Dual functions of discoidinolysin, a cholesterol-dependent cytolysin with N-terminal discoidin domain produced from Streptococcus mitis strain Nm-76

Background

Some strains of Streptococcus mitis exhibit β-hemolysis due to the β-hemolytic activity of cholesterol-dependent cytolysin (CDC). Recently, a gene encoding an atypical lectinolysin-related CDC was found in S. mitis strain Nm-76. However, the product of this gene remains uncharacterized. We aimed to characterize this atypical CDC and its molecular functions and contribution to the pathogenicity of S. mitis strain Nm-76.

Methods

Phylogenetic analysis of the CDC gene was conducted based on the web-deposited information. The molecular characteristics of CDC were investigated using a gene-deletion mutant strain and recombinant proteins expressed in Escherichia coli.

Results

The gene encoding CDC found in Nm-76 and its homolog are distributed among many S. mitis strains. This CDC is phylogenetically different from other previously characterized CDCs, such as S. mitis-derived human platelet aggregation factor (Sm-hPAF)/lectinolysin and mitilysin. Because this CDC possesses an additional N-terminal domain, including a discoidin motif, it was termed discoidinolysin (DLY). In addition to the preferential lysis of human cells, DLY displayed N-terminal domain-dependent facilitation of human erythrocyte aggregation and intercellular associations between human cells.

Conclusion

DLY functions as a hemolysin/cytolysin and erythrocyte aggregation/intercellular association molecule. This dual-function DLY could be an additional virulence factor in S. mitis.

Molecular characteristics of an adhesion molecule containing cholesterol-dependent cytolysin-motif produced by mitis group streptococci

Streptococcus pseudopneumoniae (SPpn) is a relatively new species closely related to S. pneumoniae (SPn) and S. mitis (SM) belonging to the Mitis group of the genus Streptococcus (MGS). Although genes encoding various pneumococcal virulence factors have been observed in the SPpn genome, the pathogenicity of SPpn against human, including the roles of virulence factor candidates, is still unclear. The present study focused on and characterized a candidate virulence factor previously reported in SPpn with deduced multiple functional domains, such as lipase domain, two lectin domains, and cholesterol-dependent cytolysin-related domain using various recombinant proteins. The gene was found not only in SPpn but also in the strains of SM and SPn. Moreover, the gene product was expressed in the gene-positive strains as secreted and cell-bound forms. The recombinant of gene product showed lipase activity and human cell-binding activity depending on the function of lectin domain(s), but no hemolytic activity. Thus, based on the distribution of the gene within the MGS and its molecular function, the gene product was named mitilectin (MLC) and its contribution to the potential pathogenicity of the MLC-producing strains was investigated. Consequently, the treatment with anti-MLC antibody and the mlc gene-knockout significantly reduced the human cell-binding activity of MLC-producing strains. Therefore, the multifunctional MLC was suggested to be important as an adhesion molecule in considering the potential pathogenicity of the MLC-producing strains belonging to MGS, such as SPpn and SM.

The diversity of receptor recognition in cholesterol-dependent cytolysins

Cholesterol-dependent cytolysins (CDCs) are bacterial pore-forming toxins secreted mainly by pathogenic Gram-positive bacteria. CDCs generally recognize and bind to membrane cholesterol to create pores and lyse target cells. However, in contrast to typical CDCs such as streptolysin O, several atypical CDCs have been reported. The first of these was intermedilysin, which is secreted by Streptococcus intermedius and has human cell-specificity, human CD59 (huCD59) being its receptor. In the study reported here, the diversity of receptor recognition among CDCs was investigated and multi-receptor recognition characteristics were identified within this toxin family. Streptococcus mitis-derived human platelet aggregation factor (Sm-hPAF) secreted by S. mitis strain Nm-65 isolated from a patient with Kawasaki disease was previously shown to hemolyze erythrocytes in a species-dependent manner, its maximum activity being in human cells. In the present study, it was found that Sm-hPAF recognizes both membrane cholesterol and huCD59 as receptors for triggering pore-formation. Moreover, vaginolysin (VLY) of Gardnerella vaginalis showed similar characteristics to Sm-hPAF regarding receptor recognition. On the basis of the results presented here, the mode of receptor recognition of CDCs can be categorized into the following three groups: (i) Group I, comprising typical CDCs with high affinity to cholesterol and no or very little affinity to huCD59; (ii) Group II, including atypical CDCs such as ILY, with no or very little affinity to cholesterol and high affinity to huCD59; and (iii) Group III, which contains atypical CDCs such as Sm-hPAF and VLY with affinity to both cholesterol and huCD59.

Characterization of recombinant Streptococcus mitis-derived human platelet aggregation factor

We previously purified Streptococcus mitis-derived human platelet aggregation factor (Sm-hPAF) from the culture supernatant of S. mitis strain Nm-65, isolated from the tooth surface of a patient with Kawasaki disease. Here we produced recombinant Sm-hPAF protein (rSm-hPAF) in Escherichia coli, to determine whether rSm-hPAF conserves its platelet aggregation activity. rSm-hPAF precursor (665 amino acids) shows up to 36-56% identity with the family of cholesterol-dependent cytolysins (CDCs), and rSm-hPAF displayed potent hemolytic activity toward mammalian erythrocytes, including human erythrocytes with platelet aggregation activity. The 162-amino acid amino-terminal domain of rSm-hPAF was found in no other CDCs except lectinolysin; this domain is homologous to a portion of pneumococcal fucolectin-related protein. Interestingly, suilysin (SLY) and pneumolysin (PLY) of CDCs also exhibit substantial human platelet aggregation activity, similar to rSm-hPAF, and the platelet aggregation by rSm-hPAF, SLY, and PLY was morphologically confirmed using light and electron microscopy.

Use of a dual priming oligonucleotide system to detect multiple sexually transmitted pathogens in clinical specimens

AIMS

To evaluate a new dual priming oligonucleotide (DPO)-based multiplex polymerase chain reaction (PCR) assay for detection of six sexually transmitted pathogens, including Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum and Trichomonas vaginalis.

