Obesity, Metabolic Syndrome, and Musculoskeletal Disease: Common Inflammatory Pathways Suggest a Central Role for Loss of Muscle Integrity

Inflammation can arise in response to a variety of stimuli, including infectious agents, tissue injury, autoimmune diseases, and obesity. Some of these responses are acute and resolve, while others become chronic and exert a sustained impact on the host, systemically, or locally. Obesity is now recognized as a chronic low-grade, systemic inflammatory state that predisposes to other chronic conditions including metabolic syndrome (MetS). Although obesity has received considerable attention regarding its pathophysiological link to chronic cardiovascular conditions and type 2 diabetes, the musculoskeletal (MSK) complications (i.e., muscle, bone, tendon, and joints) that result from obesity-associated metabolic disturbances are less frequently interrogated. As musculoskeletal diseases can lead to the worsening of MetS, this underscores the imminent need to understand the cause and effect relations between the two, and the convergence between inflammatory pathways that contribute to MSK damage. Muscle mass is a key predictor of longevity in older adults, and obesity-induced sarcopenia is a significant risk factor for adverse health outcomes. Muscle is highly plastic, undergoes regular remodeling, and is responsible for the majority of total body glucose utilization, which when impaired leads to insulin resistance. Furthermore, impaired muscle integrity, defined as persistent muscle loss, intramuscular lipid accumulation, or connective tissue deposition, is a hallmark of metabolic dysfunction. In fact, many common inflammatory pathways have been implicated in the pathogenesis of the interrelated tissues of the musculoskeletal system (e.g., tendinopathy, osteoporosis, and osteoarthritis). Despite these similarities, these diseases are rarely evaluated in a comprehensive manner. The aim of this review is to summarize the common pathways that lead to musculoskeletal damage and disease that result from and contribute to MetS. We propose the overarching hypothesis that there is a central role for muscle damage with chronic exposure to an obesity-inducing diet. The inflammatory consequence of diet and muscle dysregulation can result in dysregulated tissue repair and an imbalance toward negative adaptation, resulting in regulatory failure and other musculoskeletal tissue damage. The commonalities support the conclusion that musculoskeletal pathology with MetS should be evaluated in a comprehensive and integrated manner to understand risk for other MSK-related conditions. Implications for conservative management strategies to regulate MetS are discussed, as are future research opportunities.

Neutralization of IL-15 abrogates experimental immune-mediated cholangitis in diet-induced obese mice

Obesity is a global epidemic affecting chronic inflammatory diseases. Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease that can occur as an extraintestinal manifestation of inflammatory bowel disease (IBD). Previously we reported that patients with PSC who are obese have a higher risk of advanced liver disease. Currently it is unknown how obesity accelerates or worsens PSC. We evaluated the progression of PSC in an antigen-driven cholangitis mouse model of diet-induced obesity. Obesity was induced in our murine model of immune-mediated cholangitis (OVAbil). OVAbil mice were fed standard chow or high-fat/sucrose diet for twelve weeks followed by induction of biliary inflammation by OVA-specific T cell transfer. Histopathological damage in portal tracts was scored and serum collected. Neutralizing antibodies against IL-15 were administered daily until study termination. Obese mice developed exacerbated liver inflammation and damage. Immune cell phenotyping in liver revealed greater numbers of neutrophils and CD8+ T cells in obese mice. Higher levels of cytokines and chemokines were found in obese mice with cholangitis. Immuno-neutralizing antibodies against IL-15 greatly attenuated cholangitis in obese mice. Obesity exacerbated experimental PSC in part by overproduction of IL-15. Timely targeting of IL-15 may slow the progression of PSC.

Potential Impact of Metabolic and Gut Microbial Response to Pregnancy and Lactation in Lean and Diet-Induced Obese Rats on Offspring Obesity Risk

SCOPE

Maternal obesity programs metabolic dysfunction in offspring, increasing their susceptibility to obesity and metabolic diseases in later life. Moreover, pregnancy and lactation are associated with many metabolic adaptations, yet it is unclear how diet-induced maternal obesity may interrupt these processes.

METHODS AND RESULTS

¹ H NMR serum metabolomics analysis was performed on samples collected pre-pregnancy and in pregnant and lactating lean and high fat/sucrose (HFS) diet-induced obese Sprague-Dawley rats to identify maternal metabolic pathways associated with developmental programming of offspring obesity. Gut microbial composition was assessed using qPCR. Offspring of HFS dams had nearly 40% higher adiposity at weaning compared to offspring of lean dams. While pregnancy and lactation were associated with distinct maternal metabolic changes common to both lean and obese dams, we identified several metabolic differences, potentially implicating dysregulated one-carbon and mammary gland metabolism in the metabolic programming of obesity. Gut microbial composition was significantly altered with obesity, and both gestation and lactation were accompanied by changes in gut microbiota.

