n-3 and n-6 Polyunsaturated Fatty Acids Modulate Macrophage-Myocyte Inflammatory Crosstalk and Improve Myocyte Insulin Sensitivity.

In obesity, circulating saturated fatty acids (SFAs) and inflammatory cytokines interfere with skeletal muscle insulin signaling, leading to whole body insulin resistance. Further, obese skeletal muscle is characterized by macrophage infiltration and polarization to the inflammatory M1 phenotype, which is central to the development of local inflammation and insulin resistance. While skeletal muscle-infiltrated macrophage-myocyte crosstalk is exacerbated by SFA, the effects of other fatty acids, such as n-3 and n-6 polyunsaturated fatty acids (PUFAs), are less studied. Thus, the objective of this study was to determine the effects of long-chain n-3 and n-6 PUFAs on macrophage M1 polarization and subsequent effects on myocyte inflammation and metabolic function compared to SFA. Using an in vitro model recapitulating obese skeletal muscle cells, differentiated L6 myocytes were cultured for 24 h with RAW 264.7 macrophage-conditioned media (MCM), followed by insulin stimulation (100 nM, 20 min). MCM was generated by pre-treating macrophages for 24 h with 100 µM palmitic acid (16:0, PA-control), arachidonic acid (20:4n-6, AA), or docosahexaenoic acid (22:6n-3, DHA). Next, macrophage cultures were stimulated with a physiological dose (10 ng/mL) of lipopolysaccharide for an additional 12 h to mimic in vivo obese endotoxin levels. Compared to PA, both AA and DHA reduced mRNA expression and/or secreted protein levels of markers for M1 (TNFα, IL-6, iNOS; p < 0.05) and increased those for M2 (IL-10, TGF-ß; p < 0.05) macrophage polarization. In turn, AA- and DHA-derived MCM reduced L6 myocyte-secreted cytokines (TNFα, IL-6; p < 0.05) and chemokines (MCP-1, MIP-1ß; p < 0.05). Only AA-derived MCM increased L6-myocyte phosphorylation of Akt (p < 0.05), yet this was inconsistent with improved insulin signaling, as only DHA-derived MCM improved L6 myocyte glucose uptake (p < 0.05). In conclusion, dietary n-3 and n-6 PUFAs may be a useful strategy to modulate macrophage-myocyte inflammatory crosstalk and improve myocyte insulin sensitivity in obesity.

Effect of Lifelong Exposure to Dietary Plant and Marine Sources of n-3 Polyunsaturated Fatty Acids on Morphologic and Gene Expression Biomarkers of Intestinal Health in Early Life.

Altered intestinal health is also associated with the incidence and severity of many chronic inflammatory conditions, which could be attenuated via dietary n-3 PUFA interventions. However, little is known about the effect of lifelong exposure to n-3 PUFA from plant and marine sources (beginning in utero via the maternal diet) on early life biomarkers of intestinal health. Harems of C57Bl/6 mice were randomly assigned to one of three isocaloric AIN-93G modified diets differing in their fat sources consisting of the following: (i) 10% safflower oil (SO, enriched in n-6 PUFA), (ii) 3% flaxseed oil + 7% safflower oil (FX, plant-based n-3 PUFA-enriched diet), or (iii) 3% menhaden fish oil + 7% safflower oil (MO, marine-based n-3 PUFA-enriched diet). Mothers remained on these diets throughout pregnancy and offspring (n = 14/diet) continued on the same parental diet until termination at 3 weeks of age. In ileum, villi:crypt length ratios were increased in both the FX and MO dietary groups compared to SO (p < 0.05). Ileum mRNA expression of critical intestinal health biomarkers was increased by both n-3 PUFA-enriched diets including Relmß and REG3γ compared to SO (p < 0.05), whereas only the FX diet increased mRNA expression of TFF3 and Muc2 (p < 0.05) and only the MO diet increased mRNA expression of ZO-1 (p < 0.05). In the proximal colon, both the FX and MO diets increased crypt lengths compared to SO (p < 0.05), whereas only the MO diet increased goblet cell numbers compared to SO (p < 0.05). Further, the MO diet increased proximal colon mRNA expression of Relmß and REG3γ (p < 0.05) and both MO and FX increased mRNA expression of Muc2 compared to SO (p < 0.05). Collectively, these results demonstrate that lifelong exposure to dietary n-3 PUFA, beginning in utero, from both plant and marine sources, can support intestinal health development in early life. The differential effects between plant and marine sources warrants further investigation for optimizing health.

