The orally-active and selective c-Fms tyrosine kinase inhibitor Ki20227 inhibits disease progression in a collagen-induced arthritis mouse model

Macrophage colony-stimulating factor (M-CSF) is important in the development of macrophages and osteoclasts. Previous studies have also shown that CD11b(+) myeloblasts and osteoclasts play key roles during inflammation and bone destruction in arthritic lesions. In this study, we investigated whether N-{4-[(6,7-dimethoxy-4-quinolyl)oxy]-2-methoxyphenyl}-N'-[1-(1,3-thiazole-2-yl)ethyl] urea (Ki20227), an inhibitor of the M-CSF receptor (c-Fms), suppressed disease progression in a type II collagen (CII)-induced arthritis (CIA) mouse model. We found that Ki20227 inhibited M-CSF-dependent reactions, such as lipopolysaccharide-induced tumor necrosis factor-alpha production, which were enhanced by M-CSF in vitro. Oral administration of Ki20227 in vivo prevented inflammatory cell infiltration and bone destruction, and consequently suppressed disease progression. In addition, the number of CD11b(+), Gr-1(+), and Ly-6G(+) cells in the spleen decreased in the Ki20227-treated mice, and the CII-induced cytokine production in splenocytes isolated from the Ki20227-treated arthritic mice was also reduced. These observations indicate that Ki20227 might exert its therapeutic effects in the CIA mouse model by suppressing the M-CSF-dependent accumulation of both inflammatory and osteoclast cells, as well as by inhibiting inflammatory cytokine production. Hence, inhibitors of the c-Fms tyrosine kinase might act as anti-inflammatory or anti-osteolytic agents against arthritis.

Treatment with anti-gamma-glutamyl transpeptidase antibody attenuates osteolysis in collagen-induced arthritis mice

The effectiveness of a new antibody treatment on arthritis-associated osteolysis was studied by using CIA mice. GGT, a newly identified bone-resorbing factor, was upregulated in arthritic joints. We generated monoclonal antibodies against GGT and injected them into CIA mice. Mice treated with antibodies showed a reduction in osteoclast number and bone erosion.

INTRODUCTION

Gamma-glutamyl transpeptidase (GGT) acts as a bone-resorbing factor that stimulates osteoclast formation. GGT expression has been detected in active lymphocytes that accumulate at inflammation sites, such as rheumatoid arthritis (RA). We hypothesize that GGT is an effective target for suppression of arthritis-related osteoclastogenesis and joint destruction. Here, we describe the therapeutic effect of neutralizing antibodies against GGT on joint destruction using a collagen-induced arthritis (CIA) mouse model.

MATERIALS AND METHODS

GGT expression in the synovium of RA patients and CIA mice was determined by immunohistochemistry and RT-PCR. Monoclonal antibodies were generated against recombinant human GGT (GGT-mAbs) using BALB/c mice. Antibody treatment was performed by intraperitoneal injections of GGT-mAbs into CIA mice. Effects of antibody treatment on arthritis and bone erosion were evaluated by incidence score, arthritis score, and histopathological observations. The role of GGT in osteoclast development was examined by using the established osteoclastogenic culture system.

RESULTS

GGT expression was significantly upregulated in inflamed synovium. Immunohistochemistry revealed that GGT was present in lymphocytes, plasma cells, and macrophages, as well as capillaries. Injection of GGT-mAbs significantly decreased the number of osteoclasts and attenuated the severity of joint destruction in CIA mice. In vitro examination showed that GGT enhanced RANKL-dependent osteoclast formation. GGT stimulated the expression of RANKL in osteoblasts and its receptor RANK in osteoclast precursors, respectively.

CONCLUSIONS

This study indicates that inflamed synovial tissue-derived GGT acts as a risk factor for joint destruction and that the antibody-mediated inhibition of GGT significantly decreases osteoclast number and bone erosion in CIA mice. GGT antagonists might be novel therapeutic agents for attenuating joint destruction in RA patients.

CD52 is a novel costimulatory molecule for induction of CD4+ regulatory T cells

We previously reported that 4C8 monoclonal antibody (mAb) provides a costimulatory signal to human CD4+ T cells and consequently induces regulatory T (Treg) cells, which are hypo-responsive and suppress the polyclonal response of bystander CD4+ cells in a contact-dependent manner. In this study, we identified the antigen of 4C8 mAb as CD52. Costimulation with Campath-1H, a humanized anti-CD52 mAb, also induced Treg cells. Anti-CD52-induced Treg cells suppressed the proliferation of both CD4+ and CD8+ T cells provided with polyclonal or allogeneic stimulation. When Treg cells were induced from Staphylococcal enterotoxin B (SEB) treated cells, they suppressed the response to SEB more efficiently than that to another superantigen, SEA. Furthermore, anti-CD52-induced Treg cells could be expanded by culture with IL-2 followed by CD52-costimulation, and co-injection of expanded Treg cells suppressed lethal xenogeneic graft versus host disease (GvHD) reactions in SCID mice caused by human peripheral blood mononuclear cells (PBMCs).

