Oral Mucosal Epithelium Research Articles

Oral epithelial overexpression of IL-1alpha causes periodontal disease.

Periodontal disease is a bacterial infection that results in inflammatory destruction of tissues that support the teeth, including connective tissue and bone. In this study, we report that transgenic mice that overexpress the 17-kDa form of IL-1alpha in the basal layer of oral mucosal epithelium develop a syndrome that possesses all of the cardinal features of periodontal disease, including epithelial proliferation and apical migration, loss of attachment, and destruction of cementum and alveolar bone. In this model, bacterial colonization and infection were not required, since levels of periodontal bacteria were equivalent in transgenic and wild-type mice, and continuous treatment with antibiotics from birth did not ameliorate the disease. Our findings therefore indicate that elevated levels of IL-1alpha in the oral micro-environment can mediate all of the clinical features of periodontal disease.

Effect of bone marrow transplantation on the immunolocalization of p53, hMSH2, and hMLH1 proteins on oral mucosa.

Considering that hMSH2, hMLH1 and p53 are important in maintaining genomic stability of the oral mucosa epithelium, the purpose of the present study was to investigate the immunolocalization of these proteins in the epithelium of the oral mucosa of patients submitted to bone marrow transplantation (BMT) compared with controls. Twenty-one samples of lip biopsies from BMT recipients were retrieved. Twenty samples of normal lower labial mucosa associated with mucocele in non-transplanted patients were included as control group. The streptavidin-biotin complex stain was used to detect the human DNA mismatch repair proteins hMSH2, hMLH1 and p53 protein. The main findings demonstrated that the mean number of suprabasal epithelial cells positive for MSH2 was statistically higher than the control group. The immunostaining of hMLH1 and p53 at the basal and suprabasal epithelial layers were statistically higher in the oral labial mucosa of the BMT patients compared with controls. The present study shows that oral epithelial cells of BMT patients show increased immunolocalization of the DNA repair related proteins.

Bronchiolitis Obliterans Associated With Paraneoplastic Pemphigus: a Paraneoplastic Autoimmune Multiorgan Syndrome

Paraneoplastic pemphigus is a mucocutaneous disease characterized by well defined clinical and immunopathological features associated with neoplasia. Recent evidence of bronchial epithelium involvement has led to the suggestion that this process is a paraneoplastic autoimmune multiorgan syndrome. We report the case of a patient with lichenoid eruptions on the skin and mucous membranes who later developed progressive dyspnea. With a suspected diagnosis of paraneoplastic autoimmune multiorgan syndrome, the following diagnostic tests were performed: histology and immunofluorescence of the skin, oral mucosa, and bronchial epithelium; indirect immunofluorescence of serum; pulmonary function tests; and evaluation for an occult neoplasm. Findings of pathology and immunofluorescence confirmed the suspected diagnosis. The computed thoracoabdominal tomography revealed signs of bronchiolitis and the presence of a retroperitoneal tumor. Awareness of the mucocutaneous manifestations of paraneoplastic autoimmune multiorgan syndrome, and confirmation of this diagnosis by simple laboratory techniques can facilitate the early detection of occult neoplasia and forestall respiratory involvement.

Identity of TUNEL-positive cells in the oral buccal epithelium of normal mucosa and lichen lesions.

In situ detection of DNA fragmentation by TdT (terminal deoxynucleotidyl transferase)-mediated dUTP nick end labeling (TUNEL) is a widely used technique to identify apoptotic cells in the terminal phases of cell death. Several studies have shown that there are statistically increased numbers of TUNEL(+) cells within the epithelium of oral lichen (OL). It was suggested that this indicates an increased rate of apoptosis among basal and suprabasal keratinocytes in OL epithelium. The aim of this study was to identify the TUNEL(+) cells in the epithelium of erythematous (ERY) OL and normal oral mucosa (NOM). Sections of biopsies from NOM and ERY OL were processed for TUNEL combined with immunostaining for pan-cytokeratin or for cell markers specifically expressed by different leukocytes. In NOM, TUNEL(+) keratinocytes were almost exclusively seen in the outermost epithelial layers. This labeling was absent in ERY OL. In the basal and lower spinous layers, more TUNEL(+) cell nuclei were seen in ERY OL as compared with NOM, in accordance with previous studies. The present observations show, however, that only very few of these cells were keratinocytes, but rather were CD4(+) lymphocytes and CD68(+) macrophages. There was no difference between the numbers of TUNEL(+) keratinocytes in basal and lower spinous layers in ERY OL and NOM epithelium. No intraepithelial CD8(+) lymphocytes, Langerhans cells, or mast cells were found to be TUNEL(+). The findings indicate that the pathologic changes in ERY OL epithelium cannot be explained by increased prevalence of terminal keratinocyte cell death identified by TUNEL.

