Neisseria gonorrhoeae Limits Chlamydia trachomatis Inclusion Development and Infectivity in a Novel In Vitro Co-Infection Model

Chlamydia trachomatis (Ct) and Neisseria gonorrhoeae (Ng) are the most common bacterial sexually transmitted infections (STIs) worldwide. The primary site of infection for both bacteria is the epithelium of the endocervix in women and the urethra in men; both can also infect the rectum, pharynx and conjunctiva. Ct/Ng co-infections are more common than expected by chance, suggesting Ct/Ng interactions increase susceptibility and/or transmissibility. To date, studies have largely focused on each pathogen individually and models exploring co-infection are limited. We aimed to determine if Ng co-infection influences chlamydial infection and development and we hypothesized that Ng-infected cells are more susceptible to chlamydial infection than uninfected cells. To address this hypothesis, we established an in vitro model of Ct/Ng co-infection in cultured human cervical epithelial cells. Our data show that Ng co-infection elicits an anti-chlamydial effect by reducing chlamydial infection, inclusion size, and subsequent infectivity. Notably, the anti-chlamydial effect is dependent on Ng viability but not extracellular nutrient depletion or pH modulation. Though this finding is not consistent with our hypothesis, it provides evidence that interaction of these bacteria in vitro influences chlamydial infection and development. This Ct/Ng co-infection model, established in an epithelial cell line, will facilitate further exploration into the pathogenic interplay between Ct and Ng.

Neuroprotective effects of some epigenetic modifying drugs' on Chlamydia pneumoniae-induced neuroinflammation: A novel model

Chlamydia pneumoniae (Cpn) is a gram-negative intracellular pathogen that causes a variety of pulmonary diseases, and there is growing evidence that it may play a role in Alzheimer's disease (AD) pathogenesis. Cpn can interact functionally with host histones, altering the host's epigenetic regulatory system by introducing bacterial products into the host tissue and inducing a persistent inflammatory response. Because Cpn is difficult to propagate, isolate, and detect, a modified LPS-like neuroinflammation model was established using lyophilized cell free supernatant (CFS) obtained from infected cell cultures, and the effects of CFS were compared to LPS. The neuroprotective effects of Trichostatin A (TSA), givinostat, and RG108, which are effective on epigenetic mechanisms, and the antibiotic rifampin, were studied in this newly introduced model and in the presence of amyloid beta (Aβ) 1-42. The neuroprotective effects of the drugs, as well as the effects of CFS and LPS, were evaluated in Aβ-induced neurotoxicity using a real-time cell analysis system, total ROS, and apoptotic impact. TSA, RG108, givinostat, and rifampin all demonstrated neuroprotective effects in both this novel model and Aβ-induced neurotoxicity. The findings are expected to provide early evidence on neuroprotective actions against Cpn-induced neuroinflammation and Aβ-induced neurotoxicity, which could represent a new treatment option for AD, for which there are currently few treatment options.

Inflammatory profile dysregulation in nuclear workers occupationally exposed to low-dose gamma radiation

Chronic inflammation is a common denominator linking a wide range of health conditions, including tissue response to radiation exposure. This pilot study investigates whether inflammatory cytokines-interleukins IL-6, -8, -10, monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor α (TNFα)-can be used as early biomarkers of radiation-induced adverse health effects in occupationally exposed individuals. The study included 33 workers externally exposed to gamma radiation from the nuclear industry with cumulated doses from 0.11 to 190 mSv and 42 non-exposed controls of comparable age and socio-economic status. IL-6, IL-8, MCP-1, TNFα and IL-10 were analyzed by enzyme-linked assay (ELISA) in blood plasma samples. Total antioxidant status (TAS) of blood plasma was determined by a colorimetric assay. The radiation-exposed and control groups measured significantly different levels of MCP-1, TNFα and IL-10. Seventy-five percent of radiation workers had either high MCP-1 levels or low IL-10 levels and 30% had all three cytokines dysregulated. Approximately 50% of workers showed upregulated antioxidant status, which appeared to compensate the pro-inflammatory cytokine shift in these individuals. In contrast, only 2% of the control subjects were found to have three dysregulated cytokines, and all of them measured within the normal TAS range. The present study may represent an important step towards the establishment of a reliable set of biomarkers for health-risk estimation in population cohorts exposed to low radiation doses.

