[A case of chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) without relapse after early steroid treatment].

Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is a brainstem predominant lymphocytic inflammatory disease, which often relapses without oral immunosuppressants. This report describes a 37-year-old male case of CLIPPERS without relapse for 1 year after early steroid treatment. He was admitted to our hospital because of sensory disturbance in the left side of his body and ataxic gait. Gadolinium-enhanced T1-weighted MRI revealed multiple punctate and curvilinear enhancements in the pons and right middle cerebellar peduncle. We started treatment with high-dose intravenous methylprednisolone (IVMP) therapy on the 20th day of the illness. His neurological symptoms dramatically improved. Follow-up MRI showed that the enhancing lesions disappeared. We diagnosed him with CLIPPERS based on the clinical course, radiological findings, and steroid response. He did not take any oral immunosuppressant after discharge. However, there was no clinical and radiological relapse for 1 year after the IVMP therapy. Although this case requires careful follow-up because of recurrence risk, early steroid treatment was possibly related to 1-year remission.

Hepatic Overexpression of Endothelial Lipase Lowers High-Density Lipoprotein but Maintains Reverse Cholesterol Transport in Mice: Role of Scavenger Receptor Class B Type I/ATP-Binding Cassette Transporter A1-Dependent Pathways.

OBJECTIVE: Reverse cholesterol transport (RCT) is a major mechanism by which HDL (high-density lipoprotein) protects against atherosclerosis. Endothelial lipase (EL) reportedly reduces HDL levels, which, in theory, would increase atherosclerosis. However, it remains unclear whether EL affects RCT in vivo. APPROACH AND RESULTS: Adenoviral vectors expressing EL or luciferase were intravenously injected into mice, and a macrophage RCT assay was performed. As expected, hepatic EL overexpression markedly reduced HDL levels. In parallel, plasma 3H-cholesterol counts from the EL-expressing mice decreased by 85% compared with control. Surprisingly, there was no difference in fecal 3H-cholesterol excretion between the groups. Kinetic studies revealed increased catabolism/hepatic uptake of 3HDL-cholesteryl ether, resulting in no change in fecal HDL-cholesteryl ester excretion in the mice. To explore underlying mechanisms for the preservation of RCT despite low HDL levels in the EL-expressing mice, we investigated the effects of hepatic SR-BI (scavenger receptor class B type I) knockdown. RCT assay revealed that knockdown of SR-BI alone reduced fecal excretion of macrophage-derived 3H-cholesterol. Interestingly, hepatic EL overexpression under SR-BI inhibition further attenuated fecal tracer counts as compared with control. Finally, we observed that EL overexpression enhanced in vivo RCT under pharmacological inhibition of hepatic ABCA1 (ATP-binding cassette transporter A1) by probucol. CONCLUSIONS: Hepatic EL expression compensates for reduced macrophage-derived cholesterol efflux to plasma because of low HDL levels by promoting cholesterol excretion to bile/feces via an SR-BI pathway, maintaining overall RCT in vivo. In contrast, EL-modified HDL might negatively regulate RCT via hepatic ABCA1. Despite extreme hypoalphalipoproteinemia, RCT is maintained in EL-expressing mice via SR-BI/ABCA1-dependent pathways.

(123)I-meta-iodobenzylguanidine (MIBG) cardiac scintigraphy in α-synucleinopathies.

Cardiac meta-iodobenzylguanidine (MIBG) uptake on (123)I-MIBG cardiac scintigraphy is reduced in patients with Lewy body disease such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and pure autonomic failure, and has been reported to be useful for differentiating PD from other parkinsonian syndromes, as well as DLB from Alzheimer disease (AD). Postmortem studies have shown that the number of tyrosine hydroxylase (TH)-immunoreactive nerve fibers of the heart was decreased in pathologically-confirmed Lewy body disease, supporting the findings of reduced cardiac MIBG uptake in Lewy body diseases. Now, reduced cardiac MIBG uptake can be a potential biomarker for the presence of Lewy bodies in the nervous system. (123)I-MIBG cardiac scintigraphy can allow us to determine the presence of Lewy bodies.

