Mitochondrial DNA Copy Number Drives the Penetrance of Acute Intermittent Porphyria.

No published study has investigated the mitochondrial count in patients suffering from acute intermittent porphyria (AIP). In order to determine whether mitochondrial content can influence the pathogenesis of porphyria, we measured the mitochondrial DNA (mtDNA) copy number in the peripheral blood cells of 34 patients and 37 healthy individuals. We found that all AIP patients had a low number of mitochondria, likely as a result of a protective mechanism against an inherited heme synthesis deficiency. Furthermore, we identified a close correlation between disease penetrance and decreases in the mitochondrial content and serum levels of PERM1, a marker of mitochondrial biogenesis. In a healthy individual, mitochondrial count is usually modulated to fit its ability to respond to various environmental stressors and bioenergetic demands. In AIP patients, coincidentally, the phenotype only manifests in response to endogenous and exogenous triggers factors. Therefore, these new findings suggest that a deficiency in mitochondrial proliferation could affect the individual responsiveness to stimuli, providing a new explanation for the variability in the clinical manifestations of porphyria. However, the metabolic and/or genetic factors responsible for this impairment remain to be identified. In conclusion, both mtDNA copy number per cell and mitochondrial biogenesis seem to play a role in either inhibiting or promoting disease expression. They could serve as two novel biomarkers for porphyria.

The role of hypoxia and inflammation in the regulation of iron metabolism and erythropoiesis in COVID-19: The IRONCOVID study.

Coronavirus Disease (COVID-19) can be considered as a human pathological model of inflammation combined with hypoxia. In this setting, both erythropoiesis and iron metabolism appear to be profoundly affected by inflammatory and hypoxic stimuli, which act in the opposite direction on hepcidin regulation. The impact of low blood oxygen levels on erythropoiesis and iron metabolism in the context of human hypoxic disease (e.g., pneumonia) has not been fully elucidated. This multicentric observational study was aimed at investigating the prevalence of anemia, the alterations of iron homeostasis, and the relationship between inflammation, hypoxia, and erythropoietic parameters in a cohort of 481 COVID-19 patients admitted both to medical wards and intensive care units (ICU). Data were collected on admission and after 7 days of hospitalization. On admission, nearly half of the patients were anemic, displaying mild-to-moderate anemia. We found that hepcidin levels were increased during the whole period of observation. The patients with a higher burden of disease (i.e., those who needed intensive care treatment or had a more severe degree of hypoxia) showed lower hepcidin levels, despite having a more marked inflammatory pattern. Erythropoietin (EPO) levels were also lower in the ICU group on admission. After 7 days, EPO levels rose in the ICU group while they remained stable in the non-ICU group, reflecting that the initial hypoxic stimulus was stronger in the first group. These findings strengthen the hypothesis that, at least in the early phases, hypoxia-driven stimuli prevail over inflammation in the regulation of hepcidin and, finally, of erythropoiesis.

Associated Effect of SLC40A1 and TMPRSS6 Polymorphisms on Iron Overload.

Mutations in the ferroportin (FPN) gene SLC40A1 alter iron recycling and cause disturbances in iron homeostasis. The variants of TMPRSS6 contribute to the development of iron deficiencies. In this study, we determined the role of FPN and TMPRSS6 gene polymorphisms in the modulation of iron homeostasis based on biochemical parameters. PCR analysis and sequencing were performed to determine the single nucleotide polymorphisms (SNPs) SLC40A1 c.44−24G>C (rs1439816), SLC40A1 c.663T>C (rs2304704), and TMPRSS6 c.2207T>C (rs855791). Hemoglobin concentration and iron status were determined by standard procedures. We studied 79 iron-loaded individuals for SLC40A1 polymorphisms. Interestingly, 35/79 individuals with SLC40A1 SNPs also carried a TMPRSS6 c.2207T>C polymorphism. The biochemical values of the iron overloaded individuals were compared to those of the individuals carrying TMPRSS6 SNPs and the healthy individuals (wild-type group). The ferritin concentration, transferrin saturation % (TS%), and hemoglobin concentration were significantly higher in the participants with FPN SNPs than in the other three groups. The ferritin concentration and TS% were higher in participants with both SLC40A1 and TMPRSS6 SNPs than in the TMPRSS6 and wild-type groups, while hemoglobin concentration was significantly higher than that in the TMPRSS6 SNP group only. The participants with TMPRSS6 SNPs had significantly lower ferritin concentration, TS%, and hemoglobin concentration than all the other groups. SLC40A1 and TMPRSS6 SNPs might act in the opposite direction, preventing the development of severe iron overload, and the modulation of the iron status by TMPRSS6 SNPs might provide protection.

