p38 mitogen activated protein kinase regulates endothelial VCAM-1 expression at the post-transcriptional level

Characterization of p38 MAPKs from orange-spotted grouper, Epinephelus coioides involved in SGIV infection

p38 mitogen-activated protein kinases (MAPKs) are broadly expressed signaling molecules that involves in the regulation of cellular responsible for various extracellular stimuli. In this study, three p38 MAPK genes (Ec-p38a, p38b and p38β) were cloned from grouper, Epinephelus coioides and their characteristics were investigated in vitro. Although Ec-p38a, p38b and p38β showed high homologies to other fish p38a MPAK, p38b MAPK and p38β MAPK, respectively, they all contained the conserved structures of Thr-Gly-Tyr (TGY) motif and substrate binding site Ala-Thr-Arg-Trp (ATRW). Phylogenetic analysis indicated that Ec-p38a, p38b and p38β are more closely related to those from fish than mammals. The tissue distribution patterns of Ec-p38a, p38b and p38β were different, and Ec-p38β was up-regulated most obviously in head kidney after Singapore grouper iridovirus (SGIV) infection. Overexpression of Ec-p38β in FHM cells delayed the occurrence of CPE induced by SGIV infection. Further analysis indicated that overexpression of Ec-p38β inhibited viral gene transcription and protein synthesis, as well as SGIV induced typical apoptosis in fish cells. Taken together, our data indicated that Ec-p38β played a crucial role in regulating apoptosis and virus replication during iridovirus infection.

Deletion of apoptosis signal-regulating kinase-1 prevents ventilator-induced lung injury in mice

Both hyperoxia and mechanical ventilation can independently cause lung injury. In combination, these insults produce accelerated and severe lung injury. We recently reported that pre-exposure to hyperoxia for 12 hours, followed by ventilation with large tidal volumes, induced significant lung injury and epithelial cell apoptosis compared with either stimulus alone. We also reported that such injury and apoptosis are inhibited by antioxidant treatment. In this study, we hypothesized that apoptosis signal-regulating kinase-1 (ASK-1), a redox-sensitive, mitogen-activated protein kinase kinase kinase, plays a role in lung injury and apoptosis in this model. To determine the role of ASK-1 in lung injury, the release of inflammatory mediators and apoptosis, attributable to 12 hours of hyperoxia, were followed by large tidal volume mechanical ventilation with hyperoxia. Wild-type and ASK-1 knockout mice were subjected to hyperoxia (Fi(O(2)) = 0.9) for 12 hours before 4 hours of large tidal mechanical ventilation (tidal volume = 25 μl/g) with hyperoxia, and were compared with nonventilated control mice. Lung injury, apoptosis, and cytokine release were measured. The deletion of ASK-1 significantly inhibited lung injury and apoptosis, but did not affect the release of inflammatory mediators, compared with the wild-type mice. ASK-1 is an important regulator of lung injury and apoptosis in this model. Further study is needed to determine the mechanism of lung injury and apoptosis by ASK-1 and its downstream mediators in the lung.

Allergic rhinitis: an update on disease, present treatments and future prospects

Allergic rhinitis (AR) is an inflammation of nasal mucosa mediated by IgE-associated processes occurring independently, or concurrently with asthma. AR is characterized by sensitization-formation and expression of antigen specific IgE, followed by inflammation in two phases. The early phase response involves cross linking of IgE molecules leading to degranulation of mast cells and release of preformed mediators such as histamine and tryptase, or newly synthesized mediators such as prostaglandins and leukotrienes. The late phase response is predominated by the presence of eosinophils, lymphocytes, cytokines, and adhesion molecules. Newer insights reveal that the whole phenomenon of immunological inflammation is intricately knit with neural pathways, which strongly influence the process. Furthermore, AR can impact psychological health and vice versa. Classical pharmacotherapy of AR includes use of oral or topical antihistamines, oral antileukotrienes, topical corticosteroids, mast cell stabilizers, decongestants, and an anticholinergic agent. Among immunomodulatory treatments, immunotherapy is gaining widespread use, while antibody treatment is restricted mainly to resistant cases. Several small molecules with improved safety profile, or targeting novel mechanisms are in the clinical research. Newer antihistamines and corticosteroids with improved safety profile and antagonists of the prostaglandin D(2) (CRTH2) receptors are likely to be available for clinical use in the near future. Lack of properly validated animal models and complexities associated with clinical evaluation are some of the challenges facing the researchers in AR. Comprehensive understanding of immunological and neurological processes in AR would facilitate the future quest for more effective and safer management of this disease.

Age-induced augmentation of p38 MAPK phosphorylation in mouse lung

The p38 mitogen-activated protein kinase (p38 MAPK) pathway is a key regulator of pro-inflammatory cytokine biosynthesis, which may contribute to the chronic low-grade inflammation observed with aging. We hypothesize that aging up-regulates the activation of p38 MAPK as well as the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) in mouse lung, and is accompanied by disturbances in oxidant-antioxidant status. In addition, the elevated protein levels of phosphorylated active form of p38 MAPK (phospho-p38 MAPK) with age are tissue-specific. To test this hypothesis, protein levels of phospho-p38 MAPK were determined using Western blot analysis in isolated lung, brain, heart, spleen, kidney and muscle of young (2-month-old) and aged (20-month-old) male C57BL/6J mice. Results show that phospho-p38 MAPK protein levels, not total-p38 MAPK, increased significantly (p<0.01, n=8) in lung and brain of 20-month-old mice. The activation of p38 MAPK in other tissues was not altered with age. Immunostaining showed that epithelial cells and alveolar macrophages in lung parenchyma were the major cellular sources of phospho-p38 MAPK immunity. As measured by enzyme-linked immunosorbent assay (ELISA), TNF-α, IL-1β and IL-6 in lung homogenates were elevated significantly with age, but there were no differences with age in serum levels except for IL-6. In addition, IL-1β and IL-6 were increased notably while TNF-α was not different with age in bronchoalveolar lavage fluid (BALF). Furthermore, the oxidant-antioxidant status was evaluated by measuring pro-oxidant malondialdehyde (MDA) levels and the activity of reactive oxygen species scavenging enzymes (i.e. superoxide dismutase (SOD) and glutathione (GSH)) in lung homogenates. The results showed that SOD and GSH decreased with age, while MDA did not change. In conclusion, our data demonstrate that p38 MAPK is activated during lung aging with a corresponding increase in pro-inflammatory cytokines and decrease in antioxidant capacity.

Apoptosis signal-regulating kinase 1 is an intracellular inducer of p38 MAPK-mediated myogenic signalling in cardiac myoblasts

Myogenic differentiation is an essential process for the myogenesis in response to various extracellular stimuli. p38 MAPK is a core signalling molecule in myogenic differentiation. The activation of p38 MAPK is required for myogenic differentiation; however, the mechanism for this activation remains undefined. ASK1 is a member of the MAP3K family that activates both JNK and p38 MAPK pathways in response to an array of stresses such as oxidative stress, endoplasmic reticulum stress and calcium influx. Here, we reported that TNFα was significantly released from H9c2 cardiac myoblast in differentiation medium. Furthermore, the oxidant H(2)O(2) acted as a messenger in the TNFα signalling pathway to disrupt the complex of ASK1-Trx, which was followed by the activation of ASK1 in cardiac myogenic differentiation. Subsequently, the activated ASK1 stimulated MKK3/6-p38MAPK signalling cascade to induce specific myogenic differentiation. In addition, exogenous TNFα added to the medium at physiological levels enhanced the ASK1-p38 MAPK signalling pathway through the increased generation of H(2)O(2). Interestingly, inhibition of p38 MAPK abrogated the production of H(2)O(2), suggesting that there might be a positive feedback loop in the myogenic-redox signalling pathway. These results indicate that ASK1 is a new intracellular regulator of activation of the p38 MAPK in cardiac myogenic differentiation.

