The role of type III secretion system and lens material on adhesion of Pseudomonas aeruginosa to contact lenses

PURPOSE

To determine the distribution of invasive and cytotoxic genotypes among ocular isolates of P. aeruginosa and investigate the influence of the type III secretion system (T3SS) on adhesion to conventional, cosmetic, and silicone hydrogel contact lenses (CL).

METHODS

Clinical isolates from 2001 to 2010 were analyzed by multiplex PCR for exoS, exoU, and exoT genes. Bacterial adhesion to etafilcon, nelfilcon (gray colored), balafilcon, and galyfilcon CL with or without artificial tear fluid (ATF) incubation were compared. Surface characteristics were determined with scanning electron microscopy (SEM).

RESULTS

Among 87 total isolates, 64 strains were from microbial keratitis cases. CL-related microbial keratitis (CLMK) isolates were mostly of the cytotoxic genotype (expressing exoU) (P = 0.002). No significant differences were found in bacterial adhesion to all types of CL between the genotypes under T3SS-inducing conditions. A trend for least bacterial adhesion of galyfilcon compared to the other CL was noted for both genotypes. Needle complex pscC mutants adhered less to all materials than the wild type (P < 0.05), indicating a role of the T3SS in contact lens adhesion. ATF-incubated CL had significantly more bacterial adhesion (P < 0.05). SEM showed most of the bacteria adhering on CL surfaces.

CONCLUSIONS

CLMK isolates were mostly of cytotoxic genotype. Different genotypes did not significantly differ in its adhesion to various CL. T3SS and other adhesins are involved in bacteria-contact lens adhesion through complex interactions. Contact lens materials may also play an important role in the adherence of both genotypes of P. aeruginosa.

Imaging granularity of leukocytes with third harmonic generation microscopy

Using third harmonic generation (THG) microscopy, we demonstrate that granularity differences of leukocytes can be revealed without a label. Excited by a 1230 nm femtosecond laser, THG signals were generated at a significantly higher level in neutrophils than other mononuclear cells, whereas signals in agranular lymphocytes were one order of magnitude smaller. Interestingly, the characteristic THG features can also be observed in vivo to track the newly recruited leukocytes following lipopolysaccharide (LPS) challenge. These results suggest that label-free THG imaging may provide timely tracking of leukocyte movement without disturbing the normal cellular or physiological status.

Platelets enhance biofilm formation and resistance of endocarditis-inducing streptococci on the injured heart valve

Infective endocarditis is a typical biofilm-associated infectious disease frequently caused by commensal streptococci, but the contribution of host factors in biofilm formation is unclear. We found that platelets are essential for in vitro biofilm formation by Streptococcus mutans or Streptococcus gordonii grown in human plasma. The biofilms were composed of bacterial floes embedded with platelet aggregates in layers, and a similar architecture was also detected in situ on the injured valves of a rat model of experimental endocarditis. Similar to planktonic cells, the streptococci in biofilms were also able to induce platelet aggregation, which facilitates multilayer biofilm formation. Entrapping of platelets directly enhances the resistance of streptococcal biofilms to clindamycin. Prophylactic antibiotics or aspirin can reduce but not prevent or abolish biofilm formation on injured heart valves. Therefore, the platelet is a host factor for commensal streptococci in the circulation to consolidate biofilm formation and protect bacteria against antibiotics.

Increased prevalence of interleukin-17-producing CD4(+) tumor infiltrating lymphocytes in human oral squamous cell carcinoma

BACKGROUND

T helper 17 (Th17) and regulatory T cells share plasticity in the expression of interleukin (IL)-17 and forkhead box P3 (FOXP3), but their mutual presence in human diseases is unclear.

METHODS

IL-17 and FOXP3 were analyzed by immunohistostaining and flow cytometry. The cytokine milieu was analyzed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

Oral squamous cell carcinoma expresses high levels of IL-1β, IL-6, and transforming growth factor (TGF)-β. A unique subset of FOXP3(+) IL-17-producing CD4(+) T cells was consistently identified in tumor-infiltrating lymphocytes from advanced stages of cancer, but not in the circulation, at a frequency of 0.5% to 5.5 % of total CD4(+) T and positively correlated with the frequency of IL-17(+)FOXP3(-) T cells. The IL-17(+)FOXP3(+) T cells express CCR6 and suppress the proliferation of autologous CD4(+) CD25(-) responder T-cells in vitro.

