A unique insight into the MiRNA profile during genital chlamydial infection

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.

Potential diagnostic value of miRNAs in sexually transmitted infections

MiRNAs are small endogenous non-coding RNAs that have been demonstrated to be involved in post-transcriptional gene silencing, regulating a number of metabolic functions in the human body, including immune response, cellular physiology, organ development, angiogenesis, signaling, and other aspects. As popular molecules that have been studied in previous years, given their extensive regulatory functions, miRNAs hold considerable promise as non-invasive biomarkers. Sexually transmitted infections(STIs) are still widespread and have an adverse effect on individuals, communities, and society worldwide. miRNAs in the regulatory networks are generally involved in their molecular processes of formation and development. In this review, we discuss the value of miRNAs for the diagnosis of STIs.

Normospermic Patients Infected With Ureaplasma parvum: Role of Dysregulated miR-122-5p, miR-34c-5, and miR-141-3p

Background

Ureaplasma parvum (UP) is a causative agent of non-gonococcal urethritis, involved in the pathogenesis of prostatitis and epididymitis, and it could impair human fertility. Although UP infection is a frequent cause of male infertility the study evidence assessing their prevalence and the association in patients with infertility is still scarce. The molecular processes leading to defects in spermatozoa quality are not completely investigated. MicroRNAs (miRNAs) have been extensively reported as gene regulatory molecules on post-transcriptional levels involved in various biological processes such as gametogenesis, embryogenesis, and the quality of sperm, oocyte, and embryos.

Methods

Therefore, the study design was to demonstrate that miRNAs in body fluids like sperm could be utilized as non-invasive diagnostic biomarkers for pathological and physiological conditions such as infertility. A post-hoc bioinformatics analysis was carried out to predict the pathways modulated by the miRNAs dysregulated in the differently motile spermatozoa.

Results

Here it is shown that normospermic patients infected by UP had spermatozoa with increased quantity of superoxide anions, reduced expression of miR-122-5p, miR-34c-5, and increased miR-141-3p compared with non-infected normospermic patients. This corresponded to a reduction of sperm motility in normospermic infected patients compared with normospermic non-infected ones. A target gene prediction presumed that an essential role of these miRNAs resided in the regulation of lipid kinase activity, accounting for the changes in the constitution of spermatozoa membrane lipids caused by UP.

Conclusions

Altogether, the data underline the influence of UP on epigenetic mechanisms regulating spermatozoa motility.

Genital tract microbiome dynamics are associated with time of Chlamydia infection in mice

We have previously shown that the time of Chlamydia infection was crucial in determining the chlamydial infectivity and pathogenesis. This study aims to determine whether the time of Chlamydia infection affects the genital tract microbiome. This study analyzed mice vaginal, uterine, and ovary/oviduct microbiome with and without Chlamydia infection. The mice were infected with Chlamydia at either 10:00 am (ZT3) or 10:00 pm (ZT15). The results showed that mice infected at ZT3 had higher Chlamydia infectivity than those infected at ZT15. There was more variation in the compositional complexity of the vaginal microbiome (alpha diversity) of mice infected at ZT3 than those mice infected at ZT15 throughout the infection within each treatment group, with both Shannon and Simpson diversity index values decreased over time. The analysis of samples collected four weeks post-infection showed that there were significant taxonomical differences (beta diversity) between different parts of the genital tract-vagina, uterus, and ovary/oviduct-and this difference was associated with the time of infection. Firmicutes and Proteobacteria were the most abundant phyla within the microbiome in all three genital tract regions for all the samples collected during this experiment. Additionally, Firmicutes was the dominant phylum in the uterine microbiome of ZT3 Chlamydia infected mice. The results show that the time of infection is associated with the microbial dynamics in the genital tract. And this association is more robust in the upper genital tract than in the vagina. This result implies that more emphasis should be placed on understanding the changes in the microbial dynamics of the upper genital tract over the course of infection.

Swi/Snf Chromatin Remodeling Regulates Transcriptional Interference and Gene Repression

Alternative transcription start sites can affect transcript isoform diversity and translation levels. In a recently described form of gene regulation, coordinated transcriptional and translational interference results in transcript isoform-dependent changes in protein expression. Specifically, a long undecoded transcript isoform (LUTI) is transcribed from a gene-distal promoter, interfering with expression of the gene-proximal promoter. While transcriptional and chromatin features associated with LUTI expression have been described, the mechanism underlying LUTI-based transcriptional interference is not well understood. Using an unbiased genetic approach followed by integrated genomic analysis, we uncovered that the Swi/Snf chromatin remodeling complex is required for co-transcriptional nucleosome remodeling that leads to LUTI-based repression. We identified genes with tandem promoters that rely on Swi/Snf function for transcriptional interference during protein folding stress, including LUTI-regulated genes. To our knowledge, this study is the first to observe Swi/Snf's direct involvement in gene repression via a cis transcriptional interference mechanism.

