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

TLDR

Excess extracellular matrix production drives peritoneal adhesions after surgery, with transforming growth factor‑β1 and hypoxia known to promote fibrosis. The study aimed to determine whether TGF‑β1 and/or hypoxia regulate type I and III collagen expression in human peritoneal mesothelial cells. Human mesothelial cells were cultured under 2 % O₂, treated with 1 ng ml⁻¹ TGF‑β1, or both, and collagen I/III mRNA levels were quantified by multiplex RT‑PCR. Hypoxia alone raised collagen III mRNA 7.2‑fold (to 9.4‑fold with TGF‑β1) while reducing collagen I mRNA; TGF‑β1 alone increased collagen III 8.4‑fold and decreased collagen I 0.3‑fold, with hypoxia also boosting TGF‑β1 mRNA 1.9‑fold, indicating hypoxia modulates ECM via a TGF‑β1‑dependent pathway.

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.