A Novel Cleavage Pattern of Complement C5 Induced by Chlamydia trachomatis Infection via the Chlamydial Protease CPAF

Urogenital Chlamydia trachomatis infection is one of the most common bacterial sexually transmitted diseases globally. Untreated C. trachomatis infections can ascend to the upper genital tract and establish a series of severe complications. Previous studies using C3−/− and C5−/− mice models demonstrated that C3-independent activation of C5 occurred during C. trachomatis infection. However, the mechanism of how chlamydial infection activates C5 in the absence of C3 has yet to be elucidated. To delineate interactions between C5 and chlamydial infection, cleavage products in a co-incubation system containing purified human C5 and C. trachomatis-HeLa229 cell lysates were analyzed, and a novel cleavage pattern of C5 activation induced by C. trachomatis infection was identified. C5 was cleaved efficiently at the previously unidentified site K970, but was cleaved poorly at site R751. C5b was modified to C5bCt, which later formed C5bCt-9, which had enhanced lytic ability compared with C5b-9. The chlamydial serine protease CPAF contributed to C3-independent C5 activation during C. trachomatis infection. Nafamostat mesylate, a serine protease inhibitor with a good safety profile, had a strong inhibitory effect on C5 activation induced by chlamydial infection. These discoveries reveal the mechanism of C3-independent C5 activation induced by chlamydial infection, and furthermore provide a potential therapeutic target and drug for preventing tubal fibrosis caused by chlamydial infection.

Natural Killer Cells Regulate Pulmonary Macrophages Polarization in Host Defense Against Chlamydial Respiratory Infection

NK cells and pulmonary macrophages both are important components of innate immunity. The interaction between NK cells and pulmonary macrophages during chlamydial infection is poorly understood. In this study, we explored the effect of NK cells on regulation of pulmonary macrophage function during chlamydial respiratory infection. We found that NK depletion led to polarization of pulmonary macrophages from M1 to M2 phenotype, and it is related to reduced miR-155 expression in lung macrophage. Using adoptive transfer approach, we found that the recipients receiving lung macrophages isolated from C. muridarum-infected NK-cell-depleted mice exhibited an increased bacterial load and severe inflammation in the lung upon chlamydial challenge infection when compared with the recipients of lung macrophages from infected isotype control antibody treated mice. Herein, the effects of NK cells on macrophage polarization were examined in vitro. We found that NK cells from chlamydial-infected mice (iNK) significantly induced M1 polarization compared to that from uninfected mice (uNK). Inhibition of miR-155 expression in macrophages reduced M1 polarization induced by iNK, while miR-155 over-expression enhanced it. Furthermore, neutralization of IFN-γ in the coculture system decreased the expression of miR-155 by macrophages, and resulted in weakened M1 polarization. The data indicates that NK cells promote M1 polarization through up-regulation of miR-155 in macrophages by producing IFN-γ during chlamydial infection, and NK-regulated macrophage polarization is functionally relevant to host defense against the infection.

Comparison of laboratory diagnostic methods for urogenital infections caused by Chlamydia trachomatis

According to the Russian-Swedish project there was performed a comparison of methods used for Chlamydia trachomatis detection in cervical samples, obtained from 397women and urethral samples from 253 men. All specimens were examined by direct immunofluorescence (DIF), polymerase chain reaction (PCR) and cell culture (CC). In high-prevalence group (group I) chlamydiae were detected in 17,8% and 28,0% of cases in men and women, respectively. Ingroup II containing patients who were subjected to screening examination, chlamydiae were found in 5% of cases both in men and women. PCR was shown to be the most sensitive when cervical samples in group I and cervical and urethral samples in group II were investigated. When urethral samples in group I were tested, DIF proved to have the highest sensitivity. All the methods used were found to be high specific. The search for standards of genital chlamydial infection diagnosis is in progress.

Characterization of pathogenic CD8 + T cells in Chlamydia - infected OT1 mice

Chlamydia trachomatis is a leading infectious cause of infertility in women due to its induction of lasting pathology such as hydrosalpinx. Chlamydia muridarum induces mouse hydrosalpinx because C. muridarum can both invade tubal epithelia directly (as a 1 st hit) and induce lymphocytes to promote hydrosalpinx indirectly (as a 2 nd hit). In the current study, a critical role of CD8 + T cells in chlamydial induction of hydrosalpinx was validated in both wild type C57BL/6J and OT1 transgenic mice. OT1 mice failed to develop hydrosalpinx partially due to the failure of their lymphocytes to recognize chlamydial antigens. CD8 + T cells from naïve C57BL/6J rescued the recipient OT1 mice to develop hydrosalpinx when naïve CD8 + T cells were transferred at the time of infection with Chlamydia . However, when the transfer was delayed for 2 weeks or longer after the chlamydial infection, naïve CD8 + T cells no longer promoted hydrosalpinx. Nevertheless, Chlamydia -immunized CD8 + T cells still promoted significant hydrosalpinx in the recipient OT1 mice even when the transfer was delayed for 3 weeks. Thus, CD8 + T cells must be primed within 2 weeks after chlamydial infection to be pathogenic but once primed, they can promote hydrosalpinx for >3 weeks. However, Chlamydia -primed CD4 + T cells failed to promote chlamydial induction of pathology in OT1 mice. This study has optimized an OT1 mouse-based model for revealing the pathogenic mechanisms of Chlamydia -specific CD8 + T cells.

