Search

The transmembrane protein 43 (TMEM43/LUMA) p.S358L mutation causes arrhythmogenic cardiomyopathy named as ARVC5, a fully penetrant disease with high risk of ventricular arrhythmias, sudden death, and heart failure. Male gender and vigorous exercise independently predicted deleterious outcome. Our systems genetics analysis revealed the importance of Tmem43 for cardiac and metabolic pathways associated with elevated lipid absorption from small intestine. This study sought to delineate gender-specific cardiac, intestinal, and metabolic phenotypes in vivo and investigate underlying pathophysiological mechanisms of S358L mutation. Serial echocardiography, surface electrocardiography (ECG), treadmill running, and body EchoMRI have been used in knock-in heterozygous (Tmem43WT/S358L), homozygous (Tmem43S358L), and wildtype (Tmem43WT) littermate mice. Electron microscopy, histology, immunohistochemistry, transcriptome, and protein analysis have been performed in cardiac and intestinal tissues. Systolic dysfunction was apparent in 3-mo-old Tmem43S358L and 6-mo-old Tmem43WT/S358L mutants. Both mutant lines displayed intolerance to acute stress at 6 mo of age, arrhythmias, fibro-fatty infiltration, and subcellular abnormalities in the myocardium. Microarray analysis found significantly differentially expressed genes between left ventricular (LV) and right ventricular (RV) myocardium. Mutants displayed diminished PPARG activities and significantly reduced TMEM43 and β-catenin expression in the heart, whereas junctional plakoglobin (JUP) translocated into nuclei of mutant cardiomyocytes. Conversely, elongated villi, fatty infiltration, and overexpression of gut epithelial proliferation markers, β-catenin and Ki-67, were evident in small intestine of mutants. We defined Tmem43 S358L-induced pathological effects on cardiac and intestinal homeostasis via distinctly disturbed WNT-β-catenin and PPARG signaling thereby contributing to ARVC5 pathophysiology. Results suggest that cardiometabolic assessment in mutation carriers may be important for predictive and personalized care.NEW & NOTEWORTHY This manuscript describes the findings of our investigation of cardiac, small intestine, and metabolic features of Tmem43-S358L mouse model. By investigating interorgan pathologies, we uncovered multiple mechanisms of the S358L-induced disease, and these unique mechanisms likely appear to contribute to the disease pathogenesis. We hope our findings are important and novel and open new avenues in the hunting for additional diagnostic and therapeutic targets in subjects carrying TMEM43 mutation.

Among the exotic and yet unobserved features of multi-channel Kondo impurity models is their sub-unitary single electron scattering. In the two-channel Kondo model, for example, an incoming electron is fully scattered into a many-body excitation such that the single particle Green function vanishes. Here we propose to directly observe these features in a charge-Kondo device encapsulated in a Mach-Zehnder interferometer - within a device already studied in Ref.[1]. We provide detailed predictions for the visibility and phase of the Aharonov-Bohm oscillations depending on the number of coupled channels and the asymmetry of their couplings., 7 pages, 3 figures

Broad cellular functions and diseases including muscular dystrophy, arrhythmogenic right ventricular cardiomyopathy (ARVC5) and cancer are associated with transmembrane protein43 (TMEM43/ LUMA). The study aimed to investigate biological roles of TMEM43 through genetic regulation, gene pathways and gene networks, candidate interacting genes, and up- or downstream regulators. Cardiac transcriptomes from 40 strains of recombinant inbred BXD mice and two parental strains representing murine genetic reference population (GRP) were applied for genetic correlation, functional enrichment, and coexpression network analysis using systems genetics approach. The results were validated in a newly created knock-in Tmem43-S358L mutation mouse model (Tmem43S358L) that displayed signs of cardiac dysfunction, resembling ARVC5 phenotype seen in humans. We found high Tmem43 levels among BXDs with broad variability in expression. Expression of Tmem43 highly negatively correlated with heart mass and heart rate among BXDs, whereas levels of Tmem43 highly positively correlated with plasma high-density lipoproteins (HDL). Through finding differentially expressed genes (DEGs) between Tmem43S358L mutant and wild-type (Tmem43WT) lines, 18 pathways (out of 42 found in BXDs GRP) that are involved in ARVC, hypertrophic cardiomyopathy, dilated cardiomyopathy, nonalcoholic fatty liver disease, Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease were verified. We further constructed Tmem43-mediated gene network, in which Ctnna1, Adcy6, Gnas, Ndufs6, and Uqcrc2 were significantly altered in Tmem43S358L mice versus Tmem43WT controls. Our study defined the importance of Tmem43 for cardiac- and metabolism-related pathways, suggesting that cardiovascular disease-relevant risk factors may also increase risk of metabolic and neurodegenerative diseases via TMEM43-mediated pathways.

