Tr1 responses are elevated in asymptomatic H. pylori-infected individuals and are functionally impaired in H. pylori-gastric cancer patients.

Gastric cancer is one of the most lethal malignancies worldwide. Chronic Helicobacter pylori (H. pylori) infection can induce an inflammatory response that promotes atrophic gastritis, a preceding event to cancer development. The type 1 regulatory T (Tr1) cells have recently emerged as a critical participant in maintaining self-tolerance. In this study, we examined Tr1 cells in H. pylori infection and gastric cancer development. While H. pylori-uninfected (uninfected) subjects presented low Tr1 frequency in the peripheral blood, H. pylori-infected asymptomatic (infected) individuals and H. pylori-infected gastric cancer (cancer) individuals both presented elevated Tr1 frequency. Although the Tr1 cells from infected asymptomatic subjects were functionally more potent than those from uninfected healthy subjects, the Tr1 cells in cancer individuals demonstrated several functional impairments, such as reduced interleukin 10 (IL-10) expression, lower secretion of cytolytic factors including granzyme B and perforin, and lower capacity to suppress CD4+CD25- T cell and CD8+ T cell proliferation. In addition, the frequency and function of Tr1 cells were positively correlated with the disease-free survival of the gastric cancer patients. These results suggest that Tr1 cells might be involved in the regulating immune responses in H. pylori infection and gastric cancer development. The fact that Tr1 cells could suppress inflammation and produce cytotoxic molecules at the same time has made them attractive potential candidates for future immunotherapies.

Increased Frequency of CD49b/LAG-3(+) Type 1 Regulatory T Cells in HIV-Infected Individuals.

In HIV-1 infection elevated serum levels of interferon-α (IFN-α) and interleukin-10 (IL-10) are associated with immune hyperactivation and disease progression. Recently, coexpression of CD49b and LAG-3 was shown to identify Type 1 regulatory T (Tr1) cells, which secrete large amounts of the immunosuppressive cytokine IL-10. We analyzed the frequency of CD49b/LAG-3(+) Tr1 cells in the peripheral blood of HIV-infected individuals at different stages of the disease. We found increased levels of CD49b/LAG-3(+) Tr1 cells as well as IL-10 in HIV patients. With disease progression, Tr1 cells negatively correlate with frequency of plasmacytoid dendritic cells (pDCs), the main producers of IFN-α. However, elevated IL-10 levels could not be ascribed to the CD49b/LAG-3(+)Tr1 cell population. Moreover, we showed in vitro that IFN-α leads to an upregulation of IL-10 as well as CD49b/LAG-3(+) Tr1 cell counts in healthy controls, recapitulating effects observed in vivo during HIV infection. Our results suggest that overexpression of IFN-α during HIV infection drives the generation of CD49b/LAG-3(+) Tr1 cells and the immunosuppressive cytokine IL-10. Furthermore, it remains unclear whether elevated IL-10 levels are beneficial or detrimental in regard to disease progression.

Integrin ß1 is critical for gastrin-releasing peptide receptor-mediated neuroblastoma cell migration and invasion.

BACKGROUND: Gastrin-releasing peptide (GRP) and its receptor, GRP-R, are critically involved in neuroblastoma tumorigenesis; however, the molecular mechanisms and signaling pathways that are responsible for GRP/GRP-R-induced cell migration and invasion remain unclear. In this study, we sought to determine the cell signals involved in GRP/GRP-R-mediated neuroblastoma cell migration and invasion. METHODS: Human neuroblastoma cell lines SK-N-SH, LAN-1, and IMR-32 were used for our study. Transwell migration and invasion assays were performed after GRP (10(-7) M) stimulation. The cDNA GEArray Microarray kit was used to determine GRP-R-induced gene expression changes. Protein and membrane expression of integrin subunits were confirmed by Western blotting and flow cytometry analysis. siRNA transfection was performed using Lipofectamine 2000. For scratch assay, a confluent monolayer of cells in 6-well plates were wounded with micropipette tip and observed microscopically at 24 to 72 h. RESULTS: GRP increased neuroblastoma cell migration and expressions of MMP-2 whereas the TIMP-1 level decreased. GRP-R overexpression stimulated SK-N-SH cell migration and upregulated integrin α2, α3, and ß1 protein as well as mRNA expression. Targeted silencing of integrin ß1 inhibited cell migration. CONCLUSION: GRP/GRP-R signaling contributes to neuroblastoma cell migration and invasion. Moreover, the integrin ß1 subunit critically regulates GRP-R-mediated neuroblastoma cell migration and invasion.

