Vascular endothelial cadherin modulates renal interstitial fibrosis.

BACKGROUND/AIMS: Renal interstitial fibrosis is a final common pathway of all chronic, progressive kidney diseases. Peritubular capillary rarefaction is strongly correlated with fibrosis. The adherens junction protein vascular endothelial cadherin (VE-cadherin) is thought to play a critical role in vascular integrity. We hypothesized that VE-cadherin modulates the renal microcirculation during fibrogenesis and ultimately affects renal fibrosis. METHODS: Unilateral ureteral obstruction (UUO) was used as a renal fibrosis model in VE-cadherin heterozygote (VE+/-) and wild-type (WT) mice, and the kidneys were harvested at days 3, 7, and 14. Peritubular capillary changes and fibrogenesis were investigated. RESULTS: VE+/- mice had lower levels of VE-cadherin protein than WT mice at 3 and 7, but not 14 days after UUO. Vascular permeability was significantly greater in VE+/- mice 7 days after UUO, while peritubular capillary density was not significantly different in VE+/- and WT mice. Interstitial myofibroblast numbers and collagen I and III mRNA levels were significantly higher in VE+/- mice, consistent with a stronger early fibrogenic response. Expression of the pericyte marker neuron-glial antigen 2 was upregulated after UUO, but was not greater in VE+/- mice compared to the WT mice. CONCLUSION: Our data suggest that VE-cadherin controls vascular permeability and limits fibrogenesis after UUO.

Voltage-gated potassium channel Kv1.3 blocker as a potential treatment for rat anti-glomerular basement membrane glomerulonephritis.

The voltage-gated potassium channel Kv1.3 has been recently identified as a molecular target that allows the selective pharmacological suppression of effector memory T cells (T(EM)) without affecting the function of naïve T cells (T(N)) and central memory T cells (T(CM)). We found that Kv1.3 was expressed on glomeruli and some tubules in rats with anti-glomerular basement membrane glomerulonephritis (anti-GBM GN). A flow cytometry analysis using kidney cells revealed that most of the CD4(+) T cells and some of the CD8(+) T cells had the T(EM) phenotype (CD45RC(-)CD62L(-)). Double immunofluorescence staining using mononuclear cell suspensions isolated from anti-GBM GN kidney showed that Kv1.3 was expressed on T cells and some macrophages. We therefore investigated whether the Kv1.3 blocker Psora-4 can be used to treat anti-GBM GN. Rats that had been given an injection of rabbit anti-rat GBM antibody were also injected with Psora-4 or the vehicle intraperitoneally. Rats given Psora-4 showed less proteinuria and fewer crescentic glomeruli than rats given the vehicle. These results suggest that T(EM) and some macrophages expressing Kv1.3 channels play a critical role in the pathogenesis of crescentic GN and that Psora-4 will be useful for the treatment of rapidly progressive glomerulonephritis.

Involvement of epimorphin in the repair of experimental renal fibrosis in mice.

Interaction between epithelial cells and mesenchymal cells is essential in normal organ morphogenesis and in tissue repair after injury. Epimorphin, a mesenchymal protein that regulates epithelial morphogenesis through epithelial-mesenchymal interactions, has recently attracted attention as an important modulator of tissue repair. In this study we analyzed the role of epimorphin in renal fibrosis. We first found a progressive increase in epimorphin expression corresponding to the progression of renal fibrosis in mice with unilateral ureteral obstruction (UUO). To determine whether this expression has a role in the repair or progression of renal fibrosis, we analyzed a model of renal fibrosis repair, the UUO-release (UUO-R) model. Epimorphin expression was increased at 3 and 7 days after the UUO-R rather than on the day of release, but was decreased at 21 days after the release. Inhibition of endogenous epimorphin with anti-epimorphin antibody (MC-1) significantly delayed the repair of fibrosis. When compared with normal-IgG-injected mice, MC-1-injected mice showed significantly decreased renal matrix metalloproteinase (MMP)-2 and MMP-9 expressions by western blotting and increased expression of TGF-beta and collagen-I mRNA by real-time RT-PCR. Recombinant epimorphin induced prominent increases in MMP-2 and MMP-9 activities in the culture media of renal interstitial fibroblasts in vitro. These findings indicate that epimorphin has a pivotal role in the repair of renal fibrosis by modulating both extracellular matrix (ECM) degradation and its production.

Additive antifibrotic effects of pioglitazone and candesartan on experimental renal fibrosis in mice.

