A 79-year-old man was admitted to the Department of Nephrology, Kansai Electric Power Hospital on January 14, 2014, for proteinuria. He had been followed up for hypertension and dyslipidemia in a local clinic since the age of 50. He had experienced several vascular events, such as total occlusion in the common iliac artery at the age of 63 and two histories of cerebral infarction at the ages of 70 and 77. He had 30 years of smoking history but no alcohol habit. He had no family history of kidney disease except for one cousin showing end-stage renal disease of unknown etiology. During his initial admission to our hospital, his urine protein level was 5.4 g/g Cr, and serum albumin was 3.2 g/dL; he was discharged because his condition was stable. Ten months later, edema of his lower limbs worsened, and renal biopsy was performed on his second admission.\nOn the second hospitalization, physical examination showed the following: height of 169 cm, weight of 70 kg, body mass index of 24.5, and blood pressure of 180/88 mmHg. Laboratory findings revealed a nephrotic range of urine protein, 9.15 g/g Cr accompanying microscopic hematuria of dysmorphic 10 – 19 RBC/HPF, and total serum protein and albumin of 4.8 and 1.8 g/dL, respectively. Serum creatinine was 0.95 mg/dL, AST was 29 IU/L, ALT was 14 IU/L, and ALP was 188 IU/L. Serological examination revealed serum IgG, IgA, and IgM of 875, 344, and 52 mg/dL, respectively. Antinuclear and antineutrophil cytoplasmic antibodies were negative.\nLipid analysis revealed elevated total cholesterol (259 mg/dL), triglyceride (376 mg/dL), and LDL cholesterol (167 mg/dL) levels, and a low HDL cholesterol level (45 mg/dL). The serum ApoE level was 13.6 mg/dL (normal range: 2.8 – 4.6 mg/dL). An oral glucose tolerance test showed no abnormality, and his hemoglobin A1c was 5.7%. Although hypertriglyceridemia was marked, systemic abnormalities characteristic of hyperlipidemia, such as corneal opacities, xanthoma, and Achilles tendon hypertrophy, were not found. Moreover, the patient had no family history of hyperlipidemia and diabetes mellitus.\nLight microscopy (LM) revealed that the specimens contained 27 glomeruli, 8 of which showed global sclerosis (29.6%). Most glomeruli showed segmental sclerosis, infiltration of foam cells containing lipid deposits in capillary lumen (a). In periodic methenamine silver (PAM)-stained sections, spike formation and bubbling were detected on the glomerular basement membrane (GBM) (c, d). Mild to severe arteriosclerosis and arteriolosclerosis were also seen. Fibrosis was observed in ~ 20% of the whole interstitial area. Intriguingly, Sudan III staining was strongly positive not only in the mesangial and infiltrating foam cells but also in the focal capillary lumen in the glomerulus (b). Immunofluorescence (IF) studies demonstrated subtle granular staining for IgG along the capillary wall; however, C3 was not detected (data not shown). Electron microscopic (EM) findings analysis showed electron-dense deposits (EDDs) with a variety of densities and distributions. Highly-dense deposits accompanied by spike formation identical to MN were seen in the subepithelial area (a, b). In the subendothelial area, highly dense EDDs were detected but in higher magnification, and microbubbles were contained (a, b). Effacement of foot process was also accompanied with these depositions. In addition, EM findings demonstrated that the capillary lumina was filled with lipid deposits that did not show lamellar formation similar to “lipid thrombi” in LPG.\nPlasma ApoE phenotypes were analyzed by isoelectric focusing in polyacrylamide gel electrophoresis and immunoblotting analysis as previously reported [, ]. The patient’s sample showed the position of ApoE2/2 (a, Lane 1).\nThe APOE genotype was determined by restriction fragment length polymorphism (RFLP) analysis as described previously [, ]. The PCR products were digested with the restriction enzyme HhaI. Genotype ε2/2 in the patient was identified by 91- and 83-bp fragments (b, Lane 1). The ApoE Toyonaka (Ser197Cys) as shown in d was also confirmed by RFLP analysis digested with SacI (c). Genomic DNA was amplified by polymerase chain reaction (PCR) using oligonucleotide primers, sense 5′-CGTGCGGGCCGCCACTGTGAGCT-3′ and antisense 5′-TCGCATGGCTGCAGGCTTCGGCGTTC-3′. The 335-bp fragment after cleavage by SacI suggested normal c.644C of ApoE in codon 197 (Lane 3). The 358- and 335-bp fragments after cleavage by SacI showed a heterozygous novel mutation of ApoE Toyonaka (Lane 2). Direct sequencing of APOE DNA was performed as described previously []. Based on the results, we identified a homozygous polymorphism at codon 158 (e2/2: c.526 C>T: Arg158Cys) (data not shown) and a heterozygous missense mutation (C to G) in exon 4 leading to an amino acid substitution Cys (TGC) for Ser (TCC) at codon 197 (c.644 C>G: p.S215C: Ser197Cys) (d). All these findings were the same as that of a previous case of ApoE2/2 and ApoE Toyonaka showing MN-like glomerular histology [6].\nFor hypertriglyceridemia, fibrate 400 mg/day was started. Obtaining the results of the IF and EM studies, which did not deny immune-related MN like lesions, PSL 10 mg/day and cyclosporine (CyA) 75 mg/day for NS were started. These treatments brought about a substantial improvement of hypertriglyceridemia and complete remission of NS by 300 days after admission. During maintenance therapy with oral PSL 5 mg and CyA 75 mg/day, he had cerebral infarction and aspiration pneumonia. After withdrawal of CyA, his NS relapsed with an increase of proteinuria more than 1 g/day.
A 66-year-old male was referred to our center by his primary care physician because of the increase of proteinuria. He was diagnosed with diabetes at the age of 50 years but remained untreated. At the age of 60 years, he started voglibose at the diabetes center of our hospital. At the age of 66 years, urinary abnormality of protein 3+ and occult blood 1+ was pointed out, combined with simple diabetic retinopathy and a serum creatinine level of 0.96 mg/dl. He was referred to our center for further investigation, and a renal biopsy was performed. One of 11 glomeruli showed global sclerosis, and the other glomeruli showed massive foam cell infiltration in the glomerular capillaries and mildly expanded mesangium (fig. ). These foam cells immunohistochemically stained positive for cluster differentiation 68 (CD68) (not shown). Transmission electron microscope images also revealed foam cell infiltration mainly located in the capillaries containing scattered lipid droplets and lamellar bodies in their cytoplasm (fig. ). The glomerular basement membrane (GBM) showed mild thickening, and nodular lesions were formed in some glomeruli. The interstitium and tubules showed mild fibrosis and atrophy (25% of the cortical region), and a moderate degree of arteriolar hyalinosis was also found. No interstitial foamy cells or foamy tubular degeneration was found. Immunofluorescence study revealed no significant glomerular deposits. The patient's lipid profile showed type III HLP (table ). Apolipoprotein phenotype analysis showed a homozygosity of apoE2. A further DNA sequence analysis was performed as described previously [] and showed a nucleotide substitution of cysteine for arginine at codon 158 (Arg158Cys) of the apoE gene and no other mutations. Eicosapentaenoic acid was added to his statin therapy, but he progressed to end-stage renal failure and was started on dialysis 8 years after the diagnosis.