Epidermal growth factor modifies the expression and function of extracellular matrix adhesion receptors expressed by peritoneal mesothelial cells from patients on CAPD.

BACKGROUND: Efficient peritoneal dialysis depends on an intact layer of mesothelial cells that line the peritoneal membrane. This layer is disrupted in patents on continuous ambulatory peritoneal dialysis during episodes of peritonitis (acute injury) and replaced by fibrous tissue during extended dialysis (chronic injury). Little is understood of human peritoneal mesothelial cell (HPMC) responses to wounding and episodes of peritonitis. METHODS: HPMC were harvested from spent peritoneal dialysis effluent and maintained under defined in vitro conditions. Adhesive interactions with extracellular matrix (ECM) molecules and chemotactic and wound-healing responses were measured in vitro using purified ECM molecules. RESULTS: HPMC express multiple functional cell receptors recognizing and binding to ECM molecules, including several members of the integrin family. HPMC exhibit directed migration in wound healing and chemotaxis assays with ECM molecules. Epidermal growth factor (EGF) stimulates a reversible change to a fibroblastic phenotype, accompanied by increased expression of beta1 integrins, particularly alpha2beta1, increased adhesion to type I collagen, and significantly greater HPMC migration on type I collagen in wound healing and chemotaxis assays. CONCLUSIONS: HPMC possess the migratory capacity to contribute to the efficient repair of damaged peritoneal membrane after acute injury, and growth factors, such as EGF, facilitate peritoneal membrane healing by augmenting cell adhesion and migration.     

Image analysis of remesothelialization following chemical wounding of cultured human peritoneal mesothelial cells: the role of hyaluronan synthesis

BACKGROUND: To understand what happens during the wound healing process of the mesothelium, we have developed an in vitro wounding model of cultured human peritoneal mesothelial cells (HPMCs) utilizing an image acquisition and analysis system. Using this system, cell mobility and hyaluronan synthesis were quantified and their interrelationship discussed. METHODS: 1N NaOH was used to create circular wounds in cultured HPMC monolayers, which were then exposed for 30 minutes to the peritoneal dialysis solutions or fetal calf serum (FCS)-free M199 culture medium, followed by incubation with 0.3% FCS/M199 culture medium for up to 96 hours. Digitalized microscopic date was captured every 30 minutes to quantify the wound healing process. In separate experiments, the HPMC monolayers were stained with biotin-conjugated hyaluronan-binding protein (B-HABP) at a regular time interval. RESULTS: Centripetal migration of the HPMCs into the wound area was the predominant process involved in wound repair with proliferation playing a secondary role. Two noticeable observations were made from the digital video movies: (1) cell mobility varied and was dependent upon the morphology and location of the cell relative to the wound edge, and (2) cell migration continued even after wound closure. Staining for B-HABP was confined to the remesothelialized area when wound closure was complete at 24 hours. At 48 hours after wound closure, the stained area was even more visible, although somewhat diffuse; thereafter, staining was reduced to almost background levels. CONCLUSION: The cell culture model of wound healing used in our study has enabled us to demonstrate quantitative image data of the cellular processes that occur during wound healing. We have been able to continuously observe cell migration, proliferation, and transformation. Synthesis and subsequent decomposition of hyaluronan appears to be related to the mobility of the wounded and intact HPMCs in this model system.     

High glucose levels inhibit focal adhesion kinase-mediated wound healing of rat peritoneal mesothelial cells

