Cellulose Acetate Membrane Electrophoresis Based Urinary Proteomics for the Identification of Characteristic Proteins.

BACKGROUND: Analysis of urinary proteins using cellulose acetate membrane electrophoresis (CAME) is a useful and challenging method for the recognition of damaged sites in the kidney. However, protein content of each CAME fraction is still not completely understood. METHODS: In this study, an effective method of protein extraction from each band fractionated by CAME was established, which enabled us to examine the extracted proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry. RESULTS: Proteins were extracted from the gel and analyzed by mass spectrometry. In all, 31 proteins were identified, including 20 urinary proteins that were newly identified in the CAME-based analysis. CONCLUSION: This methodology was useful for identifying the proteins responsible for creating unique bands on CAME in a urine sample of a patient with drug-induced interstitial nephritis. These findings provide in-depth characterization of urinary protein contents in each CAME fraction.

Quantitative histological analysis of SM22α (transgelin) in an adriamycin-induced focal segmental glomerulosclerosis model.

BACKGROUND/AIMS: SM22α, transgelin, has been revealed to be specifically expressed in glomerular epithelial cells and interstitial cells, according to the nature of the renal injury. In this study, quantitative analyses of SM22α positivity were performed to investigate the pathological significance of its expression. METHODS: Kidney samples of adriamycin nephropathy underwent immunohistochemistry with a newly established anti-SM22α monoclonal antibody. The SM22α positivity was quantified by an image analyzer. The correlation of the histological values with biochemical data was investigated statistically. Microstructural localization of SM22α was studied by immunoelectron microscopy. RESULTS: SM22α was expressed along the dense basal microfilaments of degenerating podocytes, and diffusely in interstitial cells. Both the extent and intensity of SM22α expression in glomerular and tubulointerstitial area were correlated with the deterioration of renal function and the severity of proteinuria. Stepwise multiple linear regression analysis revealed that the extent of its positivity in glomerular or tubulointerstitial area was the determinant of the amount of proteinuria or the deterioration of creatinine clearance (Ccr), respectively. Inversely, the deterioration of Ccr was the most important predictor of SM22α expression. CONCLUSION: SM22α expression in podocytes and interstitial cells represented the severity of proteinuria and the deterioration of renal function. SM22α expression in renal tissues might be a hallmark of kidney diseases.

Expression of SM22α (transgelin) in glomerular and interstitial renal injury.

BACKGROUND/AIMS: SM22α, transgelin, is abundantly expressed in smooth muscle tissues and our previous work demonstrated that it is a novel marker of injured glomerular epithelial cells in rat antiglomerular basement membrane nephritis. In this study, we investigated SM22α expression in models of glomerular and interstitial renal injury. METHODS: The 5/6 nephrectomy (Nx) model, ischemia-reperfusion (I/R) model and puromycin aminonucleoside (PAN) nephrosis of rats were studied. Immunohistochemical analyses and immunoelectron microscopic studies of SM22α expression were performed. RESULTS: In the 5/6 Nx model, SM22α was first expressed in peritubular interstitial cells and was also expressed in injured glomerular epithelial cells at 8 weeks. In the I/R model, SM22α expression was induced in peritubular interstitial cells as early as 12 h after I/R with expression sustained at 7 days. However, SM22α was not detected in any glomerular cells or tubular epithelial cells. In PAN nephrosis, SM22α was only expressed in glomerular epithelial cells after 1 week, but expression was transient. CONCLUSION: SM22α was expressed in glomerular epithelial cells and interstitial cells in renal injury. SM22α is differentially upregulated in various models of renal injury and merits further study.

Injured kidney cells express SM22α (transgelin): Unique features distinct from α-smooth muscle actin (αSMA).

AIM: SM22α (transgelin) has been focused upon as a player in the process of phenotypic changes of types of cells. The SM22α expression in the rat anti-glomerular basement membrane (GBM) nephritis model and differences from an established phenotypic marker for the myofibroblast, α-smooth muscle actin (αSMA), were investigated. METHODS: The rat kidney tissues were processed for histological studies, immunohistochemical and immunoelectronmicroscopy analyses on days 0, 7, 28, 42 and 56 after injection of rabbit anti-GBM serum for the disease induction. RESULTS: Immunohistochemistry with anti-SM22α antibodies (Ab) revealed that kidneys of the nephritic rats on day 7 expressed SM22α in podocytes, crescentic cells and epithelial cells of Bowman's capsule. After 28 days, SM22α was also expressed in peritubular interstitial cells. Double immunofluorescence with anti-SM22α Ab and anti-αSMA Ab showed that SM22α was preferentially expressed in podocytes, whereas αSMA was positive in mesangial cells on day 7. After day 28, both molecules became positive in peritubular interstitial cells. CONCLUSION: SM22α was expressed in epithelial cells of inflamed glomeruli in the early phase, and then also in peritubular interstitial cells in the later phase of anti-GBM nephritis model. SM22α presented unique kinetics of expression distinct from αSMA.

