Mónika Katkó

Hydrogen sulfide inhibits the calcification and osteoblastic differentiation of vascular smooth muscle cells

Osteoblastic differentiation of vascular smooth muscle cells (VSMCs) is involved in the pathogenesis of vascular calcification. Hydrogen sulfide (H2S) is a gas endogenously produced by cystathionine γ-lyase in VSMC. Here we determined whether H2S plays a role in phosphate-induced osteoblastic transformation and mineralization of VSMC. Hydrogen sulfide was found to inhibit calcium deposition in the extracellular matrix and to suppress the induction of the genes involved in osteoblastic transformation of VSMC: alkaline phosphatase, osteocalcin, and Cbfa1. Moreover, phosphate uptake and phosphate-triggered upregulation of the sodium-dependent phosphate cotransporter (Pit-1) were also prevented by H2S. Reduction of endogenous production of H2S by inhibition of cystathionine γ-lyase activity resulted in increased osteoblastic transformation and mineralization. Low plasma levels of H2S, associated with decreased cystathionine γ-lyase enzyme activity, were found in patients with chronic kidney disease receiving hemodialysis. Thus, H2S is a potent inhibitor of phosphate-induced calcification and osteoblastic differentiation of VSMC. This mechanism might contribute to accelerated vascular calcification in chronic kidney disease.

Strong correlations between circulating chemerin levels and lipoprotein subfractions in nondiabetic obese and nonobese subjects

Chemerin is a recently described adipokine expressed primarily in the white adipose tissue. Compared with lean subjects, circulating chemerin levels are significantly elevated in obese individuals and correlate positively with the prevalence of various cardiovascular risk factors including altered lipoprotein levels. To date, the impact of chemerin on lipoprotein subfractions and its role in atherosclerotic processes are still unclear.

Relationship between Serum Nickel and Homocysteine Concentration in Hemodialysis Patients

Severe hyperhomocysteinemia (HHC) is associated with atherosclerosis. In hemodialysis (HD) patients, one of the main causes of death is cardiovascular disease. In animals, trace elements such as cobalt, copper, iron, and nickel ameliorated vitamin B12 deficiency-induced HHC. However, correlations between plasma total homocysteine (tHcy) and trace elements in HD patients have not been investigated. Therefore, tHcy, folate, vitamin B12, trace elements (cobalt, copper, iron, and nickel), and some laboratory parameters such as serum total protein, albumin, transferrin, ferritin, C-reactive protein (CRP), and interleukin-6 concentrations were determined in 122 hemodialysis patients. When patients were divided into groups according to their tHcy, we found no significant differences in concentrations of cobalt, copper, and total protein, while nickel was higher, and folate, vitamin B12, and iron were lower in patients with lower than higher tHcy. In univariate regression analysis, tHcy negatively correlated with concentrations of folate (r = −0.302, p < 0.006), vitamin B12 (r = −0.347, p < 0.0001), nickel (r = −0.289, p < 0.006), and CRP (r = −0.230, p < 0.02) and positively with serum albumin (r = 0.316, p < 0.0004) and hemoglobin (r = 0.329, p < 0.0001) values. No relationship between tHcy and serum concentrations of cobalt, copper, iron, or other laboratory parameters was found in HD patients. The effect of cobalt and nickel on homocysteine production was assessed in human peripheral mononuclear cells (PBMCs). Nickel but not cobalt at concentrations found in HD patients significantly inhibited homocysteine, cysteine, and S-adenosylhomocysteine production in human PBMCs. These results suggest that nickel might also be involved in the regulation of the methionine–folate cycle in humans, as was demonstrated in animal experiments.

