Biomedical subjects

Fujio Shimizu

Publications and source records attributed to Fujio Shimizu.

52 records · Page 3Linked to original sources

PubMed2003

Role of megalin in endocytosis of advanced glycation end products: implications for a novel protein binding to both megalin and advanced glycation end products.

Advanced glycation end products (AGE) are filtered by glomeruli and reabsorbed and metabolized by proximal tubule cells (PTC). In renal failure, decreased renal AGE metabolism likely accounts for the accumulation in serum that is related to uremic complications. In diabetes, AGE generation is increased, and the handling mechanisms in PTC are likely associated with the pathogenesis of tubulointerstitial injury. It is therefore important to clarify the mechanisms of the AGE metabolism to develop a strategy for removing AGE in uremia and to elucidate the pathogenesis of diabetic nephropathy. To this end, this study focused on the molecular analysis of megalin, a multi-ligand endocytic receptor, in PTC. AGE uptake analysis was performed using the rat yolk sac-derived L2 cell line system established for the analysis of megalin's endocytic functions. The cells mediated specific internalization and degradation of AGE, which were significantly blocked by anti-megalin IgG, indicating that megalin is involved in the cellular processes. However, cell surface AGE-binding assays and ligand blot analysis revealed no evidence that megalin is a direct AGE receptor. Affinity chromatography and ligand blot analysis originally revealed that 200-kD and 400-kD proteins in the cells bind to AGE and the 200-kD protein to megalin in a Ca(2+)-dependent manner. The binding of megalin with the 200-kD protein was suppressed by receptor-associated protein (RAP), a ligand for megalin. In conclusion, megalin functions for endocytosis of AGE via an indirect mechanism. L2 cells express novel AGE-binding proteins, one of which may interact with megalin.

Animals↗

PubMed2003

Pathways to recovery and loss of nephrons in anti-Thy-1 nephritis.

The present histopathologic study of anti-Thy-1.1 models of mesangioproliferative glomerulonephritis in rats provides a structural analysis of damage development and of pathways to recovery and to nephron loss. As long as the disease remains confined to the endocapillary compartment, the damage may be resolved or recover with a mesangial scar. Irreversible lesions with loss of nephrons emerge from extracapillary processes with crucial involvement of podocytes, leading to tuft adhesions to Bowman's capsule (BC) and subsequent crescent formation. Two mechanisms appeared to be responsible: (1) Epithelial cell proliferation at BC and the urinary orifice and (2) misdirected filtration and filtrate spreading on the outer aspect of the nephron. Both may lead to obstruction of the tubule, disconnection from the glomerulus, and subsequent degeneration of the entire nephron. No evidence emerged to suggest that the kind of focal interstitial proliferation associated with the degeneration of injured nephrons was harmful to a neighboring healthy nephron.

Animals↗

PubMed2003

Bioengineered implantation of megalin-expressing cells: a potential intracorporeal therapeutic model for uremic toxin protein clearance in renal failure.

Patients who have renal failure and are on dialysis therapy experience serious complications caused by low-molecular-weight uremic toxin proteins normally filtered by glomeruli and metabolized by proximal tubule cells (PTC). Dialysis-related amyloidosis is one such complication induced by systemic deposition of amyloid proteins derived from 12-kD beta(2)-microglobulin (beta(2)-m). Despite the use of high-flux membrane hemodialysis devices and direct absorbent columns, the removal of beta(2)-m is suboptimal, because the effects are transient and insufficient. Megalin is expressed in the apical membranes of PTC and recognized as a multiligand endocytic receptor that binds numerous low-molecular-weight proteins, including beta(2)-m. This study tested the feasibility of an intracorporeal therapeutic model of continuous beta(2)-m removal using megalin-expressing cell implantation. By cell association and degradation assays, rat yolk sac-derived L2 cells were identified to internalize and degrade beta(2)-m via megalin. The cells were effectively implanted within the subcutaneous tissues of nude mice using a type I collagen scaffold and a method inducing local angiogenesis. After nephrectomy and intraperitoneal injection with (125)I-beta(2)-m, it was found that the implanted cells took up the labeled ligand, efficiently removing it from the blood. Bioengineered implantation of megalin-expressing cells may represent a new supportive therapy for dialysis patients to compensate for the loss of renal protein metabolism and remove uremic toxin proteins.

Animals↗

PubMed2003

IFN-inducible protein-10 has a differential role in podocyte during Thy 1.1 glomerulonephritis.

