Chlamydia muridarum infection-induced destruction of male germ cells and sertoli cells is partially prevented by Chlamydia major outer membrane protein-specific immune CD4 cells

Enhanced clearance of C. muridarum infection using azithromycin-loaded liposomes

Chlamydia trachomatis is an intracellular bacterium which infects around 129 million people annually. Despite similar infection rates between sexes, most research investigating the effects of chlamydial infection on fertility has focused on females. There is now emerging evidence of a potential link between Chlamydia and impaired male fertility. The only treatments for chlamydial infection are antibiotics, with azithromycin (AZI) being one of the commonly used drugs. However, recent studies have suggested that optimizing the treatment regime is necessary, as higher concentrations of AZI may be required to effectively clear the infection in certain cell types, particularly testicular macrophages. To address this challenge, we have prepared liposomes consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) loaded with AZI for clearing Chlamydia. These liposomes exhibited stability over time and were readily taken up by both macrophages and epithelial cells. Moreover, they demonstrated significant enhancement of chlamydial clearance in both cell types. In a mouse model, the drug-loaded liposomes cleared Chlamydia within the penile urethra more efficiently than the same dose of unencapsulated drug. Furthermore, the liposome-drug treatment showed significant protective effects on sperm motility and morphology, suggesting potential benefits in reducing sperm damage caused by the infection.

Modulating microbiome-immune axis in the deployment-related chronic diseases of Veterans: report of an expert meeting

The present report summarizes the United States Department of Veterans Affairs (VA) field-based meeting titled "Modulating microbiome-immune axis in the deployment-related chronic diseases of Veterans." Our Veteran patient population experiences a high incidence of service-related chronic physical and mental health problems, such as infection, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), various forms of hematological and non-hematological malignancies, neurologic conditions, end-stage organ failure, requiring transplantation, and posttraumatic stress disorder (PTSD). We report the views of a group of scientists who focus on the current state of scientific knowledge elucidating the mechanisms underlying the aforementioned disorders, novel therapeutic targets, and development of new approaches for clinical intervention. In conclusion, we dovetailed on four research areas of interest: 1) microbiome interaction with immune cells after hematopoietic cell and/or solid organ transplantation, graft-versus-host disease (GVHD) and graft rejection, 2) intestinal inflammation and its modification in IBD and cancer, 3) microbiome-neuron-immunity interplay in mental and physical health, and 4) microbiome-micronutrient-immune interactions during homeostasis and infectious diseases. At this VA field-based meeting, we proposed to explore a multi-disciplinary, multi-institutional, collaborative strategy to initiate a roadmap, specifically focusing on host microbiome-immune interactions among those with service-related chronic diseases to potentially identify novel and translatable therapeutic targets.

Detection of Chlamydia trachomatis inside spermatozoa using flow cytometry: Effects of antibiotic treatment (before and after) on sperm count parameters

There is increasing evidence that Chlamydia trachomatis (CT) infection can directly affect male fertility. However, only few have investigated the effects of CT on semen parameters, and mostly with inconclusive results. The main aims of this study were to identify CT inside spermatozoa, and the possible pre and post antibiotic treatment effects on the overall semen parameters. We developed a flow cytometric method for the detection of CT inside spermatozoa (SPI™). Briefly, sperm cells were fixed, membrane permeabilized and DNA was loosened using DNAse. Sperm cells were incubated with a primary monoclonal antibody against CT and with a secondary fluorescent antibody (vs primary), and analysed using a flow cytometer. Of 2415 infertile individuals, 48.61% were found positive for CT. 170 CT+ samples were included in the CT antibiotic treatment study. 78.82% (134/170) of the CT+ showed a significant reduction in the percentage of the iCT infected spermatozoa after the antibiotic treatment; 59.70% (80/134) decreased to non-detectable levels. Spermcount data were also recorded. Spermatozoa morphology (normal and teratozoospermia index, TZI) and motility (fast progressive and non-progressive spermatozoa) were statistically significant altered in CT+ pre-treatment vs control group. CT antibiotic treatment showed statistically significant effects on normal spermatozoa morphology, mid-piece and tail defects, and TZI. The study demonstrated that semen flow cytometric analysis of semen could be a valuable tool for faster and accurate identification of individuals with asymptomatic CT infection. It also identified a positive effect of antibiotic therapy on semen parameters, that could help males with infertility.

