The provisional criteria and algorithm appear to be useful for clarifying the entity of IgG4-RKD and seeking underlying IgG4-RKD cases; however, further experience is needed to confirm the validity of these criteria.

The aim of our study was to clarify the association between immunoglobulin G(IgG) subclasses and the complement pathway in patients with idiopathic membranous nephropathy (MN). Immunofluorescence (IF) was performed in 16 MN patients and 20 controls using antibodies against IgG, IgA, IgM, C1q, C3c, C4d, IgG1, IgG2, IgG3, IgG4, mannose binding lectin (MBL), C4-binding protein (C4-bp), factor B, C5b-9, and CD59. MN was classified into two types, segmental MN (S-MN; six patients) and global MN (G-MN; ten patients), according to the distribution of IgG deposits along the glomerular capillary wall. No deposition of any antibody was found in the controls. IF revealed IgG1, IgG3, C1q, C3c, C4d, C4-bp, C5b-9, and CD59 deposits in patients with S-MN, whereas IgG1, IgG2, IgG3, IgG4, C3c, C4d, MBL, factor B, C4-bp, C5b-9, and CD59 deposits were detected in those with G-MN. There was a higher deposition of IG1, IgG2, and IgG4 in patients with G-MN than in those with S-MN, whereas the intensity of C1q deposits was higher in S-MN than in G-MN patients. In contrast, the intensity of factor B and MBL was higher in G-MN than in S-MN patients. This is the first report of S-MN patients showing complement activation of the classical pathway associated with IgG1 and IgG3 and G-MN patients showing complement activation of both the alternative and lectin pathways associated with IgG2 and IgG4.

OBJECTIVEClinicopathological characteristics, renal prognosis, and mortality in patients with type 2 diabetes and reduced renal function without overt proteinuria are scarce. RESEARCH DESIGN AND METHODSWe retrospectively assessed 526 patients with type 2 diabetes and reduced renal function (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m 2 ), who underwent clinical renal biopsy and had follow-up data, from Japan's nationwide multicenter renal biopsy registry. For comparative analyses, we derived oneto-two cohorts of those without proteinuria versus those with proteinuria using propensity score-matching methods addressing the imbalances of age, sex, diabetes duration, and baseline eGFR. The primary end point was progression of chronic kidney disease (CKD) defined as new-onset end-stage renal disease, decrease of eGFR by ‡50%, or doubling of serum creatinine. The secondary end point was all-cause mortality. RESULTS Eighty-two patients with nonproteinuria (urine albumin-to-creatinine ratio [UACR]<300 mg/g) had lower systolic blood pressure and less severe pathological lesions compared with 164 propensity score-matched patients with proteinuria (UACR ‡300 mg/g). After a median follow-up of 1.9 years (interquartile range 0.9-5.0 years) from the date of renal biopsy, the 5-year CKD progression-free survival was 86.6% (95% CI 72.5-93.8) for the nonproteinuric group and 30.3% (95% CI 22.4-38.6) for the proteinuric group (log-rank test P < 0.001). The lower renal risk was consistent across all subgroup analyses. The all-cause mortality was also lower in the nonproteinuric group (log-rank test P 5 0.005). CONCLUSIONSPatients with nonproteinuric diabetic kidney disease had better-controlled blood pressure and fewer typical morphological changes and were at lower risk of CKD progression and all-cause mortality.

This nationwide study on kidney biopsy of 600 cases with type 2 diabetes revealed that pathologic findings (presence of nodular lesions, exudative lesions and mesangiolysis) were strong predictors of kidney events in low-risk patients.

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