Sexually dimorphic activation of innate antitumor immunity prevents adrenocortical carcinoma development.

Unlike most cancers, adrenocortical carcinomas (ACCs) are more frequent in women than in men, but the underlying mechanisms of this sexual dimorphism remain elusive. Here, we show that inactivation of Znrf3 in the mouse adrenal cortex, recapitulating the most frequent alteration in ACC patients, is associated with sexually dimorphic tumor progression. Although female knockouts develop metastatic carcinomas at 18 months, adrenal hyperplasia regresses in male knockouts. This male-specific phenotype is associated with androgen-dependent induction of senescence, recruitment, and differentiation of highly phagocytic macrophages that clear out senescent cells. In contrast, in females, macrophage recruitment is delayed and dampened, which allows for aggressive tumor progression. Consistently, analysis of TCGA-ACC data shows that phagocytic macrophages are more prominent in men and are associated with better prognosis. Together, these data show that phagocytic macrophages are key players in the sexual dimorphism of ACC that could be previously unidentified allies in the fight against this devastating cancer.

Identification of Arvicola terrestris scherman Sperm Antigens for Immune Contraceptive Purposes.

The cyclical proliferation of the wild fossorial rodent Arvicola terrestris scherman (ATS) is critical in mid-mountain ecosystems of several European countries. Our goal is to develop an immunocontraceptive vaccine to control their fertility, as a sustainable alternative to chemical poisons currently used. Indeed, these chemicals cause the death of ATS predators and animals sharing their ecosystem, and current laws progressively limit their use, making the development of a targeted vaccination strategy an interesting and efficient alternative. In order to identify species-specific sperm antigens, male and female ATS received subcutaneous injections of whole ATS spermatozoa to elicit an immune response. The analysis of the immune sera led to the identification of 120 immunogenic proteins of sperm cells. Of these, 15 were strictly sperm-specific and located in different regions of the male gamete. Some of these antigens are proteins involved in molecular events essential to the reproductive process, such as sperm-egg interaction, acrosomal reaction, or sperm motility. This approach not only identified a panel of immunogenic proteins from ATS sperm cells, but also demonstrated that some of these proteins trigger an immune response in both male and female ATS. These spermatic antigens are good candidates for the development of a contraceptive vaccine.

Absence of nuclear receptors LXRs impairs immune response to androgen deprivation and leads to prostate neoplasia.

Chronic inflammation is now a well-known precursor for cancer development. Infectious prostatitis are the most common causes of prostate inflammation, but emerging evidence points the role of metabolic disorders as a potential source of cancer-related inflammation. Although the widely used treatment for prostate cancer based on androgen deprivation therapy (ADT) effectively decreases tumor size, it also causes profound alterations in immune tumor microenvironment within the prostate. Here, we demonstrate that prostates of a mouse model invalidated for nuclear receptors liver X receptors (LXRs), crucial lipid metabolism and inflammation integrators, respond in an unexpected way to androgen deprivation. Indeed, we observed profound alterations in immune cells composition, which was associated with chronic inflammation of the prostate. This was explained by the recruitment of phagocytosis-deficient macrophages leading to aberrant hyporesponse to castration. This phenotypic alteration was sufficient to allow prostatic neoplasia. Altogether, these data suggest that ADT and inflammation resulting from metabolic alterations interact to promote aberrant proliferation of epithelial prostate cells and development of neoplasia. This raises the question of the benefit of ADT for patients with metabolic disorders.

The epididymal immune balance: a key to preserving male fertility.

