Inflammatory features, including symptoms, increased serum interleukin-6, and C-reactive protein, in IgG4-related vascular diseases.

Immunoglobulin (IgG) 4-related diseases (IgG4-RDs) are fibro-inflammatory conditions characterized by tumorous swelling and serum IgG4 levels. Intrapelvic IgG4-RD has been subclassified according to the localization site and aortic shape as IgG4-related aortic aneurysms (IgG4-AAs), periaortitis (IgG4-PA), and retroperitoneal fibrosis (IgG4-RF). The IgG4-AA pathogenesis would involve interleukin (IL)-6 upregulation, and Th2-predominant and Treg-activated immune conditions. We characterized the features of intrapelvic IgG4-RD lesions, including presence of vascular lesions. The clinical, serological, and pathological features, including cytokines concerning Th1/2 and Treg (IL-4, IL-6, IL-10, IL-13, and interferon-gamma) of patients with IgG4-AAs (n = 24), IgG4-PA (n = 8), and IgG4-RF (n = 10) were retrospectively compared. Clinical symptoms, such as low-grade fever, abdominal/lumber pain, and anemia, were frequently detected in IgG4-AAs but rarely in IgG4-RF. Serum IL-6 and C-reactive protein (CRP) were significantly higher in IgG4-AAs and IgG4-PA than in IgG4-RF. Pathologically, IL-6+ cells were more frequently detected in IgG4-PA and IgG4-AAs than in IgG4-RF. There were no noteworthy differences in the clinical complications, white blood cell counts, serum IgE, and serum and immunopositive cells of other cytokines between the subgroups. Among IgG4-AAs and IgG4-PA, serum IL-6 and IL-6+ cells correlated with CRP, aortic diameter, and periaortic fibrosis. IgG4-AA and IgG4-PA, but not IgG4-RF, were characterized by "inflammatory" features, such as increased CRP and serum/pathological IL-6, and clinical inflammatory symptoms; thus, IgG4-AA and IgG4-PA belong to the same group as IgG4-related vascular disease. High levels of CRP and IL-6 would be hallmarks of IgG4-related vascular disease.