Hemorrhage-inducedIL-1R pathway in lung is suppressed by 3,5-bis(2-fluorobenzylidine)-4-piperidone (EF24) in a rat model of hypovolemic shock

Inflammation is an innate and protective immune response to a tissue injury in normal circumstances. However, unresolved, generalized and prolonged inflammation is detrimental to the well-being of the host. Exaggerated inflammation has been identified as a culprit in the pathogenesis of multiple organ dysfunction syndrome (MODS) in the victims of hemorrhagic shock and ischemia/reperfusion injury [1–3]. At cellular level, the response to inflammation is manifested by recruitment of immune cells, such as neutrophils, monocytes and dendritic cells (DCs). These cells are equipped with cell surface surveillance sensors, mainly belonging to the members of interleukin-1 receptor (IL-1R) superfamily. Upon stimulation, they recruit adaptor proteins to initiate a molecular cascade culminating into the secretion of effector cytokines, such as TNF-α and IL-6 [4, 5]. IL-1R members play a significant role in hemorrhagic shock because of their ability to interact with damage–associated molecular patterns (DAMPs) released during trauma and blood loss[6]. IL-1R superfamily comprises of receptors for IL-1 and IL-18, TLRs, single immunoglobulin IL-1R-related (SIGIRR), and an orphan receptor suppression of tumorigenicity 2 (ST2) [7–9]. They are characterized by a conserved cytosolic domain called the Toll–IL-1R (TIR) domain which activates some of the common signaling pathways. These members of IL-1R superfamily could also be classified depending on their pro- and anti-inflammatory role in the entire signaling process. Whereas IL-1R2, soluble ST2 (sST2), and SIGIRR are considered as negative regulators of inflammation, all other members of the IL-1R superfamily are pro-inflammatory. The downstream pro-inflammatory effects of IL-1R signaling are mediated by a transcription element nuclear factor-kappa B (NF-κB) [10]. Considering the diversity in theIL-1 superfamily members and their significance in perpetuating inflammation in trauma and hemorrhage, they are attractive adjunct targets in resuscitation approaches [11–13]. The objective of the presented work was to investigate the anti-inflammatory action of 3,5-bis(2-fluorobenzylidine)-4-piperidone (also known as EF24, Fig. 1a) in a hemorrhagic shock model. Originally synthesized as a synthetic curcuminoid [14], EF24 is a synthetic Michael’s acceptor which inhibits the catalytic activity of IkappaB kinase (IKK), an enzyme responsible for the phosphorylation and degradation of NF-κB inhibitory protein IkappaB[15, 16]. We recently reported that EF24 inhibits lipopolysaccharide (LPS)-induced maturation, NF-κB, and production of pro-inflammatory cytokines in DCs[15]. Here, we studied the effect of EF24 on the expression of IL-1R members, namely IL-1R1, TLR4, ST-2, and SIGIRR, in lung tissue of rats subjected to 40% blood loss. Figure 1 EF24 suppresses hemorrhage-induced phospho-NF-κB p65 expression in lung tissues of rats subjected to sham surgery (Ctrl), hemorrhage (Hem), and hemorrhage with EF24 treatment (Hem+EF24). To demonstrate equal loading, the membranes was stripped ...