Expression of hMSH2 protein of the human DNA mismatch repair system in oral lichen planus

Lichen planus is a mucocutaneous disease of inflammatory nature and unknown etiology. It is characterized by a cell-mediated immunological response to induced antigenic change in skin and/or mucosa. The possible malignant transformation of lichen planus remains a subject of controversial discussions in the literature. hMSH2 is one of the human DNA mismatch repair (hMMR) genes and it plays an important role in reducing mutation and maintaining genomic stability. hMSH2 alterations have been reported in oral squamous cell carcinoma and there are evidences suggesting the association between oral lichen planus and squamous cell carcinoma. In this study, we aim to investigate the immunolocalization of hMSH2 protein in oral lichen planus compared to oral normal mucosa epithelium. We examined the expression of hMSH2 protein by immunohistochemistry in twenty-six cases of oral lichen planus. Clinically, 12 of them were categorized into reticular subtype and 14 were atrophic/erosive. Ten cases of normal mucosa were added to the control group. Results showed that the percentage of positive cells to hMSH2 was smaller in reticular (46.54%; p=0,006) and atrophic/erosive (48.79%; p=0,028) subtypes of oral lichen planus compared to normal mucosa (61.29%). The reduced expression of hMSH2 protein in oral lichen planus suggests that this lesion is more susceptible to mutation and therefore facilitate the development of oral squamous cell carcinoma.

Transplantable cultivated mucosal epithelial sheet for ocular surface reconstruction

Ocular surface reconstruction by tissue engineering using somatic stem cells is a second-generation therapeutic modality. In view of future treatment of bilaterally affected, severe ocular surface disorders, two types of transplantable cultivated mucosal epithelial sheets can be used for reconstruction. One is an allogeneic corneal epithelial stem cell sheet, and the other is an autologous oral mucosal epithelial cell sheet. We first investigated the feasibility of amniotic membrane as an epithelial carrier, and found that denuded amniotic membrane was the most appropriate substrate for this purpose. Thus, cultivated corneal epithelial stem cell sheets were created by co-culturing with 3T3 fibroblast and air-lifting on amniotic membrane. These epithelial sheets demonstrated positive keratin 3 and 12 specific to in vivo corneal epithelium, tight junction related proteins and proliferative activity. The transplanted allogeneic human corneal epithelial sheets existed successfully on the corneal surface, and were quite effective in achieving ocular surface stability in severe ocular surface disorders. A few cases, however, developed immunological reactions or opportunistic infections, etc. Secondly, we established transplantable autologous cultivated oral mucosal epithelial sheets in rabbits. The in vitro oral mucosal epithelial sheets showed histological characteristics similar to those of in vivo corneal epithelial sheets; for example, positive keratin 3 expression. Based on the fact that, the transplanted autologous oral mucosal epithelial sheets resembled corneal epithelium and that we achieved the recovery of corneal transparency in rabbits, we propose that cultivated oral mucosal epithelium may become the substitute for corneal epithelium in ocular surface reconstruction.

