Aki Namba

Phylogenetic analysis of intestinal bacteria and their adhesive capability in relation to the intestinal mucus of carp

Aims:  The aims of the present study are to characterize the intestinal microbial community displaying a high‐adhesive capability in fish, and to evaluate the relationship between mucosal adhesion of intestinal bacteria and fish health and disease.

Effects of IL-6 and soluble IL-6 receptor on the expression of cartilage matrix proteins in human chondrocytes.

Elevated concentrations of interleukin (IL)-6 and soluble IL-6 receptor (sIL-6Rα) in synovial fluid have been implicated in joint cartilage destruction. We examined the effect of IL-6 and sIL-6Rα on cell growth, alkaline phosphatase (ALPase) activity, and the expression of Sox-9, type II collagen, aggrecan core, link protein, BMP-7, and BMP receptors in human chondrocytes. Cell proliferation increased slightly in the presence of both IL-6 and sIL-6Rα, whereas ALPase activity decreased markedly. The expression of Sox-9 and aggrecan core did not change in the presence or absence of IL-6 and sIL-6Rα, whereas the expression of type II collagen, link protein, BMP-7, and BMP receptors increased in the presence of both IL-6 and sIL-6Rα. These results suggest that IL-6 and sIL-6Rα suppress the differentiation of chondrocytes and induce the repair of arthrodial cartilage through an increase in the expression of cartilage matrix proteins, BMP-7, and BMP receptors in the cells.

IL-1 Stimulates the Expression of Prostaglandin Receptor EP4 in Human Chondrocytes by Increasing Production of Prostaglandin E2

Prostaglandin (PG) E2, which exerts its actions via the PG receptors EP1–4, is produced from arachidonic acid by cyclooxygenase (COX)-1 and COX-2. The aim of this study was to investigate the mechanisms by which interleukin (IL)-1β induces the expression of PG receptors in cultured human chondrocytes and to explore the role of PGE2 in this process. The cells were cultured with 0, 10, or 100 U/mL IL-1β with or without 1 μM celecoxib, a specific inhibitor of COX-2, for up to 28 days. Expression of the genes encoding COX-1, COX-2, and EP1–4 was quantified using real-time PCR, and expression of the corresponding proteins was examined using immunohistochemical staining. PGE2 production was determined using ELISA. IL-1β treatment caused a marked dose- and time-dependent increase in the levels of PGE2, COX-2, and EP4 as compared with the untreated control. It did not affect the expression of COX-1, and it decreased the expression of EP1 and EP2. EP3 expression was not detected in either the absence or the presence of IL-1β. When celecoxib was also present, IL-1β failed to stimulate PGE2 production and EP4 expression, but its stimulatory effect on COX-2 expression and its inhibitory effect on EP1 and EP2 expression were unchanged. IL-1β increases the production of PGE2, COX-2, and the PG receptor EP4 in cultured human chondrocytes. The increase in EP4 expression appears to be a result of the increased PGE2 production.

OmpA is an adhesion factor of Aeromonas veronii, an optimistic pathogen that habituates in carp intestinal tract.

Aims:  In the present study, we focused on one of the Aeromonas veronii isolates that exhibited marked adhesion onto carp intestine and studied its membrane‐associated proteins for their possible involvement in mucosal adhesion.

A new primer for 16S rDNA analysis of microbial communities associated with Porphyra yezoensis

To construct high-quality 16S rDNA clone libraries for microbial communities associated with Porphyra yezoensis and to minimize the detection of rDNA from leafy gametophytes of P. yezoensis, we designed a new 16S rDNA universal primer (75F). Of the clones prepared using 75F, which was designed to distinguish between bacteria and P. yezoensis, 95% were classified into four groups, namely, β-proteobacteria, γ-proteobacteria, Lentisphaerae, and Flavobacteria. PCR-based analysis of the 16S rDNA primer constructed in this study can be used to implement 16S rDNA-based methodologies for the investigation of microbial community composition and diversity related to the Porphyra group.

IL-1β Suppresses the Formation of Osteoclasts by Increasing OPG Production via an Autocrine Mechanism Involving Celecoxib-Related Prostaglandins in Chondrocytes

Elevated interleukin (IL)-1 concentrations in synovial fluid have been implicated in joint bone and cartilage destruction. Previously, we showed that IL-1β stimulated the expression of prostaglandin (PG) receptor EP4 via increased PGE2 production. However, the effect of IL-1β on osteoclast formation via chondrocytes is unclear. Therefore, we examined the effect of IL-1β and/or celecoxib on the expression of macrophage colony-stimulating factor (M-CSF), receptor activator of NF-κB ligand (RANKL), and osteoprotegerin (OPG) in human chondrocytes, and the indirect effect of IL-1β on osteoclast-like cell formation using RAW264.7 cells. OPG and RANKL expression increased with IL-1β; whereas M-CSF expression decreased. Celecoxib blocked the stimulatory effect of IL-1β. Conditioned medium from IL-1β-treated chondrocytes decreased TRAP staining in RAW264.7 cells. These results suggest that IL-1β suppresses the formation of osteoclast-like cells via increased OPG production and decreased M-CSF production in chondrocytes, and OPG production may increase through an autocrine mechanism involving celecoxib-related PGs.