Natural and engineered chemokine (C-X-C motif) receptor 4 agonists prevent acute respiratory distress syndrome after lung ischemia-reperfusion injury and hemorrhage.

We compared therapeutic properties of natural and engineered chemokine (C-X-C motif) receptor 4 (CXCR4) agonists in a rat acute respiratory distress syndrome (ARDS) model utilizing the PaO2 /FiO2 -ratio as a clinically relevant primary outcome criterion. Ventilated rats underwent unilateral lung ischemia from t = 0-70 min plus hemorrhage to a mean arterial blood pressure (MAP) of 30 mmHg from t = 40-70 min, followed by reperfusion/fluid resuscitation until t = 300 min. Natural CXCR4 agonists (CXCL12, ubiquitin) and engineered CXCL12 variants (CXCL121 , CXCL22 , CXCL12K27A/R41A/R47A, CXCL12 (3-68)) were administered within 5 min of fluid resuscitation. Animals treated with vehicle or CXCL12 (3-68) reached criteria for mild and moderate ARDS between t = 90-120 min and t = 120-180 min, respectively, and remained in moderate ARDS until t = 300 min. Ubiquitin, CXCL12, CXCL121 and CXCL122 prevented ARDS development. Potencies of CXCL12/CXCL121 /CXCL122 were higher than the potency of ubiquitin. CXCL12K27A/R41A/R47A was inefficacious. CXCL121  > CXCL12 stabilized MAP and reduced fluid requirements. CXCR4 agonists at doses that preserved lung function reduced histological injury of the post-ischemic lung and reduced mortality from 55 to 9%. Our findings suggest that CXCR4 protein agonists prevent development of ARDS and reduce mortality in a rat model, and that development of new engineered protein therapeutics with improved pharmacological properties for ARDS is possible.