Tumour necrosis factor-alpha- and interleukin-1beta-stimulated cell proliferation through activation of mitogen-activated protein kinase in canine tracheal smooth muscle cells

Update of in vitro, in vivo and ex vivo fluoro-edenite effects on malignant mesothelioma: A systematic review (Review)

Fluoro-edenite (FE), asbestiform fiber found in Biancavilla (Sicily, Italy), presents various characteristics similar to the asbestos group, in particular two fibrous phases tremolite and actinolite. Indeed, epidemiological studies have shown that FE fibers have similar effects to those of asbestos fibers. Such studies have reported a high incidence of malignant mesothelioma (MM), an aggressive neoplasm of the serosal membranes lining the pleural cavity, in individuals residing there due to FE exposure in Biancavilla related to environmental contamination. Evidence has led to the classification of FE as a Group 1 human carcinogen by the International Agency for Research on Cancer (IARC). The aim of this systematic review is to compare the results achieved in in vitro, in vivo and ex vivo experimental studies involving FE in order to update the current knowledge on the pathogenesis and molecular mechanisms responsible for FE-mediated MM development as well as the availability of effective biomarkers for MM prevention and diagnosis. This review is focused on the pathophysiological mechanisms mediated by inflammation induced by FE fiber exposure and which are responsible for MM development. This review also discusses the discovery of new diagnostic and prognostic biomarkers for the management of this pathology. It is known that the risk of cancer development increases with chronic inflammation, arising from enhanced reactive oxygen species (ROS) and NO^• production stimulated by the body to remove exogenous agents, causing DNA damage and enhanced signal transduction that may lead to activation of oncogenes. Studies concerning MM biomarker discovery indicate that several biomarkers have been proposed for MM, but mesothelin is the only Food and Drug Administration (FDA)-approved biomarker for MM, with limitations. In recent studies, in silico analysis to identify selected miRNAs highly deregulated in cancer samples when compared with normal control have been developed. This in silico approach could represent an effort in the field of biomarker discovery for MM.

Club Cell Secretory Protein Deficiency Leads to Altered Lung Function

RATIONALE

CC16 (club cell secretory protein-16), a member of the secretoglobin family, is one of the most abundant proteins in normal airway secretions and has been described as a serum biomarker for obstructive lung diseases.

OBJECTIVES

To determine whether low CC16 is a marker for airway pathology or is implicated in the pathophysiology of progressive airway damage in these conditions.

METHODS

Using human data from the birth cohort of the Tucson Children's Respiratory Study, we examined the relation of circulating CC16 levels with pulmonary function and responses to bronchial methacholine challenge from childhood up to age 32 years. In wild-type and CC16-/- mice, we set out to comprehensively examine pulmonary physiology, inflammation, and remodeling in the naive airway.

MEASUREMENTS AND MAIN RESULTS

We observed that Tucson Children's Respiratory Study participants in the lowest tertile of serum CC16 had significant deficits in their lung function and enhanced airway hyperresponsiveness to methacholine challenge from 11 years throughout young adult life. Similarly, CC16-/- mice had significant deficits in lung function and enhanced airway hyperresponsiveness to methacholine as compared with wild-type mice, which were independent of inflammation and mucin production. As compared with wild-type mice, CC16-/- mice had significantly elevated gene expression of procollagen type I, procollagen type III, and α-smooth muscle actin, areas of pronounced collagen deposition and significantly enhanced smooth muscle thickness.

CONCLUSIONS

Our findings support clinical observations by providing evidence that lack of CC16 in the lung results in dramatically altered pulmonary function and structural alterations consistent with enhanced remodeling.

Chrysin Attenuates VCAM-1 Expression and Monocyte Adhesion in Lipopolysaccharide-Stimulated Brain Endothelial Cells by Preventing NF-κB Signaling

Adhesion of leukocytes to endothelial cells plays an important role in neuroinflammation. Therefore, suppression of the expression of adhesion molecules in brain endothelial cells may inhibit neuroinflammation. Chrysin (5,7-dihydroxyflavone) is a flavonoid component of propolis, blue passion flowers, and fruits. In the present study, we examined the effects of chrysin on lipopolysaccharide (LPS)-induced expression of vascular cell adhesion molecule-1 (VCAM-1) in mouse cerebral vascular endothelial (bEnd.3) cells. In bEnd.3 cells, LPS increased mRNA expression of VCAM-1 in a time-dependent manner, and chrysin significantly decreased LPS-induced mRNA expression of VCAM-1. Chrysin also reduced VCAM-1 protein expression in a concentration-dependent manner. Furthermore, chrysin blocked adhesion of monocytes to bEnd.3 cells exposed to LPS. Nuclear factor-κB (NF-κB), p38 mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase, which are all activated by LPS, were significantly inhibited by chrysin. These results indicate that chrysin inhibits the expression of VCAM-1 in brain endothelial cells by inhibiting NF-κB translocation and MAPK signaling, resulting in the attenuation of leukocyte adhesion to endothelial cells. The anti-inflammatory effects of chrysin suggest a possible therapeutic application of this agent to neurodegenerative diseases, such as multiple sclerosis, septic encephalopathy, and allergic encephalomyelitis.

Involvement of endogenous transforming growth factor-α in signal transduction pathway for interleukin-1β-induced hepatocyte proliferation

We studied the effects of interleukin (IL)-1β on DNA synthesis and cell proliferation in primary cultures of adult rat hepatocytes in order to elucidate the mechanisms of its action. Hepatocyte parenchymal cells maintained in a serum-free, defined medium synthesized DNA and proliferated in the presence of IL-1β (3-30 ng/ml), but not IL-1α (0.1-30 ng/ml) in a time- and dose-dependent manner. Specific inhibitors of growth-related signal transducers, such as AG1478, LY294002, PD98059, and rapamycin, completely abolished IL-1β-stimulated hepatocyte DNA synthesis and proliferation. Western blot analysis showed that IL-1β significantly stimulated mitogen-activated protein (MAP) kinase activation within 10 min. Addition of a monoclonal antibody against transforming growth factor (TGF)-α, but not a monoclonal antibody against insulin-like growth factor-I, to the culture dose-dependently inhibited IL-1β-induced hepatocyte mitogenesis. Culture medium TGF-α levels increased significantly within 3 min in response to IL-1β from baseline levels. Peak TGF-α levels (33 pg/ml) were reached at 10 min after IL-1β stimulation. These results indicate that the proliferative mechanism of action of IL-1β is mediated through an increase in autocrine secretion of TGF-α from primary cultured hepatocytes. Secreted TGF-α, in turn, acts as a complete mitogen to induce hepatocyte mitogenesis through the receptor tyrosine kinase/phosphatidylinositol 3-kinase/MAP kinase/mammalian target of rapamycin pathway.

Gastrokine 1 inhibits the carcinogenic potentials of Helicobacter pylori CagA

Helicobacter pylori CagA directly injected by the bacterium into epithelial cells via a type IV secretion system, leads to cellular changes such as morphology, apoptosis, proliferation and cell motility, and stimulates gastric carcinogenesis. We investigated the effects of cytotoxin-associated gene A (CagA) and gastrokine 1 (GKN1) on cell proliferation, apoptosis, reactive oxygen species (ROS) production, epithelial-mesenchymal transition (EMT) and cell migration in CagA- or GKN1-transfected gastric epithelial cells and mucosal tissues from humans and mice infected with H.pylori. On the molecular level, H.pylori CagA induced increased cell proliferation, ROS production, antiapoptotic activity, cell migration and invasion. Moreover, CagA induced activation of NF-κB and PI3K/Akt signaling pathways and EMT-related proteins. In addition, H.pylori CagA reduced GKN1 gene copy number and expression in gastric cells and mucosal tissues of humans and mice. However, GKN1 overexpression successfully suppressed the carcinogenic effects of CagA through binding to CagA. These results suggest that GKN1 might be a target to inhibit the effects from H.pylori CagA.

