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Gut microbiome diversity and community structure following dietary genistein treatment in a murine model of cystic fibrosis

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Introduction: Cystic fibrosis (CF) is the most common life-shortening autosomal recessive genetic disease affecting Caucasians. The disease is characterized by a dysfunctional cystic fibrosis transmembrane regulator (CFTR) protein and aberrant mucus accumulation that subsequently alters the physicochemical environment in numerous organ systems. These mucosal perturbations have been associated with inflammation…

Introduction: Cystic fibrosis (CF) is the most common life-shortening autosomal recessive genetic disease affecting Caucasians. The disease is characterized by a dysfunctional cystic fibrosis transmembrane regulator (CFTR) protein and aberrant mucus accumulation that subsequently alters the physicochemical environment in numerous organ systems. These mucosal perturbations have been associated with inflammation and microbial dysbiosis, most notably in the lungs and gastrointestinal (GI) tract. Genistein, a soy isoflavone and dietary polyphenol, has been shown to modulate CFTR function in cell cultures and murine models, as well exert sex-dependent improvement of survival rates in a CF mouse model. However, it is unknown whether dietary genistein affects gut microbiome diversity and community structure in cystic fibrosis. This study sought to examine associations between dietary genistein treatment and gut microbiome diversity and community structure in a murine model of CF. Methods: Twenty-four male and female mice homozygous for the DF508 CFTR gene mutation were maintained on one of three diet regimens for a 45-day period (n=11, standard chow; n=7, Colyte-treated water and standard chow; n=6, 600 mg dietary genistein per kg body weight). One fecal pellet was collected per mouse post-treatment, and microbial genomic DNA was extracted from the fecal samples, quantified, amplified, and sequenced on the Illumina MiSeq platform. QIIME 2 was used to conduct alpha- and beta-diversity analyses on all samples. Results: Measures of alpha-diversity were significantly decreased in the dietary genistein group as compared to either standard chow or Colyte groups. Measures of beta-diversity showed that community structure differed significantly between dietary treatment groups; these differences were further illustrated by distinct clustering of taxa as shown by principal coordinates analysis plots. Conclusion: This 3-arm parallel experimental study showed that dietary genistein treatment was associated with decreased microbial diversity and differences in microbial community structure in DF508 mice.

ContributorsArgo, Katy Bryana (Author) / Whisner, Corrie M (Thesis advisor) / Al-Nakkash, Layla (Committee member) / Sweazea, Karen L (Committee member) / Arizona State University (Publisher)

Created2019

Genistein-mediated diet tends to increase oxidative stress in the vasculature of female ob/ob mice

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Morbid obesity is associated with cardiovascular and metabolic disorders. A major contributor to the pathogenesis of these diseases is impaired vasodilation resulting from elevated reactive oxygen species (ROS). This is because certain ROS such as superoxide are raised with obesity and scavenge the endogenous vasorelaxant nitric oxide, resulting in hypertension.…

Morbid obesity is associated with cardiovascular and metabolic disorders. A major contributor to the pathogenesis of these diseases is impaired vasodilation resulting from elevated reactive oxygen species (ROS). This is because certain ROS such as superoxide are raised with obesity and scavenge the endogenous vasorelaxant nitric oxide, resulting in hypertension. The objective of this study was to measure the ability of genistein to quench superoxide in the vasculature of ob/ob mice, an animal model of obesity and type 2 diabetes. Genistein is an isoflavonic phytoestrogen naturally found in soy products. While genistein has documented antioxidant and anti-inflammatory properties, it is not known whether this protects the vasculature from oxidative stress. Genistein was hypothesized to reduce superoxide in arteries from female ob/ob mice. The superoxide indicator dihydroethidium (DHE) [2µL/mL HEPES buffer] was added to isolated aortae and mesenteric arteries from mice fed either a control (standard rodent chow containing 200-300 mg genistein/kg) or genistein-enriched (600mg genistein/kg rodent chow) diets for 4 weeks. Frozen tissues sections were collected onto glass microscope slides and examined using confocal microscopy. Contrary to the hypothesis, a diet containing twice the amount of genistein found in standard chow did not significantly reduce superoxide concentrations in aortae (p=0.287) or mesenteric arteries (p=0.352). Superoxide dismutase, an antioxidant enzyme that breaks down superoxide, was significantly upregulated in the genistein-enriched diet group (p=0.004), although this elevation did not promote the breakdown of superoxide. In addition, the inflammatory marker iNOS was not downregulated in the genistein-enriched diet group (p>0.05). The results indicate that high amounts of isoflavones, like genistein, may not exhibit the purported antioxidant effects in the vasculature of obese or diabetic subjects. Further studies examining arteries from ob/ob mice fed a genistein-free diet are needed to elucidate the true effects of genistein on oxidative stress.