IFN-inducible protein-10 (IP-10/CXCL10) is a potent chemoattractant for activated T lymphocytes and was recently reported to have several additional biologic activities. In this study, the expression and the function in normal glomeruli and in Thy1.1 glomerulonephritis (GN) were investigated. The expression of IP-10 was detected in normal rat glomeruli mainly in the podocyte. The expression of IP-10 was also detected on the cultured podocyte. The IP-10 expression was elevated at the early phase of Thy1.1 GN. The double staining immunofluorescence study clearly demonstrated that the elevated expression of IP-10 was mostly detected in the podocyte and very partly in mesangial area. A receptor for IP-10, CXCR3, showed similar expression patterns to that of IP-10. Expressions of neither of IP-10 nor of CXCR3 were detected on the inflammatory cells. For elucidating the role of IP-10, the blocking study was carried out with monoclonal anti-IP-10 antibody. The monoclonal anti-IP-10 antibody treatment decreased the expression of IP-10 and podocyte-associated proteins such as nephrin and podocin that are reported to be essential for maintaining the podocyte function (IP-10, 53.0% to control; nephrin, 43.5%; podocin, 60.4%). The findings indicated that the anti-IP-10 treatment disturbed the podocyte function. The anti-IP-10 treatment given to the rats with Thy1.1 nephritis exacerbated proteinuria, mesangiolysis, and matrix expansion. Collectively, the findings indicated that IP-10 plays a role in maintaining the podocyte function. Also, the findings suggested that anti-IP-10 treatment exacerbated the glomerular alterations in Thy1.1 GN by disturbing the podocyte function.

Animals↗

PubMed2003

Genetic polymorphism of NPHS1 modifies the clinical manifestations of Ig A nephropathy.

Nephrin, the molecule responsible for congenital nephrotic syndrome of Finnish type, is crucial in maintaining the glomerular filtration barrier. Recently, its complete gene structure and common gene polymorphisms in its exons have been reported, although the functional and clinical significance of these polymorphisms has not yet been elucidated. We investigated a possible association of the NPHS1 polymorphisms with the development of Ig A nephropathy (IgAN), as well as the clinical and histologic manifestations in IgAN. A total of 464 Japanese subjects, including 267 patients with histologically proven IgAN and 197 healthy controls with normal urinalysis, were genotyped for the NPHS1 G349A, G2289A, and T3315C polymorphisms. The frequencies of the genotypes, alleles, and estimated haplotypes of NPHS1 polymorphisms were no different between patients with IgAN and the controls. Within the IgAN group, patients carrying at least one G allele of G349A tended to present with more proteinuria, lower renal function, and more severe histopathologic injury than those with the AA genotype, although the time from the first urinary abnormality to the renal biopsy was no different between both groups. The logistic regression analysis indicated that even after adjusting for the effect of proteinuria and hypertension the GG genotype of NPHS1 G349A was an independent risk factor for the deteriorated renal function at the time of diagnosis. This study suggests that the NPHS1 G349A polymorphism may be associated with heavy proteinuria and a decline in renal function in patients with IgAN.

Adolescent↗

PubMed2003

Urinary sediment podocalyxin in children with glomerular diseases.

BACKGROUND: In an immunofluorescence study using antibody to podocalyxin, we reported that urinary excretion of podocytes reflected podocyte injury in glomeruli. However, this method has some problems, since it is basically urine cytology. To overcome problems with this test, we measured whole podocalyxin content in urine sediment by enzyme-linked immunosorbent assay (ELISA). METHODS: Urinary sediment podocalyxin (u-sed-PCX) content of the first morning urine was quantified by ELISA after solubilization by detergent. We measured urine samples from children with various glomerular diseases and from healthy volunteers as controls. The glomerular diseases were classified into two categories: group I (inflammatory glomerular, 5 diseases) and group II (non-inflammatory glomerular, 3 diseases). RESULTS: (1) The level of u-sed-PCX was significantly higher in the urine from patients with glomerular diseases (groups I and II, median (interquartile range (IQR)): 2 (0.6-18.5), n = 111) compared with controls (0 (0-0.4), n = 135), and the level of u-sed-PCX in group I diseases (3.4 (0.6-27.2), n = 90) was significantly higher than those in group II diseases (0.9 (0.1-2.5), n = 21). (2) The presence of PCX in urine sediment was confirmed by Western blot analysis. (3) The degree of proteinuria was significantly correlated with the level of u-sed-PCX in group I (r(s) = 0.539, p < 0.001), but not in group II. (4) In group I, the level of u-sed-PCX was significantly higher in the acute phase than in the chronic phase (p < 0.01). (5) Comparison of histological findings of renal biopsies with u-sed-PCX showed a significant correlation in acute extracapillary lesions (p < 0.05). (6) Persistent high level of u-sed-PCX paralleled good histological progression in renal biopsies. CONCLUSION: Quantification of urinary sediment podocalyxin by ELISA is a reliable and useful laboratory marker for the estimation of the severity of active glomerular injury and a urinary index of acute extracapillary changes.

