Genetic variants affecting NQO1 protein levels impact the efficacy of idebenone treatment in Leber hereditary optic neuropathy

Idebenone, the only approved treatment for Leber hereditary optic neuropathy (LHON), promotes recovery of visual function in up to 50% of patients, but we can neither predict nor understand the non-responders. Idebenone is reduced by the cytosolic NAD(P)H oxidoreductase I (NQO1) and directly shuttles electrons to respiratory complex III, bypassing complex I affected in LHON. We show here that two polymorphic variants drastically reduce NQO1 protein levels when homozygous or compound heterozygous. This hampers idebenone reduction. In its oxidized form, idebenone inhibits complex I, decreasing respiratory function in cells. By retrospectively analyzing a large cohort of idebenone-treated LHON patients, classified by their response to therapy, we show that patients with homozygous or compound heterozygous NQO1 variants have the poorest therapy response, particularly if carrying the m.3460G>A/MT-ND1 LHON mutation. These results suggest consideration of patient NQO1 genotype and mitochondrial DNA mutation in the context of idebenone therapy.

Generation of two human iPSC lines, HMGUi004-A and FINCBi004-A, from fibroblasts of MPAN patients carrying pathogenic recessive mutations in the gene C19orf12

Mitochondrial membrane Protein-Associated Neurodegeneration (MPAN) is a lethal neurodegenerative disorder caused by mutations in the human gene C19orf12. The molecular mechanisms underlying the disorder are still unclear, and no established therapy is available. Here, we describe the generation and characterization of two human induced pluripotent stem cell (iPSC) lines derived from skin fibroblasts of two MPAN patients carrying homozygous recessive mutations in C19orf12. These iPSC lines represent a useful resource for future investigations on the pathology of MPAN, as well as for the development of successful treatments.

Bedside assessment of dependence as an independent correlate of mortality in elderly patients admitted for Acute Coronary Syndromes

Background

Elderly patients are at high risk of dependence and mortality after acute coronary syndrome (ACS)

Purpose

To assess the impact of dependence detected by a simple bedside test in elderly patients admitted for ACS on 1-year mortality.

Methods

We compared mortality between patients with or without dependence based on an Activities of Daily Living (ADL) index <6 in a prospective, cohort of patients ≥75 years old admitted for an ACS to the cardiology department of our center using a Cox proportional survival model adjusted on pre-defined confounding variables (age, gender, revascularization, heart failure, left ventricular ejection fraction and admission GRACE and CRUSADE scores).

Results

In a cohort of 1011 consecutive patients, 946 underwent ADL assessment and completed one-year follow-up. Dependence was identified in 190 (20%). At 1 year follow-up 112 patients died, 52 (27.4%) in the dependent and 60 (7.9%) in the independent groups. Dependence was associated with higher rates of 1 year mortality both on undajusted (HR 3.79; 95% CI 2.62; 5.50], p<0.0001) and adjusted models (adj-HR 2.85; 95% CI 1.89; 4.33], p<0.0001). Other independent correlates of mortality were female gender (p<0.0001), CRUSADE score (p<0.0001) and coronary revascularization (p<0.001).

Conclusions

Dependence detected by a simple bedside test in patients ≥75 admitted for ACS is associated with a 2 to 3-fold increase of the risk of mortality independent of other predictors of poor outcome. Assessment of dependence should be performed in all elderly patients as a risk stratification tool and considered for the management of such patients.

Funding Acknowledgement

Type of funding sources: None.

The relevance of mitochondrial DNA variants fluctuation during reprogramming and neuronal differentiation of human iPSCs

The generation of inducible pluripotent stem cells (iPSCs) is a revolutionary technique allowing production of pluripotent patient-specific cell lines used for disease modeling, drug screening, and cell therapy. Integrity of nuclear DNA (nDNA) is mandatory to allow iPSCs utilization, while quality control of mitochondrial DNA (mtDNA) is rarely included in the iPSCs validation process. In this study, we performed mtDNA deep sequencing during the transition from parental fibroblasts to reprogrammed iPSC and to differentiated neuronal precursor cells (NPCs) obtained from controls and patients affected by mitochondrial disorders. At each step, mtDNA variants, including those potentially pathogenic, fluctuate between emerging and disappearing, and some having functional implications. We strongly recommend including mtDNA analysis as an unavoidable assay to obtain fully certified usable iPSCs and NPCs.

