[Show abstract][Hide abstract] ABSTRACT: In glomerular hypertension, mesangial cells (MC) are subjected to at least two physical forces: a high pressure and mechanical stretch. In 5/6 nephrectomized rat, a model of progressive glomerular sclerosis associated with glomerular hypertension, monocyte chemoattractant protein-1 (MCP-1) is expressed in glomeruli, suggesting the possible role of MCP-1 in the pathogenesis of glomerular sclerosis; however, whether pressure directly affects MCP-1 expression remains undetermined. Here we examined the effects of pressure on MCP-1 expression in cultured rat MC and the signal transduction pathways that lead to MCP-1 expression.
Pressure was applied to MC by instilling compressed helium gas into sealed plates. MCP-1 mRNA and protein levels in MC were detected by reverse transcription-polymerase chain reaction (RT-PCR) or Northern blotting and ELISA or Western blotting, respectively. Mitogen-activated protein (MAP) kinase activity was measured with the catalytic activity of p42/p44 MAP kinase and anti-phospho p42/p44 MAP kinase antibody. A transient transfection assay that specifically modulates MAP kinase kinase (MEK) activity was carried out.
MCs subjected to external pressure expressed MCP-1 mRNA rapidly and transiently with the peak level noted at 10 minutes and 80 mm Hg pressure. MCP-1 protein levels in cell lysates and culture medium also significantly increased after pressure loading. Pressure rapidly increased the phosphorylation level and activity of p42/p44 MAP kinase. Treatment of MC with a MAP kinase kinase (MEK) inhibitor, PD98059, suppressed levels of both pressure-induced MAP kinase activities and MCP-1 mRNA expression. The constitutively activated type of MEK1 induced MCP-1 expression (13.7-fold) even in non-pressurized MC.
Our results indicate that pressure per se can induce MCP-1 via activation of MAP kinase pathway, suggesting that glomerular hypertension might be involved in the progression of renal diseases through the expression of MCP-1 in MC.
Kidney International 12/2001; 60(5):1705-15. · 8.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Plasma concentrations of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and cyclic guanosine monophosphate (cGMP) are suitable markers of 'dry body weight' (DW) in hemodialysis (HD) patients. However, it is still unknown whether these markers can be applied to patients with renal failure and coronary artery disease (CAD). We examined the reliability of these peptides as volume markers in HD patients with CAD. We also assessed the relationship between natriuretic peptides and indices of left ventricular (LV) function.
Plasma concentrations of ANP, BNP and cGMP were determined before and after HD in patients with CAD (group 1, n = 19, mean age 63 +/- 12 years) and were compared with those of patients without cardiac disease (group 2, n = 20, age 61 +/- 15 years). Using data obtained by cardiac catheterization, we examined the relationship between natriuretic peptides and indices of LV function in HD patients with CAD.
Baseline ANP (244 +/- 205 pg/ml), BNP (713 +/- 928 pg/ml) and cGMP (29.6 +/- 21.6 pmol/ml) were significantly higher in group 1 than in 11 healthy volunteers (18.6 +/- 9.9 pg/ml, 7.7 +/- 7.6 pg/ml, cGMP 8.9 +/- 4.9 pmol/ml, respectively). HD significantly reduced plasma ANP (87 +/- 75 pg/ml) and BNP (477 +/- 702 pg/ml) although they were still above normal control. HD reduced plasma cGMP (7.2 +/- 4.5 pmol/ml) to normal values, suggesting the elimination of cGMP across the dialyzers. Baseline levels of ANP, BNP and cGMP in group 2 were less than those of group 1 but higher than the control. HD reduced natriuretic peptides in group 2 to levels lower than those in post-HD group 1. After HD, there was no significant correlation between reductions in body weight and changes in ANP or BNP. Baseline ANP and BNP levels closely correlated with pulmonary artery pressure, pulmonary artery wedge pressure, left ventricular end-diastolic pressure and left ventricular ejection fraction. A significant correlation was observed between BNP levels and the severity of CAD.
ANP, BNP and cGMP seem to be a useful markers for fluid overload but not for DW in HD patients with CAD. Plasma ANP and BNP might be useful markers for left ventricular function.