Differential effects of beta2-adrenoceptor desensitization on the IgE-dependent release of chemical mediators from cultured human mast cells

In the present study, we examined the inhibitory effects of the beta2-adrenoceptor agonists isoproterenol, salbutamol, fenoterol, and clenbuterol, on the release of chemical mediators from cultured human mast cells after prolonged treatment with the agonists. Although preincubation of sensitized mast cells for 10 min with beta2-adrenoceptor agonists potently inhibited mediator release, prolongation of the preincubation period up to 240 min attenuated the inhibition. The attenuation of histamine release inhibition was potent when compared with that of prostaglandin D2 (PGD2) and cysteinyl leukotriene (LT) release inhibition. In contrast, forskolin inhibited mediator release and the inhibition increased gradually in proportion to the preincubation period. The reduced inhibition by the beta2-adrenoceptor agonists was compensated for by simultaneous treatment with cholera toxin. The beta2-adrenoceptor agonists elevated intracellular cAMP levels after 10-min incubation and the elevated levels were almost comparable to those after 240-min incubation. Forskolin elevated the intracellular cAMP levels more potently after incubation for 240 min than after 10 min. When mast cells were incubated for 3 d with the beta2-adrenoceptor agonists, similar attenuation of mediator release inhibition was observed. Elevation of intracellular cAMP levels was also attenuated, although beta2-adrenoceptor mRNA expression was potentiated. The present results collectively indicate that the attenuation of mediator release inhibition by beta2-adrenoceptor agonists under the present experimental conditions involves uncoupling between beta2-adrenoceptors and Gs proteins. Furthermore, the beta2-adrenoceptor desensitization causes differential attenuating effects on the inhibition of histamine, PGD2, and LT release, suggesting that downstream events involved in each inhibitory pathway have different sensitivity to receptor desensitization.

Quantitative and Qualitative Differences in the In Vivo Response of NKT Cells to Distinct α- and β-Anomeric Glycolipids

NKT cells represent a unique subset of immunoregulatory T cells that recognize glycolipid Ags presented by the MHC class I-like molecule CD1d. Because of their immunoregulatory properties, NKT cells are attractive targets for the development of immunotherapies. The prototypical NKT cell ligand alpha-galactosylceramide (alpha-GalCer), originally isolated from a marine sponge, has potent immunomodulatory activities in mice, demonstrating therapeutic efficacy against metastatic tumors, infections, and autoimmune diseases, but also has a number of adverse side effects. In vivo administration of alpha-GalCer to mice results in the rapid activation of NKT cells, which is characterized by cytokine secretion, surface receptor down-regulation, expansion, and secondary activation of a variety of innate and adaptive immune system cells. In this study, we have evaluated the in vivo immune response of mice to a set of structural analogues of alpha-GalCer. Our results show that, contrary to current thinking, beta-anomeric GalCer can induce CD1d-dependent biological activities in mice, albeit at lower potency than alpha-anomeric GalCer. In addition, we show that the response of NKT cells to distinct GalCer differs not only quantitatively, but also qualitatively. These findings indicate that NKT cells can fine-tune their immune responses to distinct glycolipid Ags in vivo, a property that may be exploited for the development of effective and safe NKT cell-based immunotherapies.

A monoclonal antibody to the alpha2 domain of murine major histocompatibility complex class I that specifically kills activated lymphocytes and blocks liver damage in the concanavalin A hepatitis model

We earlier found that a rat monoclonal antibody (mAb) RE2 can induce rapid death of murine activated, but not resting, lymphocytes and lymphocyte cell lines, in a complement-independent manner, a cell death differing from typical apoptosis or necrosis. We here found that this cell death is independent of pathways involving Fas, caspase, and phosphoinositide-3 kinase. With the advantage of producing human B cell line transfectants with stable expression of human/mouse xeno-chimeric MHC class I genes, we found that RE2 epitope resides on the murine class I alpha2 domain. However, the alpha3 domain plays a key role in transducing the death signal, which mediates extensive aggregation of the MHC class I-integrin-actin filament system, giving rise to membrane blebs and pores. In mouse models with T/NKT cell activation-associated fulminant hepatitis, administration of mAb RE2 almost completely inhibited the development of liver cell injuries. Taken collectively, this form of cell death may be involved in homeostatic immune regulation, and induction of this form of cell death using the mAbs may be potentially therapeutic for subjects with immunological diseases mediated by activated lymphocytes.

