Application of a Mycoplasma group-specific PCR for monitoring decontamination of Mycoplasma-infected Chlamydia sp. strains

Characterization of Actin-based Genotypes and Mycoplasma Endosymbionts of Trichomonas vaginalis Isolated in Sapporo, Japan

PURPOSE

Trichomonas vaginalis is a causative agent of common non-viral sexually transmitted infections worldwide. However, the biological features, such as genotypes and endosymbionts, of T. vaginalis isolated in Japan remain unclear. The aim of this study was to characterize the actin-based genotypes and the endosymbionts of T. vaginalis isolated in Sapporo, Japan.

METHODS

Three T. vaginalis clinical strains were isolated in Sapporo, Japan between 2019 and 2022. Actin-based genotyping was conducted by sequencing and phylogenetic analyses. The endosymbionts, such as Mycoplasma sp. and Trichomonasvirus, were detected using PCR and RT-PCR, respectively. Furthermore, the detected Mycoplasma spp. were identified using 16S rRNA gene sequencing.

RESULTS

Of the three T. vaginalis strains, two belonged to genotype E, whereas one was genotype G as determined by actin-based genotyping. Two of the T. vaginalis strains harbored Mycoplasma spp. Using nearly full-length 16S rRNA gene sequencing, both were identified as Candidatus Mycoplasma girerdii. In contrast, the Trichomonasvirus was not found in the T. vaginalis strains.

CONCLUSION

To our knowledge, this is the first report on the characterization of actin-based genotypes and the presence of endosymbiotic Ca. M. girerdii in T. vaginalis strains in Japan. Thus, this study will provide an important impetus for future research.

SUMOylation inhibition overcomes proteasome inhibitor resistance in multiple myeloma

Proteasome inhibition is a highly effective treatment for multiple myeloma (MM). However, virtually all patients develop proteasome inhibitor resistance, which is associated with a poor prognosis. Hyperactive small ubiquitin-like modifier (SUMO) signaling is involved in both cancer pathogenesis and cancer progression. A state of increased SUMOylation has been associated with aggressive cancer biology. We found that relapsed/refractory MM is characterized by a SUMO-high state, and high expression of the SUMO E1-activating enzyme (SAE1/UBA2) is associated with poor overall survival. Consistently, continuous treatment of MM cell lines with carfilzomib (CFZ) enhanced SUMO pathway activity. Treatment of MM cell lines with the SUMO E1-activating enzyme inhibitor subasumstat (TAK-981) showed synergy with CFZ in both CFZ-sensitive and CFZ-resistant MM cell lines, irrespective of the TP53 state. Combination therapy was effective in primary MM cells and in 2 murine MM xenograft models. Mechanistically, combination treatment with subasumstat and CFZ enhanced genotoxic and proteotoxic stress, and induced apoptosis was associated with activity of the prolyl isomerase PIN1. In summary, our findings reveal activated SUMOylation as a therapeutic target in MM and point to combined SUMO/proteasome inhibition as a novel and potent strategy for the treatment of proteasome inhibitor-resistant MM.

Isolation, Physicochemical Characterization, Labeling, and Biological Evaluation of Mannans and Glucans

The cell wall contains mannans and glucans that are recognized by the host immune system. In this chapter, we will describe the methods to isolate mannans and glucans from the C. albicans cell wall. In addition, we describe how to determine purity, molecular size, and structure of the mannans and glucans. We also detail how to prepare the carbohydrates for in vitro, ex vivo, or in vivo use by describing endotoxin removal (depyrogenation), derivatization, and labeling and evaluation of bioactivity.

Mycoplasma decontamination in Chlamydia trachomatis culture: a curative approach

Mycoplasma contamination of cell culture represents a serious problem in research and decontamination from cell-propagated obligate intracellular bacteria has proven challenging. Here, we presented an optimized protocol to remove Mycoplasma from contaminated Chlamydia trachomatis culture. A stepwise procedure of Mycoplasma removal entails (i) incubation in nonionic detergent containing solution, and (ii) separation of viable chlamydial organisms by fluorescence-activated cell sorting (FACS), followed by subcloning using a focus-forming assay. We also adapted a polymerase chain reaction (PCR) assay using paired universal and Mycoplasma-specific primers, which are distinguishable from the C. trachomatis counterparts, in combination with Sanger sequencing to determine the presence of mycoplasmas' 16S rRNA genes. These integrated approaches allow for full removal of Mycoplasma, as verified by the improved PCR assay, without compromising the capacity of viable C. trachomatis to adapt to new infection in epithelial cells. Some pitfalls during the Mycoplasma decontamination process are discussed.

Important role of Nfkb2 in the KrasG12D-driven carcinogenesis in the pancreas

BACKGROUND

Oncogenic Kras initiates and drives carcinogenesis in the pancreas by complex signaling networks, including activation of the NFκB pathway. Although recent evidence has shown that oncogenic gains in Nfκb2 collaborate with Kras in the carcinogenesis, no data at the level of genetics for the contribution of Nfκb2 is available so far.

METHODS

We used Nfkb2 knock-out mice to decipher the role of the gene in Kras-driven carcinogenesis in vivo.

RESULTS

We show that the Nfkb2 gene is needed for cancer initiation and progression in Kras^G12D-driven models and this requirement of Nfkb2 is mechanistically connected to proliferative pathways. In contrast, Nfκb2 is dispensable in aggressive pancreatic ductal adenocarcinoma (PDAC) models relying on the simultaneous expression of the Kras oncogene and the mutated tumor suppressor p53.

CONCLUSIONS

Our data add to the understanding of context-dependent requirements of oncogenic Kras signaling during pancreatic carcinogenesis.

Corrigendum to "Development and Evaluation of an Immuno-Capture Enzyme-Linked Immunosorbent Assay to Quantify the Mycoplasma capricolum subsp. Capripneumoniae (Mccp) Protein in Contagious Caprine Pleuropneumonia (CCPP) Vaccine"

[This corrects the article DOI: 10.1155/2020/4236807.].

Targeting the ubiquitin-proteasome system in a pancreatic cancer subtype with hyperactive MYC

The myelocytomatosis oncogene (MYC) is an important driver in a subtype of pancreatic ductal adenocarcinoma (PDAC). However, MYC remains a challenging therapeutic target; therefore, identifying druggable synthetic lethal interactions in MYC‐active PDAC may lead to novel precise therapies. First, to identify networks with hyperactive MYC, we profiled transcriptomes of established human cell lines, murine primary PDAC cell lines, and accessed publicly available repositories to analyze transcriptomes of primary human PDAC. Networks active in MYC‐hyperactive subtypes were analyzed by gene set enrichment analysis. Next, we performed an unbiased pharmacological screen to define MYC‐associated vulnerabilities. Hits were validated by analysis of drug response repositories and genetic gain‐ and loss‐of‐function experiments. In these experiments, we discovered that the proteasome inhibitor bortezomib triggers a MYC‐associated vulnerability. In addition, by integrating publicly available data, we found the unfolded protein response as a signature connected to MYC. Furthermore, increased sensitivity of MYC‐hyperactive PDACs to bortezomib was validated in genetically modified PDAC cells. In sum, we provide evidence that perturbing the ubiquitin–proteasome system (UPS) might be an option to target MYC‐hyperactive PDAC cells. Our data provide the rationale to further develop precise targeting of the UPS as a subtype‐specific therapeutic approach.

Elimination of Mycoplasma contamination in Chlamydia stocks as a result of in vivo passage or plaque isolation

OBJECTIVE

This study aims to eliminate Mycoplasma spp. contamination from laboratory stocks of Chlamydia spp. by in vivo passage or by plaque assay.

RESULTS

We have described two methods of eliminating Mycoplasma contamination from Chlamydia laboratory stocks. We conclude that Mycoplasma species commonly contaminating chlamydial stocks do not survive passage in mice. Chlamydia may also be derived Mycoplasma-free by plaque assay.

