ore than 1.9 billion adults are overweight or obese, representing over one third of the worldwide adult population 1. The biggest health and economic burden of obesity is the large number of obesity-related co-morbidities. In addition to type 2 diabetes and cardiovascular disease, obesity is associated with an increased risk of cancer and infections 2-4. Indeed, up to 49% of certain types of cancer are now attributed to obesity 3 , and weight loss through bariatric surgery can reverse cancer risk 5. Potential mechanisms for the increased risk of cancer associated with obesity include overproduction of hormones (for example, oestrogens), adipokines (for example, leptin), and insulin, which favor cell proliferation and tumor growth 6,7. Peroxisome proliferator-activated receptors (PPARs) are transcriptional regulators of cellular metabolism. It has recently been shown that obesity induces a PPAR-driven lipid metabolism program in metastatic tumor cells, which enhances metastasis and tumor cell survival 8. In intestinal stem cells, obesitydriven PPAR signaling enhances stemness and tumor progression 9. However, despite the increasing attention to the role of the immune system and inflammation in obesity-driven insulin resistance, the impact of obesity-induced dysfunction on immunosurveillance and cancer risk is not well understood. Natural killer (NK) cells have crucial roles in protective immunity against tumors and viral infections 10. NK cells kill their targets through the directed secretion of lytic granules, which contain pore-forming perforin and apoptosis-inducing granzymes 11-13. Cellular metabolism has a critical role in the function of immune cells. NK cells switch the balance of the core metabolic program from oxidative phosphorylation (OXPHOS) to glycolysis to meet the increased energy required to kill tumor cells 14,15 , although the steps in the killing process that require this metabolic activation are unknown. Humans and mice with obesity display numerical and functional defects in NK cells and have an increased risk of cancer and infections. As obesity is a state of altered metabolism, we investigated the effect of obesity on the cellular metabolism, gene expression, and function of NK cells, and its contribution to cancer development. Our data show that NK cell uptake of lipids from the environment in human obesity interfered with their cellular bioenergetics, inducing 'metabolic paralysis'. Lipid-induced metabolic defects caused NK cell incompetence by inhibiting trafficking of the cytotoxic machinery, leading to loss of antitumor functions in vitro and in vivo. Our data suggest that obesity targets immunometabolic pathways and that this may be partly responsible for the increased cancer and infection risks in obesity, and suggest that metabolic reprogramming may improve innate immunosurveillance in obesity. Results Obesity induces lipid metabolism in NK cells. To better understand the effects of obesity on NK cells, we examined mouse models of diet-induced obesity. We performed transcriptional a...

Obesity underpins the development of numerous chronic diseases, such as type II diabetes mellitus. It is well established that obesity negatively alters immune cell frequencies and functions. Mucosal-associated invariant T (MAIT) cells are a population of innate T cells, which we have previously reported are dysregulated in obesity, with altered circulating and adipose tissue frequencies and a reduction in their IFN-g production, which is a critical effector function of MAIT cells in host defense. Hence, there is increased urgency to characterize the key molecular mechanisms that drive MAIT cell effector functions and to identify those which are impaired in the obesity setting. In this study, we found that MAIT cells significantly upregulate their rates of glycolysis upon activation in an mTORC1-dependent manner, and this is essential for MAIT cell IFN-g production. Furthermore, we show that mTORC1 activation is dependent on amino acid transport via SLC7A5. In obese patients, using RNA sequencing, Seahorse analysis, and a series of in vitro experiments, we demonstrate that MAIT cells isolated from obese adults display defective glycolytic metabolism, mTORC1 signaling, and SLC7A5 aa transport. Collectively, our data detail the intrinsic metabolic pathways controlling MAIT cell cytokine production and highlight mTORC1 as an important metabolic regulator that is impaired in obesity, leading to altered MAIT cell responses.

