p38 MAP kinase regulates RANTES production by TNF-alpha-stimulated human pulmonary vascular endothelial cells

Tumor Necrosis Factor-alpha utilizes MAPK/NFκB pathways to induce cholesterol-25 hydroxylase for amplifying pro-inflammatory response via 25-hydroxycholesterol-integrin-FAK pathway

Exaggerated inflammatory response results in pathogenesis of various inflammatory diseases. Tumor Necrosis Factor-alpha (TNF) is a multi-functional pro-inflammatory cytokine regulating a wide spectrum of physiological, biological, and cellular processes. TNF induces Focal Adhesion Kinase (FAK) for various activities including induction of pro-inflammatory response. The mechanism of FAK activation by TNF is unknown and the involvement of cell surface integrins in modulating TNF response has not been determined. In the current study, we have identified an oxysterol 25-hydroxycholesterol (25HC) as a soluble extracellular lipid amplifying TNF mediated innate immune pro-inflammatory response. Our results demonstrated that 25HC-integrin-FAK pathway amplifies and optimizes TNF-mediated pro-inflammatory response. 25HC generating enzyme cholesterol 25-hydroxylase (C25H) was induced by TNF via NFκB and MAPK pathways. Specifically, chromatin immunoprecipitation assay identified binding of AP-1 (Activator Protein-1) transcription factor ATF2 (Activating Transcription Factor 2) to the C25H promoter following TNF stimulation. Furthermore, loss of C25H, FAK and α5 integrin expression and inhibition of FAK and α5β1 integrin with inhibitor and blocking antibody, respectively, led to diminished TNF-mediated pro-inflammatory response. Thus, our studies show extracellular 25HC linking TNF pathway with integrin-FAK signaling for optimal pro-inflammatory activity and MAPK/NFκB-C25H-25HC-integrin-FAK signaling network playing an essential role to amplify TNF dependent pro-inflammatory response. Thus, we have identified 25HC as the key factor involved in FAK activation during TNF mediated response and further demonstrated a role of cell surface integrins in positively regulating TNF dependent pro-inflammatory response.

Hyperosmolarity-induced dilation and epithelial bioelectric responses of guinea pig trachea in vitro: role of kinase signaling

Exercise-induced airway obstruction is thought to involve evaporative water loss and hyperosmolarity of the airway surface liquid. Hyperosmolar challenge of the epithelium of isolated, perfused guinea pig trachea rapidly alters transepithelial potential difference (V(t)), and it elicits smooth muscle relaxation mediated by epithelium-derived relaxing factor (EpDRF). In many cell types, protein kinases mediate responses to hyperosmolarity and regulatory volume increase. In this study, inhibitors were used to investigate the involvement of kinases and phosphatases in bioelectric responses of epithelium to hyperosmolarity and their possible relationship to EpDRF-mediated relaxation. After contraction of the perfused trachea with extraluminal methacholine, D-mannitol applied intraluminally (< or = 80 mosM) increased V(t) and elicited dilation of the smooth muscle with a similar concentration-dependence; higher concentrations decreased V(t). In tracheas exposed to 30 mosM D-mannitol (approximately EC(50)), 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB 203580) and SKF 86002 [6-(4-fluorophenyl)-2,3-dihydro-5-(4-pyridyl)imidazo[2,1-b]thiazole] (p38 inhibitors) potentiated the dilation, whereas SP 600125 [anthra[1,9-cd]pyrazol-6(2H)-one-1,9-pyrazoloanthrone] and dicumarol [c-Jun NH(2)-terminal kinase (JNK) inhibitors], chelerythrine [nonselective protein kinase C (PKC) inhibitor], and NaAsO(2) (mitogen-activated protein kinase stress inducer) and Na(3)VO(4) (protein tyrosine phosphatase inhibitor) inhibited the hyperpolarization. Large increases in the phosphorylation of p38 and JNK occurred at concentrations higher than those needed to elicit functional responses. The phosphatidylinositol 3-kinase inhibitor 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY 294002) and Na(3)VO(4) did not affect the V(t) responses, but they inhibited methacholine-induced constriction; SP 600125 and dicumarol potentiated, and chelerythrine inhibited, methacholine-induced epithelial hyperpolarization. These results suggest that JNK, PKC, and phosphatase(s) are involved in hyperosmolarity-induced hyperpolarization of the tracheal epithelium but that p38 is involved in EpDRF-mediated relaxation.

