OXACEPROL, AN ATYPICAL INHIBITOR OF INFLAMMATION AND JOINT DAMAGE

Oxaceprol, an established therapeutic agent for osteoarthritis, had no effect on macrophage prostaglandin E₂releasein vitroand inhibited carrageenan paw oedema at high doses (18–150mg/kg p.o.). In the same dose range, oxaceprol was comparable to indomethacin (3mg/kg p.o.) as an inhibitor of yeast hyperalgaesia and at 6–50mg/kg/day p.o. had a mild, variable inhibitory effect on cotton pellet granuloma formation. In adjuvant arthritic rats, oxaceprol (6–54mg/kg/day p.o.) given therapeutically had no effect on the primary paw oedema response, but inhibited secondary lesions in the ears and tail. Histologically, oxaceprol markedly inhibited inflammatory cell infiltration and bone damage in the adjuvant-injected paw. In contrast to indomethacin, oxaceprol was more effective at inhibiting periarticular soft tissue inflammation but did not affect cartilage breakdown in this model. Oxaceprol has a clearly different spectrum of action to NSAIDs such as indomethacin and may act by inhibiting leucocyte infiltration and late connective tissue changes during inflammatory joint disease.     

Reduction by dexamethasone of chemotactic activity in inflammatory exudates

Using an experimental model for allergic inflammation of the air pouch type in rats, the effects of dexamethasone and indomethacin on leukocyte infiltration and level of chemotactic activity in the inflammatory exudate were examined to clarify the mechanisms of anti-inflammatory effects of glucocorticoids. Both dexamethasone and indomethacin when locally administered inhibited leukocyte infiltration, while chemotactic activity of the exudate was reduced by dexamethasone only. Indomethacin failed to reduce the level of chemotactic activity. Suppression by dexamethasone of the level of chemotactic activity became evident prior to the decrease in the number of leukocytes in the inflammatory exudate. These results suggest that the anti-inflammatory steroids manifest their inhibitory effect on leukocyte infiltration by inhibiting the generation of chemotactic factors in the inflammatory site. Besides this, the possible production of some inhibitory factors by the steroids may be considered as an alternative mechanism.     

Inhibition of prostaglandin biosynthesis by etodolac. I. Selective activities in arthritis

Etodolac is the first anti-inflammatory drug belonging to the tetrahydropyranoindole class. In contrast to several other common anti-inflammatory drugs, etodolac exhibited an unusually high potency as an inhibitor of established adjuvant arthritis relative to its activity against carrageenan paw edema in the rat. This phenomenon led us to investigate whether the ability of NSAIDs to inhibit prostaglandin biosynthesis differed between cultures of macrophages, which are present in inflammatory exudates, and cultures of synoviocytes and chondrocytes, which contribute to inflammation of the articulating joint. Although other anti-inflammatory drugs were found to be equally active in all three cell types, etodolac was found to be much more effective on the cells of the joint than on the macrophage. This differential activity may be responsible for the striking efficacy of etodolac as an anti-arthritic drug.     

Dual acting anti-inflammatory drugs

Drugs able to inhibit both cyclooxygenases (COX-1 and COX-2) and 5-lipoxygenase (5-LOX) (dual acting anti-inflammatory drugs) have been designed in order to obtain compounds that retain the activity of classical nonsteroidal anti-inflammatory drugs (NSAIDs) while avoiding their main drawbacks. The classical NSAIDs display their anti-inflammatory action mainly through inhibition of COX and one of their main drawbacks is the curtailed production of gastroprotective prostaglandins (PGs) being associated with the concurrent increased production of the gastro-damaging and bronchoconstrictive leukotrienes (LTs). Leukotrienes and cysteinyl-leukotrienes are moreover pro-inflammatory and increase microvascular permeability. One of the leukotrienes (LTB(4)) is the most potent chemotactic agent and it induces chemotaxis of eosinophils, neutrophils and monocytes in the inflamed tissue, increases superoxide generation and proinflammatory cytokines production. It is further advantageous for a drug to have both COX and 5-LOX inhibiting activities because prostaglandins enhance leukotriene-mediated inflammation. Various structural families of dual inhibitors have been designed and several compounds are currently undergoing clinical development. In the post-COX-2 selective inhibitors era, these dual acting inhibitors may turn out to be promising new drugs to treat inflammatory diseases and possibly other diseases. Indeed, both COX-2 and 5-LOX are also involved in the development and progression of several types of cancer; in these conditions, selective inhibition of COX-2 alone may lead to a shunt of arachidonic acid metabolism towards the leukotriene pathway, and therefore the blockade of both COX-2 and 5-LOX may produce a better anticancer response. In addition, the dual inhibition of both COX and 5-LOX is neuroprotective by suppressing toxic actions of reactive microglia and macrophages, that are increased in aging brain and in age-related degenerative conditions, particularly Alzheimer's and Parkinson's diseases. Finally, the blockade of 5-LOX does not impair the synthesis of lipoxins (LXs), which are mainly produced by further lipoxygenation of 15-HPETE, and which have potent anti-inflammatory properties and can be considered as stop-signal mediators. Leukocyte 15-LOX and platelet 12-LOX by intercellular mechanism via leukocyte/platelet cell-cell interaction convert 15-HPETE into lipoxins.     

