A Multisystem Mitochondrial Disease Caused by a Novel MT-TL1 mtDNA Variant: A Case Report.

BACKGROUND: Mitochondrial tRNA (MTT) genes are hotspot for mitochondrial DNA mutation and are responsible of half mitochondrial disease. MTT mutations are associated with a broad spectrum of phenotype often with complex multisystem involvement and complex genotype-phenotype correlations. MT-TL1 mutations, among which the m.3243A>G mutation is the most frequent, are associated with myopathy, maternal inherited diabetes and deafness, MELAS, cardiomyopathy, and focal segmental glomerulosclerosis. CASE STUDY: Here we report the case of an Italian 49-years old female presenting with encephalomyopathy, chronic proteinuric kidney disease and a new heteroplasmic m.3274_3275delAC MT-TL1 gene mutation. CONCLUSIONS: Our case demonstrates a systemic mitochondrial disease caused by the heteroplasmic m.3274_3275delAC MT-TL1 gene mutation, not yet described in the literature. A mitochondrial disease should be suspected in case of complex multisystem phenotypes, including steroid-resistant nephrotic syndrome with multisystemic involvement.

Biological determinants of blood-based cytokines in the Alzheimer's disease clinical continuum.

Converging translational and clinical research strongly indicates that altered immune and inflammatory homeostasis (neuroinflammation) plays a critical pathophysiological role in Alzheimer's disease (AD), across the clinical continuum. A dualistic role of neuroinflammation may account for a complex biological phenomenon, representing a potential pharmacological target. Emerging blood-based pathophysiological biomarkers, such as cytokines (Cyt) and interleukins (ILs), have been studied as indicators of neuroinflammation in AD. However, inconsistent results have been reported probably due to a lack of standardization of assays with methodological and analytical differences. We used machine-learning and a cross-validation-based statical workflow to explore and analyze the potential impact of key biological factors, such as age, sex, and apolipoprotein-E (APOE) genotype (the major genetic risk factor for late-onset AD) on Cyt. A set of Cyt was selected based on previous literature, and we investigated any potential association in a pooled cohort of cognitively healthy, mild cognitive impairment (MCI), and AD-like dementia patients. We also performed explorative analyses to extrapolate preliminary clinical insights. We found a robust sex effect on IL12 and an APOE-related difference in IL10, with the latter being also related to the presence of advanced cognitive decline. IL1ß was the variable most significantly associated with MCI-to-dementia conversion over a 2.5 year-clinical follow-up. Although preliminary, our data support further clinical research to understand whether plasma Cyt may represent reliable and noninvasive tools serving the investigation of neuroimmune and inflammatory dynamics in AD and to foster biomarker-guided pathway-based therapeutic approaches, within the precision medicine development framework.

Acute encephalopathy of the temporal lobes leading to m.3243A>G. When MELAS is not always MELAS.

MELAS syndrome (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes) is a rare genetic condition whose differential diagnosis is often posed with juvenile stroke, but more rarely even with inflammatory/infectious encephalitis, causing diagnostic challenges. Here we report the case of a young man harbouring the m.3243A>G MELAS mutation presenting an acute onset mimicking the clinical and neuroimaging features of infective encephalitis.

A multi-parametric protocol to study exercise intolerance in McArdle's disease.

McArdle's disease is the most common metabolic myopathy of muscle carbohydrate metabolism, due to deficiency of myophosphorylase and alteration of glycogen breakdown in muscle. The clinical manifestations usually begin in young adulthood, with exercise intolerance, exercise-induced muscle cramps, pain and recurrent episodes of myoglobinuria. Many patients experience the second wind phenomenon, characterized by an improved tolerance for aerobic exercise approximately after eight minutes of motor activity, secondary to the increased availability of blood glucose and free fatty acids associated to an enhanced glucose uptake by muscle cells. In this study, we aimed to test a multi-parametric protocol in order to detect the impairment of muscular metabolism and motor performance in patients with McArdle's disease. We enrolled 5 patients and 5 age-matched healthy subjects, that were evaluated by: (01) monitoring of physical activity with an electronic armband; (02) testing of cardiopulmonary, metabolic and respiratory responses to exercise with a cardiopulmonary exercise test and analyzing muscle fatigue during exercise test by surface electromyography (04) evaluating blood lactate and oxidative stress biomarkers at rest and during exercise. The patients were tested at baseline and after three days of carbohydrate-rich diet integrated with tricarboxylic acid cycle intermediate and creatine. The multiparametric protocol proved to be useful to detect the oxidative capacity impairment and the second wind phenomenon of patients. We did not observe any significant differences of muscle metabolic response during the exercise test after three days of carbohydrate-rich diet.

