Ferroportin (SLC40A1) Q248H mutation is associated with lower circulating serum hepcidin levels in Rwandese HIV-positive women

Interplay between systemic inflammation, anemia, and mycobacterial dissemination and its impact on mortality in TB-associated HIV: a prospective cohort study

Introduction

Anemia frequently affects people living with HIV (PLHIV). Nevertheless, the impact of anemia on treatment outcomes of patients with HIV-associated tuberculosis (TB) and the underlying molecular profiles are not fully characterized. The aim of this study was to investigate the interplay between anemia, the systemic inflammatory profile, dissemination of TB and death in HIV-TB patients in an ad hoc analysis of results from a prospective cohort study.

Methods

496 hospitalized PLHIV ≥18 years old, with CD4 count <350 cells/μL and high clinical suspicion of new TB infection were enrolled in Cape Town between 2014-2016. Patients were classified according to anemia severity in non-anemic, mild, moderate, or severe anemia. Clinical, microbiologic, and immunologic data were collected at baseline. Hierarchical cluster analysis, degree of inflammatory perturbation, survival curves and C-statistics analyses were performed.

Results

Through the analysis of several clinical and laboratory parameters, we observed that those with severe anemia exhibited greater systemic inflammation, characterized by high concentrations of IL-8, IL-1RA and IL-6. Furthermore, severe anemia was associated with a higher Mtb dissemination score and a higher risk of death, particularly within 7 days of admission. Most of the patients who died had severe anemia and had a more pronounced systemic inflammatory profile.

Discussion

Therefore, the results presented here reveal that severe anemia is associated with greater TB dissemination and increased risk of death in PLHIV. Early identification of such patients through measurement of Hb levels may drive closer monitoring to reduce mortality. Future investigations are warranted to test whether early interventions impact survival of this vulnerable population.

Ferroportin Q248H mutation was not found to be protective against malaria and anemia in children under 5 years living in South Kivu/Democratic Republic of Congo, an endemic area of Plasmodium infection

Background

Materials and methods

Results

Conclusion

•

Frequency of ferroportin Q248H is high in African population.

•

Ferroportin has been described to protect red blood cells against oxidative stress and malaria infection.

•

Ferroportin allele frequency was similar in anemic and non-anemic children.

•

No difference according to ferroportin allele frequency was observed among children in endemic area of Plasmodium infection.

•

Ferroportin Q248H mutation, G6PD deficiency and sickle cell anemia did not affect susceptibility to malaria in endemic area.

HIV-1 infection in sickle cell disease and sickle cell trait: role of iron and innate response

INTRODUCTION

Sickle cell disease (SCD), an inherited hemoglobinopathy, affects primarily African Americans in the U.S.A. In addition, about 15% African Americans carry sickle cell trait (SCT). Despite the risk associated with blood transfusions, SCD patients have lower risk of acquiring HIV-1 infection. SCT individuals might also have some protection from HIV-1 infection.

AREAS COVERED

Here, we will review recent and previous studies with the focus on molecular mechanisms that might underlie and contribute to the protection of individuals with SCD and SCT from HIV-1 infection. As both of these conditions predispose to hemolysis, we will focus our discussion on the effects of systemic and intracellular iron on HIV-1 infection and progression. We will also review changes in iron metabolism and activation of innate antiviral responses in SCD and SCT and their effects on HIV-1 infection.

EXPERT OPINION

Previous studies, including ours, showed that SCD might protect from HIV-1 infection. This protection is likely due to the upregulation of complex protein network in response to hemolysis, hypoxia and interferon signaling. These findings are important not only for HIV-1 field but also for SCD cure efforts as antiviral state of SCD patients may adversely affect lentivirus-based gene therapy efforts.

An 8-ferroptosis-related genes signature from Bronchoalveolar Lavage Fluid for prognosis in patients with idiopathic pulmonary fibrosis

Background

With the rapid advances of genetic and genomic technologies, the pathophysiological mechanisms of idiopathic pulmonary fibrosis (IPF) were gradually becoming clear, however, the prognosis of IPF was still poor. This study aimed to systematically explore the ferroptosis-related genes model associated with prognosis in IPF patients.

Methods

Datasets were collected from the Gene Expression Omnibus (GEO). The least absolute shrinkage and selection operator (LASSO) Cox regression analysis was applied to create a multi-gene predicted model from patients with IPF in the Freiburg cohort of the GSE70866 dataset. The Siena cohort and the Leuven cohort were used for validation.

