Antonietta Rossi

Protective Effects of Anthocyanins from Blackberry in a Rat Model of Acute Lung Inflammation

Anthocyanins are a group of naturally occuring phenolic compounds related to the coloring of plants, flowers and fruits. These pigments are important as quality indicators, as chemotaxonomic markers and for their antioxidant activities. Here, we have investigated the therapeutic efficacy of anthocyanins contained in blackberry extract (cyanidin-3-O-glucoside represents about 80% of the total anthocyanin contents) in an experimental model of lung inflammation induced by carrageenan in rats. Injection of carrageenan into the pleural cavity elicited an acute inflammatory response characterized by fluid accumulation which contained a large number of neutrophils as well as an infiltration of polymorphonuclear leukocytes in lung tissues and subsequent lipid peroxidation, and increased production of nitrite/nitrate (NOx) and prostaglandin E2 (PGE2). All parameters of inflammation were attenuated in a dose-dependent manner by anthocyanins (10, 30 mg kg-1 30 min before carrageenan). Furthermore, carrageenan induced an upregulation of the adhesion molecule ICAM-1, nitrotyrosine and poly (ADP-ribose) synthetase (PARS) as determined by immunohistochemical analysis of lung tissues. The degree of staining was lowered by anthocyanins treatment. Thus, the anthocyanins contained in the blackberry extract exert multiple protective effects in carrageenan-induced pleurisy.

ERK-mediated regulation of leukotriene biosynthesis by androgens: A molecular basis for gender differences in inflammation and asthma

5-Lipoxygenase initiates the biosynthesis of leukotrienes, lipid mediators involved in normal host defense and in inflammatory and allergic disorders. Despite an obvious gender bias in leukotriene-related diseases (e.g., asthma), gender aspects have been neglected in studies on leukotrienes and 5-lipoxygenase. Here, we show that leukotriene formation in stimulated whole blood or neutrophils from males is substantially lower compared with females, accompanied by changed 5-lipoxygenase trafficking. This is due to gender-specific differential activation of extracellular signal-regulated kinases (ERKs). The differences are directly related to variant male/female testosterone plus 5α-dihydrotestosterone levels, and addition of 5α-dihydrotestosterone to female blood or neutrophils reduced the high (female) LT biosynthesis capacity to low (male) levels. In conclusion, regulation of ERKs and leukotriene formation by androgens constitutes a molecular basis for gender differences in the inflammatory response, and in inflammatory diseases such as asthma.

The 5-lipoxygenase inhibitor, zileuton, suppresses prostaglandin biosynthesis by inhibition of arachidonic acid release in macrophages

BACKGROUND AND PURPOSE Zileuton is the only 5‐lipoxygenase (5‐LOX) inhibitor marketed as a treatment for asthma, and is often utilized as a selective tool to evaluate the role of 5‐LOX and leukotrienes. The aim of this study was to investigate the effect of zileuton on prostaglandin (PG) production in vitro and in vivo.

Inhibition of microsomal prostaglandin E2 synthase-1 as a molecular basis for the anti-inflammatory actions of boswellic acids from frankincense

BACKGROUND AND PURPOSE Frankincense, the gum resin derived from Boswellia species, showed anti‐inflammatory efficacy in animal models and in pilot clinical studies. Boswellic acids (BAs) are assumed to be responsible for these effects but their anti‐inflammatory efficacy in vivo and their molecular modes of action are incompletely understood.

Arzanol, a prenylated heterodimeric phloroglucinyl pyrone, inhibits eicosanoid biosynthesis and exhibits anti-inflammatory efficacy in vivo.

Based on its capacity to inhibit in vitro HIV-1 replication in T cells and the release of pro-inflammatory cytokines in monocytes, the prenylated heterodimeric phloroglucinyl α-pyrone arzanol was identified as the major anti-inflammatory and anti-viral constituent from Helichrysum italicum. We have now investigated the activity of arzanol on the biosynthesis of pro-inflammatory eicosanoids, evaluating its anti-inflammatory efficacy in vitro and in vivo. Arzanol inhibited 5-lipoxygenase (EC 7.13.11.34) activity and related leukotriene formation in neutrophils, as well as the activity of cyclooxygenase (COX)-1 (EC 1.14.99.1) and the formation of COX-2-derived prostaglandin (PG)E(2)in vitro (IC(50)=2.3-9μM). Detailed studies revealed that arzanol primarily inhibits microsomal PGE(2) synthase (mPGES)-1 (EC 5.3.99.3, IC(50)=0.4μM) rather than COX-2. In fact, arzanol could block COX-2/mPGES-1-mediated PGE(2) biosynthesis in lipopolysaccharide-stimulated human monocytes and human whole blood, but not the concomitant COX-2-derived biosynthesis of thromboxane B(2) or of 6-keto PGF(1α), and the expression of COX-2 or mPGES-1 protein was not affected. Arzanol potently suppressed the inflammatory response of the carrageenan-induced pleurisy in rats (3.6mg/kg, i.p.), with significantly reduced levels of PGE(2) in the pleural exudates. Taken together, our data show that arzanol potently inhibits the biosynthesis of pro-inflammatory lipid mediators like PGE(2)in vitro and in vivo, providing a mechanistic rationale for the anti-inflammatory activity of H. italicum, and a rationale for further pre-clinical evaluation of this novel anti-inflammatory lead.

Myrtucommulone from Myrtus communis exhibits potent anti-inflammatory effectiveness in vivo.