Replication-dependent size reduction precedes differentiation in Chlamydia trachomatis

Chlamydiatrachomatis is the most common cause of bacterial sexually transmitted infection. It produces an unusual intracellular infection in which a vegetative form, called the reticulate body (RB), replicates and then converts into an elementary body (EB), which is the infectious form. Here we use quantitative three-dimensional electron microscopy (3D EM) to show that C. trachomatis RBs divide by binary fission and undergo a sixfold reduction in size as the population expands. Conversion only occurs after at least six rounds of replication, and correlates with smaller RB size. These results suggest that RBs only convert into EBs below a size threshold, reached by repeatedly dividing before doubling in size. A stochastic mathematical model shows how replication-dependent RB size reduction produces delayed and asynchronous conversion, which are hallmarks of the Chlamydia developmental cycle. Our findings support a model in which RB size controls the timing of RB-to-EB conversion without the need for an external signal.

The vegetative forms of chlamydiae (RBs) replicate within infected cells and then convert into infectious forms (EBs). Here, the authors use quantitative 3D electron microscopy and computer modeling to show that RB size decreases with replication, and conversion into EBs correlates with an RB size threshold.

MTOR inhibitor-based combination therapies for pancreatic cancer

Background:

Although the mechanistic target of rapamycin (MTOR) kinase, included in the mTORC1 and mTORC2 signalling hubs, has been demonstrated to be active in a significant fraction of patients with pancreatic ductal adenocarcinoma (PDAC), the value of the kinase as a therapeutic target needs further clarification.

Methods:

We used Mtor floxed mice to analyse the function of the kinase in context of the pancreas at the genetic level. Using a dual-recombinase system, which is based on the flippase-FRT (Flp-FRT) and Cre-loxP recombination technologies, we generated a novel cellular model, allowing the genetic analysis of MTOR functions in tumour maintenance. Cross-species validation and pharmacological intervention studies were used to recapitulate genetic data in human models, including primary human 3D PDAC cultures.

Results:

Genetic deletion of the Mtor gene in the pancreas results in exocrine and endocrine insufficiency. In established murine PDAC cells, MTOR is linked to metabolic pathways and maintains the glucose uptake and growth. Importantly, blocking MTOR genetically as well as pharmacologically results in adaptive rewiring of oncogenic signalling with activation of canonical extracellular signal-regulated kinase and phosphoinositide 3-kinase-AKT pathways. We provide evidence that interfering with such adaptive signalling in murine and human PDAC models is important in a subgroup.

Conclusions:

Our data suggest developing dual MTORC1/TORC2 inhibitor-based therapies for subtype-specific intervention.

Broad-Spectrum Inhibition of Respiratory Virus Infection by MicroRNA Mimics Targeting p38 MAPK Signaling

The majority of antiviral therapeutics target conserved viral proteins, however, this approach confers selective pressure on the virus and increases the probability of antiviral drug resistance. An alternative therapeutic strategy is to target the host-encoded factors that are required for virus infection, thus minimizing the opportunity for viral mutations that escape drug activity. MicroRNAs (miRNAs) are small noncoding RNAs that play diverse roles in normal and disease biology, and they generally operate through the post-transcriptional regulation of mRNA targets. We have previously identified cellular miRNAs that have antiviral activity against a broad range of herpesvirus infections, and here we extend the antiviral profile of a number of these miRNAs against influenza and respiratory syncytial virus. From these screening experiments, we identified broad-spectrum antiviral miRNAs that caused >75% viral suppression in all strains tested, and we examined their mechanism of action using reverse-phase protein array analysis. Targets of lead candidates, miR-124, miR-24, and miR-744, were identified within the p38 mitogen-activated protein kinase (MAPK) signaling pathway, and this work identified MAPK-activated protein kinase 2 as a broad-spectrum antiviral target required for both influenza and respiratory syncytial virus (RSV) infection.

HDAC1 and HDAC2 integrate the expression of p53 mutants in pancreatic cancer

Mutation of p53 is a frequent genetic lesion in pancreatic cancer being an unmet clinical challenge. Mutants of p53 have lost the tumour-suppressive functions of wild type p53. In addition, p53 mutants exert tumour-promoting functions, qualifying them as important therapeutic targets. Here, we show that the class I histone deacetylases HDAC1 and HDAC2 contribute to maintain the expression of p53 mutants in human and genetically defined murine pancreatic cancer cells. Our data reveal that the inhibition of these HDACs with small molecule HDAC inhibitors (HDACi), as well as the specific genetic elimination of HDAC1 and HDAC2, reduce the expression of mutant p53 mRNA and protein levels. We further show that HDAC1, HDAC2 and MYC directly bind to the TP53 gene and that MYC recruitment drops upon HDAC inhibitor treatment. Therefore, our results illustrate a previously unrecognized class I HDAC-dependent control of the TP53 gene and provide evidence for a contribution of MYC. A combined approach targeting HDAC1/HDAC2 and MYC may present a novel and molecularly defined strategy to target mutant p53 in pancreatic cancer.

Signaling events in pathogen-induced macrophage foam cell formation

Macrophage foam cell formation is a key event in atherosclerosis. Several triggers induce low-density lipoprotein (LDL) uptake by macrophages to create foam cells, including infections with Porphyromonas gingivalis and Chlamydia pneumoniae, two pathogens that have been linked to atherosclerosis. While gene regulation during foam cell formation has been examined, comparative investigations to identify shared and specific pathogen-elicited molecular events relevant to foam cell formation are not well documented. We infected mouse bone marrow-derived macrophages with P. gingivalis or C. pneumoniae in the presence of LDL to induce foam cell formation, and examined gene expression using an atherosclerosis pathway targeted plate array. We found over 30 genes were significantly induced in response to both pathogens, including PPAR family members that are broadly important in atherosclerosis and matrix remodeling genes that may play a role in plaque development and stability. Six genes mainly involved in lipid transport were significantly downregulated. The response overall was remarkably similar and few genes were regulated in a pathogen-specific manner. Despite very divergent lifestyles, P. gingivalis and C. pneumoniae activate similar gene expression profiles during foam cell formation that may ultimately serve as targets for modulating infection-elicited foam cell burden, and progression of atherosclerosis.

Comparative analysis of the growth and biological activity of a respiratory and atheroma isolate of Chlamydia pneumoniae reveals strain-dependent differences in inflammatory activity and innate immune evasion

Background

Chlamydia pneumoniae is a common human pathogen that is associated with upper and lower respiratory tract infections. It has also been suggested that C. pneumoniae infection can trigger or promote a number of chronic inflammatory conditions, including asthma and atherosclerosis. Several strains of C. pneumoniae have been isolated from humans and animals, and sequence data demonstrates marked genetic conservation, leaving unanswered the question as to why chronic inflammatory conditions may occur following some respiratory-acquired infections.

Methods

C. pneumoniae strains AR39 and AO3 were used in vitro to infect murine bone marrow derived macrophages and L929 fibroblasts, or in vivo to infect C57BL/6 mice via the intranasal route.

Results

We undertook a comparative study of a respiratory isolate, AR39, and an atheroma isolate, AO3, to determine if bacterial growth and host responses to infection varied between these two strains. We observed differential growth depending on the host cell type and the growth temperature; however both strains were capable of forming plaques in vitro. The host response to the respiratory isolate was found to be more inflammatory both in vitro, in terms of inflammatory cytokine induction, and in vivo, as measured by clinical response and lung inflammatory markers using a mouse model of respiratory infection.

Conclusions

Our data demonstrates that a subset of C. pneumoniae strains is capable of evading host innate immune defenses during the acute respiratory infection. Further studies on the genetic basis for these differences on both the host and pathogen side could enhance our understanding how C. pneumoniae contributes to the development chronic inflammation at local and distant sites.

