The olfactory mucosa, first actor of olfactory detection, is sensitive to glucocorticoid hormone.

The olfactory mucosa (OM) is the primary site of odorant detection, and its axonal projections relay information to brain structures for signal processing. We have previously observed that olfactory function can be affected during a prolonged stress challenge in Wistar rats. The stress response is a neuroendocrine retro-controlled loop allowing pleiotropic adaptive tissue alterations, which are partly mediated through the release of glucocorticoid hormones. We hypothesised that, as part of their wide-ranging pleiotropic effects, glucocorticoids might affect the first step of olfactory detection. To study this, we used a number of approaches ranging from the molecular detection and functional characterisation of glucocorticoid receptors (GRs) in OM cells, to the study of GR acute activation in vivo at the molecular, electrophysiological and behavioural levels. In contrast to previous reports, where GR was reported to be exclusive in olfactory sensory neurones, we located functional GR expression mostly in olfactory ensheathing cells. Dexamethasone (2 mg/kg) was injected intraperitoneally to activate GR in vivo, and this led to functional odorant electrophysiological response (electro-olfactogram) and OM gene expression changes. In a habituation/cross-habituation test of olfactory sensitivity, we observed that DEX-treated rats exhibited higher responsiveness to a complex odorant mixture. These findings support the idea that olfactory perception is altered in stressed animals, as glucocorticoids might enhance odour detection, starting at the first step of detection.

Effect of environmental exposure to a maternally-learned odorant on anxiety-like behaviors at weaning in mice.

Early sensory experience, such as exposure to maternal or other environmental factors, is considered to influence neurocognitive development and behaviors. In many species, exposure to odorants during pregnancy or lactation impacts the morpho-functional development of the olfactory circuitry with changes in olfactory sensitivity, feeding behavior and food preferences at birth or later. However, few studies have investigated the impact of a perinatal exposure to odorants on the anxiety-like behavior of animals to stressfull stimuli. Here, we exposed mice to heptaldehyde (HEP) during pregnancy and lactation and measured the anxiety-like behavior of their offspring to stress-inducing novel stimuli at weaning in presence or absence of odorants. We applied a combined social and maternal separation as a stressor and measured the anxiety-like behavior in an open field (OF) in presence of two odorants, HEP or α-pinene (AP) as a control odorant. Although the presence of the odorant during the social separation did not influence anxiety-like behavior, we found that, if mice born to non-odorized mothers exhibited a decreased exploratory behavior in the presence of both odorants, the effect was restricted to AP for the mice perinatally exposed to HEP. These results show that anxiety-like behaviors during a stress-inducing event could be reduced by the presence of a familiar odorant. We propose that the recall of an early olfactory experience could contribute to the improvement of animal welfare in various situations associated with husbandry practices.

IL-17c is involved in olfactory mucosa responses to Poly(I:C) mimicking virus presence.

At the interface of the environment and the nervous system, the olfactory mucosa (OM) is a privileged pathway for environmental toxicants and pathogens towards the central nervous system. The OM is known to produce antimicrobial and immunological components but the mechanisms of action of the immune system on the OM remain poorly explored. IL-17c is a potent mediator of respiratory epithelial innate immune responses, whose receptors are highly expressed in the OM of mice. We first characterized the presence of the IL-17c and its receptors in the OM. While IL-17c was weakly expressed in the control condition, it was strongly expressed in vivo after intranasal administration of polyinosinic-polycytidylic (Poly I:C), a Toll Like Receptor 3 agonist, mimicking a viral infection. Using calcium imaging and electrophysiological recordings, we found that IL-17c can effectively activate OM cells through the release of ATP. In the longer term, intranasal chronic instillations of IL-17c increased the cellular dynamics of the epithelium and promoted immune cells infiltrations. Finally, IL-17c decreased cell death induced by Poly(I:C) in an OM primary culture. The OM is thus a tissue highly responsive to immune mediators, proving its central role as a barrier against airway pathogens.

DMRT1 is a testis-determining gene in rabbits and is also essential for female fertility.

DMRT1 is the testis-determining factor in several species of vertebrates, but its involvement in mammalian testes differentiation, where SRY is the testis-determining gene, remains ambiguous. So far, DMRT1 loss-of-function has been described in two mammalian species and induces different phenotypes: Disorders of Sex Development (46, XY DSD) in men and male infertility in mice. We thus abolished DMRT1 expression by CRISPR/Cas9 in a third species of mammal, the rabbit. First, we observed that gonads from XY DMRT1-/- rabbit fetuses differentiated like ovaries, highlighting that DMRT1 is involved in testis determination. In addition to SRY, DMRT1 is required in the supporting cells to increase the expression of the SOX9 gene, which heads the testicular genetic cascade. Second, we highlighted another function of DMRT1 in the germline since XX and XY DMRT1-/- ovaries did not undergo meiosis and folliculogenesis. XX DMRT1-/- adult females were sterile, showing that DMRT1 is also crucial for female fertility. To conclude, these phenotypes indicate an evolutionary continuum between non-mammalian vertebrates such as birds and non-rodent mammals. Furthermore, our data support the potential involvement of DMRT1 mutations in different human pathologies, such as 46, XY DSD as well as male and female infertility.