Dual specificity phosphatase 1 regulates human inducible nitric oxide synthase expression by p38 MAP kinase

The role of dual specificity phosphatase 1 (DUSP1) in inducible nitric oxide synthase (iNOS) expression in A549 human pulmonary epithelial cells, J774 mouse macrophages and primary mouse bone marrow-derived macrophages (BMMs) was investigated. iNOS expression was induced by a cytokine mixture (TNF, IFNγ and IL-1β) in A549 cells and by LPS in J774 cells, and it was inhibited by p38 MAPK inhibitors SB202190 and BIRB 796. Stimulation with cytokine mixture or LPS enhanced also DUSP1 expression. Down-regulation of DUSP1 by siRNA increased p38 MAPK phosphorylation and iNOS expression in A549 and J774 cells. In addition, LPS-induced iNOS expression was enhanced in BMMs from DUSP1^(−/−) mice as compared to that in BMMs from wild-type mice. The results indicate that DUSP1 suppresses iNOS expression by limiting p38 MAPK activity in human and mouse cells. Compounds that enhance DUSP1 expression or modulate its function may be beneficial in diseases complicated with increased iNOS-mediated NO production.

Polyphenols from red wine are potent modulators of innate and adaptive immune responsiveness

It is well known that the consumption of dietary polyphenols leads to beneficial effects for human health as in the case of prevention and/or attenuation of cardiovascular, inflammatory, neurodegenerative and neoplastic diseases. This review summarizes the role of polyphenols from red wine in the immune function. In particular, using healthy human peripheral blood mononuclear cells, we have demonstrated the in vitro ability of Negroamaro, an Italian red wine, to induce the release of nitric oxide and both pro-inflammatory and anti-inflammatory cytokines, thus leading to the maintenance of the immmune homeostasis in the host. All these effects were abrogated by deprivation of polyphenols from red wine samples. We have also provided evidence that Negromaro polyphenols are able to activate extracellular regulated kinase and p38 kinase and switch off the NF-kappaB pathway via an increased expression with time of the IkappaBalpha phosphorylated form. These mechanisms may represent key molecular events leading to inhibition of the pro-inflammatory cascade and atherogenesis. In conclusion, according to the current literature and our own data, moderate consumption of red wine seems to be protective for the host in the prevention of several diseases, even including aged-related diseases by virtue of its immunomodulating properties.

p38 mitogen-activated protein kinase promotes cell survival in response to DNA damage but is not required for the G(2) DNA damage checkpoint in human cancer cells

p38 mitogen-activated protein kinase (MAPK) is rapidly activated by stresses and is believed to play an important role in the stress response. While Chk1 is known to mediate G(2) DNA damage checkpoint control, p38 was also reported to have an essential function in this checkpoint control. Here, we have investigated further the roles of p38 and Chk1 in the G(2) DNA damage checkpoint in cancer cells. We find that although p38 activation is strongly induced by DNA damage, its activity is not required for the G(2) DNA damage checkpoint. In contrast, Chk1 kinase is responsible for the execution of G(2) DNA damage checkpoint control in p53-deficient cells. The inhibition of p38 activity has no effect on Chk1 activation and gamma-H2AX expression. Global gene expression profiling of cancer cells in response to tumor necrosis factor alpha (TNF-alpha) revealed that p38 plays a strong prosurvival role through the coordinated downregulation of proapoptotic genes and upregulation of prosurvival genes. We show that the inhibition of p38 activity during G(2) DNA damage checkpoint arrest triggers apoptosis in a p53-independent manner with a concurrent decrease in the level of Bcl2 family proteins. Our results suggest that although p38 MAPK is not required for the G(2) DNA damage checkpoint function, it plays an important prosurvival role during the G(2) DNA damage checkpoint response through the upregulation of the Bcl2 family proteins.

p38 Mitogen-activated protein kinase signalling regulates vascular inflammation and epithelial barrier dysfunction in an experimental model of radiation-induced colitis

BACKGROUND

: Microvascular injury and epithelial barrier dysfunction are rate-limiting aspects in radiation enteropathy. This study examined the role of p38 mitogen-activated protein kinase (p38 MAPK) signalling in radiation-induced colitis in an experimental model.

METHODS

: The p38 MAPK inhibitor SB239063 was administered to mice immediately before exposure to 20 Gy radiation. Leucocyte- and platelet-endothelium interactions in the colonic microcirculation were assessed by intravital microscopy. Levels of myeloperoxidase (MPO) and CXC chemokines (macrophage inflammatory protein (MIP) 2 and cytokine-induced neutrophil chemoattractant (KC)), and albumin leakage were quantified 16 h after irradiation.

RESULTS

: Irradiation induced an increase in leucocyte and platelet recruitment, MPO activity, CXC chemokine levels and intestinal leakage. Inhibition of p38 MAPK by SB239063 decreased radiation-induced leucocyte and platelet recruitment (leucocyte rolling and adhesion by 70 and 90 per cent, both P < 0.001; that of platelets by 70 and 74 per cent, both P < 0.001). It also reduced radiation-provoked increases in colonic MPO activity by 88 per cent (P < 0.001), formation of MIP-2 and KC by 72 and 74 per cent respectively (P = 0.003 and P < 0.001), and intestinal leakage by 81 per cent (P < 0.001).

CONCLUSION

: p38 MAPK is an important signalling pathway in radiation-induced colitis.

Complex regulation and function of the inflammatory smooth muscle cell phenotype in atherosclerosis

Vascular smooth muscle cell (SMC) phenotypic modulation plays a key role in atherosclerosis and is classically defined as a switch from a 'contractile' phenotype to a 'synthetic' phenotype, whereby genes that define the contractile SMC phenotype are suppressed and proliferation and/or migratory mechanisms are induced. There is also evidence that SMCs may take on a 'proinflammatory' phenotype, whereby SMCs secrete cytokines and express cell adhesion molecules, e.g. IL-8, IL-6, and VCAM-1, respectively, which may functionally regulate monocyte and macrophage adhesion and other processes during atherosclerosis. Factors that drive the inflammatory phenotype are not limited to cytokines but also include hemodynamic forces imposed on the blood vessel wall and intimate interaction of endothelial cells with SMCs, as well as changes in matrix composition in the vessel wall. However, it is critical to recognize that our understanding of the complex interaction of these multiple signal inputs has only recently begun to shed light on mechanisms that regulate the inflammatory SMC phenotype, primarily through models that attempt to recreate this environment ex vivo. The goal of this review is to summarize our current knowledge in this area and identify some of the key unresolved challenges and questions requiring further study.

