The intracellular life of chlamydiae

Chlamydia trachomatis relies on the scavenger role of aryl hydrocarbon receptor with detyrosinated tubulin for its intracellular growth, but this is impaired by excess indole

Although IFN-γ depletes tryptophan (Trp) as a defense against intracellular Chlamydia trachomatis (Ct) infected to hypoxic vagina, the presence of indole, a precursor of Trp, enables Ct to infect IFN-γ-exposed culture cells. Meanwhile, Trp-derived indole derivatives interact the aryl hydrocarbon receptor (AhR), which is a ligand-dependent transcription factor involved in the cellular homeostasis with tubulin dynamics. Here, the amounts of IFN-γ and indole in cervical swabs with known Ct infection status were measured, and Ct growth in the presence of indole was determined from the perspective of the AhR axis under hypoxia. A positive correlation between the amounts of IFN-γ and indole was found, and both of these amounts were lower in Ct-positive swabs than in Ct-negative ones. Indole as well as other AhR ligands inhibited Ct growth, especially under normoxia. Ct prompted the expression of detyrosinated tubulin (dTTub), but indole inhibited it. Indole did not stimulate the translocation of AhR to nucleus, and it blocked AhR activation in AhR-reporter cells. Ct growth was reduced more effectively under normoxia in AhR-knockdown cells, an effect that was enhanced by indole, which in turn diminished dTTub. Thus, Ct growth relies on the scavenger role of cytosolic AhR responsible for promoting dTTub expression.

Cytokine profiling of samples positive for Chlamydia trachomatis and Human papillomavirus

Persistent human papillomavirus (HPV) infection is closely associated with cervical carcinoma. Co-infection in the endocervical environment with other microorganisms, such as Chlamydia trachomatis, may increase the risk of HPV infection and neoplastic progression. While in some individuals, Chlamydia trachomatis infection is resolved with the activation of Th1/IFN-γ-mediated immune response, others develop a chronic infection marked by Th2-mediated immune response, resulting in intracellular persistence of the bacterium and increasing the risk of HPV infection. This work aimed to quantify cytokines of the Th1/Th2/Th17 profile in exfoliated cervix cells (ECC) and peripheral blood (PB) of patients positive for Chlamydia trachomatis DNA, patients positive for Papillomavirus DNA, and healthy patients. Cytokine levels were quantified by flow cytometry in ECC and PB samples from patients positive for C. trachomatis DNA (n = 18), patients positive for HPV DNA (n = 30), and healthy patients (n = 17) treated at the Hospital de Amor, Campo Grande-MS. After analysis, a higher concentration of IL-17, IL-6, and IL-4 (p <0.05) in ECC; INF-γ and IL-10 (p <0.05) in PB was found in samples from patients positive for C. trachomatis DNA compared to samples from healthy patients. When comparing samples from patients positive for HPV DNA, there was a higher concentration of cytokines IL-17, IL-10, IL-6, and IL-4 (p <0.05) in ECC and IL-4 and IL-2 (p <0.05) in PB of patients positive for C. trachomatis DNA. These results suggest that induction of Th2- and Th17 mediated immune response occurs in patients positive for C. trachomatis DNA, indicating chronic infection. Our results also demonstrate a high concentration of pro-inflammatory cytokines in ECC of patients positive for C. trachomatis DNA.

Alternative strategies for Chlamydia treatment: Promising non-antibiotic approaches

Chlamydia is an obligate intracellular bacterium where most species are pathogenic and infectious, causing various infectious diseases and complications in humans and animals. Antibiotics are often recommended for the clinical treatment of chlamydial infections. However, extensive research has shown that antibiotics may not be sufficient to eliminate or inhibit infection entirely and have some potential risks, including antibiotic resistance. The impact of chlamydial infection and antibiotic misuse should not be underestimated in public health. This study explores the possibility of new therapeutic techniques, including a review of recent studies on preventing and suppressing chlamydial infection by non-antibiotic compounds.

Cardiovascular Diseases and Pharmacomicrobiomics: A Perspective on Possible Treatment Relevance

Cardiovascular diseases (CVDs), the most common cause of mortality in rich countries, include a wide variety of pathologies of the heart muscle and vascular system that compromise the proper functioning of the heart. Most of the risk factors for cardiovascular diseases are well-known: lipid disorders, high serum LDL cholesterol, hypertension, smoking, obesity, diabetes, male sex and physical inactivity. Currently, much evidence shows that: (i) the human microbiota plays a crucial role in maintaining the organism’s healthy status; and (ii) a link exists between microbiota and cardiovascular function that, if dysregulated, could potentially correlate with CVDs. This scenario led the scientific community to carefully analyze the role of the microbiota in response to drugs, considering this the right path to improve the effectiveness of disease treatment. In this review, we examine heart diseases and highlight how the microbiota actually plays a preponderant role in their development. Finally, we investigate pharmacomicrobiomics—a new interesting field—and the microbiota’s role in modulating the response to drugs, to improve their effectiveness by making their action targeted, focusing particular attention on cardiovascular diseases and on innovative potential treatments.

Pelvic inflammatory disease in the adolescent and young adult: An update

Pelvic inflammatory disease (PID) is an infection of the female upper genital tract that is typically polymicrobial with classic core involvement of Neisseria gonorrhoeae and/or Chlamydia trachomatis, though other endogenous flora from the vagino-cervical areas can be involved as well. It is often a sexually transmitted disease but other etiologic routes are also noted. A variety of risk factors have been identified including adolescence, young adulthood, adolescent cervical ectropion, multiple sexual partners, immature immune system, history of previous PID, risky contraceptive practices and others. An early diagnosis and prompt treatment are necessary to reduce risks of PID complications such as chronic pelvic pain, ectopic pregnancy and infertility. Current management principles of PID are also reviewed. It is important for clinicians to screen sexually active females for common sexually transmitted infections such as Chlamydia trachomatis and provide safer sex education to their adolescent and young adult patients. Clinicians should provide comprehensive management to persons with PID and utilize established guidelines such as those from the US Centers for Disease Control and Prevention (CDC).

Assessment of evidence for or against contributions of Chlamydia pneumoniae infections to Alzheimer's disease etiology

Alzheimer's disease, the most common form of dementia, was first formally described in 1907 yet its etiology has remained elusive. Recent proposals that Aβ peptide may be part of the brain immune response have revived longstanding contention about the possibility of causal relationships between brain pathogens and Alzheimer's disease. Research has focused on infectious pathogens that may colonize the brain such as herpes simplex type I. Some researchers have proposed the respiratory bacteria Chlamydia pneumoniae may also be implicated in Alzheimer's disease, however this remains controversial. This review aims to provide a balanced overview of the current evidence and its limitations and future approaches that may resolve controversies. We discuss the evidence from in vitro, animal and human studies proposed to implicate Chlamydia pneumoniae in Alzheimer's disease and other neurological conditions, the potential mechanisms by which the bacterium may contribute to pathogenesis and limitations of previous studies that may explain the inconsistencies in the literature.

Combined Human Genome-wide RNAi and Metabolite Analyses Identify IMPDH as a Host-Directed Target against Chlamydia Infection

Chlamydia trachomatis (Ctr) accounts for >130 million human infections annually. Since chronic Ctr infections are extremely difficult to treat, there is an urgent need for more effective therapeutics. As an obligate intracellular bacterium, Ctr strictly depends on the functional contribution of the host cell. Here, we combined a human genome-wide RNA interference screen with metabolic profiling to obtain detailed understanding of changes in the infected cell and identify druggable pathways essential for Ctr growth. We demonstrate that Ctr shifts the host metabolism toward aerobic glycolysis, consistent with increased biomass requirement. We identify key regulator complexes of glucose and nucleotide metabolism that govern Ctr infection processes. Pharmacological targeting of inosine-5'-monophosphate dehydrogenase (IMPDH), the rate-limiting enzyme in guanine nucleotide biosynthesis, efficiently inhibits Ctr growth both in vitro and in vivo. These results highlight the potency of genome-scale functional screening for the discovery of drug targets against bacterial infections.