COVID-19, inflammatory response, iron homeostasis and toxicity: a prospective cohort study in the Emergency Department of Piacenza (Italy).

BACKGROUND AND AIM: Dysregulation of iron metabolism and hyper-inflammation are two key points in the pathogenesis of coronavirus disease 2019 (COVID-19). Since high hepcidin levels and low serum iron can predict COVID-19 severity and mortality, we decided to investigate iron metabolism and inflammatory response in 32 COVID-19 adult patients with a diagnosis of COVID-19 defined by a positive result of RT-PCR nasopharyngeal swab, and admitted to an Italian emergency department for acute respiratory failure at different degree. METHODS: Patients were stratified in 3 groups based on PaO2/FiO2 ratio at admission: 13 (41%) were normoxemic at rest and suffered from exertional dyspnea (group 1); 14 (44%) had a mild respiratory failure (group 2), and 5 (15%) a severe hypoxiemia (group 3). RESULTS: White blood cells were significantly higher in group 3, while lymphocytes and hemoglobin were significantly reduced. Serum iron, transferrin saturation, non-transferrin-bound iron (NTBI) and ferritin were significantly increased in group 2. All the groups showed high hepcidin levels, but in group 3 this parameter was significantly altered. It is noteworthy that in group 1 inflammatory and oxidative indices were both within the normal range. CONCLUSIONS: We are aware that our study has some limitations, the small number of enrolled patients and the short period of data collection, but few works have been performed in the Emergency Room. However, we strongly believe that our results confirm the pivotal role of both iron metabolism dysregulation and hyper-inflammatory response in the pathogenesis of tissue and organ damage in COVID-19 patients.

Microcytosis in Erythropoietic Protoporphyria.

Partial deficiency of the last enzyme of the heme biosynthetic pathway, namely, ferrochelatase (FECH), is responsible for erythropoietic protoporphyria (EPP) in humans. This disorder is characterized by painful skin photosensitivity, due to excessive protoporphyrin IX (PPIX) production in erythrocytes. Although several papers report the presence of iron deficiency anemia in about 50% of EPP patients, there is still no a conclusive explanation of the why this occurs. In the present work, we explored hematological indices and iron status in 20 unrelated Italian EPP patients in order to propose a new hypothesis. Our data show that microcytosis is present in EPP patients also in the absence of anemia and iron deficiency with a link between PPIX accumulation and reduced MCV, probably indicating an indirect condition of heme deficiency. Patients studied had a downward shift of iron parameters due to increased hepcidin concentrations only in a state of repleted iron stores. Interestingly, hemoglobin synthesis was not limited by iron supply except in cases with further iron loss, in which concomitantly increased soluble transferrin (Tf) receptor (sTfR) levels were detected. The mechanisms involved in the iron uptake downregulation in EPP remain unclear, and the role of PPIX accumulation in microcytosis.

α-Lipoic Acid Improves Hepatic Metabolic Dysfunctions in Acute Intermittent Porphyria: A Proof-of-Concept Study.

