Lipoxin A4 Stimulates a Cytosolic Ca2+Increase in Human Bronchial Epithelium

Lipoxins are biologically active eicosanoids possessing anti-inflammatory properties. Using a calcium imaging system we investigated the effect of lipoxin A4 (LXA4) on intracellular [Ca2+] ([Ca2+]i) of human bronchial epithelial cell. Exposure of the cells to LXA4 produced a dose-dependent increase in [Ca2+]i followed by a recovery to basal values in primary culture and in 16HBE14o− cells. The LXA4-induced [Ca2+]i increase was completely abolished after pre-treatment of the 16HBE14o− cells with pertussis toxin (G-protein inhibitor). The [Ca2+]i response was not affected by the removal of external [Ca2+] but completely inhibited by thapsigargin (Ca2+-ATPase inhibitor) treatment. Pre-treatment of the bronchial epithelial cells with either MDL hydrochloride (adenylate cyclase inhibitor) or (R p)-cAMP (cAMP-dependent protein kinase inhibitor) inhibited the Ca2+ response to LXA4. However, the response was not affected by chelerytrine chloride (protein kinase C inhbitor) or montelukast (cysteinyl leukotriene receptor antagonist). The LXA4receptor mRNA was detected, by RT-PCR, in primary culture of human bronchial epithelium and in immortalized 16HBE14o− cells. The functional consequences of the effect of LXA4 on intracellular [Ca2+]i have been investigated on Cl− secretion, measured using the short-circuit techniques on 16HBE14o− monolayers grown on permeable filters. LXA4 produced a sustained stimulation of the Cl− secretion by 16HBE14o− monolayers, which was inhibited by BAPTA-AM, a chelator of intracellular calcium. Taken together our results provided evidence for the stimulation of a [Ca2+]i increase by LXA4 through a mechanism involving its specific receptor and protein kinase A activation and resulting in a subsequent Ca2+-dependent Cl− secretion by human airway epithelial cells. Lipoxins are biologically active eicosanoids possessing anti-inflammatory properties. Using a calcium imaging system we investigated the effect of lipoxin A4 (LXA4) on intracellular [Ca2+] ([Ca2+]i) of human bronchial epithelial cell. Exposure of the cells to LXA4 produced a dose-dependent increase in [Ca2+]i followed by a recovery to basal values in primary culture and in 16HBE14o− cells. The LXA4-induced [Ca2+]i increase was completely abolished after pre-treatment of the 16HBE14o− cells with pertussis toxin (G-protein inhibitor). The [Ca2+]i response was not affected by the removal of external [Ca2+] but completely inhibited by thapsigargin (Ca2+-ATPase inhibitor) treatment. Pre-treatment of the bronchial epithelial cells with either MDL hydrochloride (adenylate cyclase inhibitor) or (R p)-cAMP (cAMP-dependent protein kinase inhibitor) inhibited the Ca2+ response to LXA4. However, the response was not affected by chelerytrine chloride (protein kinase C inhbitor) or montelukast (cysteinyl leukotriene receptor antagonist). The LXA4receptor mRNA was detected, by RT-PCR, in primary culture of human bronchial epithelium and in immortalized 16HBE14o− cells. The functional consequences of the effect of LXA4 on intracellular [Ca2+]i have been investigated on Cl− secretion, measured using the short-circuit techniques on 16HBE14o− monolayers grown on permeable filters. LXA4 produced a sustained stimulation of the Cl− secretion by 16HBE14o− monolayers, which was inhibited by BAPTA-AM, a chelator of intracellular calcium. Taken together our results provided evidence for the stimulation of a [Ca2+]i increase