Mizoribine ameliorates the tubulointerstitial fibrosis of obstructive nephropathy

Influence of cyclosporine A on glomerular growth and the effect of mizoribine and losartan on cyclosporine nephrotoxicity in young rats

The aim of this study was to evaluate the influence of cyclosporine A (CsA) on glomerular growth and the effect of mizoribine (MZR) and losartan (LSAR) on CsA-induced nephropathy in young rats. Six-week-old male Sprague-Dawley rats maintained on a low salt diet were given CsA (15 mg/kg), CsA and LSRT (30 mg/kg/day), CsA and MZR (5 mg/kg), or a combination of CsA, LSRT, and MZR for 4 and 7 weeks (two experiments) and compared with control group (olive oil-treated). Histopathology and glomerular size, inflammatory and fibrotic factors were studied. The score of acute CsA toxicity significantly decreased in the CsA + MZR group compared to the CsA group (p < 0.01). MZR and MZR + LSRT reduced tubulointerstitial fibrosis and TGF-β1 mRNA expression at 7 weeks. Osteopontin (OPN) mRNA expression was decreased at 7 weeks in MZR + LSRT (p < 0.01). Glomerular area decreased CsA group and recovered in MZR (p < 0.01) and MZR + LSRT (p < 0.01) at 7weeks. This study demonstrated that MZR and LSRT had suppressive effects on inflammatory process in chronic CsA nephropathy and led to improvement of tubular damage, tubulointerstitial fibrosis and arteriolopathy by down regulation of OPN and TGF-β1 and glomerular size contraction.

Mizoribine in the treatment of pediatric-onset glomerular disease

BACKGROUND

Mizoribine (MZR) is a selective inhibitor of inosine monophosphate dehydrogenase, a key enzyme in the pathway responsible for de novo synthesis of guanine nucleotides. As an immunosuppressant, MZR has been used successfully without any serious adverse effects in the treatment of renal diseases in children as well as adults. Besides its immunosuppressive effect, MZR has been reported to ameliorate tubulointerstitial fibrosis in rats via suppression of macrophage infiltration.

DATA SOURCES

In this review, we summarize reported possible benefits of MZR in the treatment of pediatriconset glomerular disease.

RESULTS

We recently observed that MZR itself selectively attenuates the expression of monocyte chemoattractant protein-1 at both the mRNA and protein levels in human mesangial cells. Since MZR binds specifically to 14-3-3 proteins and heat shock protein 60, both of which are reportedly expressed in inflamed glomeruli, MZR may bind directly to inflamed glomerular cells, thereby possibly preventing progressive damage from glomerulonephritis through a suppressive effect on activated macrophages and intrinsic renal cells. Moreover, it has recently been reported that MZR directly prevents podocyte injury through correction of the intracellular energy balance and nephrin biogenesis in cultured podocyte and rat models, suggesting a direct anti-proteinuric effect of MZR.

CONCLUSIONS

These beneficial mechanisms of action of MZR as well as its immunosuppressive effect would warrant its use in the treatment of pediatric-onset glomerular disease. Although further studies remain to be done, we believe that MZR may be an attractive treatment of choice for children with glomerular diseases from a histologic as well as clinical standpoint.

Mizoribine selectively attenuates monocyte chemoattractant protein-1 production in cultured human glomerular mesangial cell: a possible benefit of its use in the treatment of lupus nephritis

AIM

Mizoribine (MZR) is a selective inhibitor of the inosine monophosphate dehydrogenase - a key enzyme in the de novo pathway of guanine nucleotides - that was developed in Japan. Besides its immunosuppressive effects, MZR has recently been reported to suppress the progression of histologic chronicity via suppression of macrophage infiltration of the interstitium in selected patients with lupus nephritis.

