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IL-6 Secretion (il-6 + secretion)
Selected AbstractsHaemodialysis induces mitochondrial dysfunction and apoptosisEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 12 2007D. S. C. Raj Abstract Background Mitochondria play a crucial role in the regulation of the endogenous pathways of apoptosis activated by oxidant stress. Nuclear factor-,B (NF-,B) is a central integration site for pro-inflammatory signals and oxidative stress. Materials and methods Peripheral blood mononuclear cells (PBMC) were isolated from eight end-stage renal disease (ESRD) patients before haemodialysis (Pre-HD) and during the last 10 min of HD (End-HD). A new polysulfone membrane (F70, Fresenius) was used for dialysis. Intracellular generation of reactive oxygen species (ROS), mitochondrial redox potential (,,m) and PBMC apoptosis were determined by flow-cytometry. Results Plasma levels of interleukin-6 (IL-6) (24·9 ± 7·0 vs. 17·4 ± 5·5 pg dL,1, P < 0·05), IL-6 soluble receptor (52·2 ± 4·9 vs. 37·6 ± 3·2 ng dL,1, P < 0·02) and IL-6 gp130 (405·7 ± 41·0 vs. 235·1 ± 38·4 ng dL,1, P < 0·02) were higher end-HD compared to pre-HD. IL-6 secretion by the isolated PBMC (24·0 ± 2·3 vs. 19·3 ± 3·5 pg dL,1, P < 0·02) increased end-HD. Percentage of lymphocytes exhibiting collapse of mitochondrial membrane potential (43·4 ± 4·6% vs. 32·6 ± 2·9%, P < 0·01), apoptosis (33·4 ± 7·1% vs. 23·7 ± 7·7%, P < 0·01), and generation of superoxide (20·7 ± 5·2% vs. 12·5 ± 2·9%, P < 0·02) and hydrogen peroxide (51·1 ± 7·8% vs.38·2 ± 5·9%, P < 0·04) were higher at end-HD than pre-HD. NF-,B activation (3144·1 ± 208·1 vs. 2033·4 ± 454·6 pg well,1, P < 0·02), expression of B-cell lymphoma protein-2 (6494·6 ± 1461 vs. 3501·5 ± 796·5 ng mL,1, P < 0·03) and heat shock protein-70 (9·81 ± 1·47 vs. 6·38 ± 1·0 ng mL,1, P < 0·05) increased during HD. Conclusions Intra-dialytic activation of cytokines, together with impaired mitochondrial function, promotes generation of ROS culminating in augmented PBMC apoptosis. There is concomitant activation of pathways aimed at attenuation of cell stress and apoptosis during HD. [source] Histamine induces Toll-like receptor 2 and 4 expression in endothelial cells and enhances sensitivity to Gram-positive and Gram-negative bacterial cell wall componentsIMMUNOLOGY, Issue 2 2004Jaya Talreja Summary Histamine is a major inflammatory molecule released from the mast cell, and is known to activate endothelial cells. However, its ability to modulate endothelial responses to bacterial products has not been evaluated. In this study we determined the ability of histamine to modulate inflammatory responses of endothelial cells to Gram-negative and Gram-positive bacterial cell wall components and assessed the role of Toll-like receptors (TLR) 2 and 4 in the co-operation between histamine and bacterial pathogens. Human umbilical vein endothelial cells (HUVEC) were incubated with lipopolysaccharide (LPS), lipoteichoic acid (LTA), or peptidoglycan (PGN) in the presence or absence of histamine, and the expression and release of interleukin-6 (IL-6), and NF-,B translocation were determined. The effect of histamine on the expression of mRNA and proteins for TLR2 and TLR4 was also evaluated. Incubation of HUVEC with LPS, LTA and PGN resulted in marked enhancement of IL-6 mRNA expression and IL-6 secretion. Histamine alone markedly enhanced IL-6 mRNA expression in HUVEC, but it did not stimulate proportional IL-6 release. When HUVEC were incubated with LPS, LTA, or PGN in the presence of histamine marked amplification of both IL-6 production and mRNA expression was noted. HUVEC constitutively expressed TLR2 and TLR4 mRNA and proteins, and these were further enhanced by histamine. The expression of mRNAs encoding MD-2 and MyD88, the accessory molecules associated with TLR signalling, were unchanged by histamine treatment. These results demonstrate that histamine up-regulates the expression of TLR2 and TLR4 and amplifies endothelial cell inflammatory responses to Gram-negative and Gram-positive bacterial components. [source] Regulation of epithelial cell cytokine responses by the ,3,1 integrinIMMUNOLOGY, Issue 2 2003Farah D. Lubin Summary Epithelial cells (EC) from various tissues can produce important cytokines and chemokines when stimulated by proinflammatory cytokines. These EC also receive signals from cell surface integrins, like the ,3,1 integrin, which is important