O14 Reducing blistering during junctional epidermolysis bullosa by in vivo inhibition of tumour necrosis factor and interleukin-1β signalling
Cameron Ferguson, Mohammad Yaseen, Matt Caley, Emanuel Rognoni, Emma S ChambersAbstract
Introduction and aims
Junctional epidermolysis bullosa (JEB) is an inherited, rare blistering disorder caused by loss of laminin-332, a mediator of epidermis–dermis adhesion, causing cutaneous fragility, impaired healing and exacerbating pruritus. Chronic inflammation is prominent, with elevated levels of the inflammatory cytokines tumour necrosis factor (TNF) and interleukin (IL)-1β relative to matched controls, yet in-depth immunological study of JEB is absent. We propose the underlying molecular pathology induces a distinct inflammatory niche, and repurposing TNF and IL-1β signalling inhibitors will improve inflammation and clinical symptoms. Accordingly, we aim to characterize cutaneous leucocyte composition and investigate effects of TNF and IL-1β inhibition on itch, inflammation and cutaneous phenotype.
Methods
Our inducible Lama3 knockout C57BL/6 murine model of severe, progressive JEB replicates symptoms of the human condition and is employed to investigate cutaneous leucocytes alongside evaluating TNF (adalimumab) and IL-1β (Anakinra) signalling inhibitor treatments on JEB pathology. We developed a murine leucocyte staining panel for spectral flow cytometry alongside a recording system to quantify pruritus during disease progression, a first in JEB research. In preliminary experiments, JEB mice received 2-week courses of adalimumab or anakinra with weekly recordings performed, and cutaneous tissues were harvested for downstream immunohistochemical and flow analyses.
Results
Blistered JEB skin was dominated by mononuclear phagocytes (prominently Ccr2+ macrophages, F4/80+Ly6clo macrophages, and monocytes), granulocytes, with few lymphocytes. Preliminary experimentation indicates adalimumab treatment arrested exacerbation of pruritus, reduced recruitment of monocytes, eosinophils, basophils and neutrophils, and elevated F4/80+Ly6clo and Ccr2+ macrophages alongside impeding angiogenesis. Conversely, anakinra treatment saw no improvements in pruritus, with mixed effects observed upon inflammatory leucocyte makeup, reducing neutrophil and monocyte infiltration simultaneously with F4/80+Ly6clo and Ccr2+ macrophage populations, while populations of T lymphocytes and eosinophils rose.
Conclusions
Our data illuminate underlying JEB wound inflammation, indicating repurposing established anti-TNF therapeutics presents a putative opportunity to improve patient quality of life, and that anti-IL-1β treatments may not relieve inflammation during JEB.