Results

Nineteen differentially expressed genes (DEGs) between the patients with IPF and control were associated with poor prognosis based on the univariate Cox regression analysis (all P < 0.05). According to the median value of the risk score derived from an 8-ferroptosis-related genes signature, the three cohorts’ patients were stratified into two risk groups. Prognosis of high-risk group (high risk score) was significantly poorer compared with low-risk group in the three cohorts. According to multivariate Cox regression analyses, the risk score was an independently predictor for poor prognosis in the three cohorts. Receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA) confirmed the signature's predictive value in the three cohorts. According to functional analysis, inflammation- and immune-related pathways and biological process could participate in the progression of IPF.

Conclusions

These results imply that the 8-ferroptosis-related genes signature in the bronchoalveolar lavage samples might be an effective model to predict the poor prognosis of IPF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01799-7.

Evidence for dimerization of ferroportin in a human hepatic cell line using proximity ligation assays

Mutations in the only known iron exporter ferroportin (FPN) in humans are associated with the autosomal dominantly inherited iron overload disorder ferroportin disease or type IV hereditary hemochromatosis (HH). While our knowledge of the central role of FPN in iron homeostasis has grown in the last 20 years, there exist some questions surrounding the structure and membrane topology of FPN with conflicting data on whether this receptor acts as a monomer or a multimer. To investigate and determine if FPN dimerization occurs in cells, we used novel tools including a variety of different FPN constructs expressing different tagged versions of the protein, a novel antibody that only detects cell surface FPN and proximity ligation assays. The results of the present study suggest that both the carboxy- and amino-termini of the FPN protein are intracellular. We also show that exogenously transfected FPN forms dimers; these dimers can be formed between the wild-type and mutant FPN proteins. This is the first study to examine the intracellular dimerization of FPN protein. Using proximity ligation assays, we show intracellular localization of FPN dimers and the interaction between FPN and hepcidin proteins as well. These results have important implications in the field of iron metabolism and add to our knowledge about FPN membrane topology and physiology of iron transport. This will be of importance in understanding the clinical implications of FPN mutations and of interest to future research aimed at targeting FPN expression to modulate iron homeostasis.

Anemia, Iron Status, and HIV: A Systematic Review of the Evidence

People living with HIV (PLWHIV) are at high risk of anemia due to inadequate iron intake, HIV and opportunistic infections, and inflammation, and as a side effect of antiretroviral therapy. Though iron supplementation can reduce iron deficiency anemia (IDA) in the general population, its role in anemia and in the health of PLWHIV is unclear due to concerns that iron supplementation may increase HIV replication and risk of opportunistic infections. We systematically reviewed the evidence on indicators of iron status, iron intake, and clinical outcomes among adults and children with HIV. The evidence suggests that anemia is associated with an increased risk of all-cause mortality and incident tuberculosis among HIV-infected individuals, regardless of anemia type, and the magnitude of the risk is greater with more severe anemia. High serum ferritin is associated with adverse clinical outcomes, although it is unclear if this is due to high iron or inflammation from disease progression. One large observational study found an increased risk of all-cause mortality among HIV-infected adults if they received iron supplementation. Published randomized controlled trials of iron supplementation among PLWHIV tend to have small sample sizes and have been inconclusive in terms of effectiveness and safety. Large randomized trials exploring approaches to safely and effectively provide iron supplementation to PLWHIV are warranted.

Differences in the frequency of genetic variants associated with iron imbalance among global populations

Iron deficiency anaemia is a major health problem affecting approximately 1.2 billion people worldwide. Young children, women of reproductive age and pregnant women living in sub-Saharan Africa are the most vulnerable. It is estimated that iron deficiency accounts for half of anaemia cases. Apart from nutritional deficiency, infection, inflammation and genetic factors are the major drivers of anaemia. However, the role of genetic risk factors has not been thoroughly investigated. This is particularly relevant in African populations, as they carry high genetic diversity and have a high prevalence of anaemia. Multiple genetic variations in iron regulatory genes have been linked to impaired iron status. Here we conducted a literature review to identify genetic variants associated with iron imbalance among global populations. We compare their allele frequencies and risk scores and we investigated population-specific selection among populations of varying geographic origin using data from the Keneba Biobank representing individuals in rural Gambia and the 1000 Genomes Project. We identified a significant lack of data on the genetic determinants of iron status in sub-Saharan Africa. Most of the studies on genetic determinants of iron status have been conducted in Europeans. Also, we identified population differences in allele frequencies in candidate putative genetic risk factors. Given the disproportionately high genetic diversity in African populations coupled with their high prevalence of iron deficiency, there is need to investigate the genetic influences of low iron status in Sub-Saharan Africa. The resulting insights may inform the future implementation of iron intervention strategies.