Role of stromal thrombospondin-1 in motility and proteolytic activity of oral squamous cell carcinoma cells

The immunohistochemical localization of thrombospondin-1 (TSP-1) in human normal oral mucosa and oral squamous cell carcinoma (SCC) was examined. The immunostaining of TSP-1 was mainly localized in the connective tissues adjacent to the epithelium of oral mucosa, whereas epithelial cells showed negligible immunoreactivity for TSP-1. TSP-1 expression was striking in the stroma of SCC. TSP-1 synthesis by SCC cells and fibroblasts in culture was examined by immunoprecipitation with anti-TSP-1 antibody. Fibroblasts produced a large amount of TSP-1, whereas SCC cells secreted little amount of TSP-1. Treatment of fibroblasts by the conditioned medium of SCC cells led to an increase in TSP-1 synthesis. TSP-1 induced haptotactic migration and stimulated the production of matrix metalloproteinase-9 (MMP-9) in SCC cells. These results suggest that TSP-1 in the stroma of oral SCC might be synthesized by mesenchymal cells but not by epithelial cells, and that the synthesis of TSP-1 might be regulated by interaction with SCC cells. TSP-1 accumulated in the stroma might promote the progression of oral SCC by enhancing the motility and proteolytic activity in a paracrine manner.

HPV e carcinogênese oral: revisão bibliográfica

O Papilomavírus humano (HPV) é um vírus ubíquo de DNA, epiteliotrópico, que tem a pele e as mucosas como principais sítios de infecção. Ultimamente, a sua associação com neoplasias benignas e malignas da cavidade oral, principalmente o carcinoma epidermóide, tem sido mais evidente. O seu achado comum em epitélio de mucosa oral normal, amplamente divulgado na literatura, não permite inferências mais precisas quanto ao seu papel na carcinogênese (se agente etiológico principal, coadjuvante ou simples habitante do epitélio de revestimento da mucosa oral). São mais de 100 tipos já identificados, dos quais 24 já foram localizados na cavidade oral. Desses, 4 são particularmente importantes, os tipos 6 e 11 (que estão envolvidos nas lesões benignas do epitélio oral) e 16 e 18 (comprovadamente carcinogênicos e possivelmente envolvidos na etiologia de determinados carcinomas epidermóides orais). A ação desses dois últimos tipos está principalmente associada às oncoproteínas E6 e E7 produzidas pelos mesmos. A E6 liga-se, seqüestra e degrada a p53, importante proteína supressora de tumor. A segunda liga-se e seqüestra a pRb, também supressora de tumor, facilitando a liberação de E2F. Apesar do aprimoramento das técnicas de detecção do HPV nas lesões de mucosa oral, o seu envolvimento direto com os carcinomas orais não foi ainda devidamente comprovado, todavia a sua ação sinérgica com outros carcinógenos químicos e físicos, tais como o fumo e o álcool, em determinados carcinomas epidermóides nos parece o caminho mais correto para explicar a ação do papilomavírus humano na carcinogênese oral.

Estimates, from salivary analyses, of the turnover time of the oral mucosal epithelium in humans and the number of bacteria in an edentulous mouth

The objectives were to obtain rough estimates of the number of bacteria in an edentulous mouth and the mean turnover time of the oral mucosa and the conditions under which the salivary phase in the mouth might act as a bacterial continuous culture system. The premise was that at steady state in vivo, the rates of loss of bacteria and epithelial cells in saliva must be equal to their rates of proliferation. Drooled saliva was collected from 17 subjects and the number of epithelial cells per millilitre was determined in a Coulter Counter. The numbers of adherent bacteria per epithelial cell were counted on cells stained with Toluidine Blue. For 10 subjects, salivary bacterial counts were obtained after saliva had been diluted in Reduced Transport Fluid and grown anaerobically on Blood Agar for 5 days. From the known surface areas of the oral mucosa and individual epithelial cells and the rate of loss of epithelial cells into saliva, the surface layer of epithelial cells was calculated to be replaced every 2.7 h. From the calculated number of epithelial cells lining the oral mucosa, the number of bacteria per epithelial cell, and the rate of swallowing of the bacteria in saliva, the number of bacteria in an edentulous mouth was calculated to be about 1.58×10 9 and the mean time between bacterial cell divisions to be 1.38 h. Given a residual volume of 0.8 ml and a maximal bacterial division rate of 3 h −1, the salivary phase in the mouth could act as a continuous culture system for certain fast-growing bacteria only if the maximum flow rate were <0.04 ml/min.

Recapitulation of oral mucosal tissues in long-term organotypic culture.