Resveratrol Inhibits Propagation of Chlamydia trachomatis in McCoy Cells

Resveratrol (RESV), an antifungal compound from grapes and other plants, has a distinct ability to inhibit the Chlamydia (C.) trachomatis developmental cycle in McCoy cells, a classic cell line used for chlamydial research. Inoculation of C. trachomatis with increasing amounts of RESV (from 12.5 to 100 μM) gave a dose-dependent reduction in the number of infected McCoy cells visualized by using monoclonal antibodies against chlamydial lipopolysaccharide. A similar trend has been observed with immunoassay for major outer membrane protein (MOMP). Furthermore, there was a step-wise reduction in the number of C. trachomatis infective progenies caused by the increasing concentrations of RESV. The ability of RESV to arrest C. trachomatis growth in McCoy cells was confirmed by a nucleic acid amplification protocol which revealed dose-dependent changes in mRNAs for different genes of chlamydial developmental cycle (euo, incA, and omcB). Although the precise nature of the antichlamydial activity of RESV is yet to be determined and evaluated in future studies, the observed effect of RESV on C. trachomatis infection was not related to its potential effect on attachment/entry of the pathogen into eukaryotic cells or RESV toxicity to McCoy cells. Similar inhibitory effect was shown for C. pneumoniae and C. muridarum.

Dynamic energy dependency of Chlamydia trachomatis on host cell metabolism during intracellular growth: Role of sodium-based energetics in chlamydial ATP generation

Chlamydia trachomatis is an obligate intracellular human pathogen responsible for the most prevalent sexually-transmitted infection in the world. For decades C. trachomatis has been considered an "energy parasite" that relies entirely on the uptake of ATP from the host cell. The genomic data suggest that C. trachomatis respiratory chain could produce a sodium gradient that may sustain the energetic demands required for its rapid multiplication. However, this mechanism awaits experimental confirmation. Moreover, the relationship of chlamydiae with the host cell, in particular its energy dependence, is not well understood. In this work, we are showing that C. trachomatis has an active respiratory metabolism that seems to be coupled to the sodium-dependent synthesis of ATP. Moreover, our results show that the inhibition of mitochondrial ATP synthesis at an early stage decreases the rate of infection and the chlamydial inclusion size. In contrast, the inhibition of the chlamydial respiratory chain at mid-stage of the infection cycle decreases the inclusion size but has no effect on infection rate. Remarkably, the addition of monensin, a Na⁺/H⁺ exchanger, completely halts the infection. Altogether, our data indicate that chlamydial development has a dynamic relationship with the mitochondrial metabolism of the host, in which the bacterium mostly depends on host ATP synthesis at an early stage, and at later stages it can sustain its own energy needs through the formation of a sodium gradient.

Effect of Different Antibiotic Chemotherapies on Pseudomonas aeruginosa Infection In Vitro of Primary Human Corneal Fibroblast Cells

Pseudomonas aeruginosa is a major cause of bacterial keratitis (BK) worldwide. Inappropriate or non-optimal antibiotic chemotherapy can lead to corneal perforation and rapid sight loss. In this study, we tested the hypothesis that P. aeruginosa strain PAO1 invades primary human corneal fibroblasts (hCFs) in vitro and persists intracellularly, despite chemotherapy with antibiotics used commonly to treat BK. In rank order, ciprofloxacin, levofloxacin and polymyxin B showed the highest activity against planktonic PAO1 growth (100% inhibitory concentration ≤10 μg/mL; 50% inhibitory concentration ≤1 μg/mL), followed by gentamicin and ofloxacin (100% inhibitory concentration ≤50 μg/mL; 50% inhibitory concentration ≤10 μg/mL). These bactericidal antibiotics (50–200 μg/mL concentrations) all killed PAO1 in the extracellular environment of infected hCF monolayers. By contrast, the bactericidal antibiotic cefuroxime and the bacteriostatic antibiotic chloramphenicol failed to sterilize both PAO1 broth cultures, even at a concentration of ≥200 μg/mL) and infected hCF monolayers. Statistically, all antibiotics were able to prevent LDH release from PAO1-infected hCF monolayers at both concentrations tested. Intracellular Pseudomonas were significantly reduced (>99%, P < 0.05) following treatment with ciprofloxacin, levofloxacin and ofloxacin, whereas gentamicin, polymyxin B and cefuroxime failed to clear intracellular bacteria over 24 h. Intracellular Pseudomonas infection was resistant to chloramphenicol, with hCF death observed by 9 h. Eventual growth of remaining intracellular Pseudomonas was observed in hCF after removal of all antibiotics, resulting in re-infection cycles and cell death by 48 h. All of the antibiotics reduced significantly (P < 0.05) IL-1β secretion by hCF infected with a Multiplicity Of Infection (MOI) = 1 of PAO1. With higher MOI, no pro-inflammatory effects were observed with antibiotic treatment, expect with polymyxin B and ofloxacin, which induced significant increased IL-1β secretion (P < 0.001). The findings from our study demonstrated that bactericidal and bacteriostatic antibiotics, routinely used to treat BK, failed to eradicate Pseudomonas infection of hCFs in vitro and that their bactericidal efficacies were influenced by the cellular location of the organism.

Chlamydia pecorum: successful pathogen of koalas or Australian livestock?

In Australia, the obligate intracellular bacterium Chlamydia pecorum is best known as the notorious koala pathogen that causes debilitating ocular and urogenital tract disease. While globally published data suggests that this species is essentially ubiquitous in livestock, little is known about the epidemiology of livestock C. pecorum infections here in Australia. My research is focused on investigating the genetic diversity and transmission patterns of C. pecorum, and why it causes disease. Using our newly developed C. pecorum-specific molecular epidemiology typing scheme we provided the first epidemiological data on infections in sheep and cattle in Australia, identifying strains associated with a range of diseases in livestock, and uncovering an unexpected level of diversity for this pathogen. Most importantly, we observed that the same strain can infect koala and sheep, indicating on ongoing cross-host transmission and ‘spill-over' risks to wildlife. Further, by dissecting koala, sheep, cattle and pig C. pecorum strains genomes, we have also identified novel virulence-associated factors that could be explored as vaccine candidates for both livestock and koala infections.

Impact of micro-environmental changes on respiratory tract infections with intracellular bacteria

Community-acquired pneumonia is caused by intra- and extracellular bacteria, with some of these bacteria also being linked to the pathogenesis of chronic lung diseases, including asthma and chronic obstructive pulmonary disease. Chlamydia pneumoniae is an obligate intracellular pathogen that is highly sensitive to micro-environmental conditions controlling both pathogen growth and host immune responses. The availability of nutrients, as well as changes in oxygen, pH and interferon-γ levels, have been shown to directly influence the chlamydial life cycle and clearance. Although the lung has been traditionally regarded as a sterile environment, sequencing approaches have enabled the identification of a large number of bacteria in healthy and diseased lungs. The influence of the lung microbiota on respiratory infections has not been extensively studied so far and data on chlamydial infections are currently unavailable. In the present study, we speculate on how lung microbiota might interfere with acute and chronic infections by focusing exemplarily on the obligate intracellular C. pneumoniae. Furthermore, we consider changes in the gut microbiota as an additional player in the control of lung infections, especially in view the increasing evidence suggesting the involvement of the gut microbiota in various immunological processes throughout the human body.