M2 Muscarinic acetylcholine receptor modulates rat airway smooth muscle cell proliferation

Airways chronic inflammatory conditions in asthma and COPD are characterized by tissue remodeling, being smooth muscle hyperplasia, the most important feature. Non-neuronal and neuronal Acetylcholine acting on muscarinic receptors (MAChRs) has been postulated as determinant of tissue remodeling in asthma and COPD by promoting proliferation and phenotypic changes of airway smooth muscle cells (ASMC). The objective was to evaluate proliferative responses to muscarinic agonist as carbamylcholine (Cch) and to identify the MAchR subtype involved. ASMC were isolated from tracheal fragments of Sprague-Dawley rats by enzymatic digestion. Proliferation assays were performed by MTS-PMS method. Viability was confirmed by trypan blue exclusion method. Mitogens as, epidermal growth factor (EGF), Tumor necrosis factor-alpha (TNF-α) and fetal bovine serum (FBS) increased ASMC proliferation (p < 0.05, n = 5). Cch alone increased ASMC proliferation at 24 and 48 hrs. However, combination of Cch with other mitogens exhibited a dual effect, synergistic proliferation effect in the presence of EGF (5 ng/mL) and 5% FBS and inhibiting the proliferation induced by 10% FBS, EGF (10 ng/mL) and TNF-α (10 ng/mL). To determine the MAChR subtype involved in these biological responses, a titration curve of selective muscarinic antagonists were performed. The Cch stimulatory and inhibitory effects on ASCM proliferation was blocked by AF-DX-116 (M2AChR selective antagonist), in greater proportion than 4-DAMP (M3AChR selective antagonist), suggesting that the modulation of muscarinic agonist-induced proliferation is M2AChR mediated responses. Thus, M2AChR can activate multiple signal transduction systems and mediate both effects on ASMC proliferation depending on the plethora and variable airway microenvironments existing in asthma and COPD.

MAPK/NF-κB-dependent upregulation of kinin receptors mediates airway hyperreactivity: a new perspective for the treatment

Airway hyperreactivity (AHR) is a major feature of asthmatic and inflammatory airways. Cigarette smoke exposure, and bacterial and viral infections are well-known environmental risk factors for AHR, but knowledge about the underlying molecular mechanisms on how these risk factors lead to the development of AHR is limited. Activation of intracellular mitogen-activated protein kinase (MAPK)/nuclear factor-kappa B (NF-κB) and their related signal pathways including protein kinase C (PKC), phosphoinositide 3-kinase (PI3K) and protein kinase A (PKA) signaling pathways may result in airway kinin receptor upregulation, which is suggested to play an important role in the development of AHR. Environmental risk factors trigger the production of pro-inflammatory mediators such as tumor necrosis factor-α (TNF-α) and interleukins (ILs) that activate intracellular MAPK- and NF-κB-dependent inflammatory pathways, which subsequently lead to AHR via kinin receptor upregulation. Blockage of intracellular MAPK/NF-κB signaling prevents kinin B₁ and B₂ receptor expression in the airways, resulting in a decrease in the response to bradykinin (kinin B₂ receptor agonist) and des-Arg⁹-bradykinin (kinin B₁ receptor agonist). This suggests that MAPK- and NF-κB-dependent kinin receptor upregulation can provide a novel option for treatment of AHR in asthmatic as well as in other inflammatory airway diseases.

The pro-inflammatory cytokines IL-1β and TNFα are neurotrophic for enteric neurons

Intestinal inflammation causes initial axonal degeneration and neuronal death but subsequent axon outgrowth from surviving neurons restores innervation density to the target smooth muscle cells. Elsewhere, the pro-inflammatory cytokines TNFα and IL-1β cause neurotoxicity, leading us to test their role in promoting enteric neuron death. In a rat coculture model, TNFα or IL-1β did not affect neuron number but did promote significant neurite outgrowth to twofold that of control by 48 h, while other cytokines (e.g., IL-4, TGFβ) were without effect. TNFα or IL-1β activated the NFκB signaling pathway, and inhibition of NFκB signaling blocked the stimulation of neurite growth. However, nuclear translocation of NFκB in smooth muscle cells but not in adjacent neurons suggested a dominant role for smooth muscle cells. TNFα or IL-1β sharply increased both mRNA and protein for GDNF, while the neurotrophic effects of TNFα or IL-1β were blocked by the RET-receptor blocker vandetanib. Conditioned medium from cytokine-treated smooth muscle cells mimicked the neurotrophic effect, inferring that TNFα and IL-1β promote neurite growth through NFκB-dependent induction of glial cell line-derived neurotrophic factor (GDNF) expression in intestinal smooth muscle cells. In vivo, TNBS-colitis caused early nuclear translocation of NFκB in smooth muscle cells. Conditioned medium from the intact smooth muscle of the inflamed colon caused a 2.5-fold increase in neurite number in cocultures, while Western blotting showed a substantial increase in GDNF protein. Pro-inflammatory cytokines promote neurite growth through upregulation of GDNF, a novel process that may facilitate re-innervation of smooth muscle cells and a return to homeostasis following initial damage.

Myometrial tumor necrosis factor-α receptors increase with gestation and labor and modulate gene expression through mitogen-activated kinase and nuclear factor-κB

Previously, we found that myometrial tumor necrosis factor-α (TNF-α) messenger RNA (mRNA) expression did not increase with preterm or term labor. To further investigate the role of TNF-α in human labor, we studied TNF-α receptor (TNFR1A and B) expression, regulation, and associated intracellular signaling pathways in human myometrial samples obtained both before and after the onset of labor and in primary cultures of uterine smooth muscle cells (USMCs). We found that the mRNA expression of both receptors increased with advancing gestation and labor and protein levels of TNFR1B were significantly higher in term laboring myometrial samples than in nonlabor controls. Tumor necrosis factor- treatment of USMCs activated all mitogen-activated protein kinase (MAPK) subtypes and nuclear factor κ-B (NF-κB). The TNF-α induced increases in the expression of TNFR1B and prostaglandin H synthase type 2 were reduced by inhibitors of NF-κB and MAPKs, respectively. The TNF-α induced increase in interleukin 8 (IL-8) appeared to be independent of MAPK and NF-κB pathway. These data suggest that the uterus may become more sensitive to the action of TNF-α with advancing gestation and labor and that TNF-α acts via MAPK and NF-κB to promote labor-associated gene expression.

