Resolvins of the D series are generated from docosahexaenoic acid, which are enriched in fish oils and are believed to exert beneficial roles on diverse inflammatory disorders, including inflammatory bowel disease (IBD). In this study, we investigated the anti-inflammatory effects of the aspirin-triggered resolvin D1 (AT-RvD1), its precursor (17(R)-hydroxy docosahexaenoic acid [17R-HDHA]) and resolvin D2 (RvD2) in dextran sulfate sodium (DSS)- or 2,4,6-trinitrobenzene sulfonic acid-induced colitis. Our results showed that the systemic treatment with AT-RvD1, RvD2, or 17R-HDHA in a nanogram range greatly improved disease activity index, body weight loss, colonic damage, and polymorphonuclear infiltration in both colitis experimental models. Moreover, these treatments reduced colonic cytokine levels for TNF-α, IL-1β, MIP-2, and CXCL1/KC, as well as mRNA expression of NF-κB and the adhesion molecules VCAM-1, ICAM-1, and LFA-1. Furthermore, AT-RvD1, but not RvD2 or 17R-HDHA, depended on lipoxin A4 receptor (ALX) activation to inhibit IL-6, MCP-1, IFN-γ, and TNF-α levels in bone marrow-derived macrophages stimulated with LPS. Similarly, ALX blockade reversed the beneficial effects of AT-RvD1 in DSS-induced colitis. To our knowledge, our findings showed for the first time the anti-inflammatory effects of resolvins of the D series and precursor 17R-HDHA in preventing experimental colitis. We also demonstrated the relevant role exerted by ALX activation on proresolving action of AT-RvD1. Moreover, AT-RvD1 showed a higher potency than 17R-HDHA and RvD2 in preventing DSS-induced colitis. The results suggest that these lipid mediators possess a greater efficacy when compared with other currently used IBD therapies, such as monoclonal anti-TNF, and have the potential to be used for treating IBD.

Cannabinoid receptor 2 (CB2) activation is suggested to trigger the peroxisome proliferator-activated receptor-␥ (PPAR␥) pathway, and agonists of both receptors improve colitis. Recently, the plant metabolite (E)-␤-caryophyllene (BCP) was shown to bind to and activate CB2. In this study, we examined the antiinflammatory effect of BCP in dextran sulfate sodium (DSS)-induced colitis and analyzed whether this effect was mediated by CB2 and PPAR␥. Oral treatment with BCP reduced disease activity, colonic macro-and microscopic damage, myeloperoxidase and N-acetylglucosaminidase activities, and levels and mRNA expression of colonic tumor necrosis factor-␣, IL-1␤, interferon-␥, and keratinocyte-derived chemokine. Inflammatory bowel diseases (IBDs) are a group of chronic diseases that affect the gastrointestinal tract and have been mainly subdivided as ulcerative colitis and Crohn's disease. 1 The IBDs are characterized by a strong leukocyte activation and infiltration into the intestinal tissues, the release of proinflammatory cytokines 2 and enzymes, and the formation of reactive oxygen species. All of these events can induce an extensive and unbalanced activation of the mucosal immune system, driven by the commensal flora. 3 Recent evidence suggests a role for the cannabinoid system in IBD regulation. Cannabinoid receptors 1 and 2 (CB1 and CB2) are expressed in normal human colon 4,5 and are up-regulated in IBD colonic tissue. In addition, an enhanced level of endocannabinoids was found in biopsy specimens from patients with ulcerative colitis. 5 It is thought that CB1 activation results in a decrease of intestinal hypermotility and hypersecretion, whereas the activation of CB2 results in the inhibition of proinflammatory mediators. In addition, both CB2 and CB1 knockout mice are more susceptible to the development of experimental colitis, and the activation of these receptors is extremely important for the abrogation of intestinal inflammation. 6 The role of CB2, however, is directly involved with innate immune system, because CB2 is primarily expressed in immune cells, such as macrophages, CD4 ϩ and CD8 ϩ T cells, monocytes, and polymorphonuclear neutro-

