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Parkinson's disease (PD) has been recently associated with the excessive expression of matrix metalloproteinase 3 (MMP3). One of the major challenges in treating PD is to effectively detect and inhibit the early MMP3 activities to relieve the neural stress and inflammation responses. Previously, numerous upconversion nanoparticle (UCNP)-based nanoprobes have been designed for the detection of biomarkers in neurodegenerative diseases. To further improve the performance of the conventional nanoprobes, we introduced novel reporting units and integrated the therapeutic reagents to fabricate a theragnostic platform for PD and other neurodegenerative diseases. Here, we designed a multifunctional UCNP/aggregation-induced emission luminogen (AIEgen)-based nanoprobe to effectively detect the time-lapse MMP3 activities in the inflammatory catecholaminergic SH-SY5Y cells and simultaneously deliver the MMP3-siRNA into the stressed catecholaminergic SH-SY5Y cells, inhibiting the MMP3-induced inflammatory neural responses. The unique features of our UCNP/AIEgen-based nanoprobe platform shed light on the development of a novel theragnostic probe for the early diagnosis and cure of neurodegenerative diseases.

Iron accumulation in the substantia nigra is recognized as a hallmark of Parkinson’s disease (PD). Therefore, reducing accumulated iron and associated oxidative stress is considered a promising therapeutic strategy for PD. However, current iron chelators have poor membrane permeability and lack cell-type specificity. Here we identified GSK-J4, a histone demethylase inhibitor with the ability to cross blood brain barrier, as a potent iron suppressor. Only a trace amount of GSK-J4 significantly and selectively reduced intracellular labile iron in dopaminergic neurons, and suppressed H2O2 and 6-OHDA-induced cell death in vitro. The iron-suppressive effect was mainly mediated by inducing an increase in the expression of the iron exporter ferroportin-1. In parallel, GSK-J4 rescued dopaminergic neuron loss and motor defects in 6-OHDA-induced PD rats, which was accompanied by reduction of oxidative stress. Importantly, GSK-J4 rescued the abnormal changes of histone methylation, H3K4me3 and H3K27me3 during 6-OHDA treatment although the iron-suppressive and neuroprotective effects were sensitive to H3K4me3 inhibition only. Also, upregulating H3K4me3 increased ferroportin-1 expression and neuroprotection. Taken together, we demonstrate a previously unappreciated action of GSK-J4 on cell-specific iron suppression and neuroprotection via epigenetic mechanism. Compared with conventional iron chelators, this compound has a stronger therapeutic potential for PD.

Summary Despite intensive research on Parkinson disease (PD) for decades, this common neurodegenerative disease remains incurable. We hypothesize that abnormal iron accumulation is a common thread underlying the emergence of the hallmarks of PD, namely mitochondrial dysfunction and α-synuclein accumulation. We investigated the powerful action of the main iron regulator hepcidin in the brain. In both the rotenone and 6-hydroxydopamine models of PD, overexpression of hepcidin by means of a virus-based strategy prevented dopamine neuronal loss and suppressed major pathologies of Parkinsonism as well as motor deficits. Hepcidin protected rotenone-induced mitochondrial deficits by reducing cellular and mitochondrial iron accumulation. In addition, hepcidin decreased α-synuclein accumulation and promoted clearance of α-synuclein through decreasing iron content that leads to activation of autophagy. Our results not only pinpoint a critical role of iron-overload in the pathogenesis of PD but also demonstrate that targeting brain iron levels through hepcidin is a promising therapeutic direction., Graphical Abstract, Highlights • Hepcidin rescues motor deficits and dopaminergic neurodegeneration in PD models • Hepcidin represses iron accumulation and mitochondrial deficits in Parkinsonism • Hepcidin promotes clearance of α-synuclein via autophagy activation in PD model • Manipulating brain hepcidin level has potential application in treating PD, Molecular Biology; Neuroscience ; Cell Biology

