Iron as Therapeutic Targets in Human Diseases Volume 2

Iron is an essential element for almost all organisms, a cofactor playing a crucial role in a number of vital functions, including oxygen transport, DNA synthesis, and respiration. However, its ability to exchange electrons renders excess iron potentially toxic, since it is capable of catalyzing the formation of highly poisonous free radicals. As a consequence, iron homeostasis is tightly controlled by sophisticated mechanisms that have been partially elucidated. Because of its biological importance, numerous disorders have been recently linked to the deregulation of iron homeostasis, which include not only the typical disorders of iron overload and deficiency but also cancer and neurodegenerative diseases. This leads iron metabolism to become an interesting therapeutic target for novel pharmacological treatments against these diseases. Several therapies are currently under development for hematological disorders, while other are being considered for different pathologies. The therapeutic targeting under study includes the hepcidin/ferroportin axis for the regulation of systemic iron homeostasis, complex cytosolic machineries for the regulation of the intracellular iron status and its association with oxidative damage, and reagents exploiting proteins of iron metabolism such as ferritin and transferrin receptor. A promising potential target is a recently described form of programmed cell death named ferroptosis, in which the role of iron is essential but not completely clarified. This Special Issue has the aim to summarize the state-of-the-art, and the latest findings published in the iron field, as well as to elucidate future directions

Iron as therapeutic target in human diseases

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Hepcidin antagonists for potential treatments of disorders with hepcidin excess

5noThe discovery of hepcidin clarified the basic mechanism of the control of systemic iron homeostasis. Hepcidin is mainly produced by the liver as a propeptide and processed by furin into the mature active peptide. Hepcidin binds ferroportin, the only cellular iron exporter, causing the internalization and degradation of both. Thus hepcidin blocks iron export from the key cells for dietary iron absorption (enterocytes), recycling of hemoglobin iron (the macrophages) and the release of storage iron from hepatocytes, resulting in the reduction of systemic iron availability. The BMP/HJV/SMAD pathway is the major regulator of hepcidin expression that responds to iron status. Also inflammation stimulates hepcidin via the IL6/STAT3 pathway with a support of an active BMP/HJV/SMAD pathway. In some pathological conditions hepcidin level is inadequately elevated and reduces iron availability in the body, resulting in anemia. These conditions occur in the genetic iron refractory iron deficiency anemia and the common anemia of chronic disease (ACD) or anemia of inflammation. Currently, there is no definite treatment for ACD. Erythropoiesis-stimulating agents and intravenous iron have been proposed in some cases but they are scarcely effective and may have adverse effects. Alternative approaches aimed to a pharmacological control of hepcidin expression have been attempted, targeting different regulatory steps. They include hepcidin sequestering agents (antibodies, anticalins, and aptamers), inhibitors of BMP/SMAD or of IL6/STAT3 pathway or of hepcidin transduction (siRNA/shRNA) or ferroportin stabilizers. In this review we summarized the biochemical interactions of the proteins involved in the BMP/HJV/SMAD pathway and its natural inhibitors, the murine and rat models with high hepcidin levels currently available and finally the progresses in the development of hepcidin antagonists, with particular attention to the role of heparins and heparin sulfate proteoglycans in hepcidin expression and modulation of the BMP6/SMAD pathway.openopenMaura, Poli; Michela, Asperti; Paola, Ruzzenenti; Maria, Regoni; Paolo, ArosioPoli, Maura; Asperti, Michela; Ruzzenenti, Paola; Regoni, Maria; Arosio, Paol

Bisphosphonates after Denosumab withdrawal reduce the vertebral fractures incidence

