Inhibition of neutrophil elastase-induced interleukin-8 gene expression by urinary trypsin inhibitor in human bronchial epithelial cells

The Inter-α-Trypsin Inhibitor Family: Versatile Molecules in Biology and Pathology

Inter-α-trypsin inhibitor (IαI) family members are ancient and unique molecules that have evolved over several hundred million years of vertebrate evolution. IαI is a complex containing the proteoglycan bikunin to which heavy chain proteins are covalently attached to the chondroitin sulfate chain. Besides its matrix protective activity through protease inhibitory action, IαI family members interact with extracellular matrix molecules and most notably hyaluronan, inhibit complement, and provide cell regulatory functions. Recent evidence for the diverse roles of the IαI family in both biology and pathology is reviewed and gives insight into their pivotal roles in tissue homeostasis. In addition, the clinical uses of these molecules are explored, such as in the treatment of inflammatory conditions including sepsis and Kawasaki disease, which has recently been associated with severe acute respiratory syndrome coronavirus 2 infection in children.

Ulinastatin suppresses lipopolysaccharide-induced prostaglandin E2 synthesis and nitric oxide production through the downregulation of nuclear factor‑κB in BV2 mouse microglial cells

Ulinastatin is an intrinsic serine-protease urinary trypsin inhibitor that can be extracted and purified from human urine. Urinary trypsin inhibitors are widely used to treat patients with acute inflammatory disorders, such as shock and pancreatitis. However, although the anti-inflammatory activities of urinary trypsin inhibitors have been investigated, the mechanisms underlying their actions are not yet fully understood. In the present study, we evaluated the effect of ulinastatin on lipopolysaccharide (LPS)-induced inflammation in relation with nuclear factor-κB (NF-κB) activation using BV2 mouse microglial cells. To accomplish this, we performed a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, reverse transcription-polymerase chain reaction (RT-PCR), western blot analysis, electrophoretic mobility gel shift assay (EMSA), prostaglandin E(2) (PGE(2)) immunoassay and nitric oxide (NO) detection. The results demonstrated that ulinastatin suppressed PGE2 synthesis and NO production by inhibiting the LPS-induced mRNA and protein expression of cyclooxygenase-2 (COX-2) and inducible NO synthase (iNOS) in BV2 mouse microglial cells. Ulinastatin suppressed the activation of NF-κB in the nucleus. These findings demonstrate that ulinastatin exerts analgesic and anti-inflammatory effects that possibly occur via the suppression of COX-2 and iNOS expression through the downregulation of NF-κB activity.

Urinary trypsin inhibitor attenuates lipopolysaccharide-induced neutrophil activation

Background

Urinary trypsin inhibitor (UTI), which is speculated to have anti-inflammatory effects, is one of serine protease inhibitors found in human urine and blood. The present study was conducted to clarify the effect of urinary trypsin inhibitor (UTI) on human neutrophil activation and its intracellular signaling mechanism in vitro.

Methods

To assess the possible interactions between UTI and lipopolysaccharide (LPS) in neutrophil activation, neutrophils from human blood were incubated with varying concentrations of UTI (1, 10, 100, 1,000 and 10,000 U/ml) plus LPS (100 ng/ml) or LPS alone in 24-well plates (5 × 10⁶ cells/well). We measured protein levels for interleukin (IL)-6 and tumor necrosis factor-alpha (TNF-α) using enzyme-linked immunosorbent assay (ELISA) kits after 4 hours of incubation period. To elucidate the intracellular signaling pathway, we also measured the levels of phosphorylation of p38, ERK1/2 and JNK via Western blot analysis. Moreover, the nuclear levels of nuclear factor-kappa B (NF-κB) were determined with electrophoretic mobility shift assays (EMSA).

Results

UTI decreased the expression of inflammatory cytokines, including TNF-α and IL-6, and activation of intracellular signaling pathways, such as JNK, but not P38, ERK1/2 and nuclear translocation of NF-κB.

Conclusions

UTI can attenuate LPS-induced neutrophil responses and may partially contribute to the treatment of neutrophil-mediated inflammatory diseases.

Anti-inflammatory effects of DX-890, a human neutrophil elastase inhibitor

BACKGROUND

Neutrophil elastase (NE)-mediated inflammation contributes to lung damage in cystic fibrosis (CF). We investigated if DX-890, a small-protein NE inhibitor, could reduce neutrophil trans-epithelial migration and reduce activity released from neutrophils and NE-induced cytokine expression in airway epithelial cells.