The ferroportin Q248H mutation protects from anemia, but not malaria or bacteremia

Iron acquisition is critical for life. Ferroportin (FPN) exports iron from mature erythrocytes, and deletion of the Fpn gene results in hemolytic anemia and increased fatality in malaria-infected mice. The FPN Q248H mutation (glutamine to histidine at position 248) renders FPN partially resistant to hepcidin-induced degradation and was associated with protection from malaria in human studies of limited size. Using data from cohorts including over 18,000 African children, we show that the Q248H mutation is associated with modest protection against anemia, hemolysis, and iron deficiency, but we found little evidence of protection against severe malaria or bacteremia. We additionally observed no excess Plasmodium growth in Q248H erythrocytes ex vivo, nor evidence of selection driven by malaria exposure, suggesting that the Q248H mutation does not protect from malaria and is unlikely to deprive malaria parasites of iron essential for their growth.

The association between fructosamine-3 kinase 900C/G polymorphism, transferrin polymorphism and human herpesvirus-8 infection in diabetics living in South Kivu

Prevalences of human herpesvirus-8 (HHV-8) infection and diabetes mellitus are very common in certain parts of Africa, containing iron-rich soils. We hypothesized that some genetic factors could have a link with susceptibility to HHV-8 infection. We focused on ferroportin Q248H mutation (rs11568350), transferrin (TF) polymorphism and fructosamine-3 kinase (FN3K) 900C/G polymorphism (rs1056534). The study population consisted of 210 type 2 diabetic adults and 125 healthy controls recruited in Bukavu (South Kivu). In the whole study population (diabetics+healthy controls), ferroportin Q248H mutation was detected in 47 subjects (14.0%) with 43 heterozygotes and 4 homozygotes. TF phenotype frequencies were 88.1% (CC), 10.4% (CD) and 1.5% (BC). Genotype frequencies of FN3K 900C/G polymorphism were respectively 9,3% (CC), 43.3% (GC) and 47.4% (GG). Prevalence of HHV8-infection in the study population was 77.3%. HHV-8 infection rate and HHV-8 IgG antibody titer were significantly higher in diabetics then in controls (p<0.0001). Significant differences were observed in HHV-8 infection rate and in HHV-8 IgG antibody titer according to FN3K rs1056534 (p<0.05 and p<0.05, respectively) and TF polymorphism (p<0.05 and p=0.005, respectively). No significant differences in HHV-8 infection rate and in HHV-8 IgG antibody titer were observed in the ferroportin Q248H mutation carriers (rs11568350) in comparison with ferroportin wild type. In a multiple regression analysis, FN3K rs1056534, TF polymorphism and presence of diabetes mellitus were predictors for HHV-8 infection. In contrast to these findings, ferroportin Q248H mutation (rs11568350) did not influence the susceptibility for an HHV-8 infection in sub-Saharan Africans.

Serum ferritin concentration is affected by ferroportin Q248H mutation in Africans

BACKGROUND

Ferroportin Q248H mutation is common in populations with African ancestry. Studies have reported that the mutation does not alter the ferroportin-hepcidin axis, but there is evidence suggesting that the mutation may lead to hyperferritinemia. We report on the relationship of ferroportin Q248H mutation on serum ferritin (SF) in health adults.

SUBJECTS AND METHODS

A total of 174 apparently healthy adults from Botswana were studied. SF was measured using an enzyme immunoassay and ferroportin Q248H mutation was identified by polymerase chain reaction and restriction enzyme digestion. Independent sample Mann-Whitney U test was used to correlate the presence of the mutation with SF.

RESULTS

Ferroportin Q248H mutation was identified in 30 individuals (17.2%) (one homozygote, 29 heterozygotes) and was absent in 144 individuals (82.8%), with Q248H allele frequency of 8.9%. In males, SF was significantly higher in ferroportin Q248H heterozygotes compared to wild types, p=0.029, but the relationship between ferroportin Q248H mutation and iron stores was blunted in females.