Sertoli Cell Immune Regulation: A Double-Edged Sword

The testis must create and maintain an immune privileged environment to protect maturing germ cells from autoimmune destruction. The establishment of this protective environment is due, at least in part, to Sertoli cells. Sertoli cells line the seminiferous tubules and form the blood-testis barrier (BTB), a barrier between advanced germ cells and the immune system. The BTB compartmentalizes the germ cells and facilitates the appropriate microenvironment necessary for spermatogenesis. Further, Sertoli cells modulate innate and adaptive immune processes through production of immunoregulatory compounds. Sertoli cells, when transplanted ectopically (outside the testis), can also protect transplanted tissue from the recipient’s immune system and reduce immune complications in autoimmune diseases primarily by immune regulation. These properties make Sertoli cells an attractive candidate for inflammatory disease treatments and cell-based therapies. Conversely, the same properties that protect the germ cells also allow the testis to act as a reservoir site for infections. Interestingly, Sertoli cells also have the ability to mount an antimicrobial response, if necessary, as in the case of infections. This review aims to explore how Sertoli cells act as a double-edged sword to both protect germ cells from an autoimmune response and activate innate and adaptive immune responses to fight off infections.

Long-term consequences of sexually transmitted infections on men's sexual function: A systematic review

Objective: To systematically review the available literature on the long-term effects of sexually transmitted diseases (STIs) on male reproductive functions.

Methods: A PubMed search was conducted on 3 January 2021, and as a result, 952 articles were retrieved. Exclusion of irrelevant articles resulted in 36 articles, dating from 1998 to 2020, which were analysed.

Results: Only 52.8% of these articles described original research, while the rest were reviews. The majority (26) of the articles dealt with bacterial infections, of which 20 described Chlamydia trachomatis. There were 11 articles that described research on viruses, with five on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The analysis of the articles showed further that not much new knowledge on the long-term effects on male reproductive functions has been added. The existing knowledge that ascending infections can cause epididymo-orchitis, prostatitis or urethritis was confirmed. Due to epithelial inflammatory responses these infections can result in scarring with resulting infertility due to obstruction. These effects were described for Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium or Treponema pallidum, as well as for the Zika and SARS-CoV-2 viruses. Even trichomoniasis can lead to long-term compromised male fertility if not treated.

Conclusion: In conclusion, problem awareness needs to be raised and more research on this important topic needs to be conducted.

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.

Therapeutic application of Sertoli cells for treatment of various diseases

Sertoli cells (SCs) are immune privileged cells found in the testis that function to immunologically protect maturing germ cells from immune destruction. This immune protection is due to the blood-testis-barrier, which prevents infiltration of cytotoxic immune cells and antibodies, and SC production of immunomodulatory factors, that favor a tolerogenic environment. The ability of SCs to create an immune privileged environment has led to the exploration of their potential use in the treatment of various diseases. SCs have been utilized to create a tolerogenic ectopic microenvironment, to protect co-grafted cells, and to deliver therapeutic proteins through gene therapy. To date, numerous studies have reported the potential use of SCs for the treatment of diabetes, neurodegenerative disorders, and restoration of spermatogenesis. Additionally, SCs have been investigated as a delivery vehicle for therapeutic products to treat other diseases like Laron syndrome, muscular dystrophy, and infections. This review will provide an overview of these therapeutic applications.

The effect of Chlamydia infection on koala (Phascolarctos cinereus) semen quality

Although it is well established that chlamydial disease renders female koalas infertile, there has been limited research on its effects on male koala fertility, specifically sperm quality. This study determined whether chlamydial infection adversely affects semen quality of naturally infected koalas and spermatozoa recovered from Chlamydia negative koalas co-incubated in vitro with C. pecorum elementary bodies (EBs). Semen from 102 south-east Queensland sexually mature wild koalas exhibiting varying degrees of chlamydiosis and clinical signs of disease were assessed for semen quality and compared to 11 clinically healthy, Chlamydia-free captive male koalas. For in vitro studies, semen samples were collected from 6 Chlamydia-free captive koalas, and co-incubated over 24 h with high and low concentrations of C. pecorum EBs and sperm quality assessed. Wild koalas displaying severe signs of clinical disease with C. pecorum present in the semen had significantly greater sperm DNA damage (P = 0.0267). The total % of morphologically abnormal spermatozoa was highest in wild koalas that had severe signs of clinical disease but whose semen was negative for C. pecorum (P = 0.0328). This apparent contradiction is possibly associated with wild males having resolved the infection but still possessing underlining reproductive pathology. A higher incidence of loose head spermatozoa occurred in semen of wild koalas not infected with C. pecorum compared to those that were C. pecorum infected (P = 0.026). In vitro incubation of semen with C. pecorum significantly decreased sperm motility and viability over 24 h.