Probucol-Oxidized Products, Spiroquinone and Diphenoquinone, Promote Reverse Cholesterol Transport in Mice.

OBJECTIVE: Oxidized products of probucol, spiroquinone and diphenoquinone, were shown to increase cell cholesterol release and plasma high-density lipoprotein (HDL) by inhibiting degradation of ATP-binding cassette transporter A1. We investigated whether these compounds enhance reverse cholesterol transport in mice. APPROACH AND RESULTS: Spiroquinone and diphenoquinone increased ATP-binding cassette transporter A1 protein (2.8- and 2.6-fold, respectively, P<0.01) and apolipoprotein A-I-mediated cholesterol release (1.4- and 1.4-fold, P<0.01 and P<0.05, respectively) in RAW264.7 cells. However, diphenoquinone, but not spiroquinone, enhanced cholesterol efflux to HDL (+12%, P<0.05), whereas both increased ATP-binding cassette transporter G1 protein, by 1.8- and 1.6-fold, respectively. When given orally to mice, both compounds significantly increased plasma HDL-cholesterol, by 19% and 20%, respectively (P<0.05), accompanied by an increase in hepatic and macrophage ATP-binding cassette transporter A1 but not ATP-binding cassette transporter G1. We next evaluated in vivo reverse cholesterol transport by injecting RAW264.7 cells labeled with (3)H-cholesterol intraperitoneally into mice. Both spiroquinone and diphenoquinone increased fecal excretion of the macrophage-derived (3)H-tracer, by 25% and 28% (P<0.01 and P<0.05), respectively. spiroquinone/diphenoquinone did not affect fecal excretion of HDL-derived (3)H-cholesterol, implying that macrophage-to-plasma was the most important step in spiroquinone/diphenoquinone-mediated promotion of in vivo reverse cholesterol transport. Finally, spiroquinone significantly reduced aortic atherosclerosis in apolipoprotein E null mice when compared with the vehicle. CONCLUSIONS: Spiroquinone and diphenoquinone increase functional ATP-binding cassette transporter A1 in both the macrophages and the liver, elevate plasma HDL-cholesterol, and promote overall reverse cholesterol transport in vivo. These compounds are promising as therapeutic reagents against atherosclerosis.

Ezetimibe enhances macrophage reverse cholesterol transport in hamsters: contribution of hepato-biliary pathway.

Reverse cholesterol transport (RCT) is pivotal in the return of excess cholesterol from peripheral tissues to the liver for excretion in bile and eventually feces. RCT from macrophages is a critical anti-atherogenicity mechanism of HDL. As the cholesterol absorption inhibitor ezetimibe promoted RCT in mice, which lack cholesterol ester transfer protein (CETP), we investigated its effects in hamsters, which have CETP. A high-cholesterol diet (HC) increased cholesterol levels throughout lipoprotein fractions and ezetimibe markedly reduced VLDL/LDL cholesterol levels under both normal chow (NC) and HC. However, ezetimibe did not affect and reduced HDL-cholesterol levels under NC and HC, respectively. Intraperitoneal injection of (3)H-cholesterol pre-labeled macrophages in an in vivo RCT assay increased tracer accumulation in the liver but reduced it in bile under HC, and these changes were completely cancelled by ezetimibe. Under both NC and HC, ezetimibe reduced tracer levels in the liver but increased them in feces, indicating promotion of RCT in vivo. We performed a RCT assay using hamsters subjected to bile duct ligation (BDL) to clarify whether a transintestinal cholesterol efflux (TICE) pathway contributes to ezetimibe's enhancement of RCT. BDL markedly inhibited macrophage-derived (3)H-cholesterol excretion to feces and cancelled ezetimibe's stimulatory effect on RCT, suggesting that biliary cholesterol excretion is a major contributor in RCT promotion by ezetimibe but the contribution of the TICE pathway is minimal. In conclusions, ezetimibe exerts an additive anti-atherogenic property by enhancing RCT in hamsters. Our findings suggest that this property is independent of the TICE pathway.