IntroductionChronic stress is co-morbid with alcohol use disorder that feedback on one another, thus impeding recovery from both disorders. Stress and the stress hormone corticosterone aggravate alcohol-induced intestinal permeability and liver damage. However, the mechanisms involved in compounding tissue injury by stress/corticosterone and alcohol are poorly defined. Here we explored the involvement of the TRPV6 channel in stress (or corticosterone) 3and alcohol-induced intestinal epithelial permeability, microbiota dysbiosis, and systemic inflammation. MethodsChronic alcohol feeding was performed on adult wild-type and Trpv6-/- mice with or without corticosterone treatment or chronic restraint stress (CRS). The barrier function was determined by evaluating inulin permeability in vivo and assessing tight junction (TJ) and adherens junction (AJ) integrity by immunofluorescence microscopy. The gut microbiota composition was evaluated by 16S rRNA sequencing and metagenomic analyses. Systemic responses were assessed by evaluating endotoxemia, systemic inflammation, and liver damage.ResultsCorticosterone and CRS disrupted TJ and AJ, increased intestinal mucosal permeability, and caused endotoxemia, systemic inflammation, and liver damage in wild-type but not Trpv6-/- mice. Corticosterone and CRS synergistically potentiated the alcohol-induced breakdown of intestinal epithelial junctions, mucosal barrier impairment, endotoxemia, systemic inflammation, and liver damage in wild-type but not Trpv6-/- mice. TRPV6 deficiency also blocked the effects of CRS and CRS-mediated potentiation of alcohol-induced dysbiosis of gut microbiota. ConclusionsThese findings indicate an essential role of TRPV6 in stress, corticosterone, and alcohol-induced intestinal permeability, microbiota dysbiosis, endotoxemia, systemic inflammation, and liver injury. This study identifies TRPV6 as a potential therapeutic target for developing treatment strategies for stress and alcohol-associated comorbidity.

Animals colonized with a defined microbiota represent useful experimental systems to investigate microbiome function. The altered Schaedler flora (ASF) represents a consortium of eight murine bacterial species that have been used for more than 4 decades where the study of mice with a reduced microbiota is desired. In contrast to germ-free mice, or mice colonized with only one or two species, ASF mice show the normal gut structure and immune system development. To further expand the utility of the ASF, we have developed technical and bioinformatic resources to enable a systems-based analysis of microbiome function using this model. Here, we highlighted four distinct applications of these resources that enable and improve (i) measurements of the abundance of each ASF member by quantitative PCR; (ii) exploration and comparative analysis of ASF genomes and the metabolic pathways they encode that comprise the entire gut microbiome; (iii) global transcriptional profiling to identify genes whose expression responds to environmental changes within the gut; and (iv) discovery of genetic changes resulting from the evolutionary adaptation of the microbiota. These resources were designed to be accessible to a broad community of researchers that, in combination with conventionally-reared mice (i.e., with complex microbiome), should contribute to our understanding of microbiome structure and function.