Chlamydia prevalence in Polish pig herds

Chlamydiae are frequently encountered intracellular Gram-negative bacteria. In pigs, these bacteria in combination with other pathogens contribute to the induction of a multi-aetiological syndrome. One of the major characteristics of Chlamydia spp. is their ability to cause prolonged, often subclinical infections. While the economic consequences of Chlamydia spp. infections in pig farms are not fully established, we know that reproductive disorders and other syndromes correlated with Chlamydia infection can lead to financial loss as a result of a reduction in pork production. Additionally, Chlamydia spp. presents a potential zoonotic hazard, therefore determining the prevalence of Chlamydia in pig populations is critical. In the present study 97 pig herds from Poland were involved. To determine the prevalence of Chlamydia PCR and CFT tests were used. In total 797 vaginal samples, 797 conjunctival samples, and 235 serum samples were collected and tested. The study took place from 2011 to 2014. We found Chlamydia spp. present in 71·2% of all tested farms. The percentage of animals testing positive on any given farm varied from 20% to 100%.

Differential influence of nutrient-starved Mycobacterium tuberculosis on adaptive immunity results in progressive tuberculosis disease and pathology

When infected with Mycobacterium tuberculosis, most individuals will remain clinically healthy but latently infected. Latent infection has been proposed to partially involve M. tuberculosis in a nonreplicating stage, which therefore represents an M. tuberculosis phenotype that the immune system most likely will encounter during latency. It is therefore relevant to examine how this particular nonreplicating form of M. tuberculosis interacts with the host immune system. To study this, we first induced a state of nonreplication through prolonged nutrient starvation of M. tuberculosis in vitro. This resulted in nonreplicating persistence even after prolonged culture in phosphate-buffered saline. Infection with either exponentially growing M. tuberculosis or nutrient-starved M. tuberculosis resulted in similar lung CFU levels in the first phase of the infection. However, between week 3 and 6 postinfection, there was a very pronounced increase in bacterial levels and associated lung pathology in nutrient-starved-M. tuberculosis-infected mice. This was associated with a shift from CD4 T cells that coexpressed gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α) or IFN-γ, TNF-α, and interleukin-2 to T cells that only expressed IFN-γ. Thus, nonreplicating M. tuberculosis induced through nutrient starvation promotes a bacterial form that is genetically identical to exponentially growing M. tuberculosis yet characterized by a differential impact on the immune system that may be involved in undermining host antimycobacterial immunity and facilitate increased pathology and transmission.

Mycoplasma pneumoniaeandChlamydophila pneumoniae: a comparative study in patients with nasal polyposis and healthy controls

Introduction:

The role played byMycoplasma pneumoniaeandChlamydophila pneumoniaein the pathogenesis of chronic rhinosinusitis with nasal polyps has been the object of ongoing debate. We used real-time polymerase chain reaction to investigate the prevalence of both microorganisms in the nasal tissue samples of patients and controls.

Methods:

We extracted DNA from nasal polyp samples obtained during functional endoscopic sinus surgery and the inferior turbinate samples of controls undergoing septoplasty. We used the highly sensitive real-time polymerase chain reaction to detect the presence ofM pneumoniaeandC pneumoniaeDNA.

Results:

Patients with chronic rhinosinusitis with nasal polyps consisted of 62 individuals (39 men; mean age 51 years); the control group consisted of 24 individuals (13 men; mean age 45 years). All samples from both groups were negative forM pneumoniaeandC pneumoniaeDNA.

Conclusion:

We have demonstrated that the likelihood ofM pneumoniaeandC pneumoniaeacting as an ongoing inflammatory stimulus in chronic rhinosinusitis with nasal polyps is slim.

Inhibitory activity of the isoflavone biochanin A on intracellular bacteria of genus Chlamydia and initial development of a buccal formulation

Given the established role of Chlamydia spp. as causative agents of both acute and chronic diseases, search for new antimicrobial agents against these intracellular bacteria is required to promote human health. Isoflavones are naturally occurring phytoestrogens, antioxidants and efflux pump inhibitors, but their therapeutic use is limited by poor water-solubility and intense first-pass metabolism. Here, we report on effects of isoflavones against C. pneumoniae and C. trachomatis and describe buccal permeability and initial formulation development for biochanin A. Biochanin A was the most potent Chlamydia growth inhibitor among the studied isoflavones, with an IC₅₀ = 12 µM on C. pneumoniae inclusion counts and 6.5 µM on infectious progeny production, both determined by immunofluorescent staining of infected epithelial cell cultures. Encouraged by the permeation of biochanin A across porcine buccal mucosa without detectable metabolism, oromucosal film formulations were designed and prepared by a solvent casting method. The film formulations showed improved dissolution rate of biochanin A compared to powder or a physical mixture, presumably due to the solubilizing effect of hydrophilic additives and presence of biochanin A in amorphous state. In summary, biochanin A is a potent inhibitor of Chlamydia spp., and the in vitro dissolution results support the use of a buccal formulation to potentially improve its bioavailability in antichlamydial or other pharmaceutical applications.

Chlamydia pneumoniae infection in mice induces chronic lung inflammation, iBALT formation, and fibrosis

Chlamydia pneumoniae (CP) lung infection can induce chronic lung inflammation and is associated with not only acute asthma but also COPD exacerbations. However, in mouse models of CP infection, most studies have investigated specifically the acute phase of the infection and not the longer-term chronic changes in the lungs. We infected C57BL/6 mice with 5×10⁵ CP intratracheally and monitored inflammation, cellular infiltrates and cytokine levels over time to investigate the chronic inflammatory lung changes. While bacteria numbers declined by day 28, macrophage numbers remained high through day 35. Immune cell clusters were detected as early as day 14 and persisted through day 35, and stained positive for B, T, and follicular dendritic cells, indicating these clusters were inducible bronchus associated lymphoid tissues (iBALTs). Classically activated inflammatory M1 macrophages were the predominant subtype early on while alternatively activated M2 macrophages increased later during infection. Adoptive transfer of M1 but not M2 macrophages intratracheally 1 week after infection resulted in greater lung inflammation, severe fibrosis, and increased numbers of iBALTS 35 days after infection. In summary, we show that CP lung infection in mice induces chronic inflammatory changes including iBALT formations as well as fibrosis. These observations suggest that the M1 macrophages, which are part of the normal response to clear acute C. pneumoniae lung infection, result in an enhanced acute response when present in excess numbers, with greater inflammation, tissue injury, and severe fibrosis.

Will the SAFE strategy be sufficient to eliminate trachoma by 2020? Puzzlements and possible solutions

Since the inception of (the Global Elimination of Blinding Trachoma) GET 2020 in 1997 and the implementation of the SAFE strategy a year later, much progress has been made toward lowering the prevalence of trachoma worldwide with elimination of the disease in some countries. However, high recurrence of trichiasis after surgery, difficulty in controlling the reemergence of infection after mass distribution of azithromycin in some communities, the incomplete understanding of environment in relation to the disease, and the difficulty in establishing the prevalence of the disease in low endemic areas are some of the issues still facing completion of the GET 2020 goals. In this narrative review, literature was searched from 1998 to January 2013 in PubMed for original studies and reviews. Reasons for these ongoing problems are discussed, and several suggestions are made as avenues for exploration in relation to improving the SAFE strategy with emphasis on improving surgical quality and management of the mass treatment with antibiotics. In addition, more research needs to be done to better understand the approach to improve sanitation, hygiene, and environment. The main conclusion of this review is that scale-up is needed for all SAFE components, and more research should be generated from communities outside of Africa and Asia.

