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How adult tissue stem and niche cells respond to the nutritional state of an organism is not well understood. Here we find that Paneth cells, a key constituent of the mammalian intestinal stem-cell (ISC) niche, augment stem-cell function in response to calorie restriction. Calorie restriction acts by reducing mechanistic target of rapamycin complex 1 (mTORC1) signalling in Paneth cells, and the ISC-enhancing effects of calorie restriction can be mimicked by rapamycin. Calorie intake regulates mTORC1 in Paneth cells, but not ISCs, and forced activation of mTORC1 in Paneth cells during calorie restriction abolishes the ISC-augmenting effects of the niche. Finally, increased expression of bone stromal antigen 1 ( Bst1 ) in Paneth cells—an ectoenzyme that produces the paracrine factor cyclic ADP ribose—mediates the effects of calorie restriction and rapamycin on ISC function. Our findings establish that mTORC1 non-cell-autonomously regulates stem-cell self-renewal, and highlight a significant role of the mammalian intestinal niche in coupling stem-cell function to organismal physiology. In the mouse intestine, calorie restriction enhances the regenerative capacity of intestinal stem cells by reducing mTORC1 signalling in their Paneth cell niche. Calorie restriction and the gut Reducing caloric intake while maintaining adequate nutrition extends lifespan in diverse organisms, possibly by preserving stem- and progenitor-cell function. David Sabatini and colleagues show that in the mouse intestine, caloric restriction leads to an increased number of intestinal stem cells (ISC) with enhanced regenerative capacity. The effects are mediated by modulation of mTOR signalling in Paneth cells, important components of the ISC niche. Caloric restriction leads to the expression of the Bst1 gene in Paneth cells and subsequent secretion of cyclic ADP ribose, which acts on ISCs in a paracrine manner. These findings demonstrate a link between the stem-cell function and the nutritional status of an organism, and raise the possibility that mTORC1 inhibitors or Bst1 mimetics may have therapeutic application in improving intestinal regeneration and function.

Background Understanding the mechanism of the sexual dimorphism in susceptibility to obesity and metabolic syndrome (MS) is important for the development of effective interventions for MS. Results Here we show that gut microbiome mediates the preventive effect of estrogen (17β-estradiol) on metabolic endotoxemia (ME) and low-grade chronic inflammation (LGCI), the underlying causes of MS and chronic diseases. The characteristic profiles of gut microbiome observed in female and 17β-estradiol-treated male and ovariectomized mice, such as decreased Proteobacteria and lipopolysaccharide biosynthesis, were associated with a lower susceptibility to ME, LGCI, and MS in these animals. Interestingly, fecal microbiota-transplant from male mice transferred the MS phenotype to female mice, while antibiotic treatment eliminated the sexual dimorphism in MS, suggesting a causative role of the gut microbiome in this condition. Moreover, estrogenic compounds such as isoflavones exerted microbiome-modulating effects similar to those of 17β-estradiol and reversed symptoms of MS in the male mice. Finally, both expression and activity of intestinal alkaline phosphatase (IAP), a gut microbiota-modifying non-classical anti-microbial peptide, were upregulated by 17β-estradiol and isoflavones, whereas inhibition of IAP induced ME and LGCI in female mice, indicating a critical role of IAP in mediating the effects of estrogen on these parameters. Conclusions In summary, we have identified a previously uncharacterized microbiome-based mechanism that sheds light upon sexual dimorphism in the incidence of MS and that suggests novel therapeutic targets and strategies for the management of obesity and MS in males and postmenopausal women.

Expression of IL-22 is induced in several human inflammatory conditions, including inflammatory bowel disease (IBD). Expression of the IL-22 receptor is restricted to innate immune cells; however, the role of IL-22 in colitis has not yet been defined. We developed what we believe to be a novel microinjection-based local gene-delivery system that is capable of targeting the inflamed intestine. Using this approach, we demonstrated a therapeutic potency for IL-22-mediated activation of the innate immune pathway in a mouse model of Th2-mediated colitis that induces disease with characteristics similar to that of IBD ulcerative colitis (UC). IL-22 gene delivery enhanced STAT3 activation specifically within colonic epithelial cells and induced both STAT3-dependent expression of mucus-associated molecules and restitution of mucus-producing goblet cells. Importantly, IL-22 gene delivery led to rapid amelioration of local intestinal inflammation. The amelioration of disease by IL-22 was mediated by enhanced mucus production. In addition, local gene delivery was used to inhibit IL-22 activity through overexpression of IL-22-binding protein. Treatment with IL-22-binding protein suppressed goblet cell restitution during the recovery phase of a dextran sulfate sodium-induced model of acute colitis. These data demonstrate what we believe to be a novel function for IL-22 in the intestine and suggest the potency of a local IL-22 gene-delivery system for treating UC.

