Peritoneal Dialysis Fluid and Some of its Components Potentiate Fibrocyte Differentiation

Long-term peritoneal dialysis (PD) often results in the development of peritoneal fibrosis. In many other fibrosing diseases, monocytes enter the fibrotic lesion and differentiate into fibroblast-like cells called fibrocytes. We find that peritoneal tissue from short-term PD patients contains few fibrocytes, while fibrocytes are readily observed in the peritoneal membrane of long-term PD patients. The PD fluid Dianeal (Baxter Healthcare Corporation, Deerfield, IL, USA) contains dextrose, a number of electrolytes including sodium chloride, and sodium lactate. We find that PD fluid potentiates human fibrocyte differentiation in vitro and implicates sodium lactate in this potentiation. The plasma protein serum amyloid P (SAP) inhibits fibrocyte differentiation. Peritoneal dialysis fluid and sodium chloride decrease the ability of human SAP to inhibit human fibrocyte differentiation in vitro . Together, these results suggest that PD fluid contributes to the development of peritoneal fibrosis by potentiating fibrocyte differentiation.