Influence of the anti-inflammatory serine esterase inhibitor gabexate mesilate (Foy) on aggregation, locomotion and adhesion of polymorphonuclear leukocytes

The effects of the anti-inflammatory serine esterase inhibitor, gabexate mesilate (Foy) were studied, on locomotion, autoaggregation and adhesion of polymorphonuclear leukocytes stimulated with the complement peptide C5a-desArg. The drug inhibited aggregation as well as spontaneous and directed migration of human leukocytes at concentrations of about 10(-3) M. Adhesion of peritoneal guinea-pig leukocytes to autologous aortic strips was reduced at about 20 times lower drug concentrations. The inhibitory drug effects were highly time- and temperature-dependent. Experiments with the two major drug metabolites, pHB and epsilon GC, indicate that gabexate mesilate is not active by itself but rather by its hydrolytic aromatic metabolite pHB. The results further suggest that the inhibitory effects on leukocyte activities observed are not related to the anti-inflammatory effects of gabexate mesilate.     

Anti-inflammatory effects of nitric oxide-releasing hydrocortisone NCX 1022, in a murine model of contact dermatitis

1 The concept that nitric oxide (NO) release can be beneficial in inflammatory conditions has raised more attention in the recent years, particularly with the development of nitric oxide-releasing anti-inflammatory drugs. There is considerable evidence that NO is capable of enhancing the anti-inflammatory benefits of conventional anti-inflammatory drugs. 2 Since hydrocortisone is the most widely used anti-inflammatory drug for the treatment of skin inflammation, we compared the anti-inflammatory effects of hydrocortisone to an NO-releasing derivative of hydrocortisone, NCX 1022, in a murine model of irritant contact dermatitis, induced by epidermal application of benzalkonium chloride. 3 Topical pre- and post-treatment with NCX 1022 (3 nmol) in C57BL6 mice not only reduced ear oedema formation in a dose-dependent manner, but also was significantly more effective than the parent compound during the initial stages of inflammation (from 1 to 5 h). NCX 1022, but not hydrocortisone, significantly inhibited granulocyte recruitment (tissue myeloperoxidase activity). Histological samples of mouse ears treated with NCX 1022 showed significant reduction in both the number of infiltrated cells and disruption of the tissue architecture compared to hydrocortisone-treated tissues. 4 With intravital microscopy, we observed that both pre- and post-treatments with NCX 1022 were more effective than hydrocortisone in terms of inhibiting benzalkonium chloride-induced leukocyte adhesion to the endothelium, without affecting the flux of rolling leukocytes or venule diameter. 5 These results suggest that by releasing NO, NCX 1022 modulates one of the early events of skin inflammation: the recruitment of leukocytes to the site of inflammation. Overall, we have shown that NO-hydrocortisone provided faster and greater protective effects, reducing major inflammatory parameters (leukocyte adhesion and recruitment, oedema formation, tissue disruption) compared to its parental compound.     

Anomalous effects of anti-inflammatory corticosteroids in endotoxin-induced ocular inflammation

The effect of anti-inflammatory corticosteroids upon leukocyte infiltration was investigated in vivo, using the eye as an experimental model. The inflammatory response was induced by injecting bacterial endotoxin into the vitreous body of the albino rabbit eye. Polymorphonuclear leukocyte (PMN) infiltration into the aqueous humor was quantified by counting cells directly, whereas accumulation of leukocytes in the ocular tissues was determined by measuring myeloperoxidase (MPO) activity. Systemically administered corticosteroids inhibited plasma protein leakage and PMN infiltration into the aqueous humor, but, anomalously, increased MPO activity and hence the number of PMNs in the ciliary body. These findings were confirmed qualitatively by histology. However, the clinical manifestations of the inflammatory responses were almost totally suppressed by the corticosteroids. We suggest that the inhibitory effect of corticosteroids on PMN infiltration into the aqueous humor, and possibly inflammatory exudates in general, represents the suppression of inflammatory cell activity in a manner which is unrelated to a direct effect on leukocyte movement.     