Effect of Short-Chain Fatty Acids on Inflammatory and Metabolic Function in an Obese Skeletal Muscle Cell Culture Model.

The fermentation of non-digestible carbohydrates produces short-chain fatty acids (SCFAs), which have been shown to impact both skeletal muscle metabolic and inflammatory function; however, their effects within the obese skeletal muscle microenvironment are unknown. In this study, we developed a skeletal muscle in vitro model to mimic the critical features of the obese skeletal muscle microenvironment using L6 myotubes co-treated with 10 ng/mL lipopolysaccharide (LPS) and 500 µM palmitic acid (PA) for 24 h ± individual SCFAs, namely acetate, propionate and butyrate at 0.5 mM and 2.5 mM. At the lower SCFA concentration (0.5 mM), all three SCFA reduced the secreted protein level of RANTES, and only butyrate reduced IL-6 protein secretion and the intracellular protein levels of activated (i.e., ratio of phosphorylated-total) NFκB p65 and STAT3 (p < 0.05). Conversely, at the higher SCFA concentration (2.5 mM), individual SCFAs exerted different effects on inflammatory mediator secretion. Specifically, butyrate reduced IL-6, MCP-1 and RANTES secretion, propionate reduced IL-6 and RANTES, and acetate only reduced RANTES secretion (p < 0.05). All three SCFAs reduced intracellular protein levels of activated NFκB p65 and STAT3 (p < 0.05). Importantly, only the 2.5 mM SCFA concentration resulted in all three SCFAs increasing insulin-stimulated glucose uptake compared to control L6 myotube cultures (p < 0.05). Therefore, SCFAs exert differential effects on inflammatory mediator secretion in a cell culture model, recapitulating the obese skeletal muscle microenvironment; however, all three SCFAs exerted a beneficial metabolic effect only at a higher concentration via increasing insulin-stimulated glucose uptake, collectively exerting differing degrees of a beneficial effect on obesity-associated skeletal muscle dysfunction.

The Tolerance Model of Non-Inflammatory Immune Competence in Acute Pediatric Malnutrition: Origins, Evidence, Test of Fitness and Growth Potential.

The tolerance model rests on the thesis of a physiologically regulated, albeit unsustainable, systemic attempt to adapt to the catabolic challenge posed by acute prepubescent malnutrition even in its severe forms. The model centers on the immunological component of the attempt, positing reorientation toward a non-inflammatory form of competence in place of the classic paradigm of immunological attrition and exhaustion. The foundation of the model was laid in 1990, and sixteen years later it was articulated formally on the basis of a body of evidence centered on T cell cytokines and interventions with cytokine and hormonal mediators. The benefit originally suggested was a reduced risk of autoimmune pathologies consequent to the catabolic release of self-antigens, hence the designation highlighting immune tolerance. Herein, the emergence of the tolerance model is traced from its roots in the recognition that acute malnutrition elicits an endocrine-based systemic adaptive attempt. Thereafter, the growth of the evidence base supporting the model is outlined, and its potential to shed new light on existing information is tested by application to the findings of a published clinical study of acutely malnourished children. Finally, some knowledge gaps pertinent to the model are identified and its potential for growth consonant with evolving perceptions of immunobiology is illustrated.

Differential Effects of Short-Chain Fatty Acids on L6 Myotube Inflammatory Mediator Production in Response to Lipopolysaccharide- or Palmitic Acid-Stimulation.