Up to 15% of male infertility has an immunological origin, either due to repetitive infections or to autoimmune responses mainly affecting the epididymis, prostate, and testis. Clinical observations and epidemiological data clearly contradict the idea that the testis confers immune protection to the whole male genital tract. As a consequence, the epididymis, in which posttesticular spermatozoa mature and are stored, has raised some interest in recent years when it comes to its immune mechanisms. Indeed, sperm cells are produced at puberty, long after the establishment of self-tolerance, and they possess unique surface proteins that cannot be recognized as self. These are potential targets of the immune system, with the risk of inducing autoantibodies and consequently male infertility. Epididymal immunity is based on a finely tuned equilibrium between efficient immune responses to pathogens and strong tolerance to sperm cells. These processes rely on incompletely described molecules and cell types. This review compiles recent studies focusing on the immune cell types populating the epididymis, and proposes hypothetical models of the organization of epididymal immunity with a special emphasis on the immune response, while also discussing important aspects of the epididymal immune regulation such as tolerance and tumour control.

Comprehensive overview of murine epididymal mononuclear phagocytes and lymphocytes: Unexpected populations arise.

Despite increasing evidence that epididymal immune disorders can lead to infertility, the cells and mechanisms underlying epididymal immunity remain poorly understood. In this study, we propose a rather exhaustive overview of innate and adaptive immune cells present in the murine caput and cauda epididymis. Using flow cytometry and a wide set of markers, we screened the broadest panel of immune cells ever, in this organ. For the first time, we unequivocally quantified the innate populations of monocytes, macrophages, and dendritic cells subtypes. We also revealed the presence of B cells, gamma delta T cells, and double negative T cells in the murine epididymis. They were localized by immunofluorescence stainings, and appeared to be all present in the interstitium and epithelium along the organ, but with respective preferential regional distribution. Altogether, these findings provide new insights on the actors and potential mechanisms involved in the immune responses against genital tract ascending pathogens and in the setting and maintenance of tolerance toward the sperm cells.

MyD88 is crucial for the development of a protective CNS immune response to Toxoplasma gondii infection.

BACKGROUND: Toxoplasmosis is one of the most common parasitic infections in humans. It can establish chronic infection and is characterized by the formation of tissue cysts in the brain. The cysts remain largely quiescent for the life of the host, but can reactivate and cause life-threatening toxoplasmic encephalitis in immunocompromised patients, such as those with AIDS, neoplastic diseases and organ transplants. Toll-like receptor (TLR) adaptor MyD88 activation is required for the innate sensing of Toxoplasma gondii. Mice deficient in MyD88 have defective IL-12 and Th1 effector responses, and are highly susceptible to the acute phase of T. gondii infection. However, the role of this signaling pathway during cerebral infection is poorly understood and requires examination. METHOD: MyD88-deficient mice and control mice were orally infected with T. gondii cysts. Cellular and parasite infiltration in the peripheral organs and in the brain were determined by histology and immunohistochemistry. Cytokine levels were determined by ELISA and chemokine mRNA levels were quantified by real-time PCR (qPCR). RESULTS: Thirteen days after infection, a higher parasite burden was observed but there was no histological change in the liver, heart, lungs and small intestine of MyD88⁻/⁻ and MyD88⁺/⁺ mice. However, MyD88⁻/⁻ mice compared to MyD88⁺/⁺ mice were highly susceptible to cerebral infection, displayed high parasite migration to the brain, severe neuropathological signs of encephalitis and succumbed within 2 weeks of oral infection. Susceptibility was primarily associated with lower expression of Th1 cytokines, especially IL-12, IFN-γ and TNF-α, significant decrease in the expression of CCL3, CCL5, CCL7 and CCL19 chemokines, marked defect of CD8⁺ T cells, and infiltration of CD11b⁺ and F4/80⁺ cells in the brain. CONCLUSION: MyD88 is essential for the protection of mice during the cerebral installation of T. gondii infection. These results establish a role for MyD88 in T cell-mediated control of T. gondii in the central nervous system (CNS).

Functional activation of T cells by dendritic cells and macrophages exposed to the intracellular parasite Neospora caninum.

