Impacts of the vegetable Urtica dioica on the intestinal T and B cell phenotype and macronutrient absorption in C57BL/6J mice with diet-induced obesity.

In two previous studies, we showed that supplementing a high-fat (HF) diet with 9% w/w U. dioica protects against fat accumulation, insulin resistance, and dysbiosis. This follow-up study in C57BL6/J mice aimed at testing: (i) the efficacy of the vegetable at lower doses: 9%, 4%, and 2%, (ii) the impact on intestinal T and B cell phenotype and secretions, (iii) impact on fat and glucose absorption during excess nutrient provision. At all doses, the vegetable attenuated HF diet induced fat accumulation in the mesenteric, perirenal, retroperitoneal fat pads, and liver but not the epididymal fat pad. The 2% dose protected against insulin resistance, prevented HF diet-induced decreases in intestinal T cells, and IgA+ B cells and activated T regulatory cells (Tregs) when included both in the LF and HF diets. Increased Tregs correlated with reduced inflammation; prevented increases in IL6, IFNγ, and TNFα in intestine but not expression of TNFα in epididymal fat pad. Testing of nutrient absorption was performed in enteroids. Enteroids derived from mice fed the HF diet supplemented with U. dioica had reduced absorption of free fatty acids and glucose compared to enteroids from mice fed the HF diet only. In enteroids, the ethanolic extract of U. dioica attenuated fat absorption and downregulated the expression of the receptor CD36 which facilitates uptake of fatty acids. In conclusion, including U. dioica in a HF diet, attenuates fat accumulation, insulin resistance, and inflammation. This is achieved by preventing dysregulation of immune homeostasis and in the presence of excess fat, reducing fat and glucose absorption.

Resistance to Diet Induced Visceral Fat Accumulation in C57BL/6NTac Mice Is Associated with an Enriched Lactococcus in the Gut Microbiota and the Phenotype of Immune B Cells in Intestine and Adipose Tissue.

Humans and rodents exhibit a divergent obesity phenotype where not all individuals exposed to a high calorie diet become obese. We hypothesized that in C57BL/6NTac mice, despite a shared genetic background and diet, variations in individual gut microbiota function, immune cell phenotype in the intestine and adipose determine predisposition to obesity. From a larger colony fed a high-fat (HF) diet (60% fat), we obtained twenty-four 18-22-week-old C57BL/6NTac mice. Twelve had responded to the diet, had higher body weight and were termed obese prone (OP). The other 12 had retained a lean frame and were termed obese resistant (OR). We singly housed them for three weeks, monitored food intake and determined insulin resistance, fat accumulation, and small intestinal and fecal gut microbial community membership and structure. From the lamina propria and adipose tissue, we determined the population of total and specific subsets of T and B cells. The OP mice with higher fat accumulation and insulin resistance harbored microbial communities with enhanced capacity for processing dietary sugars, lower alpha diversity, greater abundance of Lactobacilli and low abundance of Clostridia and Desulfobacterota. The OR with less fat accumulation retained insulin sensitivity and harbored microbial communities with enhanced capacity for processing and synthesizing amino acids and higher diversity and greater abundance of Lactococcus, Desulfobacterota and class Clostridia. The B cell phenotype in the lamina propria and mesenteric adipose tissue of OR mice was characterized by a higher population of IgA+ cells and B1b IgM+ cells, respectively, compared to the OP. We conclude that variable responses to the HF diet are associated with the function of individuals' gut microbiota and immune responses in the lamina propria and adipose tissue.

The Vegetable 'Kale' Protects against Dextran-Sulfate-Sodium-Induced Acute Inflammation through Moderating the Ratio of Proinflammatory and Anti-Inflammatory LPS-Producing Bacterial Taxa and Augmenting the Gut Barrier in C57BL6 Mice.

