Regulation of expression of tissue plasminogen activator and plasminogen activator inhibitor-1 by dichloroacetic acid in human fibroblasts from normal peritoneum and adhesions

Objective: As part of our ongoing studies to understand the biologic mechanisms of wound repair that lead to postoperative adhesions, we have identified characteristics of an adhesion phenotype that differs between fibroblasts that are obtained from human normal peritoneum and adhesions. In this study, we sought to examine whether stimulation of aerobic metabolism would alter differential expression of tissue plasminogen activator and plasminogen activator inhibitor-1, thereby creating a milieu likely to be less favorable to postoperative adhesion development. To examine this issue, we used a compound, dichloroacetic acid, that stimulates the pyruvate dehydrogenase complex, which causes pyruvate to be metabolized in the Kreb's cycle rather than being converted into lactate, thereby switching anaerobic to aerobic metabolism. Study design: Human fibroblasts from normal peritoneum and adhesions were cultured in the absence or presence of dichloroacetic acid (100 μg/mL) for 24 hours, under normal and hypoxic (2% O₂) conditions. Real-time reverse transcriptase-polymerase chain reaction of tissue plasminogen activator, plasminogen activator inhibitor-1, and a housekeeping gene β-actin was performed with messenger RNA that was extracted from all treatment points. Results: Dichloroacetic acid stimulated normal peritoneal fibroblast tissue plasminogen activator messenger RNA expression under hypoxic conditions. In adhesion fibroblasts, dichloroacetic acid treatment enhanced tissue plasminogen activator messenger RNA expression under both normoxic and hypoxic conditions. Plasminogen activator inhibitor-1 messenger RNA expression was unaltered by dichloroacetic acid in normoxic normal peritoneal fibroblasts; but during culture under hypoxic conditions, dichloroacetic acid reduced plasminogen activator inhibitor-1 messenger RNA expression. Similarly, in adhesion fibroblasts, dichloroacetic acid reduced plasminogen activator inhibitor-1 messenger RNA expression under both normoxic and hypoxic conditions. As a result, in normal peritoneal fibroblasts under hypoxic conditions and in adhesion fibroblasts under normoxic and hypoxic conditions, dichloroacetic acid greatly increased the tissue plasminogen activator/plasminogen activator inhibitor-1 ratios. Conclusion: These findings confirm that fibroblasts from adhesions are characterized by reduced tissue plasminogen activator and increased plasminogen activator inhibitor-1 production. These observations are extended to show the stimulation of oxidative metabolism by dichloroacetic acid increases tissue plasminogen activator expression under hypoxic conditions. Dichloroacetic acid reduces plasminogen activator inhibitor-1 production by hypoxic normal peritoneal fibroblasts and adhesion fibroblasts under hypoxic conditions. The resultant increases in the tissue plasminogen activator/plasminogen activator inhibitor-1 ratios would favor the development of a fibrinolytic milieu, which would be expected potentially to limit postoperative adhesion development. Thus, regulation of metabolic activity of peritoneal cells may provide a target for future interventions for the reduction of the development of postoperative adhesions, particularly as intervention relates to the healing of peritoneal sites that previously had adhesions. (eg, sites of potential adhesion reformation).