BACKGROUND: The peritoneum is progressively denuded of its mesothelial cell monolayer in patients on continuous ambulatory peritoneal dialysis (CAPD). These alterations of the mesothelium cause membrane dysfunction and progressive peritoneal fibrosis. Integrins regulate cell motility and play an important role in wound healing. We investigated the effects of high glucose on the regeneration process of the peritoneal mesothelial cell monolayer using cultured rat peritoneal mesothelial cells (RPMC). METHODS: The effects of glucose or mannitol on the regeneration of RPMC and formation of focal adhesions were examined by in vitro wound healing assay and immunocytochemistry, respectively. Activities of focal adhesion kinase (FAK) and its downstream p130Cas were examined by Western blotting. Effects of wild-type and dominant-negative FAK on RPMC migration were examined by a transient transfection assay. RESULTS: Cell migration over fibronectin (FN) was clearly inhibited in culture media containing high glucose (28 to 140 mmol/L). RPMC formed focal adhesions on FN in the presence of a regular glucose concentration (5.6 mmol/L); however, tyrosine phosphorylation of FAK and p130Cas and formation of focal adhesions observed by FAK and vinculin staining were substantially inhibited by high glucose. Mannitol also induced significant inhibitory effects, but these were milder than those of glucose. Transfection of dominant-negative FAK inhibited cell migration in a regular glucose concentration, whereas overexpression of wild-type FAK abrogated glucose-induced inhibition of cell migration. CONCLUSIONS: Our results demonstrate that high glucose concentrations as well as high osmolarity inhibit FAK-mediated migration of mesothelial cells, and suggest that dialysates containing high glucose concentrations may cause peritoneal damage by inhibiting wound healing of the mesothelial cell monolayer.     

Leptin augments myofibroblastic conversion and fibrogenic activity of human peritoneal mesothelial cells: a functional implication for peritoneal fibrosis.

BACKGROUND: Myofibroblastic conversion of mesothelial cells is proposed to play an important role in pathological changes following serosal membrane injury. METHODS: Human peritoneal mesothelial cells (HPMCs) were isolated and maintained in culture. The gene expression was assessed by RT-PCR. Activation of signal transduction was determined by western blot and densitometry. Morphological changes were observed by phase-contrast and electron microscopy. RESULTS: In vitro study showed that TGF-beta1-induced myofibroblastic growth of HPMCs was significantly enhanced in the presence of leptin. Augmented expression of alpha-smooth muscle actin, fibronectin and type I collagen mRNA in HPMCs induced by leptin were TGF-beta1-dependent, suggesting that leptin promoted peritoneal fibrogenesis through synergistic activation of the TGF-beta1 signaling system. Leptin and TGF-beta1 synergistically augmented activation of signalling components of mitogen-activated protein kinase (MAPK), STAT3 and Smad but did not modulate the expression of LEPR-B. CONCLUSION: Leptin may act as a profibrogenic TGF-beta1 activated cytokine in peritoneal bioenvironment associated with TGF-beta1 activated pathogenic processes.     

Involvement of TGF-beta signal for peritoneal sclerosing in continuous ambulatory peritoneal dialysis

BACKGROUND: Functional failure of the peritoneal membrane is the most serious problem in long-term continuous ambulatory peritoneal dialysis (CAPD). Transforming growth factor-beta (TGF-ss) is one of the key mediators of fibrosis in some organs, and is thought to be involved in peritoneal alterations. In this study, we examined the role of TGF-beta1/TGF-ss receptors for human peritoneal mesothelial cells (HPMCs) and fibroblasts, and their interactions in CAPD patients. METHODS: HPMCs were cultured for 48 h in a medium containing normal- dose glucose (7 mM), high-dose glucose (30 mM) and mannitol as an osmotic agent, equal to 30 mM glucose. Cell proliferation was observed using the Tetra Color One assay. The concentration of TGF-beta1 in culture supernatants was measured by enzyme-linked immunosorbent assay (ELISA). The expression of TGF-ss receptor types I and II was observed by flow cytometry. HPMCs and fibroblasts were co-cultured and assayed using transwell inserts in order to identify the effects of the high-concentration glucose solution. RESULTS: HPMC proliferation was inhibited by the high concentration of glucose but not by mannitol. The inhibition was abrogated by the neutralizing antibody for TGF-beta1. TGF-beta1 was induced by a high concentration of glucose but not by mannitol. The expression of both TGF-ss receptors was augmented in culture with the high concentration of glucose but not with mannitol. In the co-culture assay, the number of HPMCs was decreased and fibroblasts were significantly increased in culture with the high concentration of glucose. CONCLUSIONS: A high concentration of glucose induced a large amount of TGF-beta1 and enhanced the expression of TGF-ss receptors. HPMCs were sensitive to TGF-beta1 in response to a high concentration of glucose. These data suggest that TGF-beta1 from HPMCs exposed to a high concentration of glucose down-regulates the proliferation of HPMCs and accelerates peritoneal fibrosis.     

Peritoneal dialysis with solutions low in glucose degradation products is associated with improved biocompatibility profile towards peritoneal mesothelial cells.