Novosphingobium and its potential role in chronic obstructive pulmonary diseases: insights from microbiome studies

Bacterial infection of lung airways underlies some of the main complications of COPD, significantly impacting disease progression and outcome. Colonization by bacteria may further synergize, amplify, or trigger pathways of tissue damage started by cigarette smoke, contributing to the characteristic airway inflammation and alveolar destruction of COPD. We sought to elucidate the presence and types of lung bacterial populations in different stages of COPD, aimed at revealing important insights into the pathobiology of the disease. Sequencing of the bacterial small subunit ribosomal RNA gene in 55 well-characterized clinical lung samples, revealed the presence of Novosphingobium spp. (>2% abundance) in lungs of patients with GOLD 3-GOLD 4 COPD, cystic fibrosis and a subset of control individuals. Novosphingobium-specific quantitative PCR was concordant with the sequence data and high levels of Novosphingobium spp. were quantifiable in advanced COPD, but not from other disease stages. Using a mouse model of subacute lung injury due to inhalation of cigarette smoke, bronchoalveolar lavage neutrophil and macrophage counts were significantly higher in mice challenged intratracheally with N. panipatense compared to control mice (p<0.01). Frequencies of neutrophils and macrophages in lung tissue were increased in mice challenged with N. panipatense at room air compared to controls. However, we did not observe an interaction between N. panipatense and subacute cigarette smoke exposure in the mouse. In conclusion, Novosphingobium spp. are present in more severe COPD disease, and increase inflammation in a mouse model of smoke exposure.

A comparison of serum and sputum inflammatory mediator profiles in patients with asthma and COPD

OBJECTIVE

To investigate serum and sputum cytokine profiles in asthma and chronic obstructive pulmonary disorder (COPD).

METHODS

Clinical characteristics, blood and sputum samples were collected from asthma (n = 37) and COPD (n = 36) patients, and healthy subjects (n = 39). Cytokines were measured by enzyme-linked immunosorbent assay (ELISA) and inflammation antibody array; levels were analysed according to smoking status and presence of eosinophilia in the airways of COPD/asthma patients, and compared with those in healthy subjects.

RESULTS

ELISA revealed a significant difference in the expression of only a few cytokines in the COPD versus asthma groups, and in both patient groups compared with healthy subjects. The antibody array showed greater differentiation in inflammatory mediators. In the subphenotype analysis, the differential expression of cytokines was more significant between eosinophilic and noneosinophilic airway inflammation than between asthma and COPD, according to both the ELISA and antibody array. There was little difference in cytokine expression between smoking and nonsmoking subgroups.

CONCLUSIONS

Differential expression of inflammatory mediators is present between patients with COPD or asthma, and eosinophilic or noneosinophilic airway inflammation, and contributes to understanding the cytokine network of airway inflammation.

Intervertebral disc and macrophage interaction induces mechanical hyperalgesia and cytokine production in a herniated disc model in rats

OBJECTIVE

The expression of proinflammatory factors such as tumor necrosis factor α (TNFα), interleukin-6 (IL-6), IL-8, and prostaglandin E(2) (PGE(2) ) is significantly correlated with the symptoms of herniated disc disease. Among the different types of immune cells, macrophages are frequently noted in the herniated disc tissue. We undertook this study to clarify the interaction of the intervertebral disc (IVD) and macrophages with regard to the production of TNFα, IL-6, IL-8, and PGE(2) .

METHODS

We developed 2 animal models to assess the interactions of IVDs with macrophages in terms of TNFα, IL-6, IL-8, and PGE(2) production and pain-related behavior. We also cocultured IVDs and macrophages to assess the role of TNFα in IL-6, IL-8, and PGE(2) production.

RESULTS

IVD autografts induced TNFα, IL-6, IL-8, and cyclooxygenase 2 (COX-2) messenger RNA (mRNA) up-regulation; macrophage infiltration was seen shortly after the autograft was implanted. A significant decrease was noted in the mechanical threshold of the ipsilateral paw following the up-regulation of TNFα, IL-6, IL-8, and COX-2 mRNA. Only IVD and macrophage cocultures resulted in IL-8 and PGE(2) up-regulation. TNFα up-regulation was maximized before that of IL-6 and IL-8. TNFα neutralization attenuated production of IL-6 and PGE(2) , but not that of IL-8. Neutralization of TNFα and IL-8 significantly increased the paw withdrawal mechanical threshold in the IVD autograft and spinal nerve ligation model.

