Iron metabolism in patients with anorexia nervosa: elevated serum hepcidin concentrations in the absence of inflammation.

BACKGROUND: Only a few studies based on small cohorts have been carried out on iron status in anorexia nervosa (AN) patients. OBJECTIVE: The aim of this study was to evaluate the role of hepcidin in hyperferritinemia in AN adolescents. DESIGN: Twenty-seven adolescents hospitalized for AN in the pediatric inpatient unit of Ambroise Paré Academic Hospital were enrolled in the study. The control group comprised 11 patients. Hematologic variables and markers of iron status, including serum hepcidin, were measured before and after nutritional rehabilitation. RESULTS: The mean age of patients was 14.4 y. Except for 2 AN patients and 1 control patient, all patients presented normal hemoglobin, vitamin B-12, and folate concentrations. Markers of inflammation and cytokines were normal throughout the study. None of the muscular lysis markers were elevated. Most AN patients had normal serum iron concentrations on admission. Serum ferritin concentrations were significantly higher in patients than in control subjects (198 compared with 49 µg/L, respectively; P < 0.001). The median hepcidin concentration was significantly higher in AN patients than in the control group (186.5 compared with 39.5 µg/L, respectively; P = 0.002). There was a highly significant correlation between ferritinemia and serum hepcidin concentrations (P < 0.0001). After nutritional rehabilitation, a significant reduction was observed (P = 0.004) in serum ferritin. Serum hepcidin analyzed in a smaller number of patients also returned to within the normal range. CONCLUSIONS: Hepcidin and ferritin concentrations were higher in the serum of AN patients, without any evidence of iron overload or inflammation. These concentrations returned to normal after nutritional rehabilitation. These results suggest that nutritional stress induced by malnourishment in the hepatocyte could be yet another mechanism that regulates hepcidin.

Melatonin and environmental lighting regulate ALA-S gene expression and So porphyrin biosynthesis in the rat harderian gland.

The main porphyrin in rodent Harderian glands (HGs) is the heme precursor protoporphyrin IX (PPIX). Rhythmic variations in PPIX levels have yet to be studied in rodent HGs. Moreover, the mode of regulation of heme biosynthesis in this organ is poorly documented in the rat. The aim of this study was to determine day-night PPIX levels as well as day-night activity and mode of expression of the porphyrinogenic enzymes delta-aminolevulinate synthase (ALA-S) and ferrochelatase (Fech) in the rat HG. The mRNA expression of ABCG2/Bcrp1 was also investigated. Male Wistar rats acclimatized to 12 h light (L): 12 h dark (D) cycles were sacrificed in the middle of both the L and D spans, and HG and liver tissues were collected. We report here that the HG contains an extremely high level of PPIX, 630- to 670-fold higher than in the liver, without a day-night difference, which is the consequence of both low Fech gene expression (5- to 7-fold lower than in the liver) and ALA-S over-expression (4- to 7-fold higher in the HG than liver). Fech and PPIX transporter ABCG2/Bcrp1 do not exhibit day-night variation, whereas HG ALA-S levels are significantly higher during the scotophase. Interestingly, when melatonin (10 mg/kg) is administered in the middle of the light phase, it increases ALA-S mRNA levels in the HG to the ones observed during the middle of the D span. Continuous light exposure abolishes the day-night ALA-S variation in the HG that is observed under standard 12 L:12 D conditions. Our results suggest that melatonin and environmental lighting regulate ALA-S gene expression in the rat HG.

Contribution of a common single-nucleotide polymorphism to the genetic predisposition for erythropoietic protoporphyria.

Erythropoietic protoporphyria (EPP) is an inherited disorder of heme biosynthesis that results from a partial deficiency of ferrochelatase (FECH). Recently, we have shown that the inheritance of the common hypomorphic IVS3-48C allele trans to a deleterious mutation reduces FECH activity to below a critical threshold and accounts for the photosensitivity seen in patients. Rare cases of autosomal recessive inheritance have been reported. We studied a cohort of 173 white French EPP families and a group of 360 unrelated healthy subjects from four ethnic groups. The prevalences of the recessive and dominant autosomal forms of EPP are 4% (95% confidence interval 1-8) and 95% (95% confidence interval 91-99), respectively. In 97.9% of dominant cases, an IVS3-48C allele is co-inherited with the deleterious mutation. The frequency of the IVS3-48C allele differs widely in the Japanese (43%), southeast Asian (31%), white French (11%), North African (2.7%), and black West African (<1%) populations. These differences can be related to the prevalence of EPP in these populations and could account for the absence of EPP in black subjects. The phylogenic origin of the IVS3-48C haplotypes strongly suggests that the IVS3-48C allele arose from a single recent mutational event. Estimation of the age of the IVS3-48C allele from haplotype data in white and Asian populations yields an estimated age three to four times younger in the Japanese than in the white population, and this difference may be attributable either to differing demographic histories or to positive selection for the IVS3-48C allele in the Asian population. Finally, by calculating the KA/KS ratio in humans and chimpanzees, we show that the FECH protein sequence is subject to strong negative pressure. Overall, EPP looks like a Mendelian disorder, in which the prevalence of overt disease depends mainly on the frequency of a single common single-nucleotide polymorphism resulting from a unique mutational event that occurred 60,000 years ago.