To test the influence of fibroblasts on epithelial morphology and expression of keratinocyte proteins and barrier lipids, we bioengineered homotypic and heterotypic oral mucosae and skin using cultured adult human cells. Fibroblasts were allowed to modify collagen type I gels for 2 weeks before keratinocytes were added. The organotypic cultures were then grown at the air-liquid interface for 4 weeks. In homotypic combinations, epithelial morphology and protein expression closely mimicked those in vivo. In heterotypic combinations, the morphology resembled that in vivo and keratinocytes expressed their typical markers, except when skin keratinocytes were recombined with alveolar fibroblasts; they expressed K19, K4, and K13, which is similar to oral mucosal epithelia rather than to the epidermis. Morphologically, the stratum corneum layers were typical for the epithelial tissues. Grafting the bioengineered cultures to the backs of Nude mice did not change the results, suggesting that our findings are not merely a culture phenomenon. Lipid profiles of the homotypic combinations mimicked the profiles found in the normal epithelial tissues, except that the engineered alveolar epithelium expressed more ceramide 2 than that in vivo. In the heterotypic combinations, keratinocytes appeared to control the lipid profile, except in the combination of skin keratinocytes with alveolar fibroblasts, wherein the ceramide profile appeared to be partly that of alveolar epithelium and partly that of epidermis. These results suggest that cultured adult fibroblasts and keratinocytes are sufficient to recapitulate graftable oral tissues, and, except for alveolar fibroblasts, the type of fibroblast had little influence on keratinocyte differentiation.

Loss of Cell Adhesion in Dsg3bal–Pas Mice with Homozygous Deletion Mutation (2079del14) in the Desmoglein 3 Gene

Pemphigus encompasses a group of autoimmune blistering diseases with circulating pathogenic autoantibodies recognizing several proteins, including the desmosomal cadherin, desmoglein 3. Targeted disruption of the Dsg3 gene by homologous recombination (Dsg3tm1stan) in mouse results in fragility of the skin and oral mucous membranes, analogous to the human disease. In addition, the Dsg3tm1stan mice develop phenotypic runting and hair loss, identical to that of the mouse mutant, Dsg3bal-2J. The Dsg3bal-2J mice are homozygous for a 1 bp insertion (2275insT) in the Dsg3 gene resulting in a nonfunctional Dsg3 mRNA. In this study, we characterized an allelic mutation, Dsg3bal-Pas, with clinical features similar to those in Dsg3bal-2J. We have identified a 14 bp deletion in exon 13 of the Dsg3 gene resulting in a frameshift and premature termination codon 7 bp downstream from the site of the deletion and causing a truncation of the desmoglein 3 polypeptide by 199 amino acids, eliminating virtually all of the intracellular domain. We demonstrate that, although a Dsg3 mRNA transcript was detectable in Dsg3bal-Pas skin, the corresponding protein for desmoglein 3 was completely absent in the oral mucosal epithelium of homozygous Dsg3bal-Pas compared with that of +/Dsg3bal-Pas mice. No significant changes in the expression of desmogleins 1 and 2 were detected. To elucidate a potential mechanism causing loss of cell adhesion in the Dsg3bal-Pas mice, we generated a myc-tagged truncated Dsg3bal-Pas desmoglein 3 protein and expressed it in keratinocytes. The myc-tagged truncated Dsg3bal-Pas desmoglein 3 protein was found predominantly in the cytoplasm possibly due to increased proteolytic degradation. Cell surface staining was also detected but was jagged, not linear along the cell-cell border like that observed for the full-length desmoglein 3. The expression of the myc-tagged truncated Dsg3bal-Pas desmoglein 3 protein resulted in a reduction in staining of other desmosomal proteins, including desmoglein 1 and 2, plakophilin 2, and plakoglobin. In addition, the cells expressing myc-tagged truncated Dsg3bal-Pas desmoglein 3 protein underwent dramatic changes in cell morphology and exhibited striking extensive filopodia. Collectively, these data showed that the perturbation of desmoglein 3 found in the Dsg3bal-Pas mice resulted in disadhesion of keratinocytes manifested with blistering phenotype.

