Protective Effect of Suberoylanilide Hydroxamic Acid Against LPS-Induced Septic Shock in Rodents

Abstract

We have recently found that suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, improves survival in a lethal model of hemorrhagic shock in rats. The purpose of the present study was to determine whether SAHA treatment would prevent LPS-induced septic shock and improve the survival in a murine model. C57BL/6J mice were randomly divided into two groups. Experimental mice were given intraperitoneal SAHA (50 mg/kg) in vehicle dimethyl sulfoxide fluid (n = 10). The control mice (n = 10) received vehicle dimethyl sulfoxide only. They were injected with LPS (20 mg/kg, i.p.) 2 h later, and the animals from the treatment group were given a second dose of SAHA. Survival was monitored during the next 7 days. In a parallel study, mice treated with or without SAHA were subjected to LPS insult while normal (sham) mice serviced as controls. 1) Lungs were harvested at 3 and 48 h for analysis of gene expression and pathologic changes, respectively; 2) spleens were isolated for analysis of neutrophilic cell population. In addition, RAW264.7 mouse macrophages were cultured to assess the effects of SAHA on LPS-induced inflammation in vitro. All mice in the control group that were subjected to LPS challenge died in less than 48 h. However, SAHA-treated animals displayed a significantly higher 1-week survival rate (87.5%) compared with the control group (0%). Moreover, LPS insult decreased the acetylation of histone proteins (H2A, H2B, and H3), elevated the levels of TNF-alpha in vivo (circulation) and in vitro (culture medium), increased the neutrophilic cell population in the spleen, enhanced the expression of TNF-alpha and IL-1beta genes in lung tissue, and augmented the pulmonary neutrophil infiltration. In contrast, SAHA treatment markedly attenuated all of these LPS-induced alterations. We report for the first time that administration of SAHA (50 mg/kg) significantly attenuates a variety of inflammatory markers and improves long-term survival after a lethal LPS insult.

Surviving Lethal Septic Shock without Fluid Resuscitation in a Rodent Model

“…6 To assess whether SAHA post-treatment could protect the mice from LPS-induced septic shock, we injected SAHA (50 mg/ kg) into mice IP 2 hours after LPS insult and compared the survival rates between LPS and LPS + SAHA-treated animals. First, we established the lethal dose of LPS by performing a dose escalation study, and found that administration of LPS (lot #L6386) at 30 mg/kg (IP) resulted in 100% mortality (data not shown).…”

“…Mice were administrated this dose of LPS and 2 hours later, the SAHA group was given SAHA (50 mg/kg IP) in DMSO (n = 10), and the LPS group (n = 10) was injected with the same dose of DMSO (1 µL/g body weight). 6 All animals were observed to assess survival. As shown in Fig 4, all mice in the LPS group died in <24 hours.…”

“…In our previous study, cultured RAW264.7 macrophages were cotreated with LPS and SAHA; therefore, SAHA exposure was 2 hours earlier than the present project. Although the concentrations of LPS and SAHA remained constant, the earlier SAHA treatment decreased TNF-α protein secretion at 2 hours, 6 whereas SAHA posttreatment does not suppress cytokine production until 6 hours after LPS stimulation (or 4 hours after SAHA treatment; Fig 3). The delayed effect of SAHA on the TNF-α secretion may be due to retarded acetylation of proteins by SAHA.…”

Novel Pharmacological Treatment Attenuates Septic Shock and Improves Long-Term Survival

“…However, it remains unknown whether treatment with SAHA could improve survival from lethal septic shock. Our lab was the first to demonstrate that administration of SAHA improved survival in a rodent model of lipopolysaccharide (LPS)-induced lethal endotoxemia 9,10 . In this model, it decreased acute lung injury, and rapidly modulated several key genes involved in inflammation, with an attenuation of inflammatory mediators derived from both cellular and humoral arms of the innate immune system 11 .…”

Selective Inhibition of Histone Deacetylase-6 Alters the Composition of Circulating Blood Cells in a Lethal Septic Model

“…Our lab was the first to demonstrate that administration of suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor (HDACI), improved survival in lethal rodent models of lipopolysaccharide (LPS)-induced endotoxemia and cecal ligation and puncture (CLP)-induced severe sepsis [8][9][10] . Selective inhibition of HDAC6 with Tubastatin A displays even better survival outcomes in the lethal CLP-sepsis model and increases bacterial clearance in circulation (unpublished data).…”