Animals that reproduce sexually have organs called gonads, the ovaries and testes, which produce eggs and sperm. These organs, which are different in males and females, originate from the same cells during the development of the embryo. As a general rule, the chromosomal sex of an embryo, which gets determined at fertilization, leads to the activation and repression of specific genes. This in turn, controls whether the cells that will form the gonads will differentiate to develop testes or ovaries. Disruption of the key genes involved in the differentiation of the gonads can lead to fertility problems, and in some cases, it can cause the gonads to develop in the 'opposite' direction, resulting in a sex reversal. Identifying these genes is therefore essential to know how to maintain or restore fertility. DMRT1 is a gene that drives the differentiation of gonadal cells into the testicular pathway in several species of animals with backbones, including species of fish, frogs and birds. However, its role in mammals ­ where testis differentiation is driven by a different gene called SRY ­ is not well understood. Indeed, when DMRT1 is disrupted in male humans it leads to disorders of sex development, while disrupting this gene in male mice causes infertility. To obtain more information about the roles of DMRT1 in mammalian species, Dujardin et al. disrupted the gene in a third species of mammal: the rabbit. Dujardin et al. observed that chromosomally-male rabbits lacking DMRT1 developed ovaries instead of testes, showing that in rabbits, both SRY and DMRT1 are both required to produce testes. Additionally, this effect is similar to what is seen in humans, suggesting that rabbits may be a better model for human gonadal differentiation than mice are. Additionally, Dujardin et al. were also able to show that in female rabbits, lack of DMRT1 led to infertility, an effect that had not been previously described in other species. The results of Dujardin et al. may lead to better models for gonadal development in humans, involving DMRT1 in the differentiation of testes. Interestingly, they also suggest the possibility that mutations in this gene may be responsible for some cases of infertility in women. Overall, these findings indicate that DMRT1 is a key fertility gene.

Absence of Testicular Estrogen Leads to Defects in Spermatogenesis and Increased Semen Abnormalities in Male Rabbits.

Estrogens are steroid hormones produced by the aromatization of androgens by the aromatase enzyme, encoded by the CYP19A1 gene. Although generally referred to as "female sex hormones", estrogen is also produced in the adult testes of many mammals, including humans. To better understand the function of estrogens in the male, we used the rabbit model which is an important biomedical model. First, the expression of CYP19A1 transcripts was localized mainly in meiotic germ cells. Thus, testicular estrogen appears to be produced inside the seminiferous tubules. Next, the cells expressing ESR1 and ESR2 were identified, showing that estrogens could exert their function on post-meiotic germ cells in the tubules and play a role during sperm maturation, since ESR1 and ESR2 were detected in the cauda epididymis. Then, CRISPR/Cas9 CYP19A1-/- genetically modified rabbits were analyzed. CYP19A1-/- males showed decreased fertility with lower sperm count associated with hypo-spermatogenesis and lower spermatid number. Germ/sperm cell DNA methylation was unchanged, while sperm parameters were affected as CYP19A1-/- males exhibited reduced sperm motility associated with increased flagellar defects. In conclusion, testicular estrogens could be involved in the spermatocyte-spermatid transition in the testis, and in the acquisition of sperm motility in the epididymis.

Fetal Estrogens are not Involved in Sex Determination But Critical for Early Ovarian Differentiation in Rabbits.

AROMATASE is encoded by the CYP19A1 gene and is the cytochrome enzyme responsible for estrogen synthesis in vertebrates. In most mammals, a peak of CYP19A1 gene expression occurs in the fetal XX gonad when sexual differentiation is initiated. To elucidate the role of this peak, we produced 3 lines of TALEN genetically edited CYP19A1 knockout (KO) rabbits that were devoid of any estradiol production. All the KO XX rabbits developed as females with aberrantly small ovaries in adulthood, an almost empty reserve of primordial follicles, and very few large antrum follicles. Ovulation never occurred. Our histological, immunohistological, and transcriptomic analyses showed that the estradiol surge in the XX fetal rabbit gonad is not essential to its determination as an ovary, or for meiosis. However, it is mandatory for the high proliferation and differentiation of both somatic and germ cells, and consequently for establishment of the ovarian reserve.

