Aspirin, but Not Tirofiban Displays Protective Effects in Endotoxin Induced Lung Injury

Background Treatment of acute lung injury (ALI) remains an unsolved problem in intensive care medicine. Recruitment of neutrophils into the lungs, regarded as a key mechanism in progression of ALI, depends on signaling between neutrophils and platelets. Consequently we explored the effect of platelet-targeted aspirin and tirofiban treatment in endotoxin induced acute lung injury Methods C57Bl/6 mice were exposed to aerosolized LPS (500 mu g/ml) for 30min and treated with Aspirin (100 mu g/g bodyweight via intraperitoneal injection, 30 min before or 1 hour after LPS inhalation) or Tirofiban (0.5 mu g/g bodyweight via tail vein injection 30 min before or 1 hour after LPS inhalation). The count of alveolar, interstitial, and intravascular neutrophils was assessed 4h later by flow cytometry. Lung permeability changes were assessed by FITC-dextran clearance and protein content in the BAL fluid. Results Aspirin both before and after LPS inhalation reduced neutrophil influx into the lung and lung permeability indicating the protective role of Aspirin in ALI. Tirofiban, however, did not alter neutrophil recruitment after LPS inhalation. Release of platelet-derived chemokines CCL5 and PF4 and neutrophil extracellular traps was reduced by Aspirin but not by Tirofiban. Conclusion Aspirin, but not Tirofiban reduces neutrophil recruitment and displays protective effects during endotoxin induced lung injury

Aspirin, but not tirofiban prevents LPS-induced structural changes in the lung tissue.

<p><b>A:</b> Representative histological images of lungs from mice treated as indicated. <b>B:</b> Structural analyses of histological lung sections were made on based HE staining. * indicates significant difference compared to LPS-treated animals.</p

Expression of platelet-derived chemokines (CCL5 (RANTES) and CXCL4 (PF4)) and NET release.

<p>Mice were challenged with LPS via inhalation and sacrificed 4 hours later. Mice were treated with tirofiban ((0.5μg/ g bodyweight via tail vein injection) 30 min before or 1 hour after LPS exposure as indicated or with aspirin (100μg/g bodyweight via intraperitoneal injection) 30 min before or 1 hour after LPS exposure as indicated. <b>A:</b> Plasma concentration of PF4 (CXCL4) after treatment as indicated. <b>B:</b> Plasma concentration of CCL5 after treatment as indicated. <b>C and D:</b> NET formation in the plasma (<b>C</b>) and supernatant of the lyzed lung (<b>D</b>). Values are presented as percentage increase of absorbance in comparison to the control group. n = 6–8 for each bar. * indicates significant difference compared to LPS-treated animals.</p

Aspirin reduces LPS-induced acute lung injury by interference with neutrophil recruitment.

<p>Mice were challenged with LPS via inhalation and sacrificed 4 hours later. Mice were treated with aspirin (100μg/g bodyweight via intraperitoneal injection) 30 min before or 1 hour after LPS exposure as indicated. <b>A:</b> Quantification of alveolar (left), interstitial (middle), and intravascular neutrophils (right) in mice treated as indicated. <b>B:</b> protein concentration (left) and FITC-dextran clearance (right), in BAL fluids in mice treated as indicated. n = 6–8 for each bar. * indicates significant difference compared to LPS-treated animals.</p

Tirofiban displays no protective effect in LPS-induced acute lung injury.

<p>Mice were challenged with LPS via inhalation and sacrificed 4 hours later. Mice were treated with tirofiban ((0.5μg/ g bodyweight via tail vein injection) 30 min before or 1 hour after LPS exposure as indicated. <b>A:</b> Quantification of alveolar (left), interstitial (middle), and intravascular neutrophils (right) in mice treated as indicated. <b>B:</b> protein concentration (left) and FITC-dextran clearance (right), in BAL fluids in mice treated as indicated. n = 6–8 for each bar. * indicates significant difference compared to LPS-treated animals.</p