Energy intake is associated with endotoxemia in apparently healthy men.

BACKGROUND: The bridge between food intake and weight is not fully understood. Recently, the role of gut microbiota and bacterial lipopolysacharides (LPS) in weight has been noted. OBJECTIVE: The objective was to evaluate the relation between plasma LPS concentration and food intake. DESIGN: A dietary survey was conducted in 1015 subjects randomly recruited in France. The participants were given oral and written instructions on how to keep a consecutive 3-d food record. Plasma LPS was measured in a subsample of 201 men. To assess, under controlled conditions, the differential impact of various high-energy diets, plasma LPS concentrations were measured in mice fed a high-fat or a high-carbohydrate diet over a 4-wk period. RESULTS: In humans, no significant relation was observed between cardiovascular disease risk factors, carbohydrate and protein intakes, and plasma LPS concentration. Conversely, positive correlations were observed with fat and energy intakes. In a multivariate analysis, endotoxemia was independently associated with energy intake. Compared with the control mice, mice fed a high-energy diet showed an increase in plasma LPS. However, in mice fed a high-carbohydrate diet, the increase in plasma LPS was blunted compared with mice fed a high-fat diet. CONCLUSIONS: In this large sample of healthy men from a population-based sample, we found a link between food intake and plasma LPS. Experimental data suggest that fat was more efficient in transporting bacterial LPS from the gut lumen into the bloodstream. The results of this study add to the knowledge of mechanisms responsible for relations between food intake and metabolic diseases.

Association of APOC3 polymorphisms with both dyslipidemia and lipoatrophy in HAART-receiving patients.

The incidence and the magnitude of lipodystrophy and dyslipidemia in HIV-treated people reported in previous studies are very variable. Several predisposing factors have been identified, but there are few data on genetic factors. To search for a correlation between APOC3 polymorphisms and lipid disorders and lipodystrophy in HIV patients under d4T and protease inhibitors (PI)-containing HAART, we designed a monocenter, cross-sectional study in a University Hospital in Southern France during the period 2001-2004. Forty patients under HAART were included, with d4T for > or = 2 years and PI for > or = 1 year. We determined body mass composition by DXA, lipoprotein markers, and the -455/-482 apo C3 genotypes. Carriers of APOC3 variant alleles (-455 1/-482 1) displayed higher levels of triglycerides (3.72 vs. 2.57 mmol/liter), apo C3 (45.3 vs. 34.5 mg/liter), and apo E (130.2 vs. 66.5 mg/liter) and a lower fat mass (13.9 vs. 19.7%) than patients with nonvariant alleles (-455 0/-482 0). APOC3 polymorphisms might be associated with both dyslipidemia and lipoatrophy in HAART-treated patients.

Impact of genetic polymorphisms on the risk of lipid disorders in patients on anti-HIV therapy.

Active anti-HIV therapy can induce hypertriglyceridemia, low high-density lipoprotein (HDL) and insulin resistance, eventually accompanied by clinical lipodystrophy, associated loss of subcutaneous adipose tissue and an increase in abdominal adiposity. The frequency of these metabolic disorders is approximately 50% and host genetic factors might confer particular susceptibility. Variants of apolipoproteins (apo) A5 and C3, interacting with APOE genotypes, have been associated with the severity of antiretroviral therapy-induced dyslipidemia and with occurrence of lipodystrophy, and for APOC3, with objective criteria of fat redistribution. Genetic polymorphisms of the nuclear transcription-factor sterol response element-binding proteins (SREBP1c) and of tumor necrosis factor-alpha (TNFalpha) have yielded contrasting results. Other candidate genes will be explored to define a pharmacogenomic strategy to identify patients at high risk of metabolic disorders upon antiretroviral therapy.

Interleukin 6 is associated with subclinical atherosclerosis: a link with soluble intercellular adhesion molecule 1.