Metabolic syndrome comprises a cluster of related disorders that includes obesity, glucose intolerance, insulin resistance, dyslipidemia, and fatty liver. Recently, gut-derived chronic endotoxemia has been identified as a primary mediator for triggering the low-grade inflammation responsible for the development of metabolic syndrome. In the present study we examined the role of the small intestinal brush-border enzyme, intestinal alkaline phosphatase (IAP), in preventing a high-fat-diet–induced metabolic syndrome in mice. We found that both endogenous and orally supplemented IAP inhibits absorption of endotoxin (lipopolysaccharides) that occurs with dietary fat, and oral IAP supplementation prevents as well as reverses metabolic syndrome. Furthermore, IAP supplementation improves the lipid profile in mice fed a standard, low-fat chow diet. These results point to a potentially unique therapy against metabolic syndrome in at-risk humans.

Inflammatory bowel disease (IBD) is a group of disorders linked to inflammation of the gastrointestinal tract. Colitis is a type of IBD that affects the inner lining of the colon and has been linked to a gene known as C1orf106 . Mohanan et al. found that C1orf106 encodes a protein that stabilizes the integrity of epithelial junctions and enhances barrier defense (see the Perspective by Citi). IBD-associated mutations in C1orf106 lead to greater cytohesin-1 protein levels, changes in E-cadherin localization, and enhanced susceptibility to intestinal pathogens. Modulation of C1orf106 may thus hold promise for treating colitis and other IBDs. Science , this issue p. 1161 ; see also p. 1097 A protein encoded by a gene linked to colitis affects epithelial barrier function and thereby affects inflammatory bowel disease. Polymorphisms in C1orf106 are associated with increased risk of inflammatory bowel disease (IBD). However, the function of C1orf106 and the consequences of disease-associated polymorphisms are unknown. Here we demonstrate that C1orf106 regulates adherens junction stability by regulating the degradation of cytohesin-1, a guanine nucleotide exchange factor that controls activation of ARF6. By limiting cytohesin-1–dependent ARF6 activation, C1orf106 stabilizes adherens junctions. Consistent with this model, C1orf106 –/– mice exhibit defects in the intestinal epithelial cell barrier, a phenotype observed in IBD patients that confers increased susceptibility to intestinal pathogens. Furthermore, the IBD risk variant increases C1orf106 ubiquitination and turnover with consequent functional impairments. These findings delineate a mechanism by which a genetic polymorphism fine-tunes intestinal epithelial barrier integrity and elucidate a fundamental mechanism of cellular junctional control.

Fatty liver disease (FLD) influences liver disease progression and liver cancer risk. We investigated the impact of FLD on liver disease severity in a large North American cohort with chronic hepatitis B virus (HBV). Liver biopsies from 420 hepatitis B surface antigen-positive adults enrolled in the Hepatitis B Research Network and who were not on HBV therapy in the previous month were evaluated for inflammation and fibrosis. Steatohepatitis was based on steatosis, hepatocyte ballooning ± Mallory-Denk bodies, and perisinusoidal fibrosis. Models evaluated factors associated with steatohepatitis, and the associations of steatohepatitis with fibrosis, and longitudinal alanine aminotransferase, aspartate aminotransferase, and Fibrosis-4. The median age was 42 years, 62.5% were male, and 79.5% were Asian. One hundred thirty-two (31.4%) patients had FLD (77 [18.3%] steatosis only, 55 [13.1%] steatohepatitis). Older age, overweight/obesity, and diabetes were associated with steatohepatitis. Steatohepatitis (vs no FLD) was associated with 1.68 times higher risk of advanced fibrosis at baseline (95% confidence interval, 1.12-2.51), and there was an indication of higher incident cirrhosis rate during follow-up. Steatohepatitis vs no FLD was also independently associated with, on average, 1.39 times higher alanine aminotransferase (P < 0.01) and 1.25 times higher Fibrosis-4 (P = 0.04) across 4 years. Coexisting steatosis occurred in nearly a third of adults (13% had steatohepatitis) with chronic HBV in this North American cohort who underwent liver biopsies. Steatohepatitis was associated with advanced fibrosis and higher biochemical measures of hepatic inflammation over time. Therefore, in addition to viral suppression, screening for and managing metabolic abnormalities is important to prevent disease progression in HBV.

