Commonly Prescribed β-lactam Antibiotics Induce C.trachomatis Persistence/Stress in Culture at Physiologically Relevant Concentrations

Chlamydia trachomatis, the most common bacterial sexually transmitted disease agent worldwide, enters a viable, non-dividing and non-infectious state (historically termed persistence and more recently referred to as the chlamydial stress response) when exposed to penicillin G in culture. Notably, penicillin G-exposed chlamydiae can reenter the normal developmental cycle upon drug removal and are resistant to azithromycin-mediated killing. Because penicillin G is less frequently prescribed than other ß-lactams, the clinical relevance of penicillin G-induced chlamydial persistence/stress has been questioned. The goal of this study was to determine whether more commonly used penicillins also induce C. trachomatis serovar E persistence/stress. All penicillins tested, as well as clavulanic acid, induced formation of aberrant, enlarged reticulate bodies (RB) (called aberrant bodies or AB) characteristic of persistent/stressed chlamydiae. Exposure to the penicillins and clavulanic acid also reduced chlamydial infectivity by \u3e95%. None of the drugs tested significantly reduced chlamydial unprocessed 16S rRNA or genomic DNA accumulation, indicating that the organisms were viable, though non-infectious. Finally, recovery assays demonstrated that chlamydiae rendered essentially non-infectious by exposure to ampicillin, amoxicillin, carbenicillin, piperacillin, penicillin V, and clavulanic acid recovered infectivity after antibiotic removal. These data definitively demonstrate that several commonly used penicillins induce C. trachomatis persistence/stress at clinically relevant concentrations

The Type I Interferon Receptor Is Not Required for Protection in the Chlamydia Muridarum and HSV-2 Murine Super-Infection Model

Chlamydia trachomatis/HSV-2 vaginal co-infections are seen clinically, suggesting that these sexually transmitted pathogens may interact. We previously established an intravaginal Chlamydia muridarum/HSV-2 super-infection model and observed that chlamydial pre-infection protects mice from a subsequent lethal HSV-2 challenge. However, the mechanism of protection remains unknown. The type I interferon, IFN-β, binds to the type I interferon receptor (IFNR), elicits a host cellular antiviral response and inhibits HSV replication in vitro and in vivo. Previous studies have demonstrated that C. muridarum infection stimulates genital tract (GT) IFN-β production; therefore, we hypothesized that chlamydial pre-infection protects mice from HSV-2 challenge via the IFN-β/IFNR-induced antiviral response. To test this prediction, we quantified IFN-β levels in vaginal swab samples. Detection of IFN-β in C. muridarum singly infected, but not in mock-infected animals, prompted the use of the super-infection model in IFNR knockout (IFNR-/-) mice. We observed that C. muridarum pre-infection reduces HSV-2-induced mortality by 40% in wild-type mice and by 60% IFNR-/-mice. Severity of HSV-2 disease symptoms and viral shedding was also similarly reduced by C. muridarum pre-infection. These data indicate that, while chlamydial infection induces GT production of IFN-β, type I IFN-induced antiviral responses are likely not required for the observed protective effect

Host Nectin-1 Promotes Chlamydial Infection in the Female Mouse Genital Tract, But is Not Required for Infection in a Novel Male Murine Rectal Infection Model

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Chlamydia trachomatis is the most common bacterial sexually transmitted pathogen, but more than 70% of patients fail to seek treatment due to the asymptomatic nature of these infections. Women suffer from numerous complications from chronic chlamydial infections, which include pelvic inflammatory disease and infertility. We previously demonstrated in culture that host cell nectin-1 knockdown significantly reduced chlamydial titers and inclusion size. Here, we sought to determine whether nectin-1 was required for chlamydial development in vivo by intravaginally infecting nectin-1-/- mice with Chlamydia muridarum and monitoring chlamydial shedding by chlamydial titer assay. We observed a significant reduction in chlamydial shedding in female nectin-1-/- mice compared to nectin-1+/+ control mice, an observation that was confirmed by PCR. Immunohistochemical staining in mouse cervical tissue confirmed that there are fewer chlamydial inclusions in Chlamydia-infected nectin-1-/- mice. Notably, anorectal chlamydial infections are becoming a substantial health burden, though little is known regarding the pathogenesis of these infections. We therefore established a novel male murine model of rectal chlamydial infection, which we used to determine whether nectin-1 is required for anorectal chlamydial infection in male mice. In contrast to the data from vaginal infection, no difference in rectal chlamydial shedding was observed when male nectin-1+/+ and nectin-1-/- mice were compared. Through the use of these two models, we have demonstrated that nectin-1 promotes chlamydial infection in the female genital tract but does not appear to contribute to rectal infection in male mice. These models could be used to further characterize tissue and sex related differences in chlamydial infection

