Kiyoki Kitagawa

Blockade of CCR2 Ameliorates Progressive Fibrosis in Kidney

Fibrosis is a hallmark of progressive organ diseases. Monocyte chemoattractant protein (MCP)-1, also termed as macrophage chemotactic and activating factor (MCAF/CCL2) and its receptor, CCR2 are presumed to contribute to progressive fibrosis. However, the therapeutic efficacy of MCP-1/CCR2 blockade in progressive fibrosis remains to be investigated. We hypothesized that blockade of CCR2 may lead to the improvement of fibrosis. To achieve this goal, we investigated renal interstitial fibrosis induced by a unilateral ureteral obstruction in CCR2 gene-targeted mice and mice treated with propagermanium or RS-504393, CCR2 inhibitors. Cell infiltrations, most of which were F4/80-positive, were reduced in CCR2 knockout mice. In addition, dual staining revealed that CCR2-positive cells were mainly F4/80-positive macrophages. Importantly, CCR2 blockade reduced renal interstitial fibrosis relative to wild-type mice. Concomitantly, renal transcripts and protein of MCP-1, transforming growth factor-beta, and type I collagen were decreased in CCR2-null mice. Further, this CCR2-dependent loop for renal fibrosis was confirmed by treatment with CCR2 antagonists in a unilateral ureteral obstruction model. These findings suggest that the therapeutic strategy of blocking CCR2 may prove beneficial for progressive fibrosis via the decrease in infiltration and activation of macrophages in the diseased kidneys.

CCR2 Signaling Contributes to Ischemia-Reperfusion Injury in Kidney

Examined were CCR2-deficient mice to clarify the contribution of macrophages via monocyte chemoattractant protein 1 (MCP-1 or CCL2)/CCR2 signaling to the pathogenesis of renal ischemia-reperfusion injury. Also evaluated was the therapeutic effects via the inhibition of MCP-1/CCR2 signaling with propagermanium (3-oxygermylpropionic acid polymer) and RS-504393. Renal artery and vein of the left kidney were occluded with a vascular clamp for 60 min. A large number of infiltrated cells and marked acute tubular necrosis in outer medulla after renal ischemia-reperfusion injury was observed. Ischemia-reperfusion induced the expression of MCP-1 mRNA and protein in injured kidneys, followed by CCR2-positive macrophages in interstitium in wild-type mice. The expression of MCP-1 was decreased in CCR2-deficient mice compared with wild-type mice. The number of interstitial infiltrated macrophages was markedly smaller in the CCR2-deficient mice after ischemia-reperfusion. CCR2-deficient mice decreased the number of interstitial inducible nitric oxide synthase-positive cells after ischemia-reperfusion. The area of tubular necrosis in CCR2-deficient mice was significantly lower than that of wild-type mice after ischemia-reperfusion. In addition, CCR2-deficient mice diminished KC, macrophage inflammatory protein 2, epithelial cell-derived neutrophil-activating peptide 78, and neutrophil-activating peptide 2 expression compared with wild-type mice accompanied with the reduction of interstitial granulocyte infiltration. Similarly, propagermanium and RS-504393 reduced the number of interstitial infiltrated cells and tubular necrosis up to 96 h after ischemia-reperfusion injury. These results revealed that MCP-1 via CCR2 signaling plays a key role in the pathogenesis of renal ischemia-reperfusion injury through infiltration and activation of macrophages, and it offers a therapeutic target for ischemia-reperfusion.