BACKGROUND: Among the markers of inflammation, a cytokine, interleukin (IL)-6, promotes the expression of intercellular adhesion molecule 1 (ICAM-1), C-reactive protein (CRP) synthesis, and leads to a series of procoagulant actions with potential major implications on the progression of atherosclerosis. AIM OF THE STUDY: To analyse in a population-based study, the relationship between IL-6 and atherosclerotic lesions and the role of serum ICAM-1 and CRP on this relationship. POPULATION: Among 1015 individuals randomly recruited between 1995 and 1997 in Haute-Garonne, a French region with a low cardiovascular risk, 953 subjects with complete data for all measurements were analysed. Common carotid intima-media thickness (IMT) and the presence of plaques in the carotid and femoral arteries were assessed by ultrasonography. RESULTS: Quartiles of IL-6, serum ICAM-1 and CRP were positively associated with plaques and IMT. After adjustment for traditional risk factors, IL-6 (P < 0.001) and serum ICAM-1 (P < 0.002) remained positively associated with plaques but not CRP (P = 0.20). Neither IL-6, nor serum ICAM-1, nor CRP were independently associated with IMT. When serum ICAM-1 was entered into the model in addition to traditional risk factors and IL-6, the percentage of variance in the number of plaques explained by the model did not increase significantly. CONCLUSION: IL-6 levels are associated with subclinical atherosclerotic lesions independently of traditional risk factors; the influence of IL-6 on ICAM-1 secretion may play a role in this association. These results argue the interest of IL-6 in the stratification of cardiovascular risk.

Production of lysophosphatidic acid in blister fluid: involvement of a lysophospholipase D activity.

Lysophosphatidic acid (LPA) is present in abundance in serum resulting from platelet activation and is also found in other biological fluids. LPA controls numerous cellular responses and plays a role in specific functions such as wound healing, especially in the skin. Nevertheless, its presence in the skin has never been investigated. Since re-epithelialization occurs after blister rupture, we tested the presence of endogenous LPA in blister fluid and investigated a possible mechanism for its biosynthesis and biological functions. Using a radioenzymatic assay, LPA was detected in 33 blister fluids originating from 24 bullous dermatoses, and at higher concentrations than in plasma. In parallel, blister fluids contained a lysophospholipase D (LPLD) activity but no detectable phospholipase A2 activity. The expressions of the LPLD autotaxin (ATX) and of LPA1-receptor (LPA1-R) were greatly increased in blister skin when compared with normal skin. Finally, LPA was found to have a positive effect on the migration of cultured keratinocytes. These results show that LPA is present in blister fluid synthesized by the LPLD ATX. Due to its ability to enhance keratinocyte migration, LPA in blister fluid could, via the LPA1-R, play an important role in re-epithelialization occurring after blister rupture.

Bactericidal properties of group IIa secreted phospholipase A(2) against Pseudomonas aeruginosa clinical isolates.

It has been shown that human group IIa secreted phospholipase A(2) (sPLA(2)), found at high levels in inflammatory fluids, displays direct bactericidal properties against Gram-positive bacteria, while activity against Gram-negative bacteria requires the complement system or additional co-factors produced by neutrophils. Pseudomonas aeruginosa, an increasingly prevalent opportunistic human pathogen, is the most common Gram-negative rod found in cystic fibrosis lung infections, where it is associated with an inflammatory environment. Because murine intestinal group II sPLA(2) produced by Paneth cells has been shown to be directly bactericidal against Gram-negative bacteria, IIa sPLA(2) activity against P. aeruginosa clinical isolates was evaluated and provides the first evidence that the enzyme can be fully bactericidal in a concentration- and time-dependent manner against Gram-negative rods. Furthermore, it was demonstrated that these bactericidal properties were unaffected by high protein and salt concentrations, as observed in cystic fibrosis secretions, and that bacterial killing paralleled phospholipid hydrolysis. Finally, no cytotoxicity was observed when IIa sPLA(2) was incubated with human pulmonary cells, highlighting its potential use to synergize bactericidal antibiotics by promoting sublethal alterations of the bacterial cell wall.

Insulin levels measured with an insulin-specific assay in patients with fasting hypoglycaemia related to endogenous hyperinsulinism.

OBJECTIVE: The finding of insulin levels above a minimum threshold at the time of symptomatic hypoglycaemia is crucial in the diagnosis of endogenous hyperinsulinism. The aim of this study was to evaluate insulin levels at the time of hypoglycaemia with an insulin-specific assay in such patients. DESIGN AND METHODS: We measured insulin levels in 15 patients with fasting hypoglycaemia related to endogenous hyperinsulinism using an insulin-specific immunoradiometric assay (IRMA) without any significant cross-reaction with intact proinsulin. RESULTS: Insulin levels were below 6 mIU/l in all the samples taken at the time of symptomatic hypoglycaemia in 6/15 patients, and in some of the samples in three patients; insulin levels were below 3 mIU/l in samples from 5 patients. C-peptide levels were above 0.6 ng/ml in all these samples. The lowest proinsulin level was 35 pmol/l. Insulin levels were measured with a less specific RIA (40% cross-reaction with proinsulin) in 8/15 patients and were above 6 mIU/l in all samples in seven patients, and all but one sample in the 8th patient. Mean concomitant C-peptide and insulinoma size were lower in those patients with insulin-IRMA levels below 6 mIU/l. CONCLUSION: Symptomatic hypoglycaemia below 0.45 g/l can result from insulin levels below 6 or even 3 mIU/l; lower insulin levels and secretion could be observed preferentially in small insulinomas. If an insulin assay devoid of any significant cross-reaction with intact proinsulin is employed, measuring C-peptide (and/or proinsulin) levels at the time of symptomatic hypoglycaemia is mandatory to make the diagnosis of endogenous hyperinsulinism.

