Tetsuzo Sugisaki

Nephritis-Associated Plasmin Receptor and Acute Poststreptococcal Glomerulonephritis: Characterization of the Antigen and Associated Immune Response

The role of nephritis-associated antigen as a virulence factor for acute poststreptococcal glomerulonephritis (APSGN) remains to be fully clarified. Nephritis-associated plasmin receptor (NAPlr) was previously isolated from group A streptococcus (GAS) and shown to bind plasmin(ogen). The nucleotide sequence of the naplr gene from GAS isolates obtained from patients with APSGN was determined. The sequence of the putative open reading frame (1011 bp) showed 99.8% identity among isolated strains. Homology screen revealed an exact match with streptococcal glyceraldehyde-3-phosphate dehydrogenase (GAPDH). NAPlr exhibited GAPDH activity in zymography, and it activated the complement pathway in vitro. In APSGN kidney biopsy specimens, NAPlr was observed mainly in the early stage of the disease (1 to 14 d after onset) but was not colocalized with either C3 or IgG as assessed by double immunofluorescence staining. Sera of patients with APSGN, patients with GAS infection without renal involvement, nonrenal pediatric patients, and healthy adults as controls were assayed for anti-NAPlr antibody titers. Anti-NAPlr antibodies were present most frequently in APSGN sera, and antibody titers were also significantly higher than in patients with GAS infection alone or in other control patients. Moreover, antibody titers remained elevated during the entire 10-yr follow-up period.

Glomerular plasmin-like activity in relation to nephritis-associated plasmin receptor in acute poststreptococcal glomerulonephritis.

A nephritogenic antigen for acute poststreptococcal glomerulonephritis (APSGN) was isolated recently from group A streptococcus and termed nephritis-associated plasmin receptor (NAPlr). In vitro experimental data indicate that the pathogenic role of NAPlr occurs through its ability to bind to plasmin and maintain its proteolytic activity. However, the mechanism whereby this antigen induces glomerular damage in vivo has not been fully elucidated. Renal biopsy tissues from 17 patients with APSGN, 8 patients with rapidly progressive glomerulonephritis, and 10 normal kidneys were analyzed in this study. Plasmin-like activity was assessed on cryostat sections by in situ zymography with a plasmin-sensitive synthetic substrate. Serial sections were simultaneously assessed for NAPlr deposition by immunofluorescence staining. Glomerular plasmin-like activity was absent or weak in normal controls and in patients with rapidly progressive glomerulonephritis, although tubulointerstitial activity was occasionally detected. Prominent glomerular plasmin-like activity was found in patients who had APSGN and in whom glomerular NAPlr was positive, whereas it was absent or weak in patients who had APSGN and in whom glomerular NAPlr was negative. The distribution of glomerular plasmin-like activity was identical to that of NAPlr deposition but was generally different from that of fibrin(ogen) deposition as assessed by double staining. The activity was abolished by the addition of aprotinin to the reaction mixture but was not altered by the addition of a matrix metalloprotease inhibitor, a cysteine protease inhibitor, or inhibitors of plasminogen activators. Thus, upregulated glomerular plasmin-like activity in relation to NAPlr deposition in APSGN was identified. This result supports the nephritogenic character of NAPlr and offers insight into the mechanism whereby this antigen induces nephritis.

Autoimmune cell-mediated tubulointerstitial nephritis induced in lewis rats by renal antigens

Abstract Lewis rats were injected with homogenates of renal or liver tissue or saline in complete Freunds adjuvant, plus pertussis vaccine, and were sacrificed at intervals ranging from 4 to 56 days. No renal lesions were observed in liver-or saline-injected animals. However, in rats injected with kidney preparations, severe tubulointerstitial nephritis was observed at 10–14 days; the lesions were characterized by irregular mononuclear cell infiltrates and tubular cell damage. At later intervals, milder more focal lesions were found. By immunofluorescence no tubulointerstitial deposits of immunoglobulin or C3 were detected. Transfer of lymph node, spleen, or peritoneal exudate cells from kidney-injected donors to normal Lewis rats resulted in focal interstitial infiltrates and tubular cell damage at 24 to 48 hr. Transfer of serum from kidney-injected donors or cells or serum from liver- or saline-injected donors produced no renal lesions. The migration of peritoneal macrophages from kidney-injected animals was inhibited by kidney, but not liver or spleen antigens. MIF activity was found in culture supernatants when lymph node or spleen cells from kidney-injected animals were cultured with kidney, but not with liver antigen preparations. The findings are interpreted as indicating that the tubulointerstitial lesions resulted from cell-mediated reactivity against kidney-specific antigens.

