Molecular characterization of amelogenesis imperfecta in Chinese patients

BACKGROUND

Mutations in 6 genes have been identified as being part of the etiology of amelogenesis imperfecta (AI) with various phenotypes in an isolated condition. Among them the FAM83H gene is the major contributor to the etiology of AI with unknown function.

OBJECTIVE

This study aims to determine the phenotypic and molecular characterization of Chinese AI patients and to analyze the structure and function of the FAM83H protein.

METHODS

We enrolled 6 hypocalcified AI and 3 hypoplastic AI families from the Chinese population. Mutation analysis was performed by amplifying and sequencing all exons including intron-exon borders for FAM83H and ENAM genes. Structural modeling and function analysis on the FAM83H protein were carried out by bioinformatic processing.

RESULTS

No obvious anterior open bite was observed in all the investigated individuals. Five mutations (c.906T>G, c.924dupT, c.973C>T, c.1354C>T and c.2029C>T) in the C-terminal of the FAM83H gene were revealed, respectively, in 5 out of 6 hypocalcified AI families, and a splicing mutation c.534 + 1G>A in the ENAM gene was identified in 1 out of 3 hypoplastic AI families. Structural models of the N- and C-terminal regions of FAM83H were generated by homology modeling. The predicted structure of the FAM83H N-terminal shows resemblance to that of glycosyltransferases with GT-A folds, and the predicted structure of the FAM83H C-terminal possesses similarity to type I collagen protein.

CONCLUSIONS

To our knowledge, this is the first report of AI with specific molecular variations in families of Chinese descent. Our study provides new insights into the structure and function of the FAM83H protein.

Interleukin-17 exacerbates hepatic steatosis and inflammation in non-alcoholic fatty liver disease

Mechanisms associated with the progression of simple steatosis to non-alcoholic fatty liver disease (NAFLD) remain undefined. Regulatory T cells (T(regs)) play a critical role in regulating inflammatory processes in non-alcoholic steatohepatitis (NASH) and because T helper type 17 (Th17) functionally oppose T(reg)-mediated responses, this study focused on characterizing the role of Th17 cells using a NAFLD mouse model. C57BL/6 mice were fed either a normal diet (ND) or high fat (HF) diet for 8 weeks. Mice in the HF group had a significantly higher frequency of liver Th17 cells compared to ND-fed mice. Neutralization of interleukin (IL)-17 in HF mice ameliorated lipopolysaccharide (LPS)-induced liver injury reflected by decreased serum alanine aminotransferase (ALT) levels and reduced inflammatory cell infiltrates in the liver. In vitro, HepG2 cells cultured in the presence of free fatty acids (FFA; oleic acid and palmitic acid) for 24 h and IL-17 developed steatosis via insulin-signalling pathway interference. IL-17 and FFAs synergized to induce IL-6 production by HepG2 cells and murine primary hepatocytes which, in combination with transforming growth factor (TGF-β), expanded Th17 cells. It is likely that a similar process occurs in NASH patients, as there were significant levels of IL-17(+) cell infiltrates in NASH patient livers. The hepatic expression of Th17 cell-related genes [retinoid-related orphan receptor gamma (ROR)γt, IL-17, IL-21 and IL-23] was also increased significantly in NASH patients compared to healthy controls. Th17 cells and IL-17 were associated with hepatic steatosis and proinflammatory response in NAFLD and facilitated the transition from simple steatosis to steatohepatitis. Strategies designed to alter the balance between Th17 cells and T(regs) should be explored as a means of preventing progression to NASH and advanced liver diseases in NAFLD patients.

The prevalence of and risk factors for non-carious cervical lesions in adults in Hubei Province, China

OBJECTIVES

To describe the prevalence of non-carious cervical lesions (NCCLs) and to assess the relative affects of risk factors on NCCLs in middle-aged and elderly people in Hubei Province, China.