CONCLUSIONS

The prevalence of IL-17-producing FOXP3(+) CD4(+) tumor infiltrating lymphocytes is increased in oral squamous cell carcinoma.

Streptococcus mutans autolysin AtlA is a fibronectin-binding protein and contributes to bacterial survival in the bloodstream and virulence for infective endocarditis

Streptococcus mutans, a commensal of the human oral cavity, can survive in the bloodstream and cause infective endocarditis (IE). However, the virulence factors associated with this manifestation of disease are not known. Here, we demonstrate that AtlA, an autolysin of S. mutans is a newly identified fibronectin (Fn) binding protein and contributes to bacterial resistance to phagocytosis and survival in the bloodstream. Interestingly, prior exposure to plasma at low concentrations was sufficient to enhance bacterial survival in the circulation. Calcium ions at physiological plasma concentrations induced maturation of AtlA from the 104-90 kDa isoform resulting in increased Fn binding and resistance to phagocytosis. An isogenic mutant strain defective in AtlA expression exhibited reduced survival and virulence when tested in a rat model of IE compared with the wild-type and complemented strains. The data presented suggest that plasma components utilized by S. mutans enhanced survival in the circulation and AtlA is a virulence factor associated with infective endocarditis.

Treatment with levamisole and colchicine can result in a significant reduction of IL-6, IL-8 or TNF-alpha level in patients with mucocutaneous type of Behcet's disease

BACKGROUND

Mucocutaneous type of Behcet's disease (MCBD) is a multisystemic inflammatory disease with oral and genital ulcers with or without skin lesions.

METHODS

A solid phase, two-site sequential chemiluminescent immunometric assay was used to measure serum levels of interleukin (IL)-6, IL-8 and tumour necrosis factor (TNF)-alpha in 54 normal control subjects and in 64 MCBD patients before and after treatment with levamisole plus colchicine.

RESULTS

We found that 67%, 83% or 67% of MCBD patients had a serum IL-6, IL-8 or TNF-alpha level greater than the upper normal limit of 4.7, 8.7 or 7.4 pg/ml, respectively. The mean serum level of IL-6 (9.9 +/- 2.4 pg/ml, P < 0.005), IL-8 (107.5 +/- 21.4 pg/ml, P < 0.001) or TNF-alpha (22.5 +/- 4.1 pg/ml, P < 0.001) in 64 MCBD patients was significantly higher than that (2.1 +/- 0.2, 5.7 +/- 0.2 or 3.8 +/- 0.2 pg/ml for IL-6, IL-8 or TNF-alpha level, respectively) in normal control subjects. In 43 MCBD patients with all the serum IL-6, IL-8 and TNF-alpha levels higher than their upper normal limits, treatment with levamisole plus colchicine for a period of 0.5-11.5 (mean, 3.2 +/- 2.4) months could significantly reduce the mean serum IL-6, IL-8 and TNF-alpha levels from 9.0 +/- 1.7 to 1.6 +/- 0.2 pg/ml (P < 0.001), 134.6 +/-28.2-6.0 +/- 0.4 pg/ml (P < 0.001) and 25.7 +/- 5.6-3.5 +/- 0.4 pg/ml (P < 0.001), respectively.

CONCLUSIONS

Treatment with levamisole and colchicine can result in a significant reduction of serum IL-6, IL-8 or TNF-alpha level in MCBD patients.

Chromosomal inversion between rrn operons among Streptococcus mutans serotype c oral and blood isolates

Streptococcus mutans causes dental caries and infective endocarditis. The aim of this study was to determine genomic diversity among serotype c S. mutans laboratory and clinical strains and to characterize the genetic events involved. A genome-based approach using PFGE coupled with Southern hybridization was employed to examine a total of 58 serotype c oral and blood isolates and seven laboratory strains and to compare them with S. mutans UA159. No significant differences were found in the phenotypic characteristics of the strains tested, except that some of the strains exhibited smooth rather than rough colony morphology. In contrast, PFGE profiles of clinical isolates, from either diseased or healthy subjects, exhibited diverse patterns, suggesting that recombination or point mutations occurred frequently in vivo. Diverse PFGE patterns, with various lengths of insertions and deletions, could be detected even within a localized chromosomal region between rRNA operons. Comparative analysis using Southern hybridization with specific markers revealed that a large chromosomal inversion had also occurred between rrn operons in 25 strains.

