Biomedical subjects

Hannu Kankaanranta

Publications and source records attributed to Hannu Kankaanranta.

At least 19 recordsLinked to original sources

PubMed2006

The glucocorticoid RU24858 does not distinguish between transrepression and transactivation in primary human eosinophils.

BACKGROUND: Glucocorticoids are used to treat chronic inflammatory diseases such as asthma. Induction of eosinophil apoptosis is considered to be one of the main mechanisms behind the anti-asthmatic effect of glucocorticoids. Glucocorticoid binding to its receptor (GR) can have a dual effect on gene transcription. Activated GR can activate transcription (transactivation), or by interacting with other transcription factors such as NF-kappaB suppress transcription (transrepression). RU24858 has been reported to transrepress but to have little or no transactivation capability in other cell types. The dissociated properties of RU24858 have not been previously studied in non-malignant human cells. As the eosinophils have a very short lifetime and many of the modern molecular biological methods cannot be used, a "dissociated steroid" would be a valuable tool to evaluate the mechanism of action of glucocorticoids in human eosinophils. The aim of this study was to elucidate the ability of RU24858 to activate and repress gene expression in human eosinophils in order to see whether it is a dissociated steroid in human eosinophils. METHODS: Human peripheral blood eosinophils were isolated under sterile conditions and cultured in the presence and/or absence RU24858. For comparison, dexamethasone and mometasone were used. We measured chemokine receptor-4 (CXCR4) and Annexin 1 expression by flow cytometry and cytokine production by ELISA. Apoptosis was measured by DNA fragmentation and confirmed by morphological analysis. RESULTS: RU24858 (1 microM) increased CXCR4 and Annexin 1 expression on eosinophils to a similar extent as mometasone (1 microM) and dexamethasone (1 microM). Like dexamethasone and mometasone, RU24858 did suppress IL-8 and MCP-1 production in eosinophils. RU24858 also increased spontaneous eosinophil apoptosis to a similar degree as dexamethasone and mometasone, but unlike dexamethasone and mometasone it did not reverse IL-5- or GM-CSF-induced eosinophil survival. CONCLUSION: Our results suggest that in human eosinophils RU24858 acts as transactivator and transrepressor like classical glucocorticoids. Thus, RU24858 seems not to be a "dissociated steroid" in primary human eosinophils in contrast to that reported in animal cells. In addition, functionally RU24858 seems to be a less potent glucocorticoid as it did not reverse IL-5- and GM-CSF-afforded eosinophil survival similarly to dexamethasone and mometasone.

Journal Article↗

PubMed2006

c-Jun N-terminal kinase mediates constitutive human eosinophil apoptosis.

Eosinophils are considered to play an important role in the pathogenesis of asthma. Glucocorticoids are potent anti-inflammatory agents for the treatment of chronic inflammatory diseases and they have been shown to increase the rate of eosinophil apoptosis. c-Jun N-terminal kinase (JNK) has been suggested to participate in the signaling pathways of apoptosis. The aims of the present study were to examine whether JNK is involved in the regulation of constitutive eosinophil apoptosis and whether it mediates dexamethasone-induced apoptosis of human eosinophils. Isolated human eosinophils were cultured with and without dexamethasone and the JNK inhibitor L-JNKI-1. Apoptosis was assessed by measuring the relative DNA content of propidium iodide-stained cells and confirmed by Annexin V-binding and morphological analysis with bright field microscopy. The phosphorylation of both JNK and c-Jun were measured by Western blotting. During a 40h culture, dexamethasone (1muM) enhanced human eosinophil apoptosis by 10-30%. Culture with L-JNKI1 (10muM) inhibited apoptosis in dexamethasone-treated cells by 53%. Furthermore, L-JNKI1 decreased the rate of constitutive eosinophil apoptosis by 64%. However, the enhancement of eosinophil apoptosis by dexamethasone was not reversed by L-JNKI1. Slow activation of JNK in constitutive apoptosis as well as a similar tendency in dexamethasone-induced eosinophil apoptosis could be observed by Western blot analyses. c-Jun was found to be active both in the presence and absence of dexamethasone. However, no further phosphorylation of the serine residue 63 of c-Jun could be seen. Taken together, our present results suggest that JNK is active during apoptosis of human eosinophils both in the presence and absence of glucocorticoids. JNK seems to mediate constitutive human eosinophil apoptosis. However, the activity of JNK is not enhanced by glucocorticoids and the effects of glucocorticoids cannot be reversed by JNK inhibition. JNK therefore seems not to mediate glucocorticoid-induced human eosinophil apoptosis.

