Figure 4: RAGE mediated the HMGB1-induced transcytosis of albumin.

(A) RAGE, TLR2, and TLR4 expression was silenced successfully in MLVECs. The efficiency of gene silencing was tested by immunoblotting assay. (B,C) RAGE gene silencing decreased the HMGB1-induced endothelial transcytosis of albumin. After silencing the expression of the target gene, MLVECs were grown in 6-well plates (B) or in Transwell chambers (C). When the cells formed confluent monolayers, 0 or 100 ng/mL HMGB1 and ¹²⁵I-albumin were added for assays of albumin endocytosis (B) and transendothelial permeability (C). (D,E) The RAGE^+/+ and RAGE^−/− mouse lung samples were irrigated with a solution containing 0 or 100 ng/mL HMGB1 and ¹²⁵I-albumin via pulmonary artery perfusion. After 30 min, the lungs were perfused with Krebs solution, weighed and used for radioactivity detection (n = 6/each group). Then, the lungs were oven-dried. *Compared with the HMGB1-treated RAGE^+/+ group, p < 0.05.