Kenichi Shirato

C-Type Natriuretic Peptide Inhibits Proliferation and Monocyte Chemoattractant Protein-1 Secretion in Cultured Human Mesangial Cells

Background: Mesangial cell proliferation and matrix accumulation are hallmarks of various progressive glomerular diseases. We examined whether C-type natriuretic peptide (CNP) that is known to regulate the proliferation of vascular smooth muscle cells could modulate these pathological processes using human glomerular mesangial cells (GMCs) in culture. Methods: Proliferation of GMCs cultured with different concentrations of CNP-22 for 48 h was determined by a colorimetric assay using a tetrazorium salt. Monocyte chemoattractant protein-1 (MCP-1) and type IV collagen secretion into the culture media by GMCs in the presence or absence of CNP-22 were evaluated by ELISA. Expression of mRNA for natriuretic peptide receptor B (NPR-B), a specific receptor for CNP, was examined by reverse transcription polymerase chain reaction (RT-PCR). Results: CNP-22 (1–10 µM) inhibited serum-induced GMC growth in a dose-dependent manner. The amount of MCP-1 in the culture supernatant was increased approximately 2.4-fold by 5 µg/ml of lipopolysaccharide. This increase was inhibited by CNP-22 at 0.1–1 µM in a dose-dependent fashion. CNP-22 (10 µM) inhibited GMC type IV collagen secretion stimulated by 20 ng/ml of platelet-derived growth factor. Expression of NPR-B mRNA was confirmed in GMCs by RT-PCR. Conclusions: CNP suppresses GMC proliferation and MCP-1 and type IV collagen secretion by GMCs. It may have a therapeutic potential against human proliferative glomerular diseases, especially those with the involvement of monocytes.

Nephrotic syndrome associated with interferon-β-1b therapy for multiple sclerosis

A 43-year-old woman with multiple sclerosis (MS) had nephrotic syndrome 21 months after starting treatment with interferon (IFN)-β-1b (subcutaneous administration). She had taken no drug except for the IFN-β-1b. Because nephrotic syndrome may be induced by IFN therapy, the IFN was stopped. Percutaneous renal biopsy revealed that she had minimal change nephrotic syndrome. As nephrotic-range proteinuria, hypoalbuminemia, and general edema were worsening even 2 weeks after cessation of the drug, oral corticosteroid therapy (prednisolone 40 mg/day) was started. The nephrotic syndrome was treated successfully with prednisolone. The dosage of prednisolone was tapered, without a relapse, and then the corticosteroid therapy was stopped. IFN-β-1b therapy was then resumed, and the patient is in remission for both nephrotic syndrome and MS. Though proteinuria and nephrotic syndrome is a rare adverse effect of IFN-β-1b therapy, physicians treating MS patients with this agent should pay careful attention to new clinical symptoms and laboratory findings.

A case of sjögren's syndrome associated with sweet's syndrome

SummaryWe report a case of Sjögrens syndrome whose clinical course had been indolent until the patient presented with Sweets syndrome (acute febrile neutrophilic dermatosis). This patient showed renal failure and renal tubular acidosis. Sweets syndrome resolved within 3 weeks without corticosteroid therapy. Renal biopsy findings were consistent with interstitial nephritis. His renal manifestations responded to corticosteroid therapy and the renal function remained stable during 6 years follow-up without recurrence of Sweets syndrome. Although close association of both syndromes is already known, in our case Sjögrens syndrome may have been exacerbated by occurrence of Sweets syndrome.