CONCLUSION

Our study of healthy adults provides further evidence that ferroportin Q248H mutation affects SF concentration in Africans.

Inverse relationship of serum hepcidin levels with CD4 cell counts in HIV-infected patients selected from an Indonesian prospective cohort study

BACKGROUND

Distortion of iron homeostasis may contribute to the pathogenesis of human immunodeficiency virus (HIV) infection and tuberculosis (TB). We studied the association of the central iron-regulatory hormone hepcidin with the severity of HIV and the association between hepcidin and other markers of iron homeostasis with development of TB.

METHODS

Three groups of patients were selected from a prospective cohort of HIV-infected subjects in Bandung, Indonesia. The first group consisted of HIV-infected patients who started TB treatment more than 30 days after cohort enrollment (cases). The second group consisted of HIV-infected patients who were matched for age, gender and CD4 cell count to the cases group (matched controls). The third group consisted of HIV-infected patients with CD4 cell counts above 200 cells/mm(3) (unmatched controls). Iron parameters including hepcidin were compared using samples collected at cohort enrollment, and compared with recently published reference values for serum hepcidin.

RESULTS

A total of 127 HIV-infected patients were included, 42 cases together with 42 matched controls and 43 unmatched controls. Patients with advanced HIV infection had elevated serum hepcidin and ferritin levels. Hepcidin levels correlated inversely with CD4 cells and hemoglobin. Cases had significantly higher hepcidin and ferritin concentrations at cohort enrollment compared to matched controls, but these differences were fully accounted for by the cases who started TB treatment between day 31 and 60 after enrollment. Hepcidin levels were not different in those with or without hepatitis C infection.

CONCLUSION

Iron metabolism is distorted in advanced HIV infection with CD4 cell counts correlating inversely with serum hepcidin levels. High serum hepcidin levels and hyperferritinemia were found in patients starting TB treatment shortly after cohort enrollment, suggesting that these parameters have a predictive value for development of manifest TB in HIV-infected patients.

Sequestration and scavenging of iron in infection

The proliferative capability of many invasive pathogens is limited by the bioavailability of iron. Pathogens have thus developed strategies to obtain iron from their host organisms. In turn, host defense strategies have evolved to sequester iron from invasive pathogens. This review explores the mechanisms employed by bacterial pathogens to gain access to host iron sources, the role of iron in bacterial virulence, and iron-related genes required for the establishment or maintenance of infection. Host defenses to limit iron availability for bacterial growth during the acute-phase response and the consequences of iron overload conditions on susceptibility to bacterial infection are also examined. The evidence summarized herein demonstrates the importance of iron bioavailability in influencing the risk of infection and the ability of the host to clear the pathogen.

Ferroportin Q248H mutation, hyperferritinemia and atypical type 2 diabetes mellitus in South Kivu

BACKGROUND

The ferroportin Q248H mutation is relatively common in sub-Saharan Africa. No previous study examined its relationship with atypical diabetes mellitus (DM) in this area.

OBJECTIVE

To determine the potential interactions between ferroportin Q248H mutation, hyperferritinemia and DM in South Kivu (RDC).

METHODOLOGY

Presence of ferroportin Q248H mutation and iron status were investigated in diabetic patients (n=179, age (mean) 57.7 years, CRP (median) 0.16 mg/L) and non-diabetic subjects (n=86, age 44.5 years, CRP 0.07 mg/L) living in the city of Bukavu. Hyperferritinemia was considered for values greater than 200 and 300 μg/L in women and in men, respectively.

RESULTS

The prevalence of ferroportin Q248H mutation [12.1%] was non-significantly higher in diabetics than non-diabetics [14.0% vs. 8.1%, p=0.17]. Similarly, hyperferritinemia frequency was higher in diabetic patients with Q248H mutation [44.0% vs. 14.3%, p=0.16] and in mutation carriers [37.0% vs 16.5%, p=0.001] than in the control groups, respectively. The association between Q248H mutation and DM was nevertheless not significant [adjusted OR 1.70 (95% CI: 0.52-5.58), p=0.37], whereas hyperferritinemia [OR 2.72 (1.24-5.98), p=0.01] showed an independent effect after adjustment for age and metabolic syndrome.

