Evidence has been shown that indoxyl sulfate (IS) could impair kidney and cardiac functions. Moreover, macrophage polarization played important roles in chronic kidney disease and cardiovascular disease. IS acts as a nephron-vascular toxin, whereas its effect on macrophage polarization during inflammation is still not fully elucidated. In this study, we aimed to investigate the effect of IS on macrophage polarization during lipopolysaccharide (LPS) challenge. THP-1 monocytes were incubated with phorbol 12-myristate-13-acetate (PMA) to differentiate into macrophages, and then incubated with LPS and IS for 24 h. ELISA was used to detect the levels of TNFα, IL-6, IL-1β in THP-1-derived macrophages. Western blot assay was used to detect the levels of arginase1 and iNOS in THP-1-derived macrophages. Percentages of HLA-DR-positive cells (M1 macrophages) and CD206-positive cells (M2 macrophages) were detected by flow cytometry. IS markedly increased the production of the pro-inflammatory factors TNFα, IL-6, IL-1β in LPS-stimulated THP-1-derived macrophages. In addition, IS induced M1 macrophage polarization in response to LPS, as evidenced by the increased expression of iNOS and the increased proportion of HLA-DR+ macrophages. Moreover, IS downregulated the level of β-catenin, and upregulated the level of YAP in LPS-stimulated macrophages. Activating β-catenin signaling or inhibiting YAP signaling suppressed the IS-induced inflammatory response in LPS-stimulated macrophages by inhibiting M1 polarization. IS induced M1 macrophage polarization in LPS-stimulated macrophages via inhibiting β-catenin and activating YAP signaling. In addition, this study provided evidences that activation of β-catenin or inhibition of YAP could alleviate IS-induced inflammatory response in LPS-stimulated macrophages. This finding may contribute to the understanding of immune dysfunction observed in chronic kidney disease and cardiovascular disease.

有证据表明硫酸吲哚酚（IS）可能损害肾脏和心脏功能。此外，巨噬细胞极化在慢性肾脏疾病和心血管疾病中发挥着重要作用。IS 作为一种肾单位血管毒素，但其在炎症过程中对巨噬细胞极化的影响尚未完全阐明。在本研究中，我们旨在研究脂多糖 (LPS) 攻击期间 IS 对巨噬细胞极化的影响。THP-1单核细胞与佛波醇12-肉豆蔻酸酯-13-乙酸酯(PMA)一起孵育以分化为巨噬细胞，然后与LPS和IS一起孵育24小时。采用ELISA法检测THP-1来源的巨噬细胞中TNFα、IL-6、IL-1β的水平。Western blot法检测THP-1来源的巨噬细胞中精氨酸酶1和iNOS的水平。通过流式细胞仪检测HLA-DR阳性细胞（M1巨噬细胞）和CD206阳性细胞（M2巨噬细胞）的百分比。IS 显着增加了 LPS 刺激的 THP-1 衍生巨噬细胞中促炎因子 TNFα、IL-6、IL-1β 的产生。此外，IS 响应 LPS 诱导 M1 巨噬细胞极化，iNOS 表达增加和 HLA-DR+ 巨噬细胞比例增加证明了这一点。此外，IS 下调了 LPS 刺激的巨噬细胞中 β-连环蛋白的水平，并上调了 YAP 的水平。激活 β-catenin 信号传导或抑制 YAP 信号传导可通过抑制 M1 极化来抑制 LPS 刺激的巨噬细胞中 IS 诱导的炎症反应。IS 通过抑制 β-catenin 和激活 YAP 信号传导，在 LPS 刺激的巨噬细胞中诱导 M1 巨噬细胞极化。此外，这项研究提供的证据表明，β-连环蛋白的激活或 YAP 的抑制可以减轻 LPS 刺激的巨噬细胞中 IS 诱导的炎症反应。这一发现可能有助于了解慢性肾脏病和心血管疾病中观察到的免疫功能障碍。