Periodontal diseases, some of the most common infectious diseases seen in humans, are characterized by gingival inflammation, as well as loss of connective tissue and bone from around the roots of the teeth, which leads to eventual tooth exfoliation. In the past decade, the association of periodontal diseases with the development of systemic diseases has received increasing attention. Although a number of studies have presented evidence of close relationships between periodontal and systemic diseases, the majority of findings are limited to epidemiological studies, while the etiological details remain unclear. Nevertheless, a variety of recent hypothesis driven investigations have compiled various results showing that periodontal infection and subsequent direct oral-hematogenous spread of bacteria are implicated in the development of various systemic diseases. Herein, we present current understanding in regard to the relationship between periodontal and systemic diseases, including cardiovascular diseases, preterm delivery of low birth weight, diabetes mellitus, respiratory diseases, and osteoporosis.

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It has been reported that DNA of oral bacterial species, such as Porphyromonas gingivalis and Streptococcus mutans, was detected frequently in specimens of arteriosclerotic vessels. However, the source of DNA, whether from live intact bacteria or a part of the bacteria, has not been identified yet. Moreover, there was no precise evidence concerning involvement of oral bacteria in the progression of arteriosclerosis. We tried to clarify the involvement of P. gingivalis on the mechanisms of development of aortic intimal hyperplasia. Intravenous administration of P. gingivalis dramatically induced intimal hyperplasia in the mouse model with photochemical impairment of the femoral artery. However there were no changes identified in the mice without aortic impairment, even with the P. gingivalis infection. Concomitantly, S100 calcium–binding protein A9 (S100A9) and the embryonic isoform of myosin heavy chain (SMemb), a proliferative phenotypic marker of smooth muscle cells, were significantly overexpressed on the surfaces of smooth muscle cells present in the injured blood vessels. Similarly, increased expressions of S100A9 and SMemb proteins were observed in aneurismal specimens obtained from P. gingivalis–infected patients. We found that bacteremia induced by P. gingivalis leads to intimal hyperplasia associated with overexpressions of S100A9 and SMemb. Our results strongly suggest that oral-hematogenous spreading of P. gingivalis is a causative event in the development of aortic hyperplasia in periodontitis patients.

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Accumulating evidence suggests the involvement of Porphyromonas gingivalis (P. gingivalis), a periodontal pathogen, in cardiovascular diseases. Clinical specimens of aneurysmal tissue and dental plaque collected from patients infected with or without P. gingivalis were analyzed. The number of aneurysms in the distal aorta in the P. gingivalis–infected group was significantly higher than that in the non-infected group. Cellular accumulation of adipocytes in aneurysms was less frequently identified in the infected group. The expression of embryonic myosin heavy chain isoform, a phenotypic marker for proliferative smooth muscle cells, was higher in the P. gingivalis–infected group than the non-infected group. Clinical and histopathological features of aortic aneurysms associated with P. gingivalis infection are different from those present in non-infected patients. The major characteristic of P. gingivalis infection associated with aneurysms is smooth muscle cell proliferation in the distal aorta.

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Streptococcus mutans is generally known as a pathogen of dental caries, and it is also considered to cause bacteremia and infective endocarditis (IE). S. mutans was previously classified into 3 serotypes, c, e, and f, due to the different chemical compositions of the serotype-specific polysaccharides, which are composed of a rhamnose backbone and glucose side chains. We recently designated non-c/e/f serotype S. mutans strains as novel serotype k, which is characterized by a drastic reduction in the amount of the glucose side chain. A common biological feature of novel serotype-k strains is a lower level of cariogenicity due to alterations of several major cell surface protein antigens. As for virulence in blood, these strains survive in blood for a longer duration due to lower antigenicity, while the detection rate of all strains carrying the gene encoding collagen-binding adhesin has been shown to be high. Furthermore, molecular biological analyses of infected heart valve specimens obtained from IE patients revealed a high detection rate of serotype-k S. mutans. Together, these findings suggest that serotype-k S. mutans strains show low cariogenicity but high virulence in blood as compared to the other serotypes, due to alterations of several cell surface structures.

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Periodontal disease as a biofilm infectious disease is considered. Periodontal disease–associated bacteria formed biofilm in periodontal pockets or on the surface of cementum. Planktonic bacteria from biofilm invade into periodontal tissues and lead to inflammation and destruction of tissues directly and indirectly by eliciting the host defense mechanism. Supragingival dental plaques (biofilm) are easily removed by professional mechanical tooth cleaning, while subgingival dental plaques and bacteria invading into periodontal tissues are difficult to remove. Therefore, the development of a method for periodontal disease based on the concept that regards periodontal disease as a biofilm infectious disease is needed. Hereby, I report the effect of antibiotics on an in vitro biofilm model of periodontal disease and the systemic administration of azithromycin for early-onset (aggressive) periodontitis like a treatment resistant periodontitis.