CONCLUSION

IVD-macrophage interaction plays a major role in sciatica and in the production of TNFα, IL-6, IL-8, and PGE(2) . TNFα is required for IL-6 and PGE(2) production, but not for IL-8 production, during IVD-macrophage interaction. Neutralization of TNFα and IL-8 can be a valuable therapy for herniated disc disease.

Construction and characterization of a derivative of Neisseria gonorrhoeae strain MS11 devoid of all opa genes

To better understand the role of Opa in gonococcal infections, we created and characterized a derivative of MS11 (MS11Δopa) that had the coding sequence for all 11 Opa proteins deleted. The MS11Δopa bacterium lost the ability to bind to purified lipooligosaccharide (LOS). While nonpiliated MS11Δopa and nonpiliated Opa-expressing MS11 cells grew at the same rate, nonpiliated MS11Δopa cells rarely formed clumps of more than four bacteria when grown in broth with vigorous shaking. Using flow cytometry analysis, we demonstrated that MS11Δopa produced a homogeneous population of bacteria that failed to bind monoclonal antibody (MAb) 4B12, a MAb specific for Opa. Opa-expressing MS11 cells consisted of two predominant populations, where ∼85% bound MAb 4B12 to a significant level and the other population bound little if any MAb. Approximately 90% of bacteria isolated from a phenotypically Opa-negative colony (a colony that does not refract light) failed to bind MAb 4B12; the remaining 10% bound MAb to various degrees. Piliated MS11Δopa cells formed dispersed microcolonies on ME180 cells which were visually distinct from those of piliated Opa-expressing MS11 cells. When Opa expression was reintroduced into MS11Δopa, the adherence ability of the strain recovered to wild-type levels. These data indicate that Opa contributes to both bacterium-bacterium and bacterium-host cell interactions.

Antiinflammatory role of MUC1 mucin during infection with nontypeable Haemophilus influenzae

MUC1 (or Muc1 in nonhuman species) is a membrane-tethered mucin expressed on the apical surface of mucosal epithelia (including those of the airways) that suppresses Toll-like receptor (TLR) signaling. We sought to determine whether the anti-inflammatory effect of MUC1 is operative during infection with nontypeable Haemophilus influenzae (NTHi), and if so, which TLR pathway was affected. Our results showed that: (1) a lysate of NTHi increased the early release of IL-8 and later production of MUC1 protein by A549 cells in dose-dependent and time-dependent manners, compared with vehicle control; (2) both effects were attenuated after transfection of the cells with a TLR2-targeting small interfering (si) RNA, compared with a control siRNA; (3) the NTHi-induced release of IL-8 was suppressed by an overexpression of MUC1, and was enhanced by the knockdown of MUC1; (4) the TNF-α released after treatment with NTHi was sufficient to up-regulate MUC1, which was completely inhibited by pretreatment with a soluble TNF-α receptor; and (5) primary murine tracheal surface epithelial (MTSE) cells from Muc1 knockout mice exhibited an increased in vitro production of NTHi-stimulated keratinocyte chemoattractant compared with MTSE cells from Muc1-expressing animals. These results suggest a hypothetical feedback loop model whereby NTHi activates TLRs (mainly TLR2) in airway epithelial cells, leading to the increased production of TNF-α and IL-8, which subsequently up-regulate the expression of MUC1, resulting in suppressed TLR signaling and decreased production of IL-8. This report is the first, to the best of our knowledge, demonstrating that the inflammatory response in airway epithelial cells during infection with NTHi is controlled by MUC1 mucin, mainly through the suppression of TLR2 signaling.

