Peritoneal dialysate fluid composition determines heat shock protein expression patterns in human mesothelial cells

Background. Low biocompatibility of peritoneal dialysis fluids (PDF) contri butes to mesothelial injury. We investigated whether the heat shock protein s (HSP)-27, HSP-72, and HSP-90 are differentially induced upon exposure of mesothelial cells to PDF and whether this was affected by selective modulat ion of the physicochemical properties of PDF. Methods. Human mesothelial cells (Met5A and primary human mesothelial cells ) were exposed to acidic lactate and glucose-monomer based PDF (CAPD2 and C APD3), to control culture media, or to a neutral lactate and glucose-monome r-based PDF with reduced levels of glucose degradation products (BALANCE). Expression of HSP-27, HSP-72, and HSP-90 and cellular distribution of HSP-7 2 were assessed by Western blotting and immunocytochemistry. Results. Mesothelial cells exhibited strong constitutive expression of HSP- 27 and to a lesser extent HSP-72 and HSP-90. Exposure of the cells to CAPD2 and CAPD3 resulted in strong up-regulation of HSP-72. HSP-27 levels were s lightly increased, but HSP-90 levels were unchanged upon exposure to CAPD2 or CAPD3. In contrast, exposure of the cells to BALANCE did not affect HSP- 27 or HSP-72 expression. The acidic pH and glucose degradation products wer e found to be principal in mediating increased HSP-72 expression upon expos ure to PDF. Conclusions. Analysis of HSP expression represents a novel tool to assess b iocompatibility of PDF. Among the HSP investigated, HSP-72 is the most pred ictive and accurate parameter to assess mesothelial cell injury in the earl y phase of exposure to PDF.