Philippe Corcia

DYSLIPIDEMIA IS A PROTECTIVE FACTOR IN AMYOTROPHIC LATERAL SCLEROSIS

Background: Amyotrophic lateral sclerosis (ALS) is the most serious form of degenerative motor neuron disease in adults, characterized by upper and lower motor neuron degeneration, skeletal muscle atrophy, paralysis, and death. High prevalence of malnutrition and weight loss adversely affect quality of life. Moreover, two thirds of patients develop a hypermetabolism of unknown cause, leading to increased resting energy expenditure. Inasmuch as lipids are the major source of energy for muscles, we determined the status of lipids in a population of patients with ALS and investigated whether lipid contents may have an impact on disease progression and survival. Methods: Blood concentrations of triglycerides, cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) were measured in a cohort of 369 patients with ALS and compared to a control group of 286 healthy subjects. Postmortem histologic examination was performed on liver specimens from 59 other patients with ALS and 16 patients with Parkinson disease (PD). Results: The frequency of hyperlipidemia, as revealed by increased plasma levels of total cholesterol or LDL, was twofold higher in patients with ALS than in control subjects. As a result, steatosis of the liver was more pronounced in patients with ALS than in patients with PD. Correlation studies demonstrated that bearing an abnormally elevated LDL/HDL ratio significantly increased survival by more than 12 months. Conclusions: Hyperlipidemia is a significant prognostic factor for survival of patients with amyotrophic lateral sclerosis. This finding highlights the importance of nutritional intervention strategies on disease progression and claims our attention when treating these patients with lipid-lowering drugs.

SOD1, ANG, VAPB, TARDBP, and FUS mutations in familial amyotrophic lateral sclerosis: genotype–phenotype correlations

Background Mutations in SOD1, ANG, VAPB, TARDBP and FUS genes have been identified in amyotrophic lateral sclerosis (ALS). Methods The relative contributions of the different mutations to ALS were estimated by systematically screening a cohort of 162 families enrolled in France and 500 controls (1000 chromosomes) using molecular analysis techniques and performing phenotype–genotype correlations. Results 31 pathogenic missense mutations were found in 36 patients (20 SOD1, 1 ANG, 1 VAPB, 7 TARDBP and 7 FUS). Surprisingly two FUS mutation carriers also harboured ANG variants. One family of Japanese origin with the P56S VAPB mutation was identified. Seven novel mutations (three in SOD1, two in TARDBP, two in FUS) were found. None of them was detected in controls. Segregation of detected mutations with the disease was confirmed in 11 families including five pedigrees carrying the novel mutations. Clinical comparison of SOD1, TARDBP, FUS and other familial ALS patients (with no mutation in the screened genes) revealed differences in site of onset (predominantly lower limbs for SOD1 and upper limbs for TARDBP mutations), age of onset (younger with FUS mutations), and in lifespan (shorter for FUS carriers). One third of SOD1 patients survived more than 7 years: these patients had earlier disease onset than those presenting with a more typical course. Differences were also observed among FUS mutations, with the R521H FUS mutation being associated with longer disease duration. Conclusions This study identifies new genetic associations with ALS and provides phenotype–genotype correlations with both previously reported and novel mutations.

Reduced expression of the Kinesin-Associated Protein 3 (KIFAP3) gene increases survival in sporadic amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis is a degenerative disorder of motor neurons that typically develops in the 6th decade and is uniformly fatal, usually within 5 years. To identify genetic variants associated with susceptibility and phenotypes in sporadic ALS, we performed a genome-wide SNP analysis in sporadic ALS cases and controls. A total of 288,357 SNPs were screened in a set of 1,821 sporadic ALS cases and 2,258 controls from the U.S. and Europe. Survival analysis was performed using 1,014 deceased sporadic cases. Top results for susceptibility were further screened in an independent sample set of 538 ALS cases and 556 controls. SNP rs1541160 within the KIFAP3 gene (encoding a kinesin-associated protein) yielded a genome-wide significant result (P = 1.84 × 10−8) that withstood Bonferroni correction for association with survival. Homozygosity for the favorable allele (CC) conferred a 14.0 months survival advantage. Sequence, genotypic and functional analyses revealed that there is linkage disequilibrium between rs1541160 and SNP rs522444 within the KIFAP3 promoter and that the favorable alleles of rs1541160 and rs522444 correlate with reduced KIFAP3 expression. No SNPs were associated with risk of sporadic ALS, site of onset, or age of onset. We have identified a variant within the KIFAP3 gene that is associated with decreased KIFAP3 expression and increased survival in sporadic ALS. These findings support the view that genetic factors modify phenotypes in this disease and that cellular motor proteins are determinants of motor neuron viability.

