Takeo Sakuta

Involvement of the renin-angiotensin system in the development of vascular damage in a rat model of arthritis: effect of angiotensin receptor blockers.

OBJECTIVE To explore the involvement of the renin-angiotensin system (RAS) in the development of vascular damage in adjuvant-induced arthritis (AIA) in rats. METHODS Angiotensin II (Ang II; 0.25 or 1.0 mg/kg/day) was infused in control rats and rats with AIA for 21 days, and the impact of systemic inflammation on Ang II-induced hypertension, endothelial dysfunction, and vascular hypertrophy was evaluated. Expression of angiotensin II type 1 receptor (AT(1)R) and angiotensin-converting enzyme (ACE) in the aortas of rats with AIA were examined by real-time polymerase chain reaction (PCR) and Western blot analyses. Losartan (3 mg/kg/day) or irbesartan (5 mg/kg/day), both of which are AT(1)R blockers, was administered orally to rats with AIA for 21 days. In situ superoxide production in aortas was assessed according to the fluorogenic oxidation of dihydroethidium to ethidium. The expression and activity of NAD(P)H oxidases in aortas were examined by real-time PCR analysis and lucigenin chemiluminescence assay. Endothelial function in rats with AIA treated in vivo or ex vivo with AT(1)R blockers was also determined. RESULTS The Ang II-induced hypertensive response, endothelial dysfunction, and vascular hypertrophy were exacerbated in rats with AIA. Expression of AT(1)R and ACE was increased in the aortas of rats with AIA. Both losartan and irbesartan decreased the levels of superoxide and the expression and activity NAD(P)H oxidases in the aortas of rats with AIA. The endothelial dysfunction in AIA was improved by the in vivo or ex vivo treatment with AT(1)R blockers. CONCLUSION The locally activated RAS is involved in the increased vascular oxidative stress and endothelial dysfunction in AIA. Our findings have important implications for clinical approaches to the reduction of cardiovascular risk in patients with rheumatoid arthritis.

Renal denervation reduces glomerular injury by suppressing NAD(P)H oxidase activity in Dahl salt-sensitive rats

BACKGROUND Renal sympathetic nerve activity has important effects on renal function in chronic kidney disease. Recent studies indicated that beta agonists directly stimulate NAD(P)H oxidase in endothelial cells. Therefore, we investigated whether renal denervation protects renal function through an anti-oxidative effect. METHODS The right kidney was removed from Dahl salt-sensitive hypertensive rats. Two weeks later, the rats underwent either left renal denervation (Nx-RDNx; n = 10) or a sham operation (Nx-Sham; n = 10). After a further 6 weeks, kidney function and renal tissue were assessed. In this ex vivo study, using isolated glomeruli from Sprague-Dawley rats, the direct effects of catecholamine on NAD(P)H oxidase activity were assessed. RESULTS After the Nx-RDNx or Nx-Sham surgery, urinary albumin excretion and the histologic glomerular sclerosis index were lower in the Nx-RDNx group than in the Nx-Sham group. Fluorescence staining for reactive oxygen species in isolated glomeruli was significantly weaker in the Nx-RDNx group. A lucigenin assay of NAD(P)H oxidase activity in isolated glomeruli indicated that renal denervation may have caused the reduction in reactive oxygen species through suppression of the activity of NAD(P)H oxidase. The levels of mRNA for NAD(P)H oxidase components and the levels of rac1 were higher in glomeruli from the Nx-Sham group than from the Nx-RDNx group. In this ex vivo study, although the NAD(P)H oxidase activity did not change with administration of either the alpha- or beta2-agonist, it increased with the beta1-agonist. CONCLUSIONS Renal sympathetic denervation helps to protect against glomerular sclerosis, possibly by suppressing NAD(P)H oxidase activity, thereby decreasing glomerular reactive oxygen species.

Oral adsorbent AST-120 ameliorates endothelial dysfunction independent of renal function in rats with subtotal nephrectomy.