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mtDNA deep sequencing is mandatory in quality control of iPSCs

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mtDNA variants fluctuate at each step from fibroblasts/PBMC, to iPSCs and NPCs

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mtDNA variants greatly affect iPSC phenotype, reflecting their healthiness

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Results could be misinterpreted if mtDNA variants presence has not been assessed

Exploiting hiPSCs in Leber's Hereditary Optic Neuropathy (LHON): Present Achievements and Future Perspectives

More than 30 years after discovering Leber's hereditary optic neuropathy (LHON) as the first maternally inherited disease associated with homoplasmic mtDNA mutations, we still struggle to achieve effective therapies. LHON is characterized by selective degeneration of retinal ganglion cells (RGCs) and is the most frequent mitochondrial disease, which leads young people to blindness, in particular males. Despite that causative mutations are present in all tissues, only a specific cell type is affected. Our deep understanding of the pathogenic mechanisms in LHON is hampered by the lack of appropriate models since investigations have been traditionally performed in non-neuronal cells. Effective in-vitro models of LHON are now emerging, casting promise to speed our understanding of pathophysiology and test therapeutic strategies to accelerate translation into clinic. We here review the potentials of these new models and their impact on the future of LHON patients.

TFG binds LC3C to regulate ULK1 localization and autophagosome formation

The early secretory pathway and autophagy are two essential and evolutionarily conserved endomembrane processes that are finely interlinked. Although growing evidence suggests that intracellular trafficking is important for autophagosome biogenesis, the molecular regulatory network involved is still not fully defined. In this study, we demonstrate a crucial effect of the COPII vesicle-related protein TFG (Trk-fused gene) on ULK1 puncta number and localization during autophagy induction. This, in turn, affects formation of the isolation membrane, as well as the correct dynamics of association between LC3B and early ATG proteins, leading to the proper formation of both omegasomes and autophagosomes. Consistently, fibroblasts derived from a hereditary spastic paraparesis (HSP) patient carrying mutated TFG (R106C) show defects in both autophagy and ULK1 puncta accumulation. In addition, we demonstrate that TFG activity in autophagy depends on its interaction with the ATG8 protein LC3C through a canonical LIR motif, thereby favouring LC3C-ULK1 binding. Altogether, our results uncover a link between TFG and autophagy and identify TFG as a molecular scaffold linking the early secretion pathway to autophagy.

Generation of two human iPSC lines, FINCBi002-A and FINCBi003-A, carrying heteroplasmic macrodeletion of mitochondrial DNA causing Pearson's syndrome

Pearson marrow pancreas syndrome (PMPS) is a sporadic mitochondrial disease, resulting from the clonal expansion of a mutated mitochondrial DNA (mtDNA) molecule bearing a macro-deletion, and therefore missing essential genetic information. PMPS is characterized by the presence of deleted (Δ) mtDNA that co-exist with the presence of a variable amount of wild-type mtDNA, a condition termed heteroplasmy. All tissues of the affected individual, including the haemopoietic system and the post-mitotic, highly specialized tissues (brain, skeletal muscle, and heart) contain the large-scale mtDNA deletion in variable amount. We generated human induced pluripotent stem cells (hiPSCs) from two PMPS patients, carrying different type of large-scale deletion.

Bedside assessment of the risk of non-compliance to medication is associated with mortality in elderly patients admitted for acute coronary syndromes

Background

Elderly patients are at high risk of mortality in the setting of acute coronary syndromes (ACS).

Purpose

We investigated whether compliance assessed by Compliance Evaluation Test (CET) in elderly patients admitted for acute coronary syndromes was associated with higher risk of one-year mortality.

Methods

We used the data from a prospective, open, ongoing cohort of patients ≥75 years old admitted for ACS to a tertiary center. The CET is a validated 6 item test easily performed at bedside. Non-compliance is defined by ≥ “Yes” answers.

We used a Cox model, un-adjusted and adjusted on predefined correlates of mortality (age, gender, and GRACE score) to assess the relationship between the risk of non-compliance and 1-year mortality.

Results

Two hundred fifty-five consecutive patients (age 83±5, female gender 59.6%, GRACE score 175±24) with CET assessment within 48 hours after admission and 1 year follow-up were included in the analysis. 225 (88%) were identified as compliant and 30 (12%) as non-compliant based on the CET.

Thirthy-six deaths occurred at 1 year follow-up, 24 (10.6%) and 12 (30%) in compliant and non-compliant patients respectively.

There was an almost 4-fold increase in the risk of one-year mortality in association with non-compliance (HR 4.16; 95% CI 2.03 to 8.5, p<0.0001) and adj-HR 3.93; 95% CI 1.87 to 8.3, p=0.003), independent of other covariables.

Conclusions

In elderly patients admitted for ACS, the risk of non-compliance assessed by the simple bedside test is associated with a 4-fold increase in the risk of 1-year mortality independent of other correlates of mortality. Our results support specific measures to improve compliance in such patients.

