Adenosine A2B receptor agonist improves epidermal barrier integrity in a murine model of epidermal hyperplasia.

Adenosine regulates multiple physiological processes through the activation of four receptor subtypes, of which the A2B adenosine receptor (A2BAR) has the lowest affinity for adenosine. Being the adenosine receptor subtype most prominently expressed in epidermis, we recently described the antiproliferative and anti-inflammatory effect of the selective A2BAR agonist BAY60-6583 (BAY) in human keratinocytes stimulated with 12-O-tetradecanoylphorbol-13-acetate (TPA), so we sought to establish the effect of topical application of BAY in a model of murine epidermal hyperplasia. Topical application of BAY (1 or 10 µg/site) prevented the inflammatory reaction and skin lesions induced by TPA, minimizing hyperproliferation and acanthosis, as well as the expression of specific markers of proliferative keratinocytes. On the other hand, pre-treatment with the selective A2BAR antagonist, PSB-1115 (PSB, 5 or 50 µg/site) reversed these beneficial effects. Additionally, BAY application normalized the expression of epidermal barrier proteins, whose integrity is altered in inflammatory skin diseases, while treatment with the antagonist alone worsened it. Our results, besides confirming the anti-inflammatory and antiproliferative effects of the A2BAR agonist, further demonstrate a role of A2BAR activation to preserve the epidermal barrier. Therefore, the activation of A2BAR may constitute a possible new pharmacological target for the treatment of skin inflammatory diseases such as psoriasis.

Annexin A2-Mediated Plasminogen Activation in Endothelial Cells Contributes to the Proangiogenic Effect of Adenosine A2A Receptors.

Adenosine A2A receptor mediates the promotion of wound healing and revascularization of injured tissue, in healthy and animals with impaired wound healing, through a mechanism depending upon tissue plasminogen activator (tPA), a component of the fibrinolytic system. In order to evaluate the contribution of plasmin generation in the proangiogenic effect of adenosine A2A receptor activation, we determined the expression and secretion of t-PA, urokinase plasminogen activator (uPA), plasminogen activator inhibitor-1 (PAI-1) and annexin A2 by human dermal microvascular endothelial cells stimulated by the selective agonist CGS-21680. The plasmin generation was assayed through an enzymatic assay and the proangiogenic effect was studied using an endothelial tube formation assay in Matrigel. Adenosine A2A receptor activation in endothelial cells diminished the release of PAI-1 and promoted the production of annexin A2, which acts as a cell membrane co-receptor for plasminogen and its activator tPA. Annexin A2 mediated the increased cell membrane-associated plasmin generation in adenosine A2A receptor agonist treated human dermal microvascular endothelial cells and is required for tube formation in an in vitro model of angiogenesis. These results suggest a novel mechanism by which adenosine A2A receptor activation promotes angiogenesis: increased endothelial expression of annexin A2, which, in turn, promotes fibrinolysis by binding tPA and plasminogen to the cell surface.

NF-κB and STAT3 inhibition as a therapeutic strategy in psoriasis: in vitro and in vivo effects of BTH.

Benzo[b]thiophen-2-yl-3-bromo-5-hydroxy-5H-furan-2-one (BTH) is a simple and interesting synthetic derivative of petrosaspongiolide M, a natural compound isolated from a sea sponge with demonstrated potent anti-inflammatory activity through inhibition of the NF-κB signaling pathway. In the present study, we report the in vitro and in vivo pharmacological effect of BTH on some parameters related to the innate and adaptive response in the pathogenesis of psoriasis. BTH inhibited the release of some of the key psoriatic cytokines such as tumor necrosis factor α, IL-8, IL-6, and CCL27 through the downregulation of NF-κB in normal human keratinocytes. Moreover, it impaired signal transducers and activators of transcription 3 (STAT3) phosphorylation and translocation to the nucleus, which resulted in decreased keratinocyte proliferation. These results were confirmed in vivo in two murine models of psoriasis: the epidermal hyperplasia induced by 12-O-tetradecanoylphorbol-13-acetate and the imiquimod-induced skin inflammation model. In both cases, topical administration of BTH prevented skin infiltration and hyperplasia through suppression of NF-κB and STAT3 phosphorylation. Our results confirm the pivotal role of both transcriptional factors in skin inflammation, as occurs in psoriasis, and highlight the potential of small molecules as therapeutic agents for the treatment of this skin disease, with BTH being a potential candidate for future drug research.