BACKGROUND: In vitro experiments point to a better biocompatibility profile of new pH-neutral peritoneal dialysis fluids (PDFs) containing low levels of glucose degradation products (GDPs). The present study examines the impact on human peritoneal mesothelial cells (HPMCs) of equilibrated dialysates obtained during dialysis with either conventional or new PDFs. METHODS: Peritoneal dialysate was collected from 17 patients participating in a randomized, controlled, cross-over trial comparing a pH-neutral low-GDP solution (Balance) to a conventional solution (S-PDF). All patients were treated sequentially for 3 months with both PDFs. At the end of each treatment phase, peritoneal effluent was drained after a timed 10 h dwell. Samples of dialysate were then mixed with standard culture medium and added to in vitro cultures of HPMCs from healthy donors. Cells were assessed for proliferation, viability and cytokine release. RESULTS: Proliferation and viability of HPMCs were better preserved in the presence of effluent obtained during dialysis with Balance (P<0.046 and P<0.035, respectively). The proliferative response of HPMCs correlated with the concentration of fibronectin in dialysates (P = 0.0024). Effluent drained following a 3 month dialysis with Balance contained significantly increased levels of fibronectin (P = 0.004) and CA125 antigen (P = 0.0004) compared with S-PDF. There was no significant difference in constitutive and stimulated cytokine (IL-6, MCP-1, VEGF) synthesis by HPMCs treated with either Balance- or S-PDF-derived effluents. CONCLUSIONS: These results suggest that therapy with new pH-neutral low-GDP solutions contribute to an intraperitoneal milieu that improves mesothelial cell proliferation and viability. It may positively impact on the preservation of the peritoneal membrane integrity during long-term dialysis.     

Induction of hyaluronan metabolism after mechanical injury of human peritoneal mesothelial cells in vitro

BACKGROUND: Hyaluronan (HA) is an important extracellular matrix component that is involved in cell movement and tissue repair. In vertebrates, HA synthase genes (HAS 1, HAS 2, and HAS 3) that control the synthesis of HA have been identified. In this article, we investigated HA synthesis in the response of human peritoneal mesothelial cells (HPMCs) to injury. METHODS: The expression of HAS 1, HAS 2, and HAS 3 mRNA and the synthesis of [(3)H]-labeled HA were examined in an in vitro model of peritoneal mesothelial cell damage. The staining for uridine diphosphoglucose dehydrogenase, a key enzyme in the synthesis of HA, and biotinylated HA-binding protein was used to determine the cellular location of HA synthesis and its site of deposition. RESULTS: Growth-arrested human HPMCs expressed low levels of mRNA for HAS 2 and HAS 3 but not HAS 1. Following injury to the monolayer, HAS 2 was up-regulated by 6 hours, reaching maximal expression between 12 and 24 hours. In contrast, the expression of HAS 3 was down-regulated. During the same time period, synthesis of HA was increased in the injured monolayer. This synthetic activity appeared to be restricted to cells at the edge of the wound and to cells entering the wound. In a separate series of experiments, the addition of HA to the injured monolayer at a concentration range found in peritoneal fluid (50 to 3300 ng/mL) increased the migration of cells into the wound in a dose-dependent manner. CONCLUSIONS: These studies provide evidence that HA is an important component of peritoneal mesothelial cell migration. The results also suggest that in this process, there is differential regulation of HAS gene expression and that the synthesis of HA is limited to cells located at the leading edge of the wound.     

Expression of TGF-beta-induced matrix protein betaig-h3 is up-regulated in the diabetic rat kidney and human proximal tubular epithelial cells treated with high glucose

