Alteration of type I and III collagen expression in human peritoneal mesothelial cells in response to hypoxia and transforming growth factor‐β1

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Abstract
Overexpression and accumulation of extracellular matrix is central to peritoneal adhesion formation following surgically induced tissue trauma. Transforming growth factor-β1 and hypoxia have been implicated in tissue fibrosis and postoperative adhesion formation. To extend this observation we examined whether transforming growth factor-β1 and/or hypoxia regulate the expression of type I and III collagen in human peritoneal mesothelial cells. Cultured human mesothelial cells were maintained under hypoxia (2% oxygen), or treated with transforming growth factor-β1 (1 ng/ml) or a combination of hypoxia and transforming growth factor-β1. Total cellular RNA from treated and untreated cells were collected and subjected to multiplex reverse transcription/polymerase chain reaction to quantitate collagen I and III mRNA levels in response to these treatments. The results indicate that 6 hours of hypoxia increased collagen III mRNA by 7.2 fold which was further increased to 9.4 fold following transforming growth factor-β1 treatment; in contrast collagen I mRNA decreased by 0.42 fold which was further decreased by 0.3 fold following transforming growth factor-β1 treatment. Transforming growth factor-β1 treatment under normal conditions resulted in an 8.4-fold increase and a 0.3-fold decrease in collagen III and I mRNA levels, respectively. Hypoxia treatment also resulted in a 1.9-fold increase in transforming growth factor-β1 mRNA level compared with control. The ratio of type III/I collagen was increased in response to transforming growth factor-β1 treatment under hypoxic condition. In conclusion, the data suggest that hypoxia may modulate extracellular matrix production by human mesothelial cells via a transforming growth factor-β1 dependent mechanism.