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.

Expression profile screening and bioinformatics analysis of CircRNA, LncRNA, and mRNA in HeLa cells infected with Chlamydia muridarum

We have previously shown that circRNAs in host cells are involved in the process of Chlamydia trachomatis infection. In this study we aimed to identify significantly altered circRNAs/lncRNAs/mRNAs in Chlamydia muridarum infected cells and investigate their biological functions in the interaction between Chlamydia muridarum and host cells. For this purpose, circRNA, lncRNA and mRNA expression profiles were screened and identified in HeLa cells with or without Chlamydia muridarum infection by microarray. Bioinformatics analyses including Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and Gene Ontology (GO) analysis were then carried out and the circRNA-miRNA ceRNA network was constructed. The differentially expressed circRNAs and lncRNAs were selected for validation by RT-qPCR. The results shown that a total of 834 circRNAs, 2149 lncRNAs and 1283 mRNAs were found to be differentially expressed. Enrichment analysis of GO and KEGG showed that the dysregulated genes involved nuclear-transcribed mRNA catabolic process, protein binding, RNA catabolic process and translation, the MAPK signaling pathway, apoptosis, Toll-like receptor signaling pathway, cAMP signaling pathway and Notch signaling pathway may play important roles in Chlamydia infection. Our study provides a systematic outlook on the potential function of non-coding RNAs in the molecular basis of Chlamydia infection.

A literature review on correlation between HPV coinfection with C. trachomatis in cervical neoplasia - coinfection mediated cellular transformation

Cervical cancer is the fourth most common cause of mortality worldwide. Persistent infection with high-risk human papillomaviruses (hrHPV) is a known significant risk factor in cervical neoplasia development (CN). Though HPV contributes to carcinogenesis, other factors fabricate an ideal niche for HPV persistent especially, coinfection with Chlamydia trachomatis (CT) which has been linked to CN development. CT infection is associated with inflammation, cell proliferation, EMT transition and anti-apoptotic processes. To better understand the correlation between HPV-CT coinfection in CN development, a literature review was conducted on the prevalence of HPV-CT coinfection focusing on the role of infection-induced inflammation as HPV-CT coinfection creates an environment for cellular transformation, activates an innate immune response and triggers EMT transition. Moreover, inflammation plays a crucial role in developing neoplasia as there is a decrease in effector cells and a change in the expression of players like ROS and miRs. The CT infection induces chronic inflammation followed by cervical epithelial cell damage and increases susceptibility to HPV infection which may lead to cellular transformation. The literature search was performed based on a comprehensive investigation of publications in the PubMed journal database and Scopus development of CN. We have reviewed the prevalence of HPV-CT infection and the factors increasing the risk of developing CN.

MicroRNA expression profiling of cerebrospinal fluid/serum exosomes in children with human herpesvirus 6-associated encephalitis/encephalopathy by high-throughput sequencing

Primary human herpesvirus 6 (HHV-6) infection is sometimes accompanied by acute encephalopathy with reduced subcortical diffusion (AED) in immunocompetent children. We investigated exosomal microRNA (miRNA) expression profiles in cerebrospinal fluid (CSF) and sera of patients with HHV-6-associated AED (n = 5) and febrile seizure (FS) (n = 5) using high-throughput sequencing. A total of 176 and 663 miRNAs were identified in CSF and serum exosomes, respectively. Comparative analysis determined that some miRNAs (miR-381-3p, miR-155) were exclusively expressed in the CSF exosomes of AED but not of FS patients, suggesting their potential application as novel diagnostic biomarkers for AED.

Chronic testicular Chlamydia muridarum infection impairs mouse fertility and offspring development†

With approximately 131 million new genital tract infections occurring each year, Chlamydia is the most common sexually transmitted bacterial pathogen worldwide. Male and female infections occur at similar rates and both cause serious pathological sequelae. Despite this, the impact of chlamydial infection on male fertility has long been debated, and the effects of paternal chlamydial infection on offspring development are unknown. Using a male mouse chronic infection model, we show that chlamydial infection persists in the testes, adversely affecting the testicular environment. Infection increased leukocyte infiltration, disrupted the blood:testis barrier and reduced spermiogenic cell numbers and seminiferous tubule volume. Sperm from infected mice had decreased motility, increased abnormal morphology, decreased zona-binding capacity, and increased DNA damage. Serum anti-sperm antibodies were also increased. When both acutely and chronically infected male mice were bred with healthy female mice, 16.7% of pups displayed developmental abnormalities. Female offspring of chronically infected sires had smaller reproductive tracts than offspring of noninfected sires. The male pups of infected sires displayed delayed testicular development, with abnormalities in sperm vitality, motility, and sperm-oocyte binding evident at sexual maturity. These data suggest that chronic testicular Chlamydia infection can contribute to male infertility, which may have an intergenerational impact on sperm quality.

