Tohru Kokubo

Steroid Therapy during the Early Stage of Progressive IgA Nephropathy

This study was undertaken to clarify the effect of corticosteroids on the long-term clinical course of the early stage of progressive IgA nephropathy. The early stage of progressive IgA nephropathy was defined as having moderate proteinuria between 1 and 2 g/day, creatinine clearance values of 70 ml/min or more, and a histological severity score of 7 or more. The number of patients who fulfilled these three conditions during 12 years from 1972 and then were continuously followed up for 10 years or more in our renal unit was 46. Twenty of them received steroid treatment for an average period of 18 months, and the remaining 26 patients had no steroid treatment. The initial data of proteinuria, creatinine clearance values, frequency of hypertensive cases, and histological scores of 7 or more were not different between the two groups: 1.4 +/- 0.4 vs. 1.3 +/- 0.3 g/day, 85 +/- 14 vs. 88 +/- 13 ml/min, 25 vs. 38%, and 10.7 +/- 2.5 vs. 11.0 +/- 3.0, respectively. During the follow-up period of 10 years, the renal survival rate was significantly different between the two groups (100 vs. 84% 5 years after starting therapy and 80 vs. 34% 10 years later; p < 0.001). The final creatinine clearance values were significantly different between the two groups (54 +/- 35 vs. 20 +/- 29 ml/min; p < 0.005). On the other hand, the patient groups with mild histological changes or decreased renal function due to moderate proteinuria showed no significant differences in the final outcome. These results indicate that corticosteroids are beneficial in stabilizing the renal function for a long time during the early stage of progressive IgA nephropathy, although this study was not a randomized one.

Aggregated human serum immunoglobulin A1 induced by neuraminidase treatment had a lower number of O-linked sugar chains on the hinge portion

A part of human serum immunoglobulin A1(IgA1) was aggregated by treatment with neuraminidase. Aggregated IgA1 was separated from non-aggregated IgA1 by gel permeation chromatography. The prepared asialo-hinge glycopeptide (asialo-HGP) from both IgA1 subfractions was treated with beta-galactosidase to determine the number of beta-linked sugar chains attached on the hinge region. Removal of the galactose residue from asialo-HGP resulted in the HPLC separation of three major peaks. MALDI-TOFMS analysis of the glycopeptides also indicated the presence of three HGP components with three, four and five N-acetylgalactosamine (GalNAc) residues, respectively. Comparison of their relative content among the glycopeptide components showed a higher content of the HGP component with a lower number of GalNAc residues on aggregated IgA1. Thus, asialo-HGP prepared from aggregated IgA1 induced by neuraminidase treatment had an incomplete core structure of O-linked oligosaccharides. Especially, the result suggested that the reduced number of the attached O-linked oligosaccharides on IgA1 take part in phenomena such as self-aggregation of asialo-IgA1.

Application of matrix-assisted laser desorption ionization time-of-flight mass spectrometry to the analysis of glycopeptide-containing multiple O-linked oligosaccharides

In our previous report [Iwase et al., J. Biochem., 120 (1996) 393], the number of O-linked oligosaccharide chains on the hinge region of IgA1 was estimated by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS). In this experiment, the number of non-substituted N-acetylgalactosamines and Galbeta1,3GalNAc residues, as the core O-linked oligosaccharide structure per heavy chain of normal human serum IgA1, was estimated by digestion of the asialo-hinge glycopeptide with alpha-N-acetylgalactosaminidase (GalNAc-ase) or endo-alpha-N-acetylgalactosaminidase (endo-GalNAc-ase). GalNAc-ase treatment of the asialoglycopeptide produced two major peaks, one being a glycopeptide containing four GalNAc and four Gal residues, and the other contained three GalNAc and three Gal residues. Treatment with endo-GalNAc-ase also produced a nearly equal amount of the two peaks, with the naked hinge peptide and the peptide having one GalNAc residue. From those results, we concluded that the asialo-hinge glycopeptide was composed of three components bearing four Galbeta1,3GalNAc and one GalNAc, only four Galbeta1,3GalNAc, and three Galbeta1,3GalNAc and one GalNAc, respectively. This method was useful for determining the glycoforms on the IgA1 molecule with respect to the core O-linked oligosaccharide structure.

Detection of gender difference and epitope specificity of IgG antibody activity against IgA1 hinge portion in IgA nephropathy patients by using synthetic hinge peptide and glycopeptide probes.