ContributorsSimperova, Anna Marie (Co-author) / Al-Nakkash, Layla (Co-author) / Ricklefs, Kristin (Co-author) / Faust, James J. (Co-author) / Sweazea, Karen L. (Co-author) / Sweazea, Karen (Thesis director) / Gonzales, Rayna (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / T. Denny Sanford School of Social and Family Dynamics (Contributor)

Created2014-05

Systematic Review of the Impact of Genistein on Diabetes Related Outcomes

Description

As the 7th leading cause of death in the world, with over 1.6 millions deaths attributed to it in 2016 alone, diabetes mellitus has been a rising global health concern. Type 1 diabetes is caused by lack of insulin production whereas type 2 diabetes is caused by insulin resistance. Both…

As the 7th leading cause of death in the world, with over 1.6 millions deaths attributed to it in 2016 alone, diabetes mellitus has been a rising global health concern. Type 1 diabetes is caused by lack of insulin production whereas type 2 diabetes is caused by insulin resistance. Both types of diabetes lead to increased glucose levels in the body if left untreated. This, in turn, leads to the development of a host of complications, one of which is ischemic heart disease. Accounting for the death of 16% of the world’s population, ischemic heart disease has been the leading cause of death since 2000. As of 2019, deaths from this disease have risen from 2 million to over 8.9 million globally. While medicine exists to counter the negative outcomes of diabetes mellitus, lower income nations suffer from the lack of availability and high costs of these medications. Therefore, this systematic review was performed to determine whether a non-medicinal treatment could provide similar therapeutic benefits for individuals with diabetes. Genistein is a phytoestrogen found in soy-based products, which has been potentially linked with preventing diabetes and improving diabetes-related symptoms such as hyperglycemia and abnormal insulin levels. We searched PubMed and SCOPUS using the terms ‘genistein’, ‘diabetes’, and ‘glucose’ and identified 32 peer-reviewed articles. In general, preclinical studies demonstrate that genistein decreases body weight as well as circulating glucose and triglycerides concentrations while increasing insulin levels and insulin sensitivity. It also delayed the onset of type 1 and type 2 diabetes. In contrast, clinical studies of genistein in general reported no significant relationship between genistein and body mass, circulating glucose, serum insulin, A1C concentrations, or onset of type 1 diabetes. However, genistein was found to improve insulin sensitivity, delay type 2 diabetes onset and improve serum triglyceride levels. In summary, preclinical and clinical studies suggest that genistein may help delay onset of type 2 diabetes and improve several symptoms associated with the disease. By translating these findings into clinical settings, genistein may offer a cost effective natural approach at mitigating complications associated with diabetes, although additional research is required to confirm these findings.

ContributorsJain, Rijul (Author) / Sweazea, Karen (Thesis director) / Al-Nakkash, Layla (Committee member) / Bolch, Charlotte (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)

Created2021-04-16

Examining The Myosin Heavy Chain Distribution in Skeletal Muscle of High-Fat Diet Mice and the Effects of Exercise & Genistein

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According to the CDC, obesity has increased from 30.5% to 42.4% over the past 18 years. Western diets (WDs) consist of large portions in high fats, high carbohydrates, excess sugar and high-glycemic foods that can cause metabolic complications and mitochondrial dysfunction. Diet-induced obesity can lead to changes in muscle metabolism…

According to the CDC, obesity has increased from 30.5% to 42.4% over the past 18 years. Western diets (WDs) consist of large portions in high fats, high carbohydrates, excess sugar and high-glycemic foods that can cause metabolic complications and mitochondrial dysfunction. Diet-induced obesity can lead to changes in muscle metabolism and muscle fiber phenotypes, which in turn lead to metabolic complications. Muscle fiber phenotype is determined protein isoform-content of myosin heavy chain (MHC). Regular exercise alters mitochondrial content and fat oxidation and shifts MHC proportions under healthy circumstances. However, diet and exercise-driven fiber type shifts in diet-induced obesity are less understood. We designed our experiment to better understand the impact of diet and/ or exercise on fiber type content of gastrocnemius muscle in diet-induced obese mice. Exercise and genistein may be used as a treatment strategy to restore the MHC proportions in obese subjects to that of the lean subjects. We hypothesized that genistein and exercise would have the greatest MHC I change in muscle fiber phenotype of mouse gastrocnemius muscles. Further, we also hypothesized that a standard diet would reverse the expected increase in fast fiber phenotype (MHC IIb). Lastly, we also hypothesized that exercise would also reduce the abundance of MHC IIb. Gastrocnemius muscles were collected from mice, homogenized, run through gel electrophoresis and stained to give muscle fiber proportions. Paired sample t-tests were conducted for differences between the MHC isoforms compared to the lean (LN) and high-fat diet (HFD) control groups. The results showed that genistein and exercise significantly increased the abundance of MHC I muscle fibers (19%, p<0.05). Additionally, diet and exercise restored the muscle fiber phenotype to that of lean control. As expected, HFD obese mice exhibited elevated fast twitch fibers compared to only 3% slow twitch fibers. These findings show the potential for exercise and supplementation of genistein as a strategy to combat diet induced obesity. Future research should aim to understand the mechanisms that genistein acts on to make these changes, and aim to replicate these data in humans with obesity.

ContributorsSodhi, Harkaran (Author) / Katsanos, Christos (Thesis director) / Wang, Shu (Committee member) / Serrano, Nathan (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)

Created2022-05