Modulation of the expression of tissue plasminogen activator and its inhibitor by hypoxia in human peritoneal and adhesion fibroblasts

Objective: To determine whether normal peritoneal and adhesion fibroblasts express tissue plasminogen activator (tPA) and plasminogen activator inhibitor (PAI-I) and whether their expression is regulated by oxygen. Design: Prospective experimental study. Setting: University medical center. Patient(s): Cultures of human fibroblasts established from peritoneal and adhesion tissues. Intervention(s): Hypoxia treatment of the primary cultured fibroblasts. Main Outcome Measure(s): We have used the multiplex reverse transcription polymerase chain reaction (RT-PCR) technique to determine the effect of hypoxia on the expression of tPA and PAI-I in normal peritoneal (NPF) and adhesion (ADF) fibroblasts. Cultures of NPF and ADF were exposed to hypoxia (2% O₂) for 24 hours. RNA was extracted from cells and subjected to multiplex RT-PCR to quantitate relative changes in mRNA levels of tPA and PAI-I in response to hypoxia treatment. Result(s): Basal tPA mRNA levels are present in both NPF and ADF and were 45% higher in NPF than ADF. Hypoxia decreased tPA in both NPF and ADF by 74% and 95%, respectively. Basal PAI-I mRNA levels were 64% higher in ADF than in NPF. Hypoxia increased PAI-I mRNA levels by 67% and 53% in NPF and ADF, respectively. Conclusion(s): Plasminogen activator activity (PAA) of the peritoneum does not solely reside in the mesothelial cells, as previously identified, but also exists within fibroblasts, thus providing the potential to resolve postoperative fibrinous collections even at sites at which the mesothelial cells have been injured, removed, or destroyed. Furthermore, PAA in fibroblasts is regulated by oxygen; creation of a hypoxic state markedly attenuates PAA, thereby leading to adhesion development.