METHODS

Activated blood neutrophils (CF and healthy) treated ±DX-890 were assayed for NE activity. Transmigration of calcein-labeled neutrophils was studied using a 16HBE14o(-) epithelial monolayer. IL-8 release from primary nasal epithelial monolayers (CF and healthy) was measured after treatment ±DX-890 and NE or CF sputum.

RESULTS

DX-890 reduced NE activity from neutrophils (CF and healthy) and reduced neutrophil transmigration. DX-890 pre-treatment reduced IL-8 release from epithelial cells of healthy or CF subjects after stimulation with NE and CF sputum sol. All improvements with DX-890 were statistically significant (p<0.05).

CONCLUSIONS

DX-890 reduces NE-mediated transmigration and inflammation. NE inhibition could be useful in managing neutrophilic airway inflammation in CF.

Urinary trypsin inhibitor as a therapeutic option for endotoxin-related inflammatory disorders

IMPORTANCE OF THE FIELD

Urinary trypsin inhibitor (UTI), a serine protease inhibitor, has been widely used as a drug for patients with inflammatory disorders such as pancreatitis, shock and disseminated intravascular coagulation (DIC). Previous in vitro studies have demonstrated that serine protease inhibitors may have anti-inflammatory properties at sites of inflammation. However, the therapeutic effects of UTI in vivo remain unclarified, as commercial UTI has been developed to act against humans, with the activity and selectivity toward the relevant animal UTI being less characterized.

AREAS COVERED IN THIS REVIEW

In this review, we introduce the roles of UTI in experimental endotoxin (lipopolysaccharide; LPS)-related inflammatory disorders using UTI-deficient (-/-) and corresponding wild-type mice.

WHAT THE READER WILL GAIN

Our experiments using genetic approach suggest that endogenous UTI can protect against the systemic inflammatory response and subsequent organ injury induced by LPS, at least partly, through the inhibition of pro-inflammatory cytokine and chemokine expression, which provide important in vivo evidence and understanding about a protective role of UTI in inflammatory conditions.

TAKE HOME MESSAGE

Using genetically targeted mice selectively lacking UTI, UTI has been evidenced to provide an attractive 'rescue' therapeutic option for endotoxin-related inflammatory disorders such as DIC, acute lung injury and acute liver injury.

Effect of ulinastatin on cytokine reaction during gastrectomy

Background

Inflammation plays an important role in the postoperative morbidity of organs, which is related to the activation of pro-inflammatory and anti-inflammatory cytokines. Ulinastatin (Urinary trypsin inhibitor, UTI) is a serine protease inhibitor found in human urine or serum that inhibits the activation of human leukocyte elastase. This study examined the effect of UTI on the inflammation response in patients undergoing a gastrectomy.

Methods

Thirty patients scheduled to undergo a gastrectomy were divided into two groups as follows: Control group (untreated, n = 15) and UTI group (100,000 units of UTI were continuously injected intravenously for 2 hours, n = 15). Arterial blood was sampled before surgery (T0), 10 minutes after its onset (T1), at its end (T2), and 1 hour after surgery (T3) to measure the level of cytokines.

Results

Both the control and treatment groups had higher interleukin (IL)-6 levels at T2 and T3 than T0, and the level increased with time. However, the increase was smaller in the treatment group. The IL-8 levels were not activated significantly in any of the groups.

Conclusions

UTI inhibits the secretion of IL-6, which is an inflammatory cytokine produced after a gastrectomy. This shows that UTI can decrease the inflammation reaction caused by surgical stress.

Urinary trypsin inhibitor protects against liver injury and coagulation pathway dysregulation induced by lipopolysaccharide/D-galactosamine in mice

