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

Effects of coconut oil long-term supplementation in Wistar rats during metabolic syndrome - regulation of metabolic conditions involving glucose homeostasis, inflammatory signals, and oxidative stress

This study was designed to evaluate the long-term effects of Fructose (20%) feeding in rats, simulating metabolic syndrome (MetS), and the effects of coconut oil (C.O.) supplementation when administered in a MetS context. MetS is a cluster of systemic conditions that represent an increased chance of developing cardiovascular diseases and type 2 diabetes in the future. C.O. has been the target of media speculation, and recent studies report inconsistent results. C.O. improved glucose homeostasis and reduced fat accumulation in Fructose-fed rats while decreasing the levels of triglycerides (TGs) in the liver. C.O. supplementation also increased TGs levels and fructosamine in serum during MetS, possibly due to white adipose tissue breakdown and high fructose feeding. Pro-inflammatory cytokines IL-1β and TNF-α were also increased in rats treated with Fructose and C.O. Oxidative stress marker nitrotyrosine is increased in fructose-fed animals, and C.O. treatment did not prevent this damage. No significant changes were observed in lipoperoxidation marker 4-Hydroxynonenal; however, fructose feeding increased total conjugated dienes and caused conjugated dienes to switch their conformation from cis-trans to trans-trans, which was not prevented by C.O. treatment. Potential benefits of C.O. have been reported with inconsistent results, and indeed we observed some benefits of C.O. supplementation in aiding weight loss, fat accumulation, and improving glucose homeostasis. Nonetheless, we also demonstrated that long-term C.O. supplementation could present some problematic effects with higher risk for individuals suffering MetS, including increased TGs and fructosamine levels and conformational changes in dienes.

JNK1 regulates RANKL-induced osteoclastogenesis via activation of a novel Bcl-2-Beclin1-autophagy pathway

JNK1 plays an important role in osteoclastogenesis in response to the osteoclastogenic cytokine receptor activator for nuclear factor-κB ligand (RANKL). JNK1 is widely accepted as an autophagy regulator under stress conditions. However, the role of JNK1-mediated autophagy in osteoclastogenesis remains largely unknown. In the current study, our data showed that JNK1 inhibition by a pharmacological inhibitor or RNA interference significantly reduced the autophagic response induced by RANKL in osteoclast precursors (OCPs) derived from bone marrow-derived macrophages. Overexpression of the key autophagy protein Beclin1 rescued autophagy deficiency and osteoclastogenesis in the presence of a JNK inhibitor (SP600125). In contrast, JNK activator (anisomycin)-induced autophagy was blocked by Beclin1 knockdown in OCPs. In addition, JNK1 inhibition increased apoptosis and blocked autophagy, whereas overexpression of Beclin1 reversed the enhanced apoptosis induced by JNK1 inhibition in OCPs. Furthermore, RANKL could induce the phosphorylation of Bcl-2, subsequently dissociating Beclin1 from the Bcl-2-Beclin1 complex, which could be blocked by JNK1 inhibition. Collectively, this study revealed that JNK1 regulated osteoclastogenesis by activating Bcl-2-Beclin1-autophagy signaling in addition to the classic c-Jun/activator protein 1 pathway, which provided the first evidence for the contribution of JNK1 signaling to OCP autophagy and the autophagic mechanism underlying JNK1-regulated osteoclastogenesis. An important osteoclastogenesis-regulating signaling pathway (JNK1-Bcl-2-Beclin1-autophagy activation) was identified, which provides novel potential targets for the clinical therapy of metabolic bone diseases.-Ke, D., Ji, L., Wang, Y., Fu, X., Chen, J., Wang, F., Zhao, D., Xue, Y., Lan, X., Hou, J. JNK1 regulates RANKL-induced osteoclastogenesis via activation of a novel Bcl-2-Beclin1-autophagy pathway.

Maternal protein restriction that does not have an influence on the birthweight of the offspring induces morphological changes in kidneys reminiscent of phenotypes exhibited by intrauterine growth retardation rats

Severe restriction of maternal protein intake to 6-8% protein diet results in intrauterine growth retardation (IUGR), low birthweight and high risk of metabolic syndrome in the adult life of the offspring. However, little information is available on the effects of maternal protein restriction on offspring under the conditions that does not have an influence on their birthweight of the offspring,. In the present study, pregnant rats were kept on a diet consisting of either 9% (low-protein, Lp rats) or 18% (normal-protein, Np rats) protein by weight/volume/etc. After birth, both Lp and Np rats were kept on a diet containing 18% protein. Neonatal body weight was significantly lower in Lp rats compared to Np rats from 4 days to 5 weeks after birth. While glomerular number per unit volume (1 mm(3) ) of the kidney (Nv) was comparable between Lp and Np rats 4 weeks after birth, the Nv was significantly decreased in Lp rats at 20 weeks after birth. Four and 20 weeks after birth, glomerular sclerosis index, interstitial fibrosis score, and ratio of ED1-positive cell ratio were all significantly higher in Lp compared to Np rats. Transforming growth factor-β1-positive cells were observed in the distal tubules in the kidney of 4- and 20-week-old Lp rats kidneys, but not in those of age-matched Np rats. Altogether, these findings revealed that maternal protein restriction that does not have an influence on the birthweight of the offspring, induces similar changes as those seen in the kidneys of IUGR neonates.

Comparison of immunosuppressive therapies for IgA nephropathy after tonsillectomy: three-course versus one-course steroid pulse combined with mizoribine

Purpose

It has been reported that steroid pulse therapy for IgA nephropathy improves renal prognosis. However, because of the side effects, steroid dose must be restricted to some cases. Treatment effects of steroid on cases already presenting with reduced renal function are unknown. In this study, we performed tonsillectomy in patients with IgA nephropathy and conducted a comparative study about subsequent immunosuppressive therapy.

Methods

Subjects were patients younger than 70 years of age diagnosed with IgA nephropathy by renal biopsy. Treatment protocols were a single-course steroid pulse combined with mizoribine during a period from August 2006 to June 2010 (Group A; n = 34) and a three-course steroid pulse during a period from July 2010 to March 2013 (Group B; n = 32). Primary end points were excretory amounts of proteinuria, disappearance of proteinuria and hematuria, and exacerbation of renal function.

