We have reported that aldosterone is synthesized and cytochrome P450aldo mRNA exists in the vasculature. To clarify the pathophysiological role of vascular aldosterone in hypertension, we compared aldosterone production in the mesenteric arteries of stroke-prone spontaneously hypertensive rats (SHRSP) with that in Wistar-Kyoto rats (WKY). The expressions of mRNA of cytochrome P450aldo, mineralocorticoid receptor, and α 1 Na,K-ATPase in the mesenteric arteries were compared between the two groups. Aldosterone concentration in the perfusate of the vasculature was measured by radioimmunoassay after purification with high-performance liquid chromatography. Cytochrome P450aldo and mineralocorticoid receptor mRNA levels were quantified by Southern blot analysis of the products of reverse-transcribed polymerase chain reaction. Levels of α 1 Na,K-ATPase mRNA were measured by Northern blot analysis. Vascular aldosterone and cytochrome P450aldo mRNA levels of 2-week-old SHRSP were significantly increased compared with those of age-matched WKY. However, vascular aldosterone in 4- and 9-week-old SHRSP did not differ from that in age-matched WKY. Expression levels of mineralocorticoid receptor mRNA in the vasculature of 4- and 9-week-old SHRSP were significantly increased compared with those in age-matched WKY. Concentrations of vascular α 1 Na,K-ATPase mRNA of 2-, 4-, and 9-week-old SHRSP also were significantly higher than those in age-matched WKY. These results suggest that vascular aldosterone contributes to the pathophysiology of hypertension in SHRSP in the early stage.
Background: Whole exome sequencing (WES) has shown ~30% success in the diagnosis of Mendelian disorders. Few data exists regarding clinical application of WES for the molecular diagnosis of familial hypobetalipoproteinemia (FHBL), which is characterized as extremely low LDL cholesterol level. Methods: WES was performed on 36 individuals including 32 patients exhibiting low LDL-C (less than 70 mg/dl) primarily, and 4 unaffected family members from 23 families. We filtered out the following variants: 1) Benign variants predicted by SnpEff; 2) Minor allele frequency (MAF) > 1%; 3) Segregation unmatched for the autosomal codominant pattern; 4) C-score < 10 calculated using in silico prediction software named Combined Annotation Dependent Depletion. Results: Among 181,404 variants found in those individuals, we found 48,786 nonsense, missense, or splice site variants, of which 14,415 were rare (MAF ≤ 1% or not reported). Filtering assuming autosomal codominant pattern of inheritance combined with the use of C-score, we identified heterozygous mutations in 7 families, and homozygous or compound heterozygous mutations in 4 families within the coding region of APOB gene, eight of which were novel (c.394A>T/p.Lys132*, c.1902_1903delTC/p.Ser634fs, c.2702T>G/p.Met901Arg, c.2946delC/p.Ser982fs, c.4437G>C/p.Leu1479Phe, c.4439_4440delTT/p.Phe1480fs, c.11283C>A/p.Cys3761*, c.11433dupT/p.Glu3812fs). Moreover, we identified compound heterozygous mutations in 1 family within the coding region of PCSK9 gene, one of which was novel (c.1301G>A/p.Arg434Gln). Conclusion: WES combined with integrated variant annotation prediction successfully identified causative mutations in patients with FHBL either with APOB gene mutation(s) or PCSK9 gene mutation(s) in 12 among 23 families (52%). Although such comprehensive approach is useful to determine true causative mutations, other strategies are needed to identify novel causative genes, which could potentially lead to the development of novel pharmacological target for dyslipidemia.
