Decrease in APP and CP mRNA expression in Alzheimer’s disease patients suggests impairment of cellular iron export in this dementia

Recentemente tem-se assistido a um acumular de evidência sugerindo a implicação de uma desregulação do metabolismo do ferro (Fe) na fisiopatologia da doença de Alzheimer (DA). Neste trabalho, pretendemos esclarecer melhor os mecanismos moleculares subjacentes à homeostasia deste metal na DA, particularmente ao nível do efluxo celular. Assim, mediu-se em células mononucleares do sangue periférico de 73 doentes com DA e 74 controlos a expressão de genes diretamente envolvidos na regulação e exportação celular de Fe, utilizando a técnica de PCR quantitativo. Os resultados mostraram uma diminuição significativa na expressão dos genes aconitase (ACO1; P=0,007); ceruloplasmina (CP; P<0,001) e proteína precursora de beta amilóide (APP; P=0,006) em doentes com DA comparativamente com os voluntários saudáveis. Estas observações apontam para uma diminuição significativa da expressão dos genes associados com a exportação de Fe celular mediada pela ferroportina na DA. Assim, o presente estudo reforça resultados anteriores que mostram alterações no metabolismo do Fe e podem estar na origem da retenção intracelular deste metal e aumento de stress oxidativo caraterísticos desta patologia.A dysregulation of iron (Fe) metabolism in Alzheimer’s disease (AD) has been suggested previously. Herein, we intended to further clarify the molecular mechanisms underlying Fe homeostasis in AD particularly at the level of cellular iron efflux. Thus, the expression of specific Fe metabolism-related genes directly involved in Fe regulation and export was assessed by quantitative PCR in peripheral blood mononuclear cells (PBMCs) from 73 AD patients and 74 controls. A significant decrease in the expression of aconitase 1 (ACO1; P=0.007); ceruloplasmin (CP; P<0.001) and amyloid peptide precursor (APP; P=0.006) genes was fund in AD patients compared with healthy volunteers. These observations point out to a significant downregulation of the expression of genes associated with ferroportin-mediated cellular Fe export in PBMCs from AD patients. The present findings support previous studies suggesting impairment of Fe homeostasis in AD, which may lead to cellular Fe retention and oxidative stress, a typical feature of this disease

Serological response and breakthrough infection after COVID-19 vaccination in patients with cirrhosis and post-liver transplant

BACKGROUND: Vaccine hesitancy and lack of access remain major issues in disseminating COVID-19 vaccination to liver patients globally. Factors predicting poor response to vaccination and risk of breakthrough infection are important data to target booster vaccine programs. The primary aim of the current study was to measure humoral responses to 2 doses of COVID-19 vaccine. Secondary aims included the determination of factors predicting breakthrough infection. METHODS: COVID-19 vaccination and Biomarkers in cirrhosis And post-Liver Transplantation is a prospective, multicenter, observational case-control study. Participants were recruited at 4-10 weeks following first and second vaccine doses in cirrhosis [n = 325; 94% messenger RNA (mRNA) and 6% viral vaccine], autoimmune liver disease (AILD) (n = 120; 77% mRNA and 23% viral vaccine), post-liver transplant (LT) (n = 146; 96% mRNA and 3% viral vaccine), and healthy controls (n = 51; 72% mRNA, 24% viral and 4% heterologous combination). Serological end points were measured, and data regarding breakthrough SARS-CoV-2 infection were collected. RESULTS: After adjusting by age, sex, and time of sample collection, anti-Spike IgG levels were the lowest in post-LT patients compared to cirrhosis (p < 0.0001), AILD (p < 0.0001), and control (p = 0.002). Factors predicting reduced responses included older age, Child-Turcotte-Pugh B/C, and elevated IL-6 in cirrhosis; non-mRNA vaccine in AILD; and coronary artery disease, use of mycophenolate and dysregulated B-call activating factor, and lymphotoxin-α levels in LT. Incident infection occurred in 6.6%, 10.6%, 7.4%, and 15.6% of cirrhosis, AILD, post-LT, and control, respectively. The only independent factor predicting infection in cirrhosis was low albumin level. CONCLUSIONS: LT patients present the lowest response to the SARS-CoV-2 vaccine. In cirrhosis, the reduced response is associated with older age, stage of liver disease and systemic inflammation, and breakthrough infection with low albumin level

Decrease of β-amyloid peptide precursor and ceruloplasmin mRNA levels in patients with Alzheimer’s disease support impairment of cellular iron efflux in this pathology

