Direct evidence that the brain reward system is involved in the control of scratching behaviors induced by acute and chronic itch.

In the present study, we demonstrated that there is a direct relationship between scratching behaviors induced by itch and functional changes in the brain reward system. Using a conditional place preference test, the rewarding effect was clearly evoked by scratching under both acute and chronic itch stimuli. The induction of ΔFosB, a member of the Fos family of transcription factors, was observed in dopamine transporter (DAT)-positive dopamine neurons in the ventral tegmental area (VTA) of mice suffering from a chronic itch sensation. Based on a cellular analysis of scratching-activated neurons, these neurons highly expressed tyrosine hydroxylase (TH) and DAT genes in the VTA. Furthermore, in an in vivo microdialysis study, the levels of extracellular dopamine in the nucleus accumbens (NAcc) were significantly increased by transient scratching behaviors. To specifically suppress the mesolimbic dopaminergic pathway using pharmacogenetics, we used the TH-cre/hM4Di mice. Pharmacogenetic suppression of mesolimbic dopaminergic neurons significantly decreased scratching behaviors. Under the itch condition with scratching behaviors restricted by an Elizabethan collar, the induction of ΔFosB was found mostly in corticotropin-releasing hormone (CRH)-containing neurons of the hypothalamic paraventricular nucleus (PVN). These findings suggest that repetitive abnormal scratching behaviors under acute and chronic itch stimuli may activate mesolimbic dopamine neurons along with pleasant emotions, while the restriction of such scratching behaviors may initially induce the activation of PVN-CRH neurons associated with stress.

Effects of a pyroglutamyl pentapeptide isolated from fermented barley extract on atopic dermatitis-like skin lesions in hairless mouse.

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by pruritic and eczematous skin lesions. The skin of AD patients is generally in a dried condition. Therefore, it is important for AD patients to manage skin moisturization. In this study, we examined the effects of orally administered fermented barley extract P (FBEP), which is prepared from a supernatant of barley shochu distillery by-product, on stratum corneum (SC) hydration and transepidermal water loss (TEWL) in AD-like lesions induced in hairless mice using 2,4,6-trinitrochlorobenzene. Oral administration of FBEP increased SC hydration and decreased TEWL in the dorsal skin of this mouse model. Further fractionation of FBEP showed that a pyroglutamyl pentapeptide, pEQPFP comprising all -L-form amino acids, is responsible for these activities. These results suggested that this pyroglutamyl pentapeptide may serve as a modality for the treatment of AD.

Exopolysaccharide Produced by Lactobacillus paracasei IJH-SONE68 Prevents and Improves the Picryl Chloride-Induced Contact Dermatitis.

Allergic disease is one of the most important and common health problems worldwide. We have previously demonstrated that a fig leaf-derived lactic acid bacterium Lactobacillus (Lb.) paracasei IJH-SONE68 produces a novel exopolysaccharide (EPS). Furthermore, we have shown that the EPS inhibits the catalytic activity of hyaluronidase (EC 3.2.1.36) promoting inflammatory reactions. To evaluate the anti-allergy and anti-inflammatory effects of the EPS, in the present study, we employed the picryl-chloride-induced delayed-type (type IV) allergy model mice, which is used to evaluate the contact dermatitis. Oral administration of the EPS was observed to reduce the ear swelling in the model mice. We also observed that the overexpression of ear interleukin-4 (T helper (Th) 2 cytokine) mRNA and the increase in serum immunoglobulin E (IgE) are repressed. However, the expression of interferon-γ (Th1 cytokine) was not accelerated in all of the allergen-challenged model mice. The improvement may be responsible for the Th2 downregulation rather than the Th1 upregulation. In addition, the symptom of immediate-type (type I) allergy model mice was improved by oral administration of the IJH-SONE68 cell (data not shown). We can conclude that the IJH-SONE68-derived EPS is useful to improve the type I and IV allergies including atopic dermatitis.

Cytip regulates dendritic-cell function in contact hypersensitivity.