by LXA4 through a mechanism involving its specific receptor and protein kinase A activation and resulting in a subsequent Ca2+-dependent Cl− secretion by human airway epithelial cells. lipoxin leukotriene polymorphonuclear leukocytes hydroxyeicosatetraenoic acid hydroperoxyeicosatetraenoic acid reverse transcriptase primary culture of human bronchial epithelium MDL-12, 330A, hydrochloride bis-(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid acetoxymethyl ester In this paper, we investigated the effect of lipoxin A4(LXA4)1 on intracellular [Ca2+] of airway epithelial cell. Lipoxins are biologically active eicosanoids, originally described to be produced by leukocytes possessing a 5-lipoxygenase activity, in the presence of 15-HETE (or 15-HPETE) (1Samuelsson B. Dahlen S.E. Lindgren J.A. Rouzer C.A. Serhan C.N. Science. 1987; 237: 1171-1176Google Scholar, 2Serhan C. Hamberg M. Samuelsson B. Proc. Natl. Acad. Sci. U. S. A. 1984; 81: 5335-5339Google Scholar). Lipoxins also result from the conversion of LTA4 by 12-lipoxygenase activity in platelets and the 15-lipoxygenase activity in macrophages and epithelial cells (3Serhan C.N. Sheppard K.A. J. Clin. Invest. 1990; 85: 772-780Google Scholar, 4Levy B.D. Bertram S. Tai H.H. Israel E. Fischer A. Drazen J.M. Serhan C.N. Lipids. 1993; 28: 1047-1053Google Scholar, 5Edenius C. Kumlin M. Bjork T. Anggard A. Lindgren J.A. FEBS Lett. 1990; 272: 25-28Google Scholar). The natural isomer lipoxin A4(5S,6R,15S-trihydroxy-7,9,13-trans-11-cis-eicosatetraenoic acid), which is synthesized at the inflammation site, have been shown to act as a potent anti-inflammatory mediator in different cellular systems, affecting leukocyte trafficking by modulating chemotaxis, adhesion, transmigration, and phagocytic clearance of apoptotic cells (6Colgan S.P. Serhan C.N. Parkos C.A. Delp-Archer C. Madara J.L. J. Clin. Invest. 1993; 92: 75-82Google Scholar, 7Papayianni A. Serhan C.N. Brady H.R. J. Immunol. 1996; 156: 2264-2272Google Scholar, 8Fierro I.M. Serhan C.N. Braz. J. Med. Biol. Res. 2001; 34: 555-566Google Scholar, 9McMahon B. Mitchell S. Brady H.R. Godson C. Trends Pharmacol. Sci. 2001; 22: 391-395Google Scholar). LXA4 has been measured in the bronchoalveolar and nasal lavage fluids of patients with respiratory diseases including asthma (4Levy B.D. Bertram S. Tai H.H. Israel E. Fischer A. Drazen J.M. Serhan C.N. Lipids. 1993; 28: 1047-1053Google Scholar, 10Lee T.H. Crea A.E. Gant V. Spur B.W. Marron B.E. Nicolaou K.C. Reardon E. Brezinski M. Serhan C.N. Am. Rev. Respir. Dis. 1990; 141: 1453-1458Google Scholar). Levels of LXA4 are significantly higher in sputum of mild asthmatic patients compared with the levels measured in normal subjects or asthmatics with a severe form of the disease. Because LXA4 inhibited interleukin 8 release by peripheral blood mononuclear cells, the reduced levels of LXA4 in severe asthma might be associated with the persistence of airway inflammation (11Bonnans C. Vachier I. Chavis C. Godard P. Bousquet J. Chanez P. Am. J. Respir. Crit. Care Med. 2002; 165: 1531-1535Google Scholar). In addition, PMN cells from mild asthmatic patients are able to generate in vitro larger amounts of LXA4 as compared with PMN cells obtained from normal individuals (12Chavis C. Vachier I. Chanez P. Bousquet J. Godard P. J. Exp. Med. 1996; 183: 1633-1643Google Scholar). LXA4 causes contraction of pulmonary smooth muscle (13Dahlen S.E. Raud J. Serhan C.N. Bjork J. Samuelsson B. Acta Physiol. Scand. 