The two-component system ScnRK of Streptococcus mutans affects hydrogen peroxide resistance and murine macrophage killing

To survive macrophage killing is critical in the pathogenesis of viridians streptococci-induced infective endocarditis (IE). Streptococcus mutans, an opportunistic IE pathogen, generally does not survive well phagocytic killing in murine macrophage RAW 264.7 cells. A putative two-component system (TCS), ScnR/ScnK from S. mutans, was investigated to elucidate the mechanisms underlying bacteria-cellular interaction in this study. Both the wild-type and mutant strains were phagocytosed by RAW 264.7 cells at a comparable rate and an increased intracellular susceptibility during a 5 h incubation period was observed with the scnRK-null mutants. The amount of reactive oxygen species (ROS) in activated macrophages was reduced significantly after ingesting wild-type, but not scnRK-null mutant strains, suggesting that increased macrophage killing of these mutants is due to the impaired ability of S. mutans to counteract ROS. Additionally, both scnR- or scnRK-null mutants were more susceptible to hydrogen peroxide. Interestingly, scnRK expression was unaffected by hydrogen peroxide. These experimental results indicate that scnRK is important in counteracting oxidative stress in S. mutans, and decreased susceptibility to phagocytic killing is at least partly attributable to inhibition of intracellular ROS formation.

Levamisole can reduce the high serum tumour necrosis factor-? level to a normal level in patients with erosive oral lichen planus

In this study, we measured the baseline serum levels of tumour necrosis factor (TNF)-alpha in 158 patients with oral lichen planus (OLP) and in 54 normal control subjects. In total, 60 patients with erosive OLP (EOLP) with relatively high TNF-alpha levels were treated with levamisole and the serum TNF-alpha levels measured after treatment. We found that the mean +/- SD serum level of TNF-alpha in patients with either type of EOLP (12.0 +/- 1.7 pg/mL, P<0.005), major EOLP (15.5 +/- 4.4 pg/mL, P<0.001), minor EOLP (11.1 +/- 1.8 pg/mL, P<0.01), or nonerosive OLP (6.1 +/- 1.7 pg/mL, P<0.05) was significantly higher than that (3.8 +/- 0.2 pg/mL) of normal control subjects. Treatment with levamisole for a period of 0.5-7.5 months significantly reduced the mean serum TNF-alpha level from 22.6 +/- 3.4 pg/mL to 6.2 +/- 0.8 pg/mL (P<0.001) in 60 patients with EOLP. We conclude that levamisole can reduce high serum TNF-alpha levels to normal in patients with EOLP.

Glucosyltransferases of viridans group streptococci modulate interleukin-6 and adhesion molecule expression in endothelial cells and augment monocytic cell adherence

Recruitment of monocytes plays important roles during vegetation formation and endocardial inflammation in the pathogenesis of infective endocarditis (IE). Bacterial antigens or modulins can activate endothelial cells through the expression of cytokines or adhesion molecules and modulate the recruitment of leukocytes. We hypothesized that glucosyltransferases (GTFs), modulins of viridans group streptococci, may act directly to up-regulate the expression of adhesion molecules and also interleukin-6 (IL-6) to augment monocyte attachment to endothelial cells. Using primary cultured human umbilical vein endothelial cells (HUVECs) as an in vitro model, we demonstrated that GTFs (in the cell-bound or free form) could specifically modulate the expression of IL-6, and also adhesion molecules, in a dose- and time-dependent manner. Results of inhibition assays suggested that enhanced expression of adhesion molecules was dependent on the activation of nuclear factor kappaB (NF-kappaB) and extracellular signal-regulated kinase and that p38 mitogen-activated protein kinase pathways also contributed to the release of IL-6. Streptococcus-infected HUVECs or treatment with purified IL-6 plus soluble IL-6 receptor alpha enhanced the expression of ICAM-1 and the adherence of the monocytic cell line U937. These results suggest that streptococcal GTFs might play an important role in recruiting monocytic cells during inflammation in IE through induction of adhesion molecules and IL-6, a cytokine involved in transition from neutrophil to monocyte recruitment.

Levamisole can modulate the serum tumor necrosis factor-alpha level in patients with recurrent aphthous ulcerations

BACKGROUND

Recurrent aphthous ulcerations (RAU) are common oral inflammatory lesions. Tumor necrosis factor (TNF)-alpha is an important inflammatory mediator and a critical cytokine for adequate host defense. Our previous studies have shown that 14-43% and 59-63% of patients in the ulcerative stage of major, minor or herpetiform RAU have significantly higher than normal serum levels of interleukin (IL)-6 and IL-8, respectively. In this study, we examined whether RAU patients in the ulcerative stage had a significantly higher than normal serum level of TNF-alpha and assessed whether treatment with levamisole can modulate serum TNF-alpha levels in RAU patients.

