FRI0406 Increased frequency of circulating cd163+ non-classical monocytes in scleroderma and enhanced dual polarisation towards m1 and m2-like phenotypes in monocyte-derived macrophages. (12th June 2018)

• Record Type: Journal Article
• Authors: Tam, A.; Reinke-Breen, L.; Trujillo, G.; Xu, S.; Denton, C. P.; Abraham, D. J.; Jarai, G.; Ong, V. H.
• Is Part Of: Annals of the rheumatic diseases. Volume 77(2018)Supplement 2
• Page Start: 735
• Page End: 735
• Publication Date: 2018-06-12
• Subjects: Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2018-eular.1818
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Background: Scleroderma (SSc) is an autoimmune connective tissue disease involving complex interactions between various cell types leading to organ-based tissue fibrosis. Emergence of the monocytes (Mo)/macrophages (Mφ) lineage(s) as key contributors to inflammation, vascular dysfunction and scarring in scleroderma 1, 2 have led to increased scrutiny of their phenotype and function. Objectives: To determine the circulating Mo subpopulations and phenotypes of Mφ in SSc. Methods: PBMC were collected from healthy (HC) and SSc donors, and analysed by flow cytometry using Mo phenotypic antibodies or purified and cultured in vitro . For flow cytometry immunophenotyping, Mo were gated on CD3 - CD19 - CD56 - HLA-DR + populations, and subsets defined by CD14, CD16, CD163 and CD206 expression. For Mφ cultures, Mo were negatively selected from PBMCs, cultured for 7 days, and treated with IFN-γ(5 ng/ml) or IL-4(20 ng/ml) for 24 hours. Cytokine levels in the conditioned media were evaluated by MSD analyses and normalised to total protein levels. Results: The frequency of circulating CD163 + non-classical Mo (CD14 lo CD16 hi ) was 2-fold higher in SSc patients than in HC (unpaired t-test, p=0.026). No difference was found in the frequency of CD206 + monocyte subsets between HC and SSc. In vitro, unstimulated SSc Mφ (M0) secreted higher levels of classically-activated pro-inflammatory (M1) and alternatively-activated pro-regenerative (M2) cytokines. Compared to HC cells, SSc Mφ were more readily polarised towards an M1 phenotype or an M2 phenotype, when cultured in the presence of IFN-γ or IL-4, respectively. Th17 markers and MMPs were significantly increased in SSc Mφ (table 2). Conclusions: Studies exploring Mo have revealed distinct populations with selective biological functions. Our observation of an increased number of CD163 + non-classical Mo in SSc suggests that this subpopulation may play a key role in inflammatory-driven fibrosis and act as an important source of pro-fibrotic cytokines. This data is consistent with previous reports of elevated serum levels of CD163 and increased CD163 secretion by SSc PBMCs 3 . SSc Mφ showed a pronounced and enhanced dual M1 and M2 polarisation basally compared to HC, indicating cells were 'primed' to undergo phenotypic polarisation. Our studies support the notion that Mφ cytokine secretion generates a pro-fibrotic milieu in scleroderma tissues, playing a prominent role in dysregulated tissue repair in fibrosis. References: [1] Chia JJ, Lu TT. Curr Opin Rheumatol2015Nov;27(6):530–536. [2] Christmann RB, Lafyatis R. Arthritis Res Ther. 2010;12(5):146. [3] Hassan WASE, et al. Eur J Rheumatol2016Sep;3(3):95–100. Disclosure of Interest: None declared