American Journal of Nephrology 01/2001; 21(2):112-9. · 2.62 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Profilin is known to bind to actin monomers (to regulate actin polymerization) and to phosphatidylinositol-4,5-bisphosphate (to inhibit hydrolysis by unphosphorylated phospholipase C-gammal). It was recently reported that profilin is overexpressed in glomerular mesangial cells (MC) of rats with anti-Thy-1.1-induced glomerulonephritis and is accumulated in the extracellular space around MC. In this study, the biologic activities of extracellular profilin were examined. Scatchard analysis indicated the existence of a single class of cell surface binding sites, with similar equilibrium dissociation constants for purified splenic profilin and recombinant profilin, in cultured rat MC. Profilin increased [(3)H]thymidine incorporation in a dose-dependent manner and produced additive effects on platelet-derived growth factor-induced [(3)H]thymidine incorporation. Profilin increased AP-1 DNA-binding activity in a concentration-dependent (ED(50) = 30 nM) and time-dependent manner after transient c-jun gene expression, as measured using gel-shift assays and competitive reverse transcription-PCR. Pretreatment of profilin with an anti-profilin inhibitory antibody suppressed profilin-induced AP-1 activation and [(3)H]thymidine incorporation. Furthermore, profilin induced rapid transient activation of protein kinase C, and staurosporine and H-7 reduced the profilin-induced activation of AP-1, suggesting protein kinase C-dependent activation of AP-1. These findings indicate that profilin in the extracellular space can bind to cell surface receptors of MC and act as an inducer of signal transduction. These results suggest that extracellular profilin may be involved in the progression of glomerular diseases, by affecting cell growth.
Journal of the American Society of Nephrology 10/2000; 11(9):1620-30. · 8.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Profilin binds to actin monomer to regulate actin polymerization, and to phosphatidylinositol 4,5-bisphosphate to inhibit hydrolysis by phospholipase Cgamma1. This study investigated the expression of profilin in rat anti-Thy-1.1 mesangial proliferative glomerulonephritis (GN) and examined the effect of growth factors on its expression in cultured rat mesangial cells. Profilin mRNA was constitutively expressed in isolated glomeruli of untreated rats. However, in glomeruli of anti-Thy-1.1 GN rats, its expression was upregulated beginning on day 1, reaching a peak level on day 4 (3.9-fold versus control glomeruli), and decreased on day 14, as determined by competitive reverse transcription-PCR. Increased expression of profilin protein was confirmed using immunoblotting and immunohistochemistry. Immunoelectron microscopy revealed the presence of profilin in plasma membrane and the rough endoplasmic reticulum of mesangial cells, indicating that profilin was produced in mesangial cells. In cultured rat mesangial cells, expression of profilin mRNA and protein was upregulated by basic fibroblast growth factor but not by platelet-derived growth factor or transforming growth factor-beta. Suppression of profilin expression using an antisense oligonucleotide against profilin inhibited [3H]thymidine uptake. These findings indicated the involvement of profilin in anti-Thy-1.1 GN and suggest that the upregulation of profilin might be involved in the progression of anti-Thy-1.1 GN possibly by affecting cell growth.
Journal of the American Society of Nephrology 04/2000; 11(3):423-33. · 8.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Inbred polydipsic mice (STR/N strain) have primary polydipsia. The previous studies found abnormalities in the central nervous system (CNS), especially in the hypothalamus and circumventricular organ. As a part of pursuing to find the cause of the polydipsia, we investigated immunological characteristics of STR/N mice, using the ICR strain of mice as control. Their thymic subset cells showed that CD4+CD8+ double positive cells were increased, CD4+ single positive cells were decreased and CD5 expression was deficient, compared to ICR mice. T cell proliferative response and interleukin (IL)-2 production caused by IL-1beta stimulation were reduced in STR/N mice than those in the ICR mice. In in vivo studies the degree of thymic atrophy and the increases in serum level of ACTH and corticosterone induced by intraperitoneal IL-1beta injection were much less in STR/N mice than those in controls. Furthermore, adipsic response also induced by IL-1beta injection was greatly reduced compared to their control mice. All these results suggest that the responsiveness to IL-1 is impaired both in the immune system and the CNS of STR/N mice.
Life Sciences 02/2000; 66(16):1461-70. · 2.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In glomerular hypertension, mesangial cells (MC) are subjected to at least two physical forces: mechanical stretch and high transmural pressure. Increased transmural pressure, as well as mechanical stretch, promotes MC proliferation, which may enhance glomerulosclerosis. The exact mechanism of this effect is not fully understood. We examined the effects of transmural pressure alone on cell proliferation and DNA synthesis and investigated the role of platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF), candidates for mediation of glomerular diseases, in the pressure-induced events. Pressure was applied to cultured MC placed in a sealed chamber using compressed helium gas. Application of pressure resulted in a time-dependent ( approximately 2 h) and pressure level-dependent (approximately 80 mmHg) increase in cell number (1.4-fold) and [(3)H]thymidine incorporation (2.7-fold). Pressure-induced DNA synthesis was significantly suppressed by inhibitors of phospholipase C (2-nitro-4-carboxyphenyl-N, N-diphenylcarbamate), protein kinase C [1-(5-isoquinolinylsulfonyl)-2-methylpiperazine and chelerythrine], or tyrosine kinases (genistein). Pressure caused a rapid but transient formation of inositol 1,4,5-trisphosphate, which was blocked by the phospholipase C inhibitor. Pressure also promoted a rapid increase in tyrosine kinase activity. Pressure increased mRNA levels of PDGF-B, with a peak at 6 h, but not those of PDGF-A or bFGF. Pressure-induced DNA synthesis was partially inhibited by a neutralizing anti-PDGF antibody but not by an antibody against bFGF or nonimmune IgG. Our results indicated that pressure by itself increases DNA synthesis and proliferation of cultured rat MC possibly through activation of protein kinase C and tyrosine kinases, and PDGF-B could be partially involved in these pathways.
