DataSheet1_Effects of short-chain fatty acids on intestinal function in an enteroid model of hypoxia.docx

The healthy GI tract is physiologically hypoxic, but this may be perturbed by certain acute and chronic stressors that reduce oxygen availability systemically. Short-chain fatty acids have been shown to have beneficial effects on intestinal barrier function and inflammation. Therefore, our objective was to see whether short-chain fatty acids (SCFA) would improve GI barrier function, reduce production of pro-inflammatory cytokines, and increase the expression of genes regulating GI barrier function in enteroids exposed to hypoxia. Human duodenal enteroid monolayers were placed under hypoxia (1.0% O2) for 72 h with either 24, or 48 h pre-treatment with a high acetate ratio of SCFA’s or high butyrate ratio or placed under hypoxia concurrently. Transepithelial electrical resistance (TEER) increased with SCFA pre-treatment, especially 48 h of pre-treatment and this was maintained through the first 48 h of hypoxia while cells saw barrier function dramatically decrease by 72 h of hypoxia exposure. Inflammatory protein secretion largely decreased with exposure to hypoxia, regardless of SCFA pre-treatment. Gene expression of several genes related to barrier function were decreased with exposure to hypoxia, and with concurrent and 24 h SCFA pre-treatment. However, 48 h SCFA pre-treatment with a high butyrate ratio increased expression of several metabolic and differentiation related genes. Overall, pre-treatment or concurrent treatment with SCFA mixtures were not able to overcome the negative impacts of hypoxia on intestinal function and cells ultimately still cannot be sustained under hypoxia for 72 h. However, 48 h pre-treatment maintains TEER for up to 48 h of hypoxia while upregulating several metabolic genes.

健康的小肠生理状态下呈现低氧状态，然而，某些急性与慢性应激因素可能会扰动这种状态，导致系统性氧气供应量减少。研究表明，短链脂肪酸对肠道屏障功能和炎症具有益处。因此，我们的研究目标是观察短链脂肪酸（SCFA）是否能够改善肠道屏障功能，减少促炎细胞因子的产生，并增加在缺氧环境下培养的肠细胞中调节肠道屏障功能的基因表达。将人十二指肠肠细胞单层置于缺氧条件（1.0%氧气）下72小时，同时进行24小时或48小时的SCFA高乙酸比或高丁酸比预处理，或者与缺氧同时进行。SCFA预处理后，跨上皮电阻（TEER）增加，尤其是在48小时的预处理后，这一效应在缺氧的最初48小时内得以维持，而细胞在72小时缺氧暴露后屏障功能显著下降。无论是否进行SCFA预处理，炎症蛋白的分泌在缺氧环境下均显著减少。与缺氧暴露、同时处理和24小时SCFA预处理相比，与屏障功能相关的多个基因的表达均下降。然而，48小时高丁酸比SCFA预处理增加了多个与代谢和分化相关的基因的表达。总体而言，SCFA混合物的预处理或同时处理并不能克服缺氧对肠道功能及细胞造成的负面影响，细胞最终无法在缺氧条件下维持72小时。然而，48小时的预处理能够在缺氧的最初48小时内维持TEER，同时上调多个代谢基因。