This research was supported by the Fundação para a Ciência e a Tecnologia (FCT) [SFRH/BPD/29354/2006 to MM, SFRH/BD/60718/2009 to BS, and SFRH/BD/48671/2008 to LM]; Fundação Astrazeneca (Research Grant awarded through the “Programme of Support to Research”); Instituto Nacional de Saúde Dr. Ricardo Jorge; Portuguese Ministry of Health (Research Grant 53/2007 of the “Comissão de Fomento da Investigação em Cuidados de Saúde”); Lundbeck Portugal, Lda (Research Grant).Introduction: Alzheimer’s disease (AD) is the most common neurodegenerative disorder and the leading cause of dementia worldwide. Because of the clinical interest in its early diagnosis and prediction of patient evolution and prognosis, the identification of AD biomarkers is of crucial importance. Several lines of evidence implicate an imbalance of the redox-active biometals in AD. Metal-catalyzed hydroxyl radicals are potent mediators of cellular injury and are central to the oxidative injury hypothesis of AD pathogenesis [1,2]. Importantly, previous genetic and biochemical studies in AD patients support a concerted systemic iron metabolism dysregulation, namely at the level of cellular iron efflux [3]. Herein, we intended to further understand the molecular mechanisms underlying iron homeostasis in this pathology. In order to achieve this goal, the expression of specific iron metabolism-related genes directly involved in iron metabolism regulation and cellular iron export was measured in peripheral blood mononuclear cells from AD patients and healthy controls. Also, serum ceruloplasmin (CP) concentration and its oxidase activity were measured in all participants in the study, given the known role of this oxidase in facilitating iron exit from cells. Through this study we expect to further clarify the contribution of iron metabolism disruption to the etiopathogenesis of AD

Iron/copper metabolism in Alzheimer’s disease: genetics and biomarkers in a Portuguese population

This work was supported by Fundação Astrazeneca through the “Programa de Apoio à Investigação” . Presented at the “International Conference in Alzheimer’s Disease 2009The distinction between normal aging and Alzheimer's disease (AD) is a relevant step to combat this disease efficiently. Thus, the identification of biomarkers and genetic factors underlying AD pathology is extremely important. Oxidative injury in the brain, mediated by the imbalance of redox-active metals as iron (Fe) and copper (Cu) has been recognized to contribute to the pathology of AD. In this context, we further investigated this hypothesis by: (I) comparing serum biochemical markers of Fe/Cu metabolism in a sample of 117 AD patients and 91 healthy controls; (II) testing in the same sample a set of Fe/Cu metabolism-related genes and APOE for association with AD. Genetic analysis was performed through high density SNP genotyping of the candidate genes CP, CYBRD1, HAMP, HFE, IREB1, IREB2, SLC11A2, SLC40A1, TF, TFR2, FB19, CALR, and APOE. Biochemical analysis was assessed for: serum Fe, transferrin, transferrin saturation and serum ferritin levels. The most significant difference was found between AD patients and controls for serum Fe concentration (76.63 ± 26.36 μg/dL and 86.67 ± 25.18 μg/dL, respectively, P=0.003), although other significant differences were also found for transferrin and ferritin levels (P=0.016 and P=0.033, respectively). Significant associations with AD were found for two SNPs in TF (P=0.0147 and P=0.0415), one SNP in TFR2 (P=0.0055) and for the first time in IREB1 (P=0.0258) and SLC40A1 (P=0.0210) genes. In addition to the significant independent effects, evidence for interaction between IREB1 and TFR2, CP, IREB2 and SLC40A1 markers was also found. The overall results suggest the involvement of these iron metabolism genes in Alzheimer etiology. APOE was also significantly associated with AD (P=0.0007), in agreement with previous studies. We hypothesize that the lower serum Fe concentration observed in AD patients can be due to impaired Fe excretion from cells, since Fpn codified by SLC40A1 is the only known Fe exporter in mammalian cells. Also, the TFR2 polymorphism found to be associated with AD is located at the putative promoter region of the TfR2_beta isoform which seems to be involved in SLC40A1 transcriptional regulation. On the other hand, IREB1 codifies a cytosolic protein which binds to iron-responsive elements (IREs) found in RNA from several iron metabolism-related proteins as ferritin, TfR, Fpn itself and importantly GEECD, Tomar, Portugal, Jun2012 APP. The intracellular accumulation of Fe, particularly in the brain where Fpn is also expressed, would lead to a rise in oxidative damage, contributing to the AD physiopathology. Further research is demanded in a greater sample to confirm the results obtained in this pilot study. Noteworthy, an integrative approach was followed to deal with heterogeneity in this complex disorder, and new directions were raised related to the study of Fe metabolism involvement in AD

Crosstalk between genetics, gene expression and biochemical markers supports systemic iron homeostasis dysregulation in alzheimer disease

This work was supported by Fundação Astrazeneca through the “Programa de Apoio à Investigação”