Ileal Crohn's Disease Exhibits Reduced Activity of Phospholipase C-ß3-Dependent Wnt/ß-Catenin Signaling Pathway.

Crohn's disease is a chronic, debilitating, inflammatory bowel disease. Here, we report a critical role of phospholipase C-ß3 (PLC-ß3) in intestinal homeostasis. In PLC-ß3-deficient mice, exposure to oral dextran sodium sulfate induced lethality and severe inflammation in the small intestine. The lethality was due to PLC-ß3 deficiency in multiple non-hematopoietic cell types. PLC-ß3 deficiency resulted in reduced Wnt/ß-catenin signaling, which is essential for homeostasis and the regeneration of the intestinal epithelium. PLC-ß3 regulated the Wnt/ß-catenin pathway in small intestinal epithelial cells (IECs) at transcriptional, epigenetic, and, potentially, protein-protein interaction levels. PLC-ß3-deficient IECs were unable to respond to stimulation by R-spondin 1, an enhancer of Wnt/ß-catenin signaling. Reduced expression of PLC-ß3 and its signature genes was found in biopsies of patients with ileal Crohn's disease. PLC-ß regulation of Wnt signaling was evolutionally conserved in Drosophila. Our data indicate that a reduction in PLC-ß3-mediated Wnt/ß-catenin signaling contributes to the pathogenesis of ileal Crohn's disease.

G Protein-Coupled Receptor 39 Agonist Improves Concanavalin A-Induced Hepatitis in Mice.

The protective effects of G protein-coupled receptor 39 (GPR39) on concanavalin A (Con A)-induced hepatitis in mice was examined. In a dose dependent manner and at 24 h after the elicitation by Con A, oral administration of TC-G 1008, a GPR39 agonist, reduced both, the glutamic-pyruvic transaminase levels (a marker for liver injury) and the necrosis area, as revealed by the histological analysis of tissues from mice with Con A-induced hepatitis. TC-G 1008 also suppressed serum interleukin (IL)-6 and tumor necrosis factor (TNF)-α significantly at 6 h after the elicitation, suggesting that the cells producing IL-6 and/or TNF-α are the targets of TC-G 1008. One potential target cell appears to be a monocyte-derived macrophages because TC-G 1008 treatment suppressed lipopolysaccharide-induced IL-6 production from U937 macrophages in vitro. Taken together, GPR39 agonist TC-G 1008 ameliorates liver injury in the Con A model by blocking pro-inflammatory cytokine production. Use of GPR39 agonists for monotherapy or in combination with immunosuppressants might prove to be beneficial in the treatment of autoimmune hepatitis.

ASB17061, a novel chymase inhibitor, prevented the development of angiotensin II-induced abdominal aortic aneurysm in apolipoprotein E-deficient mice.

Our aim was to examine the effects of ASB17061, an orally active novel chymase inhibitor, on angiotensin II-induced abdominal aortic aneurysm (AAA) in apolipoprotein E-deficient mice. Oral administration of ASB17061 (10 mg/kg) significantly suppressed angiotensin II-induced AAA formation in these mice. The pro-matrix metalloproteinase-9 (pro-MMP-9) level in AAA lesions was significantly suppressed by ASB17061 treatment, indicating that ASB17061 inhibited the accumulation of pro-MMP-9-producing cells in AAA lesions. Mouse mast cell protease 4 (mMCP-4, human chymase ortholog) was injected into BALB/c mice intraperitoneally to examine the ability of mMCP-4 to induce the accumulation of pro-MMP-9-producing cells. An intraperitoneal injection of mMCP-4 induced the accumulation of pro-MMP-9-producing cells including CD11b + Gr-1 + cells. Taken together, these data indicate that ASB17061 is a promising novel oral therapeutic agent for human AAA.

G protein-coupled receptor 39 plays an anti-inflammatory role by enhancing IL-10 production from macrophages under inflammatory conditions.

