Lexipafant (BB-882), a platelet activating factor receptor antagonist, ameliorates mucosal inflammation in an animal model of colitis

Potential functional and pathological side effects related to off-target pharmacological activity

Most pharmaceutical companies test their discovery-stage proprietary molecules in a battery of in vitro pharmacology assays to try to determine off-target interactions. During all phases of drug discovery and development, various questions arise regarding potential side effects associated with such off-target pharmacological activity. Here we present a scientific literature curation effort undertaken to determine and summarize the most likely functional and pathological outcomes associated with interactions at 70 receptors, enzymes, ion channels and transporters with established links to adverse effects. To that end, the scientific literature was reviewed using an on-line database, and the most commonly reported effects were summarized in tabular format. The resultant table should serve as a practical guide for research scientists and clinical investigators for the prediction and interpretation of adverse side effects associated with molecules interacting with components of this screening battery.

Role of platelet-activating factor in the pathogenesis of 5-fluorouracil-induced intestinal mucositis in mice

PURPOSE

Gastrointestinal mucositis is a common side effect of cancer chemotherapy. Platelet-activating factor (PAF) is produced during gut inflammation. There is no evidence that PAF participates in antineoplastic-induced intestinal mucositis. This study evaluated the role of PAF in 5-fluorouracil (5-FU)-induced intestinal mucositis using a pharmacological approach and PAF receptor knockout mice (PAFR(-/-)).

METHODS

Wild-type mice or PAFR(-/-) mice were treated with 5-FU (450 mg/kg, i.p.). Other mice were treated with saline or BN52021 (20 mg/kg, s.c.), an antagonist of the PAF receptor, once daily followed by 5-FU administration. After the third day of treatment, animals were sacrificed and tissue samples from the duodenum were removed for morphologic evaluation. In addition, myeloperoxidase activity and the cytokine concentration were measured.

RESULTS

5-FU treatment decreased the duodenal villus height/crypt depth ratio, increased MPO activity, and increased the concentration of TNF-α, IL-1β and KC in comparison with saline-treated animals. In PAFR(-/-) mice and PAFR antagonist-treated mice, 5-FU-dependent intestinal damage was reduced and a decrease in duodenal villus height/crypt depth ratio was attenuated. However, the 5-FU-dependent increase in duodenum MPO activity was not affected. Without PAFR activation, 5-FU treatment did not increase the TNF-α, IL-1β and KC concentration.

CONCLUSIONS

In conclusion, our study establishes the role of PAFR activation in 5-FU-induced intestinal mucositis. This study implicates treatment with PAFR antagonists as novel therapeutic strategy for this condition.

Platelet-activating factor-induced NF-kappaB activation and IL-8 production in intestinal epithelial cells are Bcl10-dependent

BACKGROUND

Platelet-activating factor (PAF), a potent proinflammatory phospholipid mediator, has been implicated in inducing intestinal inflammation in diseases such as inflammatory bowel disease (IBD) and necrotizing enterocolitis (NEC). However, its mechanisms of inducing inflammatory responses are not fully understood. Therefore, studies were designed to explore the mechanisms of PAF-induced inflammatory cascade in intestinal epithelial cells.

METHODS

Nuclear factor kappa B (NF-kappaB) activation was measured by luciferase assay and enzyme-linked immunosorbent assay (ELISA), and interleukin 8 (IL-8) production was determined by ELISA. B-cell lymphoma 10 (Bcl10), caspase recruitment domain-containing membrane-associated guanylate kinase protein 3 (CARMA3), and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) mRNA and protein levels were assessed by real-time reverse-transcription polymerase chain reaction (RT-PCR) and Western blot, respectively. siRNA silencing of Bcl10 was used to examine its role in PAF-induced NF-kappaB activation and IL-8 production. The promoter region of the Bcl10 gene was cloned with the PCR method and promoter activity measured by luciferase assay.

RESULTS

The adaptor protein Bcl10 appeared to play an important role in the PAF-induced inflammatory pathway in human intestinal epithelial cells. Bcl10 was required for PAF-induced I kappaB alpha phosphorylation, NF-kappaB activation, and IL-8 production in NCM460, a cell line derived from normal human colon, and Caco-2, a transformed human intestinal cell line. PAF also stimulated Bcl10 interactions with CARMA3 and MALT1, and upregulated Bcl10 expression in these cells via transcriptional regulation.