Heat shock protein 27 phosphorylation: kinases, phosphatases, functions and pathology

The small heat shock protein Hsp27 or its murine homologue Hsp25 acts as an ATP-independent chaperone in protein folding, but is also implicated in architecture of the cytoskeleton, cell migration, metabolism, cell survival, growth/differentiation, mRNA stabilization, and tumor progression. A variety of stimuli induce phosphorylation of serine residues 15, 78, and 82 in Hsp27 and serines 15 and 86 in Hsp25. This post-translational modification affects some of the cellular functions of Hsp25/27. As a consequence of the functional importance of Hsp25/27 phosphorylation, aberrant Hsp27 phosphorylation has been linked to several clinical conditions. This review focuses on the different Hsp25/27 kinases and phosphatases that regulate the phosphorylation pattern of Hsp25/27, and discusses the recent findings of the biological implications of these phosphorylation events in physiological and pathological processes. Novel therapeutic strategies aimed at restoring anomalous Hsp27 phosphorylation in human diseases will be presented.

Activation of Nrf2 in endothelial cells protects arteries from exhibiting a proinflammatory state

OBJECTIVE

Proinflammatory mediators influence atherosclerosis by inducing adhesion molecules (eg, VCAM-1) on endothelial cells (ECs) via signaling intermediaries including p38 MAP kinase. Regions of arteries exposed to high shear stress are protected from inflammation and atherosclerosis, whereas low-shear regions are susceptible. Here we investigated whether the transcription factor Nrf2 regulates EC activation in arteries.

METHODS AND RESULTS

En face staining revealed that Nrf2 was activated in ECs at an atheroprotected region of the murine aorta where it negatively regulated p38-VCAM-1 signaling, but was expressed in an inactive form in ECs at an atherosusceptible site. Treatment with sulforaphane, a dietary antioxidant, activated Nrf2 and suppressed p38-VCAM-1 signaling at the susceptible site in wild-type but not Nrf2(-/-) animals, indicating that it suppresses EC activation via Nrf2. Studies of cultured ECs revealed that Nrf2 inactivates p38 by suppressing an upstream activator MKK3/6 and by enhancing the activity of the negative regulator MKP-1.

CONCLUSIONS

Nrf2 prevents ECs at the atheroprotected site from exhibiting a proinflammatory state via the suppression of p38-VCAM-1 signaling. Pharmacological activation of Nrf2 reduces EC activation at atherosusceptible sites and may provide a novel therapeutic strategy to prevent or reduce atherosclerosis.

Specific p38 inhibition in stimulated endothelial cells: a possible new anti-inflammatory strategy after hypothermia and rewarming

To protect immature organ systems during corrective cardiac surgery, patients are cooled to a minimal temperature of 17 degrees C during cardiopulmonary bypass (CPB). However hypothermic CPB triggers the whole body inflammatory response and results in unwanted prolonged inflammation. The present study was designed to clarify the hypothermia and rewarming induced mechanisms and examine interventional pharmacological strategies that could prevent prolonged inflammation. Stimulated primary human umbilical vein endothelial cells (HUVECs) were exposed to a dynamic temperature protocol analogous to clinical settings. Furthermore endothelial cells were pretreated with methylprednisolone and/or tacrolimus as well as with MAPK inhibitors (SB203580, U0126 and SP600125). Cell viability, expression of IL-6 and ERK 1/2, p38 and SAPK/JNK were investigated. Stimulated endothelial cells secreted significantly higher IL-6 protein 2h after rewarming in comparison to normothermic control cells. Moreover, dynamic temperature changes lead to increased MAPK phosphorylation. Only the combined pre-treatment with MP and TAC served to inhibit the IL-6 secretion. As intracellular signalling pathway we could demonstrate that SB203580 as specific p38 inhibitor most effectively down regulated the unwanted IL-6 release after cooling and rewarming. Therefore inhibition of p38 or components of the p38 pathway could be a promising and selective antiinflammatory therapeutic target after hypothermic CPB.

Sulforaphane inhibits TNF-alpha-induced activation of p38 MAP kinase and VCAM-1 and MCP-1 expression in endothelial cells

OBJECTIVE AND DESIGN

To investigate the effects of sulforaphane on endothelial inflammatory gene expression in endothelial cells.

MATERIALS AND METHODS

Human aortic endothelial cells were used in the study.

RESULTS

One-hour pretreatment of endothelial cells (EC) with sulforaphane (1-4 muM) suppressed TNF-alpha-induced MCP-1 and VCAM-1 mRNA and protein levels, but had no effect on TNF-alpha-induced ICAM-1 expression. Sulforaphane also inhibited TNF-alpha-induced activation of p38 MAP kinase, but not c-Jun-N-terminal kinase. Sulforaphane had no effect on TNF-alpha-induced NF-kappaB nuclear binding activity, IkappaB-alpha degradation or activation of NF-kappaB-driven transcriptional activity. Expression of dominant negative Nrf2 inhibited sulforaphane-induced antioxidant response element (ARE)-driven promoter activity, but had no effect on sulforaphane-mediated inhibition of VCAM-1 and MCP-1 expression.

CONCLUSION

These data suggest that sulforaphane may be useful as a therapeutic agent for the treatment of inflammatory diseases.

NF-kappaB, but not p38 MAP kinase, is required for TNF-alpha-induced expression of cell adhesion molecules in endothelial cells

In response to inflammation stimuli, tumor necrosis factor-alpha (TNF-alpha) induces expression of cell adhesion molecules (CAMs) in endothelial cells (ECs). Studies have suggested that the nuclear factor-kappaB (NF-kappaB) and the p38 MAP kinase (p38) signaling pathways play central roles in this process, but conflicting results have been reported. The objective of this study is to determine the relative contributions of the two pathways to the effect of TNF-alpha. Our initial data indicated that blockade of p38 activity by chemical inhibitor SB203580 (SB) at 10 microM moderately inhibited TNF-alpha-induced expression of three types of CAMs; ICAM-1, VCAM-1 and E-selectin, indicating that p38 may be involved in the process. However, subsequent analysis revealed that neither 1 microM SB that could completely inhibit p38 nor specific knockdown of p38alpha and p38beta with small interference RNA (siRNA) had an apparent effect, indicating that p38 activity is not essential for TNF-alpha-induced CAMs. The most definitive evidence to support this conclusion was from the experiments using cells differentiated from p38alpha knockout embryonic stem cells. We could show that deletion of p38alpha gene did not affect TNF-alpha-induced ICAM-1 and VCAM-1 expression when compared with wild-type cells. We further demonstrated that inhibition of NF-kappaB completely blocked TNF-alpha-induced expression of ICAM-1, VCAM-1 and E-selectin. Taken together, our results clearly demonstrate that NF-kappaB, but not p38, is critical for TNF-alpha-induced CAM expression. The inhibition of SB at 10 microM on TNF-alpha-induced ICAM-1, VCAM-1 and E-selectin is likely due to the nonspecific effect of SB.