METHODS AND RESULTS

Using 130 clinical specimens, the results obtained by the multiplex PCR, previously established in-house PCR and COBAS Amplicor PCR assays were compared. The specimens frequently contained multiple pathogens (34/130 specimens). The multiplex PCR assay had an overall sensitivity of 96% and specificity of 100% compared to the in-house PCR assay at >20 microg ml(-1) of DNA concentrations in samples and there was no cross-reaction with nonpathogenic Neisseria species that cause the majority of false-positive results with the COBAS Amplicor PCR assay.

CONCLUSIONS

The DPO-based multiplex PCR assay detected the six sexually transmitted pathogens in clinical specimens with a high sensitivity and specificity, although its sensitivity was dependent on the DNA content of the samples.

SIGNIFICANCE AND IMPACT OF THE STUDY

It is the first report about the new DPO-based technique to detect multiple sexually transmitted pathogens in a single assay, which has considerable potential to diagnose the infections accurately and rapidly.

[Evaluation of the GonoGen II kit for rapid identification of Neisseria gonorrhoeae using monoclonal antibody directed at gonococcal outer membrane protein 1]

The Gonogen II test for rapid identification of Neisseria gonorrhoeae (Gonococcus, GC) was evaluated. The test is based on a colorimetric reaction with monoclonal antibody to GC outer membrane protein 1. Of the 50 clinical isolates of GC, 49 isolates tested positive and only one strain tested negative. Other Neisseria. spp, H. influenzae, H. parainfluenzae, E. corrodens, M. catarrhalis, and A. baumannii showed negative test results. Non-Neisseriae. spp, such as S. aureus. P. aeruginosa, E. faecalis, and E. coli also showed negative test results. No cross-reactivity was found between GC and other Neisseriae. spp or non-Neisseriae. spp. In a mixed suspension of GC and all of non-Neisseriae. spp as mentioned above, the GonoGen II test was positive. The specificity and sensitivity of the test for the identification of GC were 98% and 100%. The minimum limit of detection of GC was > or = 1 x 10(5) cfu/mL. Decision making based on the test result is possible within 10 minutes. These findings also suggest that the test does not require pure GC. The GonoGen II test appears to be a reliable, quick and easy-to-use assay, and also to not require viable GC. Thus GonoGen II is shown to be a very useful test for the identification of GC.

Studies of recombinant streptococcal pyrogenic exotoxin B/cysteine protease (rSPE B/SCP) in the skin of guinea pigs & the release of histamine from cultured mast cells & basophilic leukocytes

BACKGROUND & OBJECTIVES

Streptococcal pyrogenic exotoxin B/streptococcal cysteine protease (SPE B/SCP) is considered to be one of the virulence factors of Streptococcus pyogenes (S. pyogenes) which causes serious diseases such as severe invasive infections and streptococcal toxic shock syndrome (STSS). There are no reports on the histamine releasing activity of SPE B/SCP from mast cells, although several biological activities have been studied. It is not clear whether SPE B/SCP have the superantigenic activity. We studied whether SPE B/SCP plays as a pathogenic factor in streptococcal infections and STSS through a histamine releasing activity.

METHODS

Human mast cells and basophils were generated from CD34 positive cells isolated from cord blood and cultured in the presence of rIL-6, stem cell factor and/or rIL-3. The capacity of increasing capillary permeability of recombinant SPE B/SCP (rSPE B/SCP) was studied by using the skin of guinea pigs. Mitogenic activity to human T-cells of rSPE B/SCP was studied by incorporation of (3)Hthymidine. The levels of histamine in the plasma of patients with STSS and controls were measured by ELISA kit.

RESULTS

rSPE B/SCP induced increased capillary permeability in the skin of guinea pigs, but both SPE A and SPE C did not exhibit such activity. Histamine was released from cultured human mast cells stimulated with rSPE B/SCP. The rSPE B/SCP did not exhibit mitogenic activity to human T-cells. Three of the 7 patients with STSS showed higher levels of plasma histamine than those of normal subjects.

INTERPRETATION & CONCLUSION

The results suggested that increased capillary permeability and histamine release from mast cells induced by rSPE B/SCP might be involved in STSS and/or streptococcal infection of skin and mucous membrane.

Frequency of alterations in the GyrA subunit of DNA gyrase and the ParC subunit of topoisomerase IV in 19 clinical isolates of Neisseria gonorrhoeae in Tokyo in 2002

The frequency of alterations in the GyrA subunit of DNA gyrase and the ParC subunit of topoisomerase IV in 19 clinical isolates of Neisseria gonorrhoeae obtained in Tokyo in 2002 was studied. The frequencies of GyrA and ParC mutations in these 19 isolates were 100% (19 of 19) and 84.2% (16 of 19), respectively, and these results were 1.48-fold (100%/67.6%) and 3.58-fold (84.2%/23.5%) higher, respectively, than the frequencies reported in 1998 in 68 isolates obtained in Fukuoka during the period from 1992 to 1996. Isolates with increasing numbers of mutations were more resistant not only to levofloxacin but also to other antibiotics. The 50% and 90% minimum inhibitory concentrations (MICs) to levofloxacin during the period from 1995 to 1996 were 0.063 and 1 micro g/ml, and they increased to 4 and 8 micro g/ml, respectively, in the present study. All 19 cases of gonoccocal urethritis in the present study were cured with a single intramuscular injection of 2 g spectinomycin.

Genetic polymorphisms of CYP2C8 in Japanese population

CYP2C8 plays important roles in metabolizing therapeutic drugs and endogenous compounds. Although genetic polymorphisms of CYP2C8 were reported, there is little information on CYP2C8 polymorphisms in the Japanese population. In the present study, we screened for previously described polymorphisms in the coding region of this gene using polymerase chain reaction (PCR)-restriction fragment length polymorphism or allele specific-PCR analyses. Eleven polymorphisms of CYP2C8*2 (I269F), CYP2C8*3 (R139K, K399R), CYP2C8*4 (I264M), CYP2C8*5 (frameshift), T130N, E154D, N193K, K249R, L390S, P404A, and H411L have been comprehensively investigated in at least 200 Japanese individuals. A single subject was heterozygous for CYP2C8*5, and the allele frequency was calculated as 0.0025. The other single nucleotide polymorphisms (SNPs) were not found in the Japanese subjects in the present study. Thus, it appears that the frequencies of these alleles in Japanese are extremely low. In addition, concerning the SNPs of T130N, E154D, N193K, K249R, and H411L, it remains clear that these alleles exist as polymorphisms or represent sequence errors or cloning artifacts. Although several SNPs such as CYP2C8*2, CYP2C8*3, CYP2C8*4, and P404A have been reported to reduce the enzymatic activity, pharmacokinetic abnormalities of drugs metabolized by polymorphic CYP2C8 might be rare in Japanese.