Role of selectins on IgE-mediated skin reaction

Selectins play an important role on leukocytes infiltration into inflammatory tissues. To understand the role of selectins, we investigated the effects of selectin-IgG chimeras and anti selectin antibodies on the murine IgE-mediated skin inflammation model. Biphasic skin reactions were induced by intradermal challenge with ovalbumin (OA) to ears of actively sensitized mice. This reaction was characterized by immediate and late phase responses observed as which were induced via a rapid increase in capillary permeability and leukocyte infiltration, respectively. The expression of E-selectin mRNA was significantly increased to reach its highest level at 2 h after OA challenge. E-, P-, and L-selectin-IgG chimeras inhibited the late phase responses, i.e. ear swelling, neutrophil infiltration and eosinophil infiltration at 24 h after OA challenge in a dose-dependent manner at dose range of 0.1 - 10 mg kg(-1), i.v. Antiselectin antibodies did not inhibit the increase of ear swelling. But anti E- and P-selectin antibodies significantly inhibited neutrophil infiltration and eosinophil infiltration. These results indicate that selectins play an important role on the late phase response of the murine IgE-mediated skin inflammation model by mediating inflammatory cell adhesion to endothelium.     

Comparison of the effects of glucocorticoid and indomethacin treatment on the acute inflammatory reaction in rabbits

We have recently shown that indomethacin and ASA diminish the elevated blood flow, protein exudation, and leukocyte infiltration during acute inflammation induced by killed Escherichia coli, the reversed Arthus reaction, or zymosan-activated plasma (ZAP; C5ades-arg) in rabbit skin. All of these effects were likely due to the inhibition by these drugs of prostaglandin (PG) synthesis in the lesions. Because glucocorticoids are also reported to inhibit PG production and, in large doses, to suppress inflammation accompanying various clinical conditions, we investigated the effects of hydrocortisone (HC), and methylprednisolone (MP), administered in large doses (100 mg/m2/d of MP or 2.5 g/m2/d of HC) on the above three forms of acute inflammation in rabbits. The effect of indomethacin treatment was studied in parallel for comparison. Blood flow, protein exudation, and leukocyte infiltration were quantitated simultaneously with 86Rb Cl, 125I-labelled rabbit albumin and 51Cr labelled blood leukocytes. Systemic indomethacin therapy decreased the blood flow and permeability, while local indomethacin (2.5 micrograms) significantly inhibited leukocyte infiltration into the lesions. In contrast, HC and MP caused only a mild decrease in blood flow, without altering protein exudation or leukocyte influx. However, HC and MP did inhibit protein exudation induced by bradykinin or histamine injection. These results indicate that, at least in rabbits, HC and MP, in contrast to indomethacin, have very weak anti-inflammatory actions on three complement- and neutrophil-mediated inflammatory responses, i.e., E. coli, ZAP (C5ades-arg) and reversed Arthus reactions.     

Dual inhibitors of cyclooxygenase and 5-lipoxygenase. A new avenue in anti-inflammatory therapy?

Nonsteroidal anti-inflammatory drugs (NSAIDs) are a mainstay in the treatment of inflammatory disease and are among the most widely used drugs worldwide. They are anti-inflammatory, antipyretic, and analgesic and are prescribed as first choice for the treatment of rheumatic disorders and, in general, inflammation. The main limitation in using NSAIDs consists in their side-effects, including gastrointestinal ulcerogenic activity and bronchospasm. The mechanism of action of these drugs is attributed to the inhibition of cyclooxygenase (COX), and, consequently, the conversion of arachidonic acid into prostaglandins. It is hypothesized that the undesirable side-effects of NSAIDs are due to the inhibition of COX-1 (constitutive isoform), whereas the beneficial effects are related to the inhibition of COX-2 (inducible isoform). Arachidonic acid can also be converted to leukotrienes (LTs) by the action of 5-lipoxygenase (5-LOX). LTC(4,) LTD(4,) and LTE(4) are potent bronchoconstrictors, whereas LTB(4) is chemotactic for leukocytes and plays an important role in the development of gastrointestinal ulcers by contributing to the inflammatory process. Thus, developing dual inhibitor compounds that will simultaneously inhibit COX and 5-LOX could enhance their individual anti-inflammatory effects and reduce the undesirable side-effects associated with NSAIDs, especially of the gastrointestinal tract. The most promising COX/5-LOX inhibitor is ML3000 ([2,2-dimethyl-6-(4-chlorophenyl)-7-phenyl-2,3-dihydro-1H-pyrrolizine-5-yl]-acetic acid), now in Phase III clinical trials. This new approach will certainly help to unravel the mechanisms at the root of the undesirable effects of NSAIDs and to develop safer NSAIDs.     