Short-chain fatty acids (SCFA) produced from dietary non-digestible carbohydrate fermentation have metabolic effects in skeletal muscle; however, their effect on inflammatory mediator production is unknown. In this study, L6 myotubes were cultured with individual SCFA (acetate, propionate, and butyrate) at 0.5 mM and 2.5 mM ± 10 ng/mL lipopolysaccharide (LPS) or ± 500 µM palmitic acid (PA) for 24 h. In response to LPS, only butyrate had an effect at the lower concentration (0.5 mM), whereas at the higher concentration (2.5 mM) both propionate and butyrate reduced MCP-1, MIP-1α, and RANTES secretion (p < 0.05), and only butyrate reduced IL-6 secretion and intracellular protein levels of phospho-STAT3 (p < 0.05). In response to PA, 0.5 mM butyrate reduced protein expression of phospho-NFκB p65 and the secretion of IL-6, MIP-1α, and MCP-1, whereas all three SCFA reduced RANTES secretion (p < 0.05). At the 2.5 mM SCFA concentration combined with PA stimulation, all three SCFA reduced intracellular protein expression of phospho-NFκB p65 and phospho-STAT3 and secreted protein levels of MCP-1, IL-6, and RANTES, whereas only butyrate reduced secretion of MIP-1α (p < 0.05). Thus, SCFA exhibit differential effects on inflammatory mediator expression in response to LPS and PA stimulation, which has implications for their individual impacts on inflammation-mediated skeletal muscle dysfunction.

Impact of the COVID-19-induced shift to online dietetics training on PDEP competency acquisition and mental health.

Purpose: A pilot study to investigate the impact of the COVID-19 pandemic and shift to online learning and practicum training on dietetics students' perceptions of Partnership for Dietetic Education and Practice (PDEP) competency acquisition and mental health.Methods: Dietetics students (n = 19) at the University of Guelph (2020-2021) were invited to complete an anonymous online survey to assess self-reported online dietetics practicum training experiences including (i) benefits and challenges, (ii) PDEP competency acquisition, and (iii) impact on mental health.Results: The benefits of online dietetics training included schedule flexibility (42.1%), reduced commute time (31.6%), and acquiring virtual counselling experience (21.1%). Reported challenges were insufficient communication with preceptors (36.8%), increased project workload (57.9%), and technology (15.8%). In online practicum placements, 52.6% of dietetics students reported adequately acquiring all PDEP competencies, with Nutrition Care identified as the most challenging to obtain (63.2%). A negative impact on mental health and increased levels of stress/anxiety were reported in 94.7% of trainees. Notably, 63.2% of students favoured continuation of online dietetics training through a hybrid or entirely online format.Conclusion: Online dietetics training has the potential to complement the traditional in-person model; however, further adaptation is required to optimize PDEP competency acquisition and students' mental health.

Exploring Barriers to Food Security Among Immigrants: A Critical Role for Public Health Nutrition.

Upon moving to a new country and new food environment, 2 important public health issues may be experienced by immigrants as they adapt to their new country of residence, namely a higher prevalence of food insecurity and/or a decline in overall health over time postimmigration. Therefore, improving the food environment experienced by new migrants may be an effective strategy to reduce long-term health complications and improve well-being postimmigration. The aim of this paper is to discuss the potential barriers experienced by new immigrants in the access, availability, and utilization of familiar culturally appropriate foods and the subsequent impact on their food security status. Culturally appropriate foods are foods commonly consumed as part of cultural food traditions and are often staples within the diet; however, limited availability of and/or access to these foods can reduce food security. By understanding the barriers to food security and challenges that may be faced by immigrants and refugees, dietitians will be better equipped to assist these individuals in accessing culturally familiar foods and improve quality of life. In this capacity, dietitians can play a critical public health nutrition role by serving as a conduit for new immigrants to access community resources and navigate a new food environment.

Dietary ω-3 polyunsaturated fatty acids modulate CD4+ T-cell subset markers, adipocyte antigen-presentation potential, and NLRP3 inflammasome activity in a coculture model of obese adipose tissue.