Cerebrotendinous xanthomatosis with the c.379C>T (p.R127W) mutation in the CYP27A1 gene associated with premature age-associated limbic tauopathy

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive disease associated with mutations in the mitochondrial CYP27A1 gene [1]. The deficiency of sterol 27-hydroxylase leads to the disturbance of bile acid synthesis and causes a multisystem disorder, including signs of premature ageing like cataracts or atherosclerosis. In addition, neuropsychiatric symptoms, like dementia, cerebellar ataxia, pyramidal signs, seizures or extrapyramidal symptoms may occur [1]. Magnetic resonance imaging (MRI) examinations emphasize cerebellar atrophy and bilateral lesions in the cerebellar white matter, while occasional neuropathological studies described granulomatous and xanthomatous changes mainly in the cerebellar hemispheres, globus pallidus and cerebellar peduncles [1]. There is a paucity of information whether age-related neurodegenerative diseases are present in CTX or not. We report the clinical, biochemical and neuropathological features of CTX associated with neuron-predominant tau pathology predominating in the limbic system, which was compatible with age-dependent argyrophilic grain disease. Two Hungarian adult siblings were examined. The elder brother died at the age of 46, and his brother is still alive at the age of 43 and presented with a similar clinical course (summarized in Table 1). The analyses presented here were performed as diagnostic tests and consent for publication was obtained from their mother. In both patients mitochondrial encephalopathy was suspected clinically. During the childhood of patient 1, diarrhoea and anaemia was reported. At elementary school a psychological examination showed moderate mental deficiency. At the age of 14 his IQ was 73. Ten years later hepatomegaly was noted. Two years later cataract was diagnosed in both eyes. Furthermore, due to cognitive impairment and aggression he left his job as an unskilled worker. Soon gait disorder and ataxia evolved and progressed to a spastico-paretico-ataxic gait, together with dysarthria, tetrapyramidal symptoms and tetraparesis. At the age of 45 he had epileptic seizures, his state deteriorated and he died due to bronchopneumonia. General autopsy showed severe atherosclerosis, fibrotic degeneration of myocardium and fatty degeneration of the liver. Neuropathological studies were performed as described using a panel of antibodies against neurodegeneration-related proteins [2], including amyloid-beta (A-beta; 1:50, clone 6F/3D, Dako, Glostrup, Denmark), alpha-synuclein (clone 5G4, 1:2000, Roboscreen, Leipzig, Germany), phospho-TDP-43 (pS409/ 410, 1:2000, Cosmo Bio, Tokyo, Japan), anti-p62 (1:500, BD Biosciences, San Jose, CA, USA), anti-ubiquitin (1:50 000, Millipore, Temecula, CA, USA), and a panel of anti-tau antibodies: anti-tau AT8 (pS202, 1:200), AT100 (pS212, 1:200), AT180 (pT231, 1:200), AT270 (pT181, 1:200), HT7 (tau 169-163, 1:100; all from Pierce Biotechnology, Rockford, IL, USA), anti-4R tau (RD4, 1:200, Upstate, Charlottesville, VA, USA), anti-3R tau (RD3, 1:2000, Upstate). The DAKO EnVision© detection kit, peroxidase/DAB, rabbit/mouse (Dako) was used for visualization of antibody reactions. In addition, Haematoxylin and Eosin, Luxol Fast Blue/nuclear fast red, periodic acidSchiff (PAS), Sudan-black, and Bielschowsky and Gallyas silver stainings were performed. Four major alterations were observed: (1) xanthomatous changes; (2) loss of axons and myelin in the white matter; (3) neuronal loss and reactive astrogliosis; and (4) limbic tauopathy compatible with argyrophilic grain disease. Accumulation of perivascular macrophages, multinucleated giant cells, fibrotic vessels and cholesterol clefts (Figure 1A–D) predominated in the cerebellar white matter, dentate nucleus, globus pallidus, cerebral peduncles, pontine base, and pyramids (Table 2). PAS positive granular material accumulated in the perivascular space; ultrastructurally these were composed of convolutes of membranes that were about 12–15 nm thick (Figure 1E,F). In addition these showed autofluorescence and were Sudan black positive indicative of lipids (online Figure S1). Prominent loss of myelin and axons (Figure 1G), and PAS-positive degradation products in macrophages together with perivascular CD8-positive T cells (Figure 1H) were seen mainly in the cerebellum, cerebral peduncles, pontine base (transverse fibres preserved) and pyramids. Neuronal loss was prominent in the inferior olives, dentate nucleus and cerebellar cortex associated with reactive microgliosis (Figure 1I). Reactive astrogliosis

Homocysteine metabolism in peripheral blood mononuclear cells: evidence for cystathionine beta-synthase activity in resting state