Annexin A5↗

PubMed2006

Antieosinophilic activity of orazipone.

Orazipone is a novel sulfhydryl-reactive compound that has been previously shown to reduce lung eosinophilia in guinea pigs and rats and to inhibit degranulation in mast cells and cytokine production in monocytes and T-cells. However, the effects of orazipone on granulocyte longevity are unknown. Orazipone and its derivative 3-(4-chloro-3-nitro-benzylidene)-pentane-2,4-dione (OR-2370) reversed interleukin-5-afforded survival of human eosinophils by inducing apoptosis. In contrast, orazipone did not affect granulocyte macrophage-colony-stimulating factor-induced survival of human neutrophils. The effect of orazipone on eosinophil apoptosis is different from that of glucocorticoids in that even high con-centrations of interleukin-5 were not able to overcome the effect of orazipone. Orazipone further enhanced spontaneous apoptosis as well as that induced by CD95 ligation without inducing primary necrosis. OR-2370-induced DNA fragmentation was shown to be dependent on caspases 3 and 6 and c-jun-N-terminal kinase, whereas extracellular regulated kinase, p38 mitogen-activated protein kinase, and phosphatidylinositol 3-kinase as well as caspases 4, 8, and 9 seem not to mediate its actions. Our results suggest that orazipone and its derivative OR-2370 possess strong antieosinophilic activity and thus may have anti-inflammatory efficacy in the treatment of asthma and/or allergic conditions.

Apoptosis↗

PubMed2006

Inhibition of p38 mitogen-activated protein kinase enhances c-Jun N-terminal kinase activity: implication in inducible nitric oxide synthase expression.

BACKGROUND: Nitric oxide (NO) is an inflammatory mediator, which acts as a cytotoxic agent and modulates immune responses and inflammation. p38 mitogen-activated protein kinase (MAPK) signal transduction pathway is activated by chemical and physical stress and regulates immune responses. Previous studies have shown that p38 MAPK pathway regulates NO production induced by inflammatory stimuli. The aim of the present study was to investigate the mechanisms involved in the regulation of inducible NO synthesis by p38 MAPK pathway. RESULTS: p38 MAPK inhibitors SB203580 and SB220025 stimulated lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS) expression and NO production in J774.2 murine macrophages. Increased iNOS mRNA expression was associated with reduced degradation of iNOS mRNA. Treatment with SB220025 increased also LPS-induced c-Jun N-terminal kinase (JNK) activity. Interestingly, JNK inhibitor SP600125 reversed the effect of SB220025 on LPS-induced iNOS mRNA expression and NO production. CONCLUSION: The results suggest that inhibition of p38 MAPK by SB220025 results in increased JNK activity, which leads to stabilisation of iNOS mRNA, to enhanced iNOS expression and to increased NO production.

Animals↗

PubMed2006

JNK inhibitor SP600125 reduces COX-2 expression by attenuating mRNA in activated murine J774 macrophages.

