Multiple sclerosis and mitochondrial gene variations: a review

Efficient Neural Differentiation of Mouse Embryonic Stem Cells by Mastic Gum

Purpose: Promoting neurogenesis is a promising strategy to treat neurodegenerative disorders. In the present study, we aimed to evaluate the effect of mastic gum resin from the Pistacia lentiscus var. Chia (Anacardiaceae family) in proliferation capacity and differentiation of embryonic mesenchymal stem cells into a neural lineage. Methods: For this purpose, mastic gum was applied as a neural inducer for stem cell differentiation into the neuronal lineage. Following treatment of embryonic stem cells (ESCs) with mastic gum, verification differentiation of the ESCs into the neuronal lineage, gene expression analysis, and immunocytochemistry staining approach were performed. Results: Gene expression analysis demonstrated that mastic gum increased the expression level of neuron markers in the ESCs-derived neuron-like cells. Moreover, our immunocytochemistry staining results of two important neural stem cell markers, including Nestin and microtubule-associated protein-2 (Map2) expression confirmed that mastic gum has the potential to promote neuronal differentiation in ESCs. Conclusion: In summary, the use of mastic gum to stimulate the differentiation of ESCs into a neural lineage can be considered as a good candidate in stem cell therapy.

Neuroimaging in Leber Hereditary Optic Neuropathy: State-of-the-art and future prospects

Leber Hereditary Optic Neuropathy (LHON) is an inherited mitochondrial retinal disease that causes the degeneration of retinal ganglion cells and leads to drastic loss of visual function. In the last decades, there has been a growing interest in using Magnetic Resonance Imaging (MRI) to better understand mechanisms of LHON beyond the retina. This is partially due to the emergence of gene-therapies for retinal diseases, and the accompanying expanded need for reliably quantifying and monitoring visual processing and treatment efficiency in patient populations. This paper aims to draw a current picture of key findings in this field so far, the challenges of using neuroimaging methods in patients with LHON, and important open questions that MRI can help address about LHON disease mechanisms and prognoses, including how downstream visual brain regions are affected by the disease and treatment and why, and how scope for neural plasticity in these pathways may limit or facilitate recovery.

The potential use of microRNAs as a therapeutic strategy for SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To date, there is no effective therapeutic approach for treating SARS-CoV-2 infections. MicroRNAs (miRNAs) have been recognized to target the viral genome directly or indirectly, thereby inhibiting viral replication. Several studies have demonstrated that host miRNAs target different sites in SARS-CoV-2 RNA and constrain the production of essential viral proteins. Furthermore, miRNAs have lower toxicity, are more immunogenic, and are more diverse than protein-based and even plasmid-DNA-based therapeutic agents. In this review, we emphasize the role of miRNAs in viral infection and their potential use as therapeutic agents against COVID-19 disease. The potential of novel miRNA delivery strategies, especially EDV™ nanocells, for targeting lung tissue for treatment of SARS-CoV-2 infection is also discussed.

Age and sex adjusted prevalence and annual incidence of multiple sclerosis in East-Azerbaijan, Iran

BACKGROUND

Incidence and prevalence of multiple sclerosis (MS) is postulated to be rising in recent decades. Therefore, updating and completing the information of patients is essential, especially in high population areas. East-Azerbaijan is the largest and most populous province in the northwest of Iran. This study aimed to determine the prevalence and annual incidence of MS from 2008 to 2017 in East-Azerbaijan.

METHODS

We evaluated the data of all patients who had registered at the MS center in the university hospital. The data include nearly all MS patients in the East-Azerbaijan region, because it is the only referral site in the area. All of the reported rates were calculated in 100,000 of the total population.

RESULTS

By the end of 2017, the number of MS patients was 2995 (residing in the, with 769 (25.67%) men and 2226 (74.32%) women. The prevalence rate was 75.72/100,000 (95 % CI: 73.06-78.48), 38.2 in men (95% CI: 35.5-41.0), and 114.61 for women (95% CI: 109.9-119.4), with a female to male (F/M) ratio of 3:1. The mean annual incidence rate was 7.63/100,000 (95% CI: 5.6-9.3), and this rate was higher in women than men. During the nine years, the incidence rate increased. The patients' mean age was 32.33 ± 8.92, with a peak prevalence in 25-29 years for both genders. In this study, 13.9% of patients had a positive MS family history.

