Sex-specific impact of psychosocial stress on hematopoiesis and blood leukocytes.

Stress exposure has been shown to modulate innate and adaptive immune responses. Indeed, stress favors myelopoiesis and monocyte generation and contributes to cardiovascular disease development. As sex hormones regulate innate and adaptive immune responses, we decided to investigate whether stress exposure leads to a different immune response in female and male mice. Our data demonstrated that psychosocial stressinduced neutrophilia in male, but not female mice. Importantly, we identified that B-cell numbers were reduced in female, but not male mice upon exposure to stress. Thus, our study revealed that the stress-induced immune alterations are sex-dependent, and this is an important feature to consider for future investigations.

Low Doses of PFOA Promote Prostate and Breast Cancer Cells Growth through Different Pathways.

Endocrine Disrupting Compounds (EDCs) are found in everyday products. Widely distributed throughout the environment, persistent organic pollutants (POPs) are a specific class of EDCs that can accumulate in adipose tissue. Many of them induce adverse effects on human health-such as obesity, fertility disorders and cancers-by perturbing hormone effects. We previously identified many compounds with EDC activity in the circulation of obese patients who underwent bariatric surgery. Herein, we analyzed the effects of four of them (aldrin, BDE28, PFOA and PCB153) on two cancer cell lines of hormone-sensitive organs (prostate and breast). Each cell line was exposed to serial dilutions of EDCs from 10-6 M to 10-12 M; cytotoxicity and proliferation were monitored using the IncuCyte® technology. We showed that none of these EDCs induce cytotoxicity and that PFOA and PCB153, only at very low doses (10-12 M), increase the proliferation of DU145 (prostate cancer) and MCF7 (breast cancer) cells, while the same effects are observed with high concentrations (10-6 M) for aldrin or BDE28. Regarding the mechanistic aspects, PFOA uses two different signaling pathways between the two lines (the Akt/mTORC1 and PlexinD1 in MCF7 and DU145, respectively). Thus, our study demonstrates that even at picomolar (10-12 M) concentrations PFOA and PCB153 increase the proliferation of prostate and breast cancer cell lines and can be considered possible carcinogens.

Investigation of a fluorescent reporter microenvironment niche labeling strategy in experimental brain metastasis.

Brain metastases are the most common brain tumors in patients and are associated with poor prognosis. Investigating the colonization and outgrowth of brain metastases is challenging given the complexity of the organ, tissue sampling difficulty, and limited experimental models. To address this challenge, we employed a strategy to analyze the metastatic niche in established lesions, based on the release of a cell-penetrating mCherry tag from labeled tumor cells to neighboring niche cells, using different brain metastasis mouse models. We found that CD206+ macrophages were the most abundant cells taking up the mCherry label in established metastases. In vitro and in vivo experiments demonstrated that macrophages uptake and retain the canonical form of mCherry, even without the cell-penetrating portion of the tag. These results identify a specific macrophage subset in the brain that retains tumor-supplied fluorescent molecules, thereby complicating the long-term use of niche labeling strategies in established experimental brain metastasis.

Adrenal gland macrophages regulate glucocorticoid production through Trem2 and TGF-ß.

Glucocorticoid synthesis by adrenal glands (AGs) is regulated by the hypothalamic-pituitary-adrenal axis to facilitate stress responses when the host is exposed to stimuli. Recent studies implicate macrophages as potential steroidogenic regulators, but the molecular mechanisms by which AG macrophages exert such influence remain unclear. In this study, we investigated the role of AG macrophages in response to cold challenge or atherosclerotic inflammation as physiologic models of acute or chronic stress. Using single-cell RNA sequencing, we observed dynamic AG macrophage polarization toward classical activation and lipid-associated phenotypes following acute or chronic stimulation. Among transcriptional alterations induced in macrophages, triggering receptor expressed on myeloid cells 2 (Trem2) was highlighted because of its upregulation following stress. Conditional deletion of macrophage Trem2 revealed a protective role in stress responses. Mechanistically, Trem2 deletion led to increased AG macrophage death, abolished the TGF-ß-producing capacity of AG macrophages, and resulted in enhanced glucocorticoid production. In addition, enhanced glucocorticoid production was replicated by blockade of TGF-ß signaling. Together, these observations suggest that AG macrophages restrict steroidogenesis through Trem2 and TGF-ß, which opens potential avenues for immunotherapeutic interventions to resolve stress-related disorders.

Unravelling the sex-specific diversity and functions of adrenal gland macrophages.

