Molecular Pathogenesis of Chlamydia Disease Complications: Epithelial-Mesenchymal Transition and Fibrosis

Role of microRNAs in immune regulation and pathogenesis of Chlamydia trachomatis and Chlamydia muridarum infections: a rapid review

MicroRNAs in Chlamydia trachomatis (CT) and Chlamydia muridarum (CM) infections are an emerging topic of research that provide knowledge that could advance vaccine development and strategies for managing infection. This rapid review summarizes human and murine studies on miRNA expression in CT and CM infections in vivo and ex vivo.

Prognostic Value of Anti-Chlamydia Trachomatis IgG in Breast Cancer and the Modification Effects of Pro-Inflammatory Cytokines: A 13-Year Prospective Cohort Study

Purpose

Chlamydia trachomatis (C. trachomatis) is associated with several gynecological tumors; yet its prognostic role in breast cancer remains unclear. Thus, we investigated the prognostic role of anti-C. trachomatis immunoglobulin G (IgG) in breast cancer patients and the modification effects of pro-inflammatory cytokines.

Methods

The serum levels of C. trachomatis IgG and four pro-inflammatory cytokines were measured. Cox regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs), including product terms to assess the modification effects of pro-inflammatory cytokines on the association between C. trachomatis IgG and breast cancer prognosis.

Results

From 2008 to 2018, 1121 breast cancer patients were recruited and followed up until December 31, 2021, with a median follow-up time of 63.91 months (interquartile range: 39.16-90.08 months). Patients positive for C. trachomatis IgG showed HRs of 1.09 (95% CI, 0.67-1.78) for overall survival (OS) and 1.24 (0.87-1.78) for progression-free survival (PFS), compared to those who were negative. These associations became statistically significant in women aged 50 years or younger (HR=1.43, 95% CI=0.79-2.58 for OS; HR=1.79, 95% CI=1.16-2.77 for PFS). Positive C. trachomatis IgG serology was associated with adverse prognostic effects among patients with higher levels of pro-inflammatory cytokines (IL-6, TNF-α, IL-8, and IL-1β), but with favorable prognostic effects for those with low levels. These interactions were particularly significant in those aged 50 years or younger.

Conclusion

In breast cancer patients younger than 50 years of age or with higher levels of pro-inflammatory cytokines, C. trachomatis infection appeared to have a negative prognostic impact. These findings highlight the significance of C. trachomatis in predicting prognosis and personalized therapy for breast cancer patients.

Chlamydial YAP activation in host endocervical epithelial cells mediates pro-fibrotic paracrine stimulation of fibroblasts

IMPORTANCE

Chronic or repeated infection of the female upper genital tract by C. trachomatis can lead to severe fibrotic sequelae, including tubal factor infertility and ectopic pregnancy. However, the molecular mechanisms underlying this effect are unclear. In this report, we define a transcriptional program specific to C. trachomatis infection of the upper genital tract, identifying tissue-specific induction of host YAP-a pro-fibrotic transcriptional cofactor-as a potential driver of infection-mediated fibrotic gene expression. Furthermore, we show that infected endocervical epithelial cells stimulate collagen production by fibroblasts and implicate chlamydial induction of YAP in this effect. Our results define a mechanism by which infection mediates tissue-level fibrotic pathology via paracrine signaling and identify YAP as a potential therapeutic target for the prevention of Chlamydia-associated scarring of the female genital tract.

Preclinical screen for protection efficacy of chlamydial antigens that are immunogenic in humans

To search for subunit vaccine candidates, immunogenic chlamydial antigens identified in humans were evaluated for protection against both infection and pathology in a mouse genital tract infection model under three different immunization regimens. The intramuscular immunization regimen was first used to evaluate 106 chlamydial antigens, which revealed that two antigens significantly reduced while 11 increased genital chlamydial burden. The two infection-reducing antigens failed to prevent pathology and 23 additional antigens even exacerbated pathology. Thus, intranasal mucosal immunization was tested next since intranasal inoculation with live Chlamydia muridarum prevented both genital infection and pathology. Two of the 29 chlamydial antigens evaluated were found to prevent genital infection but not pathology and three exacerbate pathology. To further improve protection efficacy, a combinational regimen (intranasal priming + intramuscular boosting + a third intraperitoneal/subcutaneous boost) was tested. This regimen identified four infection-reducing antigens, but only one of them prevented pathology. Unfortunately, this protective antigen was not advanced further due to its amino acid sequence homology with several human molecules. Two pathology-exacerbating antigens were also found. Nevertheless, intranasal mucosal priming with viable C. muridarum in control groups consistently prevented both genital infection and pathology regardless of the subsequent boosters. Thus, screening 140 different chlamydial antigens with 21 repeated multiple times in 17 experiments failed to identify a subunit vaccine candidate but demonstrated the superiority of viable chlamydial organisms in inducing immunity against both genital infection and pathology, laying the foundation for developing a live-attenuated Chlamydia vaccine.

