Kazuomi Yamashita

Localization of Transforming Growth Factors ß1 and ß2 and Epidermal Growth Factor in IgA Nephropathy

OBJECTIVE The localization of transforming growth factor (TGF)-beta1. TGF-beta2 and epidermal growth factor (EGF) was investigated in IgA nephropathy, and was compared with the severity of histological damage (including tubulointerstitial lesions). MATERIALS AND METHODS The enzyme antibody method was used to stain paraffin-embedded sections of renal tissue from 42 patients with IgA nephropathy (19 males and 23 females). RESULTS There was a significant correlation between glomerular positivity for TGF-beta1 and TGF-beta2 and the severity of histological damage. There was also a significant correlation between positivity for TGF-beta1 and TGF-beta2 in the tubular epithelium and tubulointerstitial lesions. In contrast, there was no relationship between glomerular positivity for EGF and histological damage, although there was a significant correlation between positivity for EGF in the tubular epithelium and tubulointerstitial lesions. CONCLUSIONS These findings suggest that TGF-beta1 and TGF-beta2 may be important in the progression of IgA nephropathy, and that the distribution of EGF may also be a useful marker for the progression of renal damage, including tubulointerstitial lesions.

Role of Transforming Growth Factor-β1 in Glomerulonephritis

The role of transforming growth factor-β1 (TGF-β1) in human glomerulonephritis is still poorly understood. The relationship between expression of TGF-β1 protein or TGF-β1 mRNA and tissue damage was investigated using the enzyme–antibody and in situ hybridization method in frozen slices of renal tissue from 30 patients: 25 with glomerulonephritis (18 with immunoglobulin A nephropathy; two with focal glomerulosclerosis, one with membranous nephropathy, one with crescentic glomerulonephritis and three with lupus nephritis) and five control patients with minimal change disease. The expression of TGF-β1 mRNA was high in sclerotic and proliferative glomeruli, as well as in the tubular epithelial cells within tubulointerstitial lesions. There was significant correlation between the severity of tissue damage in immunoglobulin A nephropathy and the presence of TGF-β1protein and TGF-β1 mRNA. These findings suggest that TGF-β1 is involved in glomerulosclerosis and the development of tubulointerstitial lesions, indicating its potential importance in the progression and aggravation of immunoglobulin A nephropathy.

Localization of Hepatocyte Growth Factor and Tubulointerstitial Lesions in IgA Nephropathy

To investigate the relationship between localization of hepatocyte growth factor (HGF) and tubulointerstitial lesions (TILs) in the cortical area of renal biopsy specimens, a clinicopathological study was performed in 35 patients with IgA nephropathy. HGF was detected by an enzyme-antibody method and TILs were assessed semiquantitatively by light microscopy. HGF was observed mainly on epithelial cells in the tubules, but not in the glomeruli. Fourteen patients had biopsies that were positive for HGF. There was a correlation between HGF positivity and histological damage, the TIL grade, and several clinical parameters determined at biopsy. Thus, HGF is related to TILs in IgA nephropathy, and may be a factor in the exacerbation of this disease.

Nicardipine Hydrochloride Suppresses DNA Synthesis in Human Mesangial Cells Stimulated with Recombinant Human (rh) Platelet-Derived Growth Factor AA, rh lnterleukin-1 α, or rh Tumor Necrosis Factor-α