CONCLUSION

Diet-induced maternal obesity and consumption of an obesogenic maternal diet results in differential metabolic and gut microbial adaptations to pregnancy and lactation; these maladaptations may be directly involved in maternal programming of offspring susceptibility to obesity.

Near-infrared spectroscopy can detect differences in vascular responsiveness to a hyperglycaemic challenge in individuals with obesity compared to normal-weight individuals

OBJECTIVE

To examine whether the near-infrared spectroscopy combined with vascular occlusion test technique could detect differences in vascular responsiveness during hyperglycaemia between normal-weight individuals and individuals with obesity.

METHODS

A total of 16 normal-weight individuals (body mass index, 21.3 ± 1.7 kg/m²) and 13 individuals with obesity (body mass index, 34.4 ± 2.0 kg/m²) were submitted to five vascular occlusion tests (Pre, 30, 60, 90 and 120 min after glucose challenge). Vascular responsiveness was determined by the Slope 2 (Slope 2 StO₂) and the area under the curve (StO_2AUC) of oxygen saturation derived from near-infrared spectroscopy-vascular occlusion test.

RESULTS

The Slope 2 StO₂ increased from 1.07 ± 0.16%/s (Pre) to 1.53 ± 0.21%/s at 90 min ( p < 0.05) in the control group, while in obese it increased from 0.71 ± 0.09%/s (Pre) to 0.92 ± 0.14%/s at 60 min ( p < 0.05), and to 0.97 ± 0.10%/s ( p < 0.01) at 120 min after glucose ingestion. The StO_2AUC decreased from 1729 ± 214% . sec (Pre) to 1259 ± 232% . sec at 60 min ( p < 0.05) and to 1034 ± 172% . sec at 90 min ( p < 0.05) in the normal-weight group, whereas it decreased at 90 min (637 ± 98% . sec; p < 0.05) and at 120 min (590 ± 93% . sec; p < 0.01) compared to 30 min (1232 ± 197% . sec) after glucose ingestion in individuals with obesity.

CONCLUSION

Near-infrared spectroscopy-vascular occlusion test technique was capable of detecting differences in vascular responsiveness during hyperglycaemia between normal-weight individuals and individuals with obesity.

Metabolic inflexibility in individuals with obesity assessed by near-infrared spectroscopy

OBJECTIVE

To non-invasively evaluate differences in oxidative metabolism in individuals with obesity compared to normal weight using the near-infrared spectroscopy and vascular occlusion technique during hyperglycaemia.

METHODS

In all, 16 normal-weight individuals (body mass index: 21.3 ± 1.7 kg/m²) and 13 individuals with obesity (body mass index: 34.4 ± 2.0 kg/m²) had five vascular occlusion tests (pre, 30, 60, 90 and 120 min after glucose ingestion). Oxygen utilization was estimated from the area under the curve of the deoxyhemoglobin [HHb] signal during occlusion. Muscle reperfusion was derived from the area above the curve after cuff release.

RESULTS

The deoxyhemoglobin area under the curve during occlusion of the normal-weight individuals increased from 15,732 ± 2344 (% . s) at pre to 18,930 ± 3226 (% . s) ( p < 0.05) at 90 min after glucose ingestion. The deoxyhemoglobin area under the curve during occlusion decreased significantly from 14,695 ± 3341 (% . s) at pre to 11,273 ± 1825 (% . s) ( p < 0.05) and 11,360 ± 1750 (% . s) ( p < 0.05) at 30 and 60 min, respectively, after glucose ingestion. The area above the curve of deoxyhemoglobin during reperfusion decreased significantly from 6450 ± 765 (% . s) at pre to 4830 ± 963 (% . s) ( p < 0.05) at 60 min and to 4210 ± 595 (% . s) ( p < 0.01) at 90 min in normal-weight individuals after glucose ingestion, with no changes observed in individuals with obesity.

CONCLUSION

This study confirmed in vivo and non-invasively the metabolic inflexibility of skeletal muscle in individuals with obesity during hyperglycaemia.

Dairy Attenuates Weight Gain to a Similar Extent as Exercise in Rats Fed a High-Fat, High-Sugar Diet

OBJECTIVE

To compare the individual and combined effects of dairy and endurance exercise training in reducing weight gain and adiposity in a rodent model of diet-induced obesity.