Neospora caninum is an intracellular protozoan pathogen that causes abortion in cattle. We studied how the interaction between murine conventional dendritic cells or macrophages and N. caninum influences the generation of cell-mediated immunity against the parasite. We first explored the invasion and survival ability of N. caninum in dendritic cells and macrophages. We observed that protozoa rapidly invaded and proliferated into these two cell populations. We then investigated how Neospora-exposed macrophages or dendritic cells distinguish between viable and non-viable (heat-killed tachyzoites and antigenic extract) parasites. Viable tachyzoites and antigenic extract, but not killed parasites, altered the phenotype of immature dendritic cells. Dendritic cells infected with viable parasites down-regulated the expression of MHC-II, CD40, CD80 and CD86 whereas dendritic cells exposed to N. caninum antigenic extract up-regulated the expression of MHC-II and CD40 and down-regulated CD80 and CD86 expression. Moreover, only viable tachyzoites and antigenic extract induced IL-12 synthesis by dendritic cells. MHC-II expression was up-regulated and CD86 expression was down-regulated at the surface of macrophages, regardless of the parasitic form was encountered. However, IL-12 secretion by macrophages was only observed under conditions using viable and heat-killed parasite. We then analysed how macrophages and dendritic cells were involved in inducing T-cell responses. T lymphocyte IFN-γ-secretion in correlation with IL-12 production occurred after interactions between T cells and dendritic cells exposed to viable tachyzoites or antigenic extract. By contrast, for macrophages IFN-γ production was IL-12-independent and only occurred after interactions between T cells and macrophages exposed to antigenic extract. Thus, N. caninum-induced activation of murine dendritic cells, but not that of macrophages, was associated with T cell IFN-γ production after IL-12 secretion.

Existence of CD8α-like dendritic cells with a conserved functional specialization and a common molecular signature in distant mammalian species.

The mouse lymphoid organ-resident CD8alpha(+) dendritic cell (DC) subset is specialized in Ag presentation to CD8(+) T cells. Recent evidence shows that mouse nonlymphoid tissue CD103(+) DCs and human blood DC Ag 3(+) DCs share similarities with CD8alpha(+) DCs. We address here whether the organization of DC subsets is conserved across mammals in terms of gene expression signatures, phenotypic characteristics, and functional specialization, independently of the tissue of origin. We study the DC subsets that migrate from the skin in the ovine species that, like all domestic animals, belongs to the Laurasiatheria, a distinct phylogenetic clade from the supraprimates (human/mouse). We demonstrate that the minor sheep CD26(+) skin lymph DC subset shares significant transcriptomic similarities with mouse CD8alpha(+) and human blood DC Ag 3(+) DCs. This allowed the identification of a common set of phenotypic characteristics for CD8alpha-like DCs in the three mammalian species (i.e., SIRP(lo), CADM1(hi), CLEC9A(hi), CD205(hi), XCR1(hi)). Compared to CD26(-) DCs, the sheep CD26(+) DCs show 1) potent stimulation of allogeneic naive CD8(+) T cells with high selective induction of the Ifngamma and Il22 genes; 2) dominant efficacy in activating specific CD8(+) T cells against exogenous soluble Ag; and 3) selective expression of functional pathways associated with high capacity for Ag cross-presentation. Our results unravel a unifying definition of the CD8alpha(+)-like DCs across mammalian species and identify molecular candidates that could be used for the design of vaccines applying to mammals in general.

Interleukin 17 receptor signaling is deleterious during Toxoplasma gondii infection in susceptible BL6 mice.

Th17 cells are involved in host defense against several pathogens. Using interleukin (IL) 17RA-deficient mice, we demonstrated reduced ileitis with diminished neutrophil recruitment and inflammatory lesions in the ileum, in the regional lymph node, in the spleen, and in the liver at day 7 and prolonged survival after Toxoplasma gondii infection. In addition, IL-17A antibody neutralization reduced inflammation and enhanced survival in BL6 mice. Diminished inflammation is associated with augmented interferon (IFN) gamma serum levels and enhanced production of IL-10 and IFN-gamma in cultured splenocytes upon antigen restimulation. Finally, cyst load and inflammation in the brain at 40 days are greater in surviving BL6 mice than in IL-17RA-deficient mice. In conclusion, oral T. gondii infection increases IL-17 expression and contributes to the inflammatory response, and IL-17 neutralization has a partial protective effect against fatal T. gondii-associated inflammation.