1987; 130: 643-647Google Scholar) although, in asthmatics, LXA4 antagonizes the broncho-constriction induced by leukotriene C4 (14Christie P.E. Spur B.W. Lee T.H. Am. Rev. Respir. Dis. 1992; 145: 1281-1284Google Scholar). LXA4 stable analogues blocked both airway hyper-responsiveness and pulmonary inflammation in a murine model of asthma (15Levy B.D. De Sanctis G.T. Devchand P.R. Kim E. Ackerman K. Schmidt B.A. Szczeklik W. Drazen J.M. Serhan C.N. Nat. Med. 2002; 8: 1018-1023Google Scholar). The airway epithelial barrier, besides its role in electrolyte and water balance of the body, also participates in inflammation as a target cell for inflammatory mediators and by secreting inflammatory cytokines. Intracellular processes such as Ca2+ or pHi signaling, protein kinase activities, and the airway neuro-humoral environment finely control the airway epithelial secretory function altered in respiratory diseases such as asthma and cystic fibrosis. However, the effect of LXA4 has not been investigated on the cellular process regulating the human airway epithelium secretory function, and its potential role in airway epithelium is not clear. Lipoxins, but particularly LXB4rather than LXA4, inhibit the proliferation of the human bronchial epithelial cell line, A549 (16Claria J. Lee M.H. Serhan C.N. Mol. Med. 1996; 2: 583-596Google Scholar). In addition, the same cell line did not show appreciable levels of the LXA4 receptor (17Gronert K. Gewirtz A. Madara J.L. Serhan C.N. J. Exp. Med. 1998; 187: 1285-1294Google Scholar). Intracellular Ca2+ plays a central role in cellular functions including inflammatory processes, and interestingly LXA4 stimulates a [Ca2+]iincrease in rainbow trout leukocytes (18Knight J. Lloyd-Evans P. Rowley A.F. Barrow S.E. J. Leukoc. Biol. 1993; 54: 518-522Google Scholar), in human monocytes (19Romano M. Maddox J.F. Serhan C.N. J. Immunol. 1996; 157: 2149-2154Google Scholar, 20Maddox J.F. Hachicha M. Takano T. Petasis N.A. Fokin V.V. Serhan C.N. J. Biol. Chem. 1997; 272: 6972-6978Google Scholar), and in human neutrophils (21Moores K.E. Merritt J.E. Eicosanoids. 1991; 4: 89-94Google Scholar). However, the direct effect of LXA4 on [Ca2+]i has not been investigated in epithelial cells. Because [Ca2+]i is a main regulator of the secretory functions of the epithelium, the aim of our study was to investigate the effect of LXA4 on [Ca2+]i and Cl− secretion through airway epithelium. The present study is the first report of a rapid and transient [Ca2+]i increase induced by LXA4in airway epithelial cells, the description of the cellular mechanisms generating the response, and its consequence on ionic secretion. The human bronchial epithelial 16HBE14o− cell line is derived from surface epithelium of mainstream, second-generation bronchi (22Cozens A.L. Yezzi M.J. Kunzelmann K. Ohrui T. Chin L. Eng K. Finkbeiner W.E. Widdicombe J.H. Gruenert D.C. Am. J. Respir. Cell Mol. Biol. 1994; 10: 38-47Google Scholar), forms polarized monolayers with intact tight junctions, and retains Cl− transport properties of freshly isolated surface airway epithelial cells (22Cozens A.L. Yezzi M.J. Kunzelmann K. Ohrui T. Chin L. Eng K. Finkbeiner W.E. Widdicombe J.H. Gruenert D.C. Am. J. Respir. Cell Mol. Biol. 1994; 10: 38-47Google Scholar). Cells were grown on a collagen/fibronectin coating, in Eagle's minimal essential medium (BioWhittaker), supplemented with 10% fetal calf serum, 1% penicillin, 1% streptomycin, and 1%l-glutamine, and incubated in a 37 °C, 5% CO2 atmosphere. For primary