METHODS

An 8-week feeding intervention of a high-fat, high-sugar diet was used to induce obesity in male Sprague-Dawley rats. Rats were then assigned to one of four groups for 6 weeks: (1) casein sedentary (casein-S), (2) casein exercise (casein-E), (3) dairy sedentary (dairy-S), and (4) dairy exercise (dairy-E). Rats were exercise trained by treadmill running 5 d/wk.

RESULTS

Dairy-E prevented weight gain to a greater extent than either dairy or exercise alone. Adipose tissue and liver mass were reduced to a similar extent in dairy-S, casein-E, and dairy-E groups. Differences in weight gain were not explained by food intake or total energy expenditure. The total amount of lipid excreted was greater in the dairy-S compared to casein-S and dairy-E groups.

CONCLUSIONS

This study provides evidence that dairy limits weight gain to a similar extent as exercise training and the combined effects are greater than either intervention alone. While exercise training reduces weight gain through increases in energy expenditure, dairy appears to increase lipid excretion in the feces.

Prebiotics Reduce Body Fat and Alter Intestinal Microbiota in Children Who Are Overweight or With Obesity

BACKGROUND & AIMS

It might be possible to manipulate the intestinal microbiota with prebiotics or other agents to prevent or treat obesity. However, little is known about the ability of prebiotics to specifically modify gut microbiota in children with overweight/obesity or reduce body weight. We performed a randomized controlled trial to study the effects of prebiotics on body composition, markers of inflammation, bile acids in fecal samples, and composition of the intestinal microbiota in children with overweight or obesity.

METHODS

We performed a single-center, double-blind, placebo-controlled trial of 2 separate cohorts (March 2014 and August 2014) at the University of Calgary in Canada. Participants included children, 7-12 years old, with overweight or obesity (>85th percentile of body mass index) but otherwise healthy. Participants were randomly assigned to groups given either oligofructose-enriched inulin (OI; 8 g/day; n=22) or maltodextrin placebo (isocaloric dose, controls; n=20) once daily for 16 weeks. Fat mass and lean mass were measured using dual-energy-x-ray absorptiometry. Height, weight, and waist circumference were measured at baseline and every 4 weeks thereafter. Blood samples were collected at baseline and 16 weeks, and analyzed for lipids, cytokines, lipopolysaccharide, and insulin. Fecal samples were collected at baseline and 16 weeks; bile acids were profiled using high-performance liquid chromatography and the composition of the microbiota was analyzed by 16S rRNA sequencing and quantitative polymerase chain reaction. The primary outcome was change in percent body fat from baseline to 16 weeks.

RESULTS

After 16 weeks, children who consumed OI had significant decreases in body weight z-score (decrease of 3.1%), percent body fat (decrease of 2.4%), and percent trunk fat (decrease of 3.8%) compared with children given placebo (increase of 0.5%, increase of 0.05%, and decrease of 0.3%, respectively). Children who consumed OI also had a significant reduction in level of interleukin 6 from baseline (decrease of 15%) compared with the placebo group (increase of 25%). There was a significant decrease in serum triglycerides (decrease of 19%) in the OI group. Quantitative polymerase chain reaction showed a significant increase in Bifidobacterium spp. in the OI group compared with controls. 16S rRNA sequencing revealed significant increases in species of the genus Bifidobacterium and decreases in Bacteroides vulgatus within the group who consumed OI. In fecal samples, levels of primary bile acids increased in the placebo group but not in the OI group over the 16-week study period.

CONCLUSIONS

In a placebo-controlled, randomized trial, we found a prebiotic (OI) to selectively alter the intestinal microbiota and significantly reduce body weight z-score, percent body fat, percent trunk fat, and serum level of interleukin 6 in children with overweight or obesity (Clinicaltrials.gov no: NCT02125955).

Inulin-type fructans and whey protein both modulate appetite but only fructans alter gut microbiota in adults with overweight/obesity: A randomized controlled trial

SCOPE

Independently, prebiotics and dietary protein have been shown to improve weight loss and/or alter appetite. Our objective was to determine the effect of combined prebiotic and whey protein on appetite, body composition and gut microbiota in adults with overweight/obesity.

METHODS AND RESULTS

In a 12 week, placebo-controlled, double-blind study, 125 adults with overweight/obesity were randomly assigned to receive isocaloric snack bars of: (1) Control; (2) Inulin-type fructans (ITF); (3) Whey protein; (4) ITF + Whey protein. Appetite, body composition and gut microbiota composition/genetic potential were assessed. Compared to Control, body fat was significantly reduced in the Whey protein group at 12 wks. Hunger, desire to eat and prospective food consumption were all lower with ITF, Whey protein and ITF + Whey protein compared to Control at 12 wks. Microbial community structure differed from 0 to 12 wks in the ITF and ITF +Whey Protein groups (i.e. increased Bifidobacterium) but not Whey Protein or Control. Changes in microbial genetic potential were seen between Control and ITF-containing treatments.

