Vitamin B12-impaired metabolism produces apoptosis and Parkinson phenotype in rats expressing the transcobalamin-oleosin chimera in substantia nigra

Parkinson's disease and vitamins: a focus on vitamin B12

Parkinson's disease (PD) has been linked to a vast array of vitamins among which vitamin B12 (Vit B12) is the most relevant and often investigated specially in the context of intrajejunal levodopa infusion therapy. Vit B12 deficiency, itself, has been reported to cause acute parkinsonism. Nevertheless, concrete mechanisms through which B12 deficiency interacts with PD in terms of pathophysiology, clinical manifestation and progression remains unclear. Recent studies have suggested that Vit B12 deficiency along with the induced hyperhomocysteinemia are correlated with specific PD phenotypes characterized with early postural instability and falls and more rapid motor progression, cognitive impairment, visual hallucinations and autonomic dysfunction. Specific clinical features such as polyneuropathy have also been linked to Vit B12 deficiency specifically in context of intrajejunal levodopa therapy. In this review, we explore the link between Vit B12 and PD in terms of physiopathology regarding dysfunctional neural pathways, neuropathological processes as well as reviewing the major clinical traits of Vit B12 deficiency in PD and Levodopa-mediated neuropathy. Finally, we provide an overview of the therapeutic effect of Vit B12 supplementation in PD and posit a practical guideline for Vit B12 testing and supplementation.

Neuroprotective role of vitamin B12 in streptozotocin-induced type 1 diabetic rats

Chronic hyperglycemia-induced neuropathological changes include neuronal apoptosis, astrogliosis, decrease in neurotrophic support, impaired synaptic plasticity, and impaired protein quality control (PQC) system. Vitamin B12 is indispensable for neuronal development and brain function. Several studies reported the neuroprotective effect of B12 supplementation in diabetic patients. However, the underlying molecular basis for the neuroprotective effect of B12 supplementation in diabetes needs to be thoroughly investigated. Two-month-old Sprague-Dawley rats were randomly assigned into three groups: Control (CN), diabetes (D; induced with streptozotocin; STZ), and diabetic rats supplemented with vitamin B12 (DBS; vitamin B12; 50 μg/kg) for four months. At the end of 4 months of experimentation, the brain was dissected to collect the cerebral cortex (CC). The morphology of CC was investigated with H&E and Nissl body staining. Neuronal apoptosis was determined with TUNEL assay. The components of neurotrophic support, astrogliosis, synaptic plasticity, and PQC processes were investigated by immunoblotting and immunostaining methods. H& E, Nissl body, and TUNEL staining revealed that diabetes-induced neuronal apoptosis and degeneration. However, B12 supplementation ameliorated the diabetes-induced neuronal apoptosis. Further, B12 supplementation restored the markers of neurotrophic support (BDNF, NGF, and GDNF), and synaptic plasticity (SYP, and PSD-95) in diabetic rats. Interestingly, B12 supplementation also attenuated astrogliosis, ER stress, and ameliorated autophagy-related proteins in diabetic rats. Overall, these findings suggest that B12 acts as a neuroprotective agent by inhibiting the neuropathological changes in STZ-induced type 1 diabetes. Thus, B12 supplementation could produce beneficial outcomes including neuroprotective effects in diabetic patients.

Could Vitamins Have a Positive Impact on the Treatment of Parkinson's Disease?

Parkinson's disease (PD) is the second most common progressive neurodegenerative disorder after Alzheimer's disease. Pathophysiologically, it is characterized by intracytoplasmic aggregates of α-synuclein protein in the Lewy body and loss of dopaminergic neurons from substantia nigra pars compacta and striatum regions of the brain. Although the exact mechanism of neurodegeneration is not fully elucidated, it has been reported that environmental toxins such as MPTP, rotenone, paraquat, and MPP⁺ induce oxidative stress, which is one of the causative factors for it. To date, there is no complete cure. However, the indispensable role of oxidative stress in mediating PD indicates that antioxidant therapy could be a possible therapeutic strategy against the disease. The deficiency of vitamins has been extensively co-related to PD. Dietary supplementation of vitamins with antioxidant, anti-inflammatory, anti-apoptotic, and free radical scavenging properties could be the potential neuroprotective therapeutic strategy. This review summarizes the studies that evaluated the role of vitamins (A, B, C, D, E, and K) in PD. It will guide future studies in understanding the potential therapeutic role of vitamins in disease pathophysiology and may provide a framework for designing treatment strategies against the disease.

Pituitary Pars Intermedia Dysfunction (PPID) in Horses

Substantial morbidity results from pituitary pars intermedia dysfunction (PPID) which is often underestimated by owners and veterinarians. Clinical signs, pathophysiology, diagnostic tests, and treatment protocols of this condition are reviewed. The importance of improved recognition of early clinical signs and diagnosis are highlighted, as initiation of treatment will result in improved quality of life. Future research should be targeted at improving the accuracy of the diagnosis of PPID, as basal adrenocorticotropic hormone (ACTH) concentration can lack sensitivity and thyrotropin releasing hormone (TRH) used to assess ACTH response to TRH stimulation is not commercially available as a sterile registered product in many countries. The relationship between PPID and insulin dysregulation and its association with laminitis, as well as additional management practices and long-term responses to treatment with pergolide also require further investigation.

