Involvement of transglutaminase-2 in pathological changes in renal disease.

BACKGROUND: Transglutaminase (Tg)-2 is shown to be related to renal fibrosis. However, its roles in human kidney disease have not been fully studied. METHODS: Using immunohistochemistry, we examined Tg-2 expression in renal biopsy specimens from 22 patients with IgA nephropathy (IgAN) and correlated the intensity of Tg-2 staining with clinical and histopathological parameters. We compared the distribution and intensity of Tg-2 staining with those of transforming growth factor (TGF)-beta staining. RESULTS: In normal human kidneys, Tg-2 staining was not significant. In IgAN kidneys, glomerular Tg-2 staining correlated with serum creatinine (S-Cr), creatinine clearance (Ccr), urinary protein excretion, glomerular sclerosis, and mesangial cell proliferation. Tubulointerstitial Tg-2 correlated with S-Cr, Ccr, N-acetyl-beta-glucosaminidase, urinary beta(2)-microglobulin, and tubulointerstitial injuries. Tg-2 staining in the vicinity of vascular poles of glomeruli preceded the development of mesangial lesions, and was more remarkable in cases with renal impairment. The distribution and intensity of Tg-2 staining were not consistent with those of TGF-beta staining. In glomerular crescents, Tg-2 staining was remarkable. CONCLUSION: The present study showed a correlation between Tg-2 expression and renal function and pathological changes. Tg-2 expression in the vicinity of vascular poles was notable because that may be an initial marker of glomerular injury.

Impact of hypertension and hypertension-related vascular lesions in IgA nephropathy.

It remains poorly understood whether vascular pathology plays an important role in the progression of renal parenchymal disease in humans. Moreover, in the case of hypertensive patients with mild proteinuria, nephrologists tend to make a diagnosis of benign nephrosclerosis without renal biopsy. Among 172 patients who were treated at our hospital for biopsy-proven IgA nephropathy, we performed quantitative histopathological analysis in 38 patients with mild proteinuria of less than 0.5 g/day. We related these histopathological parameters with clinical data at biopsy and also with follow-up data. The percentage of glomeruli showing global sclerosis exceeded 10% of total glomeruli in 15 of the patients (39.5%) and exceeded 20% in 9 (23.7%). Arteriosclerosis and tubulointerstitial changes significantly correlated with glomerular sclerosis, but mesangial cell proliferation did not. Among the 38 patients, the 12 with hypertension showed more severe glomerular sclerosis, tubulointerstitial changes and arteriosclerosis compared with the 26 without hypertension, but the mesangial cell proliferation was identical between the two groups. Stepwise multiple regression analysis revealed that hypertension and urinary protein excretion (UPE) were independent risk factors for arteriosclerosis. The follow-up data of a mean period of 27.6 months showed that 9 of the 38 patients (23.7%) had an increase in UPE. Hypertension, arteriosclerosis, age, and UPE at biopsy were selected as the important risk factors for an increase in UPE in the follow-up. Our results provide not only clinical but histopathological evidence that hypertension affects the prognosis of mild proteinuric nephropathy through vascular lesions.

Correlation between the resistive index by Doppler ultrasound and kidney function and histology.

