André Mazur

Iron absorption in dysmetabolic iron overload syndrome is decreased and correlates with increased plasma hepcidin

BACKGROUND/AIMS The dysmetabolic iron overload syndrome (DIOS) is a common disorder but its origin remains unclear. METHODS A case-control study was conducted to compare intestinal absorption of iron in 16 men with DIOS (age 53 +/- 11 years, serum ferritin 750 +/- 372 microg/l, hepatic iron 78 +/- 25 micromol/g) and in 32 age-matched controls with normal body iron stores (16 overweight subjects and 16 lean subjects). Intestinal absorption was calculated as the area under the curve (AUC) of 58Fe administered orally and correlated with plasma hepcidin and with insulin resistance parameters including HOMA. RESULTS Intestinal iron absorption was lower in DIOS (AUC = 22.4 +/- 15.9 microg/l/h) compared to both overweight controls (AUC = 40.5 +/- 29.4 microg/l/h, p=0.04) and to lean controls (AUC = 102.5 +/- 113.5 microg/l/h, p < 0.01). There was an inverse correlation between intestinal iron absorption and plasma hepcidin (r = -0.61, p < 0.001), HOMA (r = -0.35, p = 0.01) and C reactive protein (r = -0.52, p < 0.001). CONCLUSIONS In overweight subjects with normal iron stores, iron absorption is decreased through hepcidin upregulation. In patients with DIOS, this decrease is more pronounced due to an additional effect of iron excess on circulating hepcidin levels.

Role of spinal NMDA receptors, protein kinase C and nitric oxide synthase in the hyperalgesia induced by magnesium deficiency in rats

Magnesium (Mg)‐deficient rats develop a mechanical hyperalgesia which is reversed by a N‐Methyl‐D‐Aspartate (NMDA) receptor antagonist. Given that functioning of this receptor‐channel is modulated by Mg, we wondered whether facilitated activation of NMDA receptors in Mg deficiency state may in turn trigger a cascade of specific intracellular events present in persistent pain. Hence, we tested several antagonists of NMDA and non‐NMDA receptors as well as compounds interfering with the functioning of intracellular second messengers for effects on hyperalgesia in Mg‐deficient rats. Hyperalgesic Mg‐deficient rats were administered intrathecally (10 μl) or intraperitoneally with different antagonists. After drug injection, pain sensitivity was evaluated by assessing the vocalization threshold in response to a mechanical stimulus (paw pressure test) over 2 h. Intrathecal administration of MgSO4 (1.6, 3.2, 4.8, 6.6 μmol) as well as NMDA receptor antagonists such as MK‐801 (0.6, 6.0, 60 nmol), AP‐5 (10.2, 40.6, 162.3 nmol) and DCKA (0.97, 9.7, 97 nmol) dose‐dependently reversed the hyperalgesia. Chelerythrine chloride, a protein kinase C (PKC) inhibitor (1, 10.4, 104.2 nmol) and 7‐NI, a specific nitric oxide (NO) synthase inhibitor (37.5, 75, 150 μmol kg−1, i.p.) induced an anti‐hyperalgesic effect in a dose‐dependent manner. SR‐140333 (0.15, 1.5, 15 nmol) and SR‐48968 (0.17, 1.7, 17 nmol), antagonists of neurokinin receptors, produced a significant, but moderate, increase in vocalization threshold. These results demonstrate that Mg‐deficiency induces a sensitization of nociceptive pathways in the spinal cord which involves NMDA and non‐NMDA receptors. Furthermore, the data is consistent with an active role of PKC, NO and, to a lesser extent substance P in the intracellular mechanisms leading to hyperalgesia.

Bilberry anthocyanin-rich extract alters expression of genes related to atherosclerosis development in aorta of apo E-deficient mice ☆