in cell migration and wound healing of epithelial monolayers. However, little is known of the effect of integrin signals on cytokine responses by EC. Colonic Caco-2 cells treated with an anti-,3 integrin antibody prior to stimulation with the proinflammatory cytokine interleukin (IL)-1 yielded suppressed levels of mRNA and secreted IL-6, IL-8 and monocyte chemoattractant protein-1 as compared to cells treated with normal mouse immunoglobulin G. Lung A549 cells also showed a similar suppression of cytokine secretion. Likewise, treatment of the Caco-2 cells with the same antibody suppressed tumour necrosis factor-,-stimulated IL-6 secretion. Fab fragments of the anti-,3 integrin antibody did not induce the suppressive effect but did block the suppressive effect of the whole antibody suggesting that the effect of the antibody required cross-linking of the integrins. Finally, culture of the Caco-2 cells on laminin type 5 (the major ligand for this integrin) yielded depressed levels of IL-1-induced IL-6 secretion as compared to cells on laminin type 1. These data are the first indication that the ,3,1 integrin may cause a suppression of cytokine responses by EC which may be important in regulating the capacity of EC to respond during inflammation or wound healing. [source] Effect of endotoxin pretreatment on hepatic stellate cell response to ethanol and acetaldehydeJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 11 2001Silvia C Quiroz Abstract Background and Aim: The role of endotoxin in alcohol-induced liver damage is well recognized. How pre-exposure to endotoxin might affect alcohol injury is not known. We herein studied the effect of endotoxin pretreatment on hepatic stellate cell (HSC) response to ethanol and acetaldehyde. Methods: Rat HSC (CFSC-2G) were exposed to media supplemented with 1 ,g/mL lipopolysaccharide (LPS). This was followed by a 24 h exposure to media containing LPS plus 50 mmol/L ethanol or 175 ,mol/L acetaldehyde. Lipid peroxidation, collagen, and tumor necrosis factor (TNF)-,, interleukin (IL)-1,, IL-6 and transforming growth factor (TGF)-,1 secretion were determined at the end of both periods of exposure. Results: Lipopolysaccharide pretreatment did not modify lipid peroxidation induced by ethanol or acetaldehyde alone. Glutathione (GSH) content decreased to 4.2 ± 0.5 and 16.3 ± 0.8 nmol protein after exposure to ethanol or acetaldehyde alone, and decreased further with LPS pretreatment (2.4 ± 0.2 and 2.7 ± 0.3 nmol/mg protein, respectively). Oxidized GSH (GSSG) content increased in ethanol and acetaldehyde LPS-pretreated cells only. Collagen secretion increased to 988 ± 82 and 1169 ± 91 ,g/106 cells after exposure to acetaldehyde or LPS alone. Lipopolysaccharide pretreatment enhanced collagen secretion significantly in both ethanol- and acetaldehyde-treated cells (969 ± 56 and 1360 ± 72 ,g/106 cells, respectively). Interleukin-6 production increased to 288 ± 48, 1195 ± 86 and 247 ± 35 pg/mL per 106 cells after ethanol, acetaldehyde and LPS exposure, and increased further with LPS pretreatment in ethanol-exposed cells (680 ± 23 pg/mL 106 cells). Conclusion: Lipopolysaccharide pretreatment of HSC adds to the damage produced by ethanol and acetaldehyde by diminishing GSH content and increasing GSSG content, collagen and IL-6 secretion. [source] Neuropeptide Y Cotransmission with Norepinephrine in the Sympathetic Nerve,Macrophage InterplayJOURNAL OF NEUROCHEMISTRY, Issue 6 2000Rainer H. Straub Abstract: The CNS modulates immune cells by direct synaptic-likecontacts in the brain and at peripheral sites, such as lymphoid organs. Tostudy the nerve-macrophage communication, a superfusion method was used toinvestigate cotransmission of neuropeptide Y (NPY) with norepinephrine (NE),with interleukin (IL)-6 secretion used as the macrophage read-out parameter.Spleen tissue slices spontaneously released NE, NPY, and IL-6 leading to asuperfusate concentration at 3-4 h of 1 nM, 10 pM, and 120pg/ml, respectively. Under these conditions, NPY dose-dependently inhibitedIL-6 secretion with a maximum effect at 10 -10M(p = 0.012) and 10 -9M (p < 0.001).Simultaneous addition of NPY at 10 -9M and the,-2-adrenergic agonist p -aminoclonidine further inhibited IL-6secretion (p < 0.05). However, simultaneous administration of NPYat 10 -9M and the ,-adrenergic agonist isoproterenolat 10 -6M or NE at 10 -6Msignificantly increased IL-6 secretion (p < 0.005). To objectifythese