Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement
Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.
Absence of Epithelial to Mesenchymal Transition Despite Activation of Keratinocytes in Scleroderma Skin.
Buniak, Joanna Nikitorowicz, Shiwen, Xu, Abraham, David J., Denton, Christopher D., DBE, Carol M. Black, Stratton, Richard J.
We have recently shown that scleroderma (SSc) epithelial cells exhibit an activated phenotype similar to wound healing. The interplay between keratinocyte-fibroblast is important in health and disease including epithelial to mesenchymal transition (EMT). EMT is regarded as an important mechanism potentially contributing to lung, liver, and kidney fibrosis. In the SSc epidermis we found active HGF signalling via c-Met and SMAD phosphorylation consistent with TGFb signalling, both mechanisms implicated in driving EMT. Also we found increased vimentin levels in whole skin biopsy by proteomics. Therefore, we decided to look for evidence of EMT in the skin of scleroderma patients to determine if the skin fibrosis in scleroderma might involve EMT process.
Forearm skin biopsies taken from scleroderma patients diffuse subset (n=6) and age matched healthy controls (HC) (n=6) were analysed by immunohistochemical staining using antibodies against epithelial markers, K14 and E-cadherin as well as mesenchymal cell and cellular motility markers such as: vimentin, S100A4/FSP-1, a-SMA. Collagen IV was also identified in the sections to determine integrity of the basement membrane. The epidermal thickness and cell area was measured using Axiovision 4.8 software.
Immunohistochemistry results showed activated skin phenotype. Epidermal thickness was increased from 51.27 mm in HC to 88.85 mm in SSc skin, (p=0.005). The mean area of basal cells was 73.37 mm2 in HC and 111.71 mm2 in SSc (p=0.0016). While spinous layer keratinocytes were 89.26 mm2 in healthy control and 173.6 mm2 in systemic sclerosis (p=0.0038). However, higher numbers of ki67 positive cells in SSc epidermis (8.48) were not significant (p=0.08) when compared with HC (5.62). We did not observe any loss of E-cadherin or gain of vimentin in basal keratinocytes. However, healthy control sub-epidermal cells in a 50mm area adjacent to epidermis had increased vimentin staining. The collagen IV layer in the basal membrane was not compromised. Although we observed increased levels of FSP-1 expression in scleroderma skin when compared with healthy control skin, the level of smad2/3 activation in the area showed no difference.
Our results indicate that despite keratinocytes activation and HGF signalling, EMT is not taking place in scleroderma skin. Although, FSP-1 was increased the marker is not specific to fibroblasts and also detects dendritic cells and macrophages. EMT process is an important step in tumour development and the findings are consistent with the clinical observation that skin cancers are not seen at increased frequency in scleroderma patients. However, more investigations should be done to fully explore the cell and molecular mechanisms underlying the activated epidermis seen in SSc.
To cite this abstract, please use the following information:
Buniak, Joanna Nikitorowicz, Shiwen, Xu, Abraham, David J., Denton, Christopher D., DBE, Carol M. Black, Stratton, Richard J.; Absence of Epithelial to Mesenchymal Transition Despite Activation of Keratinocytes in Scleroderma Skin. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1485