Phylogenetic and functional gene structure shifts of the oral microbiomes in periodontitis patients.

Determining the composition and function of subgingival dental plaque is crucial to understanding human periodontal health and disease, but it is challenging because of the complexity of the interactions between human microbiomes and human body. Here, we examined the phylogenetic and functional gene differences between periodontal and healthy individuals using MiSeq sequencing of 16S rRNA gene amplicons and a specific functional gene array (a combination of GeoChip 4.0 for biogeochemical processes and HuMiChip 1.0 for human microbiomes). Our analyses indicated that the phylogenetic and functional gene structure of the oral microbiomes were distinctly different between periodontal and healthy groups. Also, 16S rRNA gene sequencing analysis indicated that 39 genera were significantly different between healthy and periodontitis groups, and Fusobacterium, Porphyromonas, Treponema, Filifactor, Eubacterium, Tannerella, Hallella, Parvimonas, Peptostreptococcus and Catonella showed higher relative abundances in the periodontitis group. In addition, functional gene array data showed that a lower gene number but higher signal intensity of major genes existed in periodontitis, and a variety of genes involved in virulence factors, amino acid metabolism and glycosaminoglycan and pyrimidine degradation were enriched in periodontitis, suggesting their potential importance in periodontal pathogenesis. However, the genes involved in amino acid synthesis and pyrimidine synthesis exhibited a significantly lower relative abundance compared with healthy group. Overall, this study provides new insights into our understanding of phylogenetic and functional gene structure of subgingival microbial communities of periodontal patients and their importance in pathogenesis of periodontitis.

JNK/P38 mitogen-activated protein kinase used for hepatocyte growth factor-induced proliferation, differentiation, and migration in human dental papilla cells.

INTRODUCTION: Hepatocyte growth factor (HGF) is a multifunctional cytokine that is able to stimulate multiple intracellular signaling pathways to induce a remarkable variety of biological activities in a wide spectrum of cell types. The functions of HGF in modulating diverse biological responses in mesenchymal stem cells have been reported, and our previous study also demonstrated that HGF exerts promoting functions on murine dental papilla cells. However, the potential mechanisms involved are not yet clearly understood. This study investigated the signaling pathway used by HGF in human dental papilla cells (hDPCs) to identify the role of mitogen-activated protein kinase (MAPK) pathways in inducing cell proliferation, differentiation, and migration. METHODS: The activation of P38 kinase and Jun N-terminal kinase (JNK) was analyzed by using specific antibodies against phospho-P38 and phospho-JNK. Proliferation of hDPCS was measured using the WST-8 assay with Cell Counting Kit-8, cell differentiation was determined by using alkaline phosphatase activity and mineralization assays, and migration was investigated by in vitro wound healing and transwell migration assays. Immunofluorescence staining was used to visualize fibrous actin (F-actin). RESULTS: HGF activated JNK and P38 MAPK pathways in hDPCs. Blockage of JNK or P38 pathway in hDPCs significantly reduced cell proliferation, alkaline phosphatase activities, as well as mineral nodule formation induced by HGF. The JNK and P38 inhibitors also influenced F-actin remodeling stimulated by HGF and thus contributed to HGF-induced hDPCs migration. CONCLUSIONS: Data from this study indicated that JNK and P38 MAPK pathways are required in HGF-induced biological responses in hDPCs.