Results

In both the groups, proteinuria decreased significantly 12 months after treatment, and no significant difference in alleviation effects on proteinuria was found between groups. eGFR increased significantly 12 months after treatment in Group A, whereas it tended to decrease in Group B. As for the preservation effect on eGFR, Group A showed significantly higher preservation of eGFR. Similar results were shown in the patients whose eGFR at the start of the treatment was less than 60 mL/min/1.73 m².

Conclusions

Single-course steroid pulse therapy combined with mizoribine was considered to have a protective effect on the renal function in IgA nephropathy, especially accompanying renal dysfunction.

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.

Increased macrophage activation inhibited by tacrolimus in the kidney of diabetic rats

BACKGROUND/AIMS

Accumulating evidence suggests that macrophage-induced inflammation may be the mechanism of development and progression of diabetic nephropathy. A previous study by our group has shown that tacrolimus, like cyclosporin A, has a renoprotective effect in diabetic rats. The present study aimed to elucidate the underlying molecular events.

METHODS

Diabetic rats were induced by using streptozotocin. Diabetic rats were subjected to oral tacrolimus treatment at a dose of 0.5 or 1.0 mg/kg daily for 4 weeks. Body weight, blood glucose, hemoglobin A(1c) (HbA(1c)) and renal pathology were assessed, followed by analyses of renal calcineurin (CaN) expression, changes in renal macrophage infiltration, proliferation and activation, and detection of renal TLR2+ and TLR4+ as well as NF-κB-p-p65+ in macrophages.

RESULTS

Diabetic rats had a reduced body weight and increased blood glucose and HbA(1c) levels, whereas tacrolimus treatment did not affect body weight or blood glucose and HbA(1c). Increased relative kidney weight was only significantly reduced by tacrolimus treatment at a dose of 1.0 mg/kg, while the elevated albumin excretion rate was markedly attenuated after treatment with tacrolimus (0.5 and 1.0 mg/kg) in diabetic rats. Elevated glomerular volume was significantly attenuated by tacrolimus treatment with 0.5 and 1.0 mg/kg, and increased indices for tubulointerstitial injury were only ameliorated by tacrolimus treatment with 1.0 mg/kg. Western blot data showed that expression of CaN protein was induced 2.4-fold in the kidneys of positive control diabetic rats, whereas tacrolimus treatment at 0.5 and 1.0 mg/kg doses reduced the increased expression of CaN protein by 38.0 and 73.2%, respectively. Histologically there was a marked accumulation of ED-1+ cells (macrophages) in diabetic kidneys and tacrolimus treatment failed to inhibit it. In contrast, tacrolimus treatment at 0.5 and 1.0 mg/kg doses significantly inhibited the elevated ED-1+/PCNA+ cells and ED-1+/iNOS+ cells in the kidneys of diabetic rats, while tacrolimus treatment at a dose of 0.5 or 1.0 mg/kg significantly suppressed the increased ED-1+/TLR2+ cells, ED-1+/TLR4+ cells and ED-1+/NF-κB-p-p65+ cells in the kidneys of diabetic rats.

CONCLUSION

The data from the current study demonstrated that tacrolimus could ameliorate early renal injury through a mechanism to suppress macrophage activation.

Study of mizoribine therapy in elderly patients with membranous nephropathy: comparison with patients not receiving mizoribine

BACKGROUND

We have previously reported the results of mizoribine (MZR) treatment for elderly patients with membranous nephropathy (MN). Here, we retrospectively compared these patients with those who had been initially treated with prednisolone (PSL) alone.

METHODS

The subjects were patients with MN aged ≥65 years who were examined between April 2007 and September 2010 and followed for at least 1 year.

RESULTS

The median period until the start of treatment in the MZR group (MZR-G) was 60 days. The urinary protein level at the start of MZR treatment was 3.89±2.3 g/gCr. Urinary protein in the group not treated with MZR (N-MZR-G) was 1.0±1.1 g/gCr, showing a tendency to improve in patients with nephrotic syndrome relative to the MZR-G (p=0.055). The PSL dose in the MZR-G versus N-MZR-G at 1 year was 5.7±3.0 versus 6.25±2.5 mg/day, the urinary protein level was 0.19±0.2 versus 0.13±0.1 g/gCr, and the remission rate was 80 versus 75%. In the MZR-G, the total PSL dose at 1 year after the start of MZR treatment was 5,058±1,904 versus 6,649±875 mg in the N-MZR-G. Adverse events occurred in 3/5 patients (60%) in the MZR-G and in 3/4 patients (75%) in the N-MZR-G.

CONCLUSION

Elderly patients with MN who respond poorly to PSL treatment may be treated successfully with MZR.

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.

H2S, a novel therapeutic target in renal-associated diseases?

For more than a century, hydrogen sulfide (H2S) has been regarded as a toxic gas. Recently, the understanding of the biological effects of H2S has been changed. This review surveys the growing recognition of H2S as an endogenous signaling molecule in mammals, with emphasis on its physiological and pathological pathways in the urinary system. This article reviews recent progress of basic and pharmacological researches related to endogenous H2S in urinary system, including the regulatory effects of H2S in the process of antioxidant, inflammation, cellular matrix remodeling and ion channels, and the role of endogenous H2S pathway in the pathogenesis of renal and urogenital disorders.

IgG4-Related Tubulointerstitial Nephritis Associated with Membranous Nephropathy in Two Patients: Remission after Administering a Combination of Steroid and Mizoribine

We report two cases of Japanese men who presented with proteinuria, eosinophilia, hypocomplementemia, and high serum immunoglobulin G4 (IgG4) concentration and were diagnosed with membranous nephropathy associated with IgG4-related tubulointerstitial nephritis on renal biopsy. The typical renal lesions of IgG4-related disease are tubulointerstitial nephritis, which improves remarkably with steroid therapy, and occasional glomerular changes. In our two cases, renal biopsy revealed IgG4-positive immune complex deposits in glomeruli in a pattern of membranous nephropathy and concurrent tubulointerstitial nephritis with IgG4 plasma cells. In both cases, proteinuria persisted with initial prednisolone treatment and was resolved only after the addition of mizoribine. We report the first two cases in which the combination of prednisolone and mizoribine was effective for treating membranous nephropathy associated with IgG4-related tubulointerstitial nephritis.