CONCLUSIONS

These findings highlight a novel PAF-induced inflammatory pathway in intestinal epithelial cells, requiring Bcl10 as a critical mediator and involving CARMA3/Bcl10/MALT1 interactions. The proinflammatory effects of PAF play prominent roles in the pathogenesis of IBD and this pathway may present important targets for intervention in chronic inflammatory diseases of the intestine.

Current view of the immunopathogenesis in inflammatory bowel disease and its implications for therapy

Although the aetiology of inflammatory bowel disease (IBD) remains unknown, the pathogenesis is gradually being unravelled, seeming to be the result of a combination of environmental, genetic, and immunological factors in which an uncontrolled immune response within the intestinal lumen leads to inflammation in genetically predisposed individuals. Multifactorial evidence suggests that a defect of innate immune response to microbial agents is involved in IBD. This editorial outlines the immunopathogenesis of IBD and their current and future therapy. We present IBD as a result of dysregulated mucosal response in the intestinal wall facilitated by defects in epithelial barrier function and the mucosal immune system with excessive production of cytokines growth factors, adhesion molecules, and reactive oxygen metabolites, resulting in tissue injury. Established and evolving therapies are discussed in the second part of this editorial and at the end of this section we review new therapies to modulate the immune system in patients with IBD.

Involvement of endogenous leukotriene B4 and platelet-activating factor in polymorphonuclear leucocyte recruitment to dermal inflammatory sites in rats

A critical role for leukotriene B(4) (LTB(4)) and/or platelet-activating factor (PAF) in regulating polymorphonuclear cell (PMN) trafficking to inflammatory sites has been reported in a number of experimental inflammatory models. In vitro, newly synthesized LTB(4) and PAF were shown to act in an autocrine/paracrine or intracrine fashion to enhance intracellular arachidonic acid availability and leukotriene biosynthesis. This suggested potentially cooperative effects of these lipid mediators in regulating PMN extravasation. The present study aimed to elucidate whether endogenous LTB(4) and PAF may both act to regulate plasma extravasation and PMN trafficking to inflammatory sites in experimental inflammation. With this aim, we have used selective and potent PAF and LTB(4) receptor antagonist pretreatments in dermal and pulmonary inflammation models in rats. Our results show additive inhibitory effects of dual LTB(4) and PAF receptor blockade in either PAF- or LTB(4)-elicited cutaneous PMN accumulation compared to single-drug administration. Furthermore, the combined administration of the drugs inhibited the PMN accumulation induced by the chemically unrelated soluble agonists tumour necrosis factor-alpha and C5a. Finally, in a model of pulmonary inflammation induced by the intravenous injection of Sephadex beads, lung neutrophilia was reduced by 63% following the administration of LTB(4) and PAF antagonists, in contrast with the lack of effect of single drug administration. Our results strongly support a role of both endogenous LTB(4) and PAF in regulating PMN trafficking to inflammatory sites in various experimental conditions.

Novel approaches to inflammatory bowel disease

Ulcerative colitis and Crohn's disease, collectively known as inflammatory bowel disease (IBD), are chronic, spontaneously relapsing disorders of unknown cause. These diseases appear to be immunologically mediated and have genetic and environmental influences. Although the cause of these diseases remains obscure, the pathogenesis of chronic intestinal inflammation is becoming clearer, due to improved animal models of enterocolitis and important advances in immunological techniques. Traditional therapy for IBD, although helping to induce and maintain disease remission, does little to alter the underlying fundamental disease process. New IBD therapy has not developed significantly over the past twenty years and includes 5-aminosalicylic acid preparations, corticosteroids and immunomodulatory agents, such as azathioprine, 6-mercaptopurine and methotrexate. There is, therefore, a need for new, specific disease-modifying therapy and the development of such therapy has been hastened by a greater understanding of the pathophysiology of IBD. This review examines the most recent novel therapies for IBD, with specific emphasis on immunomodulatory and novel anti-inflammatory therapies. Recent clinical trials are reviewed, and the potential advances and clinical impact that these novel agents may provide are discussed.

Effects of molsidomine and lexipafant in hepatic ischaemia--reperfusion injury

PURPOSE

The purpose of this study was to evaluate the effects of nitric oxide donor molsidomine and platelet-activating factor (PAF) antagonist lexipafant on the hepatic IR injury in rats.