Quantification of Progesterone and 17-β Estradiol in Mouse Serum by Liquid Chromatography-Tandem Mass Spectrometry

Quantification of progesterone and 17-β estradiol in mouse serum by liquid chromatography-tandem mass spectrometry Authors: Benjamin Kennard, Allison Cobble, Amy Gravitte, Keleigh Galloway, Jen Kintner, Jennifer Hall, Stacy Brown Introduction: In the United States, Chlamydia trachomatis is a commonly appearing sexually transmitted infection1. It affects the U.S. healthcare system to a tune of about $500 million dollars annually2. In women, it generally appears asymptomatic and can lead to severe secondary complications such as pelvic inflammatory diseases or infertility1. Female sex hormones, estrogen and progesterone, are being identified to have a role in chlamydial infection. Specifically, this study aims to create quantification methods to detect levels of estrogen and progesterone in mice, infected with Chlamydia muridarum, plasma samples. Methods: Progesterone samples were prepared using solid-liquid extraction (SLE+) cartridges with ethyl acetate as the elution solvent. Estradiol samples were prepared using liquid-liquid extraction (LLE) with methyl tert-butyl ether and subsequent derivatization with DMIS. Following sample preparation, hormones were quantified in samples using LC-MS/MS with a gradient elution of 1 mM ammonium fluoride in water and acetonitrile. The separation was achieved using a UCT C18 column (100 x 21.mm, 1.8 μm particle size) maintained at 50oC. The mass spectrometer was set up to isolate molecular ions for progesterone (m/z 315.0910) and derivatized estradiol (m/z 431.1835). Quantification was facilitated by the use of deuterium-labeled internal standards and their corresponding molecular ions in the mass spectrometer (d9-progesterone; m/z 324.1230 and d5-estradiol; m/z 436.2922). Results: Several aspects of the assay presented have been optimized for maximum analyte recovery and analytical sensitivity, including column choice, mobile phase, derivatizing agents for estradiol, and extraction protocols for progesterone. The LC-MS/MS method was investigated for precision and accuracy over three separate days. The dynamic range of the progesterone assay was 5 – 100 ng/mL, with a limit of detection of 1 ng/mL. Likewise, the estradiol assay was linear in the range of 5 – 100 ng/mL, with a limit of detection of 0.5 ng/mL. The average precision, represented by % RSD was 0.74 – 8.5% and 6.3 – 13.4% for progesterone and estradiol, respectively. The accuracy of the method, represented by % error was 1.6 – 14.4% and 4.0 – 10.5% for progesterone and estradiol, respectively. Successful validation was defined as \u3c 15% RSD and error (\u3c 20% at the limit of quantification), per current FDA Guidelines. Conclusions: The developed LC-MS/MS method is specific for progesterone and estradiol, and the extraction is suitable for preparation of mouse serum samples. This assay could be successfully applied to hormone quantification in mouse samples to support the investigation of the link between chlamydia infection and hormone levels in female animals. References 1. Chlamydia - 2017 Sexually Transmitted Diseases Surveillance. https://www.cdc.gov/std/stats17/chlamydia.htm. Accessed October 23, 2018. 2. Owusu-Edusei K, Chesson HW, Gift TL, et al. The Estimated Direct Medical Cost of Selected Sexually Transmitted Infections in the United States, 2008. Sex Transm Dis. 2013;40(3):197-201. doi:10.1097/OLQ.0b013e318285c6d

