The expression patterns of peritoneal defensins.

BACKGROUND Local defense mechanisms are important for the integrity of the peritoneum, but few details are known about the expression patterns of antimicrobial proteins such as human defensin in normal and damaged peritoneum. METHODS Part A: The expression of different defensins in normal (n = 12), inflamed (n = 5), and metastatic peritoneum (n = 4) and in cultured human peritoneal mesothelial cells was analyzed using mRNA and immunohistochemistry. Part B: Using immunohistochemistry the expression of different defensins was analyzed in different subgroups: healthy controls (n = 25), patients with chronic appendicitis (n = 25) or acute appendicitis (n = 10), and end-stage renal disease patients (n = 25, with 15 on peritoneal dialysis). RESULTS Part A: Human neutrophil peptides (HNP) 1 and 3 and human beta-defensins (HBD) 1 to 3 mRNA were detected in peritoneal specimens. In addition, HNP1,3, HBD1, HBD2, and HBD3 proteins were detected using immunohistochemistry. Part B: HBD1 showed a constitutive expression in mesothelium, while HBD2 and HNP1,3 were associated with inflammation. Decreased expressions of HNP1,3 were observed in end-stage renal disease patients and in patients on peritoneal dialysis. CONCLUSIONS For the first time, the expression patterns of defensins in normal and damaged peritoneum have been described. The reduced expression of some defensins in end-stage renal disease is of potential clinical interest against the background of the frequent infective complications seen in peritoneal dialysis.