Inducible prostaglandin synthase (cyclooxygenase-2, COX-2) is highly expressed in inflammation. The signaling mechanisms involved in the up-regulation of COX-2 are not known in detail. In the present study we investigated the role of c-Jun NH2-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family in COX-2 expression and prostaglandin (PG) E2 production in murine J774 macrophages activated by bacterial lipopolysaccharide (LPS). LPS caused a transient activation of JNK which was followed by increased COX-2 expression. Anthra(1,9-cd)pyrazol-6(2H)-one (SP600125), an inhibitor of JNK, inhibited phosphorylation of c-Jun with an IC50 of 5-10 microM. At the same concentrations SP600125 suppressed also LPS-induced COX-2 protein levels and PGE2 production. SP600125 did not alter LPS-induced COX-2 mRNA levels when measured 3 h after addition of LPS, whereas mRNA levels were significantly reduced in SP600125-treated cells when measured 24 h after addition of LPS. LPS-induced COX-2 mRNA levels reduced faster in cells treated with SP600125 than in control cells. Cycloheximide (that is known to activate JNK) enhanced COX-2 expression and its effect was inhibited by SP600125. The present results suggest that JNK pathway is involved in the up-regulation of COX-2 expression possibly by a mechanism related to the stability of COX-2 mRNA.

Animals↗

PubMed2006

Inhibition of classical PKC isoenzymes downregulates STAT1 activation and iNOS expression in LPS-treated murine J774 macrophages.

Proinflammatory cytokines and bacterial products trigger inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production in inflammatory and tissue cells. In inflammation, NO acts as an important mediator having both proinflammatory and destructive effects. Protein kinase C (PKC) is a family of serine-threonine protein kinase isoenzymes involved in signal transduction pathways related to inflammatory responses. The aim of the present study was to investigate the role of classical PKC (cPKC) isoenzymes in the regulation of iNOS expression and NO production in murine J774 macrophages and the mechanisms involved. RO318220 (inhibits PKCbeta, PKCgamma and PKCvarepsilon), GO6976 (inhibits cPKC isoenzymes PKCalpha and PKCbeta) and LY333531 (inhibits PKCbeta) reduced lipopolysaccharide (LPS)-induced NO production and iNOS expression in a dose-dependent manner as did 6 h pretreatment with 1 microM phorbol 12-myristate 13-acetate (PMA) (which was shown to downregulate PKC expression). PKC inhibitors also reduced LPS-induced iNOS mRNA levels, but they did not affect the half-life of iNOS mRNA. PKC inhibitors did not alter LPS-induced activation of NF-kappaB as measured by electrophoretic mobility shift assay. All PKC inhibitors used and pretreatment with 1 microM PMA inhibited signal transducer and activator of transcription 1 (STAT1) activation as measured by the translocation of STAT1alpha from the cytosol to the nucleus by Western blot. In addition, inhibition of STAT1 activation by AG-490, an inhibitor of JAK-2, also reduced NO production. These results suggest that cPKC isoenzymes, especially PKCbeta, mediate the upregulation of iNOS expression and NO production in activated macrophages in an NF-kappaB-independent manner, possibly through the activation of transcription factor STAT1.

Animals↗

PubMed2006

JAK inhibitors AG-490 and WHI-P154 decrease IFN-gamma-induced iNOS expression and NO production in macrophages.

In inflammation, inducible nitric oxide synthase (iNOS) produces nitric oxide (NO), which modulates inflammatory processes. We investigated the effects of Janus kinase (JAK) inhibitors, AG-490 and WHI-P154, on iNOS expression and NO production in J774 murine macrophages stimulated with interferon-gamma (IFN-gamma). JAK inhibitors AG-490 and WHI-P154 decreased IFN-gamma-induced nuclear levels of signal transducer and activator of transcription 1alpha (STAT1alpha). JAK inhibitors AG-490 and WHI-P154 decreased also iNOS protein and mRNA expression and NO production in a concentration-dependent manner. Neither of the JAK inhibitors affected the decay of iNOS mRNA when determined by actinomycin D assay. Our results suggest that the inhibition of JAK-STAT1-pathway by AG-490 or WHI-P154 leads to the attenuation of iNOS expression and NO production in IFN-gamma-stimulated macrophages.