The XC chemokine receptor 1 is a conserved selective marker of mammalian cells homologous to mouse CD8alpha+ dendritic cells.

Human BDCA3+ dendritic cells (DCs) were suggested to be homologous to mouse CD8alpha+ DCs. We demonstrate that human BDCA3+ DCs are more efficient than their BDCA1+ counterparts or plasmacytoid DCs (pDCs) in cross-presenting antigen and activating CD8+ T cells, which is similar to mouse CD8alpha+ DCs as compared with CD11b+ DCs or pDCs, although with more moderate differences between human DC subsets. Yet, no specific marker was known to be shared between homologous DC subsets across species. We found that XC chemokine receptor 1 (XCR1) is specifically expressed and active in mouse CD8alpha+, human BDCA3+, and sheep CD26+ DCs and is conserved across species. The mRNA encoding the XCR1 ligand chemokine (C motif) ligand 1 (XCL1) is selectively expressed in natural killer (NK) and CD8+ T lymphocytes at steady-state and is enhanced upon activation. Moreover, the Xcl1 mRNA is selectively expressed at high levels in central memory compared with naive CD8+ T lymphocytes. Finally, XCR1-/- mice have decreased early CD8+ T cell responses to Listeria monocytogenes infection, which is associated with higher bacterial loads early in infection. Therefore, XCR1 constitutes the first conserved specific marker for cell subsets homologous to mouse CD8alpha+ DCs in higher vertebrates and promotes their ability to activate early CD8+ T cell defenses against an intracellular pathogenic bacteria.

Comparative genomics as a tool to reveal functional equivalences between human and mouse dendritic cell subsets.

During evolution, vertebrates have developed an adaptive immune system able to cope with a variety of pathogens. Dendritic cells (DCs) are central to this process. DCs integrate information derived from pathogens or endogenous danger signals and convey them to T lymphocytes. Most of the present knowledge on DCs was generated in mice or by using human DCs differentiated in vitro from monocytes. In both species, several DC subsets have been identified in vivo based on differences in their phenotypes, anatomical locations or functions. In mice, protective immunity against intracellular pathogens or tumors can be induced most efficiently by targeting antigens to the CD8 alpha(+) DCs, a subset of DCs which resides in lymphoid tissues and is especially efficient at cross-presenting exogenous antigens to CD8(+) T lymphocytes. In contrary, harnessing human DC subsets for medical purposes is currently hampered by insufficient knowledge about these cells. To overcome this cognitive gap, we are using comparative genomics as a tool for designing hypotheses and experiments to further characterize DC subset functions and their molecular control, including the investigation of the functional equivalences that might exist between human and mouse DC subsets.

A vaccine based on exosomes secreted by a dendritic cell line confers protection against T. gondii infection in syngeneic and allogeneic mice.

Our results show that exosomes secreted by SRDC pulsed in vitro with Toxoplasma gondii-derived antigens (Exo-TAg) induced protective responses against infection with the parasite in both syngeneic and allogeneic mice. After oral infection, syngeneic CBA/J mice exhibited significantly fewer cysts in their brains and allogeneic C57BL/6 mice survived. This protection was associated with strong humoral responses in vivo in serum from both CBA/J and C57BL/6 mice, and with high levels of anti-TAg IgA antibodies in intestinal secretions from CBA/J mice alone. Furthermore, strong cellular responses in vivo were observed in both mouse models. Cellular proliferation was associated with cytokines production by spleen and mesenteric lymph node cells. The results presented here show that exosomes are nucleic acid free vesicles that are able to induce immune responses correlated with protection against parasitic infections in both syngeneic and allogeneic mice. They could constitute an efficient tool for use in vaccination and antitumor strategies based on exosomes.