OBJECTIVES: Chronic low-grade inflammation in obesity is partly driven by inflammatory cross talk between adipocytes and interferon-γ-secreting CD4+ T-helper (Th)1 cells, a process we have shown may be mitigated by long-chain (LC) ω-3 polyunsaturated fatty acids (PUFAs). Our objective was to study pivotal mediators of interactions between Th1 cells and adipocytes as potential mechanisms underlying the antiinflammatory effects of LC ω-3 PUFAs. METHODS: Using an in vitro model, 3T3-L1 adipocytes were cocultured with purified splenic CD4+ T cells from C57BL/6 mice consuming one of two isocaloric high-fat (HF) diets (60% kcal fat), containing either 41.2% kcal from lard + 18.7% kcal from corn oil (control, HF) or 41.2% kcal from lard + 13.4% kcal from corn oil + 5.3% kcal from fish oil (HF+FO). Cocultures were stimulated for 48 h with lipopolysaccharide (10 ng/mL). RESULTS: Compared with HF cocultures, HF+FO reduced Th1-cell markers (including secreted interferon-γ) and increased Th2-cell markers, consistent with reduced expression of genes related to major histocompatibility complex II (P < 0.05). HF+FO also blunted markers of priming and activity of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome (P < 0.05). In confirmatory work, 3T3-L1 adipocyte pretreatment with the LC ω-3 PUFA docosahexaenoic acid (100 µM, 24 h) blunted interferon-γ-induced (5 ng/mL, 24 h) expression of genes related to major histocompatibility complex II and priming and activity markers of the NLRP3 inflammasome compared with control (P < 0.05). CONCLUSIONS: Inflammatory interactions between CD4+ T cells and adipocytes may provide a target for LC ω-3 PUFAs to mitigate obesity-associated inflammation.

Fish oil supplementation increases expression of mammary tumor apoptosis mediators and reduces inflammation in an obesity-associated HER-2 breast cancer model.

Obesity is associated with inflammation and has been shown to increase breast cancer severity. The objective of this study was to examine the effect of fish oil (FO) supplementation in obesity-associated mammary tumorigenesis in the MMTV-neu(ndl)-YD5 mouse model of human epidermal growth factor receptor-2 positive BC. Female mice were fed one of three diets for 16 weeks: i) high fat diet [HF, % kacl: 41.2% lard, 18.7% corn oil (CO)], ii) an isocaloric HF plus menhaden FO diet (HF+FO, % kcal: 41.2 lard, 13.4% CO, 5.3% FO), iii) low fat diet (LF, % kcal: 4.7% lard, 6% CO). HF mice had increased body weight, visceral adipose weight and serum hormone concentrations (increased leptin and resistin; decreased adiponectin) versus LF, which was attenuated in the HF+FO group versus HF (P<.05). Compared to HF, tumor onset was delayed in HF+FO and LF mice (P<0.05). Compared to HF, HF+FO reduced mammary tumor multiplicity (-27%), tumor weight (-46%) and total tumor volume (-50%) (P<0.05). Additionally, HF+FO reduced mammary tumor multiplicity (-33%), tumor weight (-39%) and total tumor volume (-60%) versus LF. HF+FO improved mammary tumor apoptosis status with increased expression of pro-apoptotic Bad and decreased expression of anti-apoptotic Bcl-xLmediators versus HF (P<0.05). Additionally, HF+FO decreased tumor protein expression of activated Akt, NFκB p65 and STAT3, versus HF (P<0.05). Tumor mRNA expression of inflammatory mediators TNFα, IL-6 and leptin were reduced in HF+FO, whereas IL-10 expression was increased compared to HF (P<0.05). Collectively these results demonstrate the efficacy of FO supplementation for improving obesity-associated breast cancer outcomes.

Navy Bean Supplementation in Established High-Fat Diet-Induced Obesity Attenuates the Severity of the Obese Inflammatory Phenotype.

