title: Inhibition of histone deacetylase 6 restores intestinal tight junction in hemorrhagic shock.
abstract: We recently discovered that Tubastatin-A, a histone deacetylase (HDAC6) inhibitor, can improve survival in a rodent model of hemorrhagic shock (HS), but mechanisms remain poorly defined. In this study, we investigated whether Tubastatin-A could protect intestinal tight junction (TJ) in HS.
  
  
  
  In an in-vivo study with Wistar-Kyoto rats, the rats underwent HS (40% blood loss) followed by Tubastatin-A (70 mg/kg) treatment, without fluid resuscitation. The experimental groups were (1) sham (no hemorrhage, no treatment), (2) control (hemorrhage, without treatment), and (3) treatment (hemorrhage with Tubastatin-A administration). Six hours after hemorrhage, ileum was harvested. Whole cell lysate were analyzed for acetylated α-tubulin (Ac-tubulin), total tubulin, acetylated histone 3 at lysine 9 (Ac-H3K9), β-actin, claudin-3 and zonula occludens 1 (ZO-1) proteins by Western blot. Histological effects of Tubastatin-A on small bowel were examined. In an in-vitro study, human intestinal epithelial cells (Caco-2) were divided into three groups: (1) sham (normoxia), (2) control (anoxia, no treatment), and (3) treatment (anoxia, treatment with Tubastatin-A). After 12 hours in an anoxia chamber, the cells were examined for Ac-tubulin and Ac-H3K9, cellular viability, cytotoxicity, claudin-3 and ZO-1 protein expression, and transwell permeability study.
  
  
  
  Tubastatin-A treatment significantly attenuated HS-induced decreases of Ac-tubulin, Ac-H3K9, ZO-1 and claudin-3 proteins in small bowel in-vivo (p < 0.05). In cultured Caco-2 cells, anoxia significantly decreased cellular viability (p < 0.001) and increased cytotoxicity (p < 0.001) compared to the sham group, while Tubastatin-A treatment offered significant protection (p < 0.0001). Moreover, expression of claudin-3 was markedly decreased in vitro compared to the sham group, whereas this was significantly attenuated by Tubastatin-A (p < 0.05). Finally, anoxia markedly increased the permeability of Caco-2 monolayer cells (p < 0.05), while Tubastatin-A significantly attenuated the alteration (p < 0.05).
  
  
  
  Inhibition of HDAC6 can induce Ac-tubulin and Ac-H3K9, promote cellular viability, and prevent the loss of intestinal tight junction proteins during HS and anoxia.
authors.affiliation: From the Department of Surgical ICU (Z.C.), Beijing Hospital, Beijing, China; Department of Cardiothoracic Surgery (W.H.), Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China; Department of Surgery (Z.C., Y.L., W.H., B.L., I.H., T.B., B.P., Y.L., V.C.N., P.G., H.B.A.), University of Michigan Hospital, Ann Arbor, Michigan; The First Hospital (Y.L.), China Medical University, Shengyang, China; and Department of Pathology (X.D.), Loyola University Medical Center, Maywood, Illinois.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Chang
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: He
authors.forename: Baoling
authors.initials: B
authors.lastname: Liu
authors.forename: Xiuzhen
authors.initials: X
authors.lastname: Duan
authors.forename: Ihab
authors.initials: I
authors.lastname: Halaweish
authors.forename: Ted
authors.initials: T
authors.lastname: Bambakidis
authors.forename: Baihong
authors.initials: B
authors.lastname: Pan
authors.forename: Yingjian
authors.initials: Y
authors.lastname: Liang
authors.forename: Vahagn C
authors.initials: VC
authors.lastname: Nikolian
authors.forename: Patrick
authors.initials: P
authors.lastname: Georgoff
authors.forename: Hasan B
authors.initials: HB
authors.lastname: Alam
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004195:Disease Models, Animal; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006877:Hydroxamic Acids / Q000494:pharmacology*; D007085:Ilium / Q000187:drug effects*; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012771:Shock, Hemorrhagic / Q000188:drug therapy*; D019108:Tight Junctions / Q000187:drug effects*
chemical_list: D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D007211:Indoles; C553587:tubastatin A