Adolescent↗

PubMed2002

Rapidly progressive, pauci-immune diffuse crescentic glomerulonephritis in an infant.

A Japanese male infant presented with nephrotic syndrome at 41 days. His renal function progressively deteriorated, and he died at 4 months of the age. An open renal biopsy revealed diffuse crescentic glomerulonephritis (CrGN) without immune complex deposition, which is not characteristic of the congenital nephrotic syndrome (CNS). Examination for nephrin antigen using rabbit anti-nephrin extra- and intracellular site antibodies was positive. These clinical observations suggest that the patient had a unique histological variant of CNS. This is the first report of rapidly progressive, pauci-immune diffuse CrGN in infancy.

Disease Progression↗

PubMed2002

mAb 5-1-6 nephropathy and nephrin.

It is well established that the glomerular capillary wall consists of three layers: endothelial cell, glomerular basement membrane, and the slit diaphragm bridging foot processes of glomerular epithelial cell. Which structure in the glomerular capillary wall represents the primary filter for retaining plasma proteins is not clearly elucidated. An anti-slit diaphragm monoclonal antibody (mAb) 5-1-6 causes massive proteinuria in rats by single intravenous injection, which clearly indicates that the slit diaphragm plays a critical role for maintaining the barrier function of the glomerular capillary wall. Recently, we concluded that mAb 5-1-6 recognized a rat homolog of nephrin, a gene product of NPHS1. The expression of nephrin decreased in puromycin aminonucleoside nephropathy and adriamycin nephropathy as well as mAb 5-1-6-induced nephropathy, which suggested that nephrin was involved in the development of proteinuria in these proteinuric states. In mAb 5-1-6 nephropathy, the slit diaphragm was maintained morphologically normal, although nephrin expression dramatically decreased. The finding suggested that nephrin was not a sole component of the slit diaphragm. To better understand the structure of the slit diaphragm, it is particularly important to identify other components that build up the structure of the slit diaphragm together with nephrin.

Animals↗

PubMed2002

Reflection-type hologram for atoms.

A cold metastable neon atomic beam was manipulated with a reflective amplitude hologram that was encoded on a silicon surface. A black-and-white pattern of atoms was reconstructed on a microchannel plate detector. The hologram used the enhanced quantum reflection developed by authors and was made of a two-dimensional array of rectangular low and high reflective cells. The surface of the high reflective cell was composed of regularly spaced roof-shaped ridges, while the low reflective cell was simply a flat surface. The hologram was the first demonstration of reflective atom-optical elements that used universal interaction between a neutral atom and solid surface.

Journal Article↗

PubMed2002

Blockade of CXCL10 protects mice from acute colitis and enhances crypt cell survival.

Crypt cell renewal is essential for normal intestinal homeostasis as well as mucosal regeneration following injury. However, the factors regulating crypt cell growth in pathological conditions are not fully understood. We report here that the endogenously produced chemokine CXCL10 regulates crypt cell proliferation. CXCL10 was constitutively expressed by basal crypts in mouse colon, but the expression of CXCL10 as well as CXCR3 was enhanced in the epithelium in the proliferative zone after oral administration of dextran sulfate sodium. Neutralization of CXCL10 protected mice from epithelial ulceration by promoting crypt cell survival without evidence of altered immune cell infiltration. Furthermore, recombinant CXCL10 administration into mice inhibited intestinal epithelial cell proliferation. These findings suggest that CXCL10 regulates crypt cell growth to maintain intestinal homeostasis in an autocrine or paracrine fashion. Thus, CXCL10 can be a new therapeutic target for inflammatory bowel disease by controlling the dynamics of epithelial homeostasis.

Acute Disease↗

PubMed2002

Therapeutic effect of sulphated hyaluronic acid, a potential selectin-blocking agent, on experimental progressive mesangial proliferative glomerulonephritis.