Behavioral profile of vitamin B12 deficiency: A reflection of impaired brain development, neuronal stress and altered neuroplasticity

Our understanding of brain biology and function is one of the least characterized and therefore, there are no effective treatments for most of neurological disorders. The influence of vitamins, and particularly vitamin B₁₂, in neurodegenerative disease is demonstrated but largely unresolved. Behaviors are often quantified to attest brain dysfunction alone or in parallel with neuro-imaging to identify regions involved. Nevertheless, attention should be paid to extending observations made in animal models to humans, since, first, behavioral tests have to be adjusted in each model to address the initial question and second, because brain analysis should not be conducted for a whole organ but rather to specific sub-structures to better define function. Indeed, cognitive functions such as psychiatric disorders and learning and memory are often cited as the most impacted by a vitamin B₁₂ deficiency. In addition, differential dysfunctions and mechanisms could be defined according sub-populations and ages. Vitamin B₁₂ enters the cell bound to Transcobalamin, through the Transcobalamin Receptor and serves in two cell compartments, the lipid metabolism in the mitochondrion and the one-carbon metabolism involved in methylation reactions. Dysfunctions in these mechanisms can lead to two majors outcomes; axons demyelinisation and upregulation of cellular stress involving mislocalization of RNA binding proteins such as the ELAVL1/HuR or the dysregulation of pro- or anti-oxidant NUDT15, TXNRD1, VPO1 and ROC genes. Finally, it appears that apart from developmental problems that have to be identified and treated as early as possible, other therapeutic approaches for behavioral dysfunctions should investigate cellular methylation, oxidative and endoplasmic reticulum stress and mitochondrial function.

Exposure to anesthesia is not associated with development of α-synucleinopathies: A nested case-control study

INTRODUCTION

Preclinical studies suggest that inhalational anesthetics may induce neuropathology changes in the nigrostriatal system, leading to development of α-synucleinopathies. We explored the role of general anesthesia in the development of Parkinson disease (PD) and other α-synucleinopathies.

METHODS

All α-synucleinopathy cases in Olmsted County, Minnesota, from January 1991, to December 2010, were identified from diagnostic codes, and then reviewed for type and index date of diagnosis. Cases were matched by sex and age (±1 year) to a referent control, a resident living in Olmsted County, and free of α-synucleinopathies before the index date (year of onset of the α-synucleinopathy). Medical records of both cases and controls were reviewed for lifetime exposure to anesthesia prior to the index date.

RESULTS

A total of 431 cases with clinically defined α-synucleinopathies were identified. Of these, 321 (74%) underwent 1,069 procedures under anesthesia before the diagnosis date, and in the control group, 341 (79%) underwent 986 procedures. When assessed as a dichotomous variable, anesthetic exposure was not significantly associated with α-synucleinopathies (odds ratio [OR], 0.75; 95% CI, 0.54-1.05; P=.094). No association was observed when anesthetic exposure was quantified by the number of exposures (OR, 0.64, 0.89, and  0.74, for 1, 2-3, and ≥4 exposures, respectively, compared to no exposure as the reference; P=.137) or quantified by the cumulative duration of exposure assessed as a continuous variable (OR, 1.00; 95% CI, 0.97-1.02 per 1-h increase of anesthetic exposure; P=.776).

CONCLUSIONS

We did not observe a significant association between exposure to general anesthesia and risk for the development of α-synucleinopathies.

Evidence to Support the Use of S-Adenosylmethionine for Treatment of Post-Concussive Sequelae in the Military

INTRODUCTION

Since the year 2000, over 413,000 service members have sustained traumatic brain injury (TBI) and may present with post-concussive sequelae including headaches, fatigue, irritability, cognitive problems, depression, insomnia, and chronic pain. Although the focus of the article is on military TBI, the usefulness of S-adenosylmethionine (SAMe) would extend to both civilian and military populations. This narrative review examines the preclinical and clinical literature of SAMe's metabolism and alterations seen in disease states such as depressive disorders, pain disorders, fatigue, cognition, dementia, use in pregnancy and peripartum, children, adolescents, and adults, to the elderly with and without dementia, stroke, and neurodegeneration, in order to highlight its potential benefit in post-concussive sequelae after TBI.

MATERIALS AND METHODS

A MEDLINE/PubMed and Cochrane Database search was conducted between May 3, 2018 and July 30, 2019 by combining search terms for SAMe with terms for relevant disease states including depression, brain injury, dementia, Alzheimer's disease, Parkinson's disease, cognition, fatigue, and pain. This search retrieved a total of 676 references. 439 were excluded for being over a 10-year publication date, except where clinically relevant. After additional removal of repeated articles, the number of articles were totaled 197. An additional 59 articles were excluded: 10 not in English, 4 duplicates, 4 not original investigations, and 41 outside the scope of this article. The remaining 138 articles were used in this review and included 25 clinical studies, 46 preclinical studies, 63 reviews, and 4 case reports.

RESULTS

This narrative review examined the preclinical and clinical literature of SAMe's metabolism and alterations seen in MDD, pain disorders, fatigue, cognition and memory, dementia, and other disorders to highlight the potential benefit of SAMe in post-concussive sequelae in mTBI. The literature showed potential for improvement, safety, and tolerability in these symptom clusters commonly seen in military mild TBI (mTBI).