culture of human bronchus epithelium, cells were obtained from surgical biopsies. The bronchial samples were taken from a normal area of bronchi removed from patients suffering from lung cancer with a normal lung function (after approval by the ethics committee). After excision, the bronchial tubes were washed and incubated overnight at 4 °C with 0.38 mg/ml hyaluronidase, 0.75 mg/ml collagenase, 1 mg/ml protease, and 0.3 mg/ml DNase in RPMI 1640 medium (Invitrogen) and then filtered through a 70-mm mesh nylon strainer. Pieces of epithelium retained on the strainer were washed with phosphate-buffered saline. After centrifugation, epithelial cells were re-suspended in small airway epithelium basal medium (Clonetics, BioWhittaker, San Diego, CA) supplemented with 0.5 μg/ml human recombinant epidermal growth factors, 7.5 mg/ml bovine pituitary extract, 0.5 mg/ml epinephrine, 10 mg/ml transferin, 5 mg/ml insulin, 0.1 μg/ml retinoic acid, 6.5 μg/ml triiodothyronine, 50 mg/ml gentamicin, 50 μg/ml amphotericin B, and 50 mg/ml bovine serum albumin- fatty acid-free. Total RNA was obtained by lysing airway epithelial cells using TRIzol reagent (Invitrogen) and phenol-chloroform extraction and isopropanol precipitation. After DNase treatment (Invitrogen), 1 μg of total RNA was reversed transcripted using a Moloney murine leukemia virus (M-MTV RT) reverse transcriptase (Invitrogen). A first round of PCR was performed using the sense primer 5′-CAC CAG GTG CTG CTG GCA AG-3′ and the anti-sense primer 5′-AAT ATC CCT GAC CCC ATC CTC A-3′ (Applied Biosystems, Foster City, CA), which were designed to amplify the human peripheral blood mononuclear cell LXA4 receptor coding region (1,095 bp) (17Gronert K. Gewirtz A. Madara J.L. Serhan C.N. J. Exp. Med. 1998; 187: 1285-1294Google Scholar). In parallel, the hypoxanthine-guanine phosphoribosyltransferase gene (213 bp) was used as a housekeeping gene and amplified using the sense primer 5′-TGT AAT GAC CAG TCA ACA GGG-3′ and antisense primer 5′-TGG CTT ATA TCC AAC ACT TCG-3′ (23Jolly D.J. Okayama H. Berg P. Esty A.C. Filpula D. Bohlen P. J.E. T. T. Proc. Natl. Acad. Sci. U. S. A. Scholar). were with of of at °C, at °C, and at °C for LXA4 receptor and of at °C, 50 at °C, and at °C for hypoxanthine-guanine phosphoribosyltransferase on a A PCR was then with 0.5 of the PCR The used were as TCA CCT and to LXA4 receptor generating a S. B. D. J. S. J. Immunol. Scholar). described by S. B. D. J. S. J. Immunol. Scholar), the of LXA4 receptor was with minimal with of the receptor and with were to of at °C, at °C, and at °C, followed by a at °C for 5 PCR were using in with 1% were using imaging Intracellular [Ca2+] was in 16HBE14o− cells, in primary culture of human bronchial epithelial cells, or in A549 cells to a described V. J. Physiol. 2001; Scholar). Because A549 cells not form tight junctions, the calcium were performed on isolated A549 cells. The 16HBE14o− cells and primary culture of human bronchial epithelial cells grown on permeable and on 4 after we of cell on isolated cells, monolayers after and monolayers after For isolated cells the was with and for monolayers with a The cells were with 5 the ester for in the at and were then washed in 5 1 10 The with cell or isolated bronchial cells was on the of for cellular imaging was performed using the The cell was at and using the The produced after was filtered at The was using a to the The obtained at the of to to in performed using a of Ca2+ of the The [Ca2+]i was by a using the M. J. Biol. Chem. Scholar). For transport the 16HBE14o− cells were grown on permeable of surface area were in a and after the a as described V. B. Bousquet J. J. Physiol. 