AUTHOR=Surmiak Marcin , Wawrzycka-Adamczyk Katarzyna , Kosałka-Węgiel Joanna , Włudarczyk Anna , Sanak Marek , Musiał Jacek 

TITLE=Activity of granulomatosis with polyangiitis and its correlation with mTOR phosphoproteomics in neutrophils

JOURNAL=Frontiers in Immunology

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2023.1227369

DOI=10.3389/fimmu.2023.1227369

ISSN=1664-3224

ABSTRACT=Introduction. Granulomatosis with polyangiitis (GPA) is a small vessel vasculitis with a complex pathomechanism. Organ damage in GPA is mediated also by extracellular trap formation (NETosis). We analyzed a functional status of phosphoproteins modulating NETosis in neutrophils by mammalian target of rapamycine (mTOR) pathway in GPA along with NETosis biomarkers. Methods. Phosphoproteins levels measured in isolated neutrophils from 42 GPA patients, (exacerbation n=21; remission n=21) and 21 healthy controls were compared to serum biomarkers of the disease. Results. Neutrophils in active disease manifested lowered levels of phosphorylated mTOR (Ser2448) , PTEN (Ser380) and ULK1 (Ser555) , whereas phosphorylated GSK-3α/β (Ser21/Ser9) was elevated. Exacerbation of GPA was characterized by elevated neutrophil dsDNA in serum, circulating mitochondrial DNA and DNA-MPO complexes. A significant negative correlation between mTOR or PTEN phosphoproteins and biomarkers of GPA activity was also present, reflecting the clinical activity score of GPA. Positive correlations between phosphorylated of GSK-3 α/β and circulating mtDNA, DNA-MPO complexes, neutrophil-released dsDNA or circulating proteins were also significant. Increased serum levels of IGFBP-2, TFF-3, CD147, and CHI3L1 accompanied GPA exacerbation, whereas DPP-IV levels were the lowest in active GPA. Using a principal component analysis basigin, PTEN and mTOR had the highest loadings on the discrimination function allowing classification between active, remission and control subjects with 98% performance. Conclusions. We present evidence that inhibited mTOR signaling accompanies NETosis in patients with GPA. The functional status of phosphoproteins suggests simultaneous activation of NETosis and autophagy. These results prompt for studying autophagy as a mechanism underlying granuloma formation in GPA.