Differential signaling pathways are initiated in macrophages during infection depending on the intracellular fate of Chlamydia spp.

Chlamydia muridarum and Chlamydia caviae have equivalent growth rates in mouse epithelial cells but only C. muridarum replicates inside mouse macrophages, while C. caviae does not. Macrophages infected with C. muridarum or C. caviae were used to address the hypothesis that the early signaling pathways initiated during infection depend on the fate of chlamydiae in the host cell. Transmission electron microscopy of C. muridarum-infected macrophages showed intact chlamydial elementary bodies and reticulate bodies 2 h postinfection in compact vacuoles. Conversely, in macrophages infected with C. caviae, chlamydiae were observed in large phagocytic vacuoles. Furthermore, C. caviae infections failed to develop into inclusions or produce viable bacteria. Expression of proinflammatory cytokines TNFα, IL-1ß and MMP13 was similar in C. caviae- or C. muridarum-infected macrophages at 3 h postinfection, indicating that chlamydial survival is not required for initiation of these responses. IL-1ß secretion, dependent on inflammasome activation, occurred in C. caviae-infected macrophages despite no chlamydial growth. Conversely, IFNß mRNA was observed only in C. muridarum- but not in C. caviae-infected macrophages. These data demonstrate that differential signaling events are initiated during a productive versus nonproductive chlamydial infection in a macrophage.

MyD88 deficiency leads to decreased NK cell gamma interferon production and T cell recruitment during Chlamydia muridarum genital tract infection, but a predominant Th1 response and enhanced monocytic inflammation are associated with infection resolution.

We have previously shown that MyD88 knockout (KO) mice exhibit delayed clearance of Chlamydia muridarum genital infection compared to wild-type (WT) mice. A blunted Th1 response and ineffective suppression of the Th2 response were also observed in MyD88 KO mice. The goal of the present study was to investigate specific mechanisms whereby absence of MyD88 leads to these effects and address the compensatory mechanisms in the genital tract that ultimately clear infection in the absence of MyD88. It was observed that NK cells recruited to the genital tract in MyD88 KO mice failed to produce gamma interferon (IFN-γ) mRNA and protein. This defect was associated with decreased local production of interleukin-17 (IL-17), IL-18, and tumor necrosis factor alpha (TNF-α) but normal levels of IL-12p70. Additionally, recruitment of CD4 T cells to the genital tract was reduced in MyD88 KO mice compared to that in WT mice. Although chronic infection in MyD88 KO mice resulted in oviduct pathology comparable to that of WT mice, increased histiocytic inflammation was observed in the uterine horns. This was associated with increased CCL2 levels and recruitment of macrophages as a potential compensatory mechanism. Further deletion of TLR4-TRIF signaling in MyD88 KO mice, using TLR4/MyD88 double-KO mice, did not further compromise host defense against chlamydiae, suggesting that compensatory mechanisms are Toll-like receptor (TLR) independent. Despite some polarization toward a Th2 response, a Th1 response remained predominant in the absence of MyD88, and it provided equivalent protection against a secondary infection as observed in WT mice.

Host chemokine and cytokine response in the endocervix within the first developmental cycle of Chlamydia muridarum.

The initial host response in a primary chlamydial infection is the onset of acute inflammation. However, we still know very little about the early temporal events in the induction of the acute inflammatory response and how these events relate to the initial chlamydial developmental cycle in an actual genital infection. Because it was critical to initiate a synchronous infection in the endocervix in the first 24 h to evaluate the sequential expression of the host response, we developed the surgical methodology of depositing Chlamydia muridarum directly on the endocervix. Cervical tissue was collected at 3, 12, and 24 h after inoculation and the expression array of chemokines, cytokines, and receptors was assessed to characterize the response during the initial developmental cycle. Polymorphonuclear leukocyte (PMN) infiltration was first observed at 12 h after inoculation, and a few PMNs could be seen in the epithelium at 24 h. Electron microscopic analysis at 24 h showed that virtually all inclusions were at the same stage of development, indicating a synchronous infection. Several chemokine and cytokine genes were expressed as early as 3 h after infection, but by 12 h, 41 genes were expressed. Thus, activation of the host response occurs both with the introduction of elementary bodies into the host and early replication of reticulate bodies. No significant response was observed when UV-inactivated organisms were inoculated into the cervix at any time interval. This model provides an ideal opportunity to investigate the mechanisms by which the early inflammatory response is induced in vivo.

Type I interferon signaling exacerbates Chlamydia muridarum genital infection in a murine model.

Type I interferons (IFNs) induced during in vitro chlamydial infection exert bactericidal and immunomodulatory functions. To determine the precise role of type I IFNs during in vivo chlamydial genital infection, we examined the course and outcome of Chlamydia muridarum genital infection in mice genetically deficient in the receptor for type I IFNs (IFNAR(-/-) mice). A significant reduction in chlamydial shedding and duration of lower genital tract infection was observed in IFNAR(-/-) mice in comparison to the level of chlamydial shedding and duration of infection in wild-type (WT) mice. Furthermore, IFNAR(-/-) mice developed less chronic oviduct pathology in comparison to that in WT mice. Compared to the WT, IFNAR(-/-) mice had a greater number of chlamydial-specific T cells in their iliac lymph nodes 21 days postinfection. IFNAR(-/-) mice also exhibited earlier and enhanced CD4 T-cell recruitment to the cervical tissues, which was associated with increased expression of CXCL9 in the genital secretions of IFNAR(-/-) mice, but not with expression of CXCL10, which was reduced in the genital secretions of IFNAR(-/-) mice. These data suggest that type I IFNs exacerbate C. muridarum genital infection through an inhibition of the chlamydial-specific CD4 T-cell response.

A pilot randomised controlled study of three models of follow-up of patients treated for gynaecological cancer: attitudes in general practice and feasibility of randomisation.

The value of routine follow-up in secondary care for cancer patients has been widely questioned. Within our network cancer centre for gynaecological malignancies current follow-up protocols have been associated with delays in diagnosing recurrence. The aim of this study was to ascertain general practitioners' (GPs') attitudes and feasibility of randomisation for a pilot randomised controlled trial to evaluate follow-up of patients treated for gynaecological malignancy. There was a 78% response rate to the postal questionnaire; overall, GP attitudes were positive, with randomisation seeming feasible. We await the results from the pilot trial.