CONCLUSION

There is evidence of a potential benefit of SAMe as an intervention to help with symptoms across the range of post-concussive sequelae and syndromes commonly seen in military mTBI. Since the discovery of SAMe in 1952, this pleiotropic molecule has shown the significance of its involvement in several metabolic cascades in such disparate systems as epigenetics, bioenergetics, DNA methylation, neurotransmitter systems, and potential usefulness in military TBI. Significant limitations include disparate presentations seen in patients with mild TBI, those with post-concussive syndrome, as well as those with comorbid depression and posttraumatic stress disorder. Also, over-the-counter medications are not regulated and SAMe products may vary widely in price and quality. Given the potential for mania in patients with bipolar disorder, evaluation and recommendations should be made by a physician able to evaluate the underlying bipolar diathesis. Furthermore, this narrative review serves as the rationale for future open-label and double-blind placebo-controlled trials in military mTBI and SAMe.

Gastrectomy, vitamin B12 supplementation and the risk of Parkinson's disease: A nationwide cohort study

INTRODUCTION

Previous evidence has suggested roles for α-synuclein propagation and vitamin B12 (VitB12) deficiency in the pathogenesis of Parkinson's disease (PD). We investigated whether gastric cancer (GC) patients who underwent gastrectomy had a lower risk of PD and whether VitB12 supplementation modified the risk.

METHODS

GC patients aged ≥50 years who underwent curative gastrectomy between 2007 and 2012 (n = 72,216) and matched comparison groups (n = 211,389) were identified from the Korean National Health Insurance database. The risks of PD were analyzed by Cox regression.

RESULTS

Compared to their matched comparison groups, GC patients who underwent gastrectomy showed a decreased risk of PD (adjusted HR [aHR] 0.86; 95% confidence interval [CI] 0.75-0.98), but the significance disappeared after further adjustment with smoking and body mass index (BMI). To elaborate, subtotal gastrectomy (STG) was associated with decreased risk of PD (aHR 0.85; 95% CI 0.74-0.99) while total gastrectomy (TG) was not (aHR 0.89; 95% CI 0.66-1.19), although the risk reduction was not significant when further adjusted for smoking and BMI. Among the patients who underwent TG, their risk of PD was markedly lower when they had VitB12 supplementation after surgery (aHR 0.36; 95% CI 0.17-0.76), while the risk was higher when they did not have any (aHR 1.55; 95% CI 1.03-2.32).

CONCLUSIONS

GC patients who underwent gastrectomy and received uninterrupted VitB12 supplementation had a decreased incidence of PD. This study provides indirect epidemiological evidence for the potential roles of gastrectomy and VitB12 in the pathogenesis of PD.

Synthetic Monopartite Peptide That Enables the Nuclear Import of Genes Delivered by the Neurotensin-Polyplex Vector

Neurotensin (NTS)-polyplex is a multicomponent nonviral vector that enables gene delivery via internalization of the neurotensin type 1 receptor (NTSR1) to dopaminergic neurons and cancer cells. An approach to improving its therapeutic safety is replacing the viral karyophilic component (peptide KPSV40; MAPTKRKGSCPGAAPNKPK), which performs the nuclear import activity, by a shorter synthetic peptide (KPRa; KMAPKKRK). We explored this issue and the mechanism of plasmid DNA translocation through the expression of the green fluorescent protein or red fluorescent protein fused with KPRa and internalization assays and whole-cell patch-clamp configuration experiments in a single cell together with importin α/β pathway blockers. We showed that KPRa electrostatically bound to plasmid DNA increased the transgene expression compared with KPSV40 and enabled nuclear translocation of KPRa-fused red fluorescent proteins and plasmid DNA. Such translocation was blocked with ivermectin or mifepristone, suggesting importin α/β pathway mediation. KPRa also enabled NTS-polyplex-mediated expression of reporter or physiological genes such as human mesencephalic-derived neurotrophic factor (hMANF) in dopaminergic neurons in vivo. KPRa is a synthetic monopartite peptide that showed nuclear import activity in NTS-polyplex vector-mediated gene delivery. KPRa could also improve the transfection of other nonviral vectors used in gene therapy.

Relationships of inflamm-aging with circulating nutrient levels, body composition, age, and pituitary pars intermedia dysfunction in a senior horse population

Similarly to aged humans, senior horses (≥20 years) exhibit chronic low-grade inflammation systemically, known as inflamm-aging. Inflamm-aging in the senior horse has been characterized by increased circulating inflammatory cytokines as well as increased inflammatory cytokine production by lymphocytes and monocytes in response to a mitogen. Little is currently known regarding underlying causes of inflamm-aging. However, senior horses are also known to present with muscle wasting and often the endocrinopathy pituitary pars intermedia dysfunction (PPID). Despite the concurrence of these phenomena, the relationships inflamm-aging may have with measures of body composition and pituitary function in the horse remain unknown. Furthermore, nutrition has been a focus of research in an attempt to promote health span as well as life span in senior horses, with some nutrients, such as omega-3 fatty acids, having known anti-inflammatory effects. Thus, an exploratory study of a population of n = 42 similarly-managed senior horses was conducted to determine relationships between inflamm-aging and measures of circulating nutrients, body composition, age, and PPID. Serum was collected to determine vitamin, mineral, and fatty acid content. Peripheral blood mononuclear cells were also isolated to determine inflammatory cytokine production of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) following stimulation with a mitogen, as well as to determine gene expression of interleukin(IL)-1β, IL-6, IL-10, IFN-γ, and TNF-α. Serum IL-6 and C-reactive protein were determined by enzyme-linked immunosorbent assay. Whole blood was collected for hematological and biochemical analysis. Body composition was evaluated via ultrasound and muscle scoring for all 42 horses as well as by deuterium oxide dilution for a subset of n = 10 horses. Pituitary function was evaluated by measuring basal adrenocorticotropin hormone concentrations as well as by thyrotropin releasing hormone stimulation testing (to determine PPID status). Results showed various relationships between inflammatory markers and the other variables measured. Most notably, docosadienoic acid (C22:2n6c), docosapentaenoic acid (C22:5n3c), and folate were positively associated with numerous inflammatory parameters (P ≤ 0.05). Although no relationships were found between inflamm-aging and PPID, being positive for PPID was negatively associated with vitamin B12 (P ≤ 0.01). No relationships between inflammation and body composition were found. Even within this senior horse population, age was associated with multiple parameters, particularly with numerous inflammatory cytokines and fatty acids. In summary, inflamm-aging exhibited relationships with various other parameters examined, particularly with certain fatty acids. This exploratory study provides insights into physiological changes associated with inflamm-aging in the senior horse.