Moderate hypothermia delays proinflammatory cytokine production of human peripheral blood mononuclear cells

OBJECTIVE

To clarify the influence of moderate hypothermia on the production of proinflammatory cytokines.

DESIGN

Controlled in vitro study.

SETTING

Research laboratory.

SUBJECTS

Peripheral blood mononuclear cells from healthy adult human subjects.

INTERVENTIONS

Stimulation with 1 microg/mL lipopolysaccharide at 33 degrees C and 37 degrees C.

MEASUREMENTS

Concentrations of released tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 were measured chronologically by enzyme immunoassay. The number of mRNA copies of these cytokines was determined by competitive reverse transcriptase-polymerase chain reaction analysis, and nuclear factor-kappaB activations were assessed by electrophoretic mobility shift assay.

MAIN RESULTS

Significant reduction of the released-tumor necrosis factor-alpha concentration was observed 1 and 2 hrs after the stimulation with lipopolysaccharide at 33 degrees C compared with 37 degrees C. The peak release of interleukin-1beta at 33 degrees C was delayed 12 hrs later than that at 37 degrees C. A delayed peak in the release of interleukin-6 also was observed at 33 degrees C. The peaks of cytokines were confirmed at the mRNA expression level by competitive reverse transcriptase-polymerase chain reaction analysis at both temperatures. The peak of the tumor necrosis factor-alpha mRNA expression level was observed at 1 hr after the stimulation at 37 degrees C and 2 hrs after the stimulation at 33 degrees C. In the interleukin-1beta mRNA expression, at 37 degrees C the first peak appeared 1 hr and the second 6 hrs after the stimulation. In contrast, at 33 degrees C, the first peak appeared 2 hrs and the second 12 hrs after the stimulation. Whereas interleukin-6 mRNA expression at 37 degrees C peaked 6 hrs after the stimulation, no definite peak was observed at 33 degrees C and the expression level was approximately half of that at 37 degrees C. The maximum intensity of nuclear factor-kappaB activation at 33 degrees C was delayed by 1.5 hrs compared with that at 37 degrees C.

CONCLUSIONS

Moderate hypothermia delays the induction of proinflammatory cytokines in human peripheral blood mononuclear cells.

Cysteine protease activity and histamine release from the human mast cell line HMC-1 stimulated by recombinant streptococcal pyrogenic exotoxin B/streptococcal cysteine protease

We constructed the expression vector pSK-SCP containing the streptococcal exotoxin B gene (spe b) which expressed protease activity. We showed that the recombinant streptococcal pyogenic exotoxin B/streptococcal cysteine protease (rSPE B/SCP) was secreted into the culture supernatant of the transformant and retained its SCP activity, which was equivalent to or greater than that of the naturally occurring molecule. The secreted rSPE B/SCP induced histamine release and degranulation of the human mast cell line HMC-1. This study may contribute to the understanding of the pathogenic role of SPE B/SCP in streptococcal infection and streptococcal toxic shock syndrome.

Effective human herpesvirus 8 infection of human umbilical vein endothelial cells by cell-mediated transmission

Cell-free transmission of human herpesvirus 8 (HHV-8) to human cells in vitro has been reported to be difficult, if not impossible. The present experiments were conducted with the idea that cell-cell contact may produce much more effective transmission, so-called cell-mediated transmission. Primary human umbilical vein endothelial cells (HUVECs) were cocultured with an HHV-8-infected lymphoma cell line, BCBL-1 cells. When a ratio of 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated BCBL-1 cells to HUVECs of 10:1 was used, more than 20% of HUVECs were found to express the HHV-8 latency-associated nuclear antigen (LANA) 48 h after the start of coculturing; this value increased to more than 30% after 72 h. HHV-8-encoded ORF26, K8, K8.1, K10, K11, ORF59, and ORF65 proteins were not detected in these HHV-8-infected HUVECs until 72 h. The HHV-8 antigens were not observed in HUVECs cocultured with TPA-treated BCBL-1 cells separated by a membrane. Thirty days after removal of the BCBL-1 cells from the cell-mediated transmission experiment, the HUVECs still expressed LANA and the HHV-8 genome was detected by PCR in these cells. Moreover, the ORF59 protein, a DNA replication-associated protein of HHV-8, was expressed in such HUVECs in the presence of TPA stimulation. These results indicated a far more effective transmission mechanism, cell-cell contact, suggesting the possibility that such a mechanism works in vivo.

[Clinical and fundamental studies of streptococcal toxic shock syndrome]

Streptococcal toxic shock syndrome(STSS) is known to progress rapidly into septic shock and multiple organ failure with frequently necrotizing fasciitis, and high mortality (approximately 40%). The diagnosis of STSS is confirmed based on the diagnosis criteria induced by the working group of the United State. Several extracellular products such as SPE A, B, and C having pyrogenic and superantigenic activity as well as SPE F, SPE G, H, J, SME Z, SME Z2, SSA are likely to involved in the pathogenesis of STSS. Recent studies have demonstrated an important role of certain cytokines, such as TNF-alpha, in laboratory animals. The exact role of such products in the pathogenesis of STSS, however, is currently unknown. The role of several virulence factors of group A streptococci in the pathogenesis of STSS was discussed in this review.

Clonotypes of Staphylococcus aureus isolated from continuous ambulatory peritoneal dialysis patients: what is the vector between nares and infection site?