Germinated barley foodstuff, a prebiotic product, ameliorates inflammation of colitis through modulation of the enteric environment

BACKGROUND

Germinated barley foodstuff (GBF), which contains glutamine-rich protein and hemicellulose-rich fiber, exhibits therapeutic effects in ulcerative colitis; however, its mechanism is still under investigation. The aim of this study was to evaluate the anti-inflammatory effects of GBF on colitis in terms of the epithelial inflammatory response.

METHODS

Mice with dextran sulfate sodium-induced colitis were used. The effects of GBF on the colitis were evaluated by measuring the body weight; disease activity; mucosal damage (histology, mucosal inflammatory parameters, nuclear factor kappa B [NFkB] activation, and signal transducer and activator of transcription 3 [STAT3]); serum interleukin 6 (IL-6) level; cecal short-chain fatty acids (SCFAs); and bile acid contents.

RESULTS

GBF significantly prevented disease activity and body weight loss after induction of colitis. Serum IL-6 level and mucosal STAT3 expression were also significantly attenuated, with a conspicuous reduction of mucosal damage; NFkB activity showed the same tendency. Cecal butyrate content was significantly higher and, interestingly, GBF mice had lower bile acid concentrations than the control group.

CONCLUSIONS

GBF has the potential to reduce the epithelial inflammatory response by depressing STAT-3 expression and inhibiting NFkB binding activity. These effects may be brought about by an increase of butyrate production and adsorption of bile acids.

A comparative study of isolation-induced ultrasonic vocalization in rodent pups

The purpose of this study was to determine whether species differences in neonatal vocalizations of rodent pups could be observed. Ultrasonic vocalizations of pups of 5 rodent species, mouse (ICR), vole (Microtus arvalis), Syrian hamster, rat (Wistar-Imamichi), and Mongolian gerbil were recorded from 3 to 15 or 21 days of age. Recordings were made under conditions of separation from mothers and litter mates in a cooled chamber (approximately 10 degrees C). The major species differences observed were age specific and species specific frequencies. The Mongolian gerbil displayed a different frequency change with age. Namely, the day on which ultrasonic vocalizations ceased was delayed in Mongolian gerbil compared with the other rodents. The modal peak frequencies of ultrasound emitted from pups at 3 days of age were low (around 35 kHz) in the vole and the Syrian hamster, medium (around 45 kHz) in the rat and the Mongolian gerbil, and high (around 55 kHz) in the mouse.

The natural killer T-cell ligand alpha-galactosylceramide prevents autoimmune diabetes in non-obese diabetic mice

Diabetes in non-obese diabetic (NOD) mice is mediated by pathogenic T-helper type 1 (Th1) cells that arise because of a deficiency in regulatory or suppressor T cells. V alpha 14-J alpha 15 natural killer T (NKT) cells recognize lipid antigens presented by the major histocompatibility complex class I-like protein CD1d (refs. 3,4). We have previously shown that in vivo activation of V alpha 14 NKT cells by alpha-galactosylceramide (alpha-GalCer) and CD1d potentiates Th2-mediated adaptive immune responses. Here we show that alpha-GalCer prevents development of diabetes in wild-type but not CD1d-deficient NOD mice. Disease prevention correlated with the ability of alpha-GalCer to suppress interferon-gamma but not interleukin-4 production by NKT cells, to increase serum immunoglobulin E levels, and to promote the generation of islet autoantigen-specific Th2 cells. Because alpha-GalCer recognition by NKT cells is conserved among mice and humans, these findings indicate that alpha-GalCer might be useful for therapeutic intervention in human diseases characterized by Th1-mediated pathology such as Type 1 diabetes.

Antitumor activity of alpha-galactosylceramide, KRN7000, in mice with the melanoma B16 hepatic metastasis and immunohistological study of tumor infiltrating cells

Liver metastasis of primary tumors is clinically a major problem. We examined the antitumor activity of KRN7000, an alpha-galactosylceramide, in mice with liver metastasis of the B16 melanoma. KRN7000 significantly inhibited tumor growth in the liver, and its potency was similar to that of interleukin-12. The KRN7000 administration resulted in a high percentage of cured mice, which acquired tumor-specific immunity. To study what kinds of antitumor effector cells participated in killing tumor cells, we then performed immunohistological analysis of tumor-infiltrating cells, and found that KRN7000 induced marked invasion of NK1.1+ cells, CD8+ cells, and F4/80+ cells (macrophages) into B16 tumor nodules. In addition, it appeared that KRN7000-treated, liver-associated macrophages possessed strong lytic activity against tumor cells. These results suggest that NK cells, NK1.1+ T (NKT) cells, cytotoxic T lymphocytes, and macrophages play an important role in killing tumor cells in the liver, and that KRN7000 may be useful for the treatment of cancer liver metastasis.