BACKGROUND: Although duplex Doppler ultrasonography has been used widely, it still is unknown whether resistive index could be related directly to vascular or tubulointerstitial changes in the kidney. METHODS: Thirty-three patients who underwent renal biopsy were included in the present study. Clinical data, including sex; age; time from abnormal urinalysis result to biopsy; serum creatinine level; creatinine clearance; urinary excretion of protein, N-acetyl-beta-glucosaminidase, and urinary beta2-microglobulin; and presence of hypertension, were recorded at biopsy. Histopathologic data, including glomerular sclerosis, interstitial fibrosis/tubular atrophy, interstitial infiltration, and arteriolosclerosis, were evaluated separately by means of a quantitative or semiquantitative method. We examined whether resistive index at biopsy was related to these clinical and histopathologic parameters and, moreover, to renal outcome in patients followed up for more than 2 years. RESULTS: Age, creatinine clearance, urinary beta2-microglobulin excretion, and all histopathologic parameters showed statistically significant correlations with resistive index. However, stepwise multiple regression analysis showed that only arteriolosclerosis was chosen as an independent risk factor for increased resistive index. During the follow-up period of 57.5 +/- 15.6 months in 29 patients, 8 patients (27.6%) had progression of renal impairment, defined as an increase in serum creatinine level greater than 50%. They had a significantly increased resistive index at biopsy compared with patients without progression. CONCLUSION: We show a direct relationship between resistive index and arteriolosclerosis in damaged kidneys. Resistive index at renal biopsy may be useful as one of the prognostic markers for renal outcome.

Amyloidosis associated with chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL), the most common form of leukemia in Western countries, rarely induces glomerular disease, but membranoproliferative glomerulonephritis or immunotactoid glomerulopathy has been reported. The proliferating cells in CLL are of mature B-cell origin and produce monoclonal immunoglobulin (Ig), thus leading to various kinds of autoimmune disorders or immunotactoid glomerulopathy. Although there have been a few reported cases of amyloidosis accompanying CLL, the type of amyloid fibrils has not been demonstrated nor described in detail, particularly regarding monoclonal Ig productivity. We report a rare case of amyloidosis associated with CLL, in which we detected ?-light chain type monoclonal Ig in the sera, urine, and on the surface membrane of lymphocytes, and discuss an association between monoclonal Ig-related disease and non-Hodgkin's lymphoma.

Fractalkine and its receptor, CX3CR1, upregulation in streptozotocin-induced diabetic kidneys.

BACKGROUND: Fractalkine is induced on activated endothelial cells and promotes strong adhesion of T cells and monocytes via its receptor CX3CR1. In kidney, fractalkine expression might be induced by high shear stress and play an important role in prolonged glomerular diseases. We examined whether fractalkine and CX3CR1 upregulation are found in streptozotocin-induced diabetic kidneys. METHODS: Diabetic rats were randomized to receive an angiotensin-converting enzyme inhibitor (temocapril), aminoguanidine or no treatment. Reverse transcription-competitive polymerase chain reaction, Western blot analysis and immunohistochemistry were used. RESULTS: At 4 weeks, fractalkine and CX3CR1 mRNA expression in diabetic kidneys increased compared with that in controls. Fractalkine staining in diabetic kidneys was clearly detected, along with glomerular capillary lumen and peritubular capillaries. A few CX3CR1 positive cell infiltration in diabetic glomeruli were found. Treatment with temocapril or aminoguanidine did not affect these changes. At 8 weeks, fractalkine and CX3CR1 mRNA expression in untreated diabetic kidneys markedly increased compared with that in controls. Membrane-anchored fractalkine protein expression in untreated diabetic rats also increased. The increased expression was suppressed by the treatment with temocapril and aminoguanidine. Increased CX3CR1-positive cell infiltration in diabetic glomeruli was also inhibited by both treatments. Some CX3CR1-positive cells were ED3 positive. CONCLUSIONS: Fractalkine and CX3CR1 upregulation were demonstrated in an early stage of diabetic kidney. These upregulation, as well as urinary albumin excretion, were suppressed by treatments with temocapril and aminoguanidine for 8 weeks. These findings suggest that fractalkine expression and CX3CR1-positive cell infiltration in diabetic kidneys might play an important role for progression of diabetic nephropathy.

Galectin-3-positive cell infiltration in human diabetic nephropathy.