Planar Cell Polarity Enables Posterior Localization of Nodal Cilia and Left-Right Axis Determination during Mouse and Xenopus Embryogenesis

Left-right asymmetry in vertebrates is initiated in an early embryonic structure called the ventral node in human and mouse, and the gastrocoel roof plate (GRP) in the frog. Within these structures, each epithelial cell bears a single motile cilium, and the concerted beating of these cilia produces a leftward fluid flow that is required to initiate left-right asymmetric gene expression. The leftward fluid flow is thought to result from the posterior tilt of the cilia, which protrude from near the posterior portion of each cell's apical surface. The cells, therefore, display a morphological planar polarization. Planar cell polarity (PCP) is manifested as the coordinated, polarized orientation of cells within epithelial sheets, or as directional cell migration and intercalation during convergent extension. A set of evolutionarily conserved proteins regulates PCP. Here, we provide evidence that vertebrate PCP proteins regulate planar polarity in the mouse ventral node and in the Xenopus gastrocoel roof plate. Asymmetric anterior localization of VANGL1 and PRICKLE2 (PK2) in mouse ventral node cells indicates that these cells are planar polarized by a conserved molecular mechanism. A weakly penetrant Vangl1 mutant phenotype suggests that compromised Vangl1 function may be associated with left-right laterality defects. Stronger functional evidence comes from the Xenopus GRP, where we show that perturbation of VANGL2 protein function disrupts the posterior localization of motile cilia that is required for leftward fluid flow, and causes aberrant expression of the left side-specific gene Nodal. The observation of anterior-posterior PCP in the mouse and in Xenopus embryonic organizers reflects a strong evolutionary conservation of this mechanism that is important for body plan determination

Binding of Elementary Bodies by the Opportunistic Fungal Pathogen Candida albicansor Soluble β-Glucan, Laminarin, Inhibits Chlamydia Trachomatisinfectivity

Microbial interactions represent an understudied facet of human health and disease. In this study, the interactions that occur between Chlamydia trachomatis and the opportunistic fungal pathogen, Candida albicans were investigated. Candida albicans is a common component of the oral and vaginal microbiota responsible for thrush and vaginal yeast infections. Normally, Candida exist in the body as yeast. However, disruptions to the microbiota create conditions that allow expanded growth of Candida, conversion to the hyphal form, and tissue invasion. Previous studies have shown that a myriad of outcomes can occur when Candida albicans interacts with pathogenic bacteria. To determine if C. trachomatis physically interacts with C. albicans, we incubated chlamydial elementary bodies (EB) in medium alone or with C. albicans yeast or hyphal forms for 1 h. Following incubation, the samples were formaldehyde-fixed and processed for immunofluorescence assays using anti-chlamydial MOMP or anti- chlamydial LPS antibodies. Replicate samples were replenished with culture medium and incubated at 35°C for 0-120 h prior to fixation for immunofluorescence analysis or collection for EB infectivity assays. Data from this study indicates that both C. trachomatis serovar E and C. muridarum EB bind to C. albicans yeast and hyphal forms. This interaction was not blocked by pre-incubation of EB with the Candida cell wall components, mannan or β-glucans, suggesting that EB interact with a Candida cell wall protein or other structure. Bound EB remained attached to C. albicans for a minimum of 5 days (120 h). Infectivity assays demonstrated that EB bound to C. albicans are infectious immediately following binding (0h). However, once bound to C. albicans, EB infectivity decreased at a faster rate than EB in medium alone. At 6h post binding, 40% of EB incubated in medium alone remained infectious compared to only 16% of EB bound to C. albicans. Likewise, pre-incubation of EB with laminarin, a soluble preparation of β-glucan, alone or in combination with other fungal cell wall components significantly decreases chlamydial infectivity in HeLa cells. These data indicate that interactions between EB and C. albicans inhibit chlamydial infectivity, possibly by physically blocking EB interactions with host cell receptors

