Integrins mediate adherence and migration of T lymphocytes on human peritoneal mesothelial cells
2008; Elsevier BV; Volume: 74; Issue: 6 Linguagem: Inglês
10.1038/ki.2008.330
ISSN1523-1755
AutoresHsin‐Hui Wang, Tzong‐Yann Lee, Ching‐Yuang Lin,
Tópico(s)Pancreatitis Pathology and Treatment
ResumoWe previously showed that a local immune response largely composed of type 1 T cells correlated with a favorable outcome of the peritonitis associated with peritoneal dialysis. To clarify how these subsets are recruited to the peritoneal cavity during inflammation, we measured integrin-mediated interactions between the T cells and human peritoneal mesothelial cells. Direct microscopy showed that lipopolysaccharide or peritoneal dialysis effluent stimulated the adherence of T cells to mesothelial cells, a process mediated by the integrins α6β1 and α4β1. Further, the migration of Th1 cell across human mesothelial cell monolayers grown on transwell surfaces was reduced by anti-α6β1 integrin antibody while that of Th2 cell was inhibited by an anti-α4 integrin antibody. Pretreatment with either lipopolysaccharide or rapid response peritoneal dialysis effluent stimulated T cell migration and this was significantly decreased by the α6β1 compared to the α4 antibody. These results suggest that integrins may play an important role in mediating selective T cell subset adhesion and migration across human peritoneal mesothelial cell monolayers and differential integrin expression and selective T cell subset recruitment during peritonitis may affect outcome. We previously showed that a local immune response largely composed of type 1 T cells correlated with a favorable outcome of the peritonitis associated with peritoneal dialysis. To clarify how these subsets are recruited to the peritoneal cavity during inflammation, we measured integrin-mediated interactions between the T cells and human peritoneal mesothelial cells. Direct microscopy showed that lipopolysaccharide or peritoneal dialysis effluent stimulated the adherence of T cells to mesothelial cells, a process mediated by the integrins α6β1 and α4β1. Further, the migration of Th1 cell across human mesothelial cell monolayers grown on transwell surfaces was reduced by anti-α6β1 integrin antibody while that of Th2 cell was inhibited by an anti-α4 integrin antibody. Pretreatment with either lipopolysaccharide or rapid response peritoneal dialysis effluent stimulated T cell migration and this was significantly decreased by the α6β1 compared to the α4 antibody. These results suggest that integrins may play an important role in mediating selective T cell subset adhesion and migration across human peritoneal mesothelial cell monolayers and differential integrin expression and selective T cell subset recruitment during peritonitis may affect outcome. Peritoneal dialysis (PD) is an established treatment for end-stage renal disease.1.Gokal R. Mallick N.P. Peritoneal dialysis.Lancet. 1999; 353: 823-828Abstract Full Text Full Text PDF PubMed Scopus (98) Google Scholar Peritonitis, a local inflammatory disorder, is the most serious complication of PD.2.Fried L.F. Bernardini J. Johnston J.R. et al.Peritonitis influences mortality in peritoneal dialysis patients.J Am Soc Nephrol. 1996; 7: 2176-2182PubMed Google Scholar,3.Maiorca R. Vonesh E.F. Cavalli P. et al.A multicenter, selection-adjusted comparison of patient and technique survivals on CAPD and hemodialysis.Perit Dial Int. 1991; 11: 118-127PubMed Google Scholar,4.Abdel-Rahman E.M. Wakeen M. Zimmerman S.W. Characteristics of long-term peritoneal dialysis survivors: 18 years experience in one center.Perit Dial Int. 1997; 17: 151-156PubMed Google Scholar,5.Tranaeus A. Heimburger O. Lindholm B. Peritonitis in continuous ambulatory peritoneal dialysis (CAPD): diagnostic findings, therapeutic outcome and complications.Perit Dial Int. 1989; 9: 179-190PubMed Google Scholar,6.Davies S.J. Bryan J. Phillips L. et al.Longitudinal changes in peritoneal kinetics: the effects of peritoneal dialysis and peritonitis.Nephrol Dial Transplant. 1996; 11: 498-506Crossref PubMed Google Scholar,7.Piraino B. Peritonitis as a complication of peritoneal dialysis.J Am Soc Nephrol. 