The role of chemokines as inflammatory mediators in chronic hepatitis C virus infection

Hepatitis C virus (HCV) is a leading cause of chronic liver disease that can progress to cirrhosis and/or hepatocellular carcinoma. Intrahepatic inflammation and liver cell injury are defining features of chronic HCV infection. Chemokines, chemotactic cytokines that attract leucocytes to inflammatory sites, may be important in the development of intrahepatic inflammation. As T-helper (Th)1 inflammatory cells, characterized by interferon (IFN)-gamma and interleukin (IL)-2 secretion, predominate in the liver during chronic HCV infection, chemokines that attract these cells might be particularly important in disease progression. In this review, we focus on the role of Th1 chemokines, which are all members of the CXC or CC subfamilies. Among the CXC chemokines, the non-ELR group comprised of IFN-gamma-inducible protein 10 (IP-10), monokine induced by IFN-gamma (Mig) and IFN-inducible T-cell-alpha chemoattractant (I-TAC), attract Th1 cells through the interaction with their receptor, CXCR3. Among the CC subfamily, Th1-associated chemokines include regulated upon activation, normal T-cell expressed and secreted (RANTES) and macrophage inflammatory proteins (MIP)1alpha and beta. These chemokines attract cells through an interaction with their receptor, CCR5. While peripheral blood and intrahepatic levels of all of these chemokines are elevated in chronic hepatitis C patients, only select chemokines have been found to be correlated with hepatic inflammation. Among the six chemokines, IP-10 has uniquely been shown to have prognostic utility as a marker of treatment outcome. In the future, chemokines might be used to monitor the natural course and progression of HCV-associated liver disease, to identify patients with a high likelihood of achieving a therapeutic response, and they may even have potential as therapeutic targets.

Tumor necrosis factor alpha (TNF-alpha)-induced RANTES chemokine expression via activation of NF-kappaB and p38 MAP kinase: roles of TNF-alpha in alcoholic liver diseases

BACKGROUND/AIMS

Increased concentration of plasma tumor necrosis factor alpha (TNF-alpha) correlates with the clinical course of alcoholic liver diseases. In addition, hepatic RANTES which migrates CD4 T lymphocytes to liver is increased in patients with alcoholic hepatitis. We investigated that roles of TNF-alpha on RANTES expression in hepatocytes.

METHODS

HLE cells were treated with TNF-alpha in the presence, or absence of several inhibitors. Enzyme-linked immunoassay and reverse transcriptase-polymerase chain reaction were performed for the measurement of protein production and mRNA of RANTES, respectively. Moreover, DNA-binding activity of NF-kappaB was investigated using electrophoretic mobility shift assay. To examine effects of TNF-alpha on RANTES gene expression, luciferase assay was performed.

RESULTS

TNF-alpha clearly up-regulated RANTES expression in a time-dependent fashion and induced DNA-binding activity of NF-kappaB. Moreover, TNF-alpha-induced RANTES expression was completely inhibited by SB203580, but not calphostin C and wortmannin. Luciferase assay showed that TNF-alpha increased RANTES gene expression and mutation of NF-kappaB binding sites in the RANTES promoter ablated TNF-alpha inducibility.

CONCLUSIONS

We showed that RANTES was transcriptionally induced in human hepatoma cells by treatment with TNF-alpha via activation of NF-kappaB and p38 MAP kinase, presumably suggesting that TNF-alpha-induced expression of RANTES plays important roles in cell-mediated liver injury in alcoholic liver diseases.

Inhibition of TNF-alpha-induced RANTES expression in human hepatocyte-derived cells by fibrates, the hypolipidemic drugs