CONCLUSION

Adding ITF, whey protein or both to snack bars improved several aspects of appetite control. Changes in gut microbiota may explain in part the effects of ITF but likely not whey protein.

Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics

In December 2016, a panel of experts in microbiology, nutrition and clinical research was convened by the International Scientific Association for Probiotics and Prebiotics to review the definition and scope of prebiotics. Consistent with the original embodiment of prebiotics, but aware of the latest scientific and clinical developments, the panel updated the definition of a prebiotic: a substrate that is selectively utilized by host microorganisms conferring a health benefit. This definition expands the concept of prebiotics to possibly include non-carbohydrate substances, applications to body sites other than the gastrointestinal tract, and diverse categories other than food. The requirement for selective microbiota-mediated mechanisms was retained. Beneficial health effects must be documented for a substance to be considered a prebiotic. The consensus definition applies also to prebiotics for use by animals, in which microbiota-focused strategies to maintain health and prevent disease is as relevant as for humans. Ultimately, the goal of this Consensus Statement is to engender appropriate use of the term 'prebiotic' by relevant stakeholders so that consistency and clarity can be achieved in research reports, product marketing and regulatory oversight of the category. To this end, we have reviewed several aspects of prebiotic science including its development, health benefits and legislation.

Prebiotics as a modulator of gut microbiota in paediatric obesity

This review highlights our current understanding of the role of gut microbiota in paediatric obesity and the potential role for dietary manipulation of the gut microbiota with prebiotics in managing paediatric obesity. The aetiology of obesity is multifactorial and is now known to include microbial dysbiosis in the gut. Prebiotics are non-digestible carbohydrates which selectively modulate the number and/or composition of gut microbes. The goal of prebiotic consumption is to restore symbiosis and thereby confer health benefits to the host. There is convincing evidence that prebiotics can reduce adiposity and improve metabolic health in preclinical rodent models. Furthermore, there are several clinical trials in adult humans highlighting metabolic and appetite-regulating benefits of prebiotics. In paediatric obesity, however, there are very limited data regarding the potential role of prebiotics as a dietary intervention for obesity management. As the prevalence of paediatric obesity and obesity-associated comorbidities increases globally, interventions that target the progression of obesity from an early age are essential in slowing the obesity epidemic. This review emphasizes the need for further research assessing the role of prebiotics, particularly as an intervention in effectively managing paediatric obesity.

Prebiotic supplementation improves appetite control in children with overweight and obesity: a randomized controlled trial

Background: Prebiotics have been shown to improve satiety in adults with overweight and obesity; however, studies in children are limited.Objective: We examined the effects of prebiotic supplementation on appetite control and energy intake in children with overweight and obesity.Design: This study was a randomized, double-blind, placebo-controlled trial. Forty-two boys and girls, ages 7-12 y, with a body mass index (BMI) of ≥85th percentile were randomly assigned to 8 g oligofructose-enriched inulin/d or placebo (maltodextrin) for 16 wk. Objective measures of appetite included energy intake at an ad libitum breakfast buffet, 3-d food records, and fasting satiety hormone concentrations. Subjective appetite ratings were obtained from visual analog scales before and after the breakfast. Children's Eating Behavior Questionnaires were also completed by caregivers.Results: Compared with placebo, prebiotic intake resulted in significantly higher feelings of fullness (P = 0.04) and lower prospective food consumption (P = 0.03) at the breakfast buffet at 16 wk compared with baseline. Compared with placebo, prebiotic supplementation significantly reduced energy intake at the week 16 breakfast buffet in 11- and 12-y-olds (P = 0.04) but not in 7- to 10-y-olds. Fasting adiponectin (P = 0.04) and ghrelin (P = 0.03) increased at 16 wk with the prebiotic compared with placebo. In intent-to-treat analysis, there was a trend for prebiotic supplementation to reduce BMI z score to a greater extent than placebo (-3.4%; P = 0.09) and a significant -3.8% reduction in per-protocol analysis (P = 0.043).Conclusions: Independent of other lifestyle changes, prebiotic supplementation in children with overweight and obesity improved subjective appetite ratings. This translated into reduced energy intake in a breakfast buffet in older but not in younger children. This simple dietary change has the potential to help with appetite regulation in children with obesity. This trial was registered at clinicaltrials.gov as NCT02125955.

Association of body mass index (BMI) and percent body fat among BMI-defined non-obese middle-aged individuals: Insights from a population-based Canadian sample

OBJECTIVES

To evaluate the association between percent body fat (%BF) and body mass index (BMI) among BMI-defined non-obese individuals between 40 and 69 years of age using a population-based Canadian sample.