Ste20-related proline/alanine-rich kinase: A novel regulator of intestinal inflammation

Recently, inflammatory bowel disease (IBD) has been the subject of considerable research, with increasing attention being paid to the loss of intestinal epithelial cell barrier function as a mechanism of pathogenesis. Ste20-related proline/alanine-rich kinase (SPAK) is involved in regulating barrier function. SPAK is known to interact with inflammation-related kinases (such as p38, JNK, NKCC1, PKCtheta;, WNK and MLCK), and with transcription factor AP-1, resulting in diverse biological phenomena, including cell differentiation, cell transformation and proliferation, cytoskeleton rearrangement, and regulation of chloride transport. This review examines the involvement of Ste20-like kinases and downstream mitogen-activated protein kinases (MAPKs) pathways in the pathogenesis and control of intestinal inflammation. The primary focus will be on the molecular features of intestinal inflammation, with an emphasis on the interaction between SPAK and other molecules, and the effect of these interactions on homeostatic maintenance, cell volume regulation and increased cell permeability in intestinal inflammation.

Increased Endothelial Mitogen-Activated Protein Kinase Phosphatase-1 Expression Suppresses Proinflammatory Activation at Sites That Are Resistant to Atherosclerosis

Atherosclerosis is a chronic inflammatory disease of arteries. It is triggered by proinflammatory mediators which induce adhesion molecules (eg, vascular cell adhesion molecule [VCAM]-1) in endothelial cells (ECs) by activating p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein (MAP) kinases by phosphorylation. Blood flow influences atherosclerosis by exerting shear stress (mechanical drag) on the inner surface of arteries, a force that alters endothelial physiology. Regions of the arterial tree exposed to high shear are protected from endothelial activation, inflammation, and atherosclerosis, whereas regions exposed to low or oscillatory shear are susceptible. We examined whether MAP kinase phosphatase (MKP)-1, a negative regulator of p38 and JNK, mediates the antiinflammatory effects of shear stress. We observed that expression of MKP-1 in cultured ECs was elevated by shear stress, whereas the expression of VCAM-1 was reduced. MKP-1 induction was shown to be necessary for the antiinflammatory effects of shear stress because gene silencing of MKP-1 restored VCAM-1 expression in sheared ECs. Immunostaining revealed that MKP-1 is preferentially expressed by ECs in a high-shear, protected region of the mouse aorta and is necessary for suppression of EC activation at this site, because p38 activation and VCAM-1 expression was enhanced by genetic deletion of MKP-1. We conclude that MKP-1 induction is required for the antiinflammatory effects of shear stress. Thus, our findings reveal a novel molecular mechanism contributing to the spatial distribution of vascular inflammation and atherosclerosis.

MAPK phosphatases as novel targets for rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) represents a challenge for therapeutic interventions due to complex inflammatory signalling pathways underlying its pathogenesis. The MAPK signalling network, a major effector limb of the inflammatory lesion, is an attractive therapeutic target. MAPK phosphatases (MKPs), endogenous negative regulators of MAPK signalling, have received increasing recognition as modulators of inflammatory and immune responses, and hence as a potential therapeutic avenue for RA.

OBJECTIVE

To present the rationale for therapeutically targeting MAPK signalling and explore the case for addressing MKP1 as a novel therapeutic strategy for RA.

METHODS

We summarise literature describing the importance of MAPK signalling in RA and review reports describing the roles of MKPs in modulating innate and adaptive immune responses. Finally we expand on the role of MKP1 in RA pathogenesis and explore data defining MKP1 as a mediator of glucocorticoid action.

CONCLUSION

MKP1 constitutes an exciting, novel potential therapeutic target for RA.

Post-transcriptional regulation of TNF-induced expression of ICAM-1 and IL-8 in human lung microvascular endothelial cells: an obligatory role for the p38 MAPK-MK2 pathway dissociated with HSP27

The tumor necrosis factor-alpha (TNF)-induced inflammatory response in human lung microvascular endothelial cells (MVECs) is an early event in acute lung injury. Studies have shown that p38 mitogen-activated protein kinase (MAPK), MAPK-activated protein kinase 2 (MK2) and heat shock protein 27 (HSP27) are involved in the expression of pro-inflammatory mediators in other cell types. However, their role in the TNF-induced inflammatory response in lung MVECs has not been determined. We evaluated the role of p38 MAPK, MK2 and HSP27 in regulating the TNF-induced expression of ICAM-1 and IL-8 in human lung MVECs. Inhibition of p38 MAPK reduced ICAM-1 and IL-8 expression without influencing NF-kappaB activation or ICAM-1 and IL-8 mRNA levels. TNF stimulation induced p38 MAPK-dependent phosphorylation of MK2 and HSP27. MK2 silencing reduced ICAM-1 and IL-8 expression without influencing NF-kappaB activation or ICAM-1 and IL-8 mRNA levels. HSP27 silencing reduced cellular HSP27 levels and HSP27 phosphorylation following TNF stimulation but had no effect on ICAM-1 and IL-8 expression. Our study demonstrates for the first time that MK2 mediates post-transcriptional regulation by p38 MAPK of the TNF-induced expression of ICAM-1 and IL-8 in human lung MVECs, and that this regulation by the p38 MAPK/MK2 pathway is dissociated from HSP27 phosphorylation.

MicroRNA-126 regulates endothelial expression of vascular cell adhesion molecule 1

Adhesion molecules expressed by activated endothelial cells play a key role in regulating leukocyte trafficking to sites of inflammation. Resting endothelial cells normally do not express adhesion molecules, but cytokines activate endothelial cells to express adhesion molecules such as vascular cell adhesion molecule 1 (VCAM-1), which mediate leukocyte adherence to endothelial cells. We now show that endothelial cells express microRNA 126 (miR-126), which inhibits VCAM-1 expression. Transfection of endothelial cells with an oligonucleotide that decreases miR-126 permits an increase in TNF-alpha-stimulated VCAM-1 expression. Conversely, overexpression of the precursor to miR-126 increases miR-126 levels and decreases VCAM-1 expression. Additionally, decreasing endogenous miR-126 levels increases leukocyte adherence to endothelial cells. These data suggest that microRNA can regulate adhesion molecule expression and may provide additional control of vascular inflammation.

Pharmacological properties of SD-282 - an alpha-isoform selective inhibitor for p38 MAP kinase

The effects of small-molecule p38 inhibitors in numerous models of different disease states have been published, including those of SD-282, an indole-5-carboxamide inhibitor. The aim of the present study was to evaluate the pharmacological activity of SD-282 on cytokine production in vitro as well as in 2 in vivo models of inflammation in order to illuminate the role of this particular inhibitor in diverse disease states. The results presented here provide further characterization of SD-282 and provide a context in which to interpret the activity of this p38 inhibitor in models of arthritis, pain, myocardial injury, sepsis and asthma; all of which have an inflammatory component. SD-282 represents a valuable tool to elucidate the role of p38 MAP kinase in multiple models of inflammation.

p38alpha stabilizes interleukin-6 mRNA via multiple AU-rich elements

AU-rich elements (AREs) in the 3'-untranslated region (UTR) of unstable mRNA dictate their degradation or mediate translational repression. Cell signaling through p38alpha MAPK is necessary for post-transcriptional regulation of many pro-inflammatory cytokines. Here, the cis-acting elements of interleukin-6 (IL-6) 3'-UTR mRNA that required p38alpha signaling for mRNA stability and translation were identified. Using mouse embryonic fibroblasts (MEFs) derived from p38alpha(+/+) and p38alpha(-/-) mice, we observed that p38alpha is obligatory for the IL-1-induced IL-6 biosynthesis. IL-6 mRNA stability is promoted by p38alpha via 3'-UTR. To understand the mechanism of cis-elements regulated by p38alpha at post-transcriptional level, truncation of 3'-UTR and the full-length 3'-UTR with individual AUUUA motif mutation placed in gene reporter system was employed. Mutation-based screen performed in p38alpha(+/+) and p38alpha(-/-) mouse embryonic fibroblast cells revealed that ARE1, ARE2, and ARE5 in IL-6 3'-UTR were targeted by p38alpha, and truncation-based screen showed that IL-6 3'-UTR-(56-173) was targeted by p38alpha to stable mRNA. RNA secondary structure analysis indicated that modulated reporter gene expression was consistent with predicted secondary structure changes.

