Altered gene expression in leukocyte transendothelial migration and cell communication pathways in periodontitis-affected gingival tissues

BACKGROUND AND OBJECTIVE

Gene expression is related to the pathogenesis of periodontitis and plays a crucial role in local tissue destruction and disease susceptibility. The aims of the present study were to identify the expression of specific genes and biological pathways in periodontitis-affected gingival tissue using microarray and quantitative real-time RT-PCR analyses.

MATERIAL AND METHODS

Healthy and periodontitis-affected gingival tissues were taken from three patients with severe chronic periodontitis. Total RNAs from six gingival tissue samples were used for microarray analyses. Data-mining analyses, such as comparisons, gene ontology and pathway analyses, were performed and biological pathways with a significant role in periodontitis were identified. In addition, quantitative real-time RT-PCR analysis was performed on samples obtained from 14 patients with chronic periodontitis and from 14 healthy individuals in order to confirm the results of the pathway analysis.

RESULTS

Comparison analyses found 15 up-regulated and 13 down-regulated genes (all of which showed a change of more than twofold in expression levels) in periodontitis-affected gingival tissues. Pathway analysis identified 15 up-regulated biological pathways, including leukocyte transendothelial migration, and five down-regulated pathways, including cell communication. Quantitative real-time RT-PCR verified that five genes in the leukocyte transendothelial migration pathway were significantly up-regulated, and four genes in the cell communication pathway were significantly down-regulated, which was consistent with pathway analysis.

CONCLUSION

We identified up-regulated genes (ITGB-2, MMP-2, CXCL-12, CXCR-4 and Rac-2) and down-regulated genes (connexin, DSG-1, DSC-1 and nestin) in periodontitis-affected gingival tissues; these genes may be related to the stimulation of leukocyte transendothelial migration and to the the impairment of cell-to-cell communication in periodontitis.

Microarray and quantitative RT-PCR analyses in calcium-channel blockers induced gingival overgrowth tissues of periodontitis patients

OBJECTIVES

The purpose of the present study was to analyse transcriptomes and mRNA expression levels for specific genes in calcium-channel blocker-induced gingival overgrowth (GO) tissues.

DESIGN

Eight gingival tissues samples (from both GO negative and positive sites) were harvested from four GO patients for microarray analyses. Twelve candidate genes were selected for further quantitative real time reverse transcription-polymerase chain reaction (qRT-PCR) analyses. Ten GO tissues from periodontitis patients and ten control gingival tissues from healthy subjects were compared by qRT-PCR. Mann-Whitney U-test was used for statistical evaluation.

RESULTS

In GO positive tissues, 163-1631 up-regulated and 100-695 down-regulated genes were identified with more than two-fold changes compared with GO negative tissues amongst patients by microarray experiments. No commonly expressed genes amongst the eight sets of microarray data were found. The clustering analysis confirmed that the entire transcriptome patterns showed similarities in individuals, but differences amongst the four patients. The qRT-PCR and statistical analyses for the candidate genes, though, revealed differential gene expressions between GO-positive and negative tissues. We found that matrix metalloproteinase (MMP)-1 and MMP-12 as well as cathepsin-L were significantly up-regulated whilst keratin-10 and transforming growth factor-β1 were significantly down-regulated in GO tissues of periodontitis patients compared with the control gingival tissues of healthy subjects.

CONCLUSION

The microarray analyses revealed that GO pathogenesis was complex and individually varied, though GO-affected gingival tissues were controlled at least by genes related to collagen metabolisms including regulated MMPs, cathepsin-L, growth factors, and keratins to maintain tissue homeostasis in vivo.

The relationship between the cusp pattern and plural stem cell compartments in Guinea pig cheek teeth by chasing BrdU-labeling

Continuously growing rodent incisors have a special epithelial structure for maintaining adult stem cells that shows a bulbous epithelial protrusion at the apical end and is referred to as an "apical bud". Guinea pig cheek teeth (premolars and molars), also continuously growing teeth, have a complex crown shape consisting of plural cusps. The present study clarifies the existence of apical buds in guinea pig premolars/molars as it examines the relationship between the crown shape and the orientation of the apical buds by micro-computed tomography (micro-CT) and immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU). One premolar and three molar teeth in each side of the maxillae and mandibles assumed characteristic features: each horizontally-sectioned tooth showing a complex zigzag shape was composed of a core of dentin covered by a layer of enamel on all axial surfaces except the buccal of the uppers and the lingual of the lowers. Furthermore, four bulbous epithelial protrusions--including the stellate reticulum--were recognized in the apical end of each tooth, where slow-cycling long-term label-retaining cells resided 20 days after a peritoneal injection of BrdU. These data indicate that guinea pig premolars/molars have four apical buds where the epithelial adult stem cells reside. In contrast, rodent incisors, which show a single cone appearance, are covered by enamel on the labial side and possess only one apical bud. The results of this study suggest that plural apical buds, being arranged bucco-lingually and mesio-distally, produce the crown mold in a zigzag fashion.