Hematogenous dissemination of Chlamydia muridarum from the urethra in macrophages causes testicular infection and sperm DNA damage†

The incidence of Chlamydia infection, in both females and males, is increasing worldwide. Male infections have been associated clinically with urethritis, epididymitis, and orchitis, believed to be caused by ascending infection, although the impact of infection on male fertility remains controversial. Using a mouse model of male chlamydial infection, we show that all the major testicular cell populations, germ cells, Sertoli cells, Leydig cells, and testicular macrophages can be productively infected. Furthermore, sperm isolated from vas deferens of infected mice also had increased levels of DNA damage as early as 4 weeks post-infection. Bilateral vasectomy, prior to infection, did not affect the chlamydial load recovered from testes at 2, 4, and 8 weeks post-infection, and Chlamydia-infected macrophages were detectable in blood and the testes as soon as 3 days post-infection. Partial depletion of macrophages with clodronate liposomes significantly reduced the testicular chlamydial burden, consistent with a hematogenous route of infection, with Chlamydia transported to the testes in infected macrophages. These data suggest that macrophages serve as Trojan horses, transporting Chlamydia from the penile urethra to the testes within 3 days of infection, bypassing the entire male reproductive tract. In the testes, infected macrophages likely transfer infection to Leydig, Sertoli, and germ cells, causing sperm DNA damage and impaired spermatogenesis.

The occurrence and pathology of chlamydiosis in the male reproductive tract of non-human mammals: A review

Organisms belonging to the Family Chlamydiaceae are responsible for a broad range of diseases in humans, livestock, companion animals and non-domestic species. Infection of the reproductive organs can cause a range of syndromes of which sub- and infertility are the most frequently observed clinical manifestations. While the gross and histological lesions associated with the isolation of Chlamydiaceae from the non-human female reproductive tract are well documented, little attention has been given to the pathological effects of this infection in the male genital system. As such, the occurrence and importance of Chlamydia-associated disease in male non-human mammalian species is less well documented. In order to improve our understanding of the significance of chlamydiosis in domestic, laboratory and wild animals, this review provides an up-to-date summary of Chlamydia-associated male reproductive pathology, whether that infection occurs naturally or experimentally. Although most lesions in males are described as incidental and of minor significance, results of recent studies suggest that infection with Chlamydiaceae can adversely impact male fertility and/or be instrumental in disease transmission. Although in humans, bulls and mice Chlamydia infection has been associated with morphological and functional abnormalities of the spermatozoa, this review will focus on the gross and histological findings linked to the colonisation of the genital system by this pathogen. Advances in our understanding of male reproductive chlamydiosis are necessary for diagnostic and therapeutic strategies, as well as epidemiological and conservation studies.

Detection of chlamydia infection within human testicular biopsies

STUDY QUESTION

Can Chlamydia be found in the testes of infertile men?

SUMMARY ANSWER

Chlamydia can be found in 16.7% of fresh testicular biopsies and 45.3% of fixed testicular biopsies taken from a selection of infertile men.

WHAT IS KNOWN ALREADY

Male chlamydial infection has been understudied despite male and female infections occurring at similar rates. This is particularly true of asymptomatic infections, which occur in 50% of cases. Chlamydial infection has also been associated with increased sperm DNA damage and reduced male fertility.

STUDY DESIGN, SIZE, DURATION

We collected diagnostic (fixed, n = 100) and therapeutic (fresh, n = 18) human testicular biopsies during sperm recovery procedures from moderately to severely infertile men in a cross-sectional approach to sampling.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The diagnostic and therapeutic biopsies were tested for Chlamydia-specific DNA and protein, using real-time PCR and immunohistochemical approaches, respectively. Serum samples matched to the fresh biopsies were also assayed for the presence of Chlamydia-specific antibodies using immunoblotting techniques.