Mizoribine ameliorates renal injury and hypertension along with the attenuation of renal caspase-1 expression in aldosterone-salt-treated rats

Aldosterone-salt treatment induces not only hypertension but also extensive inflammation that contributes to fibrosis in the rat kidney. However, the mechanism underlying aldosterone-salt-induced renal inflammation remains unclear. Pyroptosis has recently been identified as a new type of cell death that is accompanied by the activation of inflammatory cytokines. We hypothesized that aldosterone-salt treatment could induce inflammation through pyroptosis and that mizoribine, an effective immunosuppressant, would ameliorate the renal inflammation that would otherwise cause renal fibrosis. Ten days after recovery from left uninephrectomy, rats were given drinking water with 1% sodium chloride. The animals were divided into three groups (n = 7 per group): (1) vehicle infusion group, (2) aldosterone infusion group, or (3) aldosterone infusion plus oral mizoribine group. Aldosterone-salt treatment increased the expression of the nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain containing 3 and caspase-1, and also increased the number of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells. However, the oral administration of mizoribine attenuated these alterations. Furthermore, mizoribine inhibited hypertension and renal fibrosis, and also attenuated the aldosterone-induced expression of serum/glucocorticoid-regulated kinase and α epithelial sodium channel. These results suggest that caspase-1 activation plays an important role in the development of inflammation induced by aldosterone-salt treatment and that it functions as an anti-inflammatory strategy that protects against renal injury and hypertension.

Targeting JNK by a new curcumin analog to inhibit NF-kB-mediated expression of cell adhesion molecules attenuates renal macrophage infiltration and injury in diabetic mice

Macrophage infiltration contributes to the pathogenesis of diabetic renal injury. However, the regulatory mechanisms between macrophage infiltration and epithelial cell activation are still unclear. Our previous study found that C66, a novel curcumin analog, was able to inhibit inflammatory cytokine expression in vitro and in vivo. This study further elucidated whether C66 can prevent glucose-induced renal epithelial activation and inflammatory macrophage infiltration by a MAPK/NF-κB medicated mechanism. Our data show that pretreatment with C66 not only significantly reduced high glucose (HG)-induced over-expressions of VCAM-1, ICAM-1 and MCP-1, but also remarkably inhibited NF-κB activation, MAPKs phosphorylation, and subsequently macrophage adhesion in renal epithelial NRK-52E cells. Furthermore, we find that MAPKs, especially JNK, play important roles in HG-induced NF-κB activation, which regulates the over-expression of adhesion molecules in HG-stimulated NRK-52E cells. A molecular docking predicted that C66 may target JNK2, which leads to its anti-inflammatory actions. In vivo, administration of C66 or JNK special inhibitor SP600125 at 5 mg/kg markedly decreased diabetes-induced renal adhesion molecule expression, NF-κB activation, inflammatory cell infiltration, and pathological indexes in the kidneys of diabetic mice. These findings provide a perspective on the renoprotective effects of C66 in diabetes, and outline a novel therapeutic strategy of JNK inhibition for the treatment of diabetic nephropathy.

Triptolide markedly attenuates albuminuria and podocyte injury in an animal model of diabetic nephropathy

Triptolide is a major active component of Tripterygium wilfordii Hook F, which exerts marked immunosuppressive, anti-inflammatory and podocyte-protective effects. In this study, the ability of triptolide to inhibit inflammation and attenuate podocyte injury was examined in a rat model of diabetic nephropathy (DN). Type II diabetic rats with DN were treated with triptolide at a dose of 100 μg.kg⁻¹.day⁻¹. Following 8 weeks of triptolide treatment, the urine albumin level, kidney weight/body weight and the number of cells positive for ED-1 (a marker for rat mononuclear macrophages) in the kidney were assessed. The effects of triptolide on podocyte injury and chronic inflammation were analyzed using quantitative polymerase chain reaction (qPCR), western blotting and immunohistochemistry. Following triptolide treatment, the albuminuria in the type II diabetic rats was significantly reduced. Furthermore, the glomerular hypertrophy and foot process effacement were improved, and there was a recovery of the slit diaphragm associated with nephrin and podocin expression. The inflammation in the kidneys was also attenuated. Furthermore, triptolide significantly reduced the expression of transforming growth factor-β1 and osteopontin, and the infiltration of ED-1-positive cells into the kidney. The results demonstrated that triptolide markedly attenuated albuminuria and podocyte injury in the rat model of DN, which may have been correlated with the inhibition of inflammation and macrophage infiltration in the kidneys.

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.

Gamma linolenic acid exerts anti-inflammatory and anti-fibrotic effects in diabetic nephropathy

PURPOSE

This study was undertaken to investigate the effects of gamma linolenic acid (GLA) on inflammation and extracellular matrix (ECM) synthesis in mesangial and tubular epithelial cells under diabetic conditions.

MATERIALS AND METHODS

Sprague-Dawley rats were intraperitoneally injected with either a diluent [n=16, control (C)] or streptozotocin [n=16, diabetes (DM)], and eight rats each from the control and diabetic groups were treated with evening primrose oil by gavage for three months. Rat mesangial cells and NRK-52E cells were exposed to medium containing 5.6 mM glucose and 30 mM glucose (HG), with or without GLA (10 or 100 μM). Intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein-1 (MCP-1), and fibronectin (FN) mRNA and protein expression levels were evaluated.

RESULTS

Twenty-four-hour urinary albumin excretion was significantly increased in DM compared to C rats, and GLA treatment significantly reduced albuminuria in DM rats. ICAM-1, MCP-1, FN mRNA and protein expression levels were significantly higher in DM than in C kidneys, and these increases were significantly abrogated by GLA treatment. In vitro, GLA significantly inhibited increases in MCP-1 mRNA expression and protein levels under high glucose conditions in HG-stimulated mesangial and tubular epithelial cells (p<0.05, respectively). ICAM-1 and FN expression showed a similar pattern to the expression of MCP-1.