BACKGROUND AND AIMS There are many reports on the presence of an incompletely glycosylated O-linked oligosaccharide(s) on the IgA1 hinge region in some immunoglobulin (IgA) nephropathy patients. Furthermore, the production of an antibody against the naked hinge peptide portion was reported in an IgA nephropathy patient. In this report, characterization of the IgG antibody against the hinge portion was carried out by using synthetic hinge glycopeptide probes. METHODS AND RESULTS The following synthetic hinge peptide and glycopeptides were prepared: 19mer peptide, V-P-S-T-P-P-T-P-S-P-S-T-P-P-T-P-S-P-S (designated HP), the peptide having a single alpha-linked GalNAc residue at positions 4, 7, 9, 11 and 15 (4 GN - 15 GN, respectively) and the same peptide having five GalNAc residues at all five positions (GN5). The mean value of the antibody activity against these probes was compared with each other. The highest activity against the naked hinge peptide (HP) and lowest activity against the fully glycosylated hinge peptide (GN5) were obvious. As attachment of GalNAc to position 4 or 11 on the peptide brought about a significant reduction of the activity against the naked hinge peptide, the P-S-T-P sequence included in both positions was thought to be the most probable site recognized by these antibodies. As an additional unexpected observation, a gender difference in this antibody activity against all the probes was found. The antibody activity in a female was significantly higher compared with that in a male. CONCLUSION Because the frequency of incidence of IgA nephropathy is known to be slightly higher in males, this gender difference might indicate a protective meaning to remove aberrantly glycosylated molecules from the patients serum.

Prognostic prediction of long-term clinical courses in individual IgA nephropathy patients

Summary: This study was performed to evaluate predictive factors determining a long‐term prognosis in individual IgA nephropathy patients. One hundred and fifty‐five patients who have been continuously followed up for 10 years or more from the first renal biopsy in our renal unit were the subjects of this study. As predictive factors, initial proteinuria, initial creatinine clearance (Ccr) values, initial hypertension, histological severity (eight parameters and total score), persistence of massive proteinuria (% duration of massive proteinuria; % DP) and persistence of hypertension were evaluated. All 25 of the 155 patients who had either high total score of 17 or more, or less than 60 mL/min in initial Ccr values, went onto haemodialysis (HD). However, all 38 patients who had TS of 4 or less did not. The remaining 95 patients who showed both total score from 5 to16 and Ccr values of 60 mL/min or more were divided into two groups: HD group (32 cases) and non‐HD group (63 cases). All patients but one in the HD group showed 30% or more in %DP, and 50 of 63 patients in the non‐HD group snowed 30% or less (P < 0.001). Multivariate analysis using a logistic model of factors associated with prognosis indicating HD revealed that %DP was the highest relative risk (19.5) compared with interstitial fibrosis (10.2), initial Ccr values (6.8), persistent hypertension (4.2) and initial proteinuria (1.4). These results indicated that the most reliable, independent factor determining a long‐term individual prognosis is persistent massive proteinuria of 1.0 g/day or more.

A Case of Rheumatoid Arthritis with Renal Tubular Amyloidosis

A Case of Rheumatoid Arthritis with Renal Tubular Amyloidosis Y. Yoshiyuki Hiki A. Akira Horii T. Tohru Kokubo S. Shigeko Ishikawa T. Takehiko Sugiyama H. Hidekazu Shigematsu Y. Yutaka Kobayashi Department of Medicine, School of Nursing, and Medicine, Kitasato University, Sagamihara City, Department of Medicine, Hiratsuka-Kyousai Hospital, Hiratsuka City, Department of Pathology, School of Medicine, Shinshu University, Matsumoto City, Japan

Recklinghausen's neurofibromatosis associated with membranous nephropathy.

