective tissue fibroblasts, nerves, and blood vessel walls. In the basal layer, the integrins were found around the entire periphery of the basal keratinocytes. Furthermore, confocal laser scanning microscopy (CLSM) revealed that most of the staining was in fact localized in dot-like structures at the lateral cell membranes of neighboring basal cells. In cultured human gingival keratinocytes maintained in low calcium (0.15 mM) conditions β1 integrins were localized in several different structures: trails which were left behind when the cells moved in culture, dots underneath the cells, around the nucleus, and in cell-cell contacts. The trails were also found to contain fibronectin and type IV collagen but not laminin. Switching the keratinocytes to high calcium (1.2 mM) conditions induced the formation of cell-cell contacts which were strongly positive for β1 integrins. No fibronectin or type IV collagen was found in cell-cell contact sites. The results indicate that β1 integrins are localized to cell-cell junctions of human gingival keratinocytes both in vivo and in vitro. Cultured cells also express these receptors in cell-matrix contacts indicating a dual role for β1 integrins in cell-matrix and cell-cell contacts of human gingival keratinocytes.     

血小板衍化生长因子-BB和碱性成纤维细胞生长因子对人牙周膜细胞增殖的影响

目的探讨重组人血小板衍生生长因子（rhPDGF）-BB和重组人碱性成纤维细胞生长因子（rh—bFGF）对人牙周膜细胞（PDLC）增殖的影响。方法原代培养人PDLC,应用甲噻唑四唑氮（MTT）比色和流式细胞仪检测rh-PDGF-BB和rh-bFGF单独及联合作用下细胞的增殖能力和增殖指数。结果rhPDGF-BB和rh-bFGF联合作用后,PDLC增殖能力提高,活性增强。其中,10μg·L^-1的rhPDGF—BB加10μg·L^-1的bFGF为最佳显效质量浓度,第3天为最佳显效时间。结论PDGF—BB和bFGF联合能更显著促进人PDLC的增殖并且具有明显的协同效应。     

Platelet-derived growth factor (PDGF) isoform and PDGF receptor expression in drug-induced gingival overgrowth and hereditary gingival fibrosis

OBJECTIVE: To investigate possible associations between platelet-derived growth factor (PDGF), PDGF receptor expression and macrophages in drug-induced and hereditary gingival overgrowth. MATERIALS AND METHODS: Tissues from patients with drug-induced gingival overgrowth (DIGO) (n = 10) and hereditary gingival fibrosis (n = 10) were studied and compared with 'control' gingiva (n = 10). Expression of PDGF and its alpha and beta receptors was investigated immunohistochemically and by RT-PCR. Macrophages were identified by immunostaining for CD68. RESULTS: PDGF isoforms and receptors were detected in most cells within all specimens. There were no differences in the numbers of macrophages, or fibroblasts expressing PDGF or receptors, between groups. The level of PDGF expression by fibroblasts, determined by absorbance measurements, was similar between groups for PDGF A. Significantly lower levels of total PDGF and the receptors were detected in drug-induced overgrowth compared to those in hereditary fibrosis (P < 0.004) and control specimens (P < 0.034). All specimens expressed mRNA for PDGF A, PDGF B and alpha and beta receptors. CONCLUSIONS: These data do not support a pivotal role for macrophage-derived PDGF B in the pathogenesis of DIGO. They suggest that fibroblasts in drug-induced lesions have a lowered capacity to produce, and respond to, PDGF, a property not shared by fibroblasts associated with hereditary fibrosis.