Cooked common beans (Phaseolus vulgaris) improve intestinal health in lean mice and attenuate intestinal dysbiosis and inflammation when consumed concurrent with obesity development. We determined the effects of a high-fat (HF) bean supplemented diet in mice with established obesity (induced by 12 weeks of HF diet (60% fat as kcal)) compared to obese mice consuming a HF or low-fat (LF) weight loss control diet. Obese C57BL/6 male mice remained consuming HF for eight weeks or were randomly switched from HF to an isocaloric HF with 15.7% cooked navy bean powder diet (HFàHFB) or LF (11% fat as kcal; HFàLF) (n = 12/group). HFàHFB improved the obese phenotype, including (i) fecal microbiome (increased Prevotella, Akkermansia muciniphila, and short-chain fatty acid levels), (ii) intestinal health (increased ZO-1, claudin-2, Muc2, Relmß, and Reg3γ expression), and (iii) reduced adipose tissue (AT) inflammatory proteins (NFκBp65, STAT3, IL-6, MCP-1, and MIP-1α), versus HF (p < 0.05). Conversely, HFàLF reduced body weight and circulating hormones (leptin, resistin, and PAI-1) versus HF and HFàHFB (p < 0.05); however, AT inflammation and intestinal health markers were not improved to the same degree as HFàHFB (p < 0.05). Despite remaining on a HF obesogenic diet, introducing beans in established obesity improved the obese phenotype (intestinal health and adipose inflammation) more substantially than weight loss alone.

Studying Adipocyte and Immune Cell Cross Talk Using a Co-culture System.

The co-culture of adipocytes and immune cells, such as macrophages or T cells (CD4+ or CD8+ subsets), is a novel experimental approach used to study paracrine interactions (or the cross talk) between cultured cell types in isolation, in order to understand their role in obese adipose tissue (AT) inflammation and dysfunction. Here we describe the general methodologies required for the co-culture of mature adipocytes (differentiated 3T3-L1 pre-adipocyte cell line) with primary immune cell subsets purified from mouse splenic mononuclear cells using a magnetic MicroBead positive selection, wherein multiple immune cell populations can be purified sequentially from a single mouse spleen, thereby providing diversity in the types of immune cells that can be co-cultured with adipocytes. Additionally, we describe experimental procedures for co-culturing adipocytes and immune cells in two different co-culture systems, including a cell contact-dependent co-culture system, wherein the cells are in direct physical contact, and a cell contact-independent, soluble mediator-driven co-culture system wherein the cells are physically separated by a trans-well semipermeable membrane. Finally, we discuss how these co-culture models can be utilized to recapitulate the AT microenvironment in obesity by utilizing physiologically relevant ratios of adipocytes:immune cells (specifically CDllb+ macrophages, CD4+ T cells, or CD8+ T cells) and lipopolysaccharide stimulation that mimics endotoxin concentrations observed in obesity.

Dietary long-chain n-3 PUFAs mitigate CD4+ T cell/adipocyte inflammatory interactions in co-culture models of obese adipose tissue.

Obese adipose tissue (AT) inflammation is partly driven by accumulation of CD4+ T helper (Th)1 cells and reduced Th2 and T regulatory subsets, which promotes macrophage chemotaxis and ensuing AT metabolic dysfunction. This study investigated CD4+ T cell/adipocyte cytokine-mediated paracrine interactions (cross talk) as a target for dietary intervention to mitigate obese AT inflammation. Using an in vitro co-culture model designed to recapitulate CD4+ T cell accumulation in obese AT (5% of stromal vascular cellular fraction), 3T3-L1 adipocytes were co-cultured with purified splenic CD4+ T cells from C57Bl/6 mice consuming one of two isocaloric diets containing either 10% w/w safflower oil (control, CON) or 7% w/w safflower oil+3% w/w fish oil (FO) for 4 weeks (n=8-11/diet). The FO diet provided 1.9% kcal from the long-chain (LC) n-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid and docosahexaenoic acid, a dose that can be achieved by supplementation. Co-cultures were stimulated for 48 h with lipopolysaccharide (LPS) to mimic in vivo obese endotoxin levels or with conditioned media collected from LPS-stimulated visceral AT isolated from CON-fed mice. In both stimulation conditions, FO reduced mRNA expression and/or secreted protein levels of Th1 markers (T-bet, IFN-γ) and increased Th2 markers (GATA3, IL-4), concomitant with reduced inflammatory cytokines (IL-1ß, IL-6, IL-12p70, TNF-α), macrophage chemokines (MCP-1, MCP-3, MIP-1α, MIP-2) and levels of activated central regulators of inflammatory signaling (NF-κB, STAT-1, STAT-3) (P<.05). Therefore, CD4+ T cell/adipocyte cross talk represents a potential target for LC n-3 PUFAs to mitigate obese AT inflammation.