BACKGROUNDS: betaig-h3 is an extracellular matrix protein whose expression in several cell types is greatly increased by transforming growth factor-beta (TGF-beta). TGF-beta is believed to be involved in the development of diabetic nephropathy and thus we have assessed the possibility that betaig-h3 may be a downstream molecule in this pathogenic process. METHODS: Immunoblotting and immunohistochemistry were done using an antibody against mouse betaig-h3 protein. betaig-h3 and TGF-beta concentrations were measured by enzyme-linked immunosorbent assay (ELISA). Cell adhesion and migration were assessed by measuring activity of N-acetyl-beta-d-glucosaminidase and using a transwell plate, respectively. RESULTS: Immunohistochemistry revealed that betaig-h3 occurs mainly in the basement membrane of proximal tubules, particularly the S3 segment but also to lesser extents in the basement membranes of the cortical thick ascending limb cells and the parietal glomerular epithelial cells in Bowman's capsule. Immunoblotting revealed that approximately 68 kD bands were seen only in the cortex + the outer stripe of the outer medulla. Rats with streptozotocin (STZ)-induced diabetes exhibited a marked and sustained increase in renal betaig-h3 abundance. This was mirrored by urinary betaig-h3 levels. In vitro experiments with human primary renal proximal tubular epithelial cells revealed that their expression of betaig-h3 was greatly increased by either TGF-beta or glucose. High glucose levels also stimulated TGF-beta production by renal proximal tubular epithelial cells and the high glucose-induced betaig-h3 expression was almost completely blocked by anti-TGF-beta antibody. betaig-h3 mediated renal proximal tubular epithelial cells adhesion and migration. CONCLUSION: betaig-h3 may be important in the development of diabetic nephropathy. Furthermore, the level of urinary betaig-h3 may be useful as an early marker reflecting disease onset and progression.     

Expression of Na＋-dependent glucose transporter 1 and 2 in peritoneum of peritoneal dialysis patients

Objective To investigate the expression of Na＋-dependent glucose transporter (SGLT) in human peritoneal mesothelial cells (HPMCs) and vascular endothelial cells in peritoneal tissues of peritoneal dialysis (PD) patients at different dialysis vintages, and to study the influence of high glucose treatment on the expression of SGLT1 and SGLT2 in primary HPMCs. Methods According to the dialysis vintage, PD patients were divided into four groups: 0 year group, ＞0-2 years group, ＞2-4 years group and＞4 years group. HE and Masson staining were used to observe the morphologic changes of peritoneal tissues in PD patients. Immunohistochemical staining was used to detect the expression of SGLT1 and SGLT2 in peritoneal HPMCs and vascular endothelial cells. The primary HPMCs were extracted from the peritoneal dialysis fluid, and treated with high-glucose or high-mannitol for 0 h, 12 h, 24 h, 48 h, 72 h and 96 h. Western blotting was used to investigate the SGLT1 and SGLT 2 expression in HPMCs. The cell viability was detected by using cell counting kit (CCK-8). Results HE and Masson staining showed that the peritoneum of PD patients in 0 year group was smooth and continuous, with a flat layer of HPMCs. The number of HPMCs in＞0-2 years group decreased compared with that in 0 year group. The HPMCs size increased in＞2-4 years group, but the number decreased. The peritoneum of PD patients in＞4 years group was significantly thickened and fibrotic, and HPMCs almost disappeared. Immunohistochemical staining showed that the expression of SGLT1 and SGLT2 in HPMCs gradually decreased with the increase of dialysis vintage (P＜0.05). The wall of peritoneal blood vessel became thicken, but the expression of SGLT1 and SGLT2 was not statistically different among four groups (P＞0.05). SGLT1 in primary HPMCs could be up-regulated (0 h, 12 h and 24 h), and then down-regulated (24 h, 48 h, 72 h, 96 h) with the treatment of 60 mmol/L glucose (P=0.029); but there was no significant difference of SGLT2. Conclusion High glucose and the increase of dialysis vintage can reduce the number and the viability of HPMCs, and decrease the expression of SGLT1 and SGLT2, but there was no significant influence on SGLT1 and SGLT2 in peritoneal vascular endothelial cells.     

Cellular stress-response modulators in the acute rat model of peritoneal dialysis

Cytotoxicity of peritoneal dialysis fluids (PDF) not only results in cellular injury, but also induces heat-shock proteins (HSP), the main effectors of the cellular stress response. This study investigated effects of modulation of mesothelial HSP expression on peritoneal membrane integrity during acute PDF exposure. In the acute in vivo rat model of peritoneal dialysis (PD), either the HSP coinducer indomethacin or the HSP suppressor quercetin was added to standard PDF (CAPD 3, Fresenius, Germany). HSP-72 expression, number of detached mesothelial cells, and peritoneal protein loss were evaluated at the end of a 4-h dwell time. Compared with pure PDF exposure, addition of indomethacin resulted in increased expression of mesothelial HSP-72, reduced mesothelial cell exfoliation, and reduced peritoneal protein loss. Addition of quercetin resulted in decreased expression of HSP-72, increased mesothelial cell exfoliation, and higher peritoneal protein loss. Differences were statistically significant between indomethacin-treated and quercetin-treated rats. Mesothelial HSP expression was related to markers of peritoneal membrane integrity upon in vivo PDF exposure, consistent with HSP-mediated cytoprotection. These data clearly demonstrate the potential for clinically feasible pharmacologic interventions with the cellular stress response as a novel therapeutic approach to improve PD outcome.     

