Biosynthesis of H2S is impaired in non-obese diabetic (NOD) mice

Hydrogen sulphide (H2S) has been involved in cardiovascular homoeostasis but data about its role in animal models of diabetic pathology are still lacking. Here, we have analysed H2S signalling in a genetic model of diabetes, the non-obese diabetic (NOD) mice. NOD mice exhibit a progressive endothelial dysfunction characterized by a reduced reactivity of blood vessels as diabetes develops. NOD mice were divided into three groups according to different glycosuria values: NOD I, NOD II and NOD III. Age-matched non-obese resistant (NOR) mice were used as controls. H(2)S levels in plasma and aortic tissue were measured. Functional studies in aorta were carried out in isolated organ baths using both an exogenous source of H2S (NaHS) and the metabolic precursor (L-cysteine). Real time PCR and western blot analysis were also carried out on aortic tissues. NOD mice exhibited a progressive reduction of H2S plasma levels, which paralleled disease severity. L-cysteine-induced H2S production by aortic tissues was also progressively reduced. L-cysteine-induced vasorelaxation was significantly reduced in NOD mice while NaHS-induced relaxation was unaffected. ODQ (guanylate cyclase inhibitor), L-NAME (NO synthase inhibitor) or PAG, an inhibitor of cystathionine-gamma-lyase (CSE) inhibited H2S production induced by L-cysteine. In NOD mice, endogenous H2S production is significantly impaired. Also, the ability of isolated aorta to respond to exogenous H2S is enhanced and endothelium-derived NO appears to be involved in the enzymatic conversion of L-cysteine into H2S

Synthesis of 2-Methyl-3-indolylacetic Derivatives as Anti-Inflammatory Agents That Inhibit Preferentially Cyclooxygenase 1 without Gastric Damage

Novel substituted 2-methyl-3-indolylacetic derivatives were synthesized and evaluated for their activity in vitro and in vivo on COX-1 and COX-2. Active compounds were screened to determine their gastrointestinal tolerability in vivo in the rat. Results showed that 3 and 4 preferentially inhibited COX-1 in vitro and in vivo. MD simulations indicated an induced fit for COX-1 but not for COX-2, probably because of a lower plasticity of the latter

Protective role of PI3-kinase-Akt-eNOS signalling pathway in intestinal injury associated with splanchnic artery occlusion shock.

Background and purpose: Endothelial NO synthase (eNOS) is a dynamic enzyme tightly controlled by co- and post-translational lipid modifications, phosphorylation and regulated by protein-protein interactions. Here we have pharmacologically modulated the activation of eNOS, at different post-translational levels, to assess the role of eNOS-derived NO and of these regulatory mechanisms in intestinal injury associated with splanchnic artery occlusion (SAO) shock. Experimental approach: SAO shock was induced by clamping both the superior mesenteric artery and the celiac trunk for 45 min followed by 30 min of reperfusion. During ischemia, 15 min prior to reperfusion, mice were given geldanamycin, an inhibitor of hsp90 recruitment to eNOS, or LY-294002 an inhibitor of phosphatidylinositol 3-kinase (PI3K), an enzyme that initiates Akt-catalysed phosphorylation of eNOS on Ser 1179. After 30 min of reperfusion, samples of ileum were taken for histological examination or for biochemical studies. Key results: Either LY-294002 or geldanamycin reversed the increased activation of eNOS and Akt observed following SAO shock. These molecular effects were mirrored in vivo by an exacerbation of the intestinal damage. Histological damage also correlated with neutrophil infiltration, assessed as myeloperoxidase activity, and with an increased expression of the adhesion proteins: ICAM-I, VCAM, P-selectin and E-selectin. Conclusions and implications: Overall these results suggest that activation of the Akt pathway in ischemic regions of reperfused ileum is a protective event, triggered in order to protect the intestinal tissue from damage induced by ischaemia/reperfusion through a fine tuning of the endothelial NO pathway. © 2007 Nature Publishing Group All rights reserved

Lack of Ecto-5'-Nucleotidase Protects Sensitized Mice against Allergen Challenge

Ecto-5'-nucleotidase (CD73), the ectoenzyme that together with CD39 is responsible for extracellular ATP hydrolysis and adenosine accumulation, regulates immune/inflammatory processes by controlling innate and acquired immunity cell functions. We previously demonstrated that CD73 is required for the assessment of a controlled allergic sensitization, in mice. Here, we evaluated the response to aerosolized allergen of female-sensitized mice lacking CD73 in comparison with their wild type counterpart. Results obtained show, in mice lacking CD73, the absence of airway hyperreactivity in response to an allergen challenge, paralleled by reduced airway CD23+B cells and IL4+T cells pulmonary accumulation together with reduced mast cells accumulation and degranulation. Our findings indicate CD73 as a potential therapeutic target for allergic asthma

Sphingosine-1-phosphate modulates vascular permeability and cell recruitment inacute inflammation in vivo.