METHODS

We examine the direct effect of MZR in human mesangial cells on the expression of functional molecules including monocyte chemoattractants in cultured human mesangial cells (MCs) treated with polyinosinic-polycytidylic acid (poly IC), a synthetic analogue of viral dsRNA, that makes 'pseudoviral' infection, and analyzed the expression of target molecules by reverse transcriptase-polymerase chain reaction and Western blotting. Thereafter, the effect of MZR on the expressions was examined.

RESULTS

Pretreatment of cells with MZR partially, but significantly, attenuates the expression of monocyte chemoattractant protein (MCP)-1 mRNA and protein, whereas the poly IC-induced expressions for the other functional molecules, such as CCL5, fractalkine and IL-8 were not influenced by MZR treatment. On the other hand, pretreatment of cells with tacrolimus did not suppress the expression of MCP-1 mRNA.

CONCLUSION

Mizoribine itself selectively attenuated the expression of MCP-1 both mRNA and protein levels in MCs treated with poly IC; that is, a possible model of 'pseudoviral' infection, which may be involved in the pathogenesis of lupus nephritis.

Synergistic protective effects of mizoribine and angiotensin II receptor blockade on cyclosporine A nephropathy in rats

BACKGROUND

Chronic cyclosporine A (CsA) nephrotoxicity is manifested by renal dysfunction, progressive histopathological kidney lesions characterized by afferent arteriolopathy, and tubulointerstitial fibrosis. In addition to the direct toxic effect of CsA, many other etiological factors such as angiotensin II, transforming growth factor (TGF)-β, and macrophage infiltration are involved in this pathogenesis. This study investigated the hypothesis that concomitant administration of mizoribine (MZR) and angiotensin II receptor blockade (ARB) may prevent CsA nephrotoxicity in rats.

METHODS

Sprague-Dawley male rats were divided into the following seven groups: group 1, treated with CsA; group 2, treated with CsA + MZR; group 3, treated with CsA + valsartan (Val); group 4, treated with CsA + MZR + Val; group 5, treated with MZR; group 6, treated with Val; and group 7, controls (n = 5 each). Renal histopathology and the effect of CsA-induced nephrotoxicity on inflammatory mediators were evaluated.

RESULTS

Results of this study demonstrated that ARB administration significantly decreased arteriolopathy and that in comparison with monotherapy, concomitant administration of MZR and ARB further decreased arteriolopathy, fibrosis, macrophage infiltration, and TGF-β1 mRNA expression associated with CsA nephrotoxicity.

CONCLUSION

These findings indicate that MZR and ARB combination treatment provides synergistic protective effects against chronic CsA nephrotoxicity.

Successful treatment of adult IgA nephropathy with nephrotic-level proteinuria by combination therapy including long-term coadministration of mizoribine

A 41-year-old male patient was admitted to our hospital due to massive proteinuria and hematuria. His 24-hour urinary protein excretion and the number of urinary erythrocytes were 3.91 g/day and 50–99/high-power field, respectively. A renal biopsy showed a severe pathological pattern of immunoglobulin A nephropathy (IgAN) that involved marked endocapillary proliferation and segmental sclerosis (Oxford-MEST score: M0, E1, S1, T0). Because he had nephrotic-level proteinuria with severe pathological findings, which are tonsillectomy and corticosteroid pulse therapy-resistant characteristics, he received mizoribine for a long period as part of the combination therapy using corticosteroid, tonsillectomy, dipyridamole, warfarin and renin-angiotensin-aldosterone system blockers. Twelve months after the beginning of treatment, his urinary findings were normal. In this report, we describe the pathological findings and successful treatment course, and discuss the potential effects of long-term coadministration of mizoribine for adult IgAN treatment.