Coexpression of CD49b and LAG-3 identifies human and mouse T regulatory type 1 cells.

CD4(+) type 1 T regulatory (Tr1) cells are induced in the periphery and have a pivotal role in promoting and maintaining tolerance. The absence of surface markers that uniquely identify Tr1 cells has limited their study and clinical applications. By gene expression profiling of human Tr1 cell clones, we identified the surface markers CD49b and lymphocyte activation gene 3 (LAG-3) as being stably and selectively coexpressed on mouse and human Tr1 cells. We showed the specificity of these markers in mouse models of intestinal inflammation and helminth infection and in the peripheral blood of healthy volunteers. The coexpression of CD49b and LAG-3 enables the isolation of highly suppressive human Tr1 cells from in vitro anergized cultures and allows the tracking of Tr1 cells in the peripheral blood of subjects who developed tolerance after allogeneic hematopoietic stem cell transplantation. The use of these markers makes it feasible to track Tr1 cells in vivo and purify Tr1 cells for cell therapy to induce or restore tolerance in subjects with immune-mediated diseases.

An autologous platelet-rich plasma stimulates periodontal ligament regeneration.

BACKGROUND: Regeneration of periodontal tissues is one of the most important goals for the treatment of periodontal disease. The technology of plasma rich in growth factors provides a biologic approach for the stimulation and acceleration of tissue healing. The purpose of this study is to evaluate the biologic effects of this technology on primary human periodontal ligament fibroblasts. METHODS: The authors studied the response of periodontal ligament cells to this pool of growth factors on cell proliferation, cell migration, secretion of several biomolecules, cell adhesion, and expression of α2 integrin. Cell proliferation and adhesion were evaluated by means of a fluorescence-based method. Cell migration was performed on culture inserts. The release of different biomolecules by periodontal ligament fibroblasts was quantified through enzyme-linked immunosorbent assay. The α2 integrin expression was assessed through Western blot. RESULTS: This autologous technology significantly stimulated cell proliferation, migration, adhesion, and synthesis of many growth factors from cells including vascular endothelial growth factor, thrombospondin 1, connective tissue growth factor, hepatocyte growth factor, and procollagen type I. The α2 integrin expression was lower in plasma rich in growth factor-treated cells compared to non-stimulated cells, although no statistically significant differences were observed. CONCLUSION: This plasma rich in growth factors exerts positive effects on periodontal ligament fibroblasts, which could be positive for periodontal regeneration.

Immunoexpression of á2-integrin and Hsp47 in hereditary gingival fibromatosis and gingival fibromatosis-associated dental abnormalities

Objective: The purpose of the present study was to investigate the expression of the α2-integrin subunit and heat shock protein 47 (Hsp47) in two families with isolated gingival fibromatosis (GF) form and one family with GF associated with dental abnormalities and normal gingiva (NG). Study Design: Immunohistochemistry was performed with antibodies against α2-integrin and Hsp47 in specimens from two unrelated families with hereditary gingival fibromatosis (Families 1 and 2) and from one family with a gingival fibromatosis-associated dental abnormality (Family 3); NG samples were used for comparison. The results were analysed statistically. Results: Immunoreactivity for α2-integrin and Hsp47 was observed in the nucleus of epithelial cells of both the basal and suprabasal layer and a more discreet signal was noted in connective tissue in all study samples. Hsp47 showed higher immunoreactivity in Family 2 compared with the other families (p≤0.05). Despite the markup α2-integrin was higher in Family 3 there was no statistically significant difference between the families studied (p≥0.05). Conclusions: Our results confirmed the heterogeneity of GF, such that similar patterns of expression of the condition may show differences in the expression of proteins such as Hsp47. Although no difference in α2-integrin expression was observed between GF and NG groups, future studies are necessary to determine the exact role of this protein in the various forms of GF and whether it contributes to GF pathogenesis (AU)

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Odontogenic responses of human dental pulp cells to collagen/nanobioactive glass nanocomposites.