CONCLUSIONS

This study showed a high prevalence of MS in the region. There is a significant increase in the incidence of MS during the nine years in East-Azerbaijan. The increment of incidence was more prominent in women. Also, considering the increasing incidence rate, it is concluded that the risk of MS is increasing in this region.

Clinical Features of Late-Onset Multiple Sclerosis: a Systematic Review and Meta-analysis

BACKGROUND

Multiple sclerosis (MS) commonly affects young adults at the ages 20 to 40 years old, but it can onset at each age. Late-onset multiple sclerosis (LOMS) is defined as symptoms initiating after the age of 50. Misdiagnosis and a remarkable gap in diagnosis of LOMS is a challenge of the elderly population so in this article we described the proportion of LOMS and the clinical features and phenotype of the disease in this age group.

METHODS

After registration of the study protocol, an electronic search was performed in 3 databases and for full coverage of the published studies, we also checked the references of each related article. Two independent researchers screened the records in title/abstract and full-text stages and extracted the data using a data extraction table. The risk of bias was assessed using Joanna Briggs Institute checklist and meta-analysis was conducted by CMA 2. Only the studies with 50 years old cut-off and using McDonald or Poser diagnostic criteria were included in the meta-analysis.

RESULTS

After removing duplicated studies, out of 733 results of electronic and hand searching, 31 studies met our inclusion criteria for the systematic review, and 11 of them were included in the quantitative synthesis. With different cut-offs and diagnostic methods 1.1% to 21.3% proportion of LOMS, has been reported in the studies. Meta-analysis reached a 5.01% (95% CI: 3.78% to 6.57%), proportion of LOMS in total MS cases. The female cases were more than males (range between 57.7% to 70.2%) and 64.46% (95% CI: 61.94% to 66.91%) proportion of females has been found in this study. 65.00% (95% CI: 44.71% to 81.02%) proportion of spinal cord involvements and 49.80% (95% CI: 39.28% to 60.24%) proportion of relapsing-remitting multiple sclerosis (RRMS) was also observed in LOMS cases. In 4 of included studies, the progressive form was the predominant phenotype. The most prevalent first disease presentation of LOMS was motor dysfunction (ranges between 100% to 35.4%) followed by sensory problems (ranges between 94% to 5%), visual symptoms (ranges between 22.9% to 5%), and brainstem dysfunction (ranges between 25% to 12.3%). The proportion of positive oligoclonal band (OCB), was varied from 46% to 98% in different studies and positive immunoglobulin G (IgG) index also was seen in 45.04% and 66% of the patients. 2.2% - 12.5% of the LOMS cases had a positive family history.

CONCLUSION

In about 5% of cases, MS can be diagnosed at ages above 50 years old. There is an increasing concern of a more progressive form of MS in LOMS cases. Unlike the adult-onset MS, the first presentation of LOMS is usually motor dysfunction. Understanding the proportion and clinical features of LOMS will help clinicians with the diagnosis of MS in this age group and prevention of wrong management plans and complications in these patients. Although the proportion of females is still more than males in LOMS cases; but there is a trend to increase in male cases with aging.

Omics Integration Analysis Unravel the Landscape of Driving Mechanisms of Colorectal Cancer

Colorectal cancer (CRC) is one of the most malignant cancers and results in a substantial rate of morbidity and mortality. Diagnosis of this malignancy in early stages increases the chance of effective treatment. High-throughput data analyses reveal omics signatures and also provide the possibility of developing computational models for early detection of this disease. Such models would be able to use as complementary tools for early detection of different types of cancers including CRC. In this study, using gene expression data, the Flux balance analysis (FBA) applied to decode metabolic fluxes in cancer and normal cells. Moreover, transcriptome and genome analyses revealed driver agents of CRC in a biological network scheme. By applying comprehensive publicly available data from TCGA, different aspect of CRC regulome including the regulatory effect of gene expression, methylation, microRNA, copy number aberration and point mutation profile over protein levels investigated and the results provide a regulatory picture underlying CRC. Compiling omics profiles indicated snapshots of changes in different omics levels and flux rate of CRC. In conclusion, considering obtained CRC signatures and their role in biological operating systems of cells, the results suggest reliable driver regulatory modules that could potentially serve as biomarkers and therapeutic targets and furthermore expand our understanding of driving mechanisms of this disease.
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The Dichotomous Role of Inflammation in the CNS: A Mitochondrial Point of View