Mizoribine suppresses proliferation of rat glomerular epithelial cells in culture and inhibits increase of monocyte chemoattractant protein-1 and macrophage inflammatory protein-2 stimulated by thrombin

Glomerular crescents play an important role in progressive glomerular injury. The lesions consist of epithelial cells, macrophages and fibrin deposition. Macrophage chemoattractant protin-1 (MCP-1) is a chemoattractant of monocytes, which has a potential of procoagulant activity. Macrophage inflammatory protein-2 (MIP-2) is a chemoattractant of neutrophils and acute necrotizing injury is primarily mediated by neutrophils in crescentic glomerulonephritis. Mizoribine (MZR) is an immunosuppressive drug and it has been used for organ transplantation and treatment of various autoimmune diseases. The aim of this study is to investigate the effects of MZR on glomerular epithelial cells (GEC). Rat GEC were cultured with K1 medium and used from 12th to 14th passage. GEC proliferation was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. MCP-1 and MIP-2 were quantified by enzyme-linked immunosorbent assay (ELISA) in culture supernatants and mRNA expressions of MCP-1 and MIP-2 were analyzed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The proliferation of GEC was suppressed by MZR in a dose-dependent manner in the range of 1.0-100.0 µg/mL. These concentrations of MZR had no toxic effect to GEC. Thrombin (1.0-5.0 U/mL) enhanced the production of MCP-1, MIP-2 and the mRNA expressions of MCP-1 and MIP-2. The stimulatory effect of thrombin was inhibited by addition of MZR (10 µg/mL). It is concluded that MZR may be useful for the treatment of crescentic glomerulonephritis.

Methylprednisolone pulse therapy combined with mizoribine following tonsillectomy for immunoglobulin A nephropathy: clinical remission rate, steroid sparing effect, and maintenance of renal function

Background

The long-term prognosis of immunoglobulin A nephropathy (IgAN) is reportedly poor. In Japan, tonsillectomy-steroid pulse therapy has frequently been used for treatment of early IgAN, with favorable outcomes. However, steroid usage is sometimes limited due to adverse reactions. To reduce the total dose of steroids, we have been using mizoribine (MZR) in combination with tonsillectomy-steroid pulse therapy since 2004. Here we report a retrospective evaluation of our protocol outcome.

Methods

Forty-two patients aged <70 years with histopathologically confirmed IgAN and an estimated glomerular filtration rate (eGFR) of 30 ml/min/1.73 m² or higher were enrolled. After giving informed consent, all the patients underwent bilateral tonsillectomy. One week later, intravenous methylprednisolone pulse therapy (500 mg/day) was administered for 3 days, followed by oral prednisolone (30 mg/day and tapered to 0 over 7 months) and MZR (150 mg/day for 11 months). The complete remission (CR) rate and renoprotective effect were assessed.

Results

The CR rate at 6, 12, and 24 months was 33.3, 69.1, and 76.2%, respectively. Despite a relatively low total steroid dose, renal function was satisfactorily maintained for 24 months or longer with no relapse. The eGFR in patients with stage 3 chronic kidney disease was significantly improved at 6 months after start of treatment. Three patients (7.1%) had mild and transient adverse events.

Conclusion

This protocol appears to be highly effective and safe for IgAN patients with renal dysfunction.

Mizoribine attenuates renal injury and macrophage infiltration in patients with severe lupus nephritis

The purine synthesis inhibitor mizoribine (MZR) has been successfully used without serious adverse effects in the treatment of several renal diseases including lupus nephritis. Besides its immunosuppressive effects, MZR has recently been reported to ameliorate tubulointerstitial fibrosis in rats via suppression of macrophage infiltration. However, there has been little information regarding the beneficial effects of MZR from the histologic standpoint in human lupus nephritis. Pre- and posttreatment renal biopsy specimens obtained from nine patients with diffuse proliferative lupus nephritis (DPLN) were divided into two groups (group A, five patients who received immunosuppressive treatment with MZR and group B, four patients who received immunosuppressive treatment without MZR) and histologically evaluated. Grading was done according to the 2003 classification system for lupus nephritis developed by the International Society of Nephrology/Renal Pathology Society, which considers the activity and chronicity indices, an immunohistologic study to assess intraglomerular and interstitial infiltration by macrophages, and the expression of osteopontin. Although in all the patients the posttreatment renal biopsy showed improvement of histologic grading and activity indices, group A patients showed a significant decrease of the chronicity indices and of intraglomerular infiltration by macrophages when compared to group B patients (2.6 +/- 0.5 vs 4.0 +/- 1.4 and 0.5 +/- 0.2 vs 2.4 +/- 1.9 cells per glomerulus, respectively; p < 0.05). Although this was a preliminary study in a small number of subjects, these histological observations may further confirm the beneficial effects of MZR for selected patients with DPLN.