Animals↗

PubMed2005

Inhibitors of mitogen-activated protein kinases downregulate COX-2 expression in human chondrocytes.

Inducible prostaglandin synthase (cyclooxygenase-2, COX-2) is expressed in rheumatoid and osteoarthritic cartilage and produces high amounts of proinflammatory prostanoids in the joint. In the present study we investigated the effects of the inhibitors of mitogen-activated protein kinase (MAPK) pathways Erk1/2, p38, and JNK on COX-2 expression and prostaglandin E2 (PGE2) production in human chondrocytes. Proinflammatory cytokine IL-1beta caused a transient activation of Erk1/2, p38, and JNK in immortalized human T/C28a2 chondrocytes and that was followed by enhanced COX-2 expression and PGE2 production. PD98059 (an inhibitor of Erk1/2 pathway) suppressed IL-1-induced COX-2 expression and PGE2 production in a dose-dependent manner, and seemed to have an inhibitory effect on COX-2 activity. SB203580 (an inhibitor of p38 pathway) but not its negative control compound SB202474 inhibited COX-2 protein and mRNA expression and subsequent PGE2 synthesis at micromolar drug concentrations. SP600125 (a recently developed JNK inhibitor) but not its negative control compound N1-methyl-1,9-pyrazolanthrone downregulated COX-2 expression and PGE2 formation in a dose-dependent manner. SP600125 did not downregulate IL-1-induced COX-2 mRNA expression when measured 2 h after addition of IL-1beta but suppressed mRNA levels in the later time points suggesting post-transcriptional regulation. Our results suggest that activation of Erk1/2, p38, and JNK pathways belongs to the signaling cascades that mediate the upregulation of COX-2 expression and PGE2 production in human chondrocytes exposed to proinflammatory cytokine IL-1beta.

Anthracenes↗

PubMed2005

Inhibition of tristetraprolin expression by dexamethasone in activated macrophages.

Tristetraprolin (TTP) is a factor that regulates mRNA stability and the expression of certain inflammatory genes. In the present study, we found that TTP expression was increased in macrophages exposed to bacterial lipopolysaccharide (LPS). Dexamethasone and dissociated steroid RU24858 inhibited LPS-induced TTP protein and mRNA expression and the inhibitory effect was reversed by a glucocorticoid receptor antagonist mifepristone. Histone deacetylase inhibitors trichostatin A (TSA) and apicidin reduced the inhibitory effect of dexamethasone and RU24858 on TTP expression, but the glucocorticoids did not alter TTP mRNA half-life. These results suggest that anti-inflammatory steroids reduce TTP expression in activated macrophages by a glucocorticoid response element (GRE)-independent mechanism, possibly through histone deacetylation and transcriptional silencing.

Animals↗

PubMed2005

Peripheral inflammation in patients with asthmatic symptoms but normal lung function.

Some patients with asthmatic symptoms and eosinophilic airway inflammation have normal lung function and thus do not meet the current diagnostic criteria of asthma. Exhaled nitric oxide (NO) measurement at multiple exhalation flow rates can be used to assess alveolar and bronchial NO output and inflammation. We tested whether alveolar or bronchial NO output is increased in subjects having asthmatic symptoms but normal lung function. Exhaled NO concentration was measured at three exhalation flow rates (100, 175, and 370 mL/s) to assess alveolar NO concentration and bronchial NO flux in 23 patients with asthmatic symptoms but normal lung function ("asthmatic symptoms group"), 40 patients with asthma, and 40 healthy control subjects. The asthmatic symptoms group had increased bronchial NO flux (1.7 +/- 0.3 nL/s, p = 0.016) and alveolar NO concentration (1.8 +/- 0.2 parts per billion (ppb), p = 0.010) compared with healthy controls (0.7 +/- 0.1 nL/s and 1.0 +/- 0.1 ppb, respectively). Patients with asthma had even higher bronchial NO flux (2.5 +/- 0.3 nL/s, p = 0.024) but normal alveolar NO concentration (1.1 +/- 0.2 ppb, p = 0.664). In asthmatic symptoms group, alveolar NO concentration correlated positively with blood eosinophil count and negatively with small airway function (FEF50% and FEF75%). In conclusion, patients with asthmatic symptoms but normal lung function have increased alveolar NO concentration and mildly elevated bronchial NO flux suggesting a more peripheral inflammation than in patients with asthma.

