Haruhito A. Uchida

A decreased level of serum soluble Klotho is an independent biomarker associated with arterial stiffness in patients with chronic kidney disease.

Background Klotho was originally identified in a mutant mouse strain unable to express the gene that consequently showed shortened life spans. In humans, low serum Klotho levels are related to the prevalence of cardiovascular diseases in community-dwelling adults. However, it is unclear whether the serum Klotho levels are associated with signs of vascular dysfunction such as arterial stiffness, a major determinant of prognosis, in human subjects with chronic kidney disease (CKD). Methods We determined the levels of serum soluble Klotho in 114 patients with CKD using ELISA and investigated the relationship between the level of Klotho and markers of CKD-mineral and bone disorder (CKD-MBD) and various types of vascular dysfunction, including flow-mediated dilatation, a marker of endothelial dysfunction, ankle-brachial pulse wave velocity (baPWV), a marker of arterial stiffness, intima-media thickness (IMT), a marker of atherosclerosis, and the aortic calcification index (ACI), a marker of vascular calcification. Results The serum Klotho level significantly correlated with the 1,25-dihydroxyvitamin D level and inversely correlated with the parathyroid hormone level and the fractional excretion of phosphate. There were significant decreases in serum Klotho in patients with arterial stiffness defined as baPWV≥1400 cm/sec, atherosclerosis defined as maximum IMT≥1.1 mm and vascular calcification scores of ACI>0%. The serum Klotho level was a significant determinant of arterial stiffness, but not endothelial dysfunction, atherosclerosis or vascular calcification, in the multivariate analysis in either metabolic model, the CKD model or the CKD-MBD model. The adjusted odds ratio of serum Klotho for the baPWV was 0.60 (p = 0.0075). Conclusions Decreases in the serum soluble Klotho levels are independently associated with signs of vascular dysfunction such as arterial stiffness in patients with CKD. Further research exploring whether therapeutic approaches to maintain or elevate the Klotho level could improve arterial stiffness in CKD patients is warranted.

Calpain inhibition attenuates angiotensin II-induced abdominal aortic aneurysms and atherosclerosis in low-density lipoprotein receptor-deficient mice.

Abstract Chronic infusion of angiotensin II (AngII) augments atherosclerosis and abdominal aortic aneurysm (AAA) formation in hypercholesterolemic mice. AngII-induced AAAs are associated with medial macrophage accumulation and matrix metalloproteinase (MMP) activation. Inhibition of calpain, a calcium-activated neutral cysteine protease, by overexpression of its endogenous inhibitor, calpastatin, attenuates AngII-induced leukocyte infiltration, perivascular inflammation, and MMP activation in mice. The purpose of this study was to define whether pharmacological inhibition of calpain influences AngII-induced AAAs in hypercholesterolemic mice. Male low-density lipoprotein receptor−/− mice were fed a fat-enriched diet and administered with either vehicle or a calpain-specific inhibitor, BDA-410 (30 mg/kg per day) for 5 weeks. After 1 week of feeding, mice were infused with AngII (1000 ng/kg per minute) for 4 weeks. AngII-infusion profoundly increased aortic calpain protein and activity. BDA-410 administration had no effect on plasma cholesterol concentrations or AngII-increased systolic blood pressure. Calpain inhibition significantly attenuated AngII-induced AAA formation and atherosclerosis development. BDA-410 administration attenuated activation of MMP12, proinflammatory cytokines (IL-6, monocyte chemoattractant protein-1), and macrophage infiltration into the aorta. BDA-410 administration significantly attenuated thioglycolate-elicited macrophage accumulation in the peritoneal cavity. We conclude that calpain inhibition using BDA-410 attenuated AngII-induced AAA formation and atherosclerosis development in low-density lipoprotein receptor−/− mice.