Intake of anthocyanin-rich foods has been associated with a reduced risk of cardiovascular diseases. We recently reported that a nutritional supplementation with a bilberry anthocyanin-rich extract (BE) attenuates atherosclerotic lesion development in apolipoprotein E-deficient (apoE⁻/⁻) mice. However, the mechanism(s) of their preventive action are not completely understood. Anthocyanins may alter mRNA levels of genes related to atherosclerosis in cultured macrophages and endothelial cells, but in vivo studies remain scarce. The aim of the present study was to explore the in vivo mechanisms of action of the same bilberry extract, administered by supplementation at a nutritional level, in the aorta of apo E⁻/⁻ mice using a global transcriptomic approach. This study focused on the early stage of atherosclerosis development for better assessment of BE action on initiation mechanisms of this pathology. After a two week period, plasma lipid and antioxidant capacity were evaluated and the global genomic analysis was carried out using pangenomic microarrays. BE supplementation significantly improved hypercholesterolemia whereas the plasmatic antioxidant status remained unchanged. Nutrigenomic analysis identified 1261 genes which expression was modulated by BE in the aorta. Bioinformatic analysis revealed that these genes are implicated in different cellular processes such as oxidative stress, inflammation, transendothelial migration and angiogenesis, processes associated with atherosclerosis development/protection. Some of the most significantly down-regulated genes included genes coding for AOX1, CYP2E1 or TXNIP implicated in the regulation of oxidative stress, JAM-A coding for adhesion molecules or VEGFR2 implicate in regulation of angiogenesis. Other genes were up-regulated, such as CRB3, CLDN14 or CDH4 potentially associated with increased cell-cell adhesion and decreased paracellular permeability. These results provide a global integrated view of the mechanisms involved in the preventive action of bilberry anthocyanin-rich extract against atherosclerosis.

Major Phenolic Compounds in Olive Oil Modulate Bone Loss in an Ovariectomy/Inflammation Experimental Model

This study was conducted to determine whether the daily consumption for 84 days of tyrosol and hydroxytyrosol, the main olive oil phenolic compounds, and olive oil mill wastewater (OMWW), a byproduct of olive oil production, rich in micronutrients, may improve bone loss in ovariectomized rats (an experimental model of postmenopausal osteoporosis) and in ovariectomized rats with granulomatosis inflammation (a model set up for senile osteoporosis). As expected, an induced chronic inflammation provoked further bone loss at total, metaphyseal, and diaphyseal sites in ovariectomized rats. Tyrosol and hydroxytyrosol prevented this osteopenia by increasing bone formation ( p < 0.05), probably because of their antioxidant properties. The two doses of OMWW extracts had the same protective effect on bone ( p < 0.05), whereas OMWW did not reverse established osteopenia. In conclusion, polyphenol consumption seems to be an interesting way to prevent bone loss.

Renal Anemia Induced by Chronic Ingestion of Depleted Uranium in Rats

Kidney disease is a frequent consequence of heavy metal exposure and renal anemia occurs secondarily to the progression of kidney deterioration into chronic disease. In contrast, little is known about effects on kidney of chronic exposure to low levels of depleted uranium (DU). Study was performed with rats exposed to DU at 40 mg/l by chronic ingestion during 9 months. In the present work, a approximately 20% reduction in red blood cell (RBC) count was observed after DU exposure. Hence, three hypotheses were tested to determinate origin of RBC loss: (1) reduced erythropoiesis, (2) increased RBC degradation, and/or (3) kidney dysfunction. Erythropoiesis was not reduced after exposure to DU as revealed by erythroid progenitors, blood Flt3 ligand and erythropoietin (EPO) blood and kidney levels. Concerning messenger RNA (mRNA) and protein levels of spleen iron recycling markers from RBC degradation (DMT1 [divalent metal transporter 1], iron regulated protein 1, HO1, HO2 [heme oxygenase 1 and 2], cluster of differentiation 36), increase in HO2 and DMT1 mRNA level was induced after chronic exposure to DU. Kidneys of DU-contaminated rats had more frequently high grade tubulo-interstitial and glomerular lesions, accumulated iron more frequently and presented more apoptotic cells. In addition, chronic exposure to DU induced increased gene expression of ceruloplasmin (x12), of DMT1 (x2.5), and decreased mRNA levels of erythropoietin receptor (x0.2). Increased mRNA level of DMT1 was associated to decreased protein level (x0.25). To conclude, a chronic ingestion of DU leads mainly to kidney deterioration that is probably responsible for RBC count decrease in rats. Spleen erythropoiesis and molecules involved in erythrocyte degradation were also modified by chronic DU exposure.

Caffeic acid inhibits oxidative Stress and reduces hypercholesterolemia induced by iron overload in rats.