Innate immune response is one of our primary defenses against pathogens infection, although, if dysregulated, it represents the leading cause of chronic tissue inflammation. This dualism is even more present in the central nervous system, where neuroinflammation is both important for the activation of reparatory mechanisms and, at the same time, leads to the release of detrimental factors that induce neurons loss. Key players in modulating the neuroinflammatory response are mitochondria. Indeed, they are responsible for a variety of cell mechanisms that control tissue homeostasis, such as autophagy, apoptosis, energy production, and also inflammation. Accordingly, it is widely recognized that mitochondria exert a pivotal role in the development of neurodegenerative diseases, such as multiple sclerosis, Parkinson's and Alzheimer's diseases, as well as in acute brain damage, such in ischemic stroke and epileptic seizures. In this review, we will describe the role of mitochondria molecular signaling in regulating neuroinflammation in central nervous system (CNS) diseases, by focusing on pattern recognition receptors (PRRs) signaling, reactive oxygen species (ROS) production, and mitophagy, giving a hint on the possible therapeutic approaches targeting mitochondrial pathways involved in inflammation.

Mitochondrial DNA Copy Number in Peripheral Blood as a Potential Non-invasive Biomarker for Multiple Sclerosis

The impaired mitochondrial function has been implicated in the pathogenicity of multiple sclerosis (MS), a chronic inflammatory, demyelinating, and neurodegenerative disease of the CNS. Circulating mtDNA copy number in body fluids has been proposed as an indicator for several neurodegenerative diseases, and the altered cerebrospinal fluid mtDNA has been shown as a promising marker for MS. The aim of this study was to determine changes and biomarker potential of circulating mtDNA in peripheral blood in MS. The mtDNA copy number was quantified by real-time PCR in blood samples from 60 patients with relapsing-remitting MS (RRMS) and 64 healthy controls. The RRMS patients had significantly lower circulating mtDNA copy number compared to controls. Subgroup analysis with stratification of RRMS patients based on disease duration under or over 10 years revealed that the mtDNA copy number was significantly lower in the group with longer disease duration. A negative correlation was observed between mtDNA copy number and disease duration. The ROC curve analysis indicated a significant ability of mtDNA copy number to separate RRMS patients from controls with an AUC of 0.859. This is the first study to measure peripheral blood mtDNA copy number in MS patients. Current data suggest that the reduction in peripheral blood mtDNA copy number may be an early event in MS and correlate with the disease progression. The findings of this study indicate that circulating blood-based mtDNA copy number may be a potential non-invasive candidate biomarker for mitochondria-mediated neurodegeneration and MS. This can put forward the clinical applicability over other invasive markers.

Association of MS4A6A, CD33, and TREM2 gene polymorphisms with the late-onset Alzheimer's disease

Introduction: Alzheimer’s disease (AD), which is a progressive neurodegenerative disorder, causes structural and functional brain disruption. MS4A6A, TREM2, and CD33 gene polymorphisms loci have been found to be associated with the pathobiology of late-onset AD (LOAD). In the present study, we tested the hypothesis of association of LOAD with rs983392, rs75932628, and rs3865444 polymorphisms in MS4A6A, TREM2, CD33 genes, respectively.

Methods: In the present study, 113 LOAD patients and 100 healthy unrelated age- and gender-matched controls were selected. DNA was extracted from blood samples by the salting-out method and the genotyping was performed by RFLP-PCR. Electrophoresis was carried out on agarose gel. Sequencing was thereafter utilized for the confirmation of the results.

Results: Only CD33 rs3865444 polymorphism revealed a significant difference in the genotypic frequencies of GG (P = 0.001) and GT (P = 0.001), and allelic frequencies of G (P = 0.033) and T (P = 0.03) between LOAD patients and controls.

Conclusion: The evidence from the present study suggests that T allele of CD33 rs3865444 polymorphism is associated with LOAD in the studied Iranian population.