Adult↗

PubMed2005

Ketotifen induces primary necrosis of human eosinophils.

Eosinophils are considered essential in the pathogenesis of allergy. Reduced eosinophil apoptosis is considered to be a key element in the formation of eosinophilia in allergic conditions. Antihistamines are widely used in the treatment of allergic disorders, but their effects on eosinophil apoptosis are poorly understood. The histamine H1-receptor antagonist, ketotifen, is available orally and as eye drops for the treatment of allergic symptoms. The aim of our study was to investigate the possible effect of ketotifen on constitutive eosinophil apoptosis and on interleukin (IL)-5-mediated eosinophil survival. Isolated peripheral blood eosinophils were cultured with or without the survival-prolonging cytokine IL-5 and ketotifen. Apoptosis was assessed by measuring the relative DNA content and by morphological analysis. Ketotifen was found to reverse eosinophil survival induced by interleukin-5. However, the flow cytometry histogram of DNA in propidium iodide-stained cells was not typical to apoptosis. Morphological analysis of the eosinophils by bright-field microscopy suggested that the effect of ketotifen was due to the induction of primary necrosis rather than apoptosis. Histological assessment of eosinophil ultrastructure by transmission electron microscopy confirmed signs of advanced necrosis. In summary, our results suggest that at clinically relevant drug concentrations, ketotifen induces primary necrosis in IL-5-treated human eosinophils.

Apoptosis↗

PubMed2005

Nitric oxide production and signaling in inflammation.

Nitric oxide (NO) is recognized as a mediator and regulator of inflammatory responses. It possesses cytotoxic properties that are aimed against pathogenic microbes, but it can also have damaging effects on host tissues. NO reacts with soluble guanylate cyclase to form cyclic guanosine monophosphate (cGMP), which mediates many of the effects of NO. NO can also interact with molecular oxygen and superoxide anion to produce reactive nitrogen species that can modify various cellular functions. These indirect effects of NO have a significant role in inflammation, where NO is produced in high amounts by inducible nitric oxide synthase (iNOS) and reactive oxygen species are synthesized by activated inflammatory cells. The present review deals with NO production and signaling in inflammation, especially in relation to human neutrophils and eosinophils.

Animals↗

PubMed2005

Pharmacological regulation of human eosinophil apoptosis.

Eosinophilic inflammation of the airways is a key characteristic of asthma. The balance between eosinophil recruitment into the lung and their removal from the lungs determines the number of eosinophils in the airways. Apoptosis or programmed cell death is of importance in the removal of eosinophils from the lungs. In asthma, eosinophil apoptosis is delayed. Glucocorticoids enhance eosinophil apoptosis, whereas beta(2)-agonists may delay apoptosis in eosinophils. Detailed knowledge on the mechanisms that regulate this process gives an opportunity to develop specific asthma therapies targeting the eosinophil. This review aims to focus on the signalling leading to or preventing apoptosis in human eosinophils as well as reviews the current evidence on the regulation of eosinophil apoptosis and/or survival in allergic diseases.

Animals↗

PubMed2004

Add-on therapy options in asthma not adequately controlled by inhaled corticosteroids: a comprehensive review.