1998; 9: 1956-1964PubMed Google Scholar All the resident peritoneal cavity cells, as well as the leukocytes that are recruited and infiltrate, coordinate the immune response associated with peritoneal infection.8.Broche F. Tellado J.M. Defense mechanisms of the peritoneal cavity.Curr Opin Crit Care. 2001; 7: 105-116Crossref PubMed Scopus (67) Google Scholar,9.Holmes C.J. Peritoneal host defense mechanisms in peritoneal dialysis.Kidney Int Suppl. 1994; 48: S58-S70PubMed Google Scholar,10.Topley N. The cytokine network controlling peritoneal inflammation.Perit Dial Int. 1995; 15 (discussion S39–40): S35-S39PubMed Google Scholar Human peritoneal mesothelial cells (HPMCs) line the surface of the peritoneal membrane. Following stimulation by bacteria-secreted products or pro-inflammatory cytokines, HPMCs secrete inflammatory cytokines and chemokines, which activate and control peritoneal inflammatory processes and attract leukocytes into the peritoneal cavity.11.Li F.K. Davenport A. Robson R.L. et al.Leukocyte migration across human peritoneal mesothelial cells is dependent on directed chemokine secretion and ICAM-1 expression.Kidney Int. 1998; 54: 2170-2183Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar,12.Visser C.E. Tekstra J. Brouwer-Steenbergen J.J. et al.Chemokines produced by mesothelial cells: huGRO-alpha, IP-10, MCP-1 and RANTES.Clin Exp Immunol. 1998; 112: 270-275Crossref PubMed Scopus (77) Google Scholar,13.Tekstra J. Visser C.E. Tuk C.W. et al.Identification of the major chemokines that regulate cell influxes in peritoneal dialysis patients.J Am Soc Nephrol. 1996; 7: 2379-2384PubMed Google Scholar,14.Betjes M.G. Visser C.E. Zemel D. et al.Intraperitoneal interleukin-8 and neutrophil influx in the initial phase of a CAPD peritonitis.Perit Dial Int. 1996; 16: 385-392PubMed Google Scholar,15.Topley N. Williams J.D. Role of the peritoneal membrane in the control of inflammation in the peritoneal cavity.Kidney Int Suppl. 1994; 48: S71-S78PubMed Google Scholar HPMCs constitutively express intracellular adhesion molecule-1 and vascular cell adhesion molecule-1; expressions of both are increased with in vivo inflammation or after cytokine stimulation in vitro.11.Li F.K. Davenport A. Robson R.L. et al.Leukocyte migration across human peritoneal mesothelial cells is dependent on directed chemokine secretion and ICAM-1 expression.Kidney Int. 1998; 54: 2170-2183Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar,16.Liberek T. Topley N. Luttmann W. et al.Adherence of neutrophils to human peritoneal mesothelial cells: role of intercellular adhesion molecule-1.J Am Soc Nephrol. 1996; 7: 208-217PubMed Google Scholar,17.Jonjic N. Peri G. Bernasconi S. et al.Expression of adhesion molecules and chemotactic cytokines in cultured human mesothelial cells.J Exp Med. 1992; 176: 1165-1174Crossref PubMed Scopus (230) Google Scholar,18.Andreoli S.P. Mallett C. Williams K. et al.Mechanisms of polymorphonuclear leukocyte mediated peritoneal mesothelial cell injury.Kidney Int. 1994; 46: 1100-1109Abstract Full Text PDF PubMed Scopus (41) Google Scholar,19.Cannistra S.A. Ottensmeier C. Tidy J. et al.Vascular cell adhesion molecule-1 expressed by peritoneal mesothelium partly mediates the binding of activated human T lymphocytes.Exp Hematol. 1994; 22: 996-1002PubMed Google Scholar Thus, HPMCs play an important role in mediating leukocyte trafficking into the peritoneal cavity. In PD patients, leukocyte infiltration into the peritoneal cavity is important for eradicating the invading organisms.20.Betjes M.G. Tuk C.W. Visser C.E. et al.Analysis of the peritoneal cellular immune system during CAPD shortly before a clinical peritonitis.Nephrol Dial Transplant. 1994; 9: 684-692PubMed Google Scholar,21.Betjes M.G. Tuk C.W. Struijk D.G. et al.Immuno-effector characteristics of peritoneal cells during CAPD treatment: a longitudinal study.Kidney Int. 1993; 43: 641-648Abstract Full Text PDF PubMed Scopus (56) Google Scholar The mechanisms that control leukocyte extravasation from the circulation have been extensively studied. However, how leukocytes recognize and traverse the peritoneal mesothelial lining and enter the peritoneal cavity has yet to be determined. Previous investigations have addressed the role of intracellular adhesion molecule-1 expression in leukocyte migration across HPMCs,11.Li F.K. Davenport A. Robson R.L. et al.Leukocyte migration across human peritoneal mesothelial cells is dependent on directed chemokine secretion and ICAM-1 expression.Kidney Int. 1998; 54: 2170-2183Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar,16.Liberek T. Topley N. Luttmann W. et al.Adherence of neutrophils to human peritoneal mesothelial cells: role of intercellular adhesion molecule-1.J Am Soc Nephrol. 