Loss of epithelial FAM20A in mice causes amelogenesis imperfecta, tooth eruption delay and gingival overgrowth

FAM20A has been studied to a very limited extent. Mutations in human FAM20A cause amelogenesis imperfecta, gingival fibromatosis and kidney problems. It would be desirable to systemically analyse the expression of FAM20A in dental tissues and to assess the pathological changes when this molecule is specifically nullified in individual tissues. Recently, we generated mice with a Fam2OA-floxed allele containing the beta-galactosidase reporter gene. We analysed FAM20A expression in dental tissues using X-Gal staining, immunohistochemistry and in situ hybridization, which showed that the ameloblasts in the mouse mandibular first molar began to express FAM20A at 1 day after birth, and the reduced enamel epithelium in erupting molars expressed a significant level of FAM2OA. By breeding K14-Cre mice with Fam20An^x/fl^x mice, we created K14-Cre;Fam20Af/flox/flox （conditional knock out, cKO） mice, in which Fam20A was inactivated in the epithelium. We analysed the dental tissues of cKO mice using X-ray radiography： histology and immunohistochemistry. The molar enamel matrix in cKO mice was much thinner than normal and was often separated from the dentinoenamel junction. The Fam2OA-deficient ameloblasts were non-polarized and disorganized and were detached from the enamel matrix. The enamel abnormality in cKO mice was consistent with the diagnosis of amelogenesis imperfecta. The levels of enamelin and matrix metalloproteinase 20 were lower in the ameloblasts and enamel of cKO mice than the normal mice, The cKO mice had remarkable delays in the eruption of molars and hyperplasia of the gingival epithelium. The findings emphasize the essential roles of FAM20A in the development of dental and oral tissues.

Drug-induced gingival overgrowth in cardiovascular patients

Drug-induced gingival overgrowth(DIGO)is a pathological growth of gingival tissue,primarily associated with calcium channel blockers and immunosuppressants.Consequently,it is mainly seen in cardiovascular and transplanted patients.Nifedipine remains the main calcium channel blocker related to the development of this unpleasant side-effect.As for immunosuppress-ants,cyclosporin is the leading causative agent,whereas other drugs from this druggroup,including tacrolimus,have better safety profiles.Accumulated collagen with inflammatory infiltrates is the histological hallmark of this condition.Several factors are involved in the pathogenesis and can increase the risk,such as male gender,younger age,pre-existing periodontal inflammation,and concomitant use of other DIGO-inducing medications.Patients with DIGO may experience severe discomfort,trouble with speech and mastication,pain,and teeth loss,aside from cosmetic implications.Furthermore,these patients also have an increased risk for cardiovascular diseases.The interdisciplinary approach and cooperation with dental care experts are necessary for patient management.Treatment includes discontinuing the drug and switching to one with a better profile,improving oral hygiene,and surgical removal of enlarged tissue.Recognizing the potential of commonly used medications to cause DIGO and its effect on patients'health is necessary for early detection and adequate management of this complication.

Changes in Biomarkers after Initial Periodontal Treatment in Gingival Crevicular Fluid from Patients with Chronic Periodontitis Presenting with Drug-Induced Gingival Overgrowth

Calcium channel blocker-induced gingival overgrowth (CCB-GO) is increasing in elderly patients who have been prescribed medication for hypertension for years. The purpose of the present study was to analyze the comprehensive protein expression levels of candidate biomarkers in gingival crevicular fluid (GCF) from CCB-GO patients. Eleven GO patients (10 males and one female, mean ± SD: age: 64.4 ± 14.0 years) who had been systemically prescribed CCBs, either amlodipine or nifedipine, for hypertension for at least 12 months were recruited. Before (baseline) and 4 weeks after initial periodontal treatments, subgingival plaque and GCF samples were taken from two sites per patient: sites affected by CCB-GO and chronic periodontitis. Measurement of clinical parameters and quantitative analysis of periodontopathic bacteria using real-time PCR were performed. Biomarkers/cytokines in GCF were examined using multiplex bead immunoassays. The Mann-Whitney U test was used to compare the collected data between groups. The correlations between pairs of biomarkers were assessed using the Spearman correlation relationship. Levels of two of the 14 biomarkers, interleukin (IL)-1β and transforming growth factor (TGF)- β, were significantly decreased in CCB-GO sites after initial periodontal therapy. The intragroup comparison at baseline showed that counts of Treponema denticola in the GO group were significantly higher than those in the chronic periodontitis group (P β and TGF-β in CCB-GO patients. These factors are involved in initiation and progression of GO as well as periodontitis.

Angiotensin Ⅱ stimulates expression of transcription factors c-Jun and c-Fos in cyclosporine induced human gingival fibroblasts

The present study demonstrates that the expression of c-Jun and c-Fos are elevated in gingival fibroblast cells treated with angiotensin Ⅱ and cyclosporine.The healthy human gingival tissues were collected and gingival fibroblasts were isolated and cultured.We used RT-PCR and Western blot analysis to identify the expression of c-Jun and c-Fos in cyclosporine and angiotensin II treated human gingival fibroblast cells.We found that angiotensin Ⅱ in combination with cyclosporine induces c-Jun and c-Fos expressions significantly;however,the angiotensin Ⅱ antagonist losartan inhibits the expression of c-Jun and c-Fos(p<0.01).The data suggest that angiotensin Ⅱ in combination with cyclosporine modulates the expression of c-Jun and c-Fos in human gingival fibroblast cells.