Abnormal SMN1 gene copy number is a susceptibility factor for amyotrophic lateral sclerosis

The etiology of amyotrophic lateral sclerosis remains unknown in the majority of cases. Homozygous SMN1 (survival motor neuron) gene deletion causes spinal muscular atrophy, and SMN2 gene deletions are possible risk factors in lower motor neuron disease. We studied SMN1 and SMN2 genes copy numbers in 167 amyotrophic lateral sclerosis patients and in 167 matched controls. We noted that 16% of amyotrophic lateral sclerosis patients had an abnormal copy number of the SMN1 gene (1 or 3 copies), compared with 4% of controls. An abnormal SMN1 gene locus may be a susceptibility factor for amyotrophic lateral sclerosis.

Molecular Imaging of Microglial Activation in Amyotrophic Lateral Sclerosis

There is growing evidence of activated microglia and inflammatory processes in the cerebral cortex in amyotrophic lateral sclerosis (ALS). Activated microglia is characterized by increased expression of the 18 kDa translocator protein (TSPO) in the brain and may be a useful biomarker of inflammation. In this study, we evaluated neuroinflammation in ALS patients using a radioligand of TSPO, 18F-DPA-714. Ten patients with probable or definite ALS (all right-handed, without dementia, and untreated by riluzole or other medication that might bias the binding on the TSPO), were enrolled prospectively and eight healthy controls matched for age underwent a PET study. Comparison of the distribution volume ratios between both groups were performed using a Mann-Whitney’s test. Significant increase of distribution of volume ratios values corresponding to microglial activation was found in the ALS sample in primary motor, supplementary motor and temporal cortex (p = 0.009, p = 0.001 and p = 0.004, respectively). These results suggested that the cortical uptake of 18F-DPA-714 was increased in ALS patients during the “time of diagnosis” phase of the disease. This finding might improve our understanding of the pathophysiology of ALS and might be a surrogate marker of efficacy of treatment on microglial activation.

Phenotype difference between ALS patients with expanded repeats in C9ORF72 and patients with mutations in other ALS-related genes

Background Expanded GGGGCC hexanucleotide repeats in the promoter of the C9ORF72 gene have recently been identified in frontotemporal dementia (FTD), Amyotrophic Lateral Sclerosis (ALS) and ALS-FTD and appear as the most common genetic cause of familial (FALS) and sporadic (SALS) forms of ALS. Methods We searched for the C9ORF72 repeat expansion in 950 French ALS patients (225 FALS and 725 SALS) and 580 control subjects and performed genotype-phenotype correlations. Results The repeat expansion was present in 46% of FALS, 8% of SALS and 0% of controls. Phenotype comparisons were made between FALS patients with expanded C9ORF72 repeats and patients carrying another ALS-related gene (SOD1, TARDBP, FUS) or a yet unidentified genetic defect. SALS patients with and without C9ORF72 repeat expansions were also compared. The C9ORF72 group presented more frequent bulbar onset both in FALS (p<0.0001 vs SOD1, p=0.002 vs TARDBP, p=0.011 vs FUS, p=0.0153 vs other FALS) and SALS (p=0.047). FALS patients with C9ORF72 expansions had more frequent association with FTD than the other FALS patients (p<0.0001 vs SOD1, p=0.04 vs TARDBP, p=0.004 vs FUS, p=0.03 vs other FALS). C9ORF72-linked FALS patients presented an older age of onset than SOD1 (p=0.0139) or FUS mutation (p<0.0001) carriers. Disease duration was shorter for C9ORF72 expansion carriers than for SOD1 (p<0.0001) and TARDBP (p=0.0242) carriers, other FALS (p<0.0001) and C9ORF72-negative SALS (p=0.0006). Conclusions Our results confirm the major role of expanded repeats in C9ORF72 as causative for ALS and provide evidence for specific phenotypic aspects compared to patients with other ALS-related genes.

