Differences in T regulatory cells between mouse strains frequently used in immunological research: Treg cell quantities and subpopulations in NOD, B6 and BALB/c mice.

Foxp3+ Regulatory T cells (Tregs) are essential for the maintenance of tolerance to self. Therefore, it is expected that lower numbers and/or less than optimal function could impact on the functioning of the immune system, and thereby contributing to the development of autoimmune diseases. In the present report, by comparing Tregs from most frequently used mouse strains in immunological research (C57BL/6 (B6), BALB/c and NOD), we provide evidence showing that the NOD mouse strain, highly predisposed to develop autoimmune responses, exhibit a generalized decreased in Tregs counts with enhanced proportions of CD44hiCD62Llow Tregs when compared with BALB/c mice. No major differences were observed in Helios+ or Helios- Tregs between strains. The expression of CXCR3, CCR5 and CCR6 on Tregs from all strains showed minor proportions of CXCR3+ and CCR5+ cells in NOD Tregs. Naïve CD4+CD25- T cells from NOD mice also showed decreased capacity to induce in vitro iTregs when compared with B6 and BALB/c mice. Lower expression of molecules involved in Treg suppressor mechanisms such as CD25, LAP-1, CD39 and PD-1 was observed both in NOD iTregs and Tregs from lymph nodes of NOD mice. Moreover, in vitro assays showed that Tregs from NOD mice exhibited reduced ability to suppress proliferation of CD4+CD25- responder T cells when compared with B6 and BALB/c mice. Major differences were consistently observed between NOD and BALB/c mice, whereas no major differences were found for many of the analyzed parameters between the NOD and B6 mice, suggesting that highly and mildly autoimmune prone mouse strains may share some Tregs features. On the contrary, BALB/c Tregs were in major quantities, expressed higher levels of Foxp3 and exhibited more potent ability to inhibit effector T cell proliferation, data that could be related to its natural resistance to the induction of different experimental autoimmune conditions. Altogether our results demonstrate a generalized Treg cell dysfunction in NOD mice, a strain characterized by its high predisposition to develop spontaneous and induced autoimmune diseases.

IL-10 Producing B Cells Dampen Protective T Cell Response and Allow Chlamydia muridarum Infection of the Male Genital Tract.

A significant proportion of individuals develop chronic, persistent and recurrent genital tract infections with Chlamydia trachomatis, which has been attributed to the numerous strategies that the bacterium uses to subvert host immune responses. Animal chlamydia models have demonstrated that protective immune response is mediated by CD4+ Th1 cytokine responses. Herein, we demonstrate that early after infecting the male genital tract, C. muridarum triggers the production of IL-10 by splenic and lymph node cells. In addition, C. muridarum triggers IL-6 and TNFα secretion. Data obtained from in vitro and in vivo experiments revealed B cells as the major IL-10 contributors. Indeed, purified B cells produced high amounts of IL-10 and also exhibited enhanced expression of inhibitory molecules such as CD39, PD-L1 and PD1 after C. muridarum stimulation. In vitro experiments performed with sorted cell subsets revealed that Marginal Zone B cells were the main IL-10 producers. In vitro and in vivo studies using TLR-deficient mice indicated that TLR4 signaling pathway was essential for IL-10 production. In addition, in vivo treatments to neutralize IL-10 or deplete B cells indicated that IL-10 and B cells played a significant role in delaying bacterial clearance ability. Moreover, the latter was confirmed by adoptive cell transfer experiments in which the absence of IL-10-producing B cells conferred the host a greater capability to induce Th1 responses and clear the infection. Interestingly, NOD mice, which were the least efficient in clearing the infection, presented much more Marginal Zone B counts and also enhanced TLR4 expression on Marginal Zone B cells when compared to B6 and BALB/c mice. Besides, treatment with antibodies that selectively deplete Marginal Zone B cells rendered mice more capable of inducing enhanced IFNγ responses and clearing the infection. Our findings suggest that B cells play a detrimental role in C. muridarum infection and that activation by innate receptors like TLR4 and IL-10 production by these cells could be used by Chlamydia spp. as a strategy to modulate the immune response establishing chronic infections in susceptible hosts.

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

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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.

Chronic Pelvic Pain Development and Prostate Inflammation in Strains of Mice With Different Susceptibility to Experimental Autoimmune Prostatitis.

