Efficient pulmonary lymphatic drainage is necessary for inflammation resolution in ARDS
Pu-hong Zhang, Wen-wu Zhang, Shun-shun Wang, Cheng-hua Wu, Yang-dong Ding, Xin-yi Wu, Fang Gao Smith, Yu Hao, Sheng-wei Jin
Pu-hong Zhang, Wen-wu Zhang, Shun-shun Wang, Cheng-hua Wu, Yang-dong Ding, Xin-yi Wu, Fang Gao Smith, Yu Hao, Sheng-wei Jin
View: Text | PDF
Research Article Pulmonology Vascular biology

Efficient pulmonary lymphatic drainage is necessary for inflammation resolution in ARDS

Abstract

The lymphatic vasculature is the natural pathway for the resolution of inflammation, yet the role of pulmonary lymphatic drainage function in sepsis-induced acute respiratory distress syndrome (ARDS) remains poorly characterized. In this study, indocyanine green–near infrared lymphatic living imaging was performed to examine pulmonary lymphatic drainage function in septic mouse models. We found that the pulmonary lymphatic drainage was impaired owing to the damaged lymphatic structure in sepsis-induced ARDS. Moreover, prior lymphatic defects by blocking vascular endothelial growth factor receptor-3 (VEGFR-3) worsened sepsis-induced lymphatic dysfunction and inflammation. Posttreatment with vascular endothelial growth factor-C (Cys156Ser) (VEGF-C156S), a ligand of VEGFR-3, ameliorated lymphatic drainage by rejuvenating lymphatics to reduce the pulmonary edema and promote draining of pulmonary macrophages and neutrophils to pretracheal lymph nodes. Meanwhile, VEGF-C156S posttreatment reversed sepsis-inhibited CC chemokine ligand 21 (CCL21), which colocalizes with pulmonary lymphatic vessels. Furthermore, the advantages of VEGF-C156S on the drainage of inflammatory cells and edema fluid were abolished by blocking VEGFR-3 or CCL21. These results suggest that efficient pulmonary lymphatic drainage is necessary for inflammation resolution in ARDS. Our findings offer a therapeutic approach to sepsis-induced ARDS by promoting lymphatic drainage function.

Authors

Pu-hong Zhang, Wen-wu Zhang, Shun-shun Wang, Cheng-hua Wu, Yang-dong Ding, Xin-yi Wu, Fang Gao Smith, Yu Hao, Sheng-wei Jin

×

Figure 4

Posttreatment with VEGF-C156S ameliorated pulmonary lymphatic drainage function by rejuvenating lymphatics in LPS-induced sepsis.

Options: View larger image (or click on image) Download as PowerPoint
Posttreatment with VEGF-C156S ameliorated pulmonary lymphatic drainage f...
(A) Procedure and timeline: Recombinant VEGF-C156S protein was administrated to an LPS-induced sepsis model 6 hours afterward. Then, the lung tissue and the pLNs were obtained at the 24th hour. (B) Lymphatic vessels were labeled with an immunofluorescence stain of VEGFR-3 (green) and Prox1-tdTomato signals (red). Scale bars for lung, 100 μm (left), 50 μm (right). Scale bar for pLNs, 50 μm. (C) Quantification of the percentage area coverage and the relative fluorescence intensity of lymphatic vessels in lungs (LPS = 9, LPS + VEGF-C156S = 9; representative data from 3 independent experiments). (D) Quantification of the percentage area coverage and the relative fluorescence intensity of lymphatic vessels in pLNs (LPS = 9, LPS + VEGF-C156S = 9; representative data from 3 independent experiments). (E) Scanning electron microscopy of the pulmonary lymphatic endothelium. Scale bar, 1 μm. (F and G) ICG was intratracheally poured into unilateral lung and quantified and presented as relative radiance at 0 hours, 24th hour, and 48th hour using IVIS. (H and I) The ICG clearance rate at the 24th hour and 48th hour (control n = 6, LPS n = 6, LPS + VEGF-C156S n = 6; representative data from 3 independent experiments). (J and K) At the 24th hour, ICG was intratracheally poured into unilateral lung. Fluorescence intensities of ICG were determined in pLNs at 30 minutes after the pour by IVIS and confocal microscopy (control n = 6, LPS n = 6, LPS + VEGF-C156S n = 6; representative data from 3 independent experiments). Scale bar, 200 μm. All n values refer to the number of mice used, and the error bars depict mean ± SD. P values were calculated by a 1-way ANOVA with Tukey’s multiple-comparison test.