The sphingosine kinase (SPK)/sphingosine-1-phosphate (S1P) pathway recently has been associated with a variety of inflammatory-based diseases. The majority of these studies have been performed in vitro. Here, we have addressed the relevance of the SPK/S1P pathway in the acute inflammatory response in vivo by using different well known preclinical animal models. The study has been performed by operating a pharmacological modulation using 1) L-cycloserine and DL-threo-dihydrosphingosine (DTD), S1P synthesis inhibitors or 2) 2-undecyl-thiazolidine-4-carboxylic acid (BML-241) and N-(2,6-dichloro-4-pyridinyl)-2-[1,3-dimethyl-4-(1-methylethyl)-1H-pyrazolo[3,4-b]pyridin-6-yl]-hydrazinecarboxamide (JTE-013), specific S1P(2) and S1P(3) receptor antagonists. After local injection of carrageenan in mouse paw S1P release significantly increases locally and decreases during the resolution phase. Expression of SPKs and S1P(2) and S1P(3) receptors is increased in inflamed tissues. Administration of L-cycloserine or DTD caused a significant anti-inflammatory effect. By using different animal models we have also demonstrated that the SPK/S1P pathway contributes to changes in vascular permeability and promotes cell recruitment. The S1P effect on cell recruitment results is receptor-mediated because both JTE-013 and BML-241 inhibited zymosan-induced cell chemotaxis without effect on vascular leakage. Conversely, changes in vascular permeability involve mainly SPK activity, because compound 48/80-induced vascular leakage was significantly inhibited by DTD. In conclusion, the SPK/S1P pathway is involved in acute inflammation and could represent a valuable therapeutic target for developing a new class of anti-inflammatory drugs

Antagonizing S1P3 receptor with Cell-Penetrating Pepducins in Skeletal Muscle Fibrosis

Bioactive lipids, derived from the metabolism of plasma membrane, are important mediators of cellular signaling in vertebrates. In recent years there has been a growing interest on sphingosine-1-phosphate (S1P) which is the final metabolite produced during the sequential degradation of plasma membrane glycosphingolipids and sphingomyelin. The S1P acts through five known subtypes of heptameric G-protein coupled receptors (GPCR), namely S1P1-S1P5 (S1PR). Recent evidence indicates that S1P signaling axis contributes to the development and maintenance of the fibrotic process [1]. Fibrosis is a pathological condition that can affect every organ, consequence of a persisting inflammatory and tissue remodeling condition. In different fibrotic models an extensive crosstalk between TGFβ and S1P signaling axis has been demonstrated. S1P3 plays a pivotal role in fibrosis development in different tissues such as skeletal muscle, liver, and kidney [2]. Thus, selective antagonists of the S1P3 receptor could be useful to deeply study its role in fibrosis as well as to develop new therapeutic entities to treat fibrotic diseases. Pepducins specifically target the intracellular loops, acting as allosteric modulators of GPCR activity. Using this approach, we have synthesized a pepducin based S1P3 antagonist namely KRX-725-II (Myristoyl-GRPYDAN-NH2) [3]. Here to improve the S1P1 vs S1P3 selectivity, we have synthesized several derivatives of KRX-725-II pointing our attention on the aromatic residue of the sequence, Tyr4, and with the aim to introduce molecular constraints. The new molecular entities have been evaluated for their selectivity profile by using mouse aortas. This screening allowed us to identify compounds V and VII (embodying respectively L- and D-Tic) as the most selective S1P3 antagonists. The selected compounds also displayed the ability to significantly reduce the profibrotic action of TGFβ1 in C2C12 myoblasts. To explain the higher selectivity observed for compounds V and VII, they were analyzed by Molecular Dynamics (MD) Simulations. The middle conformations of V and VII were compared by superimposing their GRP residues, which adopt a similar backbone orientation (see Figure). This revealed that the DAN residues with β-turn-like motif are located on opposite sides of the plane defined by the L- or D-Tic residue. This difference may explain, in structural terms, the selective S1P3 antagonism of V and VII in comparison to the unselective antagonist KRX-725-II, whose flexibility seems to be high enough for the adaptation to the binding regions of the individual receptor subtypes S1P1 and S1P3. Peptides V and VII possess, indeed, a highly constrained D- or L-Tic residue that hinder the pharmacophore from interacting properly with the binding pocket of the S1P1 receptor, therefore leading to S1P3 selectivity