Prolonged exposure to negative stressors could be harmful if a subject cannot respond appropriately. Strategies evolved to respond to stress, including repetitive displacement behaviours, are important in maintaining behavioural homoeostasis. In rodents, self-grooming is a frequently observed repetitive behaviour believed to contribute to post-stress de-arousal with adaptive value. Here we identified a rat limbic di-synaptic circuit that regulates stress-induced self-grooming with positive affective valence. This circuit links hippocampal ventral subiculum to ventral lateral septum (LSv) and then lateral hypothalamus tuberal nucleus. Optogenetic activation of this circuit triggers delayed but robust excessive grooming with patterns closely resembling those evoked by emotional stress. Consistently, the neural activity of LSv reaches a peak before emotional stress-induced grooming while inhibition of this circuit significantly suppresses grooming triggered by emotional stress. Our results uncover a previously unknown limbic circuitry involved in regulating stress-induced self-grooming and pinpoint a critical role of LSv in this ethologically important behaviour., Self-grooming is a frequently observed repetitive behaviour in rodents that is believed to contribute to post-stress de-arousal. The authors identified a previously unknown limbic circuit that includes the ventral lateral septum in rats and is involved in regulating stress-induced self-grooming.

Background/Aims: The studies in the patients with iron deficiency anemia (IDA) implied the existence of the association of ghrelin with iron or hepcidin levels in the plasma under the pathophysiological conditions. We hypothesized that fasting may be able to affect iron metabolism via ghrelin under the physiological conditions. Methods: We investigated the effects of fasting on serum ghrelin and iron contents in healthy volunteers (23–31 years) and C57BL/6 male mice (8-week-olds) under the physiological conditions. Results: Fasting induced a significant elevation in both total ghrelin and acylated ghrelin and a reduction in iron levels in the serum of both human and mice. Correlation analysis demonstrated that total ghrelin or acylated ghrelin is negatively correlated with iron in the serum in human and mice. Conclusion: Ghrelin has a role to reduce serum iron under the conditions of fasting.

Background: We recently demonstrated that the reduced iron usage due to suppressed erythropoiesis is a major cause of the systemic iron overload in CBS knockout (CBS-/-) mice. However, the molecular mechanisms by which CBS deficiency suppresses erythropoiesis are unknown. Methods: Here, we therefore examined the changes in the ratio of granulocyte/erythroid cells, iron content, the expression of erythropoietin (EPO), iron-metabolism proteins including transferrin receptor 1 (TfR1), ferroportin 1 (Fpn1) and iron regulatory proteins (IRPs), and other molecules that affect iron-metabolism, including hypoxia inducible factor-2 subunit α (HIF-2α), nuclear factor erythroid 2-related factor-2 (Nrf2), and Kelch-like ECH-associated protein 1 (Keap1) in the blood, bone marrow, bone marrow-derived macrophages, liver or spleen of CBS-/- (homozygous), CBS+/- (heterozygous) and CBS+/+ (Wild Type) mice. Findings & Interpretation: Our findings demonstrated that CBS deficiency suppressed erythropoiesis by disrupting iron supply mainly via EPO/IRP/TfR1, Hepcidin/Fpn1, HIF-2α/EPO/Fpn1 and Keap1/Nrf2/Fpn1 pathways in macrophage or erythroid progenitors of rats. Funding: Supported by the National Natural Science Foundation of China (NSFC31571195), and the Competitive Earmarked Grants of the Hong Kong Research Grants Council (GRF14111815, GRF 14167817, GRF14107616). Declaration of Interest: The authors have no financial or competing interests to disclose. Ethical Approval: All animal care and experimental protocols were performed according to the Animal Management Rules of the Ministry of Health of China, and approved by the Animal Ethics Committees of Fudan University (NDFC31271132) and The Chinese University of Hong Kong (GRF14111815).