Cytokines and growth factors promote airway smooth muscle cell proliferation

Chronic airway diseases, such as asthma or chronic obstructive pulmonary disease, are characterized by the presence in the airways of inflammation factors, growth factors and cytokines, which promote airway wall remodelling. The aim of this study was to investigate the effect of cytokines and growth factors on airway smooth muscle cell (ASMC) proliferation, phenotype and responsiveness. Incubation of serum starved human bronchial ASMCs with TNF- α , TGF, bFGF, and PDGF, but not IL-1 β , increased methyl-[(3)H]thymidine incorporation and cell number, mediated by the PI3K and MAPK signalling pathways. Regarding rabbit tracheal ASMC proliferation, TNF- α , IL-1 β , TGF, and PDGF increased methyl-[(3)H]thymidine incorporation in a PI3K- and MAPK-dependent manner. bFGF increased both methyl-[(3)H]thymidine incorporation and cell number. Moreover, incubation with TGF, bFGF and PDGF appears to drive human ASMCs towards a synthetic phenotype, as shown by the reduction of the percentage of cells expressing SM- α actin. In addition, the responsiveness of epithelium-denuded rabbit tracheal strips to carbachol was not significantly altered after 3-day treatment with bFGF. In conclusion, all the tested cytokines and growth factors increased ASMC proliferation to a different degree, depending on the specific cell type, with bronchial ASMCs being more prone to proliferation than tracheal ASMCs.

Mitogen-activated protein kinases in cerebral vasospasm after subarachnoid hemorrhage: a review

BACKGROUND

Mitogen-activated protein kinases (MAPKs) have been implicated in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage. The goal of this review is to bring together recent diverse data concerning the roles of MAPKs in cerebral vasospasm and to consider the future research.

METHOD

A review of publications in the National Library of Medicine and National Institutes of Health database was conducted in August 2009 using specific keyword search terms pertaining to subarachnoid hemorrhage and MAPKs.

FINDINGS

There are nine in vitro studies and 17 in vivo studies published. Most of previous studies used MAPK inhibitors or their upstream molecule inhibitors, and showed that MAPK inhibitions prevented vasospasm. The MAPK cascade appears to interact with other signaling molecules, and MAPK may be an important final common pathway for the signaling transduction during cerebral vasospasm. However, the mechanism by which MAPK causes sustained vascular smooth muscle contraction remains unclear. In addition, the role of endogenous MAPK inhibitors, MAPK phosphatases, has not been investigated in cerebral vasospasm.

CONCLUSIONS

The experimental data support the causative role of MAPK in cerebral vasospasm and warrant further research.

Recombinant osteopontin in cerebral vasospasm after subarachnoid hemorrhage

OBJECTIVE

Osteopontin (OPN), a pleiotropic extracellular matrix glycoprotein, has been reported to be protective against ischemic lesions, but effects of OPN on vascular functions have not been investigated. The aim of this study was to assess whether recombinant OPN (r-OPN) could prevent cerebral vasospasm after subarachnoid hemorrhage (SAH) in rats.

METHODS

r-OPN was administered intraventricularly to rats undergoing SAH by endovascular perforation, and its protective effects were evaluated by measuring the diameter of cerebral arteries and neurobehavioral testing. Western blotting and immunofluorescence were performed to explore the underlying mechanisms. An integrin receptor antagonist GRGDSP or mitogen-activated protein kinase (MAPK) phosphatase (MKP)-1 small interfering RNA (siRNA) was also administered to r-OPN-treated SAH rats, and those effects were evaluated.

RESULTS

Pre-SAH administration of r-OPN prevented vasospasm and neurological impairments at 24-72 hours post-SAH. r-OPN enhanced an endogenous MAPK inhibitor, MKP-1, and suppressed the phosphorylation of MAPKs, caldesmon, and heat shock protein 27 in the spastic cerebral arteries at 24 hours post-SAH. Immunofluorescence revealed that MKP-1 was induced in the arterial smooth muscle layer. GRGDSP prevented r-OPN-induced MKP-1 upregulation, and MKP-1 siRNA abolished both MAPK inactivation and anti-vasospastic effects by r-OPN. Post-SAH r-OPN treatment also prevented vasospasm.

INTERPRETATION

r-OPN induced MKP-1 in the spastic cerebral arteries via binding to L-arginyl-glycyl-L-aspartate-dependent integrin receptors and prevented vasospasm after SAH. Therapeutic induction of MKP-1 may be a novel approach for the prevention and treatment of cerebral vasospasm.

A nitric oxide/Ca(2+)/calmodulin/ERK1/2 mitogen-activated protein kinase pathway is involved in the mitogenic effect of IL-1beta in human astrocytoma cells

BACKGROUND AND PURPOSE

Evidence is accumulating to support a role for interleukin-1beta (IL-1beta) in astrocyte proliferation. However, the mechanism by which this cytokine modulates this process is not fully elucidated.

EXPERIMENTAL APPROACH

In this study we used human astrocytoma U-373MG cells to investigate the role of nitric oxide (NO), intracellular Ca(2+) concentration ([Ca(2+)](i)), and extracellular signal-regulated protein kinase (ERK) in the signalling pathway mediating IL-1beta-induced astrocyte proliferation.

KEY RESULTS

Low IL-1beta concentrations induced dose-dependent ERK activation which paralleled upregulation of cell division, whereas higher concentrations gradually reversed both these responses by promoting apoptosis. Pretreatment with the nonspecific NOS inhibitor, N-omega-nitro-l-arginine methyl ester (L-NAME) or the selective iNOS inhibitor, N-[[3-(aminomethyl)phenyl]methyl]-ethanimidamide dihydrochloride (1400W), antagonized ERK activation and cell proliferation induced by IL-1beta. Inhibition of cGMP formation by the guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), partially inhibited ERK activation and cell division. Functionally blocking Ca(2+) release from endoplasmic reticulum with ryanodine or 2-aminoethoxydiphenylborane (2-APB), inhibiting calmodulin (CaM) activity with N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide hydrochloride (W7) or MAPK kinase activity with 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthiol]butadiene (U0126) downregulated IL-1beta-induced ERK activation as well as cell proliferation. The cytokine induced a transient and time-dependent increase in intracellular NO levels which preceded elevation in [Ca(2+)](i).

CONCLUSIONS AND IMPLICATIONS

These data identified the NO/Ca(2+)/CaM/ERK signalling pathway as a novel mechanism mediating the mitogenic effect of IL-1beta in human astrocytes. As astrocyte proliferation is a hallmark of reactive astrogliosis, our results reveal a new potential target for therapeutic intervention in neuroinflammatory disorders.

TNF polymorphisms modify endotoxin exposure-associated longitudinal lung function decline

OBJECTIVES

Endotoxin exposure induces airway inflammation, hyper-responsiveness and higher expression of tumour necrosis factor (TNF). This study was conducted to investigate whether TNF polymorphisms modify the effect of endotoxin exposure on chronic declines in lung function.

METHODS

Associations between TNF and LTA polymorphisms, endotoxin exposure and lung function were analysed in 263 cotton workers and 230 silk workers as a reference group, who were prospectively followed for 20 years. Multiple linear regression models were used to assess the association, with adjustment for smoking and other covariates.

RESULTS

Endotoxin exposure was associated with faster lung function decline among genotypes associated with higher TNF expression levels, with estimates of annual FEV1 change in relation to endotoxin exposure of -2.9 ml and -6.8 ml in the G/G and G/A+AA genotypes, respectively, for the TNF polymorphism; and -2.0 ml, -4.0 ml and -3.6 ml in A/A, A/G and G/G genotypes, respectively, for the LTA polymorphism. When joint effects of endotoxin exposure and smoking were considered, the effect modification of TNF and LTA polymorphisms was prominent in never smokers.

CONCLUSIONS

TNF and LTA polymorphisms may modify the association between occupational endotoxin exposure and longitudinal lung function decline, which was more clearly observed in never smokers.