Effects of sex hormones on bronchial reactivity during the menstrual cycle

Background: Many asthmatic women complain of symptom exacerbations in particular periods, i.e. during pregnancy and menstrual cycles (perimenstrual asthma: PMA)". The goal of this study was to study the effect of the luteal and follicular phases of the menstrual cycle on bronchial reactivity (BR) in a group of asthmatic women. Methods: For this purpose, 36 pre-menopausal women were enrolled and underwent testing for resting pulmonary function, measurement of the diffusing capacity of the lung for carbon monoxide (DLCO), and airway responsiveness to methacholine in the follicular and luteal phases of their menstrual cycles. We also measured plasma hormone levels and levels of cyclic adenosine monophosphate (cAMP; a mediator of bronchial smooth muscle contraction) and testosterone in induced sputum samples. Results: Our study showed that about 30% of the asthmatic women had decreased PC20FEV1.0 in the follicular phase of menstrual cycle with a significant correlation between PC20FEV1.0 and serum testosterone levels. Moreover, marked increases in sputum testosterone levels (mean = 2.6-fold increase) together with significant increases in sputum cAMP concentrations (mean = 3.6-fold increases) were observed during the luteal phase of asthmatic patients, suggesting that testosterone contributes to the pathophysiology of PMA. We excluded the possibility that testosterone directly inhibits phosphodiesterase (PDE) activity as incubating PDE with testosterone in vitro did not reduce PDE catalytic activity. Conclusions: In conclusion, our data show that PC20FEV1.0 was decreased in the follicular phase of the menstrual cycle in about 30% of women and was associated with lower cAMP levels in sputum samples, which may contribute to bronchoconstriction. Our results also suggest a link between PMA and testosterone levels. However, whether these findings are of clinical significance in terms of the management of asthma or asthma worsening during the menstrual cycle needs further investigation

Salvinorin A Inhibits Airway Hyperreactivity Induced by Ovalbumin Sensitization

Salvinorin A, a neoclerodane diterpene isolated from Salvia divinorum, exerts a number of pharmacological actions which are not solely limited to the central nervous system. Recently it has been demonstrated that Salvinorin A inhibits acute inflammatory response affecting leukotriene (LT) production. Since LTs are potent lipid mediators implicated in allergic diseases, we evaluated the effect of Salvinorin A on allergic inflammation and on airways following sensitization in the mouse. Mice were sensitized with s.c. injection of ovalbumin (OVA) on days 1 and 8. Sensitized mice received on days 9 and 12 on the shaved dorsal surface air administration to induce the development of the air-pouches. On day 15 animals were challenged by injection of OVA into the air-pouch. Salvinorin A, administered (10 mg/kg) before each allergen exposure, significantly reduced OVA-induced LT increase in the air pouch. This effect was coupled to a reduction in cell recruitment and Th2 cytokine production. In another set of experiments, mice were sensitized with OVA and both bronchial reactivity and pulmonary inflammation were assessed. Salvinorin A abrogated bronchial hyperreactivity and interleukin (IL)-13 production, without effect on pulmonary inflammation. Indeed cell infiltration and peribronchial edema were still present following diterpenoid treatment. Similarly, pulmonary IL-4 and plasmatic IgE levels were not modulated. Conversely, Salvinorin A significantly reduced LTC4 production in the lung of sensitized mice. Finally mast cell activity was evaluated by means of toluidine blue staining. Data obtained evidenced that Salvinorin A significantly inhibited mast cell degranulation in the lung. Our study demonstrates that Salvinorin A inhibits airway hyperreactivity induced by sensitization by inhibition of LT production and mast cell degranulation. In conclusion Salvinorin A could represent a promising candidate for drug development in allergic diseases such as asthma

Diabetic mouse angiopathy is linked to progressive sympathetic receptor deletion coupled to an enhanced caveolin-1 expression.

OBJECTIVE: Clinical studies have demonstrated that hyperglycaemia represents a major risk factor in the development of the endothelial impairment in diabetes, which is the first step in vascular dysfunction. Using non-obese diabetic mice, we have evaluated the role of the adrenergic system and eNOS on progression of the disease METHODS AND RESULTS: When glycosuria is high (20 to 500 mg/dL), there is a selective reduction in the response to alpha1 and beta2 agonists but not to dopamine or serotonin. When glycosuria is severe (500 to 1000 mg/dL), there is a complete ablation of the contracture response to the alpha1 receptor agonist stimulation and a marked reduced response to beta2 agonist stimulation. This effect is coupled with a reduced expression of alpha1 and beta2 receptors, which is caused by an inhibition at transcriptional level as demonstrated by RT-PCR. In the severe glycosuria (500 to 1000 mg/dL), although eNOS expression is unchanged, caveolin-1 expression is significantly enhanced, indicating that high glucose plasma levels cause an upregulation of the eNOS endogenous inhibitory tone. These latter results correlate with functional data showing that in severe glycosuria, there is a significant reduction in acetylcholine-induced vasodilatation. CONCLUSIONS: Our results show that in diabetes development, there is a progressive selective downregulation of the alpha1 and beta2 receptors. At the same time, there is an increased expression of caveolin-1, the endogenous eNOS inhibitory protein. Thus, caveolin-1 could represent a new possible therapeutic target in vascular impairment associated with diabetes