SUMMARY Despite a wealth of clinical data showing an association between inflammation and degenerative disorders in elderly, the immune sensors that causally link systemic inflammation to aging remain unclear. Here we detail a mechanism that the Nlrp3 inflammasome controls systemic low grade age-related ‘sterile’ inflammation in both periphery and brain independently of the non-canonical caspase-11 inflammasome. Ablation of Nlrp3 inflammasome protected mice from age-related increases in the innate immune activation, alterations in CNS transcriptome and astrogliosis. Consistent with the hypothesis that systemic low grade inflammation promotes age-related degenerative changes, the deficient Nlrp3 inflammasome mediated caspase-1 activity improved glycemic control and attenuated bone loss and thymic demise. Notably, IL-1 mediated only Nlrp3 inflammasome dependent improvement in cognitive function and motor performance in aged mice. These studies reveal Nlrp3 inflammasome as an upstream target that controls age-related inflammation and offer innovative therapeutic strategy to lower Nlrp3 activity to delay multiple age-related chronic diseases.

Brown adipose tissue (BAT) thermogenesis is critical to maintain homoeothermia and is centrally controlled via sympathetic outputs. Body temperature and BAT activity also impact energy expenditure, and obesity is commonly associated with decreased BAT capacity and sympathetic tone. Severely obese mice that lack leptin or its receptor (LepRb) show decreased BAT capacity, sympathetic tone, and body temperature and thus are unable to adapt to acute cold exposure (

Dietary methionine restriction (MR) produces an integrated series of biochemical and physiological responses that improve biomarkers of metabolic health, limit fat accretion, and enhance insulin sensitivity. Using transcriptional profiling to guide tissue-specific evaluations of molecular responses to MR, we report that liver and adipose tissue are the primary targets of a transcriptional program that remodeled lipid metabolism in each tissue. The MR diet produced a coordinated downregulation of lipogenic genes in the liver, resulting in a corresponding reduction in the capacity of the liver to synthesize and export lipid. In contrast, the transcriptional response in white adipose tissue (WAT) involved a depot-specific induction of lipogenic and oxidative genes and a commensurate increase in capacity to synthesize and oxidize fatty acids. These responses were accompanied by a significant change in adipocyte morphology, with the MR diet reducing cell size and increasing mitochondrial density across all depots. The coordinated transcriptional remodeling of lipid metabolism between liver and WAT by dietary MR produced an overall reduction in circulating and tissue lipids and provides a potential mechanism for the increase in metabolic flexibility and enhanced insulin sensitivity produced by the diet.

ObjectiveLeptin responsive neurons play an important role in energy homeostasis, controlling specific autonomic, behavioral, and neuroendocrine functions. We have previously identified a population of leptin receptor (LepRb) expressing neurons within the dorsomedial hypothalamus/dorsal hypothalamic area (DMH/DHA) which are related to neuronal circuits that control brown adipose tissue (BAT) thermogenesis. Intra-DMH leptin injections also activate sympathetic outflow to BAT, but whether such effects are mediated directly via DMH/DHA LepRb neurons and whether this is physiologically relevant for whole body energy expenditure and body weight regulation has yet to be determined.MethodsWe used pharmacosynthetic receptors (DREADDs) to selectively activate DMH/DHA LepRb neurons. We further deleted LepRb with virally driven cre-recombinase from DMH/DHA neurons and determined the physiological importance of DMH/DHA LepRb neurons in whole body energy homeostasis.ResultsNeuronal activation of DMH/DHA LepRb neurons with DREADDs promoted BAT thermogenesis and locomotor activity, which robustly induced energy expenditure (p < 0.001) and decreases body weight (p < 0.001). Similarly, intra-DMH/DHA leptin injections normalized hypothermia and attenuated body weight gain in leptin-deficient ob/ob mice. Conversely, ablation of LepRb from DMH/DHA neurons remarkably drives weight gain (p < 0.001) by reducing energy expenditure (p < 0.001) and locomotor activity (p < 0.001). The observed changes in body weight were largely independent of food intake.ConclusionTaken together, our data highlight that DMH/DHA LepRb neurons are sufficient and necessary to regulate energy expenditure and body weight.

In mammals, males consume more food, which is considered a masculinized behavior, but the underlying mechanism of this sex-specific feeding behavior is unknown. In mice, neonatal testosterone (NT) is critical to masculinize the developing brain, leading to sex differences in reproductive physiology. The proopiomelanocortin (POMC) neurons of the hypothalamic arcuate nucleus (ARC) are critical to suppress energy intake and POMC innervation of hypothalamic feeding circuits develops to a large extent neonatally. We hypothesized that NT programs the masculinization of energy intake by programming POMC neurons. We tested this hypothesis by comparing control females and control males (CMs) with female mice neonatally androgenized with testosterone (NTFs). We show that increased food intake in CMs is associated with reduced POMC expression and decreased intensity of neuronal projections from POMC neurons within the ARC compared with control females. We found that NTFs display a masculinized energy intake and ARC POMC expression and innervation as observed in CMs, which can be mimicked by neonatal exposure to the androgen receptor agonist dihydrotestosterone (DHT). NTFs also exhibit hyperleptinemia and a decreased ability of leptin to up-regulate POMC, suppress food intake, and prevent adipose tissue accumulation, independent of signal transducer and activator of transcription 3. However, this leptin resistance is specific to NTFs, is not a consequence of masculinization, and is reproduced by neonatal exposure to estrogen but not DHT. Thus, NT programs a sexual differentiation of POMC neurons in female mice via DHT but also predisposes to leptin resistance and obesity in an estrogen-dependent manner.