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Dietary Iron Overload and Hfe^-/- Related Hemochromatosis Alter Hepatic Mitochondrial Function.

ABSTRACT: Iron is an essential co-factor for many cellular metabolic processes, and mitochondria are main sites of utilization. Iron accumulation promotes production of reactive oxygen species (ROS) via the catalytic activity of iron species. Herein, we investigated the consequences of dietary and genetic iron overload on mitochondrial function. C57BL/6N wildtype and Hfe^-/- mice, the latter a genetic hemochromatosis model, received either normal diet (ND) or high iron diet (HI) for two weeks. Liver mitochondrial respiration was measured using high-resolution respirometry along with analysis of expression of specific proteins and ROS production. HI promoted tissue iron accumulation and slightly affected mitochondrial function in wildtype mice. Hepatic mitochondrial function was impaired in Hfe^-/- mice on ND and HI. Compared to wildtype mice, Hfe^-/- mice on ND showed increased mitochondrial respiratory capacity. Hfe^-/- mice on HI showed very high liver iron levels, decreased mitochondrial respiratory capacity and increased ROS production associated with reduced mitochondrial aconitase activity. Although Hfe^-/- resulted in increased mitochondrial iron loading, the concentration of metabolically reactive cytoplasmic iron and mitochondrial density remained unchanged. Our data show multiple effects of dietary and genetic iron loading on mitochondrial function and linked metabolic pathways, providing an explanation for fatigue in iron-overloaded hemochromatosis patients, and suggests iron reduction therapy for improvement of mitochondrial function.

SUBMITTER: Fischer C

PROVIDER: S-EPMC8615072 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundScreening program participants with iron overload (IO) phenotypes without HFE p.C282Y/p.C282Y are incompletely characterized.MethodsWe studied white participants who had IO phenotypes without p.C282Y/p.C282Y in post-screening clinical examinations (CE). We defined IO phenotypes as a) elevated serum ferritin (SF) and transferrin saturation (TS) at screening and CE, and b) absence of IO treatment, anemia, transfusion >10 units, alcohol intake >30 g/d, hepatitis B or C, and pregnancy. We defined IO-related disease as elevated alanine or aspartate aminotransferase (ALT/AST) or swelling/tenderness of 2nd/3rd metacarpophalangeal (MCP) joints. All participants had HFE p.C282Y and p.H63D genotyping.ResultsThere were 32 men and 26 women (mean age 54±16 y). Median food/supplemental iron intakes were 14.3/0.0 mg/d. Relative risks of HFE genotypes were 12.9 (p.C282Y/p.H63D), 3.0 (p.H63D/p.H63D), 1.9 (p.C282Y/wt), 0.9 (p.H63D/wt), and 0.5 (wt/wt) compared to 42,640 white screening participants without IO phenotypes or p.C282Y/p.C282Y. Regression on SF revealed positive associations: MCV (p = 0.0006; β coefficient = 0.4531); swelling/tenderness of MCP joints (p = 0.0033; β = 0.3455); and p.H63D/wt (p = 0.0015; β = 0.4146). IO-related disease (18 elevated ALT/AST, one swelling/tenderness of MCP joints) occurred in 19 participants (7 men, 12 women). Median MCV was higher in participants with IO-related disease (97 fL vs. 94 fL; p = 0.0007). Logistic regression on IO-related disease revealed a significant association with diabetes (p = 0.0416; odds ratio 18.9 (95% confidence interval 1.0, 341.1)).ConclusionsIn the present 58 screening program participants who had IO phenotypes without HFE p.C282Y/p.C282Y, relative risks of HFE genotypes p.C282Y/p.H63D, p.H63D/p.H63D, and p.C282Y/wt were significantly higher than in 42,640 white screening participants with neither IO phenotypes nor p.C282Y/p.C282Y. SF was significantly associated with MCV, swelling/tenderness of 2nd/3rd MCP joints, and p.H63D/wt. IO-related disease was significantly associated with MCV and diabetes.