Implication of homocysteine in protein quality control processes

Homocysteine (Hcy) is a key metabolite generated during methionine metabolism. The elevated levels of Hcy in the blood are reffered to as hyperhomocystenimeia (HHcy). The HHcy is caused by impaired metabolism/deficiency of either folate or B12 or defects in Hcy metabolism. Accumulating evidence suggests that HHcy is associated with cardiovascular and brain diseases including atherosclerosis, endothelial injury, and stroke etc. Vitamin B12 (cobalamin; B12) is a water-soluble vitamin essential for two metabolic reactions. It acts as a co-factor for methionine synthase and L-methylmalonyl-CoA mutase. Besides, it is also vital for DNA synthesis and maturation of RBC. Deficiency of B12 is associated with haematological and neurological disorders. Hyperhomocysteinemia (HHcy)-induced toxicity is thought to be mediated by the accumulation of Hcy and its metabolites, homocysteinylated proteins. Cellular protein quality control (PQC) is essential for the maintenance of proteome integrity, and cell viability and its failure contributes to the development of multiple diseases. Chaperones, unfolded protein response (UPR), ubiquitin-proteasome system (UPS), and autophagy are analogous strategies of PQC that maintain cellular proteome integrity. Recently, multiple studies reported that HHcy responsible for perturbation of PQC by reducing chaperone levels, activating UPR, and impairing autophagy. Besides, HHcy also induce cytotoxicity, inflammation, protein aggregation and apoptosis. It has been shown that some of the factors including altered SIRT1-HSF1 axis and irreversible homocysteinylation of proteins are responsible for folate and/or B12 deficiency or HHcy-induced impairment of PQC. Therefore, this review highlights the current understanding of HHcy in the context of cellular PQC and their pathophysiological and clinical consequences, epigenomic changes, therapeutic implications of B12, and chemical chaperones based on cell culture and experimental animal models.

Increased MMAB level in mitochondria as a novel biomarker of hepatotoxicity induced by Efavirenz

Background

Efavirenz (EFV), a non-nucleoside reverse transcriptase inhibitor (NNRTI), has been widely used in the therapy of human immunodeficiency virus (HIV) infection. Some of its toxic effects on hepatic cells have been reported to display features of mitochondrial dysfunction through bioenergetic stress and autophagy, etc. However, alteration of protein levels, especially mitochondrial protein levels, in hepatic cells during treatment of EFV has not been fully investigated.

Methods

We built a cell model of EFV-induced liver toxicity through treating Huh-7 cells with different concentrations of EFV for different time followed by the analysis of cell viability using cell counting kit -8 (CCK8) and reactive oxygen species (ROS) using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) and MitoSox dye. Proteomic profiles in the mitochondria of Huh-7 cells stimulated by EFV were analyzed. Four differentially expressed proteins were quantified by real time RT-PCR. We also detected the expression of mitochondrial precursor Cob(I)yrinic acid a,c-diamide adenosyltransferase (MMAB) by immunohistochemistry analysis in clinical samples. The expression levels of MMAB and ROS were detected in EFV-treated Huh-7 cells with and without shRNA used to knock down MMAB, and in primary hepatocytes (PHC). The effects of other anti-HIV drugs (nevirapine (NVP) and tenofovirdisoproxil (TDF)), and hydrogen peroxide (H₂O₂) were also tested. Amino acid analysis and fatty aldehyde dehydrogenase (ALDH3A2) expression after MMAB expression knock-down with shRNA was used to investigate the metabolic effect of MMAB in Huh-7 cells.

Results

EFV treatment inhibited cell viability and increased ROS production with time- and concentration-dependence. Proteomic study was performed at 2 hours after EFV treatment. After treated Huh-7 cells with EFV (2.5mg/L or 10 mg/L) for 2 h, fifteen differentially expressed protein spots from purified mitochondrion that included four mitochondria proteins were detected in EFV-treated Huh-7 cells compared to controls. Consistent with protein expression levels, mRNA expression levels of mitochondrial protein MMAB were also increased by EFV treatment. In addition, the liver of EFV-treated HIV infected patients showed substantially higher levels of MMAB expression compared to the livers of untreated or protease inhibitor (PI)-treated HIV-infected patients. Furthermore, ROS were found to be decreased in Huh-7 cells treated with shMMAB compared with empty plasmid treated with EFV at the concentration of 2.5 or 10 mg/L. MMAB was increased in EFV-treated Huh-7 cells and primary hepatocytes. However, no change in MMAB expression was detected after treatment of Huh-7 cells and primary hepatocytes with anti-HIV drugs nevirapine (NVP) and tenofovirdisoproxil (TDF), or hydrogen peroxide (H₂O₂), although ROS was increased in these cells. Finally, knockdown of MMAB by shRNA induced increases in the β-Alanine (β-Ala) production levels and decrease in ALDH3A2 expression.

