RESUMO
Bullous pemphigoid (BP) is an autoantibody-mediated blistering skin disease characterized by local inflammation and dermal-epidermal separation, with no approved targeted therapy. The Syk tyrosine kinase is critical for various functions of the immune response. Second-generation Syk inhibitors such as entospletinib are currently being tested for hematological malignancies. Our aim was to test the effect of entospletinib in a fully human model system of BP. Incubating BP serum-treated human frozen skin sections with normal human granulocytes and fresh plasma triggered dermal-epidermal separation that was dependent on complement, NADPH oxidase, and protease activity. Entospletinib dramatically reduced dermal-epidermal separation with a half-maximal inhibitory concentration of ≈16 nM. Entospletinib also reduced ROS production, granule release, and spreading of human granulocytes plated on immobilized immune complexes consisting either of a generic antigen-antibody pair or of recombinant collagen type XVII (BPAg2) and BP serum components (supposedly autoantibodies). However, entospletinib did not affect the chemotactic migration of human granulocytes or their responses to nonphysiological stimulation by phorbol esters. Entospletinib had no effect on the survival of granulocytes either. Taken together, entospletinib abrogates dermal-epidermal separation, likely through inhibition of granulocyte responsiveness to deposited immune complexes. Entospletinib or other Syk inhibitors may provide therapeutic benefits in BP.
Assuntos
Penfigoide Bolhoso , Quinase Syk , Humanos , Quinase Syk/antagonistas & inibidores , Quinase Syk/metabolismo , Penfigoide Bolhoso/tratamento farmacológico , Penfigoide Bolhoso/imunologia , Penfigoide Bolhoso/patologia , Epiderme/efeitos dos fármacos , Epiderme/patologia , Epiderme/imunologia , Pirazinas/farmacologia , Pirazinas/uso terapêutico , Granulócitos/efeitos dos fármacos , Granulócitos/imunologia , Granulócitos/metabolismo , Derme/patologia , Derme/citologia , Proteínas Tirosina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/metabolismo , Colágeno Tipo XVII , Autoantígenos/imunologia , Colágenos não Fibrilares/imunologia , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Imidazóis/farmacologia , Peptídeos e Proteínas de Sinalização Intracelular/antagonistas & inibidores , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Indazóis , MorfolinasRESUMO
Phospholipase Cγ2 (PLCγ2) mediates tyrosine kinaseâcoupled receptor signaling in various hematopoietic lineages. Although PLCγ2 has been implicated in certain human and mouse inflammatory disorders, its contribution to autoimmune and inflammatory skin diseases is poorly understood. In this study, we tested the role of PLCγ2 in a mouse model of epidermolysis bullosa acquisita triggered by antibodies against type VII collagen (C7), a component of the dermo-epidermal junction. PLCγ2-deficient (Plcg2-/-) mice and bone marrow chimeras with a Plcg2-/- hematopoietic system were completely protected from signs of anti-C7-induced skin disease, including skin erosions, dermalâepidermal separation, and inflammation, despite normal circulating levels and skin deposition of anti-C7 antibodies. PLCγ2 was required for the tissue infiltration of neutrophils, eosinophils, and monocytes/macrophages as well as for the accumulation of proinflammatory mediators (including IL-1ß, MIP-2, and LTB4) and reactive oxygen species. Mechanistic experiments revealed a role for PLCγ2 in the release of proinflammatory mediators and reactive oxygen species but not in the intrinsic migratory capacity of leukocytes. The phospholipase C inhibitor U73122 inhibited dermal-epidermal separation of human skin sections incubated with human neutrophils in the presence of anti-C7 antibodies. Taken together, our results suggest a critical role for PLCγ2 in the pathogenesis of the inflammatory form of epidermolysis bullosa acquisita.