Binding of Elementary Bodies by the Opportunistic Fungal Pathogen Candida albicans or Soluble β-Glucan, Laminarin, Inhibits Chlamydia trachomatis Infectivity

Microbial interactions represent an understudied facet of human health and disease. In this study, the interactions that occur between Chlamydia trachomatis and the opportunistic fungal pathogen, Candida albicans were investigated. Candida albicans is a common component of the oral and vaginal microbiota responsible for thrush and vaginal yeast infections. Normally, Candida exist in the body as yeast. However, disruptions to the microbiota create conditions that allow expanded growth of Candida, conversion to the hyphal form, and tissue invasion. Previous studies have shown that a myriad of outcomes can occur when Candida albicans interacts with pathogenic bacteria. To determine if C. trachomatis physically interacts with C. albicans, we incubated chlamydial elementary bodies (EB) in medium alone or with C. albicans yeast or hyphal forms for 1 h. Following incubation, the samples were formaldehyde-fixed and processed for immunofluorescence assays using anti-chlamydial MOMP or anti- chlamydial LPS antibodies. Replicate samples were replenished with culture medium and incubated at 35°C for 0–120 h prior to fixation for immunofluorescence analysis or collection for EB infectivity assays. Data from this study indicates that both C. trachomatis serovar E and C. muridarum EB bind to C. albicans yeast and hyphal forms. This interaction was not blocked by pre-incubation of EB with the Candida cell wall components, mannan or β-glucans, suggesting that EB interact with a Candida cell wall protein or other structure. Bound EB remained attached to C. albicans for a minimum of 5 days (120 h). Infectivity assays demonstrated that EB bound to C. albicans are infectious immediately following binding (0h). However, once bound to C. albicans, EB infectivity decreased at a faster rate than EB in medium alone. At 6h post binding, 40% of EB incubated in medium alone remained infectious compared to only 16% of EB bound to C. albicans. Likewise, pre-incubation of EB with laminarin, a soluble preparation of β-glucan, alone or in combination with other fungal cell wall components significantly decreases chlamydial infectivity in HeLa cells. These data indicate that interactions between EB and C. albicans inhibit chlamydial infectivity, possibly by physically blocking EB interactions with host cell receptors

Chlamydial Pre-Infection Protects From Subsequent Herpes Simplex Virus-2 Challenge in a Murine Vaginal Super-Infection Model

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Chlamydia trachomatis and Herpes Simplex Virus-2 (HSV-2) genital tract co-infections have been reported in humans and studied in vitro but the clinical consequences are unknown. Limited epidemiologic evidence suggests that these co-infections could be more severe than single infections of either pathogen, but the host-pathogen interactions during co-infection remain uncharacterized. To determine whether disease progression and/or pathogen shedding differs between singly-infected and super-infected animals, we developed an in vivo super-infection model in which female BALB/c mice were vaginally infected with Chlamydia muridarum (Cm) followed later by HSV-2. Pre-infection with Chlamydia 3 or 9 days prior to HSV-2 super-infection conferred significant protection from HSV-2-induced neurologic disease and significantly reduced viral recovery compared to HSV-2 singlyinfected controls. Neither protection from mortality nor reduced viral recovery were observed when mice were i) super-infected with HSV-2 on day 27 post Cm; ii) infected with UV-irradiated Cm and super-infected with HSV-2; or iii) azithromycin-treated prior to HSV-2 super-infection. Therefore, protection from HSV-2-induced disease requires active infection with viable chlamydiae and is not observed after chlamydial shedding ceases, either naturally or due to antibiotic treatment. Thus, Chlamydia-induced protection is transient and requires the continued presence of chlamydiae or their components. These data demonstrate that chlamydial pre-infection can alter progression of subsequent HSV-2 infection, with implications for HSV-2 transmission from co-infected humans