Chlamydia evasion of neutrophil host defense results in NLRP3 dependent myeloid-mediated sterile inflammation through the purinergic P2X7 receptor

Chlamydia trachomatis infection causes severe inflammatory disease resulting in blindness and infertility. The pathophysiology of these diseases remains elusive but myeloid cell-associated inflammation has been implicated. Here we show NLRP3 inflammasome activation is essential for driving a macrophage-associated endometritis resulting in infertility by using a female mouse genital tract chlamydial infection model. We find the chlamydial parasitophorous vacuole protein CT135 triggers NLRP3 inflammasome activation via TLR2/MyD88 signaling as a pathogenic strategy to evade neutrophil host defense. Paradoxically, a consequence of CT135 mediated neutrophil killing results in a submucosal macrophage-associated endometritis driven by ATP/P2X7R induced NLRP3 inflammasome activation. Importantly, macrophage-associated immunopathology occurs independent of macrophage infection. We show chlamydial infection of neutrophils and epithelial cells produce elevated levels of extracellular ATP. We propose this source of ATP serves as a DAMP to activate submucosal macrophage NLRP3 inflammasome that drive damaging immunopathology. These findings offer a paradigm of sterile inflammation in infectious disease pathogenesis.

The reaction of innate lymphoid cells in the mouse female genital tract to chlamydial infection

Background Innate lymphoid cells (ILCs) are comprised of five distinct subsets. ILCs are found at mucosal barriers and may fight invading pathogens. Chlamydia is an intracellular bacterium that infects the mucosa of the genital tract and can cause severe tissue damage. Methods We used a mouse infection model with Chlamydia muridarum ( Cmu ) to measure the reaction of genital tract ILCs to the infection. Results Tissue resident natural killer cells were the largest group in the uninfected female genital tract, and their number did not substantially change. Conventional NK cells were present at the greatest numbers during acute infection, while ILC1 cells continuously increased to high numbers. ILC2 and ILC3 cells were found at lower numbers that oscillated by a factor of 2-4. The majority of ILC3 transdifferentiated into ILC1 cells. NK cells and ILC1 cells produced IFN-γ and, rarely, TNF, but only early in the infection. Lack of B and T cells increased, while the loss of myeloid cells decreased ILC numbers. ILCs accumulated to high density in the oviduct, a main site of tissue destruction. Conclusions ILC subsets are part of the inflammatory and immune reaction during infection with Cmu and may contribute to tissue damage during chlamydial infection.

Multiple drug allergy syndrome in pregnancy: Lessons for sexual health physicians

Co-existence of multiple drug allergies and pregnancy often results in vexing dilemmas for physicians. A 21-year-old pregnant woman presented with asymptomatic cervicitis with dual infection with Chlamydia trachomatis and Neisseria gonorrhoeae during her third trimester. She reported a history of generalised rash with mucous membrane involvement following use of both macrolides and penicillins. Her gonococcal infection was successfully treated with a single dose of intramuscular gentamicin and chlamydial infection with oral clindamycin and rifampicin.

To Compare the Frequency of Chlamydial Infection in Infertile Women Compared to Normal Women

Background: A better understanding of the role of persistent C. trachomatis infections in tubal factor subfertility may be useful in optimizing the fertility work-up by incorporating screening tests for persistent C. trachomatis infections. The aim is to accurately estimate the risk of persistence and identify those women who are at highest risk of tubal pathology. Aim: To compare the frequency of chlamydial infection in infertile women compared to normal women. Study Design: Case control study. Settings: Department of Obstetrics & Gynecology, Hospital, Bahawalpur. Study duration: 1st October 2019 to 31st March 2020. Methods: A total of 88 women (44 infertile and 44 normal), having normal semen analysis report, of age ranging from 18 to 40 years were included. Patients with polycystic ovarian disease, hyperprolactinemia, & hypothyroidism were excluded. Blood sample of all women in both groups was sent to the institutional pathology laboratory for presence or absence of chlamydial infection. Results: The mean age of women in case group was 27.80 ± 3.60 years and in control group was 28.05 ± 3.69 years. The mean duration of marriage in case group was 4.93 ± 1.66 years and in control group was 4.95 ± 1.68 years. The mean BMI in case group was 29.36 ± 2.52 kg/m2 and in control group was 29.50 ± 2.51 kg/m2. My study reveals the frequency of chlamydial infection in infertile women was seen in 15 (34.09%) women as compared to 05 (9.09%) in normal women which has shown p-value of 0.007 and odds ratio of 5.17 which is significant. Conclusion: This study concluded that frequency of chlamydial infection in infertile women is higher compared to normal women. Keywords: Infertility, chlamydial infection, tubal factor, sexually transmitted diseases