PI3K/Akt signaling regulates epithelial-mesenchymal transition of peritoneal mesothelial cells in peritoneal dialysis

Objective To investigate the role of PI3K/Akt signaling in the regulation of epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) in peritoneal dialysis in vitro and in vivo. Methods The level of Phosphorylated serine/threonine kinase Akt and the expression of EMT associated gene and protein, including ZO-1, Vimentin and FN, were measured in mice EMT model. In vitro study, phosphorylation level and nuclear translocation of Akt, ZO - 1 and Vimentin expression induced by TGF - β1 in human peritoneal mesothelial cells (HPMCs) were also observed. Moreover, HPMCs were pre-treated by one of PI3K/Akt inhibitor, LY294002, or transfected with dominant-negative Akt plasmid to inhibit PI3K/Akt signaling, then analyzed its effect on Zo-1 and Vimentin expression induced by TGF-β1. Results Compared with the control, thickened parietal peritoneum and remarkable decrease in mRNA and protein of the epithelial marker ZO-1, and notable increased in the expression of mesenchymal markers Vimentin and FN were observed in PD mice (all P＜0.01). Moreover, the phosphorylation of Akt also significantly increased under above condition (P＜ 0.01). In vitro study, with the stimulation of TGF-β1, the expression of Zo-1 was down-regulated, while the expression of Vimentin increased (all P＜0.01). In addition, TGF-β1 remarkably increased pAkt in HPMCs (all P＜0.01) in dose-dependent. However, LY294002 and DN-Akt dramatically inhibited the vimentin expression in HPMCs induced by TGF-β1 after inhibition of pAkt. On the other hand, the expression of ZO - 1 also was restored (P＜0.01). Conclusion PI3K/Akt signaling is involved in EMT of peritoneal mesothelial cells in peritoneal dialysis, and may be a new target for the prevention and treatment of peritoneal fibrosis during PD.     

Myofibroblast transdifferentiation of mesothelial cells is mediated by RAGE and contributes to peritoneal fibrosis in uraemia.

BACKGROUND: Uraemia is associated with fibrosis of the peritoneal membrane, even prior to the start of peritoneal dialysis. Increased carbonyl stress and the resultant formation of advanced glycation end-products (AGEs) are potentially involved. The interaction of AGEs with their cell surface receptor for AGE (RAGE) induces sustained cellular activation, including the production of the fibrogenic growth factor-beta (TGF-beta). TGF-beta is pivotal in the process of epithelial-to-mesenchymal transition with the acquisition of myofibroblast characteristics. We investigated whether antagonism of RAGE prevents uraemia-induced peritoneal fibrosis. In addition, we examined whether myofibroblast transdifferentiation of mesothelial cells contributes to peritoneal fibrosis in uraemia. METHODS: Uraemia was induced in rats by subtotal nephrectomy. Uraemic and age-matched sham-operated rats were treated for 6 weeks with neutralizing monoclonal anti-RAGE antibodies or placebo. Expression of AGE, RAGE, cytokeratin and alpha-smooth muscle actin was evaluated using immunohistochemistry. TGF-beta expression was examined with immunostaining and western blotting, and Snail expression with western blotting. Fibrosis was quantified with a picro-sirius red staining and measurement of the hydroxyproline content of the tissue. RESULTS: Uraemia resulted in the accumulation of AGE, up-regulation of RAGE and TGF-beta and the development of interstitial fibrosis and vascular sclerosis in the peritoneal membrane. Prominent myofibroblast transdifferentiation of mesothelial cells was identified by colocalization of cytokeratin and alpha-smooth muscle actin in submesothelial and interstitial fibrotic tissue. The antagonism of RAGE prevented the up-regulation of TGF-beta, epithelial-to-mesenchymal transition of mesothelial cells and fibrosis in uraemia. CONCLUSION: The ligand engagement of RAGE and the subsequent up-regulation of TGF-beta induces peritoneal fibrosis in chronic uraemia. The process may be mediated by the conversion of mesothelial cells into myofibroblasts.     

