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

Abstract

Objective: While the pathophysiology leading to adhesion development remains poorly understood, a pivotal role has been ascribed to the ability of plasminogen activator activity (PAA) of the mesothelial cells lining the peritoneal cavity to limit adhesion development. Injury to the peritoneum, with loss of the mesothelial cells and reduction of PAA exposes underlying fibroblasts, and frequently results in adhesions.Design: The objective of this study was 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.Materials/Methods: We have utilized the multiplex 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. Primary cultures of NPF and ADF were exposed to hypoxia (2% O2) for 24 hrs. Total RNA was extracted from cells and subjected to multiplex RT/PCR to quantitate relative change in mRNA levels of tPA and PAI-I in response to hypoxia treatment.Results: Basal tPA mRNA levels were 45% higher in NPF than ADF. Hypoxia decreased tPA in both NPF and ADF by 70% and 95%, respectively. Basal PAI-I mRNA levels were 64% higher in ADF than NPF. Hypoxia increased PAI-I mRNA levels by 67% and 53% in NPF and ADF, respectively.Conclusions: PAA of the peritoneum does not solely reside in the mesothelial cells, but also exists within fibroblasts, thus providing the potential to resolve postoperative fibrinous collections even at sites at which the mesothelial cells have been removed or destroyed. Furthermore, PAA in fibroblasts is regulated by oxygen; creation of a hypoxic state (as occurs with suture ligation, electrosurgery, etc.) markedly attenuates PAA, thereby leading to adhesion development. Objective: While the pathophysiology leading to adhesion development remains poorly understood, a pivotal role has been ascribed to the ability of plasminogen activator activity (PAA) of the mesothelial cells lining the peritoneal cavity to limit adhesion development. Injury to the peritoneum, with loss of the mesothelial cells and reduction of PAA exposes underlying fibroblasts, and frequently results in adhesions. Design: The objective of this study was 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. Materials/Methods: We have utilized the multiplex 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. Primary cultures of NPF and ADF were exposed to hypoxia (2% O2) for 24 hrs. Total RNA was extracted from cells and subjected to multiplex RT/PCR to quantitate relative change in mRNA levels of tPA and PAI-I in response to hypoxia treatment. Results: Basal tPA mRNA levels were 45% higher in NPF than ADF. Hypoxia decreased tPA in both NPF and ADF by 70% and 95%, respectively. Basal PAI-I mRNA levels were 64% higher in ADF than NPF. Hypoxia increased PAI-I mRNA levels by 67% and 53% in NPF and ADF, respectively. Conclusions: PAA of the peritoneum does not solely reside in the mesothelial cells, but also exists within fibroblasts, thus providing the potential to resolve postoperative fibrinous collections even at sites at which the mesothelial cells have been removed or destroyed. Furthermore, PAA in fibroblasts is regulated by oxygen; creation of a hypoxic state (as occurs with suture ligation, electrosurgery, etc.) markedly attenuates PAA, thereby leading to adhesion development.