Evaluation of antigenicity of germinated barley foodstuff for the treatment of ulcerative colitis in a chronic murine colitis model

Germinated barley foodstuff (GBF) contains insoluble protein and dietary fiber, and has the potential to attenuate diarrhea and colonic mucosal damage in colitis. Since GBF contains a poorly digested protein fraction, this protein may be transferred to and absorbed in the colon. It may therefore be possible to detect the GBF antigen in colitis patients with dysfunctional colonic mucosal barrier defense. In this study, the antigenic potency of GBF was examined in vivo and in vitro. Using the AOAC method, the indigestible fraction of GBF (dietary fiber) was obtained, and the poorly digested protein fraction in GBF was determined. Using Sprague Dawley rats with chronic colitis induced by dextran sulfate sodium (DSS, 2.5% in diet), a GBF and control diet were administered, and total and specific serum immunoglobulin E (IgE) against intestinal contents and the soluble GBF protein were determined. In addition, reactivity between serum and intestinal content were examined by gel electrophoresis mobility shift assay (EMSA). GBF showed relatively low protein digestibility (47%) because of its low solubility in neutral pH. Total serum IgE in both dietary groups was not significantly different, and specific IgE antibodies against intestinal contents and the soluble GBF protein were not significantly different. In addition, supershifts were not observed in either dietary group by EMSA. The possible antigenicity of oral GBF was considered to be low in this colitis model.

Roles of mitogen-activated protein kinase pathways for mediator release from human cultured mast cells

Human cultured mast cells (HCMC) secrete histamine, sulfidoleukotrienes (LTs), and prostaglandin D(2) (PGD(2)), and produce a variety of cytokines after aggregation of high-affinity receptors for IgE (FcepsilonRI). With respect to the mitogen-activated protein kinase (MAPK) family, extracellular signal-regulated kinases (ERKs), c-Jun NH(2)-terminal kinases (JNKs), and p38 mitogen-activated protein kinase (p38 MAPK) are known. To investigate the roles of these kinase pathways for mediator release from human mast cells, we examined the participation of the activation of these kinases in mediator release, using 1,4-diamino-2, 3-dicyano-1,4-bis(2-aminophenylthio)butadiene (U0126), an ERK pathway inhibitor, and 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imid azo le (SB203580), a p38 MAPK pathway inhibitor. U0126 inhibited ERK activation, LT and PGD(2) release, and granulocyte macrophage-colony stimulating factor (GM-CSF) production after stimulation of HCMC. SB203580, on the other hand, potentiated JNK activation and GM-CSF production. The findings of the present study demonstrated that: (i) the release of arachidonic acid metabolites is mediated by the ERK pathway; (ii) GM-CSF production may be driven by both the ERK and JNK pathways; and (iii) the p38 MAPK pathway negatively regulates the JNK pathway. This suggests that MAPK pathways play important roles in mediator release from human mast cells.

Functional natural killer T cells in experimental mouse strains, including NK1.1- strains

Natural killer T (NKT) cells are a newly discovered subset of lymphocytes. It appears that this subset has potential as important regulators of immune responses. But because there are relatively few NKT cells in lymphoid organs and because of technical difficulties in detecting NKT cells in most mouse strains, the roles of NKT cells have not been fully identified and little attention has been paid to the roles of NKT cells in immunological experiments in which NK1.1- strains were used. To examine the existence of functional NKT cells in various strains of experimental mice, including NK1.1- strains, we utilized alpha-galactosylceramide (KRN7000) which is thought to react specifically with NKT cells. Indeed, we could confirm that early cytokine (IL-4 and IFN-gamma) secretion at 2 h after the injection of KRN7000 was dependent on NKT cells. With this in vivo system, we have successfully detected the presence of functional NKT cells in various mouse strains, including AKR/N, BALB/c, C3H/HeJ, C3H/HeN, C57BL/6, C.B-17, CBA/N, NC, NOD, SJL, W/Wv, aly/aly and aly/+. Notable increases of serum IL-4 were detected in W/Wv and aly/+ strains, and defective response of IFN-gamma in SJL mice and that of IL-4 in NOD mice were observed. This is the first report to show the functional significance of NKT cells in cytokine secretion in various mouse strains in response to a ligand for the T cell receptor of NKT cells.

Long-term overexpression of human granulocyte colony-stimulating factor in transgenic mice: persistent neutrophilia with no increased mortality for more than one year

To investigate possible adverse consequences of persistent neutrophil overproduction, mice transgenic for human granulocyte colony-stimulating factor (hG-CSF) were studied for more than 1 year. They showed marked granulocytopoiesis and neutrophilia. Continuous medullary and extramedullary granulocytopoiesis resulted in marked changes in bone and liver. In the liver, haemorrhage and focal necrosis and a few haemangiosarcomas were present, presumably caused by the destructive granulocytopoiesis. Despite the high incidence of lung infiltration by mature neutrophils, lung lesions rarely appeared. Although there was a persistent increase in neutrophils, mortality of the mice did not differ from that of non-transgenic littermates at least within 1 year after birth. Factors other than overproduction of G-CSF and extensive neutrophilia could be required for the development of neutrophil-mediated acute and chronic tissue damage.

