Oliviero Olivieri

A linkage between hereditary hyperferritinaemia not related to iron overload and autosomal dominant congenital cataract

Summary. The only genetic disorder with elevated serum ferritin levels so far described is hereditary HLA‐related haemochromatosis. On the other hand, hereditary cataract is both genotypically as well as phenotypically heterogenous, and no specific locus or any useful marker has been yet identified. We studied two Italian families in whom a combination of elevated serum ferritin not related to iron overload and congenital nuclear cataract is transmitted as an autosomal dominant trait. Affected individuals have normal serum iron and transferrin saturation, but high serum ferritin. Red cell counts are normal and venesection therapy rapidly produces iron‐deficiency anaemia.

Clonal Hematopoiesis of Indeterminate Potential (CHIP) in Patients withCoronary Artery Disease and in Centenarians. Further Clues Linking Chip with Cardiovascular Risk

Biogenesis of mammalian red blood cells requires nuclear expulsion by orthochromatic erythoblasts late in terminal differentiation (enucleation), but the mechanism is largely unexplained. Here, we employed high-resolution confocal microscopy to analyze nuclear morphology and F-actin rearrangements during the initiation, progression, and completion of mouse and human erythroblast enucleation in vivo. Mouse erythroblast nuclei acquire a dumbbell-shaped morphology during enucleation, whereas human bone marrow erythroblast nuclei unexpectedly retain their spherical morphology. These morphological differences are linked to differential expression of Lamin isoforms, with primary mouse erythroblasts expressing only Lamin B and primary human erythroblasts only Lamin A/C. We did not consistently identify a continuous F-actin ring at the cell surface constriction in mouse erythroblasts, nor at the membrane protein-sorting boundary in human erythroblasts, which do not have a constriction, arguing against a contractile ring-based nuclear expulsion mechanism. However, both mouse and human erythroblasts contain an F-actin structure at the rear of the translocating nucleus, enriched in tropomodulin 1 (Tmod1) and nonmuscle myosin IIB. We investigated Tmod1 function in mouse and human erythroblasts both in vivo and in vitro and found that absence of Tmod1 leads to enucleation defects in mouse fetal liver erythroblasts, and in CD34+ hematopoietic stem and progenitor cells, with increased F-actin in the structure at the rear of the nucleus. This novel structure, the enucleosome, may mediate common cytoskeletal mechanisms underlying erythroblast enucleation, notwithstanding the morphological heterogeneity of enucleation across species.

Epigenetics and Arterial Hypertension

Abstract Epigenetic phenomena refer to DNA methylation and hydroxymethylation, posttranslational histone modifications, and noncoding RNAs. Differently from genetic features of DNA, they are potentially reversible by environmental/nutritional factors, which make them possibly crucial in complex and multifactorial diseases such as arterial hypertension (AH). DNA methylation is, among the epigenetic marks, the most highlighted. Global methylation is lower in peripheral blood mononuclear cells DNA of hypertensive patients than normotensive subjects, and DNA hydroxymethylation are both modifiable by salt intake in a Dahl salt-sensitive rat model. The specific function of DNA methylation in regulating the expression of AH-related genes at promoter site was described for HSD11B2, NKCC1, sACE, ADD1, ESR1, AGT, and for other crucial genes in endocrine hypertension. Posttranslational histone methylation at different histone 3 lysine residues was observed to control the expression of WNK4, LSD1, HSD11B2, SCNN1A, alpha-ENaC, and NOS3 genes. Noncoding RNAs including several microRNAs are being studied for regulation of genes involved in steroidogenesis and the renin–angiotensin–aldosterone pathways. The current knowledge on the relationship between the main epigenetic marks associated to AH is an ongoing tour, aimed to identify epigenetic patterns and environmental factors that may lead toward novel implications in AH preventive and therapeutic strategies.Epigenetic phenomena refer to DNA methylation and hydroxymethylation, posttranslational histone modifications, and noncoding RNAs. Differently from genetic features of DNA, they are potentially reversible by environmental/nutritional factors, which make them possibly crucial in complex and multifactorial diseases such as arterial hypertension (AH). DNA methylation is, among the epigenetic marks, the most highlighted. Global methylation is lower in peripheral blood mononuclear cells DNA of hypertensive patients than normotensive subjects, and DNA hydroxymethylation are both modifiable by salt intake in a Dahl salt-sensitive rat model. The specific function of DNA methylation in regulating the expression of AH-related genes at promoter site was described for HSD11B2, NKCC1, sACE, ADD1, ESR1, AGT, and for other crucial genes in endocrine hypertension. Posttranslational histone methylation at different histone 3 lysine residues was observed to control the expression of WNK4, LSD1, HSD11B2, SCNN1A, alpha-ENaC, and NOS3 genes. Noncoding RNAs including several microRNAs are being studied for regulation of genes involved in steroidogenesis and the renin–angiotensin–aldosterone pathways. The current knowledge on the relationship between the main epigenetic marks associated to AH is an ongoing tour, aimed to identify epigenetic patterns and environmental factors that may lead toward novel implications in AH preventive and therapeutic strategies.

Epigenetic Regulation of HSD11B2 Gene by Promoter Methylation in Glucocorticoid-Treated Patients

Background: A reduced activity of the 11 beta-hydroxysteroid dehydrogenase 2 (11 beta-HSD2) causes hypertension by conferring aldosterone selectivity to mineralcorticoid receptors and eventually impairing the tetrahydrocortisol-versus tetrahydrocortisone-metabolites (THFs/THE) shuttle. The 11 beta-HSD2 function is modulated by glucocorticoid treatment that may induce hypertension through a mechanism mostly unknown. Promoter methylation, one of the main epigenetic and potentially modifiable feature of DNA, regulates HSD11B2 gene expression and relates to the development of arterial hypertension. n nObjective: To explore the mechanism by which steroid therapy influences blood pressure we investigated the effect of glucocorticoid-treatment on HSD11B2 promoter methylation and THFs/THE ratio, that reflects the 11 beta-HSD2 activity. n nMethod: We determined urinary THFs/THE ratio by gas chromatography/mass spectrometry and HSD11B2 methylation in promoter Region 1 and 2 using bisulfitepyrosequencing in DNA from peripheral blood mononuclear cells (PBMCs) of six normotensive subjects affected by autoimmune diseases at three time points: T0) baseline, T1) following one-month prednisone therapy (0.5-1 mg/kg daily), and T2) at least one year after withdrawal. n nResults: Glucocorticoid treatment was associated with the increase of HSD11B2 promoter methylation, that was significant for Region 1 (T0 2.4%, T1 2.8%, P=0.046), and the concomitant raise of THFs/THE ratio (T0 1.29 ± 0.80, T1 4.10 ± 1.62, P=0.043). After glucocorticoid-withdrawal (T2) both parameters decreased (methylation 1.9%; THFs/THE ratio 1.09), although not significantly. A significant positive correlation was observed between HSD11B2 promoter methylation and the THFs/THE ratio. n nConclusion: High-dosage prednisone therapy alters promoter methylation of HSD11B2 and 11beta-HSD2 activity, influencing blood pressure: this effect appears slightly reversible after glucocorticoid-withdrawal, suggesting a dynamic epigenetic regulation of HSD11B2.