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Leukocyte migration across human peritoneal mesothelial cells is dependent on directed chemokine secretion and ICAM-1
F K Li1, A Davenport, R L Robson
1Institute of Nephrology, University of Wales College of Medicine, Cardiff Royal Infirmary, United Kingdom.
Background:
Leukocyte migration into the peritoneal cavity is a diagnostic feature of peritonitis in patients treated with peritoneal dialysis (PD). While neutrophil (PMN) influx is characteristic of the acute phase of peritoneal infection, significant mononuclear cell (MNC) infiltration, occurs throughout the whole period of infection. Recent data suggests that human peritoneal mesothelial cell (HPMC) adhesion molecule expression and the synthesis of chemotactic cytokines may be important in the process.
Methods:
In the present study we have examined, the regulation and directed secretion of chemokines (IL-8, MCP-1 and RANTES) and the basolateral to apical migration of unstimulated leukocytes across mesothelial cell monolayers using an in vitro model where HPMC were grown on the porous membrane of tissue culture inserts. Separate experiments have defined the importance of chemokine synthesis and ICAM-1 expression in the transmigration process.
Results:
Apical stimulation of HPMC with IL-1 beta or TNF alpha resulted in a time and dose dependent up-regulation of IL-8, MCP-1 and RANTES mRNA expression and synthesis. This secretion was predominately into the apical compartment (> 85%) with all chemokines. Apical pre-stimulation of HPMC resulted in a dose- and time-dependent migration of both PMN and MNC across HPMC. Neutrophil migration was significantly reduced in the presence of appropriate concentrations of polyclonal IL-8 antibody (IL-1 beta (100 pg/ml) 153 +/- 12 versus anti-IL-8 (100 ng/ml) 71 +/- 7 (X 10(3)) PMN, N = 6, P < 0.02) and in the presence of anti-ICAM-1 F(ab)'2 fragments or soluble ICAM-1. Constitutive and cytokine stimulated mononuclear cell migration was significantly reduced in the simultaneous presence of polyclonal MCP-1 or RANTES antibody.
Conclusions:
These data demonstrate that HPMC synthesize IL-8, MCP-1 and RANTES in response to inflammatory cytokines. HPMC-derived C-x-C and C-C chemokines might contribute to the intra-peritoneal recruitment of leukocytes during peritoneal inflammation.
Insights
Human peritoneal mesothelial cells (HPMC) release chemokines like IL-8, MCP-1, and RANTES, which attract leukocytes during peritoneal dialysis-related inflammation. This study shows HPMC-derived chemokines are key drivers of leukocyte migration in peritonitis.
Area of Science:
- Immunology
- Cell Biology
- Nephrology
Background:
- Leukocyte migration into the peritoneal cavity is a hallmark of peritonitis in patients undergoing peritoneal dialysis (PD).
- While neutrophils (PMN) dominate acute inflammation, mononuclear cells (MNC) infiltrate throughout the infection period.
- Human peritoneal mesothelial cells (HPMC) and their secreted factors are implicated in leukocyte recruitment.
Purpose of the Study:
- To investigate the regulation and secretion of chemokines (IL-8, MCP-1, RANTES) by HPMC.
- To assess the role of HPMC-derived chemokines and ICAM-1 in leukocyte transmigration across mesothelial cell monolayers.
Main Methods:
- An in vitro model using HPMC cultured on porous membranes was employed.
- HPMC were stimulated with IL-1 beta or TNF alpha to analyze chemokine mRNA expression and protein synthesis.
- Leukocyte migration across HPMC monolayers was quantified, and the effects of chemokine antibodies and ICAM-1 inhibition were evaluated.
Main Results:
- IL-1 beta and TNF alpha induced a time- and dose-dependent increase in IL-8, MCP-1, and RANTES expression and secretion by HPMC, primarily into the apical compartment.
- Pre-stimulation of HPMC enhanced PMN and MNC migration in a dose- and time-dependent manner.
- Neutrophil migration was reduced by anti-IL-8 antibodies and anti-ICAM-1 agents, while MNC migration was inhibited by anti-MCP-1 and anti-RANTES antibodies.
Conclusions:
- HPMC synthesize and secrete IL-8, MCP-1, and RANTES in response to inflammatory cytokines.
- These HPMC-derived chemokines (C-x-C and C-C) play a significant role in the intra-peritoneal recruitment of leukocytes during peritoneal inflammation.