We developed an RNA-Seq-based method to simultaneously capture prokaryotic and eukaryotic expression profiles of cells infected with intracellular bacteria. As proof of principle, this method was applied to Chlamydia trachomatis-infected epithelial cell monolayers in vitro, successfully obtaining transcriptomes of both C. trachomatis and the host cells at 1 and 24 hours post-infection. Chlamydiae are obligate intracellular bacterial pathogens that cause a range of mammalian diseases. In humans chlamydiae are responsible for the most common sexually transmitted bacterial infections and trachoma (infectious blindness). Disease arises by adverse host inflammatory reactions that induce tissue damage & scarring. However, little is known about the mechanisms underlying these outcomes. Chlamydia are genetically intractable as replication outside of the host cell is not yet possible and there are no practical tools for routine genetic manipulation, making genome-scale approaches critical. The early timeframe of infection is poorly understood and the host transcriptional response to chlamydial infection is not well defined. Our simultaneous RNA-Seq method was applied to a simplified in vitro model of chlamydial infection. We discovered a possible chlamydial strategy for early iron acquisition, putative immune dampening effects of chlamydial infection on the host cell, and present a hypothesis for Chlamydia-induced fibrotic scarring through runaway positive feedback loops. In general, simultaneous RNA-Seq helps to reveal the complex interplay between invading bacterial pathogens and their host mammalian cells and is immediately applicable to any bacteria/host cell interaction.

Genomic analysis of the Chlamydiaceae has revealed a multigene family encoding large, putatively autotransported polymorphic membrane proteins (Pmps) with nine members in the sexually transmitted pathogen Chlamydia trachomatis. While various pathogenesis-related functions are emerging for the Pmps, observed genotypic and phenotypic variation among several chlamydial Pmps in various Chlamydia species has led us to hypothesize that the pmp gene repertoire is the basis of a previously undetected mechanism of antigenic variation. To test this hypothesis, we chose to examine the serologic response of C. trachomatis-infected patients to each Pmp subtype. Immune serum samples were collected from four populations of patients with confirmed C. trachomatis genital infection: 40 women with pelvic inflammatory disease from Pittsburgh, PA; 27 and 34 adolescent/young females from Oakland, CA, and Little Rock, AR, respectively; and 58 adult male patients from Baltimore, MD. The Pmp-specific antibody response was obtained using immunoblot analysis against each of the nine recombinantly expressed Pmps and quantified by densitometry. Our results show that nearly all C. trachomatis-infected patients mount a strong serologic response against individual or multiple Pmp subtypes and that the antibody specificity profile varies between patients. Moreover, our analysis reveals differences in the strengths and specificities of the Pmp subtype-specific antibody reactivity relating to gender and clinical outcome. Overall, our results indicate that the Pmps elicit various serologic responses in C. trachomatis-infected patients and are consistent with the pmp gene family being the basis of a mechanism of antigenic variation.

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Over the last several years, four different phages of chlamydiae, in addition to a phage associated with Chlamydia psittaci isolated from an ornithosis infection in ducks over 25 years ago, have been described and characterized. While these phages and their chlamydial host specificities have been characterized in vitro, there is virtually nothing known about the interaction of the phage with chlamydiae in their natural animal host. CPG1 is a lytic phage specific for "Chlamydia caviae," which is a natural parasite of the guinea pig. In this study, guinea pigs were inoculated in the conjunctiva with suspensions of CPG1 and C. caviae and the effect on the development of pathology and on the course of chlamydial infection in the conjunctiva was determined. The presence of phage delayed the appearance of the peak level of chlamydiae in the animal and decreased the pathological response. Evidence for replication of the phage in C. caviae in the conjunctival tissue was observed. Modifying the ratio of phage to chlamydiae altered the course of infection and affected phage replication. There was no evidence for the phage increasing the virulence of C. caviae infection.Over the last several years, four different phages of chlamydiae, in addition to a phage associated with Chlamydia psittaci isolated from an ornithosis infection in ducks over 25 years ago by Richmond and coworkers (22), have been described and characterized. Hsia et al. isolated phage CPG1 from in vitrocultured "Chlamydia caviae," the agent of guinea pig inclusion conjunctivitis (7,8). This was followed shortly thereafter by the isolation of phages Chp2 (2) and CPO1 (R.-C. Hsia and P. M. Bavoil, unpublished data) from Chlamydia abortus, AR39/ Cpn1 from Chlamydia pneumoniae (10, 18), and Chp3 from Chlamydia pecorum (3). The chlamydiaphages belong to a class of lytic phages that include the closely related Bdellovibrio bacteriovorus phage pMH2K (1) and the Spiroplasma melliferum phage SpV4 (21) and for which the single-stranded DNA coliphage X174 is the prototype (4). The chlamydial host range for the various chlamydiaphages is varied, but all are lytic for their respective hosts; however, it is interesting to note that chlamydiaphages have not yet been detected in association with Chlamydia trachomatis or Chlamydia muridarum.That five different chlamydiaphages have been described for chlamydiae infecting different animal species from geographically distinct areas would suggest that they are prevalent in chlamydiae in nature. Nevertheless, because all of the chlamydiaphages have been isolated from chlamydiae in tissue culture and their interaction with their hosts has been characterized from tissue culture, there is literally nothing known about the interaction of the chlamydiaphages with their bacterial hosts in the context of infection of the natural hosts of the bacteria. In fact, there are no data describing the interaction of any bacteriophage of an obligate intracellular bacterium in the natural animal host of the bacterium.It is indeed fortunate that ...

Reactive oxygen species (ROS) are generated in nociceptive pathways in response to inflammation and injury. ROS are accumulated within the sensory ganglia following peripheral inflammation, but the functional role of intraganlionic ROS in inflammatory pain is not clearly understood. The aims of this study were to investigate whether peripheral inflammation leads to prolonged ROS accumulation within the trigeminal ganglia (TG), whether intraganglionic ROS mediate pain hypersensitivity via activation of TRPA1, and whether TRPA1 expression is upregulated in TG during inflammatory conditions by ROS. We demonstrated that peripheral inflammation causes excess ROS production within TG during the period when inflammatory mechanical hyperalgesia is most prominent. Additionally, scavenging intraganglionic ROS attenuated inflammatory mechanical hyperalgesia and a pharmacological blockade of TRPA1 localized within TG also mitigated inflammatory mechanical hyperalgesia. Interestingly, exogenous administration of ROS into TG elicited mechanical hyperalgesia and spontaneous pain-like responses via TRPA1, and intraganglionic ROS induced TRPA1 upregulation in TG. These results collectively suggest that ROS accumulation in TG during peripheral inflammation contributes to pain and hyperalgesia in a TRPA1 dependent manner, and that ROS further exacerbate pathological pain responses by upregulating TRPA1 expression. Therefore, any conditions that exacerbate ROS accumulation within somatic sensory ganglia can aggravate pain responses and treatments reducing ganglionic ROS may help alleviate inflammatory pain.