Experimental infection of BHK21 and Vero cell lines with different Mycoplasma spp

Mycoplasma spp, belongs to the class Mollicutes and is capable to produce alterations in cellular cultures causing damages to the biotechnological industry. Bioproducts generally require two essential inputs, bovine serum and cells. The study herein aims to evaluate the mycoplasma concentrations that affect the growing of BHK21 and Vero cells. The species used were: Mycoplasma orale, M. salivarium, M. arginini and M. hyorhinis, cultivated in a SP4 media. Two contamination tests were performed with BHK21 and Vero cells and one of them applied different concentrations of mycoplasma. In the first one, mycoplasma was applied at the day zero and, in the second one, the contamination was performed after the monolayer establishment. The both cellular cultures presented cytopathic effects with mycoplasma contamination, but the Vero cells suffered more damages than the BHK21 ones. It was also observed that the severity of the cytopathic effect depended on the mycoplasma specie, on the concentration and on the time of contact with the cellular culture, which evidences the importance of controlling the presence of mycoplasma in biotechnological industries.

Induction and inhibition of CPAF activity during analysis of Chlamydia-infected cells

Studies of the chlamydial protease CPAF have been complicated by difficulties in distinguishing bona fide intracellular proteolysis from in vitro proteolysis. This confounding issue has been attributed to CPAF activity in lysates from Chlamydia-infected cells. We compared three methods that have been used to inhibit in vitro CPAF-mediated proteolysis: (1) pre-treatment of infected cells with the inhibitor clasto-lactacystin, (2) direct cell lysis in 8 M urea and (3) direct lysis in hot 1% SDS buffer. We identified a number of experimental conditions that reduce the effectiveness of each method in preventing CPAF activity during lysate preparation. The amount of in vitro proteolysis in a lysate was variable and depended on factors such as the specific substrate and the time in the intracellular infection. Additionally, we demonstrated for the first time that artifactual CPAF activity is induced before cell lysis by standard cell detachment methods, including trypsinization. Protein analysis of Chlamydia-infected cells therefore requires precautions to inhibit CPAF activity during both cell detachment and lysate preparation, followed by verification that the cell lysates do not contain residual CPAF activity. These concerns about artifactual proteolysis extend beyond studies of CPAF function because they have the potential to affect the analyses of host and chlamydial proteins from Chlamydia-infected cells.

The inhibition of Platycodin D on Mycoplasma pneumoniae proliferation and its effect on promoting cell growth after anti-Mycoplasma pneumoniae treatment

Platycodin D, extract from the root of Platycodon grandiflorum, is one of the most important monomers of the Qinbaiqingfei pellets (Qinbai) that has already been approved as the first Traditional Chinese Medicine for clinic use as an anti-M. pneumoniae agent. Qinbai constituents Scutellaria baicalensis and Platycodon grandiflorum were used to treat thousands of patients clinically in China each year. In this study, a M. pneumoniae–infected mouse strain, BALB/c, and a human-derived epithelial cell line, A549 type II pneumocytes, were used as experimental model. Anti-M. pneumoniae effect of Platycodin D was measured by the Real-time quantitative PCR, while the cell pathological change with hematoxylin and eosin and the growth recovery effects were determined with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Trypan Blue dye in the experimental model after M. pneumoniae infection. Our research results showed that Platycodin D could significantly inhibit M. pneumoniae and promote cell growth after anti- M. pneumoniae treatment in the infected cells or mice.

Andrographolide inhibits intracellular Chlamydia trachomatis multiplication and reduces secretion of proinflammatory mediators produced by human epithelial cells

Chlamydia trachomatis is the most common sexually transmitted bacterial disease worldwide. Untreated C. trachomatis infections may cause inflammation and ultimately damage tissues. Here, we evaluated the ability of Andrographolide (Andro), a natural diterpenoid lactone component of Andrographis paniculata, to inhibit C. trachomatis infection in cultured human cervical epithelial cells. We found that Andro exposure inhibited C. trachomatis growth in a dose- and time-dependent manner. The greatest inhibitory effect was observed when exponentially growing C. trachomatis was exposed to Andro. Electron micrographs demonstrated the accumulation of unusual, structurally deficient chlamydial organisms, correlated with a decrease in levels of OmcB expressed at the late stage of infection. Additionally, Andro significantly reduced the secretion of interleukin6, CXCL8 and interferon-γ-induced protein10 produced by host cells infected with C. trachomatis. These results indicate the efficacy of Andro to perturb C. trachomatis transition from the metabolically active reticulate body to the infectious elementary body and concurrently reduce the production of a proinflammatory mediator by epithelial cells in vitro. Further dissection of Andro's anti-Chlamydia action may provide identification of novel therapeutic targets.

Aryl hydrocarbon receptor downregulates MYCN expression and promotes cell differentiation of neuroblastoma

Neuroblastoma (NB) is the most common malignant disease of infancy. MYCN amplification is a prognostic factor for NB and is a sign of highly malignant disease and poor patient prognosis. In this study, we aimed to investigate novel MYCN-related genes and assess how they affect NB cell behavior. The different gene expression found in 10 MYCN amplification NB tumors and 10 tumors with normal MYCN copy number were analyzed using tissue oligonucleotide microarrays. Ingenuity Pathway Analysis was subsequently performed to identify the potential genes involved in MYCN regulation pathways. Aryl hydrocarbon receptor (AHR), a receptor for dioxin-like compounds, was found to be inversely correlated with MYCN expression in NB tissues. This correlation was confirmed in a further 14 human NB samples. Moreover, AHR expression in NB tumors was found to correlate highly with histological grade of differentiation. In vitro studies revealed that AHR overexpression in NB cells induced spontaneous cell differentiation. In addition, it was found that ectopic expression of AHR suppressed MYCN promoter activity resulting in downregulation of MYCN expression. The suppression effect of AHR on the transcription of MYCN was compensated for by E2F1 overexpression, indicating that E2F1 is involved in the AHR-regulating MYCN pathway. Furthermore, AHR shRNA promotes the expression of E2F1 and MYCN in NB cells. These findings suggest that AHR is one of the upstream regulators of MYCN. Through the modulation of E2F1, AHR regulates MYCN gene expression, which may in turn affect NB differentiation.

A single-tube real-time PCR assay for Mycoplasma detection as a routine quality control of cell therapeutics

BACKGROUND

Contamination of cell culture and biological material by mollicute species is an important safety issue and requires testing. We have developed a singletube real-time polymerase chain reaction (PCR) assay for rapid detection of Mollicutes species stipulated by the European Pharmacopeia.

METHODS

Primers and TaqMan probes (FAM-labeled) were deduced from 16S rDNA sequence alignment of 18 mollicutes species. A synthetic internal control (IC) DNA and an IC-specific TaqMan probe (VIC-labeled) were included. The analytical sensitivity of the assay was determined on DNA dilutions from 12 mollicute strains. Specificity was proven by the use of DNA from other bacteria.

RESULTS

Analytical sensitivities of the PCR assay were in the range of 405-2,431 genomes/ml for 11 of the 12 tested mollicute DNA samples. The lowest sensitivity was found for Ureaplasma urealyticum (19,239 genomes/ml). Negative results for DNA samples from 3 different ubiquitous bacteria demonstrated the specificity of the PCR assay for Mollicutes. Direct testing of cell culture supernatants spiked with Mycoplasma orale revealed similar sensitivity compared to isolated DNA.

CONCLUSIONS

Our single-tube real-time PCR assay with internal reaction control enables rapid and specific detection of mollicute contaminants. The test protocol is suitable for routine quality control of cell therapeutics.

