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Background Intestinal Peyer’s patches (PPs) form unique niches for bacteria-immune cell interactions that direct host immunity and shape the microbiome. Here we investigate how peroral administration of probiotic bacterium Limosilactobacillus reuteri R2LC affects B lymphocytes and IgA induction in the PPs, as well as the downstream consequences on intestinal microbiota and susceptibility to inflammation. Results The B cells of PPs were separated by size to circumvent activation-dependent cell identification biases due to dynamic expression of markers, which resulted in two phenotypically, transcriptionally, and spatially distinct subsets: small IgD+/GL7−/S1PR1+/Bcl6, CCR6-expressing pre-germinal center (GC)-like B cells with innate-like functions located subepithelially, and large GL7+/S1PR1−/Ki67+/Bcl6, CD69-expressing B cells with strong metabolic activity found in the GC. Peroral L. reuteri administration expanded both B cell subsets and enhanced the innate-like properties of pre-GC-like B cells while retaining them in the sub-epithelial compartment by increased sphingosine-1-phosphate/S1PR1 signaling. Furthermore, L. reuteri promoted GC-like B cell differentiation, which involved expansion of the GC area and autocrine TGFβ-1 activation. Consequently, PD-1-T follicular helper cell-dependent IgA induction and production was increased by L. reuteri, which shifted the intestinal microbiome and protected against dextran-sulfate-sodium induced colitis and dysbiosis. Conclusions The Peyer’s patches sense, enhance and transmit probiotic signals by increasing the numbers and effector functions of distinct B cell subsets, resulting in increased IgA production, altered intestinal microbiota, and protection against inflammation.

Obesity is linked to non-alcoholic fatty liver disease and risk factors associated to metabolic syndrome. Bilberry (Vaccinium myrtillus) that contains easily fermentable fiber may strengthen the intestinal barrier function, attenuate inflammation and modulate gut microbiota composition, thereby prevent obesity development. In the current study, liver lipid metabolism, fat depot, cecal and serum short-chain fatty acids (SCFAs) and gut microbiome were evaluated in rats fed bilberries in a high-fat (HFD + BB) or low-fat (LFD + BB) setting for 8 weeks and compared with diets containing equal amount of fiber resistant to fermentation (cellulose, HFD and LFD). HFD fed rats did not obtain an obese phenotype but underwent pre-obesity events including increased liver index, lipid accumulation and increased serum cholesterol levels. This was linked to shifts of cecal bacterial community and reduction of major SCFAs. Bilberry inclusion improved liver metabolism and serum lipid levels. Bilberry inclusion under either LFD or HFD, maintained microbiota homeostasis, stimulated interscapular-brown adipose tissue depot associated with increased mRNA expression of uncoupling protein-1, enhanced SCFAs in the cecum and circulation, and promoted butyric acid and butyrate-producing bacteria. These findings suggest that bilberry may serve as a preventative dietary measure to optimize microbiome and associated lipid metabolism during or prior to HFD.

Scope: Emerging evidence suggests that high-fat diet (HFD) is associated with gut microbiome dysbiosis and related disorders. Bilberry is a prebiotic food component with known health benefits. Herein, the dynamics of the colonic mucus layer and microbiome during HFD and bilberry supplementation are addressed. Methods and results: The effects on colonic mucus thickness in vivo and gut microbiota composition (Illumina sequencing, quantitative real-time PCR) are investigated in young rats fed a low-fat diet or HFD with or without bilberries for 8 weeks (n = 8). HFD induced significant local colonic effects, despite no observed weight gain or systemic inflammation, as HFD causes epithelial upregulation of inducible nitric oxide synthase, which is counteracted by bilberry. The firmly adherent mucus layer becomes thicker and the mRNA levels of Muc2 and Tff3 are increased by HFD with or without bilberry. In parallel, HFD reduced the colonic abundance of mucolytic bacterial species Akkermansia muciniphila and Bacteroides spp. Finally, bilberry prevents HFD-induced microbiota dysbiosis, including expansion of pathobionts, for example, Enterobacteriaceae. Conclusion: HFD expand firmly adherent mucus thickness and reduce mucus-foraging bacteria populations in the colon prior to obesity. Enriching HFD with bilberry protects against intestinal inflammation and marked microbiota encroachment. (Less)