The hemorrhagic coli pilus (HCP) of Escherichia coli O157:H7 is an inducer of proinflammatory cytokine secretion in intestinal epithelial cells

Background

Enterohemorrhagic Escherichia coli (EHEC) O157:H7, the causative agent of hemorrhagic colitis and the hemolytic uremic syndrome (HUS), produces long bundles of type IV pili (TFP) called hemorrhagic coli pili (HCP). HCP are capable of mediating several phenomena associated with pathogenicity: i) adherence to human and bovine epithelial cells; ii) invasion of epithelial cells; iii) hemagglutination of rabbit erythrocytes; iv) biofilm formation; v) twitching motility; and vi) specific binding to laminin and fibronectin. HCP are composed of a 19 kDa pilin subunit (HcpA) encoded by the hcpA chromosomal gene (called prepilin peptidase-dependent gene [ppdD] in E. coli K-12).

Methodology/Principal Findings

In this study we investigated the potential role of HCP of E. coli O157:H7 strain EDL933 in activating the release of pro- and anti-inflammatory cytokines from a variety of host epithelial cells. We found that purified HCP and a recombinant HcpA protein induced significant release of IL-8 and TNF-α, from cultured polarized intestinal cells (T84 and HT-29 cells) and non-intestinal HeLa cells. Levels of proinflammatory IL-8 and TNF-α, but not IL-2, IL6, or IL-10 cytokines, were increased in the presence of HCP and recombinant HcpA after 6 h of incubation with ≥50 ng/ml of protein, suggesting that stimulation of IL-8 and TNF-α are dose and time-dependent. In addition, we also demonstrated that flagella are potent inducers of cytokine production. Furthermore, MAPK activation kinetics studies showed that EHEC induces p38 phosphorylation under HCP-producing conditions, and ERK1/2 and JNK activation was detectable after 3 h of EHEC infection. HT-29 cells were stimulated with epidermal growth factor stimulation of HT-29 cells for 30 min leading to activation of three MAPKs.

Conclusions/Significance

The HcpA pilin monomer of the HCP produced by EHEC O157:H7 is a potent inducer of IL-8 and TNF-α release, an event which could play a significant role in the pathogenesis of hemorrhagic colitis caused by this pathogen.

Mouse strain-dependent differences in susceptibility to Neisseria gonorrhoeae infection and induction of innate immune responses

Acute gonorrhea in women is characterized by a mucopurulent exudate that contains polymorphonuclear leukocytes (PMNs) with intracellular gonococci. Asymptomatic infections are also common. Information on the innate response to Neisseria gonorrhoeae in women is limited to studies with cultured cells, isolated immune cells, and analyses of cervicovaginal fluids. 17beta-Estradiol-treated BALB/c mice can be experimentally infected with N. gonorrhoeae, and a vaginal PMN influx occurs in 50 to 80% of mice. Here, we compared the colonization loads and proinflammatory responses of BALB/c, C57BL/6 and C3H/HeN mice to N. gonorrhoeae. BALB/c and C57BL/6 mice were colonized at similar levels following inoculation with 10(6) CFU of N. gonorrhoeae. BALB/c, but not C57BL/6, mice exhibited a marked vaginal PMN influx. Tumor necrosis factor alpha, interleukin-6, macrophage inflammatory protein 2 (MIP-2), and keratinocyte-derived chemokine were elevated in vaginal secretions from infected BALB/c mice, but not in those from C57BL/6 mice. MIP-2 levels positively correlated with a vaginal PMN influx. In contrast to BALB/c and C57BL/6 mice, C3H/HeN mice were resistant to infection, and there was no evidence of an inflammatory response. We conclude that N. gonorrhoeae causes a productive infection in BALB/c mice that is characterized by the induction of proinflammatory cytokines and chemokines and the recruitment of PMNs. Infection of C57BL/6 mice, in contrast, is more similar to asymptomatic infection. C3H/HeN mice are inherently resistant to N. gonorrhoeae infection, and this resistance is not due to an overwhelming inflammatory response to infection. Host genetic factors can therefore impact susceptibility and the immune response to N. gonorrhoeae.