Adenosine A2A receptor occupancy stimulates collagen expression by hepatic stellate cells via pathways involving protein kinase A, Src, and extracellular signal-regulated kinases 1/2 signaling cascade or p38 mitogen-activated protein kinase signaling pathway

Prior studies indicate that adenosine and the adenosine A2A receptor play a role in hepatic fibrosis by a mechanism that has been proposed to involve direct stimulation of hepatic stellate cells (HSCs). The objective of this study was to determine whether primary hepatic stellate cells produce collagen in response to adenosine (via activation of adenosine A2A receptors) and to further determine the signaling mechanisms involved in adenosine A2A receptor-mediated promotion of collagen production. Cultured primary HSCs increase their collagen production after stimulation of the adenosine A2A receptor in a dose-dependent fashion. Likewise, LX-2 cells, a human HSC line, increases expression of procollagen alphaI and procollagen alphaIII mRNA and their translational proteins, collagen type I and type III, in response to pharmacological stimulation of adenosine A2A receptors. Based on the use of pharmacological inhibitors of signal transduction, adenosine A2A receptor-mediated stimulation of procollagen alphaI mRNA and collagen type I collagen expression were regulated by signal transduction involving protein kinase A, src, and mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (erk), but surprisingly, adenosine A2A receptor-mediated stimulation of procollagen alphaIII mRNA and collagen type III protein expression depend on the activation of p38 mitogen-activated protein kinase (MAPK), findings confirmed by small interfering RNA-mediated knockdown of src, erk1, erk2, and p38 MAPK. These results indicate that adenosine A2A receptors signal for increased collagen production by multiple signaling pathways. These results provide strong evidence in support of the hypothesis that adenosine receptors promote hepatic fibrosis, at least in part, via direct stimulation of collagen expression and that signaling for collagen production proceeds via multiple pathways.

The p38 mitogen-activated protein kinase (MAPK) pathway in rheumatoid arthritis

Chronic inflammatory processes are based on a sustained and tightly regulated communication network among different cells types. This network comprises extracellular mediators such as cytokines, chemokines and matrix-degrading proteases, which orchestrate the participation of cells in the chronic inflammatory process. The mirrors of this outside communication world are intracellular transcription factor pathways, which shuttle information about inflammatory stimuli to the cell nucleus. This review examines the function of one key signal transduction pathway of inflammation--the p38 mitogen-activated protein kinases (p38MAPK). The signalling pathway is considered as crucial for the induction and maintenance of chronic inflammation, and its components thus emerge as interesting molecular targets of small molecule inhibitors for controlling inflammation. This review not only summarises the current knowledge of activation, regulation and function of the p38MAPK pathway but also examines the role of this pathway in clinical disease. It gives an overview of current evidence of p38MAPK activation in inflammatory arthritis and elaborates the key molecular determinants which contribute to p38MAPK activation in joint disease.

MK2 controls the level of negative feedback in the NF-kappaB pathway and is essential for vascular permeability and airway inflammation

We demonstrate that mitogen-activated protein kinase-activated kinase-2 (MK2) is essential for localized Th2-type inflammation and development of experimental asthma. MK2 deficiency does not affect systemic Th2 immunity, but reduces endothelial permeability, as well as adhesion molecule and chemokine expression. NF-kappaB regulates transcription of adhesion molecules and chemokines. We show that MK2 and its substrate HSP27 are essential for sustained NF-kappaB activation. MK2 and HSP27 prevent nuclear retention of p38 by sequestering it in the cytosol. As a result, MK2 precludes excessive phosphorylation of MSK1. By reducing MSK1 activity, MK2 prevents p65 NF-kappaB hyperphosphorylation and excessive IkappaBalpha transcription. IkappaBalpha mediates nuclear export of p65. By reducing IkappaBalpha level, MK2 prevents premature export of NF-kappaB from the nucleus. Thus, the MK2-HSP27 pathway regulates the NF-kappaB transcriptional output by switching the activation pattern from high level, but short lasting, to moderate-level, but long lasting. This pattern of activation is essential for many NF-kappaB-regulated genes and development of inflammation. Thus, the MK2-HSP27 pathway is an excellent target for therapeutic control of localized inflammatory diseases.

Soluble products from Eikenella corrodens induce cell proliferation and expression of interleukin-8 and adhesion molecules in endothelial cells via mitogen-activated protein kinase pathways

The periodontal vasculature is profoundly affected during the progression of periodontitis, and several specific bacteria are believed to be involved in this inflammatory disease. Eikenella corrodens is one of the common bacteria detected in periodontitis diseased lesions; however, the function of this organism in periodontitis is not well understood. In this study, we investigated the E. corrodens-induced endothelial cell alteration and inflammation process that leads to leukocyte infiltration in inflamed regions. Soluble products from E. corrodens (EcSP) induced the gene expression and protein production of vascular endothelial growth factor in oral epithelial cells and human umbilical vein endothelial cells (HUVEC). Direct stimulation by EcSP also activated endothelial cell proliferation. Moreover, EcSP induced ERK1/2 (p44/42) and p38 mitogen-activated protein kinase (MAPK) phosphorylation within 10-30 min in HUVEC, as demonstrated by Western blot analysis and up-regulated intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), E-selectin and interleukin-8 (IL-8) production demonstrated by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. The specific p38 MAPK inhibitor SB203580 reduced the expression of ICAM-1, VCAM-1 and IL-8, whereas the blockade of p44/42 by MAPK kinase (MEK1) inhibitor, PD98059, inhibited only IL-8 expression. Our results indicate that E. corrodens can trigger a cascade of events that induce inflammatory responses in periodontal tissue via the MAPK cascade and may promote chronic periodontitis without bacteria-cell contact.

Triglyceride-Rich Lipoproteins Prime Aortic Endothelium for an Enhanced Inflammatory Response to Tumor Necrosis Factor-α

High levels of triglyceride-rich lipoproteins (TGRLs) in blood are linked to development of atherosclerosis, yet the mechanisms by which these particles initiate inflammation of endothelium are unknown. TGRL isolated from human plasma during the postprandial state was examined for its capacity to bind to cultured human aortic endothelial cells (HAECs) and alter the acute inflammatory response to tumor necrosis factor-α. HAECs were repetitively incubated with dietary levels of freshly isolated TGRL for 2 hours per day for 1 to 3 days to mimic postprandial lipidemia. TGRL induced membrane upregulation of the low-density lipoprotein family receptors LRP and LR11, which was inhibited by the low-density lipoprotein receptor-associated protein-1. TGRLs alone did not elicit inflammation in HAECs but enhanced the inflammatory response via a 10-fold increase in sensitivity to cytokine stimulation. This was reflected by increased mitogen-activated protein kinase activation, nuclear translocation of NF-κB, amplified expression of endothelial selectin and VCAM-1, and a subsequent increase in monocyte-specific recruitment under shear flow as quantified in a microfabricated vascular mimetic device.