METHODS

This study used a solid phase, two-site sequential chemiluminescent immunometric assay to determine the baseline serum levels of TNF-alpha in 146 patients with RAU, nine patients with traumatic ulcers (TU), and 54 normal control subjects. Fifty-five RAU patients with serum TNF-alpha levels higher than 5.0 pg/ml were treated with levamisole for 0.5-4 months and their serum TNF-alpha levels were measured after treatment.

RESULTS

We found that 29% (42 of 146) RAU patients as well as 39% (24 of 61) major type, 20% (14 of 69) minor type, and 25% (four of 16) herpetiform type RAU patients had a serum level of TNF-alpha greater than the upper normal limit of 7.4 pg/ml. The mean serum level of TNF-alpha in patients with RAU (9.1 +/- 1.0 pg/ml, P < 0.001), major type RAU (11.6 +/- 1.9 pg/ml, P < 0.001), minor type RAU (6.9 +/- 0.9 pg/ml, P < 0.005), or herpetiform type RAU (9.6 +/- 2.7 pg/ml, P < 0.001) was higher than that (3.8 +/- 0.2 pg/ml) in normal control subjects. The mean serum TNF-alpha level was significantly higher in patients with major type RAU than in patients with minor type RAU (P < 0.05) and was significantly higher in major type RAU patients in the exacerbation stage than in the post-exacerbation stage (P < 0.05). In 55 RAU patients with serum TNF-alpha levels higher than 5.0 pg/ml, treatment with levamisole for a period of 0.5-4 months could significantly reduce the serum TNF-alpha level from 16.4 +/- 1.9 to 5.8 +/- 0.6 pg/ml (P < 0.001).

CONCLUSIONS

We conclude that a significantly higher than normal serum level of TNF-alpha can be detected in 20-39% of patients in the ulcerative stage of major, minor or herpetiform RAU. The serum TNF-alpha level may be associated with the severity and the stage of RAU. Levamisole can modulate serum TNF-alpha levels in RAU patients.

Differential regulation of Streptococcus mutans gtfBCD genes in response to copper ions

To persist in the oral cavity, bacteria must be able to tolerate environmental fluctuation, particularly in pH, nutrients, and essential elements. Glucosyltransferases B, C, and D of Streptococcus mutans synthesize glucans, and play essential roles in the sucrose-dependent adhesion of the organism to tooth surfaces. Transcriptions of gtfB, gtfC, and gtfD could be differentially regulated through independent promoters. To test the hypothesis that environmental factors frequently encountered in the dental plaque might serve as effector molecules involved in regulation, transcripts of individual gtfs were identified by reverse transcriptase-polymerase chain reaction assay and confirmed by Northern blot analysis using anti-sense RNA probes. When S. mutans was grown in different medium at low pH, differential regulation of the gtfs was observed. More specifically, the transcription and translational expression of gtfD but not gtfB and gtfC was specifically induced by copper ion (Cu(2+)). The up-regulation was independent of the Cu(2+)-transport operon copYAZ. These findings support the involvement of Cu(2+) as an effector molecule in the regulation of S. mutans gtfD. Nutrient change dominates influence of pH but not the effect of Cu(2+).

Bactericidal effects of diode laser onStreptococcus mutans after irradiation through different thickness of dentin

BACKGROUND AND OBJECTIVES

A reliable method to eradicate the bacteria of residual carious dentin has not yet been developed. The aim of this study was to evaluate the antibacterial effect of a diode laser on Streptococcus mutans through different thickness (500, 1,000, and 2,000 microm) of human dentin. The thermal effect of laser irradiation was also investigated.

STUDY DESIGN/MATERIALS AND METHODS

Dentin specimens were inoculated with 2 microl of S. mutans on one side and irradiated by a diode laser on the other side with a power output ranging from 0.5 to 7 W. The laser tip was swept with the whole irradiation area of 7 mm x 3 mm at a speed of about 10 mm/second with a total irradiation time of 30 seconds. Cooling with distilled water (30 ml/minute) was applied simultaneously during laser irradiation. After laser irradiation, the bacteria was removed from the dentin surfaces and cultured for 48 hours at 37 degrees C anaerobically to assess the colony forming units (CFU) per ml. The morphology of the lased bacteria and the temperature rise during laser irradiation were observed by scanning electron microscope (SEM) and measured by thermocouple, respectively.