The possible role of G protein-coupled receptor 39 (GPR39) in inflammation was examined in macrophages. Gpr39 expression increased in thioglycollate-induced peritoneal macrophages. TC-G 1008, a G protein-coupled receptor 39 agonist, enhanced interleukin (IL)-10 production from thioglycollate-induced peritoneal macrophages stimulated with lipopolysaccharide (LPS) in vitro. In addition, the oral administration of TC-G 1008 enhanced serum IL-10 concentrations in an LPS-induced murine model of sepsis. The ablation of G protein-coupled receptor 39 significantly reduced IL-10 production by TC-G 1008 in thioglycollate-induced peritoneal macrophages stimulated with LPS and in the LPS-induced murine model of sepsis. Moreover, the oral administration of TC-G 1008 significantly improved the survival rate in the LPS-induced murine model of sepsis. Taken together, our data suggest that G protein-coupled receptor 39 exhibits an anti-inflammatory activity by enhancing IL-10 production from macrophages.

Critical role for mast cell Stat5 activity in skin inflammation.

Atopic dermatitis (AD) is a chronic inflammatory skin disease. Here, we show that phospholipase C-ß3 (PLC-ß3)-deficient mice spontaneously develop AD-like skin lesions and more severe allergen-induced dermatitis than wild-type mice. Mast cells were required for both AD models and remarkably increased in the skin of Plcb3(-/-) mice because of the increased Stat5 and reduced SHP-1 activities. Mast cell-specific deletion of Stat5 gene ameliorated allergen-induced dermatitis, whereas that of Shp1 gene encoding Stat5-inactivating SHP-1 exacerbated it. PLC-ß3 regulates the expression of periostin in fibroblasts and TSLP in keratinocytes, two proteins critically involved in AD pathogenesis. Furthermore, polymorphisms in PLCB3, SHP1, STAT5A, and STAT5B genes were associated with human AD. Mast cell expression of PLC-ß3 was inversely correlated with that of phospho-STAT5, and increased mast cells with high levels of phospho-STAT5 were found in lesional skin of some AD patients. Therefore, STAT5 regulatory mechanisms in mast cells are important for AD pathogenesis.

Pharmacokinetic/pharmacodynamic analyses of chymase inhibitor SUN13834 in NC/Nga mice and prediction of effective dosage for atopic dermatitis patients.

A chymase inhibitor SUN13834 has been shown to improve skin condition in animal models for atopic dermatitis. In the present study, effective dosages of SUN13834 for atopic dermatitis patients were predicted by pharmacokinetic/pharmacodynamic (PK/PD) analyses of SUN13834 in NC/Nga mice, which spontaneously develop atopic dermatitis-like skin lesions. For the PK/PD analyses, we utilized the minimum effective plasma concentration of unbound SUN13834 in late-phase reaction of trinitrochlorobenzene (TNCB)-induced biphasic dermatitis in mice, based on the assumption that the minimum effective plasma concentrations are the same among the two animal models. In late-phase reaction of biphasic dermatitis, SUN13834 was most effective when its plasma concentration was highest at the elicitation, and the minimum effective plasma concentration of unbound SUN13834 at the elicitation was calculated to be 0.13-0.2 ng/mL. Oral administration of SUN13834 improved dermatitis in NC/Nga mice at 15 mg/kg (twice a day; bid) and 30 mg/kg (once a day; qd), but not at 60 mg/kg (every other day; eod). At the three dosages, the duration times over the plasma level of 0.13-0.2 ng/mL were 16.1-20.3, 10.7-12.2 and 7.8-8.8h, respectively, suggesting an importance of maintenance of the minimum effective plasma concentration for at least about 10-12h. The clinical effective dosage predicted in this paper is also discussed in relation to a recently conducted Phase 2a study.

Protective murine and human monoclonal antibodies against eczema vaccinatum.

BACKGROUND: Eczema vaccinatum is the most common severe pathology associated with smallpox vaccination (vaccinia virus), occurring at high rates among individuals with a previous history of atopic dermatitis (atopic eczema). METHODS: Monoclonal antibodies capable of neutralizing vaccinia virus, anti-H3 and anti-B5, were developed as a potential therapy for treatment of human eczema vaccinatum. RESULTS: Using a small animal model of eczema vaccinatum, we demonstrated that both murine and fully human monoclonal antibodies effectively limited eczema vaccinatum disease, foreshortening both the disease kinetics and the severity of the erosive viral skin lesions. CONCLUSIONS: These neutralizing antibodies would likely be effective at reducing or eliminating clinical disease in people with eczema vaccinatum or other severe side effects of the smallpox vaccine.