Total Lymphocyte Deficiency Attenuates AngII-induced Atherosclerosis in Males But Not Abdominal Aortic Aneurysms in ApoE Deficient Mice

OBJECTIVE T and B lymphocytes are associated with atherosclerosis and aneurysms. Angiotensin II (AngII) infusion into hypercholesterolemic mice results in augmentation of atherosclerosis and abdominal aortic aneurysm (AAA) formation. In this study, we determined whether total lymphocyte deficiency reduced AngII-induced vascular diseases. METHODS AND RESULTS ApoE deficient (apoE -/-) mice were cross-bred with recombination activating gene-1 (Rag-1) deficient mice that lack mature T and B lymphocytes. Heterozygous littermates (Rag-1 +/-) have normal lymphocytic function and served as controls. Male and female apoE -/- mice that were either Rag-1 +/- or -/- were fed a normal laboratory diet and infused with either saline or AngII (1000ng/kg/min) subcutaneously via osmotic mini pump for 28 days. Total lymphocyte deficiency had no significant effect on body weight and systolic blood pressure prior to and during AngII infusion. However, it was associated with decreased serum cholesterol concentrations. AngII infusion increased atherosclerotic lesion area in Rag-1 +/- mice compared to saline (P=0.017 in males and P=0.004 in females). This effect was significantly blunted in Rag-1 -/- male (P=0.044), but not female mice. AngII-infusion promoted increased width of the abdominal aorta, with a greater effect in males. Despite the reduction in atherosclerosis in males, Rag-1 deficiency had no significant effect on AngII-induced aortic dilation in either gender. CONCLUSION T and B lymphocyte deficiency attenuates AngII-induced atherosclerosis in males but not AAA formation in apoE -/- mice.

Urokinase-Type Plasminogen Activator Deficiency in Bone Marrow–Derived Cells Augments Rupture of Angiotensin II–Induced Abdominal Aortic Aneurysms

Objective—Abdominal aortic aneurysms (AAAs) are associated with fragmentation of extracellular matrix during development of aortic dilation and rupture. Therefore, it is important to identify specific protease systems involved in extracellular matrix degradation during AAA formation. The present study determined the contribution of the urokinase system to AAA formation and rupture. Methods and Results—Angiotensin II (Ang II)–induced AAAs were associated with increased aortic abundance of both urokinase-type plasminogen activator receptor (uPAR) and urokinase-type plasminogen activator (uPA) proteins. However, this increased presence was unrelated to AAA formation because deficiencies of either uPAR or uPA had no effect on either the incidence or size of Ang II–induced AAAs in both normolipidemic mice and low-density lipoprotein receptor−/− mice fed a saturated fat–enriched diet. Although uPA deficiency did not affect development of AAAs, there was an effect of increasing mortality rate from AAA rupture in hypercholesterolemic mice. Bone marrow transplantation demonstrated that enhanced aneurysmal rupture was attributable to deficiency of uPA in leukocytes. uPA deficiency led to an increased propensity for impaired resolution of the thrombotic material within the aneurysmal tissue. Neither uPAR nor uPA deficiency had any effect on Ang II–induced atherosclerosis in low-density lipoprotein receptor−/− mice. Conclusion—The uPA-uPAR axis has no effect on the formation of Ang II–induced AAAs, but uPA deficiency promotes aneurysmal rupture.

Cholecystokinin Plays a Novel Protective Role in Diabetic Kidney Through Anti-inflammatory Actions on Macrophage Anti-inflammatory Effect of Cholecystokinin

Inflammatory process is involved in the pathogenesis of diabetic nephropathy. In this article, we show that cholecystokinin (CCK) is expressed in the kidney and exerts renoprotective effects through its anti-inflammatory actions. DNA microarray showed that CCK was upregulated in the kidney of diabetic wild-type (WT) mice but not in diabetic intracellular adhesion molecule-1 knockout mice. We induced diabetes in CCK-1 receptor (CCK-1R) and CCK-2R double-knockout (CCK-1R−/−,-2R−/−) mice, and furthermore, we performed a bone marrow transplantation study using CCK-1R−/− mice to determine the role of CCK-1R on macrophages in the diabetic kidney. Diabetic CCK-1R−/−,-2R−/− mice revealed enhanced albuminuria and inflammation in the kidney compared with diabetic WT mice. In addition, diabetic WT mice with CCK-1R−/− bone marrow–derived cells developed more albuminuria than diabetic CCK-1R−/− mice with WT bone marrow–derived cells. Administration of sulfated cholecystokinin octapeptide (CCK-8S) ameliorated albuminuria, podocyte loss, expression of proinflammatory genes, and infiltration of macrophages in the kidneys of diabetic rats. Furthermore, CCK-8S inhibited both expression of tumor necrosis factor-α and chemotaxis in cultured THP-1 cells. These results suggest that CCK suppresses the activation of macrophage and expression of proinflammatory genes in diabetic kidney. Our findings may provide a novel strategy of therapy for the early stage of diabetic nephropathy.