BACKGROUND: Experimental autoimmune prostatitis (EAP) is an autoimmune inflammatory disease of the prostate characterized by peripheral prostate-specific autoimmune responses associated with prostate inflammation. EAP is induced in rodents upon immunization with prostate antigens (PAg) plus adjuvants and shares important clinical and immunological features with the human disease chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). METHODS: EAP was induced in young NOD, C57BL/6, and BALB/c male mice by immunization with PAg plus complete Freund́s adjuvant. Tactile allodynia was assessed using Von Frey fibers as a measure of pelvic pain at baseline and at different time points after immunization. Using conventional histology, immunohistochemistry, FACS analysis, and protein arrays, an interstrain comparative study of prostate cell infiltration and inflammation was performed. RESULTS: Chronic pelvic pain development was similar between immunized NOD and C57BL/6 mice, although the severity of leukocyte infiltration was greater in the first case. Coversely, minimal prostate cell infiltration was observed in immunized BALB/c mice, who showed no pelvic pain development. Increased numbers of mast cells, mostly degranulated, were detected in prostate samples from NOD and C57BL/6 mice, while lower total counts and resting were observed in BALB/c mice. Prostate tissue from NOD mice revealed markedly increased expression levels of inflammatory cytokines, chemokines, adhesion molecules, vascular endothelial growth factor, and metalloproteinases. Similar results, but to a lesser extent, were observed when analyzing prostate tissue from C57BL/6 mice. On the contrary, the expression of the above mediators was very low in prostate tissue from immunized BALB/c mice, showing significantly slight increments only for CXCL1 and IL4. CONCLUSIONS: Our results provide new evidence indicating that NOD, C57BL/6, and BALB/c mice develop different degrees of chronic pelvic pain, type, and amount of prostate cell infiltration and secretion of inflammatory mediators. Our results corroborate and support the notion that mice with different genetic background have different susceptibility to EAP induction. Prostate 77:94-104, 2017. © 2016 Wiley Periodicals, Inc.

IL-17 is not essential for inflammation and chronic pelvic pain development in an experimental model of chronic prostatitis/chronic pelvic pain syndrome.

Pain and inflammation in the absence of infection are hallmarks in chronic prostatitis and chronic pelvic pain syndrome (CP/CPPS) patients. The etiology of CP/CPPS is unclear, and autoimmunity has been proposed as a cause. Experimental autoimmune prostatitis (EAP) models have long been used for studying CP/CPPS. Herein, we studied prostate inflammation induction and chronic pelvic pain development in EAP using IL-12p40-KO, IL-4-KO, IL-17-KO, and wild-type (C57BL/6) mice. Prostate antigen (PAg) immunization in C57BL/6 mice induced specific Th1 and Th17 immune responses and severe prostate inflammation and cell infiltration, mainly composed of CD4 T cells and macrophages. Moreover, chronic pelvic pain was evidenced by increased allodynia responses. In immunized IL-17-KO mice, the presence of a prominent PAg-specific Th1 immune response caused similar prostate inflammation and chronic pelvic pain. Furthermore, markedly high PAg-specific Th1 immune responses, exacerbated prostate inflammation, and chronic pelvic pain were detected in immunized IL-4-KO mice. Conversely, immunized IL-12p40-KO mice developed PAg-specific Th2 immune responses, characterized by high IL-4 secretion and neither infiltration nor damage in the prostate. As observed in wild-type control animals, IL12p40-KO mice did not evidence tactile allodynia responses. Our results suggest that, as in patients, chronic pelvic pain is a consequence of prostate inflammation. After PAg immunization, a Th1-associated immune response develops and induces prostate inflammation and chronic pelvic pain. The absence of Th1 or Th2 cytokines, respectively, diminishes or enhances EAP susceptibility. In addition, IL-17 showed not to be essential for pathology induction and chronic pelvic pain development.

Expression of CXCR3 on specific T cells is essential for homing to the prostate gland in an experimental model of chronic prostatitis/chronic pelvic pain syndrome.

Experimental autoimmune prostatitis (EAP) is considered a valid model for the human disease chronic prostatitis/chronic pelvic pain syndrome. In this report, we analyzed phenotypic characteristics of T cells that gain access to the prostate and induce leukocyte recruitment in mice with different susceptibility to EAP. After EAP induction, NOD mice developed a specific cellular response characterized by a mixed Th1/Th17 pattern with specific T cells mainly expressing CXCR3 that infiltrated and damaged the prostate. In contrast, BALB/c mice, as well as NOD-IFN-γ(-/-), exhibited only Th17 cells mainly expressing CCR6 that were not capable of infiltrating the prostate gland. Adoptive transfer experiments of T cells from NOD or NOD-IFN-γ(-/-) mice to NOD-SCID recipients showed that only T cells from NOD mice successfully infiltrated the prostate. However, after "in vitro" or "in vivo" treatment with rIFN-γ, T cells from NOD-IFN-γ(-/-) mice became capable of homing to the prostate and induced leukocyte recruitment. Chemokine levels in prostate tissue from NOD mice showed increased expression levels of CXCR3 ligands. Additional experiments using adoptive transfer of sorted CXCR3(+)CD3(+) T cells or administrating a CXCR3 antagonist treatment confirmed these previous results. Altogether, our results demonstrate that the expression of CXCR3 on effector T cells is essential for their homing to the prostate gland in EAP. CXCR3 emerges as a potential therapeutic target to control chronic prostatitis/chronic pelvic pain syndrome.