Deficiency of the macrophage migration inhibitory factor gene has no significant effect on endotoxaemia

By targeted disruption of the MIF gene, we have established a mouse strain deficient in macrophage (Mphi) migration inhibitory factor (MIF). Despite previous reports indicating an essential role of MIF in endotoxaemia, an injection of lipopolysaccharide (LPS) into the MIF-deficient mice (maintained under specific pathogen-free conditions) caused shock. No significant difference was detected between the MIF-deficient mutant and normal mice in susceptibility to LPS for endotoxaemia or tumour necrosis factor-alpha (TNF-alpha) formation upon LPS injection. Peritoneal Mphi from the two strains produced TNF-alpha in response to LPS with similar dose responses. Dexamethasone suppressed the LPS-induced TNF-alpha response of Mphi, but no difference was detected between the Mphi from the two strains. These results suggest that endogenous MIF has no significant effect on the LPS-induced TNF-alpha production and no effect on suppression of the response by glucocorticoids. Thus, MIF is not crucial for LPS-induced immune responses leading to shock.

Effects of luteolin, quercetin and baicalein on immunoglobulin E-mediated mediator release from human cultured mast cells

BACKGROUND

Flavonoids have a variety of activities including anti-allergic activities, and are known to inhibit histamine release from human basophils and murine mast cells.

OBJECTIVE

The effects of luteolin, a flavone, on the immunoglobulin (Ig) E-mediated allergic mediator release from human cultured mast cells (HCMCs) were investigated and compared with those of baicalein and quercetin.

METHODS

HCMCs were sensitized with IgE, and then treated with flavonoids before challenge with antihuman IgE. The amount of released mediators was determined as was mobilization of intracellular Ca2+ concentration, protein kinase C (PKC) translocation and phosphorylation of intracellular proteins were detected after anti-IgE stimulation.

RESULTS

Luteolin, baicalein and quercetin inhibited the release of histamine, leukotrienes (LTs), prostaglandin D2 (PGD2), and granulocyte macrophage-colony stimulating factor (GM-CSF) from HCMC in a concentration-dependent manner. Additionally, the three flavonoids inhibited A23187-induced histamine release. As concerns Ca2+ signalling, luteolin and quercetin inhibited Ca2+ influx strongly, although baicalein did slightly. With regard to PKC signalling, luteolin and quercetin inhibited PKC translocation and PKC activity strongly, although baicalein did slightly. The suppression of Ca2+ and PKC signallings might contribute to the inhibition of mediator release. The activation of extracellular signal-regulated kinases (ERKs) and c-Jun NH2-terminal kinase (JNK), that were activated just before the release of LTs and PGD2 and GM-CSF mRNA expression in IgE-mediated signal transduction events, were clearly suppressed by luteolin and quercetin. In contrast, the flavonoids did not affect the activation of p38 mitogen-activated protein kinase (p38 MAPK) pathway.

CONCLUSION

These results indicate that luteolin is a potent inhibitor of human mast cell activation through the inhibition of Ca2+ influx and PKC activation.

An essential role of mast cells in the development of airway hyperresponsiveness in a murine asthma model

Immunization of BALB/c mice with alum-adsorbed OVA, followed by three bronchoprovocations with aerosolized OVA, resulted in the development of airway hyperresponsiveness (AHR) and allergic inflammation in the lung accompanied by severe infiltration of eosinophils into airways. In this murine asthma model, administration of monoclonal anti-IL-5 Ab before each Ag challenge markedly inhibited airway eosinophilia, but the treatment did not affect the development of AHR. Immunization and aerosol challenges with OVA following the same protocol failed to induce AHR in the mast cell-deficient W/Wv mice, but induced AHR in their congenic littermates, i.e., WBB6F1 (+/+) mice. No significant difference was found between the W/Wv mice and +/+ mice with respect to the IgE and IgG1 anti-OVA Ab responses and to the airway eosinophilia after Ag provocations. It was also found that reconstitution of W/Wv mice with bone marrow-derived mast cells cultured from normal littermates restored the capacity of developing Ag-induced AHR, indicating that lack of mast cells was responsible for the failure of W/Wv mice to develop Ag-induced AHR under the experimental conditions. However, the OVA-immunized W/Wv mice developed AHR by increasing the frequency and Ag dose of bronchoprovocations. The results suggested that AHR could be developed by two distinct cellular mechanisms. One would go through mast cell activation and the other is IgE/mast cell independent but an eosinophil/IL-5-dependent mechanism.

