Effect of female sex hormones on the developmental cycle of Chlamydia abortus compared to a penicillin-induced model of persistent infection

Abstract

Background Chlamydia abortus , an obligate intracellular pathogen with an affinity for placenta, causes reproductive failure. In non-pregnant animals, an initial latent infection is established until the next gestation, when the microorganism is reactivated, causing abortion. The precise mechanisms that trigger the awakening of C. abortus are still unknown. Sexual hormones such as estradiol and progesterone have been shown to affect the outcome of infection in other species of the family Chlamydiaceae, while estrogens increase chlamydial infection, progesterone has the opposite effect. To try to establish whether there is a relationship between these events and the latency/ reactivation of C. abortus in the reproductive tract of small ruminants, ovine endometrial (LE) and trophoblastic (AH-1) cells were treated with estradiol or progesterone prior to their infection with C. abortus . The results are compared with those obtained for treatment with penicillin prior to infection, which is a well-established model for studying persistent infection in other chlamydial species. Cells were examined by transmission electron microscopy, and an mRNA expression analysis of 16 genes related to the chlamydial developmental cycle was made. Results The changes observed in this study by the action of sex hormones seem to depend on the type of cell where the infection develops. In addition, while the changes are morphologically similar to those induced by treatment with penicillin, the patterns of gene expression are different. Gene expression patterns therefore, seem to depend on the persistence induced models of C. abortus used. Hormone treatments induced aberrant forms in infected endometrial cells but did not affect the chlamydial morphology in trophoblast cells. At the genetic level, hormones did not induce significant changes in the expression of the studied genes. Conclusions The results suggest that penicillin induces a state of persistence in in vitro cultured C. abortus with characteristic morphological features and gene transcriptional patterns. However, the influence of hormones on the C. abortus developmental cycle is mediated by changes in the host cell environment. Furthermore, a persistent state in C. abortus cannot be characterised by a single profile of gene expression pattern, but may change depending on the model used to induce persistence.

Detection of Chlamydia abortus in aborted chorioallantoises of horses from Western Canada

“…In the study from Hungary, 22% of the PCR-positive cases had no gross or histologic lesions. 2 , 4 This is similar to our finding of 17 cases with no lesions noted in their autopsy and histology reports. It is possible that these PCR-positive cases were the result of environmental contamination at the time of birth, prior to submission for autopsy.…”

“…24 The progesterone drop in the period before parturition is thought to be the trigger for chlamydial invasion of trophoblasts and development of disease in sheep. 4 Hence, only sheep affected in the 5-6 wk prior to lambing should be affected by the pathogen. However, this is not the case.…”

Recent advances and public health implications for environmental exposure to Chlamydia abortus: from enzootic to zoonotic disease

“…In sheep, it is only at approximately 60 days of gestation, when maternal haematomata appear in the placentome hilus, that C. abortus circulating in the bloodstream or being latent in a yet undefined site is able to begin the actual infection, coming into direct contact with the chorionic epithelium [ 31 , 32 ]. Work from Álvarez et al [ 33 ] suggests that the bacterium is likely to remain latent on the maternal side of the placenta until the final stages of gestation due to high levels of progesterone, then reactivates in concomitance to the drop of progesterone that occurs at the end of pregnancy, allowing the invasion of trophoblasts and consequently the development of the disease. Although the damages are limited to the hilar zone of some placentomes, the viability and functionality of the surrounding areas are also affected [ 31 ].…”

Bacteriophage Therapy: Recent Development and Applications

“…Before the development of antibiotics, humans were considered a much suffered from infectious diseases and the discovery of antimicrobials in the 20 th century was considered a scientific revolution that significantly reduced the number of fatal cases. So, the frame has been labeled -antibiotic generation,‖ and this type of therapy was the most successful chemotherapy in the field of medical history [7]. Due to this cause, new and alternate therapeutics must be considered, hence avoiding future mass affliction and health losses [8].…”