Metabolic changes associated with tissue inflammation result in significant extracellular acidosis (EA). Within mucosal tissues, intestinal epithelial cells (IEC) have evolved adaptive strategies to cope with EA through the up-regulation of SLC26A3 to promote pH homeostasis. We hypothesized that EA significantly alters IEC gene expression as an adaptive mechanism to counteract inflammation. Using an unbiased RNA sequencing approach, we defined the impact of EA on IEC gene expression to define molecular mechanisms by which IEC respond to EA. This approach identified a unique gene signature enriched in cyclic AMP response element-binding protein (CREB)-regulated gene targets. Utilizing loss- and gain-of-function approaches in cultured epithelia and murine colonoids, we demonstrate that EA elicits prominent CREB phosphorylation through cyclic AMP-independent mechanisms that requires elements of the mitogen-activated protein kinase signaling pathway. Further analysis revealed that EA signals through the G protein-coupled receptor GPR31 to promote induction of FosB, NR4A1, and DUSP1. These studies were extended to an in vivo murine model in conjunction with colonization of a pH reporter Escherichia coli strain that demonstrated significant mucosal acidification in the TNFΔARE model of murine ileitis. Herein, we observed a strong correlation between the expression of acidosis-associated genes with bacterial reporter sfGFP intensity in the distal ileum. Finally, the expression of this unique EA-associated gene signature was increased during active inflammation in patients with Crohn’s disease but not in the patient control samples. These findings establish a mechanism for EA-induced signals during inflammation-associated acidosis in both murine and human ileitis.

与组织炎症相关的代谢变化导致显着的细胞外酸中毒 (EA)。在粘膜组织内，肠上皮细胞 (IEC) 已经进化出适应策略来应对 EA，通过上调 SLC26A3 来促进 pH 稳态。我们假设 EA 显着改变了 IEC 基因表达，作为一种抵抗炎症的适应性机制。使用无偏见的 RNA 测序方法，我们定义了 EA 对 IEC 基因表达的影响，以定义 IEC 响应 EA 的分子机制。这种方法确定了富含环 AMP 反应元件结合蛋白 (CREB) 调节的基因靶标的独特基因特征。在培养的上皮细胞和鼠类结肠样中利用功能丧失和获得的方法，我们证明 EA 通过需要丝裂原活化蛋白激酶信号通路元件的环状 AMP 非依赖性机制引发显着的 CREB ​​磷酸化。进一步分析表明，EA 通过 G 蛋白偶联受体 GPR31 发出信号，以促进 FosB、NR4A1 和 DUSP1 的诱导。这些研究扩展到体内鼠模型以及 pH 报告基因的定植在小鼠回肠炎的 TNFΔARE 模型中表现出显着黏膜酸化的大肠杆菌菌株。在这里，我们观察到酸中毒相关基因的表达与回肠末端的细菌报告基因 sfGFP 强度之间存在很强的相关性。最后，这种独特的 EA 相关基因特征的表达在克罗恩病患者的活动性炎症期间增加，但在患者对照样本中没有。这些发现建立了在小鼠和人类回肠炎中炎症相关酸中毒期间 EA 诱导信号的机制。