A randomized open-label comparative study of conventional therapy versus mizoribine onlay therapy in patients with steroid-resistant nephrotic syndrome (postmarketing survey)

BackgroundA previous double-blind 24-week clinical trial of mizoribine (MZ) vs placebo in steroid-resistant primary nephrotic syndrome (SRPNS) showed that MZ was more effective than placebo in reducing the rate of deterioration of renal function. The present study was conducted to evaluate the efficacy and safety of MZ in patients with SRPNS after 2 years’ treatment.MethodsA multicenter randomized open-label controlled trial in patients with SRPNS was conducted as a 2-year prospective postmarketing study.ResultsThere was a significant imbalance in the baseline serum albumin level (s-Alb) between the conventional therapy (CT) and MZ onlay therapy groups. Early dropouts were more frequent in the subset of patients in the CT group having a baseline s-Alb ≤3 g/dl. Therefore, the primary analysis (urinary protein level (UP)-improving effect) was performed using a mixed-effects model, with stratification according to the baseline s-Alb value. The analysis revealed that, in the subset of 34 patients with membranous nephropathy (MN) within the stratum of patients with baseline s-Alb ≤3 g/dl (n = 52), the rate of change (slope of change in the UP level/month), in terms of the log (UP+0.2), was −0.0577 in those allocated to the MZ group and −0.0227 in those allocated to the CT group (P = 0.058). In the stratum of patients with a baseline s-Alb >3 g/dl (n = 97), there were no significant differences in the UP between the two treatment groups. Hence, MZ onlay therapy was not considered to be efficacious in this group of patients. No serious adverse reactions to the drug were observed.ConclusionsThe present study yielded significant results, in that it suggested the possibility that long-term MZ therapy may afford further reduction of the UP, in addition to that obtained following CT, in particular, in MN patients in a severe nephrotic state.

Localization and Roles of CD44, Hyaluronic Acid and Osteopontin in IgA Nephropathy

An important function of CD44 is to act as a cellular receptor for hyaluronic acid and osteopontin. Cell-matrix interactions mediated by the CD44/hyaluronic acid receptor-ligand pair are involved in the regulation of leukocyte migration and activation. Osteopontin is a molecule associated with cell adhesion and migration and functions through binding to CD44. This study examined whether CD44, hyaluronic acid and osteopontin participate in the progression of IgA nephropathy. CD44 was expressed in mesangial cells, crescents, tubular cells and interstitial infiltrating cells in areas of tubulointerstitial injury. Hyaluronic acid was deposited in the capillary tuft of adhesion, crescents and the periglomerular area, and around damaged tubules. Osteopontin was expressed in tubular cells and interstitial infiltrating cells in areas of tubulointerstitial injury. The glomerular and interstitial deposition of hyaluronic acid correlated with the glomerular and interstitial expression of CD44. The interstitial expression of CD44 correlated with the interstitial expression of osteopontin. The expression of both CD44 and osteopontin in the interstitium correlated with the extent of tubulointerstitial damage. The expression of CD44 in the interstitium correlated with the severity of chronic glomerular lesions. The glomerular and interstitial CD44 and hyaluronic acid expression correlated with proteinuria, and interstitial CD44 and hyaluronic acid expression correlated with creatinine clearance rate. In summary, this study suggests that CD44 participates in the progression of IgA nephropathy by binding hyaluronic acid and osteopontin.

The Lowering Effect of Probucol on Plasma Lipoprotein and Proteinuria in Puromycin Aminonucleoside-Induced Nephrotic Rats

Hyperlipidemia associated with nephrotic syndrome was treated with probucol and the changes in plasma lipoprotein lipid concentration and urinary protein excretion were examined in puromycin aminonucleoside-induced nephrotic rats. Rats made nephrotic exhibited severe hyperlipidemia with increases in all major lipoprotein fractions. Probucol treatment of nephrotic rats significantly lowered plasma triglyceride (TG), cholesterol (Ch) phospholipid (PL) and apoprotein B associated with very-low-density and low-density lipoprotein and Ch and PL in high-density lipoprotein (HDL). Malondialdehyde (MDA) associated with the lipoproteins was significantly elevated in nephrotic rats and probucol treatment also lowered MDA concentration in all major lipoproteins. In control rats probucol moderately, but significantly, reduced plasma TG and HDL-Ch concentrations. Proteinuria associated with nephrosis was decreased significantly by treatment with probucol. Probucol treatment did not affect blood urea nitrogen and plasma creatinine levels. A significant positive correlation existed between the amount of protein excreted in urine and the plasma lipid concentrations in all nephrotic rats, suggesting that the hypolipidemic effect of probucol may attenuate proteinuria associated with nephrosis. These results suggest that probucol may be a favorable treatment for hyperlipidemia associated with nephrotic syndrome.

