Shigeno Saito

Inhibition of a Porphyromonas gingivalis colonizing factor between Actinomyces viscosus ATCC 19246 by monoclonal antibodies against recombinant 40-kDa outer-membrane protein.

1. Porphyromonas gingivalis, an important pathogen in human periodontal disease, aggregates with Actinomyces viscosus ATCC 19246. 2. Monoclonal antibodies (mAbs) against purified recombinant 40-kDa outer-membrane protein (r40-kDa, OMP) of P. gingivalis 381 inhibited its coaggregation with A. viscosus ATCC 19246 in a dose-dependent manner. 3. Five mAb clones against r40-kDa OMP were selected. The isotype of the five was IgG1. 4. Pg-ompA2 inhibited the coaggregation of several strains of P. gingivalis with A. viscosus ATCC 19246 cells.

Enhancement of lipopolysaccharide-stimulated cyclooxygenase-2 mRNA expression and prostaglandin E2 production in gingival fibroblasts from individuals with Down syndrome.

It is well known that Down syndrome (DS) is a premature ageing syndrome. Periodontal disease in individuals with DS develops rapidly and extensively in a relatively younger age bracket compared with that in healthy controls. The mechanisms involved in the periodontal inflammatory processes in DS patients are not fully understood. In the present study, the non-inflamed gingival fibroblasts isolated from seven patients with DS (DGF) and seven healthy controls (NDGF) were stimulated with lipopolysaccharide (LPS) derived from Actinobacillus actinomycetemcomitans (A. a.). We measured the level of prostaglandin E2 (PGE2) production by DGF and NDGF by radioimmunoassay, and also measured the mRNA expression of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) by using the real-time PCR method. We found the higher levels of LPS-stimulated COX-2 mRNA expression and PGE2 production in DGF when compared with those in NDGF. This study may indicate that overexpression of LPS-stimulated COX-2 induced a greater ability of DGF to produce PGE2, and that these phenomena may be responsible for the severer periodontal disease in DS patients.

Caffeine Enhances the Expression of the Angiotensin II Type 2 Receptor mRNA in BeWo Cell Culture and in the Rat Placenta

Although chronic caffeine exposure during pregnancy has been shown to affect fetal growth, adverse effects of caffeine on embryogenesis are not only well understood, but also controversial. We have used gene chip technology in an attempt to identify to what extent, if any, caffeine could possibly alter gene expressions in the cytotrophoblast-like cell line BeWo. Few down-regulated genes were found; most of the genes were up-regulated, suggesting that chronic caffeine exposure during the gestational period could exert certain influences on embryogenesis. The highest up-regulated gene expression of BeWo cells by caffeine was angiotensin II type 2 (AT(2)) receptor gene. We focused the genes of the renin-angiotensin system (RAS), angiotensin II type 1 (AT(1)) and AT(2)receptors and angiotensin I converting enzyme, for study on caffeines responsive gene expression in BeWo cells and in the placentae of pregnant rats that were fed a diet supplemented with caffeine (2 mg/100 g body weight) during gestation, and analysed the gene expressions using RT-PCR and LightCycler system. A significantly increased AT(2)receptor gene expression and a slight decreased AT(1)receptor gene expression demonstrated the caffeines effect to the placental RAS.

Cloning of the gene for cell-surface protein antigen A from streptococcus sobrinus (serotype d)

A gene library of Strep. sobrinus B13N (serotype d) chromosomal DNA was constructed in Escherichia coli, with the bacteriophage vector lambda L47.1. A recombinant phage, lambda MDSM49, containing a 15.5 kb DNA insert, directed the expression of a 210 kDa antigenic protein. The recombinant 210 kDa protein was shown by Western blot analysis to be identical with cell-surface protein antigen A (spaA) from a serotype g strain. However, the restriction patterns of a subclone plasmid, pMD51, from lambda MDSM49 differed from those of serotype g strain. The cell-surface protein antigen I/II from serotype c Streptococcus mutans is a potential immunogen for vaccination against dental caries and corresponds to the spaA from serotype d and g strains. A recombinant clone, pDM51, will be a useful tool for serological and molecular biological studies. The recombinant spaA provides useful material for assessment of its diagnostic and immunogenic potential.

Suppression of proliferation of a human B-cell leukaemic cell line derived from acute lymphoblastic leukaemia by soluble factor(s) from Campylobacter rectus

Soluble sonic extracts of several strains were examined for their ability to alter proliferation of a cell line derived from acute lymphoblastic leukaemia (BALL-1). Extracts of all strains tested caused dose-dependent suppression of proliferation when assessed by DNA (tritiated thymidine incorporation), RNA (tritiated uridine incorporation) and protein (tritiated leucine incorporation) synthesis. There was no effect on the viability of BALL-1 as measured by either trypan-blue exclusion or extracellular release of the cytoplasmic enzyme lactate dehydrogenase. The suppressive factor(s) was separated in a well-defined peak by high-pressure liquid DEAE ion-exchange chromatography, which revealed a single active peak with a molecular mass of 48 kDa. Characterization of the peak indicated that the suppressive factor(s) was heat labile (activity destroyed at 80 degrees C) and sensitive to the proteolytic enzyme pronase P. The soluble suppressive factor(s) from Campylobacter rectus thus has protein-like properties and no cytotoxicity to a human B-cell leukaemic cell line.