Survival based on compliance test

Funding Acknowledgement

Type of funding source: None

SSBP1 mutations cause mtDNA depletion underlying a complex optic atrophy disorder

Inherited optic neuropathies include complex phenotypes, mostly driven by mitochondrial dysfunction. We report an optic atrophy spectrum disorder, including retinal macular dystrophy and kidney insufficiency leading to transplantation, associated with mitochondrial DNA (mtDNA) depletion without accumulation of multiple deletions. By whole-exome sequencing, we identified mutations affecting the mitochondrial single-strand binding protein (SSBP1) in 4 families with dominant and 1 with recessive inheritance. We show that SSBP1 mutations in patient-derived fibroblasts variably affect the amount of SSBP1 protein and alter multimer formation, but not the binding to ssDNA. SSBP1 mutations impaired mtDNA, nucleoids, and 7S-DNA amounts as well as mtDNA replication, affecting replisome machinery. The variable mtDNA depletion in cells was reflected in severity of mitochondrial dysfunction, including respiratory efficiency, OXPHOS subunits, and complex amount and assembly. mtDNA depletion and cytochrome c oxidase-negative cells were found ex vivo in biopsies of affected tissues, such as kidney and skeletal muscle. Reduced efficiency of mtDNA replication was also reproduced in vitro, confirming the pathogenic mechanism. Furthermore, ssbp1 suppression in zebrafish induced signs of nephropathy and reduced optic nerve size, the latter phenotype complemented by WT mRNA but not by SSBP1 mutant transcripts. This previously unrecognized disease of mtDNA maintenance implicates SSBP1 mutations as a cause of human pathology.

Relationship between pathological gambling, alcoholism and drug addiction

The aim of this survey was to evaluate the distribution of pathological gamblers treated in an alcohol or drug addiction treatment program run by the Italian National Health Service providing assistance to alcohol and drug abusers in Venice (North east Italy) from September 1 to December 31, 2001. Each drug- or alcohol-dependent patient retained for treatment for at least one month was administrated an anonymous precoded questionnaire to collect personal and socio-demographic features. The South Oaks Gambling Screen (SOGS) was used to measure pathological gambling and the Symptom Checklist-90-Revised (SCL-90-R) to measure psychological distress levels and psychiatric symptoms. Among the 113 enrolled subjects we found a greater prevalence of pathological gamblers among drug users than among alcoholics and drug abusers were younger than alcoholics; moreover, there was a prevalence of single status, low schooling, and a low-medium income despite full-time occupation. Only pathological gamblers revealed a significant positive correlation with a family history of gambling and reached positive scores (>1.5) for some likely psychiatric symptoms. Abuse disorders and pathological gambling are frequently associated with multidependence personality traits. Preventing substance abuse may reduce the pathological gambling rates and better results can be obtained with educational campaigns beginning earlier in life.

The immunomodulating glycoprotein extract from Klebsiella pneumoniae RU 41740 exerts a suppressive effect on human monocyte death by apoptosis

Programmed cell death or apoptosis is a physiological cell suicide process that can be suppressed by survival factors. Monocytes undergo rapid apoptosis in culture, unless signalled by cytokines or the bacterial lipopolysaccharide LPS. We have investigated the effect on monocyte apoptosis of the immunostimulating agent RU 41740 (Biostim), a glycoprotein extract from the Klebsiella pneumoniae K2O1 strain that is used for the prevention of recurrent infections. RU 41740, as LPS, strongly enhanced monocyte survival in vitro, an effect related to apoptosis suppression. RU 41740 at concentration ranging from 1 ng/ml to 10 microg/ml prevented apoptosis induced both by survival factor deprival and by gamma-irradiation. Our observation suggests that enhancement of monocyte survival may represent a component of the reported immunostimulating effect of this compound.

Circulating autoantibodies against central nervous system (CNS) antigens in neurological diseases

A number of investigators have reported the detection of circulating autoantibodies directed against serum and cerebrospinal fluid (CSF) neuronal antigens in certain neurological clinical conditions. Using an immunohistochemical technique, we examined the sera and (when available) the CSF from 120 patients with several neurological disorders and 40 controls in order to analyze the incidence and specificity of the detection of these autoantibodies. Circulating autoantibodies were found in 3 patients with cerebellar degeneration and in 3 patients with stiff-man syndrome, and different staining patterns were revealed in the same disease. Our findings confirm the reported disease-specificity of the detection of these autoantibodies in biological fluids, suggesting that a standardized immunohistochemical technique could constitute an easy and reproducible diagnostic tool in selected neurological conditions. These procedures enable the identification of an immunological pathogenesis of the disease and, in some case, early cancer detection. When atypical staining patterns of staining are found at immunohistochemistry, Western blot characterization of the recognized neuronal antigens is recommended.