The effects of caffeic acid, a major phenolic compound of the diet, on oxidative stress and cholesterolemia are studied in rats submitted to oxidative stress by iron overload. Male Wistar rats were fed semi-synthetic diets containing regular (50 mg/kg diet) or high (2000 mg/kg) doses of iron with and without caffeic acid (6460 mg/kg) for 4 weeks. The high doses of iron induced an increase of lipid oxidation in the liver, as measured by thiobarbituric acid-reactive substances (TBARS), and an increase of cholesterolemia. Caffeic acid fully prevented the pro-oxidant effects of high iron doses (p < 0.001). It also reduced lipid peroxidation in rats fed the low iron dose (p < 0.05). Caffeic acid also increased vitamin E levels in plasma (2.74 micromol/L to 4.09 micromol/L for normal diet; p < 0.001; 2.78 micromol/L to 4.94 micromol/L for iron supplemented diet p < 0.001). Iron-induced hypercholesterolemia was inhibited by caffeic acid (1.07 g/L to 0.82 g/L; p < 0.001). These results demonstrate the antioxidative capacity of caffeic acid, a highly bioavailable polyphenol, in an in vivo model of oxidative stress.

Assessment of the relationship between hyperalgesia and peripheral inflammation in magnesium-deficient rats.

Magnesium-deficient rats develop simultaneously a significant lowering of nociceptive threshold and a generalized inflammation. We investigated the relationship between these two phenomena by testing drugs that are able to suppress the inflammation in this model. In weaning rats fed a magnesium-depleted diet for ten days, the nociceptive threshold was assessed by the paw pressure test and the inflammation by a clinical score. A non-steroidal anti-inflammatory drug (piroxicam); antagonists of H1 and H2 receptors (astemizole and cimetidine. respectively); a glucocorticoid (dexamethasone); an inhibitor of mastocyte degranulation (cromoglycate); and estradiol benzoate were used to block the inflammatory response. Dexamethasone and estradiol significantly suppressed the inflammation (p < 0.001 vs control group). Cromoglycate showed a delayed anti-inflammatory effect (p < 0.01 vs control group on D10). The combination of astemizole and cimetidine partially blocked the inflammation process, whereas astemizole and piroxicam were without effect. Regardless of the effect of the test drugs on inflammation, no change in the time course of hyperalgesia was observed. These data support the view that hyperalgesia induced by the magnesium-depleted diet is not a consequence of the inflammatory process.

Insight into the contribution of isoprostanoids to the health effects of omega 3 PUFAs

Omega 3 polyunsaturated fatty acids have been reported to confer beneficial health effects notably in the field of cardiovascular and inflammatory diseases. The current knowledge suggests a significant portion of the effects of omega 3 polyunsaturated fatty acids are mediated by their oxygenated metabolites. This review attempts to cover the current literature about the contribution of specific omega 3 oxygenated metabolites, namely omega 3 isoprostanoids, which are produced through free-radical mediated oxidation. A special emphasis has been given to the most biologically relevant omega 3 polyunsaturated fatty acids namely the α-linolenic, eicosapentaenoic and docosahexaenoic acids. The review includes a comprehensive description of the biosynthetic pathways, a summary of studies related to the biological significance of omega 3 isoprostanoids as well as a critical description of analytical development in the field of omega 3 isoprostanoids profiling in biological samples.

Muscle loss associated changes of oxylipin signatures during biological aging: an exploratory study from the PROOF cohort

Characterizations of the multiple mechanisms determining biological aging are required to better understand the etiology and identify early biomarkers of sarcopenia. Oxylipins refer to a large family of signaling lipids involved in the regulation of various biological processes that become dysregulated during aging. To investigate whether comprehensive oxylipin profiling could provide an integrated and fine characterization of the early phases of sarcopenia, we performed a quantitative targeted metabolomics of oxylipins in plasma of 81-year old subjects from the PROOF cohort with decreased (n = 12), stable (n = 16) or increased appendicular muscle mass (n = 14). Multivariate and univariate analyses identified significant and concordant changes of oxylipin profiles according to the muscle status. Of note, 90 % of the most discriminant oxylipins were derived from EPA and DHA and were increased in the sarcopenic subjects. The oxylipins signatures of sarcopenic subjects revealed subtle activation of inflammatory resolution pathways, coagulation processes and oxidative stress as well as the inhibition of angiogenesis. Heat maps highlighted relationships between oxylipins and the cardiometabolic health parameters which were mainly lost in sarcopenic subjects. This exploratory study supports that targeted metabolomics of oxylipins could provide relevant and subtle characterization of early disturbances associated with muscle-loss during aging.