CD8+ T cell/adipocyte inflammatory cross talk and ensuing M1 macrophage polarization are reduced by fish-oil-derived n-3 polyunsaturated fatty acids, in part by a TNF-α-dependent mechanism.

Obese visceral adipose tissue (AT) inflammation is driven by adipokine-mediated cross talk between CD8+ T cells and adipocytes, a process mitigated by long-chain (LC) n-3 polyunsaturated fatty acids (PUFA) but underlying mechanisms and ensuing effects on macrophage polarization status are unknown. Using an in vitro co-culture model that recapitulates the degree of CD8+ T cell infiltration reported in obese AT, 3T3-L1 adipocytes were co-cultured for 24 h with purified splenic CD8+ T cells from C57Bl/6 mice consuming either a 10% w/w safflower oil (control, CON) or 7% w/w safflower oil + 3% w/w fish oil (FO) diet for 4 weeks (n=8-10/diet). Co-cultured cells were in direct contact or in a contact-independent condition separated by a Transwell permeable membrane and stimulated with lipopolysaccharide (10 ng/ml) to mimic in vivo obese endotoxin levels. In contact-dependent co-cultures, FO reduced inflammatory (IL-6, TNFα, IFN-γ) and macrophage chemotactic (CCL2, CCL7, CCL3) mRNA expression and/or secreted protein, NF-κB p65 activation, ROS accumulation, NLRP3 inflammasome priming (Nlrp3, Il1ß mRNA) and activation (caspase-1 activity) compared to CON (P<.05). The anti-inflammatory action of FO was reproduced by the addition of a TNF-α neutralizing antibody (1 µg/ml) to CON co-cultures (CON/anti-TNF-α), albeit to a lesser degree. Conditioned media from FO and CON/anti-TNF-α co-cultures, in turn, reduced RAW 264.7 macrophage mRNA expression of M1 polarization markers (iNos, Cd11c, Ccr2) and associated inflammatory cytokines (Il6, Tnfα, Il1ß) compared to CON. These data suggest that inflammatory CD8+ T cell/adipocyte cross talk is partially attributable to TNF-α signaling, which can be mitigated by LC n-3 PUFA.

Fish oil supplementation to a high-fat diet improves both intestinal health and the systemic obese phenotype.

Impaired intestinal health characterized by a dysbiotic microbial community and a dysfunctional epithelial barrier contributes to host inflammation and metabolic dysfunction in obesity. Fish oil (FO)-derived n-3 polyunsaturated fatty acids have been shown to improve aspects of the obese phenotype; however, their effect on obese intestinal health is unknown. This study aimed to determine the effect of dietary FO on the intestinal microenvironment, including the microbial community and epithelial barrier, in a mouse model of high-fat diet induced obesity and metabolic dysfunction. Male C57BL/6 mice were fed (12 weeks) either a high-fat diet (HF, 60% fat as kcal) or an isocaloric HF supplemented with Menhaden FO (5.3% kcal, HF + FO). 16S rRNA sequencing was used to determine changes in fecal microbiota. Intestinal (ileum and colon) and epididymal adipose tissue RNA was used to assess biomarkers of barrier integrity and inflammatory status, respectively. Serum was used to assess adipokine concentrations and insulin resistance. HF + FO diet altered the fecal microbiota by decreasing the abundance of Firmicutes and increasing the abundance of members of the Bacteroidetes phyla, as well as increasing the abundance of antiobesogenic Akkermansia muciniphila, compared to HF. Intestinal epithelial barrier functions were improved by HF + FO evidenced by increased mRNA expression of tight junction components, antimicrobial defenses and mucus barrier components. HF + FO-fed mice exhibited improvements in homeostatic model assessment of insulin resistance, oral glucose tolerance and serum adipokine concentrations and epididymal mRNA expression (increased adiponectin and decreased leptin) versus HF. HF + FO improved obese intestinal health and attenuated metabolic dysfunction associated with obesity.