Differential gene and protein expression of tissue inhibitors of metalloproteinases (TIMP)-3 and TIMP-4 in gingival tissues from drug induced gingival overgrowth

OBJECTIVES

The purpose of this study was to analyse mRNA expression and protein localization of tissue inhibitors of metalloproteinases (TIMP)-3 and TIMP-4 in gingival tissues removed from drug (calcium-channel blocker) induced gingival overgrowth and periodontitis patients.

DESIGN

Employing RT-PCR, we evaluated TIMP-3 and TIMP-4 mRNA levels of 20 human gingival tissue samples taken from patients suffering gingival overgrowth (GO) and periodontitis (P). Then, using immunohistochemistry we investigated the TIMP-3 and TIMP-4 protein localization of five sample tissues from each group.

RESULTS

TIMP-4 mRNA levels in GO-gingiva tended to be lower than in P-gingiva but the results differed little (p = 0.22). Varying degrees of inflammation in the protein localization of TIMP-3 and TIMP-4 were found. TIMP-4 immunoreactivity (IR) was weak in the endothelial cells, fibroblasts, epithelial basal and parabasal cells while the degree of inflammation differed as well. TIMP-3 and TIMP-4 IR in inflammatory cells, including lymphocytes, plasma cells, and macrophages, were faint and intense respectively. For P-gingiva, both TIMP-3 and TIMP-4 IR expression was weak in the endothelial cells, fibroblasts, basal and parabasal epithelial layers. Expression of TIMP-3 was faint in the inflammatory cells, whereas TIMP-4 IR was strong.

CONCLUSION

Our findings suggest that TIMP-3 and TIMP-4 expression differs in GO and P-gingival tissues, both of which are potentially involved in pathogenesis.

The relationship between the termination of cell proliferation and expression of heat-shock protein-25 in the rat developing tooth germ

Odontoblast- and ameloblast-lineage cells acquire heat-shock protein (HSP)-25 immunoreactivity after they complete cell division during postnatal odontogenesis in rat molars. However, there are no data available concerning the relationship between the termination of cell proliferation and HSP-25 immunoreactivity during tooth morphogenesis. We compared the expression of HSP-25 in tooth germs with their proliferative activity in the rat prenatal to perinatal molar and postnatal incisor to clarify the functional significance of HSP-25 during tooth morphogenesis by immunohistochemistry using anti-HSP-25 and anti-Ki67/5-bromo-2'-deoxyuridine (BrdU). Numerous proliferating cells in developing molars were distributed throughout the tooth germ and HSP-25 immunoreactivity was recognizable in the dental epithelial and mesenchymal cells after they completed cell division. However, both cell proliferation and immunoreaction for HSP-25 are absent in the enamel knots. The distribution pattern of the proliferating cells in the incisors was basically identical to that in the prenatal molars except for the lack of non-proliferating secondary enamel knots and the sparse distribution of proliferating cells in the apical bud. Thus, HSP-25 protein is suggested to act as a switch between cell proliferation and terminal cyto-differentiation during odontogenesis.

An immunohistochemical study of the expression of heat-shock protein-25 and cell proliferation in the dental pulp and enamel organ during odontogenesis in rat molars

OBJECTIVES

The aim of this study is to clarify the functional significance of heat-shock protein (HSP)-25 during tooth development.

DESIGN

We compared the expression of HSP-25 in the dental epithelial and mesenchymal cells with their proliferative activity during odontogenesis in rat molars on postnatal days 1-100 by immunohistochemistry using anti-HSP-25 and anti-5-bromo-2'-deoxyuridine (BrdU) for cell proliferation assay.

RESULTS

On day 1, BrdU-immunoreactive cells were densely located in the inner enamel epithelium in the cervical loop and intercusped areas and the dental pulp adjacent to them, whereas HSP-25-immunoractivity (IR) was restricted to the cusped area where odontoblasts and ameloblasts had already differentiated. Subsequently, BrdU-IR shifted in the apical direction to be localized around Hertwig's epithelial root sheath during days 5-30, never overlapping with concomitantly apically-shifted HSP-25-IR. On days 60-100, BrdU-immunoreactive cells were hardly recognizable in the dental pulp, where HSP-25-IR was exclusively localized in the odontoblast layer. Furthermore, the odontoblast- and ameloblast-lineage cells exhibited two steps in the expression of HSP-25 throughout the postnatal stages: first, dental epithelial and pulpal mesenchymal cells showed a weak IR for HSP-25 after the cessation of their proliferative activity, and subsequently odontoblasts and ameloblasts consistently expressed an intense HSP-25-IR.