CONCLUSIONS

The present work suggests a potential association between abnormal iron metabolism, ferroportin Q248H mutation and atypical DM in Africans, which may be modulated by environmental factors.

Pathogenesis and clinical implications of HIV-related anemia in 2013

Anemia is a common feature of HIV-related disease and has been uniformly demonstrated to be an independent predictor of morbidity and mortality. Although anemia often responds to combination antiretroviral therapy, many patients remain anemic despite therapy and such persistent anemia continues to negatively affect prognosis regardless of drug response. Anemia is also a common feature of normal aging. We postulate that the pathophysiology of anemia in HIV, especially that which persists in the face of combination antiretroviral therapy, is a reflection of underlying proinflammatory pathways that are also thought to contribute to anemia in the elderly, as well as other age-related chronic diseases such as cardiovascular disease and chronic obstructive pulmonary disease. This suggests that HIV induces inflammatory pathways that are associated with a pattern of accelerated aging and that anemia is a biomarker of these processes. A better understanding of the pathophysiology of HIV-related anemia may provide important entry points for improving the chronic manifestations of HIV-related disease.

Effect of ferroportin polymorphism on iron homeostasis and infection

Ferroportin (FPN) is the sole iron export membrane protein identified in mammals that is abundantly expressed on absorptive enterocytes and macrophages, and is essential for physiological regulation of cellular iron. The expression of FPN is positively induced by cellular iron and is suppressed by liver hepcidin in response to either increased systemic iron or inflammatory stimuli. Hepcidin binds to cell surface FPN inducing FPN internalization followed by lysosomal degradation of the protein and consequently iron efflux from macrophages is blocked and there is suboptimal iron absorption by duodenal enterocytes. Dozens of FPN gene mutations have been identified in different ethnic populations and some of the mutations are associated with autosomal dominant iron overload disorder described as FPN disease or hemochromatosis type 4 that is distinct from hereditary hemochromatosis due to HFE mutations. Clinical manifestations of iron overload FPN disease can be classified into two groups according to whether there is selective macrophage iron loading or parenchymal and reticuloendothelial iron accumulation. There is evidence suggesting that altered hepcidin-FPN interaction can modulate host's response to infection. Resistance to hepcidin promotes iron egress from cells and this inhibits growth of intracellular pathogens. Conversely, iron retention due to loss of iron export activity by mutated FPN results in intracellular iron accumulation and a permissive environment for intracellular pathogens.

Reduced sensitivity of the ferroportin Q248H mutant to physiological concentrations of hepcidin

Ferroportin Q248H mutation has an allele frequency of 2.2-13.4% in African populations and is associated with a mild tendency to increased serum ferritin in the general population. Some investigators have reported that ferroportin Q248H is degraded after exposure to hepcidin in exactly the same manner as wild-type ferroportin, but supraphysiological concentrations of hepcidin were used. The aim of our study was to determine whether ferroportin Q248H may have reduced sensitivity to physiological concentrations of hepcidin. The sensitivity of ferroportin Q248H to hepcidin was determined in 293T cells transiently expressing ferroportin using immunoblotting and fluorescence analysis. Ferritin concentrations were measured in these cells and also in human primary monocytes derived from humans with different ferroportin genotypes. The effect of Q248H on serum iron measures was examined in patients with sickle cell anemia. Immunoblotting and fluorescence analysis showed decreased sensitivity of ferroportin Q248H to physiological concentrations of hepcidin. Lower ferritin concentrations were observed after incubation with iron and hepcidin in 293T cells expressing ferroportin Q248H and in primary monocytes from ferroportin Q248H subjects. In sickle cell anemia, ferroportin Q248H heterozygotes had lower serum ferritin concentrations than wild-type subjects, consistent with enhanced iron release by macrophage ferroportin Q248H. A clinical benefit of ferroportin Q248H was suggested by lower echocardiographic estimates of pulmonary artery pressure in patients carrying mutant alleles. In conclusion, our results suggest that ferroportin Q248H protein is resistant to physiological concentrations of hepcidin and that this mutation has discernible effects on iron metabolism-related clinical complications of sickle cell anemia. They provide a mechanistic explanation for the effect of ferroportin Q248H on iron status in individuals of African descent and suggest that these changes in iron metabolism may be beneficial under certain disease-specific circumstances. (ClinicalTrials.gov Identifier:NCT00011648).