The sst1 resistance locus regulates evasion of type I interferon signaling by Chlamydia pneumoniae as a disease tolerance mechanism

The sst1, “supersusceptibility to tuberculosis,” locus has previously been shown to be a genetic determinant of host resistance to infection with the intracellular pathogen, Mycobacterium tuberculosis. Chlamydia pneumoniae is an obligate intracellular bacterium associated with community acquired pneumonia, and chronic infection with C. pneumoniae has been linked to asthma and atherosclerosis. C. pneumoniae is a highly adapted pathogen that can productively infect macrophages and inhibit host cell apoptosis. Here we examined the role of sst1 in regulating the host response to infection with C. pneumoniae. Although mice carrying the sst1 susceptible (sst1^S) locus were not impaired in their ability to clear the acute infection, they were dramatically less tolerant of the induced immune response, displaying higher clinical scores, more severe lung inflammation, exaggerated macrophage and neutrophil influx, and the development of fibrosis compared to wild type mice. This correlated with increased activated caspase-3 in the lungs of infected sst1^S mice. Infection of sst1^S macrophages with C. pneumoniae resulted in a shift in the secreted cytokine profile towards enhanced production of interferon-β and interleukin-10, and induced apoptotic cell death, which was dependent on secretion of interferon-β. Intriguingly macrophages from the sst1^S mice failed to support normal chlamydial growth, resulting in arrested development and failure of the organism to complete its infectious cycle. We conclude that the sst1 locus regulates a shared macrophage-mediated innate defense mechanism against diverse intracellular bacterial pathogens. Its susceptibility allele leads to upregulation of type I interferon pathway, which, in the context of C. pneumoniae, results in decreased tolerance, but not resistance, to the infection. Further dissection of the relationship between type I interferons and host tolerance during infection with intracellular pathogens may provide identification of biomarkers and novel therapeutic targets.

Chlamydia pneumoniae is a highly adapted intracellular pathogen and a common cause of atypical, community acquired pneumonia. It has also been suggested as a trigger or promoter of asthma and atherosclerosis. In this study, we examined the role of a genetic locus on mouse chromosome 1 that has been associated with susceptibility to another intracellular pathogen, Mycobacterium tuberculosis, in the pathogenesis of respiratory infections secondary to Chlamydia pneumoniae. We have determined that a variant at this locus, known as sst1 and associated with destructive pulmonary tuberculosis, makes mice dramatically more sensitive in vivo to the inflammatory changes following respiratory infection with C. pneumoniae. This appears to arise from activation of type I interferons and apoptotic cell death, two signaling pathways that are normally silent during productive C. pneumoniae infection. Despite a noted inability of sst1 susceptible macrophages to support chlamydial development, exuberant lung tissue damage resulted in overall more severe disease in vivo. We conclude the sst1-mediated control of lung tissue damage is an important determinant of the genetic susceptibility of a given host to a number of diverse intracellular bacterial pathogens, which may provide predictors of outcomes to infectious diseases as well as possible target for novel therapeutics.

Differences in infectivity and induction of infertility: a comparative study of Chlamydia trachomatis strains in the murine model

Chlamydia trachomatis, although commonly asymptomatic in women, can result in chronic sequelae, such as pelvic inflammatory disease, ectopic pregnancy and infertility. However, a clear relationship has not been determined between specific serovars and the ability to lead to upper genital tract infection or infertility. Thus, in order to investigate differences in pathogenicity, C3H/HeN mice were infected in the ovarian bursa with the C. trachomatis strains D (UW-3/Cx), F (N.I.1), F (IC-Cal-3) and E (Bour). Differences both in the amount of vaginal shedding as well as subsequent fertility rates were observed between D (UW-3/Cx) and F (N.I.1) compared to F (IC-Cal-3) and E (Bour). Approximately 50% of the mice infected with the D (UW-3/Cx) and F (N.I.1) strains had vaginal shedding for up to 3-4 weeks after infection and fertility rates of less than 25%. Furthermore, mice inoculated with D (UW-3/Cx) and F (N.I.1) showed infertility even in the absence of medroxy progesterone acetate (MPA) treatment. In contrast, both MPA and non-MPA treated mice infected with F (IC-Cal-3) or E (Bour) did not show vaginal shedding and had fertility rates between 45 and 88%. Mutations in the CT135 open reading frame have been associated with virulence. However, no nucleotide differences were found among the four isolates for CT135. This murine model of infection with C. trachomatis may help with the understanding of disease pathology in humans and ultimately vaccine development.

CPAF: a Chlamydial protease in search of an authentic substrate

Bacteria in the genus Chlamydia are major human pathogens that cause an intracellular infection. A chlamydial protease, CPAF, has been proposed as an important virulence factor that cleaves or degrades at least 16 host proteins, thereby altering multiple cellular processes. We examined 11 published CPAF substrates and found that there was no detectable proteolysis when CPAF activity was inhibited during cell processing. We show that the reported proteolysis of these putative CPAF substrates was due to enzymatic activity in cell lysates rather than in intact cells. Nevertheless, Chlamydia-infected cells displayed Chlamydia-host interactions, such as Golgi reorganization, apoptosis resistance, and host cytoskeletal remodeling, that have been attributed to CPAF-dependent proteolysis of host proteins. Our findings suggest that other mechanisms may be responsible for these Chlamydia-host interactions, and raise concerns about all published CPAF substrates and the proposed roles of CPAF in chlamydial pathogenesis.

Chlamydia are bacteria that invade eukaryotic host cells and live within a membrane-bound compartment called the chlamydial inclusion. Growth and survival of these important human and animal pathogens depends on extensive interactions with the host cell, which allow chlamydiae to acquire critical nutrients and to avoid host anti-microbial defenses. Chlamydiae are proposed to cause many of these host-pathogen interactions through the cleavage or degradation of host proteins by the chlamydial protease CPAF, which is secreted into the host cytoplasm. Here, we raise questions about the proposed roles of this virulence factor during infection, as well as its published substrates. We found that there was no detectable cleavage or degradation of 11 previously reported CPAF substrates in Chlamydia-infected cells and that CPAF-mediated proteolysis of these host proteins occurs during cell harvest and lysis. However, we still observed host-pathogen interactions previously attributed to CPAF proteolysis of these proteins, suggesting that Chlamydia is likely to cause these effects on the host cell through other mechanisms. Our findings call for a re-evaluation of all published CPAF substrates as well as the proposed roles of this protease in chlamydial pathogenesis.

A multi-laboratory profile of Mycoplasma contamination in Lawsonia intracellularis cultures

Background

During the routine laboratory cultivation of Lawsonia intracellularis, Mycoplasma contamination has been a frequent problem. When Mycoplasma contamination occurs in laboratories that study L. intracellularis, the cultures must be discarded for 4 reasons: 1) Mycoplasma is inevitably concentrated along with L. intracellularis during the passage of L. intracellularis; 2) Mycoplasma inhibits the growth of L. intracellularis; and 3) it is impossible to selectively eliminate Mycoplasma in L. intracellularis cultures. In this study, we observed the contamination of Mycoplasma species during L. intracellularis cultivation among multiple laboratories.

Results

The presence of a Mycoplasma infection in the L. intracellularis cultures was verified using polymerase chain reaction (PCR), and a sequence analysis of the partial 16S rRNA and 23S rRNA genes was performed. A PCR-based assay using genus-specific universal primers revealed that 29 (85.3%) of the 34 cultures were contaminated with Mycoplasma, including 26 with M. hyorhinis (89.2%), 2 with M. orale (6.9%), and 1 with M. fermentans (3.4%). The Mycoplasma contamination was not the result of infection with material of pig origin. McCoy cells, which are required for the cultivation of L. intracellularis, were also ruled out as the source of the Mycoplasma contamination.

Conclusions

In this study, M. hyorhinis was identified as the most common mollicute that contaminated L. intracellularis cultures. Whether L. intracellularis enhances the biological properties of Mycoplasma to promote infection in McCoy cells is not known. Because the McCoy cell line stocks that were used simultaneously were all negative for Mycoplasma, and the same worker handled both the McCoy cells to maintain the bacteria and the L. intracellularis cultures, it is possible that the L. intracellularis cultures are more vulnerable to Mycoplasma contamination. Taken together, these results suggest that continuous cultures of L. intracellularis must be tested for Mycoplasma contamination at regular intervals.

The GenBank accession numbers for the sequences reported in this paper are JN689375 to JN689377.

