Progresses In IgG4-related Interstitial Nephritis

IgG4-related disease(IgG4-RD)is a systemic fibroinflammatory disease that involves almost all organs.The diagnosis of IgG4-RD depends on histopathology: typical features are dense lymphoplasmacytic infiltrates and fibrillation,and a high percentage of plasma cells observed within lesions stain positively for IgG4.When an IgG4-related disease affects the kidney,it is called IgG4-related kidney disease(IgG4-RKD).IgG4-related tubulointerstitial nephritis(IgG4-TIN)is the most common renal manifestation of IgG4-RKD.Many patients with IgG4-TIN are diagnosed after IgG4-RD has been recognized in other organ systems,but the kidney may also be the first or the only site involved.The clinical manifestations of IgG4-TIN are diverse.The renal damage mainly manifests as small to moderate amount of proteinuria and microscopic hematuria.The pathological manifestations are renal interstitial fibrosis of varying degrees,infiltrating with a large number of lymphocytes and plasma cells.Fibrosis is dominant.Glucocorticoid is recognized as the most preferred treatment for IgG4-TIN treatment,while rituximab that consumes B cells is also considered to be an effective and safe treatment,and its use has increasedin recent years.For refractory or recurrent cases,treatment with a combination of immunosuppressive agents may also be considered.This article aims to introduce the pathogenesis,clinical features,diagnosis and treatment of IgG4-TIN.