Estrogen receptors affect Chlamydia muridarum infection in mice

Chlamydia trachomatis is a leading cause of bacterial genital infection in the US and worldwide. The chlamydial replication cycle is biphasic, meaning it enters the host cell as an infectious elementary body (EB), differentiates into an actively dividing reticulate body (RB) inside of a vacuole-like compartment, called a chlamydial inclusion, and differentiates back into EB form before exiting the host. Studies have demonstrated that estrogen aids Chlamydia infection in human and swine endometrial cells and in guinea pigs. Our prior data showed that antibody blockage of estrogen receptors or exposure to the ERβ antagonist tamoxifen in vitro decreased the development of chlamydial inclusions. Given these observations, we wanted to further examine the role of ER signaling on chlamydial infection in a murine model. We hypothesized that the absence of estrogen receptors would alter the establishment and/or progression of chlamydial infection in mice. To test this hypothesis, we compared C. muridarum infection in wild type (ERαWT or ERβWT) versus knockout (ERαKO or ERβKO) mice. Groups of eight ERαWT, ERβWT, ERαKO, or ERβKO mice were Depo-Provera treated seven days prior to vaginal infection with C. muridarum. Vaginal swabs were taken every three days for 21 days to monitor infection by EB titer analysis. Interestingly, titer data showed that peak EB shedding occurred earlier in the ERαKO mice compared to the ERαWT. At day 3 pi, EB shedding from ERαKO mice was 12-fold greater than shedding from ERαWT mice. On day 6, however, ERαWT mice shed \u3e3-fold more EB than ERαKO mice. Conversely, there was no significant difference observed in ERβKO versus ERβWT mice or in ERαKO versus ERβKO mice. In a subset of experiments, genital tracts were collected on day 9pi and processed for flow cytometry analysis of the immune response to infection. ERαKO mice had significantly more monocytes and macrophages than ERαWT and ERβKO mice, as well as significantly more T cells than ERβKO mice. There was no significant difference in the immune cells in ERβKO and ERβWT mice. Together, these data suggest that: 1) the absence of ERs in mice does not inhibit chlamydial infection as has been observed in human cells in vitro; and 2) C. muridarum infection progression is affected by ERα signaling, possibly via alterations in the immune response

Inhibition of Wnt Signaling Pathways Impairs Chlamydia trachomatis Infection in Endometrial Epithelial Cells

Chlamydia trachomatis infections represent the predominant cause of bacterial sexually transmitted infections. As an obligate intracellular bacterium, C. trachomatis is dependent on the host cell for survival, propagation, and transmission. Thus, factors that affect the host cell, including nutrition, cell cycle, and environmental signals, have the potential to impact chlamydial development. Previous studies have demonstrated that activation of Wnt/β-catenin signaling benefits C. trachomatis infections in fallopian tube epithelia. In cervical epithelial cells chlamydiae sequester β-catenin within the inclusion. These data indicate that chlamydiae interact with the Wnt signaling pathway in both the upper and lower female genital tract (FGT). However, hormonal activation of canonical and non-canonical Wnt signaling pathways is an essential component of cyclic remodeling in another prominent area of the FGT, the endometrium. Given this information, we hypothesized that Wnt signaling would impact chlamydial infection in endometrial epithelial cells. To investigate this hypothesis, we analyzed the effect of Wnt inhibition on chlamydial inclusion development and elementary body (EB) production in two endometrial cell lines, Ishikawa (IK) and Hec-1B, in nonpolarized cell culture and in a polarized endometrial epithelial (IK)/stromal (SHT-290) cell co-culture model. Inhibition of Wnt by the small molecule inhibitor (IWP2) significantly decreased inclusion size in IK and IK/SHT-290 cultures (p < 0.005) and chlamydial infectivity (p ≤ 0.01) in both IK and Hec-1B cells. Confocal and electron microscopy analysis of chlamydial inclusions revealed that Wnt inhibition caused chlamydiae to become aberrant in morphology. EB formation was also impaired in IK, Hec-1B and IK/SHT-290 cultures regardless of whether Wnt inhibition occurred throughout, in the middle (24 hpi) or late (36 hpi) during the development cycle. Overall, these data lead us to conclude that Wnt signaling in the endometrium is a key host pathway for the proper development of C. trachomatis