Cytohesin-interacting protein (Cytip) is induced during dendritic cell (DC) maturation and in T cells upon activation. It has also been shown to be involved in the regulation of immune responses. Here, we evaluated the functional consequences of Cytip deficiency in DCs using Cytip knockout (KO) mice. No difference in DC subpopulations in the skin draining lymph nodes (LNs) was found between Cytip KO mice and their wild-type counterparts, excluding a role in DC development. To investigate the function of Cytip in DCs in vivo, we used 2,4,6-trinitrochlorobenzene (TNCB)-induced contact hypersensitivity (CHS) as a model system. In the sensitization as well as in the elicitation phase, DCs derived from Cytip KO mice induced an increased inflammatory reaction indicated by more pronounced ear swelling. Furthermore, IL-12 production was increased in Cytip KO bone marrow-derived DCs (BMDCs) after CpG stimulation. Additionally, Cytip-deficient DCs loaded with ovalbumin induced stronger proliferation of antigen-specific CD4(+) and CD8(+) T cells in vitro. Finally, migration of skin DCs was not altered after TNCB application due to Cytip deficiency. Taken together, these data suggest a suppressive function for Cytip in mouse DCs in limiting immune responses.

Induction of thymic stromal lymphopoietin production by nonanoic acid and exacerbation of allergic inflammation in mice.

BACKGROUND: Thymic stromal lymphopoietin (TSLP) plays critical roles in the induction and exacerbation of allergic diseases. We tested various chemicals in the environment and found that xylene and 1,2,4-trimethylbenzene induced the production of TSLP in vivo. These findings prompted us to search for additional chemicals that induce TSLP production. In this study, we examined whether fatty acids could induce the production of TSLP in vivo and exacerbate allergic inflammation. METHODS: Various fatty acids and related compounds were painted on the ear lobes of mice and the amount of TSLP in the homogenate of ear lobe tissue was determined. The effects of nonanoic acid on allergic inflammation were also examined. RESULTS: Octanoic acid, nonanoic acid, and decanoic acid markedly induced TSLP production, while a medium-chain aldehyde and alcohol showed only weak activity. Nonanoic acid induced the production of TSLP with a maximum at 24 h. TSLP production was even observed in nonanoic acid-treated C3H/HeJ mice that lacked functional toll-like receptor 4. The aryl hydrocarbon receptor agonist ß-naphthoflavone did not induce TSLP production. Nonanoic acid promoted sensitization to ovalbumin, resulting in an enhancement in the cutaneous anaphylactic response. In addition, painting of nonanoic acid after the sensitization augmented picryl chloride-induced thickening of the ear, which was reversed in TSLP receptor-deficient mice. CONCLUSIONS: Nonanoic acid and certain fatty acids induced TSLP production, resulting in the exacerbation of allergic inflammation. We propose that TSLP-inducing chemical compounds such as nonanoic acid be recognized as chemical allergo-accelerators.

IL-20 receptor 2 signaling down-regulates antigen-specific T cell responses.

The recently described cytokines IL-19, IL-20, and IL-24 share structural homology with IL-10 and are therefore classified as members of the IL-10 family of cytokines. Although it has long been speculated that signaling by their heterodimeric receptor complexes (IL-20R1/IL-20R2 and IL-22R/IL-20R2) influences immunological processes, the target cells for this group of cytokines are still unclear. By generating a knockout mouse strain deficient for the common IL-20R beta-chain (IL-20R2), we show that IFN-gamma and IL-2 secretion is significantly elevated after stimulation of IL-20R2-/--deficient CD8 and CD4 T cells with Con A or anti-CD3/CD28 in vitro. IL-10 secretion by activated IL-20R2-/- CD4 cells was diminished. Consistent with our in vitro results, significantly more Ag-specific CD8 IFN-gamma+ and CD4 IFN-gamma+ T cells developed to locally applied DNA vaccines in IL-20R2-deficient mice. In a T cell-dependent model of contact hypersensitivity, IL-20R2 knockout mice were more sensitive to the contact allergen trinitro-chloro-benzene. Thus, IL-20R2 signaling directly regulates CD8 and CD4 T cell answers in vitro and in vivo. For the first time, we provide evidence that IL-19, IL-20, and IL-24 are part of a signaling network that normally down-modulates T cell responses in mice.

Regulatory T Cells Prevent Neutrophilic Infiltration of Skin during Contact Hypersensitivity Reactions by Strengthening the Endothelial Barrier.