METHODS

Fifty male Sprague-Dawley rats (200-225 g) were divided into five groups each containing 10 rats; group SO: Sham operation group; group I: hepatic ischaemia group; group IR: ischaemia-reperfusion (IR); group M: IR plus pretreatment with molsidomine; group L: IR plus pretreatment with lexipafant. Hepatic ischaemia and reperfusion, each were applied for 45 min. Hepatic specimens were obtained to determine the tissue levels of malondialdehyde (MDA) and histological changes. Blood samples were obtained by cardiac puncture for determination of alanine transaminase (ALT), aspartate transaminase (AST) and lactic dehydrogenase (LDH).

RESULTS

The liver damage scores of groups I, IR, M and L were significantly higher than that of group SO (P < 0.001). The liver damage scores of groups IR and M were significantly higher than that of group I (P = 0.009 and 0.0035, respectively). The liver damage scores of groups M and L were significantly lower than that of group IR (P < 0.001 for both M and L). Mean MDA levels of groups I and IR were significantly higher than those of group SO (P < 0.001). Administrations of molsidomine and lexipafant prior to ischaemia-reperfusion (IR) resulted in significant reduction of the MDA values (P < 0.001). A statistically significant (P < 0.001) decrease in the levels of AST, ALT and LDH was observed in groups M and L compared with group IR.

CONCLUSION

In conclusion, these observations suggest that pre-treatment with nitric oxide donor molsidomine and PAF antagonist lexipafant before the reperfusion period may be useful in preventing hepatic reperfusion injury.

The intestinal anti-inflammatory activity of UR-12746S on reactivated experimental colitis is mediated through downregulation of cytokine production

BACKGROUND

UR-12746S (dersalazine sodium) is cleaved by colonic bacteria delivering the PAF antagonist UR-12715 and 5-ASA. This study describes the anti-inflammatory activity of UR-12746S in an experimental model of reactivated colitis and its effects on cytokine production.

METHODS

Rats were initially rendered colitic by a colonic instillation of 10 mg of trinitrobenzenesulphonic acid (TNBS) dissolved in 0.25 ml of 50 % ethanol, and colitis was reactivated two weeks after by a second administration of the same dose of TNBS. Two groups of colitic rats received UR-12746S (25 and 50 mg/kg daily, p.o.) and colonic damage was evaluated every week for 4 weeks. Different biochemical markers of colonic inflammation were assayed: MPO activity and cytokine (IL-1beta and TNFalpha) levels. Also, the in vitro effects of UR-12715 and 5-ASA on cytokine production were assayed.

RESULTS

UR-12746S showed anti-inflammatory effect in reactivated colitis in rats, as evidenced by a significant reduction in MPO activity. Both doses of UR-12746S decreased IL-1beta production, while only the highest dose assayed inhibited TNFalpha production. In vitro studies revealed that UR-12715 or 5-ASA (from 10(-6) to 10(-4) M) inhibited IL-8 production (30-40%) in HT-29 cells when incubated with LPS. This inhibitory effect was enhanced when both compounds were administered simultaneously at 10(-4) M. In addition, UR-12715 inhibited IL-1beta or TNFalpha production in THP-1 or U937 cells, respectively, when these cells were stimulated by PMA and LPS; whereas 5-ASA only showed a weak effect in inhibiting IL-1beta production.

CONCLUSION

UR-12746S was able to prevent relapse in experimental colitis and inhibition of proinflammatory cytokine production participates in the intestinal anti-inflammatory activity exerted by this compound.

Platelet-activating factor regulates chloride transport in colonic epithelial cell monolayers