DESIGN

A sample of 2,160 adults, aged 35-44 years and 65-74 years and balanced by age, gender, and urbanization, participated in the cross sectional epidemiological survey. Non-carious cervical lesions were examined using a modified Tooth Wear Index. Data were collected based on structured questionnaires that assessed general information as well as oral health.

RESULTS

The prevalence of non-carious cervical lesions was 38.8% for 35-44-year-olds and 56.6% for 65-74-year-olds. The first premolars, canines, and second premolars showed the highest prevalence of lesions, while the second molars demonstrated the least. Several risk factors such as age (OR = 2.45, p < 0.001), location (OR = 1.68, p = 0.001), frequency of toothbrushing (OR = 1.33, p = 0.016), bruxism (OR = 1.37, p < 0.001), and family income (OR = 1.44, p < 0.001) were found to be associated with lesion occurrence.

CONCLUSIONS

The prevalence of non-carious cervical lesions was relatively high in the middle-aged and elderly persons in China and was also associated with socio-behavioural risk factors.

TP63 gene mutations in Chinese P63 syndrome patients

TP63 plays an essential role in the development of epidermis and skin appendages. Mutations in TP63 can give rise to a series of syndromes characterized by various combinations of ectodermal dysplasia, limb malformations, and orofacial clefting in many populations. To test whether TP63 is the disease-causative gene for these phenotypes in Chinese, we recruited two Chinese Ectrodactyly-Ectodermal-dysplasia-Cleft lip/palate syndrome (EEC) cases and a Limb-Mammary-Syndrome (LMS) patient to carry out TP63 gene sequencing. Three missense mutation, c.812G>C (Ser271Thr), c.611G>A (Arg204Gln), and c.680G>A (Arg227Gln), which lead to the substitution of highly conserved amino acids in the DNA-binding domain of TP63, were identified. These mutations were predicted to disrupt DNA-binding specificity and affinity. To our knowledge, this is the first report of EEC and LMS syndromes in individuals of Chinese descent. Analysis of our data demonstrated that TP63 is critical for the development of ectoderm in humans.

FSH aggravates periodontitis-related bone loss in ovariectomized rats

Alveolar bone loss is one of the prominent pathologic and clinical features of periodontitis. Recently, the direct effect of follicle-stimulating hormone (FSH) on bone resorption has been demonstrated. However, the effect of FSH on alveolar bone loss remains unknown. This study tested the hypothesis that FSH would exacerbate periodontitis-related alveolar bone loss. Experimental periodontitis was induced in ovariectomized rats, and the rats were treated with extrinsic FSH or its inhibitor, leuprorelin. After mandibles were collected, we performed morphological examinations to evaluate bone loss, enzyme histochemical tests for osteoclasts, and immunohistochemical examinations for FSH receptor (FSHR). The results showed that FSH significantly increased alveolar bone resorption compared with non-FSH-treated ovariectomized rats (P < 0.05), and the number of FSHR-positive cells was positively correlated with alveolar bone loss area (r = 0.682, P < 0.01). Our results suggested that FSH can aggravate alveolar bone loss by FSHR, independent of estrogen.

Mineralized Tissue Formation by BMP2-transfected Pulp Stem Cells

Previously, in vitro differentiation of odontoblasts was shown for dental pulp stem cells (DPSCs) transfected with bone morphogenetic protein-2 ( Bmp2). For this study, we hypothesized that such cells also show potential for mineralized tissue formation in vivo. DPSCs were transfected with Bmp2 and seeded onto a ceramic scaffold. These complexes were cultured in medium without dexamethasone, and thereafter placed subcutaneously in nude mice for 1, 4, and 12 weeks. Samples were evaluated by histology and real-time PCR for osteocalcin, bone sialoprotein, dentin sialophosphoprotein, and dentin matrix protein 1. Results indicated that only the transfected DPSCs showed obvious mineralized tissue generation, and 12 weeks of implantation gave the highest percentage of mineralized tissue formation (33 ± 7.3% of implant pore area). Real-time PCR confirmed these results. In conclusion, Bmp2-transfected DPSCs effectively show mineralized tissue formation upon ectopic implantation.