Activation of Liver X Receptor Inhibits Osteopontin and Ameliorates Diabetic Nephropathy

Osteopontin is a proinflammatory cytokine and monocyte chemoattractant implicated in the pathogenesis of diabetic nephropathy. Synthetic agonists for liver X receptors (LXRs) suppress the expression of proinflammatory genes, including osteopontin, but whether LXR activation modulates diabetic nephropathy is unknown. We administered the LXR agonist T0901317 to mice with streptozotocin-induced diabetes and evaluated its effects on diabetic nephropathy. The LXR agonist decreased urinary albumin excretion without altering blood glucose levels and substantially attenuated macrophage infiltration, mesangial matrix accumulation, and interstitial fibrosis. LXR activation suppressed the gene expression of inflammatory mediators, including osteopontin, in the kidney cortex. In vitro, LXR activation suppressed osteopontin expression in proximal tubular epithelial cells by inhibiting AP-1-dependent transcriptional activation of the osteopontin promoter. Taken together, these results suggest that inhibition of renal osteopontin by LXR agonists may have therapeutic potential for diabetic nephropathy.

The effects of telmisartan treatment on the abdominal fat depot in patients with metabolic syndrome and essential hypertension: Abdominal fat Depot Intervention Program of Okayama (ADIPO)

Telmisartan partially activates the peroxisome proliferator-activated receptor γ (PPARγ), which may ameliorate the accumulation of visceral adipose tissues and sensitise insulin action. Nineteen patients with essential hypertension and metabolic syndrome were randomly assigned to receive 40 mg of telmisartan (TELMI group) once daily or 80 mg of valsartan (VAL group) once daily for 24 weeks. The visceral fat area (VFA) measured by computed tomography (CT) was significantly reduced from 150.4±15.5 to 127.7±16.7 cm2 in the TELMI group (p=0.049). Although VFA was also reduced in the VAL group from 169.8±14.8 to 155.3±14.8 cm2, the change was not significant (p=0.173). There were no significant changes in body weight, body mass index (BMI), waist circumference, subdermal fat area (SFA), fasting plasma glucose, and homeostasis model assessment of insulin resistance (HOMA-IR) in comparison to the baseline and follow-up data in both groups. In conclusion, telmisartan may have a benefit in the reduction of visceral adipose tissues in comparison to valsartan.

Serum high sensitivity cardiac troponin T is a significant biomarker of left ventricular diastolic dysfunction in subjects with non-diabetic chronic kidney disease.

Background: Chronic kidney disease (CKD) is associated with left-ventricular (LV) diastolic dysfunction (LVDD) which progresses to diastolic heart failure. However, biomarkers predicting LVDD in patients with CKD are largely unknown. Methods: In 93 patients with non-diabetic CKD, the relationships among echocardiography, high-sensitivity cardiac troponin T (hs-cTnT), B-type natriuretic peptide (BNP), and renal function were evaluated. LV mass index, peak early diastolic mitral filling velocity (E), peak early diastolic mitral annular velocity (E′), and E/E′ were recorded. Results: The E′ values were significantly decreased and E/E′, BNP, and hs-cTnT increased with increasing CKD stage. The CKD patients with LVDD with E′ <5 cm/s had a significantly higher hs-cTnT level as well as a significantly higher BNP level compared to those with E′ ≧5 cm/s. The area under the receiver-operating characteristic curve for hs-cTnT and BNP to detect E′ <5 cm/s was 0.880 (p = 0.0101) and 0.741 (p = 0.0570), respectively. In multivariate analysis, hs-cTnT and albuminuria were significantly associated with E′, and estimated glomerular filtration rate with the hs-cTnT level, after adjusting for age, cause of CKD, and other parameters. Conclusions: These data suggest that hs-cTnT may be a useful biomarker of LVDD in non- diabetic CKD patients.

