PhD Scientific Days 2025

Poster Session I. - I: Theoretical and Translational Medicine

Complement 5 inhibition abolishes skin separation by inhibiting granulocyte chemotaxis in a human ex vivo model of bullous pemphigoid.

Name of the presenter

Vikár Simon

Institute/workplace of the presenter

Institut of Physiology

Authors

Simon Vikár¹, Tamás Soma Szalay¹, Barbara Uzonyi², Mihály Józsi², Miklós Sárdy³, Attila Mócsai¹

1: Department of Physiology, Semmelweis University
2: Department of Immunology, Eötvös Lóránd University
3: Department of Dermatology, Venereology and Dermatooncology

Text of the abstract

Bullous pemphigoid (BP) is an autoimmune blistering skin disease characterized by autoantibody formation against key anchoring proteins of the dermo-epidermal junction (DEJ). The deposition of these autoantibodies leads to complement activation and leukocyte infiltration in the skin causing blister formation. C5 cleavage is known to be a central mechanism inducing inflammatory cell responses. However, the importance of C5 and the role of complement in BP remained controversial.

Our aim was to investigate the effect of eculizumab, an antibody against C5, and the role of the C5a-C5aR1 axis in a fully human ex vivo model of BP.

In our model, frozen sections of normal human skin were treated with heat-inactivated serum from BP patients. These sections were then incubated with freshly isolated human granulocytes and fresh plasma pretreated with eculizumab (C5 inhibitor), vilobelimab (C5a inhibitor), avacopan (C5aR1 inhibitor) or vehicle. Dermo-epidermal separation was assessed by light microscopy after haematoxylin-eosin staining. The effect of eculizumab on cell migration was assessed by real-time microscopy after fluorescent staining of the cells. Migration data were analysed by the Fiji software.

In the ex vivo skin separation model, eculizumab inhibited dermo-epidermal separation in a dose-dependent manner with a complete inhibition at 20 µg/ml concentration as well as in therapeutic concentrations, applying plasma of eculizumab-treated patients. Real-time microscopy revealed robust granulocyte chemotaxis to the DEJ, which was also completely inhibited by 20 µg/ml eculizumab. 10 µM Avacopan and 50 µg/ml vilobelimab also completely inhibited dermo-epidermal separation on BP-serum treated skin.

Taken together, eculizumab inhibited the skin separation in therapeutic concentration in our fully human BP model, which can be explained by the inhibition of the chemotactic C5a protein production. Our results strengthen the importance of C5 cleavage and the role of the C5a-C5aR1 axis in the pathogenesis of BP, suggesting that eculizumab or other C5 inhibitors may be beneficial in the therapy of BP.

Funded by the Hungarian National Research, Development and Innovation Office (KKP-129954, TKP2021-EGA-24 and TKP2021-EGA-29), the HUN-REN Hungarian Research Network (0207007), the Hungarian Academy of Sciences (LP2024-16/2024) and the EKÖP Scholarship.