Inhibitory effects of Actinidia polygama extract and cyclosporine A on OVA-induced eosinophilia and bronchial hyperresponsiveness in a murine model of asthma

Actinidia polygama is one of the well known herb used in oriental medicine for treatment of anti-inflammatory and many allergic diseases. Anti-asthmatic effects of A. polygama in the development of OVA-induced eosinophilia and hyperresponsiveness in murine model of asthma have not been fully investigated in vivo. Cyclosporine A (CsA) has been shown to inhibit single allergen-induced allergic inflammation such as eosinophilic and lymphocytic infiltration and mRNA expression for interleukin (IL)-4 and IL-5. Asthma is a chronic inflammatory disease of the mucosa and is associated with excess production of Th2 cytokines and eosinophil influx in lung. To clarify the anti-inflammatory and anti-asthmatic effects of A. polygama and CsA, we examined the influence of A. polygama fructus extract (APF) and CsA on the development of pulmonary eosinophilic inflammation in murine model of asthma. Our results have shown that APF and CsA have profound inhibitory effects on the accumulation of eosinophills into airways, with the reduction of eosinophil and total lung leukocyte number by reducing IL-4, IL-5, IL-13 and IgE levels in the BALF. Moreover, APF decreased eosinophil CCR3 expression and CD11b expression in lung cells. These results indicate that APF has a deep inhibitory effect on airway inflammation and hyperresponsiveness in murine model of asthma and play a crucial role as an immunomodulator which possess anti-inflammatory and anti-asthmatic property by modulating the relationship between Th1/Th2 cytokine imbalance.     

Nitric oxide-releasing compounds inhibit neutrophil adhesion to endothelial cells.

In the present work, we demonstrated that chemically different nitric oxide (NO)-releasing compounds inhibit tumor necrosis factor alpha (TNF-alpha)-induced polymorphonuclear leukocyte adhesion to endothelial cells in vitro. Two mesoionic oxatriazole derivatives GEA 3162 (1,2,3,4-oxatriazolium,5-amino-3(3, 4-dichlorophenyl)-chloride) and GEA 3175 (1,2,3,4-oxatriazolium, -3-(3-chloro-2-methylphenyl)-5-[[(4-methylphenyl)sulfonyl]amino]-, hydroxide inner salt) were compared to the earlier-known NO donor SIN-1 (3-morpholino-sydnonimine). GEA 3162 (3-10 microM) and GEA 3175 (10-30 microM) inhibited human polymorphonuclear leukocyte adhesion to B(4) endothelial cells in a dose-dependent manner being more potent than SIN-1. In the present model, leukocytes rather than endothelial cells seemed to be the target of the effect of NO. Flow cytometric analysis showed that NO-releasing compounds did not alter TNF-alpha induced CD11/CD18 surface expression in polymorphonuclear leukocytes. The inhibitory action of NO-releasing compounds on adhesion paralleled with the increased synthesis of cGMP in polymorphonuclear leukocytes. Analogues of cGMP inhibited polymorphonuclear leukocyte adhesion indicating a role for cGMP in the action of NO donors. The results suggest that exogenous NO in the form of NO-releasing compounds inhibits polymorphonuclear leukocyte adhesion to endothelial cells, which may be implicated in the regulation of leukocyte migration and leukocyte-mediated tissue injury.     

NSAIDs: small molecules for prevention of Alzheimer's disease or precursors for future drug development?

Non-steroidal anti-inflammatory drugs (NSAIDs) have been considered for treatment and prevention of Alzheimer's disease (AD) for more than two decades. Biochemical markers in the brains of individuals with AD suggest that inflammation might be a driving cause of the disease that can be suppressed by drug treatment. In addition, a subgroup of widely used NSAIDs inhibits generation of the pathogenic amyloid-beta(1-42) peptide (Abeta42) independently of the inflammatory cyclooxygenase (COX) pathway. Here, we summarize evidence showing that the efficacy of NSAIDs in AD might be attributable to either anti-inflammatory or anti-amyloidogenic activities, and we acknowledge the possibility that current NSAIDs could be neuroprotective through synergistic mechanisms. Ongoing drug development efforts are concentrating on improvement of the COX-independent Abeta42-lowering activity to prevent amyloid pathology and secondary inflammatory reactions and to avoid the clinical side-effects associated with inhibition of COX.     