Involvement of MAPKs and NF-kappaB in LPS-induced VCAM-1 expression in human tracheal smooth muscle cells

Lipopolysaccharide (LPS) has been shown to induce the expression of adhesion molecules on airway epithelial and smooth cells and contributes to inflammatory responses. Here, the roles of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappaB (NF-kappaB) pathways for LPS-induced vascular cell adhesion molecule (VCAM)-1 expression were investigated in HTSMCs. LPS-induced expression of VCAM-1 protein and mRNA in a time-dependent manner, was significantly inhibited by inhibitors of MEK1/2 (U0126), p38 (SB202190), and c-Jun-N-terminal kinase (JNK; SP600125). The involvement of p42/p44 MAPK and p38 in these responses was further confirmed by that transfection with small interference RNAs (siRNA) direct against MEK, p42, and p38 significantly attenuated LPS-induced VCAM-1 expression. Consistently, LPS-stimulated phosphorylation of p42/p44 MAPK and p38 was attenuated by pretreatment with U0126 or SB202190, and transfection with these siRNAs, respectively. In addition, LPS-induced VCAM-1 expression was significantly blocked by a specific NF-kappaB inhibitor helenalin. LPS-stimulated translocation of NF-kappaB into the nucleus and degradation of IkappaB-alpha was blocked by helenalin, U0126, SB202190, or SP600125. Moreover, the resultant enhancement of VCAM-1 expression increased the adhesion of polymorphonuclear cells to monolayer of HTSMCs which was blocked by pretreatment with helenalin, U0126, or SP600125 prior to LPS exposure. Taken together, these results suggest that in HTSMCs, activation of p42/p44 MAPK, p38, and JNK pathways, at least in part, mediated through NF-kappaB, is essential for LPS-induced VCAM-1 gene expression. These results provide new insight into the mechanisms of LPS action that bacterial toxins may promote inflammatory responses in the airway disease.

Interleukin-1β induces MMP-9 expression via p42/p44 MAPK, p38 MAPK, JNK, and nuclear factor-κB signaling pathways in human tracheal smooth muscle cells

Matrix metalloproteinases (MMPs) are responsible for degradation of extracellular matrix and play important roles in cell migration, proliferation, and tissue remodeling related to airway inflammation. Interleukin-1beta (IL-1beta) has been shown to induce MMP-9 production in many cell types and contribute to airway inflammatory responses. However, the mechanisms underlying MMP-9 expression induced by IL-1beta in human tracheal smooth muscle cells (HTSMCs) remain unclear. Here, we investigated the roles of p42/p44 MAPK, p38 MAPK, JNK, and NF-kappaB pathways for IL-1beta-induced MMP-9 production in HTSMCs. IL-1beta induced production of MMP-9 protein and mRNA in a time- and concentration-dependent manner determined by zymographic, Western blotting, and RT-PCR analyses, which was attenuated by inhibitors of MEK1/2 (U0126), p38 MAPK (SB202190), JNK (SP600125), and NF-kappaB (helenalin), and transfection with dominant negative mutants of MEK1/2, p38 and JNK, respectively. IL-1beta-stimulated phosphorylation of p42/p44 MAPK, p38 MAPK, and JNK was attenuated by pretreatment with U0126, SB202190, SP600125, or transfection with these dominant negative mutants of MEK, ERK, p38 and JNK, respectively. Furthermore, IL-1beta-stimulated translocation of NF-kappaB into the nucleus and degradation of IkappaB-alpha was blocked by helenalin. Finally, the reporter gene assay revealed that MAPKs and NF-kappaB are required for IL-1beta-induced MMP-9 luciferase activity in HTSMCs. MMP-9 promoter activity was enhanced by IL-1beta in HTSMCs transfected with MMP-9-Luc, which was inhibited by helenalin, U0126, SB202190, and SP600125. Taken together, the transcription factor NF-kappaB, p42/p44 MAPK, p38 MAPK, and JNK that are involved in MMP-9 expression in HTSMCs exposed to IL-1beta have now been identified.

IL-1β activates p44/42 and p38 mitogen-activated protein kinases via different pathways in cat esophageal smooth muscle cells

AIM: To examine the pathway related to the IL-1β-induced activation of mitogen-activated protein (MAP) kinases in cat esophageal smooth muscle cells.

METHODS: Culture of the esophageal smooth muscle cells from cat was prepared. Specific inhibitors were treated before applying the IL-1β. Western blot analysis was performed to detect the expressions of COX, iNOS and MAP kinases.

RESULTS: In the primary cultured cells, although IL-1β failed to upregulate the COX and iNOS levels, the levels of the phosphorylated forms of p44/42 MAP kinase and p38 MAP kinase increased in both concentration- and time-dependent manner, of which the level of activation reached a maximum within 3 and 18 h, respectively. The pertussis toxin reduced the level of p44/42 MAP kinase phosphorylation. Tyrphostin 51 and genistein also inhibited this activation. Neomycin decreased the density of the p44/42 MAP kinase band to the basal level. Phosphokinase C (PKC) was found to play a mediating role in the IL-1β-induced p44/42 MAP kinase activity. In contrast, the activation of p38 MAP kinase was inhibited only by a pretreatment with forskolin, and was unaffected by the other compounds.

CONCLUSION: Based on these results, IL-1β-induced p44/42 MAP kinase activation is mediated by the Gi protein, tyrosine kinase, phospholipase C (PLC) and PKC. The pathway for p38 MAP kinase phosphorylation is different from that of p44/42 MAP kinase, suggesting that it plays a different role in the cellular response to IL-1β.

Chronic IL-1beta signaling potentiates voltage-dependent sodium currents in trigeminal nociceptive neurons

The proinflammatory cytokine interleukin-1beta (IL-1beta) mediates inflammation and hyperalgesia, although the underlying mechanisms remain elusive. To better understand such molecular and cellular mechanisms, we investigated how IL-1beta modulates the total voltage-dependent sodium currents (INa) and its tetrodotoxin-resistant (TTX-R) component in capsaicin-sensitive trigeminal nociceptive neurons, both after a brief (5-min) and after a chronic exposure (24-h) of 20 ng/ml IL-1beta. A brief exposure led to a 28% specific (receptor-mediated) reduction of INa in these neurons, which were found to contain type I IL-1 receptors (IL-1RI+) on both their soma and nerve endings. In marked contrast, after a 24-h exposure, the total sodium current was specifically increased by 67%, without significantly affecting the TTX-R component. This potentiation of INa was suppressed in the presence of selective inhibitors of protein kinase C and G-protein-coupled signaling pathways, thereby suggesting that INa can be modulated through multiple pathways. In summary, the potentiation of INa through chronic IL-1beta signaling in nociceptive sensory neurons may be a critical component of inflammatory-associated hyperalgesia.

Induction of cyclooxygenase-2 expression in human tracheal smooth muscle cells by interleukin-1beta: involvement of p42/p44 and p38 mitogen-activated protein kinases and nuclear factor-kappaB

Interleukin-1beta (IL-1beta) has been recognized as a potent stimulus for the synthesis of prostaglandin (PG), which has been implicated in inflammatory responses of the airways. However, the mechanisms underlying IL-1beta-induced cyclooxygenase (COX) expression and PGE(2) synthesis via activation of p42/p44 and p38 mitogen-activated protein kinases (MAPKs) in human tracheal smooth muscle cells (HTSMCs) are not completely understood. We found that IL-1beta increased COX-2 expression and PGE(2) synthesis in time- and concentration-dependent manners. Both specific phosphatidylcholine-phospholipase C inhibitor (D609) and protein kinase C inhibitor (GF109203X) attenuated IL-1beta-induced responses in HTSMCs. IL-1beta-induced COX-2 expression and PGE(2) synthesis were also inhibited by an inhibitor of MEK1/2 (PD98059) and inhibitors of p38 MAPK (SB203580 and SB202190), respectively, suggesting the involvement of p42/p44 and p38 MAPKs in these responses. This hypothesis was further supported by the transient activation of p42/p44 and p38 MAPKs induced by IL-1beta. Furthermore, IL-1beta-induced activation of nuclear factor-kappaB (NF-kappaB) was inversely correlated with the degradation of IkappaB-alpha in HTSMCs. IL-1beta-induced COX-2 expression and PGE(2) synthesis were inhibited by the NF-kappaB inhibitor pyrrolidinedithiocarbamate. These findings suggest that the expression of COX-2 is correlated with the release of PGE(2) from IL-1beta-challenged HTSMCs, which is mediated, at least in part, through p42/p44 and p38 MAPKs and NF-kappaB signaling pathways in HTSMCs.