Hsp90α/β associates with the GSK3β/axin1/phospho-β-catenin complex in the human MCF-7 epithelial breast cancer model

Hsp90α/β, the signal transduction chaperone, maintains intracellular communication in normal, stem, and cancer cells. The well characterised association of Hsp90α/β with its client kinases form the framework of multiple signalling networks. GSK3β, a known Hsp90α/β client, mediates β-catenin phosphorylation as part of a cytoplasmic destruction complex which targets phospho-β-catenin to the 26S proteasome. The canonical Wnt/β-catenin pathway promotes stem cell self-renewal as well as oncogenesis. The degree of Hsp90α/β involvement in Wnt/β-catenin signalling needs clarification. Here, we describe the association of Hsp90α/β with GSK3β, β-catenin, phospho-β-catenin and the molecular scaffold, axin1, in the human MCF-7 epithelial breast cancer cell model using selective inhibition of Hsp90α/β, confocal laser scanning microscopy and immunoprecipitation. Our findings suggest that Hsp90α/β modulates the phosphorylation of β-catenin by interaction in common complex with GSK3β/axin1/β-catenin.

Enhanced virulence of Chlamydia muridarum respiratory infections in the absence of TLR2 activation

Chlamydia trachomatis is a common sexually transmitted pathogen and is associated with infant pneumonia. Data from the female mouse model of genital tract chlamydia infection suggests a requirement for TLR2-dependent signaling in the induction of inflammation and oviduct pathology. We hypothesized that the role of TLR2 in moderating mucosal inflammation is site specific. In order to investigate this, we infected mice via the intranasal route with C. muridarum and observed that in the absence of TLR2 activation, mice had more severe disease, higher lung cytokine levels, and an exaggerated influx of neutrophils and T-cells into the lungs. This could not be explained by impaired bacterial clearance as TLR2-deficient mice cleared the infection similar to controls. These data suggest that TLR2 has an anti-inflammatory function in the lung during Chlamydia infection, and that the role of TLR2 in mucosal inflammation varies at different mucosal surfaces.

Notch1 expression predicts an unfavorable prognosis and serves as a therapeutic target of patients with neuroblastoma

PURPOSE

Notch signaling has been implicated to play a critical role in the tumorigenesis of neuroblastoma (NB) and can modulate calreticulin (CRT) expression that strongly correlates with tumor differentiation and favorable prognosis of NB. We thus sought to determine how Notch regulates CRT expression and affects NB tumor behavior.

EXPERIMENTAL DESIGN

The Notch-dependent regulation of CRT expression in cultured NB cells was analyzed by confocal microscopy and Western blotting. Notch1 protein expression in 85 NB tumors was examined by immunohistochemistry and correlated with the clinicopathologic/biological characters of NB patients. The progression of NB tumors in response to attenuated Notch signaling was examined by using a xenograft mouse model.

RESULTS

We showed that CRT is essential for the neuronal differentiation of NB cells elicited by inhibition of Notch signaling. This effect was mediated by a c-Jun-NH(2)-kinase-dependent pathway. Furthermore, NB tumors with elevated Notch1 protein expression were strongly correlated with advanced tumor stages, MYCN amplification, an undifferentiated histology, as well as a low CRT expression level. Most importantly, the opposing effect between Notch1 and CRT could reciprocally affect the survival of NB patients. The administration of a gamma-secretase inhibitor into a xenograft mouse model of NB significantly suppressed the tumor progression.

CONCLUSIONS

Our findings provide the first evidence that a c-Jun-NH(2)-kinase-CRT-dependent pathway is essential for the neuronal differentiation elicited by Notch signaling blockade and that Notch1 and CRT can synergistically predict the clinical outcomes of NB patients. The present data suggest that Notch signaling could be a therapeutic target for NB.

Rapid and sensitive detection of Mollicutes in cell culture by polymerase chain reaction

Infections with Mollicutes species (such as Mycoplasma, Acholeplasma, and Ureaplasma) can induce a variety of problems in living organisms and laboratory cell cultures. Therefore, it is necessary to establish a routine diagnostic protocol for Mycoplasma infection in order to ensure reliable research results, as well as the safety of commercial biological products. For that purpose a novel PCR-based procedure using specific designed primers complementary to 16S rRNA genome region of mollicute species was evaluated. PCR was optimized and sensitivity and specificity was evaluated by defined cell count concentrations (2-31250 CFU/ml) of different strains of Mycoplasma, Acholeplasma and Ureaplasma. Amplicon (272 bp) was cloned by PCR-cloning and sequenced by dideoxy chain termination. PCR, was found to be able to detect 10 copies of mollicute target DNA. No cross-reactivity with genomic DNA of non-mollicute bacteria or human cell lines was observed. Forty seven human and animal cell lines were evaluated for mollicute contamination. Twenty five cell lines (53%) were correctly identified as contaminated by this molecular approach. The results of this study demonstrated that this PCR-based method is not only fast and reproducible, but also highly sensitive and specific for detecting contaminant mycoplasmas in cell cultures.

Stability of Chlamydophila pneumoniae in a harsh environment without a requirement for acanthamoebae

The effect of actual interactions between Chlamydophila pneumoniae and amoebae (Acanthamoeba) on the survival of C. pneumoniae was investigated. C. pneumoniae and amoebae were detected in 75 soil samples by IFU assay and PCR. Although C. pneumoniae could not be cultured, the DNA prevalence of C. pneumoniae and amoebae in natural soil was 20% and 92% (no correlation between the prevalence of DNA was observed). The viability of C. pneumoniae spiked in autoclaved soil was assessed by IFU assay and RT-PCR. Although the number of infective progeny decreased for three days, transcripts of C. pneumoniae were detected for up to 98 days independently of amoebae. The stability of C. pneumoniae in liquid medium was also assessed by IFU assay and transmission electron microscopy. The bacteria could survive at 15 degrees C for 14 days independently of amoebae. Bacteria cultured without amoebae were confirmed to have normal structures. Thus, the presence of amoebae has no effect on C. pneumoniae survival, and the bacteria can survive in the absence of host cells for an extended period of time.

Inflammation and fibrosis during Chlamydia pneumoniae infection is regulated by IL-1 and the NLRP3/ASC inflammasome

Chlamydia pneumoniae is a common respiratory pathogen associated with atypical pneumonia, and it has been suggested as a trigger or promoter of several chronic inflammatory conditions, such as asthma and atherosclerosis. The beta form of IL-1 (IL-1beta) is a proinflammatory cytokine released by many cell types and is an important mediator of inflammation during infection. IL-1beta production is a tightly controlled process that includes regulation at multiple levels and typically requires two distinct signals for activation and release. In this study, we investigated the ability of C. pneumoniae to induce IL-1beta secretion. We found that C. pneumoniae was unique among the other Chlamydia species tested in its ability to potently induce secretion of mature IL-1beta from unprimed bone marrow-derived macrophages during a productive infection. TLR2 was required for induction of pro-IL-1beta, whereas the NLRP3/ASC was required for caspase-1 activation and pro-IL-1beta cleavage to produce mature IL-1beta. Caspase-1 cleavage was independent of endogenous ATP release, but required potassium flux, lysosomal acidification, and cathepsin B release. We further investigated the role of IL-1 in host defense against C. pneumoniae-induced pneumonia using mice deficient in the type I IL-1R. Although the IL-1R(-/-) mice developed an inflammatory infiltrate, the number of infiltrating neutrophils was lower, whereas there was evidence of increased infiltrating fibroblasts and mesenchymal cells and more lung fibrosis. We conclude that C. pneumoniae directly activates the NLRP3/ASC inflammasome, leading to the release of biologically active IL-1beta, and that concurrent IL-1 signaling is required for optimal host defense against acute bacterial pneumonia.

