Plasma non-cholesterol sterols: a useful diagnostic tool in pediatric hypercholesterolemia.

Current guidelines strongly recommend the identification of genetic forms of hypercholesterolemia (HC) during childhood.The usefulness of non-cholesterol sterols (NCS) in the diagnosis of genetic HC has not been fully explored. Plasma NCS were measured by gas chromatography/mass spectrometry (GC/MS) in 113 children with hypercholesterolemia affected by: autosomal dominant hypercholesterolemia (ADH), familial combined hyperlipidemia(FCHL), polygenic hypercholesterolemia (PHC), and in 79 controls to evaluate: i) plasma NCS profile in different genetic HC and ii) the usefulness of NCS for the diagnosis of HC beyond current clinical criteria. ADH was characterized by raised lathosterol/total cholesterol (TC) and reduced phytosterols/TC ratios, indicative of increased cholesterol synthesis. FCHL showed a slight increase of lathosterol/TC ratio, whereas PHC showed increased phytosterols/TC ratios, indicative of increased cholesterol absorption. In a post hoc discriminant analysis of patients with HC, lipid values correctly classified the 73% (14 of 19) of ADH, whereas the inclusion of plasma sterols allowed the correct identification of all 19 patients with ADH. FCHL was not differentiated from PHC (62 versus 69%).In conclusion, NCS measurement showed that cholesterol plasma levels are related to the cholesterol synthesis in ADH and to cholesterol absorption in PHC. NCS improve the detection of ADH in pediatric patients, whereas FCHL diagnosis is not improved.

Interleukin 6 plasma levels predict with high sensitivity and specificity coronary stenosis detected by coronary angiography.

In recent years new biomarkers able to measure the coronary atherosclerotic burden have been investigated. The aim of the present study was: i) to measure plasma levels of four biomarkers: C reactive protein (CRP), soluble intercellular adhesion molecule-1 (sICAM-1), interleukin 6 (IL-6), 8-isosprostane (8-ISO), in a series of patients undergoing coronary angiography; ii) to assess the power of the biomarkers to predict critical coronary stenosis detected by angiography. The study population consisted of a group of 438 subjects undergoing coronary angiography; 160 patients with 0, 1, 2, or 3 critical vessels were selected, and biomarkers plasma levels were measured in plasma samples obtained before the procedure. The most predictive biomarker was then assayed in 120 patients with critical stenosis and 120 unmatched patients without stenosis. CRP, sICAM-1, IL-6 and 8-ISO plasma levels increased with the number of diseased vessels. All biomarkers were good predictors of critical stenosis (receiver-operator-curve [ROC] areas; CRP = 0.880, IL-6 = 0.936, sICAM-1 = 0.907, 8-ISO = 0.873). IL-6 was confirmed in an expanded sample of 240 subjects to be the best predictor with a ROC area = 0.959. With a threshold of 3.6 ng/l, a 100% sensitivity (120/120) and a 90% specificity (108/120) was observed. In conclusion, IL-6, sICAM-1, CRP and 8-ISO are predictive of CAD. IL-6 predicts critical coronary stenosis with the highest sensitivity and specificity.

Plasma non-cholesterol sterols in primary hypobetalipoproteinemia.

Primary hypobetalipoproteinemia (pHBL) is characterized by plasma cholesterol levels <5th percentile of a population distribution. Plasma non-cholesterol sterols (NCS) are markers of cholesterol liver synthesis and intestinal absorption. Plasma NCS were measured in 111 pHBL subjects, 108 low cholesterol (LC) and 253 normal cholesterol (NC) controls to gain information on cholesterol metabolism in pHBL, and to assess whether NCS measurements may aid in distinguishing pHBL from LC controls. pHBL subjects compared with LC controls were characterized by increased cholesterol absorption (campesterol/TC) while the synthesis (lathosterol/TC) was not increased. The analysis of pHBL subjects divided by gene defect showed a high campesterol/TC ratio in familial HBL (FHBL) carriers of apolipoproteinB (ApoB) truncations longer than ApoB48 and in FHBL without known gene defect ("not linked"). One not linked kindred was characterized by an increase of the 7-dehydrocholesterol/latho ratio. In a discriminant analysis plasma NCS did not improve the power of TC levels to distinguish FHBL from LC controls. In conclusion, increased cholesterol absorption was found in FHBL subjects harbouring truncations of ApoB>ApoB48, and FHBL harbouring as yet unknown molecular defects. Not linked FHBL kindred are not homogeneous in terms of plasma NCS levels. NCS cannot replace genetic HBL analysis.

Familial hypobetalipoproteinemia due to apolipoprotein B R463W mutation causes intestinal fat accumulation and low postprandial lipemia.

OBJECTIVE: Familial hypobetalipoproteinemia (FHBL) is characterized by inherited low plasma levels of apolipoprotein B (apoB)-containing lipoproteins. In this paper we investigated whether the already described APOB R463W missense mutation, a FHBL mutation able to impair the activity of microsomal triglyceride transfer protein (MTP), may cause intestinal fat accumulation and reduced postprandial lipemia. METHODS: Four out of five probands harboring APOB R463W mutation were compared with six healthy controls and six patients with celiac disease (CD). An oral fat load supplemented with retinyl palmitate (RP) was administered and a gastro-duodenal endoscopy with biopsy was performed. RESULTS: Plasma triglyceride area under curves was significantly reduced in FHBL probands compared to controls and CD patients; the proportion of absorbed RP was similar to that of CD patients. Only the intestinal biopsies of FHBL patients showed lipids accumulating within the duodenal mucosa. CONCLUSIONS: FHBL due to R463W apoB mutation is a cause of intestinal fat accumulation and postprandial lipid absorption impairment.