The impact of positive clinical signs (xanthoma and/or family history) and positive familial hypercholesterolaemia (FH) mutation status on risk of coronary artery disease (CAD) over and above that predicted by low-density lipoprotein (LDL) cholesterol level alone has not been fully determined. We assessed whether positive clinical signs and genetic FH diagnosis affected CAD risk among subjects with significantly elevated LDL cholesterol levels (≥180 mg/dL, or ≥140 mg/dL in subjects <15 years of age).Three genes causative for FH (LDLR, APOB, and PCSK9) were sequenced in 636 patients with severe hypercholesterolaemia (mean age, 45 years; 300 males [47%], CAD diagnosis, 185 [29%]), and the presence of clinical FH signs (xanthoma and/or family history) were assessed. CAD prevalence was compared between four subject groups categorized based on these parameters. Compared with the reference group without FH mutations or clinical signs of FH, subjects with clinical signs of FH or FH mutations had three- to four-fold higher odds of developing CAD (odds ratio [OR], 4.6; 95% confidence interval [CI], 1.5-14.5; P = 0.0011 and OR, 3.4; 95% CI, 1.0-10.9; P = 0.0047, respectively), whereas those with clinical signs of FH and FH mutation(s) had >11-fold higher odds of developing CAD (OR, 11.6; 95% CI, 4.4-30.2; P = 1.1 × 10-5) after adjusting for known risk factors including LDL cholesterol.Our findings revealed an additive effect of positive clinical signs of FH and positive FH mutation status to CAD risk among patients with significantly elevated LDL cholesterol.
Objective Cyclosporine (CysA), a potent immunosuppressant, is associated with hypertension and nephrotoxicity. Neutral endopeptidase (NEP) degrades vasoactive peptides, including the natriuretic peptides and endothelin-1 (ET-1). We conducted the present study to determine whether or not the NEP inhibitor, ecadotril, prevents cyclosporine-induced hypertension and to clarify the mechanisms responsible for the hypotensive effects of ecadotril. Design and methods We studied the chronic effects of ecadotril (30 mg/kg per day) on blood pressure; the production of ET-1 and C-type natriuretic peptide (CNP); endothelial nitric oxide synthase (eNOS) activity; and the expression of messenger RNA (mRNA), for each substance in blood vessels of CysA-induced hypertensive rats. Results CysA (25 mg/kg per day) given for 4 weeks increased the blood pressure from 116 6 14 mmHg to 159 ± 15 mmHg, in rats. This increase was blunted by the co-administration of ecadotril (blood pressure: 134 ± 14 mmHg). CysA increased plasma NEP activity. CysA increased the production of ET-1 and the expression of ET-1 mRNA without affecting CNP synthesis and endothelin converting enzyme (ECE)-1 mRNA expression. CysA decreased the eNOS activity and eNOS mRNA levels. Addition of the NEP inhibitor decreased the synthesis of ET-1 and ET-1 mRNA levels and increased the eNOS activity and the eNOS mRNA levels. Vascular CNP synthesis and ECE-1 mRNA expression in rats treated with ecadotril did not differ from those in rats treated with CysA and ecadotril. Conclusion These results indicate that chronic NEP inhibition may prevent the CysA-induced hypertension by decreasing local ET-1 synthesis and partly increasing vascular nitric oxide production.
An inherited deficiency of low density lipoprotein (LDL) receptors in familial hypercholesterolemia (FH) is assumed to be the cause of the decreased catabolism of LDL. In contrast, in hyperthyroidism there is an increased rate of LDL catabolism. A 58-year-old female patient with heterozygous FH revealed a normal level of serum cholesterol (193mg/dl) in coexistence of hyperthyroidism. After the therapy of hyperthyroidism with radioiodine the patient's lipid profile revealed an increased concentrations of cholesterol (Whole serum 338, VLDL 68, LDL 199, HDL 42mg/dl). There was a significant inverse correlation between her serum cholesterol levels and her serum thyroxine levels (r=-0.815, p<0.01).Since LDL catabolism in vivo is thought to be mediated largely through the LDL receptor, the role of thyroid hormone in this receptor-mediated degradation of LDL was studied in human skin fibroblasts. Confluent cells were exposed to a medium containing 5% lipoprotein deficient serum prepared from a myxedematous patient by ultracentrifugation for 2 days with or without added triiodothyronine (T3). After 125I-LDL was added, the cells were incubated for 6 hours at 37°C for the determinations of 125I-LDL uptake and degradation. In the cells from 2 normal subjects, LDL uptake and degradation was enhanced 29% by preincubation with T3 (1.0μg/ml). In the cells from 2 heterozygous patients with FH, LDL uptake and degradation was enhanced 23% with T3(1.0μg/ml). While, in the cells from 2 homozygous patients with FH, no effect of T3 was observed. These results suggest that normal serum cholesterol levels in a heterozygous patient with FH result in part from an enhanced degradation of LDL by extrahepatic cells exposed to excess thyroid hormone.