Role of inflammation in túbulo-interstitial damage associated to obstructive nephropathy

Obstructive nephropathy is characterized by an inflammatory state in the kidney, that is promoted by cytokines and growth factors produced by damaged tubular cells, infiltrated macrophages and accumulated myofibroblasts. This inflammatory state contributes to tubular atrophy and interstitial fibrosis characteristic of obstructive nephropathy. Accumulation of leukocytes, especially macrophages and T lymphocytes, in the renal interstitium is strongly associated to the progression of renal injury. Proinflammatory cytokines, NF-κB activation, adhesion molecules, chemokines, growth factors, NO and oxidative stress contribute in different ways to progressive renal damage induced by obstructive nephropathy, as they induce leukocytes recruitment, tubular cell apoptosis and interstitial fibrosis. Increased angiotensin II production, increased oxidative stress and high levels of proinflammatory cytokines contribute to NF-κB activation which in turn induce the expression of adhesion molecules and chemokines responsible for leukocyte recruitment and iNOS and cytokines overexpression, which aggravates the inflammatory response in the damaged kidney. In this manuscript we revise the different events and regulatory mechanisms involved in inflammation associated to obstructive nephropathy.

Prevention of renal interstitial fibrosis via histone deacetylase inhibition in rats with unilateral ureteral obstruction

Acute rejection following renal transplantation has become manageable with the introduction of calcineurin inhibitors, FK506 and cyclosporine A. However, chronic allograft dysfunction accompanied by renal interstitial fibrosis, which induces graft loss, remains unresolved. Here, we evaluated the effect of FR276457, a pan-histone deacetylase (HDAC) inhibitor, on interstitial fibrosis in the injured kidneys of a rat model of unilateral ureteral obstruction. The injured kidneys, harvested on Day 14 following the operation, showed progression of interstitial fibrosis, increases of hydroxyproline contents, and mRNA expression of collagen type Ialpha1 and monocyte chemotactic protein 1 (MCP-1). However, these changes were found to be prevented with daily oral administration of FR276457. In addition, given that MCP-1 is believed to contribute to progressive fibrosis, we investigated the direct effect of FR276457 on MCP-1 production by activated THP-1 cells in vitro. Results showed that FR276457 administration decreased MCP-1 production in these cells in a concentration-dependent manner. Findings from the present study suggested that a pan-HDAC inhibitor may exert a prophylactic effect against renal interstitial fibrosis by inhibiting MCP-1 production.

Protective effects of Mizoribine on Cyclosporine A nephropathy in rats

The therapeutic benefits of Cyclosporine A (CsA) are often limited by the chronic nephrotoxicity of its long-term use. Chronic nephrotoxicity is manifested by renal function impairment and progressive histopathological kidney lesions characterized by tubular vacuolization, tubular necrosis, interstitial fibrosis, and afferent arteriolopathy. This study tested the hypothesis that the concurrent administration of Mizoribine (MZR) may improve chronic CsA nephrotoxicity. Sprague-Dawley male rats were divided into the following four groups: group 1, control (n = 6); group 2, treated with CsA alone (n = 5); group 3, treated with CsA and MZR (n = 4); and group 4, treated with MZR alone (n = 6). The anti-inflammatory and antifibrotic effects of MZR were studied by evaluating the concentrations of the inflammatory mediator, osteopontin, renal function, and histopathology. The interstitial fibrosis was stained blue with Elastica-Massontrichrome and the sections were quantified. The CsA-treated rats showed decreased renal function and increased histologic parameters in comparison with the control rats and also showed significantly increased interstitial fibrosis area and macrophage in comparison with the control rats. The CsA MZR treatment significantly improved the interstitial fibrosis area and macrophage in comparison with the CsA-treated rats. On the basis of these findings, we suggest MZR effectively attenuates renal macrophage accumulation and the progression of interstitial fibrosis.

