pDCs in lung and skin fibrosis in a bleomycin-induced model and patients with systemic sclerosis

• DOI: 10.1172/jci.insight.98380
• Publication Date: 2018-05-02T15:00:57Z
• Authors: Suzanne Kafaja; Isela Valera; Anagha A. Divekar; Rajan Saggar; Fereidoun Abtin; Daniel E. Furst; Dinesh Khanna; Ram Raj Singh
• Keywords: CD4-Positive T-Lymphocytes; Male; 0301 basic medicine; Biomedical and clinical sciences; Pulmonology; Autoimmune diseases; Gene Expression; Severity of Illness Index; Scleroderma; Mice; Antibiotics; Receptors; 2.1 Biological and endogenous factors; Lung; Skin; Antibiotics, Antineoplastic; Chemotaxis; Antineoplastic; 3. Good health; Chemokine; Respiratory; Imatinib Mesylate; Female; Chemokines; Bronchoalveolar Lavage Fluid; Adult; Immunology; Autoimmune Disease; Transforming Growth Factor beta1; Young Adult; Bleomycin; 03 medical and health sciences; Rare Diseases; Rheumatology; Clinical Research; Animals; Humans; Protein Kinase Inhibitors; Inflammation; Biomedical and Clinical Sciences; Animal; Systemic; Health sciences; Dendritic Cells; Fibrosis; Disease Models, Animal; Case-Control Studies; Disease Models; Interleukin-4; Spleen

Fibrosis is the end result of most inflammatory conditions, but its pathogenesis remains unclear. We demonstrate that, in animals and humans with systemic fibrosis, plasmacytoid DCs (pDCs) are unaffected or are reduced systemically (spleen/peripheral blood), but they increase in the affected organs (lungs/skin/bronchoalveolar lavage). A pivotal role of pDCs was shown by depleting them in vivo, which ameliorated skin and/or lung fibrosis, reduced immune cell infiltration in the affected organs but not in spleen, and reduced the expression of genes and proteins implicated in chemotaxis, inflammation, and fibrosis in the affected organs of animals with bleomycin-induced fibrosis. As with animal findings, the frequency of pDCs in the lungs of patients with systemic sclerosis correlated with the severity of lung disease and with the frequency of CD4+ and IL-4+ T cells in the lung. Finally, treatment with imatinib that has been reported to reduce and/or prevent deterioration of skin and lung fibrosis profoundly reduced pDCs in lungs but not in peripheral blood of patients with systemic sclerosis. These observations suggest a role for pDCs in the pathogenesis of systemic fibrosis and identify the increased trafficking of pDCs to the affected organs as a potential therapeutic target in fibrotic diseases.