The healing phase of contact hypersensitivity reactions is critically dependent on regulatory T cells (Tregs), but even the early inflammatory phase, that is, 6-24 hours after induction of a contact hypersensitivity reaction, is susceptible to Treg-mediated suppression. To investigate the underlying mechanisms, we injected Tregs before the challenge and analyzed the skin-infiltrating cells as early as 6 hours later. Early on, we found mainly neutrophils in the challenged skin, but only a few T cells. This influx of neutrophils was blocked by the injection of Tregs, indicating that they were able to prevent the first wave of leukocytes, which are responsible for starting an immune reaction. As an underlying mechanism, we identified that Tregs can tighten endothelial junctions by inducing intracellular cAMP, leading to protein kinase A-RhoA‒dependent signaling. This eventually reorganizes endothelial junction proteins, such as Notch3, Nectin 2, Filamin B, and VE-cadherin, all of which contribute to the tightening of the endothelial barrier. In summary, Tregs prevent the leakage of proinflammatory cells from and into the tissue, which establishes a mechanism to downregulate immune reactions.

Effects of single and combined administration of fermented barley extract and gamma-aminobutyric acid on the development of atopic dermatitis in NC/Nga mice.

We examined the effects single and combined administration of fermented barley extract P (FBEP), prepared from barley-shochu distillery by-products, and gamma-aminobutyric acid (GABA) on the development of atopic dermatitis (AD)-like skin lesions in NC/Nga mice. Single administration of FBEP and GABA dose-dependently reduced the development of AD-like skin lesions in mice. GABA reduced the development of AD-like skin lesions by suppressing serum immunoglobulin E (IgE) and splenocyte interleukin (IL)-4 production, while FBEP reduced skin lesions without affecting the IgE or cytokine production. However, in mice with induced AD-like skin lesions, combined administration of FBEP and GABA decreased serum IgE levels and splenic cell IL-4 production, and increased splenic cell interferon-gamma production. These results suggest that combined administration of FBEP and GABA alleviated AD-like skin lesions in the NC/Nga mice by adjusting the Th1/Th2 balance to a Th1-predominant immune response.

Synergetic effects of prednisolone and olopatadine on atopic dermatitis model of hairless mice.

We investigated the synergetic effects of glucocorticoid and histamine H1 receptor antagonists on an atopic dermatitis model. Hairless mice were used in this study and an atopic dermatitis model was made by repeated application of 2,4,6-trinitrochlorobenzene. The effects of glucocorticoid, histamine H1 receptor antagonists, and the simultaneous use of these drugs were investigated by measuring scratching behavior, skin symptoms and nerve growth factor (NGF) in the skin. Topical application of prednisolone significantly inhibited scratching behavior, skin symptoms and NGF contents in the skin by repeated application. Olopatadine also showed a significant effect on scratching behavior and NGF contents in the skin, whereas chlorpheniramine showed no significant inhibitory effect on these indices. Furthermore, the combined use of prednisolone and olopatadine potentiated the inhibition of scratching behavior, skin symptoms, and NGF in the skin. From these findings, olopatadine potentiated the inhibitory effect of prednisolone on the symptoms of atopic dermatitis by inhibiting NGF.

Roxithromycin inhibits the effector phase of delayed-type hypersensitivity.

In the present paper, the effect of roxithromycin on delayed-type hypersensitivity (DTH) was evaluated. Roxithromycin had no effect on sheep red blood cells (SRBC)-induced food pad swelling when orally administered in induction phase, whereas it suppressed the SRBC-induced DTH reaction and 2,4,6-Trinitrochlorobenzene (TNCB)-induced contact hypersensitivity (CHS) significantly when administered to mice in effector phase. For the sustained-CHS model induced by multi-challenge with TNCB, roxithromycin also inhibited the ear swelling when exposed to mice in three effector phases while showed no inhibitory effect on CHS by continuous treatment. Administration of this antibiotic in effector phase also down-regulated the MMP-9 activity and the higher in vitro survival of splenocytes from SRBC-challenged mice. Furthermore, this drug inhibited the gene expression of T-helper type 1 (Th1) cytokines such as IL-2 and IFN-gamma of lymph node cells from mice immuned by TNCB or of Con A-stimulated spleen cells. In addition, roxithromycin administered in vivo decreased the concanavalin A (Con A)-induced splenocyte proliferation without affecting the cell survival in vitro. These results suggest that roxithromycin might alleviate DTH reaction at least by suppressing the function and survival of effector T cells.

Critical role of IL-10 in the induction of low zone tolerance to contact allergens.