Chlamydia pneumoniae induces a pro-inflammatory phenotype in murine vascular smooth muscle cells independently of elevating reactive oxygen species

  NADPH oxidases (Nox) are reactive oxygen species (ROS)-generating enzymes that play important physiological roles in host defence and redox signalling. However, Nox activity is upregulated in the vascular wall during atherosclerosis and contributes to plaque formation by promoting oxidative stress and inflammation.   The bacterium Chlamydia pneumoniae has been detected in vascular smooth muscle cells (VSMC) of human atheroma. We hypothesized that C. pneumoniae infection of VSMC causes Nox activation, which initially limits infection but ultimately causes oxidative stress, activation of pro-inflammatory pathways and an atherogenic phenotype.   Chlamydia pneumoniae infection of mouse cultured VSMC significantly increased ROS production by twofold but did not upregulate mRNA expression of Nox1 or Nox4. Chlamydia pneumoniae did increase Nox2 mRNA levels significantly by threefold, but this did not translate to elevated Nox2 protein expression.   The Nox inhibitor gp91ds-tat had no effect on C. pneumoniae-induced ROS production. In contrast, apocynin significantly reduced ROS levels by 75% in C. pneumoniae-infected VSMC, an effect most likely attributable to its direct anti-oxidant action.   Although apocynin had no effect on C. pneumoniae-induced expression of inflammatory markers, bacteria recovered from apocynin-treated VSMC displayed a higher degree of infectivity in HEp-2 cells.   In conclusion, C. pneumoniae infection increases ROS production in VSMC independently of Nox activity. Although elevated ROS production appears to serve a protective role by limiting the spread of infection, we speculate that this response will be detrimental over the long term by causing oxidative stress and a smouldering inflammatory response by maintaining C. pneumoniae persistence within the cell.

Ocular Clinical Pictures Disclosed by PCR Molecular Diagnosis and Chlamydia Trachomatis Infection Performed following the Appropriate Sampling Modality in Ocular Ecosystem

Four clinical cases regarding the correct diagnosis of early ocular Chlamydia trachomatis (Ct) inflammation, performed by two different modalities on the ocular ecosystem, are discussed. The present study was carried out in parallel using a cotton flock ocular swab and the scraping of upper lid conjunctiva. The ocular samplings were carried out by a first ocular swab from inner canthus and fornix, while the second by a conjunctival scraping from upper the conjunctiva of four patients. In the first case, by ocular swab, all samples resulted negative to Ct-DNA research by PCR, while the cultural analyses showed a growth of saprophytic and opportunist germs in all patients. No growth micetes resulted. On the contrary, in the second case, by conjunctival scraping, three of four samples were positive to Ct-DNA research. No fungal growth was observed, while only the 3rd patient, negative to Ct-DNA research, showed microbial growth. Our study, carried out with two different modalities of sampling on different areas of the same ecosystem, showed different results, demonstrating the importance of sampling accuracy for chlamydial research by molecular analysis in PCR, during the slight phase of inflammation. These initial data indicate that laboratory diagnosis by PCR for precocious Ct infection, not revealed clinically, could represent the first step for a correct diagnostic procedure, eliminating one of the critical points, allowing an accurate, effective and precocious antibiotic therapy. We hypothesize that only by following these correct procedures of sampling during the early phase of chlamydial inflammation, in the future, will it be possible to reduce a pejorative evolution of this worsening disease in people genetically susceptible, building a more efficacious Public Health program of prevention against chronic conjunctivitis and to favour a major prevention of trachoma in endemic areas.

Innate immune responses to Chlamydia pneumoniae infection: role of TLRs, NLRs, and the inflammasome

Chlamydiae are important human pathogens that are responsible for a wide rage of diseases with a significant impact on public health. In this review article we highlight how recent studies have increased our knowledge of Chlamydia pneumoniae pathogenesis and mechanisms of innate immunity directed host defense against C. pneumoniae infection.

In vitro antichlamydial activity of garenoxacin against Chlamydia trachomatis

Garenoxacin showed the most potent chlamydial activity against Chlamydia trachomatis D/UW-3/Cx among three tested quinolones and azithromycin. The DNA gyrase genes, gyrA and gyrB, of C. trachomatis D/UW-3/Cx were cloned and the GyrA and GyrB subunits of DNA gyrase protein were separately expressed as histidine-tagged proteins in Escherichia coli. The mean 50% inhibitory concentration (IC(50)) of garenoxacin against the supercoiling activity of C. trachomatis D/UW-3/Cx gyrase was 2.9 ± 0.4 μg/ml, which was the most potent inhibitory activity against DNA gyrase among the quinolones tested in this study. At an extracellular concentration of 0.5 μg/ml, the cellular-to-extracellular concentration ratio of garenoxacin was 15.3 ± 1.3, equivalent to that of moxifloxacin and greater than that of levofloxacin. In a time-kill experiment, after exposure to garenoxacin at a concentration of 0.5 μg/ml at 0-6, 5-11, and 24-30 h after infection, the percentages of recoverable chlamydial inclusion-forming units were 11.1 ± 3.3, 0.6 ± 0.1, and 2.6 ± 0.5%, respectively. On transmission electron microscopy observation, after exposure to garenoxacin at 24-30 h after infection, some C. trachomatis elementary bodies remained in the inclusion body; however, the reticulate bodies were completely disrupted. In conclusion, garenoxacin is expected to be a useful quinolone in the treatment of infectious diseases caused by C. trachomatis.

Comparison of real-time PCR and a microimmunofluorescence serological assay for detection of chlamydophila pneumoniae infection in an outbreak investigation

We assessed the performance of a recently validated real-time PCR assay and a commercially available microimmunofluorescence serologic test for the detection of Chlamydophila pneumoniae infection during an outbreak. Evaluation of specimens from 137 individuals suggests that real-time PCR holds greater utility as a diagnostic tool for early C. pneumoniae detection.

Chlamydiaceae infections in pig

Chlamydiaceae are Gram-negative obligate intracellular bacteria. They are responsible for a broad range of diseases in animals and humans. In pigs, Chlamydia suis, Chlamydia abortus, Chlamydia pecorum and Chlamydia psittaci have been isolated. Chlamydiaceae infections in pigs are associated with different pathologies such as conjunctivitis, pneumonia, pericarditis, polyarthritis, polyserositis, pseudo-membranous or necrotizing enteritis, periparturient dysgalactiae syndrome, vaginal discharge, return to oestrus, abortion, mummification, delivery of weak piglets, increased perinatal and neonatal mortality and inferior semen quality, orchitis, epididymitis and urethritis in boars. However, Chlamydiaceae are still considered as non-important pathogens because reports of porcine chlamydiosis are rare. Furthermore, Chlamydiaceae infections are often unnoticed because tests for Chlamydiaceae are not routinely performed in all veterinary diagnostic laboratories and Chlamydiaceae are often found in association with other pathogens, which are sometimes more easily to detect. However, recent studies have demonstrated that Chlamydiaceae infections in breeding sows, boars and piglets occur more often than thought and are economically important. This paper presents an overview on: the taxonomy of Chlamydiaceae occurring in pigs, diagnostic considerations, epidemiology and pathology of infections with Chlamydiaceae in pigs, public health significance and finally on prevention and treatment of Chlamydiaceae infections in pigs.