CONCLUSION

Odontoblast- and ameloblast-lineage cells acquire HSP-25-IR after they complete their cell division, suggesting that this protein acts as a switch between cell proliferation and differentiation during tooth development. The consistent expression of HSP-25-IR in the formative cells may be involved in the maintenance of their functional integrity.

The eternal tooth germ is formed at the apical end of continuously growing teeth

Rodent incisors are known to be continuously growing teeth that are maintained by both the cell-proliferation at the apical end and the attrition of the incisal edge. This type of tooth had a special epithelial structure for the maintenance of stem cells, showing the bulbous epithelial protrusion at the apical end. The morphological transition of the epithelial-mesenchymal compartment by serial transverse sections of the apical end toward the incisal direction is likely to reflect the development of the tooth germ in the prenatal stage. Based on the present histological and previous molecular biological studies, the special structure at the apical end is obviously different from the cervical loop giving rise to Hertwig's epithelial root sheath (HERS), in human, mouse and rat molar tooth germs. Hence, we propose a new concept that the eternal tooth bud producing various dental progeny is formed at the apical end of continuously growing teeth, and a new term "apical bud" for indicating this specialized epithelial structure. Furthermore, BrdU labelling analysis suggested that the guinea-pig molars, which were continuously growing teeth, also possessed plural specific proliferative regions and "apical bud" at the apical end.

Gene analysis of Vibrio cholerae NAGV14 pilus and its distribution

Adhesive pilus of Vibrio cholerae 034, strain NAGV14, was genetically analyzed. The deduced amino acid (aa) sequence of the major pilin structural gene (VcfA) was 67% homologous to the MshA pilin in the N-terminal region, but no homology was found in the C-terminal region which contained the antigenic epitopes. Upstream and downstream flanking regions examined were highly homologous to mshB and mshC of the MSHA (mannose-sensitive hemagglutinin) gene locus. A short leader sequence and a pair of cysteines near the C-terminus which are the characteristics of type 4a pilus family were found. The major pilin structural gene of NAGV14 was compared to that of a strain V10 producing non-adhesive pili. The deduced aa sequences showed 60% homology, and the distance between two cysteines in the C-terminal region was different. A total of 177 V. cholerae strains were investigated for the presence of a type 4 pilus gene locus by PCR, and 95% were positive. The major pilin gene of NAGV14 was detected in 4 of 93 V. cholerae non-O1, non-0139 strains tested, but none of the V. cholerae O1 and O139 (72 and 12 strains, respectively). Our result suggested that a type 4 pilus gene locus similar to the MSHA gene locus is widely distributed among V. cholerae strains. We proposed naming this type 4 pilus gene locus the VCF (for V. cholerae flexible pili) gene locus.

[Pathogenic bacteria in the nasal vestivulum of children with acute respiratory tract infection]

The isolation frequency of pathogenic bacteria for acute respiratory infection (ARI) in the pharynx and nasal vestivulum was investigated. Age group-matched children with or without ARI including 109 individuals in each group were examined. Any of the organisms, which are widely regarded as the pathogens causing ARI such as Haemophilus influenzae, Streptococcus pneumoniae, beta-haemolytic Streptococcus, Staphylococcus aureus, and Moraxella catarrhalis, were isolated from 91% of the patient group and from 77% of the healthy group. The isolation frequency of S. pneumoniae in the nasal vestivulum of the patient group was outstanding. The healthy carrier rates of S. pneumoniae in the pharynx and nasal vestivulum were 9% and 8%, respectively. Whereas the isolation frequencies from the patient group were 7% and 28%, respectively. alpha-haemolytic Streptococci except S. pneumoniae revealed different tendency from S. pneumoniae. These organisms were almost always isolated from their pharynx but rarely isolated from the nasal vestivulum. The isolation frequency of H. influenzae from the pharynx of the patient group was 41%, which was slightly higher than 34% in the healthy group, but the difference was statistically not significant. H. influenzae was not isolated from the nasal vestivulum of the healthy group, nevertheless it was isolated from 25% of the patient group. The isolation of H. influenzae from the nasal vestivulum may have some important information about ARI. S. aureus was isolated from the pharynx with higher rate than the nasal vestivulum in both groups, and moreover, the isolation frequency of S. aureus in the healthy group was higher than the patient group. It means that the diagnosis of staphylococcal infection should be made very carefully. Considering the results of this study, it could be said that bacteriologic examination of the specimens from nasal vestivulum is valuable to determine S. pneumoniae and H. influenzae as the etiologic agents of ARI.