Gene Therapy via Blockade of Monocyte Chemoattractant Protein-1 for Renal Fibrosis

Monocyte chemoattractant protein (MCP)-1, also termed monocyte chemotactic and activating factor (MCAF)/CCL2, plays an important role in progressive organ fibrosis. It was hypothesized that MCP-1, through its cognate receptor, CCR2, regulates the pathogenesis and is therapeutically of importance for renal fibrosis. To achieve this goal, the therapeutic efficacy and efficiency in renal fibrosis induced by a unilateral ureteral obstruction nephropathy model in mice by the blockade of MCP-1/CCR2 signaling was studied. The delivery of N-terminal deletion mutant of the human MCP-1 gene, 7ND, into a skeletal muscle ameliorated renal fibrosis by resulting in decrease in the deposit of type I collagen and in reduced expression of TGF-beta. Concomitantly, gene transfer of 7ND reduced the cell infiltration, most of which were CCR2-positive macrophages, followed by the decrease in MCP-1 expression in the diseased kidneys. These observations suggest that MCP-1 through CCR2 signaling is responsible for Mphi recruitment, which augments downstream events, resulting in renal fibrosis. Moreover, these findings imply that gene therapy against MCP-1/CCR2 signaling via the mutant gene transferred strategy may serve a beneficial therapeutic application for renal fibrosis.

Gene Therapy Expressing Amino-Terminal Truncated Monocyte Chemoattractant Protein-1 Prevents Renal Ischemia-Reperfusion Injury

Ischemia-reperfusion is closely associated with tissue damage in various organs, including kidney. Despite clinical investigations, useful therapy for renal ischemia-reperfusion injury is not available so far. This study evaluated therapeutic effects of gene therapy expressing an amino-terminal deletion mutant of MCP-1 called 7ND to inhibit monocyte chemoattractant protein (MCP)-1/CCR2 signaling in vivo on renal ischemia-reperfusion injury. 7ND gene was transferred into the femoral muscle of Balb/c mice. Renal artery and vein of the left kidney were occluded with a vascular clamp for 60 min. A large number of infiltrated cells were observed, as was marked acute tubular necrosis in outer medulla after renal ischemia-reperfusion injury in control mice, while these lesions were significantly decreased in 7ND gene-transfected mice. Macrophages in the interstitial region, most of which were CCR2-positive, were markedly decreased in 7ND gene-transfected mice after reperfusion. Although macrophages infiltrated around MCP-1-positive cells in control mice, the smaller number of F4/80-positive cells could infiltrate into the neighbor of MCP-1-positive cells in 7ND-treated mice. These results provide evidence that gene therapy by 7ND is potentially a powerful therapeutic approach to inhibit MCP-1/CCR2 signaling, resulting in rescue from renal ischemia-reperfusion injury.

Long-term Outcomes of Japanese Type 2 Diabetic Patients With Biopsy-Proven Diabetic Nephropathy

OBJECTIVE We evaluated the structural-functional relationships and the prognostic factors for renal events, cardiovascular events, and all-cause mortality in type 2 diabetic patients with biopsy-proven diabetic nephropathy. RESEARCH DESIGN AND METHODS Japanese type 2 diabetic patients with biopsy-proven diabetic nephropathy (n = 260) were enrolled. Patients were stratified by albuminuria (proteinuria) and estimated glomerular filtration rate (eGFR) at the time of renal biopsy. The outcomes were the first occurrence of renal events (requirement of dialysis or a 50% decline in eGFR from baseline), cardiovascular events (cardiovascular death, nonfatal myocardial infarction, coronary interventions, or nonfatal stroke), and all-cause mortality. RESULTS The factors associated with albuminuria (proteinuria) regardless of eGFR were hematuria, diabetic retinopathy, low hemoglobin, and glomerular lesions. The factors associated with low eGFR regardless of albuminuria (proteinuria) were age and diffuse, nodular, tubulointerstitial, and vascular lesions. The glomerular, tubulointerstitial, and vascular lesions in patients with normoalbuminuria (normal proteinuria) and low eGFR were more advanced compared to those in patients with normoalbuminuria (normal proteinuria) and maintained eGFR. In addition, compared to patients with micro-/macroalbuminuria (mild/severe proteinuria) and low eGFR, their tubulointerstitial and vascular lesions were similar or more advanced in contrast to glomerular lesions. The mean follow-up period was 8.1 years. There were 118 renal events, 62 cardiovascular events, and 45 deaths. The pathological determinants were glomerular lesions, interstitial fibrosis and tubular atrophy (IFTA), and arteriosclerosis for renal events, arteriosclerosis for cardiovascular events, and IFTA for all-cause mortality. The major clinical determinant for renal events and all-cause mortality was macroalbuminuria (severe proteinuria). CONCLUSIONS Our study suggests that the characteristic pathological lesions as well as macroalbuminuria (severe proteinuria) were closely related to the long-term outcomes of biopsy-proven diabetic nephropathy in type 2 diabetes.