Platelet-activating factor (PAF) has been implicated in the pathogenesis of gastrointestinal diseases such as necrotizing enterocolitis, Crohn's disease, and ulcerative colitis. However, neither the physiologic role of PAF in the intestine, nor the mechanisms by which PAF participates in the pathogenesis of disease are well understood. The aim of the present study was to determine the direct effect of PAF on intestinal epithelial cell ion transport, and to delineate the mechanisms of regulation. Ion transport was evaluated by measuring short circuit current (I(sc)) in HT29-CL19A cell monolayers using Ussing chambers. PAF receptor polarity was assessed using domain-selective biotinylation followed by immunoprecipitation and streptavidin blotting of intact epithelial monolayers. PAF (1-200 microM) stimulated I(sc) that followed the direction of a Cl(-) gradient and was specifically inhibited by the Cl(-) channel blockers glybenclamide, 2,2' iminodibenzoic acid and 4,4' diisothiocyanostilbene-2, 2' disulfonic acid, but was unaffected by the inhibition of prostaglandin synthesis with indomethacin. Stimulated I(sc) was only detected after apical addition of PAF, correlating with the results of biotinylation experiments indicating an exclusive apical polarity of the PAF receptor. PAF receptor antagonists CV6209 and octylonium bromide abolished PAF-stimulated I(sc). Thus, mucosal acting PAF directly and specifically stimulates ion transport via activation of an apical Cl(-) channel in intestinal epithelial cell monolayers independent of prostaglandin biosynthesis.

E3040 sulphate, a novel thromboxane synthase inhibitor, blocks the Cl- secretion induced by platelet-activating factor in isolated rat colon

1. E3040 (6-hydroxy-5,7-dimethyl-2-methylamino-4-(3-pyridylmethyl)benzothiazole), is a novel dual inhibitor of 5-lipoxygenase (5-LOX) and thromboxane synthase (Tx synthase). Here, we examined the effects of E3040 sulphate, a sulphate conjugate of E3040, on these enzyme activities in cell-free systems and on the thromboxane A2 (TxA2)-mediated Cl- secretion induced by platelet-activating factor (PAF) in isolated rat colons. 2. E3040 sulphate inhibited Tx synthase activity in a concentration-dependent manner (IC50=0.013 microM), whereas it induced little effects on 5-LOX and cyclo-oxygenase activities (IC50>100 microM) with the cell-free enzyme assay. 3. With isolated rat colonic mucosa, E3040 sulphate in a concentration-dependent manner (IC50=1.8 microM) inhibited the Cl- secretion induced by 10 microM PAF. On the other hand, E3040 sulphate (30 microM) induced no effect on the prostaglandin E2 (0.5 microM)- and leukotriene D4 (1 microM)-induced Cl- secretion in the colon. 4. PAF (10 microM) increased a release of TxB2, a stable metabolite of TxA2, from the colonic mucosa. This increase was significantly inhibited by subsequent addition of E3040 sulphate (30 microM). 5. Probenecid (100 microM), an inhibitor of organic anion transporter, abolished the inhibitory effect of E3040 sulphate on the PAF-induced Cl- secretion. Another inhibitor, sulphobromophthalein (30 microM) partially but significantly attenuated the effect of E3040 sulphate. p-aminohippuric acid (1 mM) had no effect. 6. These findings suggest that E3040 sulphate is a novel Tx synthase inhibitor, and that E3040 sulphate taken up into the colonic cells by organic anion transporters inhibits the PAF-induced Cl- secretion by blocking a release of TxA2.

Lexipafant inhibits postsurgical adhesion formation

BACKGROUND

PAF and its antagonists have been studied in the pathophysiology of various inflammatory conditions. This study investigates the effects of a platelet activating factor antagonist, lexipafant, on peritoneal adhesion formation and wound healing.

MATERIALS AND METHODS

Forty-eight Wistar albino rats (300-350 g) were divided into four equal groups; adhesion-induced lexipafant (AL), adhesion-induced saline (AS), sham-operated lexipafant (SL), and sham-operated saline (SS). All rats underwent a midline laparotomy under sterile conditions. The anterior wall of the left uterine horn was scraped to cause hemorrhages in adhesion-induced groups. Following peritoneal injections of either saline or lexipafant, the incisions were closed in layers. On the 14th day, the rats were killed and adhesions were scored from 0 (none) to 4 (dense). Tissue samples from the adhesions and the left horn of uterus were examined biochemically for hydroxyproline content, and serum IL-6 levels were determined.

RESULTS

The adhesion formation score was significantly increased in the AS group compared to the SL and AL groups (P < 0.001). The IL-6 levels of the AS group were higher than those of the other groups (P < 0.05). There was no significant difference in hydroxyproline content between groups (P > 0.05).

CONCLUSIONS

Lexipafant plays a role in the prevention of adhesion formation without affecting wound healing.