BACKGROUND: Galectin-3 has several functions, such as cell proliferation, regulation of apoptosis and interaction of cell adhesion, and has a high binding affinity for advanced glycation end products. In animal models with diabetic nephropathy (DMN) or acute renal failure, galectin-3 is known to be upregulated. However, galectin-3 expression has not been investigated in human kidney diseases. METHODS: Using immunohistochemistry we examined galectin-3 expression in renal biopsy specimens obtained from 37 patients with nephropathy: DMN (n = 9), IgA nephropathy (n = 9), crescentic glomerulonephritis (n = 8), membranous nephropathy (n = 6) and minimal change nephrotic syndrome (n = 5). RESULTS: In normal human kidney, galectin-3 was found in distal tubuli, but not in glomeruli. However, galectin-3-positive cell infiltration was observed in glomeruli of 12 patients. Galectin-3-positive cells, also stained with CD68, were significantly more numerous in glomeruli of DMN than in glomeruli of other nephropathies. The ratio of galectin-3-positive cells to the total number of macrophages in tubules was also significantly increased in DMN. There was a significant correlation between the number of galectin-3-positive cells in glomeruli and urinary protein excretion in all patients (r = 0.616, P<0.001). In diabetic patients, the number of galectin-3-positive cells in glomeruli closely correlated with the regression rate of renal function (r = -0.930, P<0.005). CONCLUSION: These findings suggest that galectin-3-positive cell infiltration may play an important role in the progression of DMN, and the degree of its expression may be predictive of poor prognosis of DMN.

A composite hormone response element regulates transcription of the rat GHRH receptor gene.

To further elucidate the molecular mechanisms underlying the transcriptional regulation of the GHRH receptor (GHRH-R) gene, hormonal regulation of the promoter activity of this gene was examined. An approximately 3-kb genomic fragment spanning the promoter region of the gene was sequenced and the transcription start site was determined by RT-PCR and RNase protection assay. A major start site was localized at -105 (relative to the translation initiation codon, ATG), and a pit-1 binding sequence characteristic of pituitary specific genes was found at -155 to -146. Deletion and mutation studies demonstrated this site to be functional. In the presence of dexamethasone, the GHRH-R promoter (from -2935 to -11) directed luciferase expression in MtT-S cells, a somatotropic cell line, but not in the PC12 cells that normally do not express GHRH-R. While T(3), all trans-RA, and 9cis-RA alone weakly enhanced the reporter gene expression, each of these substances was found to act as a synergistic enhancer in the presence of dexamethasone. Additional deletion and mutation analyses demonstrated a functional RA response element at -1090 to -1074. Two functional glucocorticoid response elements and a T(3) response element were found in an 80-bp 5'-flanking sequence of the pit-1 site. Interestingly, it is suggested that the 6-bp half-site AGGACA (from -209 to -204) functions as a 3'-half-site of T(3) response element as well as a 5'-half-site of one of the glucocorticoid response elements.

[Pathological analysis of renal diseases with mild proteinuria].

Proteinuria is an important predictor of renal outcome in a variety of renal diseases. Proteinuria exceeding 0.5 g/day is often considered to be a major indication of renal biopsy. In this study, we analyzed the clinical and histopathological data of 58 patients with mild proteinuria of less than or equal to 0.5 g/day. The histopathological diagnosis included 45 cases(77.6%) of mesangial proliferative glomerulonephritis, 4 cases(6.9%) of lupus nephritis, one case of membranoproliferative glomerulonephritis and only 6 cases(10.3%) of minor glomerular abnormality. The percent sclerotic glomeruli exceeded 10% in 17 cases(29.3%) and reached 71.4% in 2 cases. There were no significant differences in histopathological parameters(percent sclerotic glomeruli, tubulointerstitial change, arterio-arterio sclerotic change) between the groups with or without microhematuria. There was a positive correlation between age and percent sclerotic glomeruli. Percent sclerotic glomeruli in our cases were higher than in the healthy population reported by Kaplan et al. and the influence of glomerulonephropathy was obvious. During the follow-up period(mean 19.7 months), one patient progressed to chronic renal failure and 2 patients had increased urinary protein excretion, but the others did not. These results suggest the importance of clarifying the prognosis by renal biopsy even in cases with mild proteinuria.