Bisphenol A (BPA) is an endocrine-disrupting chemical that may contribute to development of obesity and metabolic disorders. Humans are constantly exposed to low concentrations of BPA, and studies support that the developmental period is particularly sensitive.The aim was to investigate the effects of low-dose developmental BPA exposure on metabolic parameters in male and female Fischer 344 (F344) rat offspring.Pregnant F344 rats were exposed to BPA via their drinking water, corresponding to 0.5 μg/kg BW/d (BPA0.5;emn/em=21) or 50 μg/kg BW/d (BPA50;emn/em=16), from gestational day (GD) 3.5 until postnatal day (PND) 22, and controls were given vehicle (emn/em=26). Body weight (BW), adipose tissue, liver (weight, histology, and gene expression), heart weight, and lipid profile were investigated in the 5-wk-old offspring.Males and females exhibited differential susceptibility to the different doses of BPA. Developmental BPA exposure increased plasma triglyceride levels (0.81plusmn;0.10 mmol/L compared with 0.57plusmn;0.03 mmol/L, females BPA50emp/em=0.04; 0.81plusmn;0.05 mmol/L compared with 0.61plusmn;0.04 mmol/L, males BPA0.5emp/em=0.005) in F344 rat offspring compared with controls. BPA exposure also increased adipocyte cell density by 122% in inguinal white adipose tissue (iWAT) of female offspring exposed to BPA0.5 compared with controls (68.2plusmn;4.4 number of adipocytes/HPF compared with 55.9plusmn;1.5 number of adipocytes/HPF;emp/em=0.03) and by 123% in BPA0.5 females compared with BPA50 animals (68.2plusmn;4.4 number of adipocytes/high power field (HPF) compared with 55.3plusmn;2.9 number of adipocytes/HPF;emp/em=0.04). In iWAT of male offspring, adipocyte cell density was increased by 129% in BPA50-exposed animals compared with BPA0.5-exposed animals (69.9plusmn;5.1 number of adipocytes/HPF compared with 54.0plusmn;3.4 number of adipocytes/HPF;emp/em=0.03). Furthermore, the expression of genes involved in lipid and adipocyte homeostasis was significantly different between exposed animals and controls depending on the tissue, dose, and sex.Developmental exposure to 0.5 μg/kg BW/d of BPA, which is 8-10 times lower than the current preliminary EFSA (European Food Safety Authority) tolerable daily intake (TDI) of 4 μg/kg BW/d and is within the range of environmentally relevant levels, was associated with sex-specific differences in the expression of genes in adipose tissue plasma triglyceride levels in males and adipocyte cell density in females when F344 rat offspring of dams exposed to BPA at 0.5 μg/kg BW/d were compared with the offspring of unexposed controls. https://doi.org/10.1289/EHP505.

The availability of paracrine factors in the islets of Langerhans, and the constitution of the beta cell basement membrane can both be affected by proteolytic enzymes. This study aimed to investigate the effects of the extracellular matrix-degrading enzyme gelatinase B/matrix metalloproteinase-9 (Mmp-9) on islet function in mice. Islet function of Mmp9-deficient (Mmp9(-/-)) mice and their wild-type littermates was evaluated both in vivo and in vitro. The pancreata of Mmp9(-/-) mice did not differ from wild type in islet mass or distribution. However, Mmp9(-/-) mice had an impaired response to a glucose load in vivo, with lower serum insulin levels. The glucose-stimulated insulin secretion was reduced also in vitro in isolated Mmp9(-/-) islets. The vascular density of Mmp9(-/-) islets was lower, and the capillaries had fewer fenestrations, whereas the islet blood flow was threefold higher. These alterations could partly be explained by compensatory changes in the expression of matrix-related proteins. This in-depth investigation of the effects of the loss of MMP-9 function on pancreatic islets uncovers a deteriorated beta cell function that is primarily due to a shift in the beta cell phenotype, but also due to islet vascular aberrations. This likely reflects the importance of a normal islet matrix turnover exerted by MMP-9, and concomitant release of paracrine factors sequestered on the matrix. publisher: Elsevier articletitle: Matrix Metalloproteinase-9 Is Essential for Physiological Beta Cell Function and Islet Vascularization in Adult Mice journaltitle: The American Journal of Pathology articlelink: http://dx.doi.org/10.1016/j.ajpath.2014.12.009 content_type: article copyright: Copyright © 2015 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved. ispartof: American Journal of Pathology vol:185 issue:4 pages:1094-103 ispartof: location:United States status: published