Use of mizoribine as a rescue drug for steroid-resistant pediatric IgA nephropathy

Recent clinical trials have shown a beneficial effect of mizoribine (Miz), an immunosuppressive drug, in the treatment of new-onset pediatric IgA nephropathy (IgAN). In this study, we evaluated the efficacy of Miz treatment in three children with established steroid-resistant IgAN. The patients had IgAN featuring persistent proteinuria and diffuse mesangial proliferation and had failed to respond to 2 years of treatment with prednisolone. Based upon the second biopsy results, patients were given methylprednisolone (mPSL) pulse therapy that induced a transient reduction in proteinuria, which was reversed when the mPSL dose was tapered. Miz therapy was then instigated in place of pulse mPSL. All three patients showed a substantial reduction in proteinuria and resolution of hematuria within 5 months. A follow-up biopsy in two of the patients showed a substantial reduction in the severity of glomerular lesions and a decrease in the number of activated macrophages. In conclusion, Miz therapy was found to be a safe and effective therapy in three cases of steroid-resistant pediatric IgAN. The ability of Miz to reduce the number of activated macrophages may be an important mechanism by which this drug ameliorated renal disease in these patients.

Cobalt protoporphyrin attenuates rat obstructive nephropathy: role of cellular infiltration

OBJECTIVES

Renal interstitial inflammation is closely related to the progressive renal fibrosis. It has been reported that heme oxygenase-1 (HO-1) induction attenuated renal fibrosis in obstructive nephropathy. To elucidate the antifibrogenic mechanisms of HO-1, we examined the effect of HO-1 induction on renal interstitial inflammation.

METHODS

Adult male rats underwent unilateral ureteral obstruction (UUO). The rats were pretreated with cobalt protoporphyrin (CoPP, a potent HO-1 inducer; 15 or 50 mg/kg) subcutaneously on the day -6 and -1 before UUO. Sham-operated rats served as controls. Renal interstitial fibrosis, macrophage and T cell infiltration were immunohistochemically assessed on the day 5 after UUO. Gene expressions of HO-1 and profibrogenic molecules were determined by real-time reverse transcriptase-polymerase chain reaction.

RESULTS

CoPP dose-dependently induced HO-1 activity, protein, and messenger RNA (mRNA) expression in the renal cortices. CoPP significantly attenuated the renal fibrosis in a dose-dependent manner. Gene expressions of transforming growth factor-beta and extracellular matrix proteins were upregulated in UUO and were attenuated by CoPP. CoPP markedly inhibited T cell infiltration. Unexpectedly, it enhanced macrophage influx dose dependently. Double immunostaining of macrophage and HO-1 showed that CoPP elicited HO-1 overexpression in infiltrating macrophages, whereas UUO alone did not.

CONCLUSIONS

HO-1 induction protected against the renal interstitial fibrosis in rat obstructive nephropathy. It is suggested that inhibition of T cell influx is, at least in part, involved in the protection. Increased macrophages that overexpress HO-1 may play an important role in attenuating renal fibrosis.

Long-term intermittent pulse therapy with mizoribine attenuates histologic progression in young patients with severe lupus nephritis: report of two patients

Mizoribine (MZR), a novel selective inhibitor of inosine monophosphate dehydrogenase in the de novo pathway, whose mode of action is very similar to that of mycophenolate mofetil, has been successfully applied without serious adverse effects for the treatment of renal diseases. We have previously reported the efficacy and safety of a new MZR treatment regimen, namely, oral MZR intermittent pulse therapy, which we examined based on the observation that it might show superior efficacy to the conventional daily low-dose MZR regimen on account of the higher peak serum MZR levels, in selected patients with lupus nephritis. Two Japanese patients with severe lupus nephritis (WHO class IV-G) who were administered long-term intermittent MZR pulse therapy, and in whom pre- and post-treatment renal biopsies were reported. Post-treatment renal biopsy confirmed the marked attenuation of histologic progression by the treatment. These clinical observations may lend further support, from the histologic standpoint, to the efficacy of long-term MZR intermittent pulse therapy for selected patients with active lupus nephritis.