In order to define the role of cytokines in mesangial cell pathophysiology, we measured the mitogenic activity of recombinant human platelet-derived growth factor AA (rhPDGF-AA), rh interleukin-1 alpha (rhIL-1 alpha) and rh tumor necrosis factor-alpha (rhTNF-alpha) in cultured human mesangial cells, and investigated the effect of the calcium channel blocker nicardipine hydrochloride on their cell mitogenic activity. DNA synthesis in mesangial cells, stimulated by rhPDGF-AA, rhIL-1 alpha or rhTNF-alpha, was measured using [3H]TdR up take and similar investigations, with nicardipine hydrochloride added to the above, were conducted. The results showed DNA synthesis in cultured human mesangial cells were stimulated by rhPDGF-AA, rhIL-1 alpha and rhTNF-alpha, and this effect was reduced by the addition of nicardipine hydrochloride. Since rhPDGF-AA, rhIL-1 alpha and rhTNF-alpha are released by the inflammatory cells which infiltrate glomeruli, these cytokines may be involved in the mechanisms of mesangial cell proliferation observed in immune-mediated mesangial proliferative glomerulonephritis. Nicardipine hydrochloride reduced DNA synthesis in cultured human mesangial cells in response to these cytokines, suggesting possible application in medical therapy for immune-mediated mesangial proliferative glomerulonephritis.

Oral iron supplementation with sodium ferrous citrate reduces the serum intact and c-terminal FGF23 levels of maintenance hemodialysis patients

Iron deficiency stimulates fibroblast growth factor 23 (FGF23) transcription. This study aimed to determine whether oral ferrous iron (Fe2+) reduces the serum FGF23 levels of iron‐deficient maintenance haemodialysis (MHD) patients in the same way as oral ferric iron (Fe3+)

Tissue factor and tissue factor pathway inhibitor in hemodialysis patients.

Tissue factor and tissue factor pathway inhibitor are important in extrinsic coagulation. We investigated their clinical significance in hemodialysis patients. We took blood samples, prior to initiation of routine hemodialysis, from 73 patients on hemodialysis (35 men and 38 women aged 56.1 ± 11.7 years on dialysis for 82.1 ± 61.0 months), and determined tissue factor and tissue factor pathway inhibitor levels by ELISA. In the patients the tissue factor level was 704.5 ± 141.6 pg/ml and the tissue factor pathway inhibitor level was 44.5 ± 23.3 ng/ml; both values were significantly higher than in normal controls (192.7 ± 36.6 pg/ml and 18.6 ± 5.7 ng/ml, respectively). In patients with shunt obstruction, tissue factor pathway inhibitor levels were significantly higher than in those without it. Therefore, the tissue factor pathway inhibitor level may be a marker of shunt obstruction.

Factors influencing arteriovenous fistula dysfunction in Japanese patients on chronic hemodialysis.

Arteriovenous fistula dysfunction is a constant problem in chronic hemodialysis patients. We investigated the factors influencing fistula dysfunction in 184 patients on chronic hemodialysis. Stepwise regression analysis and Cox proportional hazards model were used to assess the relationship between fistula dysfunction and age, sex, duration of hemodialysis, diabetes mellitus, hematocrit, serum creatinine, blood urea nitrogen, Kt/V, prothrombin time, blood pressure, anticoagulant therapy, dose of erythropoietin, calcium channel blocker therapy, and angiotensin-converting enzyme inhibitor therapy. Fistula dysfunction showed a significant relationship with a low systolic blood pressure, a low hematocrit, the presence of diabetes mellitus, and angiotensin-converting enzyme inhibitor therapy. These results suggested that treatment with angiotensin-converting enzyme inhibitors may help to prevent fistula dysfunction.

Hepatocyte Growth Factor Localization in Primary Glomerulonephritis and Drug-Induced Interstitial Nephritis