The role of infected epithelial cells in Chlamydia-associated fibrosis

Ocular, genital, and anogenital infection by the obligate intracellular pathogen Chlamydia trachomatis have been consistently associated with scar-forming sequelae. In cases of chronic or repeated infection of the female genital tract, infection-associated fibrosis of the fallopian tubes can result in ectopic pregnancy or infertility. In light of this urgent concern to public health, the underlying mechanism of C. trachomatis-associated scarring is a topic of ongoing study. Fibrosis is understood to be an outcome of persistent injury and/or dysregulated wound healing, in which an aberrantly activated myofibroblast population mediates hypertrophic remodeling of the basement membrane via deposition of collagens and other components of the extracellular matrix, as well as induction of epithelial cell proliferation via growth factor signaling. Initial study of infection-associated immune cell recruitment and pro-inflammatory signaling have suggested the cellular paradigm of chlamydial pathogenesis, wherein inflammation-associated tissue damage and fibrosis are the indirect result of an immune response to the pathogen initiated by host epithelial cells. However, recent work has revealed more direct routes by which C. trachomatis may induce scarring, such as infection-associated induction of growth factor signaling and pro-fibrotic remodeling of the extracellular matrix. Additionally, C. trachomatis infection has been shown to induce an epithelial-to-mesenchymal transition in host epithelial cells, prompting transdifferentiation into a myofibroblast-like phenotype. In this review, we summarize the field's current understanding of Chlamydia-associated fibrosis, reviewing key new findings and identifying opportunities for further research.

Epigenetic changes induced by pathogenic Chlamydia spp

Chlamydia trachomatis, C. pneumoniae, and C. psittaci, the three Chlamydia species known to cause human disease, have been collectively linked to several pathologies, including conjunctivitis, trachoma, respiratory disease, acute and chronic urogenital infections and their complications, and psittacosis. In vitro, animal, and human studies also established additional correlations, such as between C. pneumoniae and atherosclerosis and between C. trachomatis and ovarian cancer. As part of their survival and pathogenesis strategies as obligate intracellular bacteria, Chlamydia spp. modulate all three major types of epigenetic changes, which include deoxyribonucleic acid (DNA) methylation, histone post-translational modifications, and microRNA-mediated gene silencing. Some of these epigenetic changes may be implicated in key aspects of pathogenesis, such as the ability of the Chlamydia spp. to induce epithelial-to-mesenchymal transition, interfere with DNA damage repair, suppress cholesterol efflux from infected macrophages, act as a co-factor in human papillomavirus (HPV)-mediated cervical cancer, prevent apoptosis, and preserve the integrity of mitochondrial networks in infected host cells. A better understanding of the individual and collective contribution of epigenetic changes to pathogenesis will enhance our knowledge about the biology of Chlamydia spp. and facilitate the development of novel therapies and biomarkers. Pathogenic Chlamydia spp. contribute to epigenetically-mediated gene expression changes in host cells by multiple mechanisms.

The Correlation between Chlamydia Trachomatis and Female Infertility: A Systematic Review

The impact of Chlamydia trachomatis (CT) infection on female's fertility is not completely established yet, since the level of evidence associating these factors is still weak. Hence, the goal of the present review is to contribute to a better elucidation of this matter. The electronic database chosen was the Medline/PubMed, with the last survey on May 11, 2021. Publication date was used as a filter, with the previous 5 years having been selected. The following describers were used: chlamydia trachomatis AND infertility; chlamydia trachomatis AND tubal alteration AND infertility; chlamydia AND low pregnancy rates. From the 322 studies screened, 293 that failed to meet our eligibility criteria were excluded. Subsequently, we removed seven studies for not having the possible correlation between CT infections and female infertility as its main focus, and three for being about sexually transmitted infections (STIs) in general. Moreover, two studies designed as reviews were also excluded. Ergo, we included 17 studies in our qualitative analysis. The authors conducted research individually and analyzed carefully the studies selected. As we retrieved the information needed for our study through reading the texts, no contact was made with the authors of the studies selected. This systematic review corroborates the hypothesis that CT infection potentiates female infertility, as 76.47% of the included studies found a positive correlation between them. We conclude that there is an important association between CT infection and female infertility. Ergo, making CT screening part of the infertility investigation routine is relevant and has a reasonable justification.