Characterization of the pili isolated from Vibrio parahaemolyticus O3:K6

Pilus of Vibrio parahaemolyticus O3:K6 strain LVP9 belonging to the newly identified clone was purified and characterized. The molecular mass of the pilin was estimated to be about 18 kDa by SDS-PAGE, and the isoelectric point of the pilin was 5.0 +/- 0.2. The LVP9 pili were antigenically different from the other V. parahaemolyticus Na2 pili and Ha7 pili as previously reported, nevertheless all three had indistinguishable morphology and shared a high degree of homology in their N-terminal amino acid sequences. Strain LVP9 and its purified pili did not agglutinate human and rabbit erythrocytes. The LVP9 organisms and the purified pili were adhesive to the rabbit intestine. The adhesion was inhibited by pretreatment of the rabbit intestine with the purified pili or by pretreatment of the organisms with the Fab fractions of anti-pilus antibody. These results indicate that the LVP9 pilus is an adherent factor to the rabbit intestine.

Detection of Clostridium difficile toxin A by reversed passive latex agglutination

A reversed passive latex agglutination (RPLA) assay for detecting Clostridium difficile toxin A is presented. Purified monoclonal antibody (mAb 37B5) was used for latex sensitization. The culture supernatants of 93 strains of C. difficile were tested by RPLA assay and the results compared with those of a commercially available latex agglutination test, PCR and cytotoxin assay with Vero cells. There was agreement between RPLA, cytotoxicity and PCR assays, but 29 strains were positive in the RPLA assay while 35 were positive in the cytotoxicity test and PCR using primer pair NK3-NK2 directed to the nonrepeating portion of the C. difficile toxin A gene. The 6 cytotoxic but RPLA-negative strains were demonstrated to be toxin A-negative/toxin B-positive strains in the PCR assay by using primer pair NK11-NK9 directed to the repeating portion of the C. difficile toxin A gene. There were no cross-reactions with culture supernatants of the other clostridial strains except for two strains of C. sordelli that produced hemorrhagic toxin (which is immunologically related to C. difficile toxin A).

Expression of type I pili is abolished in verotoxin-producing Escherichia coli O157

Verotoxin-producing Escherichia coli (VTEC) were examined for production of type I pili. None of 34 strains of VTEC serogroup O157 examined expressed any pili, whereas 26 strains of 27 VTEC serogroup O26 and seven strains of nine non-VTEC O157 produced type I pili. These VTEC strains were collected from sporadic human cases and cattle in Okinawa in 1997. The genes encoding the major structural component (FimA) and the adhesin (FimH) of type I pili were detected in all 70 strains examined. The inability to express type I pili could be a unique character of VTEC O157 and this trait could be a new candidate to identify the organisms.

A filamentous phage of Vibrio parahaemolyticus O3:K6 isolated in Laos

A filamentous phage, 'lvpf5,' of Vibrio parahaemolyticus O3:K6 strain LVP5 was isolated and characterized. The host range was not restricted to serotype O3:K6, but 7 of 99 V. parahaemolyticus strains with a variety of serotypes were susceptible to the phage. The phage was inactivated by heating at 80 C for 10 min and by treating with chloroform. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the phage exhibited a 3.8 kDa protein. The amino-terminal amino acid sequence of the coat protein was determined as AEGGAADPFEAIDLLGVATL. The phage genome consisted of a single-stranded DNA molecule. The activity of the phages was inhibited by anti-Na2 pili antibody.

Characterization of outer membrane protein OmpU of Vibrio cholerae O1

The outer membrane protein OmpU of Vibrio cholerae O1 strain 86B3 was characterized with reference to colonization of the intestine by the organism. The purified OmpU exhibited a pI of 3.6. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, it migrated to 38, 32, and 110 kDa when the sample was heated at 100 degrees C for 2 min, 50 degrees C for 15 min, and room temperature for 30 min, respectively. The purified OmpU was not hemagglutinative. Anti-OmpU serum did not agglutinate strain 86B3 or other V. cholerae organisms. OmpU adhered to the brush border of the rabbit small intestine; adhesion of the organisms to the intestine treated in advance with OmpU was not inhibited. Treating the organisms in advance with anti-OmpU Fab did not inhibit adhesion to the intestine. These results obtained in vitro suggest that OmpU is not involved in the adhesion of V. cholerae to the intestinal epithelium.