1996; 7: 208-217PubMed Google Scholar,22.Zeillemaker A.M. Mul F.P. Hoynck van Papendrecht A.A. et al.Neutrophil adherence to and migration across monolayers of human peritoneal mesothelial cells. The role of mesothelium in the influx of neutrophils during peritonitis.J Lab Clin Med. 1996; 127: 279-286Abstract Full Text PDF PubMed Scopus (28) Google Scholar and the role of interferon-γ and interleukin (IL)-17 in controlling neutrophil migration across the mesothelium.23.Robson R.L. McLoughlin R.M. Witowski J. et al.Differential regulation of chemokine production in human peritoneal mesothelial cells: IFN-gamma controls neutrophil migration across the mesothelium in vitro and in vivo.J Immunol. 2001; 167: 1028-1038Crossref PubMed Scopus (57) Google Scholar,24.Witowski J. Pawlaczyk K. Breborowicz A. et al.IL-17 stimulates intraperitoneal neutrophil infiltration through the release of GRO alpha chemokine from mesothelial cells.J Immunol. 2000; 165: 5814-5821Crossref PubMed Scopus (264) Google Scholar The mechanisms that control T-lymphocyte migration across HPMCs have not been addressed. The T-cell/subsets response plays a role in peritoneal immunity during peritonitis. Previous studies showed that interferon-γ levels in PD effluent (PDE) were often elevated in patients with bacterial peritonitis.25.Dasgupta M.K. Larabie M. Halloran P.F. Interferon-gamma levels in peritoneal dialysis effluents: relation to peritonitis.Kidney Int. 1994; 46: 475-481Abstract Full Text PDF PubMed Scopus (34) Google Scholar We previously found that a progressive increase in the CD4/CD8 ratio in PDE indicated a favorable outcome in patients with PD-related peritonitis.26.Wang H.H. Lin C.Y. Huang T.P. Patterns of CD4/CD8 T-cell ratio in dialysis effluents predict the long-term outcome of peritonitis in patients undergoing peritoneal dialysis.Nephrol Dial Transplant. 2003; 18: 1181-1189Crossref PubMed Scopus (19) Google Scholar We recently found that high IL-12 and IL-18 levels in PDE during the early phase of peritonitis were correlated with a predominant type I T-cell immune response and a favorable outcome.27.Wang H.H. Lin C.Y. Interleukin-12 and -18 levels in peritoneal dialysate effluent correlate with the outcome of peritonitis in patients undergoing peritoneal dialysis: implications for the Type I/Type II T-cell immune response.Am J Kidney Dis. 2005; 46: 328-338Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar Some studies show the link between T cells and HPMCs in peritoneal immunity. Hausmann et al.28.Hausmann M.J. Rogachev B. Weiler M. et al.Accessory role of human peritoneal mesothelial cells in antigen presentation and T-cell growth.Kidney Int. 2000; 57: 476-486Abstract Full Text Full Text PDF PubMed Scopus (52) Google Scholar found that HPMCs participated in the peritoneal immune response by antigen presentation and contributed to T-cell activation by secreting IL-15.28.Hausmann M.J. Rogachev B. Weiler M. et al.Accessory role of human peritoneal mesothelial cells in antigen presentation and T-cell growth.Kidney Int. 2000; 57: 476-486Abstract Full Text Full Text PDF PubMed Scopus (52) Google Scholar Basok et al.29.Basok A. Shnaider A. Man L. et al.CD40 is expressed on human peritoneal mesothelial cells and upregulates the production of interleukin-15 and RANTES.J Am Soc Nephrol. 2001; 12: 695-702PubMed Google Scholar reported that CD40, whose ligand is mainly expressed on the membrane of activated CD4 lymphocytes, is expressed on HPMCs. However, the interaction between T cells and HPMCs needs further study. Integrins mediate cell–cell and cell–extracellular matrix adhesion.30.Hynes R.O. Integrins: versatility, modulation, and signaling in cell adhesion.Cell. 1992; 69: 11-25Abstract Full Text PDF PubMed Scopus (8813) Google Scholar,31.Albelda S.M. Buck C.A. Integrins and other cell adhesion molecules.FASEB J. 1990; 4: 2868-2880Crossref PubMed Scopus (1592) Google Scholar,32.Hynes R.O. Integrins: a family of cell surface receptors.Cell. 1987; 48: 549-554Abstract Full Text PDF PubMed Scopus (3002) Google Scholar,33.Ruoslahti E. Integrins.J Clin Invest. 