Urinary trypsin inhibitor (UTI), a serine protease inhibitor, has been widely used for patients with inflammatory disorders including disseminated intravascular coagulation, shock, and pancreatitis in Japan. Our recent studies using UTI-null (-/-) mice have shown that UTI protects against systemic inflammatory responses and acute lung injury. However, the role of UTI in liver injury has not been elucidated. This study determined the contribution of UTI to liver injury and coagulatory disturbance induced by lipopolysaccharide and D-galactosamine (LPS/D-GalN) using UTI (-/-) and wild-type (WT) mice. LPS/D-GalN treatment caused severe liver injury characterized by neutrophilic inflammation, hemorrhagic change, necrosis, and apoptosis, which was more prominent in UTI (-/-) than in WT mice. In both genotypes of mice, LPS/D-GalN challenge caused elevations of aspartate amino-transferase and alanine amino-transferase, prolongation of the prothrombin and activated partial thromboplastin time, and decreases in fibrinogen and platelet counts, as compared with vehicle challenge. These changes, however, were significantly greater in UTI (-/-) than in WT mice. Circulatory levels of tumor necrosis factor (TNF)-alpha (P<0.05) and interferon (IFN)-gamma were also greater in UTI (-/-) than in WT mice after LPS/D-GalN challenge. These results suggest that UTI protects against severe liver injury and subsequent coagulatory disturbance induced by LPS/D-GalN, which was mediated, at least partly, through the suppression of TNF-alpha production along with its antiprotease activity.

Urinary trypsin inhibitor present in fetal urine prevents intraamniotic meconium-induced intestinal damage in gastroschisis

BACKGROUND/PURPOSE

Contact with amniotic fluid causes intestinal damage in gastroschisis, and intraamniotic meconium has been shown to be responsible. Meconium has been shown to contain a significant amount of IL-8, which may be the responsible cytokine for harmful effects of meconium. Neonatal urine contains high amount of urinary trypsin inhibitor (UTI) compared with adult human urine. Urinary trypsin inhibitor has been shown to exert inhibitory effects on IL-8. Therefore, far from being destructive, presence of fetal urine in the amniotic fluid might be beneficial because human urine contains UTI. An experimental study has been performed to investigate whether presence of intraamniotic human urine (consequently UTI) besides meconium is beneficial on intestines of chick embryo with gastroschisis.

METHODS

Five-day-old fertilized chick eggs were used. Gastroschisis was created through amniotic cavity without opening the allantoic cavity. Sterile urine and meconium were obtained from newborn humans. Study was conducted in 2 stages. In the first stage, gastroschisis was created, and meconium suspensions at minimal harmful meconium concentration were prepared using natural and denatured human neonatal urine and instilled into the amniotic cavity. In the second stage of study, various concentrations of UTI plus meconium suspension at minimal harmful meconium concentration was instilled into the amniotic cavity.

RESULTS

Serosal thickening, inflammation, and focal fibrin deposits were observed in intestines of the groups with meconium and meconium in denatured urine. Histopathologic features of intestines of the group with meconium in natural urine did not differ from the intestines of the control group. Histopathologic examination of intestines of groups with meconium and meconium plus 50 U/mL UTI showed serosal thickening, inflammation, focal fibrin, and collagen deposits. Histopathologic features of intestines of the groups with 1:400 intraamniotic meconium plus 100 and 200 U/mL UTI did not differ from the intestines of control group.

CONCLUSION

Urinary trypsin inhibitor 100 U/mL prevented the intestinal damage via inhibiting IL-8, which is contained by 1:400 concentration of meconium. Therefore, besides the existence of threshold level of meconium, the existence of UTI, which is capable of inhibiting IL-8 contained by threshold level of meconium, may be a factor in the occurrence of intestinal damage in gastroschisis.

Neutrophil-mediated inflammation in respiratory syncytial viral bronchiolitis

BACKGROUND

The involvement of neutrophil-mediated inflammation may play an important role in the pathogenesis of acute respiratory syncytial virus bronchiolitis. However, no measurable marker is sensitive enough to assess neutrophil-mediated inflammation in the airways. Released neutrophil elastase (NE) in intraluminal airways has been reported to induce pulmonary inflammation. The aim of this study was to determine whether the amount of urinary trypsin inhibitor (UTI) in serum, a degenerate induced by NE, reflects the degree of airway inflammation in children with respiratory syncytial viral (RSV) bronchiolitis and whether the severity of inflammation is evaluated. The pre-alpha-/inter-alpha-trypsin inhibitor is assumed to be precursors of the UTI. When NE degrades these inhibitors, UTI is liberated.

METHODS

Serum UTI concentrations in infants admitted with RSV bronchiolitis, other viral infections, bacterial pneumonia and control subjects were measured by means of one-step sandwich-type enzyme immunoassay.

