Pharmacological activity of the second generation leukotriene B4 receptor antagonist,SC-53228:

Inflammatory bowel disease is a chronic inflammatory disorder of the gastrointestinal tract that includes ulcerative colitis and Crohn's disease. Leukotriene B₄ is thought to be a prominent proinflammatory mediator in these diseases, in that leukotriene B₄ levels are increased in the colonic mucosa of inflammatory bowel disease patients and there is increased polymorphonuclear leukocyte infiltration of these tissues. SC-53228(+)-(S)-7-[3-[2(-cyclopropylmethyl)-3-methoxy-4-[(methylamino)carbonyl]phenoxy]propoxy]-3,4-dihydro-8-propyl-2H-1-benzopyran-2-propanoic acid, a second generation LTB₄ receptor antagonist, was evaluated for therapeutic efficacy in a rodent model of acute colonic inflammation induced by short chain organic acids, as well as for effects on rodent liver. When given intracolonically to mice, SC-53228 inhibited neutrophil infiltration, assessed by myeloperoxidase (MPO) levels, with an ED₅₀ value of 9±1.2 mg/kg. When given by gavage, SC-53228 inhibited neutrophil influx in colitic mice with an ED₅₀ value of 30 mg/kg. These results were also confirmed histologically. Furthermore, high dose oral SC-53228 treatment had no effect on liver cytochrome P-450 content, fatty acyl CoA oxidase or liver weight in rats and mice. Together, these data suggest that SC-53228 may be efficacious orally and locally, as well as safe for use in trials for the medical management of IBD.     

The pharmacokinetics and metabolism of SC-53228, a specific leukotriene B4 receptor antagonist

Inflammation Research -     

Antiinflammatory effects of second-generation leukotriene B4 receptor antagonist,SC-53228: Impact upon Leukotriene B4- and 12(R)-HETE- mediated events

Leukotriene B₄ (LTB₄) and 12(R)-hydroxyeicosatetraenoic acid [12(R)-HETE] are proinflammatory products of arachidonic acid metabolism that have been implicated as mediators in a number of inflammatory diseases. When injected intradermally into the guinea pig, LTB₄ and 12(R)-HETE elicit a dose-dependent migration (chemotaxis) of neutrophils (PMNs) into the injection sites as assessed by the presence of a neutrophil marker enzyme myeloperoxidase. SC-41930 {7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)propoxyl]-3,4-dihydro-8-propyl-2H-1-benzopyran-2-carboxylic acid}, a first-generation LTB₄ receptor antagonist, inhibited the chemotactic actions of LTB₄ when given orally with an ED₅₀ value of 1.7 mg/kg. The second-generation LTB₄ receptor antagonist, SC-53228 [(+)-(S)-7-(3-{2-(cyclopropylmethyl)-3-methoxy-4-[(methylamino)carbonyl]phenoxy} propoxy)-3,4-dihydro-8-propyl-2H-1-benzopyran-2-propanoic acid], inhibited LTB₄-induced chemotaxis when given intragastrically with an ED₅₀ value of 0.07 mg/kg. Furthermore, SC-53228 inhibited 12(R)-HETE-induced granulocyte chemotaxis with an oral ED₅₀ value of 5.8 mg/kg. When dosed orally over a range of 0.03–100 mg/kg, SC-53228 gaveC _max plasma concentrations of 0.015–41.1g/ml. SC-53228 inhibited LTB₄-primed membrane depolarization of human neutrophils with an IC₅₀ value of 34 nM. As a potent LTB₄ receptor antagonist, SC-53228 may well have application in the medical management of disease states such as asthma, rheumatoid arthritis, inflammatory bowel disease, contact dermatitis, and psoriasis, in which LTB₄ and/or 12(R)-HETE are implicated as inflammatory mediators.     