1991; 87: 1-5Crossref PubMed Scopus (1441) Google Scholar Integrins are not simply adhesion sites on T cells; they play prominent roles in the migration of T cells to peripheral lymph node and inflammatory sites, in antigen presentation, cytotoxic killing, and transduction of co-stimulatory signals in T cells.34.Hogg N. Laschinger M. Giles K. et al.T-cell integrins: more than just sticking points.J Cell Sci. 2003; 116: 4695-4705Crossref PubMed Scopus (231) Google Scholar,35.von Andrian U.H. Mackay C.R. T-cell function and migration. Two sides of the same coin.N Engl J Med. 2000; 343: 1020-1034Crossref PubMed Scopus (1175) Google Scholar,36.Westermann J. Engelhardt B. Hoffmann J.C. Migration of T cells in vivo: molecular mechanisms and clinical implications.Ann Intern Med. 2001; 135: 279-295Crossref PubMed Scopus (66) Google Scholar,37.Faull R.J. Ginsberg M.H. Inside-out signaling through integrins.J Am Soc Nephrol. 1996; 7: 1091-1097Crossref PubMed Google Scholar,38.Clark E.A. Brugge J.S. Integrins and signal transduction pathways: the road taken.Science. 1995; 268: 233-239Crossref PubMed Scopus (2758) Google Scholar T helper (Th) subtype 1 (Th1) and subtype 2 (Th2) cells have different integrin expression patterns; these differences contribute to the differential recruitment of Th1 and Th2 cells39.D'Ambrosio D. Iellem A. Colantonio L. et al.Localization of Th-cell subsets in inflammation: differential thresholds for extravasation of Th1 and Th2 cells.Immunol Today. 2000; 21: 183-186Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar and promote a predominant type I or type II T-cell immune response. Previous studies showed preferential expression of integrin α6β1 on Th1 cells; IL-12 upregulates their expression and promotes Th1 cell migration.39.D'Ambrosio D. Iellem A. Colantonio L. et al.Localization of Th-cell subsets in inflammation: differential thresholds for extravasation of Th1 and Th2 cells.Immunol Today. 2000; 21: 183-186Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar,40.Colantonio L. Iellem A. Clissi B. et al.Upregulation of integrin alpha6/beta1 and chemokine receptor CCR1 by interleukin-12 promotes the migration of human type 1 helper T cells.Blood. 1999; 94: 2981-2989Crossref PubMed Google Scholar,41.Clissi B. D'Ambrosio D. Geginat J. et al.Chemokines fail to up-regulate beta 1 integrin-dependent adhesion in human Th2 T lymphocytes.J Immunol. 2000; 164: 3292-3300Crossref PubMed Scopus (31) Google Scholar Th2 cells express elevated levels of α4β1 integrins, which mediate Th2 cell adhesion and migration.35.von Andrian U.H. Mackay C.R. T-cell function and migration. Two sides of the same coin.N Engl J Med. 2000; 343: 1020-1034Crossref PubMed Scopus (1175) Google Scholar,39.D'Ambrosio D. Iellem A. Colantonio L. et al.Localization of Th-cell subsets in inflammation: differential thresholds for extravasation of Th1 and Th2 cells.Immunol Today. 2000; 21: 183-186Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar,41.Clissi B. D'Ambrosio D. Geginat J. et al.Chemokines fail to up-regulate beta 1 integrin-dependent adhesion in human Th2 T lymphocytes.J Immunol. 2000; 164: 3292-3300Crossref PubMed Scopus (31) Google Scholar,42.Lim Y.C. Wakelin M.W. Henault L. et al.Alpha4beta1-integrin activation is necessary for high-efficiency T-cell subset interactions with VCAM-1 under flow.Microcirculation. 