Noriaki Yorioka, MD, 2nd Department of Internal Medicine, Hiroshima University School of Medicine, 1-2-3 Kasumi Minami-ku, Hiroshima City 734 (Japan) Table 1. Correlation between the distribution of HGF on tubule epithelial cells and primary glomerulonephritis, drug-induced interstitial nephritis and control tissue. Dear Sir, Hepatocyte growth factor (HGF) was initially identified as a mitogen for hepatocytes by Nakamura et al. [1] in 1984. Recently, HGF has been shown to be a mitogen for a variety of cell types, including renal tubular cells [2, 3]. Nagaike et al. [4] examined changes in HGF mRNA expression, HGF activity and HGF receptor in the rat kidney following unilateral nephrectomy or treatment with carbon tetrachloride, and suggested that HGF might function as a renotropic factor during renal regeneration after injury. In this study, we present the immunohis-tochemical localization of HGF in patients with primary glomerulonephritis and drug-induced interstitial nephritis. We examined 37 patients (18 males and 19 females; age: 15-74 years, mean ± SD; 40.9 ± 17.6) who underwent renal biopsy prior to treatment in the Second Department of Internal Medicine, Hiroshima University School of Medicine, Hiroshima, Japan. These patients were diagnosed as follows: primary glomerulonephritis, 25 patients (IgA nephropathy, 15 patients; membranous glomerulonephritis, 6 patients; focal glomer-ulosclerosis, 4 patients); druginduced interstitial nephritis, 9 patients (NSAIDs, 4 patients; anticancer agents, 2 patients; antibiotics, 2 patients; interferon-γ, 1 patient), and minimal changes, for control tissue, 3 patients. Kidney tissue fixed in formalin and embedded in paraffin was used to localize HGF. The sections were deparaffmized using xylene and alcohol, and the antigen was unmasked in 0.01% trypsin diluted with 0.06 M PBS, pH 7.2, for 30 min at 37 °C. The primary antibody (monoclonal anti-HGF antibody, Otsuka Pharmaceuticals, Japan) was applied overnight at 4 o C, followed by incubation with the secondary antibody for 30 min at room temperature. Immuno-products were visualized by applying DAB. The relationship between the presence of HGF and the histological stages of IgA nephropathy [5] was evaluated.

Transforming Growth Factor-β1 May Be Involved in Shunt Obstruction in Patients on Chronic Hemodialysis

Obstructed shunt vessels were studied immunohistochemically to clarify the mechanism of shunt obstruction in hemodialysis patients. The subjects were 12 hemodialysis patients with shunt obstruction, and 8 patients newly started on hemodialysis were used as the controls. Cryosections of shunt tissue were prepared and stained for thrombomodulin as well as transforming growth factor-β1 using the enzyme antibody method. In the obstructed shunt group, the intima was significantly thicker than in the control group. In addition, staining of the intima for thrombomodulin was decreased in the obstructed shunt group when compared with the controls. Staining for transforming growth factor-β1 was related to intimal thickening and cell proliferation. These results indicate that release of thrombomodulin occurs with vascular endothelial cell damage and that transforming growth factor-β1 may be involved in intimal hypertrophic change and shunt obstruction.

Hemoglobin Maintenance and Dosing Strategies Using Intravenous Continuous Erythropoietin Receptor Activator in Japanese Hemodialysis Patients

Methoxy polyethylene glycol‐epoetin beta, a continuous erythropoietin receptor activator (CERA), is reported to be effective in managing renal anemia but there is little data about CERA in Japan. This study aimed to ascertain the effects of CERA in Japanese hemodialysis patients and the appropriate starting dose of CERA when switching from other erythropoiesis‐stimulating agents. We switched 61 stable hemodialysis patients to 4‐weekly intravenous CERA, from either epoetin beta (rHuEPO) or darbepoetin alpha (DA). When determining the initial dose of CERA, we used guidelines recommended by the Japanese supplier for switching from rHuEPO, but for DA we based the CERA dose on European reports, because no Japanese guidelines exist. Fifty‐two patients completed the 28‐week study. Hemoglobin was maintained within the target range (10.0–12.0 g/dL). The required CERA dose decreased over the 28 weeks. The hemoglobin level and CERA dose stabilized faster when switching from DA. CERA showed similar efficacy in diabetic and non‐diabetic patients. The effect of CERA is similar regardless of whether patients switch from low‐ or high‐dose erythropoiesis‐stimulating agents. In conclusion, CERA is effective for Japanese hemodialysis patients at a lower dose than expected.