title: Calprotectin in rheumatic diseases.
abstract: Calprotectin is a heterodimer formed by two proteins, S100A8 and S100A9, which are mainly produced by activated monocytes and neutrophils in the circulation and in inflamed tissues. The implication of calprotectin in the inflammatory process has already been demonstrated, but its role in the pathogenesis, diagnosis, and monitoring of rheumatic diseases has gained great attention in recent years. Calprotectin, being stable at room temperature, is a candidate biomarker for the follow-up of disease activity in many autoimmune disorders, where it can predict response to treatment or disease relapse. There is evidence that a number of immunomodulators, including TNF-α inhibitors, may reduce calprotectin expression. S100A8 and S100A9 have a potential role as a target of treatment in murine models of autoimmune disorders, since the direct or indirect blockade of these proteins results in amelioration of the disease process. In this review, we will go over the biologic functions of calprotectin which might be involved in the etiology of rheumatic disorders. We will also report evidence of its potential use as a disease biomarker. Impact statement Calprotectin is an acute-phase protein produced by monocytes and neutrophils in the circulation and inflamed tissues. Calprotectin seems to be more sensitive than CRP, being able to detect minimal residual inflammation and is a candidate biomarker in inflammatory diseases. High serum levels are associated with some severe manifestations of rheumatic diseases, such as glomerulonephritis and lung fibrosis. Calprotectin levels in other fluids, such as saliva and synovial fluid, might be helpful in the diagnosis of rheumatic diseases. Of interest is also the potential role of calprotectin as a target of treatment.
authors.affiliation: Medicine Department - DIMED, Rheumatology Unit, University of Padova, Padova 35128, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Ometto
authors.affiliation: Medicine Department - DIMED, Rheumatology Unit, University of Padova, Padova 35128, Italy.
authors.forename: Lara
authors.initials: L
authors.lastname: Friso
authors.affiliation: Medicine Department - DIMED, Rheumatology Unit, University of Padova, Padova 35128, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Astorri
authors.affiliation: Medicine Department - DIMED, Rheumatology Unit, University of Padova, Padova 35128, Italy.
authors.forename: Costantino
authors.initials: C
authors.lastname: Botsios
authors.affiliation: Medicine Department - DIMED, Rheumatology Unit, University of Padova, Padova 35128, Italy.
authors.forename: Bernd
authors.initials: B
authors.lastname: Raffeiner
authors.affiliation: Medicine Department - DIMED, Rheumatology Unit, University of Padova, Padova 35128, Italy.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Punzi
authors.affiliation: Medicine Department - DIMED, Rheumatology Unit, University of Padova, Padova 35128, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Doria
mesh_terms: D056704:Adaptive Immunity; D000328:Adult; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D006801:Humans; D039841:Leukocyte L1 Antigen Complex / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008958:Models, Molecular; D012216:Rheumatic Diseases / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D039841:Leukocyte L1 Antigen Complex
keywords: Calprotectin; S100A8/A9; biomarker; inflammation; rheumatic diseases; rheumatoid arthritis