MiR-378b Modulates Chlamydia-Induced Upper Genital Tract Pathology

Genital Chlamydia trachomatis infection causes severe reproductive pathologies such as salpingitis and pelvic inflammatory disease that can lead to tubal factor infertility. MicroRNAs (miRNAs) are evolutionarily conserved regulators of mammalian gene expression in development, immunity and pathophysiologic processes during inflammation and infection, including Chlamydia infection. Among the miRNAs involved in regulating host responses and pathologic outcome of Chlamydia infection, we have shown that miR-378b was significantly differentially expressed during primary infection and reinfection. In this study, we tested the hypothesis that miR-378b is involved in the pathological outcome of Chlamydia infection. We developed miR-378b knockout mice (miR-378b-/-) using Crispr/Cas and infected them along with their wild-type (WT) control with Chlamydia to compare the infectivity and reproductive pathologies. The results showed that miR-378b-/- mice were unable to clear the infection compared to WT mice; also, miR-378b-/- mice exhibited a relatively higher Chlamydia burden throughout the duration of infection. However, gross pathology results showed that miR-378b-/- mice had significantly reduced uterine dilatations and pathologic lesions after two infections compared to WT mice. In addition, the pregnancy and fertility rates for infected miR-378b-/- mice showed protection from Chlamydia-induced infertility with fertility rate that was comparable to uninfected WT mice. These results are intriguing as they suggest that miR-378b is important in regulating host immune responses that control Chlamydial replication and drive the inflammation that causes complications such as infertility. The finding has important implications for biomarkers of Chlamydial complications and targets for prevention of disease.

Analysis of microRNA expression profiles in human bronchial epithelial cells infected by Chlamydia psittaci

BACKGROUND

Chlamydia psittaci is a pathogen of birds that can cause zoonotic disease in mammals including pneumonia in humans. MicroRNAs (miRNAs) are a class of small non-coding RNA fragments with a length of about 22 nt, which play an important role in regulating gene expression after transcription. Chlamydia infection can cause changes in host cell miRNA expression, but the potential biological function of miRNAs in C. psittaci infection and pathogenesis is not well understood.

METHODS

Small RNA sequencing (sRNA-Seq) technology was used to characterise miRNA expression in human bronchial epithelial (HBE) cells after C. psittaci infection, and differentially expressed miRNAs were identified. Candidate target genes for these miRNAs were then functionally annotated by Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The sRNA-Seq results were partially validated by quantitative real time polymerase chain reaction (qRT-PCR) and miRNA-target networks were constructed using visualization software.

RESULTS

We identified 151 differentially expressed miRNAs (46 known miRNAs and 105 novel miRNAs) in C. psittaci-infected HBE cells, of which 140 were upregulated and 11 were downregulated. Of these, 17 known miRNAs were significantly upregulated and two were downregulated using P < 0.05 and |log₂FoldChange|>1.5 as threshold criteria. GO enrichment results showed that the predicted targets of these differentially expressed miRNAs were mainly involved in transcriptional regulation and ATP binding. KEGG pathway analysis suggested that the candidate target genes were involved in several important signaling pathways such as MAPK, ErbB, cGMP-PKG, cAMP, mTOR, GNRH, oxytocin, PI3K-Akt and AMPK, which are primarily related to biological processes such as transcription and signal transduction. The qRT-PCR results for miR-2116-3p, miR-3195, miR-663a, miR-10401-5p, miR-124-3p, miR-184, miR-744-5p and hsa-miR-514b-5p were consistent with the sRNA-Seq data.

CONCLUSIONS

A large amount of miRNA expression profile data relating to C. psittaci infection was obtained, which provides a useful experimental and theoretical basis for further understanding the pathogenic mechanisms of C. psittaci infection.

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.

MicroRNA-101-3p, MicroRNA-195-5p, and MicroRNA-223-3p in Peripheral Blood Mononuclear Cells May Serve as Novel Biomarkers for Syphilis Diagnosis

OBJECTIVES

Syphilis is a sexually transmitted disease of global prevalence. Current diagnostic methods lack sensitivity and specificity, which limits the early diagnosis and prognosis of the disease. MiRNAs hold great promise as potential biomarkers for infectious diseases diagnosis. We previously profiled the expression of miRNAs in PBMCs from patients with different stages of syphilis. We aimed to further confirm the miR-101-3p, miR-195-5p, and miR-223-3p expression profiles and evaluate their diagnostic value in syphilis infection.