differential effects of NPY, electrical field stimulation of spleenslices was applied to release endogenous NPY and NE. Electrical fieldstimulation markedly reduced IL-6 secretion, which was attenuated by the NPYY1 receptor antagonist BIBP 3226 (10 -7M, p = 0.039;10 -8M, p = 0.035). This indicates that NPY increases theinhibitory effect of endogenous NE, which is mediated at low NE concentrationsvia ,-adrenoceptors. Blockade of ,-adrenoceptors attenuatedelectrically induced inhibition of IL-6 secretion (p < 0.001),which was dose-dependently abrogated by BIBP 3226. This indicates that underblockade of ,-adrenoceptors endogenous NPY supports the stimulatingeffect of endogenous NE via ,-adrenoceptors. These experimentsdemonstrate the ambiguity of NPY, which functions as a cotransmitter of NE inthe nerve-macrophage interplay. [source] Effects of statins on microgliaJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2005Catharina Lindberg Abstract High serum cholesterol level has been shown as one of the risk factors for Alzheimer's disease (AD), and epidemiological studies indicate that treatment with cholesterol-lowering substances, statins, may provide protection against AD. An acute-phase reaction and inflammation, with increased levels of proinflammatory cytokines, are well known in the AD brain. Notably, there is evidence for antiinflammatory activities of statins, such as reduction in proinflammatory cytokines. Consequently, it is of interest to analyze the effects of statins on microglia, the main source of inflammatory factors in the brain, such as in AD. The aims of this study were to determine the effects of statins (atorvastatin and simvastatin) on microglial cells with regard to the secretion of the inflammatory cytokine interleukin-6 (IL-6) and cell viability after activation of the cells with bacterial lipopolysaccharides (LPS) or ,-amyloid1,40 (A,1,40) and in unstimulated cells. Cells of the human microglial cell line CHME-3 and primary cultures of rat neonatal cortical microglia were used. Incubation with LPS or A,1,40 induced secretion of IL-6, and A,1,40, but not LPS, reduced cell viability. Both atorvastatin and simvastatin reduced the basal secretion of IL-6 and the cell viability of the microglia, but only atorvastatin reduced LPS- and A,1,40 -induced IL-6 secretion. Both statins potentiated the A,1,40 -induced reduction in cell viability. The data indicate the importance of also considering the microglial responses to statins in evaluation of their effects in AD and other neurodegenerative disorders with an inflammatory component. © 2005 Wiley-Liss, Inc. [source] Inhibitory effect of pooled human immunoglobulin on cytokine production in peripheral blood mononuclear cellsPEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 1 2006Kuan-Hsun Wu Human intravenous immunoglobulins (IVIG) are widely used as immunomodulators because of their ability to modify the course of various immune-mediated diseases. We investigated the mechanisms responsible for the regulatory effects of IVIG on in vitro human peripheral blood mononuclear cell (PBMC) cytokine production. Pre-incubation of PBMCs with IVIG inhibited lipopolysaccharide (LPS) and phorbol 12-myristate 13-acetate (PMA)/ionomycin stimulated cytokine secretion. Pre-incubation of PBMCs with IVIG induced a significant inhibition of LPS-stimulated (IL-6) secretion (p = 0.045); the effect on tumor necrosis factor- , (TNF- ,) secretion was not significant (p = 0.234). Pre-incubation of PBMCs with IVIG inhibited IL-6 secretion (p = 0.033) stimulated with anti-CD14 antibody cross-linking but had no significant effect on TNF- , secretion (p = 0.125). PBMC pre-incubation with anti-CD14-blocking antibody induced a significant reduction (p = 0.042) in LPS-stimulated TNF- , secretion in comparison with a non-significant reduction (p =0.256) noted with IVIG pre-treatment. In contrast, pre-incubation of PBMCs with anti-CD14 antibody did not induce a significant reduction in LPS-stimulated IL-6 secretion (p = 0.166) in comparison with a significant reduction (p = 0.001) induced with IVIG pre-treatment. Our data suggest that the immunoregulatory properties of IVIG may rely on several mechanisms, some of which may be independent of CD14. Our data also showed that cross-linking cell membrane-bound IVIG with anti-human kappa- and lambda-chain antibodies resulted in cytokine secretion levels similar to those elicited by