Programmed initiation of hemodialysis for systemic amyloidosis patients associated with rheumatoid arthritis.

Reactive amyloidosis is a serious systemic disease in rheumatoid arthritis (RA). Amyloid protein can be deposited in kidneys, heart or gastrointestinal tract leading to organ failure. Renal involvement is a well-known complication in amyloidosis as this may culminate in end-stage renal disease (ESRD). Hemodialysis (HD) is always considered the treatment of choice for such patients; however, the prognosis is usually poor due to a large number of sudden deaths immediately following HD therapy. To circumvent the problem of HD initiation while instituting HD safety, we devised a plan to start HD and compare patient's survival with our previous data. Sixty-three patients were treated with HD. They were categorized according to the initiation of first dialysis. All patients were divided into planned, unplanned and programmed initiation groups. First dialysis that had been initiated as not urgent was considered 'planned' (20 patients). First dialysis that had been performed urgently for life-threatening renal insufficiency was considered 'unplanned' (31 patients). First dialysis that had been initiated as not urgent and according to our dialysis program was considered 'programmed' (12 patients). Survival of these 63 patients from the initiation of HD at 38 days was 75%, at 321 days was 50% and at 1,784 days was 25%. Patients with unplanned initiation of HD showed a significant poor survival compared with those of both planned and programmed initiation. Additionally, patients with planned and programmed initiation of HD showed no significant difference for the patients' survival. Our study demonstrates that patients with amyloidosis have a higher mortality rate. Nevertheless, programmed initiation of HD will improve the prognosis of patients with ESRD. Such possibility needs to be considered in more detail in the future.

Redox state of urinary albumin in patients with IgA nephropathy.

We examined the relationship between oxidative damage and molecular instability of urinary albumin in the urine of patients with IgA nephropathy (IgAN). As measure of oxidation, we detected the free thiol group at Cys34 in albumin (albumin-Cys34) using maleimide-PEG2-biotin reagent; because decreased levels of albumin-Cys34 are correlated with increased oxidation. The urine albumin-Cys34 level in all 30 patients with IgAN was decreased to varying extents. No correlations were found between urinary albumin/creatinine ratio and decreased urinary albumin-Cys34 level. Furthermore, decreases in urinary albumin-Cys34 were not accompanied by changes in serum albumin-Cys34. In diagonal-two-dimensional SDS PAGE analysis which reveals reduction-induced degradation of H2O2-treated human serum albumin, a similar pattern of albumin degradation was also detected in urine samples from patients with IgAN, indicating that structural alterations resulting from oxidative stress may be involved. Our findings suggest that redox state, in addition to urinary albumin concentration, may be an important indicator of post-translational modification and a potentially useful predictor of the kidney disease.

SM22alpha: the novel phenotype marker of injured glomerular epithelial cells in anti-glomerular basement membrane nephritis.

BACKGROUND/AIMS: Our previous comprehensive analysis of the genes expressed in kidneys with anti-glomerular basement membrane (GBM) nephritis using DNA microarrays showed that SM22alpha was one of the highly expressed genes. SM22alpha is a 22-kDa cytoskeletal protein that is exclusively expressed in smooth muscle cells. We investigated the localization of SM22alpha at mRNA and protein levels, and its pathological significance in anti-GBM nephritis kidneys. METHODS: Northern blot analysis, in situ hybridization, immunohistochemistry and double immunofluorescence studies were performed. The specific antibody (Ab) against SM22alpha was obtained by immunization of rabbits with recombinant rat SM22alpha protein. RESULTS: SM22alpha mRNA expression was upregulated in kidneys and inducibly expressed in the parietal and visceral glomerular epithelial cells in anti-GBM nephritis kidneys. Immunohistochemistry with anti-SM22alpha Ab showed that SM22alpha protein was localized in the same series of cells. Double immunofluorescence with anti-SM22alpha and anti-glomerular cell markers demonstrated that SM22alpha might be expressed in epithelial cells of injured glomeruli. In visceral epithelial cells, SM22alpha might be expressed in cells in which podocyte specific markers, podocalyxin and nephrin were lost. CONCLUSION: The injured glomerular epithelial cells in anti-GBM nephritis might undergo structural and functional alterations, including the expression of a smooth muscle marker, SM22alpha.

