PhD Scientific Days 2024

Poster Session K - Theoretical and Translational Medicine 2.

Eculizumab abolishes skin separation by inhibiting cell migration in a human ex vivo model of bullous pemphigoid.

Text of the abstract

Introduction: 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 along with the activation of the complement system leads to the recruitment and activation of different leukocytes causing blister formation. During complement activation, C5 cleavage is known to be a central mechanism inducing inflammatory cell responses. However, the importance of C5 and the pathogenic role of complement in BP remained controversial throughout the past decades.

Aims: Our aim was to investigate the effect of eculizumab, an antibody against C5 in a fully human ex vivo model of BP.

Methods: In the ex vivo skin separation model, frozen sections of normal human skin were treated with the heat-inactivated serum from BP patients. The skin sections were then incubated with freshly isolated granulocytes of healthy volunteers and complement-containing plasma pretreated with eculizumab or vehicle. Granulocyte-mediated dermo-epidermal separation was assessed by light microscopy after haematoxylin-eosin staining. Cell migration toward the DEJ was assessed by real-time microscopy after fluorescent staining of the cells and tissues. Migration data were analysed using ImageJ and Ibidi Chemotaxis Tool.

Results: In the ex vivo skin separation model, eculizumab inhibited BP serum-induced dermo-epidermal separation in a dose-dependent manner with a practically complete inhibition at 20 µg/ml concentration. Real-time microscopy revealed robust neutrophil migration and attachment to the DEJ, which was also completely inhibited by 20 µg/ml eculizumab.

Conclusions: Taken together, eculizumab inhibited the skin separation in our ex vivo fully human model of BP, which can be partly explained by the inhibitory effect of eculizumab on cell migration towards the DEJ. Our results strengthen the importance of C5 cleavage in the pathogenesis of BP and thus the application of eculizumab, or other C5 inhibitors may be beneficial in the therapy of BP.

Funding: This research was funded by the Hungarian National Research, Development and Innovation Office, the HUN-REN Hungarian Research Network, the Hungarian National Academy of Scientist Education, the Hungarian New National Excellence Program and the SE 250+ excellence PhD scholarship.