Reduction in glial immunity and neuropathology by a PAF antagonist and an MMP and TNFalpha inhibitor in SCID mice with HIV-1 encephalitis

The effects of anti-inflammatory drugs on glial immunity and neuropathology were determined in a severe combined immune deficiency (SCID) mouse model of HIV-1 encephalitis. HIV-1-infected human monocyte-derived macrophages (MDM) are stereotactically inoculated into basal ganglia resulting in a multinucleated giant cell encephalitis. A platelet activating factor antagonist and a matrix metalloproteinase inhibitor, which also inhibits tumor necrosis factor alpha release, were administered to animals at the time of the MDM inoculation. The drugs administered in combination markedly reduced brain inflammation, astrogliosis and microglia activation. These findings demonstrate that reduction of brain inflammatory responses, independent of viral replication, can affect HIVE pathology in an animal model system of disease.

Recent advances in inflammatory bowel disease

The last decade has seen tremendous advances in our knowledge, which has led to genuine improvements in our understanding of the pathogenesis and management of inflammatory bowel disease (IBD). The combined power of cellular and molecular biology has begun to unveil the enigmas of IBD, and, consequently, substantial gains have been made in the treatment of IBD. Refinements in drug formulation have provided the ability to target distinct sites of delivery, while enhancing the safety and efficacy of older agents. Simultaneous progress in biotechnology has fostered the development of new agents that strategically target pivotal processes in disease pathogenesis. This article addresses our current understanding of the pathogenesis of IBD, including the latest developments in animal models and covers agents currently used in the treatment of IBD as well as emerging therapies.

Intestinal anti-inflammatory activity of UR-12746, a novel 5-ASA conjugate, on acute and chronic experimental colitis in the rat

The present study was undertaken to investigate the intestinal anti-inflammatory effects of UR-12746 on the acute and chronic stages of a trinitrobenzene sulphonic acid (TNBS) experimental model of inflammatory bowel disease (IBD) in the rat. UR-12746 is a novel, locally-acting compound which combines, through an azo bond, 5-aminosalicylic (5-ASA) and UR-12715, a potent platelet activating factor (PAF)-antagonist. UR-12746 oral pretreatment of colitic rats (50 and 100 mg kg(-1)) reduced acute colonic damage when evaluated 2 days after colonic insult. Postreatment for 4 weeks with UR-12746 (50 and 100 mg kg(-1)) resulted in a faster recovery of the damaged colonic mucosa, which was macroscopically significant from the third week. The intestinal anti-inflammatory effect of UR-12746 was associated with a decrease in leukocyte infiltration in the colonic mucosa, which was evidenced both biochemically, by a reduction in myeloperoxidase activity, and histologically, by a lower leukocyte count after morphometric analysis. This effect was higher than that seen with sulphasalazine, when assayed at the same doses and in the same experimental conditions. Several mechanisms can be involved in the beneficial effects showed by UR-12746: inhibition of leukotriene B(4) synthesis in the inflamed colon, improvement of the altered colonic oxidative status, and reduction of colonic interleukin-1beta production. The results suggest that the intestinal anti-inflammatory activity of UR-12746 can be attributed to the additive effects exerted by 5-ASA and UR-12715, the PAF antagonist compound, that are released in the colonic lumen after reduction of the azo bond by the intestinal bacteria.

Thromboxane A(2)-mediated Cl(-) secretion induced by platelet-activating factor in isolated rat colon

Thromboxane A(2) is a novel endogenous secretagogue of Cl(-) secretion in the distal colon. Here, we examined if the Cl(-) secretion caused by platelet-activating factor (PAF; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is mediated by thromboxane A(2) production using isolated mucosae of the rat colon. Furosemide (100 microM) and 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB; 300 microM) completely inhibited PAF (10 microM)-induced increase in short-circuit current (Isc) across the mucosa, indicating that PAF caused a Cl(-) secretion in the rat colon. A selective thromboxane A(2) receptor antagonist (sodium(E)-11-[2-(5, 6-dimethyl-1-benzimidazolyl)-ethylidene]-6,11-dihydrobenz[b, e]oxepine-2-carboxylate monohydrate; KW-3635), and a selective thromboxane synthase inhibitor (sodium 4-[alpha-hydroxy-5-(1-imidazolyl)-2-methylbenzyl]-3, 5-dimethylbenzoate dihydrate; Y-20811) inhibited the PAF-induced Cl(-) current in a concentration-dependent manner. The IC(50) values of KW-3635 and Y-20811 were 2.1 and 0.5 microM, respectively. 30 microM KW-3635 and 1 microM Y-20811 inhibited the PAF response by 92% and 83%, respectively. These inhibitors did not affect the prostaglandin E(2)-induced increase in Isc. A 5-lipoxygenase-activating protein inhibitor (3-[1-(p-chlorobenzyl)-5-(isopropyl)-3-t-butylthioindol-2-yl]-2, 2-dimethyl-propanoic acid sodium; MK-886) (5 microM) did not affect the PAF-induced Cl(-) current. The present study suggests that the PAF-induced Cl(-) secretion in the rat colonic mucosa is mainly mediated by a release of thromboxane A(2).