Metabolism of Nutrients by Gut Microbiota is a timely collection of works focussing on the functional roles of intestinal microorganisms and their diverse metabolites that interface with the host under various dietary inputs and circumstances relevant to human health. Chapters focus on host–microbial interactions under different major macronutrient dietary intakes, the state of prebiotics, probiotics, and synbiotics, interactions between microbes and drug metabolism, how initial microbial colonizers following birth shape lifelong chronic disease risk and metabolism, and the role of microbes in bariatric surgically induced weight loss. We have placed specific emphasis on the functional roles microbes play within the host, as we move beyond descriptive explorations of the microbiome and delve into more focused determination of the mechanisms underpinning microbial contribution to health and disease. This collection of work will be of interest to the lay audience, science enthusiast, industry partners, and career academics alike.

The early life assemblages of microbial community membership, diversity, and function within the gastrointestinal tract play fundamental roles in shaping host growth, body composition, and organ development and function, including the programming of immune systems, shaping central nervous system signaling and behaviour, and influencing metabolic set points. Abnormal colonization during this period may elevate the risk of chronic and metabolic disease throughout the lifespan. Research on the influence of microbial communities on neonatal health has historically been focused on the prevention and treatment of infectious disease during the neonatal and early adolescent period. Over the last decade, deeper insights into the role of normal human microbiome colonization in early life and childhood has grown substantially and strong evidence for its importance in human development has accumulated. Acquisition of an early life microbiome is influenced by the route of birth, nutrition composition and source, antibiotic and toxin exposures, geological location and home environment, and other pivotal factors. The microbiome appears to be dynamically developed during the first year of life but becomes more stabilized once community diversity and membership increases, along with compensatory and complementary host immune response. During microbial community assemblage, it is proposed that critical developmental immune windows are shaped that influence host homeostasis and disease risk in later life. This chapter will review this rapidly developing field and highlight the role of the microbiome in early life along with implications for long-term health during the lifespan.

The prevalence of obesity has become an epidemic among westernized societies and a leading cause of non-communicable disease associated with numerous comorbidities, including diabetes, chronic inflammatory disease, and cancers. In the most morbidly obese patients, bariatric and metabolic surgical interventions are the most effective interventions for weight loss and are associated with rapid improvements in metabolic health. Contributing factors to the efficacy of metabolic surgery include changes in gut signaling pathways – including the enteric nervous system and enteroendocrine hormones – altered food preference, delayed absorption, enhanced thermogenesis, altered enterohepatic circulation, and reshaping of the gut microbiota communities. This chapter will focus on the rise of metabolic surgery for the treatment of obesity and related comorbidities, followed by the state of knowledge regarding mechanisms of action. Bariatric interventions alter the gut microbiome and its interaction with host metabolites, including bile acid pools. We review the interactions between the host, the gut microbiome, bile acid metabolites, and immune function underpinning improved metabolism in obesity, through central and peripheral mechanisms, following metabolic surgery.

Background: Obesity leads to a higher risk of cancer invasion, metastases, recurrence, mortality, and impaired therapeutic response through various mechanisms. One of these mechanisms is microenvironment dysfunction, where changes in immune cells, microbes, metabolites, and growth factors contribute to tumor aggressiveness. We study obesity-induced changes to the tumor microenvironment in Triple Negative Breast Cancer (TNBC), an aggressive subtype associated with obesity. The goal to compare tumor progression in lean vs. obese vs. weight loss manipulations to identify causal and targetable pathways associated with reprogramming the tumor microenvironment. Clinically, bariatric surgery induced weight loss reduced the risk of BC, with the greatest benefit detected in pre-menopausal patients with ER- tumors, like TNBC. We hypothesize surgically-induced weight loss will diminish obesity-associated tumor progression. Methods: To study weight gain and loss that best mimics human adiposity, we utilized obesogenic C57BL/6 females with a syngeneic orthotopic transplant of TNBC cells. Female mice placed on a high fat diet (HFD) at weaning became obese compared to mice on a low fat diet (LFD). After 16 weeks on an HFD diet, mice underwent the bariatric surgery Vertical Sleeve Gastrectomy (VSG). The VSG resulted in reduced body weight, adiposity, and correction of metabolic profiles compared to obese mice. Two weeks post-surgery, TNBC cells were OT into the mammary fat. Results: As expected, tumor growth was increased in obese mice compared to lean. Importantly, surgical weight loss rescued obese tumor progression. We identified key changes in tumor infiltrating of immune cells that could be responsible for the beneficial effects of bariatric surgery on tumor progression. We then exploited these changes with immunotherapy, which was uniquely effective in mice that underwent bariatric surgery. Conclusions: In conclusion obesity promotes a pro-tumor microenvironment, that can be corrected through surgically induced weight loss. Citation Format: Laura Sipe, Mehdi Chaib, Emily B Korba, Mary C Lovely, Jared C Clements, Neena A John, Ajeeth K Pingili, Joseph F Pierre, Liza Makowski. Surgically induced weight loss corrects obesity associated tumor progression and improves responsiveness to immunotherapy [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS17-29.