Anti-inflammatory activity of the leukotriene B4 receptor antagonist,SC-41930, in colitic cotton-top tamarins

Cotton-top tamarins (CTTs) with histologically confirmed persistent and active colitis were given the leukotriene B₄ (LTB₄) receptor antagonist, SC-41930, (10 mg/kg BW, by gavage b.i.d.) for eight weeks. Anti-inflammatory activity was evaluated by colonic biopsy, stool consistency and the level of the lipid mediators LTB₄ and prostaglandin E₂ (PGE₂) in rectal dialysates. Stool consistency did not improve with treatment but did not worsen. Blood chemistry (ALT, AST, LDH) and hematological parameters neither showed any untoward effects of SC-41930 treatment nor was there any effect on body weight. In rectal dialysate LTB₄ levels were significantly reduced from pretreatment level of 4.87±1.46 ng/ml to 1.07±0.67 and 2.45±0.13 ng/ml at 4 and 8 weeks, respectively, and higher prostaglandin E₂ (PGE₂) over time. Histologically, 5/7 improved, 1/7 remained the same and 1/7 worsened.

Oral SC-41930 treatment was safe and associated with an anti-colitic effect. The reduced LTB₄ levels (affecting granulocyte degranulation and recruitment into tissues) and increased PGE₂ (perhaps exerting a mucosal protective effect) may, in part explain the observed efficacy of this compound in active tamarin colitis. Use of the CTT model could provide insight into the inflammatory mediator contribution to idiopathic colitis and serve as a useful bridge between preclinical pharmacology and the assessment of these compounds in the medical management of human inflammatory bowel disease.

     

Effect of the leukotriene B4 receptor antagonist,SC-41930, on experimental allergic encephalomyelitis (EAE) in the guinea pig

The accepted model for the human demyelinating disease, multiple sclerosis (MS), is experimental allergic encephalomyelitis (EAE). We assessed the ability of SC-41930(7-[3(4-acetyl-3-methoxy-2-propylphenoxy)-propoxy]-3,4-dihydro-8-propyl-2H-1-benzopyran-2-carboxyl acid), to modulate the symptoms of acute EAE generated in guinea pigs. Animals were pretreated with SC-41930 (20 mg/kg, i.p.) for two days followed by thrice-weekly maintenance. At day 52, a significant number of the SC-41930-treated animals were alive as compared to EAE alone. Control animals had an increase in body weight while EAE animals lost over 20% (p<0.5) of their body weight by day 18. SC-41930-treatment significantly reduced, but did not completely inhibit the cachectic response. The results indirectly implicate LTB₄ in the pathogenesis of EAE. Agents that modify this model be useful in the treatment of human MS.     

Effects of leukotriene B4 receptor antagonist, LY293111Na, on antigen-induced bronchial hyperresponsiveness and leukocyte infiltration in sensitized guinea pigs

OBJECTIVE AND DESIGN: LY29311 Na, 2-[2-propyl-3-[3-[2-ethyl-4-(4-fluorophenyl)-5-hydroxyphenoxy] propoxy] -phenoxy]-benzoic acid sodium salt, is a novel leukotriene B4 (LTB4) receptor antagonist. Its effects on guinea pig models of asthma were compared with those of dexamethasone. METHODS: Effects of LY293111Na were tested in antigen (ovalbumin, OA)-induced bronchial hyperresponsiveness (BHR) and leukocyte accumulation in actively sensitized guinea pigs. Its effects on antigen-induced acute bronchoconstriction in passively sensitized guinea pigs were also studied. RESULTS: LY293111 Na (10 to 30 mg/kg p.o., 1 h before and 6 h after OA challenge) inhibited BHR to acetylcholine. LY293111 Na (3 mg/kg p. o.) significantly inhibited accumulation of neutrophils in bronchoalveolar lavage (BAL) fluid 24 h after antigen challenge but it did not inhibit accumulation of eosinophils and macrophages at any doses used. In contrast, dexamethasone (30 mg/kg p.o., 4 h before OA challenge) not only inhibited BHR but also reduced the infiltration of all three types of leukocytes. A significant increase of LTB4 levels in BAL fluid was noted at 3 and 15 min after the antigen challenge. LY293111Na did not inhibit antigen-induced acute bronchoconstriction in passively sensitized guinea pigs. CONCLUSION: These results indicate that LTB4 may participate in antigen-induced BHR but not in eosinophil infiltration and acute bronchoconstriction in guinea pigs.     