It is important to consider a strategy to halt the development of cardiovascular disease (CVD) in patients with chronic kidney disease (CKD). Oral adsorbent AST-120 retards deterioration in renal function, reducing indoxyl sulfate (IS) accumulation. The aim of this study was to determine whether AST-120 improves endothelial dysfunction by reducing oxidative/nitrative stress in a rat-CKD model. Subtotally nephrectomized (Nx) rats aged 17 weeks were divided into two groups: control rats and rats orally treated with AST-120. Two weeks after initiation of AST-120, serum and urinary IS levels, renal histological scores and endothelium-dependent vascular responses (EDVRs) in the aorta were investigated. EDVR in 5-h incubation with 250 μg ml−1 IS was also examined in normal rat aortas. Nitrotyrosine content, mRNA expression of p47phox, a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase component, and expression and phosphorylation (serine-1177) of endothelial nitric oxide synthase (eNOS) in the aorta were examined in untreated and treated Nx rats. At the end of treatment, renal function and histological scores were not different in the two groups. AST-120 prevented the elevation of serum IS level in Nx rats, reducing urinary IS excretion, and ameliorated decreased EDVR in Nx rats. Incubation with IS tended to reduce EDVR in normal aortas, albeit insignificantly. AST-120 also suppressed nitrotyrosine accumulation and inhibited p47phox expression in Nx rats. The eNOS expression and phosphorylation were similar in the two groups. In conclusion, AST-120 ameliorated endothelial dysfunction and alleviated oxidative/nitrative stress in the aorta through reduced accumulation of IS, independent of renal function, in a rat CKD model.

Tacrolimus induces glomerular injury via endothelial dysfunction caused by reactive oxygen species and inflammatory change.

Background/Aims: The immunosuppressive drug tacrolimus (FK506) is used clinically to reduce the rejection rate in patients with kidney transplantation; however, the resultant nephrotoxicity remains a serious problem. In the present study we attempted to elucidate the mechanisms of glomerular injury induced by FK506 and the renoprotective effects of the angiotensin II receptor blocker telmisartan. Methods: Seven-week-old male Wistar rats were divided into three groups: vehicle group, FK506 group, and FK506 + telmisartan group. After 8 weeks, we assessed kidney function and renal morphological changes including oxidative stress. We also assessed the effect of FK506 in human glomerular endothelial cells (hGECs) with regard to reactive oxygen species (ROS). Results: FK506 induced ROS production via activation of NAD(P)H oxidase in the glomeruli. Expression of ICAM mRNA was increased in glomeruli from the FK506 group. These effects resulted in macrophage infiltration into the glomeruli. FK506 directly promoted NAD(P)H oxidase activity and accelerated production of ROS in hGECs. Conversely, cotreatment with telmisartan inhibited both NAD(P)H oxidase activity and production of ROS. Conclusion: These findings suggest that glomerular injury resulting from FK506 is caused by oxidative stress mediated by activation of NAD(P)H oxidase and that telmisartan exerts a renoprotective effect via antioxidative activity.

Mesenteric panniculitis: a rare cause of fever.

Dear Editor, Mesenteric panniculitis is a rare disease characterized by nonspecific inflammation of the adipose tissue of the mesentery. The documented symptoms include abdominal pain, intestinal obstruction, malaise and weight loss. However, patients with mesenteric panniculitis could also present with fever only or be asymptomatic, with laboratory data showing elevation of the erythrocyte sedimentation rate or serum C-reactive protein (CRP). Such patients can be a diagnostic and therapeutic challenge to the rheumatologist. Based on a search of the PubMed database, it seems that mesenteric panniculitis has received little attention in the rheumatology literature. We report here two patients who presented with fever, and were finally diagnosed with mesenteric panniculitis.

Abdominal pain as the initial presentation of Takayasu arteritis

Abdominal pain is rarely described as a clinical manifestation of Takayasu arteritis, although abdominal vascular involvement is common in this disease. We report the case of a 20-year-old female with Takayasu arteritis who complained of chronic and intermittent abdominal pain. Computed tomographic angiography and ultrasonography were useful in evaluating the abdominal arterial involvement. Takayasu arteritis must be considered one of the underlying diseases that may cause chronic abdominal pain in young females.

Predominance of Th2 and regulatory cytokines in the serum of a patient with IgG4-related lymphadenopathy.

