Toronto Lung Transplant Program, University Health Network, Toronto, Ontario, Canada; Institute of Pulmonary Medicine, Sheba Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel.
Toronto Lung Transplant Program, University Health Network, Toronto, Ontario, Canada.
J Heart Lung Transplant. 2023 Aug;42(8):1152-1160. doi: 10.1016/j.healun.2023.03.009. Epub 2023 Mar 23.
Airway epithelial injury is thought to be a key event in the pathogenesis of chronic lung allograft dysfunction (CLAD). We investigated whether markers of epithelial activity and injury in bronchoalveolar lavage fluid (BAL) correlate with CLAD diagnosis and major CLAD phenotypes: bronchiolitis obliterans syndrome (BOS) vs restrictive allograft syndrome (RAS)-related phenotypes (including RAS, mixed phenotype, and all other patients with RAS-like opacities).
CLAD status and phenotypes were retrospectively determined in a cohort of all consecutive adult, first, bilateral lung transplants performed 2010-2015, with available BAL samples. All patients with RAS-related phenotypes were included and 1:1 matched with BOS patients based on the time from transplant to CLAD-onset. Subjects who were CLAD-free for a minimum of 3 years post-transplant were 1:1 matched to CLAD patients and included as controls. Proteins that maintain the barrier function of the airway epithelial mucosa (club cell secretory protein, surfactant protein-D and epithelial mucins: MUC1, MUC5AC, MUC5B, MUC16), as well as epithelial cell death markers (M30&M65 representing epithelial cell apoptosis and overall death, respectively), were measured in BAL obtained within 6-months post CLAD onset using a double-sandwich ELISA or a multiplex bead assay. Protein levels were compared using Mann-Whitney-U-test. Association between protein levels and graft survival was assessed using Cox proportional hazards models, adjusted for CMV serology mismatch status and CLAD phenotype.
Fifty-four CLAD (27 BOS, 11 RAS, 7 mixed, 9 others with RAS-like opacities) patients and 23 CLAD-free controls were included. Median BAL levels were significantly higher in patients with CLAD compared to CLAD-free controls for M30 (124.5 vs 88.7 U/L), MUC1 (6.8 vs 3.2 pg/mL), and MUC16 (121.0 vs 30.1 pg/mL). When comparing CLAD phenotypes, M30 was significantly higher in patients with RAS-related phenotypes than BOS (160.9 vs 114.6 U/L). In multivariable models, higher M30 and MUC5B levels were associated with decreased allograft survival after CLAD onset independent of phenotype (p < 0.05 for all).
Airway epithelial mucins and cell death markers are enhanced in the BAL of patients with CLAD and can assist in differentiating between CLAD phenotypes and post-CLAD outcomes. Abnormal airway mucin expression and epithelial cell death may be involved in the pathogenesis of CLAD, and therefore their detection may aid in future selection of targeted therapies.
气道上皮损伤被认为是慢性肺移植物功能障碍（CLAD）发病机制中的关键事件。我们研究了支气管肺泡灌洗液（BAL）中上皮活性和损伤标志物是否与 CLAD 诊断和主要 CLAD 表型相关：闭塞性细支气管炎综合征（BOS）与限制性移植物综合征（RAS）相关表型（包括 RAS、混合表型和所有其他具有 RAS 样混浊的患者）。
回顾性确定了 2010-2015 年期间进行的所有连续成年、双侧肺移植的队列中的 CLAD 状态和表型，并获得了 BAL 样本。纳入了所有具有 RAS 相关表型的患者，并根据从移植到 CLAD 发作的时间与 BOS 患者进行了 1:1 匹配。在移植后至少 3 年 CLAD 无复发的患者与 CLAD 患者进行了 1:1 匹配，并作为对照纳入。使用双夹心 ELISA 或多重珠粒测定法，在 CLAD 发作后 6 个月内测量 BAL 中维持气道上皮粘膜屏障功能的蛋白质（分泌蛋白 CC16、表面活性蛋白-D 和上皮粘蛋白：MUC1、MUC5AC、MUC5B、MUC16）以及上皮细胞死亡标志物（M30&M65 分别代表上皮细胞凋亡和总死亡）。使用曼-惠特尼 U 检验比较蛋白水平。使用 Cox 比例风险模型评估蛋白水平与移植物存活率之间的关联，该模型调整了巨细胞病毒血清学错配状态和 CLAD 表型。
54 例 CLAD（27 例 BOS、11 例 RAS、7 例混合、9 例其他具有 RAS 样混浊）患者和 23 例 CLAD 无复发的对照组纳入研究。与 CLAD 无复发的对照组相比，CLAD 患者的 BAL 中 M30（124.5 与 88.7 U/L）、MUC1（6.8 与 3.2 pg/mL）和 MUC16（121.0 与 30.1 pg/mL）水平显著升高。在比较 CLAD 表型时，RAS 相关表型患者的 M30 明显高于 BOS 患者（160.9 与 114.6 U/L）。在多变量模型中，M30 和 MUC5B 水平升高与 CLAD 发作后移植物存活率降低相关，独立于表型（所有 P<0.05）。
CLAD 患者的 BAL 中气道上皮粘蛋白和细胞死亡标志物增加，并有助于区分 CLAD 表型和 CLAD 后结局。气道粘蛋白表达异常和上皮细胞死亡可能参与 CLAD 的发病机制，因此其检测可能有助于未来选择靶向治疗。
