Apolipoprotein E-associated Lipoprotein Glomerulo-tubulopathy

Abstract

A 32-year-old man was admitted for the evaluation of proteinuria (5.69 g/day). A light microscopic examination showed markedly dilated glomerular capillary loops with vacuolated areas in many glomeruli, and vacuolated areas were seen on peritubular capillaries in the tubulointerstitium. When electron microscopy specimens prepared by pre-fixation with glutaraldehyde and post-fixation with osmium tetroxide were used for oil red staining, the deposition was confirmed on the affected areas. A genetic analysis of apoE showed that the lipoprotein glomerulopathy was due to apoE-Sendai (Arg145Pro, p.R163P) heterozygosity, which was found in not only the patient but also his mother and twin brother.

Keywords: apolipoprotein E; lipoprotein glomerulopathy; oil red staining.

Figure 1.

Kidney biopsy findings. a-d: Collapsed glomerular capillaries with segmental sclerosis coexisted with marked dilatation of glomerular capillary loops that were seen as vacuolated areas (arrow). c, e: Vacuolated areas were seen in the tubulointerstitium (arrow). f, g: Vacuolated areas in the glomeruli and interstitium were surrounded by walls positive for CD34 (which stains vascular walls; arrow). h, i: Vacuolated areas in the glomeruli and interstitium were negative for CD68 (which stains macrophages; arrow). j, k: CD10 (which stains proximal tubules and glomerular capillaries) was positive in glomerular capillaries (arrow; j) and negative in the wall of the vacuolated area in the interstitium (arrow; k). l-n: Electron microscopy. o: Affected areas of intraglomerular and peritubular capillaries were stained gray (arrow) by toluidine blue staining. p: Affected areas of intraglomerular and peritubular capillaries were stained brown (arrow) by oil red staining. a: Hematoxylin and Eosin staining (original magnification ×400). b: Periodic acid Schiff staining (original magnification ×400). C: Masson trichrome staining (original magnification ×200). d, e: Periodic acid methenamine silver staining (original magnification ×400). f, g: CD34 staining (original magnification ×400). h, i: CD68 staining (original magnification ×400). j, k: CD10 staining (original magnification ×400). o: Toluidine blue staining (original magnification ×200). p: Oil red staining (original magnification ×100).

Figure 2.

A genetic analysis of apolipoprotein E.

Figure 3.

Clinical course (changes in ApoE protein and urinary protein after the kidney biopsy). Olmesartan (angiotensin II receptor antagonist, 20 mg daily), pemafibrate (triglyceride-lowering drug) (0.2 mg daily), esaxerenone (nonsteroidal anti-mineralocorticoid) (2.5 mg daily), triglyceride (TG).