Many patients with persistent asthma can be controlled with inhaled corticosteroids (ICS). However, a considerable proportion of patients remain symptomatic, despite the use of ICS. We present systematically evidence that supports the different treatment options. A literature search was made of Medline/PubMed to identify randomised and blinded trials. To demonstrate the benefit that can be obtained by increasing the dose of ICS, dose-response studies with at least three different ICS doses were identified. To demonstrate whether more benefit can be obtained by adding long-acting beta2-agonist (LABA), leukotriene antagonist (LTRA) or theophylline than by increasing the dose of ICS, studies comparing these options were identified. Thirdly, studies comparing the different "add-on" options were identified. The addition of a LABA is more effective than increasing the dose of ICS in improving asthma control. By increasing the dose of ICS, clinical improvement is likely to be of small magnitude. Addition of a LTRA or theophylline to the treatment regimen appears to be equivalent to doubling the dose of ICS. Addition of a LABA seems to be superior to an LTRA in improving lung function. However, addition of LABA and LTRA may be equal with respect to asthma exacerbations. However, more and longer studies are needed to better clarify the role of LTRAs and theophylline as add-on therapies.

Administration, Inhalation↗

PubMed2003

Regulation of eosinophil apoptosis by nitric oxide: Role of c-Jun-N-terminal kinase and signal transducer and activator of transcription 5.

BACKGROUND: Reduced eosinophil apoptosis is considered to be a key mechanism for eosinophilia in allergic diseases such as asthma, rhinitis, and eczema. OBJECTIVE: The aim of our study was to investigate the possible modulatory effect of nitric oxide (NO) in human eosinophils. METHODS: Apoptosis in isolated eosinophils was assessed by relative DNA fragmentation assay, annexin-V binding, and morphologic analysis. The activation of c-Jun-N-terminal kinase (JNK) and signal transducer and activator of transcription 5 (STAT5) was assessed by immunoblot analysis. RESULTS: The NO donor S-nitroso-N -acetylpenicillamine (SNAP) reversed the survival-prolonging effect of IL-5 by inducing apoptosis. This effect was blocked by the NO scavenger (2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3 oxide.potassium salt), indicating that reversal of IL-5-mediated eosinophil survival was due to NO. The effect of NO on IL-5-afforded cell survival was not mediated by cyclic guanosine 3': 5'-monophosphate (cGMP), because neither an inhibitor of guanylyl cyclase nor inhibitors of phosphodiesterases had any effect on SNAP-induced eosinophil apoptosis in IL-5-treated cells. SNAP induced a time-dependent increase in the activity of JNK, and an inhibitor peptide specific for JNK, L-JNKI1, completely reversed SNAP-induced apoptosis in IL-5-treated eosinophils. In contrast, SNAP did not inhibit IL-5-induced STAT5 activation. Inhibition of the activity of caspases by Z-Asp-CH(2)-DCB reversed the effect of SNAP, suggesting that NO promotes apoptosis in IL-5-treated human eosinophils in a caspase-dependent manner. However, this effect of NO was not mediated by means of activation of caspases 3, 8, or 9. CONCLUSIONS: Our results suggest that exogenous NO reverses IL-5-mediated eosinophil survival by inducing apoptosis, and this is mediated by means of activation of JNK in a cGMP-independent manner.

Apoptosis↗

PubMed2003

c-Jun NH2-terminal kinase inhibitor anthra(1,9-cd)pyrazol-6(2H)-one reduces inducible nitric-oxide synthase expression by destabilizing mRNA in activated macrophages.

In this study, we investigated the role of c-Jun NH2-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family, in lipopolysaccharide (LPS)-stimulated inducible nitric-oxide synthase (iNOS) expression and nitric oxide (NO) production in J774 murine macrophages. Anthra(1,9-cd)pyrazol-6(2H)-one (SP600125), a pharmacological inhibitor of JNK, inhibited phosphorylation of c-Jun with an IC50 of 5 to 10 microM. At the same concentrations, SP600125 inhibited LPS-induced iNOS protein expression and NO production. SP600125 had no effect on the activation of nuclear factor kappaB, which is an important transcription factor for iNOS expression. SP600125 had no significant effect on iNOS mRNA levels if measured 4 h after LPS. In contrast, SP600125 reduced iNOS mRNA levels >90% when measured 8 h after LPS. These data suggest that SP600125 reduced iNOS mRNA stability, and this was confirmed in the mRNA degradation assay using actinomycin D, in which SP600125 reduced the iNOS mRNA half-life from 5 to 2 h. These results show that the JNK pathway is involved in the up-regulation of LPS-induced iNOS expression and NO production by a mechanism related to the stabilization of iNOS mRNA.