Staphylococcus aureus is frequently isolated from patients with infections related to continuous ambulatory peritoneal dialysis (CAPD). In many cases, the organism is also isolated simultaneously from the anterior nares. To clarify the transmission trail of S. aureus, we used DNA analysis to identify clonotypes of clinical strains. The nares and exit sites of 32 CAPD patients were swabbed, and PD fluid samples were taken for pathogen culture. Genome DNA of S. aureus was digested with restriction enzyme Sma I for pulsed-field gel electrophoresis. We also asked the patients how they usually performed the PD procedure. S. aureus was isolated from 4 patients, including 3 who hosted two strains isolated separately from different sites. The DNA patterns of the strains isolated from these latter 3 patients were identical. However, the clonotypes from all 4 patients were different. Most of the patients did not wash their hands and wear masks while exchanging PD bags and caring for their exit sites. After the patients were disinfected and re-educated in proper procedures, S. aureus was not detected in any of them. These data suggest that no outbreak occurred in our hospital and that the vectors of endogenous infection were the patients themselves, probably their hands. A bacteriological study presents an efficient opportunity to re-educate patients in PD procedure.

Effects of "isolating hemodialysis" on prevention of methicillin-resistant Staphylococcus aureus cross-infection in a hemodialysis unit

AIM

To evaluate the effects of a contact isolation program against methicillin-resistant Staphylococcus aureus (MRSA) cross-infection among patients in a hemodialysis unit. CLINICAL SETTING AND METHODS: In all patients maintaining hemodialysis therapy were tested for MRSA infection and who had MRSA infection, not only inpatients but also outpatients were separated into a designated area (isolating hemodialysis). Clinically isolated MRSA strains were clonotyped with coagulase typing, staphylococcal enterotoxin typing and restriction enzyme analysis of plasmid DNA.

RESULTS

The frequency of patients with MRSA infection was 4.5% before starting this protocol and was reduced to 2.9% two and a half years later. At this time, MRSA was isolated from the 8 patients. These 8 clinical strains were differentiated into 6 clonotypes and 3 strains showed the same patterns. Two of 3 were isolated from inpatients and the other was from a patient with community onset MRSA colitis. In this case, most MRSA infections were independent under prophylaxis control and cross-infection was observed only once between hospitalized patients who stayed in a same ward.

CONCLUSION

This "isolating hemodialysis" should be useful to prevent cross-infection among patients in end-stage renal disease in a dialysis unit.

Synergistic bactericidal effects of acrinol and tetracycline against Pseudomonas aeruginosa

Combined treatment of acrinol (Ac) and tetracycline hydrochloride (Tc) against Pseudomonas aeruginosa strains isolated from clinical specimens synergistically increased the bactericidal effect. The minimum bactericidal concentration (MBC) of Ac against P. aeruginosa strain no. 985 was 200 microg/ml, while the MBC of Ac against strains no. 47 and no. 783 was above 800 microg/ml for each. The MBC of Tc was above 400 microg/ml against each of the tested strains. However, simultaneous treatment with 25 microg/ml Ac and 200 microg/ml Tc against P. aeruginosa strain no. 985 decreased the viable cell number from 107 cfu/ml to <10 cfu/ml within 24 h, while a higher concentration of Tc (400 microg/ml) with Ac (25 microg/ml) reduced the viable cell number to <10 cfu/ml within 8 h. A similar synergistic bactericidal effect of Ac and Tc was observed in strains no. 47 and no. 783 by treatment with 200 microg/ml Ac and 200 microg/ml or 400 microg/ml Tc. The degree of bactericidal effect against P. aeruginosa was proportional to the concentration of Tc under the condition of a constant concentration of Ac. Furthermore, Ac-treated cells of strain no. 47 were killed by a following Tc treatment, but cells pretreated with Tc did not show such a sensitivity to Ac. To induce the synergistic effect of Ac and Tc, Ac must be applied to P. aeruginosa before or at the same time as Tc.

Adjuvant activities of pyrene, anthracene, fluoranthene and benzo(a)pyrene in production of anti-IgE antibody to Japanese cedar pollen allergen in mice

We have previously demonstrated that pyrene in diesel-exhaust particles (DEP) has an adjuvant activity on immunoglobulin E (IgE) antibody production in mice immunized with Japanese cedar pollen allergen (JCPA) or ovalbumin (OA) intraperitoneally. The present study is concerned with the adjuvant activity in IgE antibody production against JCPA of pyrene or DEP inoculated intranasally in mice. We show that anthracene, fluoranthene and benzo(a)pyrene in DEP have the ability to enhance anti-JCPA IgE antibody production in mice by intranasal immunization. Mice were grouped, immunized with 10 micrograms of JCPA plus 400 micrograms of pyrene, 10 micrograms of JCPA plus 100 micrograms of DEP, 10 micrograms of JCPA plus 2 mg of aluminum hydroxide and 10 micrograms of JCPA alone intranasally 7 times at 2 week intervals. Mice were also grouped, and immunized with JCPA (10 micrograms) plus 40 micrograms of anthracene, JCPA (10 micrograms) plus 400 micrograms of fluoranthene, JCPA (10 micrograms) plus 40 micrograms of benzo(a)pyrene, and JCPA (10 micrograms) plus 400 micrograms of pyrene and JCPA (10 micrograms) alone. We found that the IgE antibody responses to JCPA in mice immunized with JCPA plus pyrene, JCPA plus DEP or JCPA plus the three chemical organic compounds mentioned above were significantly enhanced compared with those immunized with JCPA alone. In addition, when the intraperitoneal macrophages obtained from the normal mice (unimmunized mice) were incubated with pyrene, anthracene, fluoranthene or benzo(a)pyrene in vitro, an enhanced chemiluminescence (CI) response and interleukin-1 alpha (IL-1 alpha) production of the macrophages was observed in each instance. These results suggest that in the production of IgE antibody to JCPA the adjuvancy of polycyclic aromatic hydrocarbons (PAHs) in DEP may be important in an attack of Japanese cedar pollinosis.

