Mammary duct luminal epithelium controls adipocyte thermogenic programme.

Sympathetic activation during cold exposure increases adipocyte thermogenesis via the expression of mitochondrial protein uncoupling protein 1 (UCP1)1. The propensity of adipocytes to express UCP1 is under a critical influence of the adipose microenvironment and varies between sexes and among various fat depots2-7. Here we report that mammary gland ductal epithelial cells in the adipose niche regulate cold-induced adipocyte UCP1 expression in female mouse subcutaneous white adipose tissue (scWAT). Single-cell RNA sequencing shows that glandular luminal epithelium subtypes express transcripts that encode secretory factors controlling adipocyte UCP1 expression under cold conditions. We term these luminal epithelium secretory factors 'mammokines'. Using 3D visualization of whole-tissue immunofluorescence, we reveal sympathetic nerve-ductal contact points. We show that mammary ducts activated by sympathetic nerves limit adipocyte UCP1 expression via the mammokine lipocalin 2. In vivo and ex vivo ablation of mammary duct epithelium enhance the cold-induced adipocyte thermogenic gene programme in scWAT. Since the mammary duct network extends throughout most of the scWAT in female mice, females show markedly less scWAT UCP1 expression, fat oxidation, energy expenditure and subcutaneous fat mass loss compared with male mice, implicating sex-specific roles of mammokines in adipose thermogenesis. These results reveal a role of sympathetic nerve-activated glandular epithelium in adipocyte UCP1 expression and suggest that mammary duct luminal epithelium has an important role in controlling glandular adiposity.

Interferon Lambda Signaling Restrains Experimental Autoimmune Encephalomyelitis.

IFN-λ is a type III interferon (IFN) with pleiotropic functions in modulating immune responses. To address its function in autoimmune neuroinflammation, we evaluated the development and progression of experimental autoimmune encephalitis (EAE) in IFNLR1KO (Ifnlr1-/-) and C57Bl/6 (WT) mice following immunization with MOG35-55 peptide. The results show that Ifnlr1-/-mice developed significantly more severe EAE than WT littermates with a similar day of onset, suggesting the potential of IFN-λ in reducing disease severity. We next interrogated whether IFN-λ differentially modulates EAE induced by encephalitogenic Th1 cells or Th17 cells. Encephalitogenic Th1 or Th17 generated from WT donors were transferred into WT or Ifnlr1-/-recipient mice. Whereas encephalitogenic Th1 cells induced more severe EAE in Ifnlr1-/- than WT recipients, the disease severity induced by encephalitogenic Th17 cells was similar. Additionally, in vitro experiments showed that Ifnlr1-/-macrophages promoted the expansion of myelin peptide-reactive Th17 cells but not Th1 cells. Early in the disease, the spinal cords of EAE mice displayed a significantly greater proportion of Ly6C-Ly6G+ cells with CXCR2+CD62Llo phenotype, indicating activated neutrophils. These findings suggest that IFN-λ signaling restrains activation and migration of neutrophils to the CNS, potentially attenuating neutrophil-mediated disease progression in autoimmune neuroinflammation. Recombinant IFN-λ can be used as a potential therapeutic target for treatment of patients with multiple sclerosis as it has fewer side effects due to the restricted expression of its receptor.

Sexually dimorphic role of diet and stress on behavior, energy metabolism, and the ventromedial hypothalamus.

Scientific evidence underscores the influence of biological sex on the interplay between stress and metabolic dysfunctions. However, there is limited understanding of how diet and stress jointly contribute to metabolic dysregulation in both males and females. To address this gap, our study aimed to investigate the combined effects of a high-fat diet (HFD) and repeated footshock stress on fear-related behaviors and metabolic outcomes in male and female mice. Using a robust rodent model that recapitulates key aspects of post-traumatic stress disorder (PTSD), we subjected mice to footshock stressor followed by weekly reminder footshock stressor or no stressor for 14 weeks while on either an HFD or chow diet. Our findings revealed that HFD impaired fear memory extinction in male mice that received initial stressor but not in female mice. Blood glucose levels were influenced by both diet and sex, with HFD-fed female mice displaying elevated levels that returned to baseline in the absence of stress, a pattern not observed in male mice. Male mice on HFD exhibited higher energy expenditure, while HFD-fed female mice showed a decreased respiratory exchange ratio (RER). Sex-specific alterations in pro-inflammatory markers and abundance of hematopoietic stem cells were observed in chronically stressed mice on an HFD in different peripheral tissues, indicating the manifestation of distinct comorbid disorders. Single-nuclei RNA sequencing of the ventromedial hypothalamus from stressed mice on an HFD provided insights into sex-specific glial cell activation and cell-type-specific transcriptomic changes. In conclusion, our study offers a comprehensive understanding of the intricate interactions between stress, diet, sex, and various physiological and behavioral outcomes, shedding light on a potential brain region coordinating these interactions.