A minor catalytic activity of Src family kinases is sufficient for maximal activation of mast cells via the high-affinity IgE receptor.

Src family kinases (SFK) are critical for initiating and regulating the response of mast cells activated by engagement of the high-affinity IgE receptor, FcepsilonRI. Lyn is the predominant SFK in mast cells and has been ascribed both positive and negative roles in regulating mast cell activation. We analyzed the mast cell phenotype of WeeB, a recently described mouse mutant that expresses a Lyn protein with profoundly reduced catalytic activity. Surprisingly, we found that this residual activity is sufficient for wild-type levels of cytokine production and degranulation in bone marrow-derived mast cells after low-intensity stimulation with anti-IgE. High-intensity stimulation of lyn(-/-) bone marrow-derived mast cells with highly multivalent Ag resulted in enhanced cytokine production as previously reported, and WeeB cells displayed an intermediate phenotype. Under this latter condition, SFK inhibition using PP2 increased cytokine production in wild-type and WeeB but not lyn(-/-) cells, resulting in substantially higher levels in the PP2-treated WeeB than in lyn(-/-) cells. Restoration of wild-type and WeeB lyn alleles in lyn(-/-) cells generated activation phenotypes similar to those in nontransduced wild-type and WeeB cells, respectively, whereas a kinase-dead allele resulted in a phenotype similar to that of empty-vector-transduced cells. These data indicate that inhibition of Lyn and/or SFK activity can result in higher levels of mast cell activation than simple deletion of lyn and that only near-complete inhibition of Lyn can impair its positive regulatory functions. Furthermore, the data suggest that both positive and negative regulatory functions of Lyn are predominantly carried out by its catalytic activity and not an adaptor function.

Polyclonal IgE induces mast cell survival and cytokine production.

BACKGROUND: Ag-dependent activation of IgE-bearing mast cells is a critical first step in immediate hypersensitivity and other allergic responses. Recent studies have revealed Ag-independent effects of monoclonal mouse IgE molecules on mast cell survival and activation. However, no studies have been performed on the effects of polyclonal IgE molecules. Here, we tested whether polyclonal mouse and human IgE molecules affect survival and cytokine production in mast cells. METHODS: Mast cells were cultured in the presence of polyclonal mouse and human IgE molecules, and cell survival and cytokine production were analyzed. RESULTS: Polyclonal mouse IgE molecules in sera from mice with atopic dermatitis-like allergic skin inflammation, enhanced survival and cytokine production in mast cell cultures. Similar to the effects of monoclonal IgE, the polyclonal IgE effects were mediated by the high-affinity IgE receptor, FcepsilonRI. Human polyclonal IgE molecules present in sera from atopic dermatitis patients were also capable of activating mast cells, and inducing IL-8 production in human cord blood-derived mast cells. CONCLUSIONS: These results imply that polyclonal IgE in atopic dermatitis and other atopic conditions might modulate mast cell number and function, thus amplifying the allergic response.

Inhibition of NK cell activity by IL-17 allows vaccinia virus to induce severe skin lesions in a mouse model of eczema vaccinatum.

Threats of bioterrorism have renewed efforts to better understand poxvirus pathogenesis and to develop a safer vaccine against smallpox. Individuals with atopic dermatitis are excluded from smallpox vaccination because of their propensity to develop eczema vaccinatum, a disseminated vaccinia virus (VACV) infection. To study the underlying mechanism of the vulnerability of atopic dermatitis patients to VACV infection, we developed a mouse model of eczema vaccinatum. Virus infection of eczematous skin induced severe primary erosive skin lesions, but not in the skin of healthy mice. Eczematous mice exhibited lower natural killer (NK) cell activity but similar cytotoxic T lymphocyte activity and humoral immune responses. The role of NK cells in controlling VACV-induced skin lesions was demonstrated by experiments depleting or transferring NK cells. The proinflammatory cytokine interleukin (IL)-17 reduced NK cell activity in mice with preexisting dermatitis. Given low NK cell activities and increased IL-17 expression in atopic dermatitis patients, these results can explain the increased susceptibility of atopic dermatitis patients to eczema vaccinatum.