Streptococcus peroris sp. nov. and Streptococcus infantis sp. nov., new members of the Streptococcus mitis group, isolated from human clinical specimens

Taxonomic studies were performed on eight strains of alpha-haemolytic streptococci that showed very low DNA-DNA hybridization similarity values with all established members of the mitis group of the genus Streptococcus. These strains were isolated from the tooth surface and pharynx of humans. 16S rRNA gene sequence analysis showed that these strains belonged to the mitis group, but that they fell into two new branches. DNA-DNA hybridization demonstrated two new similarity groups. From the results of the present study, the names Streptococcus peroris sp. nov. and Streptococcus infantis sp. nov. are proposed for these new groups. The type strains are O-66T (= GTC 848T = JCM 10158T) and O-122T (= GTC 849T = JCM 10157T), respectively.

[Report of surveillance on streptococcal toxic shock syndrome in Japan and presentation of the criteria]

A survey was made on the situation of Group A Streptococcal toxic shock syndrome (STSS) based on questionnaires. The survey was divided into two parts. The first survey was done by sending out an outline of the STSS inquiring if any STSS cases were observed by mail to university hospitals, residence training hospital and other major hospitals totaling 2512 institutes. The second survey was subsequently done to the institutes that had STSS cases asking for the clinical course, data and sampling of the bacteria. The diagnosis of STSS was confirmed based on the diagnostic criteria induced by the working group of the United States. We have found 97 cases of STSS which 48.5% had fatal outcomes. There was no significant sex difference in the onset or the mortality rate. It occurred more in the older population, and occurred through out Japan but was not found to be epidemic. The first case was backed in 1978 and it began to increase since 1993, reaching its peak in 1994 and now decreasing in number. Most of the isolated Group A streptococcus were of type M1 and M3. We have modified the United States diagnostic criteria creating a new Japanese criteria, which includes the symptoms of the central nervous system in the term MOF. The aim for the Japanese criteria is to search for the etiology of the disease. The Japanese criteria requires that the disease progresses rapidly and that the patient be free from any conditions that might suppress the immunal system.

Adjuvant activity of diesel exhaust particulates (DEP) in production of anti-IgE and anti-IgG1 antibodies to mite allergen in mice

The present study indicates that diesel exhaust particulates (DEP) and pyrene contained in DEP have an adjuvant activity on IgE and IgG1 antibody productions in mice immunized intranasally with a mite allergen. The effect of pyrene on IgE and IgG1 antibody productions in mice was investigated to clarify the relation between mite allergy and adjuvancy of the chemical compounds in DEP. Der f II, one of the major allergens of house dust mite (Dermatophagoides farinae), was used as a mite allergen. Mice were grouped, and immunized with 5 micrograms of Der f II alone, 5 micrograms of Der f II plus 200 micrograms of pyrene and 5 micrograms of Der f II plus 100 micrograms of DEP intranasally seven times at two week intervals. The separate groups of mice were also immunized with 10 micrograms of Der f II plus the same dose of adjuvants in the same way. The IgE antibody responses to Der f II in mice immunized with Der f II plus pyrene or Der f II plus DEP were markedly enhanced compared with those immunized Der f II alone. The anti-Der f II IgE antibody production increased with increasing the dose of Der f II from 5 micrograms to 10 micrograms in mice immunized with Der f II plus the same dose of adjuvants. The IgG1 antibody responses to Der f II in mice immunized with 10 micrograms of Der f II plus 200 micrograms of pyrene or 10 micrograms of Der f II plus 100 micrograms of DEP were extremely higher than those immunized with 10 micrograms of Der f II alone. In addition, when the peritoneal macrophages obtained from normal mice were incubated with pyrene or DEP in vitro, an enhanced interleukin-1 alpha production of the macrophages was observed. When the spleen lymphocytes obtained from the mice immunized with 10 micrograms of Der f II plus 100 micrograms of DEP or 10 micrograms Der f II plus 200 micrograms of pyrene were stimulated with 10 micrograms of Der f II in vitro, an enhanced IL-4 production of the lymphocytes was also observed compared with those immunized with Der f II alone. These results suggest that the adjuvancy of DEP and pyrene on the production of IgE and IgG1 antibodies to Der f II may be one of the factors responsible for an incidence of asthma caused by house dust mite.

Purification and partial characterization of a novel human platelet aggregation factor in the extracellular products of Streptococcus mitis, strain Nm-65

A human blood platelet aggregation factor was purified from the extracellular products (ECP) of Streptococcus mitis, strain Nm-65 by sequential chromatography on DEAE-Sepharose CL-6B, hydroxyapatite and Superdex 75 columns. The purified factor (S. mitis-derived human platelet aggregation factor, Sm-hPAF) gave a single band with a molecular weight of 66 kDa on SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Sm-hPAF showed a peak absorption at 278 nm and an isoelectric point of around 8.5. Chemical analyses revealed that Sm-hPAF contained no sugars and that its first 15 amino-terminal amino acid residues were H-DEQGNRPVETENIAR. Platelet aggregation activity of Sm-hPAF was abolished by heating at 45 degrees C for 10 min. Platelet aggregation by Sm-hPAF was accompanied by a release of prostaglandin E2 (PGE2) in a dose-dependent manner. The platelet aggregation was not inhibited by either prostaglandin E1 (PGE1) or Gly-Arg-Gly-Asp-Ser (GRGDS), that inhibit the platelet aggregation induced by collagen. Twenty (77%) platelet rich-plasma (PRP) specimens derived from 26 healthy volunteers were aggregated by Sm-hPAF, but the remaining 6 (23%) were not reactive. A preliminary study suggested the presence of an inhibitory factor against Sm-hPAF in the plasma from a non-reactive donor.

