PhD Scientific Days 2024

Poster Session F - Molecular Medicine 3.

The effect of neutrophil-specific deletion of PLCγ2 in experimental autoimmune skin blistering

Text of the abstract

Introduction: Epidermolysis bullosa acquisita (EBA) is a rare autoimmune blistering
disease mediated by autoantibodies against type VII collagen (C7), an essential
anchoring fibril of the dermal-epidermal junction. Previously we showed that the
absence of phospholipase Cγ2 (PLCγ2) protects mice from autoantibody-induced
skin blistering in an autoantibody-induced mouse model of EBA. However, it is
unclear in which cell type the presence of PLCγ2 is required for disease
development.
Aims: We aimed to investigate the role of PLCγ2 expression within neutrophils in a
mouse model of EBA using a lineage-specific deletion approach.
Methods: Transgenic mice carrying neutrophil-specific (MRP8) promoter-driven Cre
recombinase were crossed with mice bearing floxed Plcg2 alleles (Plcg2 ΔPMN mice).
The efficacy and specificity of Plcg2 deletion in leukocytes was tested by flow
cytometry. Autoimmune skin blistering was induced by repeated subcutaneous
injections of anti-C7 antibodies in wild type, Plcg2-deficient (Plcg2 –/– ) and Plcg2 ΔPMN
mice. Disease progression was followed by evaluating the extent and severity of skin
lesions and ear thickness measurements for 14 days. Histological changes were
assessed using H&E-stained ear sections. Leukocyte accumulation and
proinflammatory mediator levels in the ears were measured by flow cytometry and
ELISA, respectively.
Results: The expression of PLCγ2 was strongly decreased (but not completely
abrogated) in circulating neutrophils of Plcg2 ΔPMN mice. PLCγ2 expression in
eosinophils, monocytes, and lymphocytes was not affected by the Plcg2 ΔPMN mutation.
Similar to Plcg2 –/– animals, development of autoantibody-induced skin blistering was
almost completely abrogated in Plcg2 ΔPMN mice, irrespective of the parameters
measured. Dermo-epidermal separation was significantly reduced in ear sections of
Plcg2 ΔPMN mice compared to wild-type littermates. Accumulation of different leukocyte
populations and proinflammatory mediator levels were also reduced upon neutrophil-
specific PLCγ2 deletion.
Conclusion: The Plcg2 ΔPMN mutation leads to efficient and specific, although
incomplete deletion of PLCγ2 in neutrophils. PLCγ2 expressed in neutrophils
appears to be indispensable for the pathogenesis of autoantibody-induced skin
blistering in mice.
Funding: KKP-129954, TKP2021-EGA-29, HUN-REN (0207007).