LPS. In addition, intracellular DNA staining results did not support the involvement of apoptosis in the regulatory mechanisms of IVIG. This data may further our understanding of the immunoregulatory effects exerted by IVIG on the production of inflammatory-response mediators. [source] Ergocalciferol promotes in vivo differentiation of keratinocytes and reduces photodamage caused by ultraviolet irradiation in hairless micePHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2004Hiroaki Mitani Background: Ergocalciferol (VD2) is usually administered orally and it is metabolized to produce its biologically active metabolites in the liver and kidney. Active vitamin D is a well-known potent regulator of cell growth and differentiation. Purpose: Active vitamin D such as 1,25-dihydroxyvitamin D3 (1,,25(OH)2D3) prevents photodamage, including wrinkles and morphologic alterations. However, its clinical and cosmetic use is limited because of its potent, associated effect on calcium metabolism. We examined the efficacy of vitamin D analogues with few adverse effects for preventing skin photodamage. Method: Topical application of VD2 to hairless mouse dorsal skin, and exposure to solar-simulating ultraviolet (UV) radiation at a dose of 10.8 J/cm2 (UVA) were performed for 15 weeks, five times a week on weekdays. At the end of the final irradiation, histological and analytical studies were performed. Results: Topical application of VD2 significantly prevented wrinkle formation and abnormal accumulation of extracellular matrix components. In addition, VD2 suppressed excessive secretion of IL-6 induced by UV irradiation in cultured human normal keratinocytes, in a dose-dependent manner. Conclusion: VD2 promoted keratinocytes differentiation in the epidermis and showed diverse physiological effects, the same as the active form of VD3. The results suggested that the suppression of skin photodamage involved the promotion of keratinocytes differentiation and suppression of IL-6 secretion induced by exposure to UV. Topical application of VD2 may become an effective means to suppress solar UV-induced human skin damage. [source] The role of autocrine TGF,1 in endothelial cell activation induced by phagocytosis of necrotic trophoblasts: a possible role in the pathogenesis of pre-eclampsia,THE JOURNAL OF PATHOLOGY, Issue 1 2010Qi Chen Abstract Pre-eclampsia is a disorder of pregnancy characterized by hypertension and endothelial cell dysfunction. The causes of pre-eclampsia are unclear but it is proposed that a factor released from the placenta triggers the maternal symptoms. One possible triggering factor is dead trophoblasts that are shed from the placenta, then deported to become trapped in the maternal pulmonary capillaries. It is hypothesized that trophoblasts die by apoptosis in normal pregnancy, but by necrosis in pre-eclampsia. Deported trophoblasts may be phagocytosed by the pulmonary endothelial cells and we have previously shown that phagocytosis of necrotic trophoblasts leads to the activation of endothelial cells, accompanied by the release of interleukin-6 from these cells. However, the mechanistic pathway linking phagocytosis of necrotic trophoblasts and endothelial cell activation is unknown. Here we show that, after phagocytosis of necrotic, but not apoptotic, trophoblasts, endothelial cells secrete TGF,1. Using recombinant endoglin to inhibit the function of TGF,1 we have shown that the TGF,1 does not directly activate endothelial cells but rather it induces endothelial IL-6 secretion. The IL-6 then induces endothelial cell activation. Inhibiting either TGF,1 or IL-6 prevented endothelial cell activation in response to phagocytosing necrotic trophoblasts, but inhibiting IL-6 did not prevent secretion of TGF,1, confirming the order of signalling. IL-6 also reduced endothelial cell-surface endoglin but increased the amount of soluble endoglin released from placental explants. These interactions between the IL-6 and TGF,1 pathways in both the endothelium and placenta may help to regulate the maternal response to deported trophoblasts in pregnancy. