Jillian M Piaggione, MD1, Lee-Ann M Murata, MSc2, Catherine F Uyehara, PhD2, Dao H Ho, PhD2. 1Department of General Surgery, Tripler Army Medical Center, 2Department of Clinical Investigation, Tripler Army Medical Center
Objectives. Trauma accounts for ~50% of combat-related deaths. Rapid blood loss from trauma can lead to hemorrhagic shock resulting in organ damage. Renal function is greatly reduced during shock, and dysfunction is observed long after recovery. Fluid resuscitation and vasopressors improve acute management of shock; however, long-term prognosis of vascular and renal function under different resuscitation strategies remains unclear. Epigenetic processes underlie many long-term physiological changes, and may play a role in resuscitation effects on renal function. Maintenance of kidney function depends heavily on vascular integrity, thus we aim to investigate epigenetic changes in the renal artery with the goal of elucidating novel therapeutic targets to improve prognosis. The specific objective of this study was to investigate regulation of epigenetic enzymes responsible for modification of chromatin in renal artery of a pig model of hemorrhage and saline resuscitation with and without vasopressin administration.
Methods. Adult pigs were anesthetized and hemodynamically monitored while subjected to hemorrhage (n=10), or maintained as non-hemorrhaged controls (n=6). One hour post-hemorrhage, animals were resuscitated with saline up to 2x shed blood volume (n=5), or with saline plus vasopressin infusion (n=5). Animals were euthanized 4-5 hours post-hemorrhage, and renal arteries collected. Gene array platform was used to detect expression of 84 chromatin remodeling enzymes.
Results. Saline+vasopressin infusion significantly increased mean arterial pressures compared to saline only resuscitation (71.80±8.60 versus 54.40±5.30mmHg, p<0.05). Renal vascular resistance of pigs after saline+vasopressin was elevated compared to non-hemorrhaged controls (0.20±0.04 versus 0.097±0.01mmHg·min/l, p<0.05), indicating differences in vascular function. Notably, saline+vasopressin resuscitation upregulated expression of histone deacetylases (HDAC2, HDAC4, HDAC9, HDAC11), SET domain containing methyltransferases (NDS1, SETD7, SETD8, SETDB2), methyltransferases (EZH2, PRMT5), and demethylases (KDM5B, KDM6B). In contrast, saline resuscitation upregulated expression of SETD4, and protein kinase NEK6. In both resuscitation groups, LOC100739818, protein kinase RPS6KA3 and ubiquitinase USP16 were upregulated, while SET1B was downregulated.
Conclusions. We are the first to show that within hours after resuscitation, expression of vascular epigenetic enzymes is dramatically altered. In contrast to resuscitation with saline only, vasopressin infusion predominantly altered HDACs and SETDs, suggesting epigenetic regulation of vascular physiology due to altered chromatin acetylation and methylation states. Upregulation of HDACs is known to cause vascular instability, while the role of SETDs in vascular integrity is currently unknown. Epigenetic modifications are stable for months to years, thus epigenetic modification unique to different resuscitation strategies may have differential impact on long-term prognosis of renal function.
Presented at the SAGES 2017 Annual Meeting in Houston, TX.
Abstract ID: 86594
Program Number: MSS03
Presentation Session: Full-Day Military Surgical Symposium – Basic Science Presentations
Presentation Type: MSSPodium