The initial event in the process of leukocyte infiltration is characterized by leukocyte rolling on the surface of the endothelium, which is mediated by selectins. P- and L-selectin bind to the sulphated sugar chains of their natural ligands, including sulphated glycolipids such as sulphatide. Recently, it has been demonstrated that sulphated glycolipids and sulphated oligosaccharides interfere with selectin binding pathways. This study synthesized sulphated hyaluronic acid (SHA), which is a potential selectin-blocking agent, and examined its therapeutic effect on the experimental progressive mesangial proliferative glomerulonephritis induced by anti-Thy-1 monoclonal antibody (1-22-3 MAb) after unilateral nephrectomy. The selectin-inhibitory effect of SHA in vitro was confirmed. SHA inhibited the binding of P- and L-selectin to sulphatide, which is a glycolipid ligand for P- and L-selectin, at a concentration of 1.5 micro g/ml and 100 micro g/ml. Immunohistochemical examination showed that P-selectin was up-regulated in the glomeruli in the 1-22-3 MAb nephritis model, while the ligands for L-selectin were not detected in the glomerular tufts. A single administration of SHA ameliorated proteinuria and glomerular leukocyte infiltration in 24 h after the injection of anti-Thy-1 MAb. Anti-P-selectin MAb, but not anti-L-selectin MAb, inhibited proteinuria and glomerular leukocyte infiltration. To examine further the therapeutic effect of SHA on chronic glomerulonephritis, SHA was administered daily from day 3 to day 14 in this model. Proteinuria and glomerular leukocyte infiltration were significantly diminished in SHA-treated rats on day 14. These results suggest that SHA ameliorated rat progressive mesangial proliferative glomerulonephritis by inhibiting P-selectin-dependent leukocyte infiltration in glomeruli. Sulphated oligosaccharides may be beneficial for the therapy of mesangial proliferative glomerulonephritis.

Animals↗

PubMed2002

FK506 ameliorates proteinuria and glomerular lesions induced by anti-Thy 1.1 monoclonal antibody 1-22-3.

BACKGROUND: We have previously reported that CD4 T lymphocytes and their cytokines contribute to development of Thy 1.1 glomerulonephritis (GN). FK506 is reported to suppress the production of Th1 cytokines. The aims of this study were to elucidate the role of Th1 cytokines on mesangial alteration and to examine whether FK506 is available for therapy of mesangial proliferative GN. METHODS: The effects of daily treatments of FK506 from day -5 and from day +1 of Thy 1.1 GN induction on glomerular alterations were analyzed. RESULTS: FK506 treatment with 1.0 and 0.3 mg/kg body weight (BW) daily from day 1 to day 4 significantly reduced the glomerular expression of mRNA for interferon-gamma (IFN-gamma; 1.0 mg/kg BW FK506, 32.4% to the placebo group, P < 0.01) and IL-2 (55.6%, P < 0.01) on day 5. FK506 treatment from day -5 of GN induction reduced proteinuria and glomerular alteration in a dose-dependent manner. Although no side effects were detected in rats with 0.3 mg/kg BW of FK506 treatment from day +1, the treatment also ameliorated proteinuria (day 14, 3.7 +/- 0.89 vs. 19.8 +/- 12.3 mg/100 g BW/day P < 0.05) and glomerular alterations [total cell number, 63.1 +/- 3.1 vs. 80.2 +/- 7.4, P < 0.01; matrix expansion, 0.90 +/- 0.30 vs. 1.34 +/- 0.27, P < 0.05; alpha-smooth muscle actin (alphaSMA) expression; 1.20 +/- 0.12 vs. 1.96 +/- 0.29, P < 0.01] on day 14. CONCLUSION: Th1 cytokines may play an important role in the development of mesangial proliferative glomerulonephritis, and could be targets for therapy. FK506 might be available for clinical use.

Animals↗

PubMed2002

Fractalkine expression and the recruitment of CX3CR1+ cells in the prolonged mesangial proliferative glomerulonephritis.

BACKGROUND: We established the reversible and the prolonged models of mesangial proliferative glomerulonephritis (GN) with anti-Thy 1 antibody 1-22-3. However, the essential factors leading to the prolonged glomerular alterations have not been identified. METHODS: The expressions of several chemokines and cytokines were compared in the reversible and the prolonged models. Expression of fractalkine and the number of the fractalkine receptor CX3CR1-positive cells in the glomeruli in the prolonged model were significantly higher than those in the reversible model. Then, the localization of fractalkine and the characteristics of CX3CR1+ cells were analyzed in glomeruli. To elucidate the significance of the fractalkine expression, we analyzed the expression in the model treated with angiotensin II receptor antagonist, candesartan. RESULTS: Immunostaining of fractalkine was detected on endothelial cells on the fifth day, and fractalkine staining also was detected in the mesangial area on day 14. Major parts of the CX3CR1+ cells in the glomeruli were macrophages, especially ED3+ cells. Candesartan treatment ameliorated the glomerular morphological findings at six weeks after disease induction. Although the treatment did not ameliorate the morphological finding at two weeks, decreased expression of fractalkine and CX3CR1+ were already detected at two weeks in rats treated with candesartan. CONCLUSIONS: Fractalkine expression and the recruitment of CX3CR1+ cells in glomeruli might play an important role in the development of the prolonged disease. These expressions could be predictors of the prolonged disease of the mesangial proliferative glomerulonephritis.