Fallopian tubal infertility: the result of Chlamydia trachomatis-induced fallopian tubal fibrosis

Chlamydia trachomatis is one of the most common pathogens of sexually transmitted diseases, and its incidence in genital tract infections is now 4.7% in south China. Infertility is the end result of C. trachomatis-induced fallopian tubal fibrosis and is receiving intense attention from scientists worldwide. To reduce the incidence of infertility, it is important to understand the pathology-related changes of the genital tract where C. trachomatis infection is significant, especially the mechanism of fibrosis formation. During fibrosis development, the fallopian tube becomes sticky and occluded, which will eventually lead to tubal infertility. At present, the mechanism of fallopian tubal fibrosis induced by C. trachomatis infection is unclear. Our study attempted to summarize the possible mechanisms of fibrosis caused by C. trachomatis infection in the fallopian tube by reviewing published studies and further providing potential therapeutic targets to reduce the occurrence of infertility. This study also provides ideas for future research. Factors leading to fallopian tube fibrosis include inflammatory factors, miRNA, ECT, cHSP, and host factors. We hypothesized that C. trachomatis mediates the transcription and translation of EMT and ECM via upregulating TGF signaling pathway, which leads to the formation of fallopian tube fibrosis and ultimately to tubal infertility.

Is There a Hidden Burden of Disease as a Result of Epigenetic Epithelial-to-Mesenchymal Transition Following Chlamydia trachomatis Genital Tract Infection?

Chlamydia trachomatis (CT), the most common bacterial sexually transmitted infection worldwide, has been widely researched for its involvement in many disease pathologies in the reproductive tract, including pelvic inflammatory disease, ectopic pregnancy, and tubal factor infertility. Recent findings, through the efforts to understand the pathogenesis of CT, suggest that CT can induce the process of epithelial-to-mesenchymal transition (EMT) through epigenetic changes in the epithelium of the female reproductive tract. This literature review aims to analyze the evidence for CT's ability to promote EMT and to pinpoint the areas that merit further investigation.

Eutopic endometrium from women with endometriosis and chlamydial endometritis share immunological cell types and DNA repair imbalance: A transcriptome meta-analytical perspective

The aim of this study was to identify the key similarities between the eutopic endometrium of women with endometriosis and chlamydia-induced endometritis taking into account tissue microenvironment heterogeneity, transcript gene profile, and enriched pathways. A meta-analysis of whole transcriptome microarrays was performed using publicly available data, including samples containing both glandular and stromal endometrial components. Control samples were obtained from women without any reported pathological condition. Only samples obtained during the proliferative menstrual phase were included. Cellular tissue heterogeneity was predicted using a method that integrates gene set enrichment and deconvolution approaches. The batch effect was estimated by principal variant component analysis and removed using an empirical Bayes method. Differentially expressed genes were identified using an adjusted p-value < 0.05 and fold change = 1.5. The protein-protein interaction network was built using the STRING database and interaction score over 400. The Molecular Signatures Database was used to analyse the functional enrichment analysis. Both conditions showed similarities in cell types in the microenvironment, particularly CD4⁺ and CD8⁺ Tem cells, NKT cells, Th2 cells, basophils, and eosinophils. With regards to the regulation of cellular senescence and DNA integrity/damage checkpoint, which are commonly enriched pathways, 21 genes were down-regulated and directly related to DNA repair. Compared to the endometriosis samples, some chlamydial endometritis samples presented a lack of enriched immune pathways. Our results suggest that both conditions show similar distributions of microenvironment cell types, the downregulation of genes involved in DNA repair and cell cycle control, and pathways involved in immune response evasion.