Tissue factor pathway inhibitor production by human proximal tubular epithelial cells in culture

Fibrin deposition in the peritubular capillaries and along the tubular basement membrane is commonly observed in several renal diseases and suggests the involvement of blood coagulation in tubulointerstitial damage. It has been demonstrated that tissue factor (TF) is present in tubular epithelial cells of animal models of nephritis. Tissue factor pathway inhibitor (TFPI) regulates the extrinsic pathway of blood coagulation through its ability to inhibit TF activity and it is now thought to be produced mainly by the vascular endothelial cells. We examined whether human proximal tubular epithelial cells (PTEC) could produce TFPI and attempted to clarify the regulatory factors affecting TFPI production. Cultured human PTEC were used. The procoagulant activity (PCA) in PTEC lysate was quantified by measurement of the one-stage recalcification time. TFPI in the cell supernatants was measured by ELISA. The mRNA of TF and TFPI in PTEC was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR). PCA which is compatible with TF activity was present in the PTEC lysate. TF mRNA and TFPI mRNA were detected in PTEC. The amount of TFPI increased over time in the cell supernatants. Immnoblot analysis revealed 40 kD protein of TFPI, and TFPI antigen was demonstrated in PTEC by immunofluorescence. The concentration of TFPI was significantly increased following incubation with thrombin and heparin in a dose- and time-dependent manner, although the amount of TFPI mRNA was not changed. Our study showed that TFPI is produced in cultured PTEC and added one more cell type that produced TFPI other than endothelial cells. Thrombin and heparin stimulated TFPI secretion from PTEC. TFPI of PTEC may act against generation of thrombin and tubular fibrin formation induced by tissue factor activation. The augmentation of TFPI secretion by heparin may play an important role in the modulation of anticoagulant properties of PTEC.

Paroxysmal nocturnal hemoglobinuria in systemic lupus erythematosus: a case report

IntroductionParoxysmal nocturnal hemoglobinuria is an acquired disorder of hemopoiesis and is characterized by recurrent episodes of intravascular hemolysis due to an increased sensitivity to complement-mediated hemolysis. Systemic lupus erythematosus with paroxysmal nocturnal hemoglobinuria is very rare. We report a case of paroxysmal nocturnal hemoglobinuria that developed in a patient with systemic lupus erythematosus and lupus nephritis.Case presentationA 29-year-old Mongolian woman had systemic lupus erythematosus, which manifested only as skin lesions when she was 12 years old. She had leg edema and proteinuria when she was 23 years old, and a renal biopsy revealed lupus nephritis (World Health Organization type IV). She had been treated with steroids and immunosuppressant therapy. At 29, she had headaches, nausea, general fatigue, and severe pancytopenia and was admitted to our hospital. A laboratory evaluation showed hemolytic anemia. Further examination showed a neutrophil alkaline phosphatase score of 46 points, a CD55 value of 18%, and a CD59 value of 78.6%. The results of Ham test and sugar water tests were positive. The constellation of symptoms throughout the clinical course and the laboratory findings suggested paroxysmal nocturnal hemoglobinuria.ConclusionsTo the best of our knowledge, systemic lupus erythematosus with paroxysmal nocturnal hemoglobinuria is very rare. Clinicians should be aware of the association between autoimmune and hematological diseases.

Acute Tubulointerstitial Nephritis with Antineutrophil Cytoplasmic Antibody

We present a case of acute tubulointerstitial nephritis that developed in a 77-year-old woman who had a high titer of myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody (ANCA). The constellation of clinical, laboratory and histopathologic findings suggested idiopathic acute tubulointerstitial nephritis. Of interest, no drugs were found to be responsible. Therefore, MPO-ANCA itself might play a causative role in the development of acute tubulointerstitial nephritis.

Platelet-derived growth factor stimulates matrix metalloproteinase-2 secretion in cultured human mesangial cells