IL1B promoter polymorphism regulates the expression of gastric acid stimulating hormone gastrin

It is important to dissect the effect of the alternative alleles of a functional SNP on the entire biochemical pathway for the complete understanding of the mechanism of the manifestation of complex diseases. IL1B-511C>T and -31C>T promoter polymorphisms have been suggested as potential susceptibility loci for Helicobacter pylori associated gastroduodenal diseases. We report that altered expression of IL1B due to a specific polymorphism in its promoter modulates the expression of gastrin, an acid regulating hormone. Treatment of gastric carcinoma cells, AGS, with IL1B resulted in a 20-fold reduction in gastrin expression. Gastrin promoter assay showed that IL1B inhibits gastrin expression at the transcriptional level and part of this inhibitory process is mediated via activation of NFkappaB and involvement of HDACs. An almost 3-fold increase in IL1B expression was observed when AGS cells were transfected with -31TIL1B expression plasmid in comparison to -31CIL1B. The -31TIL1B induced a 2-fold greater repression of the gastrin luciferase activity compared to -31CIL1B. This signaling of the -31TIL1B variant allele driven IL1B revealed an almost 1.5-fold greater expression of NFkappaB. Thus, this study showed that a single base substitution at the -31 position of the IL1B promoter brought about differential expression of IL1B which differentially altered both NFkappaB activation and gastrin expression.

Quantification of bacterial internalization by host cells using a beta-lactamase reporter strain: Neisseria gonorrhoeae invasion into cervical epithelial cells requires bacterial viability

Neisseria gonorrhoeae can invade into cervical epithelial cells to overcome this host defense barrier. We developed a beta-lactamase reporter system that allowed us to quantify at the single cell level if a host cell internalized a viable or nonviable microorganism. We autodisplayed beta-lactamase on the surface of FA1090 [FA1090Phi(bla-iga')] and demonstrated by confocal fluorescence microscopy and flow cytometry that FA1090Phi(bla-iga') cleaved the beta-lactamase substrate CCF2-AM loaded into host cells only when gonococci were internalized by these host cells. While FA1090Phi(bla-iga') adhered to almost all ME180 cells, viable N. gonorrhoeae were internalized by only a subset of cells during infection. Nonviable gonococci adhered to, but were not internalized by ME180 cells, and failed to recruit F-actin to sites of adherent bacteria. Overall, we show that epithelial cell invasion is a dynamic process that requires viable N. gonorrhoeae. We demonstrate the advantages of the beta-lactamase reporter system over the gentamicin protection assay in quantifying bacterial invasion. The reporter system that we have developed can be adapted to studying the internalization of any bacterial species into any host cell.

Effect of gonococcal lipooligosaccharide variation on human monocytic cytokine profile

Background

Neisseria gonorrhoeae is an obligate human pathogen that causes significant worldwide morbidity. N. gonorrhoeae expresses lipooligosaccharide (LOS), a phase variable molecule that plays an important role during pathogenesis of the organism. Alteration in the structure of gonococcal LOS correlates with altered disease presentation. In addition, LOS sialylation occurs readily in vivo, though the role of this sialylation during disease is unknown.

Results

Challenge of human monocytes with purified LOS preparations isolated from strains expressing distinct structurally defined LOSs resulted in identical production of the proinflammatory cytokines tumor necrosis factor alpha (TNFα) and interleukin-12 (IL-12). Similar results were seen when monocytes were challenged with either live or gentamicin-killed whole cell gonococcal variants expressing these LOS structures, although greater cytokine production was observed in comparison with challenge by purified LOS. Challenge of a human primary monocyte model with distinct LOS variants resulted in similar production of TNFα, IL-12, interleukin-10 (IL-10), and interleukin-8 (IL-8). A cytokine array was employed to allow measurement of a broad range of cytokines in samples challenge with gonococcal LOS variants as well as variants expressing sialylated LOS. Challenge of primary monocytes with sialylated gonococci was shown to elicit the production of more MCP-2 (monocyte chemoattractant protein-2) in comparison with challenge by unsialylated gonococci.

Conclusion

We demonstrated that while alterations in the carbohydrate moiety of LOS do not impact the production of most cytokines by human monocytes, whole-cell bacterial challenge is more stimulatory than challenge with purified LOS, implying that other gonococcal cell surface antigens are important for the elicitation of cytokines. Challenge with gonococci expressing sialylated LOS resulted in elicitation of more of the chemokine MCP-2 from challenged cells in comparison with gonococci expressing unsialylated LOS. As MCP-2 is an important chemoattractant, this indicates that in vivo sialylation may play an important role during the pathogenesis of N. gonorrhoeae.