Involvement of p42/p44 MAPK, p38 MAPK, JNK, and NF-kappaB in IL-1beta-induced VCAM-1 expression in human tracheal smooth muscle cells

Interleukin-1beta (IL-1beta) has been shown to induce the expression of adhesion molecules on airway epithelial and smooth cells and contributes to inflammatory responses. Here, the roles of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappaB (NF-kappaB) pathways for IL-1beta-induced vascular cell adhesion molecule (VCAM)-1 expression were investigated in human tracheal smooth muscle cells (HTSMC). IL-1beta induced expression of VCAM-1 protein and mRNA in a time-dependent manner, which was significantly inhibited by inhibitors of MEK1/2 (U0126 and PD-98059), p38 (SB-202190), and c-Jun NH(2)-terminal kinase (JNK; SP-600125). Consistently, IL-1beta-stimulated phosphorylation of p42/p44 MAPK, p38, and JNK was attenuated by pretreatment with U0126, SB-202190, or SP-600125, respectively. IL-1beta-induced VCAM-1 expression was significantly blocked by the specific NF-kappaB inhibitors helenalin and pyrrolidine dithiocarbamate. As expected, IL-1beta-stimulated translocation of NF-kappaB into the nucleus and degradation of IkappaB-alpha were blocked by helenalin but not by U0126, SB-202190, or SP-600125. Moreover, the resultant enhancement of VCAM-1 expression increased the adhesion of polymorphonuclear cells to a monolayer of HTSMC, which was blocked by pretreatment with helenalin, U0126, SB-202190, or SP-600125 before IL-1beta exposure or by anti-VCAM-1 antibody. Together, these results suggest that in HTSMC, activation of p42/p44 MAPK, p38, JNK, and NF-kappaB pathways is essential for IL-1beta-induced VCAM-1 gene expression. These results provide new insight into the mechanisms of IL-1beta action that cytokines may promote inflammatory responses in airway disease.

Tumor necrosis factor-alpha-induced cyclooxygenase-2 expression in human tracheal smooth muscle cells: involvement of p42/p44 and p38 mitogen-activated protein kinases and nuclear factor-kappaB

This study was to determine the mechanism of tumor necrosis factor-alpha (TNF-alpha)-enhanced cyclooxygenase (COX)-2 expression associated with prostaglandin E2 (PGE2) synthesis in human tracheal smooth muscle cells (HTSMCs). TNF-alpha markedly increased COX-2 expression and PGE2 synthesis in a time- and concentration-dependent manner, whereas COX-1 remained unaltered. Tyrosine kinase inhibitor (genistein), phosphatidylcholine-specific phospholipase C (PC-PLC) inhibitor (D-609) and PKC inhibitor (GF109203X) attenuated TNF-alpha-induced COX-2 expression and PGE2 synthesis in HTSMCs. TNF-alpha-induced COX-2 expression and PGE2 synthesis were also inhibited by PD98059 (an inhibitor of MEK1/2) and SB203580 and SB202190 (inhibitors of p38 MAPK), respectively, suggesting the involvement of p42/p44 and p38 MAPKs in these responses. This hypothesis was further supported by that TNF-alpha induced a transient activation of p42/p44 and p38 MAPKs in a time-and concentration-dependent manner. Furthermore, TNF-alpha-induced activation of nuclear factor-kappaB (NF-kappaB) reversely correlated with the degradation of IkappaB-alpha in HTSMCs. TNF-alpha-induced COX-2 expression and PGE2 synthesis was also inhibited by NF-kappaB inhibitor pyrrolidinedithiocarbamate (PDTC). These findings suggest that the increased expression of COX-2 correlates with the release of PGE2 from TNF-alpha-challenged HTSMCs, at least in part, mediated through p42/p44 and p38 MAPKs as well as NF-kappaB signaling pathways in HTSMCs.

Up-regulation of human beta-defensin 2 by interleukin-1beta in A549 cells: involvement of PI3K, PKC, p38 MAPK, JNK, and NF-kappaB

Induction of human beta-defensin 2 (HBD-2) by interleukin-1beta (IL-1beta) in epithelial cells has been reported. However, the mechanism by which IL-1beta up-regulates HBD-2 remains poorly understood. In this study, we investigated the effect of IL-1beta on induction of HBD-2 in A549 cells. IL-1beta markedly increased HBD-2 mRNA expression in concentration- and time-dependent manners. HBD-2 mRNA expression in response to IL-1beta was attenuated by pretreatment of GF109203X, Go6976, and staurosporine [inhibitors of protein kinase C (PKC)], SB203580 [an inhibitor of p38 mitogen-activated protein kinase (MAPK)], SP600125 [an inhibitor of c-Jun N-terminal kinase (JNK)], and LY294002 [an inhibitor of phosphatidylinositol-3-kinase (PI3K)], but not PD98059 [an inhibitor of extracellular signal-regulated kinase (ERK)], suggesting involvement of PKC, p38 MAPK, JNK, and PI3K in this response. Interestingly, IL-1beta induced nuclear factor-kappaB (NF-kappaB) activation in A549 cells, which was shown by increased nuclear translocation of p65 NF-kappaB and degradation of IkappaB-alpha. Importantly, IL-1beta-induced HBD-2 mRNA expression was inhibited by blockage of NF-kappaB activation using NF-kappaB inhibitors, including pyrrolidine dithiocarbamate and MG132. Specifically, IL-1beta-induced nuclear translocation of NF-kappaB was in part attenuated by LY294002, but not by GF109203X, SB203580, and SP600125, suggesting PI3K-dependent nuclear translocation of NF-kappaB in response to IL-1beta. Together, these results suggest that IL-1beta induces HBD-2 mRNA expression in A549 cells, and the induction seems to be at least in part mediated through activation of NF-kappaB transcription factor as well as activation of signaling proteins of PKC, p38 MAPK, JNK, and PI3K, but not ERK.

The mechanism of cleavage of EGFR ligands induced by inflammatory cytokines in gastric cancer cells

BACKGROUND & AIMS

The epidermal growth factor (EGF) receptor (EGFR) can be transactivated by many factors including G-protein-coupled receptor agonists and cytokines. Although this EGFR transactivation reportedly requires a disintegrin and metalloproteinase (ADAM) that sheds the ectodomain of EGFR ligands, the detailed mechanisms are still unknown. This study evaluated the mechanism of interleukin (IL)-8- and IL-1beta-dependent shedding of the EGFR ligand in KATO III cells.