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] ORIGINAL ARTICLE: Antiphospholipid Antibodies Limit Trophoblast Migration by Reducing IL-6 Production and STAT3 ActivityAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 5 2010Melissa J. Mulla Citation Mulla MJ, Myrtolli K, Brosens JJ, Chamley LW, Kwak-Kim JY, Paidas MJ, Abrahams VM. Antiphospholipid antibodies limit trophoblast migration by reducing IL-6 production and STAT3 activity. Am J Reprod Immunol 2010 Problem Women with antiphospholipid antibodies (aPL) are at risk of recurrent miscarriage and pre-eclampsia. aPL target the placenta by binding to ,2 -glycoprotein I (,2 GPI) expressed by the trophoblast. The objective of this study was to evaluate if and how aPL affect first trimester trophoblast migration. Method of study First trimester trophoblast cells were treated with anti-,2 GPI monoclonal antibodies. Migration was determined using a two-chamber assay. Interleukin (IL)-6 production was evaluated by RT-PCR and enzyme-linked immunosorbent assay, and signal transducer and activator of transcription 3 (STAT3) activation was assessed by western blot. Results Trophoblast cells constitutively secreted IL-6 in a time-dependent manner and this directly correlated with STAT3 phosphorylation. In the presence of anti-,2 GPI Abs, trophoblast IL-6 mRNA levels and secretion was downregulated in a Toll-like receptor 4/MyD88-independent manner and this correlated with a reduction in phosphorylated STAT3 levels. In addition, the anti-,2 GPI Abs reduced the migratory potential of trophoblast. Heparin was able to reverse aPL-dependent inhibition of trophoblast IL-6 secretion and migration. Conclusion This study demonstrates that aPL limit trophoblast cell migration by downregulating trophoblast IL-6 secretion and STAT3 activity. As heparin was unable to prevent these effects, our findings may explain why women with antiphospholipid syndrome, treated with heparin, remain at risk of developing obstetrical syndromes, associated with impaired deep placentation, such as pre-eclampsia. [source] ORIGINAL ARTICLE: Effects of Cyclic Versus Sustained Estrogen Administration on Peripheral Immune Functions in Ovariectomized MiceAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 4 2010Jing Li Citation Li J, McMurray RW. Effects of cyclic versus sustained estrogen administration on peripheral immune functions in ovariectomized mice. Am J Reprod Immunol 2010; 63: 274,281 Problem, Estrogens have multiple influences on immune functions. We aimed to compare the effects of cyclic versus sustained estrogen treatments under the same accumulated dose on peripheral immune functions in ovariectomized mice. Method of study, Ovariectomized adult Balb/c mice were treated with estradiol (E2) by s.c. injection once every 4 days (total 44.8 ,g) or by pellet implantation (total 44.2 ,g). After 6 weeks of treatment, all animals were immunized with DNP-KLH. Peripheral immune functions were assessed 10 days later. Results, Both cyclic and sustained E2 treatments significantly reduced the percentage of splenic B220+sIgM+ cells, enhanced IFN-, production and suppressed IL-6 secretion from Con A-stimulated splenocytes, and increased serum anti-DNP antibody levels. No differences were found in the above responses or in uterine weight gain between the two regimens of E2 administration. Conclusion, There are no differential effects on peripheral immune functions between cyclic and sustained estrogen administration under the same total dose. [source] Glucocorticoids Inhibit Diastrophic Dysplasia Sulfate Transporter Activity in Otosclerosis by Interleukin-6THE LARYNGOSCOPE, Issue 9 2006Yutaka Imauchi MD Abstract Hypothesis/Objective: Otosclerosis is a bone remodeling disorder localized to the otic capsule and associated with inflammation. In vitro, increased activity of the diastrophic dysplasia sulf/te transporter (DTDST), which is implicated in bone metabolism, has been reported. Because glucocorticoids modulate the bone turnover and inhibit inflammatory processes, we investigated the effect of dexamethasone (Dex) on interleukin-6 and DTDST in otosclerosis. Study Design: The authors conducted a prospective, case,control study. Materials and Methods: Primary cell cultures were obtained from stapes and external auditory canals in otosclerosis (n = 21) and control patients (n = 18). Assays with [3H]Dex evaluated specific binding sites in otosclerotic and control stapes. The effects of Dex (10,9 to 10,6 M) and RU486 (10,7 M), a glucocorticoid antagonist, were studied on DTDST activity by sulfate uptake. IL-6 secretion was measured in culture media before and after Dex (10,7 M, 24 hours). The effect of IL-6 (10,7 M, 24 hours) was assessed on DTDST activity in control stapes. Results: The number