Mechanism of the inhibitory action of cyclooxygenase inhibitors on leukocyte infiltration: involvement of endogenous histamine

The mechanism of the inhibitory action of cyclooxygenase inhibitors on leukocyte accumulation in the inflammatory locus was investigated in an allergic inflammation of the air pouch types in rats. Three kinds of cyclooxygenase inhibitors, indomethacin, diclofenac and tiaprofenic acid, caused not only inhibition of the vascular permeability response and leukocyte accumulation but also elevation of histamine levels in the exudate. These effects of indomethacin were all reversed by local administration of prostaglandin E2. Pyrilamine, an H1 antagonist, did not affect the anti-inflammatory actions of indomethacin. The H2 antagonists, cimetidine, ranitidine and famotidine, decreased the inhibitory effect of indomethacin on leukocyte accumulation without affecting the inhibitory action on vascular permeability. These results indicate that the inhibitory action of cyclooxygenase inhibitors on leukocyte accumulation is derived from their blocking effect against generation of PGE2 which works as an inhibitory factor on the production of histamine in the inflammatory tissues.     

秋水仙碱在心血管疾病中应用的研究进展

秋水仙碱是一种独特、复杂的抗炎剂,几十年来一直用于预防痛风的急性炎症发作。近年来,临床试验已证明其在一系列心血管疾病中的潜力。冠心病是一种慢性血管炎症性疾病,其主要病理特征是内膜下脂蛋白累积引发异常免疫反应,进而导致富含脂质的炎症斑块形成。炎性反应与冠心病的发生发展密切相关,其中中性粒细胞的浸润及活动被认为是冠心病进展的重要机制。秋水仙碱可通过与微管蛋白二聚体结合而影响细胞的有丝分裂过程,抑制微管蛋白引发的白细胞运动、胞吐和吞噬作用,中断核苷酸结合寡聚化结构域样受体蛋白3炎症小体激活与吞噬,中断白三烯与细胞因子生成,减少微管相关炎症细胞趋化,尤其是中性粒细胞趋化、黏附和募集。秋水仙碱对血小板的作用主要表现在抑制血小板活化及血小板与白细胞相互作用2个方面。抗炎、抗血小板聚集是秋水仙碱治疗心血管疾病的重要机制,其中抗炎可能是秋水仙碱发挥治疗效果的核心机制。低剂量、长疗程的秋水仙碱干预方案可能对心血管疾病患者具有实质性好处。本文主要对秋水仙碱作为附加疗法在心包炎、冠心病、急性冠脉综合征、支架内再狭窄、心房颤动、心力衰竭等心血管疾病中的应用作一综述。     

Enhanced anti-inflammatory potency of a nitric oxide-releasing prednisolone derivative in the rat

1. Derivatization of nonsteroidal anti-inflammatory drugs, such that they release nitric oxide (NO) in small amounts, has been shown to significantly increase their anti-inflammatory activity and analgesic potency. In this study, we compared the anti-inflammatory potency of prednisolone to a nitric oxide-releasing derivative of prednisolone (NCX-1015). 2. Carrageenan-induced inflammation of an airpouch in the rat was used. The rats were pretreated with equimolar doses of prednisolone or NCX-1015 and the effects on leukocyte infiltration into the airpouch and exudates levels of prostaglandin E(2) (PGE(2)), leukotriene B(4) (LTB(4)) and nitrite (as an index of NO production) were measured 6 h later. 3. Injection of carrageenan into the airpouch resulted in a progressive increase in leukocyte infiltration, and accumulation of PGE(2), LTB(4) and nitrite. Carrageenan also induced elevated expression of cyclooxygenase-1 and -2, inducible nitric oxide synthase and 5-lipoxygenase in the inflammatory exudate. 4. Prednisolone dose dependently reduced the numbers of leukocytes within the airpouch exudates, as well as reducing PGE(2), LTB(4) and nitrite levels. NCX-1015 also reduced leukocyte numbers and inflammatory mediator levels. However, the doses of NCX-1015 required to produce a maximal reduction of each of these parameters was one-third to one-tenth the dose of prednisolone that produced a comparable effect. 5. The reduction of PGE(2) and NO production was likely to be at least in part due to reduced expression of the key enzymes responsible for their synthesis (cyclooxygenase-2, inducible NO synthase), with NCX-1015 producing greater suppression than prednisolone at an equimolar dose. 6. Coadministration of prednisolone with a nitric oxide donor (DETA-NONOate) resulted in a greater reduction of leukocyte infiltration and inflammatory mediator production than was observed with either drug alone. 7. These results support the notion that delivery of NO to a site of inflammation can markedly enhance the anti-inflammatory activity of a glucocorticoid.