Plasmatic oxidative stress biomarkers in multiple sclerosis: relation with clinical and demographic characteristics.

OBJECTIVES: In multiple sclerosis (MS) oxidative injury likely plays a major role in disease progression and in damaging tissue in the central nervous system (CNS), although with different mechanisms in the initial and the progressive disease stages. We compared the biomarker levels of plasmatic oxidative stress in patients with relapsing remitting (RR) and secondary progressive (SP) MS in order to correlate biomarker levels with demographic and clinical variables. DESIGN AND METHODS: We included 60 consecutive MS patients (30 with RR-MS and 30 with SP-MS) and a control group of 81 healthy subjects. All patients underwent clinical assessment, including disability, fatigue and sleepiness evaluations and blood sample collection for advanced oxidation protein products (AOPPs), plasmatic ferric reducing ability (FRA) and thiol group dosage. RESULTS: Plasmatic AOPPs were significantly higher while FRA and thiol levels were lower in MS patients compared to healthy controls. No difference was found in oxidative stress biomarker values in RR and SP-MS patients. However, in patients with "active" disease, FRA levels and thiol groups (expression of antioxidant power) were significantly lower. No significant correlation was found with demographic and clinical characteristics of patients, including age, disease duration, disability, fatigue, and daytime sleepiness. CONCLUSIONS: Plasmatic AOPPs, FRA and thiol groups show oxidative damage and reduced antioxidant capability in MS. Although their power to characterize different courses of the disease is limited, they seem to be related to disease activity.

Novel MTCYB mutation in a young patient with recurrent stroke-like episodes and status epilepticus.

The acronym "MELAS" (mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes) denotes patients with histological, biochemical and/or molecular evidence of mitochondrial disease who experience stroke-like episodes. Here we report on a girl with repeated stroke-like episodes and status epilepticus, who was diagnosed with MELAS due to a novel mitochondrial cytochrome b gene (MTCYB) mutation (m.15092G>A, which predicts p.G116S). Western blotting and in silico analyses suggested that this mutation could affect the stability of complex III. Cytochrome b is the only mtDNA-encoded subunit of respiratory chain complex III. Mutations in MTCYB have been associated with isolated mitochondrial myopathy and exercise intolerance, and rarely with multisystem and/or central nervous system involvement. If the m.3243A>G and other common MELAS mutations are absent in several tissues, MTCYB should be sequenced from muscle in patients with stroke-like episodes, especially if muscle histology does not support a mitochondrial myopathy and lactic acidosis is absent.

Hereditary spastic paraparesis in adults. A clinical and genetic perspective from Tuscany.

OBJECTIVE: Hereditary spastic paraparesis or paraplegias (HSPs) are a group of neurogenetic conditions with prominent involvement of the pyramidal tracts. Aim of this study is the clinical and molecular characterization of a cohort of patients with HSP. Moreover, we aim to study the minimum prevalence of HSP in our area and to propose a schematic diagnostic approach to HSP patients based on the available data from the literature. METHODS: Retrospective/perspective study on the subjects with clinical signs and symptoms indicative of pure or complicated HSP, in whom other possible diagnosis were excluded by appropriate neuroradiological, neurophysiologic and laboratory studies, who have been evaluated by the Neurogenetic Service of our Clinic in last two years (2011-2012). RESULTS: 45 patients were identified. The minimum prevalence of HSP in our area was of about 2.17-3.43/100,000. The SF-36 (quality of life) and SPRS (disease progression) scores were inversely related; the time-saving, four-stage scale of motor disability could predict the SPRS scores with a high statistical significance, and we encourage its use in HSP. Our study confirms SPG4 as the major cause of HSP. All SPG4 patients had a pure HSP phenotype, and the dominant inheritance was evident in the great majority of these subjects. SPG7 was the second genetic cause. Other genotypes were rarer (SPG10, SPG11, SPG17). CONCLUSION: Exact molecular diagnosis will allow a more accurate patient counseling and, hopefully, will lead to specific, targeted, therapeutic options for these chronic, still incurable diseases.

