Characterization of intestinal mononuclear phagocyte subsets in young ruminants at homeostasis and during Cryptosporidium parvum infection.

Introduction: Cryptosporidiosis is a poorly controlled zoonosis caused by an intestinal parasite, Cryptosporidium parvum, with a high prevalence in livestock (cattle, sheep, and goats). Young animals are particularly susceptible to this infection due to the immaturity of their intestinal immune system. In a neonatal mouse model, we previously demonstrated the importance of the innate immunity and particularly of type 1 conventional dendritic cells (cDC1) among mononuclear phagocytes (MPs) in controlling the acute phase of C. parvum infection. These immune populations are well described in mice and humans, but their fine characterization in the intestine of young ruminants remained to be further explored. Methods: Immune cells of the small intestinal Peyer's patches and of the distal jejunum were isolated from naive lambs and calves at different ages. This was followed by their fine characterization by flow cytometry and transcriptomic analyses (q-RT-PCR and single cell RNAseq (lamb cells)). Newborn animals were infected with C. parvum, clinical signs and parasite burden were quantified, and isolated MP cells were characterized by flow cytometry in comparison with age matched control animals. Results: Here, we identified one population of macrophages and three subsets of cDC (cDC1, cDC2, and a minor cDC subset with migratory properties) in the intestine of lamb and calf by phenotypic and targeted gene expression analyses. Unsupervised single-cell transcriptomic analysis confirmed the identification of these four intestinal MP subpopulations in lamb, while highlighting a deeper diversity of cell subsets among monocytic and dendritic cells. We demonstrated a weak proportion of cDC1 in the intestine of highly susceptible newborn lambs together with an increase of these cells within the first days of life and in response to the infection. Discussion: Considering cDC1 importance for efficient parasite control in the mouse model, one may speculate that the cDC1/cDC2 ratio plays also a key role for the efficient control of C. parvum in young ruminants. In this study, we established the first fine characterization of intestinal MP subsets in young lambs and calves providing new insights for comparative immunology of the intestinal MP system across species and for future investigations on host-Cryptosporidium interactions in target species.

The adiponectin agonist, AdipoRon, inhibits steroidogenesis and cell proliferation in human luteinized granulosa cells.

During obesity, excess body weight is not only associated with an increased risk of type 2-diabetes, but also several other pathological processes, such as infertility. Adipose tissue is the largest endocrine organ of the body that produces adipokines, including adiponectin. Adiponectin has been reported to control fertility through the hypothalamic-pituitary-gonadal axis, and folliculogenesis in the ovaries. In this study, we focused on a recent adiponectin-like synthetic agonist called AdipoRon, and its action in human luteinized granulosa cells. We demonstrated that AdipoRon activated the adenosine monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor alpha (PPAR) signalling pathways in human luteinized granulosa cells. A 25 µM AdipoRon stimulation reduced granulosa cell proliferation by inducing cell cycle arrest in G1, associated with PTEN and p53 pathway activation. In addition, AdipoRon perturbed cell metabolism by decreasing mitochondrial activity and ATP production. In human luteinized granulosa cells, AdipoRon increased phosphodiesterase activity, leading to a drop in cyclic adenosine monophosphate (cAMP) production, aromatase expression and oestrogens secretion. In conclusion, AdipoRon impacted folliculogenesis by altering human luteinized granulosa cell function, via steroid production and cell proliferation. This agonist may have applications for improving ovarian function in metabolic disorders or granulosa cancers.

Acriflavine targets oncogenic STAT5 signaling in myeloid leukemia cells.

Acriflavine (ACF) is an antiseptic with anticancer properties, blocking the growth of solid and haematopoietic tumour cells. Moreover, this compound has been also shown to overcome the resistance of cancer cells to chemotherapeutic agents. ACF has been shown to target hypoxia-inducible factors (HIFs) activity, which are key effectors of hypoxia-mediated chemoresistance. In this study, we showed that ACF inhibits the growth and survival of chronic myeloid leukaemia (CML) and acute myeloid leukaemia (AML) cell lines in normoxic conditions. We further demonstrated that ACF down-regulates STAT5 expression in CML and AML cells but activates STAT3 in CML cells in a HIF-independent manner. In addition, we demonstrated that ACF suppresses the resistance of CML cells to tyrosine kinase inhibitors, such as imatinib. Our data suggest that the dual effect of ACF might be exploited to eradicate de novo or acquired resistance of myeloid leukaemia cells to chemotherapy.

Sexually dimorphic gene expression and neurite sensitivity to estradiol in fetal arcuate Kiss1 cells.

Kiss1 neurons of the arcuate (ARC) nucleus form an interconnected network of cells that communicate via neurokinin B (encoded by Tac2) and its receptor (encoded by Tacr3) and play key roles in the control of the reproductive axis through sex hormone-regulated synthesis and release of kisspeptin peptides (Kp, encoded by Kiss1). The aim of this study was to determine whether the Kiss1 cell population of the ARC already displays sexually dimorphic features at embryonic age E16.5 in mice. At this time of development, Kiss1-GFP- and Kp-immunoreactive cell bodies were restricted to the ARC and not found in the pre-optic area (POA). The Kiss1-GFP cell population was identical in size between sexes but had significantly lower Kiss1, Tac2, and Tacr3 mRNA levels and lower Kp-ir fiber density in the POA in male compared to female fetuses. Receptors for androgen (Ar) and estrogen (Esr1, Esr2, Gpr30) and the Cyp19a1 gene (encoding the estradiol-producing enzyme aromatase) transcripts were also detected in fetal ARC Kiss1-GFP cells with significant sex differences for Ar (higher in males) and Esr1 (higher in females). Functional studies on primary cultures of sorted fetal Kiss1-GFP cells revealed a significant negative effect of estradiol treatment on neurite outgrowth on the fourth day of culture in the female group specifically. We conclude that the ARC Kiss1 cell population is already sexually differentiated at E16.5 and that its morphogenetic development may be particularly vulnerable to estradiol exposure at this early developmental time.

Batf3-Dependent Intestinal Dendritic Cells Play a Critical Role in the Control of Cryptosporidium parvum Infection.

Understanding the protective immune response to Cryptosporidium parvum infection is of critical importance to reduce the widespread impact caused by this disease in young individuals. Here, we analyzed the various subsets of CD103+ and CD103- intestinal dendritic cells (DCs) of wild-type and Batf3-/- neonatal mice at homoeostasis and investigated their role during infection. Neonatal Batf3-/- mice had a low CD103+/CD103- DC ratio, resulting in higher susceptibility to the acute phase of the infection and they could not cure the infection. Early during infection, CD103- DCs of Batf3-/- neonates had a lower ability to produce interleukin-12 than their wild-type littermates and lower levels of interferon-gamma mRNA were detected in the infected mucosa. Amplification of CD103+ DCs in Batf3-/- neonates prior to infectious challenge reduced their susceptibility to infection. CD103+ DCs thus outperform CD103- DCs in controlling C. parvum infections and represent a primary target of host-directed immunotherapies dedicated to neonates.