Dear Editor, Immunoglobulin G4 (IgG4)-related lymphadenopathy is a novel clinical entity characterized by numerous IgG4 plasma cells in lymph nodes and elevated serum IgG4 levels. However, patients with hyper-interleukin 6 (IL-6) syndromes such as multicentric Castleman’s disease, rheumatoid arthritis, or other immune-mediated inflammatory conditions, frequently show lymph node involvement and often fulfill the diagnostic criteria for IgG4-related lymphadenopathy. Therefore, diagnosis should not rest on pathological findings alone but be supplemented with additional laboratory analyses. We describe a patient with IgG4-related lymphadenopathy with marked increase in serum levels of Th2 and regulatory cytokines. A 76-year-old man presented with a complaint of generalized fatigue and appetite loss. He was also aware of body weight loss which developed over a few months. The patient had no history of allergy, bronchial asthma, atopic disorder, rhinitis or eczema. Physical examination showed a body temperature of 36.5°C, blood pressure of 130/73 mmHg, and pulse of 93 beats/min. No crackle or wheeze was detected on auscultation. He had multiple palpable lymph nodes in the neck, supraclavicular, axillary and inguinal regions. Laboratory studies showed a C-reactive protein level of 3.77 mg/dL (normal < 0.30), hemoglobin of 11.3 g/ dL, white cell count of 9250/lL (neutrophils 5828/lL, eosinophils 2220/lL [24%]), and platelet count of 14.0 9 10/lL. Serum lactate dehydrogenase level was not elevated at 175 U/L (normal 120–240). Serum total IgG was elevated at 5087 mg/dL (normal 1000–1800), and IgG4 increased at 1140 mg/dL (normal 4.8–105.0, 22.4% of total IgG). No M-protein was detected by immunoelectrophoresis. Serum IgE was markedly elevated at 20 523 IU/mL (normal < 170). Serological tests showed negativity for antinuclear antibodies and rheumatoid factor. Serum concentrations of complements (C3 and C4) were normal. An antigen and antibody combination test for human immunodeficiency virus infection was negative. Computed tomography (CT) scan of the chest demonstrated supraclavicular, mediastinal and hilar lymphadenopathy, as well as diffuse reticulation and interlobular thickening mixed with multiple subpleural consolidations in the bilateral lower pulmonary lobes. Abdominal CT scan also showed mild splenomegaly. Positron emission tomography – CT scan with F-fluoro-2-deoxyglucose (FDG) showed accumulation in the lymph nodes of the neck and supraclavicular, mediastinal, axillary and inguinal regions (Fig. 1). Left inguinal lymph node biopsy revealed diffuse infiltration of predominantly mononuclear cells and plasma cells expressing IgG4 (IgG4/IgG plasma cell ratio 60%). A diagnosis of IgG4-related lymphadenopathy (type II: reactive follicular hyperplasia-like type) with possible pulmonary involvement was made. The patient was started on prednisolone (30 mg/day). Such treatment resulted in the improvement of symptoms, pulmonary lesions and multiple lymphadenopathy. Serum levels of total IgG and IgG4 were reduced to normal ranges. The patient remained clinically well without recurrence for a further 12 months on maintenance prednisolone at 10 mg/day. To investigate the underlying pathophysiology in IgG4-related lymphadenopathy, serum levels of 26 types of cytokines were measured by a multiplex bead analysis system using a Milliplex Map kit (Millipore, Billerica, MA, USA). The cytokines measured were IL-1a, IL-1b, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p40, IL-12p70, IL-13, IL-15, IL-17, eotaxin, granulocyte colony-stimulating factor, granulocytemacrophage colony-stimulating factor, interferon (IFN)-a2, IFN-c, IP-10, MCP-1, MIP-1a, MIP-1b, tumor necrosis factor (TNF)-a, and TNF-b. As shown in Table 1, levels of Th2 and regulatory cytokines such as IL-4, IL-5, IL-10 and IL-13 in the patient’s serum before treatment were markedly higher than in the serum after treatment and higher than in healthy controls. Additionally, levels of IL6, IL-8, TNF-a, and IFN-a2 were modestly increased in the patient’s serum before treatment, while serum levels of IFN-c, IL-17 and IL-1a were increased after treatment. Differences in the serum levels of the other 16 cytokines

High dietary protein intake induces endothelial dysfunction in uninephrectomized rats

High dietary protein (HP) intake is a risk factor for chronic kidney disease (CKD). HP intake is associated with the development of albuminuria and glomerulosclerosis in uninephrectomized rats. In such rats, we investigated whether HP intake induces endothelial dysfunction. Male Wistar rats were divided into sham-operated rats fed a standard-protein diet, sham-operated rats fed a high-protein diet, uninephrectomized rats fed a standard-protein diet (NxSP) and uninephrectomized rats fed a high-protein diet (NxHP) (n=8 each). One week after treatment, endothelial function and urinary albumin excretion (UAE) were measured. Protein expression, phosphorylation at serine residue 1177 and uncoupling of endothelial nitric oxide synthase (eNOS), and mRNA expression of NADPH oxidase components were assessed in the aorta. NxHP rats showed hypertriglyceridemia and modest hyperhomocysteinemia. Endothelial function was significantly lower, and UAE was significantly higher in NxHP rats compared with the other groups (P<0.01 each), although there was no difference in creatinine clearance between NxSP and NxHP rats. Expression levels, phosphorylation and the dimer/monomer ratio of eNOS did not differ among the four groups. HP intake did not modify p22phox and p47phox expression levels in uninephrectomized rats. In conclusion, HP intake induced endothelial dysfunction and enhanced albuminuria in uninephrectomized rats, inde-pendent of renal function, suggesting that HP intake may cause the development of cardiovascular disease associated with CKD.