BACKGROUND: Acute intermittent porphyria (AIP) is caused by the haploinsufficiency of porphobilinogen deaminase (PBGD) enzymatic activity. Acute attacks occur in response to fasting, and alterations in glucose metabolism, insulin resistance, and mitochondrial turnover may be involved in AIP pathophysiology. Therefore, we investigated the metabolic pathways in PBGD-silenced hepatocytes and assessed the efficacy of an insulin mimic, α-lipoic acid (α-LA), as a potential therapeutic strategy. METHODS: HepG2 cells were transfected with siRNA-targeting PBGD (siPBGD). Cells were cultured with low glucose concentration to mimic fasting and exposed to α-LA alone or with glucose. RESULTS: At baseline, siPBGD cells showed a lower expression of genes involved in glycolysis and mitochondrial dynamics along with reduced total ATP levels. Fasting further unbalanced glycolysis by inducing ATP shortage in siPBGD cells and activated DRP1, which mediates mitochondrial separation. Consistently, siPBGD cells in the fasted state showed the lowest protein levels of Complex IV, which belongs to the oxidative phosphorylation (OXPHOS) machinery. α-LA upregulated glycolysis and prompted ATP synthesis and triglyceride secretion, thus possibly providing energy fuels to siPBGD cells by improving glucose utilization. Finally, siPBGD exposed to α-LA plus glucose raised mitochondrial dynamics, OXPHOS activity, and energy production. CONCLUSIONS: α-LA-based therapy may ameliorate glucose metabolism and mitochondrial dysfunctions in siPBGD hepatocytes.

Differential Redox State and Iron Regulation in Chronic Obstructive Pulmonary Disease, Acute Respiratory Distress Syndrome and Coronavirus Disease 2019.

In patients affected by Acute Respiratory Distress Syndrome (ARDS), Chronic Obstructive Pulmonary Disease (COPD) and Coronavirus Disease 2019 (COVID-19), unclear mechanisms negatively interfere with the hematopoietic response to hypoxia. Although stimulated by physiological hypoxia, pulmonary hypoxic patients usually develop anemia, which may ultimately complicate the outcome. To characterize this non-adaptive response, we dissected the interplay among the redox state, iron regulation, and inflammation in patients challenged by either acute (ARDS and COVID-19) or chronic (COPD) hypoxia. To this purpose, we evaluated a panel of redox state biomarkers that may integrate the routine iron metabolism assays to monitor the patients' inflammatory and oxidative state. We measured redox and hematopoietic regulators in 20 ARDS patients, 20 ambulatory COPD patients, 9 COVID-19 ARDS-like patients, and 10 age-matched non-hypoxic healthy volunteers (controls). All the examined pathological conditions induced hypoxia, with ARDS and COVID-19 depressing the hematopoietic response without remarkable effects on erythropoietin. Free iron was higher than the controls in all patients, with higher levels of hepcidin and soluble transferrin receptor in ARDS and COVID-19. All markers of the redox state and antioxidant barrier were overexpressed in ARDS and COVID-19. However, glutathionyl hemoglobin, a candidate marker for the redox imbalance, was especially low in ARDS, despite depressed levels of glutathione being present in all patients. Although iron regulation was dysfunctional in all groups, the depressed antioxidant barrier in ARDS, and to a lesser extent in COVID-19, might induce greater inflammatory responses with consequent anemia.