Chronic inhibition of p38MAPK improves cardiac and endothelial function in experimental diabetes mellitus

To investigate the influence of p38 mitogen activated kinase (p38MAPK) on the development of diabetic cardiac and endothelial dysfunction, we assessed left ventricular and vascular function as well as inflammatory markers in diabetic rats after chronic pharmacological inhibition of p38MAPK. Diabetes mellitus was induced in rats by a single injection of streptozotocin. Rats were treated with the p38MAPK inhibitor SB 239063 (40 mg/kg/day, p.o.) or vehicle. 48 days after diabetes mellitus-induction, left ventricular function and vascular function were assessed in vivo by TIP-catheter and the autoperfused hindlimb, respectively. Cell adhesion molecules staining was quantified immunohistochemically in the heart and quadriceps muscle, respectively, as well as cardiac phosphorylation of p38MAPK by Western blot analysis. Treated and untreated diabetic groups displayed similar severe hyperglycemia. Left ventricular and endothelial function were impaired in the untreated diabetic group compared to controls (dp/dtmax: -40%, dp/dtmin: +49%, maximal vasodilatation: -57%; P < 0.05) associated with significantly increased cardiac (3-fold) and peripheral cell adhesion molecules staining, respectively. Treatment of diabetic rats with SB 239063 led to a significant reduction of diabetes-induced enhancement of p38MAPK phosphorylation associated with improved left ventricular function (dp/dtmax: +39%, dp/dtmin: +47%; P < 0.05) and peripheral endothelial function (maximal vasodilatation: +71%; P < 0.05) under diabetic conditions. This was associated with reduced cardiac and peripheral inflammation indexed by reduced adhesion molecules content. Pharmacological inhibition of p38MAPK is sufficient to mitigate the development of diabetic cardiac and endothelial dysfunction despite of hyperglycemia. Our data suggest that the anti-inflammatory properties due to p38MAPK inhibition contribute to these beneficial cardiovascular effects.

Differential tissue expression and activation of p38 MAPK alpha, beta, gamma, and delta isoforms in rheumatoid arthritis

OBJECTIVE

Activation of p38 MAPK is a key signaling step in chronic inflammation. Inhibition of p38 MAPK is considered to be a promising future strategy to control inflammatory diseases, but studies of compounds to inhibit this kinase have so far been limited to investigation of their side effects. We undertook the present study to investigate which specific molecule, among 4 different isoforms of p38 MAPK (alpha, beta, gamma, and delta), is predominantly expressed and activated in inflammation. Such knowledge could allow more specific targeting of p38 MAPK in inflammatory disease.

METHODS

Studies were performed on inflamed tissue from patients with rheumatoid arthritis, as a prototype of inflammatory disease. The expression and activation of the alpha, beta, gamma, and delta isoforms of p38 MAPK were examined by immunoblotting, immunoprecipitation, and immunohistochemistry.

RESULTS

Immunoblot analysis revealed that alpha and gamma were the predominantly expressed p38 MAPK isoforms, whereas the other 2 isoforms were less frequently present. By immunohistochemistry, the expression of all p38 MAPK isoforms was localized to the synovial lining layer as well as to blood vessels. Colabeling with cell-specific markers revealed that macrophages expressed the alpha and gamma isoforms, synovial fibroblasts the beta and gamma isoforms, and granulocytes the delta isoform, whereas T lymphocytes were rarely positive for any p38 MAPK isoform. Double-labeling with isoform-specific antibody and pan-p38 antibody against the phosphorylated form of p38 MAPK showed activation of the alpha and gamma isoforms. Occasional activation of the beta isoform was also noted in the synovial lining and the endothelium, whereas the delta isoform, although expressed in pericytes around blood vessels, was not phosphorylated. This phosphorylation pattern was confirmed in immunoprecipitation studies in which activated p38 MAPK from synovial tissue extracts was identified as p38 MAPKalpha and -gamma but not p38 MAPKbeta or -delta.

CONCLUSION

These data show that the alpha and gamma isoforms of p38 MAPK dominate in chronic inflammation. Effective strategies to inhibit p38 MAPK should therefore aim to specifically target either or both of these isoforms.

Immunomodulatory effects of statins and autoimmune rheumatic diseases: novel intracellular mechanism involved

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, known as statins, are the most commonly prescribed agents for the treatment of hypercholesterolemia. However, the effects of statins may extend beyond their influences on serum cholesterol levels resulting in cholesterol-independent or pleiotropic effects. Clinical, animal and in vitro studies suggest that statins have additional clinical uses because of their anti-inflammatory and immunomodulatory effects, in part due to their capacity to interfere with the mevalonate pathway and inhibit prenylation of Rho family GTPases. This review focuses on the molecular mechanisms of the anti-inflammatory and immunomodulatory effects of statins. In base to all these information, we suggest that statins could have similar inhibitory effects on MAPKs pathways in cells from RA patients, including osteoclasts and fibroblasts.

TNF-alpha mediated suppression of tissue type plasminogen activator expression in vascular endothelial cells is NF-kappaB- and p38 MAPK-dependent

BACKGROUND

Several proatherothrombotic conditions are associated with enhanced levels of circulating proinflammatory cytokines, which are believed to impair endothelial fibrinolytic capacity.

OBJECTIVE

This study aims at investigating how tumor necrosis factor (TNF)-alpha regulates endothelial gene expression of the key fibrinolytic enzyme tissue-type plasminogen activator (t-PA).

METHODS

Cultured human umbilical vein endothelial cells were pretreated with selective inhibitors of the three major inflammatory signaling pathways activated by TNF-alpha; the nuclear factor kappa-B (NF-kappaB), the p38 mitogen-activated protein kinase (p38 MAPK), and the c-jun N-terminal kinase (JNK) pathways. Following TNF-alpha stimulation, effects on t-PA gene expression were evaluated with real-time reverse transcriptase polymerase chain reaction and interactions of nuclear proteins with potential gene regulatory elements were studied with electrophoretic mobility shift assays.

RESULTS

Approximately 50% suppression of t-PA gene expression was observed after prolonged stimulation with TNF-alpha (> or =24 h). The repression was shown to be preferentially dependent on NF-kappaB activation, but also on p38 MAPK signaling. Further, we provide evidence for a TNF-alpha induced binding of NF-kappaB to the recently described kappaB site in the t-PA gene and of cyclic adenosine monophosphate response element binding protein (CREB) to the t-PA CRE-like site.

CONCLUSIONS

We conclude that TNF-alpha impairs fibrinolytic capacity in vascular endothelial cells by a NF-kappaB and p38 MAPK-dependent suppression of t-PA. This mechanism sheds a light on how inflammation contributes to the pathogenesis of cardiovascular diseases.

