Autoantibodies against Progranulin and IL-1 receptor antagonist due to immunogenic posttranslational isoforms contribute to hyperinflammation in critically ill COVID-19

• Published in: bioRxiv 2021-10
• Main Authors: Thurner, Lorenz, Fadle, Natalie, Bewarder, Moritz, Kos, Igor, Regitz, Evi, Cetin, Onur, Thurner, Bernhard, Fischer, Yvan, Rixecker, Torben, Preuss, Klaus-Dieter, Schormann, Claudia, Neumann, Frank, Hartmann, Sylvia, Bock, Theresa, Kaddu-Mulindwa, Dominic, Birgit Bette, Bittenbring, Joerg Thomas, Christofyllakis, Konstantinos, Bick, Angelika, Lesan, Vadim, Abdi, Zanir, Mang, Sebastian, Becker, Andre, Metz, Carlos, Seiler, Frederik, Lehmann, Johannes, Agne, Philipp, Adams, Thomas, Link, Andreas, Werner, Christian, Thiel-Bodenstaff, Angela, Reichert, Matthias, Danziger, Guy, Papan, Cihan, Pilch, Jan, Pfuhl, Thorsten, Wuchter, Patrick, Herr, Christian, Lohse, Stefan, Schrezenmeier, Hubert, Boehm, Michael, Langer, Frank, Gaebelein, Gereon, Friesenhahn-Ochs, Bettina, Lammert, Frank, Koerper, Sixten, Rissland, Juergen, Stilgenbauer, Stephan, Lensch, Christian, Kessel, Christoph, Foell, Dirk, Bals, Robert, Becker, Soeren L, Smola, Sigrun, Krawczyk, Marcin, Lepper, Philipp
• Format: Article
• Language: English
• Subjects: Antigens; Autoantibodies; Coronaviruses; COVID-19; Enzyme-linked immunosorbent assay; Immune system; Immunogenicity; Immunoglobulin G; Immunoglobulin M; Immunological tolerance; Inflammation; Interferon; Interleukin 1; Interleukin 1 receptor antagonist; Interleukin 10; Isoforms; Phosphorylation; Plasma levels; Severe acute respiratory syndrome coronavirus 2; Structural proteins; Tumor necrosis factor-α
• DOI: 10.1101/2021.04.23.441188

Hyperinflammation is frequently observed in patients with severe COVID-19. Inadequate and defective IFN type I responses against SARS-CoV-2, associated with autoantibodies in a proportion of patients, lead to severe courses of disease. In addition, hyperactive responses of the humoral immune system have been described. In the current study we investigated a possible role of neutralizing autoantibodies against anti-inflammatory mediators. Plasma from adult patients with severe and critical COVID-19 was screened by ELISA for antibodies against PGRN, IL-1-Ra, IL-10, IL-18BP, IL-22BP, IL-36-Ra, CD40, IFN-α2, IFN-γ, IFN-ω and serpinB1. Autoantibodies were characterized and the antigens were analyzed for immunogenic alterations. In a discovery cohort with severe to critical COVID-19 high titers of PGRN-autoantibodies were detected in 11 of 30 (36.7%), and of IL-1-Ra-autoantibodies in 14 of 30 (46.7%) patients. In a validation cohort of 64 patients with critical COVID-19 high-titer PGRN-Abs were detected in 25 (39%) and IL-1-Ra-Abs in 32 of 64 patients (50%). PGRN-Abs and IL-1-Ra-Abs belonged to IgM and several IgG subclasses. In separate cohorts with non-critical COVID-19, PGRN-Abs and IL-1-Ra-Abs were detected in low frequency (i.e. in < 5% of patients) and at low titers. Neither PGRN- nor IL-1-Ra-Abs were found in 40 healthy controls vaccinated against SARS-CoV-2 or 188 unvaccinated healthy controls. PGRN-Abs were not cross-reactive against SARS-CoV-2 structural proteins nor against IL-1-Ra. Plasma levels of both free PGRN and free IL-1-Ra were significantly decreased in autoantibody-positive patients compared to Ab-negative and non-COVID-19 controls. In vitro PGRN-Abs from patients functionally reduced PGRN-dependent inhibition of TNF-α signaling, and IL-1-Ra-Abs from patients reduced IL-1-Ra- or anakinra-dependent inhibition of IL-1β signaling. The pSer81 hyperphosphorylated PGRN isoform was exclusively detected in patients with high-titer PGRN-Abs; likewise, a hyperphosphorylated IL-1-Ra isoform was only found in patients with high-titer IL-1-Ra-Abs. Thr111 was identified as the hyperphophorylated amino acid of IL-1-Ra. In longitudinally collected samples hyperphosphorylated isoforms of both PGRN and IL-1-Ra emerged transiently, and preceded the appearance of autoantibodies. In hospitalized patients, the presence of IL-1-Ra-Abs or IL-1-Ra-Abs in combination with PGRN-Abs was associated with a higher morbidity and mortality. To conclude, neutralizing autoant