Human intestinal epithelial cells express receptors for platelet-activating factor

The intestinal epithelium produces and responds to cytokines and lipid mediators that play a key role in the induction and regulation of mucosal inflammation. The lipid mediator platelet-activating factor (PAF) can be produced and degraded by the human intestinal epithelium and is known to mediate a range of proinflammatory and other biological effects in the intestinal mucosa. In the studies herein, we assessed whether or not human intestinal epithelial cells express cell surface or intracellular PAF receptors (PAF-R), whether expression of these receptors can be regulated, and whether human intestinal epithelial cells respond to PAF. Several human colon epithelial cell lines (HT-29, Caco-2, T84, HCT-8, HCA-7, I407, and LS-174T) were shown by RT-PCR to constitutively express mRNA for PAF-R. In addition, PAF-R expression was demonstrated by immunoblot analysis and PAF-R was shown to be constitutively expressed on the cell surface of several of these cell lines, as assessed by flow cytometry. PAF-R expression by human colon epithelial cells was upregulated by stimulation with retinoic acid but not by stimulation with PAF, proinflammatory agonists (tumor necrosis factor-alpha, interleukin-1, interferon-gamma), or transforming growth factor-alpha. PAF-R on intestinal epithelial cells were functional, as PAF stimulation of the cells increased tyrosine phosphorylation of several cellular proteins, including proteins of 75 and 125 kDa, and this response was blocked by a PAF-R antagonist. Consistent with the findings using cell lines, PAF-R were also constitutively expressed by normal human colon and small intestinal epithelium in vivo, as shown by immunohistology. The constitutive and regulated expression of functional PAF-R by human intestinal epithelium suggests PAF produced by the intestinal epithelial cells or cells underlying the epithelium has autocrine or paracrine effects on intestinal epithelial cells.

Treatment of ulcerative colitis

Advances in the treatment of ulcerative colitis have continued to focus on improved local delivery of existing agents, such as 5-aminosalicylate and corticosteroids, and on novel immunosuppressive agents. Although newer preparations of 5-aminosalicylate continue to provide incremental benefits in safety, tolerance, and efficacy, there is a growing understanding of the limits of benefit from increasing doses. Knowledge of the safety of these agents, particularly in regard to their use in pregnancy, continues to expand. Novel corticosteroids are used in much of the world for the treatment of ulcerative colitis, with the exception of the United States, with anticipated benefits in safety but little additional therapeutic benefit. Innovative use of oral emulsion preparations of cyclosporine has been reported in the treatment of ulcerative colitis and adds to the growing body of literature on the efficacy of cyclosporine in severe disease. Relatively limited experience with other immunosuppressive agents, such as tacrolimus, has been reported. The role of antibiotics in the treatment of ulcerative colitis has continued to present controversy.

Lack of effectiveness of the platelet-activating factor antagonist SR27417A in patients with active ulcerative colitis: a randomized controlled trial. The Platelet Activating Factor Antagonist Study Group in Ulcerative Colitis

BACKGROUND & AIMS

Platelet-activating factor (PAF) is increased during relapse of ulcerative colitis. In animal models of experimental colitis, specific inhibition of PAF has reduced inflammation. The aim of this study was to evaluate the efficacy and safety of the PAF antagonist SR27417A in moderately active UC.

METHODS

A double-blind multicenter trial was conducted during a 28-day period in hospital outpatients with an exacerbation of ulcerative colitis. Patients were randomized to receive 10 mg/day SR27417A or placebo, and both groups were also given 2.4 g mesalazine. Patient classification at the end of the treatment period was based on sigmoidoscopy and clinical scores.