RESULTS

The results revealed that 7 W of laser power could kill 97.7% of CFU through 500 microm thickness of dentin. However, the bactericidal efficiency was significantly reduced as the dentin thickness was increased. The morphological changes of lased bacteria ranged from less affected such as loss of their wall bands and existence of minicells to more severely degenerated, such as disintegration and fusion of cells with pores on the cell wall. Only the dentin specimens with a thickness of 500 microm exhibited a temperature rise greater than 5.5 degrees C after receiving 5 or 7 W of laser irradiation.

CONCLUSIONS

A diode laser can eliminate the Streptococcus mutans of the residual carious dentin without inducing high pulpal temperature rise when the remaining dentin thickness is greater than 1 mm.

"Tien-Hsien liquid" can modulate antigen-stimulated cytokine production by T-cells isolated from patients with recurrent aphthous ulcerations

Recurrent aphthous ulcerations (RAU) represent a common oral mucosal disease with altered humoral and cellular immunities. Tien-Hsien liquid (THL) is an extract of Chinese medicinal herbs with immunomodulating effects. Our previous study found that THL can modulate the antigen-stimulated proliferative response of peripheral blood mononuclear cells and T-cells isolated from RAU patients. In this study, we further tested whether THL can modulate the antigen-stimulated cytokine production by T-cells isolated from RAU patients. To achieve this goal, T-cells isolated from 19 RAU patients were incubated with phytohemagglutinin (PHA), glutaraldehyde-inactivated tetanus toxoid (TT), glucosyltransferase D (GtfD), or antigens of Streptococcus mutans in the presence or absence of THL. The levels of interleukin (IL)-2, interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), IL-6, or IL-10 in the supernatants of T-cell cultures were measured by cytokine enzyme-linked immunosorbent assay (ELISA) kits. We found that THL significantly increased the PHA- or TT-stimulated TNF-alpha, IL-6, and IL-10 production by T-cells isolated from RAU patients. However, THL could also significantly decrease the TT-stimulated IL-2 production, the GtfD-stimulated IL-2, TNF-alpha, IL-6 and IL-10 production, and the S. mutans-stimulated IFN-gamma, TNF-alpha, and IL-10 production by T-cells isolated from RAU patients. These results indicate that THL can modulate the antigen-stimulated cytokine production by T-cells isolated from RAU patients. Because RAU is probably a Thl-mediated disease with elevated levels of IL-2, IFN-gamma, TNF-alpha and IL-6 in either the patient's sera or oral lesions and these increased levels of cytokines can be reduced by THL, we suggest that THL may be a potential immunoceutical agent for treatment of RAU.

The chinese herbal medicine Tien-Hsien liquid inhibits cell growth and induces apoptosis in a wide variety of human cancer cells

OBJECTIVE

Tien-Hsien liquid (THL) is a commercially available Chinese herbal mixture that has been used as an anticancer dietary supplement for more than 10 years. We recently showed that THL has strong immunomodulatory effects on peripheral blood mononuclear cells (PBMC) and T cells. To investigate the antitumor activity of THL further, we sought to test whether THL could induce apoptosis in various human cancer cell lines based on the fact that THL contains several components with tumor killing functions.

DESIGN

The growth inhibitory effect of THL on human cervical carcinoma C-33A cells, human lung carcinoma H1299 cells, and human PBMC was assessed by counting viable cells using the trypan blue dye exclusion method. The apoptosis-inducing activity of THL in H1299 cells was assessed by analyzing the cells with four assays: (1) Hoechst 33258 nuclear DNA staining; (2) the terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) assay; (3) the nucleosomal DNA fragment ladder assay; and (4) the sub-G1 cell analysis. The activities of caspase-8, -9, and -3 in H1299 cells treated with or without THL were also measured to elucidate the possible mechanism underlying THL apoptosis-inducing effect. Finally, the apoptotic effect of THL on fifteen human cancer cell lines and normal human cells were analyzed by the TUNEL assay.

RESULTS

THL could induce apoptosis in all human cancer cell lines tested but not in normal human cells. THL treatment of H1299 cancer cells resulted in activation of caspase-8, -9, and -3 and the inhibitors of these caspases could partially block THL-induced apoptosis.

CONCLUSIONS

THL has been used by numerous patients with cancer for many years with no known adverse effect. Our present study showing that THL had a broad-range tumor killing function has provided a molecular basis underlying THL therapeutic activity. Furthermore, because THL had apoptotic effects only on cancer cells but not on normal cells, this selectivity suggests that THL could be a potential cancer therapeutic agent.