Although neutrophils are strongly implicated in eliminating pathogens, excessive recruitment may cause tissue damage. Therefore, reducing cell influx during an inflammatory process may be a potential target for treating inflammatory bowel diseases (IBD). As CXCR2 is involved in neutrophil migration, this study aimed to evaluate whether the systemic therapeutic treatment with selective CXCR2 antagonist SB225002 ameliorates experimental colitis, which was induced in mice by 2,4,6-trinitrobenzene sulfonic acid (TNBS). After colitis establishment (24 h), mice were treated with SB225002. At later time-points, up to 72 h, mice were monitored for body weight loss and overall mortality. At the time of sacrifice, colonic tissues were scored for macro- and microscopic damage, and cytokine levels, myeloperoxidase (MPO) activity, and protein expression were analyzed. TNBS administration induced macro- and microscopic damage in colon tissue, leading in most cases to animal death. Curative treatment with SB225002 significantly reduced all of the parameters analyzed, leading to an improvement of inflammatory signs. SB225002 reduced neutrophil influx, MPO activity, IL-1beta, MIP-2, and keratinocyte-derived chemokine (KC) levels and the expression of vascular endothelial growth factor, inducible NO synthase, and cyclooxygenase-2 proteins into the colon tissue. Levels of IL-4 and IL-10 were increased significantly in the colons of animals treated with SB225002. Additionally, curative treatment with mouse anti-KC significantly reduced MPO activity and colonic damage. These results taken together demonstrate that a selective blockade of CXCR2 consistently reduced TNBS-induced colitis, suggesting that the use of SB225002 is a potential therapeutic approach for the treatment of IBD and other related inflammatory disorders.

The trigeminal nerve is the largest of all cranial nerves. It has three branches that provide the main sensory innervation of the anterior two-thirds of the head and face. Trigeminal neuralgia (TN) is characterized by sudden, severe, brief, and stabbing recurrent episodes of facial pain in one or more branches of the trigeminal nerve. Pain attacks can occur spontaneously or can be triggered by non-noxious stimuli, such as talking, eating, washing the face, brushing teeth, shaving, a light touch or even a cool breeze. In addition to pain attacks, a proportion of the patients also experience persistent background pain, which along with autonomic signs and prolonged disease duration, represent predictors of worse treatment outcomes. It is now widely accepted that the presence of a neurovascular compression at the trigeminal root entry zone is an anatomic abnormality with a high correlation with classical TN. However, TN may be related to other etiologies, thus presenting different and/or additional features. Since the 1960s, the anticonvulsant carbamazepine is the drug of choice for TN treatment. Although anti-epileptic drugs are commonly used to treat neuropathic pain in general, the efficacy of carbamazepine has been largely limited to TN. Carbamazepine, however, is associated with dose-limiting side-effects, particularly with prolonged usage. Thus, a better understanding and new treatment options are urgently warranted for this rare, but excruciating disease.

Background and purpose: Receptor subtypes involved in PGE 2 -induced nociception are still controversial. The present study investigated the prostanoid E receptor (EP) subtypes and the protein kinase (PK) pathways involved in the nociception induced by PGE 2 injection in the mouse paw. Experimental approach: Paw-licking and mechanical allodynia were measured in vivo and protein kinase activation ex vivo by Western blots of extracts of paw skin. Key results: Intraplantar (i.pl.) injection of PGE 2 into the mouse paw caused nociceptive behaviour of short duration with mean ED 50 of 1.43 nmol. PGE 2 produced a longer-lasting mechanical allodynia, with an ED 50 of 0.05 nmol. Intraplantar injection of antagonists at EP 3 or EP 4 , but not at EP 1 or EP 2 receptors inhibited PGE 2 -induced paw-licking. Paw-licking caused by PGE 2 was blocked by an inhibitor of PKA but only partially decreased by inhibition of the extracellular-regulated kinase (ERK). Selective inhibitors of PKC, c-Jun N-terminal kinase (JNK) or p38, all failed to affect PGE 2 -induced paw-licking. An EP 3 antagonist inhibited PGE 2 -induced mechanical allodynia. However, inhibitors of PKA, PKC or ERK, but not p38 or JNK, also partially inhibited PGE 2 -induced mechanical allodynia. Western blot analyses confirmed that i.pl. injection of PGE 2 activated PKA, PKCa, and mitogen activated kinases (MAPKs) in the paw. Co-treatment with EP 3 or EP 4 receptor antagonists reduced PGE 2 -induced PKA and ERK, but not PKCa activation. Conclusions and Implications:The present results indicate that the nociceptive behaviour and mechanical allodynia caused by i.pl. PGE 2 are mediated through activation of distinct EP receptors and PK-dependent mechanisms.