Epidemiological shift of glucose-6-phosphate dehydrogenase mutations in northern Italy in the last 15 years.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive hemolytic anemia caused by mutations in G6PD gene. The distribution and frequency of genetic variants differ depending on ethnicity and geographical areas. Because of new migrations different variants are now present in Europe. This retrospective study aims to identify variants among the G6PD deficient subjects referred since 2004 to IRCCS Ca' Granda Foundation Hospital in Milan. The subjects were divided into 3 groups: group 1 (2004-2008), group 2 (2009-2013), and group 3 (2014-2018). During 15 years a significant decrease of the Mediterranean and an important increase of the African, Asian, and uncommon variants (classified as Others) have been observed. Three new mutations were found: in group 2 heterozygosity for c.[1454G > A] (Gly485Asp) in an adult female with severe anemia, high bilirubin levels and G6PD activity of 0,69 (IU/gHb) and heterozygosity for c.[584A > G] (Gln195Arg) in an elderly woman of Italian origin showing only anemia and enzymatic activity of 1,54 (IU/gHb) were detected. In group 3 hemizygosity for c.[670A > T] (Ile224Phe) in an adult Chinese man without anemia but with total absence of G6PD activity was found. These data reflect the appearance of uncommon G6PD mutations in northern Italy, probably due to new migrations, as consequence G6PD characterization becomes a diagnostic issue.

Alternative Pathway Involvement in Protoporphyria Patients Related to Sun Exposure.

The homeostasis of tissues in a chronic disease is an essential function of the alternative pathway (AP) of the complement system (CS). However, if not controlled, it may also be detrimental to healthy cells with a consequent aggravation of symptoms. The protoporphyria (PP) is a rare chronic disease that causes phototoxicity in visible light with local skin pain and general malaise. In order to establish if there is a systemic involvement of the CS during sun exposure, we designed a non-invasive method with a serum collection in winter and summer from 19 PP and 13 controls to detect the levels of CS protein: Properdin, Factor H (FH), and C5. Moreover, the global radiation data were collected from the regional agency of environmental protection (ARPA). The results show growing values for every protein in patients with PP, compared to control, in both seasons, in particular in summer compared to winter. To reinforce the evidence, we have estimated the personal exposure of patients based on the global radiation data. The main factors of the AP increased over the season, confirming the involvement of the AP in relation to light exposure. The systemic response could justify the general malaise of patients after long light exposure and can be exploited to elucidate new therapeutic approaches.

Activin Receptor-Ligand Trap for the Treatment of ß-thalassemia: A Serendipitous Discovery.

ß-thalassemia is a hereditary disorder caused by defective production of ß-globin chains of hemoglobin (Hb) that leads to an increased α/ß globins ratio with subsequent free α-globins. Alpha globin excess causes oxidative stress, red blood cells membrane damage, premature death of late-stage erythroid precursors, resulting in ineffective erythropoiesis. The transforming growth factor ß (TGF-ß) superfamily signaling acts on biological processes, such as cell quiescence, apoptosis, proliferation, differentiation, and migration, and plays an essential role in regulating the hematopoiesis. This pathway can lose its physiologic regulation in pathologic conditions, leading to anemia and ineffective erythropoiesis. Activin receptor-ligand trap molecules such as Sotatercept and Luspatercept downregulate the TGF-ß pathway, thus inhibiting the Smad2/3 cascade and alleviating anemia in patients with ß-thalassemia and myelodysplastic syndromes. In this review, we describe in extenso the TGF-ß pathway, as well as the molecular and biological basis of activin receptors ligand traps, focusing on their role in various ß-thalassemia experimental models. The most recent results from clinical trials on sotatercept and luspatercept will also be reviewed.

Inflammatory involvement into phototoxic reaction in erythropoietic protoporphyria (EPP) patients.

Phototoxic reaction is a known feature of EPP at least in part triggered by the oxidative status, complement system activation, and mast cell response. The aim of this study was to verify some aspects involved in phototoxic reaction during a season. The complement system was evaluated by C3 assay, alternative pathway by factor-B, and classical pathway by C1q; oxidative status was tested with malondialdehyde (MDA) and mast cell by IL-10 assay. The serum samples were collected in winter and summer from 19 EPP patients and 13 controls. The reaction to sun exposure within each group was monitored without any invasive treatment. In summer, C3 and factor B were higher in patients than in controls (p = 0.002 and < 0.0001 respectively), while no change was detected for C1q. The oxidative stress was increased in summer in comparison with the control group (p = 0.04), and IL-10 an assay was normal in both seasons. The correlation between the C3 and factor-B in summer was significant. This study shows that the phototoxic reaction is not limited to the dermis but can also exert a systemic response, which could affect the general health of a patient. The knowledge of the pathophysiology of phototoxic reaction is essential for identifying new disease markers useful for improving clinical studies of known and future drugs.

