Abiotrophia defectiva is a nutritionally variant streptococci that is found in the oral cavity, and it is an etiologic agent of infective endocarditis. We have previously reported the binding activity of A. defectiva to fibronectin and to human umbilical vein endothelial cells (HUVECs). However, the contribution of some adhesion factors on the binding properties has not been well delineated. In this study, we identified DnaK, a chaperon protein, as being one of the binding molecules of A. defectiva to fibronectin. Recombinant DnaK (rDnaK) bound immobilized fibronectin in a concentration-dependent manner, and anti-DnaK antiserum reduced the binding activity of A. defectiva with both fibronectin and HUVECs. Furthermore, DnaK were observed on the cell surfaces via immune-electroscopic analysis with anti-DnaK antiserum. Expression of IL-8, CCL2, ICAM-1, and VCAM-1 was upregulated with the A. defectiva rDnaK treatment in HUVECs. Furthermore, TNF-α secretion of THP-1 macrophages was also upregulated with the rDnaK. We observed these upregulations in rDnaK treated with polymyxin B, but not in the heat-treated rDnaK. The findings show that A. defectiva DnaK functions not only as an adhesin to HUVECs via the binding to fibronectin but also as a proinflammatory agent in the pathogenicity to cause infective endocarditis.

Lactic acid (LA) is short-chain fatty acid, such as butyric acid and propionic acid, that is produced as a metabolite of lactic acid bacteria, including periodontopathic bacteria. These short-chain fatty acids have positive effects on human health but can also have negative effects, such as the promotion of periodontal disease (PD), which is caused by periodontal pathogens present in the gingival sulcus. PD is characterized by apical migration of junctional epithelium, deepening of pockets, and alveolar bone loss. Thus, the junctional epithelial cells that form the bottom of the gingival sulcus are extremely important in investigating the pathophysiology of PD. The aim of this study was to investigate the effect of LA on wound healing, cell growth, cell cycle kinetics, and gene expression of cultured junctional epithelium cells. The results showed that stimulation with 10 mM LA slowed wound healing of the junctional epithelial cell layer and arrested the cell cycle in the G0/G1 (early cell cycle) phase, thereby inhibiting cell growth. However, cell destruction was not observed. LA also enhanced mRNA expression of integrin α5, interleukin (IL)-6, IL-8, intercellular adhesion molecule-1, and receptor activator of nuclear factor kappa-B ligand. The results of this study suggest that stimulation of junctional epithelial cells with high concentrations of LA could exacerbate PD, similarly to butyric acid and propionic acid.

α-chlorohydrin (ACH) is a known male reproductive toxicant and produces antifertility in rats. The present experiments were performed to determine the relationship between sperm motions and reproductive function, and to further examine the possible mechanism for antifertility. ACH was administered to male rats for 9 days at 1, 3 and 10 mg/kg/day. The males were mated with untreated females and their reproductive status was determined. All mated males failed to impregnate females at 10 mg/kg/day. Low pregnancy rate associated with a decreased implant number was seen at 3 mg/kg/day. When sperm motions were analyzed using the CellSoft^TM computer-assisted sperm analyzer, percentage of motile sperm, curvilinear velocity (VCL) and amplitude of lateral head displacement (ALH) were reduced at 10 mg/kg/day. At 3 mg/kg/day, VCL and ALH were reduced but the percentage of motile sperm was comparable to that of controls. In order to examine a possible mechanism for the effect of ACH on fertility, the number of sperm reaching the oviducts of mated females and the number of fertilized eggs was evaluated. Half of the females mated with ACH-treated males at 3 mg/kg/day had very low sperm numbers in the oviducts. At 10 mg/kg/day, all the mated females had a very low sperm number. The percent of fertilized eggs in the oviducts of mated females was decreased in a dose-dependent manner. These findings suggest that the effect of ACH on fertility was directly related to decreased VCL and ALH as well as percentage of motile sperm, and by the mechanism in which the sperm number reaching the oviducts after mating was reduced, so the reduction resulted in only a rare chance to fertilize.

Granulicatella adiacens (G. adiacens) and Abiotrophia defectiva (A. defectiva) colonize the oral cavity and form part of the normal flora in the intestinal and genitourinary tracts. As reported previously, the frequency of isolation of G. adiacens from the oral cavity was much higher than that of A. defectiva. However, it has been reported that compared with G. adiacens, A. defectiva was isolated at considerably higher frequencies from the blood of patients with infective endocarditis (IE). Hence, in this study, the in vitro interaction of G. adiacens and A. defectiva strains with host surfaces and biofilm formation was examined to assess whether their different adhesive properties contribute to their associations with oral colonization and IE, respectively. G. adiacens exhibited an increased binding ability to saliva-coated hydroxyapatite beads than A. defectiva following the addition of CaCl2. Furthermore, biofilm formation was observed only for G. adiacens with the use of a polystyrene tube and scanning electron microscopy analysis. Conversely, A. defectiva displayed significantly greater adherence to human umbilical vein endothelial cells and immobilized fibronectin than G. adiacens. These findings suggest that differences in binding properties to host components imply specific binding mechanisms in G. adiacens and A. defectiva, which might mediate selective colonization in the oral cavity or are associated with the pathogenicity of endocarditis.