Kale (Brassica oleracea var. acephala), a food rich in bioactive phytochemicals, prevents diet-induced inflammation and gut dysbiosis. We hypothesized that the phytochemicals protect against the lipopolysaccharide (LPS)-induced acute inflammation which results from gut dysbiosis and loss of gut barrier integrity. We designed this study to test the protective effects of the whole vegetable by feeding C57BL/6J mice a rodent high-fat diet supplemented with or without 4.5% kale (0.12 g per 30 g mouse) for 2 weeks before administering 3% dextran sulfate sodium (DSS) via drinking water. After one week, DSS increased the representation of proinflammatory LPS (P-LPS)-producing genera Enterobacter and Klebsiella in colon contents, reduced the representation of anti-inflammatory LPS (A-LPS)-producing taxa from Bacteroidales, reduced the expression of tight junction proteins, increased serum LPS binding protein, upregulated molecular and histopathological markers of inflammation in the colon and shortened the colons. Mice fed kale for 2 weeks before the DSS regime had a significantly reduced representation of Enterobacter and Klebsiella and instead had increased Bacteroidales and Gram-positive taxa and enhanced expression of tight junction proteins. Downstream positive effects of dietary kale were lack of granuloma in colon samples, no shortening of the colon and prevention of inflammation; the expression of F4/80, TLR4 and cytokines 1L-1b, IL-6, TNF-a and iNOS was not different from that of the control group. We conclude that through reducing the proliferation of P-LPS-producing bacteria and augmenting the integrity of the gut barrier, kale protects against DSS-induced inflammation.

Kale supplementation during high fat feeding improves metabolic health in a mouse model of obesity and insulin resistance.

Cruciferous vegetables have been widely studied for cancer prevention and cardiovascular health. Broccoli is the cruciferous vegetable whose phytochemistry and physiological effects have been most extensively studied. Kale (Brassica oleracea var. acephala) appears on lists of 'healthiest, nutrient dense foods' but, there is paucity of data on kale as a functional food. In a 12-week study, we tested the effect of curly green kale on high fat diet (HFD) induced obesity and insulin resistance, lipid metabolism, endotoxemia and inflammation in C57BL/6J mice fed isocaloric diets. Kale supplementation did not attenuate HFD diet induced fat accumulation and insulin resistance (P = ns; n = 9) but, it lowered serum triglycerides, low density lipoprotein (LPL) cholesterol and prevented HFD induced increases in systemic endotoxemia and inflammation (serum LPS and Ccl2) (P<0.01; n = 9). In adipose tissue, kale enhanced the expression of genes involved in adipogenesis (P<0.01; n = 9), reduced the appearance of histologic markers of inflammation, downregulated both the gene expression and protein expression of the adipose tissue specific inflammation markers CD11c and F4/80 (P<0.001; n = 9) and reduced the gene expression of a battery of chemokine C-C motif ligands (Ccl2, Ccl6, Ccl7, Ccl8, Ccl9) and chemokine C-C motif receptors (Ccr2, Ccr3, Ccr5). We conclude that kale vegetable protects against HFD diet induced dysfunction through mechanisms involving lipid metabolism, endotoxemia and inflammation.

Metagenomic insights into the effects of Urtica dioica vegetable on the gut microbiota of C57BL/6J obese mice, particularly the composition of Clostridia.

Urtica dioica (UT) vegetable attenuates diet induced weight gain and insulin resistance. We hypothesized that UT imparts metabolic health by impacting the gut microbiota composition. We examined effects of UT on the cecal bacterial taxonomic signature of C57BL/6J mice fed isocaloric diets: a low-fat diet (LFD) with 10% fat, a high fat diet (HFD) with 45% fat or the HFD supplemented with 9% UT (HFUT). Among Firmicutes, the HFD had no significant impact on Clostridia, but increased Bacilli particularly genus Lactococcus and Lactobacillus. HFUT lowered Lactococcus but not Lactobacillus to levels of the LFD (P<.01; n=9). Further examination of Clostridia showed that HFUT increased genus Clostridium by over 2-fold particularly the species C. vincentii and C. disporicum and increased genus Turicibacter by three-fold (P<.05; n=9). Abundance of Clostridium and Turicibacter negatively correlated with body weight (P<.05; R2=0.42) and HOMA-IR (P<.05; R2=0.45). Turicibacter and Clostridium have been shown to be more abundant in lean phenotypes compared to obese. Clostridium impacts host phenotype by inducing intestinal T cell responses. The HFUT diet had no effect on members of Actinobacteria. Among Bacteroidetes, HFUT mainly increased proliferation of Bacteroides thetaiotaomicron (P<.05; n=9) with no significant impact on other groups. Functional analysis showed that HFUT enhanced bacterial beta-alanine and D-arginine metabolism both of which are associated with a lean phenotype and enhanced insulin sensitivity. We conclude that increasing the proliferation of Clostridium and Turicibacter and altering amino acid metabolism may be contributing mechanism(s) by which Urtica dioica impacts metabolic health.