Obesity and alcohol modulate the effect of apolipoprotein E polymorphism on lipids and insulin.

OBJECTIVE: To assess the interaction between apolipoprotein (apo) E polymorphism, alcohol consumption, and BMI on insulin, lipid, and lipoprotein levels in men. RESEARCH METHODS AND PROCEDURES: Cross-sectional study of 266 healthy men without hypolipidemic or antidiabetic drug treatment. BMI, apo E polymorphisms, insulin, and lipid and lipoprotein levels were assessed. Alcohol consumption was assessed by questionnaire. epsilon2/epsilon4 carriers were excluded from the analysis. RESULTS: On bivariate analysis, epsilon2 carriers had lower levels of total and low-density lipoprotein cholesterol and higher levels of apo E and lipoparticle B:E than epsilon3 carriers, the opposite being found for epsilon4 carriers compared with epsilon3 carriers; epsilon4 carriers also had significantly higher insulin levels. On multivariate analysis, significant interactions (p < 0.04) between apo E alleles and increased BMI were found for total and low-density lipoprotein cholesterol and insulin levels, the increase in those parameters with BMI being stronger among epsilon4 carriers than among epsilon3 or epsilon2 carriers. Significant interactions (p < 0.02) between apo E alleles and alcohol consumption were also found for apo B levels, which increased in epsilon2 carriers but remained relatively stable in epsilon3 and tended to decrease in epsilon4 carriers. DISCUSSION: These data suggest that effects of apo E alleles on lipids and insulin levels are partly dependent on environmental variables such as BMI and alcohol intake. These findings highlight the importance of gene x environment interactions on the deleterious effect of obesity on cardiovascular risk factors.

Effect of apolipoprotein E alleles and angiotensin-converting enzyme insertion/deletion polymorphisms on lipid and lipoprotein markers in middle-aged men and in patients with stable angina pectoris or healed myocardial infarction.

The effects of the apolipoprotein E epsilon and angiotensin-converting enzyme insertion/deletion alleles on lipid levels and hypolipidemic drug treatment was assessed in 400 men with stable angina pectoris or healed myocardial infarction and 338 healthy controls. The data indicate that epsilon4 carriers have increased total and low-density lipoprotein cholesterol levels, that the epsilon4 allele unfavorably decreases the efficiency of statin treatment, and that the angiotensin-converting enzyme insertion/deletion polymorphism exerts no significant effect, with the exception of an increase in apolipoprotein E levels.

Apoptotic effect of sphingosine 1-phosphate and increased sphingosine 1-phosphate hydrolysis on mesangial cells cultured at low cell density.

The lipid mediator sphingosine 1-phosphate (S1P) may alter the proliferation of mesangial cells during pathophysiological processes. Here, S1P stimulated proliferation of rat mesangial cells and phosphorylation of MAPKs at subconfluent cell density. Both effects were inhibited by pertussis toxin treatment. Mesangial cells expressed several S1P receptors of the endothelial differentiation gene family: EDG-1, -3, -5, and -8. Conversely, S1P induced apoptosis at low cell density (2 x 10(4) cells/cm(2)), which was demonstrated by flow cytometry and Hoechst staining. Apoptosis was observed also in quiescent or growing cells and was not reverted by lysophosphatidic acid or platelet-derived growth factor. S1P enhanced phosphorylation of SAPKs. Incubation with [(33)P]S1P, [(3)H]S1P, and [(3)H]sphingosine demonstrated increased S1P hydrolysis, resulting in enhanced intracellular sphingosine levels and decreased S1P levels. A rise in total ceramide levels was also observed; however, ceramide did not originate from [(3)H]sphingosine, and S1P-induced apoptosis was not inhibited by fumonisin B, precluding involvement of de novo ceramide synthesis in apoptosis. Therefore, we suggest that sphingosine accumulation and decreased S1P are primarily responsible for S1P-induced apoptosis. In conclusion, incubation of low-density mesangial cells with S1P results in apoptosis, presumably due to increased S1P hydrolysis.