OBJECTIVES: Collagen-based nanocomposite incorporating nanobioactive glass (Col/nBG) was developed as a scaffolding matrix for dentin-pulp regeneration. The effects of the novel matrix on the proliferation of human dental pulp cells (hDPCs) and their differentiation into odontoblastic lineage were investigated. METHODS: Nanocomposite scaffold was prepared by incorporating nBG within the Col solution and then reconstituting them into a membrane form. Cell growth by MTS assay, adhesion by scanning electron microscopy (SEM), and odontoblastic differentiation by alkaline phosphatase (ALP) activity, mineralization, and the mRNA expression of differentiation-related genes of DPCs on each scaffold were evaluated. RESULTS: The introduction of nBG significantly improved the bone mineral-like apatite formation in the simulated body fluid, suggesting excellent acellular bone-bioactivity. The hDPCs cultured on the Col/nBG nanocomposite have shown active growth behavior during culture for 14 days. The mRNA levels of major organic extracellular matrix of dentin, collagen type I and III were highly expressed in the Col/nBG matrix. Moreover, the alkaline phosphatase (ALP) activity and the mineralized nodule formation were increased in the Col/nBG nanocomposite compared to those in Col. Odontoblatic differentiation genes, including dentin sialophosphoprotein, dentin matrix protein I, ALP, osteopontin and osteocalcin were significantly stimulated in the Col containing nBG. Moreover, the key adhesion receptor integrin components α2 and ß1, specifically binding to collagen molecule sequence, were upregulated in Col/nBG compared to Col, suggesting that odontogenic stimulation was closely related to the integrin-mediated process. SIGNIFICANCE: In our study, the nanocomposite Col/nBG matrix induced the growth and odontogenic differentiation more effectively than Col alone, providing a promising scaffold condition for regeneration of dentin-pulp complex tissue.

Increased expression of putative cancer stem cell markers in primary prostate cancer is associated with progression of bone metastases.

BACKGROUND: A number of putative stem cell markers have been associated with aggressiveness of prostate cancer, including alpha 2 and alpha 6 integrin and c-met. The study aimed to test the hypothesis that the development of bone metastasis correlates with the proportion of prostate cancer stem cell-like cells present in the primary tumor. METHODS: Prostate tissue samples were obtained from patients with high-risk prostatic adenocarcinoma. Prostate cancer tumor tissue samples underwent immunohistochemical staining for alpha 2 and alpha 6 integrin and c-met; positive and negative controls were included. Samples were scored as positive if >5% of cells within the sample stained positively. Survival and bone metastasis-free survival curves on the patient cohort were estimated by the actuarial method of Kaplan-Meier. RESULTS: A total of 62 patients were included in the study. Bone metastases progression rate was 46% at 105 months with a median time of 46 months (95% CI: 1-62.5 months); prostate cancer-specific survival was 33% at 122 months with a median survival time of 69.4 months (95% CI: 63.5-109.4 months). Survival curves show that c-met-, alpha 2, and alpha 6 integrin-positive tumors were positively associated with the occurrence of bone metastasis-free survival. There was a higher level of significance when at least c-met and either alpha 2 or alpha 6 integrin was positive. CONCLUSION: It can be concluded that percentage of stem cell-like prostate cancer cells has a prognostic impact especially on the risk of metastatic bone progression.

Role of IL-1α in cisplatin-induced acute renal failure in mice.