2000; 7: 201-214Crossref PubMed Scopus (39) Google Scholar The role of T-cell integrin as an adhesion, migration, and co-stimulatory molecule suggests that integrins may be involved in the interaction between T cells and HPMCs. However, the role and regulation of T-cell integrins during the interaction with HPMCs are poorly defined. To clarify the mechanisms of T-lymphocyte adherence and migration across HPMCs, we developed an in vitro adhesion and migration assay to determine whether integrins are involved in T lymphocyte–mesothelial recognition under various conditions. The various integrins involved in the different T-cell subsets and in their interaction with HPMCs were also investigated to elucidate the mechanism regulating the polarized T-cell immune response. Our data indicate that integrins may play an important role in mediating T-lymphocyte adhesion and migration across HPMCs; the presence of differential integrins promotes the selective recruitment of T-cell subsets and correlates with peritonitis treatment outcome. To determine whether T lymphocytes are capable of adhering to HPMCs under different environmental stimuli, the adhesion relationships were observed directly under a microscope. HPMCs have a small, round, often eccentric, nucleus and a large amount of cytoplasm (Figure 1a). When HPMCs were not pre-stimulated, 3.0±1.6% of HPMC–T-lymphocytes formed rosettes (Figure 1b). When HPMCs were pre-exposed to lipopolysaccharide (LPS), 20.2±3.1% formed rosettes (Figure 1c). When HPMCs were pre-exposed to rapid and delayed-response PDE, 19.1±2.9% (Figure 1d) and 18.2±3.3% (Figure 1e) formed rosettes, respectively. After stimulation with LPS or PDE, HPMCs showed a polarized morphology with multiple elongated cytoplasmic processes (Figure 1c–e). Compared with HPMCs without pre-stimulation, significantly more LPS- and PDE-pretreated HPMCs formed rosettes with T lymphocytes (P<0.05). These data show that T lymphocytes exhibit low-level specific binding to HPMCs under control conditions, and that stimulation enhances adhesion. To study integrin expression during HPMC–T-lymphocyte adhesion, immunofluorescence staining was carried out. The expression of α6β1 and α4β1 integrins was examined due to their potential role in Th subset adhesion and migration. When T lymphocytes interacted with unstimulated HPMCs, the expressions of integrins α6β1 and α4β1 were 4.7±1.1% and 3.2±0.7%, respectively (Figure 2a). When HPMCs were pre-stimulated with LPS, the T-lymphocyte expressions of integrins α6β1 and α4β1 increased to 36.4±5.3% and 32.2±4.3%, respectively (Figure 2b). Compared with the control group of HPMCs without pre-stimulation, T-lymphocyte expressions of integrins α6β1 and α4β1 increased significantly (P<0.05). When HPMCs were pre-stimulated with rapid-response PDE, T-lymphocyte expressions of α6β1 and α4β1 integrins increased significantly (P<0.05) compared with the control groups (38.6±4.4%, 35.9±5.3%, respectively; Figure 2c). T-lymphocyte expressions of α6β1 (35.2±4.2%) and α4β1 (36.4±3.7%) integrins increased significantly (P<0.05) when they interacted with HPMCs pretreated with delayed-response PDE (Figure 2d), compared with when they interacted with unstimulated HPMC controls. Blank controls with HPMC only were negative for the expression of both α6β1 and α4β1 integrins. Thus, integrins α6β1 and α4β1 are involved in HPMC–T-lymphocyte adhesion, and their expression increases after HPMC pre-stimulation. To determine whether T lymphocytes migrate across HPMCs under various environmental stimuli, an in vitro migration system was used to assess the time course of changes (Figure 3). Apical pre-stimulation of the HPMC monolayer with LPS or PDE resulted in a time-dependent increase in T-lymphocyte migration across HPMCs. T-lymphocyte migration across pre-stimulated HPMCs was significantly greater than control after 2 h of stimulation, and continued to increase (P<0.05; Figure 3). No significant difference in T-lymphocyte migration was observed for HPMCs pre-stimulated with LPS or PDE (rapid or delayed clinical response). To determine whether integrins had an effect on T-lymphocyte migration across HPMCs, antibody-blocking of T-lymphocyte migration was studied. In the control group, T-lymphocyte migration was not significantly reduced by pretreatment with anti-α6β1 or anti-α4 antibody (Figure 4a). T lymphocytes pretreated with anti-α6β1 or anti-α4 antibody had significantly reduced migration across HPMCs in the LPS and PDE groups (Figure 4b–d). When HPMCs were pre-stimulated with LPS, T lymphocytes pretreated with anti-α6β1 antibody showed significantly reduced migration after 6 h stimulation and continued throughout the entire duration of the study, compared to T lymphocytes pretreated with anti-α4 antibody (P 0.05; Figure 4d). These data suggest that