Serum Protein Profiling Reveals a Specific Upregulation of the Immunomodulatory Protein Progranulin in Coronavirus Disease 2019

Background. Severe courses of coronavirus disease 2019 (COVID-19) are associated with elevated levels of interleukin 6 (IL-6). However, there is a growing body of evidence pointing to a broad and more complex disorder of proinflammatory and antiviral responses with disturbed interferon signaling in COVID-19. Methods. In this prospective, single-center registry, we included severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive patients and patients with similar symptoms and severity of disease but negative for SARS-CoV-2 admitted to the emergency department and compared their serum protein expression profiles. Results. IL-6 abundance was similar in SARS-CoV-2-positive patients (n = 24) compared with SARS-CoV-2-negative controls (n = 61). In contrast, we observed a specific upregulation of the immunomodulatory protein progranulin (GRN). High GRN abundance was associated with adverse outcomes and increased expression of IL-6 in COVID-19. Conclusions. The data from this registry reveal that GRN is specifically upregulated in SARS-CoV-2-positive patients while IL-6 may serve as marker for disease severity. The potential of GRN as a biomarker and a possible impact of increased GRN expression on interferon signaling, virus elimination, and virus-induced lung tissue damage in COVID-19 should be further explored.

Automated summary

Level of interleukin 6 (IL-6) is associated with disease severity in COVID-19, however, there is also upregulation of immunomodulatory protein progranulin (GRN) which is specifically observed in SARS-CoV-2-positive patients. High GRN abundance is linked to adverse outcomes and increased IL-6 expression in COVID-19.