BACKGROUND/AIMS: For unknown reasons, caspase-1 -/- mice, protected against cisplatin-induced acute renal failure (ARF), are deficient in interleukin (IL)-1α. We thus asked whether IL-1α deficiency underlies the mechanism of protection against cisplatin-induced ARF in these mice. METHODS: Cisplatin (30 mg/kg) was injected intraperitoneally into wild-type C57BL/6 mice to produce a cisplatin-induced model of ARF. IL-1α was measured in control vehicle- and cisplatin-treated wild-type animals. We also examined whether IL-1α -/- mice were similarly protected against cisplatin-induced ARF. Additionally, infiltration of CD11b- and CD49b-positive cells, as markers of macrophages, natural killer, and natural killer T cells (pan-NK cells), was investigated in wild-type and IL-1α -/- mice. RESULTS: Compared with vehicle-treated mice, renal IL-1α increased in cisplatin-treated wild-type mice beginning on day 1. IL-1α -/- mice were shown to be protected against cisplatin-induced ARF. No significant difference in the infiltration of neutrophils or CD11b- and CD49b-positive cells were observed between wild-type and IL-1α -/- mice. CONCLUSIONS: Mice deficient in IL-1α are protected against cisplatin-induced ARF. The lack of IL-1α may explain, at least in part, the protection against cisplatin-induced ARF observed in caspase-1 -/- mice. Investigation of the protective mechanism (s) in IL-1α -/- mice in cisplatin-induced ARF merits further study.

Sandblasted-acid-etched titanium surface influences in vitro the biological behavior of SaOS-2 human osteoblast-like cells.

Osseointegrated dental implants have been successfully used over the past several years, allowing functional replacement of missing teeth. Surface properties of titanium dental implants influence bone cell response. Implant topography appears to modulate cell growth and differentiation of osteoblasts thus affecting the bone healing process. Optimal roughness and superficial morphology are still controversial and need to be clearly defined. In the present study we evaluated in vitro the biological behavior of SaOS-2 cells, a human osteoblast-like cell line, cultured on two different titanium surfaces, smooth and sandblasted-acid-etched, by investigating cell morphology, adhesion, proliferation, expression of some bone differentiation markers and extracellular matrix components. Results showed that the surface topography may influence in vitro the phenotypical expression of human osteoblast-like cells. In particular the tested sandblasted-acid-etched titanium surface induced a significantly increased Co I deposition and α2-ß1 receptor expression as compared to the relatively smooth surface, promoting a probable tendency of SaOS-2 cells to shift toward a mature osteoblastic phenotype. It is therefore likely that specific surface properties of sandblasted-acid-etched titanium implants may modulate the biological behavior of osteoblasts during bone tissue healing.

Role of IL-1alpha in Cisplatin-Induced Acute Renal Failure in Mice

BACKGROUND/AIMS: For unknown reasons, caspase-1 -/- mice, protected against cisplatin-induced acute renal failure (ARF), are deficient in interleukin (IL)-1alpha. We thus asked whether IL-1alpha deficiency underlies the mechanism of protection against cisplatin-induced ARF in these mice. METHODS: Cisplatin (30 mg/kg) was injected intraperitoneally into wild-type C57BL/6 mice to produce a cisplatin-induced model of ARF. IL-1alpha was measured in control vehicle- and cisplatin-treated wild-type animals. We also examined whether IL-1alpha -/- mice were similarly protected against cisplatin-induced ARF. Additionally, infiltration of CD11b- and CD49b-positive cells, as markers of macrophages, natural killer, and natural killer T cells (pan-NK cells), was investigated in wild-type and IL-1alpha -/- mice. RESULTS: Compared with vehicle-treated mice, renal IL-1alpha increased in cisplatin-treated wild-type mice beginning on day 1. IL-1alpha -/- mice were shown to be protected against cisplatin-induced ARF. No significant difference in the infiltration of neutrophils or CD11b- and CD49b-positive cells were observed between wild-type and IL-1alpha -/- mice. CONCLUSIONS: Mice deficient in IL-1alpha are protected against cisplatin-induced ARF. The lack of IL-1alpha may explain, at least in part, the protection against cisplatin-induced ARF observed in caspase-1 -/- mice. Investigation of the protective mechanism (s) in IL-1alpha -/- mice in cisplatin-induced ARF merits further study.