integrins play a role in T-lymphocyte migration across HPMCs. However, the importance of α6β1 and α4β1 integrins depends on the conditions used to stimulate HPMCs. Polarized human Th lymphocytes were generated (Figure 5) to study how different integrins mediate the migration of the various T-cell subsets across HPMCs. In the control group, there was no significant reduction of Th1-cell migration following anti-α6β1 or anti-α4 antibody treatment (Figure 6a). In the LPS and PDE groups, Th1 cells that were pretreated with anti-α6β1 antibody showed decreased migration across HPMCs compared with untreated Th1 cells (Figure 6b–d). When Th1 cells were pretreated with anti-α4 antibody, Th1-cell migration was mildly decreased compared with untreated Th1 cells, but the difference was not statistically significant (Figure 6b–d). In the LPS- and PDE-stimulated groups, there was a significant decrease in Th1-cell migration with anti-α6β1 antibody treatment compared with anti-α4 antibody treatment throughout the experiment (P<0.05; Figure 6b–d). These data suggest that α6β1 integrin is more important than α4β1 integrin in Th1-cell migration across HPMCs.Figure 6Inhibition of Th1-cell migration across HPMCs by anti-α6β1 antibodies. (a) HPMCs without pre-stimulation at different time periods; HPMCs pre-stimulated with (b) LPS 10 μg/ml; (c) rapid-response PDE 1000 μg/ml; (d) delayed-response PDE 1000 μg/ml in different time periods. ▪, no antibody; , Th1 cells pretreated with anti-α6β1 antibody; , Th1 cells pretreated with anti-α4 antibody; □, Th1 cells pretreated with isotype-matched control antibody.Data are expressed as mean±s.d. from eight separate experiments. *P<0.05 versus control, **P<0.05 anti-α6β1 antibody versus anti-α4 antibody.View Large Image Figure ViewerDownload (PPT) In the control group, there was no significant reduction in Th2-cell migration after pretreatment with either anti-α6β1 or anti-α4 antibody (Figure 7a). In the LPS- and PDE-stimulated groups, pretreatment with anti-α4 antibody inhibited Th2-cell migration across HPMCs compared with untreated Th2 cells (P<0.05; Figure 7b–d). The reduction in Th2-cell migration occurred after 2 h of stimulation and continued throughout the entire experiment. Th2-cell migration was somewhat reduced with anti-α6β1 antibody pretreatment, but, compared with untreated Th2 cells, the difference was not statistically significant (Figure 7b–d). In the LPS- and PDE-stimulated groups, there was a significant decrease in Th2-cell migration with anti-α4 antibody treatment compared with anti-α6β1 antibody treatment (P<0.05; Figure 7b–d). Thus, α4β1 integrin appears to be more important than α6β1 integrin in Th2-cell migration across HPMCs. The present study used in vitro systems to examine the adhesion relationship and migration behavior of HPMCs and T lymphocytes. The morphology of the T-lymphocyte–mesothelial cell interaction and the role that integrins play in the interaction have not been previously reported with respect to peritoneal immunity. Microscopic observation showed direct adhesion of HPMCs and T lymphocytes through rosette formation. This provides evidence that the mesothelium plays an active role in peritoneal inflammatory processes. Based on immunofluorescence staining, it was found that integrins α6β1 and α4β1 were involved in the interaction and that their expression increased after stimulation. The data suggest that both integrin and its ligand are important in peritoneal inflammatory and immune reaction. The present study also found morphological evidence that HPMCs may act as antigen-presenting cells,28.Hausmann M.J. Rogachev B. Weiler M. et al.Accessory role of human peritoneal mesothelial cells in antigen presentation and T-cell growth.Kidney Int. 2000; 57: 476-486Abstract Full Text Full Text PDF PubMed Scopus (52) Google Scholar and that integrins may act as co-stimulatory molecules that activate T lymphocytes and promote the adaptive peritoneal immune response. The migration assay study indicated the importance of integrins α6β1 and α4β1 in the migration process of T lymphocytes across HPMCs. Furthermore, α6β1 integrin predominantly mediates Th1-cell migration across HPMCs and α4β1 integrin predominantly mediates Th2-cell migration. To the best of our knowledge, this is the first time that Th-subset integrin expression and function have been demonstrated in peritonitis. The differential expression of integrins on Th subsets is compatible with previous studies under other conditions.35.von Andrian U.H. Mackay C.R. T-cell function and migration. Two sides of the same coin.N Engl J Med. 2000; 343: 1020-1034Crossref PubMed Scopus (1175) Google Scholar,39.D'Ambrosio D. Iellem A. Colantonio L. et al.Localization of Th-cell subsets in inflammation: differential thresholds for extravasation of Th1 and Th2 cells.Immunol Today. 