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-α and interleukin-1β) in the pleural exudate and their immunohistochemical localization in the lung; 5) the leukotriene B4, but not prostaglandin E2, 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.

Structural Optimization and Biological Evaluation of 2-Substituted 5-Hydroxyindole-3-carboxylates as Potent Inhibitors of Human 5-Lipoxygenase

Pharmacological suppression of leukotriene biosynthesis by inhibitors of 5-lipoxygenase (5-LO) is a strategy to intervene with inflammatory and allergic disorders. We recently presented 2-amino-5-hydroxy-1H-indoles as efficient 5-LO inhibitors in cell-based and cell-free assays. Structural optimization led to novel benzo[g]indole-3-carboxylates exemplified by ethyl 2-(3-chlorobenzyl)-5-hydroxy-1H-benzo[g]indole-3-carboxylate (compound 11a), which inhibits 5-LO activity in human neutrophils and recombinant human 5-LO with IC(50) values of 0.23 and 0.086 microM, respectively. Notably, 11a efficiently blocks 5-LO product formation in human whole blood assays (IC(50) = 0.83-1.6 microM) and significantly prevented leukotriene B(4) production in pleural exudates of carrageenan-treated rats, associated with reduced severity of pleurisy. Together, on the basis of their high potency against 5-LO and the marked efficacy in biological systems, these novel and straightforward benzo[g]indole-3-carboxylates may have potential as anti-inflammatory therapeutics.

The inhibitory effect of propolis and caffeic acid phenethyl ester on cyclooxygenase activity in J774 macrophages

The effect of an ethanolic extract of propolis, with and without CAPE, and some of its components on cyclooxygenase (COX-1 and COX-2) activity in J774 macrophages has been investigated. COX-1 and COX-2 activity, measaured as prostaglandin E2 (PGE2) production, were concentration-dependently inhibited by propolis (3 x 10(-3) - 3 x 10(2) microgml(-1)) with an IC50 of 2.7 microgml(-1) and 4.8 x 10(-2) microgml(-1), respectively. Among the compounds tested pinocembrin and caffeic, ferulic, cinnamic and chlorogenic acids did not affect the activity of COX isoforms. Conversely, CAPE (2.8 x 10(-4) - 28 microgml(-1); 10(-9) - 10(-4) M) and galangin (2.7 x 10(-4) - 27 microgml(-1); 10(-9) - 10(-4) M) were effective, the last being about ten-twenty times less potent. In fact the IC50 of CAPE for COX-1 and COX-2 were 4.4 x 10(-1) microgml(-1) (1.5 x 10(-6) M) and 2 x 10(-3) microgml(-1) (6.3 x 10(-9) M), respectively. The IC50 of galangin were 3.7 microgml(-1) (15 x 10(-6) M) and 3 x 10(-2) microgml(-1) (120 x 10(-9) M), for COX-1 and COX-2 respectively. To better investigate the role of CAPE, we tested the action of the ethanolic extract of propolis deprived of CAPE, which resulted about ten times less potent than the extract with CAPE in the inhibition of both COX-1 and COX-2, with an IC50 of 30 microgml(-1) and 5.3 x 10(-1) microgml(-1), respectively. Moreover the comparison of the inhibition curves showed a significant difference (p < 0.001). These results suggest that both CAPE and galangin contribute to the overall activity of propolis, CAPE being more effective.

5-Lipoxygenase modulates colitis through the regulation of adhesion molecule expression and neutrophil migration

Leukotrienes play a part in inflammatory response. The unique role of the enzyme 5-lipoxygenase (5-LO) in the production of leukotrienes makes it as therapeutic target for inflammatory conditions like inflammatory bowel disease (IBD). In the present study, by comparing the responses in wild-type mice (5-LOWT) and mice lacking the 5-lipoxygenase (5-LOKO), we investigated the role played by this enzyme in the development of experimental colitis. To address this question, we used an experimental model of colitis, induced by dinitrobenzene sulfonic acid (DNBS). When compared to DNBS-treated 5-LOWT mice, DNBS-treated 5-LOKO mice experienced a reduced rate of the extent and severity of the histological signs of colon injury. After administration of DNBS 5-LOWT mice showed hemorrhagic diarrhea, weight loss and large areas of necrosis in the mucosa of the colon. Neutrophil infiltration was associated with the expression of ICAM-1, VCAM-1, P-selectin, E-selectin that were mainly localized around vessels. Absence of a functional 5-LO resulted in a significant reduction of all the above-described parameters. In particular, we have observed a significant reduction of: (i) the degree of colon injury, (ii) the rise in myeloperoxidase (MPO) activity (mucosa), (iii) the increase in staining (immunohistochemistry) for ICAM-1, VCAM-1, P-selectin, E-selectin caused by DNBS in the colon. Similarly, the treatment of 5-LOWT with zileuton (50 mg/kg per os twice a day) resulted in a significant reduction of all the above-described parameters. In addition, in in vitro study a significantly reduced chemotactic response to IL-8 was observed in peripheral blood leukocytes from 5-LOKO in comparison to 5-LOWT polymorphonuclear leukocyte. Similar results were obtained when we analyzed the chemotactic response of 5-LOWT cell incubated for 15 min with zileuton (50 μg/ml). Taken together, our results clearly demonstrate that 5-LO modulates neutrophil infiltration in experimental colitis through the expression of adhesion molecules.

Effects of zileuton and montelukast in mouse experimental spinal cord injury

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).