Species identification of mutans streptococci by groESL gene sequence

The near full-length sequences of the groESL genes were determined and analysed among eight reference strains (serotypes a to h) representing five species of mutans group streptococci. The groES sequences from these reference strains revealed that there are two lengths (285 and 288 bp) in the five species. The intergenic spacer between groES and groEL appears to be a unique marker for species, with a variable size (ranging from 111 to 310 bp) and sequence. Phylogenetic analysis of groES and groEL separated the eight serotypes into two major clusters. Strains of serotypes b, c, e and f were highly related and had groES gene sequences of the same length, 288 bp, while strains of serotypes a, d, g and h were also closely related and their groES gene sequence lengths were 285 bp. The groESL sequences in clinical isolates of three serotypes of S. mutans were analysed for intraspecies polymorphism. The results showed that the groESL sequences could provide information for differentiation among species, but were unable to distinguish serotypes of the same species. Based on the determined sequences, a PCR assay was developed that could differentiate members of the mutans streptococci by amplicon size and provide an alternative way for distinguishing mutans streptococci from other viridans streptococci.

Glucosyltransferases of viridans streptococci are modulins of interleukin-6 induction in infective endocarditis

The glucosyltransferases (GTFs) of viridans streptococci, common pathogens of infective endocarditis, are extracellular proteins that convert sucrose into exopolysaccharides and glucans. GTFs B, C, and D of Streptococcus mutans are modulins that induce, in vitro and in vivo, the production of cytokines, in particular interleukin-6 (IL-6), from monocytes. The roles of S. mutans GTFs in infectivity and inflammation in situ were tested in a rat experimental model of endocarditis. No significant differences in infectivity, in terms of 95% infective dose and densities of bacteria inside vegetations, were observed between laboratory strain GS-5 and two clinical isolates or isogenic mutant NHS1DD, defective in the expression of GTFs. In aortic valves and surrounding tissues, IL-6 was detected by Western blots and immunostaining 24 h after GS-5 infection, was maintained over 72 h, and was followed by production of tumor necrosis factor alpha but not IL-1beta. Animals infected with NHS1DD showed markedly lower levels of IL-6 (less than 5% of that of parental GS-5-infected rats), while tumor necrosis factor alpha was unaffected. In contrast, animals infected with NHR1DD, another isogenic mutant expressing only GtfB, showed a much smaller reduction (down to 56%). These results suggest that GTFs are specific modulins that act during acute inflammation, inducing IL-6 from endothelial cells surrounding the infected valves without affecting bacterial colonization in vegetations, and that IL-6 might persist in chronic inflammation in endocarditis.

Serum interleukin-8 level is a more sensitive marker than serum interleukin-6 level in monitoring the disease activity of oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is a T-cell-mediated inflammatory disease. Interleukin (IL)-8 is a pro-inflammatory cytokine of host response to injury and inflammation.

OBJECTIVES

To investigate whether serum IL-8 level was a more sensitive marker than serum IL-6 level in monitoring the disease activity of OLP and to assess whether IL-8 was a useful serum marker in evaluating the therapeutic effects of levamisole on OLP patients.

METHODS

In this study, we used a solid phase, two-site sequential chemiluminescent immunometric assay to determine the baseline serum levels of IL-6 and IL-8 in 158 patients with OLP, nine patients with traumatic ulcers (TU) and 54 normal control subjects. Some OLP patients with the serum IL-6 or IL-8 levels higher than the upper limit of normal serum concentration were treated with levamisole for 0.5-6.0 months and their serum IL-6 and IL-8 levels were measured after treatment.

RESULTS

We found that 28% (44 of 158) OLP, 28% (40 of 142) erosive OLP (EOLP), and 25% (four of 16) nonerosive OLP (NEOLP) patients had a serum IL-6 level greater than the upper normal limit of 4.7 pg mL(-1). In contrast, 63% (99 of 158) OLP, 63% (90 of 142) EOLP and 56% (nine of 16) NEOLP patients had a serum IL-8 level greater than the upper normal limit of 8.7 pg mL(-1). In some OLP patients with the serum IL-6 or IL-8 levels higher than the upper limit of normal serum concentration, treatment with levamisole for a period of 0.5-6.0 months could significantly reduce the mean serum IL-6 level from 14.3 +/- 1.9 pg mL(-1) to 3.2 +/- 0.6 pg mL(-1) (P < 0.001) and could significantly reduce the mean serum IL-8 level from 95.8 +/- 17.1 pg mL(-1) to 14.8 +/- 5.8 pg mL(-1) (P < 0.001).

