Session Type: ACR Poster Session B
Session Time: 9:00AM-11:00AM
Background/Purpose: Systemic sclerosis (SSc) is an autoimmune disease characterized by immune system alterations, vasculopathy and fibrosis . SSc-related interstitial lung disease (ILD) represents a common and early complication of SSc, being the leading cause of mortality . Monocytes/macrophages seem to have a key role in SSc-related ILD. Interestingly, the classically (M1) and alternatively (M2) activated monocyte/macrophage phenotype categorization is currently under revision . Our aim was to evaluate if circulating monocyte/macrophage phenotype could be hypothesized as a pathogenic factor and/or used as biomarker for SSc-related ILD. To this purpose we developed a wide phenotype characterization of circulating monocyte/macrophage subsets in SSc patients and evaluated relations with lung involvement parameters.
Methods: A single centre, cross-sectional study was performed, in fifty-five consecutive SSc patients (50 females/5 males, mean age of 63±13 years, 36 with a diffused cutaneous disease form and 19 with a limited cutaneous disease). All clinical and instrumental tests requested for SSc follow up and in particular: lung computed tomography (CT) scan, pulmonary function tests (PFTs), Doppler echocardiography with systolic pulmonary artery pressure (sPAP) measurement, blood pro-hormone of brain natriuretic peptide evaluation, were performed in each patient. Flow-cytometry characterization of circulating monocytes/macrophages was performed using surface markers attributed both to M1 and M2 cell subsets. Non-parametric tests were used for statistical analysis and any p-value lower than 0.05 was considered as statistically significant.
Results: Several mixed M1/M2 monocyte/macrophage subsets showed higher percentages in patients positive for anti-topoisomerase antibody, a well-known lung involvement predictor. A higher percentage of circulating cells positive for both CD204, CD163, CD206 (M2 markers) and TLR4, CD80, CD86 (M1 markers), was identified to characterize patients affected by SSc-related ILD and higher systolic pulmonary artery pressure. Higher percentages of circulating M1/M2 subsets showed a linear negative correlation with diffusion lung capacity of carbon monoxide (DLCO)%. A FVC/DLCO ratio higher than 1.5 correlated with higher circulating M1/M2 percentages.
Conclusion: The present study shows for the first time, through a wide flow cytometry surface marker analysis, that higher circulating mixed M1/M2 monocyte/macrophage cell percentage significantly correlated with anti-topoisomerase antibody positivity, ILD and sPAP in SSc, opening the path for research on their possible role as pathogenic or biomarker elements for SSc lung involvement. References. Cutolo M, et al. Nat Rev Rheumatol 2015; 11:569-71.  Steen VD, et al. Ann Rheum Dis 2007;66:940-4.  Christmann RB, et al. Arthritis Rheumatol. 2014;66:714-25.
To cite this abstract in AMA style:Cutolo M, Trombetta AC, Tomatis V, Paolino S, Pizzorni C, Smith V, Contini P, Montagna P, Brizzolara R, Soldano S. Circulating Hybrid M1/M2 Monocytes/Macrophages in Systemic Sclerosis Patients with Lung Involvement [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 10). https://acrabstracts.org/abstract/circulating-hybrid-m1-m2-monocytes-macrophages-in-systemic-sclerosis-patients-with-lung-involvement/. Accessed August 14, 2020.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/circulating-hybrid-m1-m2-monocytes-macrophages-in-systemic-sclerosis-patients-with-lung-involvement/