J. ZHOU1,2, Y. Tian1,3, Q. Deng1,3, P. Chang1,2, A. M. Williams1, U. F. Bhatti1, B. E. Biesterveld1, B. Liu1, J. Zhang1, T. Wang2, Y. Li1, H. B. Alam1 1University Of Michigan,Department Of Surgery,Ann Arbor, MI, USA 2Peking University People’s Hospital,Trauma Center, Department Of Orthopedic And Traumatology,Beijing, BEIJING, China 3Central South University,Xiangya Hospital,Changsha, HUNAN, China
Introduction: The peptidylarginine deiminase (PAD) family consists of five isozymes (PADs 1, 2, 3, 4, and 6), which convert arginine into citrulline through protein citrullination. Our recent studies demonstrate that a pan-PAD inhibitor can improve survival in a rat model of hemorrhagic shock (HS). However, the impact of specific PAD isozyme inhibition in improving survival has not been well studied. In this study, we sought to determine whether selective knockout (KO) of PAD2 could improve outcomes in models of HS.
Methods: I) Survival experiment: PAD2 KO and wild type (WT) mice (n=5/cohort) were subjected to lethal HS (55% volume hemorrhage), and survival was monitored for 10 days. II) Mechanistic studies: PAD2 KO and WT mice (n=3/group) were subjected to sub-lethal HS (30% volume hemorrhage), and the animals were euthanized 12 hours (h) later. Serum and tissues were harvested to analyze the inflammatory response and organ damage. Sham (no HS) was used as a control. Survival was assessed using Kaplan-Meier with log-rank testing, while analysis of variance was used for comparisons among groups.
Results:PAD2 KO mice demonstrated significantly better survival (Figure) compared to WT mice (100 vs 0%; P=0.0017). All the WT mice died within the first hour following HS. Serum IL-1β level was significantly decreased in PAD2 KO mice compared to WT mice 12 hours following sub-lethal HS. Furthermore, the degree of acute lung injury (pulmonary neutrophil infiltration and alveolar edema) and intestinal injury (breakdown of the microvilli) was significantly attenuated in the PAD2 KO mice compared to the WT mice (Figure).
Conclusion:This is the first study to demonstrate that knocking out the PAD2 enzyme improves survival in a rodent model of HS, and attenuates the markers of systemic inflammatory response, acute lung injury, and intestinal damage.