Objective Several studies showed the occurrence of vertebral fracture (VFx) in patients discontinuing denosumab (Dmab), suggesting the need of bisphosphonate (BPs) therapy to mitigate this VFx risk increase. However, the morphometric VFx (morphoVFx) incidence after Dmab discontinuation and the BPs effect on VFx risk in this setting are still a matter of debate. Design Retrospective, monocentric study. Methods In 120 patients (111 females) discontinuing Dmab, 19 have not been treated (non-treated group: 16 females, aged 63.5 ± 15.0 years) and 101 patients have been treated (treated group: 95 females, aged 70.0 ± 10.6 years) with BPs (28 alendronate (ALN); 73 zoledronate ZOL), single infusion), respectively. We evaluated the incidence of both clinical VFx and morphoVFx in treated group and non-treated group. Results Patients in treated group showed a 5.5% VFx incidence (n = 6, three clinical, three morpho VFx), which was anyway lower than non-treated group patients (n = 4, 21.1%, four clinical, three multiple, P = 0.029), despite a comparable FRAX score at the time of Dmab initiation. The logistic regression analysis showed that the VFx incidence was independently associated with the lack of BPs treatment (odds ratio: 13.9, 95% CI 1.7–111.1, P = 0.014), but not with the number of Dmab injections, age, duration of BPs before Dmab initiation, the BMD at Dmab withdrawal, and the prevalence of VFx at Dmab withdrawal. Conclusions The Dmab withdrawal is associated with an increased risk of clinical but not morphometric VFx. Therapy with ALN or with a single ZOL treatment is partially effective in reducing the increased VFx risk after Dmab withdrawal

Hepatic heparan sulfate is a master regulator of hepcidin expression and iron homeostasis in human hepatocytes and mice.

Hepcidin is a liver-derived peptide hormone that controls systemic iron homeostasis. Its expression is regulated by the bone morphogenetic protein 6 (BMP6)/SMAD1/5/8 pathway and by the proinflammatory cytokine interleukin 6 (IL6). Proteoglycans that function as receptors of these signaling proteins in the liver are commonly decorated by heparan sulfate, but the potential role of hepatic heparan sulfate in hepcidin expression and iron homeostasis is unclear. Here, we show that modulation of hepatic heparan sulfate significantly alters hepcidin expression and iron metabolism both in vitro and in vivo Specifically, enzymatic removal of heparan sulfate from primary human hepatocytes, CRISPR/Cas9 manipulation of heparan sulfate biosynthesis in human hepatoma cells, or pharmacological manipulation of heparan sulfate-protein interactions using sodium chlorate or surfen dramatically reduced baseline and BMP6/SMAD1/5/8-dependent hepcidin expression. Moreover inactivation of the heparan sulfate biosynthetic gene N-deacetylase and N-sulfotransferase 1 (Ndst1) in murine hepatocytes (Ndst1 f/f AlbCre +) reduced hepatic hepcidin expression and caused a redistribution of systemic iron, leading to iron accumulation in the liver and serum of mice. Manipulation of heparan sulfate had a similar effect on IL6-dependent hepcidin expression in vitro and suppressed IL6-mediated iron redistribution induced by lipopolysaccharide in vivo These results provide compelling evidence that hepatocyte heparan sulfate plays a key role in regulating hepcidin expression and iron homeostasis in mice and in human hepatocytes

Cortisol Secretion in Patients With Type 2 Diabetes: Relationship With Chronic Complications

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Improved diastolic function in type 2 diabetes after a six month liraglutide treatment

AbstractAimsTo investigate whether liraglutide improves diastolic function in type 2 diabetes.MethodsThirty-seven patients with type 2 diabetes who began liraglutide therapy between June 2013 and May 2014 were enrolled in this observational, prospective study. 26 patients received liraglutide therapy for at least 6months. The remaining 11 patients withdrew from liraglutide therapy during the first month, were started on other hypoglycaemic therapies and formed the control group. Anthropometric, metabolic and echocardiographic parameters including pulsed wave tissue Doppler imaging were evaluated at baseline and at 6months.ResultsIn the liraglutide group the early diastolic mitral annulus velocity on the lateral (e-lat) and medial (e-med) sides of the mitral annulus increased from 9.2±3.4 to 11.6±4.7cm/s (p<0.001) and from 6.9±1.7 to 8.4±2.6cm/s (p<0.003), respectively. The ratio of early-to-late velocities on the lateral and medial sides of the mitral annulus increased from 0.7±0.3 to 0.9±0.4 (p<0.001) and from 0.5±0.1 to 0.6±0.1 (p<0.02), respectively. The ratio of early diastolic mitral inflow velocity to early diastolic myocardial relaxation velocity decreased from 10.7±4.3 to 8.5±2.5 (p<0.005). No improvements in diastolic function was detected in the control group. Glucose control improved similarly in both groups: HA1bc −1.5% (−17mmol/mol) vs −1.3% (−14mmol/mol), p=0.67.ConclusionsIn patients with type 2 diabetes, 6months liraglutide treatment was associated with a significant improvement in diastolic function