A case of mixed connective tissue disease complicated with thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura (TTP) is a rare complication of mixed connective tissue disease (MCTD). In this report, we describe the case of a 73-year-old Japanese woman with MCTD who developed fever, thrombocytopenia, and microangiopathic hemolytic anemia and was diagnosed with MCTD together with TTP. The activity of von Willebrand factor (vWF) cleaving metalloprotease ADAMTS13 was low and considered to have contributed to the disease activity of TTP. The patient died despite intensive treatment of plasma exchange (PEX) and steroid pulse therapy. Autopsy results revealed that the kidneys had platelet and fibrin thrombi, which occluded capillaries and arterioles. These findings were compatible with TTP and the decreased activity of ADAMTS13 was considered to be associated with the disease activity of TTP.

Long-term mortality outcome in patients with reactive amyloidosis associated with rheumatoid arthritis.

It is well established that amyloidosis is a serious clinical complication that can influence the prognosis of patients with rheumatoid arthritis (RA). The purpose of the study was to obtain information on the survival and the hemodialysis (HD) of patients with amyloidosis. Eighty patients (9 men and 71 women) who were diagnosed with amyloidosis by biopsy and definite or classical RA were studied retrospectively. The average duration of RA prior to the diagnosis of amyloidosis was 15.4+/-9.4 years. The average period from the diagnosis of amyloidosis to death was 67.4 months. Forty-nine patients died of the disease (32 cases with HD and 17 cases without HD). Thirty-one patients lived (7 cases with HD and 24 cases without HD). Regarding the survival of these patients, 49 (61.3%) of the 80 patients have died. Survival rate at 28 months was 75%; at 67 months, it was 50%; and at 111 months, it was down to 25%. Mortality rate was 11.9% per year. Survival rate in dialysis at 9.8 months was 75%; at 60.6 months, it dropped to 50%; and at 100.0 months, to 25%. As for patients' survival, high onset age of amyloidosis was the major determining factor for poor survival in these patients (p<0.001). Furthermore, male patients also had poor survival (p=0.07). The long-term results were very encouraging to initiate HD in patients with end-stage renal disease due to reactive amyloidosis associated with RA.

[Estimation of glomerular filtration rate by inulin clearance: comparison with creatinine clearance].

Inulin clearance (Cin) is widely believed to be the gold standard of the glomerular filtration rate (GFR). However, in Japan, Cin has not been officially recognized by the Ministry of Health, Labour and Welfare of Japan for clinical use. Creatinine clearance (Ccr) has been used to estimate the renal function of patients, but there have been many studies in which Ccr estimates were GFR falsely high because the metabolism and tubular excretion of creatinine widely varied according to the pathophysiological state of the patient. In the present study, we determined Cin and Ccr simultaneously in 116 adult patients with renal diseases and diabetic mellitus. The clearance study was performed by the modified Wesson's method. The inulin preparation was FFI-1010 (Fuji Yakuhin Co. Ltd.). Inulin in serum and urine was determined by the newly devised enzymatic assay (Toyobo Co. Ltd.), which is specific for inulin. The mean Cin was 35.0 +/- 14.4 ml/min/1.73 m2. The mean Ccr(the enzyme assay) was 63.6 +/- 24.1 ml/min/1.73 m2 and that of the kinetic Jaffe assay was 55.3 +/- 19.3 ml/min/1.73 m2. Mean Ccr/Cin was 1.93 +/- 0.73, 1.69 +/- 0.62, respectively. This ratio was significantly different(p < 0.05) in the degree of reduction of Cin, with values of 2.07 +/- 0.82 (Cin < 40 ml/min/1.73 m2) and 1.64 +/- 0.32(40 < Cin < 80 ml/min/1.73 m2), respectively. Only 8 patients were classified into the same degree of reduced renal function (the Guideline of Japanese Society of Nephrology). The findings of this study suggest that the GFR determined by Ccr could misjudge the renal function of patient and delay the administration of proper treatment of the patient. Introduction of Cin into the clinical field is necessary to avoid this delay.

