Association between histopathological changes and expression of selected microRNAs in skin of adult patients with IgA vasculitis

Aims IgA vasculitis (IgAV) is a common small‐vessel systemic vasculitisthat is histologically characterised by granulocyte infiltration and IgA deposition in vessel walls. Information on microRNA (miRNA) involvement inIgAVis limited. The aim of this study was to analyse the association between histopathological changes and expression profiles of 14 miRNAs in the affected skin of 70 adult patients with IgAV. Methods and results miRNA expression analysis was performed by quantitative real‐time polymerase chain reaction and evaluation of histopathological changes by light and immunofluorescence microscopy on formalin‐fixed paraffin‐embedded skin excision samples. In IgAV‐affected skin, granulocyte infiltration was significantly associated with vessel fibrinoid necrosis. Of the analysed miRNAs, four showed two‐fold increased expression (let‐7d, let‐7f, miR‐21‐5p, and miR‐203‐3p), five showed five‐fold increased expression (let‐7b, miR‐17‐5p, miR‐155‐5p, miR‐423‐5p, and miR‐451a), and threeshowed 15‐fold increased expression (let‐7a, miR‐21‐3p, miR‐223‐3p), as compared with controls (all P