DATA AND METHODS

Cross-sectional data from the Canadian Health Measures Survey (2007 and 2009) was used to select all middle-aged individuals with BMI &lt; 30 kg/m2 (n = 2,656). %BF was determined from anthropometric skinfolds and categorized according to sex-specific equations. Association of other anthropometry measures and metabolic markers were evaluated across different %BF categories. Significance of proportions was evaluated using chi-squared and Bonferroni-adjusted Wald test. Diagnostic performance measures of BMI-defined overweight categories compared to those defined by %BF were reported.

RESULTS

The majority (69%) of the sample was %BF-defined overweight/obese, while 55% were BMI-defined overweight. BMI category was not concordant with %BF classification for 30% of the population. The greatest discordance between %BF and BMI was observed among %BF-defined overweight/obese women (32%). Sensitivity and specificity of BMI-defined overweight compared to %BF-defined overweight/obese were (58%, 94%) among females and (82%, 59%) among males respectively. According to the estimated negative predictive value, if an individual is categorized as BMI-defined non-obese, he/she has a 52% chance of being in the %BF-defined overweight/obese category.

CONCLUSION

Middle-aged individuals classified as normal by BMI may be overweight/obese based on measures of %BF. These individuals may be at risk for chronic diseases, but would not be identified as such based on their BMI classification. Quantifying %BF in this group could inform targeted strategies for disease prevention.

Oligofructose decreases serum lipopolysaccharide and plasminogen activator inhibitor-1 in adults with overweight/obesity

OBJECTIVE

To determine the effect of prebiotic supplementation on metabolic endotoxemia and systemic inflammation in adults with overweight and obesity.

METHODS

Samples from a previously conducted randomized, double-blind, placebo-controlled trial were used for analysis. Participants were randomized to 21 g of oligofructose (n = 20; BMI 30.4 kg/m² ) or a maltodextrin placebo (n = 17; BMI 29.5 kg/m² ) for 12 weeks. A total of 37 participants had samples available for the current analysis. Resistin, adiponectin, plasminogen activator inhibitor-1 (PAI-1), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and macrophage chemoattractant protein-1 (MCP-1) were quantified using MILLIPLEX® assays. Lipopolysaccharide (LPS) was measured using PyroGene™ Recombinant Factor C Assay.

RESULTS

Plasma LPS concentrations were reduced by 40% in the oligofructose group over 12 weeks compared to a 48% increase in the placebo group (P = 0.04). PAI-1, a risk factor for thrombosis, was reduced to a greater extent in the oligofructose group (-17.3 ± 2.6 ng/ml) compared to the placebo group (-9.7 ± 1.8 ng/ml; P = 0.03). Oligofructose did not affect IL-6, TNF-α, MCP-1, adiponectin, or resistin.

CONCLUSIONS

Oligofructose reduces metabolic endotoxemia and PAI-1. Incorporating prebiotics into the diet through supplements or functional foods may help mitigate some markers of obesity-associated inflammation.

Dietary Intake and Associated Body Weight in Canadian Undergraduate Students Enrolled in Nutrition Education

The primary purpose of this study was to describe dietary intakes among Canadian undergraduate students enrolled in an Introductory Nutrition course. A secondary objective was to determine food group servings associated with meeting more Dietary Reference Intakes (DRIs) of select nutrients and with a lower body mass index (BMI). Participants (n = 124, 20.7±3.2yrs) provided output from a 3-day dietary record and completed a physical activity/demographics questionnaire. Linear regression showed that the dietary intake associated with meeting the most DRIs included vegetables, fruits, protein foods, and dairy (p = 0.001). Protein foods were a positive predictor and fruit a negative predictor of BMI (p = 0.001 and p = 0.023 respectively). Males consumed more grains (p = 0.001), dairy (p = 0.04), protein foods (p < 0.001), empty calories (p = 0.007) and total calories than females (p < 0.001). A diet characterized by greater intake of vegetables, fruits, protein foods, and dairy was associated with a Canadian undergraduate population meeting the greatest number of nutrient requirements.

Consuming yellow pea fiber reduces voluntary energy intake and body fat in overweight/obese adults in a 12-week randomized controlled trial

BACKGROUND & AIMS

The purpose of this randomized, double-blind, placebo-controlled study was to assess the effects of yellow pea fiber intake on body composition and metabolic markers in overweight/obese adults.

METHODS

Participants (9 M/41 F; age 44 ± 15 y, BMI 32.9 ± 5.9 kg/m2) received isocaloric doses of placebo (PL) or pea fiber (PF; 15 g/d) wafers for 12 weeks. Outcome measures included changes in anthropometrics, body composition (DXA), oral glucose tolerance test (OGTT), food intake (ad libitum lunch buffet), and biochemical indices.

