Department of Cardiology, Affiliated Hospital of Jiangnan University, Wuxi, Jiangsu, P. R. China.
Department of Cardiology, First Affiliated Hospital of Nanjing Medicial University, Nanjing, Jiangsu, P. R. China.
Clin Transl Med. 2023 Jun;13(6):e1308. doi: 10.1002/ctm2.1308.
Chronic changes caused by a high-fat diet (HFD) may be associated with weakened lung function in obese patients. However, few studies have focused on the role of senescent cells in HFD-induced pulmonary fibrosis. This study aimed to determine whether (i) obesity causes the accumulation of aging cells in the lungs, (ii) p16 accumulation in aging epithelial cells or fibroblasts exacerbates long-term HFD-induced senescence-associated pulmonary fibrosis (SAPF) and (iii) p16 deletion or clearance of aging cells ameliorates HFD-induced SAPF through inactivation of the inflammasome and metabolic remodelling.
Twelve-month old male mice of p16 (hereafter p16) knockout (p16 ) and wild-type (WT), ApoE knockout (ApoE ) and ApoE p16 were fed a HFD to induce obesity, and the effects of treatment with the senolytic drug ABT263 or the SGK1 specific inhibitor EMD638683 on fibrosis, inflammaging, gene expression, integrin-inflammasome signalling and metabolism were examined. A549 and IMR-90 cells were transduced with p16-overexpressing adenovirus, and treated with palmitic and oleic acids (P&O) to induce steatosis in vitro.
We found that long-term HFD promoted the expression of p16 and the increase of senescent cells in the lung. P16 knockout or ABT263 treatment alleviated pulmonary fibrosis, the increase of senescent cells and senescence-associated secretory phenotype (SASP) in HFD-fed mice, as well as in P&O-treated A549 and IMR-90 cells. RNA sequencing and bioinformatics analyses revealed that p16 knockout inhibited activation of the integrin-inflammasome pathway and cellular glycolysis. Mass spectrometry, co-immunoprecipitation and GST pull-down assays demonstrated that p16 bound to the N-terminal of SGK1, thereby interfering with the interaction between the E3 ubiquitin ligase NEDD4L and SGK1, and subsequently inhibiting K48-polyubiquitin-dependent degradation of SGK1 mediated by the NEDD4L-Ubch5 complex. EMD638683 was found to alleviate HFD-induced pulmonary fibrosis and activation of the integrin-inflammasome pathway.
P16 accumulation promoted activation of integrin- inflammasome pathway and cell glycolysis by binding to the N- terminal of SGK1, intefering with the interaction between the E3 ubiquitin ligase NEDD4L and SGK1, thereby inhibiting K48- polyubiquitin- dependent degradation of SGK1 mediated by the NEDD4L-Ubch5 complex. ABT263 or EMD638683 could be used as potential drugs to treat pulmonary fibrosis in obese patients.
高脂肪饮食（HFD）引起的慢性变化可能与肥胖患者肺功能减弱有关。然而，很少有研究关注衰老细胞在 HFD 诱导的肺纤维化中的作用。本研究旨在确定（i）肥胖是否导致肺中衰老细胞的积累，（ii）衰老上皮细胞或成纤维细胞中 p16 的积累是否会加剧长期 HFD 诱导的衰老相关肺纤维化（SAPF），以及（iii）p16 缺失或清除衰老细胞是否通过失活炎性小体和代谢重塑来改善 HFD 诱导的 SAPF。
12 个月大的雄性 p16（以下简称 p16）敲除（p16 ）和野生型（WT）、载脂蛋白 E 敲除（ApoE ）和 ApoE p16 小鼠喂食 HFD 以诱导肥胖，并检查了 senolytic 药物 ABT263 或 SGK1 特异性抑制剂 EMD638683 对纤维化、炎性衰老、基因表达、整合素炎性小体信号和代谢的影响。将 p16 过表达腺病毒转导至 A549 和 IMR-90 细胞，并在体外用棕榈酸和油酸（P&O）处理以诱导脂肪变性。
我们发现，长期 HFD 促进了 p16 的表达和肺中衰老细胞的增加。p16 敲除或 ABT263 治疗减轻了 HFD 喂养小鼠的肺纤维化、衰老细胞和衰老相关 secretory 表型（SASP）的增加，以及 P&O 处理的 A549 和 IMR-90 细胞。RNA 测序和生物信息学分析表明，p16 敲除抑制了整合素炎性小体途径和细胞糖酵解的激活。质谱、免疫共沉淀和 GST 下拉实验表明，p16 与 SGK1 的 N 端结合，从而干扰了 E3 泛素连接酶 NEDD4L 与 SGK1 的相互作用，随后抑制了 NEDD4L-Ubch5 复合物介导的 K48-多聚泛素依赖的 SGK1 降解。发现 EMD638683 可减轻 HFD 诱导的肺纤维化和整合素炎性小体途径的激活。
p16 积累通过与 SGK1 的 N 端结合，促进整合素-炎性小体途径和细胞糖酵解的激活，干扰 E3 泛素连接酶 NEDD4L 与 SGK1 的相互作用，从而抑制 NEDD4L-Ubch5 复合物介导的 K48-多聚泛素依赖的 SGK1 降解。ABT263 或 EMD638683 可作为治疗肥胖患者肺纤维化的潜在药物。