The development and mechanisms of tolerance to allergens are poorly understood. Using the murine low zone tolerance (LZT) model, where contact hypersensitivity (CHS) is prevented by repeated topical low-dose applications of contact allergens, we show that LZT induction is IL-10 dependent. IL-10 is required for the generation of LZT effector cells, that is, CD8+ regulatory T cells. Only T cells from tolerized IL-10+/+ mice or IL-10-/- mice reconstituted with IL-10 during LZT induction adoptively transferred LZT to naive mice and prevented CHS, whereas T cells from IL-10-/- mice failed to do so. The IL-10 required for normal LZT development is derived from lymph node CD4+ T cells, the only skin or lymph node cell population found to produce relevant amounts of IL-10 after tolerization. CD4+ T cells derived from IL-10+/+ mice, but not from IL-10-/- mice, allowed the induction of LZT in adoptively transferred T cell-deficient mice. Interestingly, IL-10 injections during tolerization greatly enhanced LZT responses in normal mice. Thus, the generation of CD8+ LZT effector T cells by CD4+ regulatory T cells via IL-10 may be a promising target of strategies aimed at preventing contact allergies and other harmful immune responses.

Nonatopic asthma: in vivo airway hyperreactivity adoptively transferred to naive mice by THY-1(+) and B220(+) antigen-specific cells that lack surface expression of CD3.

To investigate the cellular immune events contributing to airway hyperreactivity (AHR), we studied an in vivo mouse model induced by the hapten picryl (trinitrophenyl) chloride (PCl). Mice were immunized by cutaneous contact sensitization with PCl and airway challenged subsequently with picryl sulfonic acid (PSA) antigen (Ag). Increased airway resistance was produced late (24 h) after Ag challenge, disappeared by 48 h, and was associated with no decrease in diffusion capacity. AHR could be produced in PCl immune/ PSA challenged mice on day 7 or even, with challenge, as early as 1 d after contact sensitization, after adoptive transfer of immune cells lacking CD3(+) contact sensitivity effector T cells, or after transfer of Ag-specific lymphoid cells depleted of conventional T lymphocytes with surface determinants for CD3, CD4, CD8, TCR-beta, or TCR-delta molecules. Further experiments showed that development of AHR depended upon transfer of immune cells expressing surface membrane Thy-1 and B220 (CD45RA) determinants. We concluded that a novel population of Ag-specific lymphoid cells with a defined surface phenotype (Thy-1(+), CD3(-), CD4(-), CD8(-), TCR-alphabeta-, TCR-gammadelta-, and CD45RA+) is required in a mouse model for the development of AHR.

Expression of CD73 slows down migration of skin dendritic cells, affecting the sensitization phase of contact hypersensitivity reactions in mice.

BACKGROUND: Application of haptens to the skin induces release of immune stimulatory ATP into the extracellular space. This "danger" signal can be converted to immunosuppressive adenosine (ADO) by the action of the ectonucleotidases CD39 and CD73, expressed by skin and immune cells. Thus, the expression and regulation of CD73 by skin derived cells may have crucial influence on the outcome of contact hypersensitivity (CHS) reactions. OBJECTIVE: To investigate the role of CD73 expression during 2,4,6-trinitrochlorobenzene (TNCB) induced CHS reactions. METHODS: Wild type (wt) and CD73 deficient mice were subjected to TNCB induced CHS. In the different mouse strains the resulting ear swelling reaction was recorded along with a detailed phenotypic analysis of the skin migrating subsets of dendritic cells (DC). RESULTS: In CD73 deficient animals the motility of DC was higher as compared to wt animals and in particular after sensitization we found increased migration of Langerin+ DC from skin to draining lymph nodes (LN). In the TNCB model this led to a stronger sensitization as indicated by increased frequency of interferon-γ producing T cells in the LN and an increased ear thickness after challenge. CONCLUSION: CD73 derived ADO production slows down migration of Langerin+ DC from skin to LN. This may be a crucial mechanism to avoid over boarding immune reactions against haptens.

Effect of orally administered rolipram, a phosphodiesterase 4 inhibitor, on a mouse model of the dermatitis caused by 2,4,6-trinitro-1-chlorobenzene (TNCB)-repeated application.