Hydrogen sulfide (H2 S) has a significant effect on the regulation of interleukin-6 (IL-6) and signal transducer and activator of transcription 3 (STAT3) activities, while IL-6 directly regulates hepcidin expression via STAT3. We therefore hypothesized that H 2 S has a role in body iron homeostasis by regulating the expression of iron transport proteins via the IL-6/STAT3/Hepcidin pathway. Here, we investigated the effects of two H 2 S donors sodium hydrosulfide and GYY4137 on the expression of ferroportin-1 (Fpn1), transferrin receptor-1 (TfR1), hepcidin, IL-6 and pSTAT3 in the spleen of mice in vivo and peritoneal macrophage in vitro. We also examined the effects of H 2 S on serum iron, transferrin saturation, and ferritin light chain contents in the spleen, and on nitrite content, nuclear factor erythroid 2-related factor-2 (Nrf2) and iron regulatory protein 1 (IRP1) in the macrophages. We demonstrated that H 2 S regulates the expression of TfR1 and Fpn1 in the spleen in vivo and in peritoneal macrophages in vitro predominantly via the IL-6/pSTAT3/hepcidin pathway, under the conditions of inflammation induced by lipopolysaccharides. We also provide evidence that under uninflamed conditions, the regulation of Fpn1 and TfR1 expression by H 2 S, both in vivo and in vitro, are mediated by the nitric oxide (NO)/Nrf2 and iron regulatory protein/iron responsive element pathways, respectively, which are independent of IL-6/pSTAT3/hepcidin signals. These findings show that H 2 S is a key player in iron homeostasis under not only the inflamed conditions but also uninflamed conditions.

Iron plays a key role in secondary neuronal injury after intracerebral hemorrhage (ICH), and hepcidin is able to reduce brain iron in iron-overloaded rats by down-regulating iron transport proteins. These led us to hypothesize that hepcidin might reduce iron-mediated neurotoxicity by inhibiting iron accumulation in ICH brain. Here, we tested our hypothesis in 510 rats and demonstrated for the first time that hepcidin could significantly suppress the ICH-induced increase in iron and ferritin in brain tissues and cerebrospinal fluid by inhibiting expression of iron transport proteins, increase neuronal survival by attenuating ICH-induced apoptosis, neurodegeneration and brain edema, as well as effectively improve ICH-induced behavioral and cognitive deficit in rats. We concluded that hepcidin could effectively attenuate iron-mediated secondary neuronal injury after ICH in rats. This naturally existing protein which is biodegradable, nontoxic, and non-immunogenic can potentially be developed into a therapeutic drug for the treatment of ICH patients. Funding: The studies were supported by the National Natural Science Foundation of China (NSFC31330035-ZMQ, NSFC31571195-ZMQ), the Competitive Earmarked Grants of The Hong Kong Research Grants Council (GRF14111815-KY, GRF 14167817-KY, GRF14107616-KY), Hong Kong Health & Medical Research Fund (HMRF: 03141436-KY), Hong Kong Innovation and Technology Fund (ITS/163/16-KY), and the National 973 Programs (2014CB541604-ZMQ). Conflict of interest: The authors declare that they have no conflict of interest. Ethical Approval Statement: The Health Department of Hong Kong and Shanghai Government and the Animal Research Ethics Committee of The Chinese University of Hong Kong and Fudan University approved the experimental procedures of this study and the care and handling of the animals were in accord with National Institutes of Health guidelines.

Cystathionine β-synthase (CBS) catalyzes the transsulfuration pathway and contributes, among other functions, to the generation of hydrogen sulfide (H2S). In view of the exceptionally high expression of CBS in the liver and the common interleukin-6 (IL-6) pathway utilized in the regulatory systems of H2S and hepcidin, we speculate that CBS is involved in body iron homeostasis. We found that CBS knock-out (CBS-/-) mice exhibited anemia and a significant increase in iron content in the serum, liver, spleen and heart, along with severe damage to the liver, displaying a hemochromatosis-like phenotype. A high level of hepatic and serum hepcidin was also found. A major cause of the systemic iron-overload is the reduced iron utilization due to suppressed erythropoiesis, which is consistent with an increase in IL-6 and the reduced expression of erythropoietin. Importantly, in the liver, an absence of CBS caused both a reduction in the transcriptional factor NRF2 and an upregulation of hepcidin that lead to a decrease in the iron export protein ferroportin 1. The resulting suppression of iron export exacerbates iron retention, causing damage to hepatocytes. Finally, administration of CBS-overexpressing adenovirus into CBS mutant mice could partially reverse the iron-related phenotype. Our findings thus point to a previously unknown, yet critical role of CBS in iron homeostasis of the body, and the liver in particular. It is likely that a hemochromatosis-like phenotype in patients can be induced by aberration not only in the expression of key molecules in the hepcidin pathway, but also in those related to CBS. This article is protected by copyright. All rights reserved.