Increased concentrations and activity of plasma cytokines produced by monocytes, macrophages, and hepatocytes in patients with alcoholic liver diseases, correlate with the clinical course of liver diseases and are of prognostic value. Especially, high levels of circulating tumor necrosis factor (TNF)-alpha have been found to correlate with increased mortality in alcoholic hepatitis. Moreover, hepatic RANTES was increased in patients with alcoholic hepatitis. Thus, TNF-alpha-induced RANTES expression may have a critical role in cell-mediated liver injury associated with alcoholic hepatitis. Fibrates are widely used in the treatment of hyperlipidemia and lower triglyceride levels in patients with hyperlipidemia. Recently, several groups reported that bezafibrate, one of fibrates, is effective in primary biliary cirrhosis treatment. Additionally, it is reported that bezafibrate is effective in the treatment not only of primary biliary cirrhosis but also of chronic hepatitis C and tamoxifen-induced non-alcoholic steatohepatitis. We, here, presented that bezafibrate and fenofibrate repressed TNF-alpha-induced protein production and mRNA expression of RANTES in human hepatocyte-derived cells. Luciferase assay showed that bezafibrate and fenofibrate inhibited RANTES gene expression in response to TNF-alpha. Moreover, bezafibrate repressed TNF-alpha-induced DNA-binding activity of NF-kappaB. Thus, fibrates reduced TNF-alpha-induced NF-kappaB activation and RANTES expression, possibly suggesting that fibrates might be inhibitory agents of migration of inflammatory cells by RANTES to the liver in patients with alcoholic liver diseases. In line of these results, it might be possible that fibrates are therapeutic agents in alcoholic liver diseases.

Soluble donor HLA class I and beta 2m-free heavy chain in serum of lung transplant recipients: steady-state levels and increases in patients with recurrent CMV infection, acute rejection episodes, and poor outcome

We determined the concentration of donor sHLA/beta(2)m and total beta(2)m-free heavy chain (HC) in the serum of lung transplant recipients with ELISA assays. While we were unable to detect specific donor beta(2)m-free HCs due to a lack of available antibodies, we could determine if events that led to an increase in the release of beta(2)m-free HC also led to an increase in the release of donor sHLA/beta(2)m, particularly the 36 kDa, proteolytically cleaved form. We found that lung transplants constituitively release donor sHLA/beta(2)m at ng/ml levels. The levels (both of donor sHLA/beta(2)m and total beta(2)m-free HC) were significantly increased in CMV-sero-negative recipients (but not in CMV-sero-positive recipients) at the onset of post-transplant CMV disease. Acute rejection episodes were also associated with an increased release of donor sHLA/beta(2)m, but not of beta(2)m-free HC. However, in patients with particularly poor outcome (i.e., graft loss within 1 year) there was a significant release of beta(2)m-free HC. Analysis of one such patient showed a predominance of 36 kDa forms of donor-sHLA/beta(2)m. Our data are consistent with the hypothesis that the metalloproteinase that cleaves beta(2)m-free HC is active during uncontrolled CMV infection and acute rejection. However, recall responses to CMV and controlled immune responses to donor may result in little or no activation of sHLA class I release.

Regulation by intracellular glutathione of TNF-alpha-induced p38 MAP kinase activation and RANTES production by human pulmonary vascular endothelial cells

BACKGROUND

We have previously shown that p38 mitogen-activated protein (MAP) kinase regulates tumor necrosis factor-alpha (TNF-alpha)-induced RANTES production by human pulmonary vascular endothelial cells, and that sensitivity to TNF-alpha is inversely correlated with cellular reduction and oxidation (redox) state. However, a regulatory role of intracellular glutathione (GSH) in TNF-alpha-induced p38 MAP kinase activation and p38 MAP kinase-mediated RANTES production has not been determined. In the present study, therefore, we extended our previous studies and focused on redox regulation on p38 MAP kinase activation.

METHODS

Human pulmonary vascular endothelial cells were exposed to N-acetylcysteine (NAC) or buthionine sulfoximine (BSO), and then TNF-alpha-induced p38 MAP kinase activation and p38 MAP kinase-mediated RANTES production were determined.

RESULTS

The results showed that 1) NAC attenuated TNF-alpha-induced p38MAP kinase activation and RANTES production 2) SB 203580 as the specific inhibitor of p38 MAP kinase activity attenuated TNF-alpha-induced RANTES production 3) BSO facilitated TNF-alpha-induced p38 MAP kinase activation and RANTES production 4) SB 203580 attenuated BSO-mediated facilitation of TNF-alpha-induced RANTES production.

CONCLUSIONS

These results indicated that TNF-alpha-induced p38 MAP kinase activation and p38 MAP kinase-mediated RANTES production by human pulmonary vascular endothelial cells are inversely regulated by intracellular GSH levels.