Animals↗

PubMed2002

P38 mitogen-activated protein kinase inhibitor SB203580 has a bi-directional effect on iNOS expression and NO production.

In the present study, the mediator role of p38 kinase, a member of the mitogen-activated protein kinase (MAPK) family, was studied in lipopolysaccharide-induced inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production in J774 mouse macrophages and T-84 human colon epithelial cells. Two pyridinyl imidazole inhibitors of p38 MAPK, 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-imidazole (SB203580) and 4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)-imidazole (SB202190), stimulated NO production at low drug concentrations, maximal stimulation occurring at 1 microM drug concentration. In contrast, higher concentrations inhibited NO production, which was>90% at 30 microM drug concentration. The bi-directional effect was found in both cell types tested. Negative control compound SB202474, which is structurally related but does not inhibit p38, did not stimulate NO production but inhibited it at 30 microM concentration. A chemically different p38 inhibitor 2-methyl-4-phenyl-5-(4-pyridyl)oxazole (SC68376) had only a stimulatory action on NO production. Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) analysis of iNOS showed that both stimulatory and inhibitory effects of SB203580 occurred at the level of iNOS expression. SB203580 did not alter lipopolysaccharide-induced NF-kappaB activation as detected by electrophoretic mobility shift assay (EMSA). The data show that pyridinyl imidazoles SB203580 and SB202190 have a bi-directional effect on NO production through iNOS pathway depending on the drug concentration used. The inhibitory effect was unrelated to inhibition of p38 MAPK, whereas the stimulatory effect is most likely mediated by p38 MAPK dependent mechanism, suggesting a novel mechanism for regulation of iNOS expression, which is common for murine and human cells.

Animals↗

PubMed2002

Divergent effect of mometasone on human eosinophil and neutrophil apoptosis.

Mometasone is a potent synthetic glucocorticoid, which is under development as an inhaled preparation for the treatment of asthma. Previous studies have suggested that glucocorticoids have direct effects on human eosinophil and neutrophil apoptosis. The present study was designed to characterize the effects of mometasone on constitutive apoptosis and cytokine-afforded survival in isolated human eosinophils and neutrophils. The isolated eosinophils or neutrophils were cultured in vitro, and apoptosis was assessed by flow cytometric analysis of relative DNA content, by annexin-V binding and morphological analysis. Mometasone enhanced constitutive human eosinophil apoptosis in a concentration-dependent manner. The maximal enhancement of eosinophil apoptosis was 2.1-fold with an EC(50) value of 5.63 +/- 2.33 nM. This enhancing effect was reversed by the glucocorticoid receptor antagonist, mifepristone. In the presence of added cytokines, mometasone reversed tumor necrosis factor -alpha-induced eosinophil survival but not that afforded by interleukin -5. In contrast, mometasone inhibited human neutrophil apoptosis in a concentration-dependent manner. The maximal inhibition of neutrophil apoptosis was 50% with an EC(50) value of 0.17 +/- 0.03 nM. The inhibitory effect was partly reversed by mifepristone. In the presence of added cytokines, mometasone further enhanced neutrophil survival induced by the granulocyte-macrophage colony-stimulating factor and leukotriene B(4). The present data suggests that mometasone has opposite effects on apoptosis of human eosinophils and neutrophils at clinically relevant drug concentrations via an effect on glucocorticoid receptor.

Apoptosis↗