We report a 42-year-old man with subacute infectious endocarditis (IE) with septic pulmonary embolism, presenting rapidly progressive glomerulonephritis and positive proteinase 3-anti-neutrophil cytoplasmic antibody (PR3-ANCA). He had no previous history of heart disease. Renal histology revealed diffuse endocapillary proliferative glomerulonephritis with complement 3- (C3-) dominant staining and subendothelial electron dense deposit, mimicking C3 glomerulonephritis. Successful treatment of IE with valve plastic surgery gradually ameliorated hypocomplementemia and renal failure; thus C3 glomerulonephritis-like lesion in this case was classified as postinfectious glomerulonephritis. IE associated glomerulonephritis is relatively rare, especially in cases with no previous history of valvular disease of the heart like our case. This case also reemphasizes the broad differential diagnosis of renal involvement in IE.

Topiroxostat is a novel inhibitor of xanthine oxidase, and is postulated to exert a renoprotective effect. Puromycin aminonucleoside nephrosis (PAN) is a rat model of minimal change nephrotic syndrome. In this study, we examined whether topiroxostat ameliorates the kidney injury in PAN rats that was induced by a single intraperitoneal injection of PA (100 mg/kg body weight). Rats were divided into four groups: control rats, PAN rats, control rats treated with topiroxostat (1.0 mg/kg/day), and PAN rats treated with topiroxostat. Topiroxostat significantly reduced the amount of uric acid in the kidney cortex, while serum UA concentration remained unaffected by this treatment. Urinary protein excretion decreased significantly on day 10 in PAN rats upon topiroxostat treatment. Podocyte injury in PAN rats, as indicated by the reduction in WT‐1‐positive cell numbers and podocin immunoreactivity and foot process effacement, was partially yet significantly alleviated with topiroxostat treatment. In the kidney cortex, the increase in oxidative stress markers such as nitrotyrosine and 8‐hydroxy‐2‐deoxyguanosine (8‐OHdG) and the enhanced expressions of xanthine oxidase and NADPH oxidase 4 (NOX4) in PAN rats were significantly ameliorated by topiroxostat. Using cultured podocytes NOX4 expression was upregulated by adding 12 mg/dL UA into the culture medium. These results suggest that topiroxostat ameliorates proteinuria and kidney injury in PAN rats by lowering oxidative stress and tissue UA concentration. The renoprotective effects of topiroxostat could be attributed to its potential to inhibit xanthine oxidase and NOX4 in concert with suppression of intracellular UA production.

A 26-year-old man highly suspected of having antiglomerular basement membrane (GBM) disease was treated with corticosteroid pulse therapy 9 days after initial infection-like symptoms with high procalcitonin value. The patient required hemodialysis the next day of the treatment due to oliguria. In addition to corticosteroid therapy, plasmapheresis was introduced and the patient could discontinue hemodialysis 43 days after the treatment. Kidney biopsy after initiation of hemodialysis confirmed anti-GBM disease with 86.3% crescent formation. Physician should keep in mind that active anti-GBM disease shows even high procalcitonin value in the absence of infection. To pursue recovery of renal function, the challenge of the immediate and persistent treatment with high-dose corticosteroids plus plasmapheresis for highly suspected anti-GBM disease is vitally important despite the presence of reported predictors for dialysis-dependence including oliguria and requiring hemodialysis at presentation.

No abstract

We report a 32-year-old man with nephrotic syndrome and preceding symptom of infection. He had renal insufficiency, hypocomplementemia, and elevated titer of anti-streptolysin O. Renal biopsy showed mesangial hypercellularity and focal segmental endocapillary hypercellularity with double contour of the glomerular basement membrane (GBM). Immunofluorescence study showed granular C3 staining on the mesangial areas and glomerular capillary walls (GCWs) and linear immunoglobulin G (IgG) staining on GCWs. Electron microscopy revealed sporadic subepithelial humps, discontinuous small and thin deposits in the endothelial side of the GBM and mesangial deposits. He was diagnosed with infection-related glomerulonephritis (IRGN) with the striking finding of linear IgG staining, which is unusual in IRGN. The patient did not have diabetes mellitus or anti-GBM disease. The patient's serum seemed not to contain IgG, which can bind to GCW. He showed normalization of complement within two months after relief from infection symptoms and a trend toward improvement in proteinuria, hematuria and renal function over 14 months. We discuss the possible mechanisms of linear IgG staining in our case based on clinical and experimental studies on IRGN with cationic bacterial protein as antigen.