Association of the MCP-1 gene polymorphism A-2518G with carpal-tunnel syndrome in hemodialysis patients.

Carpal-tunnel syndrome (CTS) in long-term hemodialysis patients is caused by the deposition of amyloid as well as by the local inflammatory process. The recruitment of monocytes/macrophages in the tenosynovium, promoted by chemokines such as monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha), is thought to play an important role in CTS development. The genetic polymorphism of these chemokines has been identified and their clinical function has been partly revealed We attempted to analyze the relationship between these polymorphisms and their susceptibility to CTS. The subjects of this study were 366 patients who underwent hemodialysis. Ninety-five patients received surgery for CTS. No significant difference was observed in the genotype distributions of MCP-1 or MIP-1alpha between patients who received CTS surgery and those that did not. However, with the use of a logistic regression model, the MCP-1 GG genotype was identified as a risk factor for the development of CTS, in addition to the duration and the age of initiation of dialysis, as confirmed by a Cox proportional hazards model. In conclusion, homozygosity for G at -2518 in the MCP-1 gene might be a candidate for the genetic marker of CTS development in Japanese hemodialysis patients.

Role of genetic polymorphism in the SA gene on the blood pressure and prognosis of renal function in patients with immunoglobulin A nephropathy.

The SA gene has been shown to be much more highly expressed in the kidneys of spontaneously hypertensive rats than in the corresponding wild-type strain. Genetic polymorphism of this gene has been shown to play a role in human hypertension, although the details of this association remain controversial. We investigated the possible associations between SA gene polymorphism and both hypertension and the prognosis of renal function in patients with immunoglobulin A nephropathy (IgAN). Genomic DNA was isolated from the peripheral blood of 367 individuals, including 274 patients with histologically proven IgAN and 100 controls without any history of renal disease. The SA genotype was determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) with Pst I. The frequencies of genotypes and alleles were not different between the patients with IgAN and those without renal disease. In the group without renal disease, the SA gene polymorphism was not associated with hypertension. However, in the patients with IgAN the A1 allele frequency was significantly higher in the hypertensives than in the normotensives. The renal survival of the patients with the A2 allele tended to be better than that of those without the A2 allele. The findings thus suggest that SA gene polymorphism may be associated with the renal prognosis of IgAN through its effect on blood pressure. Further, they suggest that the sensitivity to this gene polymorphism increases in patients with renal injury.

A case of Takayasu arteritis complicated with glomerulonephropathy mimicking membranoproliferative glomerulonephritis.

We report on a 65-year-old Japanese woman with Takayasu arteritis who developed severe proteinuria, hypertension, and renal dysfunction. Renal angiography demonstrated moderate irregular narrowing of both renal arteries. Renal biopsy showed glomerulonephropathy mimicking membranoproliferative glomerulonephritis (MPGN) with glomerular capillary wall thickening ("double contour") accompanied by mesangial cell proliferation and moderate increase of mesangial matrix without deposits of C3. Electron microscopy showed no subendothelial deposit and no circumferential mesangial interposition (CMI), and these findings are different from MPGN. In this report we present a case of Takayasu arteritis associated with glomerulonephropathy mimicking MPGN.

Molecular heterogeneity of urinary albumin in glomerulonephritis: comparison of cardiovascular disease with albuminuria.

BACKGROUND: Despite the unstable structure of urinary albumin in kidney diseases, urinary albumin fragments have been identified by denaturing methods such as two-dimensional electrophoresis. This study examined the relationship between the structural heterogeneity of urinary albumin and protease effects. METHODS: Urine samples from patients with glomerulonephritis (GN), cardiovascular diseases (CVD), and healthy subjects were analyzed by non-reducing sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE), Western blot, diagonal 2-dimensional non-reducing/reducing (d2D) SDS PAGE, and albumin zymography. RESULTS: The major band was monomer albumin in CVD and healthy subjects; however, 13 urinary albumin bands ranging from 55 to 172 kDa were identified by non-reducing SDS PAGE in GN. The results from d2D SDS PAGE showed urinary albumin polymerization between disulfide bridges, interactions with other proteins, and reduction induced degradation in GN patients. The results from albumin zymography showed that low-molecular mass forms of albumin did not necessarily correspond to high protease activity. Furthermore, concentrated healthy urine showed similar protease digestion as in GN without low-molecular mass of albumin. CONCLUSIONS: The molecular alterations observed cannot be explained only by urinary proteases. The specific alteration of urinary albumin molecules in GN can be attributed to different mechanisms to CVD.