METHODS

We established transfectants stably expressing alkaline phosphatase-tagged heparin-binding EGF-like growth factor (HB-EGF), transforming growth factor alpha, or amphiregulin precursors, and depleted ADAM proteins, using short interfering RNA against ADAM10, 12, or 17. We assessed shedding of EGFR ligands by measuring AP activities in the conditioned media after IL-1beta or IL-8 stimulation. EGFR activation was examined by immunoprecipitation and Western blotting using antiphosphotyrosine antibody. KB-R7785 and anti-IL-8 neutralizing antibody were used to inhibit activities of ADAMs and IL-8 action, respectively.

RESULTS

IL-8 dose dependently released the EGFR ligands and transiently phosphorylated EGFR, with a peak at 15 minutes. KB-R7785 completely blocked IL-8-induced shedding and EGFR transactivation. Depletion of ADAM10 also dramatically reduced IL-8-induced shedding and EGFR transactivation, but depletion of ADAM12 and 17 did not. IL-1beta dose dependently enhanced shedding of HB-EGF, which was not blocked by KB-R7785 in the early phase. In the late phase, however, the EGFR transactivation was blocked by KB-R7785 and abrogated by anti-IL-8 neutralizing antibody.

CONCLUSIONS

IL-8 induces shedding of EGFR ligands because of an ADAM10-dependent pathway in gastric cancer cells, whereas IL-1beta acts principally by an ADAM-independent pathway. IL-1beta-dependent prolonged EGFR transactivation involves multiple pathways, including an IL-8-dependent pathway.

Endotoxin and proinflammatory cytokines modulate Sertoli cell proliferation in vitro

Sertoli cells play a key role in testicular function and their final number in the adult testis determines the capacity of germ cell production. Sertoli cell proliferation, stimulated by FSH and paracrine factors, occurs only in fetal and prepubertal life and may be an important target of pathogenic influences affecting testis development. We used a Sertoli cell proliferation assay to address the question whether if bacterial endotoxin (lipopolysaccharide; LPS) and proinflammatory cytokines could influence early postnatal Sertoli cell development. LPS and tumor necrosis factor-alpha (TNF-alpha) dose-dependently stimulated proliferation of primary cultures of isolated Sertoli cells from 8- to 9-day-old rats, assessed by (3)H-thymidine and BrdU incorporation. LPS also significantly increased the number of living cells in culture, measured by supravital staining. Interleukin-6 (IL-6) and interferon-gamma (IFN-gamma) had no direct effect on Sertoli cell growth, but were found to modulate FSH action. IL-6 increased, while IFN-gamma inhibited, FSH-induced Sertoli cell DNA-synthesis. We conclude that endotoxin and TNF-alpha are potent direct stimulators of Sertoli cell proliferation in vitro, and that IL-6 and IFN-gamma can modulate the mitogenic action of FSH on immature Sertoli cells. This may contribute to the pathogenesis of testicular damage after infections and inflammatory diseases in fetal and early postnatal life, with subsequent disturbance of adult germ cell production.

Involvement of p42/p44 MAPK, JNK, and NF-?B in IL-1?-induced ICAM-1 expression in human pulmonary epithelial cells

Interleukin-1beta (IL-1beta) has been shown to induce the expression of intercellular adhesion molecule-1 (ICAM-1) on airway epithelial cells and contributes to inflammatory responses. However, the mechanisms regulating ICAM-1 expression by IL-1beta in human A549 cells was not completely understood. Here, the roles of mitogen-activated protein kinases (MAPKs) and NF-kappaB pathways for IL-1beta-induced ICAM-1 expression were investigated in A549 cells. IL-1beta induced expression of ICAM-1 protein and mRNA in a time- and concentration-dependent manner. The IL-1beta induction of ICAM-1 mRNA and protein were partially inhibited by U0126 and PD98059 (specific inhibitors of MEK1/2) and SP600125 [a specific inhibitor of c-Jun-N-terminal kinase (JNK)]. U0126 was more potent than other inhibitors to attenuate IL-1beta-induced ICAM-1 expression. Consistently, IL-1beta stimulated phosphorylation of p42/p44 MAPK and JNK which was attenuated by pretreatment with U0126 or SP600125, respectively. Moreover, transfection with dominant negative mutants of MEK1/2 (MEK K97R) or ERK2 (ERK2 K52R) also attenuated IL-1beta-induced ICAM-1 expression. The combination of PD98059 and SP600125 displayed an additive effect on IL-1beta-induced ICAM-1 gene expression. IL-1beta-induced ICAM-1 expression was almost completely blocked by a specific NF-kappaB inhibitor helenalin. Consistently, IL-1beta stimulated translocation of NF-kappaB into the nucleus and degradation of IkappaB-alpha which was blocked by helenalin, U0126, or SP600125. Taken together, these results suggest that activation of p42/p44 MAPK and JNK cascades, at least in part, mediated through NF-kappaB pathway is essential for IL-1beta-induced ICAM-1 gene expression in A549 cells. These results provide new insight into the mechanisms of IL-1beta action that cytokines may promote inflammatory responses in the airway disease.

Secretion of matrix metalloproteinase-9 by the proinflammatory cytokine, IL-1beta: a role for the dual signalling pathways, Akt and Erk

BACKGROUND

Matrix metalloproteinases including MMP-9 mediate matrix destruction during chronic inflammatory diseases such as arthritis and atherosclerosis. MMP-9 up-regulation by inflammatory cytokines involve interactions between several transcription factors including activator protein-1 and NFkappaB. The upstream regulatory pathways are less well understood.

RESULTS

To search for the mechanism of tissue destruction in the process of inflammatory disorders, we investigated the signalling pathway critical for the activation of MMP-9 expression and secretion by IL-1beta. Treatment of Balb 3T3 cells with IL-1beta activated MMP-9 transcription and subsequent secretion in a time- and dose-dependent manner. Concomitantly, IL-1beta treatment of cells activated phosphorylation of Akt, Erk and p38. Treatment of cells with either LY294002, a PI3K inhibitor, or expression of a dominant negative form of Akt drastically suppressed the IL-1beta-dependent secretion of MMP-9. Pretreatment of cells with a MEK1 inhibitor, U0126, also strongly inhibited IL-1beta-dependent secretion of MMP-9. In contrast, pre-treatment with a specific p38 kinase inhibitor, SB203580, had no effect on IL-1beta-dependent secretion of MMP-9. In addition, cells expressing constitutively active form of Akt or MEK1 showed no clear activation of MMP-9 secretion, whereas these cells responded well to IL-1beta treatment. However, co-transfection of cells with both active Akt and MEK1 was sufficient to induce MMP-9 secretion without stimulation with IL-1beta.

CONCLUSION

Taken together, our results suggest that IL-1beta stimulation of cells activates MMP-9 secretion by the activation of the dual signalling pathways, the PI3K-Akt and MEK1-Erk and constitutive activation of these pathways were sufficient to induce MMP-9 secretion.