Cutting Edge: Activation of NK T Cells by CD1d and α-Galactosylceramide Directs Conventional T Cells to the Acquisition of a Th2 Phenotype

NK T cells recognize glycolipid Ags such as α-galactosylceramide (α-GalCer) presented by the MHC class I-like molecule CD1d. In this paper we have studied the in vivo effects of α-GalCer on the generation of adaptive immune responses. Treatment of mice with α-GalCer resulted in rapid activation of NK T cells and production of the cytokines IL-4 and IFN-γ. However, after this initial stimulation, NK T cells became polarized for the production of IL-4. Further, as soon as 6 days after α-GalCer injection, a marked increase in serum IgE levels was observed. Administration of α-GalCer at the time of priming of mice with protein Ag resulted in the generation of Ag-specific Th2 cells and a profound increase in the production of IgE. Collectively, these findings indicate that α-GalCer may be useful for modulating immune responses toward a Th2 phenotype during prophylaxis and therapy.

Cutting edge: activation of NK T cells by CD1d and alpha-galactosylceramide directs conventional T cells to the acquisition of a Th2 phenotype

NK T cells recognize glycolipid Ags such as alpha-galactosylceramide (alpha-GalCer) presented by the MHC class I-like molecule CD1d. In this paper we have studied the in vivo effects of alpha-GalCer on the generation of adaptive immune responses. Treatment of mice with alpha-GalCer resulted in rapid activation of NK T cells and production of the cytokines IL-4 and IFN-gamma. However, after this initial stimulation, NK T cells became polarized for the production of IL-4. Further, as soon as 6 days after alpha-GalCer injection, a marked increase in serum IgE levels was observed. Administration of alpha-GalCer at the time of priming of mice with protein Ag resulted in the generation of Ag-specific Th2 cells and a profound increase in the production of IgE. Collectively, these findings indicate that alpha-GalCer may be useful for modulating immune responses toward a Th2 phenotype during prophylaxis and therapy.

Lipid antigen presentation in the immune system: lessons learned from CD1d knockout mice

CD1 molecules represent a distinct lineage of antigen-presenting molecules that are evolutionarily related to the classical major histocompatibility complex (MHC) class I and class II molecules. Unlike the classical MHC products that bind peptides, CD1 molecules have evolved to bind lipids and glycolipids. Murine and human CD1d molecules can present glycolipid antigens such as alpha-galactosylceramide (alpha-GalCer) to CD1d-restricted natural killer (NK) T cells. Using CD1d knockout mice we demonstrated that CD1d expression is required for the development of NK T cells. These animals were also deficient in the rapid production of interleukin-4 and interferon-gamma in response to stimulation by anti-CD3 antibodies. Despite these defects, CD1d knockout animals were able to generate strong T-helper type 1 (TH1) and TH2 responses. Spleen cells from these animals neither proliferated nor produced cytokines in response to stimulation by alpha-GalCer. Repeated injection of alpha-GalCer into wild-type but not CD1d mutant mice was able to clear metastatic tumors. We further showed that alpha-GalCer can inhibit disease in diabetes-prone non-obese diabetic mice. Collectively, these findings with CD1d knockout animals indicate a critical role for CD1d-dependent T cells in various disease conditions, and suggest that alpha-GalCer may be useful for therapeutic intervention in these diseases.

Role of cyclic 3',5'-adenosine monophosphate in the regulation of chemical mediator release and cytokine production from cultured human mast cells

BACKGROUND

Cultured human mast cells are known to resemble human lung mast cells in terms of the profiles of intracellular protease, the characteristics of histamine release, and the pharmacologic properties.

OBJECTIVE

The role of cyclic 3',5'-adenosine monophosphate (cAMP) in chemical mediator release and cytokine production by human mast cells was determined.

METHODS

We investigated the effects of cAMP-elevating agents on IgE-mediated chemical mediator release and cytokine production by cultured human mast cells. We also examined the relationship between intracellular cAMP levels and the inhibition of chemical mediator release or cytokine production by various drugs.

RESULTS

beta-agonists significantly suppressed IgE-mediated release of histamine, leukotrienes, and PGD2 (chemical mediators) and the production of GM-CSF, IL-5 and macrophage inflammatory protein-1alpha (cytokines). Phosphodiesterase inhibitors (theophylline, rolipram, and cilostazol) had no effect on chemical mediators but suppressed cytokine production. Dibutyryl cAMP significantly suppressed both chemical mediator release and cytokine production, suggesting that their induction was regulated by intracellular cAMP. Elevation of cAMP by beta-agonists at 10 minutes after treatment correlated well with the inhibition of histamine release. There was a significant relationship between cAMP elevation at 180 minutes and the inhibition of GM-CSF production at 360 minutes by beta-agonists, rolipram, or cilostazol. Although 100 micromol/L theophylline significantly inhibited GM-CSF production, it had no effect on cAMP.