CONCLUSIONS

Because measurement of the serum IL-8 level can detect more OLP patients with an abnormal serum level than measurement of the serum IL-6 level (63% vs. 28%), we conclude that serum IL-8 level is a more sensitive marker than serum IL-6 level in monitoring the disease activity of OLP. Levamisole can modulate both the serum IL-6 and IL-8 levels in OLP patients. IL-8, like IL-6, is also a useful serum marker in evaluating the therapeutic effects of levamisole on OLP patients.

Immunomodulating effects of "tien-hsien liquid" on peripheral blood mononuclear cells and T-lymphocytes from patients with recurrent aphthous ulcerations

Recurrent aphthous ulcerations (RAU) represent a common oral mucosal disease with altered humoral and cellular immunities. In our institution, an immunomodulating agent, levamisole, is used to treat RAU with satisfactory therapeutic effect. Tien-Hsien liquid (THL) is an extract of Chinese medicinal herbs with immunomodulating effects. To test whether THL has immunomodulating effects on antigen-stimulated proliferation response (PR) of peripheral blood mononuclear cells (PBMC) and T-cells isolated from RAU patients and to test whether THL is a potential drug for treating RAU, PBMC or T-cells isolated from RAU patients were incubated with lipopolysaccharides (LPS) from Escherica coli, phytohemagglutinin (PHA), staphylococcal enterotoxin B (SEB), glutaraldehyde-inactivated tetanus toxoid (TT), glucosyltransferase D (GtfD), or antigens of Streptococcus mutans in the presence or absence of THL. We found that THL significantly increased the LPS-stimulated PR of PBMC from active RAU patients, the GtfD-stimulated PR of PBMC and of T-cells from inactive RAU patients, and the S. mutans-stimulated PR of PBMC from inactive RAU patients. However, THL could also significantly reduce the SEB-stimulated PR of PBMC and of T-cells from active RAU patients and S. mutans-stimulated PR of T-cells from active RAU patients. These results suggest that THL can modulate the antigen-stimulated PR of PBMC and T-cells from RAU patients. Therefore, it may be a potential immunoceutical agent for treatment of RAU.

Platelet aggregation induced by serotype polysaccharides from Streptococcus mutans

Platelet aggregation plays an important role in the pathogenesis of infective endocarditis induced by viridans streptococci or staphylococci. Aggregation induced in vitro involves direct binding of bacteria to platelets through multiple surface components. Using platelet aggregometry, we demonstrated in this study that two Streptococcus mutans laboratory strains, GS-5 and Xc, and two clinical isolates could aggregate platelets in an irreversible manner in rabbit platelet-rich plasma preparations. The aggregation was partially inhibited by prostaglandin I(2) (PGI(2)) in a dose-dependent manner. Whole bacteria and heated bacterial cell wall extracts were able to induce aggregation. Cell wall polysaccharides extracted from the wild-type Xc strain, containing serotype-specific polysaccharides which are composed of rhamnose-glucose polymers (RGPs), could induce platelet aggregation in the presence of plasma. Aggregation induced by the serotype-specific RGP-deficient mutant Xc24R was reduced by 50% compared to the wild-type strain Xc. In addition, cell wall polysaccharides extracted from Xc24R failed to induce platelet aggregation. The Xc strain, but not the Xc24R mutant, could induce platelet aggregation when preincubated with plasma. Both Xc and Xc24R failed to induce platelets to aggregate in plasma depleted of immunoglobulin G (IgG), but aggregation was restored by replenishment of anti-serotype c IgG. Analysis by flow cytometry showed that S. mutans RGPs could bind directly to rabbit and human platelets. Furthermore, cell wall polysaccharides extracted from the Xc, but not the Xc24R, strain could induce pseudopod formation of both rabbit and human platelets in the absence of plasma. Distinct from the aggregation of rabbit platelets, bacterium-triggered aggregation of human platelets required a prolonged lag phase and could be blocked completely by PGI(2). RGPs also trigger aggregation of human platelets in a donor-dependent manner, either as a transient and reversible or a complete and irreversible response. These results indicated that serotype-specific RGPs, a soluble product of S. mutans, could directly bind to and activate platelets from both rabbit and human. In the presence of plasma containing IgG specific to RGPs, RGPs could trigger aggregation of both human and rabbit platelets, but the degree of aggregation in human platelets depends on the donors.

