DIFFERENTIAL CYTOKINE PRODUCTION PROFILES IN STIMULATED MONONUCLEAR CELLS OF PATIENTS WITH SYSTEMIC SCLEROSIS AND CONTROLS

BackgroundAltered innate and adaptive immune responses represent the link between microvascular injury and fibrosis in systemic sclerosis (SSc) pathophysiology. Peripheral monocytes and lymphocytes are responsible for the secretion of cytokines with proven pro-inflammatory and pro-fibrotic activities. Chronic immune activation in SSc is supported by distinct serum and peripheral blood mononuclear cell (PBMC) cytokine profiles in relation to disease duration, autoantibody subtype, as well as severity of clinical manifestations.ObjectivesThis pilot study aimed to: (1) evaluate the PBMC cytokine production in SSc patients versus healthy controls (HC) after in vitro stimulation with lipopolysaccharide (LPS) and heat-killed Candida albicans and (2) distinguish different SSc clinical phenotypes based on their cytokine signature.MethodsEighteen SSc patients (8 limited cutaneous, 9 diffuse cutaneous, 1 sine scleroderma) and 17 age and gender matched HC were enrolled between February 2020 and October 2021. PBMCs were isolated and further subjected to stimulation with LPS and Candida albicans. Cytokine production was measured after 24 hours using ELISA kits for interleukin (IL)-1β, IL-1 receptor antagonist and IL-6. IL-17 and interferon gamma (IFN-γ) concentrations were determined at 7 days from samples stimulated with Candida albicans-in the presence of 10% human pooled serum. Non-parametric data was analyzed using Mann-Whitney test while T.test was used for parametric data.ResultsSignificantly elevated IL-1 β and IL-6 concentrations were detected in SSc patients compared to HC after stimulation with either LPS or Candida albicans. IL-17 cytokine production was also enhanced in SSc patients compared to HC after stimulation with Candida albicans for 7 days, but no difference was identified with respect to IFN-γ. No significant statistical difference was demonstrated between cytokine levels and extent of cutaneous involvement. Furthermore, no association was observed between autoantibody subtypes and cytokine production. Patients with diffuse cutaneous SSc and those positive for anti-Scl-70 antibodies revealed elevated C-reactive protein (CRP) levels.ConclusionSSc patients exhibit a pro-inflammatory phenotype irrespective of the extent of cutaneous involvement or autoantibody profile. This appears to be mediated through increased production of innate immune cytokines, which correlated to elevated Th-17 responses on later time-points. Elevated CRP levels might define a subgroup of SSc patients with specific disease characteristics. Validation of these findings and mechanistic assessment is warranted in larger cohorts of patients.References[1]Dantas AT et al. Different profile of cytokine production in patients with systemic sclerosis and association with clinical manifestations. Immunol Lett 2018;198:12-16[2]Mitev A et al. Inflammatory stays inflammatory: a subgroup of systemic sclerosis characterized by high morbidity and inflammatory resistance to cyclophosphamide. Arthritis Res Ther 2019;21(1):262[3]Lin E et al. Analysis of serum interleukin (IL)-1α, IL-1β and IL-18 in patients with systemic sclerosis. Clin Transl Immunology 2019;8(4):e1045Disclosure of InterestsIulia Szabo Speakers bureau: Roche, Boehringer-Ingelheim, Medeea Badii: None declared, Claudia Sirbe: None declared, Orsi Gaal: None declared, Tania Crisan: None declared, Cristina Pamfil: None declared, Simona Rednic Speakers bureau: Abbvie, Boehringer Ingelheim, Eli Lilly, MSD, Novartis, Pfizer, Roche, Sandoz, UCB, Zentiva