Division of Trauma, Emergency Surgery & Surgical Critical Care, Department of Surgery, Massachusetts General Hospital/Harvard Medical School, Boston, MA.
Department of Surgery, University of Michigan Hospital, Ann Arbor, MI.
Surgery. 2014 Aug;156(2):235-42. doi: 10.1016/j.surg.2014.03.033. Epub 2014 Jun 16.
An overproduction of corticosterone during severe sepsis results in increased apoptosis of immune cells, which may result in relative immunosuppression and an impaired ability to fight infections. We have previously demonstrated that administration of tubastatin A, a selective inhibitor of histone deacetylase-6 (HDAC6), improves survival in a lethal model of cecal ligation and puncture (CLP) in mice. The purpose of this study was to characterize the effects of this treatment on sepsis-induced stress responses and immune function.
C57BL/6J mice were subjected to CLP, and 1 hour later given an intraperitoneal injection of either tubastatin A dissolved in dimethyl sulfoxide (DMSO), or DMSO only. Blood samples were collected to measure the levels of circulating corticosterone and adrenocorticotropic hormone (ACTH). Thymus and long bones (femur and tibia) were subjected to hematoxylin and eosin staining, and immunohistochemistry was utilized to detect cleaved-caspase 3 in the splenic follicles as a measure of cellular apoptosis.
All vehicle-treated CLP animals died within 3 days, and displayed increased corticosterone and decreased ACTH levels compared with the sham-operated group. These animals also developed atrophy of thymic cortex with a marked depletion of thymocytes. Tubastatin A treatment significantly attenuated the stress hormone abnormalities. Treated animals also had significantly lower percentages of thymic atrophy (95.0 ± 5.0 vs 42.5 ± 25.3; P = .0366), bone marrow depletion and atrophy (58.3 ± 6.5 vs 25.0 ± 14.4%; P = .0449), and cellular apoptosis in the splenic follicles (41.2 ± 3.7 vs 28.5 ± 4.3 per 40× field; P = .0354).
Selective inhibition of HDAC6 in this lethal septic model was associated with a significant blunting of the stress responses, with attenuated thymic and bone marrow atrophy, and decreased splenic apoptosis. Our findings identify a novel mechanism behind the survival advantage seen with tubastatin A treatment.
严重脓毒症期间皮质酮的过度产生导致免疫细胞凋亡增加，这可能导致相对免疫抑制和抗感染能力受损。我们之前的研究表明，选择性组蛋白去乙酰化酶-6（HDAC6）抑制剂 tubastatin A 的给药可改善盲肠结扎和穿刺（CLP）致死性小鼠模型的存活率。本研究的目的是描述这种治疗对脓毒症应激反应和免疫功能的影响。
C57BL/6J 小鼠接受 CLP 后 1 小时，给予 tubastatin A 溶于二甲基亚砜（DMSO）或仅 DMSO 的腹腔内注射。采集血样测量循环皮质酮和促肾上腺皮质激素（ACTH）水平。对胸腺和长骨（股骨和胫骨）进行苏木精和伊红染色，并利用免疫组化检测脾滤泡中的裂解型半胱天冬酶 3，作为细胞凋亡的指标。
所有用载体处理的 CLP 动物均在 3 天内死亡，与假手术组相比，皮质酮水平升高，ACTH 水平降低。这些动物还出现胸腺皮质萎缩，胸腺细胞明显耗竭。Tubastatin A 治疗显著减轻了应激激素异常。治疗组动物的胸腺萎缩百分比也显著降低（95.0 ± 5.0 比 42.5 ± 25.3；P =.0366），骨髓耗竭和萎缩（58.3 ± 6.5 比 25.0 ± 14.4；P =.0449），以及脾滤泡中的细胞凋亡（41.2 ± 3.7 比 28.5 ± 4.3 个/40×视野；P =.0354）。
在这种致命的脓毒症模型中，选择性抑制 HDAC6 与应激反应明显减弱、胸腺和骨髓萎缩减轻以及脾细胞凋亡减少有关。我们的发现确定了 tubastatin A 治疗的生存优势背后的新机制。