Activated peripheral blood mononuclear cells (PBMC) release homocysteine and possess cystathionine β-synthase (CBS) activity; however, it was thought that there is no CBS in resting state. Previously, we found that nickel decreased intracellular homocysteine concentration in un-stimulated (e.g. resting) PBMC, suggesting that resting PBMC might also have active homocysteine metabolism. Here, we demonstrated that un-stimulated PBMC synthesize (incorporate l-[methyl-14C]methionine to DNA, lipids and proteins), release (increase extracellular homocysteine), and metabolize homocysteine. Intracellular homocysteine concentration varied with incubation time, depending on extracellular concentrations of methionine, homocysteine, and glutathione. Methionine synthase activity was constant and independent of thiol concentrations. In Western blot, CBS protein was clearly identified in freshly isolated PBMC. CBS protein level and activity increased with incubation time, upon stimulation, and similar to intracellular homocysteine, depending on intra- and extracellular homocysteine and glutathione concentrations. According to our knowledge, this is the first evidence that certifies homocysteine metabolism and regulatory role of CBS activity to keep balanced intracellular homocysteine level in resting PBMC. Homocysteine, released by PBMC, in turn can modulate its functions contributing to the development of hyperhomocysteinemia-induced diseases.

Thyroglobulin level at week 16 of pregnancy is superior to urinary iodine concentration in revealing preconceptual and first trimester iodine supply

Abstract Pregnant women are prone to iodine deficiency due to the increased need for iodine during gestation. Progress has recently occurred in establishing serum thyroglobulin (Tg) as an iodine status biomarker, but there is no accepted reference range for iodine sufficiency during pregnancy. An observational study was conducted in 164 pregnant women. At week 16 of gestation urinary iodine concentration (UIC), serum Tg, and thyroid functions were measured, and information on the type of iodine supplementation and smoking were recorded. The parameters of those who started iodine supplementation (≥150 μg/day) at least 4 weeks before pregnancy (n = 27), who started at the detection of pregnancy (n = 51), and who had no iodine supplementation (n = 74) were compared. Sufficient iodine supply was found in the studied population based on median UIC (162 μg/L). Iodine supplementation ≥150 μg/day resulted in higher median UIC regardless of its duration (nonusers: 130 μg/L vs. prepregnancy iodine starters: 240 μg/L, and pregnancy iodine starters: 205 μg/L, p < .001, and p = .023, respectively). Median Tg value of pregnancy starters was identical to that of nonusers (14.5 vs. 14.6 μg/L), whereas prepregnancy starters had lower median Tg (9.1 μg/L, p = .018). Serum Tg concentration at week 16 of pregnancy showed negative relationship (p = .010) with duration of iodine supplementation and positive relationship (p = .008) with smoking, a known interfering factor of iodine metabolism, by multiple regression analysis. Serum Tg at week 16 of pregnancy may be a promising biomarker of preconceptual and first trimester maternal iodine status, the critical early phase of foetal brain development.

Paraoxonase-1 arylesterase activity is an independent predictor of myeloperoxidase levels in overweight patients with or without cardiovascular complications.

OBJECTIVES Myeloperoxidase (MPO), matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) were shown to contribute to atherogenesis, while human paraoxonase-1 (PON1) protects against oxidative stress. Although several studies investigated these biomarkers, their associations have not been completely clarified yet. We aimed to investigate these parameters in overweight hyperlipidemic, lipid-lowering therapy-naive patients (n=167) with and without vascular complications. DESIGN AND METHODS MPO, MMP-9 and TIMP-1 levels were measured by ELISA. PON1 activities were detected spectrophotometrically. PON1 phenotype was calculated by using a dual substrate method. RESULTS Patients with vascular complications (VC) had significantly higher MPO and TIMP-1 levels compared to those without (patients with no vascular complications; NVC) (728 (367.25-1177.90) mg/ml vs. 315.9 (176.05-687.40) mg/ml; p<0.001; and 172.7 (157.7-197.7) ng/ml vs. 152.6 (129.3-172.3) ng/ml; p<0.0001; respectively). MPO levels showed a significant negative correlation with PON1 arylesterase activity (whole patient group (W): r=0.42, p<0.0001; VC: r=0.44, p=0.01; NVC: r=0.39, p<0.0001) and positive correlations with MMP-9 (W: r=0.37, p<0.0001; VC: r=0.29, p=0.07; NVC: r=0.42, p<0.0001) and TIMP-1 (W: r=0.42, p<0.0001; VC: r=0.33, p<0.05; NVC: r=0.41, p<0.0001), respectively. PON1 arylesterase activity was found to be an independent predictor of MPO levels in the whole patient group (β=-0.350, p<0.0001) or when studied separately in the subgroups with or without cardiovascular complications (VC: β=-0.57, p<0.05; NVC: β=-0.33, p<0.0001). CONCLUSIONS Our results suggest that parallel investigation of MPO, MMP-9 and TIMP-1 levels and PON1 arylesterase activity may be a more accurate indicator of atherosclerosis, which may allow earlier treatment and therefore, improvement of treatment efficacy.

