Assaying Chlamydia pneumoniae Persistence in Monocyte-Derived Macrophages Identifies Dibenzocyclooctadiene Lignans as Phenotypic Switchers.

Antibiotic-tolerant persister bacteria involve frequent treatment failures, relapsing infections and the need for extended antibiotic treatment. The virulence of an intracellular human pathogen C. pneumoniae is tightly linked to its propensity for persistence and means for its chemosensitization are urgently needed. In the current work, persistence of C. pneumoniae clinical isolate CV6 was studied in THP-1 macrophages using quantitative PCR and quantitative culture. A dibenzocyclooctadiene lignan schisandrin reverted C. pneumoniae persistence and promoted productive infection. The concomitant administration of schisandrin and azithromycin resulted in significantly improved bacterial eradication compared to sole azithromycin treatment. In addition, the closely related lignan schisandrin C was superior to azithromycin in eradicating the C. pneumoniae infection from the macrophages. The observed chemosensitization of C. pneumoniae was associated with the suppression of cellular glutathione pools by the lignans, implying to a previously unknown aspect of chlamydia-host interactions. These data indicate that schisandrin lignans induce a phenotypic switch in C. pneumoniae, promoting the productive and antibiotic-susceptible phenotype instead of persistence. By this means, these medicinal plant -derived compounds show potential as adjuvant therapies for intracellular bacteria resuscitation.

Impact of dibenzocyclooctadiene lignans from Schisandra chinensis on the redox status and activation of human innate immune system cells.

Redox signaling has been established as an essential component of inflammatory responses, and redox active compounds are of interest as potential immunomodulatory agents. Dibenzocyclooctadiene lignans isolated from Schisandra chinensis, a medicinal plant with widespread use in oriental medicine, have been implicated to possess immunomodulatory properties but their effects on the human innate immune system cells have not been described. In this contribution, data are presented on the impact of schisandrin, schisandrin B and schisandrin C on human monocytic cell redox status, as well as their impact on dendritic cell maturation and T cell activation capacity and cytokine production. In THP-1 cells, levels of intracellular reactive oxygen species (ROS) were elevated after 1 h exposure to schisandrin. Schisandrin B and schisandrin C decreased cellular glutathione pools, which is a phenotype previously reported to promote anti-inflammatory functions. Treatment of human primary monocytes with the lignans during their maturation to dendritic cells did not have any effect on the appearance of surface markers HLA-DR and CD86 but schisandrin B and schisandrin C suppressed the secretion of cytokines interleukin (IL)-6, IL-10 and IL-12 by the mature dendritic cells. Dendritic cells maturated in presence of schisandrin C were further cocultured with naïve CD4+ T cells, resulting in reduced IL-12 production. In THP-1 cells, schisandrin B and schisandrin C reduced the IL-6 and IL-12 production triggered by E. coli lipopolysaccharide and IL-12 production induced by an infection with Chlamydia pneumoniae. In conclusion, the studied lignans act as immunomodulatory agents by altering the cytokine secretion, but do not interfere with dendritic cell maturation. And the observed effects may be associated with the ability of the lignans to alter cellular redox status.

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.

Identification of a ubiG-like gene involved in ubiquinone biosynthesis from Chlamydophila pneumoniae AR39.

AIMS: To investigate if one hypothetical protein from Chlamydophila pneumoniae AR39 exerts UbiG-like function by complementary experiments. METHODS AND RESULTS: Proteins UbiG have a signature S-adenosylmethionine-binding motif compared with other methyltransferases. Probing with the conserved motif, one hypothetical protein from C. pneumoniae AR39 was proposed to be a UbiG-like protein. The protein encoding the gene was used to swap its counterpart in Escherichia coli, and its expression in resultant strain DYCG was confirmed by RT-PCR. Strain DYCG grew on succinate as a carbon source, and rescued ubiquinone content in vivo, while the ubiG deletion strain DYK did not. CONCLUSIONS: Results indicate that the putative protein from C. pneumoniae exerts a UbiG-like function involved in ubiquinone biosynthesis. SIGNIFICANCE AND IMPACT OF THE STUDY: Identification of the ubiG-like gene will facilitate research on ubiquinone biosynthesis and aerobic respiration in the genus Chlamydophila owing to the important function of ubiquinone in vivo.

Serotonin and melatonin, neurohormones for homeostasis, as novel inhibitors of infections by the intracellular parasite chlamydia.