Involvement of CD11b+ GR-1low cells in autoimmune disorder in MRL-Faslpr mouse

ObjectiveMyeloid-derived suppressor cells (MDSCs) have been identified as immunosuppressive cells in tumor-related inflammation. However, the pathogenesis of MDSCs for autoimmune disease has not been investigated as yet. The aim of this study was to address whether MDSCs contribute to autoimmune organ injury in lupus-prone mice.MethodsMDSCs were analyzed by flow cytometric staining of CD11b+ GR-1+ in MRL-Faslpr mice. CD4+ T-cell proliferation assay was performed by coculture with CD11b+ GR-1+ splenocytes. The percentage of immunosuppressive cells was examined during disease progression. Expression of chemokine receptor on immunosuppressive cells was analyzed, and chemotaxis assay was performed.ResultsCD11b+ GR-1low cells had a suppressive effect on CD4+ T-cell proliferation, which was restored by an arginase-1 inhibitor. CD11b+ GR-1low cells increased in percentage during disease progression in kidney and blood. The number of migrated CD11b+ GR-1low cells increased in the presence of monocyte chemoattractant protein-1/CCL2.ConclusionWe assessed the involvement of CD11b+ GR-1low cells in autoimmune disorder in MRL-Faslpr mice. These cells regulate immunological responses via CCL2/CCR2 signaling. The regulation of immunosuppressive monocytes may provide novel therapeutic strategy for organ damage in autoimmune diseases.

Blockade of IP-10/CXCR3 Promotes Progressive Renal Fibrosis

Background/Aim: Fibrosis is a hallmark of progressive organ disease. The 10-kDa interferon-inducible protein IP-10/CXCL10 is a potent chemoattractant for activated T lymphocytes, natural killer cells, and monocytes. However, the involvement of IP-10 in the pathogenesis of renal diseases viaits receptor, CXCR3, remains unclear. To contribute to the clarification of this issue was the aim of this study. Methods: The impacts of IP-10 on renal fibrosis were investigated in a unilateral ureteral obstruction model in CXCR3-deficient mice and mice treated with anti-IP-10-neutralizing monoclonal antibody. Anti-IP-10 monoclonal antibody (5 mg/kg/day) was injected intravenously once a day until sacrifice on days 1, 4, or 7 after treatment. The effects of IP-10 were confirmed in cultured tubular epithelial cells. Results: IP-10 and CXCR3 were upregulated in progressive renal fibrosis. Blockade of IP-10/CXCR3 promotes renal fibrosis, as evidenced by increases in interstitial fibrosis and hydroxyproline contents, concomitant decrease in hepatocyte growth factor expression, and converse increase in transforming growth factor-β1 in diseased kidneys. IP-10 blockade affected neither macrophage nor T cell infiltration in diseased kidneys. Conclusion: These results suggest that blockade of IP-10 via CXCR3 contributes to renal fibrosis, possibly by upregulation of transforming growth factor-β1, concomitant with downregulation of hepatocyte growth factor.

Matrix metalloproteinase-2 (MMP-2) and membrane-type 1 MMP (MT1-MMP) affect the remodeling of glomerulosclerosis in diabetic OLETF rats