Cell-free mitochondrial DNA in progressive multiple sclerosis

Recent studies have linked cell-free mitochondrial DNA (ccf-mtDNA) to neurodegeneration in both Alzheimer's and Parkinson's disease, raising the possibility that the same phenomenon could be seen in other diseases which manifest a neurodegenerative component. Here, we assessed the role of circulating cell-free mitochondrial DNA (ccf-mtDNA) in end-stage progressive multiple sclerosis (PMS), where neurodegeneration is evident, contrasting both ventricular cerebral spinal fluid ccf-mtDNA abundance and integrity between PMS cases and controls, and correlating ccf-mtDNA levels to known protein markers of neurodegeneration and PMS. Our data indicate that reduced ccf-mtDNA is a component of PMS, concluding that it may indeed be a hallmark of broader neurodegeneration.

In-vitro Transcribed mRNA Delivery Using PLGA/PEI Nanoparticles into Human Monocyte-derived Dendritic Cells

Induction of protein synthesis by the external delivery of in-vitro transcription-messenger RNA (IVT-mRNA) has been a useful approach in the realm of cell biology, disease treatment, ‎reprogramming of cells, and vaccine design. Therefore, the development of new formulations for ‎protection of mRNA against nucleases is required to maintain its activity in-vivo. It was the aim of the present study to ‎investigate the uptake, toxicity, transfection efficiency as well as phenotypic consequences of ‎a nanoparticle (NP) in cell culture. NP consists of poly D, L-lactide-co-glycolide (PLGA) and polyethyleneimine (PEI) ‎for delivery of in-vitro transcription-messenger RNA (IVT- mRNA) encoded green fluorescent protein (GFP) in human monocyte-derived ‎dendritic cells (moDCs). Nanoparticles that were synthesized and encapsulated with synthetic GFP mRNA, exhibited size distribution in this formulation, with mean particle sizes ranging between 415 and 615 nm. Zeta potential was positive (above 12-13 mV) and the encapsulation efficiency exceeded 73.5%. Our results demonstrated that PLGA/PEI NPs encapsulation of GFP mRNA had ‎no toxic effect on immature monocyte-derived ‎dendritic cells and was capable of delivering of IVT-mRNA into moDCs and was highly effective. The expression of GFP protein 48 h after transfection was confirmed by flow cytometry, microscopic examination and western blotting assay. This NP can make a way to target moDCs to express a variety of antigens by IVT- mRNA. The ‎present study introduced the PLGA/PEI NP, which provided effective delivery of ‎IVT-mRNA that encodes the GFP protein.

Mitochondrial DNA damage and reactive oxygen species in neurodegenerative disease

Mitochondria are essential organelles within the cell where most ATP is produced through oxidative phosphorylation (OXPHOS). A subset of the genes needed for this process are encoded by the mitochondrial DNA (mtDNA). One consequence of OXPHOS is the production of mitochondrial reactive oxygen species (ROS), whose role in mediating cellular damage, particularly in damaging mtDNA during ageing, has been controversial. There are subsets of neurons that appear to be more sensitive to ROS-induced damage, and mitochondrial dysfunction has been associated with several neurodegenerative disorders. In this review, we will discuss the current knowledge in the field of mtDNA and neurodegeneration, the debate about ROS as a pathological or beneficial contributor to neuronal function, bona fide mtDNA diseases, and insights from mouse models of mtDNA defects affecting the central nervous system.

Mitochondrial DNA Double-Strand Breaks in Oligodendrocytes Cause Demyelination, Axonal Injury, and CNS Inflammation

