Background: Acute lung injury (ALI) is a complication of hemorrhagic shock (HS). Histone deacetylase inhibitors, such as valproic acid (VPA), can improve survival after HS; however, their effects on late organ injury are unknown. Herein, we have investigated the effects of HS and VPA treatment on ALI and circulating cytokines that may serve as biomarkers for the development of organ injury.
Methods: Anesthetized Wistar-Kyoto rats (250-300 g) underwent 40% blood volume hemorrhage over 10 minutes followed by 30 minutes of unresuscitated shock and were treated with either VPA (300 mg/kg) or vehicle control. Blood samples were obtained at baseline, after shock, and before death (at 1, 4, and 20 hours; n = 3-4/timepoint/group). Serum samples were screened for possible biomarkers using a multiplex electrochemiluminescence detection assay, and results were confirmed using enzyme-linked immunosorbent assay (ELISA). In addition, lung tissue lysate was examined for chemokine and myeloperoxidase (MPO) levels as a marker for neutrophil infiltration and ALI. Lung cytokine-induced neutrophil chemoattractant-1 (CINC-1; a chemokine belonging to the interleukin-8 family that promotes neutrophil chemotaxis) mRNA levels were measured by real-time polymerase chain reaction studies.
Results: Serum screening revealed that hemorrhage rapidly altered levels of circulating CINC-1. ELISA confirmed that CINC-1 protein was significantly elevated in the serum as early as 4 hours and in the lung at 20 hours after hemorrhage, without any significant changes in CINC-1 mRNA expression. Lung MPO levels were also elevated at both 4 and 20 hours after hemorrhage. VPA treatment attenuated these changes.
Conclusion: Hemorrhage resulted in the development of ALI, which was prevented with VPA treatment. Circulating CINC-1 levels rose rapidly after hemorrhage, and serum CINC-1 levels correlated with lung CINC-1 and MPO levels. This suggests that circulating CINC-1 levels could be used as an early marker for the subsequent development of organ inflammation and injury.
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