Oral chymase inhibitor SUN13834 ameliorates skin inflammation as well as pruritus in mouse model for atopic dermatitis.

Chymase is a chymotrypsin-like serine protease exclusively stored in secretory granules of mast cells and has been thought to participate in allergic diseases. It has already been shown that chymase inhibitor SUN13834 improves dermatitis in NC/Nga mice that spontaneously develop dermatitis resembling atopic dermatitis. In the present study, effect of chymase inhibitor SUN13834 on itch, the major feature of atopic dermatitis, was examined using a mouse dermatitis model induced by repeated topical application of 2,4-dinitrofluorobenzene (DNFB). Oral administration of SUN13834 once a day for 5 weeks inhibited not only skin swelling but accumulation of inflammatory cells including mast cells and eosinophils in the skin of the mice. In addition, SUN13834 also decreased significantly at 10 and 50 mg/kg the amount of scratching behavior induced by the DNFB challenge. This result indicates for the first time that mast cell chymase may be involved in itch induction. In conclusion, SUN13834 is thought to be useful as therapeutic agent for atopic dermatitis.

Identification of 6-substituted 4-arylsulfonyl-1,4-diazepane-2,5-diones as a novel scaffold for human chymase inhibitors.

A novel series of 6-substituted 4-sulfonyl-1,4-diazepane-2,5-diones were designed, synthesized and evaluated as human chymase inhibitors. Structure-activity relationship studies led to the identification of a potent inhibitor, (6S)-6-(5-chloro-2-methoxybenzyl)-4-[(4-chlorophenyl)sulfonyl]-1,4-diazepane-2,5-dione, with an IC(50) of 0.027 microM.

Development of 6-benzyl substituted 4-aminocarbonyl-1,4-diazepane-2,5-diones as orally active human chymase inhibitors.

A novel series of 6-benzyl substituted 4-aminocarbonyl-1,4-diazepane-2,5-diones was designed, synthesized, and evaluated as human chymase inhibitors. From this series, we identified several compounds which were effective, via oral administration, in a mouse model of chronic dermatitis.

Mast cell chymase induces expression of chemokines for neutrophils in eosinophilic EoL-1 cells and mouse peritonitis eosinophils.

Human chymase induced release of interleukin-8 (IL-8) in human EoL-1 cells that had been differentiated into eosinophil-like cells with butyric acid. The chymase-induced IL-8 production was specific in that other cytokines/chemokines examined were not induced. Human chymase also increased mRNA for IL-8 in the differentiated EoL-1 cells, showing involvement of mRNA synthesis. The chymase-induced IL-8 release was inhibited by pertussis toxin as well as U0126 (an inhibitor for extracellular signal-regulated kinase pathway) and SB203580 (p38 inhibitor), suggesting that the chymase-induced IL-8 production is mediated by G protein-coupled receptor and mitogen-activated protein kinases. Mouse mast cell protease-4 (mMCP-4), a mouse chymase, induced macrophage-inflammatory protein-2 (MIP-2), a mouse homologue for IL-8, in mouse eosinophils in vitro. Intradermal injection of mMCP-4 not only induced skin edema but increased MIP-2 content and neutrophil number at the injection site. Taken together, our findings demonstrate that mast cell chymase may contribute to the interaction between eosinophils and neutrophils by inducing IL-8/MIP-2 in eosinophils at allergic inflamed sites.

Eosinophil migration induced by mast cell chymase is mediated by extracellular signal-regulated kinase pathway.

Mast cell chymase is known to induce eosinophil migration in vivo and in vitro. In the present study, we investigated possible involvement of mitogen-activated protein (MAP) kinases; extracellular signal-regulated kinase (ERK), c-Jun amino-terminal kinase (JNK), and p38, in the chymase-induced eosinophil migration. Human chymase induced a rapid phosphorylation of ERK1/2 and p38 in human eosinophilic leukemia EoL-1 cells, while no phosphorylation was detected in JNK. The chymase-induced phosphorylation of ERK and p38 was inhibited by pertussis toxin. Similar results were obtained in the experiments using mouse chymase and eosinophils. U0126 (the inhibitor for MAP/ERK kinase) suppressed chymase-induced migration of EoL-1 cells and mouse eosinophils. However, SB203580 (p38 inhibitor) and SP600125 (JNK inhibitor) showed little effect on the migration. It is suggested therefore that chymase activates ERK and p38 probably through G-protein-coupled receptor, and that ERK but not p38 cascade may have a crucial role in chymase-induced migration of eosinophils.