RESULTS

Serum UTI concentrations in 25 patients on admission were significantly higher than the 15 infantile control values (mean +/- SEM, 22.126 +/- 2.317 and 6.701 +/- 0.719 U/mL, respectively; P < 0.0001). The elevated levels returned to baseline values with improvement in the respiratory symptoms. Higher levels of serum UTI with RSV infection were consistently associated with clinical symptoms and artificial ventilation. Serum NE concentrations of patients were elevated in some patients but not significantly different from controls in the patients who showed only upper respiratory symptoms with RSV infections.

CONCLUSION

The findings strongly suggested that neutrophil-mediated events are involved in the pathogenesis of RSV bronchiolitis, and the monitoring of UTI concentrations might be useful for evaluating the neutrophil-mediated airway inflammation.

Urinary trypsin inhibitor protects against systemic inflammation induced by lipopolysaccharide

Urinary trypsin inhibitor (UTI), a serine protease inhibitor, has been widely used as a drug for patients with acute inflammatory disorders such as disseminated intravascular coagulation, shock, and pancreatitis in Japan. Recent studies have demonstrated that serine protease inhibitors may play an anti-inflammatory role beyond merely an inhibitory action on neutrophil elastase at the site of inflammation at least in vitro. To clarify the direct contributions of UTI to inflammatory condition in vivo, we analyzed its roles in experimental systemic inflammatory response induced by intraperitoneal administration of lipopolysaccharide (LPS) using UTI deficient (-/-) mice and corresponding wild-type (WT) mice. After LPS (1 mg/kg) challenge, UTI (-/-) mice revealed a significant elevation of plasma fibrinogen and fibrinogen/fibrin degradation products and a decrease in white blood cell counts compared with WT mice. LPS treatment induced more severe neutrophilic inflammation in the lung and the kidney obtained from UTI (-/-) mice than in those from WT mice, which was confirmed by histological examination. The protein levels of proinflammatory mediators, such as macrophage chemoattractant protein (MCP)-1 in the lungs, MCP-1 and keratinocyte chemoattractant (KC) in the kidneys, and interleukin-1beta, macrophage inflammatory protein-2, MCP-1, and KC in the liver, were significantly greater in UTI (-/-) mice than in WT mice after LPS challenge. Our results suggest that UTI protects against systemic inflammatory response and subsequent organ injury induced by bacterial endotoxin, at least partly through the inhibition of the enhanced expression of proinflammatory cytokines and chemokines.

Urinary trypsin inhibitor improves peripheral microcirculation and bronchospasm associated with systemic anaphylaxis in rabbits in vivo

Using intravital microscopy of the rabbit ear for quantitative studies of microvascular dynamics, we examined the impact of urinary trypsin inhibitor (UTI), a proteolytic enzyme inhibitor, on microvascular changes during immune complex-mediated anaphylaxis. A total of 50 rabbits, previously sensitized with horse serum, were anesthetized and mechanically ventilated with pentobarbital and isoflurane for the intravital microscopy. Rabbits were then challenged with intravenous injection of horse serum to induce systemic anaphylaxis. One minute after the challenge, each rabbit was randomly assigned to receive saline (group C), 50,000 units x kg(-1) of UTI (group U1), or 150,000 units x kg(-1) (group U2). There were no statistical differences between hemodynamic variables, including heart rate (HR), mean arterial pressure (MAP), and central venous pressure (CVP), among the survivors in each treatment group. Peak inspiratory pressure rose in all three groups but at a much higher rate in group C (P < 0.05). In contrast with the moderate effects of UTI on the above parameters, microscopic evaluation revealed a substantial difference among treatment groups: upon the initiation of anaphylaxis, the arteriole started to reduce in diameter, but UTI prevented vasoconstriction in the arteriole in a dose-dependent manner. Similar results were observed with blood flow velocity. Because flow rate was calculated as the product of blood flow velocity and vascular cross-sectional area proportional to the square of the vessel diameter, these results indicate that UTI preserves microvascular flow rate during anaphylaxis. Rabbit ear microcirculation is highly preserved in the UTI-treated groups during systemic anaphylactic shock.