Fibroblast growth factor-inducible 14 (Fn14) is expressed in the lower genital tract and may play a role in amplifying inflammation during infection

TNF-like weak inducer of apoptosis (TWEAK) is a member of the tumor necrosis factor (TNF) cytokine superfamily which regulates a number of cellular responses, including inflammation and proliferation. TWEAK is primarily secreted by phagocytic cells and its receptor, fibroblast growth factor-inducible 14 (Fn14), is expressed on non-lymphoid cells, including epithelial, endothelial and mesenchymal cells. The TWEAK/Fn14 pathway is highly conserved from an evolutionary standpoint, and has been shown to play a role in tissue regeneration and inflammation in the liver, kidney, lung and skeletal muscle. We hypothesized that TWEAK/Fn14 might have a physiological role in regulating infection-induced inflammation in the lower female genital tract. To test this hypothesis, we examined expression of the receptor Fn14 in relevant cells and tissue. Receptor function was tested by treating cells with recombinant TWEAK, with and without other known proinflammatory stimuli. Flow cytometric analysis of vaginal and cervical epithelial cells revealed that Fn14 was highly expressed at the cell surface. We also detected both Fn14 and TWEAK in whole cervical tissue by RT-PCR. Treatment of vaginal and cervical epithelial cells with recombinant TWEAK led to a weak induction of the chemokine IL-8. However, TWEAK potentiated the effects of IL-1ss, the TLR2 ligand Pam(3)CysSK(4), and live Neisseria gonorrhoeae in a synergistic manner. These data reveal a novel pathway for regulation of microbial-induced inflammation in the female reproductive tract and suggest that interference with the TWEAK/Fn14 pathway might be an approach to abrogate excessive infection-induced inflammation caused by sexually transmitted pathogens.

Centrosome abnormalities during a Chlamydia trachomatis infection are caused by dysregulation of the normal duplication pathway

The presence of supernumerary centrosomes in cells infected with Chlamydia trachomatis may provide a mechanism to explain the association of C. trachomatis genital infection with cervical cancer. We show that the amplified centrosomal foci induced during a chlamydial infection contain both centriolar and pericentriolar matrix markers, demonstrating that they are bona fide centrosomes. As there were multiple immature centrioles but approximately one mature centriole per cell, aborted cytokinesis alone cannot account for centrosome amplification during a chlamydial infection. Production of supernumerary centrosomes required the kinase activities of Cdk2 and Plk4, which are known regulators of centrosome duplication, and progression through S-phase, which is the stage in the cell cycle when duplication of the centrosome occurs. These requirements indicate that centrosome amplification during a chlamydial infection depends on the host centrosome duplication pathway, which normally produces a single procentriole from each template centriole. However, C. trachomatis induces a loss of numerical control so that multiple procentrioles are formed per template.

Chlamydia pneumoniae growth inhibition in cells by the steroid receptor antagonist RU486 (mifepristone)

Since steroids are powerful anti-inflammatory agents and increase susceptibility to a variety of infections, including Chlamydia (Chlamydophila) pneumoniae respiratory tract infections, the effect of the steroid receptor antagonist RU486 (mifepristone) on C. pneumoniae growth in epithelial HEp-2 cells was examined. Treatment of HEp-2 cells with RU486 significantly inhibited the growth of C. pneumoniae in a dose-dependent manner. Electron microscopic studies also revealed that the treatment of infected cells with RU486 resulted in a marked destruction of infecting organisms. The addition of the host cell protein synthesis inhibitor cycloheximide to the infected cells did not alter the inhibition of C. pneumoniae growth by RU486. Pretreatment of C. pneumoniae organisms with RU486 before addition to culture also did not result in any modulation of bacterial growth in the cells. However, the binding of RU486 to C. pneumoniae organisms in cells at 24 h after infection was demonstrated by immune electron microscopy with anti-RU486 antibody. Incubation of cells with anti-RU486 antibody completely diminished the inhibition of C. pneumoniae growth by RU486. These results indicate that RU486 may directly bind to the bacteria within cells and cause the destruction of C. pneumoniae. This novel mode of regulation of C. pneumoniae growth in cells by RU486 might provide a new approach to understanding complicated aspects of C. pneumoniae infection.

Reversal of the antichlamydial activity of putative type III secretion inhibitors by iron

INPs, which are chemically synthesized compounds belonging to a class of acylated hydrazones of salicylaldehydes, can inhibit the growth of Chlamydiaceae. Evidence has been presented that in Yersinia and Chlamydia INPs may affect the type III secretion (T3S) system. In the present study 25 INPs were screened for antichlamydial activity at a concentration of 50 muM, and 14 were able to completely inhibit the growth of Chlamydia trachomatis serovar D in McCoy and HeLa 229 cells. The antichlamydial activities of two of these INPs, INPs 0341 and 0400, were further characterized due to their low cytotoxicity. These compounds were found to inhibit C. trachomatis in a dose-dependent manner; were not toxic to elementary bodies; were cidal at a concentration of > or =20 microM; inhibited all Chlamydiaceae tested; and could inhibit the development of C. trachomatis as determined by the yield of progeny when they were added up to 24 h postinfection. INP 0341 was able to affect the expression of several T3S genes. Compared to the expression in control cultures, lcrH-1, copB, and incA, all middle- to late-expressed T3S genes, were not expressed in the INP 0341-treated cultures 24 to 36 h postinfection. Iron, supplied as ferrous sulfate, as ferric chloride, or as holo-transferrin, was able to negate the antichlamydial properties of the INPs. In contrast, apo-transferrin and other divalent metal ions tested were not able to reverse the inhibitory effect of the INPs. In conclusion, the potent antichlamydial activity of INPs is directly or indirectly linked with iron, and this inhibition of Chlamydia has an effect on the T3S system of this intracellular pathogen.

Development of diabetes in non-obese diabetic mice promotes Chlamydia pneumoniae dissemination from lung to peripheral blood

We examined a possible association between development of diabetes in non-obese diabetic (NOD) mice and dissemination of Chlamydia (Chlamydophila) pneumoniae from lung to peripheral blood. By real-time reverse transcription-polymerase chain reaction (RT-PCR) with primers for C. pneumoniae 16S rRNA, following multiple intranasal inoculations, we detected bacteria in lung in NOD mice with diabetes (38.5%) as well as Institute of Cancer Research, USA (ICR) mice (40%), but prevalence of bacteria in NOD mice without diabetes (pre-diabetic NOD mice and non-diabetic retired NOD mice) was very low (4.8%). The bacteria were only detected in peripheral blood mononuclear cells (PBMCs) cultured with hydrocortisone of the NOD mice with diabetes (53.8%). Results of immunostaining with fluorescein isothiocyanate-conjugated antichlamydia monoclonal antibody also showed the presence of bacterial antigens in the lungs and the PBMCs judged as positive by the RT-PCR. However, C. pneumoniae from cultured PBMCs of all NOD mice was undetected by cultivation method with inclusion-forming units assay. In addition, no influence of C. pneumoniae intranasal inoculation on development of diabetes in NOD mice was confirmed. Thus, the development of diabetes in NOD mouse appears to be one of critical factors for promoting the dissemination of C. pneumoniae from lung to peripheral blood.

Introduction of a validation concept for a PCR-based Mycoplasma detection assay

BACKGROUND

Mycoplasma contamination is amongst the most frequently occurring problems associated with cell cultures. In order to meet the legal requirements (European Pharmacopoeia and FDA) for Mycoplasma testing of cell lines and therapeutics, we have developed a PCR-based method to detect mycoplasms and introduce a validation concept.

METHODS

The PCR assay specifically amplifies a 280-bp DNA fragment of the gene coding for the 16S rDNA. Simultaneous amplification of an artificial oligonucleotide containing primer-binding sites allowed control of the efficacy of the PCR. The validation of the PCR assay was performed with two Mycoplasma reference strains, M. orale and M. pneumoniae. The validation concept included (i) cultivation of M. orale and M. pneumoniae in medium with an indicator for bacterial metabolism, (ii) determination of the color-changing units (CCU) in repeated dilution experiments and (iii) correlation of the PCR results with CCU values.

RESULTS

The detection range was found to include all Mycoplasma species most commonly found in cell cultures. The analytical sensitivity of the PCR was the CCU equivalent of 100 for M. orale and M. pneumoniae. Probit analysis revealed a detection probability of 9% for a mean concentration of 1222 (935-1844) CCU/mL for M. pneumoniae and 2547 (1584-10,352) CCU/mL for M. orale.

DISCUSSION

The validation of the Mycoplasma detection assay supported PCR as an attractive diagnostic tool that will help manage the important issue of Mycoplasma contamination of cell cultures.

