POS0144 miRNA CARGO CHARACTERIZATION FROM CIRCULATING EXTRACELLULAR VESICLES IN PATIENTS WITH IDIOPATHIC INFLAMMATORY MYOPATHIES (IIM) HIGHLIGHTS PECULIAR EPIGENETIC PROFILES ACROSS DEFINITE IIM SUBSETS AND DIFFERENT CLINICAL MANIFESTATIONS

Abstract

BackgroundIdiopathic Inflammatory myopathies (IIM) are heterogeneous systemic autoimmune diseases for which biomarkers are needed. Extracellular vesicles (EVs) are cell-derived nanoparticles regulating several biological functions[1]. Growing evidence supports the role of EVs in the pathogenesis of systemic autoimmune diseases[2].ObjectivesTo evaluate the EVs-microRNA (miRNA) profile among distinct clinical manifestations and subsets of IIM, and healthy donors (HD).MethodsWe enrolled adult (≥18 years) consecutive IIM patients (EULAR 2017 criteria) and sex- and age-matched HD. Circulating EVs were isolated from plasma through size exclusion chromatography and ultra-filtration. miRNA isolation was performed using Qiagen miRNeasy Serum/Plasma Advanced kit and miRNA quantification and analysis through next generation sequencing (NGS). Comparisons were carried out using Student’s t-test or one-way ANOVA with multiple comparisons.ResultsWe included 60 IIM patients (females 61.7%; mean age 56.3±13.1 years; seropositive 78.3%; clinically active 56.7%; on immunosuppressants (any): 63.3%) and 60 HD. miRNA analysis was performed on 21 IIM patients and 21 HD considering a comprehensive pool of 100 miRNAs. Ten miRNAs resulted significantly dysregulated between patients and HD (Table 1). Among miRNAs upregulated in patients, some exhibit immunoregulatory functions (hsa-miR-222-3p, hsa-miR185-5p) while others are involved in oncogenesis (hsa-miR-486-5p, has-miR-451a, hsa-miR-15a-5p)[3]. Conversely, downregulated miRNAs in patients usually display anti-inflammatory and anti-neoplastic properties (hsa-let-7 group)[1,3]. More specific EVs-miRNA profiles were identified considering IIM subsets and organ involvement (lung, skin and muscles). Patients with Cancer-associated myositis displayed down-regulated hsa-miR-23b-3p (p=0.03), hsa-miR-374a-5p (p=0.01), hsa-miR-361-5p (p=0.046), hsa-miR-143-3p (p=0.03) and up-regulated hsa-miR-26b-5p (p=0.046). Anti-synthetase syndrome patients showed up-regulated hsa-miR-30c-5p (p=0.033) and hsa-miR-186-5p (p=0.024). Dermatomyositis patients displayed up-regulated hsa-miR-125b-5p (p=0.02), hsa-miR-29c-3p (p=0.027), hsa-miR-361-5p (p=0.039). According to different clinical manifestations, hsa-miR-451a, hsa-miR-29a-3p, hsa-miR-342-2p and hsa-miR-146b-5p were up-regulated in active myositis, and hsa-miR-222-3p, hsa-miR-144-5p, hsa-miR-101-3p, hsa-miR-19b-3p, hsa-miR-25-3p in active skin and Gottron’s lesions.ConclusionDifferential expression of EVs-miRNAs across IIM subsets suggests peculiar epigenetic footprints to distinguish specific IIM phenotypes and clinical manifestations, which may shed light on disease mechanisms and possibly generate tailored treatment targets (Figure 1). Circulating EVs might serve as IIM biomarkers and for early stratification of disease manifestations.