Lack of association between nuclear factor erythroid-derived 2-like 2 promoter gene polymorphisms and oxidative stress biomarkers in amyotrophic lateral sclerosis patients.

Oxidative stress involvement has been strongly hypothesized among the possible pathogenic mechanisms of motor neuron degeneration in amyotrophic lateral sclerosis (ALS). The intracellular redox balance is finely modulated by numerous complex mechanisms critical for cellular functions, among which the nuclear factor erythroid-derived 2-like 2 (NFE2L2/Nrf2) pathways. We genotyped, in a cohort of ALS patients (n = 145) and healthy controls (n = 168), three SNPs in Nrf2 gene promoter: -653 A/G, -651 G/A, and -617 C/A and evaluated, in a subset (n = 73) of patients, advanced oxidation protein products (AOPP), iron-reducing ability of plasma (FRAP), and plasma thiols (-SH) as oxidative damage peripheral biomarkers. Nrf2 polymorphisms were not different among patients and controls. Increased levels of AOPP (P < 0.05) and decreased levels of FRAP (P < 0.001) have been observed in ALS patients compared with controls, but no difference in -SH values was found. Furthermore, no association was found between biochemical markers of redox balance and Nrf2 polymorphisms. These data confirm an altered redox balance in ALS and indicate that, while being abnormally modified compared to controls, the oxidative stress biomarkers assessed in this study are independent from the -653 A/G, -651 G/A, and -617 C/A Nrf2 SNPs in ALS patients.

An "inflammatory" mitochondrial myopathy. A case report.

We describe a case of an adult male patient with progressive external ophthalmoplegia and upper limb weakness, who presented with an episode of sudden respiratory failure. Muscle biopsy showed ragged-red and COX-negative fibers associated with discrete inflammatory infiltrates and necrotizing features. Apart from artificial ventilator support, he was treated with intravenous immunoglobulins and carnitine, with excellent clinical outcome. Mitochondrial DNA analysis revealed the 3251A>G mutation, previously reported in association with rapidly progressive mitochondrial myopathy and respiratory failure. Our case expands the spectrum of this mutation and suggests a therapeutic attempt with immunoglobulins in mitochondrial patients with acute respiratory failure, at least when this mutation and/or muscle inflammation is present. Moreover, this case supports the idea of a pathologic inflammatory response induced by mitochondrial disease; such an abnormal response may be a contributory factor in disease progression or acute exacerbation typical of some mitochondrial diseases, but further studies are needed.

Oxidative stress biomarkers in patients with untreated obstructive sleep apnea syndrome.

BACKGROUND: The pathogenic role of oxidative stress in obstructive sleep apnea syndrome (OSAS) is still a matter of debate, with different studies obtaining contrasting results. METHODS: The aim of the present study was to evaluate three well-known markers of oxidative stress (advanced oxidation protein products [AOPP], ferric reducing antioxidant power [FRAP], and total glutathione [GSH]) in a cohort of 41 untreated patients with a new diagnosis of OSAS. RESULTS: We observed that OSAS patients showed increased protein oxidative damage and impaired antioxidant defenses. Patients with more severe OSAS had a lower total antioxidant capability. Preliminary data on a subgroup of patients (n=7) treated with CPAP show a significant increment of the FRAP values (P<0.005). CONCLUSIONS: Our findings indicate that such oxidative stress markers may be useful to detect and monitor redox imbalance in OSAS. Moreover, FRAP might be a new useful biomarker to monitor in vivo the oxidative response to CPAP therapy.

Oxidative stress treatment for clinical trials in neurodegenerative diseases.