Despite the ubiquitous function of macrophages across the body, the diversity, origin, and function of adrenal gland macrophages remain largely unknown. We define the heterogeneity of adrenal gland immune cells using single-cell RNA sequencing and use genetic models to explore the developmental mechanisms yielding macrophage diversity. We define populations of monocyte-derived and embryonically seeded adrenal gland macrophages and identify a female-specific subset with low major histocompatibility complex (MHC) class II expression. In adulthood, monocyte recruitment dominates adrenal gland macrophage maintenance in female mice. Adrenal gland macrophage sub-tissular distribution follows a sex-dimorphic pattern, with MHC class IIlow macrophages located at the cortico-medullary junction. Macrophage sex dimorphism depends on the presence of the cortical X-zone. Adrenal gland macrophage depletion results in altered tissue homeostasis, modulated lipid metabolism, and decreased local aldosterone production during stress exposure. Overall, these data reveal the heterogeneity of adrenal gland macrophages and point toward sex-restricted distribution and functions of these cells.

Macrophage metabolic regulation in atherosclerotic plaque.

Metabolism plays a key role in controlling immune cell functions. In this review, we will discuss the diversity of plaque resident myeloid cells and will focus on their metabolic demands that could reflect on their particular intraplaque localization. Defining the metabolic configuration of plaque resident myeloid cells according to their topologic distribution could provide answers to key questions regarding their functions and contribution to disease development.

UBTD1 regulates ceramide balance and endolysosomal positioning to coordinate EGFR signaling.

To adapt in an ever-changing environment, cells must integrate physical and chemical signals and translate them into biological meaningful information through complex signaling pathways. By combining lipidomic and proteomic approaches with functional analysis, we have shown that ubiquitin domain-containing protein 1 (UBTD1) plays a crucial role in both the epidermal growth factor receptor (EGFR) self-phosphorylation and its lysosomal degradation. On the one hand, by modulating the cellular level of ceramides through N-acylsphingosine amidohydrolase 1 (ASAH1) ubiquitination, UBTD1 controls the ligand-independent phosphorylation of EGFR. On the other hand, UBTD1, via the ubiquitination of Sequestosome 1 (SQSTM1/p62) by RNF26 and endolysosome positioning, participates in the lysosomal degradation of EGFR. The coordination of these two ubiquitin-dependent processes contributes to the control of the duration of the EGFR signal. Moreover, we showed that UBTD1 depletion exacerbates EGFR signaling and induces cell proliferation emphasizing a hitherto unknown function of UBTD1 in EGFR-driven human cell proliferation.

Brown adipose tissue monocytes support tissue expansion.

Monocytes are part of the mononuclear phagocytic system. Monocytes play a central role during inflammatory conditions and a better understanding of their dynamics might open therapeutic opportunities. In the present study, we focused on the characterization and impact of monocytes on brown adipose tissue (BAT) functions during tissue remodeling. Single-cell RNA sequencing analysis of BAT immune cells uncovered a large diversity in monocyte and macrophage populations. Fate-mapping experiments demonstrated that the BAT macrophage pool requires constant replenishment from monocytes. Using a genetic model of BAT expansion, we found that brown fat monocyte numbers were selectively increased in this scenario. This observation was confirmed using a CCR2-binding radiotracer and positron emission tomography. Importantly, in line with their tissue recruitment, blood monocyte counts were decreased while bone marrow hematopoiesis was not affected. Monocyte depletion prevented brown adipose tissue expansion and altered its architecture. Podoplanin engagement is strictly required for BAT expansion. Together, these data redefine the diversity of immune cells in the BAT and emphasize the role of monocyte recruitment for tissue remodeling.

The Adult Adrenal Cortex Undergoes Rapid Tissue Renewal in a Sex-Specific Manner.

Evolution has resulted in profound differences between males and females that extend to non-reproductive organs and are reflected in the susceptibility and progression of diseases. However, the cellular and molecular basis for these differences remains largely unknown. Here we report that adrenal gland tissue renewal is highly active and sexually dimorphic, with female mice showing a 3-fold higher turnover than males. Moreover, in males, homeostasis relies on proliferation of cells within the steroidogenic zone, but females employ an additional stem and/or progenitor compartment situated in the adrenal capsule. Using lineage tracing, sex reversal models, gonadectomy, and dihydrotestosterone treatments, we further show that sex-specific stem cell activity is driven by male hormones that repress recruitment of Gli1+ stem cells from the capsule and cell proliferation. Taken together, our findings provide a molecular and cellular basis for adrenal sex dimorphism that may contribute to the increased incidence of adrenal diseases in females.