The purpose of this study was to evaluate the efficacy of rolipram, a phosphodiesterase (PDE) 4 inhibitor, in a mouse model of dermatitis induced by repeated application of 2,4,6-trinitro-1-chlorobenzene (TNCB). BALB/c mice were sensitized with 0.3% w/v TNCB applied to the ear on day -7, followed by application three times a week from day 0. Rolipram, prednisolone and cyclosporine A were administered orally once daily from day 0 to 21. Rolipram at a dose of 10 mg/kg/day significantly inhibited the ear thickness and the increase in cytokine levels and enzyme activity in the ear. Interleukin (IL)-4 production was markedly decreased in cervical lymph node cells from animals treated with rolipram at a dose of 10 mg/kg/day. Prednisolone and cyclosporine A significantly reduced ear thickness. These compounds significantly decreased the total cell and lymphocyte number of the cervical lymph nodes. Furthermore, prednisolone markedly suppressed body weight gain, and cyclosporine A significantly increased the serum total IgE concentration compared with that in the vehicle-treated control. Rolipram, unlike prednisolone and cyclosporine A, did not influence body weight and the total IgE concentration in the serum. The present results suggest that the PDE4 inhibitor is a promising oral medicine for the treatment of chronic skin inflammatory diseases.

A new chronic itch model accompanied by skin lesions in hairless mice.

The present study was performed to develop a new chronic itch model accompanied by skin lesions using hairless mice. The effects of some drugs on the itch response in this model were also studied. 2,4,6-Trinitrochlorobenzene (TNCB) was applied repeatedly on the rostral back of sensitized hairless mice every 2 days for 54 days, and the scratching behavior was observed on day 0, 18, 36 and 54. The skin symptoms and total IgE level were also observed. The number of scratches observed at 24 and 48 h after TNCB challenge was increased gradually from day 18 to day 54. An intimate relationship was observed between the number of scratches and the skin score at 48 h after TNCB on day 54. The skin symptoms and total IgE levels were also elevated gradually from day 18 to day 54. Chlorpheniramine, cyproheptadine and methysergide caused no effect on the scratching behavior accompanied by skin lesions at 48 h after TNCB challenge, even at a high dose. On the other hand, L-733,060, naloxone, naltrexone, prednisolone and dexamethasone caused a significant inhibition of the scratching behavior induced by TNCB. Therefore, this model may be useful to evaluate the effects of drugs on the itch response accompanied by skin lesions, such as atopic dermatitis.

Inhibitory effect of antidepressant drugs on contact hypersensitivity reaction is connected with their suppressive effect on NKT and CD8(+) T cells but not on TCR delta T cells.

BACKGROUND: Contact hypersensitivity (CHS) reaction induced by a topical application of hapten is a cell-mediated antigen-specific type of skin inflammation mediated by interaction of several subtypes of T cell subpopulations. Recently, it has been shown that antidepressant drugs inhibit CHS reaction, although the mechanism of this effect remains unknown. The aim of the present study was to investigate the effect of 2-week desipramine or fluoxetine administration on the CHS reaction induced by picryl chloride (PCL) application in B10.PL mice and in knock-out mice established on B10.PL background: TCRδ(-/-) mice lacking TCRγδ T lymphocytes; ß2m(-/-) mice lacking CD8(+) T lymphocytes and CD1d(-/-) mice lacking CD1d dependent natural killer T (NKT) lymphocytes. METHODS: B10.PL, TCRδ(-/-), ß2m(-/-) and CD1d(-/-) mice were divided into six groups: 1) vehicle-treated negative control group; 2) desipramine-treated negative control group; 3) fluoxetine-treated negative control group; 4) vehicle and PCL-treated group (positive control group); 5) desipramine and PCL-treated group; and 6) fluoxetine and PCL-treated group. CHS to PCL was tested by evaluation of ear swelling. Metabolic activity of spleen and lymph node cells were estimated by MTT test. RESULTS: The antidepressants significantly suppressed the CHS reaction in B10.PL mice: desipramine by 55% and fluoxetine by 42% compared to the positive control. This effect was even stronger in TCRδ(-/-) mice, in which fluoxetine reduced the ear swelling by 73% in comparison with the vehicle-treated positive control group. On the other hand, desipramine and fluoxetine did not inhibit CHS reaction in ß2m(-/-) and CD1d(-/-) mice. Moreover, PCL increased metabolic and/or proliferative activity of splenocytes in all four strains of mice whereas the antidepressants decreased this activity of splenocytes in B10.PL, TCRδ(-/-) and CD1d(-/-) mice. CONCLUSION: The results of the present study show that lack of CD8(+) T cells or NKT cells abolishes the immunosuppressive effect of antidepressant drugs on PCL-induced CHS reaction in mice. These results suggest that antidepressant drug-induced inhibition of CHS reaction is connected with their inhibitory effect on ability of CD8(+) T cells and NKT cells to induce and/or escalate CHS reaction. TCRγδ cells seem not to be involved in antidepressant-induced suppression of CHS.