Etiological study of diarrheal patients in Vientiane, Lao People's Democratic Republic

The etiological agents of diarrhea in Vientiane, Lao People's Democratic Republic (Lao PDR), were studied in the period from October 1996 to August 1997. A total of 880 patients with diarrhea visiting medical facilities were examined for Shigella, Salmonella, diarrheagenic Escherichia coli, vibrio, Aeromonas, Campylobacter, and rotavirus. Shigella spp., heat-stable enterotoxin (ST)-producing E. coli, and serogroup-based enteropathogenic E. coli were found to be the main organisms causing diarrhea in Vientiane, with frequencies of 16.8% (148 of 880), 17.2% (111 of 645), and 11.0% (97 of 880), respectively. Relatively low incidences were observed in the cases of Salmonella spp., (0.6%; 5 of 880), Campylobacter spp. (4.4%; 39 of 880), and rotavirus (6.1%; 9 of 148), and no isolates of V. cholerae O1 or O139 or Aeromonas were recovered. An analysis of the incidences of enteropathogens with respect to age and seasonal variations demonstrated that the frequencies of isolation of Shigella spp. and heat-labile enterotoxin-producing E. coli were significantly higher in those aged 1 to 5 years than in those younger than 1 year of age and those older than 5 years of age (P < 0.0001 and P < 0.05, respectively) and that the frequencies of isolation of Shigella spp. and ST-producing E. coli were significantly higher in the rainy season than in the dry season (P < 0.005 and P < 0.001, respectively). Almost all strains of Shigella spp. tested were resistant to ampicillin, tetracycline, and erythromycin and were susceptible to cefdinir and ofloxacin. This is the first intensive and longitudinal study to define the etiologic agents of diarrheal diseases in Lao PDR.

Filamentous phage fs1 of Vibrio cholerae O139

Filamentous phage, fs1, was obtained from Vibrio cholerae O139. The lysogenized strains produced a large amount of fs1 phage in the culture supernatant. This phage was previously reported as novel fimbriae of that organism. The genome of the phage was a 6.5 kb single-stranded DNA. The capsid of fsl consists of a small molecule peptide (about 2.5 kDa).

Adhesive property of toxin-coregulated pilus of Vibrio cholerae O1

The adhesive property of toxin-coregulated pilus (TCP) to the human intestine jejunum), and whether or not TCP mediates the adhesion of Vibrio cholerae 395 organisms to the intestinal epithelium were investigated using visually proving methods. The purified TCP did not agglutinate human erythrocytes nor adhere to the surface of human intestinal epithelium. V. cholerae 395 adhered to the epithelium, but the adhesion was not inhibited by blocking the pili with the Fab fraction of anti-TCP IgG. The organisms adhered to the intestine treated with purified TCP in advance, as well as to the intact intestine. These findings suggest that TCP is not involved in the adhesion of these organisms to the intestinal epithelium.

Characterization of an enterotoxin produced by Vibrio cholerae O139

A cholera-like enterotoxin was purified from Vibrio cholerae O139 strain AI-1841 isolated from a diarrheal patient in Bangladesh. Its characteristics were compared with that of cholera toxins (CTs) of classical strain 569B and El Tor strain KT25. Al-1841 produced as much toxin as O1 strains. The toxins were indistinguishable in terms of their migration profiles in conventional polyacrylamide gel disc electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectrofocusing as well as their affinity for hydroxyapatite. The skin permeability factor activity and the fluid accumulation induced in rabbit ileal loops of the toxin of AI-1841 were identical to those of the CTs. Three toxins equally reacted against anti-569B CT antiserum in Western blotting, and their B subunits formed a precipitin line against any anti-B subunit antiserum by double gel immunodiffusion. Anti-569B CTB antibody neutralized the three toxins in their PF activities and enterotoxicities. The amino acid sequence of 1841 toxin B subunit was identical with that of KT25 CTB, corresponding to the DNA sequence of ctxB from El Tor strains of the seventh pandemic. We concluded 1841 toxin was identical to CT of the seventh pandemic El Tor vibrios.

Pili of a Vibrio cholerae O139

The pili of a strain of Vibrio cholerae O139 were purified and characterized. They were morphologically, electrophoretically and immunologically indistinguishable from the pili with 16 kDa subunit protein of V. cholerae O1. All 22 strains of V. cholerae O139 examined possessed the pili. The pili were different in hemagglutination inhibition pattern from V. cholerae O1 16K pili.

Purification and characterization of vibrio cholerae O139 fimbriae

A Vibrio cholerae O139 (strain Al-1841) isolated from a patient with a cholera-like disease in Bangladesh predominantly produced new curved, wavy fimbriae (Al-1841 fimbriae) and small numbers of previously reported V. cholerae non-O1 S7-like pili. The former was purified and characterized. The molecular mass of the Al-1841 fimbrial subunit was less than 2.5 kDa, and it was immunologically different from that of V. cholerae non-O1 S7 pili. This novel fimbrial antigen was detected in all 182 Gram-negative strains from five genera tested but was absent from the Gram-positive bacteria tested. The purified Al-1841 fimbriae did not agglutinate human or rabbit erythrocytes.

