Context-dependent role of group 3 innate lymphoid cells in mucosal protection.

How group 3 innate lymphoid cells (ILC3s) regulate mucosal protection in the presence of T cells remains poorly understood. Here, we examined ILC3 function in intestinal immunity using ILC3-deficient mice that maintain endogenous T cells, T helper 17 (TH17) cells, and secondary lymphoid organs. ILC3s were dispensable for generation of TH17 and TH22 cell responses to commensal and pathogenic bacteria, and absence of ILC3s did not affect IL-22 production by CD4 T cells before or during infection. However, despite the presence of IL-22-producing T cells, ILC3s and ILC3-derived IL-22 were required for maintaining homeostatic functions of the intestinal epithelium. T cell-sufficient, ILC3-deficient mice were capable of pathogen clearance and survived infection with a low dose of Citrobacter rodentium. However, ILC3s promoted pathogen tolerance at early time points of infection by activating tissue-protective immune pathways. Consequently, ILC3s were indispensable for survival after high-dose infection. Our results demonstrate a context-dependent role for ILC3s in immune-sufficient animals and provide a blueprint for uncoupling of ILC3 and TH17 cell functions.

Microbiota imbalance induced by dietary sugar disrupts immune-mediated protection from metabolic syndrome.

How intestinal microbes regulate metabolic syndrome is incompletely understood. We show that intestinal microbiota protects against development of obesity, metabolic syndrome, and pre-diabetic phenotypes by inducing commensal-specific Th17 cells. High-fat, high-sugar diet promoted metabolic disease by depleting Th17-inducing microbes, and recovery of commensal Th17 cells restored protection. Microbiota-induced Th17 cells afforded protection by regulating lipid absorption across intestinal epithelium in an IL-17-dependent manner. Diet-induced loss of protective Th17 cells was mediated by the presence of sugar. Eliminating sugar from high-fat diets protected mice from obesity and metabolic syndrome in a manner dependent on commensal-specific Th17 cells. Sugar and ILC3 promoted outgrowth of Faecalibaculum rodentium that displaced Th17-inducing microbiota. These results define dietary and microbiota factors posing risk for metabolic syndrome. They also define a microbiota-dependent mechanism for immuno-pathogenicity of dietary sugar and highlight an elaborate interaction between diet, microbiota, and intestinal immunity in regulation of metabolic disorders.

Foxo in T Cells Regulates Thermogenic Program through Ccr4/Ccl22 Axis.

Crosstalk between immunity and the thermogenic program has provided insight into metabolic energy regulation. Here, we generated thermogenic program-accelerating mice (T-QKO), in which Foxo1 is knockout and Foxo3 is hetero-knockout in CD4+ T cells. T-QKO exhibit lean phenotype under HFD due to increased energy expenditure. Cold exposure significantly increased expression of the thermogenic genes (Ppargc1a and Ucp1), Th2 cytokines (Il4 and Il13), and Th2 marker gene (Gata3) in subcutaneous adipose tissue (SC) of T-QKO. Furthermore, Ccr4 expression was significantly increased in Th2 cells of T-QKO, and cold exposure induced Ccl22 expression in SC, leading to increased accumulation of Th2 cell population in SC of T-QKO. These data reveal a mechanism by which cold exposure induces selective recruitment of Th2 cells into SC, leading to regulation of energy expenditure by generating beige adipocyte and suggest that inhibition of Foxo in T cells may support a strategy to prevent and treat obesity.

Zfp238 Regulates the Thermogenic Program in Cooperation with Foxo1.

Obesity has become an explicit public health concern because of its relevance to metabolic syndrome. Evidence points to the significance of beige adipocytes in regulating energy expenditure. Here, using yeast two-hybrid screening, we show that Zfp238 is a Foxo1 co-repressor and that adipose-tissue-specific ablation of Zfp238 (Adipo-Zfp238KO) in mice leads to obesity, decreased energy expenditure, and insulin resistance under normal chow diet. Adipo-Zfp238KO inhibits induction of Ucp1 expression in subcutaneous adipose tissue upon cold exposure or CL316243, but not in brown adipose tissue. Furthermore, knockdown of Zfp238 in 3T3-L1 cells decreases Ucp1 expression in response to cool incubation or forskolin significantly compared with control cells. In contrast, overexpression of Zfp238 in 3T3-L1 cells significantly increases Ucp1 expression in response to forskolin. Finally, double knockdown of both Zfp238 and Foxo1 normalizes Ucp1 induction. These data suggest that Zfp238 in adipose tissue regulates the thermogenic program in cooperation with Foxo1.