Programmed death ligand 1 (PD-L1) is expressed on a number of immune and cancer cells, where it can downregulate antitumor immune responses. Its expression has been linked to metabolic changes in these cells. Here we develop a radiolabeled camelid single-domain antibody (anti-PD-L1 VHH) to track PD-L1 expression by immuno-positron emission tomography (PET). PET-CT imaging shows a robust and specific PD-L1 signal in brown adipose tissue (BAT). We confirm expression of PD-L1 on brown adipocytes and demonstrate that signal intensity does not change in response to cold exposure or β-adrenergic activation. This is the first robust method of visualizing murine brown fat independent of its activation state. Current approaches to visualise brown adipose tissue (BAT) rely primarily on markers that reflect its metabolic activity. Here, the authors show that PD-L1 is expressed on brown adipocytes, does not change upon BAT activation, and that BAT volume in mice can be measured by PET-CT with a radiolabeled anti-PD-L1 antibody.

A coding polymorphism (Thr300Ala) in the essential autophagy gene, autophagy related 16-like 1 (ATG16L1), confers increased risk for the development of Crohn disease, although the mechanisms by which single disease-associated polymorphisms contribute to pathogenesis have been difficult to dissect given that environmental factors likely influence disease initiation in these patients. Here we introduce a knock-in mouse model expressing the Atg16L1 T300A variant. Consistent with the human polymorphism, T300A knock-in mice do not develop spontaneous intestinal inflammation, but exhibit morphological defects in Paneth and goblet cells. Selective autophagy is reduced in multiple cell types from T300A knock-in mice compared with WT mice. The T300A polymorphism significantly increases caspase 3- and caspase 7-mediated cleavage of Atg16L1, resulting in lower levels of full-length Atg16Ll T300A protein. Moreover, Atg16L1 T300A is associated with decreased antibacterial autophagy and increased IL-1β production in primary cells and in vivo. Quantitative proteomics for protein interactors of ATG16L1 identified previously unknown nonoverlapping sets of proteins involved in ATG16L1dependent antibacterial autophagy or IL-1β production. These findings demonstrate how the T300A polymorphism leads to cell typeand pathway-specific disruptions of selective autophagy and suggest a mechanism by which this polymorphism contributes to disease.

Gastrointestinal toxicity (GIT) is a debilitating side effect of Irinotecan (CPT-11) and limits its clinical utility. Gut dysbiosis has been shown to mediate this side effect of CPT-11 by increasing gut bacterial β-glucuronidase (GUSB) activity and impairing the intestinal mucosal barrier (IMB). We have recently shown the opposing effects of omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFA) on the gut microbiome. We hypothesized that elevated levels of tissue n-3 PUFA with a decreased n-6/n-3 PUFA ratio would reduce CPT-11-induced GIT and associated changes in the gut microbiome. Using a unique transgenic mouse (FAT-1) model combined with dietary supplementation experiments, we demonstrate that an elevated tissue n-3 PUFA status with a decreased n-6/n-3 PUFA ratio significantly reduces CPT-11-induced weight loss, bloody diarrhea, gut pathological changes, and mortality. Gut microbiome analysis by 16S rRNA gene sequencing and QIIME2 revealed that improvements in GIT were associated with the reduction in the CPT-11-induced increase in both GUSB-producing bacteria (e.g., Enterobacteriaceae) and GUSB enzyme activity, decrease in IMB-maintaining bacteria (e.g., Bifidobacterium), IMB dysfunction and systemic endotoxemia. These results uncover a host–microbiome interaction approach to the management of drug-induced gut toxicity. The prevention of CPT-11-induced gut microbiome changes by decreasing the tissue n-6/n-3 PUFA ratio could be a novel strategy to prevent chemotherapy-induced GIT.

Chronic hepatitis C infection is common among patients with human immunodeficiency virus (HIV) infection. In this randomized trial, 133 patients were assigned to receive either peginterferon alfa-2a with ribavirin or interferon alfa-2a with ribavirin. The rate of sustained virologic response was higher in the peginterferon group than in the interferon group (27 percent vs. 12 percent). Coinfection with hepatitis C virus (HCV) is common among persons infected with the human immunodeficiency virus (HIV), with a prevalence ranging from 4 to 92 percent depending on the underlying risk factors. Since the introduction of potent antiretroviral therapy, liver disease due to HCV coinfection has become a major source of mortality among HIV-infected persons. 1 – 3 The progression of liver disease appears to be accelerated in such persons. 4 Treatment regimens based on interferon and ribavirin are recommended for chronic hepatitis C but pose special concerns in persons coinfected with HIV, particularly those who are receiving antiretroviral therapy. Common side effects . . .