Animals↗

PubMed2002

Molecular structure and function of the slit diaphragm: expression of nephrin in proteinuric states and in developing glomeruli.

Nephrin is identified as a product of the gene mutated in a patient with congenital nephrotic syndrome of the Finnish type. To analyse the function of nephrin and the relationship of nephrin and the target antigen of nephritogenic anti-rat slit diaphragm monoclonal antibody (mAb) 5-1-6, the rat homologue of nephrin was cloned. The deduced amino acid sequence of rat nephrin shows 82.2% homology to human nephrin. Signal sequences of rat nephrin are 36 amino acids, whereas those of human nephrin are reported to be 22 amino acids. The localization of rat nephrin always coincided with that of mAb 5-1-6 antigen. The specific anti-nephrin antibody recognized the mAb 5-1-6-antigen complex. mAb 5-1-6 reacted with COS cells transfected with rat nephrin cDNA. These results demonstrate that nephritogenic mAb 5-1-6 identifies the extracellular domain of rat nephrin, thereby documenting that nephrin is a functional protein of the slit diaphragm. The staining pattern of nephrin shifted from a linear-like pattern to a discontinuous coarse granular pattern not only in mAb 5-1-6-induced nephropathy, but also in puromycin aminonucleoside nephropathy, adriamycin nephropathy and passive Heymann nephropathy. Rat nephrin is detected first on the basal and lateral side below the junctional complex at the S-shaped body stage. With the interdigitation of foot processes, nephrin becomes concentrated in the slit pore, and finally restricted in the site of the slit diaphragm bridging two adjacent foot processes.

Animals↗

PubMed2002

Angiotensin type 2 receptor antagonism confers renal protection in a rat model of progressive renal injury.

The role of the angiotensin type 2 (AT(2)) receptor in the pathogenesis of progressive renal injury has not been previously elucidated. The renal expression of the AT(1) and AT(2) receptors in subtotally nephrectomized rats (STNx) and the effects of AT(2) receptor blockade on renal injury were explored. Reduced renal expression of the AT(1) but not the AT(2) receptor was observed in STNx by reverse transcription-PCR, by in vitro autoradiography, and by immunohistochemical staining. The STNx rats were randomly assigned to AT(1) receptor antagonist valsartan, AT(2) receptor antagonist PD123319, or the combination of both for 4 wk. Increased proteinuria in STNx rats was reduced by PD123319 but to a lesser degree when compared with valsartan. Reduced gene and protein expression of the slit diaphragm protein nephrin was prevented by either valsartan or PD123319. Expression of osteopontin, proliferating cell nuclear antigen, and monocyte/macrophage infiltration was increased in STNx rats and was reduced by both AT(1) and AT(2) receptor antagonists. These effects of AT(2) receptor antagonism were observed in the presence of increased BP in STNx rats. These findings suggest that blockade of the AT(2) receptor alone confers a degree of renal protection; in particular, it seems that the combination of the AT(1) and AT(2) receptor antagonists may confer additive renal effects than either receptor antagonist as monotherapy.

Angiotensin Receptor Antagonists↗

PubMed2001

Specific antagonism of PDGF prevents renal scarring in experimental glomerulonephritis.

Glomerular mesangial cell proliferation and/or mesangial matrix accumulation characterizes many progressive renal diseases. Rats with progressive mesangioproliferative glomerulonephritis were treated from day 3 to day 7 after disease induction with a high-affinity oligonucleotide aptamer antagonist against platelet-derived growth factor-B chain (PDGF-B). In comparison with nephritic rats that received vehicle or a scrambled aptamer, treatment with the PDGF-B aptamer led to a significant reduction of mesangioproliferative changes, glomerular hypertrophy, podocyte damage, and glomerular macrophage influx on day 8. Both nephritic control groups subsequently developed progressive proteinuria and decreased renal function. On day 100, glomerulosclerosis, tubulointerstitial damage, glomerular and interstitial accumulation of types III and IV collagen, and overexpression of transforming growth factor-beta were widespread. All of these chronic changes were prevented in rats that received the PDGF-B aptamer, and their functional and morphologic parameters on day 100 were largely indistinguishable from non-nephritic rats. These data provide the first evidence for a causal role of PDGF in the pathogenesis of renal scarring and point to a new, highly effective therapeutic approach to progressive, in particular mesangioproliferative, renal disease.

Animals↗