Interleukin‐10 (IL‐10) exerts a wide spectrum of regulatory activities in the immune and inflammatory response. The aim of this study was to investigate the role of endogenous IL‐10 on the modulation of the secondary events in mice subjected to spinal cord injury induced by the application of vascular clips (force of 24 g) to the dura via a four‐level T5–T8 laminectomy. IL‐10 wild‐type mice developed severe spinal cord damage characterized by oedema, tissue damage and apoptosis (measured by Annexin‐V, terminal deoxynucleotidyltransferase‐mediated UTP end labeling staining, Bax, Bcl‐2, and Fas‐L expression). Immunohistochemistry demonstrated a marked increase of localization of TNF‐α, IL‐1β and S100β, while western blot analysis shown an increased immunoreactivity of inducible nitric oxide synthase in the spinal cord tissues. The absence of IL‐10 in IL‐10 KO mice resulted in a significant augmentation of all the above described parameters. We have also demonstrated that the genetic absence of IL‐10 worsened the recovery of limb function when compared with IL‐10 wild‐type mice group (evaluated by motor recovery score). Taken together, our results clearly demonstrate that the presence of IL‐10 reduces the development of inflammation and tissue injury events associated with spinal cord trauma.

Myrtucommulone (MC), a nonprenylated acylphloroglucinol contained in the leaves of myrtle (Myrtus communis), has been reported to suppress the biosynthesis of eicosanoids by inhibition of 5-lipoxygenase and cyclooxygenase-1 in vitro and to inhibit the release of elastase and the formation of reactive oxygen species in activated polymorphonuclear leukocytes. Here, in view of the ability of MC to suppress typical proinflammatory cellular responses in vitro, we have investigated the effects of MC in in vivo models of inflammation. MC was administered to mice intraperitoneally, and paw edema and pleurisy were induced by the subplantar and intrapleural injection of carrageenan, respectively. MC (0.5, 1.5, and 4.5 mg/kg i.p.) reduced the development of mouse carrageenan-induced paw edema in a dose-dependent manner. Moreover, MC (4.5 mg/kg i.p. 30 min before and after carrageenan) exerted anti-inflammatory effects in the pleurisy model. In particular, 4 h after carrageenan injection in the pleurisy model, MC reduced: 1) the exudate volume and leukocyte numbers; 2) lung injury (histological analysis) and neutrophil infiltration (myeloperoxidase activity); 3) the lung intercellular adhesion molecule-1 and P-selectin immunohistochemical localization; 4) the cytokine levels (tumor necrosis factor-␣ and interleukin-1␤) in the pleural exudate and their immunohistochemical localization in the lung; 5) the leukotriene B 4 , but not prostaglandin E 2 , levels in the pleural exudates; and 6) lung peroxidation (thiobarbituric acid-reactant substance) and nitrotyrosine and poly (ADP-ribose) immunostaining. In conclusion, our results demonstrate that MC exerts potent anti-inflammatory effects in vivo and offer a novel therapeutic approach for the management of acute inflammation.

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Permanent functional deficits following spinal cord injury (SCI) arise from both mechanical injury and from secondary tissue reactions involving inflammation. The mitogen-activated protein kinases (MAPKs) play a critical role in cell signaling and gene expression. MAPK family includes three major members: extracellular signal regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK), representing three different signaling cascades. Moreover, various studies have clearly shown that high-mobility group box 1 (HMGB1) protein is implicated as a putative danger signal involved in the pathogenesis of a variety of inflammatory conditions including autoimmunity, cancer, trauma and hemorrhagic shock, and ischemia-reperfusion injury. Recently, we have reported that the pineal secretory product melatonin exerts important anti-inflammatory effects in an experimental model of SCI induced by the application of vascular clips (force of 24 g) to the dura after a four-level T5-T8 laminectomy. However, no reports are available on the effect of melatonin on MAPK signaling pathways and HMGB1 expression in SCI. The aim of the present study was to evaluate whether the melatonin protective effect observed in SCI is related to the regulation of MAPK signaling pathways and HMGB1 in mice. In this study we demonstrate the efficacy of treatment with the melatonin in SCI in mice in reducing (a) motor recovery, (b) activation of MAPKs p38, JNK and ERK1/2, (c) tumor necrosis factor-alpha expression, and (d) expression of HMGB1. We propose that melatonin's ability to reduce SCI in mice is also related to a reduction in MAPK signaling pathways and HMGB1 expression.

Background and purpose: 5-lipoxygenase (5-LO) is the key enzyme in leukotriene (LT) biosynthesis from arachidonic acid (AA). Here, we examined the role of the 5-LO-product, cysteinyl-LT (Cys-LT), with a 5-LO inhibitor (zileuton) and a Cys-LT, receptor antagonist (montelukast), in the inflammatory response and tissue injury associated with spinal cord injury (SCI). Experimental approach: SCI was induced in mice by the application of vascular clips to the dura via a two-level T6 to T7 laminectomy for 1 min. Cord inflammation was assessed histologically and by measuring inflammatory mediators (ELISA) and apoptosis by annexin V, TUNEL, Fas ligand staining and Bax and Bcl-2 expression (immunohistochemistry and western blots). Motor function in hindlimbs was assessed by a locomotor rating scale, for 10 days after cord injury. Key results: SCI in mice resulted in tissue damage, oedema, neutrophil infiltration, apoptosis, tumour necrosis-a (TNF-a) and cyclooxygenase-2 (COX-2) expression, prostaglandin E 2 (PGE 2 ) and leukotriene B 4 (LTB 4 ) production, and extracellular signalregulated kinase 1/2 (ERK1/2) phosphorylation in injured tissue. Treatment of the mice with zileuton or montelukast reduced the spinal cord inflammation and tissue injury, neutrophil infiltration, TNF-a, COX-2 and pERK1/2 expression, PGE 2 and LTB 4 production, and apoptosis. In separate experiments, zileuton or montelukast significantly improved the recovery of limb function over 10 days. Conclusions and implications: Zileuton and montelukast produced a substantial reduction of inflammatory events associated with experimental SCI. Our data underline the important role of 5-LO and Cys-LT in neurotrauma.