Background: The bronchial infection by Mycobacterium tuberculosis (Mtb) is increasing in prevalence and severity worldwide. Despite appropriate tuberculosis treatment, most patients still develop bronchial stenosis, which often leads to disability. Polyphyllin II (PP2) is a steroidal saponin extracted from Rhizoma Paridis. In this study, we aimed to explore the effect of PP2 on the advancement of Mtb-induced bronchial infection. Method: The effects of PP2 on cell viability were measured by using MTT and lactate dehydrogenase (LDH) kit. The mRNA and protein levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-8 were elucidated by RT-qPCR and ELISA, respectively. The expression of NLR family pyrin domain containing 3 (NLRP3) related inflammasome (NLRP3, IL-1β, and cleaved-caspase-1) and the activated degree of protein kinase B (AKT)/nuclear factor-kappa B (NF-kB; p-AKT and p-NF-κB) were detected by Western blotting. Results: PP2 at 0, 1, 5, and 10 μM had little cytotoxicity on 16HBE cells. PP2 inhibited Mtb-induced cell proliferation and decreased LDH levels. We further found that PP2 could suppress Mtb-induced inflammatory responses and activation of NLPR3 inflammasome. Additionally, the role of PP2 in Mtb is associated with the AKT/NF-kB signaling pathway. Conclusion: PP2 inhibited Mtb infection in bronchial epithelial cells, by inhibiting Mtb-induced inflammatory reactions and activation of NLPR3 inflammasome. These effects may be exerted by suppressing the AKT/NF-kB pathway, which will provide a prospective treatment.

中文翻译：

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Polyphyllin II 抑制 NLPR3 炎症小体激活和结核分枝杆菌感染的人支气管上皮细胞的炎症反应

背景：全球范围内结核分枝杆菌 (Mtb) 支气管感染的患病率和严重程度正在增加。尽管进行了适当的结核病治疗，大多数患者仍然出现支气管狭窄，这往往导致残疾。Polyphyllin II (PP2) 是从重楼中提取的甾体皂苷。在本研究中，我们旨在探讨PP2对Mtb诱导的支气管感染进展的影响。方法：采用MTT和乳酸脱氢酶（LDH）试剂盒测定PP2对细胞活力的影响。分别通过 RT-qPCR 和 ELISA 阐明肿瘤坏死因子 (TNF)-α、白细胞介素 (IL)-1β 和 IL-8 的 mRNA 和蛋白水平。NLR家族pyrin结构域包含3（NLRP3）相关炎症小体（NLRP3、IL-1β和cleaved-caspase-1）的表达以及蛋白激酶B（AKT）/核因子-κB（NF-kB）的激活程度； p-AKT 和 p-NF-κB）通过蛋白质印迹法检测。结果：0、1、5和10 μM的PP2对16HBE细胞几乎没有细胞毒性。PP2 抑制 Mtb 诱导的细胞增殖并降低 LDH 水平。我们进一步发现PP2可以抑制Mtb诱导的炎症反应和NLPR3炎症小体的激活。此外，PP2 在 Mtb 中的作用与 AKT/NF-kB 信号通路相关。结论：PP2通过抑制Mtb诱导的炎症反应和NLPR3炎症小体的激活，从而抑制Mtb对支气管上皮细胞的感染。这些作用可能是通过抑制 AKT/NF-kB 通路来发挥的，这将提供一种前瞻性的治疗。