Mitochondrial dysfunction has been implicated in the pathophysiology of neurodegenerative disorders, including multiple sclerosis (MS). To date, the investigation of mitochondrial dysfunction in MS has focused exclusively on neurons, with no studies exploring whether dysregulation of mitochondrial bioenergetics and/or genetics in oligodendrocytes might be associated with the etiopathogenesis of MS and other demyelinating syndromes. To address this question, we established a mouse model where mitochondrial DNA (mtDNA) double-strand breaks (DSBs) were specifically induced in myelinating oligodendrocytes (PLP:mtPstI mice) by expressing a mitochondrial-targeted endonuclease, mtPstI, starting at 3 weeks of age. In both female and male mice, DSBs of oligodendroglial mtDNA caused impairment of locomotor function, chronic demyelination, glial activation, and axonal degeneration, which became more severe with time of induction. In addition, after short transient induction of mtDNA DSBs, PLP:mtPstI mice showed an exacerbated response to experimental autoimmune encephalomyelitis. Together, our data demonstrate that mtDNA damage can cause primary oligodendropathy, which in turn triggers demyelination, proving PLP:mtPstI mice to be a useful tool to study the pathological consequences of mitochondrial dysfunction in oligodendrocytes. In addition, the demyelination and axonal loss displayed by PLP:mtPstI mice recapitulate some of the key features of chronic demyelinating syndromes, including progressive MS forms, which are not accurately reproduced in the models currently available. For this reason, the PLP:mtPstI mouse represents a unique and much needed platform for testing remyelinating therapies.SIGNIFICANCE STATEMENT In this study, we show that oligodendrocyte-specific mitochondrial DNA double-strand breaks in PLP:mtPstI mice cause oligodendrocyte death and demyelination associated with axonal damage and glial activation. Hence, PLP:mtPstI mice represent a unique tool to study the pathological consequences of mitochondrial dysfunction in oligodendrocytes, as well as an ideal platform to test remyelinating and neuroprotective agents.

The clinical and genetic characteristics in children with mitochondrial disease in China

Mitochondrial disease was a clinically and genetically heterogeneous group of diseases, thus the diagnosis was very difficult to clinicians. Our objective was to analyze clinical and genetic characteristics of children with mitochondrial disease in China. We tested 141 candidate patients who have been suspected of mitochondrial disorders by using targeted next-generation sequencing (NGS), and summarized the clinical and genetic data of gene confirmed cases from Neurology Department, Beijing Children's Hospital, Capital Medical University from October 2012 to January 2015. In our study, 40 cases of gene confirmed mitochondrial disease including eight kinds of mitochondrial disease, among which Leigh syndrome was identified to be the most common type, followed by mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS). The age-of-onset varies among mitochondrial disease, but early onset was common. All of 40 cases were gene confirmed, among which 25 cases (62.5%) with mitochondrial DNA (mtDNA) mutation, and 15 cases (37.5%) with nuclear DNA (nDNA) mutation. M.3243A>G (n=7) accounts for a large proportion of mtDNA mutation. The nDNA mutations include SURF1 (n=7), PDHA1 (n=2), and NDUFV1, NDUFAF6, SUCLA2, SUCLG1, RRM2B, and C12orf65, respectively.

Pandora's Box: mitochondrial defects in ischaemic heart disease and stroke

Ischaemic heart disease and stroke are vascular events with serious health consequences worldwide. Recent genetic and epigenetic techniques have revealed many genetic determinants of these vascular events and simplified the approaches to research focused on ischaemic heart disease and stroke. The pathogenetic mechanisms of ischaemic heart disease and stroke are complex, with mitochondrial involvement (partially or entirely) recently gaining substantial support. Not only can mitochondrial reactive oxygen species give rise to ischaemic heart disease and stroke by production of oxidised low-density lipoprotein and induction of apoptosis, but the impact on pericytes contributes directly to the pathogenesis. Over the past two decades, publications implicate the causative role of nuclear genes in the development of ischaemic heart disease and stroke, in contrast to the potential role of mitochondrial DNA (mtDNA) in the pathophysiology of the disorders, which is much less understood, although recent studies do demonstrate that the involvement of mitochondria and mtDNA in the development of ischaemic heart disease and stroke is likely to be larger than originally thought, with the novel discovery of links among mitochondria, mtDNA and vascular events. Here we explore the molecular events and mtDNA alterations in relation to the role of mitochondria in ischaemic heart disease and stroke.

