Granulomatosis with polyangiitis (GPA) is a form of ANCA-associated vasculitis, characterized by systemic inflammation, primarily targeting the respiratory tract and kidneys. Key to GPA pathology is the dysregulated and therefore immunogenic cell death in neutrophils, leading to chronic inflammation and autoimmunity.

Staphylococcus aureus (S. aureus), often found in the nasal mucosa as both a commensal organism and a pathogen, is increasingly recognized for its involvement in GPA. However, the exact interplay between S. aureus and GPA has not been elucidated so far. Therefore, understanding the role of S. aureus in initiating different cell death pathways - namely apoptosis, necroptosis, pyroptosis and NETosis - offers a significant opportunity to unravel the complex etiology of GPA.

To identify which cell death pathway is being induced by S. aureus, I will stimulate endothelial and neutrophilic cell lines as well as polymorphonuclear neutrophils (PMNs) isolated from blood of both GPA patients and healthy controls, with different S. aureus toxins. Using Western Blot and RT-PCR, I will look for different markers characteristic for either apoptosis, pyroptosis or necroptosis. For the simulation of vascular conditions, I utilize an organ-on-a-chip model. Here, I want to mimic the vascular damage seen in GPA by inducing cell death in the endothelial layer via S. aureus toxins, followed by an barrier-intergrity-assay. With the organ-on-a-chip model, I also want to assess if and to what extent there is transendothelial migration of neutrophils and monocytes induced by supernatants from toxin induced-cell death.