Association of Maternal Factors with Perinatal Complications in Pregnancies Complicated with Diabetes: A Single-Center Retrospective Analysis.

OBJECTIVE: The aim of this study was to clarify the association of maternal factors with perinatal complications in pregnancies complicated with type 1 (T1D) or type 2 diabetes (T2D). METHODS: We conducted a retrospective chart review and enrolled 26 Japanese pregnant women with diabetes who received perinatal care at our hospital between 2008 and 2015. Perinatal complications were defined as one or more of the following: miscarriage, fetal death, fetal dysfunction, fetal structural anomaly, small-for-gestational age, large-for-gestational age (LGA), premature birth, neonatal hypoglycemia, pregnancy-induced hypertension (PIH), deterioration of maternal kidney function, and urgent Caesarean section (CS). The associations between perinatal complications and maternal factors were examined. RESULTS: Approximately 70% and 50% of women with T1D and T2D experienced perinatal complications, respectively. LGA, neonatal hypoglycemia, and urgent CS were major perinatal complications in women with T1D, while PIH and urgent CS were major complications in those with T2D. In women with T1D, pre-gestational HbA1c was significantly higher in women with perinatal complications than in those without. In women with T2D, pre-gestational body mass index was significantly higher in women with perinatal complications than in those without. CONCLUSIONS: These findings suggest that while pre-gestational glycemic control remains the most important issue in women with T1D, pre-gestational weight control in addition to glycemic control should be greater emphasized in women with T2D to reduce the risk of perinatal complications.

Colonic Pro-inflammatory Macrophages Cause Insulin Resistance in an Intestinal Ccl2/Ccr2-Dependent Manner.

High-fat diet (HFD) induces low-grade chronic inflammation and insulin resistance. However, little is known about the mechanism underlying HFD-induced chronic inflammation in peripheral insulin-responsive tissues. Here, we show that colonic pro-inflammatory macrophages regulate insulin sensitivity under HFD conditions. To investigate the pathophysiological role of colonic macrophages, we generated macrophage-specific chemokine (C-C Motif) receptor 2 (Ccr2) knockout (M-Ccr2KO) and intestinal epithelial cell-specific tamoxifen-inducible Ccl2 knockout (Vil-Ccl2KO) mice. Both strains exhibited similar body weight to control under HFD. However, they exhibited decreased infiltration of colonic pro-inflammatory macrophages, decreased intestinal permeability, and inactivation of the colonic inflammasome. Interestingly, they showed significantly improved glucose tolerance and insulin sensitivity with decreased chronic inflammation of adipose tissue. Therefore, inhibition of pro-inflammatory macrophage infiltration prevents HFD-induced insulin resistance and could be a novel therapeutic approach for type 2 diabetes.

Bile acid binding resin improves hepatic insulin sensitivity by reducing cholesterol but not triglyceride levels in the liver.

AIMS: Bile acid binding resin (BAR) improves glycaemic control in patients with type 2 diabetes. Although the mechanism is hypothesised to involve the clearance of excess hepatic triglyceride, this hypothesis has not been examined in appropriately designed studies. Therefore, we investigated whether reduced hepatic triglyceride deposition is involved in BAR-mediated improvements in glycaemic control in spontaneous fatty liver diabetic mice without dietary interventions. METHODS: Male 6-week-old fatty liver Shionogi (FLS) mice were fed a standard diet without or with 1.5% BAR (colestilan) for 6 weeks. Glucose tolerance, insulin sensitivity, hepatic lipid content, and gene expression were assessed. A liver X receptor (LXR) agonist was also administered to activate the LXR pathway. We also retrospectively analysed the medical records of 21 outpatients with type 2 diabetes who were treated with colestilan for ≥6 months. RESULTS: BAR enhanced glucose tolerance and insulin sensitivity in FLS mice without altering fat mass. BAR improved hepatic insulin sensitivity, increased IRS2 expression, and decreased SREBP expression. BAR reduced hepatic cholesterol levels but not hepatic triglyceride levels. BAR also reduced the expression of LXR target genes, and LXR activation abolished the BAR-mediated improvements in glycaemic control. Colestilan significantly lowered serum cholesterol levels and improved glycaemic control in patients with type 2 diabetes. CONCLUSIONS: BAR improved hepatic insulin resistance in FLS mice by reducing hepatic cholesterol without affecting hepatic triglyceride levels or body fat distribution. Our study revealed that BAR improves glycaemic control at least in part by downregulating the hepatic cholesterol-LXR-IRS2 pathway.

