{
  "abstract": "Background The complement system is crucial in antineutrophil cytoplasmic antibody-associated vasculitis (AAV) pathogenesis. Extracellular vesicles (EVs) serve as carriers of bioactive substances, influencing the immune system. We aimed to investigate myeloperoxidase-positive EVs (MPO +EVs) exposing complement components (C3a, C4d), terminal complement complex (TCC) and complement factor B (CFB) in relation to disease activity and kidney involvement.Methods Plasma MPO +EVs carrying complement products, C3a, C4d, TCC or CFB, were analysed by flow cytometry. Clinical data, including kidney biopsy findings, were retrieved. Disease activity was assessed using the Birmingham Vasculitis Activity Score (BVAS).Results Eighty-one patients with AAV with granulomatosis with polyangiitis (n=59) or microscopic polyangiitis (n=22) were included. Active disease was noted in 73 (90.1%) patients and 50 (68.5%) had kidney involvement. Patients with kidney involvement had higher concentrations of MPO +, MPO+C3a+, MPO+C4d+ and MPO+TCC+EVs compared to patients without, and concentrations correlated positively with BVAS (p<0.05), respectively. Levels of EVs showed a negative correlation with estimated glomerular filtration rate, and a positive correlation with the proportions of necrosis and crescents in kidney biopsies. ROC curve analysis indicated that MPO+EVs could distinguish patients with kidney involvement from non-renal AAV. A binary multivariable logistic regression confirmed an independent association between levels of EV subsets and kidney involvement.Conclusions Elevated levels of MPO +EVs exposing complement components in patients with kidney involvement indicate activation of the classical or lectin and common complement pathways in renal AAV. Furthermore, the association between levels of MPO+EVs with the presence of crescents and necrotic lesions in kidney tissue supports a role in renal inflammatory activity.",
  "authors": [
    {
      "affiliations": [
        "Division of Rheumatology, Department of Medicine, Karolinska Institutet, Stockholm, Sweden",
        "Rheumatology, Karolinska University Hospital, Stockholm, Sweden"
      ],
      "name": "Anna Juto"
    },
    {
      "affiliations": [
        "Division of Rheumatology, Department of Medicine, Karolinska Institutet, Stockholm, Sweden",
        "Institute of Rheumatology, School of Medicine, University of Belgrade, Belgrade, Serbia"
      ],
      "name": "Jelena Colic"
    },
    {
      "affiliations": [
        "Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden",
        "Clinical Chemistry, Karolinska University Laboratory, Karolinska University Hospital, Stockholm, Sweden"
      ],
      "name": "Apostolos Taxiarchis"
    },
    {
      "affiliations": [
        "Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden",
        "Center for Clinical and Translational Research, Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, USA"
      ],
      "name": "Iva Pruner"
    },
    {
      "affiliations": [
        "Division of Rheumatology, Department of Medicine, Karolinska Institutet, Stockholm, Sweden"
      ],
      "name": "Vivianne Malmström"
    },
    {
      "affiliations": [
        "Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden",
        "CLINTEC, Karolinska Institutet, Stockholm, Sweden",
        "Department of Renal Medicine, Karolinska University Hospital, Stockholm, Sweden"
      ],
      "name": "Annette Bruchfeld"
    },
    {
      "affiliations": [
        "Division of Rheumatology, Department of Medicine, Karolinska Institutet, Stockholm, Sweden",
        "Rheumatology, Karolinska University Hospital, Stockholm, Sweden"
      ],
      "name": "Iva Gunnarsson"
    },
    {
      "affiliations": [
        "Division of Rheumatology, Department of Medicine, Karolinska Institutet, Stockholm, Sweden",
        "Rheumatology, Karolinska University Hospital, Stockholm, Sweden"
      ],
      "name": "Aleksandra Antovic"
    }
  ],
  "title": "Extracellular vesicles exposing complement split products are associated with kidney involvement in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV)",
  "uid": "a526da55-771f-52ec-a7b5-cda63a6845fd"
}