MAIN RESULTS AND THE ROLE OF CHANCE

Chlamydial major outer membrane protein was detected in fixed biopsies at a rate of 45.3%. This was confirmed by detection of chlamydial DNA and TC0500 protein (replication marker). C. trachomatis DNA was detected in fresh biopsies at a rate of 16.7%, and the sera from each of these three positive patients contained C. trachomatis-specific antibodies. Overall, C. trachomatis-specific antibodies were detected in 72.2% of the serum samples from the patients providing fresh biopsies, although none of the patients were symptomatic nor had they reported a previous sexually transmitted infection diagnosis including Chlamydia.

LIMITATIONS, REASONS FOR CAUTION

No reproductively healthy male testicular biopsies were tested for the presence of Chlamydia DNA or proteins or Chlamydia-specific antibodies due to the unavailability of these samples.

WIDER IMPLICATIONS FOR THE FINDINGS

Application of Chlamydia-specific PCR and immunohistochemistry in this human male infertility context of testicular biopsies reveals evidence of a high prevalence of previously unrecognised infection, which may potentially have a pathogenic role in spermatogenic failure.

STUDY FUNDING/COMPETING INTEREST(S)

Funding for this project was provided by the Australian NHMRC under project grant number APP1062198. We also acknowledge assistance from the Monash IVF Group and Queensland Fertility Group in the collection of fresh biopsies, and the Monash Health and co-author McLachlan (declared equity interest) in retrieval and sectioning of fixed biopsies. E.M. declares an equity interest in the study due to financing of fixed biopsy sectioning. All other authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Effects of bacteria on male fertility: Spermatogenesis and sperm function

Bacterial infection can negatively affect different parts of the male genital tract and subsequently cause impaired spermatogenesis and male fertility. However, most of the previous studies have focused on the infected organs of the male genital tract and there are not many studies that investigated the direct effect of bacteria on sperm and their mechanism of action. Interestingly, bacteria can induce different damages on sperm cells such as DNA fragmentation, cell membrane peroxidation, and acrosome impairment. Such negative effects can be mediated by bacteria-secreted toxins and metabolites or by direct attachment of bacteria on the sperm cells and subsequent activation of signaling pathways related to oxidative stress, apoptosis, and inflammation. These bacteria-induced changes can impair semen parameters and subsequently cause infertility. Given the significant destructive effect of some bacteria on sperm function and male fertility, in this study, we reviewed the impact of male urogenital bacteria on spermatogenesis and sperm functions as well as the underlying mechanisms by which the bacteria can damage sperm.

Growth kinetics of Chlamydia trachomatis in primary human Sertoli cells

Chlamydia trachomatis (Ct) is the leading cause of bacterial sexually transmitted infections worldwide and has been associated with male infertility. Recently, it was hypothesized that Ct may infect the epithelium of the seminiferous tubule, formed by Sertoli cells, thus leading to impaired spermatogenesis. To date, there is a lack of data on Ct infection of the seminiferous epithelium; therefore, we aimed to characterize, for the first time, an in vitro infection model of primary human Sertoli cells. We compared Ct inclusion size, morphology and growth kinetics with those in McCoy cells and we studied F-actin fibres, Vimentin-based intermediate filaments and α-tubulin microtubules in Sertoli and McCoy cells. Our main finding highlighted the ability of Ct to infect Sertoli cells, although with a unique growth profile and the inability to exit host cells. Furthermore, we observed alterations in the cytoskeletal fibres of infected Sertoli cells. Our results suggest that Ct struggles to generate a productive infection in Sertoli cells, limiting its dissemination in the host. Nevertheless, the adverse effect on the cytoskeleton supports the notion that Ct may compromise the blood-testis barrier, impairing spermatogenesis.

Male infertility: the intracellular bacterial hypothesis

Infertility is a disease that affects one in seven couples. As male infertility affects approximately 30% of these couples with an unknown cause in half the cases, it represents a major public health concern. The classic treatment of male infertility involves intrauterine insemination, with modest outcome, and in vitro fertilization with intracytoplasmic sperm injection, which is known to be invasive and expensive, without treating the specific cause of infertility. Male fertility is mainly evaluated through a semen assessment where abnormal parameters such as concentration and motility can be associated with a decreased chance of conception. Infectious processes represent plausible candidates for male infertility. Chlamydia trachomatis is well known to cause female infertility through tubal damage but its role in male infertility remains controversial. The link between ureaplasmas/mycoplasmas and male infertility is also debatable. The potential negative impact of these bacteria on male fertility might not only involve semen parameters but also, as with C. trachomatis, include important physiological mechanisms such as fertilization processes that are not routinely assessed during infertility investigation. Basic research is important to help determine the exact effect of these bacteria on male fertility to develop targeted treatment and go beyond in vitro fertilization with intracytoplasmic sperm injection.