OBJECTIVES: Chlamydiae are obligate intracellular bacteria, causing a variety of diseases, i.e. pneumonia, sexually transmitted disease, conjunctivitis and zoonosis. Tryptophan depletion by interferon-gamma (IFN-gamma) is the most important host defence system against chlamydial infection. Thus chlamydial tryptophan metabolism is thought to play key roles for IFN-gamma resistance, persistent infection and host/tissue tropisms. We tested tryptophan derivatives for activity against chlamydia-infected cells. METHODS: Rates of chlamydial infection and sizes of the inclusions were evaluated by in vitro infection using three Chlamydiaceae species, Chlamydia trachomatis, Chlamydophila pneumoniae and Chlamydophila felis, which show significant divergence of tryptophan synthesis genes and different susceptibilities to IFN-gamma. RESULTS: Melatonin and serotonin, which are recognized as neural hormones for maintenance of organism homeostasis, reduced chlamydial infection but not other bacterial growth tested here. Unlike IFN-gamma, melatonin limited infection of all three chlamydiae and the effects were not recovered by tryptophan supplementation. Melatonin treatment only of host cells could diminish infection and the infection reduction was neutralized by a pertussis toxin, an inhibitor of G proteins. Ligands of melatonin and serotonin receptors also hampered infection. CONCLUSIONS: Inhibition mechanisms of chlamydial infection by melatonin and serotonin appear to be different from those of IFN-gamma and involve specific G-protein-coupled receptors. Melatonin is deemed to inhibit early progression of the chlamydial development cycle, such as establishment of intracellular infection and/or conversion from elementary body to reticulate body. Utilization of melatonin, serotonin or their derivatives may be advantageous for harmless prevention of chlamydial infection.

Chlamydia pneumoniae arthritis in a patient with common variable immunodeficiency.

BACKGROUND: Arthritis is an important and sometimes life-threatening complication in patients with common variable immunodeficiency (CVID). OBJECTIVE: To describe a patient with CVID and arthritis due to Chlamydia pneumoniae, which is usually regarded as a respiratory tract pathogen and has not previously been detected in the synovial fluid by cell culture technique. METHODS: Routine bacteriologic, virologic, mycologic, and tuberculosis cultures were performed. The patient's synovial fluid was examined for fastidious organisms that might be causative pathogens of arthritis, such as chlamydiae, and special cell culture methods were used. Serologic tests were performed to determine viral and bacteriologic etiology. RESULTS: The patient had a history of recurrent respiratory tract infections, and the latest exacerbation was followed by arthritis. Cytologic examination of the fluid yielded abundant lymphocytes. Chlamydia pneumoniae was detected in synovial fluid specimens by cell culture technique. Her nasopharyngeal swab and sputum culture specimens were also positive for this pathogen. She was diagnosed as having arthritis caused by C pneumoniae and was given antibiotherapy. CONCLUSION: Chlamydia pneumoniae should be kept in mind as a causative pathogen in patients with CVID and arthritis, especially when effusion fluid is full of lymphocytes rather than polymorphonuclear cells and no organism is grown on routine cultures.

In vitro inhibitory effects of tea polyphenols on the proliferation of Chlamydia trachomatis and Chlamydia pneumoniae.

In vitro inhibitory effects of tea polyphenols on Chlamydia trachomatis and C. pneumoniae were investigated. A product of tea polyphenols, Polyphenon 70S was used. Chlamydial strains used were C. trachomatis D/UW-3/Cx and L(2)/434/Bu, and C. pneumoniae AR-39 and AC-43 strains. HeLa229 cells and HL cells were used for cultivation of C. trachomatis and C. pneumoniae, respectively. In the post-inoculation method, no inclusions of C. trachomatis were observed at 0.5 mg/ml of Polyphenon 70S. However, the toxicity of Polyphenon 70S was noted in HeLa229 cells and HL cells at a concentration of 0.25 mg/ml. In the pre-inoculation method, no toxic effects of Polyphenon 70S on the cells were noted. Complete inhibition of C. trachomatis D and L(2) was noted at concentrations of 1.6 and 0.4 mg/ml, respectively. With C. pneumoniae strains, the end points were 0.8 and 1.6 mg/ml for AR-39 and AC-43, respectively. Our findings encouraged the application of tea polyphenols for topical usage.

A novel method for isolation of Chlamydia pneumoniae by treatment with trypsin or EDTA.

To establish a novel method for the efficient isolation of Chlamydia pneumoniae, experiments were performed to determine the effects of EDTA or trypsin treatment of C. pneumoniae on its adsorption and inclusion body formation. Treatment of C. pneumoniae with 0.1% trypsin or 1 mM EDTA significantly increased inclusion body-forming activity from 8,000- to 10,000-fold higher than that of the control. C. pneumoniae was successfully isolated in cultured cells which were inoculated with clinical specimens after treatment with 0.1% trypsin.