Hepatic overexpression of idol increases circulating protein convertase subtilisin/kexin type 9 in mice and hamsters via dual mechanisms: sterol regulatory element-binding protein 2 and low-density lipoprotein receptor-dependent pathways.

OBJECTIVE: Low-density lipoprotein receptor (LDLR) is degraded by inducible degrader of LDLR (Idol) and protein convertase subtilisin/kexin type 9 (PCSK9), thereby regulating circulating LDL levels. However, it remains unclear whether, and if so how, these LDLR degraders affect each other. We therefore investigated effects of liver-specific expression of Idol on LDL/PCSK9 metabolism in mice and hamsters. APPROACH AND RESULTS: Injection of adenoviral vector expressing Idol (Ad-Idol) induced a liver-specific reduction in LDLR expression which, in turn, increased very-low-density lipoprotein/LDL cholesterol levels in wild-type mice because of delayed LDL catabolism. Interestingly, hepatic Idol overexpression markedly increased plasma PCSK9 levels. In LDLR-deficient mice, plasma PCSK9 levels were already elevated at baseline and unchanged by Idol overexpression, which was comparable with the observation for Ad-Idol-injected wild-type mice, indicating that Idol-induced PCSK9 elevation depended on LDLR. In wild-type mice, but not in LDLR-deficient mice, Ad-Idol enhanced hepatic PCSK9 expression, with activation of sterol regulatory element-binding protein 2 and subsequently increased expression of its target genes. Supporting in vivo findings, Idol transactivated PCSK9/LDLR in sterol regulatory element-binding protein 2/LDLR-dependent manners in vitro. Furthermore, an in vivo kinetic study using (125)I-labeled PCSK9 revealed delayed clearance of circulating PCSK9, which could be another mechanism. Finally, to extend these findings into cholesteryl ester transfer protein-expressing animals, we repeated the above in vivo experiments in hamsters and obtained similar results. CONCLUSIONS: A vicious cycle in LDLR degradation might be generated by PCSK9 induced by hepatic Idol overexpression via dual mechanisms: sterol regulatory element-binding protein 2/LDLR. Furthermore, these effects would be independent of cholesteryl ester transfer protein expression.

Intensive lipid lowering therapy with titrated rosuvastatin yields greater atherosclerotic aortic plaque regression: Serial magnetic resonance imaging observations from RAPID study.

OBJECTIVE: Although previous randomized clinical trials established a basis for lipid guidelines worldwide, they employed fixed doses of statins throughout trials (fire-and-forget approach). In the real clinical setting, however, statin doses are titrated to achieve target low-density lipoprotein cholesterol (LDL-C) levels (treat-to-target approach). The major objective was to investigate whether intensive lipid-lowering therapy using the treat-to-target approach yielded greater regression of aortic plaques. METHODS: We therefore performed a prospective, randomized trial comparing the effects of standard (achieve LDL-C levels recommended by the Japanese guidelines) and intensive (achieve 30% lower LDL-C levels than standard) rosuvastatin therapy for 1 year in 60 hypercholesterolemic patients with a primary endpoint of aortic atherosclerotic plaques evaluated by non-invasive magnetic resonance imaging (MRI). RESULTS: Average doses were 2.9 ± 3.1 and 6.5 ± 5.1 mg/day for standard (n = 29) and intensive therapy group (n = 31), respectively. Although both therapies significantly reduced LDL-C and high-sensitivity C-reactive protein (hsCRP) levels, LDL-C reduction was significantly greater in the intensive group (-46 vs. -34%). MRI study showed that thoracic aortic plaques were significantly regressed in both groups, with greater regression of thoracic plaque in the intensive group (-9.1 vs. -3.2%, p = 0.01). Multivariate analyses revealed that thoracic plaque regression was significantly correlated with hsCRP reduction, but not with changes in serum lipids, endothelial function, or doses of rosuvastatin. CONCLUSION: Intensive statin therapy with titration targeting lower LDL-C levels resulted in greater thoracic aortic plaque regression compared to standard therapy, which was correlated with hsCRP reduction, suggesting that intensive statin therapy could provide better clinical outcomes.