BACKGROUND Change in left atrial pressure (LAP) has been shown to be associated with symptom improvement post-MitraClip; however, the association between acute procedural changes in transmitral diastolic mean gradient (MG) compared to LAP and symptom improvement is not well established. METHODS 164 consecutive patients undergoing MitraClip at Mayo Clinic between June 2014 and May 2018 were included. Preclip and postclip MG and LAP were recorded. Baseline demographics, clinical, and echocardiographic outcomes, including 30-day New York Heart Association (NYHA) functional status were obtained from patient charts. RESULTS Median age was 81.5 years (IQR: 76.3, 87), 34% were female and 94.5% had NYHA class III and IV functional status at baseline. At baseline, median MG was 4 mmHg (IQR: 3, 5) and LAP was 19 mmHg (IQR: 16, 23.5). Following MitraClip deployment, the median MG was 4 mmHg (IQR: 3, 6) and the median LAP was 17 mmHg (IQR: 14, 21), 69.5% of patients had less than moderate MR. There was no statistically significant association between change in MG and NYHA functional class at 30 days (OR = 0.95, 95% CI: 0.76-1.20). However, a reduction in LAP following MitraClip deployment was significantly associated with improvement in NYHA functional status at 30 days following adjustments for age and sex (aOR 3.36, 95% CI: 1.34-8.65). There was no significant correlation between change in mean LAP and change in MG (p = .98). CONCLUSION Unlike change in left atrial pressure, change in MG post-MitraClip was not associated with patient reported outcomes at 30 days and did not correlate with change in left atrial pressure. Long-term follow up is needed to evaluate the impact of LA pressure on symptoms.

Alcohol use disorders are associated with altered stress responses, but the impact of stress or stress hormones on alcohol-associated tissue injury remain unknown. We evaluated the effects of chronic restraint stress on alcohol-induced gut barrier dysfunction and liver damage in mice. To determine whether corticosterone is the stress hormone associated with the stress-induced effects, we evaluated the effect of chronic corticosterone treatment on alcoholic tissue injury at the Gut-Liver-Brain (GLB) axis. Chronic restraint stress synergized alcohol-induced epithelial tight junction disruption and mucosal barrier dysfunction in the mouse intestine. These effects of stress on the gut were reproduced by corticosterone treatment. Corticosterone synergized alcohol-induced expression of inflammatory cytokines and chemokines in the colonic mucosa, and it potentiated the alcohol-induced endotoxemia and systemic inflammation. Corticosterone also potentiated alcohol-induced liver damage and neuroinflammation. Metagenomic analyses of 16S RNA from fecal samples indicated that corticosterone modulates alcohol-induced changes in the diversity and abundance of gut microbiota. In Caco-2 cell monolayers, corticosterone dose-dependently potentiated ethanol and acetaldehyde-induced tight junction disruption and barrier dysfunction. These data indicate that chronic stress and corticosterone exacerbate alcohol-induced mucosal barrier dysfunction, endotoxemia, and systemic alcohol responses. Corticosterone-mediated promotion of alcohol-induced intestinal epithelial barrier dysfunction and modulation of gut microbiota may play a crucial role in the mechanism of stress-induced promotion of alcohol-associated tissue injury at the GLB axis.