RESULTS

The PF group lost 0.87 ± 0.37 kg of body weight, primarily due to body fat (-0.74 ± 0.26 kg), whereas PL subjects gained 0.40 ± 0.39 kg of weight over the 12 weeks (P = 0.022). The PF group consumed 16% less energy at the follow-up lunch buffet (P = 0.026), whereas the PL group did not change. During the OGTT, glucose area under the curve (AUC) was lower in PF subjects at follow-up (P = 0.029); insulin increased in both groups over time (P = 0.008), but more so in the PL group (38% higher AUC vs. 10% higher in the PF group). There were no differences in gut microbiota between groups.

CONCLUSIONS

In the absence of other lifestyle changes, incorporating 15 g/day yellow pea fiber may yield small but significant metabolic benefits and aid in obesity management. Clinical Trial Registry: ClinicalTrials.gov NCT01719900.

Preconception Prebiotic and Sitagliptin Treatment in Obese Rats Affects Pregnancy Outcomes and Offspring Microbiota, Adiposity, and Glycemia

Maternal obesity is associated with increased risk of pregnancy complications and greater risk of obesity in offspring, but studies designed to examine preconception weight loss are limited. The objective of this study was to determine if a combined dietary [oligofructose (OFS)] and pharmacological (sitagliptin) preconception intervention could mitigate poor pregnancy outcomes associated with maternal obesity and improve offspring metabolic health and gut microbiota composition. Diet-induced obese female Sprague-Dawley rats were randomized to one of four intervention groups for 8 weeks: (1) Obese-Control (consumed control diet during intervention); (2) Obese-OFS (10% OFS diet); (3) Obese-S (sitagliptin drug); (4) Obese-OFS + S (combination treatment). Two reference groups were also included: (5) Obese-HFS (untreated obese consumed high fat/sucrose diet throughout study); (6) Lean-Control (lean reference group that were never obese and consumed control diet throughout). Offspring consumed control diet until 11 weeks of age followed by HFS diet until 17 weeks of age. The Obese-OFS + S rats lost weight during the intervention phase whereas the OFS and S treatments attenuated weight gain compared with Obese-HFS (p < 0.05). Gestational weight gain was lowest in Obese-OFS + S rats and highest in Obese-HFS rats (p < 0.05). Prepregnancy intervention did not affect reproductive parameters but did affect pregnancy outcomes including litter size. Male Obese-OFS offspring had significantly lower percent body fat than Obese-HFS at 17 weeks. Female Obese-S and Obese-OFS offspring had significantly lower fasting glucose at 17 weeks compared with Obese-Control and Obese-HFS. Clostridium cluster XI was higher in Obese-HFS and Obese-S dams at birth compared with all other groups. Dams with an adverse pregnancy outcome had significantly lower (p = 0.035) Lactobacillus spp. compared with dams with normal or small litters. At weaning, male offspring of Obese-HFS had higher levels of Methanobrevibacter than all other groups except Obese-S and female Obese-HFS offspring had higher Enterobacteriaceae compared with all other groups. At 11 and 17 weeks of age, Bacteroides/Prevotella spp. was significantly lower in male and female offspring of Obese-HFS dams compared with all other groups except Obese-OFS + S. Modest weight loss induced with a diet-drug combination did not affect maternal fecundity but did have sex-specific effects on offspring adiposity and glycemia that may be linked to changes in offspring microbiota.

High-fat high-sucrose diet leads to dynamic structural and inflammatory alterations in the rat vastus lateralis muscle

The influence of obesity on muscle integrity is not well understood. The purpose of this study was to quantify structural and molecular changes in the rat vastus lateralis (VL) muscle as a function of a 12-week obesity induction period and a subsequent adaptation period (additional 16-weeks). Male Sprague-Dawley rats consumed a high-fat, high-sucrose (DIO, n = 40) diet, or a chow control-diet (n = 14). At 12-weeks, DIO rats were grouped as prone (DIO-P, top 33% of weight change) or resistant (DIO-R, bottom 33%). Animals were euthanized at 12- or 28-weeks on the diet. At sacrifice, body composition was determined and VL muscles were collected. Intramuscular fat, fibrosis, and CD68+ cells were quantified histologically and relevant molecular markers were evaluated using RT-qPCR. At 12- and 28-weeks post-obesity induction, DIO-P rats had more mass and body fat than DIO-R and chow rats (p < 0.05). DIO-P and DIO-R rats had similar losses in muscle mass, which were greater than those in chow rats (p < 0.05). mRNA levels for MAFbx/atrogin-1 were reduced in DIO-P and DIO-R rats at 12- and 28-weeks compared to chow rats (p < 0.05), while expression of MuRF1 was similar to chow values. DIO-P rats demonstrated increased mRNA levels for pro-inflammatory mediators, inflammatory cells, and fibrosis compared to DIO-R and chow animals, despite having similar levels of intramuscular fat. The down-regulation of MAFbx/atrogin-1 may suggest onset of degenerative changes in VL muscle integrity of obese rats. DIO-R animals exhibited fewer inflammatory changes compared to DIO-P animals, suggesting a protective effect of obesity resistance on local inflammation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2069-2078, 2016.