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A multitarget herbal preparation, STW 5, has been used clinically in different gastro-intestinal disorders including functional dyspepsia and irritable bowel syndrome. Previous studies have shown that it possesses properties that may render it useful in gastro-oesophageal reflux disease (GERD). We performed this study to test this compound in an acute model of reflux oesophagitis in rats. Oesophagitis was induced surgically by ligating the pyloric end and fore-stomach. Lower oesophageal pH was measured 3 h later in conscious animals. Five hours after surgery, animals were sacrificed and the oesophagi were examined macroscopically and histologically. Selected markers of inflammation were measured in oesophageal homogenates. STW 5 was given orally for 5 days before induction of oesophagitis. Pantoprazole was used as a reference standard. Ligated animals showed a high incidence of ulcerative lesions associated with a marked increase in myeloperoxidase, thiobarbituric acid–reactive substances, tumor necrosis factor-α, and interleukin-1β. STW 5 did not affect oesophageal pH, but dose-dependently reduced the severity of the oesophageal lesions and normalized the deranged level of the inflammation markers. The beneficial effects were confirmed histopathologically. STW 5 proved to be effective in protecting against inflammatory lesions in this model of oesophagitis, thus warranting further investigation of its potential therapeutic usefulness in GERD.

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We investigated the effects of various emetic agents: cisplatin, apomorphine, lithium chloride (LiCl), rolipram, sibutramine, and the β₃-adrenoceptor (AR) agonist CL316243 on salivary amylase secretion in rats. We also determined the inhibitory effect of granisetron, a 5-HT₃–receptor antagonist, on cisplatin-induced increased salivary amylase activity and the inhibitory effect of bilateral abdominal vagotomy on increases in salivary amylase activity induced by cisplatin and LiCl. Granisetron was administered 15 min before and 1 h after cisplatin administration. Cisplatin (10 – 15 mg/kg, i.v.) increased salivary amylase activity dose-dependently and induced an acute increase from 1.5 h post-treatment with 15 mg/kg. Apomorphine (1 – 3 mg/kg, s.c.), LiCl (120 mg/kg, i.p.), rolipram (3 – 10 mg/kg, p.o.), and sibutramine (10 mg/kg, p.o.) induced significant increases in salivary amylase secretion. On the other hand, CL316243 did not stimulate salivary amylase secretion. The increased amylase activity induced by cisplatin (15 mg/kg, i.v.) was inhibited significantly by granisetron (1 or 3 mg/kg × 2, i.v.) or tended to be inhibited by bilateral abdominal vagotomy, whereas an increase in amylase activity produced by LiCl was not inhibited by abdominal visceral nerve section. These results suggest that salivary amylase activity is useful as a marker for emesis in rats, a species that does not exhibit vomiting.

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The present study examined the effect of the nitric oxide (NO) donor NOC18 on lipopolysaccharide (LPS)-induced NO production to investigate a regulation mechanism of NO production by microglial cells. LPS increased the levels of NO and inducible NO synthase (iNOS) protein in BV-2 murine microglial cells in a concentration-dependent manner. Pretreatment with NOC18 for 24 h concentration-dependently attenuated the LPS-induced iNOS protein expression and NO production. The inhibitory effect of NOC18 on LPS-induced NO production was partially blocked by LY83583, a soluble guanylate cyclase inhibitor. Pretreatment with dibutyryl guanosine-3′,5′-cyclic monophosphate (DBcGMP), a cell-permeable cGMP analogue, for 24 h attenuated partially LPS-induced iNOS protein expression and NO production. Furthermore, the effects of LPS on iNOS and NO production were inhibited by the c-Jun N-terminal kinase (JNK) inhibitor SP600125, and LPS-induced phosphorylation of JNK and c-Jun was inhibited by NOC18 and DBcGMP. These results suggest that NO production by microglial cells is controlled by a negative feedback mechanism via the NO/cGMP signaling pathway.

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Clinical studies have shown that angiotensin-receptor blockers (ARBs) reduce the risk of cardiovascular diseases in hypertensive patients. It is assumed that the reduction of the risk by ARBs may be attributed in part to the inhibition of angiotensin II (AII)-induced vascular smooth muscle cell (VSMC) migration associated with atherosclerosis. However, the effect of ARBs on AII-induced changes in intracellular signaling and resultant cell migration has not been well established. Here, we investigated the effect of olmesartan, an ARB, on AII-induced extracellular signal–regulated kinases 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK) activation and rat aortic smooth muscle cell (RASMC) migration. Olmesartan inhibited AII-induced ERK1/2 and JNK activation at lower concentrations (10 nM). On the other hand, PP2, a Src tyrosine kinase inhibitor, also inhibited AII-induced ERK1/2 and JNK activation, but its effect on ERK1/2 was less pronounced than that of olmesartan. Olmesartan, U0126 (an ERK1/2 inhibitor), SP600125 (a JNK inhibitor), and PP2 potently inhibited AII-induced RASMC migration. From these findings, it was inferred that angiotensin-receptor blockade by olmesartan results in the inhibition of AII-induced activation of Src, ERK1/2, and JNK in RASMC. Olmesartan may be a potent inhibitor of AII-induced VSMC migration, which may be involved in the progression of atherosclerosis.