Repeated topical challenge with chemical antigen elicits sustained dermatitis in NC/Nga mice in specific-pathogen-free condition.

NC/Nga mice are known to develop skin lesions resembling to atopic dermatitis (AD) in conventional but not in specific-pathogen-free (SPF) condition. An epicutaneous application of 2,4-dinitrofluorobenzene (DNFB) increased skin thickness in C3H as well as NC/Nga mice in SPF environment, and the response was enlarged by repeating the challenge at weekly intervals. Although the skin reaction in C3H mice was ameliorated when the challenge was discontinued after the fifth application, the reaction in NC/Nga mice was sustained at least for 3 wk. Analyses of cytokine production by CD4+ cells from the draining lymph node proximal to the lesions revealed that, unlike C3H mice, NC/Nga mice fail to induce T helper 2 (Th2) cytokine interleukin-4 (IL-4), whereas the level of Th1 cytokine interferon-gamma in NC/Nga mice is equivalent to that of C3H mice. In addition, NC/Nga mice highly expressed IL-12, a cytokine-preventing formation of Th2 response, whereas C3H mice did not. Administration of anti-IL-12 antibody reduced duration of dermatitis in DNFB-treated NC/Nga mice. Taken together, our data suggest that IL-12 plays a role in the persistent skin reaction in NC/Nga mice. The action of IL-12 might be mediated by the decrease in IL-4 production.

First total synthesis of structurally unique flavonoids and their strong anti-inflammatory effect.

The first total synthesis of structurally unique flavonoids 1a and 1b is described. These compounds showed very strong anti-inflammatory effect against delayed hypersensitivity in a mouse model.

Involvement of mast cell chymase in bleomycin-induced pulmonary fibrosis in mice.

The possible role of mast cell chymase in organ fibrosis was examined using a bleomycin-induced pulmonary fibrosis model in mice. Intratracheal injection of bleomycin to mice significantly increased not only hydroxyproline content but also chymase activity in the lung. Administration of a chymase inhibitor SUN C8077 (7-chloro-3-(3-amynophenyl) quinazoline-2, 4-dione methanesulfonate) dose-dependently reversed the bleomycin-induced increase in hydroxyproline content as well as chymase activity in the lung. Human chymase digested latent transforming growth factor-beta1 (TGF-beta1) to form mature TGF-beta1 in vitro, which was inhibited by SUN C8077. Human chymase, on the other hand, failed to stimulate DNA synthesis of human lung fibroblasts CCD-8Lu and LL97A. Taken together, it is suggested that mast cell chymase might participate in the pathogenesis of pulmonary fibrosis, and that the chymase-induced fibrosis might be mediated at least in part by TGF-beta1. Chymase inhibitor may be promising for treatment of pulmonary fibrosis in humans.

Human chymase stimulates Ca2+ signaling in human polymorphonuclear cells.

Human chymase is known to function as a chemoattractant for human leukocytes. To investigate the mechanism of the chymase-induced cell migration, change in intracellular calcium concentration ([Ca(2+)]i) was examined in human polymorphonuclear (PMN) cells using Fluo-3 as a fluorescent Ca(2+) indicator. Treatment of PMN cells with human chymase caused [Ca(2+)]i elevation in a concentration-dependent manner. Depletion of extracellular Ca(2+) from the medium partially attenuated the chymase-induced [Ca(2+)]i increase, showing that both Ca(2+) influx and Ca(2+) release from internal stores might be involved in the [Ca(2+)]i response. Pretreatment of the cells with pertussis toxin completely blocked the chymase-induced [Ca(2+)]i signal, suggesting an involvement of G protein in the chymase-mediated [Ca(2+)]i elevation. The data in the present study raise the possibility that the chymase-induced cell migration is mediated by the [Ca(2+)]i elevation, which might be caused by stimulation of a G-protein-coupled receptor such as protease-activated receptors (PARs).