Possibilities for therapeutic interventions in disrupting Chlamydophila pneumoniae involvement in atherosclerosis

Strong sero-epidemiologic, pathologic, and experimental evidence suggests that Chlamydophila pneumoniae (Cpn) infection may play a causative role in the development of atherosclerosis. Cpn is an obligate intracellular gram-negative bacterium that is responsible for 10% of cases of community-acquired pneumonia. In addition to its presence in the respiratory tract, live Cpn has been found within atherosclerotic plaques. Experimental findings have established Cpn's ability to infect vascular cells and elicit important atherogenic responses. Furthermore, Cpn infection can promote atherosclerotic development in different animal models. To date however, large-scale antibiotic clinical trials have not been effective in preventing major cardiovascular events. It is becoming apparent that Cpn undergoes a persistent state of infection, which is refractory to current chlamydial antibiotics. New treatment strategies that are effective toward acute and persistent forms of Cpn infection are needed in order to effectively eradicate the bacterium within the vascular wall. Possible therapeutics targets include Cpn-specific proteins and machinery directly involved in their survival, replication and maintenance. Alternatively, selectively targeting host cell pathways and machinery required for Cpn's actions in vascular cells also represent potential treatment strategies for atherosclerosis.

Cell cycle-dependent, intercellular transmission of Toxoplasma gondii is accompanied by marked changes in parasite gene expression

Intracellular microbes have evolved efficient strategies for transitioning from one cell to another in a process termed intercellular transmission. Here we show that host cell transmission of the obligate intracellular parasite Toxoplasma gondii is closely tied to specific cell cycle distributions, with egress and reinvasion occurring most proficiently by parasites in the G1 phase. We also reveal that Toxoplasma undergoes marked changes in mRNA expression when transitioning from the extracellular environment to its intracellular niche. These mRNA level changes reflect a modal switch from expression of proteins involved in invasion, motility and signal transduction in extracellular parasites to expression of metabolic and DNA replication proteins in intracellular parasites. Host cell binding and signalling associated with the discharge of parasite secretory proteins was not sufficient to induce this switch in gene expression, suggesting that the regulatory mechanisms responsible are tied to the establishment of the intracellular environment. The genes whose expression increased after parasite invasion belong to a progressive cascade known to underlie the parasite division cycle indicating that the unique relationship between the G1 phase and invasion effectively synchronizes short-term population growth. This work provides new insight into how this highly successful parasite competently transits from cell to cell.

Serological diagnosis of Chlamydia pneumoniae infection: limitations and perspectives

Chlamydia pneumoniae is an obligate intracellular human pathogen responsible for a wide range of acute and chronic human diseases, including pneumonia and other respiratory diseases. Serological methods for the diagnosis of C. pneumoniae infection vary widely, and several authors have reported significant inter- and intra-laboratory variability in diagnostic methods and criteria. Over the past 10 years, numerous studies have focused on the identification of specific antigens for application in serodiagnosis, including the diagnosis of persistent infections. The use of proteomics may enable the development of serological diagnosis kits that offer reliable sensitivity and specificity and might even differentiate between the various stages of infection with this pathogen.

Stevens-Johnson syndrome/erythema multiforme major and Chlamydia pneumoniae infection in young patients

Erythema multiforme major (EMM) is an acute, self-limited mucocutaneous disease characterized by the abrupt onset of symmetrical fixed red papules evolving to target lesions. It is triggered mainly by infections, such as herpes simplex virus (HSV) and Mycoplasma pneumoniae, or drugs. In instances of extensive skin lesions with “giant” targets, prominent involvement of several mucous sites and fever, it may be difficult to distinguish from Stevens-Johnson syndrome (SJS), a rarer, life-threatening reaction which is mainly drug-induced. We report a 7-year old boy with SJS and Chlamydia pneumoniae infection and 3 patients with erythema multiforme (EM) and co-infection with Chlamydia pneumoniae: a 3-year old girl and a 29-year old man developed EMM lesions associated to Mycoplasma pneumoniae and Chlamydia pneumonia and a 20-year old woman with EMM associated to herpes simplex type 2 and Chlamydia pneumoniae infection. None of the 4 patients had history of drug intake in the last two months.

Chlamydia pneumoniae is an intracellular bacteria responsible for respiratory infections. Despite the fact that its role in SJS/EMM has been rarely reported, our cases suggest that it may cause SJS and trigger EM when co-infecting a patient, either with Mycoplasma pneumoniae or herpes simplex. We conclude that infection by Chlamydia pneumoniae should be suspected and ruled out in every patient with SJS/EMM, especially in those with signs of respiratory infection.

Chlamydia pneumoniae-induced memory CD4+ T-cell activation in human peripheral blood correlates with distinct antibody response patterns

Chlamydia pneumoniae is a frequent pathogen of the respiratory tract, and persistent infections with this obligate intracellular bacterium have been associated with different severe sequelae. Although T-cell activation during acute C. pneumoniae infections has been described, little is known about the frequency or the role of the C. pneumoniae-specific memory T cells that reside in the human body after the resolution of the infection. In the present study, the C. pneumoniae-induced T-cell responses in peripheral blood mononuclear cells of 56 healthy volunteers were analyzed and compared to the donor's serum antibody reactivity toward whole C. pneumoniae as well as recombinant C. pneumoniae antigens. Following short-term stimulation with C. pneumoniae, both gamma interferon (IFN-gamma)- and interleukin-2 (IL-2)-producing CD4(+) T-cell responses could be detected in 16 of 56 healthy individuals. C. pneumoniae-activated CD4(+) T cells expressed CD154, a marker for T-cell receptor-dependent activation, and displayed a phenotype of central memory T cells showing dominant IL-2 production but also IFN-gamma production. Interestingly, individuals with both IFN-gamma- and IL-2-producing responses showed significantly decreased immunoglobulin G reactivity toward C. pneumoniae RpoA and DnaK, antigens known to be strongly upregulated during chlamydial persistence, compared to IgG reactivity of seropositive individuals with no T-cell response or CD4(+) T-cell responses involving the production of a single cytokine (IFN-gamma or IL-2). Our results demonstrate that memory CD4(+) T cells responding to C. pneumoniae stimulation can be detected in the circulation of healthy donors. Furthermore, among seropositive individuals, the presence or the absence of dual IFN-gamma- and IL-2-producing T-cell responses was associated with distinct patterns of antibody responses toward persistence-associated C. pneumoniae antigens.

Essential role of mitochondrial antiviral signaling, IFN regulatory factor (IRF)3, and IRF7 in Chlamydophila pneumoniae-mediated IFN-beta response and control of bacterial replication in human endothelial cells

Chlamydophila pneumoniae infection of the vascular wall as well as activation of the transcription factor IFN regulatory factor (IRF)3 have been linked to development of chronic vascular lesions and atherosclerosis. The innate immune system detects invading pathogens by use of pattern recognition receptors, some of which are able to stimulate IRF3/7 activation and subsequent type I IFN production (e. g., IFN-beta). In this study, we show that infection of human endothelial cells with C. pneumoniae-induced production of IFN-beta, a cytokine that so far has been mainly associated with antiviral immunity. Moreover, C. pneumoniae infection led to IRF3 and IRF7 nuclear translocation in HUVECs and RNA interference experiments showed that IRF3 and IRF7 as well as the mitochondrial antiviral signaling (MAVS) were essential for IFN-beta induction. Finally, C. pneumoniae replication was enhanced in endothelial cells in which IRF3, IRF7, or MAVS expression was inhibited by small interfering RNA and attenuated by IFN-beta treatment. In conclusion, C. pneumoniae infection of endothelial cells activates an MAVS-, IRF3-, and IRF7-dependent signaling, which controls bacterial growth and might modulate development of vascular lesions.