CONCLUSION

GLA attenuates not only inflammation by inhibiting enhanced MCP-1 and ICAM-1 expression, but also ECM accumulation in diabetic nephropathy.

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.

Inflammation in diabetic nephropathy

Diabetic nephropathy is the leading cause of end-stage kidney disease worldwide but current treatments remain suboptimal. This review examines the evidence for inflammation in the development and progression of diabetic nephropathy in both experimental and human diabetes, and provides an update on recent novel experimental approaches targeting inflammation and the lessons we have learned from these approaches. We highlight the important role of inflammatory cells in the kidney, particularly infiltrating macrophages, T-lymphocytes and the subpopulation of regulatory T cells. The possible link between immune deposition and diabetic nephropathy is explored, along with the recently described immune complexes of anti-oxidized low-density lipoproteins. We also briefly discuss some of the major inflammatory cytokines involved in the pathogenesis of diabetic nephropathy, including the role of adipokines. Lastly, we present the latest data on the pathogenic role of the stress-activated protein kinases in diabetic nephropathy, from studies on the p38 mitogen activated protein kinase and the c-Jun amino terminal kinase cell signalling pathways. The genetic and pharmacological approaches which reduce inflammation in diabetic nephropathy have not only enhanced our understanding of the pathophysiology of the disease but shown promise as potential therapeutic strategies.

Proinflammatory CD14+CD16+ monocytes are associated with microinflammation in patients with type 2 diabetes mellitus and diabetic nephropathy uremia

Diabetic nephropathy (DN) is a major cause of type 2 diabetes mellitus (T2DM) mortality. Innate immunity has been shown to be closely associated with the occurrence and progression of T2DM-associated complications. In this study, we investigated the expression of Toll-like receptor 4 (TLR4) and CD14(+)CD16(+) monocytes in patients with T2DM and DN patients with uremia and TLR4 response to lipopolysaccharide (LPS), and to further explore the potential effects of inflammatory immune response in T2DM and DN uremia. Thirty DN patients with uremia, 28 T2DM patients, and 20 healthy volunteers were enrolled for the determination of CD14(+)CD16(+) fluorescence intensity and TLR4 expression on monocytes by using peripheral blood flow cytometry. Serum C-reactive protein (CRP) level was determined by using the immunoturbidimetry. Peripheral blood mononuclear cells (PBMCs) were isolated and stimulated with LPS for 24 h. monocytes were collected to detect NF-κB p65 and phosphorylated STAT5(p-STAT5) expressions by using Western blotting. Supernatants were sampled for the determination of interleukin-6 (IL-6) concentration by using ELISA. Compared to normal control, T2DM patients and DN uremic patients had a significantly higher CD14(+)CD16(+) fluorescence intensity, TLR4 expression, serum IL-6 and CRP level, whilst these biomarkers were more upregulated in DN uremic patients than in T2DM patients. Following the exposure to LPS, PBMCs showed a significant upregulation in NF-κB-p65 and p-STAT5 expression and a remarked increase in Supernatants IL-6 level, in a positive correlation with disease severity. Our results suggest that the disturbance in proinflammatory CD14(+)CD16(+) monocytes occurs in T2DM and DN uremic patients. Such immunological dysfunction may be related to the activation of TLR4/NF-κB and STAT5 signaling pathways underlying the immune abnormalities of CD14(+)CD16(+) monocytes.

Monocyte Chemoattractant Protein 1 (MCP-1) in obesity and diabetes

Monocyte Chemoattractant Protein-1 (MCP-1) is the first discovered and most extensively studied CC chemokine, and the amount of studies on its role in the etiologies of obesity- and diabetes-related diseases have increased exponentially during the past two decades. This review attempted to provide a panoramic perspective of the history, regulatory mechanisms, functions, and therapeutic strategies of this chemokine. The highlights of this review include the roles of MCP-1 in the development of obesity, diabetes, cardiovascular diseases, insulitis, diabetic nephropathy, and diabetic retinopathy. Therapies that specifically or non-specifically inhibit MCP-1 overproduction have been summarized.

Serum allograft inflammatory factor-1 is a novel marker for diabetic nephropathy

AIMS

Recent studies have identified macrophage-mediated injury as an important component in the development of diabetic nephropathy. The aim of this study was to investigate the correlations between serum allograft inflammatory factor-1 (AIF-1) concentration, which is a marker of activated macrophages, and diabetic nephropathy.

METHODS

Serum AIF-1 concentrations were measured in 284 patients with type 2 diabetes. We evaluated relationships of serum AIF-1 concentrations to degree of urinary albumin excretion (UAE) or estimated glomerular filtration rate (eGFR) in univariate and multivariate linear regression analyses.

RESULTS

Serum AIF-1 concentrations positively correlated with logarithm of UAE (r=0.260, P<0.0001), whereas serum AIF-1 concentrations inversely correlated with eGFR (r=-0.312, P<0.0001). Mean serum AIF-1 concentration was higher in patients with macroalbuminuria than that in patients with normoalbuminuria (P=0.0001) or that in patients with microalbuminuria (P=0.0093). In multivariate linear regression analyses, serum AIF-1 concentrations were independently correlated with logarithm of UAE (β=0.213, P=0.0120) and with eGFR (β=-0.286, P=0.0011).

CONCLUSIONS

Serum AIF-1 concentration correlated with albuminuria and eGFR in patients with type 2 diabetes and it could be a marker of diabetic nephropathy as well as activated macrophages.

Mizoribine provides effective treatment of sequential histological change of arteritis and reduction of inflammatory cytokines and chemokines in an animal model of Kawasaki disease

The incidence of panvasculitis in the coronary arteries and aortic root was 100% in the control group. The incidence of panvasculitis in the MZR group decreased to 50%. Moreover, the scope and severity of the inflammation of those sites were significantly reduced in the MZR group as well as the IgG group. On the other hand, increased cytokines and chemokines, such as IL-1α, TNF-α, KC, MIP-1α, GM-CSF, and IL-13, in the nontreatment group were significantly suppressed by treatment with MZR, but the MCP-1 level increased. In addition, IL-1α, TNF-α, IL-10, IL-13, and MIP-1α were suppressed by treatment in the IgG group.