Project description:BACKGROUND:Patients with hepatitis C virus (HCV) and hepatocellular carcinoma (HCC) may or not develop iron overload (IO), which is associated with worst prognosis, because can cause serious damage to organs. HFE gene controls the iron uptake from gut, particularly in patients with hereditary hemochromatosis (HH). AIM:To identify associations between HFE coding region in patients exhibiting hereditary hemochromatosis and in diseases associated with acquired IO. METHODS:We sequenced exons 2 to 5 and boundary introns of HFE gene, evaluating all polymorphic sites in patients presenting hereditary (hemochromatosis) or acquired iron overload HCV and HCC) and in healthy controls, using Sanger sequencing. We also determined the ensemble of extended haplotype in healthy control individuals, including several major histocompatibility complex loci, using sequence specific probes. Haplotype reconstruction was performed using the Arlequin and Phase softwares, and linkage disequilibrium (LD) between histocompatibility loci and HFE gene was performed using the Haploview software. RESULTS:The HFE*003 allele was overrepresented (f = 71%) and HFE*001 allele was underrepresented (f = 14%) in HH patients compared to all groups. A strong linkage disequilibrium was observed among the H63D-G, IVS2(+4)-C and C282Y-G gene variants, particularly in HH; however, the mutation IVS2(+4)T>C was not directly associated with HH susceptibility. The HFE*001/HFE*002 genotype conferred susceptibility to HCC in HCV patients exhibiting IO (P = 0.02, OR = 14.14). Although HFE is telomeric to other histocompatibility genes, the H63D-G/IVS2(+4)-C (P ? 0.00001/P ? 0.0057) combination was in LD with HLA-B*44 allele group in healthy controls. No LD was observed between HFE alleles and other major histocompatibility loci. CONCLUSION:A differential HFE association was observed for HH and for diseases associated with acquired IO (HCV, HCC). Since HFE is very distant from other histocompatibility loci, only weak associations were observed with these alleles.

Project description:ImportanceHereditary hemochromatosis is predominantly caused by the HFE p.C282Y homozygous pathogenic variant. Liver carcinoma and mortality risks are increased in individuals with clinically diagnosed hereditary hemochromatosis, but risks are unclear in mostly undiagnosed p.C282Y homozygotes identified in community genotyping.ObjectiveTo estimate the incidence of primary hepatic carcinoma and death by HFE variant status.Design, setting, and participantsCohort study of 451 186 UK Biobank participants of European ancestry (aged 40-70 years), followed up from baseline assessment (2006-2010) until January 2018.ExposuresMen and women with HFE p.C282Y and p.H63D genotypes compared with those with neither HFE variants.Main outcomes and measuresTwo linked co-primary outcomes (incident primary liver carcinoma and death from any cause) were ascertained from follow-up via hospital inpatient records, national cancer registry, and death certificate records, and from primary care data among a subset of participants for whom data were available. Associations between genotype and outcomes were tested using Cox regression adjusted for age, assessment center, genotyping array, and population genetics substructure. Kaplan-Meier lifetable probabilities of incident diagnoses were estimated from age 40 to 75 years by HFE genotype and sex.ResultsA total of 451 186 participants (mean [SD] age, 56.8 [8.0] years; 54.3% women) were followed up for a median (interquartile range) of 8.9 (8.3-9.5) years. Among the 1294 male p.C282Y homozygotes, there were 21 incident hepatic malignancies, 10 of which were in participants without a diagnosis of hemochromatosis at baseline. p.C282Y homozygous men had a higher risk of hepatic malignancies (hazard ratio [HR], 10.5 [95% CI, 6.6-16.7]; P < .001) and all-cause mortality (n = 88; HR, 1.2 [95% CI, 1.0-1.5]; P = .046) compared with men with neither HFE variant. In lifetables projections for male p.C282Y homozygotes to age 75 years, the risk of primary hepatic malignancy was 7.2% (95% CI, 3.9%-13.1%), compared with 0.6% (95% CI, 0.4%-0.7%) for men with neither variant, and the risk of death was 19.5% (95% CI, 15.8%-24.0%), compared with 15.1% (95% CI, 14.7%-15.5%) among men with neither variant. Among female p.C282Y homozygotes (n = 1596), there were 3 incident hepatic malignancies and 60 deaths, but the associations between homozygosity and hepatic malignancy (HR, 2.1 [95% CI, 0.7-6.5]; P = .22) and death (HR, 1.2 [95% CI, 0.9-1.5]; P = .20) were not statistically significant.Conclusions and relevanceAmong men with HFE p.C282Y homozygosity, there was a significantly increased risk of incident primary hepatic malignancy and death compared with men without p.C282Y or p.H63D variants; there was not a significant association for women. Further research is needed to understand the effects of early diagnosis and treatment.

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Dietary Iron Overload and Hfe^-/- Related Hemochromatosis Alter Hepatic Mitochondrial Function.

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Dietary Iron Overload and Hfe-/- Related Hemochromatosis Alter Hepatic Mitochondrial Function.

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OmicsDI is part of the ELIXIR infrastructure

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Dietary Iron Overload and Hfe^-/- Related Hemochromatosis Alter Hepatic Mitochondrial Function.