Caveolin-1 is associated with VCAM-1 dependent adhesion of gastric cancer cells to endothelial cells

BACKGROUND/AIMS

Cell adhesion molecules play a critical role in the invasion and metastasis of a variety of human tumors. Abnormal expression of VCAM-1 has been demonstrated to correlate with the malignant progression of gastric tumors, but the molecular mechanism underlying the VCAM-1-dependent metastasis has been rarely investigated. To explore the role for tumor cell-expressing adhesion molecules in the carcinoma-endothelium adhesion, we analyzed expression status of adhesion molecules in gastric cancer cells and its association with tumor cell capability of endothelial adhesion.

METHODS

Endothelial adhesion ability of gastric tumor cells was tested using calcein AM staining assay. Expression of cell surface proteins was determined by Western blot, flow cytometry, and immunofluorescence assays. RNAi-mediated knockdown of gene expression and neutralization with specific antibodies were utilized for functional analysis.

RESULTS

One of three cell lines tested was identified to be adhesive to endothelial cells and express VCAM-1. Adherence ability of the cells was dramatically decreased by neutralization of surface VCAM-1. VCAM-1 was co-localized with Caveolin-1 and siRNA-mediated knockdown of Caveolin-1 expression significantly blocked the VCAM-1-dependent cell adhesion.

CONCLUSIONS

Our data imply important roles for VCAM-1 and Caveolin- 1 in the regulation of metastatic potential of gastric tumor cells.

Eicosapentaenoic acid and docosahexaenoic acid modulate mitogen-activated protein kinase activity in endothelium

Omega-3 polyunsaturated fatty acids (PUFA) regulate inflammation and immunoreaction partially via affecting endothelial functions. However, the intracellular signaling mechanisms for inhibiting endothelial activation by omega-3 PUFA remain unclear. We investigated the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on mitogen-activated protein kinases (MAPK) of endothelium. We analyzed the expression of extracellular signal-related kinases (ERK1/2), Jun amino-terminal kinases (JNK), and p38 mRNA by real-time RT-PCR and the kinases activity by western blotting in tumor necrosis factor-alpha (TNF-alpha)-activated human umbilical vein endothelial cells (HUVEC). We observed that EPA or DHA alone significantly reduced the TNF-alpha-induced activation of p38 and JNK kinases at a concentration of 20 microM, but EPA is a more potent inhibitor than DHA. In contrast, both EPA and DHA significantly counteracted the TNF-alpha-mediated deactivation of ERK1/2 kinases. Meanwhile, both EPA and DHA significantly attenuated the TNF-alpha-induced expression of p38 and ERK1/2 mRNA, and DHA but not EPA also reduced the TNF-alpha-induced JNK mRNA expression. We present data show that both EPA and DHA alone diminish activation of p38 and JNK kinases, while maintaining the activation of ERK1/2 kinases of TNF-alpha-stimulated HUVEC. This may contribute to the inhibiting effects of omega-3 PUFA on endothelial activation by proinflammatory stimuli.

Activation of Nrf2/ARE pathway protects endothelial cells from oxidant injury and inhibits inflammatory gene expression

The antioxidant response element (ARE) is a transcriptional control element that mediates expression of a set of antioxidant proteins. NF-E2-related factor 2 (Nrf2) is a transcription factor that activates ARE-containing genes. In endothelial cells, the ARE-mediated genes are upregulated by atheroprotective laminar flow through a Nrf2-dependent mechanism. We tested the hypothesis that activation of ARE-regulated genes via adenovirus-mediated expression of Nrf2 may suppress redox-sensitive inflammatory gene expression. Expression of Nrf2 in human aortic endothelial cells (HAECs) resulted in a marked increase in ARE-driven transcriptional activity and protected HAECs from H2O2-mediated cytotoxicity. Nrf2 suppressed TNF-α-induced monocyte chemoattractant protein (MCP)-1 and VCAM-1 mRNA and protein expression in a dose-dependent manner and inhibited TNF-α-induced monocytic U937 cell adhesion to HAECs. Nrf2 also inhibited IL-1β-induced MCP-1 gene expression in human mesangial cells. Expression of Nrf2 inhibited TNF-α-induced activation of p38 MAP kinase. Furthermore, expression of a constitutively active form of MKK6 (an upstream kinase for p38 MAP kinase) partially reversed Nrf2-mediated inhibition of VCAM-1 expression, suggesting that p38 MAP kinase, at least in part, mediates Nrf2's anti-inflammatory action. In contrast, Nrf2 did not inhibit TNF-α-induced NF-κB activation. These data identify the Nrf2/ARE pathway as an endogenous atheroprotective system for antioxidant protection and suppression of redox-sensitive inflammatory genes, suggesting that targeting the Nrf2/ARE pathway may represent a novel therapeutic approach for the treatment of inflammatory diseases such as atherosclerosis.

Fucoidan induces nitric oxide production via p38 mitogen-activated protein kinase and NF-kappaB-dependent signaling pathways through macrophage scavenger receptors

It has been reported that ligands of the macrophage scavenger receptor (MSR) induce a range of cellular responses including urokinase-type plasminogen activator and the production of inflammatory cytokines. Although nitric oxide (NO) is an important regulatory molecule in physiological functions such as vascular homeostasis, neurotransmission, and host defense, the effect of MSR ligands on NO production from macrophages was unknown. Here, we demonstrate that the MSR ligand, fucoidan, but neither oxidized low-density lipoprotein, acetylated LDL, maleylated bovine serum albumin nor dextran sulfate induces activation of inducible nitric oxide synthase (iNOS) promoter or NO production in RAW264.7 cells. Furthermore, we investigated the molecular mechanism by which fucoidan induces iNOS promoter activation. Using different inhibitors, we showed that the stimulation of fucoidan was mediated by both the p38 mitogen-activated protein kinase and the NF-kappaB-dependent pathways. Although these two pathways were independent, heat shock protein 90 (HSP90) played a significant role in both pathways. Our previous study showed that HSP90 directly interacts with the cytoplasmic domain of MSR. These results provide the evidence that HSP90 bound to the cytoplasmic domain of MSR is implicated in MSR-mediated signal transduction. Moreover, fucoidan-induced NO production by peritoneal macrophages from MSR-knockout (MSR-/-) mice significantly decreases compared with those from wild-type mice. This is the first indication that MSR transduces the signal of fucoidan to iNOS gene expression.

Positive correlation between sialyl Lewis X expression and pathologic findings in renal cell carcinoma

BACKGROUND

Interaction between tumor cells and endothelium plays a major role in cancer invasion and metastasis. Among various cell adhesion molecules, the cognate interaction between sialyl Lewis antigen expressed in the tumor cell surface and E-selectin expressed on endothelial cells is considered to be crucial for the tumor cell adhesion to the endothelium.

METHODS

The sialyl Lewis X (sL(X)) expression in 45 specimens from renal cell carcinoma patients was examined using immunohistochemistry.

RESULTS

In this study, we demonstrate that the immunoreactivity for sL(X) in renal cell carcinoma specimens not only correlates with conventional histopathologic parameters but also serves as a useful indicator for the prognosis of renal cell carcinoma.

CONCLUSION

Since beneficial effect of cimetidine has been reported and ascribed to its inhibitory action on the expression of E-selectin, a ligand molecule of sialyl Lewis antigen, cimetidine may also show inhibitory effect on the tumor recurrence and metastasis of renal cell carcinoma with high level of sL(X) expression.

