Abstract: SA-PO943
Direct Interaction of Mesothelial Cells with Macrophages via Stalked Fractalkine Promotes Dialysate Induced Peritoneal Fibrosis
Session Information
- Dialysis: Peritoneal Dialysis - III
October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Dialysis
- 703 Dialysis: Peritoneal Dialysis
Authors
- Helmke, Alexandra, Hannover Medical School, Hannover, Germany
- Nordlohne, Johannes, Hannover Medical School, Hannover, Germany
- Balzer, Michael S., Hannover Medical School, Hannover, Germany
- Hiss, Marcus, Hannover Medical School, Hannover, Germany
- Shushakova, Nelli, Nephrology and Hypertensiology, Hannover, Germany
- Haller, Hermann G., Hannover Medical School, Hannover, Germany
- Von Vietinghoff, Sibylle, Hannover Medical School, Hannover, Germany
Background
Fibrosis limits the use of peritoneal dialysis (PD) as renal replacement therapy. PD solution induces mesothelial cell activation and macrophage accumulation in the peritoneal wall. Macrophages highly express chemokine receptor CX3CR1. Its ligand fractalkine (CX3CL1) exists in a stalked surface-bound and a soluble form. This study addressed their role in peritoneal fibrosis.
Methods
Wildtype and CX3CR1 deficient mice received dialysis solution for human use via a peritoneal catheter for six weeks and tissues were analyzed by histology. Murine and human primary cells were investigated using a combination of qPCR, ELISA, flow cytometry and confocal microscopy.
Results
Human and murine peritoneal mesothelial cells expressed surface-bound and secreted fractalkine/CX3CL1. During experimental PD treatment in mice, CX3CL1 increased on the peritoneal membrane. Cytokines TNFα, IL-1β and TGFβ markedly induced CX3CL1 expression by mesothelial cells in vitro. In addition, direct co-culture with CX3CR1-competent macrophages induced CX3CL1 and also TGFβ, a main promoter of fibrosis. The increase of CX3CL1 and TGFβ in direct macrophage-mesothelial coculture was no longer observed in transwell co-cultures and also disappeared in direct coculture with CX3CR1 deficient macrophages, indicating a role for cellular CX3CR1-CX3CL1 interaction. TGFβ increased macrophage CX3CR1 expression and Increased CX3CR1 was observed during PD treatment. Wildtype mice developed significantly more peritoneal fibrosis than CX3CR1 deficient animals. Peritoneal dialysis solution directly induced macrophage IL-1β, one of the mesothelial CX3CL1-promoting cytokines, thus providing a mechanism of initiation for this pro-fibrotic interaction loop.
Peritoneal dialysis patients’ peritoneum expressed more CX3CL1 than untreated tissue and CX3CR1 was higher in serum of patients that recently started PD than in controls, providing evidence of relevance in the human situation.
Conclusion
PD solution initiates a pro-fibrotic loop of mesothelial CX3CL1 binding to macrophage CX3CR1 that promote peritoneal fibrosis in vivo. Similar observations in human cells suggest that CX3CR1-CX3CL1 interaction should be investigated further as a new therapeutic angle in peritoneal fibrosis.