Kale Attenuates Inflammation and Modulates Gut Microbial Composition and Function in C57BL/6J Mice with Diet-Induced Obesity.

Kale (Brassica oleracea var. acephala) is a vegetable common in most cultures but is less studied as a functional food compared to other cruciferous vegetables, such as broccoli. We investigated the effect of supplementing a high-fat diet (HFD) with kale (HFKV) in C57BL/6J mice. We particularly explored its role in metabolic parameters, gut bacterial composition and diversity using 16S rRNA sequencing, systematically compared changes under each phylum and predicted the functional potential of the altered bacterial community using PICRUSt2. Like other cruciferous vegetables, kale attenuated HFD-induced inflammation. In addition, kale modulated HFD-induced changes in cecal microbiota composition. The HFD lowered bacterial diversity, increased the Firmicutes: Bacteroidetes (F/B) ratio and altered composition. Specifically, it lowered Actinobacteria and Bacteroidetes (Bacteroidia, Rikenellaceae and Prevotellaceae) but increased Firmicutes (mainly class Bacilli). Kale supplementation lowered the F/B ratio, increased both alpha and beta diversity and reduced class Bacilli and Erysipelotrichi but had no effect on Clostridia. Within Actinobacteria, HFKV particularly increased Coriobacteriales/Coriobacteriaceae about four-fold compared to the HFD (p < 0.05). Among Bacteroidia, HFKV increased the species Bacteroides thetaiotaomicron by over two-fold (p = 0.05) compared to the HFD. This species produces plant polysaccharide digesting enzymes. Compared to the HFD, kale supplementation enhanced several bacterial metabolic functions, including glycan degradation, thiamine metabolism and xenobiotic metabolism. Our findings provide evidence that kale is a functional food that modulates the microbiota and changes in inflammation phenotype.

Urtica dioica Whole Vegetable as a Functional Food Targeting Fat Accumulation and Insulin Resistance-a Preliminary Study in a Mouse Pre-Diabetic Model.

The shoot of Urtica dioica is used in several cultures as a vegetable or herb. However, not much has been studied about the potential of this plant when consumed as a whole food/vegetable rather than an extract for dietary supplements. In a 12-week dietary intervention study, we tested the effect of U. dioica vegetable on high fat diet induced obesity and insulin resistance in C57BL/6J mice. Mice were fed ad libitum with isocaloric diets containing 10% fat or 45% fat with or without U. dioica. The diet supplemented with U. dioica attenuated high fat diet induced weight gain (p < 0.005; n = 9), fat accumulation in adipose tissue (p < 0.005; n = 9), and whole-body insulin resistance (HOMA-IR index) (p < 0.001; n = 9). Analysis of gene expression in skeletal muscle showed no effect on the constituents of the insulin signaling pathway (AKT, IRS proteins, PI3K, GLUT4, and insulin receptor). Notable genes that impact lipid or glucose metabolism and whose expression was changed by U. dioica include fasting induced adipocyte factor (FIAF) in adipose and skeletal muscle, peroxisome proliferator-activated receptor-α (Ppar-α) and forkhead box protein (FOXO1) in muscle and liver, and Carnitine palmitoyltransferase I (Cpt1) in liver (p < 0.01). We conclude that U. dioica vegetable protects against diet induced obesity through mechanisms involving lipid accumulation and glucose metabolism in skeletal muscle, liver, and adipose tissue.