Anti-ADAMTS13 autoantibodies in immune-mediated thrombotic thrombocytopenic purpura do not hamper ELISA-based quantification of ADAMTS13 antigen.

BACKGROUND: The biological diagnosis of immune-mediated thrombotic thrombocytopenic purpura (iTTP) is based on determination of ADAMTS13 activity (<10%) and anti-ADAMTS13 autoantibodies. ADAMTS13 antigen levels are not routinely measured in iTTP patients, but studies have shown that antigen levels are a valuable prognostic factor. OBJECTIVES: To (a) report the validation of our in-house developed ADAMTS13 antigen enzyme-linked immunosorbent assay (ELISA) and determine ADAMTS13 antigen in a large cohort of healthy donor and iTTP patient plasma samples; and (b) to investigate whether ADAMTS13 antigen determination is not disturbed by the presence of anti-ADAMTS13 autoantibodies. METHODS: Our in-house ADAMTS13 antigen ELISA was validated in terms of sensitivity, repeatability, and reproducibility. ADAMTS13 antigen levels were determined in plasma samples from 423 healthy donors and 112 acute iTTP patients. Purified IgGs from iTTP patients were added to normal human plasma to determine whether anti-ADAMTS13 autoantibodies hampered ADAMTS13 antigen determination. RESULTS: Our in-house ADAMTS13 antigen ELISA has a detection limit of 3% and low intra-assay (coefficient of variation, %CV < 10%) and inter-assay (%CV < 18%) variability. ADAMTS13 antigen levels were significantly reduced (P < .0001) in acute iTTP patients (15 ± 18%) compared to healthy donors (101 ± 18%). The anti-ADAMTS13 autoantibodies in plasma of iTTP patients did not impede ADAMTS13 antigen determinations using our in-house ELISA. CONCLUSIONS: Our in-house ADAMT13 antigen ELISA is a powerful tool to correctly determine ADAMTS13 antigen levels in iTTP patients, which supports routine ADAMTS13 antigen measurements in these patients to have better insight into disease prognosis.

Chronic perinatal odour exposure with heptaldehyde affects odour sensitivity and olfactory system homeostasis in preweaning mice.

Exposure to specific odorants in the womb during pregnancy or in the milk during early nursing is known to impact morpho-functional development of the olfactory circuitry of pups. This can be associated with a modification in olfactory sensitivity and behavioural olfactory-based preferences to the perinatally encountered odorants measured at birth, weaning or adult stage. Effects depend on a multitude of factors, such as odorant type, concentration, administration mode and frequency, as well as timing and mice strain. Here, we examined the effect of perinatal exposure to heptaldehyde on the neuro-anatomical development of the olfactory receptor Olfr2 circuitry, olfactory sensitivity and odour preferences of preweaning pups using mI7-IRES-tau-green fluorescent protein mice. We found that perinatal odour exposure through the feed of the dam reduces the response to heptaldehyde and modulates transcript levels of neuronal transduction proteins in the olfactory epithelium of the pups. Furthermore, the number of I7 glomeruli related to Olfr2-expressing OSN is altered in a way similar to that seen with restricted post-natal exposure, in an age-dependent way. These variations are associated with a modification of olfactory behaviours associated with early post-natal odour preferences at weaning.

Promotion of cancer cell invasiveness and metastasis emergence caused by olfactory receptor stimulation.

Olfactory receptors (ORs) are expressed in the olfactory epithelium, where they detect odorants, but also in other tissues with additional functions. Some ORs are even overexpressed in tumor cells. In this study, we identified ORs expressed in enterochromaffin tumor cells by RT-PCR, showing that single cells can co-express several ORs. Some of the receptors identified were already reported in other tumors, but they are orphan (without known ligand), as it is the case for most of the hundreds of human ORs. Thus, genes coding for human ORs with known ligands were transfected into these cells, expressing functional heterologous ORs. The in vitro stimulation of these cells by the corresponding OR odorant agonists promoted cell invasion of collagen gels. Using LNCaP prostate cancer cells, the stimulation of the PSGR (Prostate Specific G protein-coupled Receptor), an endogenously overexpressed OR, by ß-ionone, its odorant agonist, resulted in the same phenotypic change. We also showed the involvement of a PI3 kinase γ dependent signaling pathway in this promotion of tumor cell invasiveness triggered by OR stimulation. Finally, after subcutaneous inoculation of LNCaP cells into NSG immunodeficient mice, the in vivo stimulation of these cells by the PSGR agonist ß-ionone significantly enhanced metastasis emergence and spreading.