Browsing by Subject "Dysbiosis"

Now showing 1 - 5 of 5
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    FRI009 Microbiome Affects Host Metabolic Homeostasis Via Differential Regulation Of Gene Expression In The Endocrine System
    (The Endocrine Society, 2023-10-05) Milhouse, Wynne; Ren, Hongxia; Pediatrics, School of Medicine
    Dysbiosis has been implicated in many metabolic disorders, but the exact role of microbiota is not completely understood. To address this question, we used germ-free (GF) and conventional (CON) mouse models to examine the expression of genes critical for endocrine regulation of metabolic homeostasis. Samples of the mediobasal hypothalamus (MBH) were obtained from 18 germ-free and 18 conventional C57BL/6 mice (n=9 males, 9 females). Each gene transcript was quantified using quantitative real-time polymerase chain reaction (qRT-PCR). We also collected the serum from both cohorts and measured ad libitum insulin and leptin concentrations by enzyme-linked immunosorbent assay (ELISA). Our results showed that, in the MBH, GF mice had increased expression of neuropeptides involved in feeding regulation, i.e., Neuropeptide Y (Npy) and Proopiomelanocortin (Pomc), compared to CON mice (p < 0.0001). Furthermore, CON mice had increased expression of a negative regulator of leptin signaling, Suppressor of cytokine signaling 3 (Socs3), in the MBH. Consistently, serum leptin in CON male mice was higher than that of male GF mice (p < 0.001). In the gut samples, the GF cohort demonstrated increased expression of gut hormones that promote satiety, such as Peptide yy (Pyy) and Cholecystokinin (Cck), respectively (p < 0.05 and p < 0.0001). The absence of a microbiome had differing effects on the expression of incretin hormones and the G protein-coupled receptors (GPCRs) that stimulate their secretion. In the jejunum, ileum, and colon of CON mice, expression of Glucagon-like peptide 1 (Glp-1) was increased compared to that of GF mice (p < 0.001, p < 0.05, and p < 0.0001, respectively). Conversely, Glucose-dependent insulinotropic polypeptide (Gip) showed increased expression in the duodenum of male and female GF mice (p < 0.0001). G protein-coupled receptor 119 (Gpr119) and G protein-coupled receptor 120 (Gpr120) showed increased expression only in the colon of female GF mice (p < 0.0001 and p < 0.01, respectively). Germ-free and conventional mice demonstrated comparable ad libitum insulin concentrations. We conclude that the increased expression of Pomc, Gip, Cck, and Pyy and the increased leptin sensitivity in GF mice contribute to the lean phenotype observed in these mice. The additional increase in Npy and decrease in Glp-1 likely play a compensatory role in regulating energy consumption and expenditure. Thus, the microbiome may impinge upon diverse effectors of the neuroendocrine and enteroendocrine systems to regulate host metabolism, influencing energy consumption and expenditure in the development of obesity.
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    Multi-modal Single-Cell Analysis Reveals Brain Immune Landscape Plasticity during Aging and Gut Microbiota Dysbiosis
    (Elsevier, 2020-12-01) Golomb, Samantha M.; Guldner, Ian H.; Zhao, Anqi; Wang, Qingfei; Palakurthi, Bhavana; Aleksandrovic, Emilija A.; Lopez, Jacqueline A.; Lee, Shaun W.; Yang, Kai; Zhang, Siyuan; Medicine, School of Medicine
    Phenotypic and functional plasticity of brain immune cells contribute to brain tissue homeostasis and disease. Immune cell plasticity is profoundly influenced by tissue microenvironment cues and systemic factors. Aging and gut microbiota dysbiosis that reshape brain immune cell plasticity and homeostasis has not been fully delineated. Using Cellular Indexing of Transcriptomes and Epitopes by sequencing (CITE-seq), we analyze compositional and transcriptional changes of the brain immune landscape in response to aging and gut dysbiosis. Discordance between canonical surface-marker-defined immune cell types and their transcriptomes suggest transcriptional plasticity among immune cells. Ly6C+ monocytes predominate a pro-inflammatory signature in the aged brain, while innate lymphoid cells (ILCs) shift toward an ILC2-like profile. Aging increases ILC-like cells expressing a T memory stemness (Tscm) signature, which is reduced through antibiotics-induced gut dysbiosis. Systemic changes due to aging and gut dysbiosis increase propensity for neuroinflammation, providing insights into gut dysbiosis in age-related neurological diseases.