Differential miRNA Profiles Correlate With Disparate Immunity Outcomes Associated With Vaccine Immunization and Chlamydial Infection

Vaccine-induced immune responses following immunization with promising Chlamydia vaccines protected experimental animals from Chlamydia-induced upper genital tract pathologies and infertility. In contrast, primary genital infection with live Chlamydia does not protect against these pathologies. We hypothesized that differential miRNA profiles induced in the upper genital tracts (UGT) of mice correlate with the disparate immunity vs. pathologic outcomes associated with vaccine immunization and chlamydial infection. Thus, miRNA expression profiles in the UGT of mice after Chlamydia infection (Live EB) and immunization with dendritic cell (DC)-based vaccine (DC vaccine) or VCG-based vaccine (VCG vaccine) were compared using the NanoString nCounter Mouse miRNA assay. Of the 602 miRNAs differentially expressed (DE) in the UGT of immunized and infected mice, we selected 58 with counts >100 and p-values < 0.05 for further analysis. Interestingly, vaccine immunization and Chlamydia infection induced the expression of distinct miRNA profiles with a higher proportion in vaccine-immunized compared to Chlamydia infected mice; DC vaccine (41), VCG vaccine (23), and Live EB (15). Hierarchical clustering analysis showed notable differences in the uniquely DE miRNAs for each experimental group, with DC vaccine showing the highest number (21 up-regulated, five down-regulated), VCG vaccine (two up-regulated, five down-regulated), and live EB (two up-regulated, four down-regulated). The DC vaccine-immunized group showed the highest number (21 up-regulated and five down-regulated compared to two up-regulated and four down-regulated in the live Chlamydia infected group). Pathway analysis showed that the DE miRNAs target genes that regulate several biological processes and functions associated with immune response and inflammation. These results suggest that the induction of differential miRNA expression plays a significant role in the disparate immunity outcomes associated with Chlamydia infection and vaccination.

Chromatin accessibility dynamics of Chlamydia-infected epithelial cells

Chlamydia are Gram-negative, obligate intracellular bacterial pathogens responsible for a broad spectrum of human and animal diseases. In humans, Chlamydia trachomatis is the most prevalent bacterial sexually transmitted infection worldwide and is the causative agent of trachoma (infectious blindness) in disadvantaged populations. Over the course of its developmental cycle, Chlamydia extensively remodels its intracellular niche and parasitises the host cell for nutrients, with substantial resulting changes to the host cell transcriptome and proteome. However, little information is available on the impact of chlamydial infection on the host cell epigenome and global gene regulation. Regions of open eukaryotic chromatin correspond to nucleosome-depleted regions, which in turn are associated with regulatory functions and transcription factor binding. We applied formaldehyde-assisted isolation of regulatory elements enrichment followed by sequencing (FAIRE-Seq) to generate temporal chromatin maps of C. trachomatis-infected human epithelial cells in vitro over the chlamydial developmental cycle. We detected both conserved and distinct temporal changes to genome-wide chromatin accessibility associated with C. trachomatis infection. The observed differentially accessible chromatin regions include temporally-enriched sets of transcription factors, which may help shape the host cell response to infection. These regions and motifs were linked to genomic features and genes associated with immune responses, re-direction of host cell nutrients, intracellular signalling, cell-cell adhesion, extracellular matrix, metabolism and apoptosis. This work provides another perspective to the complex response to chlamydial infection, and will inform further studies of transcriptional regulation and the epigenome in Chlamydia-infected human cells and tissues.

Effectiveness of Platelet-Rich Plasma in the Prevention of Chlamydia-Induced Hydrosalpinx in a Murine Model

Chlamydia trachomatis (C. trachomatis) is a major pathogen implicated in the formation of hydrosalpinx in the female reproductive tract. In mice, a related strain of Chlamydia, Chlamydia trachomatis (C. trachomatis) can induce almost 100% bilateral hydrosalpinx. This model was used as a hydrosalpinx induction model to test whether oviduct delivery of platelet-rich plasma (PRP) can attenuate chlamydia induction of hydrosalpinx in a mouse model. Mice were infected intravaginally with Chlamydia muridarum organisms, and 21 days after the infection, PRP was instilled into the lumen of one oviduct, and a sham instillation with phosphate buffer solution was performed on the contralateral oviduct. Mice were then sacrificed at designated time points after infection for oviduct pathologic evaluation including incidence, severity, and histopathologic grade of chronic inflammation. Oviduct instillation of PRP was associated with a 36% reduction in the incidence of hydrosalpinx and a 33% reduction in severity compared with sham. The median grade of chronic inflammation on histopathology was significantly lower with PRP instillation compared with sham and control. No differences were observed in vaginal or rectal shedding of C. muridarum between the test group and the control group. In short, the results suggest that oviduct instillation of PRP can significantly reduce the incidence and severity of C. muridarum-induced hydrosalpinx without affecting chlamydial infection courses in CBA/J mice.