RESULTS

One hundred fifty-one subjects entered the study (75 placebo and 76 SR27417A). The remission rate between placebo- and SR27417A-treated patients at 28 days was not significantly different (29.0% and 35.6% respectively; P = 0.44). Similarly, 49.2% treated with SR27417A had a definite or possible improvement of their symptom score compared with 48.3% of those treated with placebo (P = 0.43). Four subjects in the placebo group and 5 subjects in the SR27417A group discontinued the drug treatment because of adverse events. No significant adverse events were thought to be caused by SR27417A.

CONCLUSIONS

Although the specific PAF antagonist SR27417A is safe in humans, there is no evidence of efficacy in the treatment of acute ulcerative colitis.

Anti-inflammatory effect of interleukin-10 in rabbit immune complex-induced colitis

BACKGROUND

Interleukin-10 (IL-10) is an anti-inflammatory cytokine that downregulates the secretion of pro-inflammatory cytokines and additionally induces the secretion of anti-inflammatory cytokines, thus possibly leading to reduction of chronic inflammation in inflammatory bowel disease. In this study we evaluated the anti-inflammatory effect of IL-10 in a model of acute colitis in rabbits.

METHODS

Colitis was induced by rectal instillation of formalin, 0.65%, followed by intravenous infusion of 0.85 ml heat-aggregated rabbit immunoglobulin. Rabbits were treated with an intravenous bolus of recombinant human IL-10 (SCH52000), 100 microg/kg (n=14) or 500 microg/kg (n=14), 1 h before induction of colitis (control group, n=12).

RESULTS

High-dose IL-10 improved macroscopic scores of inflammation and decreased tissue myeloperoxidase levels and leukotriene B4 levels in dialysate fluid. Thromboxane B2 and prostaglandin E2 levels remained unaffected.

CONCLUSION

IL-10 ameliorates acute colitis in this model. Consequently, this anti-inflammatory cytokine may have a role in the therapy of acute inflammatory bowel disease.

The platelet-activating factor antagonist BB-882 does not improve tissue oxygen extraction in endotoxic shock

PURPOSE

We investigated whether BB-882, a novel potent PAF antagonist, could influence systemic and pulmonary hemodynamics and oxygen extraction capabilities during an acute reduction in blood flow induced by cardiac tamponade after endotoxin challenge.

MATERIALS AND METHODS

Twenty-one anesthetized, ventilated, and endotoxin-shocked (2 mg/kg i.v. Escherichia coli endotoxin) dogs were randomly divided in three groups. One group (N = 7) served as control. A second group (N = 7) received BB-882 as a single bolus dose of 5 mg/kg, 30 minutes before endotoxin administration. A third group (N = 7) received BB-882 as a continuous infusion of 5 mg/kg x h, started 30 minutes after endotoxin. Hemodynamic and gazometric measurements were obtained in all dogs 30 minutes after endotoxin injection and repeated 30 minutes after cardiac filling pressures were restored to baseline by generous saline infusion. Saline infusion rate was then set at 20 mL/kg x h and tamponade was induced by repeated bolus injections of warm saline into the pericardial sac.

RESULTS

Compared with controls, pretreatment with BB-882 attenuated the early endotoxin-induced decrease in arterial pressure (70 +/- 17 v 51 +/- 14 mm Hg, P < .05), cardiac index (118 +/- 29 v 91 +/- 15 mL/ kg x min, P < .05), stroke index (1.0 +/- 0.2 v 0.7 +/- 0.3 mL/kg, P < .05), and left ventricular stroke work index (0.9 +/- 0.3 v 0.4 +/- 0.2 g x m/kg, P < .05), but these effects were not sustained after fluid resuscitation. In contrast, BB-882 post-treatment maintained arterial pressure and improved cardiac performance at lower filling pressures in the later phase of endotoxic shock. BB-882 did not influence pulmonary hemodynamics. Treatment with BB-882 did not influence oxygen extraction at critical oxygen delivery (51.5 +/- 9.9% and 52.8 +/- 13.9% v 46.6 +/- 9.0%, respectively BB-882 pretreatment and post-treatment v control).

CONCLUSIONS

We conclude that in this model of endotoxic shock the administration of BB-882, either before or after endotoxin challenge, has time-related beneficial hemodynamic and cardiac effects but does not improve global oxygen extraction capabilities. The potential benefit of adjunctive treatment with a platelet-activating factor antagonist in sepsis remains doubtful.