2000; 21: 183-186Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar,40.Colantonio L. Iellem A. Clissi B. et al.Upregulation of integrin alpha6/beta1 and chemokine receptor CCR1 by interleukin-12 promotes the migration of human type 1 helper T cells.Blood. 1999; 94: 2981-2989Crossref PubMed Google Scholar,41.Clissi B. D'Ambrosio D. Geginat J. et al.Chemokines fail to up-regulate beta 1 integrin-dependent adhesion in human Th2 T lymphocytes.J Immunol. 2000; 164: 3292-3300Crossref PubMed Scopus (31) Google Scholar,42.Lim Y.C. Wakelin M.W. Henault L. et al.Alpha4beta1-integrin activation is necessary for high-efficiency T-cell subset interactions with VCAM-1 under flow.Microcirculation. 2000; 7: 201-214Crossref PubMed Scopus (39) Google Scholar These data suggest that integrins are expressed on T lymphocytes and play an important regulatory role in controlling the phenotype of infiltrating T lymphocytes during peritoneal inflammation. In our previous study,27.Wang H.H. Lin C.Y. Interleukin-12 and -18 levels in peritoneal dialysate effluent correlate with the outcome of peritonitis in patients undergoing peritoneal dialysis: implications for the Type I/Type II T-cell immune response.Am J Kidney Dis. 2005; 46: 328-338Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar a type I T-cell response was found to be critical for favorable outcome following peritonitis treatment. In the present study, stimulation with rapid-response PDE caused a profound decrease in T-cell migration when the T cells were pretreated with anti-α6β1 antibody. These data indicate that, with rapid-response PDE stimulation, adaptive immunity predominantly shifted toward Th1 immune response, which is clinically correlated with a favorable treatment outcome. The maintenance of a functionally polarized immune response requires different T-cell subsets to localize in sites of inflammation. The present data may explain how different T-cell subsets are preferentially recruited to sites of peritoneal inflammation; selective modulation of these integrins illustrates an additional level of control for specific T-cell subset homing. Manipulating T-lymphocyte integrin expression could modulate the Th1/Th2 balance and affect the outcome of peritonitis treatment. The present study shows that under LPS stimulation, a Th1 immune response was predominant; T-lymphocyte migration was significantly decreased with anti-α6β1 antibody pretreatment compared with anti-α4 antibody pretreatment. In previous studies, LPS from Escherichia coli was found to induce a Th1 response,43.Pulendran B. Kumar P. Cutler C.W. et al.Lipopolysaccharides from distinct pathogens induce different classes of immune responses in vivo.J Immunol. 2001; 167: 5067-5076Crossref PubMed Scopus (408) Google Scholar,44.Agrawal S. Agrawal A. Doughty B. et al.Cutting edge: different Toll-like receptor agonists instruct dendritic cells to induce distinct Th responses via differential modulation of extracellular signal-regulated kinase-mitogen-activated protein kinase and c-Fos.J Immunol. 2003; 171: 4984-4989Crossref PubMed Scopus (601) Google Scholar whereas LPS from Porphyromonas gingivalis and schistosome egg antigen induced Th2 responses.43.Pulendran B. Kumar P. Cutler C.W. et al.Lipopolysaccharides from distinct pathogens induce different classes of immune responses in vivo.J Immunol. 2001; 167: 5067-5076Crossref PubMed Scopus (408) Google Scholar,45.Cervi L. MacDonald A.S. Kane C. et al.Cutting edge: dendritic cells copulsed with microbial and helminth antigens undergo modified maturation, segregate the antigens to distinct intracellular compartments, and con
Referência(s)