Yutaka Kobayashi, MD, Department of Medicine, School of Medicine, Kitasato University, 1-15-1, Kitasato, Sagamihara 228 (Japan) Dear Sir, We present here a rare case of Recklinghausen’s neurofibromatosis associated with membranous nephropathy. A detailed evaluation of the clinicopathological findings is described. A 68-year-old Japanese woman was admitted to Kitasato Universitiy Hospital on May 30,1990, because of general edema and severe proteinuria. She had a history of Recklinghausen’s neurofibromatosis since 1964. Her proteinuria was first pointed out in April 1989 and continued since then. In December 1989, general edema developed. On admission, physical examination revealed a blood pressure of 140/80 mm Hg and general edema. There were multiple subcutaneous neurofibromas covering the entire skin surface involving cafe au lait spots on the right knee and the axilla. Laboratory findings were as follows: urinary protein 3-4 g/day, sediment RBC negative, WBC count 6,900/μl with normal differentials, RBC count 351 × lOVμl, hemoglobin 10.6 g/dl, platelets 31.3 × lOVμl, ESR 59 mm/h, serum total protein 4.7 g/dl, albumin 3.1 g/dl, total cholesterol 404 mg/dl, urea nitrogen 22 mg/dl, crea-tinine 0.8 mg/dl, IgG 380 mg/dl, IgA 77 mg/ dl, IgM 131 mg/dl, CH50 33 U/ml, C3 56 mg/ dl, C415 mg/dl, ANA negative, RAtest negative, circulating immune complexes negative, Hbs-antigen negative, syphilis reaction negative, Ccr 62 1/day. Malignanacy survey revealed no abnormality. Renal biopsy was performed on the 21st hospital day. The histological findings were compatible with membranous nephropathy. The biopsy specimen contained 10 glomeruli showing a diffuse moderate thickening of the capillary walls. Silver impregnation revealed diffuse vacuolization of the capillary walls and the presence of perpendicular projections extending from the basement membrane. Significant cellular proliferations were unremarkable. Two of the glomeruli showed segmental sclerotic changes with some foam cells. Tubular degeneration and atrophy were focally observed. Interstitial fibrosis and mononuclear cell infiltration were also noted in some parts. Interstitial foam cells were also seen. Ultrastructurally, diffuse subepithelial and intramembranous dense deposits were observed. The glomerular basement membrane was thickened with wide spike formation and included intramembranous lucent deposits in some parts. Newly formed glomerular basement membrane materials were also seen. Subendothelial and mesangial dense deposits were not observed at all. Im-munohistochemically, IgG and C3

Mutual separation of hinge-glycopeptide isomers bearing five N-acetylgalactosamine residues from normal human serum immunoglobulin A1 by capillary electrophoresis

Immunoglobulin A1 (IgA1) from normal human serum is known to have O-linked sugar chains, sialylated Galbeta1,3GalNAc, in the hinge portion. In order to reduce the microheterogenity of the sugar chain, the hinge glycopeptide prepared from IgA1 was sequentially treated with neuraminidase and beta-galactosidase. The asialo-, agalacto-hinge glycopeptide (HGP-SG) composed of a 33-mer peptide (HP33) and N-acetylgalactosamine (GalNAc) residues was obtained. The HGP-SG was separated into three major peaks, A, B and C, by high-performance liquid chromatography (HPLC). Each glycopeptide fraction was further separated by capillary electrophoresis (CE). Peaks A, B and C with HPLC abundantly contained HP33 bearing five and six N-acetylgalactosamine residues (HGP33-5,6GN), HGP33-4,5GN and HGP33-3,4GN, respectively. Among these glycopeptide peaks, only the HGP33-5GN peak was partly split into two peaks based on the CE analysis - HGP33-5GN-alpha and -beta. The glycopeptide, HGP25-5GN shortened by the thermolysin digest of HGP33-SG was also well separated into the alpha and beta forms by CE analysis. No differences in their mass and peptide portion were observed between HGP25-5GN-alpha and -beta. Therefore, the obtained result might indicate that HGP25-5GN-alpha was an isomer of HGP25-5GN-beta differing in its stereospecific structure of the peptide portion and/or the attachment site of the GalNAc residue.

Lipoprotein Derangement during Steroid Treatment in Minimal-Change Nephrotic Syndrome

To study the pathophysiology of hyperlipidemia in nephrotic syndrome, we compared lipid metabolism in the nephrotic stage (stage 1) and in stage 2, when albuminuria had subsided, in 11 patients with minimal-change disease treated with corticosteroid. High-density lipoprotein (HDL) levels were decreased and HDL contained more cholesterol and triglyceride per unit of protein in stage 1 in the patients than in age-matched healthy controls. The urinary protein level was positively correlated only with low-density lipoprotein (LDL) levels, suggesting that the increased albumin clearance stimulated LDL production. Serum cholesterol levels were positively correlated with apolipoprotein E levels and were negatively correlated with lecithin-cholesterol acyltransferase activity in the nephrotic stage; the opposite correlations were seen in controls. Although triglycerides in HDL had normalized at stage 2, triglycerides in LDL and very-low-density lipoprotein did not return toward normal until stage 3, when serum cholesterol levels were normalized.

A case of severe IgA nephropathy associated with psoriatic arthritis and idiopathic interstitial pneumonia.

A patient is described with severe IgA nephropathy associated with psoriatic arthritis, idiopathic interstitial pneumonia and brain hemorrhage that developed serially over one and a half years. The histological findings of the renal biopsy showed severe endo‐and extracapillary proliferative glomerulonephritis. Massive IgA deposits were observed by immunoflurorescence not only in the mesangium but also along the capillary walls. Electron microscopy revealed abundant electron‐dense deposits in the mesangial and subendothelial areas. The overlapping or coexistence of these conditions has rarely been reported.