Transforming growth factor receptor III (Betaglycan) regulates the generation of pathogenic Th17 cells in EAE.

The transforming growth factor receptor III (TßRIII) is commonly recognized as a co-receptor that promotes the binding of TGFß family ligands to type I and type II receptors. Within the immune system, TßRIII regulates T cell development in the thymus and is differentially expressed through activation; however, its function in mature T cells is unclear. To begin addressing this question, we developed a conditional knock-out mouse with restricted TßRIII deletion in mature T cells, necessary because genomic deletion of TßRIII results in perinatal mortality. We determined that TßRIII null mice developed more severe autoimmune central nervous neuroinflammatory disease after immunization with myelin oligodendrocyte peptide (MOG35-55) than wild-type littermates. The increase in disease severity in TßRIII null mice was associated with expanded numbers of CNS infiltrating IFNγ+ CD4+ T cells and cells that co-express both IFNγ and IL-17 (IFNγ+/IL-17+), but not IL-17 alone expressing CD4 T cells compared to Tgfbr3fl/fl wild-type controls. This led us to speculate that TßRIII may be involved in regulating conversion of encephalitogenic Th17 to Th1. To directly address this, we generated encephalitogenic Th17 and Th1 cells from wild type and TßRIII null mice for passive transfer of EAE into naïve mice. Remarkably, Th17 encephalitogenic T cells from TßRIII null induced EAE of much greater severity and earlier in onset than those from wild-type mice. The severity of EAE induced by encephalitogenic wild-type and Tgfbr3fl/fl.dLcKCre Th1 cells were similar. Moreover, in vitro restimulation of in vivo primed Tgfbr3fl/fl.dLcKCre T cells, under Th17 but not Th1 polarizing conditions, resulted in a significant increase of IFNγ+ T cells. Altogether, our data indicate that TßRIII is a coreceptor that functions as a key checkpoint in controlling the pathogenicity of autoreactive T cells in neuroinflammation probably through regulating plasticity of Th17 T cells into pathogenic Th1 cells. Importantly, this is the first demonstration that TßRIII has an intrinsic role in T cells.

Sexually dimorphic role of the locus coeruleus PAC1 receptors in regulating acute stress-associated energy metabolism.

Severe stress leads to alterations in energy metabolism with sexually dimorphic onset or severity. The locus coeruleus (LC) in the brainstem that mediates fight-or-flight-or-freeze response to stress is sexually dimorphic in morphology, plays a key role in interactions between diet and severe stressors, and has neuronal input to the brown adipose tissue (BAT)-a thermogenic organ important for energy balance. Yet, little is known on how LC coordinates stress-related metabolic adaptations. LC expresses receptors for the neuropeptide PACAP (pituitary adenylate cyclase activating peptide) and PACAP signaling through PAC1 (PACAP receptor) are critical regulators of various types of stressors and energy metabolism. We hypothesized that LC-PAC1 axis is a sex-specific central "gatekeeper" of severe acute stress-driven behavior and energy metabolism. Selective ablation of PAC1 receptors from the LC did not alter stress response in mice of either sex, but enhanced food intake in females and was associated with increased energy expenditure and BAT thermogenesis in male mice. These results show a sexually dimorphic role of the LC-PAC1 in regulating acute stress-related energy metabolism. Thus, by disrupting LC-PAC1 signaling, our studies show a unique and previously unexplored role of LC in adaptive energy metabolism in a sex-dependent manner.