BACKGROUND We reported previously that diabetic glomerular nodular-like lesions were formed during the reconstruction process of mesangiolysis. However, the precise mechanism has yet to be elucidated. Here, we investigated the roles of matrix metalloproteinase (MMP)-2, which is activated from proMMP-2 by membrane-type (MT)-MMP in the sclerotic and endothelial cell injury process of a type II diabetic model, Otsuka Long-Evans Tokushima Fatty (OLETF) rats. METHODS Monocrotaline (MCT) or saline only was injected three times every 4 weeks in 36-week-old OLETF rats and control Long-Evans Tokushima Otsuka rats. Glomerular expression and enzymatic activity of MMP-2 and MT1-MMP were assessed by immunohistochemistry, gelatin zymography of cultured glomerular supernatants, in situ enzymatic detection and reverse transcription-polymerase chain reaction. RESULTS Mesangial matrix increased in OLETF rats. In addition, mesangiolysis and nodular-like mesangial expansion were observed only in MCT-injected endothelial injured OLETF rats. MMP-2 and MT1-MMP proteins increased in the expanded mesangial lesions in OLETF rats. Gelatin zymography revealed an increase in 62-kDa activated MMP-2 in the culture supernatants of isolated glomeruli from OLETF rats. In situ enzymatic activity of MMP in the mesangial areas was also detected in 50-week-old MCT-injected OLETF rats. CONCLUSION These results suggest that MMP-2 and MT1-MMP are produced and activated in glomeruli through the progression of diabetic nephropathy and may have some effect on the remodeling of the glomerular matrix in diabetic nephropathy.

Fractalkine and its receptor, CX3CR1, promote hypertensive interstitial fibrosis in the kidney

Hypertension promotes and escalates kidney injury, including kidney fibrosis. Fractalkine/CX3CL1 is a unique chemokine that works as a leukocyte chemoattractant and an adhesion molecule. Recently, fractalkine/CX3CL1 has been reported to promote tissue fibrosis via its cognate receptor, CX3CR1. However, the involvement of the fractalkine-CX3CR1 axis in the pathogenesis of hypertensive kidney fibrosis remains unclear. The impacts of the fractalkine-CX3CR1 axis on hypertensive kidney fibrosis were investigated in a deoxycorticosterone acetate (DOCA)-salt hypertensive model in CX3CR1-deficient mice, which were sacrificed on day 28. The blood pressure levels were similarly elevated in both CX3CR1−/− C57BL/6 and wild-type C57BL/6 mice. Fractalkine and CX3CR1 were upregulated in kidneys that were damaged by hypertension. Deficiency in CX3CR1 inhibited kidney fibrosis, as evidenced by a decrease in the presence of interstitial fibrotic area detected by type I collagen in Mallory–Azan staining, concomitant with the downregulation of transforming growth factor (TGF)-β1 and type I procollagen mRNA expression in damaged kidneys. The CX3CR1 blockade also decreased the number of infiltrating F4/80-positive macrophages in damaged kidneys. These results suggest that the fractalkine-CX3CR1 axis contributes to kidney fibrosis in a hypertensive mouse model, possibly by the upregulation of macrophage infiltration and the expression of TGF-β1 and type I collagen.

Reduction in Chronic Allograft Nephropathy by Inhibition of p38 Mitogen-Activated Protein Kinase

Background: Chronic allograft nephropathy (CAN) is the major cause for late graft loss and is therefore a key target for therapy. Methods: The impact of p38 mitogen-activated kinase (MAPK) on CAN was investigated by administering FR167653 (32 mg/kg/day), a specific inhibitor of p38 MAPK, for 4 weeks in addition to conventional cyclosporine therapy (1.5 mg/kg/day for 5 days) in an established experimental rat transplantation model. Results: Transplanted rats develop glomerulosclerosis, arterial obliteration, interstitial fibrosis and tubular atrophy, all of which are characteristic of CAN, resulting in shortened survival on 32 weeks. However, the inhibition of p38 MAPK by daily subcutaneous treatment with FR167653 resulted in reduced CAN with preserved renal function and prolonged survival. The FR167653-treated rats had fewer phosphorylated p38 MAPK-positive cells in treated kidneys. Concomitantly, the expression of monocyte chemoattractant protein-1/CCL2 and transforming growth factor-β1 was markedly reduced. Conclusion: These results suggest that p38 MAPK phosphorylation is involved in the pathogenesis of CAN and provide evidence that p38 MAPK is a novel, appealing therapeutic target for combating CAN.