Antagonism of the in vivo and in vitro effects of leukotriene D4 by SC-39070 in guinea pigs

Leukotriene D₄ (LTD₄) causes contractions of guinea pig isolated ilea, evokes pulmonary bronchoconstriction and induces lesions of the dermal vasculature. In the present study, we assessed the antagonism of these actions by SC-39070 compared to FPL-55712, a known LTD₄ receptor antagonist. In guinea pig isolated ileum preparations, SC-39070 displayed selective antagonism of LTD₄ with a pA₂=8.20±0.06 (S.E.) and a Schild plot slope of –1.20. Administered intravenously to artificially-respired guinea pigs one minute prior to the agonist, SC-39070 antagonized (p<0.05) the bronchoconstrictive effect of LTD₄ in a dose-dependent manner (0.5–10 mg/kg). At a dose of 2.0 mg/kg, i.v. this activity was retained through a 60 minute pretreatment interval. Similarly, after oral administration of SC-39070, there was a dose-dependent antagonism of the bronchoconstrictive activity of LTD₄ (MED₅₀=3.8 mg/kg). Antagonism of LTD₄-induced bronchoconstriction was evidenced after oral administration of SC-39070 within one hour of treatment and efficacy was retained as long as 20 hours after treatment at a dose of 10 mg/kg. Finally, intravenously administered SC-39070 blocked LTD₄-induced dermal permeability in guinea pigs with a minimum effective dose of 1.0 mg/kg. In each assay, the LTD₄ antagonism evidence after treatment with SC-39070 appeared to be equal to or greater than that observed after treatment with FPL-55712.     

The effect of leukotriene-B4 receptor antagonist,SC-41930, on acetic acid-induced colonic inflammation

SC-41930, 7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)-propoxy]-3,4-dihydro-8-propyl-2H-1-benzopyran-2-carboxylic acid, is a potentin vitro leukotriene-B₄ (LTB₄) receptor antagonist. LTB₄ levels are elevated in colonic tissue of inflammatory bowel disease (IBD) patients which may account for the high degree of neutrophil (PMN) infiltration. The guinea pig acetic acid-induced colonic inflammation model has characteristics of IBD including PMN infiltration, edema, ulceration and necrosis. The model was used to evaluate the effect of SC-41930. SC-41930 was given orally, 30 min before and after intrarectal administration of 3% acetic acid. The PMN marker enzyme, myeloperoxidase, was measured along with histological evaluation to assess inflammation. Both parameters showed significantly less inflammation in SC-41930 treated animals with an oral ED₅₀ of 20 mg/kg. These study results with an LTB₄ receptor antagonist indicate a role for LTB₄ in colonic inflammation and that an LTB₄ receptor antagonist may be beneficial for treatment of IBD.     

Effect of a leukotriene B4 receptor antagonist on leukotriene B4-induced neutrophil chemotaxis in cavine dermis

Leukotriene B₄ (LTB₄) is a proinflammatory product of arachidonic acid metabolism that has been implicated as a mediator in a number of inflammatory diseases. When injected intradermally into the cavine, LTB₄ elicits a dose-dependent immigration (chemotaxis) of neutrophils (PMNs) into the injection sites as assessed by the presence of a neutrophil marker enzyme myeloperoxidase. SC-41930 {7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)propoxy]-3,4-dihydro-8-propyl-2H-l-benzopyran-2-carboxylic acid, a potent LTB₄ receptor antagonist inhibited the chemotactic actions of LTB₄ when coadministered into the dermal site and when given intravenously or orally with ED₅₀ values of 200 ng, 0.5 mg/kg, and 0.6 mg/ kg respectively. This compound may well have application in disease states, such as inflammatory bowel disease and psoriasis, where LTB₄ is implicated as a proinflammatory mediator.     

