HARS1 and idiopathic inflammatory myopathy: With this in mind, we were struck by the observation that circulating HARS levels are higher in anti-Jo-1-negative myositis patients, potentially because of the increased expression of HARS that is observed in regenerating muscle cells from patients with idiopathic inflammatory myopathy (IIM).21 This observation suggested that HARS could have a role in ameliorating inflammatory muscle conditions and led to us demonstrating that recombinant HARS was active in inhibiting T-cell activation in vitro and exhibits therapeutic activity using in vivo models of inflammatory disease.