The rapid expansion of microbiota research has significantly advanced our understanding of the complex interactions between gut microbiota and cardiovascular, metabolic, and renal system regulation. Low-grade chronic inflammation has long been implicated as one of the key mechanisms underlying cardiometabolic disease risk and progression, even before the insights provided by gut microbiota research in the past decade. Microbial translocation into the bloodstream can occurviadifferent routes, including through the oral and/or intestinal mucosa, and may contribute to chronic inflammation in cardiometabolic disease. Among several gut-derived products identifiable in the systemic circulation, bacterial endotoxins and metabolites have been extensively studied, however recent advances in microbial DNA sequencing have further allowed us to identify highly diverse communities of microorganisms in the bloodstream from an -omics standpoint, which is termed “circulating microbiota.” While detecting microorganisms in the bloodstream was historically considered as an indication of infection, evidence on the circulating microbiota is continually accumulating in various patient populations without clinical signs of infection and even in otherwise healthy individuals. Moreover, both quantitative and compositional alterations of the circulating microbiota have recently been implicated in the pathogenesis of chronic inflammatory conditions, potentially through their immunostimulatory, atherogenic, and cardiotoxic properties. In this mini review, we aim to provide recent evidence on the characteristics and roles of circulating microbiota in several cardiometabolic diseases, such as type 2 diabetes, cardiovascular disease, and chronic kidney disease, with highlights of our emerging findings on circulating microbiota in patients with end-stage kidney disease undergoing hemodialysis.

Gut microbial diurnal oscillations are important diet-dependent drivers of host circadian rhythms and metabolism ensuring optimal energy balance. Yet, the interplay between diet, microbes, and host factors sustaining intestinal oscillations is complex and poorly understood. Here, using a mouse model, we report the host C-type lectin antimicrobial peptide Reg3γ works with key ileal microbes to orchestrate these interactions in a bi-directional manner and does not correlate with the intestinal core circadian clock. High-fat diet is the primary driver of microbial oscillators that impair host metabolic homeostasis, resulting in arrhythmic host Reg3γ expression that secondarily drives abundance and oscillation of key gut microbes. This illustrates transkingdom coordination of biological rhythms primarily influenced by diet, and reciprocal sensor-effector signals between host and microbial components, ultimately driving metabolism. Restoring the gut microbiota’s capacity to sense dietary signals mediated by specific host factors such as Reg3γ could be harnessed to improve metabolic dysfunction.

Bariatric surgery is becoming more prevalent as a sustainable weight loss approach, with vertical sleeve gastrectomy (VSG) being the first line of surgical intervention. We and others have shown that obesity exacerbates tumor growth while diet-induced weight loss impairs obesity-driven progression. It remains unknown how bariatric surgery-induced weight loss impacts cancer progression or alters responses to therapy. Using a pre-clinical model of diet induced obesity followed by VSG or diet-induced weight loss, breast cancer progression and immune checkpoint blockade therapy was investigated. Weight loss by bariatric surgery or weight matched dietary intervention before tumor engraftment protected against obesity-exacerbated tumor progression. However, VSG was not as effective as dietary intervention in reducing tumor burden despite achieving a similar extent of weight and adiposity loss. Circulating leptin did not associate with changes in tumor burden. Uniquely, tumors in mice that received VSG displayed elevated inflammation and immune checkpoint ligand, PD-L1. Further, mice that received VSG had reduced tumor infiltrating T lymphocytes and cytolysis suggesting an ineffective anti-tumor microenvironment. VSG-associated elevation of PD-L1 prompted us to next investigate the efficacy of immune checkpoint blockade in lean, obese, and formerly obese mice that lost weight by VSG or weight matched controls. While obese mice were resistant to immune checkpoint blockade, anti-PD-L1 potently impaired tumor progression after VSG through improved anti-tumor immunity. Thus, in formerly obese mice, surgical weight loss followed by immunotherapy reduced breast cancer burden.