Conclusions

A mitochondrial proteomic study was performed to study the proteins related to EFV-inducted liver toxicity. MMAB might be a target and potential biomarker of hepatotoxicity in EFV-induced liver toxicity.

Neurturin overexpression in dopaminergic neurons induces presynaptic and postsynaptic structural changes in rats with chronic 6-hydroxydopamine lesion

The structural effect of neurturin (NRTN) on the nigrostriatal dopaminergic system in animals remains unknown, although NRTN has been shown to be effective in Parkinson's disease animal models. Herein, we aimed to demonstrate that NRTN overexpression in dopaminergic neurons stimulates both neurite outgrowths in the nigrostriatal pathway and striatal dendritic spines in aging rats with chronic 6-hydroxydopamine (6-OHDA) lesion. At week 12 after lesion, pTracer-mNRTN-His or pGreenLantern-1 plasmids were intranigrally transfected using the NTS-polyplex nanoparticles system. We showed that the transgenic expression in dopaminergic neurons remained until the end of the study (12 weeks). Only animals expressing NRTN-His showed recovery of tyrosine hydroxylase (TH)+ cells (28 ± 2%), their neurites (32 ± 2%) and the neuron-specific cytoskeletal marker β-III-tubulin in the substantia nigra; striatal TH(+) fibers were also recovered (52 ± 3%), when compared to the healthy condition. Neurotensin receptor type 1 levels were also significantly recovered in the substantia nigra and striatum. Dopamine recovery was 70 ± 4% in the striatum and complete in the substantia nigra. The number of dendritic spines of striatal medium spiny neurons was also significantly increased, but the recovery was not complete. Drug-activated circling behavior decreased by 73 ± 2% (methamphetamine) and 89 ± 1% (apomorphine). Similar decrease was observed in the spontaneous motor behavior. Our results demonstrate that NRTN causes presynaptic and postsynaptic restoration of the nigrostriatal dopaminergic system after a 6-OHDA-induced chronic lesion. However, those improvements did not reach the healthy condition, suggesting that NRTN exerts lesser neurotrophic effects than other neurotrophic approaches.

Regulation of human GDNF gene expression in nigral dopaminergic neurons using a new doxycycline-regulated NTS-polyplex nanoparticle system

The human glial-cell derived neurotrophic factor (hGDNF) gene transfer by neurotensin (NTS)-polyplex nanoparticles functionally restores the dopamine nigrostriatal system in experimental Parkinson's disease models. However, high levels of sustained expression of GDNF eventually can cause harmful effects. Herein, we report an improved NTS-polyplex nanoparticle system that enables regulation of hGDNF expression within dopaminergic neurons. We constructed NTS-polyplex nanoparticles containing a single bifunctional plasmid that codes for the reverse tetracycline-controlled transactivator advanced (rtTA-Adv) under the control of NBRE3x promoter, and for hGDNF under the control of tetracycline-response element (TRE). Another bifunctional plasmid contained the enhanced green fluorescent protein (GFP) gene. Transient transfection experiments in N1E-115-Nurr1 cells showed that doxycycline (100 ng/mL) activates hGDNF and GFP expression. Doxycycline (5 mg/kg, i.p.) administration in rats activated hGDNF expression only in transfected dopaminergic neurons, whereas doxycycline withdrawal silenced transgene expression. Our results offer a specific doxycycline-regulated system suitable for nanomedicine-based treatment of Parkinson's disease.

Neurotensin-polyplex-mediated brain-derived neurotrophic factor gene delivery into nigral dopamine neurons prevents nigrostriatal degeneration in a rat model of early Parkinson's disease

Background

The neurotrophin Brain-Derived Neurotrophic Factor (BDNF) influences nigral dopaminergic neurons via autocrine and paracrine mechanisms. The reduction of BDNF expression in Parkinson’s disease substantia nigra (SN) might contribute to the death of dopaminergic neurons because inhibiting BDNF expression in the SN causes parkinsonism in the rat. This study aimed to demonstrate that increasing BDNF expression in dopaminergic neurons of rats with one week of 6-hydroxydopamine lesion recovers from parkinsonism. The plasmids phDAT-BDNF-flag and phDAT-EGFP, coding for enhanced green fluorescent protein, were transfected using neurotensin (NTS)-polyplex, which enables delivery of genes into the dopaminergic neurons via neurotensin-receptor type 1 (NTSR1) internalization.

Results

Two weeks after transfections, RT-PCR and immunofluorescence techniques showed that the residual dopaminergic neurons retain NTSR1 expression and susceptibility to be transfected by the NTS-polyplex. phDAT-BDNF-flag transfection did not increase dopaminergic neurons, but caused 7-fold increase in dopamine fibers within the SN and 5-fold increase in innervation and dopamine levels in the striatum. These neurotrophic effects were accompanied by a significant improvement in motor behavior.