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Two distinct α₁-adrenoceptor phenotypes (α_1A- and α_1L-ARs) are known to originate from a single ADRA1A(α_1a) gene by an as-yet-unknown mechanism. We hypothesized that an α_1a-AR–interacting protein could generate the α_1L-AR phenotype and we sought to identify such a protein and to examine its effects on the expression of α_1A and α_1L phenotypes. Cysteine-rich epidermal growth factor–like domain 1α (CRELD1α) was first identified using a yeast two-hybrid approach as an α_1a-AR–interacting protein. Transfection of α_1a-AR cDNA alone yielded Chinese hamster ovary (CHO) cells expressing α_1A-ARs having a predominant high affinity site for prazosin, with a low proportion (<10%) of prazosin-low affinity sites (α_1L-AR). Knockdown of endogenous CHO-CRELD1α [α_1a-CKD(α_1A-enhanced) cells] enhanced the expression of α_1A-AR, whereas over-expression of CRELD1α reduced α_1A-AR expression, yielding α_1a-COE(α_1L-dominant) cells expressing a high proportion (50%) of the α_1L-AR phenotype. The ligand binding and functional agonist and antagonist profiles in α_1a-CKD(α_1A-enhanced) and α_1a-COE(α_1L-dominant) cell lines were entirely in accord with the α_1A-AR and α_1L-AR phenotypes observed in intact tissues. CRELD1α down-regulates expression of the α_1A-AR, thereby enhancing the proportion of expression of the α_1L-AR phenotype. The α_1L-AR–expressing α_1a-COE(α_1L-dominant) cell line reflects accurately the phenotype of this AR observed in vivo and will facilitate development of α_1L-AR–targeted drugs.

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CV-159, a 1,4-dihydropyridine derivative, has Ca²⁺ antagonistic and anti-calmodulin actions. An early feature of atherosclerosis is vascular endothelial inflammatory change. We examined whether CV-159 has protective effects against endothelial inflammatory responses. After pretreatment of human umbilical vein endothelial cells (ECs) with CV-159 (10 μM, 30 min), TNF-α (10 ng/ml) was applied for 20 min or 24 h. Expressions of inflammatory markers and activation of inflammatory signal molecules were examined by Western blotting. Reactive oxygen species (ROS) generation was examined by using 2′,7′-dichlorodihydrofluorescein diacetate. CV-159 inhibited TNF (24 h)–induced expression of e-selectin but not vascular cell adhesion molecule-1 and intercellular adhesion molecule-1. CV-159 inhibited TNF (20 min)–induced phosphorylation of JNK, p38, and NF-κB p65 (Ser536). A JNK inhibitor, SP600125, and a p38 inhibitor, SB203580, inhibited TNF-induced e-selectin expression. An antioxidant drug, N-acetyl-L-cysteine (NAC), inhibited TNF-induced e-selectin expression. NAC inhibited TNF-induced phosphorylation of JNK and p38 but not NF-κB. CV-159 inhibited TNF-induced ROS generation. Our results indicate that in ECs CV-159 specifically inhibits TNF-induced e-selectin expression through inhibition of JNK, p38, and NF-κB phosphorylation. It is suggested that CV-159 prevents activation of JNK and p38 through inhibition of ROS, while it prevents activation of NF-κB via a ROS-independent manner.

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Aristolochic acids (AAs), contained in Chinese herbal preparations, have been considered to induce nephropathy. In order to elucidate the molecular mechanisms of AA-induced nephrotoxicity, we have elucidated the interaction of human organic anion transporters (hOATs) with AAs using their stable cell lines. AA-I and AA-II inhibited organic anion uptake by hOAT1, hOAT3, and hOAT4 in dose-dependent manners. Treatment of hOAT3 with AA-I resulted in a significant reduction in viability compared with that of mock, which was rescued by the organic anion transport inhibitor probenecid. In conclusion, hOAT3-mediated AA-I uptake may be associated with the induction of nephrotoxicity.

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3,4-Methylenedioxymethamphetamine (MDMA) causes serotonin efflux via serotonin transporter. Recently, we have reported that sustained exposure to MDMA induced an augmentation of serotonin release in rat raphe serotonergic slice cultures. Here we investigated the mechanism of augmented serotonin release from the slice cultures. Sustained MDMA exposure had no effect on MDMA-induced serotonin efflux in the synaptosomal fraction, whereas either tetrodotoxin, calcium channel inhibitors, or AMPA-receptor antagonists significantly attenuated the augmented serotonin release. These results suggest that the increase in Ca²⁺-dependent exocytotic serotonin release is mediated through activation of AMPA receptors and responsible for the sustained MDMA-induced augmentation of serotonin release.

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