Diagnosis and treatment of patients with IgA nephropathy in Japan

Abstract

Chronic kidney disease (CKD) is a worldwide public health problem that affects millions of people from all racial and ethnic groups. Although CKD is not one specific disease, it is a comprehensive syndrome that includes IgA nephropathy. As reported by the Japanese Society of Nephrology, 13.0 million people have CKD. In Japan, major causes of end-stage kidney disease are type 2 diabetic nephropathy, chronic glomerulonephritis, especially IgA nephropathy, hypertensive nephrosclerosis, and polycystic kidney disease. IgA nephropathy is characterized by polymeric IgA1 with aberrant galactosylation (galactose-deficient IgA1) increased in the blood and deposited in the glomerular mesangial areas, as well as partially in the capillary walls. The tonsils are important as one of the responsible regions in this disease. The clarification of the mechanism of galactose-deficient IgA1 production will pave the way for the development of novel therapies. The results of future research are eagerly awaited. At present, the most important therapeutic goals in patients with IgA nephropathy are the control of hypertension, the decrease of urinary protein excretion, and the inhibition of progression to end-stage kidney disease. Several investigators have reported that renin–angiotensin–aldosterone system inhibitors reduce levels of urinary protein excretion and preserve renal function in patients with IgA nephropathy. In Japan, tonsillectomy and steroid pulse therapy are more effective for patients with IgA nephropathy.

Age-adjusted global glomerulosclerosis predicts renal progression more accurately in patients with IgA nephropathy

“…IgAN is the most prevalent primary glomerulonephritis and that it accounts for 28.3% of the glomerular disease confirmed by biopsy 4 . Similar results have been shown in Japan 5 and in China 6 .…”

Clinical significance of serum and mesangial galactose-deficient IgA1 in patients with IgA nephropathy

“…Therapeutic regimens, including information about treatment with renin-angiotensin system inhibitors and oral steroids, were assessed and TSP implementation was also analyzed in the patients with IgAN. Indications and the regimen for TSP are detailed elsewhere [ 26 , 32 , 33 ].…”

“…These studies identified excess Gd-IgA1 in both serum and glomerular immune deposits of patients with IgAN [ 19 , 20 , 25 ]. Furthermore, the recently proposed multi-hit theory of IgAN states that overproduced Gd-IgA1 and autoantibodies against Gd-IgA1 subsequently form circulating immune complexes (IC), resulting in glomerular mesangial deposits followed by accelerated nephritis [ 19 , 26 ]. Thus, Gd-IgA1 is vital to the pathogenesis of IgAN, and Gd-IgA1 (s-Gd-IgA1) or mesangial Gd-IgA1 (m-Gd-IgA1) could serve as candidate disease-specific biomarkers that reflect severity and prognosis.…”

A cross-sectional analysis of clinicopathologic similarities and differences between Henoch-Schönlein purpura nephritis and IgA nephropathy

“…In addition, implementation of steroid pulse therapy combined with tonsillectomy (TSP) after RB was also analyzed. Indications for and the regimen for TSP in IgAN are detailed elsewhere [24,33,34].…”

“…These studies identified excess Gd-IgA1 in both serum and glomerular immune deposits in patients with IgAN [20][21][22][23]. Furthermore, the recently proposed multi-hit theory of IgAN states that overproduced Gd-IgA1 and autoantibodies against Gd-IgA1 subsequently form circulating IC, resulting in glomerular mesangial deposits followed by accelerated nephritis [20,24]. Thus, Gd-IgA1 is vital to the pathogenesis of IgAN.…”