Conclusions

NTS-polyplex-mediated BDNF overexpression in dopaminergic neurons has proven to be effective to remit hemiparkinsonism in the rat. This BDNF gene therapy might be helpful in the early stage of Parkinson’s disease.

Suicide HSVtk gene delivery by neurotensin-polyplex nanoparticles via the bloodstream and GCV Treatment specifically inhibit the growth of human MDA-MB-231 triple negative breast cancer tumors xenografted in athymic mice

The human breast adenocarcinoma cell line MDA-MB-231 has the triple-negative breast cancer (TNBC) phenotype, which is an aggressive subtype with no specific treatment. MDA-MB-231 cells express neurotensin receptor type 1 (NTSR1), which makes these cells an attractive target of therapeutic genes that are delivered by the neurotensin (NTS)-polyplex nanocarrier via the bloodstream. We addressed the relevance of this strategy for TNBC treatment using NTS-polyplex nanoparticles harboring the herpes simplex virus thymidine kinase (HSVtk) suicide gene and its complementary prodrug ganciclovir (GCV). The reporter gene encoding green fluorescent protein (GFP) was used as a control. NTS-polyplex successfully transfected both genes in cultured MDA-MB-231 cells. The transfection was demonstrated pharmacologically to be dependent on activation of NTSR1. The expression of HSVtk gene decreased cell viability by 49% (P<0.0001) and induced apoptosis in cultured MDA-MB-231 cells after complementary GCV treatment. In the MDA-MB-231 xenograft model, NTS-polyplex nanoparticles carrying either the HSVtk gene or GFP gene were injected into the tumors or via the bloodstream. Both routes of administration allowed the NTS-polyplex nanoparticles to reach and transfect tumorous cells. HSVtk expression and GCV led to apoptosis, as shown by the presence of cleaved caspase-3 and Apostain immunoreactivity, and significantly inhibited the tumor growth (55-60%) (P<0.001). At the end of the experiment, the weight of tumors transfected with the HSVtk gene was 55% less than that of control tumors (P<0.05). The intravenous transfection did not induce apoptosis in peripheral organs. Our results offer a promising gene therapy for TNBC using the NTS-polyplex nanocarrier.

Exposure to anesthetic gases and Parkinson's disease: a case report

BACKGROUND

The administration of anesthetics determines depression of the central nervous system and general anesthesia by inhalation may cause an environmental pollution of the operating rooms. It may therefore conceive a possible occupational etiology of Parkinson's Disease (PD).

CASE PRESENTATION

In a Caucasian male aged 59 years, PD was diagnosed by brain scans with a presynaptic radioactive tracer of the dopaminergic system. Family history was negative for Parkinson's disease or essential tremor. He was a smoker, a moderate consumer of coffee and alcohol, and never exposed to pesticides/metals. For 30 years (since the age of 29 until today), he worked as an anesthesiologist in private clinics in the Veneto (Northern Italy), exposed to anesthetic gases. The time elapsed from first exposure to onset of disease is 22 years, fulfilling the requirement of the induction/latency period. A literature search demonstrated unacceptable levels of anesthetic gases in public hospitals of the Veneto region from 1990 to 1999. This exposure was presumably high also in private hospitals of the region until at least 2007, when an overexposure to sevoflurane was repeatedly measured in this patient. The association between occupational exposure to anesthetic gases and risk of Parkinson's disease was supported by a case-control study (reporting a two-fold increase in the risk of PD associated with a clinical history of general anesthesia) and a cohort study comparing mortality from PD between US anesthesiologists and internists (showing a statistically significant excess (p=0.01) in anesthesiologists compared to internists). Numerous recent mechanistic studies (in vitro essays and in vivo short-term studies) strengthened the association between exposure to anesthetic gases (nitrous oxide, halothane, isoflurane, levoflurane) and PD.

CONCLUSION

In view of the limited evidence of human studies and the sufficient evidence of experimental studies, the high exposure to anesthetic gases could have induced PD in the subject under study.

[History of the therapy of pernicious anemia]

Increased blood cell regeneration in exsanguinated experimental animals treated either with liver or with aqueous liver extracts was reported by Whipple and by Jeney and Jobling, respectively. These findings stimulated Minot and Murphy to provide evidence for the efficacy of liver against anaemia in clinical studies. After oral administration of liver (45-50 g per day) for 45 patients with anaemia perniciosa improvement of the hematological status was demonstrated. Consequently, for proving the therapeutic value of liver therapy Whipple, Minot and Murphy received Nobel price in 1934. The isolation of the antianemic factor from the liver has been succeeded in 1948 and designated as vitamin B12. At the same time Lucy Wills applied yeast for the treatment of pregnant women with anemia related to undernourishment. The conclusions of this study inspired the discovery of folate. The detailed investigation of the mode of action of vitamin B12 and folate enriched our knowledge in the area of pathophysiology and extended the clinical application of these two drugs.

