Biology subjects

Wallach, T.

Publications and source records attributed to Wallach, T..

4 recordsLinked to original sources

bioRxiv2022

In-Vitro Efficacy of Targeted FODMAP Enzymatic Digestion in a High-Fidelity Simulated Gastrointestinal Environment

IntroductionIrritable bowel syndrome (IBS) is characterized by abdominal pain and changes in bowel habits. FODMAPs are poorly absorbed short-chain carbohydrates that may drive commensal microbial gas production, promoting abdominal pain in IBS. Low-FODMAP diet can result in symptomatic improvement in 50-80% of IBS patients. However, this diet is not meant to be sustained long term, with concern for downstream nutrition and microbial issues. In this study, we evaluate the function of a targeted FODMAP enzymatic digestion food supplement FODZYME(R) containing an fructan hydrolase enzyme in a simulated gastrointestinal environment. MethodsUsing SHIME(R), a multi-compartment simulator of the human gut, FODZYME(R) dose finding assay in modeled gastrointestinal conditions assessed enzymatic ability to hydrolyze 3 g of inulin. Full intestinal modeling assessing digestion of inulin, absorption of fructose, gas production and other measures of commensal microbial behavior was completed using 1.125 g of FODZYME(R). ResultsAfter 30 minutes, 90% of the inulin was converted to fructose by 1.125 g of FODZYME(R).Doubling dosage showed no significant improvement in conversion, whereas a half dose decreased performance to 77.2%. 70% of released fructose was absorbed during simulated small intestinal transit, with a corresponding decrease in microbial gas production, and a small decrease in butyrate and short chain fatty acid (SCFA) production. DiscussionFODZYME(R) specifically breaks down inulin in representative gastrointestinal conditions, resulting in decreased gas production while substantially preserving SCFA and butyrate production in the model colon. Our results suggest dietary supplementation with FODZYME(R) would decrease intestinal FODMAP burden and gas production.

pharmacology and toxicology↗

bioRxiv2021

Single-cell profiling of environmental enteropathy reveals signatures of epithelial remodeling and immune activation in severe disease

Environmental enteropathy (EE) is a subclinical condition of the small intestine that is highly prevalent in low- and middle-income countries. It is thought to be a key contributing factor to childhood malnutrition, growth-stunting, and diminished oral vaccine responses. While EE has been shown to be the by-product of recurrent enteric infection, its full pathophysiology remains unclear. Here, we mapped the cellular and molecular correlates of EE severity by performing high-throughput single-cell RNA-sequencing on 33 small intestinal biopsies from 11 adults with EE from Lusaka, Zambia (8 HIV-negative, 3 HIV-positive), 6 adults without EE in Boston, USA, and 2 adults from Durban, South Africa, which we complemented with published data from 3 additional South African adults from the same clinical site. By using these data to reanalyze previously-defined bulk-transcriptomic signatures of reduced villus height and decreased plasma LPS levels in EE, we found that these signatures may be driven by an increased abundance of surface mucosal cells - a gastric-like subset previously implicated in epithelial repair in the gastrointestinal tract. In addition, we identified several cell subsets whose fractional abundances associate with histologically determined EE severity, small intestinal region, and HIV infection. Furthermore, by comparing distal duodenal EE samples with those from three control cohorts, we identified dysregulated WNT and MAPK signaling in the EE epithelium and a T cell subset highly expressing a transcriptional signature of tissue-resident memory cells but with increased pro-inflammatory cytokine expression in the EE cohort. Altogether, our work illuminates epithelial and immune correlates of EE and provides new molecular targets for intervention. One Sentence SummaryUsing single-cell RNA-sequencing, we characterize the pathophysiology of environmental enteropathy (EE) - a highly prevalent condition of the small intestine that is thought to be a primary cause of global growth-stunting cases and a key contributing factor to childhood malnutrition and diminished oral vaccine responses - to derive insights into the epithelial and immune correlates of disease severity, suggesting new therapeutic targets for future investigation.

genomics↗

bioRxiv2019

Lactoferrin Reverses Methotrexate Driven Epithelial Barrier Defect by Inhibiting TGF-β Mediated Epithelial to Mesenchymal Transition

BACKGROUND AND AIMSMethotrexate is an important tool in the arsenal of oncologists, gastroenterologists, and rheumatologists. At low doses it induces intestinal barrier dysfunction that may induce side effects such as gastrointestinal discomfort and liver injury. Previous studies suggest that lactoferrin can improve barrier function in a variety of contexts. This study set out to determine the mechanism of methotrexate induced barrier dysfunction and assess the effect of lactoferrin and other components of human breast milk on this dysfunction. METHODSUsing a murine enteroid model and Caco2 spheroids, we measured flux of basolateral-administered fluorescent dextran into the lumen. Barrier dysfunction was induced using methotrexate (220 nM) or lipopolysaccharide (20 nM). Human lactoferrin was added at 0.8 mg/ml (10 {micro}M). RNAseq was performed on exposed samples. RESULTSLactoferrin blocks methotrexate-induced barrier dysfunction in murine enteroids. Similar results were observed when barrier dysfunction was induced in Caco2 spheroids with methotrexate and LPS, but not ML7. RNAseq revealed activation of TGF-{beta} response genes and epithelial-mesenchymal transition (EMT) by methotrexate, which normalized in the presence of lactoferrin. TGF-{beta} receptor inhibition (RepSox) blocked methotrexate induced barrier dysfunction in Caco2 spheroids. 20 nM TGF-{beta} induced barrier dysfunction in Caco2 spheroids which was also inhibited by lactoferrin. CONCLUSIONSMethotrexate induces barrier dysfunction by activation of an EMT program promoted by TGF-{beta} signaling and inhibited by lactoferrin. Lactoferrin is also protective of barrier function in an LPS-induced model. The likely mechanism of this effect is blockade of EMT programs induced by TGF-{beta}.

cell biology↗

bioRxiv2019

Human endogenous retrovirus HERV-K(HML-2) RNA causes neurodegeneration through Toll-like receptors

Although human endogenous retroviruses (HERVs) represent a substantial proportion of the human genome and some HERVs have been suggested to be involved in neurological disorders, little is known about their biological function and pathophysiological relevance. HERV-K(HML-2) comprises evolutionarily young proviruses transcribed in the brain. We report that RNA derived from an HERV-K(HML-2) env gene region binds to the human RNA-sensing Toll-like receptor (TLR) 8, activates human TLR8, as well as murine Tlr7, and causes neurodegeneration through TLR8 and Tlr7 in neurons and microglia. HERV-K(HML-2) RNA introduced extracellularly into the cerebrospinal fluid (CSF) of either C57BL/6 wild-type mice or APPPS1 mice, a mouse model for Alzheimers disease (AD), resulted in neurodegeneration. Tlr7-deficient mice were protected against neurodegenerative effects, but were re-sensitized towards HERV-K(HML-2) RNA when neurons ectopically expressed murine Tlr7 or human TLR8. Accordingly, transcriptome datasets of human brain samples from AD patients revealed a specific correlation of upregulated HERV-K(HML-2) and TLR8 RNA expression. HERV-K(HML-2) RNA was detectable more frequently in CSF from AD individuals compared to controls. Our data establish HERV-K(HML-2) RNA as an endogenous ligand for human TLR8 and murine Tlr7 and imply a functional contribution of specific human endogenous retroviral transcripts to neurodegenerative processes such as AD.

neuroscience↗