Purification and characterization of pili of a Vibrio cholerae non-O1 strain

Pili of the Vibrio cholerae non-O1 strain V10 were purified and characterized. The V10 pili were physicochemically and immunologically different from those of the previously reported V. cholerae non-O1 strain S7, although the pili of the two strains had homologous N-terminal amino acid sequences. V10 plus antigen was detected only in V. cholerae non-O1 strains.

Cell-associated hemagglutinin of classical vibrio cholerae O1 with reference to intestinal adhesion

Vibrio cholerae O1 86B3 biovar cholerae has at least two types of cell-associated hemagglutinin. One is cell wall-associated and L-fucose sensitive, whereas the other is pili-associated and D-mannose sensitive. A pilus rich variant of 86B3 and a poorly piliated parent strain adhered equally to the rabbit intestine. This adhesion was inhibited by L-fucose but not by D-mannose. A Fab fraction prepared from anti-pilus antibody did not inhibit the adhesion. These results suggest that not the pili but a colonization factor located in the outer membrane of the organisms plays a role in intestinal adhesion.

Pili of vibrio cholerae widely distributed in serogroup O1 strains

The distribution of Vibrio cholerae O1 pili consisting of 16 kDa subunit protein (16K-pili) was examined by Western blotting, using 211 strains from various origins and specific anti-16K-pili sera. The 16 kDa protein was detected in all 211 strains. The pili were purified from 3 El Tor and 3 classical strains, and characterized by hemagglutination and inhibition tests. All purified pili were hemagglutinative. However, the hemagglutinating activity of classical pili disappeared after exposure to 5 M urea and the agglutination induced by the classical pili was inhibited by D-mannose, alpha-methylmannoside, D-glucose and N-acetylglucosamine. On the contrary, El Tor pili were resistant to these sugars and urea.

The role of pili in colonization of the rabbit intestine by Vibrio parahaemolyticus Na2

Vibrio parahaemolyticus Na2 and its pili were studied in relation to intestinal colonization. The isolated pili were adhesive to the intestinal epithelium. The adhesion of the organisms was blocked by masking the epithelial receptor with the purified pili, or by treating the organisms with anti-pilus antibody (Fab fraction). These results suggest that the pili of V. parahaemolyticus Na2 play an important role in the adhesion of the organisms to the rabbit intestine.

Purification and characterization of pili isolated from Vibrio parahaemolyticus Na2

Pili from Vibrio parahaemolyticus Na2 isolated from a patient with diarrhea were purified and characterized. The organisms were hemagglutinative, but the purified pili were not. Na2 pili were physicochemically and immunologically quite different from the previously described V. parahaemolyticus Ha7 pili. Nevertheless, there was a high degree of homology between their N-terminal amino acid sequences.

Pili of an Aeromonas hydrophila strain as a possible colonization factor

Aeromonas hydrophila Ae6 had 2 morphologically distinctive kinds of pili. One appeared rigid and straight with a diameter of 9 nm (R-pili). The other appeared wavy and flexible with a diameter of 7 nm (W-pili). W-pili were very few on the cell as compared with R-pili. In this study, W-pili were purified and characterized. The pili consisted of a subunit protein with a molecular weight of 21 kDa as estimated by SDS-PAGE. There was no immunological cross-reaction between W-pili and other cellular components. The strain Ae6 and its purified W-pili adhered to human and rabbit intestine and agglutinated human and rabbit erythrocytes. Organisms pretreated with the Fab fraction of anti-pilus antibody failed to adhere to the intestine. Pretreatment of intestine with purified W-pili blocked adherence of the organisms to the intestine. These results suggest that the W-pili are the colonization factor of A. hydrophila Ae6.

Pili of Vibrio cholerae non-O1

Pili of Vibrio cholerae non-O1 strain S7 were purified and characterized. The pili of S7 were morphologically, electrophoretically, and immunologically (as far as polyclonal antibody was used) indistinguishable from the 16-kilodalton pili of V. cholerae O1 strain 82P7. The purified pili and organisms had D-mannose- and L-fucose-resistant hemagglutinin. The hemagglutinating activity of the purified pili was inhibited by the Fab fraction of antipilus antibody, but the hemagglutinating activity of live organisms was not inhibited completely. The purified pili or Fab fraction of antipilus antibody did not inhibit the adhesion of V. cholerae non-O1 to rabbit intestines. Therefore, the pili were not regarded as a colonization factor of V. cholerae non-O1. A total of 148 V. cholerae non-O1 and O1 clinical isolates were screened for the presence of S7 pili by using an agglutination test with anti-S7 pilus serum; 12 of 49 V. cholerae non-O1 strains and 25 of 99 V. cholerae O1 strains were positive for agglutination. These agglutination reactions were not correlated with adhesion of the organisms to intestines.