Paraoxonase-1 and myeloperoxidase correlate with vascular biomarkers in overweight patients with newly diagnosed untreated hyperlipidaemia

BACKGROUND In hyperlipidaemic state, increased levels of myeloperoxidase (MPO) and decreased paraoxonase-1 (PON1) activity have been reported; however, their relationships with other atherosclerotic biomarkers have not been completely clarified. PATIENTS AND METHODS Serum concentrations of lipid and inflammatory parameters, MPO levels, and PON1 activities were investigated in 167 untreated hyperlipidaemic patients with and without vascular complications and in 32 healthy controls. Additionally, levels of CD40 ligand (sCD40L) and asymmetric dimethyl arginine (ADMA), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1, and oxidized LDL were determined. RESULTS We found elevated C-reactive protein (CRP), ADMA, sCD40L, sICAM-1 concentrations, and higher MPO levels in patients with vascular complications compared to those without. The PON1 arylesterase activity correlated negatively with sCD40L, ADMA, and sICAM-1 levels, respectively. In contrast, MPO concentrations showed positive correlations with sCD40L, ADMA, and sICAM-1 levels, respectively. CONCLUSIONS It can therefore be stated that PON1 activity and MPO level correlate strongly with the vascular biomarkers, highlighting the importance of the HDL-associated pro- and antioxidant enzymes in the development of endothelial dysfunction and atherogenesis.

Egy ritka, veleszületett neurodegeneratív betegség: a cerebrotendinosus xanthomatosis laboratóriumi diagnosztikája@@@Laboratory diagnosis of a rare congenital neurodegenerative disease: cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis is a rare neurodegenerative disease characterized by the accumulation of cholesterol and cholestanol in the brain and the tendons caused by mutations of the gene encoding sterol 27-hydroxylase (CYP27A1), which is involved in bile acid synthesis. The diagnosis is often missed and delayed because of the variable clinical presentation of the disease. Blood testing for cerebrotendinous xanthomatosis is routinely performed using gas chromatography-mass spectrometry measurement of elevated cholestanol level, and the diagnosis is confirmed by molecular genetic analysis. Early recognition and initiation of chenodeoxycholic acid therapy with hydoxymethyl‑glutaryl‑Coenzyme-A reductase inhibitors is critical to prevent irreversible neurological damage and permanent disability. The authors summarize the current knowledge about the pathomechanism, laboratory diagnosis and therapeutic options of cerebrotendinous xanthomatosis.

[Laboratory diagnosis of a rare congenital neurodegenerative disease: cerebrotendinous xanthomatosis].

Cerebrotendinous xanthomatosis is a rare neurodegenerative disease characterized by the accumulation of cholesterol and cholestanol in the brain and the tendons caused by mutations of the gene encoding sterol 27-hydroxylase (CYP27A1), which is involved in bile acid synthesis. The diagnosis is often missed and delayed because of the variable clinical presentation of the disease. Blood testing for cerebrotendinous xanthomatosis is routinely performed using gas chromatography-mass spectrometry measurement of elevated cholestanol level, and the diagnosis is confirmed by molecular genetic analysis. Early recognition and initiation of chenodeoxycholic acid therapy with hydoxymethyl‑glutaryl‑Coenzyme-A reductase inhibitors is critical to prevent irreversible neurological damage and permanent disability. The authors summarize the current knowledge about the pathomechanism, laboratory diagnosis and therapeutic options of cerebrotendinous xanthomatosis.