BACKGROUND

Intravenous immunoglobulin (IVIg) treatment results in an effective response from patients with acute-phase Kawasaki disease (KD), but 16.5% of them remain nonresponsive to IVIg. To address this therapeutic challenge, we tried a new therapeutic drug, mizoribine (MZR), in a mouse model of KD, which we have established using injections of Candida albicans water-soluble fractions (CAWS).

METHODS

CAWS (4 mg/mouse) were injected intraperitoneally into C57BL/6N mice for 5 consecutive days. MZR or IgG was administered for 5 days. After 4 weeks, the mice were sacrificed and autopsied, the hearts were fixed in 10% neutral formalin, and plasma was taken to measure cytokines and chemokines using the Bio-Plex system.

RESULTS

The incidence of panvasculitis in the coronary arteries and aortic root was 100% in the control group. The incidence of panvasculitis in the MZR group decreased to 50%. Moreover, the scope and severity of the inflammation of those sites were significantly reduced in the MZR group as well as the IgG group. On the other hand, increased cytokines and chemokines, such as IL-1α TNF-α, KC, MIP-1α, GM-CSF, and IL-13, in the nontreatment group were significantly suppressed by treatment with MZR, but the MCP-1 level increased. In addition, IL-1α, TNF-α, IL-10, IL-13, and MIP-1α were suppressed by treatment in the IgG group.

CONCLUSION

MZR treatment suppressed not only the incidence, range, and degree of vasculitis, but also inflammatory cytokines and chemokines in the plasma of the KD vasculitis model mice, suggesting that MZR may be useful for treatment of KD.

FK506 ameliorates renal injury in early experimental diabetic rats induced by streptozotocin

Calcineurin (CaN) plays an important role in glomerular hypertrophy and extracellular matrix accumulation in early diabetic nephropathy. Cyclosporine (CSA), a CaN inhibitor, has been shown to reduce renal injury in streptozotocin-induced diabetic rats. We examined whether FK506, which immunosuppressive action was 10-100 times of CSA, inhibits progression of diabetic nephropathy in experimental diabetic rats. Diabetes was induced with streptozotocin in rats, and FK506 (0.5 or 1.0mg/kg) was orally administered once a day for 4 weeks. Increased relative kidney weight was significantly reduced by FK506 treatment with 1.0mg/kg (p<0.05), and elevated 24 hour urinary albumin excretion rate was markedly attenuated by FK506 treatment with 0.5 and 1.0mg/kg (p<0.05, 0.01). Elevated glomerular volume was significantly attenuated by FK506 treatment with 0.5 and 1.0mg/kg (p<0.05), and increased indices for tubulointerstitial injury were only ameliorated by FK506 treatment with 1.0mg/kg (p<0.01). Western blot analysis noted that the expression of CaN protein was increased 2.4 fold in the kidney from diabetic rats, and FK506 treatment with 0.5 and 1.0mg/kg could reduce increased expression of CaN protein by 38.0% and 73.2%. The expression of 1α (IV) collagen, p65, p-p65, OPN, α-SMA and TGF-β1 protein in kidney was significantly increased in diabetic rats and reduced by FK506 treatment (p<0.05, 0.01). Our results show that FK506 could ameliorate renal injury in early experimental diabetic rats, which mechanism may be at least partly correlated with suppression on increased CaN in renal tissue in diabetic rats.

Keishibukuryogan reduces renal injury in the early stage of renal failure in the remnant kidney model

The effects of keishibukuryogan on the early stage of progressive renal failure were examined in rats subjected to 5/6 nephrectomy. Keishibukuryogan, one of the traditional herbal formulations, was given orally at a dose of 1% (w/w) and 3% (w/w) in chow. Administration of keishibukuryogan was started at 1 week after 5/6 nephrectomy and was continued for 4 weeks. At the end of the experiment, Azan staining did not reveal any severe histological changes in the kidneys of the nephrectomized rats. On the other hand, significant increases in mRNA expressions of transforming growth factor-β₁ and fibronectin related to tissue fibrosis, as examined by Reverse Transcriptase-Polymerase Chain Reaction, were observed in nephrectomized rats, and they were significantly suppressed by 3% keishibukuryogan treatment. Against gene expressions related to macrophage infiltration, 3% keishibukuryogan treatment significantly suppressed osteopontin mRNA levels, and monocyte chemoattractant protein-1 and vascular cell adhesion molecule-1 mRNA levels showed a tendency to decrease, but without statistical significance. It was also observed that 3% keishibukuryogan attenuated serum urea nitrogen and urinary protein excretion levels. From these results, it was suggested that keishibukuryogan exerts beneficial effects that result in slowing the progression of chronic renal failure.

Long-term diabetic complications may be ameliorated by targeting Rho kinase

This review addresses the roles of Rho/Rho-kinase (ROCK) pathway in the pathogenesis of diabetes complications. Diabetes can cause many serious complications and can result in physical disability or even increased mortality. However, there are not many effective ways to treat these complications. The small guanosine-5'-triphosphate-binding protein Rho and its downstream target Rho-kinase mediate important cellular functions, such as cell morphology, motility, secretion, proliferation, and gene expression. Recently, the Rho/Rho-kinase pathway has attracted a great deal of attention in diabetes-related research. These studies have provided evidence that the activity and gene expression of Rho-kinase are upregulated in some tissues in animal models of type 1 or type 2 diabetes and in cell lines cultured with high concentrations of glucose. Inhibitors of Rho-kinase could prevent or ameliorate the pathological changes in diabetic complications. The inhibitory effects of statins on the Rho/Rho-kinase signalling pathway may also play a role in the prevention of diabetic complications. However, the precise molecular mechanism by which the Rho/Roh-kinase pathway participates in the development or progression of diabetic complications has not been extensively investigated. This article evaluates the relationship between Rho/Roh-kinase activation and diabetic complications, as well as the roles of Roh-kinase inhibitors and statins in the complications of diabetes, with the objective of providing a novel target for the treatment of long-term diabetic complications.