Cacospongionolide B suppresses the expression of inflammatory enzymes and tumour necrosis factor-alpha by inhibiting nuclear factor-kappa B activation.

1. The marine product cacospongionolide B, a sesterterpene isolated from the Mediterranean sponge Fasciospongia cavernosa, is an inhibitor of secretory phospholipase A(2) with anti-inflammatory properties. In this work, we have studied the mechanism of action of this compound in the inflammatory response induced by zymosan in primary cells and in the mouse air pouch. 2. In mouse peritoneal macrophages, cacospongionolide B was able to downregulate the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), resulting in decreased production of NO and prostaglandin E(2) (PGE(2)). This compound also reduced tumour necrosis factor-alpha (TNF-alpha) mRNA expression and TNF-alpha levels. 3. Cacospongionolide B inhibited nuclear factor-kappaB (NF-kappaB)-DNA binding activity and the nuclear translocation of this transcription factor. 4. Treatment of cells with cacospongionolide B impaired NF-kappaB inhibitory protein (IkappaB-alpha) phosphorylation and enhanced IkappaB-alpha expression. 5. Inhibition of iNOS, COX-2 and inflammatory mediators was confirmed in the mouse air pouch. 6. These results show that cacospongionolide B is able to control NO, PGE(2) and TNF-alpha production in vitro and in vivo, effects likely dependent on NF-kappaB inhibition.

Diayangambin exerts immunosuppressive and anti-inflammatory effects in vitro and in vivo.

In this study, the furofuran lignan (+)-diayangambin [tetrahydro-1,4-bis(3,4,5-trimethoxyphenyl)-(1 R)-1alpha,3abeta,4alpha,6abeta-1 H,3 H-furo [3,4- c]furan] was evaluated in vitro and in vivo for its immunomodulatory and anti-inflammatory efficacy. Human mononuclear cell proliferation was inhibited by diayangambin with an IC 50 value of 1.5 (0.5 - 2.8) microM. In addition, the compound reduced for 40.8 % prostaglandin E 2 generation in stimulated RAW 264.7 macrophage cell line at 10 microM. In vivo, a clear reduction of ear swelling was observed when diayangambin (40 mg/kg) was administered orally to 2,4-dinitrofluorobenzene-treated mice. The inhibition of swelling was associated with a reduction of leukocyte infiltration determined as myeloperoxidase activity. In the carrageenan mouse paw edema model, diayangambin significantly suppressed inflamed paw volume and prostaglandin E 2 levels. Our findings indicate the potential interest of diayangambin in the treatment of immune and inflammatory responses.

A new ditriazine inhibitor of NF-kappaB modulates chronic inflammation and angiogenesis.

We have previously shown that a ditriazine derivative 4,10-dichloropyrido[5,6:4,5]thieno[3,2- d':3,2- d]-1, 2, 3-ditriazine (DTD) modulates acute inflammation in murine models by inhibition of leukocyte functions and expression of inducible enzymes including nitric oxide synthase and cyclooxygenase-2 (COX-2). In the present work, we have demonstrated the anti-inflammatory effect of DTD after oral administration in the rat adjuvant-induced arthritis, by reduction of interleukin-1beta and tumour necrosis factor-alpha levels and COX-2 expression in the inflamed tissues. These mediators were also significantly decreased by DTD treatment in the angiogenesis-dependent murine air pouch granuloma model, where this agent exerted anti-inflammatory and antiangiogenic effects. In vitro experiments indicated that DTD is an inhibitor of the nuclear factor-kappaB (NF-kappaB) pathway of cellular activation in macrophages, in parallel with the regulation of cytokine release. Our results suggest that the anti-inflammatory and antiangiogenic properties of DTD can be related to the inhibition of cytokine and PGE(2) production by interfering with NF-kappaB activation. This compound thus offers a therapeutic potential for the treatment of chronic inflammatory diseases with an angiogenic component, such as rheumatoid arthritis.