Localization of TLR2 and MyD88 to Chlamydia trachomatis inclusions. Evidence for signaling by intracellular TLR2 during infection with an obligate intracellular pathogen

Chlamydia trachomatis is an obligate intracellular gram-negative pathogen and the etiologic agent of significant ocular and genital tract diseases. Chlamydiae primarily infect epithelial cells, and the inflammatory response of these cells to the infection directs both the innate and adaptive immune response. This study focused on determining the cellular immune receptors involved in the early events following infection with the L2 serovar of C. trachomatis. We found that dominant negative MyD88 inhibited interleukin-8 (IL-8) secretion during a productive infection with chlamydia. Furthermore, expression of Toll-like receptor (TLR)-2 was required for IL-8 secretion from infected cells, whereas the effect of TLR4/MD-2 expression was minimal. Cell activation was dependent on infection with live, replicating bacteria, because infection with UV-irradiated bacteria and treatment of infected cells with chloramphenicol, but not ampicillin, abrogated the induction of IL-8 secretion. Finally, we show that both TLR2 and MyD88 co-localize with the intracellular chlamydial inclusion, suggesting that TLR2 is actively engaged in signaling from this intracellular location. These data support the role of TLR2 in the host response to infection with C. trachomatis. Our data further demonstrate that TLR2 and the adaptor MyD88 are specifically recruited to the bacterial or inclusion membrane during a productive infection with chlamydia and provide the first evidence that intracellular TLR2 is responsible for signal transduction during infection with an intracellular bacterium.

MyD88 is pivotal for the early inflammatory response and subsequent bacterial clearance and survival in a mouse model of Chlamydia pneumoniae pneumonia

Chlamydia pneumoniae is the causative agent of respiratory tract infections and a number of chronic diseases. Here we investigated the involvement of the common TLR adaptor molecule MyD88 in host responses to C. pneumoniae-induced pneumonia in mice. MyD88-deficient mice were severely impaired in their ability to mount an acute early inflammatory response toward C. pneumoniae. Although the bacterial burden in the lungs was comparable 5 days after infection, MyD88-deficient mice exhibited only minor signs of pneumonia and reduced expression of inflammatory mediators. MyD88-deficient mice were unable to up-regulate proinflammatory cytokines and chemokines, demonstrated delayed recruitment of CD8+ and CD4+ T cells to the lungs, and were unable to clear the pathogen from their lungs at day 14. At day 14 the MyD88-deficent mice developed a severe, chronic lung inflammation with elevated IL-1beta and IFN-gamma leading to increased mortality, whereas wild-type mice as well as TLR2- or TLR4-deficient mice recovered from acute pneumonia and did not show delayed bacterial clearance. Thus, MyD88 is essential to recognize C. pneumoniae infection and initiate a prompt and effective immune host response against this organism leading to clearance of bacteria from infected lungs.

Cytokine response of lymphocytes persistently infected with Chlamydia pneumoniae

Chlamydia pneumoniae infection of lymphocytes in blood has been documented, and it is apparent that control of this pathogen in lymphocytes as well as immune functions of the infected lymphocytes may be critical in the development of chronic inflammatory diseases associated with infection by this bacterium. Since immune function of lymphocytes infected with C. pneumoniae has not been well studied, the cytokine response of lymphocytes infected with this pathogen was analyzed using an in vitro infection model of the Molt-4 human lymphoid cell line. C. pneumoniae infection of the cells showed a persistent infection without any vigorous growth of the bacteria. Analysis of the cytokine response of the cells persistently infected with C. pneumoniae showed minimum induction of inflammatory cytokine TNF-alpha message, determined by real-time reverse transcription (RT)-PCR in the lymphocytes, even though the infection of THP-1 monocytic cells showed a marked induction of this cytokine messages. BIC (a lymphocyte activation marker gene) as well as IFN-gamma messages were also minimally induced by the infection in Molt-4 lymphocytes. In contrast, constitutive expression of interleukin 8 (IL-8) messages of Molt-4 cells was suppressed by the infection. Thus, these results suggest that lymphocytes persistently infected with C. pneumoniae may have attenuated cytokine responses.

Interaction between components of the type III secretion system of Chlamydiaceae

Members of the family Chlamydiaceae possess at least 13 genes, distributed throughout the chromosome, that are homologous with genes of known type III secretion systems (TTS). The aim of this study was to use putative TTS proteins of Chlamydophila pneumoniae, whose equivalents in other bacterial TTS function as chaperones, to identify interactions between chlamydial proteins. Using the BacterioMatch Two-Hybrid Vector system (Stratagene, La Jolla, Calif.), lcrH-2 and sycE, positions 1021 and 0325, respectively, from C. pneumoniae CM-1 were used as "bait" to identify target genes (positions 0324, 0705, 0708, 0808 to 0810, 1016 to 1020, and 1022) in close proximity on the chromosome. Interaction between the products of the lcrH-2 (1021) and lcrE (copN) (0324) genes was detected and confirmed by pull-down experiments and enzyme immunoassays using recombinant LcrH-2 and LcrE. As further confirmation of this interaction, the homologous genes from Chlamydia trachomatis, serovar E, and Chlamydophila psittaci, Texas turkey, were also cloned in the two-hybrid system to determine if LcrH-2 and LcrE would interact with their orthologs in other species. Consistent with their genetic relatedness, LcrH-2 from C. pneumoniae interacted with LcrE produced from the three species of Chlamydiaceae; LcrH-2 from C. psittaci reacted with LcrE from C. pneumoniae but not from C. trachomatis; and C. trachomatis LcrH-2 did not react with LcrE from the other two species. Deletions from the N and C termini of LcrE from C. pneumoniae identified the 50 C-terminal amino acids as essential for the interaction with LcrH-2. Thus, it appears that in the Chlamydiaceae TTS, LcrH-2 interacts with LcrE, and therefore it may serve as a chaperone for this protein.

Chlamydia pneumoniae induces aponecrosis in human aortic smooth muscle cells

Background

The intracellular bacterium Chlamydia pneumoniae is suspected to play a role in formation and progression of atherosclerosis. Many studies investigated cell death initiation versus inhibition by Chlamydia pneumoniae in established cell lines but nothing is known in primary human aortic smooth muscle cells, a cell type among others known to be involved in the formation of the atherosclerotic plaque. Type of cell death was analyzed by various methods in primary aortic smooth muscle cells after infection with Chlamydia pneumoniae to investigate a possible pathogenic link in atherosclerosis.

Results

Chlamydiae were found to be localized up to 72 h post infection in aortic smooth muscle cells either as single bacteria or inside of large inclusions. Quantification of host cell death by lactate dehydrogenase release assay revealed strictly dose and time dependent lysis for all tested isolates of Chlamydia pneumoniae. Phosphatidylserine exposure was detected by flow cytometry in Chlamydia pneumoniae infected cells. Ultrastructure of Chlamydia pneumoniae infected human aortic smooth muscle cells showed extensive membrane- and organelle damage, chromatin condensation but no nuclear fragmentation. DNA fragmentation as well as cell membrane permeability was analyzed by TUNEL and NHS-biotin staining and occurred exclusively in cells carrying Chlamydia pneumoniae spots but not in smooth muscle cells with inclusions. These morphological features of cell death were not accompanied by an activation of caspase-3 as revealed by analysis of enzyme activity but involved mitochondrial membrane depolarization as shown by TMRE uptake and release of cytochrome c from mitochondria.

Conclusion

This study provides evidence that Chlamydia pneumoniae induce a spot like infection in human aortic smooth muscle cells, which results in a chimeric cell death with both apoptotic and necrotic characteristics. This aponecrotic cell death may assist chronic inflammation in atherosclerotic blood vessels.