Effect of glucose on intercellular junctions of cultured human peritoneal mesothelial cells

During continuous ambulatory peritoneal dialysis, the peritoneum is directly and continuously exposed to unphysiologic peritoneal dialysis fluid; the resulting mesothelial damage has been suggested to cause loss of ultrafiltration and dialysis efficacy. The present study investigated the effect of a high glucose concentration on cultured human peritoneal mesothelial cells to clarify the cause of decreased dialysis efficacy during prolonged peritoneal dialysis. High glucose caused a concentration-dependent decrease in cell proliferation, damage to the intercellular junctions, and excess production of transforming growth factor-beta (TGF-beta). The levels of intercellular junctional proteins (ZO-1, E-cadherin, and beta-catenin) were decreased, and immuno-staining by anti-ZO-1 and anti- beta-catenin antibodies became weaker and often discontinuous along the cell contour. Mannitol had similar but weaker effects at the same osmolality, and an anti-TGF-beta neutralizing antibody reduced the effects of high glucose. Therefore, these effects were induced not only by glucose itself but also by hyperosmolality and by a glucose-induced increase of TGF-beta. These findings suggest that the peritoneal mesothelium is damaged by prolonged peritoneal dialysis using high glucose dialysate and that impairment of the intercellular junctions of peritoneal mesothelial cells by high glucose dialysate induces peritoneal hyperpermeability and a progressive reduction in dialysis efficacy.     

In vitro and in vivo models for peritonitis demonstrate unchanged neutrophil migration after exposure to dialysis fluids.

BACKGROUND: Recurrent infections in peritoneal dialysis (PD) patients may alter the abdominal wall resulting in an impairment of its dialysis capacity. In this study we investigated both in vitro and in vivo the effects of mesothelial exposure to dialysis fluids on the migration of neutrophils and their capacity to clear a bacterial infection. METHODS: First, we evaluated neutrophil migration in an in vitro transwell model for the peritoneal membrane with monolayers of primary human mesothelial cells (MC) on the lower side and primary human endothelial cells (EC) on top of the same transwell membrane, upon exposure of MC to PD fluid (PDF)-derived components. In addition to this in vitro model, we combined chronic peritoneal exposure to PDF with a peritoneal infection model in the rat. We investigated the kinetics of the chemokine response, neutrophil recruitment and bacterial clearance. RESULTS: Known chemoattractants, such as fMLP and IL-8, strongly increased neutrophil migration across both cell layers in the in vitro model of the peritoneal membrane. Pre-incubation of the MC layer for 48 h with 55 mM glucose, a combination of two glucose degradation products, methylglyoxal and 3-deoxyglucosone, or conventional dialysis fluid (1:4 dilution), however, did not change the IL-8-induced migration of neutrophils. In concert with this finding we demonstrated an unchanged MC expression of ICAM-1 and VCAM-1 after these pre-treatments. Unexpectedly, chronic i.p. exposure to conventional PDF or a recently developed lactate/bicarbonate-buffered PDF in a rat peritoneal exposure model strongly hampered the chemokine response upon bacterial challenge. Nevertheless, neutrophil recruitment and bacterial clearance were effective and did not differ from rats not pre-exposed to PDF. CONCLUSIONS: We conclude that exposure of MC to PDF does not hamper the recruitment of functional neutrophils upon challenge.     

Integrins mediate adherence and migration of T lymphocytes on human peritoneal mesothelial cells

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 alpha6beta1 and alpha4beta1. Further, the migration of Th1 cell across human mesothelial cell monolayers grown on transwell surfaces was reduced by anti-alpha6beta1 integrin antibody while that of Th2 cell was inhibited by an anti-alpha4 integrin antibody. Pretreatment with either lipopolysaccharide or rapid response peritoneal dialysis effluent stimulated T cell migration and this was significantly decreased by the alpha6beta1 compared to the alpha4 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.