Overexpression of stearoyl-coenzyme A desaturase 1 in macrophages promotes reverse cholesterol transport.

Stearoyl-coenzyme A desaturase 1 (SCD1) is the rate-limiting enzyme in the synthesis of monounsaturated fatty acids. However, the impact of SCD1 on atherosclerosis remains unclear. The aim of this study was to determine whether SCD1 affects macrophage reverse cholesterol transport (RCT) in mice. Compared to the control, adenoviral-mediated SCD1 overexpression in RAW264.7 macrophages increased cholesterol efflux to HDL, but not to apoA-I, without clear changes in ABCA1, ABCG1 and SR-BI expressions. While knockdown of ABCG1 and SR-BI did not affect the SCD1-induced cholesterol efflux to HDL, SCD1-overexpressing macrophages promoted the formation of both normal- and large-sized HDL in media, accompanying increased apolipoprotein A-I levels in HDL fractions. Transformation to larger particles of HDL was independently confirmed by nuclear magnetic resonance-based lipoprotein analysis. Interestingly, media transfer assays revealed that HDL generated by SCD1 had enhanced cholesterol efflux potential, indicating that SCD1 transformed HDL to a more anti-atherogenic phenotype. To study macrophage RCT in vivo, (3)H-cholesterol-labeled RAW264.7 cells overexpressing SCD1 or the control were intraperitoneally injected into mice. Supporting the in vitro data, injection of SCD1-macrophages resulted in significant increases in (3)H-tracer in plasma, liver, and feces compared to the control. Moreover, there was a shift towards larger particles in the (3)H-tracer distribution of HDL fractions obtained from the mice. In conclusion, macrophage-specific SCD1 overexpression promotes overall RCT through increased cholesterol efflux to HDL, suggesting that macrophage SCD1 achieves an anti-atherogenic effect by enhancing RCT.

Dipeptidyl peptidase-4 inhibitors attenuate endothelial function as evaluated by flow-mediated vasodilatation in type 2 diabetic patients.

BACKGROUND: Endothelial dysfunction is an independent predictor for cardiovascular events in patients with type 2 diabetes (T2DM). Glucagon like peptide-1 (GLP-1) reportedly exerts vasodilatory actions, and inhibitors of dipeptidyl peptidase-4 (DPP-4), an enzyme-degrading GLP-1, are widely used to treat T2DM. We therefore hypothesized that DPP-4 inhibitors (DPP-4Is) improve endothelial function in T2DM patients and performed 2 prospective, randomized crossover trials to compare the DPP-4I sitagliptin and an α-glucosidase inhibitor, voglibose (in study 1) and the DPP-4Is sitagliptin and alogliptin (in study 2). METHODS AND RESULTS: In study 1, 24 men with T2DM (46±5 years) were randomized to sitagliptin or voglibose for 6 weeks without washout periods. Surprisingly, sitagliptin significantly reduced flow-mediated vasodilatation (FMD; -51% compared with baseline, P<0.05) of the brachial artery despite improved diabetic status. In contrast, voglibose did not affect FMD. To confirm this result and determine whether it is a class effect, we conducted another trial (study 2) to compare sitagliptin and alogliptin in 42 T2DM patients (66±8 years) for 6 weeks with 4-week washout periods. Both DPP-4Is improved glycemic control but significantly attenuated FMD (7.2/4.3%, P<0.001, before/after sitagliptin; 7.0/4.8%, P<0.001, before/after alogliptin, respectively). Interestingly, FMD reduction was less evident in subjects who were on statins or whose LDL cholesterol levels were reduced by them, but this was not correlated with parameters including DPP-4 activity and GLP-1 levels or diabetic parameters. CONCLUSIONS: Our 2 independent trials demonstrated that DPP-4 inhibition attenuated endothelial function as evaluated by FMD in T2DM patients. This unexpected unfavorable effect may be a class effect of DPP-4Is. CLINICAL TRIAL REGISTRATION: URL: http://center.umin.ac.jp, Unique Identifiers: UMIN000005682 (sitagliptin versus voglibose) and UMIN000005681 (sitagliptin versus alogliptin).