Chlamydia trachomatis growth inhibition and restoration of LDL-receptor level in HepG2 cells treated with mevastatin

Background

Perihepatitis is rare but consistently occurring extragenital manifestation of untreated Chlamydia trachomatis infection. Despite of possible liver involvement in generalized C. trachomatis infection, the ability of the pathogen to propagate in the hepatic cells and its impact on liver functions is not thoroughly investigated. The effect of mevastatin, an inhibitor of 3-hydroxy-3-methylglutaryl CoA reductase, on C. trachomatis growth in human hepatoma cell line HepG2 has been studied. Bacterial growth was assessed by immunostaining with FITC-labeled monoclonal antibody against chlamydial lipopolysaccharide and by RT-PCR for two chlamydial genetic markers (16S rRNA and euo).

Results

Chlamydial inclusion bodies were seen in approximately 50% of hepatocytes at 48 hours in the post infection period. Lysates obtained from infected hepatocytes were positive in the infective progeny test at 48 and especially in 72 hours after infection initiation. It has been shown that chlamydial infection in hepatocytes also leads to the decline of LDL-receptor mRNA which reflects infection multiplicity rate. Additions of mevastatin (1, 20 and 40 μM) 1 hour before inoculation restored and upregulated LDL-receptor mRNA level in a dose-dependent manner. Mevastatin treatment had no effect on internalization of chlamydial particles. However it reduced drastically the number of chlamydial 16S rRNA and euo transcripts as well as overall infection rate in HepG-2 cells. Complete eradication of infection has been seen by immunofluorescent staining at 40 μM mevastatin concentration, when expression level of chlamydial 16S rRNA and euo was undetectable. Lower concentration of mevastatin (20 μM) promoted euo expression level and the appearance of atypically small chlamydial inclusions, while there was a noticeable reduction in the number of infected cells and 16S rRNA transcripts.

Conclusions

C. trachomatis can efficiently propagate in hepatocytes affecting transcription rate of some liver-specific genes. Ongoing cholesterol synthesis is essential for chlamydial growth in hepatocytes. Inhibitors of cholesterol biosynthesis can supplement conventional strategy in the management of C. trachomatis infection.

Chlamydophila pneumoniae infection and COPD: more evidence for lack of evidence?

Chlamydophila pneumoniae has been recognized as a common cause of respiratory tract infections affecting all age groups. The organism has been implicated as an infectious trigger for acute exacerbations of COPD. Moreover, the intracellular existence of this pathogen and the ability to cause chronic respiratory infections have led to a number of studies that investigated its possible association with disease development. The present paper examines and discusses the possible association of acute C. pneumoniae infection in episodes of acute exacerbation of COPD. It also reviews the existing evidence of chronic C. pneumoniae infection with disease pathogenesis and severity. The significant interstudy variation of the choice of diagnostic methods and criteria applied is most likely responsible for the great diversity of results observed. The use of well-standardized, commercially available diagnostic tools, as well as the adoption of a more unified diagnostic approach is probably the key element missing in order to clarify the exact role of C. pneumoniae in COPD.

The NOD/RIP2 pathway is essential for host defenses against Chlamydophila pneumoniae lung infection

Here we investigated the role of the Nod/Rip2 pathway in host responses to Chlamydophila pneumoniae–induced pneumonia in mice. Rip2^−/− mice infected with C. pneumoniae exhibited impaired iNOS expression and NO production, and delayed neutrophil recruitment to the lungs. Levels of IL-6 and IFN-γ levels as well as KC and MIP-2 levels in bronchoalveolar lavage fluid (BALF) were significantly decreased in Rip2^−/− mice compared to wild-type (WT) mice at day 3. Rip2^−/− mice showed significant delay in bacterial clearance from the lungs and developed more severe and chronic lung inflammation that continued even on day 35 and led to increased mortality, whereas WT mice cleared the bacterial load, recovered from acute pneumonia, and survived. Both Nod1^−/− and Nod2^−/− mice also showed delayed bacterial clearance, suggesting that C. pneumoniae is recognized by both of these intracellular receptors. Bone marrow chimera experiments demonstrated that Rip2 in BM-derived cells rather than non-hematopoietic stromal cells played a key role in host responses in the lungs and clearance of C. pneumoniae. Furthermore, adoptive transfer of WT macrophages intratracheally was able to rescue the bacterial clearance defect in Rip2^−/− mice. These results demonstrate that in addition to the TLR/MyD88 pathway, the Nod/Rip2 signaling pathway also plays a significant role in intracellular recognition, innate immune host responses, and ultimately has a decisive impact on clearance of C. pneumoniae from the lungs and survival of the infectious challenge.

Chlamydophila pneumoniae (C. pneumoniae) is a common intracellular parasite that causes lung infections and contributes to several diseases characterized by chronic inflammation. Toll-like receptors expressed on the cell surface detect C. pneumoniae and mount a vigorous defense, but it is not known how the cell defends itself once the pathogen has taken up residence as a parasite. We reasoned that cytosolic pattern recognition receptors called Nods (nucleotide oligomerization domain) that detect microbes that gain entry into the cell might be involved. Using mice genetically deficient in Nod1 and Nod2 or their common downstream adaptor (Rip2), we show that in lung infection, Nod proteins are indeed essential in directing a defense against C. pneumoniae. Mice with defective Nod/Rip2-dependent signaling exhibited delayed recruitment of neutrophils, blunted production of pro-inflammatory cytokines and chemokines, and evidence of defective iNOS expression and NO production. These impaired responses led to delayed clearance of bacteria, intense persistent lung inflammation, and increased mortality. By performing bone marrow transplantation experiments and direct transfer of cells into the lungs of mice, we demonstrated that intact Nod-dependent signaling in bone marrow–derived cells was critical in the defense against C. pneumoniae. Our results indicate that Nod proteins also play an important role in host defense against C. pneumoniae. Coordinated and sequential activation of TLR and Nod signaling pathways may be necessary for an efficient immune response and host defense against C. pneumoniae.

Identification of high- and low-virulent strains of Chlamydia pneumoniae by their characterization in a mouse pneumonia model

Contradicting reports exist about the pathogenicity of Chlamydia pneumoniae and the severity of the respiratory disease they cause. This study aimed to clarify, in mice, our hypothesis that marked differences in virulence of well-defined C. pneumoniae strains might exist for lung infections. C57BL/6J mice were intranasally infected with equal amounts of five different, identically prepared laboratory strains of C. pneumoniae. Based on the clinical score, weight, histopathological score, the granulocyte marker-enzyme myeloperoxidase, and the amount of Chlamydiae in the lung tissue, the C. pneumoniae isolates exhibited clear differences in overall growth characteristics or clearance, and pathological potential. Thus, we could identify chlamydial strains (Kajaani-K6 and CWL-029), where mice became seriously ill, as well as a relatively low-virulent isolate (TWAR-183). Cytokine profiles also varied drastically between the five strains in extent and kinetic. Our results indicate that C. pneumoniae isolates differ markedly with regard to their interaction with the host and their pathological potential. This might also be true for the infection in humans. Because the genomic diversity of C. pneumoniae is rather small, more subtle genomic deviations account most likely for the apparent functional differences. Our results will be useful to identify additional virulence factors in the future.

Atypical bacteria and macrolides in asthma

: Chlamydophila pneumoniae and Mycoplasma pneumoniae are common pathogens causing acute illness in both the upper and lower airways. Several observations are supportive of a possible causative role of these pathogens in asthma; however, more evidence is required before this becomes meaningful in clinical practice. Atypical bacteria can enhance airway hyperresponsiveness and inflammation, both of which have been associated with exacerbations in patients with preexisting asthma. It is less clear whether the above mechanisms might also be responsible for the development of asthma. Difficulties in accurately diagnosing these infections contribute to such uncertainty. In the present report, evidence of the involvement of Chlamydophila and Mycoplasma infection in the development and the progression of asthma are reviewed.