CD66a (CEACAM1) expression by mouse natural killer cells.

CD66a (CEACAM1), an adhesion molecule that has regulatory function on T lymphocytes, was found to be expressed on a minority of mouse natural killer (NK) cells, especially in the liver. CD66a expression on NK cells depended on their differentiation stage, with highest levels on immature CD49b(-)NK cells. Expression of CD66a on NK cells was strongly enhanced by in vitro activation with interleukin-12 (IL-12) and IL-18. However, in vivo NK cell stimulation by infection with lactate dehydrogenase-elevating virus did not lead to strong CD66a expression, even on activated interferon--gamma-producing NK cells. These results indicate that CD66a expression is differently regulated, depending on the NK cell activation pathway, which may lead to distinct regulatory mechanisms of the functional subpopulations of these cells.

17beta-estradiol alters the activity of conventional and IFN-producing killer dendritic cells.

Estrogens increase aspects of innate immunity and contribute to sex differences in the prevalence of autoimmune diseases and in response to infection. The goal of the present study was to assess whether exposure to 17beta-estradiol (E2) affects the development and function of bone marrow-derived dendritic cells and to determine whether similar changes are observed in CD11c(+) splenocytes exposed to E2 in vivo. E2 facilitated the differentiation of BM precursor cells into functional CD11c(+)CD11b(+)MHC class II(+) dendritic cells (DCs) with increased expression of the costimulatory molecules CD40 and CD86. Exposure of bone marrow-derived dendritic cells to E2 also enhanced production of IL-12 in response to the TLR ligands, CpG and LPS. In contrast, CD11c(+) cells isolated from the spleens of female C57BL/6 mice that were intact, ovariectomized, or ovariectomized with E2 replacement exhibited no differences in the number or activity of CD11c(+)CD11b(+)MHC class II(+) DCs. The presence of E2 in vivo, however, increased the number of CD11c(+)CD49b(+)NK1.1(low) cells and reduced numbers of CD11c(+)CD49b(+)NK1.1(high) cells, a surface phenotype for IFN-producing killer DCs (IKDCs). Ultrastructural analysis demonstrated that CD11c(+)NK1.1(+) populations were comprised of cells that had the appearance of both DCs and IKDCs. CD11c(+) splenocytes isolated from animals with supplemental E2 produced more IFN-gamma in response to IL-12 and IL-18. These data illustrate that E2 has differential effects on the development and function of DCs and IKDCs and provide evidence that E2 may strengthen innate immunity by enhancing IFN-gamma production by CD11c(+) cells.

Putative IKDCs are functionally and developmentally similar to natural killer cells, but not to dendritic cells.

Interferon-producing killer dendritic cells (IKDCs) have been described as possessing the lytic potential of NK cells and the antigen-presenting capacity of dendritic cells (DCs). In this study, we examine the lytic function and antigen-presenting capacity of mouse spleen IKDCs, including those found in DC preparations. IKDCs efficiently killed NK cell targets, without requiring additional activation stimuli. However, in our hands, when exposed to protein antigen or to MHC class II peptide, IKDCs induced little or no T cell proliferation relative to conventional DCs or plasmacytoid DCs, either before or after activation with CpG, or in several disease models. Certain developmental features indicated that IKDCs resembled NK cells more than DCs. IKDCs, like NK cells, did not express the transcription factor PU.1 and were absent from recombinase activating gene-2-null, common gamma-chain-null (Rag2(-/-)Il2rg(-/-)) mice. When cultured with IL-15 and -18, IKDCs proliferated extensively, like NK cells. Under these conditions, a proportion of expanded IKDCs and NK cells expressed high levels of surface MHC class II. However, even such MHC class II(+) IKDCs and NK cells induced poor T cell proliferative responses compared with DCs. Thus, IKDCs resemble NK cells functionally, and neither cell type could be induced to be effective antigen-presenting cells.