Astaxanthin enhances ATP-binding cassette transporter A1/G1 expressions and cholesterol efflux from macrophages.

ATP-binding cassette transporters (ABC) A1 and G1 are key molecules in cholesterol efflux from macrophages, which is an initial step of reverse cholesterol transport (RCT), a major anti-atherogenic property of high-density lipoprotein (HDL). Astaxanthin is one of the naturally occurring carotenoids responsible for the pink-red pigmentation in a variety of living organisms. Although astaxanthin is known to be a strong antioxidant, it remains unclear through what mechanism of action it affects cholesterol homeostasis in macrophages. We therefore investigated the effects of astaxanthin on cholesterol efflux and ABCA1/G1 expressions in macrophages. Astaxanthin enhanced both apolipoprotein (apo) A-I- and HDL-mediated cholesterol efflux from RAW264.7 cells. In supporting these enhanced cholesterol efflux mechanisms, astaxanthin promoted ABCA1/G1 expression in various macrophages. In contrast, peroxisome proliferator-activated receptor γ, liver X receptor (LXR) α and LXRß levels remained unchanged by astaxanthin. An experiment using actinomycin D demonstrated that astaxanthin transcriptionally induced ABCA1/G1 expression, and oxysterol depletion caused by overexpression of cholesterol sulfotransferase further revealed that these inductions in ABCA1/G1 were independent of LXR-mediated pathways. Finally, we performed luciferase assays using human ABCA1/G1 promoter-reporter constructs to reveal that astaxanthin activated both promoters irrespective of the presence or absence of LXR-responsive elements, indicating LXR-independence of these activations. In conclusion, astaxanthin increased ABCA1/G1 expression, thereby enhancing apoA-I/HDL-mediated cholesterol efflux from the macrophages in an LXR-independent manner. In addition to the anti-oxidative properties, the potential cardioprotective properties of astaxanthin might therefore be associated with an enhanced anti-atherogenic function of HDL.

Retinoic acid receptor agonists regulate expression of ATP-binding cassette transporter G1 in macrophages.

ABC transporter G1 (ABCG1) plays a pivotal role in HDL-mediated cholesterol efflux and atherogenesis. We investigated whether, and how, retinoic acid receptors (RARs) regulate ABCG1 expression in macrophages. All-trans retinoic acid (ATRA), an RAR ligand, increased ABCG1 protein levels and apoA-I/HDL-mediated cholesterol efflux from the macrophages. Both ATRA and other RAR agonists, TTNPB and Am580, increased major transcripts driven by promoter B upstream of exon 5, though minor transcripts driven by promoter A upstream of exon 1 were only increased by ATRA. The stimulatory effects of ATRA on ABCG1 expression were completely abolished in the presence of RAR/RXR antagonists but were only partially canceled in the presence of an LXR antagonist. Adenovirus with overexpressed oxysterol sulfotransferase abolished the LXR pathway, as previously reported, and ATRA-responsiveness in ABCA1/ABCG1 expressions were respectively attenuated by 38 and 22% compared to the control virus. Promoter assays revealed that ABCG1 levels were regulated more by promoter B than promoter A, and ATRA activated promoter B in a liver X receptor-responsive element (LXRE)-dependent manner. Further, LXRE-B in intron 7, but not LXRE-A in intron 5, enhanced ATRA responsiveness under overexpression of all RAR isoforms-RARα/ß/γ. In contrast, the activation of promoter B by TTNPB depended on LXRE-B and RARα, but not on RARß/γ. Finally, chromatin immunoprecipitation and gel-shift assays revealed a specific and direct repeat 4-dependent binding of RARα to LXRE-B. In conclusion, RAR ligands increase ABCA1/G1 expression and apoA-I/HDL-mediated cholesterol efflux from macrophages, and modulate ABCG1 promoter activity via LXRE-dependent mechanisms.