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    Restructuring of the Gut Microbiome by Intermittent Fasting Prevents Retinopathy and Prolongs Survival in db/db Mice
    (American Diabetes Association, 2018-09) Beli, Eleni; Yan, Yuanqing; Moldovan, Leni; Vieira, Cristiano P.; Gao, Ruli; Duan, Yaqian; Prasad, Ram; Bhatwadekar, Ashay; White, Fletcher A.; Townsend, Steven D.; Chan, Luisa; Ryan, Caitlin N.; Morton, Daniel; Moldovan, Emil G.; Chu, Fang-I; Oudit, Gavin Y.; Derendorf, Hartmut; Adorini, Luciano; Wang, Xiaoxin X.; Evans-Molina, Carmella; Mirmira, Raghavendra G.; Boulton, Michael E.; Yoder, Mervin C.; Li, Qiuhong; Levi, Moshe; Busik, Julia V.; Grant, Maria B.; Pediatrics, School of Medicine
    Intermittent fasting (IF) protects against the development of metabolic diseases and cancer, but whether it can prevent diabetic microvascular complications is not known. In db/db mice, we examined the impact of long-term IF on diabetic retinopathy (DR). Despite no change in glycated hemoglobin, db/db mice on the IF regimen displayed significantly longer survival and a reduction in DR end points, including acellular capillaries and leukocyte infiltration. We hypothesized that IF-mediated changes in the gut microbiota would produce beneficial metabolites and prevent the development of DR. Microbiome analysis revealed increased levels of Firmicutes and decreased Bacteroidetes and Verrucomicrobia. Compared with db/db mice on ad libitum feeding, changes in the microbiome of the db/db mice on IF were associated with increases in gut mucin, goblet cell number, villi length, and reductions in plasma peptidoglycan. Consistent with the known modulatory effects of Firmicutes on bile acid (BA) metabolism, measurement of BAs demonstrated a significant increase of tauroursodeoxycholate (TUDCA), a neuroprotective BA, in db/db on IF but not in db/db on AL feeding. TGR5, the TUDCA receptor, was found in the retinal primary ganglion cells. Expression of TGR5 did not change with IF or diabetes. However, IF reduced retinal TNF-α mRNA, which is a downstream target of TGR5 activation. Pharmacological activation of TGR5 using INT-767 prevented DR in a second diabetic mouse model. These findings support the concept that IF prevents DR by restructuring the microbiota toward species producing TUDCA and subsequent retinal protection by TGR5 activation.
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    Volatile Organic Compound Assessment as a Screening Tool for Early Detection of Gastrointestinal Diseases
    (MDPI, 2023-07-17) Dalis, Costa; Mesfin, Fikir M.; Manohar, Krishna; Liu, Jianyun; Shelley, W. Christopher; Brokaw, John P.; Markel, Troy A.; Surgery, School of Medicine
    Gastrointestinal (GI) diseases have a high prevalence throughout the United States. Screening and diagnostic modalities are often expensive and invasive, and therefore, people do not utilize them effectively. Lack of proper screening and diagnostic assessment may lead to delays in diagnosis, more advanced disease at the time of diagnosis, and higher morbidity and mortality rates. Research on the intestinal microbiome has demonstrated that dysbiosis, or unfavorable alteration of organismal composition, precedes the onset of clinical symptoms for various GI diseases. GI disease diagnostic research has led to a shift towards non-invasive methods for GI screening, including chemical-detection tests that measure changes in volatile organic compounds (VOCs), which are the byproducts of bacterial metabolism that result in the distinct smell of stool. Many of these tools are expensive, immobile benchtop instruments that require highly trained individuals to interpret the results. These attributes make them difficult to implement in clinical settings. Alternatively, electronic noses (E-noses) are relatively cheaper, handheld devices that utilize multi-sensor arrays and pattern recognition technology to analyze VOCs. The purpose of this review is to (1) highlight how dysbiosis impacts intestinal diseases and how VOC metabolites can be utilized to detect alterations in the microbiome, (2) summarize the available VOC analytical platforms that can be used to detect aberrancies in intestinal health, (3) define the current technological advancements and limitations of E-nose technology, and finally, (4) review the literature surrounding several intestinal diseases in which headspace VOCs can be used to detect or predict disease.