Nadia Fatih

Iron excess limits HHIPL-2 gene expression and decreases osteoblastic activity in human MG-63 cells

SummaryIn order to understand mechanisms involved in osteoporosis observed during iron overload diseases, we analyzed the impact of iron on a human osteoblast-like cell line. Iron exposure decreases osteoblast phenotype. HHIPL-2 is an iron-modulated gene which could contribute to these alterations. Our results suggest osteoblast impairment in iron-related osteoporosis.IntroductionIron overload may cause osteoporosis. An iron-related decrease in osteoblast activity has been suggested.MethodsWe investigated the effect of iron exposure on human osteoblast cells (MG-63) by analyzing the impact of ferric ammonium citrate (FAC) and iron citrate (FeCi) on the expression of genes involved in iron metabolism or associated with osteoblast phenotype. A transcriptomic analysis was performed to identify iron-modulated genes.ResultsFAC and FeCi exposure modulated cellular iron status with a decrease in TFRC mRNA level and an increase in intracellular ferritin level. FAC increased ROS level and caspase 3 activity. Ferroportin, HFE and TFR2 mRNAs were expressed in MG-63 cells under basal conditions. The level of ferroportin mRNA was increased by iron, whereas HFE mRNA level was decreased. The level of mRNA alpha 1 collagen type I chain, osteocalcin and the transcriptional factor RUNX2 were decreased by iron. Transcriptomic analysis revealed that the mRNA level of HedgeHog Interacting Protein Like-2 (HHIPL-2) gene, encoding an inhibitor of the hedgehog signaling pathway, was decreased in the presence of FAC. Specific inhibition of HHIPL-2 expression decreased osteoblast marker mRNA levels. Purmorphamine, hedgehog pathway activator, increased the mRNA level of GLI1, a target gene for the hedgehog pathway, and decreased osteoblast marker levels. GLI1 mRNA level was increased under iron exposure.ConclusionWe showed that in human MG-63 cells, iron exposure impacts iron metabolism and osteoblast gene expression. HHIPL-2 gene expression modulation may contribute to these alterations. Our results support a role of osteoblast impairment in iron-related osteoporosis.

Mid-infrared spectroscopy of serum, a promising non-invasive method to assess prognosis in patients with ascites and cirrhosis

Background & aims Prognostic tests are critical in the management of patients with cirrhosis and ascites. Biological tests or scores perform poorly in that situation. Mid-infrared fibre evanescent wave spectroscopy (MIR-FEWS) which allows for global serum metabolic profiling may provide more relevant information by measuring a wider range of metabolic parameters in serum. Here we present the accuracy of a MIR-FEWS based predictive model for the prognosis of 6 months survival in patients with ascites and cirrhosis. Methods Patients with ascites were prospectively included and followed up for 6 months. MIR-FEWS spectra were measured in serum samples. The most informative spectral variables obtained by MIR-FEWS were selected by FADA algorithm and then used to build the MIR model. Accuracy of this model was assessed by ROC curves and 90%/10% Monte Carlo cross-validation. MIR model accuracy for 6 months survival was compared to that of the Child-Pugh and MELD scores. Results 119 patients were included. The mean age was 57.36±13.70, the MELD score was 16.32±6.26, and the Child-Pugh score was 9.5±1.83. During follow-up, 23 patients died (20%). The MIR model had an AUROC for 6 months mortality of 0.90 (CI95: 0.88–0.91), the MELD 0.77 (CI95: 0.66–0.89) and Child-Pugh 0.76 (CI95: 0.66–0.88). MELD and Child-Pugh AUROCs were significantly lower than that of the MIR model (p = 0.02 and p = 0.02 respectively). Multivariate logistic regression analysis showed that MELD (p<0.05, OR:0.86;CI95:0.76–0.97), Beta blockers (p = 0.036;OR:0.20;CI95:0.04–0.90), and the MIR model (p<0.001; OR:0.50; CI95:0.37–0.66), were significantly associated with 6 months mortality. Conclusions In this pilot study MIR-FEWS more accurately assess the 6-month prognosis of patients with ascites and cirrhosis than the MELD or Child-Pugh scores. These promising results, if confirmed by a larger study, suggest that mid infrared spectroscopy could be helpful in the management of these patients.

Curcuma decreases serum hepcidin levels in healthy volunteers: a placebo‐controlled, randomized, double‐blind, cross‐over study

Hepcidin, secreted by hepatocytes, controls iron metabolism by limiting iron egress in plasma. Hepcidin is upregulated during inflammation through the activation of the signal transducer and activator of transcription 3 (STAT3) transduction pathway, which decreases iron bioavailability and may explain the anemia of chronic inflammatory disease. In vitro, it has been shown that curcumin can decrease hepcidin synthesis by decreasing STAT3 activity. We conducted a proof‐of‐concept study to assess the effect of curcuma on hepcidin synthesis in human. This was a placebo‐controlled, randomized, double‐blind, cross‐over, two‐period study performed in 18 healthy male volunteers. Subjects received a single oral dose of 6 g curcuma containing 2% of curcumin or placebo. Serum hepcidin and iron parameters were assessed repeatedly until 48 h after dosing. When compared with a placebo curcuma decreased hepcidin levels significantly at 6 h (−19%, P = 0.004), 8 h (−17%, P = 0.009), and 12 h (−17%, P = 0.007) and tended to decrease hepcidin at 24 h (−15%, P = 0.076). Curcuma also significantly increased serum ferritin levels at 6 and 8 h (+7% for both times, P = 0.018, 0.030, respectively) and had no effects on serum iron, transferrin, and transferrin saturation. This pilot study showed that curcuma decreases serum hepcidin levels in human and supports the idea that curcuma could be useful in treating hepcidin overproduction during inflammatory processes. Confirmatory studies in patients with chronic inflammation are now required to determine the optimal dose and therapeutic scheme of curcuma.

Ferroportine et pathologies du métabolisme du fer

La ferroportine, proteine qui s’insere dans la membrane des cellules, joue un role dans l’exportation du fer a partir des cellules vers le plasma. Ses sites d’expression majeurs sont la membrane basale des enterocytes et la membrane des macrophages, cellules qui sont les principales sources de fer pour le plasma. La ferroportine est donc un acteur moleculaire majeur du controle de la biodisponibilite du fer plasmatique. La regulation de son expression depend de mecanismes : i) transcriptionnels, controlant le niveau d’ARNm ; ii) traductionnels, modulant la synthese de la proteine ; et iii) post-traductionnels, controlant sa stabilite et son activite. Ce dernier mecanisme depend du niveau d’hepcidine plasmatique qui interagit avec la ferroportine et provoque sa degradation. Des mutations du gene codant la ferroportine entrainent des surcharges en fer a transmission dominante. Certaines mutations, les plus frequentes, entrainent une diminution de l’expression ou de l’activite de la proteine a la membrane cellulaire et sont responsables de surcharges en fer a saturation de la transferrine normale ou basse, le fer etant retenu dans les cellules. Les autres, plus rares, entrainent une impossibilite d’interaction avec l’hepcidine, et donc, un tableau clinique en tout point similaire a celui des hemochromatoses genetiques liees a une baisse de l’expression de l’hepcidine dont l’hemochromatose HFE. Une meilleure connaissance des mecanismes regulant l’expression de la ferroportine et de ceux impliques dans son interaction avec l’hepcidine permettra d’ameliorer la prise en charge des pathologies du metabolisme du fer.