Serum interleukin-8 level is a more sensitive marker than serum interleukin-6 level in monitoring the disease activity of recurrent aphthous ulcerations

BACKGROUND

Recurrent aphthous ulcerations (RAU) are common oral inflammatory lesions. Interleukin (IL)-8 is a pro-inflammatory cytokine of host response to injury and inflammation. Our recent study has found that measurement of serum IL-6 level can detect only 24% RAU patients with an abnormal serum level. In this study, we examined both the serum IL-6 and IL-8 levels in a group of RAU patients. The abilities of IL-6 and IL-8 to detect patients with an abnormal serum level were compared in order to find out whether IL-8 was a more sensitive serum marker than IL-6 in monitoring the disease activity of RAU.

METHODS

In this study, we used a solid-phase, two-site sequential chemiluminescent immunometric assay to determine the baseline serum levels of IL-6 and IL-8 in 146 patients with RAU, 9 patients with traumatic ulcers (TU), and 54 normal control (NC) subjects. Eighty-two RAU patients, with the serum IL-6 or IL-8 levels higher than the upper limit of normal serum concentration, were treated with levamisole for 0.5-3.5 months, and their serum IL-6 and IL-8 levels were measured after treatment.

RESULTS

We found that 25% (37/146) RAU patients, as well as 33% (20/61) major-type, 19% (13/69) minor-type, and 25% (4/16) herpetiform-type RAU patients, had a serum level of IL-6 greater than the upper normal limit of 4.7 pg/ml. In contrast, 60% (87/146) RAU patients, as well as 59% (36/61) major-type, 59% (41/69) minor-type, and 63% (10/16) herpetiform-type RAU patients, had a serum level of IL-8 greater than the upper normal limit of 8.7 pg/ml. In 82 RAU patients with the serum IL-6 or IL-8 levels higher than the upper limit of normal serum concentration, treatment with levamisole for a period of 0.5-3.5 months could significantly reduce the serum IL-6 level from 12.0 +/- 1.6 to 3.0 +/- 0.5 pg/ml (P < 0.001), and could significantly lower the serum IL-8 level from 70.9 +/- 11.2 to 13.8 +/- 3.1 pg/ml (P < 0.001).

CONCLUSIONS

Because measurement of serum IL-8 level can detect 60% RAU patients with an abnormal serum level, while measurement of serum IL-6 level can detect only 25% RAU patients with an abnormal serum level, we conclude that serum IL-8 level is a more sensitive marker than serum IL-6 level in monitoring the disease activity of RAU. Levamisole can modulate both the serum IL-6 and IL-8 levels in RAU patients. IL-8, like IL-6, is also a useful serum marker in evaluating therapeutic effects of levamisole on RAU patients.

Structural analysis of the functional influence of the surface peptide Gtf-P1 on Streptococcus mutans glucosyltransferase C activity

Glucosyltransferases (GtfB/C/D) in Streptococcus mutans are responsible for synthesizing water-insoluble and water-soluble glucans from sucrose and play very crucial roles in the formation of dental plaque. A monoclonal antibody against a 19-mer peptide fragment named Gtf-P1 was found in GtfC to reduce the enzyme activity to 50%. However, a similar experiment suggested almost unchanged activity in GtfD, despite of the very high sequence homology between the two enzymes. No further details are yet available to elucidate the biochemical mechanism responsible for such discrimination. For a better understanding of the catalytic behavior of these glucosyltransferases, structural and functional analyses were performed. First, the exact epitope was identified to specify the residue(s) required for monoclonal antibody recognition. The results suggest that the discrimination is determined solely by single residue substitution. Second, based on a combined sequence and secondary structure alignment against known crystal structure of segments from closely related proteins, a three-dimensional homology model for GtfC was built. Structural analysis for the region communicating between Gtf-P1 and the catalytic triad revealed the possibility for an "en bloc" movement of hydrophobic residues, which may transduce the functional influence on enzyme activity from the surface of molecule into the proximity of the active site. Figure Side chain interactions between Gtf-P1 and catalytic Asp-477 in GtfC. Calpha-tracing of GtfC with the two crucial peptides (Gtf-P1, orange; Gtf-P2, blue) and the catalytic triad residues ( red) highlighted to show their relative spatial organization. Side chains for the residues are also depicted according to their atom types. The structure is viewed with the barrel opening facing down