Pili of Aeromonas hydrophila: purification, characterization, and biological role

Aeromonas hydrophila (Ae6) has 2 morphologically distinctive kinds of pili. One appeared rigid, channeled, and straight with a diameter of 9 nm (Ae6-R pili). The other looked flexible, wavy, and having helical structure with a diameter of 7 nm (Ae6-W pili). Ae6-R pili were purified and characterized. The pili consisted of a subunit protein with a molecular weight of 18 kDa as estimated by SDS-PAGE, and contained 42.3% hydrophobic amino acids and one cysteine residue. The pilus was solubilized to 18 kDa subunit protein by 2-mercaptoethanol, dithiothreitol, hydrochloric acid, or heating at 120 C for 5 min. The organism Ae6 was strongly adhesive to rabbit intestines as well as human intestines, and agglutinated erythrocytes. Anti-pili antibody (Fab fraction) did not block the adhesion. Purified Ae6-R pili did not adhere to the intestine or to the erythrocytes. However, the anti-pili Fab inhibited pellicle formation of the organisms cultured in broth, and also inhibited salt agglutination with ammonium sulfate. From these results, Ae6-R pili are not likely a colonization factor but probably play a role in the autoaggregation of the organisms.

Pili of a Vibrio parahaemolyticus strain as a possible colonization factor

Pili of Vibrio parahaemolyticus were purified from a Kanagawa phenomenon-positive strain (Ha7) that belongs to serogroup O2:K3 and is adhesive to rabbit intestine. The organisms treated with the Fab fraction of antipilus antibody failed to adhere to the intestine. Purified pili had the ability to adhere to the intestine, but the pretreatment of the intestine with purified pili did not allow adherence of the organisms to the intestine. These results suggest that pili of this V. parahaemolyticus strain play an important role in colonization.

Pili of Vibrio cholerae O1 biotype E1 Tor: a comparative study on adhesive and non-adhesive strains

Pili were found on the cell surface of non-adhesive Vibrio cholerae O1 Biotype E1 Tor as well as the adhesive strain. Purified pili of the adhesive and non-adhesive strains were morphologically, electrophoretically, and immunologically, indistinguishable from each other. The molecular weights of both pilin (subunit protein of the pilus) were about 16,000 daltons as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These 16 kDa pili are different from the pilus colonization factor, which is a 20.5 kDa protein, reported by Taylor et al. The 16 kDa pili of Vibrio cholerae O1 Biotype E1 Tor have hemagglutinating activity, but may have no role in colonization, because non-adhesive strains also have such pili.

Characterization of Vibrio cholerae 01 recently isolated in Bangladesh

91 strains of Vibrio cholerae O1, isolated in Bangladesh in January 1986, were examined for their biological behaviour and sensitivity to 6 antimicrobial agents. Biotyping indicated that 60 of the isolates belonged to the classical biotype and 31 to the El Tor biotype. 21 El Tor strains revealed beta-haemolysis on blood agar plates, but only 8 showed complete haemolysis in broth. Serotyping indicated 79 Ogawa, 10 Inaba, and 2 Hikojima. Phage typing showed that all classical vibrios belonged to Mukerjee's phage type 1. El Tor vibrios were classified into 4 groups: one strain each in type 1 and type 5, 19 in type 4, and 10 in an untypable group. Prophage typing of El Tor vibrios identified 14 strains of Ubol type, 16 of cured Celebes type, and one of original Celebes type. No strain was resistant to tetracycline, minocycline, chloramphenicol, streptomycin, amoxicillin or nalidixic acid. The classical vibrios differed from those isolated before 1973 in toxin production pattern.

Quantitative evaluation of colonizing ability of Vibrio cholerae O1

A new method to evaluate the adhesive ability of Vibrio cholerae O1 was proposed. Broth cultured V. cholerae O1 and a piece of formalin-fixed rabbit intestinal wall were incubated together in KRT buffer and the number of adhered organisms was counted under a scanning electron microscope. This method was much less laborious than other methods that have been used so far, and most significantly, constant results were obtained in repeated experiments. The adhesive properties of toxigenic V. cholerae O1 evaluated by this method correlated well with its observed experimental pathogenicity.