Cooked Red Lentils Dose-Dependently Modulate the Colonic Microenvironment in Healthy C57Bl/6 Male Mice.

Dietary pulses, including lentils, are protein-rich plant foods that are enriched in intestinal health-promoting bioactives, such as non-digestible carbohydrates and phenolic compounds. The aim of this study was to investigate the effect of diets supplemented with cooked red lentils on the colonic microenvironment (microbiota composition and activity and epithelial barrier integrity and function). C57Bl/6 male mice were fed one of five diets: a control basal diet (BD), a BD-supplemented diet with 5, 10 or 20% cooked red lentils (by weight), or a BD-supplemented diet with 0.7% pectin (equivalent soluble fiber level as found in the 20% lentil diet). Red lentil supplementation resulted in increased: (1) fecal microbiota α-diversity; (2) abundance of short-chain fatty acid (SCFA)-producing bacteria (e.g., Prevotella, Roseburia and Dorea spp.); (3) concentrations of fecal SCFAs; (4) mRNA expression of SCFA receptors (G-protein-coupled receptors (GPR 41 and 43) and tight/adherens junction proteins (Zona Occulden-1 (ZO-1), Claudin-2, E-cadherin). Overall, 20% lentil had the greatest impact on colon health outcomes, which were in part explained by a change in the soluble and insoluble fiber profile of the diet. These results support recent public health recommendations to increase consumption of plant-based protein foods for improved health, in particular intestinal health.

Navy bean supplemented high-fat diet improves intestinal health, epithelial barrier integrity and critical aspects of the obese inflammatory phenotype.

Obesity is associated with impaired intestinal epithelial barrier function and an altered microbiota community structure, which contribute to host systemic inflammation and metabolic dysfunction. Fiber-rich common beans (Phaseolus vulgaris) promote intestinal health (microbiota and host epithelial barrier integrity) in lean mice. The objective was to assess the intestinal health promoting effects of navy bean supplementation during high-fat (HF)diet-induced obesity. Male C57BL/6 mice were fed either a high-fat (HF) diet (60% of kcal from fat) or an isocaloric HF diet supplemented with 15.7% (by weight) cooked navy bean powder (HF+B) for 12 weeks. Compared to HF, the HF+B diet altered the fecal microbiota community structure (16S rRNA gene sequencing), most notably increasing abundance of Akkermansia muciniphila (+19-fold), whose abundance typically decreases in obese humans and rodents. Additionally, HF+B fecal abundance of carbohydrate fermenting, short chain fatty acid (SCFA) producing Prevotella (+332-fold) and S24-7 (+1.6-fold) and fecal SCFA levels were increased. HF+B improved intestinal health and epithelial barrier integrity versus HF, evidenced by reduced serum fluorescein isothiocyanate (FITC)-dextran concentration in an in vivo gut permeability test, and increased intestinal mRNA expression of tight junction components (ZO-1, occludin), anti-microbial defenses (Reg3γ, IgA, Defα5, Defß2) and mucins (Muc2). Additionally, HF+B improved the systemic obese phenotype via reduced serum HOMA-IR and leptin:adiponectin ratio, and locally via attenuation of epididymal adipose tissue crown-like structure formation, adipocyte size, and inflammatory transcription factor (NFκBp65 and STAT3) activation. Therefore, navy bean supplementation improved obese intestinal health (microbiota and epithelial barrier integrity) and attenuated the severity of the obese phenotype.

Navy and black bean supplementation attenuates colitis-associated inflammation and colonic epithelial damage.

