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FRI0441 Microrna-34A Unbalance is Associated to IL-6/IL-6R Pathway in CD14 Cells and Skin Compartment of Systemic Sclerosis Patients
  1. S. Alivernini1,
  2. S.L. Bosello1,
  3. M. Kurowska-Stolarska2,
  4. S. Canestri1,
  5. L. Bui3,
  6. M.M. Fabrizi3,
  7. B. Tolusso1,
  8. I.B. McInnes2,
  9. G. Ferraccioli1
  1. 1Division Of Rheumatology, Institute Of Rheumatology And Affine Sciences, Catholic University Of The Sacred Heart, Rome, Italy
  2. 2Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
  3. 3Division of Pathology, Catholic University Of The Sacred Heart, Rome, Italy

Abstract

Background MicroRNAs (miRs) are post-transcriptional negative regulators that have been implicated in Systemic Sclerosis (SSc). MiR-34a has been linked to endothelial senescence and myeloid cell driven inflammation. However its role in SSc hasn't been investigated yet.

Objectives To investigate miR-34a expression in peripheral blood (PB) CD14 cells and in paired lesional and non-lesional SSc skin biopsies.

Methods Healthy controls (HC)(n=7) and 27 patients with Raynaud phenomenon (RP) were enrolled to the study. The latter were divided into 3 groups: long standing SSc (lsSSc)(n=10), early SSc (eSSc)(n=9) and primary RP (n=8) respectively. Immunostaining (IHC) for CD68 and in situ hybridization (ISH) for miR-34a were performed on paired lesional and non-lesional skin tissues from SSc patients. In addition, miR-34a expression was evaluated by qPCR on CD14 cells isolated from PB and paired lesional and non-lesional skin samples. IL-6 receptor (IL6-R) was selected as a potential miR-34a target (TargetScan) and experimentally confirmed by qPCR. IL-6 and IL-6R plasma levels were determined by ELISA. CD14 cells from PB of HC (n=5) were stimulated with IL-6 (30ng/ml) in vitro and miR-34a expression assessed by qPCR.

Results MiR-34a expression was increased in lsSSc compared to HC (p=0.01). Early SSc and RP patients showed pattern of expression similar to HC (p=0.63 and p=0.71). IHC showed that CD68 cells are over-represented in lesional skin compared to non-lesional skin (p=0.02) and ISH revealed that miR-34a is over-expressed in lesional skin compared to non-lesional skin (p=0.001). In addition qPCR confirmed higher expression of miR-34a in lesional than in non-lesional skin (p=0.001). Consistently, IL-6R expression in PB CD14+ cells was lower in lsSSc and eSSc patients compared to primary RP (p=0.0001 and p=0.0002) whereas IL-6R expression was similar comparing primary RP and HC (p=0.73). In addition, IL-6R inversely correlated with miR-34a expression in lsSSc in PB CD14+ cells (r=-0.81; p=0.01). IL-6 plasma levels were higher in lsSSc (p=0.002) as well as in eSSc (p=0.04) compared to HC whereas no significant difference was found in soluble IL-6R plasma levels. MiR-34a expression in CD14+ cells directly correlated with the skin score value (R=0.52, p=0.03) and with IL-6 plasma levels (R=0.42; p=0.01) in SSc patients. Anti-Scl70+ patients have higher expression of miR-34a than anti-centromere+ patients (p=0.04). Considering SSc related vasculopathy, SSc patients with digital ulcers had higher miR-34a expression than SSc patients without ulcers (p=0,01). Finally, miR-34a was inducible in healthy CD14 cells by IL-6 in vitro stimulation.

Conclusions MiR-34a is IL-6 inducible miR, which expression in PB CD14+ cells positively correlates with skin fibrosis and vascular manifestations. It negatively correlates with the expression of its target IL-6R in patients with severe disease suggesting for the role of this miR in the regulation of IL-6/IL-6R pathway. MiR-34a could represent a possible biomarker to identify patients with SSc associated RP and organ involvement.

Disclosure of Interest None declared

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