of specific Dex-binding sites was similar in all stapedial cultures. Dex inhibited DTDST activity (19.4 ± 1.02 vs. 29.4 ± 3.94 pmol/,g prot/5 minutes) only in otosclerotic stapes. This effect was dose-dependent, antagonized by RU 486 and only observed 24 hours after Dex exposure. Interleukin (IL)-6 stimulated DTDST activity in normal stapes, whereas Dex inhibited IL-6 production only in otosclerotic stapes. Conclusion: Dex inhibits the DTDST activity, at least in part, through a reduction of IL-6 secretion only in otosclerotic cells. This effect is mediated through the glucocorticoid receptors and may lead to the reduction of bone turnover. [source] Over-expression of I,B-kinase-, (IKK,/IKKi) induces secretion of inflammatory cytokines in prostate cancer cell linesTHE PROSTATE, Issue 7 2009Benjamin Péant Abstract BACKGROUND Elevated inflammatory cytokine levels in serum have been associated with advanced stage metastasis-related morbidity in prostate cancer. Several studies have shown that IL-6 and IL-8 can accelerate the growth of human prostate cancer cell lines. Previous studies, in murine embryonic fibroblasts, have shown that I,-B kinase-epsilon (IKK,/IKKi)-deficiency results in the reduction of lipopolysaccharide-mediated expression of IL-6. RESULTS In this study, we report that over-expression of IKK, in hormone-sensitive 22Rv1 and LNCaP prostate cancer cells induces the secretion of several inflammatory cytokines including IL-6 and IL-8. Both of these cytokines are secreted by hormone-refractory PC-3 prostate cancer cells and IKK, knock-down in these cells correlates with a strong decrease in IL-6 secretion. Furthermore, we demonstrate that IKK, over-expression does not induce the activation of the IKK, classical targets NF-,B and IRF-3, two transcription factors involved in the regulation of several cytokines. Finally, we observe that high IKK, expression results in its nuclear translocation, a phenomena that is TBK1-independent. CONCLUSIONS This study identifies IKK, as a potential prostate cancer gene that may favor chronic inflammation and create a tumor-supporting microenvironment that promotes prostate cancer progression, particularly by the induction of IL-6 secretion that may act as a positive growth factor in prostate cancer. Prostate 69: 706,718, 2009. © 2009 Wiley-Liss, Inc. [source] Adenosine receptor expression in Escherichia coli -infected and cytokine-stimulated human urinary tract epithelial cellsBJU INTERNATIONAL, Issue 11 2009Susanne Säve OBJECTIVE To assess the expression and regulation of adenosine receptors in unstimulated, uropathogenic Escherichia coli (UPEC)-infected and cytokine-stimulated human urinary tract epithelial cells, and to examine the regulation of interleukin (IL)-6 secretion in response to A2A receptor activation. MATERIALS AND METHODS Human urinary tract epithelial cells (A498, T24 and RT4) were grown in cell culture and stimulated with a mixture of pro-inflammatory cytokines (CM) or UPEC. The expression of adenosine receptors was evaluated using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), Western blot analysis and immunocytochemistry. IL-6 secretion was measured with an enzyme-linked immunosorbent assay. RESULTS RT-PCR analysis showed the presence of transcripts for the A1, A2A and A2B receptor subtypes but not for the A3 receptor in A498 kidney epithelial cells. The expression of A2A receptor mRNA increased in A498 epithelial cells exposed to CM and UPEC, while A1 and A2B receptor transcripts decreased or remained unchanged. Up-regulation of A2A receptors was confirmed at the protein level using Western blot analysis and immunocytochemistry. There was also an increase in A2A receptor mRNA in human bladder epithelial cells (T24 and RT4) and in mouse bladder uroepithelium in response to cytokines and UPEC. IL-6 secretion in UPEC-infected A498 cells was decreased by 38% when exposed to the A2A receptor agonist CGS 21680. CONCLUSION Our data showed a subtype-selective plasticity among adenosine receptors in urinary tract epithelial cells in response to UPEC-infection and cytokines. There was a consistent up-regulation of A2A receptors in kidney and bladder epithelial cells. Functionally, A2A receptor activation reduced UPEC-induced IL-6 secretion. These findings suggest that adenosine might be a previously unrecognized regulator of the mucosal response in urinary tract infection. [source] | |||||||||||||||||||||||||