METHODS

The expression levels of PBMC-derived miR-101-3p, miR-195-5p, and miR-223-3p were analyzed in 133 syphilis patients, 18 non-syphilis patients, and 23 healthy controls by RT-qPCR. ROC analysis was used to evaluate the differentiation power of these miRNAs in syphilis diagnosis, while the correlation between the expression of these miRNAs and TRUST titer was also statistically analyzed.

RESULTS

These miRNAs were significantly upregulated in syphilis patients in a stage-specific manner. ROC analysis indicated that miR-223-3p was powerful in discriminating between controls and patients with early, primary, secondary, and latent syphilis, as well as serological cure; the miR-195-5p/miR-223-3p panel showed an improved capacity to differentiate between syphilis patients, primary, or serofast-stage syphilis and controls, while the three miRNAs combined showed an improved capacity to differentiate latent syphilis or serological cure from controls. Importantly, miR-101-3p and miR-223-3p singly or jointly could specifically distinguish syphilis from non-syphilis patients. Moreover, TRUST titer was significantly correlated with miR-101-3p expression.

CONCLUSIONS

MiR-101-3p, miR-195-5p, and miR-223-3p might singly or jointly be potential diagnostic biomarkers at different stages of syphilis.

The role of miR-128-3p through MAPK14 activation in the apoptosis of GC2 spermatocyte cell line following heat stress

BACKGROUND

MicroRNAs play a crucial role in the regulation of spermatogenesis. For example, miR-128-3p expression is known to decrease significantly after testicular hyperthermia, but the regulatory effect of this change on the spermatogenesis damage caused by heat stress remains unclear.

OBJECTIVES

This study aimed to verify whether the target gene of miR-128-3p is MAPK14, which affects spermatogenic cell proliferation and apoptosis under testicular hyperthermia.

MATERIALS AND METHODS

Mouse testis and GC2 spermatocyte cell line heat stress models were established. miR-128-3p expression before and after heat stress was analyzed by reverse transcription polymerase chain reaction. MAPK14 and p-MAPK14 expression was detected by Western blot, and cell apoptosis was analyzed by Annexin V-FITC/PI. Subsequently, miR-128-3p inhibitors and mimics were used to interfere with spermatocytes before and after heat stress, respectively, for correlation detection.

RESULTS

Compared with the control group, the heat stress group showed decreased miR-128-3p expression, increased p-MAPK14 expression, and decreased cell proliferation activity. In the GC2-spd cell line in vitro, miR-128-3p inhibitors were found to upregulate p-MAPK14 expression, reduce cell proliferation activity, and increase apoptosis, consistent with the results obtained in the heat treatment alone. Furthermore, miR-128-3p mimics transfected in the GC2 cells after heat stress reduced p-MAPK14 expression, alleviated the decrease in cell proliferation, and decreased the apoptosis level.

CONCLUSIONS

The downregulation of miR-128-3p expression plays an important role in spermatogenesis damages after testicular hyperthermia, which is probably attributable to the activation of the MAPK signaling pathway. Downregulated miR-128-3p expression induces the apoptosis and inhibits the proliferation of spermatogenic cells by promoting MAPK14 phosphorylation.

Chlamydia trachomatis L2c Infection in a Porcine Model Produced Urogenital Pathology and Failed to Induce Protective Immune Responses Against Re-Infection

The current study was designed to evaluate the pathogenesis, pathology and immune response of female genital tract infection with Chlamydia trachomatis L2c, the most recently discovered lymphogranuloma venereum strain, using a porcine model of sexually transmitted infections. Pigs were mock infected, infected once or infected and re-infected intravaginally, and samples were obtained for chlamydial culture, gross and microscopic pathology, and humoral and cell-mediated immunity. Intravaginal inoculation of pigs with this bacterium resulted in an infection that was confined to the urogenital tract, where inflammation and pathology were caused that resembled what is seen in human infection. Re-infection resulted in more severe gross pathology than primary infection, and chlamydial colonization of the urogenital tract was similar for primary infected and re-infected pigs. This indicates that primary infection failed to induce protective immune responses against re-infection. Indeed, the proliferative responses of mononuclear cells from blood and lymphoid tissues to C. trachomatis strain L2c were never statistically different among groups, suggesting that C. trachomatis-specific lymphocytes were not generated following infection or re-infection. Nevertheless, anti-chlamydial antibodies were elicited in sera and vaginal secretions after primary infection and re-infection, clearly resulting in a secondary systemic and mucosal antibody response. While primary infection did not protect against reinfection, the porcine model is relevant for evaluating immune and pathogenic responses for emerging and known C. trachomatis strains to advance drug and/or vaccine development in humans.