Proteomics reveals region-specific hemostatic alterations in response to mechanical ventilation in a preterm lamb model of lung injury.

Introduction: Preterm infants often require assisted ventilation, however ventilation when applied to the immature lung can initiate ventilator-induced lung injury (VILI). The biotrauma which underscores VILI is largely undefined, and is likely to involve vascular injury responses, including hemostasis. We aimed to use a ventilated, preterm lamb model to: (1) characterize regional alterations in hemostatic mediators within the lung and (2) assess the functional impact of protein alterations on hemostasis by analyzing temporal thrombin generation.

Materials And Methods: Preterm lambs delivered at 124 to 127 days gestation received 90 min of mechanical ventilation (positive end-expiratory pressure = 8 cm HO, V = 6-8 ml/kg) and were compared with unventilated control lambs. At study completion, lung tissue was taken from standardized nondependent and gravity-dependent regions, and Orbitrap-mass spectrometry and KEGG were used to identify and map regional alterations in hemostasis pathway members. Temporal alterations in plasma thrombin generation were assessed.

Results: Ventilation was distributed towards the nondependent lung. Significant changes in hemostatic protein abundance, were detected at a two-fold higher rate in the nondependent lung when compared with the gravity-dependent lung. Seven proteins were uniquely altered in non-dependent lung (SERPINA1, MYL12A, RAP1B, RHOA, ITGB1, A2M, GNAI2), compared with a single proteins in gravity-dependent lung (COL1A2). Four proteins were altered in both regions (VTN, FGG, FGA, and ACTB). Tissue protein alterations were mirrored by plasma hypocoagulability at 90-minutes of ventilation.

Conclusions: We observed regionally specific, hemostatic alterations within the preterm lung together with disturbed fibrinolysis following a short period of mechanical ventilation.