2002; Scholar). a for Cl− secretion, the of the was in and the was in a Cl− 5 1 10 The potential was measured and to by of a short-circuit using a model of was 10 the is a of The from the was using a system for The LXA4 used in this study was provided by The of lipoxin was using reverse to the described (12Chavis C. Vachier I. Chanez P. Bousquet J. Godard P. J. Exp. Med. 1996; 183: 1633-1643Google Scholar). of in were at °C to of the The to the the [Ca2+]i measured the to to LXA4 and the [Ca2+]i measured at the In the [Ca2+]i was obtained from cells in the are shown as the S.E. of of were obtained using the or the for was to be were performed using Exposure of human bronchial epithelial cells to LXA4 produced a and transient increase in [Ca2+]i A and In primary culture of human bronchial epithelial cell after produced increase in [Ca2+]i of from a basal of In 16HBE14o− cell monolayers or isolated cells to LXA4 produced a [Ca2+]i increase of from a basal of and increase of 50 from a basal of 50 In 16HBE14o− monolayers for than 4 to LXA4 did not In cells, LXA4 did not the However, as a control we a of A549 cells to to a [Ca2+]i produced the response 1 The of the Ca2+ response to LXA4 in is shown in 1 D. The larger increase in [Ca2+]i was obtained using 0.1 of LXA4 did not in used as a LXA4 did not the of the [Ca2+]i increase induced by LXA4 we investigated the effect of a and removal of external Ca2+ on 16HBE14o− cell shown in thapsigargin produced a [Ca2+]iincrease by followed by a to a After of thapsigargin the effect of LXA4 on [Ca2+]i was completely After of the 16HBE14o− cells to LXA4 did not in 5 Exposure of 16HBE14o− cells to external medium did not the response to LXA4. In and 5 produced a [Ca2+]i increase by which was not significantly different from the LXA4-induced Ca2+ increase produced in control and Taken results the response of human bronchial epithelial cells to LXA4 the Ca2+ release from intracellular than Ca2+ from the The role of either protein kinase A or protein kinase C in the of the response have been investigated using (R p)-cAMP of protein kinase A MDL hydrochloride of and chelerytrine chloride of protein kinase C on 16HBE14o− cell (R p)-cAMP MDL hydrochloride chloride significantly affected the basal of [Ca2+]i 8 4 shown in B, (R p)-cAMP and MDL the response to of After chloride the response to was not significantly different from control C and Because A549 cells not levels of LXA4 the of the effect of LXA4 on [Ca2+]i in A549 cells in 16HBE14o− cells the Ca2+ response to LXA4 is by the LXA4 Because the LXA4 receptor have been to be to pertussis we the effect of the toxin on the Ca2+ response induced by LXA4 in cells. shown in A and in 16HBE14o− cells pertussis toxin treatment completely abolished the response to LXA4 at either LXA4 produced a [Ca2+]i of at and of at also investigated the role of the leukotriene which be by LXA4 and is also to pertussis toxin in the [Ca2+]i response to LXA4. shown in and montelukast used as a specific leukotriene receptor did not the to LXA4 The LXA4receptor mRNA was investigated in different human bronchial epithelial cells the and the A549 by using specific for LXA4receptor of the housekeeping gene hypoxanthine-guanine phosphoribosyltransferase was to control for and PCR blood mononuclear cells, from which the LXA4 receptor