Einfluss der Glykosylierung auf die IgG2-induzierte Signalgebung in Neutrophilen

Abstract

Epidermolysis bullosa acquisita (EBA) is a rare autoimmune blistering disease with significant therapeutic challenges due to its lack of steroid responsiveness and the absence of randomized clinical trials. This underscores the urgent need for both curative and targeted therapies. EBA is characterized by pathogenic autoantibodies targeting type VII collagen (COL7) in the skin's basement membrane, leading to complement activation, cytokine release, and leukocyte recruitment. Mainly, neutrophils activated by immune complexes (IC) via Fc gamma receptors release reactive oxygen species (ROS) and proteases, causing characteristic subepidermal blisters. While IgG1 and IgG3 antibodies are primarily involved in EBA, the role of IgG2 and its glycosylation in disease modulation is less understood. In this body of work, experiments on differentially glycosylated anti-COL7 IgG2 IC demonstrated that EndoS-treated IgG2 IC significantly reduced neutrophil adhesion and ROS release. Correspondingly, pro-inflammatory degalactosylated IgG2 IC exhibited higher adhesion and ROS release compared to anti-inflammatory glycoforms. PamGene analysis revealed that, unlike IgG1, IgG2-based IC did not activate the pathogenic phosphoinositide 3-kinase (PI3K)/AK strain transforming (AKT)/mammalian target of rapamycin (mTOR) or the cyclin-dependent kinase (CDK) pathways. Pro-inflammatory degalactosylated glycoforms exhibited higher kinase activation, whereas anti-inflammatory forms showed fewer upregulated kinases. All IgG2-based glycoforms upregulated Casein kinase 1 epsilon, particularly EndoS and galactosylated forms, suggesting a potential anti-inflammatory role, possibly through Wnt signaling. IgG2 IC also did not upregulate Spleen tyrosine kinase (Syk), aligning with findings that Syk-deficient neutrophils protected against disease in murine EBA models. In conclusion, these glycoforms effectively inhibited key neutrophil functions. The signaling pathways identified suggest a potential protective role of IgG2-based IC stimulation in neutrophil-mediated inflammation and tissue damage, presenting glycoengineering as a potential therapeutic future option in EBA.