Aim: To investigate colonic mucus thickness in vivo in health and during experimental inflammatory bowel disease. Methods: Colitis was induced with 5% DSS in drinking water for 8 days prior to experiment, when the descending colonic mucosa of anesthetized rats was studied using intravital microscopy. Mucus thickness was measured with micropipettes attached to a micromanipulator. To assess the contributions of NOS and prostaglandins in the regulation of colonic mucus thickness, the non-selective NOS-inhibitor L-NNA (10 mg/kg bolus followed by 3 mg/kg/h), the selective iNOS-inhibitor L-NIL (10 mg/kg bolus followed by 3 mg/kg/h) and the non-selective COX-inhibitor diclofenac (5 mg/kg) were administered intravenously prior to experiment. To further investigate the role of iNOS in the regulation of colonic mucus thickness, iNOS -/- mice were used. Results: Colitic rats had a thicker firmly adherent mucus layer following 8 days of DSS treatment than untreated rats (88 +/- 2 mu m vs 76 +/- 1 mu m). During induction of colitis, the thickness of the colonic mucus layer initially decreased but was from day 3 significantly thicker than in untreated rats. Diclofenac reduced the mucus thickness similarly in colitic and untreated rats (-16 +/- 5 mu m vs -14 +/- 2 mu m). While L-NNA had no effect on colonic mucus thickness in DSS or untreated controls (+3 +/- 2 mm vs +3 +/- 1 mu m), L-NIL reduced the mucus thickness significantly more in colitic rats than in controls (-33 +/- 4 mu m vs -10 +/- 3 mu m). The importance of iNOS in regulating the colonic mucus thickness was confirmed in iNOS-/- mice, which had thinner colonic mucus than wild-type mice (35 +/- 3 mu m vs 50 +/- 2 mu m, respectively). Furthermore, immunohistochemistry revealed increased levels of iNOS in the colonic surface epithelium following DSS treatment. Conclusion: Both prostaglandins and nitric oxide regulate basal colonic mucus thickness. During onset of colitis, the thickness of the mucus layer is initially reduced followed by an iNOS mediated increase.

Sex differences in obesity-induced complications such as type 2 diabetes have been reported. The aim of the study was to pinpoint the mechanisms resulting in different outcome of female and male mice on a high-fat diet (HFD). Mice fed control or HFD were monitored for weight, blood glucose, and insulin for 14 weeks. Circulating chemokines, islet endocrine function and blood flow, as well as adipose tissue populations of macrophages and regulatory T-lymphocytes (T-reg) were thereafter assessed. Despite similar weight (43.8 +/- 1.0 and 40.2 +/- 1.5 g, respectively), male but not female mice developed hyperinsulinemia on HFD as previously described (2.5 +/- 0.7 and 0.5 +/- 0.1 pmol/l, respectively) consistent with glucose intolerance. Male mice also exhibited hypertrophic islets with intact function in terms of insulin release and blood perfusion. Low-grade, systemic inflammation was absent in obese female but present in obese male mice (IL-6 and mKC, males: 77.4 +/- 17 and 1795 +/- 563; females: 14.6 +/- 4.9 and 240 +/- 22 pg/ml), and the population of inflammatory macrophages was increased in intra-abdominal adipose tissues of high-fat-fed male but not female mice. In contrast, the anti-inflammatory T-reg cell population increased in the adipose tissue of female mice in response to weight gain, while the number decreased in high-fat-fed male mice. In conclusion, female mice are protected against HFD-induced metabolic changes while maintaining an anti-inflammatory environment in the intra-abdominal adipose tissue with expanded T-reg cell population, whereas HFD-fed male mice develop adipose tissue inflammation, glucose intolerance, hyperinsulinemia, and islet hypertrophy.

Adipose tissue and metabolic homeostasis in Fischer F344 rats, exposed to developmental low doses of bisphenol A, are affected in a gender specific and non-monotonic manner