C-reactive protein induces VCAM-1 gene expression through NF-kappaB activation in vascular endothelial cells

Recent studies have shown that C-reactive protein (CRP) is not just a predictor of cardiovascular events but also acts directly as a proinflammatory stimulus in vascular cells. In this report, we studied the molecular mechanisms underlying vascular cellular adhesion molecule-1 (VCAM-1) induction by CRP. CRP-induced VCAM-1 mRNA expression and this induction was inhibited by protein kinase C (PKC) inhibitors, p38 mitogen-activated protein kinase (MAPK) inhibitor, and tyrosine kinase inhibitors. In addition, parthenolide, a nuclear factor kappaB (NF-kappaB) inhibitor, abolished VCAM-1 induction. Moreover, CRP increased VCAM-1 promoter activity, indicating that CRP induces VCAM-1 mRNA expression at the transcriptional level. Mutation of NF-kappaB-binding sites resulted in a loss of induction. Finally, an electrophoretic mobility shift assay confirmed binding of the p65 subunit of NF-kappaB to kappaB-binding sites. Taken together, our findings suggest that VCAM-1 induction by CRP is mediated by PKC, p38MAPK, tyrosine kinase and the NF-kappaB-dependent signaling pathways in vascular endothelial cells.

Chemokine production and E-selectin expression in activated endothelial cells are inhibited by p38 MAPK (mitogen activated protein kinase) inhibitor RWJ 67657

Endothelial cells play an important role in inflammatory diseases like rheumatoid arthritis by recruitment of inflammatory cells. The cytokines TNF-alpha and IL-1beta are major inducers of endothelial cell activation and are stimulators of inflammatory signal transduction pathway involving p38 MAPK (mitogen-activated protein kinase). The present study investigated the effects of p38 MAPK inhibition on cell adhesion molecule (CAM) expression and chemokine production by endothelial cells both on mRNA and protein level. Pre-treatment of endothelial cells with the pharmacologically relevant concentration of 1 microM of the p38 MAPK inhibitor RWJ 67657 reduced TNF-alpha and IL-1beta induced mRNA and membrane expression of E-selectin. Moderate inhibitory effects on ICAM-1 and VCAM-1 expression were found. Significant reduction of mRNA expression and protein production of the inflammatory cytokine IL-6 and the chemokines IL-8 and MCP-1 was demonstrated. Treatment with RWJ 67657 could lead to reduced leukocyte infiltration by the reduction of E-selectin expression and chemokine production.

Differential effects of NF-{kappa}B and p38 MAPK inhibitors and combinations thereof on TNF-{alpha}- and IL-1{beta}-induced proinflammatory status of endothelial cells in vitro

Endothelial cells actively participate in inflammatory events by regulating leukocyte recruitment via the expression of inflammatory genes such as E-selectin, VCAM-1, ICAM-1, IL-6, IL-8, and cyclooxygenase (COX)-2. In this study we showed by real-time RT-PCR that activation of human umbilical vein endothelial cells (HUVEC) by TNF-alpha and IL-1beta differentially affected the expression of these inflammatory genes. Combined treatment with TNF-alpha and IL-1beta resulted in nonadditive, additive, and even synergistic induction of expression of VCAM-1, IL-8, and IL-6, respectively. Overexpression of dominant-negative inhibitor kappaB protein blocking NF-kappaB signaling confirmed a major role of this pathway in controlling both TNF-alpha- and IL-1beta-induced expression of most of the genes studied. Although dexamethasone exerted limited effects at 1 muM, the thioredoxin inhibitor MOL-294, which regulates the redox state of NF-kappaB, mainly inhibited adhesion molecule expression. Its most pronounced effect was seen on VCAM-1 mRNA levels, especially in IL-1beta-activated endothelium. One micromolar RWJ-67657, an inhibitor of p38 MAPK activity, diminished TNF-alpha- and IL-1beta-induced expression of IL-6, IL-8, and E-selectin but had little effect on VCAM-1 and ICAM-1. Combined treatment of HUVEC with MOL-294 and RWJ-67657 resulted in significant blocking of the expression of E-selectin, IL-6, IL-8, and COX-2. The inhibitory effects were much stronger than those observed with single drug treatment. Application of combinations of drugs that affect multiple targets in activated endothelial cells may therefore be considered as a potential new therapeutic strategy to inhibit inflammatory disease activity.

Activation and signaling of the p38 MAP kinase pathway

The family members of the mitogen-activated protein (MAP) kinases mediate a wide variety of cellular behaviors in response to extracellular stimuli. One of the four main sub-groups, the p38 group of MAP kinases, serve as a nexus for signal transduction and play a vital role in numerous biological processes. In this review, we highlight the known characteristics and components of the p38 pathway along with the mechanism and consequences of p38 activation. We focus on the role of p38 as a signal transduction mediator and examine the evidence linking p38 to inflammation, cell cycle, cell death, development, cell differentiation, senescence and tumorigenesis in specific cell types. Upstream and downstream components of p38 are described and questions remaining to be answered are posed. Finally, we propose several directions for future research on p38.

The p38 MAP kinase pathway and its biological function

p38 is a mitogen-activated protein (MAP) kinase with structural and functional characteristics that distinguish it from JNK and ERK MAP kinases. p38 activity is upregulated when cells are exposed to a variety of stimuli including bacterial pathogens, proinflammatory cytokines, certain growth factors, and other forms of environmental stress. By regulating downstream substrates that include protein kinases and transcription factors, p38 participates in transmission, amplification, and diversification of the extracellular signal, initiating several different cellular responses. Studies have revealed that activation of p38 pathway is related to many pathological changes that occur in the course of inflammatory/immunologic and cardiovascular diseases.

Superoxide Dismutase Inhibits the Expression of Vascular Cell Adhesion Molecule-1 and Intracellular Cell Adhesion Molecule-1 Induced by Tumor Necrosis Factor-α in Human Endothelial Cells Through the JNK/p38 Pathways

Objective— Expression of adhesion molecules on endothelial cells and subsequent leukocyte recruitment are critical early events in the development of atherosclerosis. We tried to study possible effects of Cu/Zn superoxide dismutase (SOD) on adhesion molecule expression and its underlying mechanism in the prevention and treatment of cardiovascular disorders.

Methods and Results— Human aortic endothelial cells (HAECs) were transfected with adenovirus carrying the human SOD gene (AdSOD) to investigate whether SOD expression in HAECs attenuated tumor necrosis factor (TNF)-α–induced reactive oxygen species production and adhesion molecule expression and to define the mechanisms involved. SOD expression significantly suppressed TNF-α–induced expression of vascular cell adhesion molecule-1 and intercellular cell adhesion molecule-1 and reduced the binding of the human neutrophils to TNF-α–stimulated HAECs. SOD expression suppressed c-JUN N-terminal kinase and p38 phosphorylation. It also attenuated intracellular superoxide anion production and NADPH oxidase activity in TNF-α–treated HAECs.

Conclusions— These results provide evidence that SOD expression in endothelial cells attenuates TNF-α–induced superoxide anion production and adhesion molecule expression, and that this protective effect is mediated by decreased JNK and p38 phosphorylation and activator protein-1 and nuclear factor κB inactivation. These results suggest that SOD has antiinflammatory properties and may play important roles in the prevention of atherosclerosis and inflammatory response.