Enhanced TGF-b/Smad signaling in the early stage of diabetic nephropathy is independent of the AT1a receptor

BackgroundAngiotensin II (AII) and transforming growth factor-β (TGF-β) are closely involved in the pathogenesis of diabetic nephropathy (DN). AII is known to induce TGF-β production in resident renal cells, including glomerular mesangial cells and tubular epithelial cells. TGF-β receptor types I and II (TGF-βRI, II) are up-regulated in the diabetic kidney. The aim of this study was to clarify the role of AII in the regulation of the TGF-β system in the early stage of DN using AII type1a receptor-deficient(AT1a−/−) mice.MethodsWe investigated the expression of TGF-β1, TGF-βRI, II, and Smad signaling in AT1a−/− mice with streptozotocin (STZ)-induced DN. Mice were killed 10 and 20 days after the induction of hyperglycemia. The expression of TGF-β receptors was analyzed by immunohistochemical staining and reverse transcriptase–polymerase chain reaction (RT–PCR). TGF-β-specific Smad signaling was analyzed by electrophoretic mobility shift assay and Western blotting.ResultsThe expression of both TGF-βRI and RII was up-regulated in the glomerular tufts and vasculature in diabetic AT1a+/+ mice kidney by immunohistochemistry. RT–PCR revealed that mRNAs for TGF-βRI and RII were also up-regulated. Smad2 and 4 protein levels were reduced in the renal cortex after the induction of diabetes, with an increase of Smad 3/4 complex in the nucleus. The expression of TGF-β receptors increased in both diabetic AT1a−/− and AT1a+/+ mice. Smad signaling in AT1a−/− mice was also enhanced.ConclusionsOur results suggest that the complete blockade of the AT1a-mediated pathway has a minimal effect on the enhanced TGF-β/Smad signaling in the early stage of DN, at least in the AT1a−/− model.

Calpain-2 compensation promotes angiotensin II-induced ascending and abdominal aortic aneurysms in calpain-1 deficient mice.

Background and Objective Recently, we demonstrated that angiotensin II (AngII)-infusion profoundly increased both aortic protein and activity of calpains, calcium-activated cysteine proteases, in mice. In addition, pharmacological inhibition of calpain attenuated AngII-induced abdominal aortic aneurysm (AA) in mice. Recent studies have shown that AngII infusion into mice leads to aneurysmal formation localized to the ascending aorta. However, the precise functional contribution of calpain isoforms (-1 or -2) in AngII-induced abdominal AA formation is not known. Similarly, a functional role of calpain in AngII-induced ascending AA remains to be defined. Using BDA-410, an inhibitor of calpains, and calpain-1 genetic deficient mice, we examined the relative contribution of calpain isoforms in AngII-induced ascending and abdominal AA development. Methodology/Results To investigate the relative contribution of calpain-1 and -2 in development of AngII-induced AAs, male LDLr −/− mice that were either calpain-1 +/+ or −/− were fed a saturated fat-enriched diet and infused with AngII (1,000 ng/kg/min) for 4 weeks. Calpain-1 deficiency had no significant effect on body weight or blood pressure during AngII infusion. Moreover, calpain-1 deficiency showed no discernible effects on AngII-induced ascending and abdominal AAs. Interestingly, AngII infusion induced increased expression of calpain-2 protein, thus compensating for total calpain activity in aortas of calpain-1 deficient mice. Oral administration of BDA-410, a calpain inhibitor, along with AngII-infusion significantly attenuated AngII-induced ascending and abdominal AA formation in both calpain-1 +/+ and −/− mice as compared to vehicle administered mice. Furthermore, BDA-410 administration attenuated AngII-induced aortic medial hypertrophy and macrophage accumulation. Western blot and immunostaining analyses revealed BDA-410 administration attenuated AngII-induced C-terminal fragmentation of filamin A, an actin binding cytoskeletal protein in aorta. Conclusion Calpain-2 compensates for loss of calpain-1, and both calpain isoforms are involved in AngII-induced aortic aneurysm formation in mice.