The enriched levels of nondigestible fermentable carbohydrates and phenolic compounds found in common beans can exert immunomodulatory effects within the colon that improve gut health and mitigate the severity of colitis-associated inflammatory pathology. Prior to acute colitis onset, C57Bl/6 mice were prefed isocaloric 20% cooked navy bean (NB) or black bean (BB) diets for 3 weeks and switched to control basal diet (BD) 24 h prior to colitis induction via 5-day exposure to dextran sodium sulfate (2% w/v in drinking water)+3 days of fresh water. The severity of the acute colitis phenotype was attenuated by bean prefeeding, evidenced by reduced colon tissue inflammatory transcription factor activation (NFκB, STAT3) and inflammatory mediator levels in the colon (IL-1ß, IL-6, IL-18 and MCP-1) and serum (TNFα, IL-6, IL-1ß, MCP-1) versus BD (P≤.05). Additionally, biomarkers of enhanced wound repair responses were increased by bean prefeeding including colon tissue protein levels of IL-22, IL-27 and activated (i.e., GTP-bound) Cdc42 and Rac1 versus BD (P≤.05). mRNA expressions of genes involved in normal colonic epithelial function and the promotion of epithelial barrier integrity, defense and/or restitution and wound closure including MUC1, RELMß, IgA and REG3γ were all increased in NB and BB prefed mice versus BD (P≤.05). Collectively, bean supplementation prior to colitis induction (i.e., mimicking disease relapse) primes the colonic microenvironment to attenuate the severity of the colitis inflammatory phenotype and maintain aspects of epithelial barrier function.

Chickpea supplementation prior to colitis onset reduces inflammation in dextran sodium sulfate-treated C57Bl/6 male mice.

The potential for a chickpea-supplemented diet (rich in fermentable nondigestible carbohydrates and phenolic compounds) to modify the colonic microenvironment and attenuate the severity of acute colonic inflammation was investigated. C57Bl/6 male mice were fed a control basal diet or basal diet supplemented with 20% cooked chickpea flour for 3 weeks prior to acute colitis onset induced by 7-day exposure to dextran sodium sulfate (DSS; 2% w/v in drinking water) and colon and serum levels of inflammatory mediators were assessed. Despite an equal degree of DSS-induced epithelial barrier histological damage and clinical symptoms between dietary groups, biomarkers of the ensuing inflammatory response were attenuated by chickpea pre-feeding, including reduced colon tissue activation of nuclear factor kappa B and inflammatory cytokine production (tumor necrosis factor alpha and interleukin (IL)-18). Additionally, colon protein expression of anti-inflammatory (IL-10) and epithelial repair (IL-22 and IL-27) cytokines were increased by chickpea pre-feeding. Furthermore, during acute colitis, chickpea pre-feeding increased markers of enhanced colonic function, including Relmß and IgA gene expression. Collectively, chickpea pre-feeding modulated the baseline function of the colonic microenvironment, whereby upon induction of acute colitis, the severity of the inflammatory response was attenuated.

Marine fish oil is more potent than plant-based n-3 polyunsaturated fatty acids in the prevention of mammary tumors.

Marine-derived n-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been shown to inhibit mammary carcinogenesis. However, evidence regarding plant-based α-linolenic acid (ALA), the major n-3 PUFA in the Western diet, remains equivocal. The objective of this study was to examine the effect of lifelong exposure to plant- or marine-derived n-3 PUFAs on pubertal mammary gland and tumor development in MMTV-neu(ndl)-YD5 mice. It is hypothesized that lifelong exposure to n-3 PUFA reduces terminal end buds during puberty leading to delayed tumor onset, volume and multiplicity. It is further hypothesized that plant-derived n-3 PUFAs will exert dose-dependent effects. Harems of MMTV-FVB males were bred with wild-type females and fed either a (1) 10% safflower (10% SF, n-6 PUFA, control), (2) 10% flaxseed (10% FS), (3) 7% safflower plus 3% flaxseed (3% FS) or (4) 7% safflower plus 3% menhaden (3% FO) diet. Female offspring were maintained on parental diets. Compared to SF, 10% FS and 3% FO reduced (P<.05) terminal end buds at 6 weeks and tumor volume and multiplicity at 20 weeks. A dose-dependent reduction of tumor volume and multiplicity was observed in mice fed 3% and 10% FS. Antitumorigenic effects were associated with altered HER2, pHER-2, pAkt and Ki-67 protein expression. Compared to 10% SF, 3% FO significantly down-regulated expression of genes involved in eicosanoid synthesis and inflammation. From this, it can be estimated that ALA was 1/8 as potent as EPA+DHA. Thus, marine-derived n-3 PUFAs have greater potency versus plant-based n-3 PUFAs.