IFN-gamma inhibits human airway smooth muscle cell proliferation by modulating the E2F-1/Rb pathway

Elucidating the factors that inhibit the increase in airway smooth muscle (ASM) mass may be of therapeutic benefit in asthma. Here, we investigated whether interferon-gamma (IFN-gamma), a potent inducer of growth arrest in various cell types, regulates mitogen-induced ASM cell proliferation. IFN-gamma (1-100 U/ml) was found to markedly decrease both DNA synthesis and ASM cell number induced by the mitogens epidermal growth factor (EGF) and thrombin. Interestingly, IFN-gamma had no effect on mitogen-induced activation of three major mitogenic signaling pathways, phosphatidylinositol 3-kinase, p70(S6k), or mitogen-activated protein kinases. Mitogen-induced expression of cell cycle regulator cyclin D1 was increased by IFN-gamma, whereas no effect was observed on degradation of p27(Kip1). Expression array analysis of 23 cell cycle-related genes showed that IFN-gamma inhibited EGF-induced increases in E2F-1 expression, whereas induction of c-myc, cyclin D2, Egr-1, and mdm2 were unaffected. Induction of E2F-1 protein and Rb hyperphosphorylation after mitogen stimulation was also suppressed by IFN-gamma. In addition, IFN-gamma decreased activation of cdk2 and expression of cyclin E, upstream signaling molecules responsible for Rb hyperphosphorylation in the late G1 phase. IFN-gamma also increased levels of IFI 16 protein, whose mouse homolog p202 has been associated with growth inhibition. Together, our data indicate that IFN-gamma is an effective inhibitor of ASM cell proliferation by blocking transition from G1-to-S phase by acting at two different levels: modulation of cdk2/cyclin E activation and inhibition of E2F-1 gene expression.

A role for SHPS-1/SIRPalpha1 in IL-1beta- and TNFalpha-dependent signaling

We investigated the role of SHPS-1/SIRPalpha1 in IL-1beta- and TNFalpha-dependent signaling that leads to the activation of Erk 1/2 and Akt. Treatment of Balb3T3 cells with IL-1beta or TNFalpha activated tyrosine phosphorylation of SHPS-1, its association with SHP-2 and the phosphorylation of Erk 1/2 and Akt. PP1, a specific inhibitor for the Src family protein tyrosine kinases, strongly inhibited tyrosine phosphorylation of SHPS-1 and complex formation of SHPS-1 with SHP-2 by IL-1beta. In addition, PP1 substantially inhibited the IL-2beta- and TNFalpha-dependent activation of Erk 1/2 and Akt. Exogenous expression of either SHPS-1 mutants that lack SHP-2 binding function or a dominant negative mutant of SHP-2 markedly inhibited the activation of Erk 1/2 and Akt by IL-1beta, whereas wild type SHPS-1 did not. Moreover, IL-1beta-stimulation induced association of SHPS-1 with IL-1RAcP, a second subunit of IL-1 receptor, whereas expression of SHPS-1 mutant that lack SHP-2 binding function clearly blocked the association and tyrosine phosphorylation of endogenous SHPS-1. Taken together, our results strongly suggest that activation of Erk 1/2 and Akt by proinflammatory cytokines requires tyrosine phosphorylation of SHPS-1 and subsequent association of SHPS-1 with SHP-2.

Interleukin-1beta-induced cyclooxygenase-2 expression is mediated through activation of p42/44 and p38 MAPKS, and NF-kappaB pathways in canine tracheal smooth muscle cells

Interleukin-beta (IL-1beta) was found to induce inflammatory responses in the airways, which exerted a potent stimulus for PG synthesis. This study was to determine the mechanisms of IL-1beta-enhanced cyclooxygenase (COX)-2 expression associated with PGE(2) synthesis in tracheal smooth muscle cells (TSMCs). IL-1beta markedly increased COX-2 expression and PGE(2) formation in a time- and concentration-dependent manner in TSMCs. Both COX-2 expression and PGE(2) formation in response to IL-1beta were attenuated by a tyrosine kinase inhibitor, genistein, a phosphatidylcholine-phospholipase C inhibitor, D609, a phosphatidylinositol-phospholipase C inhibitor, U73122, protein kinase C inhibitors, GF109203X and staurosporine, removal of Ca(2+) by addition of BAPTA/AM plus EGTA, and phosphatidylinositol 3-kinase (PI3-K) inhibitors, LY294002 and wortmannin. IL-1beta-induced activation of NF-kappaB correlated with the degradation of IkappaB-alpha in TSMCs. IL-1beta-induced NF-kappaB activation, COX-2 expression, and PGE(2) synthesis were inhibited by the dominant negative mutants of NIK and IKK-alpha, but not by IKK-beta. IL-1beta-induced COX-2 expression and PGE(2) synthesis were completely inhibited by PD98059 (an inhibitor of MEK1/2) and SB203580 (an inhibitor of p38 inhibitor), but these two inhibitors had no effect on IL-1beta-induced NF-kappaB activation, indicating that activation of p42/44 and p38 MAPK and NF-kappaB signalling pathways were independently required for these responses. These findings suggest that the increased expression of COX-2 correlates with the release of PGE(2) from IL-1beta-challenged TSMCs, at least in part, independently mediated through MAPKs and NF-kappaB signalling pathways in canine TSMCs. IL-1beta-mediated responses were modulated by PLC, Ca(2+), PKC, tyrosine kinase, and PI3-K in these cells.

Long-term modulation of glucose utilization by IL-1 alpha and TNF-alpha in astrocytes: Na+ pump activity as a potential target via distinct signaling mechanisms

Interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha) markedly stimulate glucose utilization in primary cultures of mouse cortical astrocytes. The mechanism that gives rise to this effect, which takes place several hours after application of cytokine, has remained unclear. Experiments were conducted to identify the major signaling cascades involved in the metabolic action of cytokine. First, the selective IL-1 receptor antagonist (IL-1ra) prevents the effect of IL-1alpha on glucose utilization in a concentration-dependent manner, whereas it has no effect on the action of TNF-alpha. Then, using inhibitors of three classical signaling cascades known to be activated by cytokines, it appears that the PI3 kinase is essential for the effect of both IL-1alpha and TNF-alpha, whereas the action of IL-1alpha also requires activation of the MAP kinase pathway. Participation of a phospholipase C-dependent pathway does not appear critical for both IL-1alpha and TNF-alpha. Inhibition of NO synthase by L-NAME did not prevent the metabolic response to both IL-1alpha and TNF-alpha, indicating that nitric oxide is probably not involved. In contrast, the Na(+)/K(+) ATPase inhibitor ouabain prevents the IL-1alpha- and TNF-alpha-stimulated 2-deoxyglucose (2DG) uptake. When treatment of astrocytes with a cytokine was followed 24 h later by an acute application of glutamate, a synergistic enhancement in glucose utilization was observed. This effect was greatly reduced by ouabain. These data suggest that Na(+) pump activity is a common target for both the long-term metabolic action of cytokines promoted by the activation of distinct signaling pathways and the enhanced metabolic response to glutamate.

Inhibitory effect with antisense mitogen-activated protein kinase oligodeoxynucleotide against cerebral vasospasm in rats

BACKGROUND AND PURPOSE

Mitogen-activated protein kinase (MAPK) may be associated with the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). This study aimed to clarify the role of MAPK expression and activation during cerebral vasospasm and to evaluate the therapeutic effect on cerebral vasospasm using an antisense MAPK oligodeoxynucleotide (ODN).

METHODS

Antisense MAPK, sense MAPK, or scrambled ODN was injected into the rats intracisternally. We used a single-hemorrhage experimental SAH model to assess vasospasm in the basilar arteries at 30 minutes, 1 day, and 2 days after SAH by cross-sectional area measurement and other histological parameters. Immunohistochemistry and Western blot analysis were used to quantify MAPK expression and activation. In addition, a double-hemorrhage rat SAH model was used to test the effect of post-SAH treatment with antisense MAPK ODN.