β-Carotene Plasma Levels and Content in Oral Mucosal Epithelium Is Skin Type Associated

β-Carotene is one of the important antioxidants in the defence mechanisms of the body against reactive oxygen species and, in particular, against UV radiation in the skin. The aim of our study was to measure if differences of β-carotene in the peripheral blood and oral mucosa exist in relation to skin types I–IV (according to Fitzpatrick). One hundred and seventy-four subjects were studied with regard to β-carotene plasma levels. Out of these, 63 healthy volunteers (24–28 years) with skin type I–IV were studied with regard to plasma levels and content of β-carotene in the oral mucosa. Ten millilitres of venous blood was obtained and oral mucosa cells (OMCs) were taken by gently brushing the oral cavity without contamination of capillary leak blood. A modified method by Stich et al. was used for preparing cells and measuring β-carotene in OMCs by HPLC. Plasma levels of skin type I were 0.1565 µmol/l and increased via skin types II with 0.2989 and III with 0.5457 to 1.221 µmol/l in skin type IV. A similar skin type-dependent increase in β-carotene could be measured in the oral mucosa epithelium (OMC) either when measured in micromoles/litre (0.0056–0.0217) or in nanograms/10⁶ cells (0.2090–0.9989). Smokers had significantly lower levels of β-carotene in plasma and OMC as compared with non-smokers. Non-melanoma and melanoma skin cancer patients also showed lower β-carotene plasma levels and in the OMCs as well. From our results, we conclude that plasma levels and content of β-carotene in the cytoplasm of OMCs show marked and significant differences with regard to skin types I–IV. The question arises whether these differences are genetically controlled.

Syndecan-1 expression during postnatal tooth and oral mucosa development in rats aged from two days to six weeks

Abstract Syndecans are a family of heparan sulphate proteoglycans that regulate cell-matrix interactions that influence cell growth, proliferation and morphology. The aim of this study was to observe changes in the expression of Syndecan-1 in the developing epithelium of the rat oral mucosa and in the epithelial cell rests of Malassez in the developing periodontium of normal rat molars, from late crown development through to early eruption. Immuno-histo-chemistry (Syndecan-1 N–18) and histochemistry (Alcec Blue) were used to observe changes in the expression of Syndecan-1 in rats aged two to 42 days. Results indicated that during normal tooth development in the rat, labelling or staining of variable intensity for Syndecan-1 was demonstrated in the stratified oral epithelium above the stratum basale in the rat tongue and palate, and in ameloblasts of the developing molar in rats aged two to 14 days. Histochemical staining of the predentine and dentine layers was consistent in all specimens. Labelling or staining for Syndecan-1 was negative in the rat periodontal ligament, which may suggest that either Syndecan-1 was not expressed during normal molar root development or that continued work is required for identification of a suitable label in rats.

Differential expression of heat shock protein 27 in normal oral mucosa, oral epithelial dysplasia and squamous cell carcinoma

The aim of this study was to evaluate HSP27 expression in fetal, normal and inflamed oral mucosal epithelium and in oral premalignant epithelial lesions and in their ensuing invasive cancers. In developing human oral epithelia, immunoreactions for HSP27 were moderately observed in suprabasal keratinocytes of palate and tongue. Normal oral epithelium had an intense suprabasal positivity. In inflamed oral mucosa, HSP27 staining was stronger in basal and suprabasal keratinocytes than in normal epithelium. Most oral premalignant lesions showed no (5 cases, 29%) or low (8 cases, 46.4%) staining. In OSCC both low and high HSP27 levels of expression were observed. HSP27 immunolabelling was down-regulated in poorly differentiated areas and up-regulated in highly differentiated ones. These findings indicated that HSP27 expression seems to protect cells from apoptosis during inflammation, while the down-regulation in dysplasia could impair the protective mechanism against mutagenesis induced by environmental factors and thus enhancing the transformation of oral epithelial dysplasia into OSCCs.

Leukotriene A(4)-hydrolase expression and leukotriene B(4) levels in chronic inflammation of bacterial origin: immunohistochemistry and reverse-phase high-performance liquid chromatography analysis of oral mucosal epithelium.

