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Updated: Aug 21, 2026
Studying Chronic Exposure of Mice to Ultraviolet B Radiation
Published on: August 19, 2025
Modulation of endothelial dysfunction and apoptosis: UVA1-mediated skin improvement in systemic sclerosis
Frank Breuckmann1, Markus Stuecker, Peter Altmeyer
1Department of Dermatology, Ruhr-University Bochum, Gudrunstrasse 56, 44791 Bochum, Germany. Frank.Breuckmann@ruhr-uni-bochum.de
Abstract:
UVA1-mediated effects regarding vascular dysregulation as a primary pathogenetic factor of systemic sclerosis skin lesions have so far not been investigated. Pre- and posttherapy skin biopsies of four patients were evaluated immunohistochemically for angiostatic, angiogenic and angioapoptotic features. Immunohistochemistry revealed a partial pretherapy loss of endothelial CD31 and CD34 expression accompanied by a posttherapy increase of CD34(+) cells. Simultaneously, VEGF and M30 CytoDEATH immunolabeling demonstrated UVA1-induced neovascularization and decreased endothelial apoptosis. Our results suggest that UVA1 irradiation exerts its positive effects by a modulation of endothelial regulation/transformation beside the proposed induction of T cell apoptosis and collagenases.
Insights
UVA1 irradiation improves systemic sclerosis skin lesions by promoting vascular repair. This therapy increases beneficial CD34+ cells and neovascularization, while reducing endothelial cell death.
Area of Science:
- Dermatology
- Vascular Biology
- Photomedicine
Background:
- Systemic sclerosis (SSc) involves vascular dysregulation contributing to skin lesions.
- The role of UVA1 irradiation in modulating vascular aspects of SSc remains unexplored.
Purpose of the Study:
- To investigate the effects of UVA1 therapy on vascular changes in SSc skin.
- To evaluate angiostatic, angiogenic, and angioapoptotic markers before and after UVA1 treatment.
Main Methods:
- Immunohistochemical analysis of pre- and post-therapy skin biopsies from four SSc patients.
- Assessment of endothelial markers (CD31, CD34), vascular endothelial growth factor (VEGF), and M30 CytoDEATH.
Main Results:
- UVA1 therapy increased CD34+ cells and neovascularization, indicated by VEGF.
- Endothelial apoptosis decreased post-therapy, as shown by reduced M30 CytoDEATH.
- Partial loss of CD31 and CD34 expression pre-therapy was noted.
Conclusions:
- UVA1 irradiation positively impacts SSc skin lesions through vascular modulation.
- The therapy appears to enhance endothelial regulation and neovascularization.
- These effects complement previously suggested mechanisms like T cell apoptosis induction.