Microscopic polyangiitis after silicone breast implantation.

We describe the case of a patient who developed microscopic polyangiitis (MPA) after silicone breast implantation. A 60-year-old woman who had undergone silicone breast implantation was admitted to our hospital with complaints of general malaise and hematoproteinuria. She was diagnosed as having MPA with evidence of acute progressive renal failure, pulmonary hemorrhage, and positivity for myeloperoxidase-antineutrophil cytoplasmic antibody (ANCA). A renal biopsy showed severe necrotizing and crescentic glomerulonephritis with arteriolitis. The patient received high-dose steroids and plasma exchange treatment, but died of progressive pulmonary hemorrhage and multiple cerebral hemorrhage. Silicone implantation is associated with scleroderma, systemic lupus erythematosus, and rheumatoid arthritis. This case report indicates the possibility of the development of MPA after silicone breast implantation.

Acquired reactive perforating collagenosis in a nondiabetic hemodialysis patient: successful treatment with allopurinol.

The authors present a case of acquired reactive perforating collagenosis developed in a nondiabetic hemodialysis patient, who was treated successfully with allopurinol. Treatment of acquired reactive perforating collagenosis is difficult and often ineffective. The patient had been unresponsive to conventional treatments, but the pruritus was controlled, and skin lesions subsequently resolved after the treatment with allopurinol. Possible mechanisms of allopurinol treatment for acquired reactive perforating collagenosis are discussed.

Localization of nephritis-associated plasmin receptor in acute poststreptococcal glomerulonephritis

The nephritis-associated plasmin receptor is a recently identified nephritogenic antigen associated with acute poststreptococcal glomerulonephritis and proposed to play a pathogenic role, but its precise glomerular localization in acute poststreptococcal glomerulonephritis has not been elucidated. We therefore analyzed renal biopsy sections from 10 acute poststreptococcal glomerulonephritis patients by using immunofluorescence staining with anti-nephritis-associated plasmin receptor antibody and various markers of glomerular components. Nephritis-associated plasmin receptor was detected in the glomeruli of all patients, and double staining for nephritis-associated plasmin receptor and collagen IV showed nephritis-associated plasmin receptor to be predominantly on the inner side of the glomerular tufts. Nephritis-associated plasmin receptor-positive areas within glomerular tufts were further characterized with markers for neutrophils, mesangial cells, endothelial cells, and macrophages. In 6 of the patients, nephritis-associated plasmin receptor staining was seen mainly in neutrophils and to a lesser degree in mesangial and endothelial cells. In the other 4 patients, nephritis-associated plasmin receptor staining was seen mainly in mesangial cells and to a lesser degree in neutrophils and endothelial cells. In all patients, macrophages showed little staining. Elevated plasmin activity in glomerular neutrophils was identified by combining in situ zymography staining for plasmin activity and immunofluorescence staining for neutrophils. The glomerular localizations of nephritis-associated plasmin receptor and another nephritogenic antigen, streptococcal pyrogenic exotoxin B, were compared by double immunofluorescence staining and found to be similar. These findings indicate the nephritogenic potential of nephritis-associated plasmin receptor and offer valuable information with respect to the pathogenic mechanism of acute poststreptococcal glomerulonephritis.

A Case of Primary Antiphospholipid Antibody Syndrome with Acute Renal Failure Showing Thrombotic Microangiopathy

An 18-year-old woman complained of fever and edema and was admitted to Showa University Hospital for treatment of thrombocytopenia and deteriorating renal function. Laboratory studies demonstrated the presence of lupus anticoagulant (LA), prolongation of prothrombin time, hemolytic anemia, a negative Coombs’ test, the absence of antinuclear antibodies, and a normal fibrinogen level. Renal biopsy revealed mesangial hypercellularity, severe endocapillary cell damage, and double contour of the basement membrane walls. Immunofluorescence studies demonstrated focal, peripheral, and finely granular deposits for IgG, IgM, and IgA but were negative for fibrinogen. Electron microscopy showed glomerular capillary loops with subendothelial widening and subendothelial deposits, mesangiolysis, mesangial interposition, and marked luminal narrowing. Biopsy findings were consistent with thrombotic microangiopathy. The patient was treated with hemodialysis, methylprednisolone pulse therapy, and dipyridamole. After treatment, LA disappeared, the prothrombin time became normal, and renal function improved. The renal lesions in this patient were caused by primary antiphospholipid antibody syndrome. This case strongly suggests an important causal relationship between LA and renal lesions in thrombotic microangiopathy. We present this case to promote understanding of the pathogenesis of primary antiphospholipid antibody syndrome.