Male genital tract immune response against Chlamydia trachomatis infection

Chlamydia trachomatis is the most commonly reported agent of sexually transmitted bacterial infections worldwide. This pathogen frequently leads to persistent, long-term, subclinical infections, which in turn may cause severe pathology in susceptible hosts. This is in part due to the strategies that Chlamydia trachomatis uses to survive within epithelial cells and to evade the host immune response, such as subverting intracellular trafficking, interfering signaling pathways and preventing apoptosis. Innate immune receptors such as toll-like receptors expressed on epithelial and immune cells in the genital tract mediate the recognition of chlamydial molecular patterns. After bacterial recognition, a subset of pro-inflammatory cytokines and chemokines are continuously released by epithelial cells. The innate immune response is followed by the initiation of the adaptive response against Chlamydia trachomatis, which in turn may result in T helper 1-mediated protection or in T helper 2-mediated immunopathology. Understanding the molecular mechanisms developed by Chlamydia trachomatis to avoid killing and host immune response would be crucial for designing new therapeutic approaches and developing protective vaccines. In this review, we focus on chlamydial survival strategies and the elicited immune responses in male genital tract infections.

Chlamydia trachomatis neither exerts deleterious effects on spermatozoa nor impairs male fertility

Chlamydia trachomatis is the most prevalent sexually transmitted bacterial infection. However, whether Chlamydia trachomatis has a negative impact on sperm quality and male fertility is still controversial. Herein, we report the effects on sperm quality of the in vitro exposure of spermatozoa to Chlamydia trachomatis, and also the effects of male genital infection on male fertility using an animal model. Human and mouse sperm were obtained from healthy donors and cauda epididimys from C57BL/6 mice, respectively. Highly motile human or mouse spermatozoa were in vitro exposed to C. trachomatis (serovar E or LGV) or C. muridarum, respectively. Then, sperm quality parameters were analyzed. Moreover, male fertility of Chlamydia muridarum infected male C57BL/6 mice was assessed. Human or murine sperm in vitro exposed to increasing bacterial concentrations or soluble factors from C. trachomatis or C. muridarum, respectively, did not show differences in sperm motility and viability, apoptosis, mitochondrial membrane potential, DNA fragmentation, ROS production and lipid peroxidation levels, when compared with control sperm (p > 0.05). Moreover, no differences in fertility parameters (potency, fecundity, fertility index, pre- and post-implantation loss) were observed between control and infected males. In conclusion, our results indicate that Chlamydia spp. neither directly exerts deleterious effects on spermatozoa nor impairs male fertility.

Chronic Infection of the Prostate by Chlamydia muridarum Is Accompanied by Local Inflammation and Pelvic Pain Development

BACKGROUND

Chlamydia trachomatis urogenital infections are the leading cause of sexually transmitted bacterial infections. Although the prevalence of chlamydial infection is similar in men and women, current research is mainly focused on women, neglecting the study of male genital tract infections. We, therefore, investigated Chlamydia infection in the rodent male genital tract.

MATERIALS AND METHODS

Male NOD and C57BL/6 mice were inoculated in the meatus urethra with C. muridarum. Bacterial DNA, leukocyte infiltration of male genital tract tissues, pelvic pain, and Chlamydia-specific immune responses were analyzed at different time points.

RESULTS AND CONCLUSIONS

The inoculation of C. muridarum in the meatus urethra of male mice resulted in an ascending and widely disseminated infection of the male genital tract. C. muridarum remained longer and with the highest bacterial burdens in the prostate, thus showing a special tropism for this organ. Infection caused leukocyte infiltration, mainly composed by neutrophils, and also induced early pelvic pain development that rapidly dropped and resolved as the infection became chronic. Bacterial load and leukocyte infiltration was observed in all prostate lobes, although dorsolateral prostate was the most affected lobe. Interestingly, immune responses induced by both mice strains were characterized by the production of high levels of IL-10 during early stages of the infection, with highest and sustained levels observed in NOD mice, which showed to be less efficient in clearing the infection. Chronic infection of the prostate accompanied by local inflammation and pelvic pain development described herein have important implications for the improvement of the diagnosis and for the design of new efficient therapies. Prostate 77:517-529, 2017. © 2017 Wiley Periodicals, Inc.