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Background & AimsHypoxia in the intestinal epithelium can be caused by acute ischemic events or conditions like Inflammatory Bowel Disease (IBD) where immune cell infiltration produces ‘inflammatory hypoxia’, a chronic condition that starves the mucosa of oxygen. Epithelial regeneration after ischemia and IBD suggests intestinal stem cells (ISCs) are highly tolerant to acute and chronic hypoxia; however, the impact of acute and chronic hypoxia on human ISC (hISC) properties have not been reported. Here we present a new microphysiological system (MPS) to investigate how hypoxia affects hISCs isolated from healthy human tissues. We then test the hypothesis that some inflammation-associated interleukins protect hISCs during prolonged hypoxia.MethodshISCs were exposed to ResultsThe novel MPS enables precise, real-time control and monitoring of oxygen levels at the cell surface. Under hypoxia, hISCs remain viable until 72hrs and exhibit peak HIF1α at 24hrs. hISCs lose stem cell activity at 24hrs that recovers at 48hrs of hypoxia. Hypoxia increases the proportion of hISCs in G1 and regulates hISC capacity to respond to multiple inflammatory signals. Hypoxia induces hISCs to upregulate many interleukin receptors and hISCs demonstrate hypoxia-dependent cell cycle regulation and increased organoid forming efficiency when treated with specific interleukinsConclusionsHypoxia primes hISCs to respond differently to interleukins than hISCs in normoxia through a transcriptional response. hISCs slow cell cycle progression and increase hISC activity when treated with hypoxia and specific interleukins. These findings have important implications for epithelial regeneration in the gut during inflammatory events.

Fatty acid oxidation by absorptive enterocytes has been linked to the pathophysiology of type 2 diabetes, obesity, and dyslipidemia. Caco-2 and organoids have been used to study dietary lipid-handling processes including fatty acid oxidation, but are limited in physiological relevance or preclude simultaneous apical and basal access. Here, we developed a high-throughput planar human absorptive enterocyte monolayer system for investigating lipid handling, and then evaluated the role of fatty acid oxidation in fatty acid export, using etomoxir, C75, and the antidiabetic drug metformin.Single-cell RNA-sequencing, transcriptomics, and lineage trajectory was performed on primary human jejunum. In vivo absorptive enterocyte maturational states informed conditions used to differentiate human intestinal stem cells (ISCs) that mimic in vivo absorptive enterocyte maturation. The system was scaled for high-throughput drug screening. Fatty acid oxidation was modulated pharmacologically and BODIPY (Thermo Fisher Scientific, Waltham, MA) (B)-labeled fatty acids were used to evaluate fatty acid handling via fluorescence and thin-layer chromatography.Single-cell RNA-sequencing shows increasing expression of lipid-handling genes as absorptive enterocytes mature. Culture conditions promote ISC differentiation into confluent absorptive enterocyte monolayers. Fatty acid-handling gene expression mimics in vivo maturational states. The fatty acid oxidation inhibitor etomoxir decreased apical-to-basolateral export of medium-chain B-C12 and long-chain B-C16 fatty acids, whereas the CPT1 agonist C75 and the antidiabetic drug metformin increased apical-to-basolateral export. Short-chain B-C5 was unaffected by fatty acid oxidation inhibition and diffused through absorptive enterocytes.Primary human ISCs in culture undergo programmed maturation. Absorptive enterocyte monolayers show in vivo maturational states and lipid-handling gene expression profiles. Absorptive enterocytes create strong epithelial barriers in 96-Transwell format. Fatty acid export is proportional to fatty acid oxidation. Metformin enhances fatty acid oxidation and increases basolateral fatty acid export, supporting an intestine-specific role.

Background & AimsAbsorption, metabolism, and export of dietary lipids occurs in the small intestinal epithelium. Caco-2 and organoids have been used to study these processes but are limited in physiological relevance or preclude simultaneous apical and basal access. Here, we develop a high-throughput planar human absorptive enterocyte (AE) monolayer system for investigating lipid-handling, then evaluate the role of fatty acid oxidation (FAO) in fatty acid (FA) export, using etomoxir, C75, and anti-diabetic drug, metformin.MethodsSingle-cell RNA-sequencing (scRNAseq), transcriptomics, and lineage trajectory was performed on primary human jejunum. In vivo AE maturational states informed conditions used to differentiate human intestinal stem cells (ISCs) that mimic in vivo AE maturation. The system was scaled for high-throughput drug screening. Fatty acid oxidation (FAO) was pharmacologically modulated and BODIPY™ (B)-labelled FAs were used to evaluate FA-handling via fluorescence and thin layer chromatography (TLC).ResultsscRNAseq shows increasing expression of lipid-handling genes as AEs mature. Culture conditions promote ISC differentiation into confluent AE monolayers. FA-handling gene expression mimics in vivo maturational states. FAO inhibitor, etomoxir, decreased apical-to-basolateral export of medium-chain B-C12 and long-chain B-C16 FAs whereas CPT1 agonist, C75, and antidiabetic drug, metformin, increased apical-to-basolateral export. Short-chain B-C5 was unaffected by FAO inhibition and diffused through AEs.ConclusionsPrimary human ISCs in culture undergo programmed maturation. AE monolayers demonstrate in vivo maturational states and lipid-handling gene expression profiles. AEs create strong epithelial barriers in 96-Transwell format. FA export is proportional to FAO. Metformin enhances FAO and increases basolateral FA export, supporting an intestine-specific role.

Head and neck squamous cell carcinomas (HNSCCs) have devastating morbidity rates with mortality mainly because of metastasis.Multiplex enzyme-linked immunosorbent assay (ELISA) to assay a variety of cytokine levels secreted by a panel of stage-specific and anatomic site-specific primary, and recurrent and metastatic University of Michigan-HNSCC cell lines over a 72-hour time course.Conditioned medium from metastatic or recurrent HNSCC showed significantly higher amounts of interleukin (IL)-6, IL-6 receptor, tumor growth factor-beta (TGF-β) and vascular endothelial growth factor (VEGF) than nonmetastatic cells or normal oral keratinocytes. Tumor necrosis factor (TNF) was only secreted by stage IV, metastatic, or recurrence-derived cell lines.The cytokine profile of cultured HNSCC cells suggests that high levels of IL-6 and IL-6R, TGF-β, and VEGF are significantly related with their metastatogenic potential and provide rationale for determining if serum testing for a combination of these 4 soluble factors could be of predictive value for the HNSCC tumor progression and clinical outcome.