AbstractBackground. Platelet-derived growth factor (PDGF) is an important mediator of mesangial proliferative glomerulonephritis. Little is known about the role of PDGF in the regulation of intraglomerular extracellular matrix turnover. Method. Effects of PDGF on the secretion of matrix metalloproteinase-2 (MMP-2), tissue inhibitor of MMP-2 (TIMP-2), and type IV collagen by cultured human mesangial cells (HMCs) were examined in the present study. Secretion of MMP-2, TIMP-2, and type IV collagen by HMCs was quantified with an enzyme immunoassay. Collagenase activity of HMCs was evaluated by gelatin zymography. Results. Recombinant human PDGF (10–20 ng/ml) stimulated MMP-2 secretion by HMCs in a dose-dependent fashion. PDGF (20 ng/ml) increased TIMP-2 secretion by HMCs to a lesser extent. Enhanced activity of 72-kDa collagenase derived from HMCs incubated with PDGF was demonstrated by zymography. Although PDGF alone did not affect type IV collagen secretion by HMCs, PDGF increased type IV collagen secretion in the presence of TIMP. Conclusions. PDGF may contribute to intraglomerular matrix turnover by up-regulating secretion and activation of MMP-2 by HMCs.

Angiotensin II further enhances type IV collagen production stimulated by platelet-derived growth factor and fibroblast growth factor-2 in cultured human mesangial cells

SUMMARY: Angiotensin II (Ang II) is considered to play a role in the development of glomerulosclerosis, which is characterized by excessive accumulation of mesangial matrix after mesangial cell proliferation. We have reported that platelet‐derived growth factor (PDGF) and fibroblast growth factor‐2 (FGF‐2) stimulate type IV collagen production by cultured human mesangial cells (HMC). Although Ang II is well known to have a mitogenic effect in various kinds of cells, its role in the production of extracellular matrix is still undetermined. This study was designed to examine the effect of Ang II and its interaction with PDGF and FGF‐2 in type IV collagen production by HMC. Cultured HMC were incubated with Ang II with or without PDGF or FGF‐2 for 72 h and type IV collagen, fibronectin and laminin in the cell supernatants were measured. Ang II (10−6–10−8) itself did not change the production of type IV collagen, fibronectin, laminin and transforming growth factor‐β. PDGF and FGF‐2 enhanced type IV production, although they did not stimulate the production of fibronectin and laminin. Ang II further increased the stimulating effect of PDGF and FGF‐2 in type IV collagen production in a dose‐dependent manner. This effect of Ang II was completely blocked by Ang II type I receptor antagonist (Losartan). These data imply that Ang II is a potent stimulator of type IV collagen production by HMC in the presence of growth factors.

Interleukin 6 as a marker of mesangial cell proliferative activity

AbstractBackground. The role of Interleukin 6 (IL-6) in the pathogenesis of mesangial proliferative glomerulonephritis has been controversial. To test the hypothesis that glomerular mesangial cell (GMC)-derived IL-6 may not be a mitogen for GMCs, but, rather, a factor that reflects GMC proliferative activity, we investigated how the culture condition; namely, cell confluency, affected IL-6 production in human cultured GMCs. Methods. IL-6 in the culture supernatant was measured by enzyme-linked immunoassay (ELISA). The expression of IL-6, IL-6 receptor (IL-6R), and proliferating cell nuclear antigen (PCNA) mRNA in GMCs was examined by reverse transcriptase polymerase chain reaction (RT-PCR). The effects of human recombinant IL-6 (rIL-6) on the proliferation of GMCs and an IL-6 dependent cell line, B9 cells, were evaluated by a colorimetric assay. Results. The IL-6 ELISA study revealed that subconfluent GMCs secreted more IL-6 than confluent GMCs (12.9 ± 2.9 pg/104 cells versus 4.05 ± 0.2 pg/104 cells; P < 0.01). In the RT-PCR, the mRNA expression of both IL-6 and PCNA was upregulated in subconfluent GMCs as compared with confluent GMCs. An approximately four-fold increase in IL-6 mRNA expression and a two-fold increase in PCNA mRNA expression were shown. IL-6R mRNA expression was demonstrated in GMCs by RT-PCR. However, recombinant human IL-6, which stimulated the growth of B9 cells in a dose-dependent fashion, did not induce GMC proliferation. Conclusions. GMC-derived IL-6 may have significance as a marker of GMC proliferative activity, although GMC-derived IL-6 per se does not act as an autocrine growth factor for GMCs.