Induction of lymphocytes cytotoxic to oral epithelial cells by Streptococcus mitis superantigen

The preparation of a superantigenic fraction F-2 from the culture supernatant of Streptococcus mitis 108, a fresh isolate from human tooth surfaces, was reported previously. Now, to determine the possible pathogenic role of the superantigen in oral mucosal diseases, we examined the cytotoxic effects of human peripheral blood T-cells activated with F-2 on human oral epithelial cells. T-cells activated with F-2 were cytotoxic to the human squamous carcinoma HO-1-N-1 cells derived from the oral mucosa, similar to those activated with Staphylococcus aureus enterotoxin B (SEB). This cytotoxic effect was increased in a dose-dependent manner by the addition of the respective stimulant, F-2 or SEB, to the cytotoxic assay system. F-2 endowed mainly CD8+ T-cells with cytotoxic activity. Pretreatment with human interferon gamma increased the sensitivity of the HO-1-N-1 cells to the cytotoxic effects of F-2-activated T-cells. The F-2-activated T-cells were also cytotoxic to human keratinocytes derived from gingiva. There was no correlation between the degree of cytotoxicity and the levels of tumor necrosis factor alpha in co-cultures of F-2-activated T-cells and HO-1-N-1 cells. A double-chamber plate experiment revealed no cytotoxic effects when the F-2-activated T-cells were separated from the HO-1-N-1 cells. Supernatants of the co-cultures of target and effector cells were not cytotoxic to HO-1-N-1 cells. These findings suggest that the cytotoxic effects of the F-2-activated T-cells on HO-1-N-1 cells were mediated not by soluble factors but by the direct interaction between the activated T-cells and the target cells. The cytotoxicity of the F-2-activated T-cells against HO-1-N-1 cells was markedly inhibited by monoclonal antibodies (MAbs) against CD11a and CD54, but was only slightly inhibited by MAbs against human leukocyte antigen (HLA)-DR and CD2. Thus, the interaction between lymphocyte-function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) was crucial for the F-2-dependent T-cell-mediated cytotoxicity against oral epithelial cells, while HLA-DR and CD2 molecules are not necessarily involved in the cytotoxicity observed.

Efficacy of gentian violet in the eradication of methicillin-resistant Staphylococcus aureus from skin lesions

The efficacy of gentian violet (Gv) in eradicating methicillin-resistant Staphylococcus aureus (MRSA) in decubitus ulcers was investigated. Decubitus ulcers (a total of 18 cases) were scrubbed with Gv aqueous solution 0.1% and ointment containing Gv 0.1% was applied daily. MRSA was not detected in these lesions for 3-34 days (average, 10.5 +/- 2.5 days) after the application of Gv ointment. Before this trial, all patients were treated with povidone-iodine and antibiotics; however, those treatments were not effective in eradicating MRSA from skin lesions. Skin irritation and other systemic side effects caused by Gv were not observed. Our data suggest that Gv is a useful agent for treatment of the decubitus ulcers infected with MRSA.

Alveolar fibrosis and capillary alteration in experimental pulmonary silicosis in rats

To analyze the evolution of fibrotic and vascular changes in pulmonary silicosis, ultrastructural and immunohistochemical studies were made of the lungs of rats given a single intratracheal injection of silica particles. Early lesions were characterized by accumulations of macrophages and neutrophils in alveolar lumina and interstitium and by damage to alveolar capillaries and epithelial cells. The intraluminal masses of inflammatory cells developed into granulomas and became associated with myofibroblasts that migrated from the interstitium through the damaged epithelial lining. Type II epithelial cells and bronchiolar cuboidal cells proliferated rapidly to line the intraluminal granulomas, incorporating them into the interstitium. This process mediated the transition from intraalveolar fibrosis to interstitial fibrosis. Vascular damage was repaired by proliferation and migration of endothelial cells. Some endothelial cells in alveolar capillaries expressed Factor VIII-related antigen at 2 wk after silica infusion. In normal animals, this feature was present in peribronchiolar but not in alveolar capillaries. Two patterns of endothelial cell migration were shown by staining for proliferating-cell nuclear antigen. The first pattern was characterized by endothelial cells that extended their cytoplasm over preexisting, denuded basement membranes and replaced necrotic cells in alveolar capillaries. At 4 mo after injury, some of these cells had developed fenestrations. The second pattern consisted of budlike sproutings that developed only in peribronchiolar connective tissue. These observations indicate that peribronchiolar vessels are sources for renewal of alveolar capillary endothelium as well as for neovascularization.

Immunopathological activities of extracellular products of Streptococcus mitis, particularly a superantigenic fraction

Previously, we prepared extracellular products, fractions F-1 and F-2 of Streptococcus mitis 108, an isolate from the tooth surface of an infant, and showed that F-1 exhibited inflammatory cytokine-inducing activities. In the present study, we present evidence that fraction F-2 induced human T-cell proliferation in the presence of irradiated human peripheral blood mononuclear cells and selectively activated T cells bearing V beta 2 and V beta 5.1 in the T-cell receptor. F-1, on the other hand, stimulated human gingival fibroblasts to support the T-cell proliferation in the same way as human gamma interferon or Prevotella intermedia lipopolysaccharide (LPS). Fraction F-1 also primed gingival fibroblasts to support the production of interleukin-2 and gamma interferon by the T cells upon stimulation with F-2. Human gingival fibroblasts stimulated with fraction F-1, like those stimulated by P. intermedia LPS and human gamma interferon, exhibited human leukocyte antigen (HLA)-DR mRNA expression and cell surface HLA-DR molecules as detected by enzyme-linked immunosorbent assay. An anti-HLA-DR monoclonal antibody inhibited T-cell proliferation in response to F-2, probably through inactivating the accessory function of HLA-DR-bearing fibroblasts. T cells activated with F-2 in the presence of irradiated peripheral blood mononuclear cells exhibited definite cytotoxic effects against fibroblasts and squamous carcinoma cells originating from human oral tissues. These findings are strongly suggestive of an association of extracellular products of viridans streptococci with pathogenesis of oral mucosal diseases, particularly those disorders in gingiva which are accompanied by heavy infiltration of T cells.

Superantigenic exotoxin production by isolates of Staphylococcus aureus from the Kawasaki syndrome patients and age-matched control children

Nineteen strains of Staphylococcus aureus were isolated from the throat or the tooth surfaces of 19 cases amongst 127 patients with Kawasaki syndrome (KS) during the acute phases and 11 S. aureus isolates were obtained from five of 17 diseased controls and six healthy controls. The production of exotoxins, particularly superantigenic toxic shock syndrome toxin-1 (TSST-1), coagulase serotype, pigment production, haemolytic activity and tryptophan auxotrophy of these isolates were compared. Among 10 KS S. aureus strains isolated in 1990-1991, five (50%) secreted TSST-1, a higher frequency than two (18%) of 11 control isolates. In contrast, none of the nine KS strains collected in 1984 produced TSST-1. Four of five TSST-1-secreting KS strains produced white or white to golden pigmentation, whereas the two control strains capable of TSST-1 production formed golden colonies. There were no noticeable differences between S. aureus strains from KS patients and control children in the production of staphylococcal exotoxins A-E, coagulase serotype, haemolysis of sheep erythrocytes and tryptophan auxotrophy. The pathological or aetiological role of a new TSST-1-secreting S. aureus clone in patients with KS was not confirmed.