The novel proangiogenic effect of hydrogen sulfide is dependent on Akt phosphorylation.

OBJECTIVE: Hydrogen sulfide (H(2)S) has been reported to be a gasotransmitter which regulates cardiovascular homeostasis. The present study aims to examine the hypothesis that hydrogen sulfide is able to promote angiogenesis. METHODS: Angiogenesis was assessed using in vitro parameters (i.e. endothelial cell proliferation, adhesion, transwell migration assay, scratched wound healing and formation of tube-like structure) and in vivo by assessing neovascularization in mice. Phosphorylation of Akt was measured using Western blot analysis. RESULTS: Exogenously administered NaHS (H(2)S donor) concentration-dependently (10-20 micromol/l) increased cell growth, migration, scratched wound healing and tube-like structure formation in cultured endothelial cells. These effects of NaHS on endothelial wound healing and tube-like structure formation were prevented by either the phosphatidylinositol 3-kinase (PI3K) inhibitor LY 294002 (5 micromol/l) or transfection of a dominant-negative mutant of Akt. NaHS increased Akt phosphorylation and this effect was also blocked by either LY 294002 or wortmannin (25 nmol/l). NaHS did not significantly alter the levels of vascular endothelial growth factor, mRNA expression of fibroblast growth factor and angiopoietin-1, or nitric oxide metabolites. NaHS treatment (10 and 50 micromol kg(-1) day(-1)) significantly promoted neovascularization in vivo in mice. CONCLUSION: The present study reports a novel proangiogenic role of H(2)S which is dependent on activation of Akt.

Identification and characterization of receptors for vacuolating activity of subtilase cytotoxin.

Some shiga toxin-producing Escherichia coli secrete a novel AB5 cytotoxin, named subtilase cytotoxin (SubAB), which induces vacuole formation in addition to cytotoxicity in susceptible cells. By immunoprecipitation with SubAB from Vero cells, we discovered proteins of 100 kDa, 135 kDa and 155 kDa as potential candidates for its receptor. These proteins were N-glycosylated in their extracellular domains, a modification that was necessary for interaction with SubAB. Biotinylated receptors were partially purified by Datura stramonium agglutinin affinity chromatography and avidin-agarose and analysed by TOF mass spectroscopy. The peptide sequences of p135 were identical to beta1 integrin, and its identification was confirmed with anti-integrin beta1 antibody. The p155 protein was identified as alpha2 integrin using anti-integrin alpha2 antibody. In addition, treatment of Vero cells with beta1 integrin RNAi before exposure to SubAB prevented vacuolating activity. These results suggested that SubAB recognizes alpha2beta1 integrin as a functional receptor; this first interaction may be an important key step leading to the SubAB-induced morphological changes in Vero cells.

Weight-dependent changes of immune system in adipose tissue: importance of leptin.

Ancestral lymphoid cells reside in adipose tissues, and their numbers are highly altered in obesity. Leptin, production of which is correlated to fat mass, is strongly involved in the relationships between adipose tissues and immune system. We investigated in epididymal (EPI) and inguinal (ING) fat pads to determine whether 1) lymphocyte phenotypes were correlated to the tissue weight and 2) leptin was involved in such relationships. Immunohistological analyses revealed a tight relationship between the T and NK lymphocytes of the stromal vascular fraction and adipocytes. We identified a significant negative and positive correlation between EPI weight and the percentage of NK and total T cells respectively by cytofluorometric analyses. The NK and ancestral gammadelta T cell contents were directly dependent of leptin since they increased significantly in high-fat (HF) diet mice but not in leptin-deficient (ob/ob) mice as compared to control. By contrast, the alphabeta T cell content seemed independent of leptin because their percentages increased significantly with the EPI weight whatever the type of mice (control, HF, ob/ob). The present study suggests that adipose tissues present, according to their localization, different immunological mechanisms that might be involved in the regulation of adipose cells functions and proliferations.