CONCLUSION

Elevation of cAMP may be responsible for the inhibitory effect of beta-agonists, rolipram, and cilostazol on chemical mediator release and cytokine production by cultured human mast cells. In contrast, theophylline may inhibit GM-CSF production independently of cAMP.

Ca2+ and protein kinase C signaling for histamine and sulfidoleukotrienes released from human cultured mast cells

Human cultured mast cells (HCMC) release histamine and sulfidoleukotrienes (LTs) upon IgE-FcepsilonRI-mediated mast cell activation. We analyzed the Ca2+ and PKC signaling in HCMC and compared it to that in rodent mast cells. In HCMC, after IgE-mediated stimulation, an elevation of [Ca2+]i and PKC translocation to the membrane fraction was observed. As concerns Ca2+ signaling, 1) IgE-mediated histamine and LTs release was abolished after Ca2+ depletion, and the reconstitution of Ca2+ recovered the release of histamine and LTs. As regards PKC signaling, 1) staurosporine inhibited IgE-mediated mediator release. 2) PKC-downregulated mast cells did not release histamine and LTs. A23187 and PMA synergistically potentiated the activation of extracellular-regulated kinase and synergistically induced histamine and LTs release. These results demonstrated that HCMC might be useful for analysis of the signal transduction pathway for mediator release, such as histamine and LTs.

The effects of anti-asthma drugs on mediator release from cultured human mast cells

BACKGROUND

A method for generating human mast cells in vitro was recently established. Little is known about the pharmacological profiles of allergic mediator release from cultured mast cells.

OBJECTIVE

The main objective was to investigate the nature of cultured mast cells from a pharmacological point of view. We examined the effect of anti-asthma drugs on the release of histamine, sulfidoleukotrienes (LTs) and prostaglandin D2 (PGD2) from the cultured mast cells.

METHODS

Using the method established by Saito et al. we cultured cord blood mononuclear cells in the presence of 80 ng/mL stem cell factor (SCF), 50 ng/mL interleukin-6 (IL-6) and 300 nmol/L prostaglandin E2 (PGE2), and obtained almost pure (> 99%) mast cells. We sensitized cultured mast cells with immunoglobulin E (IgE)-rich serum, and then treated them with some anti-asthma drugs before challenge with anti-human IgE. Released histamine, LTs and PGD2 were measured by high-performance liquid chromatography, commercial enzyme-linked immunosorbent assay (ELISA) and enzyme immunoassay (EIA) systems, respectively.

RESULTS

The cultured mast cells released histamine, LTs and PGD2 following immunological stimulation through IgE. The mast cell stabilizing agents disodium cromoglycate (DSCG, 1 mmol/L) and azelastine (100 micromol/L) significantly inhibited the release of these three mediators. The beta-adrenoceptor agonists isoproterenol, salbutamol, and clenbuterol also inhibited all three mediators' release in a concentration-dependent manner. The non-selective and selective phosphodiesterase (PDE) inhibitors theophylline, rolipram, and cilostazol had no significant effect on mediator release at clinically useful concentrations. BAY x 1005 (a 5-lipoxygenase-activating protein inhibitor) inhibited the LTs release, whereas indomethacin (a cyclo-oxygenase I and II inhibitor) and NS-398 (a cyclo-oxygenase II inhibitor) inhibited PGD2 release.

CONCLUSIONS

The present results indicate that cultured mast cells release histamine, LTs and PGD2 following IgE crosslinking. Anti-asthma drugs showed a characteristic suppression of the release of each mediator. The suppressive actions of these drugs are similar to their pharmacological actions on human lung mast cells. These results suggest that cultured mast cells are useful for the analysis of function and pharmacological profiles of lung mast cells.

Cardiotoxicity of combined administration of adriamycin and recombinant human granulocyte colony-stimulating factor (rhG-CSF) in rats-with special reference to 125I-MIBG cardioautoradiography and histopathological findings