Loss of Pdk1-Foxo1 signaling in myeloid cells predisposes to adipose tissue inflammation and insulin resistance.

Chronic inflammation in adipose tissue contributes to obesity-related insulin resistance. The 3-phosphoinositide-dependent protein kinase 1 (Pdk1)/forkhead transcription factor (Foxo1) pathway is important in regulating glucose and energy homeostasis, but little is known about this pathway in adipose tissue macrophages (ATMs). To investigate this, we generated transgenic mice that carried macrophage/granulocyte-specific mutations, including a Pdk1 knockout (LysMPdk1(-/-)), a Pdk1 knockout with transactivation-defective Foxo1 (Δ256LysMPdk1(-/-)), a constitutively active nuclear (CN) Foxo1 (CNFoxo1(LysM)), or a transactivation-defective Foxo1 (Δ256Foxo1(LysM)). We analyzed glucose metabolism and gene expression in ATM populations isolated with fluorescence-activated cell sorting. The LysMPdk1(-/-) mice exhibited elevated M1 macrophages in adipose tissue and insulin resistance. Overexpression of transactivation-defective Foxo1 rescued these phenotypes. CNFoxo1(LysM) promoted transcription of the C-C motif chemokine receptor 2 (Ccr2) in ATMs and increased M1 macrophages in adipose tissue. On a high-fat diet, CNFoxo1(LysM) mice exhibited insulin resistance. Pdk1 deletion or Foxo1 activation in bone marrow-derived macrophages abolished insulin and interleukin-4 induction of genes involved in alternative macrophage activation. Thus, Pdk1 regulated macrophage infiltration by inhibiting Foxo1-induced Ccr2 expression. This shows that the macrophage Pdk1/Foxo1 pathway is important in regulating insulin sensitivity in vivo.

Novel repressor regulates insulin sensitivity through interaction with Foxo1.

Forkhead box-containing protein o (Foxo) 1 is a key transcription factor in insulin and glucose metabolism. We identified a Foxo1-CoRepressor (FCoR) protein in mouse adipose tissue that inhibits Foxo1's activity by enhancing acetylation via impairment of the interaction between Foxo1 and the deacetylase Sirt1 and via direct acetylation. FCoR is phosphorylated at Threonine 93 by catalytic subunit of protein kinase A and is translocated into nucleus, making it possible to bind to Foxo1 in both cytosol and nucleus. Knockdown of FCoR in 3T3-F442A cells enhanced expression of Foxo target and inhibited adipocyte differentiation. Overexpression of FCoR in white adipose tissue decreased expression of Foxo-target genes and adipocyte size and increased insulin sensitivity in Lepr(db/db) mice and in mice fed a high-fat diet. In contrast, Fcor knockout mice were lean, glucose intolerant, and had decreased insulin sensitivity that was accompanied by increased expression levels of Foxo-target genes and enlarged adipocytes. Taken together, these data suggest that FCoR is a novel repressor that regulates insulin sensitivity and energy metabolism in adipose tissue by acting to fine-tune Foxo1 activity.

A case of IgA-related enteropathy complicated with gastrointestinal bleeding and progressive IgA nephropathy: a possible variant Henoch-Schönlein purpura?

Here, we report an adult patient with IgA-related enteropathy complicated with massive intestinal bleeding and acute renal failure, but without skin lesions. Surgical resection of the small intestine and steroid pulse therapy was performed. Histopathology revealed significant deposition of IgA and C3 in the small vessels of the intestine and the kidney mesangium. Although skin purpura was absent, the histopathology and clinical manifestations suggested that the pathophysiology was similar to Henoch-Schönlein purpura (HSP), implying IgA-related enteropathy as a subclass of HSP. Retrospective analysis indicates that terminal ileum lesions may be a poor prognostic indicator.

Pioglitazone might prevent the progression of slowly progressive type 1 diabetes.

Although recent studies recommended that insulin should be administered to patients with slowly progressive type 1 diabetes, even those with non-insulin dependent status, patients prefer oral hypoglycemic agents to insulin injections. We report a slowly progressive type 1 diabetic patient whose insulin production was preserved for 4 years (SigmaC-peptide from 29.48 ng/mL to 24.58 ng/mL) using pioglitazone despite a high titer of anti-GAD antibody (GADA; 120.7 U/mL). This case suggests that pioglitazone might prevent or delay the loss of insulin secretion and insulin dependency in slowly progressive type 1 diabetic patients.