Causes of death amongst French patients with amyotrophic lateral sclerosis: a prospective study

Background and purpose:  To prospectively investigate causes of death and the circumstances surrounding death in 302 patients with amyotrophic lateral sclerosis (ALS). The functional status of patients immediately before death was also determined.

Causes of death in a post‐mortem series of ALS patients

Death represents the main hallmark of amyotrophic lateral sclerosis (ALS). Despite its importance in clinical care and phase III trials, many uncertainties remain on the cause of death due to the lack of post‐mortem verifications. To provide a more robust approach to these causes, we performed a retrospective pathological study on a large cohort of patients. 100 ALS patients referred for a deterioration of their clinical condition and who died in the ALS clinic of Salpétrière had a complete macroscopic and microscopic post‐mortem analysis. The clinical causes of death reported on medical records were compared to the results of autopsy. The concordance between clinical and pathological conclusions was insufficient (20%) to consider clinical assessment as a reliable marker of causes of death. At autopsy, broncho‐pneumonia and pneumonia were the main causes of death. Heart failure, representing 10% of deaths, was two times more frequent in bulbar than in spinal ALS. Pulmonary embolism representing 6% of death was exclusively found in spinal onset patients and is related to lower limbs disability. An effort has to be made for a better understanding of the causes of deterioration of ALS patients. A more proactive attitude to treat respiratory infections could have a significant impact on survival.

Impaired glucose tolerance in patients with amyotrophic lateral sclerosis

Our objectives were to analyse carbohydrate metabolism in a series of ALS patients and to examine potential association with parameters of lipid metabolism and clinical features. Glucose tolerance was assessed by the oral glucose tolerance test in 21 non-diabetic ALS patients and compared with 21 age- and sex-matched normal subjects. Lipids and lactate/pyruvate ratio, levels of pro-inflammatory cytokines (tumour necrosis factor-alpha and interleukin-6) and adipocytokines (leptin and adiponectin) were also measured in ALS patients. Mann-Whitney U-tests analysed continuous data and Fishers exact tests assessed categorical data. Blood glucose determined 120 min after the glucose bolus was significantly higher in patients with ALS (7.41 mmol/l±1.68) compared to controls (6.05±1.44, p=0.006). ALS patients with impaired glucose tolerance (IGT) according to WHO criteria (n=7, 33%) were more likely to have elevated free fatty acids (FFA) levels compared to patients with normal glucose tolerance (0.77 nmol/l±0.30 vs. 0.57±0.19, p=0.04). IGT was not associated with disease duration or severity. In conclusion, patients with ALS show abnormal glucose tolerance that could be associated with increased FFA levels, a key determinant of insulin resistance. The origin of glucose homeostasis abnormalities in ALS may be multifactorial and deserves further investigation.

1H-NMR-Based Metabolomic Profiling of CSF in Early Amyotrophic Lateral Sclerosis

Background Pathophysiological mechanisms involved in amyotrophic lateral sclerosis (ALS) are complex and none has identified reliable markers useful in routine patient evaluation. The aim of this study was to analyze the CSF of patients with ALS by 1H NMR (Nuclear Magnetic Resonance) spectroscopy in order to identify biomarkers in the early stages of the disease, and to evaluate the biochemical factors involved in ALS. Methodology CSF samples were collected from patients with ALS at the time of diagnosis and from patients without neurodegenerative diseases. One and two-dimensional 1H NMR analyses were performed and metabolites were quantified by the ERETIC method. We compared the concentrations of CSF metabolites between both groups. Finally, we performed principal component (PCA) and discriminant analyses. Principal Findings Fifty CSF samples from ALS patients and 44 from controls were analyzed. We quantified 17 metabolites including amino-acids, organic acids, and ketone bodies. Quantitative analysis revealed significantly lower acetate concentrations (p = 0.0002) in ALS patients compared to controls. Concentration of acetone trended higher (p = 0.015), and those of pyruvate (p = 0.002) and ascorbate (p = 0.003) were higher in the ALS group. PCA demonstrated that the pattern of analyzed metabolites discriminated between groups. Discriminant analysis using an algorithm of 17 metabolites revealed that patients were accurately classified 81.6% of the time. Conclusion/Significance CSF screening by NMR spectroscopy could be a useful, simple and low cost tool to improve the early diagnosis of ALS. The results indicate a perturbation of glucose metabolism, and the need to further explore cerebral energetic metabolism.