We studied whether adriamycin(ADM)-induced myocardial disorder in rats is advanced when recombinant human granulocyte colony-stimulating factor (rhG-CSF) is administered. Rats were divided into three groups (15 rats/group), i.e. the ADM group, the ADM+rhG-CSF group, and the vehicle-treated control group. ADM (2 mg/kg, i.p.) was administered for the first 2 days in each cycle and 10 days of administration of rhG-CSF (50 micrograms/kg, s.c.) was started two days after the second dose of ADM was given in each cycle. The dosing cycle was repeated 3 times. One day after the last dose, the following parameters were analyzed: peripheral blood and bone marrow cells, electrocardiogram (ECG) and histopathological findings. Four hours after intravenous administration of 125I-metaiodobenzylguanidine (125I-MIBG), accumulation of 125I-MIBG in some organs and findings from autoradiography (ARG) of the heart were examined. ECG revealed an extended ventricular activation (VAT) time in the ADM and ADM+rhG-CSF groups. In histopathological analysis, vacuolar degeneration of the myocardium was observed in both the ADM and ADM+rhG-CSF groups. The degree of change was the same for both groups. The accumulation of 125I-MIBG in the heart was lower in both the ADM and ADM+rhG-CSF groups than in the control group. The same tendency was observed in ARG, but the difference between the ADM group and the ADM+rhG-CSF group was not significant. These results suggest that administration of rhG-CSF at the standard clinical dose does not aggravate ADM-induced myocardial disorder. However, because this disorder may be more clearly manifested by treatment with higher doses of ADM, it is necessary to conduct further studies on the methods of dosing and administration.

Effects of streptozotocin-induced diabetes on receptive and proceptive behaviors in female rats

Sexual dysfunction in diabetic men is thoroughly recognized, while not yet done in diabetic women. Recently, Streptozotocin (STZ)-induced male rats showed a significantly depressed copulatory behavior, compared with normal animals. We investigated whether STZ-induced diabetic female rats would produce observable deficits in sexual behavior. Results in the present study are the first to show that STZ-induced diabetic female rats have a depressed sexual behavior.

[Pharmacological study of mequitazine (LM-209). (IV). General pharmacological action (author's transl)]

The general pharmacological actions of LM-209 were studied in rats, cats, dogs, guinea pigs and mice and the findings were compared with data on clemastine fumarate (CL). LM-209 but not CL produced a slight increase in pulse pressure and tachycardia. Inhibitory effects of LM-209 against contraction of the vas deferens and nictitating membrane, mainly dominated by sympathetic innervation, were remarkably less potent than CL. Inhibitory effects of LM-209 in the gastrointestinal tract were slightly more potent than CL. LM-209 accelerated norepinephrine-induced pressor reaction, while CL inhibited these effects at the dose level inhibiting histamine-induced depressor reaction. At the oral dose level showing anti-histaminic and anti-allergic actions, LM-209 but not CL had slight anti-tussive action, in an experimental model. Local anesthetic action of LM-209 was slightly more potent than that of lidocaine. LM-209 showed the same properties and potencies as CL, in most of the general pharmacological experiments.

[Pharmacological study of Mequitazine (LM-209). (V). Pharmacological actions of a main metabolite of LM-209, mequitazine sulfoxide (LM-209 SO) (author's transl)]

The pharmacological action of a main metabolite of Mequitazine (LM-209), Mequitazine sulfoxide (LM-209 SO), was compared with data on LM-209 to investigate whether LM-209 is metabolized in vivo to the active form and if it has pharmacological actions. In the excised ileum of guinea-pigs, the anti-histaminic and anti-cholinergic activities of LM-209 SO were about 1/8 and 1/20, respectively, of LM-209. The protective activity of LM-209 SO on sudden death induced by histamine in mice was about 1/2.5 of LM-209. Acute toxicity of LM-209 SO given orally to mice was 1/3 of LM-209. In the EEG of rabbits, LM-209 SO did not affect the spontaneous pattern or the arousal and recruiting responses. The mydriatic and local anesthetic activities of LM-209 SO were significantly less than those of LM-209. Thus, the pharmacological activities and toxicity of LM-209 SO were significantly less potent than those of LM-209.

[Pharmacological study of mequitazine (LM-209) (III). Action on the central nervous system (author's transl)]

The action of an anti-histaminic agent, Mequitazine (LM-209) on the central nervous system was investigated. We found that LM-209 did not affect the spontaneous and co-operative movement in mice, did not induce muscle relaxation, analgesic effects or anti-convulsant effect in micr or hypothermic effects in rats. The anti-oxotremorine effect of LM-209 in mice was about 10 times more potent than clemastine fumarate (CL) and the same as promethazine. The activity and duration of the action were also superior to diethazine and orphenadrine used as an anti-Parkinson drug. LM-209 prolonged by 50% the hypnotic time induced by hexobarbital at 50 mg/kg (p.o.) in mice, while CL prolonged 50 and 100% it at 25 and 50 mg/kg (p.o.) respectively. In the EEG of rabbits, LM-209 produced a resting pattern, inhibited the arousal responses and recruiting responses and the effect was the same as CL and less potent than promethazine. From these results, the activity of LM-209 on the central nervous system (except for the anti-oxotremorine effect) seems to be the same as or somewhat less potent than CL. Therefore LM-209 should be an effective and anti-histaminic agent for clinical application.