Hydrochloride pioglitazone decreases urinary monocyte chemoattractant protein-1 excretion in type 2 diabetics

AIM

To observe the effects of hydrochloride pioglitazone on monocyte chemoattractant protein-1 (MCP-1) excretion in type 2 diabetics and explore its reno-protective mechanism.

METHODS

98 uncontrolled type 2 diabetics with fasting blood glucose (FBG) between 7.0 and 13.0 mmol/L and glycated hemoglobin A1c (HbA1c)> or =7.0% were assigned randomly into group DP (pioglitazone add-on) and group DS (sulfonylureas add-on). Another 49 healthy individuals were chosen as normal controls (group NC). At the basal and 12th week, FBG, HbA1c, urinary MCP-1, albumin (UALB) and creatinine (UCr) were determined.

RESULTS

(1) Compared with group NC, all the parameters mentioned above were significantly increased in diabetic groups. (2) Compared with pre-treatment, FBG, HbA1c and urinary MCP-1/UCr ratio (UMCR) were obviously decreased in both therapy groups; systolic blood pressure (SBP), diastolic blood pressure (DBP) and UALB/UCr ratio (UACR) decreased markedly in group DP (P<0.05 or P<0.01), while slightly in group DS (P>0.05). (3) FBG and HbA1c had no marked difference between group DP and group DS after treatment, however, SBP, DBP, UACR and UMCR in group DP were significantly lower than those in group DS (P<0.05 or P<0.01).

CONCLUSIONS

Pioglitazone can decrease urinary albumin and MCP-1 excretion in type 2 diabetics, which may partly contribute to its reno-protection by inhibiting the inflammation reaction in vivo.

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.

Hydrogen sulfide regulates homocysteine-mediated glomerulosclerosis

BACKGROUND/AIMS

In this study we tested the hypothesis that H(2)S regulates collagen deposition, matrix metalloproteinases (MMP) and inflammatory molecules during hyperhomocysteinemia (HHcy) resulting in attenuation of glomerulosclerosis and improved renal function.

MATERIALS AND METHODS

A genetic model of HHcy, cystathionine beta-synthase heterozygous (CBS+/-) and wild-type (WT) 2-kidney (2K) mice were used in this study and supplemented with or without NaHS (30 micromol/l, H(2)S donor) in drinking water for 8 weeks. To expedite the renal damage associated with HHcy, uninephrectomized (1K) mice of similar groups were also used.

RESULTS

Results demonstrated that NAD(P)H oxidase (p47(phox)subunit) and blood pressure were upregulated in WT 1K, CBS+/- 2K and CBS+/- 1K mice with downregulation of H(2)S production and reduced glomerular filtration rate. These changes were normalized with H(2)S supplementation. Both pro- and active MMP-2 and -9 and collagen protein expressions and glomerular depositions were also upregulated in WT 1K, CBS+/- 2K and CBS+/- 1K mice. Increased expressions of inflammatory molecules, intercellular cell adhesion molecule-1 and vascular cell adhesion molecule-1, as well as increased macrophage infiltration, were detected in WT 1K, CBS+/- 2K and CBS+/- 1K mice. These changes were ameliorated with H(2)S supplementation.

CONCLUSION

Together, these results suggest that increased oxidative stress and decreased H(2)S in HHcy causes matrix remodeling and inflammation resulting in glomerulosclerosis and reduced renal function.

Rosiglitazone protects diabetic rats against kidney disease through the suppression of renal moncyte chemoattractant protein-1 expression

Although the pathogenetic mechanisms of diabetic nephropathy (DN) have not been elucidated thoroughly, an inflammatory mechanism has been suggested to contribute to its development and progression. Moncyte chemoattractant protein (MCP)-1 is a chemokine that can attract macrophages and T cells from the circulation to the local kidney, then activate them, and ultimately injure the renal tissue. Recent studies have demonstrated that thiazolidinediones decrease urinary albumin (ALB) excretion, which may be partly related to its anti-inflammatory action. Therefore, the effects of rosiglitazone on renal inflammation and renal injury were investigated in streptozotocin (STZ)-induced diabetic rats in this study. We examined the urinary excretion rates of ALB, retinal-binding protein (RBP), and MCP-1 of normal control group (Group C, n=8), STZ-induced diabetes mellitus group (Group D, n=8), and diabetes plus rosiglitazone (5 mg x kg-1 x day-1) treatment group (Group R, n=8) at the eighth week. The renal tissues of diabetic rats were obtained for reverse transcriptase-polymerase chain reaction to examine the expression of MCP-1 mRNA. Our results showed that compared to normal control, urinary excretion rates of ALB, RBP, and MCP-1 were significantly increased in untreated diabetic rats at the eighth week. However, rosiglitazone treatment could markedly decrease all the parameters above. In addition, urinary excretion rate of MCP-1 showed positive correlations with urinary ALB excretion, urinary RBP excretion, and kidney/body weight. The expressions of MCP-1 mRNA in renal tissues were markedly up-regulated in untreated diabetic rats, and these could be notably reduced by rosiglitazone treatment. In conclusion, rosiglitazone may have a potential therapeutic target in DN, which may be partly attributed to lowering of the expression of MCP-1 in the local kidney and the urinary excretion of MCP-1.

Structural and functional changes in the kidneys of high-fat diet-induced obese mice

Metabolic syndrome has been reported to be associated with chronic kidney disease, but the mechanisms remain unclear. Although feeding of a high-fat diet (HFD) to C57BL/6 mice is reported to induce systemic metabolic abnormalities and subsequent renal injuries, such as albuminuria, similar to human metabolic syndrome, alterations in HFD-induced renal injuries have not been fully elucidated in detail. We therefore investigated the structural and functional changes in the kidneys of C57BL/6 mice on a HFD. Six-week-old mice were fed a low-fat diet (LFD; 10% of total calories from fat) or a HFD (60% fat) for 12 wk. Mice fed a HFD showed significant increases in body weight, systolic blood pressure, plasma insulin, glucose, and triglycerides compared with those on a LFD. Accompanying these systemic changes, mice on a HFD showed albuminuria, an increase in glomerular tuft area, and mesangial expansion. These systemic and renal alterations in mice on a HFD were prevented by body weight control with the dietary restriction of feeding a HFD. Furthermore, mice on a HFD showed renal pathophysiological alterations including renal lipid accumulation, an increased accumulation of type IV collagen in glomeruli, an increase in macrophage infiltration in the renal medulla, an increase in urinary 8-hydroxy-2'-deoxyguanosine excretion, and impaired sodium handling. In conclusion, this study suggests that local metabolic alterations in the kidney play important roles in the development of renal injury associated with metabolic syndrome in addition to systemic metabolic changes and an increase in body weight.