Endocervical miRNA Expression Profiles in Women Positive for Chlamydia trachomatis with Clinical Signs and/or Symptoms Are Distinct from Those in Women Positive for Chlamydia trachomatis without Signs and Symptoms

Chlamydia trachomatis is the leading cause of sexually transmitted infections that may progress to pelvic inflammatory disease and infertility. No effective vaccine exists for Chlamydia, nor are there biomarkers available that readily predict disease progression. In this cross-sectional pilot study, we recruited symptomatic and asymptomatic women with C. trachomatis (CT) infection and asymptomatic, uninfected control women from an urban sexually transmitted disease clinic to determine if there were differences in microRNA (miRNA) expression. Infected women with signs and/or symptoms (CTSS) have distinct miRNA profiles compared to asymptomatic infected women (CTNS). In the CTSS group, miR-142 and -147 showed 2.2- to 6.9-fold increases in expression. In the CTNS group, miR-449c, -6779, -519d, -449a, and -2467 showed 3.9- to 9.0-fold increases in expression. In the CTNS group, cyclins and cell cycle regulation and IL-17 pathways were likely downregulated, while the same signaling pathways were upregulated in the CTSS group. In addition, in the CTSS group, additional inflammatory pathways associated with TNFR1 and IL-8 appear to be upregulated. The miRNA expression patterns differ between CT-infected symptomatic and asymptomatic women, and these differences may warrant further study.

Epidermal Growth Factor Receptor and Transforming Growth Factor β Signaling Pathways Cooperate To Mediate Chlamydia Pathogenesis

Human genital Chlamydia infection is a major public health concern due to the serious reproductive system complications. Chlamydia binds several receptor tyrosine kinases (RTKs) on host cells, including the epidermal growth factor receptor (EGFR), and activates cellular signaling cascades for host invasion, cytoskeletal remodeling, optimal inclusion development, and induction of pathogenic epithelial-mesenchyme transition (EMT). Chlamydia also upregulates transforming growth factor beta (TGF-β) expression, whose signaling pathway synergizes with the EGFR cascade, but its role in infectivity, inclusions, and EMT induction is unknown. We hypothesized that the EGFR and TGF-β signaling pathways cooperate during chlamydial infection for optimal inclusion development and stable EMT induction. The results revealed that Chlamydia upregulated TGF-β expression as early as 6 h postinfection of epithelial cells and stimulated both the EGFR and TGF-β signaling pathways. Inhibition of either the EGFR or TGF-βR1 signaling substantially reduced inclusion development; however, the combined inhibition of both EGFR and TGF-βR1 signaling reduced inclusions by over 90% and prevented EMT induction. Importantly, EGFR inhibition suppressed TGF-β expression, and an inhibitory thrombospondin-1 (Tsp1)-based peptide inhibited chlamydia-induced EMT, revealing a major source of active TGF-β during infection. Finally, TGF-βR signaling inhibition suppressed the expression of transforming acidic coiled-coil protein-3 (TACC3), which stabilizes EGFR signaling, suggesting reciprocal regulation between TGF-β and EGFR signaling during chlamydial infection. Thus, RTK-mediated host invasion by chlamydia upregulated TGF-β expression and signaling, which cooperated with other cellular signaling cascades and cytoskeletal remodeling to support optimal inclusion development and EMT induction. This finding may provide new targets for chlamydial disease biomarkers and prevention.

The Role of MicroRNA-155 in Chlamydia muridarum Infected lungs

Our laboratory has investigated the role of an evolutionarily conserved RNA species called microRNAs (miRs) in regulation of anti-chlamydial protective immunity. MiRs including miR-155 expressed in specific immune effector cells are critical for antigen specific protective immunity and IFN-γ production. Using miR-155 deficient mice, and a murine pulmonary model for chlamydial infection, we report here 1) the effect of host miR-155 on bacterial burden, and 2) identify probable immune genes regulated by miR-155.