Inhibition of ovulation in the rat by a leukotriene B(4) receptor antagonist

The involvement of leukotriene (LT) B(4) in the ovulatory process of the rat was investigated by the use of a LTB(4)-receptor antagonist (ZK158252 = L-ANT) administered either intrabursally in vivo or to the in-vitro perfused ovary. The in-vivo experiments revealed inhibition of human chorionic gonadotrophin (HCG)-induced ovulation by 500 micromol/l L-ANT (median 5.5, 25-75% range 1.0-6.0) compared with controls (median 9.0, range 6.25-13.5). In vitro, ovulation was induced by LH (0.2 microg/ml) + 3-isobutyl-1-methylxanthine (IBMX; 0.2 mmol/l). The ovary was perfused either for 20 h, to study ovulation rate, or for 10 h to examine ovarian concentrations of the ovulatory mediators matrix metalloproteinase (MMP)-2 and MMP-9, plasminogen activator (PA), prostaglandin (PG)E(2) and PGF(2 alpha). Addition of LH+IBMX resulted in a marked stimulation of steroid release and ovulations occurred in all ovaries (median 11.0, range 10.0-14.0). The L-ANT inhibited ovulation in a dose-dependent way (median 10.0, range 8.0-13.0 at 1 micromol/l; median 6.0, range 3.5-10.0 at 10 micromol/l; median 2.0, range 0.75-5.75 at 100 micromol/l). The intra-ovarian activity of PA was increased 1.5-fold by L-ANT (100 micromol/l), but the concentrations of PGE(2) and PGF(2 alpha) remained unaltered. While no changes in MMP-9 were observed, conversion from pro-MMP-2 to active MMP-2 was inhibited by L-ANT. These results suggest that activation of the LTB(4)-receptor within the ovary is involved in the ovulatory process and that the effects of LTB(4)-receptor activation are partly mediated via MMP-2.     

A selective H4R antagonist prevents antigen-induced asthma-like reaction and airway inflammation in guinea pigs

Objective:  Curdlan, an extracellular bacterial polysaccharide, is a linear β-1,3-glucan. Previously, we developed Curdlan-oligo (CRDO). We investigated its effect on the production of cytokines in leukocytes from mice, and compared its activity with that of SCG, a 6-branched 1,3-β-glucan. Methods:  Splenocytes from DBA/2 mice were cultured with CRDO or SCG (0, 1, 10 or 100 μg/ml) in vitro, and then the supernatants were collected to measure cytokines. Bone marrow-derived dendritic cells (BMDCs) were cultured with CRDO (0, 1, 10 or 100 ng/ml) in vitro, and then the supernatant was collected to measure cytokines. Results:  SCG stimulated splenocytes in DBA/2 mice to produce GM-CSF, IFN-γ and TNF-α. CRDO induced production of GM-CSF and IFN-γ, but not TNF-α. The amounts of GM-CSF and IFN-γ were small compared with those produced in response to SCG. The effect of SCG on TNF-α production was partially inhibited by CRDO. In bone marrow-derived dendritic cells, CRDO induced production of TNF-α and IL-6. Conclusion:  Taken together, these results suggest that CRDO stimulated mouse leukocytes to induce the production of cytokines, and the mechanism of the effect of CRDO on leukocytes is different from that of SCG. Received 30 June 2008; returned for revision 5 August 2008; received from final revision 3 September 2008; accepted by A. Bauhofer 22 September 2008     

The design and synthesis of second generation leukotriene B4 (LTB4) receptor antagonists related to SC-41930

SC-41930, 7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)propoxy]-3,4-dihydro-8-propyl-2H-1-benzopyran-2-carboxylic acid, is a selective, orally active, LTB₄ receptor antagonist currently in clinical trials for psoriasis and ulcerative colitis. Exhaustive SAR studies found a potential backup compound, SC-50605, which was 7–16 times more potent than SC-41930 in LTB₄ receptor binding, chemotaxis and degranulation assays. SC-50605 also inhibited LTB₄-induced intradermal chemotaxis in cavine skin at an oral dose of 0.10 mg/kg and displayed good activity in animal models of colitis and epidermal inflammation both orally and topically.     