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.

Reduced albuminuria with sarpogrelate is accompanied by a decrease in monocyte chemoattractant protein-1 levels in type 2 diabetes

BACKGROUND AND OBJECTIVES

Sarpogrelate has been shown to reduce albuminuria in diabetic nephropathy. For examination of whether this is based on the same mechanisms as angiotensin II receptor blockers or thiazolidinedione, effects of sarpogrelate on atherosclerotic inflammatory molecules and their relations to albuminuria in patients who had diabetes and had already been treated with angiotensin II receptor blockers and with or without thiazolidinedione were examined.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Forty patients who had diabetes with nephropathy and arteriosclerosis obliterans and had already been treated with angiotensin II receptor blocker (n = 40) were randomly assigned to sarpogrelate (300 mg/d; n = 20) or aspirin group (100 mg/d; n = 20). Plasma monocyte chemoattractant protein-1 and urinary albumin-to-creatinine ratio and monocyte chemoattractant protein-1 were measured at baseline and 16 wk after administration.

RESULTS

Only the sarpogrelate group showed increases in plasma adiponectin and decreases in both plasma and urinary monocyte chemoattractant protein-1 and albumin-to-creatinine ratio levels. Moreover, percentage change of monocyte chemoattractant protein-1 level correlated positively to that of albumin-to-creatinine ratio. Even when the sarpogrelate group was further divided into two groups with (n = 9) or without thiazolidinedione (n = 11), changes in monocyte chemoattractant protein-1 or albumin-to-creatinine ratio did not differ.

CONCLUSIONS

Sarpogrelate can reduce albuminuria and plasma and urinary monocyte chemoattractant protein-1 levels while increasing plasma adiponectin in diabetic nephropathy. These effects seem to be mediated via mechanisms that are different from those of angiotensin II receptor blocker or thiazolidinedione.

Pravastatin Inhibits Carboxymethyllysine-Induced Monocyte Chemoattractant Protein 1 Expression in Podocytes via Prevention of Signalling Events

BACKGROUND

Up-regulation of local monocyte chemoattractant protein 1 (MCP-1) production is involved in glomerular damage through macrophage recruitment and activation in diabetic nephropathy. Advanced glycation end-products induced chemokine production in cultured mesangial cells and podocytes. Statins prevented recruitment of macrophages to the glomeruli, suggesting that statins may have the ability of anti-inflammation. In the present studies, we investigated the effects of pravastatin in the carboxymethyllysine (CML)-induced MCP-1 expression in mouse differentiated podocytes.

METHODS

MCP-1 gene and protein expressions were examined using RT-PCR and ELISA. Dichlorofluorescein-sensitive intracellular reactive oxygen species (ROS) generation was measured by confocal microscopy. Activation of extracellular signal-regulated kinase (ERK), nuclear factor (NF) kappaB and Sp1 were studied using Western blotting and immunocytochemistry.

RESULTS

MCP-1 was induced by CML in a time- and dose-dependent manner. CML-induced MCP-1 mRNA and protein production were inhibited by 0.1 or 1 mM pravastatin. CML rapidly generated intracellular ROS in podocytes. Pravastatin did not have any ability of blocking ROS generation. Phosphorylated ERK was found in podocytes incubated with CML and was prevented by pravastatin in a dose-dependent manner. Both Western blotting and immunocytochemistry results suggested that pretreatment of podocytes with pravastatin prevented the CML-induced NF-kappaB and Sp1 translocation.

CONCLUSION

These results suggest that pravastatin prevents CML to induce MCP-1 expression in podocytes via modulation of the intracellular ERK/NF-kappaB and Sp1 signalling pathway.

The Monocyte Chemotactic Protein-1 Gene May Contribute to Hypertension in Dahl Salt-Sensitive Rats

In a previous study, we performed a genome-wide quantitative trait loci (QTLs) analysis for blood pressure using F2 rats derived from Dahl salt-sensitive (DS) and Lewis (LEW) rats and identified two QTLs that influenced blood pressure levels. Although we determined that one of the causative genes in the chromosome (Ch) 1 region seemed to be Klk1, we did not perform detailed analyses on the Ch10 QTL region. The purpose of the present study was to identify candidate genes that influence blood pressure in the Ch10 QTL region. Using microarray analysis, we compiled a list of the genes that are differentially expressed between the two strains and that were localized to the Ch10 QTL region. Subsequent reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis identified that, while the expression levels of Ccl2 mRNA were not different between the kidneys of DS and LEW rats fed a normal diet, those in DS were 10-fold higher than those in LEW under a high-salt diet. Although the promoter reporter assay failed to identify causative nucleotide changes that led to the differential expression, monocyte chemotactic protein-1 (MCP-1) release from isolated monocytes were significantly higher in DS than in LEW. Intriguingly, this Ch10 QTL for blood pressure was also a possible QTL for urinary albumin excretion. Since Ccl2 is well known to be involved in various types of renal injury, it is likely that a higher expression of Ccl2 might aggravate macrophage infiltration, which in turn could aggravate tubulointerstitial injury, and thereby accelerate salt-sensitive hypertension. Thus, Ccl2 appears to be a interesting candidate gene for salt-sensitive hypertension in DS.