Pathogenic Puppetry: Manipulation of the Host Actin Cytoskeleton by Chlamydia trachomatis

The actin cytoskeleton is crucially important to maintenance of the cellular structure, cell motility, and endocytosis. Accordingly, bacterial pathogens often co-opt the actin-restructuring machinery of host cells to access or create a favorable environment for their own replication. The obligate intracellular organism Chlamydia trachomatis and related species exemplify this dynamic: by inducing actin polymerization at the site of pathogen-host attachment, Chlamydiae induce their own uptake by the typically non-phagocytic epithelium they infect. The interaction of chlamydial adhesins with host surface receptors has been implicated in this effect, as has the activity of the chlamydial effector TarP (translocated actin recruitment protein). Following invasion, C. trachomatis dynamically assembles and maintains an actin-rich cage around the pathogen’s membrane-bound replicative niche, known as the chlamydial inclusion. Through further induction of actin polymerization and modulation of the actin-crosslinking protein myosin II, C. trachomatis promotes egress from the host via extrusion of the inclusion. In this review, we present the experimental findings that can inform our understanding of actin-dependent chlamydial pathogenesis, discuss lingering questions, and identify potential avenues of future study.

Toll-Like Receptor 3 Deficiency Leads to Altered Immune Responses to Chlamydia trachomatis Infection in Human Oviduct Epithelial Cells

Reproductive tract pathology caused by Chlamydia trachomatis infection is an important global cause of human infertility. To better understand the mechanisms associated with Chlamydia-induced genital tract pathogenesis in humans, we used CRISPR genome editing to disrupt Toll-like receptor 3 (TLR3) function in the human oviduct epithelial (hOE) cell line OE-E6/E7 in order to investigate the possible role(s) of TLR3 signaling in the immune response to Chlamydia Disruption of TLR3 function in these cells significantly diminished the Chlamydia-induced synthesis of several inflammation biomarkers, including interferon beta (IFN-β), interleukin-6 (IL-6), interleukin-6 receptor alpha (IL-6Rα), soluble interleukin-6 receptor beta (sIL-6Rβ, or gp130), IL-8, IL-20, IL-26, IL-34, soluble tumor necrosis factor receptor 1 (sTNF-R1), tumor necrosis factor ligand superfamily member 13B (TNFSF13B), matrix metalloproteinase 1 (MMP-1), MMP-2, and MMP-3. In contrast, the Chlamydia-induced synthesis of CCL5, IL-29 (IFN-λ1), and IL-28A (IFN-λ2) was significantly increased in TLR3-deficient hOE cells compared to their wild-type counterparts. Our results indicate a role for TLR3 signaling in limiting the genital tract fibrosis, scarring, and chronic inflammation often associated with human chlamydial disease. Interestingly, we saw that Chlamydia infection induced the production of biomarkers associated with persistence, tumor metastasis, and autoimmunity, such as soluble CD163 (sCD163), chitinase-3-like protein 1, osteopontin, and pentraxin-3, in hOE cells; however, their expression levels were significantly dysregulated in TLR3-deficient hOE cells. Finally, we demonstrate using hOE cells that TLR3 deficiency resulted in an increased amount of chlamydial lipopolysaccharide (LPS) within Chlamydia inclusions, which is suggestive that TLR3 deficiency leads to enhanced chlamydial replication and possibly increased genital tract pathogenesis during human infection.

A renewed tool kit to explore Chlamydia pathogenesis: from molecular genetics to new infection models

Chlamydia trachomatis is the most prevalent sexually transmitted bacterial pathogen and the leading cause of preventable blindness in the developing world. C. trachomatis invades the epithelium of the conjunctiva and genital tract and replicates within an intracellular membrane-bound compartment termed the inclusion. To invade and replicate in mammalian cells, Chlamydia remodels epithelial surfaces by reorganizing the cytoskeleton and cell–cell adhesions, reprograms membrane trafficking, and modulates cell signaling to dampen innate immune responses. If the infection ascends to the upper female genital tract, it can result in pelvic inflammatory disease and tissue scarring. C. trachomatis infections are associated with infertility, ectopic pregnancies, the fibrotic disorder endometriosis, and potentially cancers of the cervix and uterus. Unfortunately, the molecular mechanisms by which this clinically important human pathogen subverts host cellular functions and causes disease have remained relatively poorly understood because of the dearth of molecular genetic tools to study Chlamydiae and limitations of both in vivo and in vitro infection models. In this review, we discuss recent advances in the experimental molecular tool kit available to dissect C. trachomatis infections with a special focus on Chlamydia-induced epithelial barrier disruption by regulating the structure, function, and dynamics of epithelial cell–cell junctions.

