Objective Urinary angiotensinogen (AGT) is a surrogate marker for intrarenal renin-angiotensin system (RAS) activity that plays an important role in the development of renal damage. Urinary AGT levels are determined by the filtration of plasma AGT through the damaged glomeruli and production of AGT in the proximal tubules. However, the relative merits of the filtration and production of urinary AGT levels in chronic kidney diseases (CKD) have not been clarified. Therefore, we investigated them in CKD patients. Methods We recruited 41 biopsy-proven patients diagnosed with IgA nephropathy (IgAN) in 31, membranous nephropathy (MN) in 5, and tubulointerstitial nephritis (TIN) in 5. The patients taking RAS blockers were excluded. Results The urinary albumin levels in MN patients were significantly higher and those in TIN patients significantly lower than in IgAN patients, and the urinary AGT levels in the MN and TIN patients were significantly higher than those in IgAN patients. Conversely, the urinary AGT-to-urinary albumin (urinary AGT/Alb) ratios were the same for IgAN and MN patients, and those of TIN patients were significantly higher than those of IgAN and MN patients. A multiple linear regression analysis revealed that the urinary AGT/Alb ratios had a significant positive association with IgAN and TIN after adjustments (β=0.75, and p<0.01). Conclusion These data suggest that the origins of urinary AGT may differ according to the etiology of renal damage [i.e. glomerular damage (such as IgAN and MN) or tubulointerstitial damage (such as TIN)], and a higher urinary AGT/Alb ratio, as in TIN, may reflect AGT production in the kidney.
Cutaneous and systemic plasmacytosis (CSP) is a rare lymphoproliferative disorder that mainly affects middle-aged Asian individuals. Although Castleman disease is often complicated with various renal involvements, glomerulonephritis associated with CSP, which is considered as a variant of Castleman disease, is rare. This report presents the case of a 41-year-old Japanese man with nephrotic syndrome associated with CSP. Renal biopsy findings showed focal segmental glomerulosclerosis (FSGS) and diffusely mild segmental mesangial proliferation. Plasma cell infiltration in the interstitium was not observed. Electron microscopic findings showed diffuse foot process effacement, localized involvement of subendothelial space widening with amorphous materials, and endothelial cell swelling. Lymph node biopsy findings denied Castleman disease. His skin regions and proteinuria were successfully treated with prednisolone and cyclosporine. The causal relationship between CSP and FSGS is unknown. However, increased serum levels of IL-6 and VEGF and decreased VEGF expression in the podocyte may contribute to renal lesions in patients with CSP. To our best knowledge, this is the first case of a patient with FSGS associated with CSP.
A 31-year-old woman was admitted to our hospital for thrombotic microangiopathy (TMA). She was diagnosed with systemic lupus erythematosus (SLE) and class V lupus nephritis. She had no aggravated SLE activity, Shiga toxin positivity, ADAMTS13 abnormality, or other causes of secondary TMA. Plasma exchange partially improved TMA, and eculizumab was introduced for suspected atypical hemolytic uremic syndrome (aHUS), as eculizumab was effective in suppressing the TMA activity. A kidney biopsy revealed diffusely organized crescents (pseudotubulization) with glomerular and arteriolar endothelial injury and subepithelial immune deposits. Thus, this was a rare case of lupus nephritis presenting as TMA with pseudotubulization possibly caused by aHUS.
A 30-year-old woman with proteinuria first noted at 26 weeks of gestation was admitted to undergo further evaluation. A renal biopsy revealed membranous nephropathy (MN). There was no evidence of any secondary MN. Prednisolone was initiated 6 months after delivery. Four months later, her urine protein became negative. Enhanced granular staining for thrombospondin type-1 domain-containing 7A (THSD7A) in the glomeruli was retrospectively detected in a biopsy specimen. A literature review revealed that 60% of cases of THSD7A-related MN occurred in women of childbearing age. Therefore, THSD7A-related MN should be considered in female patients presenting with idiopathic MN in childbearing age.
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