Kazuaki Shimizu

MCP-1/CCR2-dependent loop for fibrogenesis in human peripheral CD14-positive monocytes.

Monocyte/macrophage (Mο) migration to sites of inflammation is a prerequisite cause of organ fibrosis. The recruitment and activation of Mo are regulated by C‐C chemokines, especially monocyte chemoattractant protein‐1 [(MCP‐1)/CC chemokine ligand 2], which interacts with CC chemokine receptor 2 (CCR2). However, the mechanisms leading to fibrosis via MCP‐1/CCR2 signaling in Mo remain to be investigated. The effect of MCP‐1 on the expression of MCP‐1, CCR2, transforming growth factor‐β1 (TGF‐β1), and type I collagen in circulating human CD14‐positive Mo was investigated. In addition, the impact of MCP‐1‐specific or TGF‐β1‐specific antisense (AS) phosphorothioate oligodeoxynucleotides (ODN) was examined to explore the involvement of autocrine/paracrine production of MCP‐1 and TGF‐β1 by human CD14‐positive Mo. Furthermore, specific CCR2 inhibitors were applied to examine the involvement of CCR2 signaling for the promotion of a fibrogenic response. The stimulation of Mo with MCP‐1 increased mRNA levels of TGF‐β1 and a pro‐α1 chain of type I collagen (COL1A1) as well as protein synthesis. Similarly, the expression of MCP‐1 and CCR2 was enhanced by the stimulation with MCP‐1 in dose‐ and time‐dependent manners. This positive loop via MCP‐1 was reduced by pretreatment with MCP‐1‐specific AS‐ODN. It was also noted that pretreatment with TGF‐β1‐specific AS‐ODN partially reduced COL1A1 mRNA levels. Finally, transcripts of these molecules were suppressed by pretreatment with specific CCR2 inhibitors. The present study demonstrated that human peripheral CD14‐positive Mo contribute directly to fibrogenesis by a MCP‐1/CCR2‐dependent amplification loop. These data suggest that fibrogenic processes in Mo regulated by MCP‐1/CCR2 may be novel, therapeutic targets for combating organ fibrosis.

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.

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.

A chimeric CYP11B1/CYP11B2 gene in glucocorticoid-insuppressible familial hyperaldosteronism

Although a chimeric gene combining the 11β‐hydroxylase gene (CYP11B1) and the aldosterone synthase gene (CYP11B2) explains the pathophysiology of familial hyperaldosteronism (FH) type I, the contribution of this abnormality to FH type II has not been tested. We screened genomic DNA from a Japanese family with FH type II for the CYP11B1/CYP11B2 gene. The index patient was a 27‐year‐old woman with hypertension. Hypokalaemia, elevated plasma aldosterone and suppressed plasma renin activity suggested primary aldosteronism. Though computed tomography failed to reveal an adrenal tumour, left adrenalectomy was indicated due to a high aldosterone concentration in left adrenal venous blood. The resected adrenal gland contained an adenoma. As her mother had also been diagnosed with primary aldosteronism due to an adenoma, we administered oral dexamethasone to our patient before the operation and observed the response of the blood pressure and plasma aldosterone concentration for 2 weeks. Both parameters remained elevated during the treatment period, confirming the diagnosis of FH type II. Total DNA was isolated from blood cells of the index patient, her mother, and an unaffected brother. Samples were amplified by polymerase chain reaction using specific primers from CYP11B1 and CYP11B2. Unique DNA fragments of 1·4 kb were obtained from the index patient and her mother, but not from the healthy subject. The CYP11B1/CYP11B2 chimeric gene was found in a Japanese family with FH type II.

Unilateral Stent Implantation for Renal Function in Bilateral Atherosclerotic Renovascular Hypertension A Case Report

Renal artery stenting improves or preserves renal function in patients with bilateral renovas cular disease and chronic renal insufficiency. An 80-year-old male was admitted to the hospital for elevated blood pressure accompanied by congestive heart failure. He had renal insufficiency and severe hypertension secondary to bilateral atherosclerotic renal artery stenosis. Unilateral renal artery stenting in the left kidney resulted in the recovery of renal function, whereas renal artery stenting in the right kidney was technically difficult due to a tortuous aorta. After the left unilateral stent implantation, the serum creatinine concentration decreased from 2.0 to 1.3 mg/dL, and control of his blood pressure required fewer antihypertensive drugs, namely a calcium antagonist, an angiotensin-converting enzyme inhibitor, and diuretics. Fifteen months after stenting, renal scintigraphy demonstrated improved function of the right kidney, despite severe renal artery stenosis, as well as improved function of the left kidney. Renal angioplasty or stenting should be attempted in bilateral atherosclerotic renovascular hypertension with renal insufficiency, even though it may only be successful unilaterally.