Post-surgical Thyroid Bed Pyoderma Gangrenosum Mimicking Recurrent Papillary Thyroid Carcinoma

Background: Pyoderma gangrenosum (PG) is a rare inflammatory disease presenting with chronic-recurrent cutaneous ulcers histopathologically hallmarked by neutrophilic infiltrates, which may occur more frequently at sites of surgical traumas. The disease is habitually limited to the skin, but it can virtually involve any organ. Nevertheless, no prior cases of PG involving the thyroid bed have ever been reported.Case Report: A bilateral PG of the breast was diagnosed in a 51-year-old woman and treated with intravenous methylprednisolone pulse-therapy and cyclosporine, with partial improvement. During the hospitalization, cytological examination of two hypoechoic thyroid nodules by fine-needle aspiration (FNA) was consistent with thyroid carcinoma. After total thyroidectomy, histopathology confirmed a papillary thyroid cancer (PTC), and radioactive iodine ablation was performed. At 12-month ultrasonographic follow-up, two hypoechoic avascular areas localized in the empty thyroid bed raised the suspect of PTC recurrence. However, (i) undetectable levels of thyroglobulin without anti-thyroglobulin antibodies, (ii) neutrophilia and increased inflammatory marker levels, and (iii) cytological examination of FNA showing numerous neutrophils induced to suspect thyroid bed PG infiltration. An ex juvantibus approach with high-dose methylprednisolone led to dimensional reduction of the hypoechoic areas on ultrasonography, thus confirming the hypothesis of thyroid bed PG.Conclusion: This case of thyroid bed PG supports the idea that PG reflects a cutaneous phenotype encompassed in the spectrum of systemic neutrophilic diseases. Endocrinologists should be aware that thyroid bed PG involvement is an albeit rare differential diagnosis to consider in patients who had undergone thyroid surgery, especially with a history of PG

trabecular bone score tbs and bone metabolism in patients affected with type 1 neurofibromatosis nf1

In patients with neurofibromatosis type 1 (NF1), decreased bone mineral density (BMD) and low levels of 25-hydroxy vitamin D3 (25OHD) have been reported. Recently, the trabecular bone score (TBS) measurement has been proposed as index of bone microarchitecture and fracture risk. In 74 NF1 patients (48 females, 26 males, age 41 ± 12), we measured TBS and investigated clinical stage, lifestyle, vitamin D, serum bone turnover markers, vertebral and femoral BMD. A homogenous cohort of 61 healthy subjects was used as control group. TBS was lower in NF1 patients (1.266 ± 0.113 vs. 1.346 ± 0.105) without differences between sexes. No correlations with 25OHD, low exercise, low calcium intake, reduced sun exposure, and number of skin neurofibromas were observed. As expected, hypovitaminosis D was common (98.6%), as well as BMD reduction in hip and spine sites: In NF1 patients, bone texture evaluated by TBS was low in both sexes without any correlation with clinical or metabolic parameters, suggesting a direct role of the fibromin mutation

Heparanase overexpression reduces hepcidin expression, affects iron homeostasis and alters the response to inflammation

Hepcidin is the key regulator of systemic iron availability that acts by controlling the degradation of the iron exporter ferroportin. It is expressed mainly in the liver and regulated by iron, inflammation, erythropoiesis and hypoxia. The various agents that control its expression act mainly via the BMP6/SMAD signaling pathway. Among them are exogenous heparins, which are strong hepcidin repressors with a mechanism of action not fully understood but that may involve the competition with the structurally similar endogenous Heparan Sulfates (HS). To verify this hypothesis, we analyzed how the overexpression of heparanase, the HS degrading enzyme, modified hepcidin expression and iron homeostasis in hepatic cell lines and in transgenic mice. The results showed that transient and stable overexpression of heparanase in HepG2 cells caused a reduction of hepcidin expression and of SMAD5 phosphorylation. Interestingly, the clones showed also altered level of TfR1 and ferritin, indices of a modified iron homeostasis. The heparanase transgenic mice showed a low level of liver hepcidin, an increase of serum and liver iron with a decrease in spleen iron content. The hepcidin expression remained surprisingly low even after treatment with the inflammatory LPS. The finding that modification of HS structure mediated by heparanase overexpression affects hepcidin expression and iron homeostasis supports the hypothesis that HS participate in the mechanisms controlling hepcidin expression