Immunoproteomic identification and serological responses to novel Chlamydia pneumoniae antigens that are associated with persistent C. pneumoniae infections

The controversial discussion about the role of Chlamydia pneumoniae in atherosclerosis cannot be solved without a reliable diagnosis that allows discrimination between past and persistent infections. Using a proteomic approach and immunoblotting with human sera, we identified 31 major C. pneumoniae Ags originating from 27 different C. pneumoniae proteins. More than half of the proteins represent Chlamydia Ags not described previously. Using a comparative analysis of spot reactivity Pmp6, OMP2, GroEL, DnaK, RpoA, EF-Tu, as well as CpB0704 and CpB0837, were found to be immunodominant. The comparison of Ab-response patterns of sera from subjects with and without evidence for persisting C. pneumoniae, determined by multiple PCR analysis of PBMC and vasculatory samples, resulted in differential reactivity for 12 proteins, which is not reflected by reactivity of the sera in the microimmunofluorescence test, the current gold standard for serodiagnosis. Although reactivity of sera from PCR-positive donors was increased toward RpoA, MOMP, YscC, Pmp10, PorB, Pmp21, GroEL, and Cpaf, the reactivity toward YscL, Rho, LCrE, and CpB0837 was decreased, reflecting the altered protein expression of persisting C. pneumoniae in vitro. Our data provide the first evidence of a unique Ab-response pattern associated with persistent C. pneumoniae infections, which is a prerequisite for the serological determination of persistently infected patients.

The autoimmune origin of atherosclerosis

Atherosclerosis is a chronic inflammatory disease. Many studies and observations suggest that it could be caused by an immune reaction against autoantigens at the endothelial level, the most relevant of which are oxidized LDL and heat shock proteins (HSP) 60/65. Endothelial dysfunction plays a fundamental role. The first antigen is related to the increased leakage and oxidation of LDL; the second to cellular reaction to stress. Experimental and clinical observations confirm the pathogenetic role of these antigens. Both innate and adaptive immunity and impaired regulatory mechanisms of the autoimmune reaction are involved. Different triggering factors are examined: infectious agents, smoking, air pollution, diabetes and hypercholesterolemia. Analogies and differences between systemic atherosclerosis and transplant-related coronary atherosclerosis help to understand their respective nature. Immune mechanisms might be responsible for the passage from stable plaque to unstable and rupture-prone plaque. Finally, prospects of treatment and prevention are linked to the induction of tolerance to responsible antigens, activation of immune regulatory response and the use of immunomodulatory drugs.

Chlamydophila pneumoniae derived from inclusions late in the infectious cycle induce aponecrosis in human aortic endothelial cells

BACKGROUND

Atherosclerosis is still the leading cause of death in the western world. Besides known risk factors studies demonstrating Chlamydophila pneumoniae (C. pneumoniae) to be implicated in the progression of the disease, little is known about C. pneumoniae infection dynamics. We investigated whether C. pneumoniae induce cell death of human aortic endothelial cells, a cell type involved in the initiation of atherosclerosis, and whether chlamydial spots derive from inclusions.

RESULTS

Lactate dehydrogenase release revealed host cell death to be dependent on the amounts of Chlamydia used for infection. The morphology of lysed human aortic endothelial cells showed DNA strand breaks simultaneously with cell membrane damage exclusively in cells carrying Chlamydia as spots. Further ultrastructural analysis revealed additional organelle dilation, leading to the definition as aponecrotic cell death of endothelial cells. Exclusive staining of the metabolic active pathogens by chlamydial heat shock protein 60 labelling and ceramide incorporation demonstrated that the bacteria responsible for the induction of aponecrosis had resided in former inclusions. Furthermore, a strong pro-inflammatory molecule, high mobility group box protein 1, was shown to be released from aponecrotic host cells.

CONCLUSION

From the data it can be concluded that aponecrosis inducing C. pneumoniae stem from inclusions, since metabolically active bacterial spots are strongly associated with aponecrosis late in the infectious cycle in vascular endothelial cells and metabolic activity was exclusively located inside of inclusions in intact cells. Vice versa initial spot-like infection with metabolically inert bacteria does not have an effect on cell death induction. Hence, C. pneumoniae infection can contribute to atherosclerosis by initial endothelial damage.

Chlamydophila pneumoniae induces a sustained airway hyperresponsiveness and inflammation in mice

Background

It has been reported that Chlamydophila (C.) pneumoniae is involved in the initiation and promotion of asthma and chronic obstructive pulmonary diseases (COPD). Surprisingly, the effect of C. pneumoniae on airway function has never been investigated.

Methods

In this study, mice were inoculated intranasally with C. pneumoniae (strain AR39) on day 0 and experiments were performed on day 2, 7, 14 and 21.

Results

We found that from day 7, C. pneumoniae infection causes both a sustained airway hyperresponsiveness and an inflammation. Interferon-γ (IFN-γ) and macrophage inflammatory chemokine-2 (MIP-2) levels in bronchoalveolar lavage (BAL)-fluid were increased on all experimental days with exception of day 7 where MIP-2 concentrations dropped to control levels. In contrast, tumor necrosis factor-α (TNF-α) levels were only increased on day 7. From day 7 to 21 epithelial damage and secretory cell hypertrophy was observed. It is suggested that, the inflammatory cells/mediators, the epithelial damage and secretory cell hypertrophy contribute to initiation of airway hyperresponsiveness.

Conclusion

Our study demonstrates for the first time that C. pneumoniae infection can modify bronchial responsiveness. This has clinical implications, since additional changes in airway responsiveness and inflammation-status induced by this bacterium may worsen and/or provoke breathlessness in asthma and COPD.

Competitive inhibition of amino acid uptake suppresses chlamydial growth: involvement of the chlamydial amino acid transporter BrnQ

Chlamydiaceae are obligate intracellular bacterial pathogens that strictly depend on host metabolites, such as nucleotides, lipids, and amino acids. Depletion of amino acids in cell culture media results in abnormal chlamydial development in vitro. Surprisingly, enrichment of certain amino acids also retards chlamydial growth. Our experiments revealed that the antichlamydial effects are largely independent of changes in the host cell transcriptome or proteome and in the major signal transduction pathway modulated by amino acids, the mTOR (mammalian target of rapamycin) pathway. Furthermore, the chlamydial growth inhibition induced by leucine, isoleucine, methionine, or phenylalanine was completely reversed by concomitant addition of valine. In contrast, the growth inhibition induced by serine, glycine, or threonine was not reversed by valine addition. Functional characterization of the only predicted chlamydial transporter for branched-chain amino acids, BrnQ, revealed that it can be blocked by leucine, isoleucine, methionine, or phenylalanine but not by serine, glycine, or threonine. This chlamydial transporter is the only known BrnQ homolog possessing specificity for methionine, suggesting a unique strategy for methionine uptake among gram-negative bacteria. The antichlamydial effects of leucine, isoleucine, methionine, and phenylalanine could be explained as competitive inhibition of the BrnQ transporter and subsequent valine starvation.