MtDNA T4216C variation in multiple sclerosis: a systematic review and meta-analysis

MtDNA T4216C variation has frequently been investigated in Multiple Sclerosis (MS) patients; nonetheless, controversy has existed about the evidence of association of this variation with susceptibility to MS. The present systematic review and meta-analysis converge the results of the preceding publications, pertaining to association of mtDNA T4216C variation with susceptibility to MS, into a common conclusion. A computerized literature search in English was carried out to retrieve relevant publications from which required data were extracted. Using a fixed effect model, pooled odds ratio (OR), 95 % confidence interval (95 % CI), and P value were calculated for association of mtDNA T4216C variation with susceptibility to MS. The pooled results showed that there was a significant association between mtDNA T4216C variation and MS (OR = 1.38, 95 % CI = 1.13-1.67, P = 0.001). The present systematic review and meta-analysis suggest that mtDNA T4216C variation is a contributory factor in susceptibility to MS.

Mitochondria in Multiple Sclerosis: Molecular Mechanisms of Pathogenesis

Mitochondria, the organelles that function as the powerhouse of the cell, have been increasingly linked to the pathogenesis of many neurological disorders, including multiple sclerosis (MS). MS is a chronic inflammatory demyelinating disease of the central nervous system (CNS) and a leading cause of neurological disability in young adults in the western world. Its etiology remains unknown, and while the inflammatory component of MS has been heavily investigated and targeted for therapeutic intervention, the failure of remyelination and the process of axonal degeneration are still poorly understood. Recent studies suggest a role of mitochondrial dysfunction in the neurodegenerative aspects of MS. This review is focused on mitochondrial functions under physiological conditions and the consequences of mitochondrial alterations in various CNS disorders. Moreover, we summarize recent findings linking mitochondrial dysfunction to MS and discuss novel therapeutic strategies targeting mitochondria-related pathways as well as emerging experimental approaches for modeling mitochondrial disease.

Mitochondrial DNA sequence variation in multiple sclerosis

OBJECTIVE

To assess the influence of common mitochondrial DNA (mtDNA) sequence variation on multiple sclerosis (MS) risk in cases and controls part of an international consortium.

METHODS

We analyzed 115 high-quality mtDNA variants and common haplogroups from a previously published genome-wide association study among 7,391 cases from the International Multiple Sclerosis Genetics Consortium and 14,568 controls from the Wellcome Trust Case Control Consortium 2 project from 7 countries. Significant single nucleotide polymorphism and haplogroup associations were replicated in 3,720 cases and 879 controls from the University of California, San Francisco.

RESULTS

An elevated risk of MS was detected among haplogroup JT carriers from 7 pooled clinic sites (odds ratio [OR] = 1.15, 95% confidence interval [CI] = 1.07-1.24, p = 0.0002) included in the discovery study. The increased risk of MS was observed for both haplogroup T (OR = 1.17, 95% CI = 1.06-1.29, p = 0.002) and haplogroup J carriers (OR = 1.11, 95% CI = 1.01-1.22, p = 0.03). These haplogroup associations with MS were not replicated in the independent sample set. An elevated risk of primary progressive (PP) MS was detected for haplogroup J participants from 3 European discovery populations (OR = 1.49, 95% CI = 1.10-2.01, p = 0.009). This elevated risk was borderline significant in the US replication population (OR = 1.43, 95% CI = 0.99-2.08, p = 0.058) and remained significant in pooled analysis of discovery and replication studies (OR = 1.43, 95% CI = 1.14-1.81, p = 0.002). No common individual mtDNA variants were associated with MS risk.

CONCLUSIONS

Identification and validation of mitochondrial genetic variants associated with MS and PPMS may lead to new targets for treatment and diagnostic tests for identifying potential responders to interventions that target mitochondria.

Mitochondrial genome changes and neurodegenerative diseases

Mitochondria are essential organelles within the cell where most of the energy production occurs by the oxidative phosphorylation system (OXPHOS). Critical components of the OXPHOS are encoded by the mitochondrial DNA (mtDNA) and therefore, mutations involving this genome can be deleterious to the cell. Post-mitotic tissues, such as muscle and brain, are most sensitive to mtDNA changes, due to their high energy requirements and non-proliferative status. It has been proposed that mtDNA biological features and location make it vulnerable to mutations, which accumulate over time. However, although the role of mtDNA damage has been conclusively connected to neuronal impairment in mitochondrial diseases, its role in age-related neurodegenerative diseases remains speculative. Here we review the pathophysiology of mtDNA mutations leading to neurodegeneration and discuss the insights obtained by studying mouse models of mtDNA dysfunction.