Chronic inflammation of the oral epithelium of bacterial origin is associated with elevated leukotriene B(4) (LTB(4)) levels. We investigated leukotriene A(4) (LTA(4))-hydrolase expression and LTB(4) levels in oral epithelium in relation to the clinical disease manifestation and immunohistopathology and LTA(4)-hydrolase expression in cultured oral keratinocytes. In 11 patients, three different types of biopsy specimens of the oral mucosa tissues were examined. Each sample was divided, and one-half was analysed using immunohistochemistry with antibodies to LTA(4)-hydrolase, CD1a, CD3, CD19, macrophages/monocytes and granulocytes. The other half of the sample was homogenised and analysed using reverse-phase high-performance liquid chromatography to determine LTB(4) levels. We found strong LTA(4)-hydrolase expression in basal cells of the oral epithelium from tissue samples that appeared clinically healthy; however, histologically a mild chronic inflammation was observed. In contrast, patients with symptoms of an inflammation of the oral mucosa showed only weak LTA(4)-hydrolase staining of the epithelial cell layers, but strong immunoreactivity in endothelial and invading inflammatory cells. LTB(4) levels were elevated in inflamed tissues compared with non-inflamed controls. Most significantly, there was a strong association between the immunohistochemical detection of the enzyme, LTB(4) levels, cellular infiltration and the clinical disease manifestations. In vitro experiments indicated that LTA(4)-hydrolase expression may be induced by bacterial contamination. This study suggests that LTA(4)-hydrolase expression and elevated LTB(4) levels in oral mucosal epithelium are integral parts of the induction and progression of chronic inflammatory reactions. Epithelial cells may participate in early stages of inflammation as a source of LTB(4).

The tau protein of oral epithelium increases in Alzheimer's disease.

Alzheimer's disease (AD) is an important problem that should be solved in the 21st century. Prior to treatment, a simple and easy diagnostic method using biological markers should be available. As a method to attain this goal, we detected and determined tau protein in oral mucosal epithelium. Oral epithelium was exfoliated from 34 patients with AD or 29 patients with vascular dementia, and 33 young and 34 age-matched controls. Western blot was performed for determining the molecular weight of oral tau protein. The tau protein level was determined with an enzyme-linked immunosorbent assay (ELISA) kit for cerebrospinal fluid (CSF). CSF tau was also measured and compared with oral tau. Western blot analysis using an anti-non-phosphorylated tau-protein antibody showed two bands, one at 65 Kd and the other at 110 Kd. The tau-protein level in oral epithelia showed a significant positive correlation with those in the CSF (p <.05). The patients with AD had significantly higher levels of tau protein than the patients with vascular dementia and the controls (p <.01). AD patients with a younger age at onset of the study showed a higher level of the tau protein than the patients with later age at onset (p <.05). Like other nonneural tissues, oral epithelium contains small tau and big tau. The tau protein in oral epithelium reflects the pathological changes, as does the CSF tau. Individuals who develop AD may have had high levels of the tau protein in oral mucosal epithelium since early childhood. The tau-protein level in oral epithelia could be helpful in diagnosing AD.

Effects of a 10% carbamide peroxide bleaching agent on rat oral epithelium proliferation.

The purpose of the present study was to evaluate the influence of short course topical application of carbamide peroxide on proliferating cell nuclear antigen (PCNA) immunohistochemical expression in the oral tongue mucosa of rats. Twelve male Wistar rats were submitted to topical application of 10% carbamide peroxide on one side of the dorsal tongue once a week for three consecutive weeks. Only distilled water was applied on the control side. The animals were killed on days 0, 10, and 20 after the last application. The tongue was fixed in buffered formalin for 24 h and embedded in paraffin. Tissue blocks (3 microns) were subjected to the biotin-streptavidin amplified system for identification of PCNA. The percentage of epithelial-positive basal cells in each side of the tongue mucosa was calculated. The results demonstrated that topical application of 10% carbamide peroxide increases PCNA immunohistochemical expression on the basal layer of the oral mucosa epithelium of rats on day 0 after treatment. In conclusion, short-course use of carbamide peroxide induces transient epithelial cell proliferation of the oral mucosa of rats.