The American journal of physiology 08/1999; 277(1 Pt 2):F105-12. · 3.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adrenomedullin (AM), a hypotensive peptide isolated from human pheochromocytoma, inhibits the proliferation of mesangial cells (MC) induced by mitogens such as platelet-derived growth factor. Quite recently, we have demonstrated that transmural pressure applied to cultured MC increased DNA synthesis and cell proliferation through protein kinase C and tyrosine kinase pathways. However, the modulatory effect of AM on pressure-induced cell proliferation is as yet unknown. In the present study, we examined the effect of AM on transmural pressure-induced DNA synthesis in cultured rat MC. Pressure was applied to cells placed in a sealed chamber using compressed helium. Application of pressure resulted in an increase in [(3)H]thymidine incorporation (approximately 2.0-fold). AM clearly inhibited pressure-induced DNA synthesis in a concentration-dependent manner. This inhibition was paralleled by an increase in cellular cAMP levels evoked by AM. Forskolin and dibutyryl cAMP mimicked the inhibitory effect of AM. The protein kinase A inhibitor H-89 significantly attenuated the effect of AM. Human AM(22-52)-NH(2), a putative AM receptor antagonist, reversed the inhibitory effects of AM more potently than did human CGRP(8-37), a calcitonin gene related peptide receptor antagonist. Our results suggest that AM, by acting mainly on AM-sensitive receptors, inhibits pressure-induced DNA synthesis in cultured rat MC through activation of protein kinase A. AM may play a protective role against MC proliferation in certain pathological conditions.
[Show abstract][Hide abstract] ABSTRACT: We have experienced a case of myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA)-related glomerulonephritis induced by propylthiouracil (PTU). A 45-year-old female had been treated with PTU for 4 years after the diagnosis of hyperthyroidism. She was referred to out hospital because of abrupt macroscopic hematuria and moderate proteinuria after several days of upper respiratory tract infection. On admission, her laboratory findings showed deterioration of renal function. Renal biopsy revealed crescentic glomerulonephritis without deposition of immune complexes. Her serology was found to be MPO-ANCA-positive and cytoplasmic-ANCA-negative. Based of these findings, we diagnosed idiopathic crescentic glomerulonephritis. Following the initiation of steroid pulse therapy, her urinary protein excretion and renal function gradually improved in parallel with a decrease in the MPO-ANCA titer. Although steroid therapy effectively responded to their renal function without the withdrawal of PTU, it seems that PTU may be closely associated with the development of (MPO-ANCA)-related glomerulonephritis in this case. Therefore, hyperthyroidism patients treated with PTU should be paced under vigilant observation by monitoring their urinalysis and serum creatinine level.
[Show abstract][Hide abstract] ABSTRACT: Systemic lupus erythematosus (SLE) patients, especially those with antiphospholipid antibodies, have a high incidence of arterial and venous thrombotic manifestations. However, renovascular hypertension (RVH) has been rarely reported in these patients. We describe here a 49-year-old female with antiphospholipid antibodies, complicated with RVH and presenting with sudden onset of severe hypertension, headache and nausea. She had experienced phlebitis and arterial thrombosis of the right leg. At the age of 38 years, she was diagnosed as SLE and steroid therapy was started, but she had poor drug compliance and irregularly visited our clinic. On admission, hypertension was recognized and abdominal bruit was audible on physical examination. Serological findings were compatible with SLE. She was also found to have IgG anti-cardiolipin antibody and lupus anticoagulant. Peripheral plasma renin activity (PRA) was elevated, and captopril test showed hyper-response of PRA with lowering of blood pressure. Renal echography and scintigram showed a small and poorly perfused right kidney. Selective angiography demonstrated a severe stenosis of the right renal artery at origin. A stenosis at the origin of both the superior mesenteric artery (SMA) and celiac trunk was also detected. Percutaneous transluminal angioplasty was performed, achieving successful dilatation of the right renal artery and SMA, whereas the attempt to insert the catheter into the celiac trunk was unsuccessful. After this procedure, abdominal bruit has not been audible. Following the initiation of steroid pulse therapy combined with heparin and dipyridamole, her blood pressure was gradually depressed and the test for lupus anticoagulant became negative. Therefore, RVH of this patient is thought to be associated with antiphospholipid antibodies.