Reduced cardiac 123I-MIBG uptake reflects cardiac sympathetic dysfunction in de novo Parkinson's disease.

It remains unclear whether cardiac iodine-123-labeled metaiodobenzylguanidine ((123)I-MIBG) uptake is clinically related to autonomic dysfunction on conventional autonomic function testing in de novo Parkinson's disease (PD). We therefore studied the relation between cardiac (123)I-MIBG uptake and cardiovascular autonomic dysfunction in patients with de novo PD. The subjects were 26 patients with de novo PD. The ratio of the average pixel count in the heart to that in the mediastinum was calculated to derive the cardiac (123)I-MIBG uptake. Cardiovascular autonomic function was evaluated on the basis of cardiovascular autonomic response on the Valsalva maneuver (VM), and systolic blood pressure response (SBP) on head-up tilt-table testing (HUT). Patients with de novo PD had significantly reduced cardiac (123)I-MIBG uptake as compared with controls (1.58 ± 0.43 vs. 2.25 ± 0.34, p = 0.0001) and cardiovascular autonomic response on the VM. No significant difference in the fall in SBP on HUT was found between patients with de novo PD and the controls. Cardiac (123)I-MIBG uptake in de novo PD was not significantly related to vasomotor sympathetic function, baroreceptor reflex gain, cardiac parasympathetic function, or the changes in SBP on HUT. Cardiac (123)I-MIBG uptake was, however, significantly related to the blood pressure overshoot in phase IV of the VM (r = 0.648, p = 0.0003). Cardiac (123)I-MIBG uptake began to decrease in association with the reduction in the overshoot of phase IV on the VM. Cardiac (123)I-MIBG uptake clinically reflects cardiac sympathetic dysfunction in de novo PD.

Olfactory dysfunction and cardiovascular dysautonomia in Parkinson's disease.

Several studies have reported that olfactory dysfunction is an early neuropathological manifestation of Parkinson's disease (PD). Reduced cardiac meta-iodobenzylguanidine ((123)I-MIBG) uptake may be one of the earliest signs of PD. We studied the relation of olfactory dysfunction to cardiovascular dysautonomia in patients with PD. The study group comprised 66 patients with PD (70.5 years) and 26 controls (70.3 years) for olfactory assessment, 21 controls (72.1 years) for cardiac (123)I-MIBG scintigraphy and heart rate variability (HRV), assessed using the coefficient of variation for RR intervals (HRV), and 23 controls (69.2 years) for orthostatic blood pressure response. Olfactory function was assessed by the odor stick identification test Japan (OSIT-J), and cardiovascular autonomic function was evaluated by (123)I-MIBG scintigraphy of the heart, the fall in orthostatic blood pressure, and HRV. Patients with PD had a significantly lower OSIT-J score than did the controls (4.1 +/- 3.0 vs. 9.9 +/- 1.7, p = 0.001). The OSIT-J score was unrelated to variables other than gender, including age, disease duration, motor score on the unified Parkinson's disease rating scale, score on the mini-mental state examination, motor phenotype, visual hallucinations, and dopaminergic medication on multiple regression and logistic regression analyses. The OSIT-J score was related to the heart/mediastinum ratio of cardiac (123)I-MIBG uptake, the fall in orthostatic blood pressure, and HRV, after adjustment for other clinical variables. Olfactory dysfunction in PD was, thus, significantly related to both cardiac sympathetic and parasympathetic dysfunction, as well as vascular sympathetic dysfunction. As non-motor symptoms of PD, olfactory dysfunction and autonomic network failure appear to be closely related in PD.