title: Selective histone deacetylase 6 inhibition prolongs survival in a lethal two-hit model.
abstract: BACKGROUND
  Hemorrhagic shock (HS) followed by a subsequent insult ("second hit") often initiates an exaggerated systemic inflammatory response and multiple organ failure. We have previously demonstrated that valproic acid, a pan histone deacetylase inhibitor, could improve survival in a rodent "two-hit" model. In the present study, our goal was to determine whether selective inhibition of histone deacetylase 6 with Tubastatin A (Tub-A) could prolong survival in a two-hit model where HS was followed by sepsis from cecal ligation and puncture (CLP).
  
  
  METHODS
  C57Bl/6J mice were subjected to sublethal HS (30% blood loss) and then randomly divided into two groups (n = 13 per group) such as Tub-A group (treatment) and vehicle (VEH) group (control). The Tub-A group was given an intraperitoneal injection of Tub-A (70 mg/kg) dissolved in dimethyl sulfoxide (DMSO). The VEH group was injected with DMSO (1 μl/g body weight). After 24 h, all mice were subjected CLP followed immediately by another dose of Tub-A or DMSO. Survival was monitored for 10 d. In a parallel study, peritoneal irrigation fluid and liver tissue from Tub-A- or DMSO-treated mice were collected 3 h after CLP. Enzyme-linked immunosorbent assay was performed to quantify activity of the myeloperoxidase and concentrations of tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6) in the peritoneal irrigation fluid. RNA was isolated from the liver tissue, and real-time polymerase chain reaction was performed to measure relative messenger RNA levels of TNF-α and IL-6.
  
  
  RESULTS
  Treatment with Tub-A significantly improved survival compared with that of the control (69.2% versus 15.4%). In addition, Tub-A significantly suppressed myeloperoxidase activity (169.9 ± 8.4 ng/mL versus 70.4 ± 17.4 ng/mL; P < 0.01) and reduced levels of cytokines TNF-α and IL-6 in the peritoneal fluid (TNF-α: 105.7 ± 4.7 versus 7.4 ± 2.4 pg/mL; IL-6: 907.4 ± 2.3 versus 483.6 ± 1.6 pg/mL; P < 0.01) compared with those in the VEH control. Gene expression measured by real-time polymerase chain reaction confirmed that Tub-A inhibits transcription of TNF-α and IL-6.
  
  
  CONCLUSIONS
  Tub-A treatment significantly improves survival, attenuates inflammation, and downregulates TNF-α and IL-6 gene expression in a rodent two-hit model.
authors.affiliation: Department of Surgery, University of Michigan Hospital, Ann Arbor, Michigan.
authors.forename: Xin
authors.initials: X
authors.lastname: Cheng
authors.affiliation: Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China.
authors.forename: Zhengcai
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Surgery, University of Michigan Hospital, Ann Arbor, Michigan.
authors.forename: Baoling
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Surgery, University of Michigan Hospital, Ann Arbor, Michigan.
authors.forename: Ting
authors.initials: T
authors.lastname: Zhao
authors.affiliation: Department of Surgery, University of Michigan Hospital, Ann Arbor, Michigan.
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Surgery, University of Michigan Hospital, Ann Arbor, Michigan. Electronic address: alamh@med.umich.edu.
authors.forename: Hasan B
authors.initials: HB
authors.lastname: Alam
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D000073864:Histone Deacetylase 6; D056572:Histone Deacetylase Inhibitors / Q000627:therapeutic use*; D006655:Histone Deacetylases; D006877:Hydroxamic Acids / Q000627:therapeutic use*; D007211:Indoles / Q000627:therapeutic use*; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009102:Multiple Organ Failure / Q000209:etiology / Q000378:metabolism / Q000401:mortality / Q000517:prevention & control*; D011897:Random Allocation; D060888:Real-Time Polymerase Chain Reaction; D018805:Sepsis / Q000150:complications / Q000188:drug therapy* / Q000378:metabolism / Q000401:mortality; D012771:Shock, Hemorrhagic / Q000150:complications / Q000188:drug therapy* / Q000378:metabolism / Q000401:mortality; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D007211:Indoles; C553587:tubastatin A; C499033:Hdac6 protein, mouse; D000073864:Histone Deacetylase 6; D006655:Histone Deacetylases
keywords: HDAC6; Hemorrhagic shock; Mouse; Tubastatin A; Two-hit
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