Activation of ERK in renal fibrosis after unilateral ureteral obstruction: modulation by antioxidants

BACKGROUND

A recent in vitro model of oxidative stress-induced renal fibrosis demonstrated that activated or phosphorylated extracellular signal-regulated protein kinase (pERK) played a role in apoptosis of renal fibroblasts, but not tubular epithelium where it promoted cell growth and survival. The present study utilized an in vivo model of renal fibrosis after unilateral ureteral obstruction (UUO) to examine the relationship between pERK, apoptosis, proliferation, and differentiation in renal fibroblast and tubular epithelial cells, in comparison with the in vitro results.

METHODS

UUO was induced in rats for 0 (controls, untreated), 6, and 24 hours, 2, 4, and 7 days (N= 4), and tissue analyzed for fibrotic characteristics using microscopy and special stains, Western immunoblots and reverse transcription-polymerase chain reaction (RT-PCR). Controls and UUO animals were also treated with vitamin E, N-acetylcysteine (NAC), or fluvastatin to assess any antioxidant effect on attenuation of fibrosis and pERK expression.

RESULTS

Azan stain and alpha-smooth muscle actin (alpha-SMA), collagen III, and fibronectin expression confirmed development of UUO-induced fibrosis. Oxidative stress markers heme oxygenase-1 (HO-1) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) confirmed oxidative stress at all UUO time points. Tubular epithelial and interstitial mitosis and apoptosis were significantly increased over controls at 2 to 7 days after UUO (P < 0.01). The pERK/ERK ratio increased significantly at 1 to 7 days of UUO in comparison with controls (three- to fivefold, P < 0.05). There was a significant spatiotemporal correlation between pERK and tubular epithelial proliferation (P < 0.001). pERK occasionally colocalized with apoptotic cells (dual labeling) in the interstitium but not in the tubular epithelium. Fluvastatin was the only treatment that attenuated fibrosis (decreased alpha-SMA, fibronectin, tubular epithelial apoptosis) and it also significantly decreased expression of 8-OHdG at 2 and 7 days (P < 0.05). It was associated with decreased pERK at 7 days, compared with UUO alone (P < 0.05).

CONCLUSION

Promotion of tubular epithelial proliferation and survival, and interstitial cell apoptosis, may minimize renal fibrosis after UUO. In the present study, both were linked spatially and temporally with increased pERK expression. Fluvastatin treatment attenuated UUO-induced fibrosis via an antioxidant and pERK-related mechanism.

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.

Fasudil attenuates interstitial fibrosis in rat kidneys with unilateral ureteral obstruction

This study was designed to investigate possible effects of the Rho-kinase inhibitor, fasudil, on the progression of renal failure in rats with unilateral ureteral obstruction. The renal failure markers monitored were the extent of renal interstitial fibrosis and that of macrophage infiltration. In kidneys with unilateral ureteral obstruction, interstitial fibrosis was observed, using Sirius-Red staining, on day 16 after unilateral ureteral obstruction. Macrophage infiltration was observed by immunohistochemistry, using the antibody, ED1. Interstitial fibrosis and macrophage infiltration were significantly attenuated in fasudil-treated animals. The migration of monocytes in vitro elicited by N-formyl-methionyl-leucyl-phenylalanine was potently inhibited by fasudil and its active metabolite, hydroxyfasudil. These results suggest that inhibition of Rho-kinase produces a reduction of macrophage infiltration and represents a new therapeutic strategy for renal fibrosis, a major factor in the progression to end-stage renal failure.