After calving, the bovine endometrium undergoes marked morphological and functional changes that are necessary for subsequent re-breeding. Regulation and integration of these key events are largely uncharacterised. Here, endometrial swabs and biopsies were taken at 15, 30 and 60 days postpartum (DPP) from 13 healthy primiparous cows, 10 of which subsequently conceived, with a view to characterising innate and inflammatory gene expression profiles. Endometrial biopsies exhibited severe inflammation (>75 leukocytes per high-power field) at 15 DPP, which had begun to resolve by 30 DPP and had completely resolved by 60 DPP. The severe inflammation at 15 DPP coincided with uterine infection in all cows and a significant increase (P < 0.05) in the expression of all of 16 genes investigated, including CD45, IL8, IL6, IL1, TNF, TAP, SAA3 and HP at 15 DPP, relative to 60 DPP. All of these parameters had begun to return to normal physiological levels at 30 DPP. Systemically, serum protein concentrations of IL-8 were elevated at 15 DPP compared with 60 DPP (78 pg mL–1 vs 48 pg mL–1; P = 0.02). These results indicate that endometrial inflammation, leukocyte infiltration and increased expression of pro-inflammatory, antimicrobial and acute-phase protein genes are expected features of the postpartum period, critical to bacterial clearance and uterine involution.

BackgroundThe regulation of endometrial inflammation has important consequences for the resumption of bovine fertility postpartum. All cows experience bacterial influx into the uterus after calving; however a significant proportion fail to clear infection leading to the development of cytological endometritis (CE) and compromised fertility. We hypothesised that early immunological changes could not only act as potential prognostic biomarkers for the subsequent development of disease but also shed light on the pathogenesis of endometritis in the postpartum dairy cow.MethodsEndometrial biopsy RNA was extracted from 15 cows at 7 and 21 days postpartum (DPP), using the Qiagen RNeasy® Plus Mini kit and quality determined using an Agilent 2100 bioanalyser. Disease status was determined by histpathology based on inflammatory cell infiltrate. RNA-seq of both mRNA and miRNA libraries were performed on an Illumina® HiSeq™ 2000. Paired reads were aligned to the bovine genome with Bowtie2 and differentially expressed genes were identified using EdgeR. Significantly over-represented Gene Ontology terms were identified using GO-seq, and pathway analysis was performed using KEGG. Quanititative real-time PCR was also performed for validation (ABI 7500 fast). Haematology was assessed using an automated ADVIA 2120 analyser. Serum proteins were evaluated by ELISA and metabolite analysis was performed using a Beckman Coulter AU 400 clinical analyser. Terminal-restriction fragment length polymorphism (T-RFLP) was used to obtain fingerprints of the microbial communities present.ResultsNext-generation sequencing from endometrial biopsies taken at 7 DPP identified significant induction of inflammatory gene expression in all cows. Despite the common inflammatory profile and enrichment of the Toll-like receptor and NFκB pathways, 73 genes and 31 miRNAs were significantly differentially expressed between healthy cows (HC, n = 9) and cows which subsequently developed CE at 7 DPP (n = 6, FDR < 0.1). While significant differential expression of 4197 genes in the transcriptome of healthy cows between 7 and 21 DPP showed the transition from a proinflammatory to tissue profliferation and repair, only 31 genes were differentially expressed in cows with CE (FDR < 0.1), indicating the arrest of such a transition. A link betwene the dysregulated inflammatory response and the composition of the uterine microbial communities was suggested by the presence of significant differences in uterine bacterial tRFLP profiles between HC and CE groups. Furthermore, inflammatory activity was not confined to the uterus; decreased circulating granulocytes and increased Acute Phase Protein (SAA and HP) expression levels were detected in plasma at 7 DPP in cows that developed CE.ConclusionOur data suggests that the IL1 and IL17 inflammatory cascade activated early postpartum is resolved thereby restoring homeostasis in healthy cows by 21 DPP, but this transition fails to occur in cows which develop CE. Despite a common early inflammatory profile, elevated and differe...