Decreased vitamin B12 availability induces ER stress through impaired SIRT1-deacetylation of HSF1

Vitamin B12 (cobalamin) is a key determinant of S-adenosyl methionine (SAM)-dependent epigenomic cellular regulations related to methylation/acetylation and its deficiency produces neurodegenerative disorders by elusive mechanisms. Sirtuin 1 deacetylase (SIRT1) triggers cell response to nutritional stress through endoplasmic reticulum (ER) stress. Recently, we have established a N1E115 dopaminergic cell model by stable expression of a transcobalamin–oleosin chimera (TO), which impairs cellular availability of vitamin B12, decreases methionine synthase activity and SAM level, and reduces cell proliferation. In contrast, oleosin-transcobalamin chimera (OT) does not modify the phenotype of transfected cells. Presently, the impaired cellular availability of vitamin B12 in TO cells activated irreversible ER stress pathways, with increased P-eIF-2α, P-PERK, P-IRE1α, ATF6, ATF4, decreased chaperon proteins and increased pro-apoptotic markers, CHOP and cleaved caspase 3, through reduced SIRT1 expression and consequently greater acetylation of heat-shock factor protein 1 (HSF1). Adding either B12, SIRT1, or HSF1 activators as well as overexpressing SIRT1 or HSF1 dramatically reduced the activation of ER stress pathways in TO cells. Conversely, impairing SIRT1 and HSF1 by siRNA, expressing a dominant negative form of HSF1, or adding a SIRT1 inhibitor led to B12-dependent ER stress in OT cells. Addition of B12 abolished the activation of stress transducers and apoptosis, and increased the expression of protein chaperons in OT cells subjected to thapsigargin, a strong ER stress stimulator. AdoX, an inhibitor of methyltransferase activities, produced similar effects than decreased B12 availability on SIRT1 and ER stress by a mechanism related to increased expression of hypermethylated in cancer 1 (HIC1). Taken together, these data show that cellular vitamin B12 has a strong modulating influence on ER stress in N1E115 dopaminergic cells. The impaired cellular availability in vitamin B12 induces irreversible ER stress by greater acetylation of HSF1 through decreased SIRT1 expression, whereas adding vitamin B12 produces protective effects in cells subjected to ER stress stimulation.

Molecular and cellular effects of vitamin B12 in brain, myocardium and liver through its role as co-factor of methionine synthase

Vitamin B12 (cobalamin, cbl) is a cofactor of methionine synthase (MTR) in the synthesis of methionine, the precursor of the universal methyl donor S-Adenosylmethionine (SAM), which is involved in epigenomic regulatory mechanisms. We have established a neuronal cell model with stable expression of a transcobalamin-oleosin chimer and subsequent decreased cellular availability of vitamin B12, which produces reduced proliferation, increased apoptosis and accelerated differentiation through PP2A, NGF and TACE pathways. Anti-transcobalamin antibody or impaired transcobalamin receptor expression produce also impaired proliferation in other cells. Consistently, the transcription, protein expression and activity of MTR are increased in proliferating cells of skin and intestinal epitheliums, in rat intestine crypts and in proliferating CaCo2 cells, while MTR activity correlates with DNA methylation in rat intestine villi. Exposure to nitrous oxide in animal models identified impairment of MTR reaction as the most important metabolic cause of neurological manifestations of B12 deficiency. Early vitamin B12 and folate deprivation during gestation and lactation of a 'dam-progeny' rat model developed in our laboratory is associated with long-lasting disabilities of behavior and memory capacities, with persisting hallmarks related to increased apoptosis, impaired neurogenesis and altered plasticity. We found also an epigenomic deregulation of energy metabolism and fatty acids beta-oxidation in myocardium and liver, through imbalanced methylation/acetylation of PGC-1alpha and decreased expression of SIRT1. These nutrigenomic effects display similarities with the molecular mechanisms of fetal programming. Beside deficiency, B12 loading increases the expression of MTR through internal ribosome entry sites (IRES) and down-regulates MDR-1 gene expression. In conclusion, vitamin B12 influences cell proliferation, differentiation and apoptosis in brain. Vitamin B12 and folate combined deficiency impairs fatty acid oxidation and energy metabolism in liver and heart through epigenomic mechanisms related to imbalanced acetylation/methylation. Some but not all of these effects reflect the upstream role of vitamin B12 in SAM synthesis.

Cobalamin and normal prions: a new horizon for cobalamin neurotrophism

It is known that cobalamin (Cbl) deficiency damages myelin by increasing tumor necrosis factor (TNF)-α and decreasing epidermal growth factor (EGF) levels in rat central nervous system (CNS), and affects the peripheral nervous system (PNS) morphologically and functionally. It is also known that some polyneuropathies not due to Cbl deficiency are connected with increased TNF-α levels, and that various cytokines (including TNF-α) and growth factors regulate the in vitro synthesis of normal prions (PrP(C)s). Given that there is extensive evidence that PrP(C)s play a key role in the maintenance of CNS and PNS myelin, we investigated whether the PrP(C) octapeptide repeat (OR) region is involved in the pathogenesis of rat Cbl-deficient (Cbl-D) polyneuropathy. After intracerebroventricularly administering antibodies (Abs) against the OR region (OR-Abs) to Cbl-D rats to prevent myelin damage and maximum nerve conduction velocity (MNCV) abnormalities, and PrP(C)s to otherwise normal rats to reproduce PNS Cbl-D-like lesions, we measured PrP(C) levels and MNCV of the sciatic and tibial nerves. PrP(C) and TNF-α levels were increased in sciatic and tibial nerves of Cbl-D and saline-treated rats, and the OR-Abs normalized the myelin ultrastructure, TNF-α levels, and MNCV values of the sciatic and tibial nerves of Cbl-D rats. The same peripheral nerves of the otherwise normal PrP(C)-treated rats showed typical Cbl-D myelin lesions, significantly increased TNF-α levels, and significantly decreased MNCV values. These findings demonstrate that Cbl deficiency induces excess PrP(C)s and thereby excess OR regions, which seem to be responsible for the PNS myelin damage, as has recently been found in the case of CNS myelin damage [66]. Furthermore, excess TNF-α is also involved in the pathogenesis of Cbl-D polyneuropathy. In conclusion, we have extended the list of prion diseases by adding one caused by excess PrP(C)s and the polyneuropathies related to excess TNF-α.