Bikunin target genes in ovarian cancer cells identified by microarray analysis

Bikunin, a Kunitz-type protease inhibitor, could potentially suppress tumor cell invasion and metastasis. Our previous study revealed that overexpression of bikunin in a human ovarian cancer cell line, HRA, resulted in a down-regulation in uPA and uPAR gene expression. For identifying the full repertoire of bikunin-regulated genes, a cDNA microarray hybridization screening was conducted using mRNA from bikunin-treated or bikunin-transfected HRA cells. A number of bikunin-regulated genes were identified, and their regulation was confirmed by Northern blot analysis. Our screen identified 11 bikunin-stimulated genes and 29 bikunin-repressed genes. The identified genes can indeed be classified into distinct subsets. These include transcriptional regulators, oncogenes/tumor suppressor genes, signaling molecules, growth/cell cycle, invasion/metastasis, cytokines, apoptosis, ion channels, extracellular matrix proteins, as well as some proteases. This screen identified suppression of several genes such as CDC-like kinase, LIM domain binding, Ets domain transcription factor, Rho GTPase-activating protein, tyrosine phosphorylation-regulated kinase, hyaluronan-binding protein, matriptase, and pregnancy-associated plasma protein-A (PAPP-A), which have previously been implicated in enhancing tumor promotion. Northern blot analysis confirmed that several genes including matriptase and PAPP-A were down-regulated by bikunin by approximately 9-fold. Further, genetic inhibition of matriptase or PAPP-A could lead to diminished invasion. These results show that bikunin alters the pattern of gene expression in HRA cells leading to a block in cell invasion.

Proteases and lung injury

OBJECTIVE

Acute respiratory distress syndrome (ARDS) represents an inflammatory process that is initiated by diverse systemic and/or pulmonary insults, resulting in a clinical syndrome of severe respiratory distress and refractory hypoxemia. Neutrophils and their cytotoxic products, including oxidants and proteases, such as elastase, have been implicated as playing a key role in the pathophysiology of ARDS. This article reviews some of the physiologic actions of proteases, specifically elastase, the evidence for neutrophil elastase involvement in ARDS, and the potential therapeutic use of neutrophil elastase inhibitors in lung injury.

DATA SOURCE

A review of published literature (original articles and reviews) in English from 1965 to 2002.

CONCLUSION

Although the data support a key role for neutrophil elastase in the pathogenesis of ARDS, further study is needed to fully define the actions of neutrophil elastase, and how these actions affect host functions, before we can exploit this knowledge for therapeutic benefit.

Human leukocyte elastase induces keratinocyte proliferation in vitro and in vivo

Neutrophil infiltration and epidermal hyperproliferation are major histopathologic changes observed in psoriasis. Neutrophils contain human leukocyte elastase, which is thought to be released during neutrophil infiltration of the epidermis. As active human leukocyte elastase is known to be present in psoriatic lesions we were interested whether human leukocyte elastase induces hyperproliferation in keratinocytes in vitro and in vivo. In the cultured murine keratinocyte cell line PAM-212 concentrations of human leukocyte elastase from 1 to 30 nM induced significant proliferation as determined by 5-bromo-2'-deoxy-uridine-incorporation. Daily topical application of 0.043-434.8 pmol human leukocyte elastase per cm2 skin on hairless mice induced a concentration-dependent epidermal hyperproliferation and an increase in 5-bromo-2'-deoxy-uridine incorporation of up to 5-fold in basal keratinocytes within 3 d. Hyperproliferation resulted in a up to 2-fold increase of keratinocyte layers. Histologic analysis revealed marked vasodilatation but no inflammatory infiltrate. Application of porcine pancreatic elastase (3-300 pmol per cm2 skin) resulted in similar epidermal changes as observed for human leukocyte elastase. Hyperproliferative effects of human leukocyte elastase in vitro and in vivo were abolished by the addition of elastase inhibitors, such as elafin, anti-leukoprotease, and alpha1-protease inhibitor. In summary, human leukocyte elastase induces proliferation in murine keratinocytes in concentrations, which can be found on the skin surface of psoriatic lesions. These results may provide an explanation for the epidermal hyperproliferation observed in psoriasis.