has been were used as control J.F. Hachicha M. Takano T. Petasis N.A. Fokin V.V. Serhan C.N. J. Biol. Chem. 1997; 272: 6972-6978Google Scholar). of the PCR obtained is shown in LXA4 receptor mRNA was not after a first round of of of the and cell of LXA4 receptor in human bronchial epithelial cells the of as shown in the in 16HBE14o− and LXA4 receptor A549 cells did Because intracellular a regulator of epithelial secretory function we investigated a role for LXA4 on a Ca2+-dependent Cl− secretion. LXA4 on the of the produced a sustained increase by 1 of the short-circuit The increase and 5 after the of LXA4 and a 10 In of external Cl− on both of the epithelium, the response to LXA4 was completely the LXA4 effect on the was to Cl− secretion The role of intracellular [Ca2+]i on the was investigated using the intracellular calcium the shown in produced a of the a of intracellular [Ca2+] to the basal However, after of treatment with BAPTA-AM, the on short-circuit was completely results the LXA4-induced short-circuit increase is to the stimulation of a Ca2+-dependent secretory The present study is the first description of the rapid [Ca2+]i increase induced by LXA4in human airway epithelial cells including the description of the cellular mechanism in the The stimulation of a [Ca2+]i increase by LXA4 has been in rainbow trout leukocytes (18Knight J. Lloyd-Evans P. Rowley A.F. Barrow S.E. J. Leukoc. Biol. 1993; 54: 518-522Google Scholar), in human monocytes (19Romano M. Maddox J.F. Serhan C.N. J. Immunol. 1996; 157: 2149-2154Google J.F. Hachicha M. Takano T. Petasis N.A. Fokin V.V. Serhan C.N. J. Biol. Chem. 1997; 272: 6972-6978Google Scholar), and in human neutrophils (21Moores K.E. Merritt J.E. Eicosanoids. 1991; 4: 89-94Google Scholar). In airway epithelial of the intracellular calcium as the main of the LXA4-induced [Ca2+]iincrease is with the report of intracellular calcium induced by LXA4 in cell (19Romano M. Maddox J.F. Serhan C.N. J. Immunol. 1996; 157: 2149-2154Google Scholar, 20Maddox J.F. Hachicha M. Takano T. Petasis N.A. Fokin V.V. Serhan C.N. J. Biol. Chem. 1997; 272: 6972-6978Google Scholar). In addition, the murine LXA4 receptor and was also shown to the of a cellular to Ca2+ J. Immunol. 2002; Scholar). is report of a [Ca2+]i increase induced by LXA4 in epithelial cells. In cells, epithelial cell line, LXA4 inhibited the of PMN by the Ca2+ response to the epithelial but the direct effect of LXA4 on [Ca2+]i was not B. Petasis N.A. K. Serhan C.N. Madara J.L. J. Clin. Invest. 1998; Scholar). The [Ca2+]i response to LXA4 was dose-dependent with a response measured at which is with the [Ca2+]i response to LXA4 in cell A effect was obtained at in human neutrophils and human monocytes and at in rainbow leukocytes (18Knight J. Lloyd-Evans P. Rowley A.F. Barrow S.E. J. Leukoc. Biol. 1993; 54: 518-522Google Scholar, M. Maddox J.F. Serhan C.N. J. Immunol. 1996; 157: 2149-2154Google Scholar, 20Maddox J.F. Hachicha M. Takano T. Petasis N.A. Fokin V.V. Serhan C.N. J. Biol. Chem. 1997; 272: 6972-6978Google Scholar, K.E. Merritt J.E. Eicosanoids. 1991; 4: 89-94Google Scholar). In human monocytes the [Ca2+]i response was by stimulation of the LXA4 receptor J.F. Hachicha M. Takano T. Petasis N.A. Fokin V.V. Serhan C.N. J. Biol. Chem. 1997; 272: 6972-6978Google Scholar). The LXA4 receptor has been in human leukocytes S. Serhan C.N. 34: Scholar) and in epithelial cell (17Gronert K. Gewirtz A. Madara J.L. Serhan C.N. J. Exp. Med. 1998; 187: 1285-1294Google Scholar). mRNA of the LXA4 receptor in the 16HBE14o− cell line and in human bronchial epithelial cells in but not in A549 cells. The of the LXA4 receptor mRNA in human airway epithelial cells is with the of LXA4 receptor in murine lung J. Immunol. 