A case of AA amyloidosis associated with rheumatoid arthritis effectively treated with Infliximab.

We report the case of a 55-year-old Japanese woman with reactive AA amyloidosis associated with rheumatoid arthritis, in which inflammatory disease was completely suppressed with infliximab. Nephrotic syndrome was observed and renal biopsy specimens revealed amyloidosis deposits. Treatment with infliximab normalized the serum amyloid A (SAA) protein level, and subsequently nephritic syndrome disappeared and her creatinine clearance improved. Serial gastrointestinal biopsy specimens showed marked lasting regression of amyloid deposits. Thus treatment with infliximab represents an important therapeutic strategy for AA amyloidosis associated with RA.

Rapid and sensitive electrophoresis of urinary protein clearly reveals the pathophysiological feature of renal diseases.

AIM: The diagnostic approach for renal diseases with the electrophoretic pattern of urinary protein on cellulose acetate (CA) membrane differentiates the causes of proteinuria. However, this method has not been used routinely because of its difficulty in obtaining a clear image. This study was performed in order to re-evaluate this method with an improved system. METHODS: Using the newly developed system of CA membrane electrophoresis and its visualization, we examined fresh urine from patients (n = 100) who subsequently underwent renal biopsy and compared the results with the histological findings. RESULTS: The improved method of urine electrophoresis with CA membrane provided clear images and was sensitive enough for urine samples to be applied without concentration. The profiles of proteinuria were clearly classified into three patterns: glomerular, tubular or mixed. The profiles exhibited a good agreement with the histological findings of renal biopsy. CONCLUSION: The recognition of damaged portions in kidney through the profiles of proteinuria by this system could be practically effective for understanding the kidney disease at bedside.

Mortality predictors after 10 years of dialysis: a prospective study of Japanese hemodialysis patients.

BACKGROUND: This work aimed to examine the predictive value for death of various clinical variables after long-term hemodialysis (HD). DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: A total of 947 patients (597 men and 350 women, aged 21 to 93 yr) who were undergoing maintenance HD in Niigata, Japan, were stratified into two cohorts: Those with >10 yr of prior HD at study enrollment (n = 391) and those with < or =10 yr of previous therapy (n = 556). The survival of patients was examined for up to 40 mo (1999 to 2003) with the Cox proportional hazards model. Baseline clinical and dialysis data and serum biochemistries were used as independent variables. For adjustment for bias in patient selection, patient survival in either cohort was analyzed separately. RESULTS: In patients with >10 yr of HD, high pulse pressure, cerebrovascular disease, low serum creatinine, and low Kt/V values were the mortality risk predictors, whereas for those with < or =10 yr of HD, age and cerebrovascular disease were independent risk predictors for death. Diabetes, coronary artery disease, serum albumin, and C-reactive protein were NS predictors in those with long-term HD. CONCLUSIONS: Providing adequate dosage of dialysis and achieving a better control of pulse pressure may further improve survival in selected patients who had undergone HD for >10 yr.

Mizoribine therapy for patients with lupus nephritis: the association between peak mizoribine concentration and clinical efficacy.

The clinical efficacy of mizoribine (MZR; 4-carbamoyl-1-b-D-ribofuranosylimidazolium) in patients with lupus nephritis was investigated. Thirteen Japanese patients with biopsy-proved lupus nephritis were enrolled in this study. A change in global assessments score, total protein (TP) of serum, serum creatinine, creatinine clearance (Ccr), proteinuria, titers of serum anti-ds DNA antibody, C3, C4, and hemolytic complement activity (CH50) were examined. Following MZR treatment, the level of urinary protein decreased (P < 0.05), whereas the level of Ccr increased (P < 0.05). Moreover, the level of TP significantly increased from 5.5 g/dl to 6.3 g/dl (P < 0.01) and the level of C3 increased significantly (P < 0.01). However, there was no change in the levels of both C4 and CH50. The titer of anti-ds DNA antibody significantly decreased (P < 0.05). The dosage of prednisolone could be tapered from 24.8 mg to 14.9 mg daily during the period. The clinical effects associated with MZR concentration in the blood revealed that there was a significant correlation between the peak MZR blood concentration of more than 0.66 microg/ml and clinical improvement (P = 0.021). Our results suggest that an optimal MZR blood concentration was important for the treatment of lupus nephritis.