AIM: To examine the additive protective effects of the peroxisome proliferator-activated receptor-gamma agonist pioglitazone (Pio) and the angiotensin II receptor blocker candesartan (Cand) in a murine model of renal fibrosis: mice with unilateral ureteral obstruction (UUO). METHODS: Mice were randomly assigned into four groups that after UUO received i.p. injections of either Pio (10 mg/kg/day), Cand (1 mg/kg/day), Cand + Pio or vehicle for 10 days. Physiological parameters, the degree of renal fibrosis and molecules related to renal fibrosis were analysed, and sham-operated mice were used as controls. RESULTS: Total collagen assay showed prominent renal fibrosis in the vehicle-treated mice, significantly attenuated renal fibrosis in the Cand-treated and the Pio-treated mice, and further attenuated renal fibrosis in the (Cand + Pio)-treated mice. Real-time reverse transcription polymerase chain reaction revealed that this attenuation pattern was also evident in the expression of the mRNA for transforming growth factor-beta, collagens I and III, and plasminogen activator inhibitor-1. CONCLUSION: Pioglitazone and candesartan have additive protective effects on renal fibrosis due to UUO in mice, suggesting that their use in combination would be an effective treatment for chronic kidney disease.

[Antihypertensive treatment for chronic kidney disease].

The aims of treating hypertension in patients with chronic kidney disease including diabetes are to prevent both cardiovascular events and end stage renal failure, and goal of blood pressure is less than 130/80 mmHg. The first choice is angiotensin II receptor blocker (ARB) or angiotensin converting enzyme inhibitor. If the patient is salt-sensitive and hypervolemic, the second choice is diuretic. When the patient has some risk factors for cardiovascular events, the second choice is calcium channel blocker. In treating patient whose serum creatinine more than 2 mg/dL, we should start the ARB with lower dose and examine serum creatinine and potassium every 2 week.

A case of essential thrombocytosis developing nephrotic syndrome and severe endothelial damage.

We present a 75-year-old Japanese man with essential thrombocytosis presenting nephrotic syndrome. Proteinuria developed soon after the patient was given a diagnosis of essential thrombocytosis and, 4 years later, it increased to a nephrotic range. Renal biopsy revealed one third of the obtained glomeruli totally sclerotic and the other glomeruli showed a marked thickening of the glomerular basement membrane and mild mesangial proliferation. Remarkable widening of the subendothelial space was evident on electron microscopy. Increased expression of platelet derived growth factor receptor beta was detected in the mesangium and interstitium by immunohistochemistry. Abnormal platelet activation in myeloproliferative disease has been shown to contribute in glomerulosclerosis by releasing various growth factors and cytokines including PDGF. Considering his clinical course and the pathological findings, the probable risk factor for developing severe endothelial damage and glomerulosclerosis is due to the persistence of high platelet count and platelet abnormality.

An adult with acute poststreptococcal glomerulonephritis complicated by hemolytic uremic syndrome and nephrotic syndrome.

We report the case of a 47-year-old man with the simultaneous occurrence of clinical and laboratory features consistent with acute poststreptococcal glomerulonephritis (APSGN), hemolytic uremic syndrome (HUS), and nephrotic syndrome. Acute nephritic syndrome occurred 3 weeks after having pharyngeal pain and diarrhea. He presented with edema and hypertension on admission. Laboratory evaluation showed hemolytic anemia with fragmentation, thrombocytopenia, elevated lactic dehydrogenase level, low haptoglobin level, low complement C3 level, and elevated antistreptolysin-O titer. Serum creatinine level was 1.22 mg/dL (108 micromol/L), and urinalysis showed marked proteinuria, with protein of 8.7 g/d, and hematuria. The renal biopsy specimen was characteristic of APSGN, but not HUS. Moderate expansion of the mesangial matrix, moderate proliferation of epithelial and endothelial cells, and marked infiltration of neutrophils was seen by means of light microscopy, and many subepithelial humps were seen by means of electron microscopy. Neither fibrin deposition nor evidence of thrombotic microangiopathy was found. Complement C3 deposition along the capillary wall and tubules was seen in an immunofluorescence study. The patient was administered plasma infusion at 320 mL/d and antihypertensive drugs. Serum complement C3 and haptoglobin levels returned to normal within 3 weeks. This is a rare case of the simultaneous occurrence of APSGN, HUS, and nephrotic syndrome.

Effect of risedronate on high-dose corticosteroid-induced bone loss in patients with glomerular disease.

BACKGROUND: Corticosteroids are often used for the treatment of glomerular diseases. We examined whether bisphosphonate or vitamin D3 has beneficial effects on bone mineral density (BMD) in patients with glomerular diseases being treated with high-dose corticosteroids, including pulse therapy. METHODS: Thirty-eight patients (19 men and 19 women, aged 42 +/- 16 years) were randomized into three groups: bisphosphonate alone (risedronate 2.5 mg/day, group R, n = 12), vitamin D3 alone (alfacalcidol 0.5 mug/day, group A, n = 15) and the combination of both agents (group R+A, n = 11). BMD at the lumbar spine was measured before and 12 months after treatment. The biochemical parameters of bone metabolism were assessed before and 3, 6 and 12 months after treatment. RESULTS: In group R+A, BMD was significantly increased (+2.0%), whereas BMD was significantly decreased in group A (-5.6%). The BMD in group R did not show a significant change. In patients treated with steroid-pulse, BMD was decreased in groups R and A. In group R+A, BMD was significantly increased (+2.1%). Serum osteocalcin and alkaline phosphatase levels, markers of bone formation, were significantly decreased in all groups. Urinary crosslinked N-telopeptide of type I collagen (NTx) levels, a marker of bone resorption, were decreased in groups R and R+A. In patients with decreased BMD, the urinary NTx levels at baseline were significantly higher than the patients with increased BMD. CONCLUSIONS: Bisphosphonate might be beneficial for the prevention of steroid-induced bone loss in patients with glomerular diseases compared with vitamin D3. The combined therapy may be more effective, especially in patients treated with high-dose corticosteroids, including pulse therapy. A high urinary NTx level before receiving corticosteroids might be a predictive marker of the loss of BMD.