Murine oviduct epithelial cell cytokine responses to Chlamydia muridarum infection include interleukin-12-p70 secretion

Epithelial cells play an important role in host defense as sentinels for invading microbial pathogens. Chlamydia trachomatis is an intracellular bacterial pathogen that replicates in reproductive tract epithelium. Epithelial cells lining the reproductive tract likely play a key role in triggering inflammation and adaptive immunity during Chlamydia infections. For this report a murine oviduct epithelial cell line was derived in order to determine how epithelial cells influence innate and adaptive immune responses during Chlamydia infections. As expected, oviduct epithelial cells infected by Chlamydia muridarum produced a broad spectrum of chemokines, including CXCL16, and regulators of the acute-phase response, including interleukin-1alpha (IL-1alpha), IL-6, and tumor necrosis factor alpha. In addition, infected epithelial cells expressed cytokines that augment gamma interferon (IFN) production, including IFN-alpha/beta and IL-12-p70. To my knowledge this is the first report of a non-myeloid/lymphoid cell type making IL-12-p70 in response to an infection. Equally interesting, infected epithelial cells significantly upregulated transforming growth factor alpha precursor expression, suggesting a mechanism by which they might play a direct role in the pathological scarring seen as a consequence of Chlamydia infections. Data from these in vitro studies predict that infected oviduct epithelium contributes significantly to host innate and adaptive defenses but may also participate in the immunopathology seen with Chlamydia infections.

Prevalence of viable Chlamydia pneumoniae in peripheral blood mononuclear cells of healthy blood donors

BACKGROUND

Demonstration of viable Chlamydia (Chlamydophila) pneumoniae in peripheral blood mononuclear cells (PBMNCs) is essential to understand the involvement of C. pneumoniae in atherosclerosis. Nevertheless, the prevalence of viable C. pneumoniae in the blood of healthy donors has not yet been studied.

STUDY DESIGN AND METHODS

The presence of C. pneumoniae transcript in PBMNCs from blood of healthy human donors was assessed by real-time reverse transcription-polymerase chain reaction (RT-PCR) with primers for C. pneumoniae 16S rRNA, which is more sensitive than genomic-DNA-based analysis, and by the use of staining with fluorescein isothiocyanate-conjugated chlamydia monoclonal antibody (MoAb).

RESULTS

Thirteen of 70 donors (18.5%) showed the presence of bacterial transcript in cultured PBMNCs. The prevalence of bacterial detection and bacterial numbers was significantly increased in PBMNC cultures incubated with cycloheximide. Immunostaining of PBMNCs with antichlamydial MoAb also revealed the presence of bacterial antigen in the PBMNCs judged as positive. Nevertheless, cultivation of C. pneumoniae from all PCR-positive donors was unsuccessful. There was no significant correlation between the presence of chlamydia and either sex or current smoking habits. A possible age variation, however, in the presence of chlamydia in blood of healthy donors was suggested by the results obtained.

CONCLUSION

The bacterial transcripts in PBMNCs obtained from healthy donors were detected by the RT-PCR method. Viable C. pneumoniae may be present in healthy human PBMNCs.

In vitro activities of garenoxacin and levofloxacin against Chlamydia pneumoniae are not affected by presence of Mycoplasma DNA

We studied 20 Chlamydia pneumoniae isolates obtained from respiratory sites and atheroma tissue of patients from various geographic areas to determine the susceptibilities of these isolates to a new des-fluoroquinolone, garenoxacin, and to levofloxacin. In addition, we assessed the cultures with these isolates by PCR for the presence or absence of Mycoplasma sp. DNA. Both the MIC at which 90% of isolates are inhibited (MIC(90)) and the minimal bactericidal concentration at which 90% of isolates are killed (MBC(90)) for garenoxacin were 0.06 microg/ml, and both the MIC(90) and the MBC(90) for levofloxacin were 2.0 microg/ml. The activity of garenoxacin against C. pneumoniae was 32-fold greater than that of levofloxacin. Mycoplasma sp. DNA was detected by PCR in 17 of 20 cultures. Mycoplasma amplicons from five Mycoplasma DNA-positive C. pneumoniae cultures were sequenced and found to represent four Mycoplasma species. Our data demonstrate that C. pneumoniae cultures frequently contain Mycoplasma DNA and that its presence in C. pneumoniae cultures does not appear to affect the susceptibility results for the two fluoroquinolones that we tested.

Simultaneous detection and identification of common cell culture contaminant and pathogenic mollicutes strains by reverse line blot hybridization

We have developed a reverse line blot (RLB) hybridization assay to detect and identify the commonest mollicutes causing cell line contamination (Mycoplasma arginini, Mycoplasma fermentans, Mycoplasma hyorhinis, Mycoplasma orale, and Acholeplasma laidlawii) and human infection (Mycoplasma pneumoniae, Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma parvum, and Ureaplasma urealyticum). We developed a nested PCR assay with "universal" primers targeting the mollicute 16S-23S rRNA intergenic spacer region. Amplified biotin-labeled PCR products were hybridized to membrane-bound species-specific oligonucleotide probes. The assay correctly identified reference strains of 10 mollicute species. Cell cultures submitted for detection of mollicute contamination, clinical specimens, and clinical isolates were initially tested by PCR assay targeting a presumed mollicute-specific sequence of the 16S rRNA gene. Any that were positive were assessed by the RLB assay, with species-specific PCR assay as the reference method. Initially, 100 clinical and 88 of 92 cell culture specimens gave concordant results, including 18 in which two or more mollicute species were detected by both methods. PCR and sequencing of the 16S-23S rRNA intergenic spacer region and subsequent retesting by species-specific PCR assay of the four cell culture specimens for which results were initially discrepant confirmed the original RLB results. Sequencing of amplicons from 12 cell culture specimens that were positive in the 16S rRNA PCR assay but negative by both the RLB and species-specific PCR assays failed to identify any mollicute species. The RLB hybridization assay is sensitive and specific and able to rapidly detect and identify mollicute species from clinical and cell line specimens.

Micromanipulation of the Chlamydia pneumoniae inclusion: implications for cloning and host-pathogen interactions

The Chlamydia trachomatis inclusion is fragile, rendering it incompatible to micromanipulation. We show that the Chlamydia pneumoniae inclusion differs, being resistant to micromanipulation as shown by direct microinjection of the infected host cytosol or the inclusion itself. We have used micromanipulation to clone C. pneumoniae and to free it from mycoplasma contamination.

Involvement of nicotinic acetylcholine receptors in controlling Chlamydia pneumoniae growth in epithelial HEp-2 cells

Nicotinic acetylcholine receptors (nAChRs) play an essential role in neurotransmission. Recent studies have indicated that nAChRs may be involved in the regulation of some bacterial infections through immunological mechanisms in macrophages. However, the regulation of infection with Chlamydia pneumoniae, which is a ubiquitous pneumonia-causing bacterium, by an nAChR-mediated mechanism is still unclear. In the present study, it was found that stimulation of nAChRs with ligands such as nicotine and acetylcholine altered the growth of C. pneumoniae in epithelial HEp-2 cells. Thus, the results revealed a possible pathophysiological role of nAChRs in the regulation of intracellular bacterial infection.

Monitoring intracellular replication of Chlamydophila (Chlamydia) pneumoniae in cell cultures and comparing clinical samples by real-time PCR

Strains of Chlamydophila pneumoniae may be associated with respiratory disease or atherosclerosis. Two real-time quantitative PCR assays targeting the species-specific genes Cpn0278 and ArgR were developed to compare the in vitro growth of respiratory strains AR39 and K6 with that of atherosclerotic strain A03 and to quantify C. pneumoniae in clinical samples. A third real-time PCR assay was designed to assess contamination with Mycoplasma spp. The assays targeting C. pneumoniae detected DNA concentrations corresponding to 10(4) to 10(-4) inclusion-forming units (IFU)/reaction and were highly specific. AR39 exhibited the longest lag phase and period of exponential growth; K6 augmented growth rates at higher inocula; and A03 grew at highest rates. Contamination with Mycoplasma spp. of AR39 and A03 unlikely accounted for growth differences between them. Numbers of IFU in C. pneumoniae-positive respiratory secretions varied within 4 to 5 orders of magnitude. The assays described may prove valuable for pathogenicity studies.