Iron overload in congenital haemolytic anaemias: role of hepcidin and cytokines and predictive value of ferritin and transferrin saturation.

Iron overload (IO) is poorly investigated in the congenital haemolytic anaemias (CHAs), a heterogeneous group of rare inherited diseases encompassing abnormalities of the erythrocyte membrane and metabolism, and defects of the erythropoiesis. In this study we systematically evaluated routine iron parameters and cardiac and hepatic magnetic resonance imaging, together with erythropoietin, hepcidin, non-transferrin bound iron (NTBI), and cytokine serum levels in patients with different CHAs. We found that 40% of patients had a liver iron concentration (LIC) >4 mg Fe/g dry weight. Hepatic IO was associated with ferritin levels (P = 0·0025), transferrin saturation (TfSat, P = 0·002) and NTBI (P = 0·003). Moreover, ferritin >500 µg/l plus TfSat >60% was demonstrated as the best combination able to identify increased LIC, and TfSat alteration as more important in cases with discordant values. Possible confounding factors, such as transfusions, hepatic disease, metabolic syndrome and hereditary haemochromatosis-associated mutations, had negligible effects on IO. Erythropoietin and hepcidin levels were increased in CHAs compared with controls, correlating with LIC and ferritin, respectively. Regarding cytokines, γ-interferon (IFN-γ) was increased, and both interleukin 6 and IFN-γ levels positively correlated with ferritin and hepcidin levels. Overall, these findings suggest the existence of a vicious cycle between chronic haemolysis, inflammatory response and IO in CHAs.

Anti-TNF-Mediated Modulation of Prohepcidin Improves Iron Availability in Inflammatory Bowel Disease, in an IL-6-Mediated Fashion.

Background. Anaemia is common in inflammatory bowel disease (IBD), frequently resulting from a combination of iron deficiency and of anaemia of chronic disease (ACD). ACD is characterized by macrophage iron retention induced by proinflammatory cytokines. Hepcidin is the master inducer of iron accumulation during ACD, and its production is mainly regulated by IL-6 and the novel erythroid hormone erythroferrone (ERFE). This study evaluates whether anti-TNF monoclonal antibodies therapy modurates hepcidin production and the levels of its main regulators, leading to a restoration of iron homeostasis. Methods. Sera were collected from 21 IBD patients, before each anti-TNF administration, for the first 6 weeks of therapy. Prohepcidin, erythropoietin, erythroferrone, C reactive protein, interleukin-6, iron markers, and haemoglobin levels were measured and clinical activity indexes were evaluated. Results. Serum prohepcidin, IL-6, CRP, and ferritin were significantly reduced after 6-week treatment; an increase in serum iron and total transferrin was observed. No changes in the EPO-ERFE axis were found. Remarkably, haemoglobin was significantly increased. Conclusions. Anti-TNF therapy improves iron metabolism and, subsequently, anaemia in IBD. This effect appears to be related to the modulation of the cytokine network and specifically IL-6 leading to a relevant decrease of hepcidin, a master regulator of ACD.

Role of Non-Transferrin-Bound Iron in the pathogenesis of cardiotoxicity in patients with ST-elevation myocardial infarction assessed by Cardiac Magnetic Resonance Imaging.

