研究报告了胃肠道(GI)症状的发生,主要是COVID-19的腹泻。然而,关于COVID-19在胃肠道中的病理学仍然有限。这项工作旨在在不同的实验方法中评估SARS-CoV-2刺突蛋白与肠腔的相互作用。这里,我们提出了一种新的实验模型,在小鼠空肠腔中接种病毒蛋白,体外方法与人肠上皮细胞和分子对接分析。刺突蛋白导致肠液增加,伴有Cl-分泌,其次是肠水肿,白细胞浸润,谷胱甘肽水平降低,和增加的细胞因子水平(IL-6,TNF-α,IL-1β,IL-10),提示炎症。此外,病毒表位导致粘膜组织结构的破坏,并损害潘氏和杯状细胞,包括溶菌酶和粘蛋白的减少,分别。TLR2和TLR4基因表达上调提示局部先天免疫的潜在激活。此外,该实验模型显示空肠平滑肌的收缩反应降低。在屏障功能中,小鼠空肠上皮中跨上皮电阻降低,紧密连接蛋白表达改变。此外,在人肠上皮细胞中,细胞旁肠通透性增加。最后,计算机模拟数据显示,Spike蛋白与CFTR和CaCC相互作用,推断其在分泌效应中的作用。一起来看,观察到的所有事件点肠道损伤,影响到最内层的粘膜屏障,建立了在GI背景下研究COVID-19的成功实验模型。
Studies have reported the occurrence of gastrointestinal (GI) symptoms, primarily diarrhea, in COVID-19. However, the pathobiology regarding COVID-19 in the GI tract remains limited. This work aimed to evaluate SARS-CoV-2 Spike protein interaction with gut lumen in different experimental approaches. Here, we present a novel experimental model with the inoculation of viral protein in the murine jejunal lumen, in vitro approach with human enterocytes, and molecular docking analysis. Spike protein led to increased intestinal fluid accompanied by Cl- secretion, followed by intestinal edema, leukocyte infiltration, reduced glutathione levels, and increased cytokine levels [interleukin (IL)-6, tumor necrosis factor-α, IL-1β, IL-10], indicating inflammation. Additionally, the viral epitope caused disruption in the mucosal histoarchitecture with impairment in Paneth and goblet cells, including decreased lysozyme and mucin, respectively. Upregulation of toll-like receptor 2 and toll-like receptor 4 gene expression suggested potential activation of local innate immunity. Moreover, this experimental model exhibited reduced contractile responses in jejunal smooth muscle. In barrier function, there was a decrease in transepithelial electrical resistance and alterations in the expression of tight junction proteins in the murine jejunal epithelium. Additionally, paracellular intestinal permeability increased in human enterocytes. Finally, in silico data revealed that the Spike protein interacts with cystic fibrosis transmembrane conductance regulator (CFTR) and calcium-activated chloride conductance (CaCC), inferring its role in the secretory effect. Taken together, all the events observed point to gut impairment, affecting the mucosal barrier to the innermost layers, establishing a successful experimental model for studying COVID-19 in the GI context.