SC-41930, a leukotriene B4 receptor antagonist,inhibits 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE) binding to epidermal cells

SC-41930, 7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)-propoxyl]-3,4-dihydro-8-propyl-2H-1-benzopyran-2-carboxylic acid, a potent leukotriene-B₄ (LTB₄) receptor antagonist, inhibitsin vivo 12-hydroxyei-cosatetraenoic acid (12-HETE)-induced neutrophil infiltration, suggesting a potential 12-HETE receptor antagonist effect, as well. Since 12-HETE is assumed to have a pathophysiological role in inflammatory skin diseases, and epidermal cells possess high affinity binding sites for 12(S)-HETE, we studied the effect of SC-41930 on 12(S)-HETE binding to the human epidermal cell line, SCL-II. SC-41930 antagonized the 12(S)-HETE binding to SCL-II cells with a Ki of 480 nM. This Ki value is similar to that obtained for the inhibition of LTB₄ binding to human neutrophils. Our results show that SC-41930, in addition to its LTB₄ receptor antagonist effect, exhibits 12-HETE receptor antagonist effect as well, and therefore may be of benefit in skin diseases with elevated 12-HETE levels.Dr. Kemény is on leave from the Department of Dermatology, Albert Szent-Györgyi Medical University, Szeged, Hungary, as a recipient of the Humboldt Fellowship, and his work was supported by the Alexander von Humboldt Foundation.     

Inhibition of antigen-induced arthritis in guinea pigs by a selective LTB4 receptor antagonist LY293111Na

OBJECTIVE AND DESIGN: To investigate the role of leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) in the development and progression of antigen-induced arthritis (AIA) in guinea pigs and rats. METHODS: Arthritis was induced by injecting cationic amidated bovine serum albumin (aBSA) into the knee joint of immunized guinea pigs or rats. The effect of a potent and selective LTB4 receptor antagonist, LY29311INa (2-[2-propyl-3-[3-[2-ethyl-4-(4-fluorophenyl)-5-hydroxyphenoxy]-propoxy]-phenoxy]benzoic acid sodium salt) was compared with those of indomethacin and dexamethasone. The effect of LY293111Na on adjuvant arthritis in rats was also examined. RESULTS: LY293 111Na (5 to 50 mg/kg b.i.d.) significantly inhibited knee joint swelling and histopathological changes of AIA in guinea pigs, but not in rats. Especially its protective effect against bone and cartilage destruction was substantial. In contrast, the cyclooxygenase inhibitor indomethacin significantly inhibited AIA in rats, but slightly inhibited in guinea pigs, while dexamethasone markedly inhibited AIA in both guinea pigs and rats. Increases of LTB4 and myeloperoxidase (MPO) activity were observed in the knee joint tissue of AIA guinea pigs, and LY293111Na dose-dependently inhibited the increase of MPO activity. Moreover, in adjuvant arthritic rats, LY293111Na showed slight inhibitory effect, while indomethacin showed marked inhibition. CONCLUSIONS: LTB4 but not PGE2 appeared to play important roles as an effective mediator in joint, particularly in cartilage and bone destruction of AIA in guinea pigs probably by inducing polymorphonuclear leukocytes (PMNs) chemotaxis to the joint tissue. In contrast, PGE2 but not LTB4 is an important mediator of arthritis in rats.     

Muscarinic receptors, leukotriene B4 production and neutrophilic inflammation in COPD patients