Advanced glycation end-product induces fractalkine gene upregulation in normal rat glomeruli.

BACKGROUND: We previously reported that fractalkine was upregulated in streptozotocin-induced diabetic kidneys. Fractalkine in diabetic kidneys was detected on glomerular capillaries and the mesangium. This upregulation was suppressed by treatment with angiotensin-converting enzyme inhibitor (ACE-I) or aminoiguanidine. We examined what factors induce fractalkine upregulation in normal rat glomeruli. METHODS: Glomeruli were collected from the kidneys of normal Sprague-Dawley rats by a microdissection method. Ten glomeruli were incubated in a solution with glucose, mannitol, angiotensin II, tumour necrosis factor (TNF)-alpha and advanced glycation end-product (AGE)-bovine serum albumin (BSA) for 1, 2 and 4 h. Fractalkine mRNA expression in glomeruli was examined by reverse transcription-polymerase chain reaction. RESULTS: Fractalkine mRNA levels in the 30 mM glucose solution significantly increased (121%) compared with those in the control or 30 mM mannitol solution at 1 h. Fractalkine mRNA levels in the 15 mM glucose solution showed no significant differences at 1 or 2 h, but significantly increased (106%) after 4 h incubation. Fractalkine mRNA levels in 10(-6)-10(-8) M angiotensin II solution showed no significant differences. Fractalkine mRNA levels in the 5 or 10 ng/ml TNF-alpha solution significantly increased compared with those in the control in a time- and dose-dependent manner (by 94 to 253%). Fractalkine mRNA levels in the 50-200 microg/ml AGE-BSA solution also increased compared with those in BSA solution in a time- and dose-dependent manner (by 119 to 261%). By pre-incubation with MG132, a nuclear factor-kappaB inhibitor, fractalkine upregulation by AGE-BSA or 30 mM glucose was completely suppressed. CONCLUSIONS: High glucose levels, AGE formation and cytokine activation in diabetes may induce fractalkine upregulation in the kidneys and lead to progression of diabetic nephropathy.

Mizoribine reduces renal injury and macrophage infiltration in non-insulin-dependent diabetic rats.

BACKGROUND: Macrophage infiltration in kidney is one of the most important events for the progression of diabetic nephropathy. Mycophenolate mofetil (MMF), an anti-inflammatory agent, has been shown to suppress macrophage infiltration and to improve renal injury in streptozotocin-induced diabetic kidneys. We examined whether mizoribine, which acts through immunosuppressive mechanisms similar to MMF, inhibits progression of diabetic nephropathy in non-insulin-dependent diabetic rats. METHODS: Male Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a non-insulin-dependent diabetic model, and Long-Evans Tokushima Otsuka (LETO) rats, a non-diabetic control, were studied at 35 weeks of age. OLETF rats were randomized to receive mizoribine (5 or 10 mg/kg) or normal saline for 8 weeks. Histological changes such as glomerulosclerosis and interstitial fibrosis and the number of ED1- and CD5-positive cells in the kidney were assessed. By using reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry, monocyte chemoattractant protein-1 (MCP-1), osteopontin (OPN) and transforming growth factor (TGF)-beta1 expression in the kidney was also analysed. RESULTS: Urinary albumin excretion in OLETF rats increased compared with that in LETO rats. Administration of mizoribine suppressed urinary albumin excretion. Development of glomerulosclerosis, interstitial fibrosis and macrophage infiltration in the kidney was also inhibited by treatment with mizoribine. The expression of MCP-1, OPN and TGF-beta1 mRNA in untreated OLETF rats was significantly increased compared with that in LETO rats. By immunohistochemistry, increased expression of MCP-1, OPN and TGF-beta1 was found in the tubules and glomeruli of untreated OLETF rats. This expression was significantly suppressed by treatment with mizoribine. CONCLUSIONS: Mizoribine inhibited renal macrophage accumulation and prevented the progression of glomerulosclerosis and interstitial fibrosis in non-insulin-dependent diabetic kidneys. In addition to standard treatments, anti-inflammatory agents may be useful for management of non-insulin-dependent diabetic nephropathy.