Dynamic protein expression patterns during intraoral wound healing in the rat.

Wound healing after cleft palate surgery is often associated with impairment of maxillary growth and dento-alveolar development. Wound contraction and scar tissue formation contribute strongly to these effects. In vitro studies have revealed that fibroblasts isolated during different phases of palatal wound healing show phenotypical differences. They change from a quiescent to an activated state and then partly back to a quiescent state. In this study, we evaluated the existence of fibroblast phenotypes at several time-points during palatal wound healing in the rat. Based on cytoskeletal changes (alpha-sma, vimentin, vinculin), integrin expression (alpha1, alpha2, alpha(v) and beta1) and changes in cellularity, we conclude that phenotypically different fibroblast populations are also present during in vivo wound healing. Alpha-sma and the integrin subunits alpha1 and alpha(v) were significantly up-regulated, and vinculin was significantly down-regulated, at early time-points compared to late time-points in wound healing. These changes point to an activated fibroblast state early in wound healing. Later in wound healing, these activated fibroblasts return only partially to the unwounded situation. These results strongly support the idea that different fibroblast populations with specific phenotypes occur in the course of palatal wound healing.

Expression patterns of integrins on pleomorphic adenoma and adenoid cystic carcinoma: study on specimens and in vitro investigation of the effects of extracellular matrix on the expression of these adhesion molecules.

BACKGROUND: Pleomorphic adenoma (PA) and adenoid cystic carcinoma (ACC) are neoplasms of distinct behaviour, showing similar origin, cell components and marked presence of extracellular matrix (ECM). Interactions between cells and ECM are important in the biology of tumours, being partially mediated by integrins. This study investigated these interactions on PA and ACC using paraffin-embedded tissue and an in vitro model of these conditions. METHODS: Expression of integrins in paraffin-embedded samples was assessed by immunohistochemistry. Cells from PA and ACC were characterized using immunofluorescence, and integrin patterns of expression were investigated on cells cultivated on different ECM proteins. RESULTS: Luminal cells of both PA and ACC were more intensely positive for integrins than myoepithelial cells. In vitro studies revealed that PA cells expressed more integrins than ACC cells regardless the ECM protein present. CONCLUSIONS: This study revealed particular patterns of integrin expression in both specimens and in vitro models of PA and ACC. This might prove useful for a better understanding of the biology of these lesions.

Expression of integrin subunits alpha2, alpha3, alpha5, alphav, beta1, beta3 and beta4 in different histological types of ameloblastoma compared with dental germ, dental lamina and adult lining epithelium.

OBJECTIVE: To analyze integrin expression and distribution in different histological types of ameloblastoma, compared with dental germ, dental lamina and adult lining epithelium. MATERIALS AND METHODS: Three-micrometer sections from paraffin-embedded specimens were evaluated employing a streptavidin-biotin immunohistochemical method and anti-integrin alpha2, alpha3, alpha5, alphav, beta1, beta3 and beta4 antibodies. RESULTS: All integrins were present in all specimens, exhibiting different patterns. In follicular ameloblastoma, the integrin staining was stronger in the periphery while integrin alpha2 was not present in the central cells. Acanthomatous ameloblastoma showed a similar pattern, with positive staining for integrins alpha3, alpha5, alphav, beta1 and beta4 in the metaplastic cells. In the unicystic, integrin staining was uniform except for integrins alpha5 and beta3 which showed weaker staining in the upper layers. In the plexiform ameloblastoma, dental germ and lamina integrin staining was uniform. In the adult lining epithelium, staining for integrins alpha2, alpha5 and beta4 was confined to the basal layer, while integrins alphav and beta3 were present in the basal and parabasal, with integrins alpha3 and beta1 in the upper layers. CONCLUSION: Acanthomatous, follicular and unicystic ameloblastomas showed integrin staining patterns similar to the adult lining epithelium while the plexiform ameloblastoma was similar to the dental germ and lamina.