Uropathogenic Escherichia coli Infection Compromises the Blood-Testis Barrier by Disturbing mTORC1-mTORC2 Balance.

The structural and functional destruction of the blood-testis barrier (BTB) following uropathogenic E. coli (UPEC) infection may be a critical component of the pathologic progress of orchitis. Recent findings indicate that the mammalian target of the rapamycin (mTOR)-signaling pathway is implicated in the regulation of BTB assembly and restructuring. To explore the mechanisms underlying BTB damage induced by UPEC infection, we analyzed BTB integrity and the involvement of the mTOR-signaling pathway using in vivo and in vitro UPEC-infection models. We initially confirmed that soluble virulent factors secreted from UPEC trigger a stress response in Sertoli cells and disturb adjacent cell junctions via down-regulation of junctional proteins, including occludin, zonula occludens-1 (ZO-1), F-actin, connexin-43 (CX-43), ß-catenin, and N-cadherin. The BTB was ultimately disrupted in UPEC-infected rat testes, and blood samples from UPEC-induced orchitis in these animals were positive for anti-sperm antibodies. Furthermore, we herein also demonstrated that mTOR complex 1 (mTORC1) over-activation and mTORC2 suppression contributed to the disturbance in the balance between BTB "opening" and "closing." More importantly, rapamycin (a specific mTORC1 inhibitor) significantly restored the expression of cell-junction proteins and exerted a protective effect on the BTB during UPEC infection. We further confirmed that short-term treatment with rapamycin did not aggravate spermatogenic degeneration in infected rats. Collectively, this study showed an association between abnormal activation of the mTOR-signaling pathway and BTB impairment during UPEC-induced orchitis, which may provide new insights into a potential treatment strategy for testicular infection.

Chlamydia trachomatis elicits TLR3 expression but disrupts the inflammatory signaling down-modulating NFκB and IRF3 transcription factors in human Sertoli cells.

Chlamydia trachomatis, the leading cause of bacterial sexually transmitted diseases worldwide, can disseminate and localize to the upper genital tract impairing reproductive function. Specifically, ascending C. trachomatis genital infection has been demonstrated to cause epididymitis or epididymo-orchitis, well-known risk factors for male infertility. C. trachomatis possesses the ability to infect primary human Sertoli cells, key elements for the spermatogenetic process and the immune protection of germ cells. Therefore, herein, we investigated the innate immune response in Sertoli cells following C. trachomatis infection, as well as its indirect effects on human spermatozoa. Specifically, we evaluated C. trachomatis mediated induction of Toll-like Receptors (TLR) 2, 3 and 4 as well as of downstream intracellular signaling molecules (NFκB and IRF3) and the levels of the related inflammatory mediators (IL-1α, IL-6, IFN-α, IFN-ß and IFN-γ), in an in vitro infection model of primary human Sertoli cells. The main result of our study shows that C. trachomatis induced TLR3-mediated recognition in human Sertoli cells, accompanied by the down-modulation of NFκB and IRF3-dependent signaling pathways followed by no production of pro-inflammatory cytokines. In conclusion, our findings suggest that C. trachomatis can disrupt the innate immune response in Sertoli cells and evade intracellular killing, potentially giving rise to a long-term infection that may exert negative effects on the male reproductive system.

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.

Uropathogenic Escherichia coli Epigenetically Manipulate Host Cell Death Pathways.

Urinary tract infections caused by uropathogenic Escherichia coli (UPEC) pathovars belong to the most frequent infections in human. It is well established that UPEC can subvert innate immune responses, but the role of UPEC in interfering with host cell death pathways is not known. Here, we show that UPEC abrogates activation of the host cell prosurvival protein kinase B signaling pathway, which results in the activation of mammalian forkhead box O (FOXO) transcription factors. Although FOXOs were localized in the nucleus and showed increased DNA-binding activity, no change in the expression levels of FOXO target genes were observed. UPEC can suppress BIM expression induced by LY249002, which results in attenuation of caspase 3 activation and blockage of apoptosis. Mechanistically, BIM expression appears to be epigenetically silenced by a decrease in histone 4 acetylation at the BIM promoter site. Taken together, these results suggest that UPEC can epigenetically silence BIM expression, a molecular switch that prevents apoptosis.

Expression of IL-1alpha, IL-6, TGF-beta, FasL and ZNF265 during sertoli cell infection by ureaplasma urealyticum.

To investigate immunoregulatory mechanisms of Sertoli cells in the testis in vitro and in vivo, we utilized our well-characterized Ureaplasma Urealyticum (UU)-induced model. We investigated the expressions of IL-1alpha, IL-6, TGF-beta, FasL and ZNF265 at the first, second and third weeks post-infection. During recovery from inflammation and with the help of negative regulators TGF-beta and FasL, the high levels of IL-1alpha and IL-6 expressions were observed in the early stages of the infection, and decreased gradually in the later weeks both in vitro and in vivo. The trend of varied expression of ZNF265 was similar to those of TGF-beta and FasL in vitro and in vivo for Sertoli cells infected with UU.

Development-dependent replication of minute virus of mice in differentiated mouse testicular cell lines.

The replication of the autonomous parvovirus, minute virus of mice (MVM), requires mitotically active cells and depends on certain factors expressed by cells of particular differentiated phenotype. As an approach to the understanding of these helper functions, we studied the interaction of the fibrotropic [MVM(p)] and the lymphotropic [MVM(i)] strains of MVM with two differentiated cell lines from mouse testicular epithelial origins. The relative support given to viral expression by these cell lines varied extensively. Cells from Sertoli origin (TM4) were permissive to MVM(p) but were mostly restrictive to MVM(i). The other cell line, of Leydig cell origin (TM3), was highly restrictive to both viral strains, but the blocks to their growth in these cells were localized at different stages of their growth cycle, suggesting that the replication of MVM in these cells requires tissue-specific helper functions during at least two stages of viral replication.

Testicular lesions in Whipple's disease.

In two patients with Whipple's disease a variety of abnormalities were found in the testis. In both there was a thickened tunica albuginea containing macrophages filled with Schiff-positive bacilli, and both exhibited Whipple bacilli alone or in small clumps within the tunica media of the testicular arteries. One patient had focal inflammatory lesions among the Leydig cells. The most prominent abnormality in each was the abundance of Whipple bacilli within the epithelium of the seminiferous tubules. Some of these bacilli (which were free rather than within macrophages) appeared to be being shed into the tubular lumen; there was no associated inflammation. In some areas macrophages filled with bacilli appeared to migrate from the arterial adventitia toward the seminiferous tubules. Potential significance of these findings is discussed relative to a variety of testicular and prostatic diseases, as well as the possible (and arguable) relationship to the acquired immune deficiency syndrome.