[Synergism on the bactericidal effect of gentian violet (Gv) and acrinol (Ac) against Pseudomonas aeruginosa]

The MBCs of Ac against P. aeruginosa (7 strains) isolated from infected skin lesions of patients were more than 6400 micrograms/ml, and those of Gv were more than 1600 micrograms/ml. When either Ac or Gv was used independently, these dyes did not have the bactericidal effect of P. aeruginosa. When Gv was used in combination with Ac, predominantly synergism on the bactericidal effect of Ac and Gv against P. aeruginosa was observed. The MBCs of an Ac-Gv cocktail were between 100 micrograms/ml and 225 micrograms/ml. We have previously reported that Gv possessed significantly a bactericidal effect to MRSA isolated from clinical specimens. Therefore, these results suggested that a combination treatment by an Ac-Gv cocktail may be one of the useful drugs for the MRSA and P. aeruginosa mixed infection on the skin lesions which is frequently observed clinically.

The presence of tumor necrosis factor-alpha and its antibody in the sera of cachexic patients with gastrointestinal cancer

Although cancer cachexia has been shown to involve several cytokines, the tumor necrosis factor-alpha (TNF) has rarely been detected in such patients. In this study, sera from 21 patients with cancer cachexia were examined for the presence of TNF and the anti-TNF antibody using an enzyme-linked immunosorbent assay (ELISA) and Western blotting, respectively. All of the patients had recurrent cancer and manifested the characteristics of progressive body weight loss. TNF was found in the sera of four patients (20%) at levels ranging from 10.4 to 53.1 pg/ml, while a positive reaction for the anti-TNF antibody was detected in the sera from six patients (30%), two of whom showed both TNF and its antibody. Thus, either TNF or the anti-TNF antibody was present in the sera from 8 of 21 patients (40%). The results of this study indicate that TNF may be present in the circulation of at least 40% of cachexic patients, and suggest that it may be one of the main mediators of cancer-associated cachexia.

Cytokine induction by extracellular products of oral viridans group streptococci

During an etiological study of Kawasaki disease (mucocutaneous lymph node syndrome [MCLS]), we found that dominant viridans streptococcal strains on tooth surfaces and in the throat of both MCLS patients and non-MCLS control children formed erythrogenic and biologically active, extracellular products. In this study, we demonstrated that erythrogenic culture supernatant concentrates of representative strains (two Streptococcus mitis and two Streptococcus oralis), when injected intravenously, induced serum tumor necrosis factor alpha, interleukin-6 (IL-6), and gamma interferon in muramyldipeptide- or Propionibacterium acnes-primed C3H/HeN mice. The concentrates also induced tumor necrosis factor alpha, IL-6, and thymocyte-activating factor (essentially IL-1) in murine peritoneal macrophage, human monocyte, and human whole-blood cultures. An erythrogenic, heat-labile extracellular protein fraction (F-1) that was concentrated from the culture supernatants of a representative S. mitis strain exhibited the above-mentioned cytokine-inducing activity. This partially purified F-1 fraction also induced thymocyte-activating factor and IL-6 in human umbilical vascular endothelial cell and gingival fibroblast cultures.

Biologically active extracellular products of oral viridans streptococci and the aetiology of Kawasaki disease

A bacteriological study of isolates from the oral cavity of patients with Kawasaki disease (KD), age-matched non-KD patients and healthy children, showed that over half the KD and control isolates had gram-positive, catalase-negative cocci. About 50% of these organisms were identified as viridans streptococci by means of an API Strep 20 kit. Further identification by fluorometric DNA-DNA hybridisation demonstrated that the predominant species were S. oralis and S. mitis, each of which accounted for 25% of the isolates of viridans streptococci; 40% of viridans strains were unidentifiable; and S. sanguis and S. parasanguis were minor components. Studies in vivo showed that insertion of culture supernates of most of the viridans streptococci increased capillary permeability and induced redness with swelling and occasional bleeding in rabbit skin. One-third of S. mitis strains and one-fifth of the unidentified strains caused aggregation of human blood platelets, whereas S. oralis and other strains had no such effect. The distribution of extracellular lipoteichoic acids and glucan produced in the presence of sucrose was also examined. There were no significant differences in the recovery rate of viridans streptococci forming these biologically active extracellular products between KD and control groups.

[Effect of gentian violet on the elimination of methicillin-resistant Staphylococcus aureus (MRSA) existing in the decubitus region]

Methicillin-resistant Staphylococcus aureus (MRSA) is frequently isolated from skin lesions, such as in the decubitus region. There is a possibility that MRSA through these lesions can spread widely in a hospital. However, local treatment with most antibiotics and antiseptics (povidone-iodine) is not effective to eradicate MRSA from the infected decubitus. We have recently demonstrated that gentian violet (Gv) possessed a bactericidal effect against MRSA isolated from clinical specimens in vitro. This examination evaluated whether or not a topical ointment containing 0.1% Gv is effective to eradicate MRSA which existed in decubitus regions. Decubitus (14 clinical cases, ages 59-87 years) infected with MRSA were treated with 0.1% Gv-ointment once or twice daily after bathing in 0.1% Gv aqueous solution. Although all patients were treated with povidone-iodine and 9 out of 14 patients were given either local or systemic administration of antibiotics, those treatments were not effective to eradicate MRSA from decubituses. However, MRSA was not detectable in all cases within 34 days (average: 10.8 days +/- 2.7) after treatment with 0.1% Gv-ointment. The eradication of MRSA from decubitus areas tended to be delayed, depending upon the size and depth of decubituses (Grade III and IV) and complications such as diabetes mellitus. Skin irritability was not observed in any patients. These results suggest that 0.1% Gv-ointment is a useful material for the treatment of the MRSA-local wound infection. Treatment with Gv-ointment to MRSA-infected decubitus may exhibit a protective effect with regard to infection with MRSA in hospital.

