Cells from the skin of patients with systemic sclerosis secrete chitinase 3-like protein 1

Background: The chitinase-like protein, Chi3L1, is associated with increased fibrotic activity as well as inflammatory processes. The capacity of skin cells from systemic sclerosis (SSc) patients to produce Chi3L1, and the stimulation of its synthesis by cytokines or growth factors known to be associated with SSc, was investigated. Methods: Cellswere isolated fromforearmand/or abdomen skin biopsies taken fromSSc patients and normal individuals and stimulated with cytokines and growth factors to assess Chi3L1 expression. Chi3L1-expressing cells were characterized by immunohistochemical staining. Results: Chi3L1 was not secreted by skin cells fromnormal individuals nor was its synthesis induced by any of the cytokines or growth factors investigated. In contrast, Chi3L1 secretion was induced by OSM or IL-1 in cells from all forearmbiopsies of SSc patients, and endogenous secretion in the absence of cytokineswas detected in several specimens. Patientswith Chi3L1-producing cells at both the armand abdomen had a disease duration of less than 3 years. Endogenous Chi3L1 production was not a property of the major fibroblast population nor of myofibroblasts, but rather was related to the presence of stem-like cells not present in normal skin. Other cells, however, contributed to the upregulation of Chi3L1 by OSM. Conclusions: The emergence of cells primed to respond to OSM with increased Chi3L1 production appears to be associated with pathological processes active in SSc. General significance: The presence of progenitor cells expressing the chilectin Chi3L1 in SSc skin appears to play a role in the initiation of the disease process. (C) 2013 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.