Asymmetric dimethylarginine: An crucial regulator in tissue fibrosis

Fibrosis is a reparative process with very few therapeutic options to prevent its progression to organ dysfunction. Chronic fibrotic diseases contribute to an estimated 45% of all death in the industrialized world. Asymmetric dimethylarginine (ADMA), an endothelial nitric oxide synthase inhibitor, plays a crucial role in the pathogenesis of various cardiovascular diseases associated with endothelial dysfunction. Recent reports have focused on ADMA in the pathogenesis of tissue fibrosis. This review discusses the current knowledge about ADMA biology, its association with risk factors of established fibrotic diseases and the potential pathophysiological mechanisms implicating ADMA in the process of tissue fibrosis.

A unique insight into the MiRNA profile during genital chlamydial infection

Background

Genital C. trachomatis infection may cause pelvic inflammatory disease (PID) that can lead to tubal factor infertility (TFI). Understanding the pathogenesis of chlamydial complications including the pathophysiological processes within the female host genital tract is important in preventing adverse pathology. MicroRNAs regulate several pathophysiological processes of infectious and non-infectious etiologies. In this study, we tested the hypothesis that the miRNA profile of single and repeat genital chlamydial infections will be different and that these differences will be time dependent. Thus, we analyzed and compared differentially expressed mice genital tract miRNAs after single and repeat chlamydia infections using a C. muridarum mouse model. Mice were sacrificed and their genital tract tissues were collected at 1, 2, 4, and 8 weeks after a single and repeat chlamydia infections. Histopathology, and miRNA sequencing were performed.

Results

Histopathology presentation showed that the oviduct and uterus of reinfected mice were more inflamed, distended and dilated compared to mice infected once. The miRNAs expression profile was different in the reproductive tissues after a reinfection, with a greater number of miRNAs expressed after reinfection. Also, the number of miRNAs expressed each week after chlamydia infection and reinfection varied, with weeks eight and one having the highest number of differentially expressed miRNAs for chlamydia infection and reinfection respectively. Ten miRNAs; mmu-miR-378b, mmu-miR-204-5p, mmu-miR-151-5p, mmu-miR-142-3p, mmu-miR-128-3p, mmu-miR-335-3p, mmu-miR-195a-3p, mmu-miR-142-5p, mmu-miR-106a-5p and mmu-miR-92a-3p were common in both primary chlamydia infection and reinfection. Pathway analysis showed that, amongst other functions, the differentially regulated miRNAs control pathways involved in cellular and tissue development, disease conditions and toxicity.

Conclusions

This study provides insights into the changes in miRNA expression over time after chlamydia infection and reinfection, as well as the pathways they regulate to determine pathological outcomes. The miRNAs networks generated in our study shows that there are differences in the focus molecules involved in significant biological functions in chlamydia infection and reinfection, implying that chlamydial pathogenesis occurs differently for each type of infection and that this could be important when determining treatments regime and disease outcome. The study underscores the crucial role of host factors in chlamydia pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5495-6) contains supplementary material, which is available to authorized users.

Silence of IGFBP7 suppresses apoptosis and epithelial mesenchymal transformation of high glucose induced-podocytes

Insulin-like growth factor-binding protein 7 (IGFBP7) has been identified as a secreted protein associated with a number of cellular processes. However, the specific regulatory mechanisms of IGFBP7 on podocytes of diabetic nephropathy (DN) are yet to be elucidated. In the present study, podocytes were identified initially via an immunofluorescence assay using an anti-synaptopodin antibody. It was subsequently demonstrated that glucose promoted podocyte proliferation in a time- and dose-dependent manner via MTT assay. In addition, IGFBP7 expression was silenced in podocytes via siRNA, the effects of which were evaluated using western blotting and reverse transcription-quantitative polymerase chain reaction. It was demonstrated that silencing IGFBP7 inhibited apoptosis and epithelial mesenchymal transformation (EMT) of podocytes mediated by high glucose (HG). Transforming growth factor (TGF)-β1/mothers against decapentaplegic homolog (Smad) signaling was associated with proliferation, apoptotic activities and EMT. Therefore, the expression levels of TGF-β1/Smad pathway were detected, and it was observed that silencing IGFBP7 suppressed the TGF-β1/Smad pathway in podocytes induced by HG. These findings suggested that IGFBP7 may serve as a potential therapeutic target for DN.