Oligofructose as an adjunct in treatment of diabetes in NOD mice

In type 1 diabetes, restoration of normoglycemia can be achieved if the autoimmune attack on beta cells ceases and insulin requirement is met by the residual beta cells. We hypothesize that an adjunctive therapy that reduces insulin demand by increasing insulin sensitivity will improve the efficacy of an immunotherapy in reversing diabetes. We tested the gut microbiota-modulating prebiotic, oligofructose (OFS), as the adjunctive therapy. We treated non-obese diabetic mice with an immunotherapy, monoclonal anti-CD3 antibody (aCD3), with or without concurrent dietary supplement of OFS. After 8 weeks of OFS supplement, the group that received both aCD3 and OFS (aCD3 + OFS) had a higher diabetes remission rate than the group that received aCD3 alone. The aCD3 + OFS group had higher insulin sensitivity accompanied by reduced lymphocytic infiltrate into the pancreatic islets, higher beta-cell proliferation rate, higher pancreatic insulin content, and secreted more insulin in response to glucose. The addition of OFS also caused a change in gut microbiota, with a higher level of Bifidobacterium and lower Clostridium leptum. Hence, our results suggest that OFS can potentially be an effective therapeutic adjunct in the treatment of type 1 diabetes by improving insulin sensitivity and beta-cell function, leading to improved glycemic control.

Reduced knee adduction moments for management of knee osteoarthritis:: A three month phase I/II randomized controlled trial

Wedged insoles are believed to be of clinical benefit to individuals with knee osteoarthritis by reducing the knee adduction moment (KAM) during gait. However, previous clinical trials have not specifically controlled for KAM reduction at baseline, thus it is unknown if reduced KAMs actually confer a clinical benefit. Forty-eight participants with medial knee osteoarthritis were randomly assigned to either a control group where no footwear intervention was given, or a wedged insole group where KAM reduction was confirmed at baseline. KAMs, Knee Injury and Osteoarthritis Outcome Score (KOOS) and Physical Activity Scale for the Elderly (PASE) scores were measured at baseline. KOOS and PASE surveys were re-administered at three months follow-up. The wedged insole group did not experience a statistically significant or clinically meaningful change in KOOS pain over three months (p=0.173). Furthermore, there was no association between change in KAM magnitude and change in KOOS pain over three months within the wedged insole group (R²=0.02, p=0.595). Improvement in KOOS pain for the wedged insole group was associated with worse baseline pain, and a change in PASE score over the three month study (R²=0.57, p=0.007). As an exploratory comparison, there was no significant difference in change in KOOS pain (p=0.49) between the insole and control group over three months. These results suggest that reduced KAMs do not appear to provide any clinical benefit compared to no intervention over a follow-up period of three months. ClinicalTrials.gov ID Number: NCT02067208.

Ketogenic diet modifies the gut microbiota in a murine model of autism spectrum disorder

Background

Gastrointestinal dysfunction and gut microbial composition disturbances have been widely reported in autism spectrum disorder (ASD). This study examines whether gut microbiome disturbances are present in the BTBR^T + tf/j (BTBR) mouse model of ASD and if the ketogenic diet, a diet previously shown to elicit therapeutic benefit in this mouse model, is capable of altering the profile.

Findings

Juvenile male C57BL/6 (B6) and BTBR mice were fed a standard chow (CH, 13 % kcal fat) or ketogenic diet (KD, 75 % kcal fat) for 10–14 days. Following diets, fecal and cecal samples were collected for analysis. Main findings are as follows: (1) gut microbiota compositions of cecal and fecal samples were altered in BTBR compared to control mice, indicating that this model may be of utility in understanding gut-brain interactions in ASD; (2) KD consumption caused an anti-microbial-like effect by significantly decreasing total host bacterial abundance in cecal and fecal matter; (3) specific to BTBR animals, the KD counteracted the common ASD phenotype of a low Firmicutes to Bacteroidetes ratio in both sample types; and (4) the KD reversed elevated Akkermansia muciniphila content in the cecal and fecal matter of BTBR animals.