The adjuvant activity of pyrene in diesel exhaust on IgE antibody production in mice

In this communication, it is shown that pyrene has an adjuvant activity on IgE antibody production when mice are immunized by an intraperitoneal injection of ovalbumin (OA) or Japanese cedar pollen allergen (JCPA) with pyrene. The effects of pyrene on IgE antibody production in mice were investigated to clarify the relation between pollen allergy and the adjuvanticity of the chemical compounds contained in diesel-exhaust particulates (DEP). In the first experiment, three groups of mice were immunized intraperitoneally six times at 2-week intervals with 1 microgram of OA alone, 1 microgram of OA plus 1 mg of pyrene, and 1 microgram of OA plus 1 mg of DEP, respectively. The IgE antibody responses to OA in mice immunized with OA plus pyrene or OA plus DEP were extremely enhanced as compared with those in mice immunized with OA alone, and the highest responses were observed in mice immunized with OA plus DEP. In the second experiment, mice were immunized with 10 micrograms of JCPA alone or 10 micrograms of JCPA plus 5 mg of pyrene in the same way. The IgE antibody responses to JCPA in mice immunized with JCPA plus pyrene were higher than those in mice immunized with JCPA alone. The intraperitoneal macrophages of the mice also clearly stimulated in vitro by pyrene on chemiluminescence assay. These results suggest that pyrene contained in DEP acts as an adjuvant in IgE antibody production when mice are immunized with antigens.

[Adhesion ultrastructures of mononuclear cells in experimentally-induced silicotic granuloma]

Experimental silicosis was induced by intratracheal infusions of 1 ml saline containing 50 mg standard silica (less than 5 microns diameter) in Sprague-Dawley rats. The lung tissues were observed histologically and ultrastructurally from half an hour up to 4 months. Macrophages, neutrophils, desquamated cells and their debris piled up around the alveolar ducts where the central cores of silicotic granuloma appeared. The granuloma became apparent by day 4 after the infusion and were covered by type II alveolar epithelial cells and bronchiolar cuboidal epithelial cells. Macrophages, fibroblasts and epithelial cells began to react to the antibody against proliferating cell nuclear antigen (PCNA) indicating self-replication on day 1. Macrophages in the granuloma made a close interdigitation with adjacent macrophages, and they gradually formed subplasmalemmal linear densities (SPLD) as paired forms between adjacent plasma membranes, and unpaired forms facing the interstitial matrix. SPLD were composed of linear densities with actin-like microfilaments along the leaflets of plasma membrane and were associated with extracellular dense bands which resembled a limited length of basement membrane. Interdigitation and SPLD structures were quite rare on day 1, but the number of macrophages with both structures increasingly appeared. The frequency of SPLD in macrophages also increased on a time course of granuloma maturation up to 4 months. Thus SPLD, which were originally found in the mononuclear phagocytes including macrophages, epithelioid cells and multi-nucleated giant cells, particularly in immune granuloma of man, also played a basic role in immobilizing macrophages in lesions of silica-induced granulomas.

Detection of antibodies against streptococcal peptidoglycan and the peptide subunit (synthetic tetra-D-alanyl-bovine serum albumin complex) in rheumatic-diseases

Serum antibodies reactive with streptococcal cell wall peptidoglycan (PG) and its peptide subunit (synthetic tetra-D-alanine) were measured by enzyme-linked immunosorbent assay (ELISA) in patients with rheumatoid arthritis (RA), juvenile rheumatoid arthritis (JRA), osteoarthritis and acute rheumatic fever (RF) compared with healthy subjects. Using 'checkerboard' titrations, anti-PG antibody in human serum was detected at a concentration of PG antigen at 10 micrograms per well with serum dilutions of 1:1,000. For measurement of anti-tetra-D-alanine antibody, the antigen, (D-Ala4)31 was used at 0.5 micrograms per well and sera were diluted to 1:200. When the IgG antibody levels to the PG and the tetra-D-alanine of the sera of patients with RA, JRA and RF were compared with sera from healthy subjects, the sera of the patients had significantly higher levels than did healthy subjects. Antibody that reacted with the PG in serum was absorbed with purified group-specific C-carbohydrate (A-CHO), but A-CHO was not capable of absorbing anti-(D-Ala4)31 antibodies. Therefore, the peptide subunit should be used as antigen in order to measure the specific antibody to PG. Both anti-PG and anti-tetra-D-alanine antibody in human sera primarily belonged to the IgG2 subclass.

Immunochemical studies and complete amino acid sequence of the streptokinase from Streptococcus pyogenes (group A) M type 12 strain A374

The complete amino acid sequence of the streptokinase (SKase) of Streptococcus pyogenes M type 12 strain A374, isolated from a patient with poststreptococcal glomerulonephritis (PSGN), was determined. The epitope domain for the monoclonal antibody N-59, which cross-reacts with SKases of both the PSGN-associated strain and S. equisimilis H46A (a non-PSGN-associated strain), was predicted to be localized in residues 370 to 374. The epitope domain specific for monoclonal antibody RU-1, which reacts only with the PSGN-associated SKase, was localized to residues 164 to 236.

Detection of nephritis strain-associated streptokinase by monoclonal antibodies

Monoclonal antibodies (MAbs) N-59 and RU-1 were produced by immunisation of mice with streptokinase secreted by Streptococcus group A, type 12, strain A374 isolated from a patient with post-streptococcal glomerulonephritis (PSGN) and were characterised by Western blot analysis. MAb N-59 recognised antigenic determinants shared by both nephritis strain-associated streptokinase (NSA-SKase) and streptokinase of Streptococcus group C (C-SKase); MAb RU-1 reacted only with NSA-SKase. All nephritis-associated group A streptococcal strains tested reacted with MAb N-59; 87.5% of these strains reacted with MAb RU-1. MAb N-59 reacted with SKase produced by group G streptococcal strains isolated from patients with PSGN, and MAb RU-1 recognised SKase in two out of three of these strains.