[Show abstract][Hide abstract] ABSTRACT: Profilin is a cytoplasmic protein that binds to actin monomer and regulates actin polymerization. In a number of experimental and human glomerular diseases, the mesangial cell expresses alpha-smooth muscle actin and undergoes a phenotypic change to myofibroblast. We used a rat model of mesangial proliferative nephritis induced with antibody to the Thy 1 antigen present on mesangial cells to investigate whether profilin is upregulated. We amplified and sequenced rat profilin cDNA by the reverse-transcribed-polymerase chain reaction (RT-PCR). The nucleotide and amino acid sequences were highly conserved across the mammalian profilins. We raised affinity purified antibody to rat profilin in rabbits immunized with a synthetic profilin peptide (EFTMDLRTKS). At 7 days after disease induction, enhanced expression in both profilin mRNA and protein was demonstrated in the isolated glomeruli by RT-PCR and Western blot analysis. These results suggest that profilin may be involved in the pathogenesis of glomerulonephritis by reorganizing actin cytoskeleton.
Biochemical and Biophysical Research Communications 06/1996; 222(3):683-7. · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adjuvant arthritis (AA) is an experimental model for rheumatoid arthritis, and is induced most easily in inbred Lewis rats by an intradermal injection of heat-killed Mycobacterium tuberculosis (MT) in incomplete Freund's adjuvant. Susceptivity to the arthritis in Lewis rats is thought to be related to a defect in their responses of the hypothalamo-pituitary-adrenal (HPA) axis to the disease. Because the use of an inbred strain is necessary for our immunological studies, we examined in Lewis rats changes in behavior, the HPA axis, and sympathetic nerve activities during development of the adjuvant arthritis. Following intradermal injections of heat-killed MT in adjuvant, the arthritis began to develop on day 12, reaching its maximum severity on day 21, and remained at the level for over a month. The body temperature rose from day 0 to 5 (the primary phase--before the onset of the arthritis). It then fell to normal temperature, and again rose from day 10 to 21 (the secondary phase--with fully developed arthritis). The behavioral (physical activity, food, and water intake) and hormonal parameters [plasma adrenocorticotropic hormone (ACTH) and corticosterone levels] also changed in two phases, similar to those observed in the temperature responses. No change in plasma vasopressin level was observed. Sympathetic nerve activities, assessed by changes in plasma noradrenalin levels, increased more in the primary than in the secondary phase. The possible causes for the biphasic changes associated with development of arthritis are discussed.
Brain Research Bulletin 02/1996; 39(1):33-7. · 2.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We examined kidney biopsy specimens obtained from 40 adult patients with isolated hematuria to determine the renal pathology and the incidence of thin glomerular basement membrane nephropathy (TGBMN). Light microscopy showed minor glomerular abnormalities in 26 patients (65%), focal and segmental lesions in 3 patients (8%), and mild diffuse proliferative glomerulonephritis in 11 patients (28%). Immunofluorescence microscopy showed IgA nephropathy (IgA-N) in 16 patients (40%), in whom no progressive lesions were identified. We measured the glomerular basement membrane (GBM) thickness using electron microscopy, and TGBMN was identified in 4 patients (10%). Our results suggest that IgA is a major pathological finding in adult patients with isolated hematuria. GBM thinning does not appear to be a major cause of glomerular hematuria.
American Journal of Nephrology 02/1996; 16(5):412-6. · 2.62 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Effects of intracerebroventricular (i.c.v.) administration of endothelin-3 (ET-3) on renal sympathetic nerve activity (RSNA) and renal blood flow (RBF), arterial blood pressure and heart rate were examined in conscious rats. Administration of ET-3 (1-50 pmol) through a chronically implanted cannula evoked an increase in arterial blood pressure and decreases in heart rate and RSNA, whereas RBF measured by Doppler flow probes did not change. Maximum changes in these responses occurred 10-15 min after i.c.v. administration of ET-3 and the responses returned to the control level after approximately 60 min. In sinoaortic denervated (SAD) rats, the decrease in RSNA induced by i.c.v. ET-3 was attenuated but still significantly persistent. During the experiments, we found that the injection of ET-3 (50-100 pmol) induced a barrel rotation, with an onset latency of 10-15 min. In those cases, prominent increases in arterial blood pressure and RSNA were observed, and these lasted for more than 60 min. The result shows that ET-3 can have centrally mediated effects on autonomic nerve activity as well as on cardiovascular function.
Journal of the Autonomic Nervous System 11/1994; 49(2):105-13.