Calcium-induced changes in chondroitin sulfate chains of urinary trypsin inhibitor

Urinary trypsin inhibitor (UTI) has several roles other than protease inhibition. It is suggested that UTI inhibits calcium influx in cultured cells and that the chondroitin sulfate chain of UTI may play an important role. In order to clarify the mechanistic features of this phenomenon, the chondroitin sulfate chain of UTI was analyzed by (1)H-NMR. The samples were highly purified UTI dissolved in D(2)O in the presence or absence of Ca(2+), Mg(2+) and Na(+). 1D-spectra were obtained and T(1) values of detected signals were estimated from the inversion-recovery method. The addition of Ca(2+) to UTI caused a chemical shift to downfield, line broadening and a reduction of T(1) values at several signals from chondroitin sulfate moiety (especially at axial H-2 of GalNAc), whereas Mg(2+) and Na(+) had no significant effect. Some of the signals in the linkage region of chondroitin sulfate chain showed marked line broadening by Ca(2+). The reduction of T(1) values implies formation of a complex. It is suggested that Ca(2+) generates the sulfate salt and interacts with other polar groups in the chondroitin sulfate chain, thereby causing bridging between UTI molecules. Several properties of UTI may be related to this interaction of Ca(2+) with chondroitin sulfate chains.

Urinary trypsin inhibitor reduces C-X-C chemokine production in rat liver ischemia/reperfusion

BACKGROUND AND AIM

Protease inhibitors attenuate ischemia/reperfusion injury. However, the underlying mechanisms by which protease inhibitors prevent reperfusion injury remain obscure. Neutrophils play an important role in reperfusion injury. We studied the effects of urinary trypsin inhibitor (UTI) on production of the C-X-C chemokine, cytokine-induced neutrophil chemoattractant (CINC), by Kupffer cells during ischemia/reperfusion of the liver.

METHODS

Liver ischemia was induced in rats by occlusion of the portal vein for 30 min. UTI (50,000 U/kg) was injected intravenously 5 min before vascular clamping. Serum CINC concentrations were measured by enzyme-linked immunosorbent assay. Levels of CINC mRNA in the liver were determined by Northern blot analysis. We also examined the inhibitory effects of UTI on in vitro CINC production by peritoneal macrophages in response to neutrophil elastase (NE).

RESULTS

Serum CINC concentrations increased and peaked 6 h after reperfusion. However, pretreatment of animals with UTI blunted this increase in CINC and significantly reduced CINC mRNA levels in the liver after ischemia/reperfusion. UTI also decreased neutrophil accumulation in the liver 24 h after reperfusion. In vitro CINC production by Kupffer cells from rats pretreated with UTI 3 h after ischemia/reperfusion was significantly decreased compared to those from untreated animals. UTI reduced NE activity in vitro in a dose-dependent manner, and UTI significantly reduced in vitro CINC production by peritoneal macrophages stimulated with NE.

CONCLUSION

UTI reduces the production of CINC by Kupffer cells stimulated with NE, attenuating ischemia/reperfusion injury of the liver.

Identification of a potent, selective non-peptide CXCR2 antagonist that inhibits interleukin-8-induced neutrophil migration

Interleukin-8 (IL-8) and closely related Glu-Leu-Arg (ELR) containing CXC chemokines, including growth-related oncogene (GRO)alpha, GRObeta, GROgamma, and epithelial cell-derived neutrophil-activating peptide-78 (ENA-78), are potent neutrophil chemotactic and activating peptides, which are proposed to be major mediators of inflammation. IL-8 activates neutrophils by binding to two distinct seven-transmembrane (7-TMR) G-protein coupled receptors CXCR1 (IL-8RA) and CXCR2 (IL-8RB), while GROalpha, GRObeta, GROgamma, and ENA-78 bind to and activate only CXCR2. A chemical lead, which selectively inhibited CXCR2 was discovered by high throughput screening and chemically optimized. SB 225002 (N-(2-hydroxy-4-nitrophenyl)-N'-(2-bromophenyl)urea) is the first reported potent and selective non-peptide inhibitor of a chemokine receptor. It is an antagonist of 125I-IL-8 binding to CXCR2 with an IC50 = 22 nM. SB 225002 showed >150-fold selectivity over CXCR1 and four other 7-TMRs tested. In vitro, SB 225002 potently inhibited human and rabbit neutrophil chemotaxis induced by both IL-8 and GROalpha. In vivo, SB 225002 selectively blocked IL-8-induced neutrophil margination in rabbits. The present findings suggest that CXCR2 is responsible for neutrophil chemotaxis and margination induced by IL-8. This selective antagonist will be a useful tool compound to define the role of CXCR2 in inflammatory diseases where neutrophils play a major role.