LncRNA H19 regulates macrophage polarization and promotes Freund's complete adjuvant-induced arthritis by upregulating KDM6A.

Aberrant expression of long non-coding RNA (lncRNA) H19 is tightly linked to multiple steps of tumorigenesis via the modulation of cell proliferation and apoptosis; however, the pathological significance and regulatory mechanisms of lncRNA H19 in macrophages remain obscure. To investigate whether lncRNA H19 modulates macrophage activation in rheumatoid arthritis (RA), lncRNA H19 levels in PMA-induced PBMC from patients with RA and healthy volunteers were assessed. In addition, the distribution of macrophage subsets, macrophage phenotypic characteristics, and pro-inflammatory gene expression were examined in lncRNA H19 smart silencer- or pcDNA 3.1- H19-transfected macrophages and AAV8-mediated H19 overexpression in a Freund' s complete adjuvant-induced arthritis mouse model. The level of lncRNA H19 was higher in RA patients than in healthy volunteers. Silencing of lncRNA H19 altered lipopolysaccharide plus interferon-induced M1 macrophage polarization and decreased IL-6, CD80, CCL8, and CXCL10 expression in macrophages of RA patients. LncRNA H19 overexpression markedly induced IL-6, CD80, HLA-DR, KDM6A, STAT1, IRF5, CCL8, CXCL9, CXCL10, and CXCL11 expression in macrophages and promoted macrophage migration. AAV8-mediated H19 overexpression aggravated arthritis in mice by promoting M1 macrophage polarization along with iNOS, IL-6, CCL8, CXCL9, CXCL10, CXCL11, MMP3, MMP13 and COX-2 expression in mononuclear cells isolated from the swollen ankle. GSK-J4, an inhibitor of KDM6A, suppressed the activity of lncRNA H19 in macrophages and ameliorated lncRNA H19-aggravated arthritis. In summary, the current study demonstrated that lncRNA H19 is upregulated in RA patients and arthritic mice. LncRNA H19 promotes M1 macrophage polarization and aggravates arthritis by upregulating KDM6A expression.