Combined MMF and insulin therapy prevents renal injury in experimental diabetic rats

Conventional therapies for diabetic mellitus are not effective in preventing the progression from early diabetic nephropathy (DN) to end-stage renal disease. The role of inflammation in the pathogenesis of DN has been implicated both clinically and experimentally, which provides an alternative therapeutic target for DN. Anti-inflammatory impact of mycophenolate mofetil (MMF) alone and in combination with insulin had been observed in a rat model of experimental DN. In this study, the diabetic rats were subjected to different treatments. Compared to control, the expression levels of CD68, NGF, and NF-kappaB p65, as determined immunohistochemically, were elevated in diabetic rats. Treatment with combined MMF/insulin is associated with a significant reduction in renal tissue of NGF and NF-kappaB p65 expression, macrophage infiltration. It also partially improved the renal function and attenuated renal hypertrophy at early stage of DN. CD68 was found to positively correlate with urinary albumin excretion and NGF. The combined use of MMF/insulin seemed to offer more protections in rats with experimental diabetic renal injury, and the protective effects of MMF might be due to its anti-inflammatory actions through inhibition of NF-kappaB activation and reduction of T cells and macrophage infiltration and/or other kidney chemokine productions.

Macrophage accumulation in human progressive diabetic nephropathy

BACKGROUND

Diabetic nephropathy is a major global health problem. Progression to renal failure is common; however, the mechanisms are unknown. Experimental models suggest a role for macrophages. Therefore, macrophage accumulation and its relationship to the subsequent clinical course were studied.

METHODS

A retrospective study of baseline histology and the subsequent clinical course over at least 5 years involving 20 consecutive patients with a histological and clinical diagnosis of diabetic nephropathy was performed. The relationship between macrophage accumulation in renal biopsy tissue (KP-1/anti-CD68+ cells), baseline measures of known predictors of progression (proteinuria, tubulointerstitial damage, myofibroblast accumulation) and progression over 5 years (plot of reciprocal of serum creatinine) was quantified.

RESULTS

Accumulation of macrophages was apparent in the glomeruli (2.8 + 0.7/gcs vs 1.0 + 0.2 for normals, P = not significant) and interstitium (296.9 + 63.3/mm(2) vs 19.0 + 1.3/mm(2) for normals, P = 0.002) of patients with diabetic nephropathy. Glomerular macrophage number correlated with baseline serum creatinine (r = 0.548, P = 0.012) but not with progression of renal failure as glomerular macrophages were prevalent in early, but not advanced diabetic nephropathy. Interstitial macrophage accumulation correlated strongly with serum creatinine (r = 0.649, P = 0.002), proteinuria (r = 0.779, P < 0.0001), interstitial fibrosis (r = 0.774, P < 0.0001) and inversely with the slope of 1/serum creatinine (r = -0.531, P = 0.023).

CONCLUSION

Macrophages accumulate within glomeruli and the interstitium in diabetic nephropathy and the intensity of the interstitial infiltrate is proportional to the rate of subsequent decline in renal function. These human data support animal studies that suggest a pathogenic role for the macrophage in diabetic nephropathy.

Renoprotective Effect of Breviscapine through Suppression of Renal Macrophage Recruitment in Streptozotocin-Induced Diabetic Rats

BACKGROUND/AIMS

Experimental and clinical evidence has consistently demonstrated that renal macrophage infiltration is one of the most important events for the progression of diabetic nephropathy. Breviscapine is a flavonoid extracted from the Chinese herb Erigeron breviscapus. Previously, it was shown that treatment with breviscapine attenuated renal injury in the diabetic rats. The purpose of this study is to investigate whether the renoprotective effect of breviscapine is through suppression of renal macrophage recruitment in diabetic rats.

METHODS

Diabetes was induced bystreptozotocin injection, and breviscapine was administered orally at a dose of 20 mg/kg/day for 8 weeks. Control rats received vehicle or breviscapine with the same schedule.

RESULTS

Breviscapine treatment markedly inhibited both an increase of albuminuria and glomeruli hypertrophy and tubulointerstitial injury without modifying mean arterial blood pressure and creatinine clearance. Levels of malondialdehyde and protein kinase C activities were markedly higher and antioxidant enzyme activities such as superoxide dismutase, catalase as well as glutathione peroxidase were significantly lower in the kidneys of diabetic rats than of the control group, breviscapine administration markedly remitted these changes. ED-1-positive cells and expression of intercellular adhesion molecule-1 (ICAM-1) and monocyte chemoattractant protein-1 (MCP-1) in glomeruli and tubulointerstitium were all markedly elevated but were significantly reduced by breviscapine. Western blot analysis noted that the expression of transforming growth factor beta1 protein was increased 1.8-fold in the kidney in diabetic rats, breviscapine treatment could reduce increased expression of TGF-beta1 protein by 47%.

CONCLUSION

This study describes a novel mechanism by which breviscapine confers a renoprotective effect.

Spironolactone prevents diabetic nephropathy through an anti-inflammatory mechanism in type 2 diabetic rats

Aldosterone induces myocardial fibrosis and vascular inflammation via proinflammatory and profibrotic cytokines. The effect of spironolactone on renal inflammation and renal function was investigated in type 2 diabetic rats. For define the molecular mechanism of spironolactone, the effect of spironolactone on the synthesis of monocyte chemotactic peptide-1 (MCP-1) and its upstream transcription factor, NF-kappaB, was evaluated in cultured mesangial cells and proximal tubular cells. There were no changes in blood glucose concentration or BP after spironolactone treatment. Spironolactone treatment significantly reduced urinary albumin excretion and ameliorated glomerulosclerosis. Urinary levels of MCP-1 were significantly increased concurrently with renal expression of MCP-1, macrophage migration inhibitory factor, and macrophage infiltration. Spironolactone treatment significantly inhibited urinary excretion of MCP-1 as well as renal MCP-1 and migration inhibitory factor expression and macrophage infiltration. In addition, aldosterone induced upregulation of MCP-1 expression and NF-kappaB transcriptional activity in cultured cells, and spironolactone reduced both NF-kappaB activation and MCP-1 synthesis. Furthermore, NF-kappaB inhibition abolished aldosterone-induced MCP-1 production. Overall, these findings suggest that aldosterone-induced NF-kappaB activation leads to activation of proinflammatory cytokines, ultimately leading to renal injury in this model. These data suggest that mineralocorticoid blockade may be a potential therapeutic target in diabetic nephropathy.