(WHS-P13) GRANZYME B MEDIATES DEGRADATION OF HEMIDESMOSOME PROTEINS IN STEVENS-JOHNSON SYNDROME/TOXIC EPIDERMAL NECROLYSIS
Friday, May 17, 2024
7:30 AM – 5:00 PM East Coast USA Time
Background: Stevens-Johnson syndrome (SJS) /Toxic epidermal necrolysis (TEN) are life-threatening, immune-mediated, cutaneous adverse drug reactions characterized by the separation of the epidermal and dermal layers of the skin, resulting in severe blistering and peeling. Serine protease Granzyme B (GzmB) was recently found to contribute to the sub-epidermal blistering in bullous pemphigoid through the cleavage of α6/β4 integrin, collagen VII, and collagen XVII at the dermal-epidermal junction. In the present study, the role of GzmB in SJS/TEN was investigated. Hypothesis: GzmB accumulation at the dermal-epidermal junction contributes to sub-epidermal blistering in SJS/TEN through the cleavage of α6/β4 integrin, collagen VII, and/or collagen XVII.
Methods: Skin biopsies collected from SJS/TEN patients (n=8) and healthy participants (n=8) were analyzed using immunohistochemistry to assess protein levels of GzmB and its substrates, α6/β4 integrin, collagen VII, and collagen XVII. ELISA was used to quantify GzmB levels in blister fluid from patients with SJS/TEN (n=6) and was compared that of bullous pemphigoid patients (n=2). Western blotting was used to identify fragments of Collagen XVII in SJS/TEN blister fluid samples (n=6).
Results: Epidermal and dermal GzmB levels were significantly elevated in SJS/TEN compared to healthy skin. SJS/TEN sections exhibited reduced α6/β4 integrin, collagen VII, and collagen XVII at the dermal-epidermal junction compared to healthy skin. Increased levels of GzmB as well as fragments of collagen XVII (around 120 kDa and 97 kDa, as previously observed in GzmB cleavage assays in vitro) were detected in all SJS/TEN blister fluid samples, suggesting that the extracellular proteolytic activity of GzmB is sustained in SJS/TEN.
Conclusions: The present study provides a novel pathological mechanism of action in SJS/TEN whereby elevated levels of extracellular GzmB mediates degradation of dermal-epidermal junction proteins, leading to separation of the epidermis from the dermis.