Limitation of glucocoriticoid treatment and novel therapy for IgG4-related disease:

Abstract

  IgG4-related disease（IgG4-RD）is a newly recognized systemic fibroinflammatory condition characterized by tumor-like swelling of involved organs, elevated levels of serum IgG4, diffuse infiltration of IgG4-positive plasma cells, and fibrosis in lesions. The most frequently involved organs are salivary and lacrimal glands（so-called Mikulicz’s disease）, and pancreas（autoimmune pancreatitis type 1）. In addition, bile ducts, kidney, retroperitoneum, aorta and lung are often affected in a synchronous or metachronous clinical course. It is necessary to suspect IgG4-RD in case of mass-forming lesions of unidentified origin in those organs. First-line treatment for IgG4-RD is glucocorticoids（GC）based on the prompt, positive response to GC. However, osteonecrosis of femoral head has occasionally occurred after starting GC treatment in IgG4-RD patients like other rheumatic diseases. Because long-term administration of GC has been inevitable due to high rate of relapse in the clinical course, it is necessary to pay attention to adverse effects of GC such as osteoporosis and opportunistic infections. Although the etiology of IgG4-RD has been not been elucidated, several molecules and immune cells involved in the pathological condition of IgG4-RD are being identified and introduction of therapies targeting these molecules and cells is expected. In fact, favorable treatment outcomes with monoclonal antibodies targeting CD20 and CD19 present on B cells have been reported.