Analysis of dose response of trinitrochlorobenzene contact hypersensitivity induction in mice: pretreatment with cyclophosphamide reveals an optimal sensitizing dose.

A detailed dose-response curve has been established for induction of contact hypersensitivity (CH) in mice with trinitrochlorobenzene (TNCB). It was determined that in BALB/c, CBA/J, and C57BL/6 mice, the dose required to sensitize via epicutaneous application was between 1 and 10 micrograms TNCB. When doses of hapten of 200 micrograms or greater were painted on abdominal skin, CH responses were induced which were only marginally greater than responses induced by sensitizing doses of hapten in the 10-50-micrograms range, implying that no further dose-response relationship exists beyond 50 micrograms of hapten. However, in companion experiments, in which panels of mice were pretreated with cyclophosphamide, it was determined that sensitizing doses of hapten in excess of 50 micrograms induced both CH and concomitant induction of down-regulation of CH. Thus, at 200 micrograms or higher doses of TNCB, CH responses of cyclophosphamide pretreated mice were invariably more intense than in their untreated, hapten-painted cohorts. In the animals pretreated with cyclophosphamide, it was possible to see that a dose-response relationship continued to exist between the amount of epicutaneously applied hapten over a 200 micrograms to 14 mg range and the intensity of the CH induced. We conclude that the optimal dose for immunizing mice epicutaneously with TNCB is between 10 and 50 micrograms. This is considered optimal since animals sensitized in this manner display no evidence of concomitant down-regulation of their CH responses.

Platelets play a role in the pathogenesis of the irritant reaction in mice.

The irritant reaction is a model of local inflammation that results from the epicutaneous application of a small molecule with irritating properties such as trinitrochlorobenzene (TNCB). The irritant reaction is mediated by tumor necrosis factor (TNF) and is characterized by skin edema and neutrophil (PMN) infiltration. The aim of this study was to explore the role of platelets in the pathogenesis of the irritant reaction. Mice depleted of platelets by an anti-platelet antibody showed a decrease in edema upon the application of a low dose of TNCB--chosen for causing an irritant reaction that is not complicated by intravascular fibrin deposition and hemorrhage--but no significant change in PMN infiltration. There was platelet trapping in TNCB-treated ears that was maximum between 2 and 6 h after TNCB application. Platelets lined the venular endothelium, which was intact in the absence of hemorrhage, and were not accompanied by fibrin. Mice treated with anti-TNF, anti-CD11a, anti-CD18, or anti-CD54 antibodies showed a decrease in platelet trapping, edema, and PMN infiltration. Platelets contribute to the pathogenesis of the irritant reaction and are necessary for edema to develop but not for PMN infiltration. The role of platelets implicates their early localization in the dermal venules, which depends, at least in part, on TNF and on the adhesion molecules involved in the interaction between CD11a/CD18 and CD54.

Therapeutic potential of a novel synthetic selectin blocker, OJ-R9188, in allergic dermatitis.

1. We investigated the ability of a newly synthesized sugar derivative, OJ-R9188, [N-(2-tetradecylhexadecanoyl)-O-(L-alpha-fucofuranosyl)-D-seryl]-L-glutamic acid 1-methylamide 5-L-arginine salt, to block binding of selectins to their ligands in vitro and inhibit the infiltration of leukocytes in vivo. 2. OJ-R9188 prevented the binding of human E-, P- and L-selectin-IgG fusion proteins to immobilized sialyl Lewis(x) (sLe(x))-pentasaccharide glycolipid, with IC(50) values of 4.3, 1.3, and 1.2 microM, respectively. 3. In a mouse model of thioglycollate-induced peritonitis, OJ-R9188 at 10 mg kg(-1), i.v. inhibited neutrophil accumulation in the peritoneal cavity. In the IgE-mediated skin reaction, OJ-R9188 at 3 and 10 mg kg(-1), i.v. significantly inhibited extravasation of neutrophils and eosinophils into the inflammatory sites and at 10 mg kg(-1), i.v. also inhibited infiltration caused by picryl chloride-induced delayed-type hypersensitivity in mice. These results suggest that OJ-R9188 may be a useful selectin blocker, with activity against human and mouse E-, P- and L-selectins in vitro and in vivo, and that blocking selectin-sLe(x) binding is a promising strategy for the treatment of allergic skin diseases.