Optimizing NTS-polyplex as a tool for gene transfer to cultured dopamine neurons

The study of signal transduction in dopamine (DA)-containing neurons as well as the development of new therapeutic approaches for Parkinson's disease requires the selective expression of transgenes in such neurons. Here we describe optimization of the use of the NTS-polyplex, a gene carrier system taking advantage of neurotensin receptor internalization, to transfect mouse DA neurons in primary culture. The plasmids DsRed2 (4.7 kbp) and VGLUT2-Venus (11 kbp) were used to compare the ability of this carrier system to transfect plasmids of different sizes. We examined the impact of age of the neurons (1, 3, 5 and 8 days after seeding), of culture media used during the transfection (Neurobasal with B27 vs. conditioned medium) and of three molar ratios of plasmid DNA to carrier. While the NTS-polyplex successfully transfected both plasmids in a control N1E-115 cell line, only the pDsRed2 plasmid could be transfected in primary cultured DA neurons. We achieved 20% transfection efficiency of pDsRed2 in DA neurons, with 80% cell viability. The transfection was demonstrated pharmacologically to be dependent on activation of neurotensin receptors and to be selective for DA neurons. The presence of conditioned medium for transfection was found to be required to insure cell viability. Highest transfection efficiency was achieved in the most mature neurons. In contrast, transfection with the VGLUT2-Venus plasmid produced cell damage, most likely due to the high molar ratios required, as evidenced by a 15% cell viability of DA neurons at the three molar ratios tested (1:36, 1:39 and 1:42). We conclude that, when used at molar ratios lower than 1:33, the NTS-polyplex can selectively transfect mature cultured DA neurons with only low levels of toxicity. Our results provide evidence that the NTS-polyplex has good potential for targeted gene delivery in cultured DA neurons, an in vitro system of great use for the screening of new therapeutic approaches for Parkinson's disease.

Integral Proteins in Plant Oil Bodies

Hydrophobic storage neutral lipids are stably preserved in specialized organelles termed oil bodies in the aqueous cytosolic compartment of plant cells via encapsulation with surfactant molecules including phospholipids and integral proteins. To date, three classes of integral proteins, termed oleosin, caleosin, and steroleosin, have been identified in oil bodies of angiosperm seeds. Proposed structures, targeting traffic routes, and biological functions of these three integral oil-body proteins were summarized and discussed. In the viewpoint of evolution, isoforms of oleosin and caleosin are found in oil bodies of pollens as well as those of more primitive species; moreover, caleosin- and steroleosin-like proteins are also present in other subcellular locations besides oil bodies. Technically, artificial oil bodies of structural stability similar to native ones were successfully constituted and seemed to serve as a useful tool for both basic research studies and biotechnological applications.

NTS-Polyplex: a potential nanocarrier for neurotrophic therapy of Parkinson's disease

Nanomedicine has focused on targeted neurotrophic gene delivery to the brain as a strategy to stop and reverse neurodegeneration in Parkinson's disease. Because of improved transfection ability, synthetic nanocarriers have become candidates for neurotrophic therapy. Neurotensin (NTS)-polyplex is a "Trojan horse" synthetic nanocarrier system that enters dopaminergic neurons through NTS receptor internalization to deliver a genetic cargo. The success of preclinical studies with different neurotrophic genes supports the possibility of using NTS-polyplex in nanomedicine. In this review, we describe the mechanism of NTS-polyplex transfection. We discuss the concept that an effective neurotrophic therapy requires a simultaneous effect on the axon terminals and soma of the remaining dopaminergic neurons. We also discuss the future of this strategy for the treatment of Parkinson's disease.

FROM THE CLINICAL EDITOR

This review paper focuses on nanomedicine-based treatment of Parkinson's disease, a neurodegenerative condition with existing symptomatic but no curative treatment. Neurotensin-polyplex is a synthetic nanocarrier system that enables delivery of genetic cargo to dopaminergic neurons via NTS receptor internalization.

Luminal expression of cubilin is impaired in Imerslund-Grasbeck syndrome with compound AMN mutations in intron 3 and exon 7

Juvenile megaloblastic anaemia 1 (OMIM # 261100) is a rare autosomic disorder characterized by selective cobalamin mal-absorption and inconstant proteinuria produced by mutations in either CUBN or AMN genes. Amnionless, the gene product of AMN, is a transmembrane protein that binds tightly to the N-terminal end of cubilin, the gene product of CUBN. Cubilin binds to intrinsic factor-cobalamin complex and is expressed in the distal intestine and the proximal renal tubule. We report a compound AMN heterozygosity with c.742C>T, p.Gln248X and c.208-2A>G mutations in 2 siblings that led to premature termination codon in exon 7 and exon 6, respectively. It produced a dramatic decrease in receptor activity in urine, despite absence of CUBN mutation and normal affinity of the receptor for intrinsic factor binding. Heterozygous carriers for c.742T and c.208-2G had no pathological signs. These results indicate that amnionless is essential for the correct luminal expression of cubilin in humans.