Biomarkers of haemodynamic severity of systemic sclerosis-associated pulmonary arterial hypertension by serum proteome analysis.

Objectives: To mine the serum proteome of patients with systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) and to detect biomarkers that may assist in earlier and more effective diagnosis and treatment.
Methods: Patients with limited cutaneous SSc, no extensive interstitial lung disease and no PAH-specific therapy were included. They were classified as cases if they had PAH confirmed by right heart catheterisation (RHC) and serum collected on the same day as RHC; and as controls if they had no clinical evidence of PAH.
Results: Patients were mostly middle-aged females with anticentromere-associated SSc. Among 1129 proteins assessed by a high-throughput proteomic assay (SOMAscan), only 2 were differentially expressed and correlated significantly with pulmonary vascular resistance (PVR) in SSc-PAH patients (n=15): chemerin ( ρ =0.62, p=0.01) and SET ( ρ =0.62, p=0.01). To validate these results, serum levels of chemerin were measured by ELISA in an independent cohort. Chemerin levels were confirmed to be significantly higher (p=0.01) and correlate with PVR ( ρ =0.42, p=0.04) in SSc-PAH patients (n=24). Chemerin mRNA expression was detected in fibroblasts, pulmonary artery smooth muscle cells (PA-SMCs)/pericytes and mesothelial cells in SSc-PAH lungs by single-cell RNA-sequencing. Confocal immunofluorescence revealed increased expression of a chemerin receptor, CMKLR1, on SSc-PAH PA-SMCs. SSc-PAH serum seemed to induce higher PA-SMC proliferation than serum from SSc patients without PAH. This difference appeared neutralised when adding the CMKLR1 inhibitor α-NETA.
Conclusion: Chemerin seems an interesting surrogate biomarker for PVR in SSc-PAH. Increased chemerin serum levels and CMKLR1 expression by PA-SMCs may contribute to SSc-PAH pathogenesis by inducing PA-SMC proliferation.
Competing Interests: Competing interests: SS reports travel grants from Shire, Sanofi-Genzyme, SOBI and Novartis; consulting fees from Novartis; outside the submitted work. J-LC reports grants from United Therapeutic, Bioprojet and Topadur, outside the submitted work. DM reports grants and personal fees from Actelion, grants and personal fees from Bayer, personal fees from GSK, personal fees from Pfizer, personal fees from MSD, personal fees from Chiesi, outside the submitted work. EH reports consulting fees from Actelion, Boehringer Ingelheim, GSK, Roche-Chugai, Sanofi-Genzyme; speaking fees from Actelion, GSK, Roche-Chugai; and research funding from CSL Behring, GSK, Roche-Chugai, outside the submitted work. DL reports personal fees from Actelion, grants and personal fees from Takeda, grants and personal fees from CSL Behring, outside the submitted work. MH reports personal fees from Actelion, grants and personal fees from Bayer, grants and personal fees from GSK, personal fees from Merck, personal fees from United Therapeutics, personal fees from Acceleron, outside the submitted work. RL reports research grants from Formation, Elpidera and Kiniksa, outside the submitted work. RL has served as a consultant for Bristol Myers Squibb, Boehringer-Mannheim, Merck, Magenta and Genentech/Roche, outside the submitted work. Over the last three years, CG, reports grants from Acceleron, ShouTi, and Janssen and grants and personal fees from Merck, outside the submitted work.
(© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.)