Gene expression profiles of Chlamydophila pneumoniae during the developmental cycle and iron depletion-mediated persistence

The obligate intracellular, gram-negative bacterium Chlamydophila pneumoniae (Cpn) has impact as a human pathogen. Little is known about changes in the Cpn transcriptome during its biphasic developmental cycle (the acute infection) and persistence. The latter stage has been linked to chronic diseases. To analyze Cpn CWL029 gene expression, we designed a pathogen-specific oligo microarray and optimized the extraction method for pathogen RNA. Throughout the acute infection, ratio expression profiles for each gene were generated using 48 h post infection as a reference. Based on these profiles, significantly expressed genes were separated into 12 expression clusters using self-organizing map clustering and manual sorting into the “early”, “mid”, “late”, and “tardy” cluster classes. The latter two were differentiated because the “tardy” class showed steadily increasing expression at the end of the cycle. The transcriptome of the Cpn elementary body (EB) and published EB proteomics data were compared to the cluster profile of the acute infection. We found an intriguing association between “late” genes and genes coding for EB proteins, whereas “tardy” genes were mainly associated with genes coding for EB mRNA. It has been published that iron depletion leads to Cpn persistence. We compared the gene expression profiles during iron depletion–mediated persistence with the expression clusters of the acute infection. This led to the finding that establishment of iron depletion–mediated persistence is more likely a mid-cycle arrest in development rather than a completely distinct gene expression pattern. Here, we describe the Cpn transcriptome during the acute infection, differentiating “late” genes, which correlate to EB proteins, and “tardy” genes, which lead to EB mRNA. Expression profiles during iron mediated–persistence led us to propose the hypothesis that the transcriptomic “clock” is arrested during acute mid-cycle.

Chlamydophila (Chlamydia) pneumoniae (Cpn) accounts for approximately one-tenth of the cases of community-acquired pneumonia worldwide, and persistent Cpn infections are thought to be associated with a variety of chronic diseases. Little is known about Cpn transcriptome changes during its biphasic developmental cycle (the acute infection) and persistence stages. Iron limitation, among several other treatments, has recently been shown to lead to persistent Cpn infection. How this pathogen reacts to iron-limiting host defense mechanisms is of great interest, as iron is an important factor affecting virulence. This article reports on the Cpn transcriptome during the developmental cycle and iron depletion–mediated persistence and reveals that genes coding for proteins of the infectious particle (the elementary body [EB]) were expressed constantly at the end of the cycle. In contrast, genes contributing to EB mRNA but not to EB protein showed an increasing expression at the end of the cycle. This suggested that most EB proteins are made in mid-cycle, and the redifferentiation process is initiated only by a limited number of genes. During iron depletion–mediated persistence, the Cpn transcriptome was altered in such a way that an arrest in Cpn gene expression can be proposed.

Cardiovascular and oral disease interactions: what is the evidence?

This paper reviews the evidence for the interaction of oral disease (more specifically, periodontal infections) with cardiovascular disease. Cardiovascular disease is a major cause of death worldwide, with atherosclerosis as the underlying aetiology in the vast majority of cases. The importance of the role of infection and inflammation in atherosclerosis is now widely accepted, and there has been increasing awareness that immune responses are central to atherogenesis. Chronic inflammatory periodontal diseases are among the most common chronic infections, and a number of studies have shown an association between periodontal disease and an increased risk of stroke and coronary heart disease. Although it is recognised that large-scale intervention studies are required, pathogenic mechanism studies are nevertheless required so as to establish the biological rationale. In this context, a number of hypotheses have been put forward; these include common susceptibility, inflammation via increased circulating cytokines and inflammatory mediators, direct infection of the blood vessels, and the possibility of cross-reactivity or molecular mimicry between bacterial and self-antigens. In this latter hypothesis, the progression of atherosclerosis can be explained in terms of the immune response to bacterial heat shock proteins (HSPs). Because the immune system may not be able to differentiate between self-HSP and bacterial HSP, an immune response generated by the host directed at pathogenic HSP may result in an autoimmune response to similar sequences in the host. Furthermore, endothelial cells express HSPs in atherosclerosis, and cross-reactive T cells exist in the arteries and peripheral blood of patients with atherosclerosis. Each of these hypotheses is reviewed in light of current research. It is concluded that although atherosclerotic cardiovascular disease is almost certainly a multifactorial disease, there is now strong evidence that infection and inflammation are important risk factors. As the oral cavity is one potential source of infection, it is wise to try to ensure that any oral disease is minimised. This may be of significant benefit to cardiovascular health and enables members of the oral health team to contribute to their patients' general health.

Persistent Chlamydia pneumoniae infection of cardiomyocytes is correlated with fatal myocardial infarction

Acute myocardial infarction (AMI) associated with unfavorable prognosis is likely to be the consequence of a diffuse active chronic inflammatory process that destabilizes the whole coronary tree and myocardium, suggesting a possible common causal agent underlying both conditions. The main objective of this study was to investigate whether Chlamydia pneumoniae (CP) infection occurred beyond the coronary plaques, namely in the myocardium of individuals who died of AMI. The presence of CP cell wall antigen (OMP-2) and CP-HSP60 was investigated in the myocardium and coronary plaques of 10 AMI and 10 age-matched control patients by immunohistochemistry, electron microscopy, and molecular biology. OMP-2 antigens were found in the unaffected myocardium of 9 of 10 AMI patients. Conversely, only 1 of 10 control patients exhibited a positive staining for CP. Moreover, OMP-2 and CP-HSP60 were detected in the whole coronary tree. CP presence was strongly associated with a T-cell inflammatory infiltrate. Our results suggest that CP may underlie both coronary and myocardial vulnerabilities in patients who died of AMI and corroborate the notion that CP may act by reducing cardiac reserves, thus worsening the ischemic burden of myocardium.

Fitness cost due to mutations in the 16S rRNA associated with spectinomycin resistance in Chlamydia psittaci 6BC

The fitness cost of a resistance determinant is the primary parameter that determines its frequency in vivo. As a model for analysis of the impact of drug resistance mutations on the intracellular life cycle of Chlamydia spp., we studied the growth of four genetically defined spectinomycin-resistant (Spc(r)) clonal variants of Chlamydia psittaci 6BC isolated in the plaque assay. The development of each variant was monitored over 46 h postinfection in the absence of drug, either in pure culture or in 1:1 competition with the parent strain. Spc(r) mutations in the 16S rRNA gene at positions 1191 and 1193 were associated with a marked impairment of C.psittaci biological fitness, and the bacteria were severely out-competed by the wild-type parent. In contrast, mutations at position 1192 had minor effects on the bacterial life cycle, allowing the resistant isolates to compete more efficiently with the wild-type strain. Thus, mutations with a wide range of fitness costs can be selected in the plaque assay, providing a new strategy for prediction and monitoring of the emergence of antibiotic resistance in chlamydiae. So far, drug resistance has not been a serious threat for the treatment of chlamydial infections. Tetracycline is an effective antichlamydial drug that targets 16S rRNA. Attempts to isolate spontaneous tetracycline-resistant mutants of C. psittaci 6BC revealed a frequency <3 x 10(-9). We suggest that the rarity of genotypic antibiotic resistance among chlamydial clinical isolates reflects the deleterious effects of such mutations on the fitness of these obligate intracellular bacteria in the host.

Chlamydia pneumoniae genome sequence analysis and identification of HLA-A2-restricted CD8+ T cell epitopes recognized by infection-primed T cells

In the present study, we performed in silico analysis of Chlamydia pneumoniae genome sequence to identify human HLA-A2-restricted T cell epitopes. Thirty-one Chlamydia-specific protein antigens were selected and peptides were derived thereof using an HLA-A2 epitope predictive algorithm. Firstly, we tested binding of 55 selected 9mer peptides to HLA-A2 in vitro. Next, infection of HLA-A2 transgenic mice with C. pneumoniae elementary bodies and assessment of effector CD8+ T cells allowed us to identify which of the epitopes binding to HLA-A2 in vitro were recognized by C. pneumoniae infection-primed CD8+ T cells. Finally, we could confirm that CD8+ T cells in association with HLA-A2 recognized the most reactive peptides when the corresponding full-length genes were used to DNA-immunize HLA-A2 transgenic mice. By using this approach, a novel HLA-A2-restricted epitope in the outer membrane protein A (OmpA) of C. pneumoniae was identified, which proved to mediate specific lysis of peptide-loaded target cells.