Human papillomavirus type 38 infection in oral squamous cell carcinomas

In this study, 53 paraffin-embedded oral squamous cell carcinoma (OSCC) biopsy specimens were used. Human papillomavirus type 38 (HPV-38) infection was demonstrated in OSCCs using the PCR technique, DNA sequencing analysis, in situ hybridization, and immunohistochemical techniques. Additionally, the correlation between HPV-38 infection and expressions of proliferating cell nuclear antigens (PCNA) or p53 protein was analyzed immunohistochemically. Using consensus primers for the L1 region (L1-PCR), we identified 35 of 53 specimens (66%) as positive for HPV-38 DNA. Furthermore, specimens from patients over 60 years of age revealed a lower prevalence for the HPV-38 (56.7%) than did those below that age (78.3%). Immunohistochemically, positive stainings for PCNA and p53 protein were more frequently detected in HPV-38 positive OSCCs than HPV negative ones. These results indicate that HPV-38 positive OSCCs were higher in proliferative cellular activity than HPV negative ones. Moreover, the findings suggest that HPV-38 infection may cause malignant transformation of the oral mucosal epithelium.

Discovery of a novel murine keratin 6 (K6) isoform explains the absence of hair and nail defects in mice deficient for K6a and K6b.

The murine genome is known to have two keratin 6 (K6) genes, mouse K6 (MK6)a and MK6b. These genes display a complex expression pattern with constitutive expression in the epithelia of oral mucosa, hair follicles, and nail beds. We generated mice deficient for both genes through embryonic stem cell technology. The majority of MK6a/b−/− mice die of starvation within the first two weeks of life. This is due to a localized disintegration of the dorsal tongue epithelium, which results in the build up of a plaque of cell debris that severely impairs feeding. However, ∼25% of MK6a/b−/− mice survive to adulthood. Remarkably, the surviving MK6a/b−/− mice have normal hair and nails. To our surprise, we discovered MK6 staining both in the hair follicle and the nail bed of MK6a/b−/− mice, indicating the presence of a third MK6 gene. We cloned this previously unknown murine keratin gene and found it to be highly homologous to human K6hf, which is expressed in hair follicles. We therefore termed this gene MK6 hair follicle (MK6hf). The presence of MK6hf in the MK6a/b−/− follicles and nails offers an explanation for the absence of hair and nail defects in MK6a/b−/− animals.

ヒト培養複合口腔粘膜上皮層におけるＧｌｕｃｏｓｅ ｔｒａｎｓｐｏｒｔｅｒ １（ＧＬＵＴ１）発現

Recent studies have revealed that glucose transporter 1 (GLUT 1) expression can be detected in basal layer cells of skin. Expression levels of GLUT 1 are thought to be regulated by glucose transport activity within cells. Glucose metabolism in the epithelial layers may affect keratinocyte differentiation. We studied the localization of GLUT 1 expression in the epithelial layers of oral mucosa equivalents, grown in a defined serum-free culture medium without a feeder layer. The oral mucosa produced in this system is minimally exposed to potential foreign contaminants and is thus more acceptable for use in humans. Samples of native human gingiva and oral mucosa equivalents on days 4, 11, and 18 were fixed in 4% paraformaldehyde, embedded in paraffin, and cut into 5-micrometer-thick sections. For immunohistochemical studies, sections were stained by the ABC method using polyclonal antibodies to rabbit GLUT-1. Well-stratified, differentiated epithelial layers in day 18 oral mucosa equivalents had a similar keratinization pattern to that of native tissue. GLUT 1 was expressed in both the basal cell layer and suprabasal cell layer of oral mucosa epithelium, but not in the superficial layer. Immunoreactivity for GLUT-1 was detected in all epithelial layers of oral mucosa equivalents, except for the superficial layer of day 18 equivalents. In conclusion, keratinocytes of all layers of oral mucosa equivalents were in a highly active metabolic state and showed increased glycolysis, suggesting active proliferative and a less differentiated state as comnared with the basal and na.ra.ba.sa.1 cell lavers of native tissue.