RESULTS

Antisense MAPK therapy significantly inhibited cerebral vasospasm when compared with sense MAPK or scrambled ODN treatment on day 2. The immunohistochemistry and Western blotting performed in the basilar artery of rats that received antisense MAPK ODN demonstrated inhibition of MAPK and phosphorylated MAPK on day 2. In post-SAH treatment study, antisense ODN reduced MAPK and phosphorylated MAPK in the basilar artery and attenuated cerebral vasospasm.

CONCLUSIONS

MAPK activation, but not expression, might be implicated with sustained smooth muscle contraction during cerebral vasospasm after SAH. This study suggests that antisense MAPK ODN strategy is an effective treatment against cerebral vasospasm.

Opposite role of Ras in tumor necrosis factor-alpha-induced cell cycle regulation: competition for Raf kinase

Ras, a well-known oncogene, induces cell cycle stimulation through the Raf/Erk pathway and leads to cellular transformation, accompanied by other oncogenes such as c-myc and viral oncogenic protein. Here we suggest the interfering role of Ras in tumor necrosis factor (TNF)-alpha-induced cell cycle regulation. In TSU-Pr1 and T24 (oncogenic Ras cell lines), TNF-alpha suppresses cell cycle progression without induction of apoptosis, whereas AGS (wild-type Ras) is stimulated in its cell cycle by TNF-alpha coupled with activation of Erk. However, in TSU-Pr1 and T24, TNF-alpha leads to dephosphorylation of Erk1/2. Inhibition or activation of Ras can restore or convert TNF-alpha-induced cell cycle regulation in the cell lines containing the oncogenic Ras (TSU-Pr1 and T24) or AGS, respectively. Regulation of Erk also shows the coincidental pattern. We suggest the competition between the Ras pathway and TNF signaling for the binding to Raf, a common downstream target, as the cause of such reciprocal response, based on co-immunoprecipitation (co-IP) with antibodies against Raf and Ras or cellular Flice-inhibitory protein (c-FLIP), which have been recently identified upstream of Raf in death-ligand-induced cell cycle stimulation. Overexpression of Raf in TSU-Pr1, to reduce the competition, overcomes TNF-induced cell cycle arrest, also supporting our hypotheses.

Tumour necrosis factor-alpha enhances bradykinin-induced signal transduction via activation of Ras/Raf/MEK/MAPK in canine tracheal smooth muscle cells

Inhalation of tumour necrosis factor-alpha (TNF-alpha) induced a bronchial hyperreactivity to contractile agonists. However, the mechanisms of TNF-alpha involved in the pathogenesis of bronchial hyperreactivity were not completely understood. Therefore, we investigated the effect of TNF-alpha on bradykinin (BK)-induced inositol phosphate (IP) accumulation and Ca(2+) mobilization, and up-regulation of BK receptor density in canine cultured tracheal smooth muscle cells (TSMCs). Pretreatment of TSMCs with TNF-alpha potentiated BK-induced IP accumulation and Ca(2+) mobilization. However, there was no effect on the IP response induced by endothelin-1 (ET-1), 5-hydroxytryptamine (5-HT), and carbachol. Pretreatment with PDGF B-chain homodimer (PDGF-BB) also enhanced BK-induced IP response. These enhancements induced by TNF-alpha and PDGF-BB might be due to an increase in BK B(2) receptor density (B(max)), since [3H]BK binding to TSMCs was inhibited by the B(2) selective agonist and antagonist, BK and Hoe 140, but not by the B(1) selective reagents. The enhancing effects of TNF-alpha and PDGF-BB were attenuated by PD98059 (an inhibitor of activation of MAPK kinase, MEK) and cycloheximide (an inhibitor of protein synthesis), suggesting that TNF-alpha may share a common signalling pathway with PDGF-BB via protein(s) synthesis in TSMCs. Furthermore, overexpression of dominant negative mutants, H-Ras-15A and Raf-N4, significantly suppressed p42/p44 mitogen-activated protein kinase (MAPK) activation induced by TNF-alpha and PDGF-BB and attenuated the effect of TNF-alpha on BK-induced IP response, indicating that Ras and Raf may be required for activation of these kinases. These results suggest that the augmentation of BK-induced responses produced by TNF-alpha might be, at least in part, mediated through activation of Ras/Raf/MEK/MAPK pathway in TSMCs.

IL-1 induced chemokine production through the association of Syk with TNF receptor-associated factor-6 in nasal fibroblast lines

The fibroblasts stimulated by cytokines released the chemokine and recruited the infiltrating cells, including eosinophils, that play a key role in the pathogenesis of airway disease. We established the human fibroblast lines showing high Syk expression and the lines showing low Syk expression from pieces of nasal polyp. IL-1 induces the interaction of TNFR-associated factor (TRAF) 6 with IL-1R-associated kinase, which is rapidly recruited to the IL-1R after IL-1 induction, whereas TRAF2 participates in TNF-alpha-signaling. In the present study, we found that Syk played a different role in IL-1- and TNF-alpha-induced chemokine production through a signaling complex involving Syk and TRAF6. Overexpression of wild-type Syk by gene transfer enhanced RANTES production from nasal fibroblasts stimulated with IL-1. The decrease of Syk expression by the administration of Syk antisense inhibited RANTES production in response to IL-1. However, the change of Syk expression did not affect RANTES production by TNF-alpha stimulation. We concluded that Syk is required for the IL-1-induced chemokine production through the association with TRAF-6 in fibroblasts of nasal polyps.

Mitogenic effect of oxidized low-density lipoprotein on vascular smooth muscle cells mediated by activation of Ras/Raf/MEK/MAPK pathway

1. It has been demonstrated that oxidized low-density lipoprotein (OX-LDL) is a risk factor in atherosclerosis by stimulating vascular smooth muscle cell (VSMC) proliferation. However, the mechanisms of OX-LDL-induced cell proliferation are not completely understood. Therefore, we investigated the effect of OX-LDL on cell proliferation associated with mitogen-activated protein kinase (MAPK) activation in rat cultured VSMCs. 2. Both native-LDL (N-LDL) and OX-LDL induced a time- and concentration-dependent incorporation of [(3)H]-thymidine in VSMCs. 3. OX-LDL induced time- and concentration-dependent phosphorylation of p42/p44 MAPK. Pretreatment of these cells with pertussis toxin or U73122 attenuated the OX-LDL-induced responses. 4. Pretreatment with PMA for 24 h, preincubation with a PKC inhibitor staurosporine or the tyrosine kinase inhibitors, genistein and herbimycin A for 1 h, substantially reduced [(3)H]-thymidine incorporation and p42/p44 MAPK phosphorylation induced by OX-LDL. 5. Removal of Ca(2+) by BAPTA/AM or depletion of the internal Ca(2+) pool by thapsigargin significantly inhibited OX-LDL-induced [(3)H]-thymidine incorporation and p42/p44 MAPK phosphorylation. 6. OX-LDL-induced [(3)H]-thymidine incorporation and p42/p44 MAPK phosphorylation was inhibited by PD98059 (an inhibitor of MEK1/2) and SB203580 (an inhibitor of p38 MAPK) in a concentration-dependent manner. 7. Overexpression of dominant negative mutants of Ras (H-Ras-15A) and Raf (Raf-N4) significantly suppressed MEK1/2 and p42/p44 MAPK activation induced by OX-LDL and PDGF-BB, indicating that Ras and Raf may be required for activation of these kinases. 8. These results suggest that the mitogenic effect of OX-LDL is mediated through a PTX-sensitive G protein-coupled receptor that involves the activation of the Ras/Raf/MEK/MAPK pathway similar to that of PDGF-BB in rat cultured VSMCs.