Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Biochemistry

Supervisor

O'Gorman, David B.

Abstract

Palmar fascia fibrosis (Dupuytren’s disease or DD), can cause permanent palmar-digital contractures. There are currently no effective treatments for DD. We have previously reported a DD-associated increase in the expression of WT1, encoding a transcription factor, Wilms Tumor 1 (WT1). We demonstrate that fibroblasts derived from fibrotic palmar fascia of DD patients constantly express an isoform of WT1, AWT1, unlike syngeneic pre-fibrotic (PF) or allogeneic normal control (CT) fibroblasts that only express AWT1 in response to pro-inflammatory stimuli. Adenoviral transduction and constant expression of AWT1 in PF and CT fibroblasts induced the expression of genes encoding pro-inflammatory cytokines and cytokine receptors. Co-culturing AWT1 expressing PF and CT fibroblasts with a monocyte cell line, THP-1, induced pro-inflammatory cytokine responses and the formation of a pro-inflammatory milieu. These data are consistent with the hypothesis that the constant expression of AWT1 in DD fibroblasts induces a local pro-inflammatory microenvironment that promotes fibrosis development.

Summary for Lay Audience

The focus of this thesis is palmar fascia fibrosis, also known as Dupuytren’s Disease (DD). The palmar fascia is a layer of connective tissue that lies below the skin of the palm where it protects the underlying nerves, blood vessels and bones of the hands. DD is characterized by the formation of abnormal scar tissue (fibrosis) in the palmar fascia that can cause permanent contracture of the affected digits, resulting in loss of dexterity and reduced quality of life. Unfortunately, there are no truly effective treatments for DD, as current therapies are associated with high rates of disease recurrence. Previous work in the O’Gorman laboratory has identified an increase in the expression of a transcription factor, Wilms’ Tumor 1 (WT1), in contracture tissues from DD patients. Transcription factors are proteins that regulate the expression of genes, and abnormal transcription factor activity can lead to the development of diseases, such as cancers and fibroses. WT1 was first identified in a pediatric cancer but has since been identified in other cancers. Interestingly, WT1 appears to play multiple, even apparently contradictory, roles in the development of different cancers. This complexity may be explained by the existence of multiple versions (isoforms) of WT1, the results of alternative splicing in, and/or alternative start sites for, WT1 mRNA transcripts.

Three major findings are described in this thesis: 1) hypercontractile cells that cause palmar fascia contractures, myofibroblasts, constantly express an isoform of WT1, AWT1, that can be induced in fibroblasts derived from visibly non-fibrotic palmar fascia by pro-inflammatory molecules, 2) constant expression of AWT1 in fibroblasts derived from visibly non-fibrotic palmar fascia promotes the expression of pro-inflammatory cytokines and cytokine receptors, and 3) co-cultures of fibroblasts expressing AWT1 with THP-1 cells, which are derived from human immune system cells called monocytes, modify THP-1 cell gene expression and the secretion of pro-inflammatory molecules. These findings are consistent with the hypothesis that constant expression of AWT1 in DD promotes chronic inflammation in the palmar fascia. As WT1 is currently a therapeutic target for various cancers, it may be possible to cross-purpose these drugs as a novel treatment for DD.

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