2002; Scholar). results are in with the K. S.P. Serhan C.N. J. Pharmacol. Exp. 1998; Scholar) the human bronchial epithelial cell line A549 did not show appreciable levels of LXA4 receptor which we as a cell line than a of the LXA4 receptor Because is not LXA4receptor in A549 cells, we this cell line as a the the LXA4receptor mRNA and the the LXA4 receptor was in the Ca2+ the LXA4 receptor activation has been shown to be associated to the of the LXA4-induced [Ca2+]i response to pertussis toxin is also with a role for LXA4receptor in the has been in cells, LXA4 the which is also to a M. Serhan C.N. Proc. Natl. Acad. Sci. U. S. A. Scholar, in Scholar). However, we have shown the montelukast did not the [Ca2+]i response to LXA4 in airway epithelium, which the [Ca2+]i response to LXA4 is not by the receptor S.E. Respir. J. Scholar). result evidence for the of the LXA4 receptor in the Ca2+ response to LXA4 in airway epithelial cell. Because LXA4 is a the of epithelium to LXA4 not the However, the of Ca2+ response to to LXA4 of monolayers compared with the response obtained in isolated cells or cell monolayers be by the of of the of the a of the LXA4 In this is with the report T. Gewirtz D. Madara J.L. Am. J. Physiol. Cell Physiol. 2002; Scholar) of a of the LXA4 receptor in epithelial cells. we the of the by LXA4 on the Because the role of LXA4 in protein kinase C activation have been we investigated the of protein kinase C activity in the of the Ca2+ response A. Serhan C.N. J. M. Samuelsson B. Res. Scholar, K. A. FEBS Lett. Scholar, D. J. FEBS Lett. 1990; Scholar, Spur B.W. Lee T.H. J. Pharmacol. 1996; Scholar). The of a protein kinase C in the Ca2+ response to LXA4 protein kinase C activity is not in the of the However, the stimulation of protein kinase C activity by LXA4 might Ca2+ as described in the present The role of protein kinase A activity has also been The effect of (R p)-cAMP and MDL hydrochloride in airway epithelium, the Ca2+ response to stimulation of cyclase and protein kinase A In the LXA4 effect on in monocytes and macrophages is by the protein kinase A and inhibited by the cell P. D.C. Petasis N.A. Brady H.R. Godson C. Am. J. 2002; Scholar). Intracellular [Ca2+] plays a central role in epithelial cellular function such as or protein secretion. The LXA4-induced [Ca2+]i response might be in by epithelium, which is to on [Ca2+]i Am. J. Respir. Cell Mol. Biol. 1991; Scholar, P. Barrow S.E. D.J. J. Rowley A.F. 1994; Scholar, Rowley A.F. Barrow S.E. J. Biol. Chem. 1991; Scholar). a [Ca2+]i increase is for activity in the LXA4 from its (12Chavis C. Vachier I. Chanez P. Bousquet J. Godard P. J. Exp. Med. 1996; 183: 1633-1643Google Scholar, P. Barrow S.E. D.J. J. Rowley A.F. 1994; Scholar, Rowley A.F. Barrow S.E. J. Biol. Chem. 1991; Scholar). the LXA4-induced [Ca2+]i increase might a central role in of LXA4 and mechanism for the of In addition, our results the Cl− secretion induced by LXA4 is of the functional consequences of the LXA4-induced in airway epithelial cells, its anti-inflammatory role LXA4 is in ionic transport might have in in the treatment of respiratory diseases associated with transport and anti-inflammatory treatment such as cystic and D.C. Gruenert of San CA) for the of the 16HBE14o− cell