Department of Surgery, University of Virginia School of Medicine, Charlottesville, Virgina.
Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia.
Ann Thorac Surg. 2022 Apr;113(4):1256-1264. doi: 10.1016/j.athoracsur.2021.04.052. Epub 2021 May 4.
Lung ischemia-reperfusion injury (IRI), involving severe inflammation and edema, is a major cause of primary graft dysfunction after transplant. Activation of transient receptor potential vanilloid 4 (TRPV4) channels modulates vascular permeability. Thus, this study tests the hypothesis that endothelial TRPV4 channels mediate lung IRI.
A left lung hilar-ligation model was used to induce lung IR in C57BL/6 wild-type (WT), Trpv4, tamoxifen-inducible endothelial Trpv4 knockout (Trpv4), and tamoxifen-treated control (Trpv4) (n ≥ 6 mice/group). WT mice were also treated with GSK2193874 (WT+GSK219), a TRPV4-specific inhibitor (1 mg/kg). Partial pressure of arterial oxygen, edema (wet-to-dry weight ratio), compliance, neutrophil infiltration, and cytokine concentrations in bronchoalveolar lavage fluid were assessed. Pulmonary microvascular endothelial cells were characterized in vitro after exposure to hypoxia-reoxygenation.
Compared with WT, partial pressure of arterial oxygen after IR was significantly improved in Trpv4 mice (133.1 ± 43.9 vs 427.8 ± 83.1 mm Hg, P < .001) and WT+GSK219 mice (133.1 ± 43.9 vs 447.0 ± 67.6 mm Hg, P < .001). Pulmonary edema and neutrophil infiltration were also significantly reduced after IR in Trpv4 and WT+GSK219 mice vs WT. Trpv4 mice after IR demonstrated significantly improved oxygenation vs control (109.2 ± 21.6 vs 405.3 ± 41.4 mm Hg, P < .001) as well as significantly improved compliance and significantly less edema, neutrophil infiltration, and proinflammatory cytokine production (tumor necrosis factor-a, chemokine [C-X-C motif] ligand 1, interleukin 17, interferon-γ). Hypoxia-reoxygenation-induced permeability and chemokine (C-X-C motif) ligand 1 expression by pulmonary microvascular endothelial cells were significantly attenuated by TRPV4 inhibitors.
Endothelial TRPV4 plays a key role in vascular permeability and lung inflammation after IR. TRPV4 channels may be a promising therapeutic target to mitigate lung IRI and decrease the incidence of primary graft dysfunction after transplant.
肺缺血再灌注损伤（IRI）涉及严重的炎症和水肿，是移植后原发性移植物功能障碍的主要原因。瞬时受体电位香草酸 4（TRPV4）通道的激活可调节血管通透性。因此，本研究旨在验证内皮细胞 TRPV4 通道是否介导肺 IRI。
采用左侧肺门结扎模型诱导 C57BL/6 野生型（WT）、Trpv4、他莫昔芬诱导型内皮细胞 Trpv4 敲除（Trpv4）和他莫昔芬处理对照（Trpv4）（每组 n≥6 只小鼠）肺 IRI。WT 小鼠还接受 TRPV4 特异性抑制剂 GSK2193874（WT+GSK219，1mg/kg）处理。评估动脉血氧分压、水肿（湿干重比）、顺应性、中性粒细胞浸润和支气管肺泡灌洗液中的细胞因子浓度。在体外对缺氧再复氧后的肺微血管内皮细胞进行特征描述。
与 WT 相比，IR 后 Trpv4 小鼠的动脉血氧分压明显改善（133.1±43.9 与 427.8±83.1mmHg，P＜0.001），WT+GSK219 小鼠也明显改善（133.1±43.9 与 447.0±67.6mmHg，P＜0.001）。IR 后，Trpv4 和 WT+GSK219 小鼠的肺水肿和中性粒细胞浸润也明显低于 WT。IR 后，Trpv4 小鼠的氧合作用明显优于对照组（109.2±21.6 与 405.3±41.4mmHg，P＜0.001），顺应性明显改善，水肿、中性粒细胞浸润和促炎细胞因子（肿瘤坏死因子-α、趋化因子[C-X-C 基序]配体 1、白细胞介素 17、干扰素-γ）生成明显减少。TRPV4 抑制剂显著减弱缺氧复氧诱导的肺微血管内皮细胞通透性和趋化因子（C-X-C 基序）配体 1 的表达。
内皮细胞 TRPV4 在 IRI 后的血管通透性和肺炎症中起关键作用。TRPV4 通道可能是减轻肺 IRI 和降低移植后原发性移植物功能障碍发生率的有希望的治疗靶点。