Obesity is a complex metabolic condition considered a worldwide public health crisis, and a deeper mechanistic understanding of obesity-associated diseases is urgently needed. Obesity comorbidities include many associated cancers and are estimated to account for 20% of female cancer deaths in the USA. Breast cancer, in particular, is associated with obesity and is the focus of this review. The exact causal links between obesity and breast cancer remain unclear. Still, interactions have emerged between body mass index, tumor molecular subtype, genetic background, and environmental factors that strongly suggest obesity influences the risk and progression of certain breast cancers. Supportive preclinical research uses various diet-induced obesity models to demonstrate that weight loss, via dietary interventions or changes in energy expenditure, reduces the onset or progression of breast cancers. Ongoing and future studies are now aimed at elucidating the underpinning mechanisms behind weight-loss-driven observations to improve therapy and outcomes in patients with breast cancer and reduce risk. This review aims to summarize the rapidly emerging literature on obesity and weight loss strategies with a focused discussion of bariatric surgery in both clinical and preclinical studies detailing the complex interactions between metabolism, immune response, and immunotherapy in the setting of obesity and breast cancer.

Parenteral nutrition (PN) provides nutritional support intravenously to individuals who have gastrointestinal (GI) failure or contraindication to enteral feeding. Since the initial development of PN, researchers have developed specialized formulas with complete macronutrients, micronutrients, vitamins, minerals, and electrolytes to support patients’ metabolic needs. These formulas prevent malnutrition and optimize patient health, especially under long-term feeding circumstances. Although PN is commonly used and essential in preterm and malnourished patients, complications associated with PN feeding include gastrointestinal defects, infection, and other metabolic abnormalities such as liver injury and brain related disorders. In this chapter, we highlight an overview of PN and its association with abnormalities of microbiome composition as well as with gastrointestinal (GI), immune, hepatic, and neuronal disfunction. Within the gut, PN influences the number and composition of gut-associated lymphoid tissue (GALT) cells, altering adaptive immune responses. PN also modulates intestinal epithelium cell turnover, secretions, and gut barrier function, as well as the composition of the intestinal microbiome leading to changes in gut permeability. Collectively, these changes result in increased susceptibility to infection and injury. Here, we highlight animal models used to examine parenteral nutrition, changes that occur to the major organ systems, and recent advancement in using enteric nervous system (ENS) neuropeptides or microbially derived products during PN, which may improve GI, immune cell, hepatic, and neuronal function.

Elevated levels of dietary fats in westernized diets, associated with increased risk of obesity and other chronic diseases, are increasingly consumed by children in the United States. Cooking practices such as high heat frying and increased use of oxidizable sources of fats have introduced high levels of lipid oxidation products (LOPs) into these diets. The effects of these highly reactive dietary compounds on human biology are largely unstudied, especially in the gut where these compounds are likely present at higher concentrations. Given that the gut microbiome can be influenced by dietary components and then in turn have a systemic impact, we investigated the effects of consuming LOPs on gut bacterial and fungal communities and on growth and body composition during the prepubertal period in a porcine model. The presence of LOPs in the high fat diet reduced growth and body fat gain in the model. The gut microbiome was uniquely altered by both high fat and the presence of LOPs, with notable changes in the abundances of Turicibacterales, Spriochaetales, RF39, Lactobacillales and Erysipelotrichales. The mycobiome was dominated by Kazachstania, a porcine specific yeast, which was only minimally influenced by the dietary regimen. Application of machine learning identified dietary fat and LOPs as strong predictors of body fat. The genus Methanobrevibacter was the key microbial predictor of body fat. This study highlights the need for further studies on the biological effects of LOPs which have become ubiquitous in human, livestock and pet diets in developed countries.