BACKGROUND: Hereditary hemochromatosis, thalassemia and myelodysplastic syndromes represent disease models with evidence of iron-related heart failure. Non-Transferrin Bound Iron (NTBI) induces cardiac toxicity through the production of reactive oxygen species and lipid peroxidation. In ST-elevation acute myocardial infarction (STEMI) with evidence of microvascular obstruction (MVO) and hemorrhage (HEM), HEM may be a source of iron-related cardiac toxicity through NTBI and pro-inflammatory mediators. AIM OF THE STUDY: The study aims to assess NTBI in patients with STEMI and its possible relationship with MVO and HEM. METHODS AND RESULTS: NTBI, LPO-Malondialdehyde (MDA) and interleukin-6 (IL-6) were assessed in 15 patients with STEMI immediately before primary percutaneous coronary intervention (PPCI) and at 3, 6, 9, 12, and 24h post-PPCI. Cardiac Magnetic Resonance (CMR) was performed at 5days and 6months after STEMI. Myocardial edema and HEM were assessed by T2 and T2* mapping. MVO and necrotic area were assessed by early and late gadolinium enhancement (LGE). NTBI was detected in 13/15 patients with the highest values in 4 patients with evidence of MVO and HEM. NTBI levels were significantly related to CK-MB and troponin T values. NTBI kinetics appeared to be different in patients with MVO and HEM (7/15 patients), with a peak value at 6h after PCI, in comparison with those with no evidence of MVO and HEM, in whom NTBI values were lower and remained indeterminable after the first 24h. CONCLUSIONS: The detection of elevated NTBI values in patients with STEMI, MVO and HEM suggests a possible role of iron cardiotoxicity in myocardial damage.

Non transferrin bound iron (NTBI) in acute leukemias throughout conventional intensive chemotherapy: kinetics of its appearance and potential predictive role in infectious complications.

We analyzed appearance of non transferrin bound iron (NTBI) in 30 transplant eligible patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) during conventional chemotherapy treatment program and evaluated possible relationship with transfusional body iron intake, iron parameters and clinical complications. For each course, serum samples for NTBI detection were taken prior to chemotherapy, during treatment and during subsequent bone marrow myelosuppression: NTBI was assessed by HPLC. Appearance of NTBI was observed from the start of induction treatment and was still detectable during bone marrow myelosuppression; the recovery of the bone marrow function coincided with the disappearance of NTBI. This kinetic was observed in all subsequent high doses chemotherapy courses, independently from confounding variables such as transfusional iron intake and transferrin saturation. NTBI seems to be a consequence of chemotherapy induced lysis of bone marrow cells and, partly, of hepatocytes after cytotoxic injury. The subsequent persistence of NTBI throughout bone marrow myelosuppression is related to the transient suspension of erythropoietic activity. Moreover, NTBI levels >2µM at the beginning of iatrogenic myelosuppression were associated with higher risk of sepsis caused by Gram negative Bacilli (RR 2.571), also compared with other infectious complications (RR 1.954).

Erythropoietin in Friedreich ataxia: no effect on frataxin in a randomized controlled trial.

BACKGROUND: Friedreich ataxia is a rare disease caused by GAA-trinucleotide-repeat expansions in the frataxin gene, leading to marked reduction of qualitatively normal frataxin protein. Recently, human recombinant erythropoietin was reported to increase frataxin levels in patients with Friedreich ataxia. METHODS: We performed a 6-month, randomized placebo-controlled, double-blind, dose-response pilot trial to assess the safety and efficacy of erythropoietin in increasing frataxin levels. Sixteen adult patient with Friedreich ataxia were randomly assigned to erythropoietin (n = 11) or matching placebo (n = 5). All patients continued Idebenone treatment (5 mg/kg/day). Treatment consisted of a 6-month scaling-up phase, in which erythropoietin was administered intravenously at the following doses: 20,000 IU every 3 weeks, 40,000 IU every 3 weeks, and 40,000 IU every 2 weeks. RESULTS: Erythropoietin treatment was safe and well tolerated, but did not result in any significant hematological, clinical, or biochemical effects in Friedreich ataxia patients.