Oxidative stress is a metabolic condition arising from imbalance between the production of potentially reactive oxygen species and the scavenging activities. Mitochondria are the main providers but also the main scavengers of cell oxidative stress. The role of mitochondrial dysfunction and oxidative stress in the pathogenesis of neurodegenerative diseases is well documented. Therefore, therapeutic approaches targeting mitochondrial dysfunction and oxidative damage hold great promise in neurodegenerative diseases. Despite this evidence, human experience with antioxidant neuroprotectants has generally been negative with regards to the clinical progress of disease, with unclear results in biochemical assays. Here we review the antioxidant approaches performed so far in neurodegenerative diseases and the future challenges in modern medicine.

Clock T3111C and Per2 C111G SNPs do not influence circadian rhythmicity in healthy Italian population.

A possible relationship between human circadian rhythmicity and polymorphisms in clock genes have been documented. However, these data are controversial, and studies both corroborating and denying them have been reported. T3111C Clock polymorphism had been associated with the human evening preference, however, this association has not been confirmed. Moreover, C111G Per2 polymorphism has been associated with the "morning larks" chronotype in one study, not yet replicated. We have, therefore, performed this study to evaluate whether Per2 C111G and Clock T3111C polymorphisms might influence sleep circadian rhythmicity in a sample of 219 Italian volunteers. A possible interaction between these polymorphisms was also investigated. No differences in Per2 C111G and Clock T3111C allele and genotype frequencies were found, and none of the combined Clock T3111C-Per2 C11G genotypes resulted more frequent in one group compared to the others. Present results do not support a role of these polymorphisms in the circadian phenotypes.

Clinical features and pathogenesis of Alzheimer's disease: involvement of mitochondria and mitochondrial DNA.

Alzheimer's disease (AD) is a neurodegenerative disorder which results in the irreversible loss of cortical neurons, particularly in the associative neocortex and hippocampus. AD is the most common form of dementia in the elderly people. Apart from the neuronal loss, the pathological hallmarks are extracellular senile plaques containing the peptide beta-amyloid (AP) and neurofibrillary tangles. The Af cascade hypothesis remains the main pathogenetic model, as suggested by familiar AD, mainly associated to mutation in amyloid precursor protein and presenilin genes. The remaining 95% of AD patients are mostly sporadic late-onset cases, with a complex aetiology due to interactions between environmental conditions and genetic features of the individual. Mitochondria play a central role in the bioenergetics of the cell and apoptotic cell death. Morphological, biochemical and genetic abnormalities of the mitochondria in several AD tissues have been reported. Impaired mitochondrial respiration, particularly COX deficiency, has been observed in brain, platelets and fibroblasts of AD patients. Somatic mutations in mitochondrial DNA (mtDNA) could cause energy failure and increased oxidative stress. No causative mutations in the mtDNA have been detected and studies on mtDNA polymorphisms are controversial, but the "mitochondrial cascade hypothesis" here revised, could explain many of the biochemical, genetic and pathological features of sporadic AD.

Oxidative stress biomarkers in mitochondrial myopathies, basally and after cysteine donor supplementation.

Mitochondrial diseases are due to impairment of the mitochondrial respiratory chain. A plausible pathogenic mechanism leading to cellular dysfunction and phenotypic expression is oxidative stress, but there are surprisingly few clinical studies on this subject. Glutathione (GSH) deficiency has been reported in mitochondrial diseases, and the biosynthesis of glutathione depends on cysteine availability. We have examined oxidative stress biomarkers [advanced oxidation protein products (AOPP) and ferric reducing antioxidant power (FRAP)] in blood samples from 27 patients and 42 controls. AOPP levels were greater in patients than in controls (P value <0.00001). Therefore, we performed a double-blind cross-over study to evaluate if 30-day supplementation with a whey-based cysteine donor could modify these markers, reduce lactate concentration during aerobic exercise, or enhance muscular strength and quality of life. Treatment did not modify lactate concentration, clinical scale (MRC) or quality of life (SF-36), but significantly reduced oxidative stress levels. Our findings reinforce the notions that in mitochondrial diseases oxidative stress is important and can be reduced by administration of a cysteine donor. Oxidative stress biomarkers may be useful to detect redox imbalance in mitochondrial diseases and to provide non-invasive tools to monitor disease status.