BACKGROUND: Acetylcholine (ACh) plays an important role in smooth muscle contraction and in the development of airway narrowing; preliminary evidences led us to hypothesize that ACh might also play a role in the development of airways inflammation in chronic obstructive pulmonary disease (COPD). METHODS: We evaluated the concentrations of leukotriene B4 (LTB4) in induced sputum, and the expression of Ach M1, M2, and M3 receptors in sputum cells (SC) obtained from 16 patients with COPD, 11 smokers, and 14 control subjects. The SC were also treated with ACh and the production of LTB4 assessed in the presence or absence of a muscarinic antagonist (oxitropium). In blood monocytes, we evaluated LTB4 release and activation of the extracellular signal-regulated kinases (ERK) pathway after treatment with Ach. RESULTS: The LTB4 concentrations were higher in COPD than in controls (P < 0.01) and correlated with the number of neutrophil (P < 0.01). The M3 receptors expression was increased in COPD subjects when compared to smokers and control (P < 0.05 and 0.0001, respectively), while M2 expression resulted decreased (P < 0.05 and 0.01). The ACh-induced LTB(4) production was observed in peripheral blood monocytes, and was sensitive to ERK inhibition. Similarly, ACh significantly increased neutrophil chemotactic activity and LTB4 released from SC of COPD patients only, and these effects were blocked by pretreatment with the inhibitor of ERK pathway PD98059. CONCLUSIONS: The results obtained show that muscarinic receptors may be involved in airway inflammation in COPD subjects through ACh-induced, ERK1/2-dependent LTB4 release. Muscarinic antagonism may contribute to reduce neutrophil infiltration and activation in COPD.     

Attenuation of allergic airway inflammation in IL-4 deficient mice

To investigate the role of IL-4 in vivo in allergic asthma, we developed a murine model of allergen-induced airway inflammation. Repealed daily exposures of actively immunised C57BL/6 mice to aerosolized ovalbumin (OVA) induced a peribronchial inflammation and an increase in eosinophils and lymphocytes in bronchoalveolar-lavage(BAL) fluid. In IL-4 deficient (IL4^?/?) mice, treated in the same way, there were substantially fewer eosinophils in BAL and much less peribronchial inflammation compared with wild type mice. In this model, mast cell deficient (W/W^v) mice developed a similar degree of BAL eosinophilia and peribronchial inflammation as wild type mice, demonstrating that the mast cell is not required for the induction of chronic airway inflammation. In contrast, BAL eosinophilia and airway inflammation were absent in OVA-treated MHC ClassII deficient (B6.Aa^?/?) mice which lack mature CD4⁺ T lymphocytes. In conclusion, these results indicate that IL-4 is a central mediator of allergic airway inflammation, regulating antigen-induced eosinophil recruitment into the airways by a T cell dependent mechanism.     

Effects of a leukotriene receptor antagonist on exhaled leukotriene E4 and prostanoids in children with asthma

BACKGROUND: Leukotriene (LT) E(4) and 8-isoprostane concentrations are elevated in exhaled breath condensate in children with asthma. The effects of leukotriene receptor antagonists (LTRAs) on exhaled leukotriene and prostanoids in children with asthma are unknown. OBJECTIVE: (1) To study the effect of montelukast, a LTRA, on exhaled LTE(4), 8-isoprostane, and prostaglandin E(2) in children with asthma and atopic children; (2) to measure exhaled nitric oxide. METHODS: An open-label study with oral montelukast (5 mg once daily for 4 weeks) was undertaken in 17 atopic children with asthma and 16 atopic children without asthma. RESULTS: Pretreatment exhaled LTE(4) (P < .0001) and 8-isoprostane (P < .0001) values were higher in atopic children with asthma than in atopic children without asthma. In atopic children with asthma, montelukast reduced exhaled LTE(4) by 33% (P < .001), and this reduction was correlated with pretreatment LTE(4) values (r = -0.90; P = .0001). Posttreatment exhaled LTE(4) levels in children with asthma were higher than pretreatment LTE(4) values in atopic children without asthma (P < .004). Montelukast had no effect on exhaled LTE(4) in atopic children without asthma (P = .74), or on exhaled 8-isoprostane (atopic children with asthma, P = .94; atopic children without asthma, P = .55) and PGE(2) (atopic children with asthma, P = .56; atopic children without asthma, P = .93) in both groups. In atopic children with asthma, exhaled nitric oxide concentrations were reduced by 27% (P < .05) after montelukast. CONCLUSION: Leukotriene receptor antagonists decrease exhaled LTE(4) in atopic children with asthma. This reduction is dependent on baseline exhaled LTE(4) values. CLINICAL IMPLICATIONS: Measurement of exhaled LTE(4) might help identify children with asthma most likely to benefit from LTRAs.