title: Serum amyloid A is a marker for pulmonary involvement in systemic sclerosis.
abstract: Inflammation in systemic sclerosis (SSc) is a prominent, but incompletely characterized feature in early stages of the disease. The goal of these studies was to determine the circulating levels, clinical correlates and biological effects of the acute phase protein serum amyloid A (SAA), a marker of inflammation, in patients with SSc. Circulating levels of SAA were determined by multiplex assays in serum from 129 SSc patients and 98 healthy controls. Correlations between SAA levels and clinical and laboratory features of disease were analyzed. The effects of SAA on human pulmonary fibroblasts were studied ex vivo. Elevated levels of SAA were found in 25% of SSc patients, with the highest levels in those with early-stage disease and diffuse cutaneous involvement. Significant negative correlations of SAA were found with forced vital capacity and diffusion capacity for carbon monoxide. Patients with elevated SAA had greater dyspnea and more frequent interstitial lung disease, and had worse scores on patient-reported outcome measures. Incubation with recombinant SAA induced dose-dependent stimulation of IL-6 and IL-8 in normal lung fibroblasts in culture. Serum levels of the inflammatory marker SAA are elevated in patients with early diffuse cutaneous SSc, and correlate with pulmonary involvement. In lung fibroblasts, SAA acts as a direct stimulus for increased cytokine production. These findings suggest that systemic inflammation in SSc may be linked to lung involvement and SAA could serve as a potential biomarker for this complication.
authors: Department of Rheumatology, University Medical Centre Ljubljana, Ljubljana, Slovenia; Division of Rheumatology, Feinberg School of Medicine, Northwestern University, Chicago, United States of America.
authors: Katja
authors: K
authors: Lakota
authors: Division of Rheumatology, Feinberg School of Medicine, Northwestern University, Chicago, United States of America.
authors: Mary
authors: M
authors: Carns
authors: Division of Rheumatology, Feinberg School of Medicine, Northwestern University, Chicago, United States of America.
authors: Sofia
authors: S
authors: Podlusky
authors: Department of Rheumatology, University Medical Centre Ljubljana, Ljubljana, Slovenia.
authors: Katjusa
authors: K
authors: Mrak-Poljsak
authors: Division of Rheumatology, Feinberg School of Medicine, Northwestern University, Chicago, United States of America.
authors: Monique
authors: M
authors: Hinchcliff
authors: Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, United States of America.
authors: Jungwha
authors: J
authors: Lee
authors: Department of Rheumatology, University Medical Centre Ljubljana, Ljubljana, Slovenia.
authors: Matija
authors: M
authors: Tomsic
authors: Department of Rheumatology, University Medical Centre Ljubljana, Ljubljana, Slovenia; University of Primorska, Faculty of Mathematics, Natural Sciences and Information Technology, Koper, Slovenia.
authors: Snezna
authors: S
authors: Sodin-Semrl
authors: Division of Rheumatology, Feinberg School of Medicine, Northwestern University, Chicago, United States of America.
authors: John
authors: J
authors: Varga
mesh_terms: D015415:Biomarkers / Q000097:blood; D001799:Blood Sedimentation; D002097:C-Reactive Protein; D016022:Case-Control Studies; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D008168:Lung / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology; D063868:Patient Outcome Assessment; D012129:Respiratory Function Tests; D012595:Scleroderma, Systemic / Q000097:blood* / Q000453:epidemiology / Q000473:pathology*; D057566:Self Report; D000685:Serum Amyloid A Protein / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D015850:Interleukin-6; D000685:Serum Amyloid A Protein; D002097:C-Reactive Protein
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