Competing interests: PX has received personal fees from MSD and OMT. AM has received personal fees from Bayer, outside the submitted work. NB has received consulting fees, speaker fees and/or honoraria from MSD, GSK, Actelion and Bayer Vital. BE received travel fees, consulting fees, speaking fees and/or honoraria from Actelion, MSD, Bayer and OMT (less than US$10 000 each). MG serves on an advisory Board for Bayer AG and receives lecture fees from Pfizer, MSD and Actelion Pharmaceuticals. SH has received personal fees from Bayer, MSD, Actelion and GSK, outside the submitted work. H-ML has received consulting fees, speaking fees and/or honoraria from AbbVie, BMS, Pfizer, Cellgene, Medac, GSK, Roche, Chugai, Novartis, UCB, Janssen-Cilag, AstraZeneca and Lilly (less than US$10 000 each) and research support from AbbVie, MSD, BMS, Cellgene, Medac, GSK, Roche, Chugai, Novartis, UCB, Janssen-Cilag, AstraZeneca, Lilly, Baxter, SOBI, Biogen, Actelion, Bayer Vital, Shire, Octapharm, Sanofi, Hexal, Mundipharm and Thermo Fisher. CN has received consulting fees, speaking fees and/or honoraria from Actelion, MSD, Boehringer, Novartis, Bayer and AstraZeneca (less than US$10 000 each). CB received travel support from Actelion SA and Orpha Swiss and speakers’ fee from MSD. SU received grants from the Swiss National Science foundation and the Zurich Lung League, travel support and speakers’ fees from Actelion SA, Switzerland, Bayer SA, Germany, MSD, Switzerland and Orpha Swiss. EG has received grants and personal fees from Actelion, Bayer AG and MSD; grants from GSK, Novartis and United Therapeutics; and personal fees from SCOPE, OrPha Swiss GmbH and Zurich Heart House (less than US$10 000 each). NB received speaker fees from Actelion pharmaceuticals, Bayer HealthCare and MSD. OD has received grants and personal fees from research consultancies from AM, Acceleron Pharma, Amgen, AnaMar, Bayer, Beacon Discovery, Boehringer Ingelheim, Catenion, CSL Behring, ChemomAb, Ergonex, GSK, Inventiva, Italfarmaco, iQone, iQvia, Lilly, medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Novartis, Pfizer, Roche, Sanofi, Blade Therapeutics, Glenmark Pharmaceuticals, Target Bio Science and UCB, outside the submitted work, to investigate potential treatments of scleroderma and its complications. In addition, OD has a patent mir-29 for the treatment of systemic sclerosis issued (US8247389, EP2331143).