Vitamin D receptor (VDR) executes the main biological functions of its ligand vitamin D. VDR/vitamin D plays critical roles in regulating host immunity, maintaining barrier functions, and shaping gut microbiome. Reduction of intestinal VDR has been reported in various diseases, including inflammatory diseases and colon cancer. However, it is always challenging to get biopsies to test the pathologic changes of VDR in intestine. In the current study, we reported a simple and sensitive quantitative PCR (qPCR) method to detect reduction of intestinal VDR using fecal samples. We validated this method in several experimental models, such as colitis, bacterial infection, and aging. We further correlated the qPCR data of VDR with the protein level of VDR in colon or serum 25 (OH)D₃ in mice with different VDR status (VDR^+/+, VDR^+/-, and VDR^−/−). Our data indicate that the qPCR method to test VDR using fecal samples could detect the expression level of intestinal VDR in various diseases. Our study highlights the feasibility, sensitivity, and simplicity of a molecular method to study the status of VDR as a biomarker.

维生素 D 受体 (VDR) 执行其配体维生素 D 的主要生物学功能。VDR/维生素 D 在调节宿主免疫、维持屏障功能和塑造肠道微生物群方面发挥着关键作用。肠道 VDR 的降低已被报道用于多种疾病，包括炎症性疾病和结肠癌。然而，通过活组织检查来测试肠道 VDR 的病理变化总是具有挑战性的。在目前的研究中，我们报告了一种简单而灵敏的定量 PCR (qPCR) 方法，可使用粪便样本检测肠道 VDR 的减少。我们在多种实验模型中验证了这种方法，例如结肠炎、细菌感染和衰老。我们进一步将 VDR 的 qPCR 数据与结肠或血清 25 (OH)D ₃中 VDR 的蛋白质水平相关联在具有不同 VDR 状态（VDR ^+/+、VDR ^+/-和 VDR ^-/-）的小鼠中。我们的数据表明，使用粪便样本检测 VDR 的 qPCR 方法可以检测各种疾病中肠道 VDR 的表达水平。我们的研究强调了研究 VDR 作为生物标志物状态的分子方法的可行性、敏感性和简单性。