Characterization of mesosomes of Micrococcus luteus: isolation and properties of mesosomal ribosomes, and localization of penicillin-binding proteins in mesosomal membranes

Mesosomes were isolated and purified from Micrococcus luteus under hypertonic conditions throughout preparation processes. The purified mesosomal preparation was composed of closed tubules and vesicles. Electron-dense ribosome-like particles were observed within the isolated mesosomal vesicles by electron microscopy. The ribosome-like particles were isolated from the purified mesosomes by a procedure involving solubilization of the membranes with detergents followed by centrifugation on a linear density gradient of sucrose. The isolated particles have a sedimentation coefficient of 70S in the presence of 10 mM Mg2+, when Mg2+ concentration was lowered to 0.1 mM, the particles were dissociated into two sub-particles of 30S and 50S. The 70S particles had the same appearance as cytoplasmic 70S ribosome particles upon observations of negatively stained preparations. These findings indicate that mesosomal tubules contain ribosomes. The isolated mesosomal ribosomes had the ability for protein synthesis when polyuridylic acid-directed polyphenylalanine synthesis was assayed. The sensitivity of mesosomal ribosomes to inhibitors, chloramphenicol and streptomycin, for protein synthesis was significantly lower than that of both cytoplasmic and cytoplasmic membrane-bound ribosomes. In addition, three penicillin-binding proteins were detected in the mesosomal membranes. One of these was localized predominantly in the mesosomal membranes and the other two were distributed almost equally in both mesosomal and cytoplasmic membranes.

Enterotoxicity of El Tor-like hemolysin of non-O1 Vibrio cholerae

The enterotoxicity of an El Tor-like hemolysin purified from non-O1 Vibrio cholerae was investigated. Fluid accumulation was induced by injection of purified hemolysin into the ligated intestinal loops in adult rabbits (De test), intraintestinal administration in infant rabbits (Dutta test), and oral inoculation in suckling mice. The accumulated fluid was invariably mucous and bloody, and a histological change in the mucosa was observed. These results suggest that the hemolysin is an enterotoxic factor that is responsible for non-O1 V. cholerae gastroenteritis.

Electron microscopic demonstration and isolation of ribosomes in mesosomes from Staphylococcus aureus

Mesosomes of Staphylococcus aureus 209P were observed to be extruded as tubules upon protoplast formation by electron microscopy and isolated under hypertonic conditions to maintain their structural integrity by differential centrifugation followed by sucrose density gradient centrifugation. Isolated mesosomes were composed of long, branched tubules of irregular sizes and they were shortened during purification. Thin sections of isolated mesosomes showed that the mesosomal tubule was surrounded by a triple-layered membrane and contained ribosome-like particles in diameter of about 15 to 20 nm. These particles were isolated from purified mesosomal preparation by disrupting the mesosomal tubule with deoxycholate and Triton X-100 under hypotonic conditions followed by a linear sucrose density gradient centrifugation. Negatively stained preparations of the isolated particles revealed the same appearance as those of the ribosomes isolated from the cytoplasm. The mesosomal particles sedimented at 70S in sucrose gradients in the presence of 10 mM Mg2+, but they were dissociated into two subparticles, 50S and 30S subunits, upon lowering the Mg2+ concentration to 1 mM. These findings indicate that the mesosomal tubule is packed with ribosomes.

Culture conditions for stimulating cholera toxin production by Vibrio cholerae O1 El Tor

A method that stimulates cholera toxin (CT) production by Vibrio cholerae O1 biotype El Tor (El Tor vibrios) to the level of several micrograms per ml in the culture fluid was established. Such a large amount of CT was obtained by the following method: El Tor vibrios were cultured in AKI medium (1.5% Bacto peptone, 0.4% yeast extract-Difco, 0.5% NaCl, 0.3% NaHCO3) at 37 C for 4 hr in a stationary test tube and then for 16 hr in a shaken flask, with inoculum sizes of 10(5) to 10(7)/ml. With this method, 35 strains out of 60 examined produced 2 to 16 micrograms/ml of CT as determined by the reversed passive latex agglutination test (RPLA). Thirty-three randomly selected strains out of the 60 produced reasonable amounts of rabbit skin vascular permeability factor, reflecting the amount of CT titrated with RPLA.

Identity of hemolysins produced by Vibrio cholerae non-O1 and V. cholerae O1, biotype El Tor

Hemolysins purified from non-O1 Vibrio cholerae (non-O1 hemolysin) and a Vibrio cholerae O1, biotype El Tor (El Tor hemolysin) were investigated for their homology. The hemolysins were isolated from the culture supernatant fluids by ammonium sulfate precipitation and gel filtration on Sephadex G-100 columns. The purified hemolysins gave single bands with an identical mobility on conventional polyacrylamide gel disc electrophoresis. The molecular weights of the non-O1 and El Tor hemolysins were estimated to be about 60,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the amino acid compositions of the hemolysins were very similar. The specific activities of the hemolysins were identical, and both hemolysins were neutralized to the same extent with antisera against the homologous and heterologous hemolysins. Ouchterlony double immunodiffusion tests with both hemolysins and antihemolysin serum gave a common (fused) precipitin line. These data indicate that the non-O1 hemolysin is biologically, physicochemically, and immunologically indistinguishable from the El Tor hemolysin.