Conclusions

Results indicate that consumption of a KD likely triggers reductions in total gut microbial counts and compositional remodeling in the BTBR mouse. These findings may explain, in part, the ability of a KD to mitigate some of the neurological symptoms associated with ASD in an animal model.

Electronic supplementary material

The online version of this article (doi:10.1186/s13229-016-0099-3) contains supplementary material, which is available to authorized users.

Response to diet-induced obesity produces time-dependent induction and progression of metabolic osteoarthritis in rat knees

Obesity, and corresponding chronic-low grade inflammation, is associated with the onset and progression of knee OA. The origin of this inflammation is poorly understood. Here, the effect of high fat, high sucrose (HFS) diet induced obesity (DIO) on local (synovial fluid), and systemic (serum) inflammation is evaluated after a 12-week obesity induction and a further 16-week adaptation period. For 12-weeks of obesity induction, n = 40 DIO male Sprague-Dawley rats consumed a HFS diet while the control group (n = 14) remained on chow. DIO rats were allocated to prone (DIO-P, top 33% based on weight change) or resistant (DIO-R, bottom 33%) groups at 12-weeks. Animals were euthanized at 12- and after an additional 16-weeks on diet (28-weeks). At sacrifice, body composition and knee joints were collected and assessed. Synovial fluid and sera were profiled using cytokine array analysis. At 12-weeks, DIO-P animals demonstrated increased Modified Mankin scores compared to DIO-R and chow (p = 0.026), and DIO-R had higher Mankin scores compared to chow (p = 0.049). While numerous systemic and limited synovial fluid inflammatory markers were increased at 12-weeks in DIO animals compared to chow, by 28-weeks there were limited systemic differences but marked increases in local synovial fluid inflammatory marker concentrations. Metabolic OA may manifest from an initial systemic inflammatory disturbance. Twelve weeks of obesity induction leads to a unique inflammatory profile and induction of metabolic OA which is altered after a further 16-weeks of obesity and HFS diet intake, suggesting that obesity is a dynamic, progressive process. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1010-1018, 2016.

Reshaping the gut microbiota: Impact of low calorie sweeteners and the link to insulin resistance?

Disruption in the gut microbiota is now recognized as an active contributor towards the development of obesity and insulin resistance. This review considers one class of dietary additives known to influence the gut microbiota that may predispose susceptible individuals to insulin resistance - the regular, long-term consumption of low-dose, low calorie sweeteners. While the data are controversial, mounting evidence suggests that low calorie sweeteners should not be dismissed as inert in the gut environment. Sucralose, aspartame and saccharin, all widely used to reduce energy content in foods and beverages to promote satiety and encourage weight loss, have been shown to disrupt the balance and diversity of gut microbiota. Fecal transplant experiments, wherein microbiota from low calorie sweetener consuming hosts are transferred into germ-free mice, show that this disruption is transferable and results in impaired glucose tolerance, a well-known risk factor towards the development of a number of metabolic disease states. As our understanding of the importance of the gut microbiota in metabolic health continues to grow, it will be increasingly important to consider the impact of all dietary components, including low calorie sweeteners, on gut microbiota and metabolic health.

Improvement in adiposity with oligofructose is modified by antibiotics in obese rats

Given the intimate link between gut microbiota and host physiology, there is growing interest in understanding the mechanisms by which diet influences gut microbiota and affects human metabolic health. Using antibiotics and the prebiotic oligofructose, which has been shown to counteract excess fat mass, we explored the gut microbiota-dependent effects of oligofructose on body composition and host metabolism. Diet-induced obese male Sprague Dawley rats, fed a background high-fat/sucrose diet, were randomized to one of the following diets for 6 wk: 1) high-energy control; 2) 10% oligofructose; 3) ampicillin; 4) ampicillin + 10% oligofructose; 5) ampicillin/neomycin; or 6) ampicillin/neomycin + 10% oligofructose. Combining oligofructose with ampicillin treatment blunted the decrease in adiposity seen with oligofructose. Although ampicillin did not affect total bacteria, ampicillin impeded oligofructose-induced increases in Bifidobacterium and Lactobacillus In contrast, the combination of ampicillin and neomycin reduced total bacteria but did not abrogate the oligofructose-induced decrease in adiposity. Oligofructose-mediated effects on host adiposity and metabolic health appear to be in part dependent on the presence of specific microbial species within the gut.-Bomhof, M. R., Paul, H. A., Geuking, M. B., Eller, L. K., Reimer, R. A. Improvement in adiposity with oligofructose is modified by antibiotics in obese rats.