Objective
Accumulation of misfolded superoxide dismutase‐1 (SOD1) is a pathological hallmark of SOD1‐related amyotrophic lateral sclerosis (ALS) and is observed in sporadic ALS where its role in ...pathogenesis is controversial. Understanding in vivo protein kinetics may clarify how SOD1 influences neurodegeneration and inform optimal dosing for therapies that lower SOD1 transcripts.
Methods
We employed stable isotope labeling paired with mass spectrometry to evaluate in vivo protein kinetics and concentration of soluble SOD1 in cerebrospinal fluid (CSF) of SOD1 mutation carriers, sporadic ALS participants and controls. A deaminated SOD1 peptide, SDGPVKV, that correlates with protein stability was also measured.
Results
In participants with heterozygous SOD1A5V mutations, known to cause rapidly progressive ALS, mutant SOD1 protein exhibited ~twofold faster turnover and ~ 16‐fold lower concentration compared to wild‐type SOD1 protein. SDGPVKV levels were increased in SOD1A5V carriers relative to controls. Thus, SOD1 mutations impact protein kinetics and stability. We applied this approach to sporadic ALS participants and found that SOD1 turnover, concentration, and SDGPVKV levels are not significantly different compared to controls.
Interpretation
These results highlight the ability of stable isotope labeling approaches and peptide deamidation to discern the influence of disease mutations on protein kinetics and stability and support implementation of this method to optimize clinical trial design of gene and molecular therapies for neurological disorders.
Trial Registration
Clinicaltrials.gov: NCT03449212.
Understanding the natural history of familial amyotrophic lateral sclerosis (ALS) caused by SOD1 mutations (ALS
) will provide key information for optimising clinical trials in this patient ...population.
To establish an updated natural history of ALS
.
Retrospective cohort study from 15 medical centres in North America evaluated records from 175 patients with ALS with genetically confirmed SOD1 mutations, cared for after the year 2000.
Age of onset, survival, ALS Functional Rating Scale (ALS-FRS) scores and respiratory function were analysed. Patients with the A4V (Ala-Val) SOD1 mutation (SOD1
), the largest mutation population in North America with an aggressive disease progression, were distinguished from other SOD1 mutation patients (SOD1
) for analysis.
Mean age of disease onset was 49.7±12.3 years (mean±SD) for all SOD1 patients, with no statistical significance between SOD1
and SOD1
(p=0.72, Kruskal-Wallis). Total SOD1 patient median survival was 2.7 years. Mean disease duration for all SOD1 was 4.6±6.0 and 1.4±0.7 years for SOD1
. SOD1
survival probability (median survival 1.2 years) was significantly decreased compared with SOD1
(median survival 6.8 years; p<0.0001, log-rank). A statistically significant increase in ALS-FRS decline in SOD1
compared with SOD1
participants (p=0.02) was observed, as well as a statistically significant increase in ALS-forced vital capacity decline in SOD1
compared with SOD1
(p=0.02).
SOD1
is an aggressive, but relatively homogeneous form of ALS. These SOD1-specific ALS natural history data will be important for the design and implementation of clinical trials in the ALS
patient population.
Highlights • We performed sequencing of 38 genes in 79 sporadic inclusion body myositis patients (sIBM). • Genetic variants associated with hereditary diseases may be found in sIBM patients but their ...significance is unclear. • Genetic studies in sIBM patients may be clinically helpful in distinguishing hereditary diseases.
Background and purpose
AV‐1451 (18F‐AV‐1451, flortaucipir) positron emission tomography was performed in C9orf72 expansion carriers to assess tau accumulation and disease manifestation.
Methods
Nine ...clinically characterized C9orf72 expansion carriers and 18 age‐ and gender‐ matched cognitively normal individuals were psychometrically evaluated and underwent tau positron emission tomography imaging. The regional AV‐1451 standard uptake value ratios from multiple brain regions were analyzed. Spearman correlation was performed to relate the AV‐1451 standard uptake value ratio to clinical, psychometric and cerebrospinal fluid measures.
Results
C9orf72 expansion carriers had increased AV‐1451 binding in the entorhinal cortex compared to controls. Primary age‐related tauopathy was observed postmortem in one patient. AV‐1451 uptake did not correlate with clinical severity, disease duration, psychometric performance or cerebrospinal fluid markers.
Conclusion
C9orf72 expansion carriers exhibited increased AV‐1451 uptake in entorhinal cortex compared to cognitively normal controls, suggesting a propensity for primary age‐related tauopathy. However, AV‐1451 accumulation was not associated with psychometric performance in our cohort.
We developed stable isotope labeling and mass spectrometry approaches to measure the kinetics of multiple isoforms and fragments of tau in the human central nervous system (CNS) and in human induced ...pluripotent stem cell (iPSC)-derived neurons. Newly synthesized tau is truncated and released from human neurons in 3 days. Although most tau proteins have similar turnover, 4R tau isoforms and phosphorylated forms of tau exhibit faster turnover rates, suggesting unique processing of these forms that may have independent biological activities. The half-life of tau in control human iPSC-derived neurons is 6.74 ± 0.45 days and in human CNS is 23 ± 6.4 days. In cognitively normal and Alzheimer’s disease participants, the production rate of tau positively correlates with the amount of amyloid plaques, indicating a biological link between amyloid plaques and tau physiology.
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•Multiple forms of tau exist in the human brain, CSF, and iPSC-derived neurons•Newly synthesized tau is truncated and actively released by human neurons•Fibrillogenic forms of tau have shorter half-lives than non-fibrillogenic forms•Tau production rate positively correlates with amyloid plaque burden
Sato et al. show that stable isotope labeling kinetics enable measurement of tau in the CNS and in iPSC-derived neurons. Specific forms of tau are uniquely processed in neurons and tau production rates correlate with amyloid accumulation in human subjects.
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease in which microglia play a significant and active role. Recently, a rare missense variant (p.R47H) in the microglial activating ...gene TREM2 was found to increase the risk of several neurodegenerative diseases, including Alzheimer disease. Whether the p.R47H variant is a risk factor for ALS is not known.
To determine whether p.R47H (rs75932628) in TREM2 is a risk factor for ALS and assess whether TREM2 expression is dysregulated in disease.
Samples of DNA from 923 individuals with sporadic ALS and 1854 healthy control individuals self-reported as non-Hispanic white were collected from ALS clinics in the United States and genotyped for the p.R47H variant in TREM2. Clinical data were obtained on ALS participants for genotype/phenotype correlations. Expression of TREM2 was measured by quantitative polymerase chain reaction and compared in spinal cord samples from 18 autopsied patients with ALS and 12 neurologically healthy controls, as well as from wild-type and transgenic SOD1G93A mice.
Minor allele frequency of rs75932628 and relative expression of TREM2.
The TREM2 variant p.R47H was more common in patients with ALS than in the controls and is therefore a significant risk factor for ALS (odds ratio, 2.40; 95% CI, 1.29-4.15; P = 4.1×10-3). Furthermore, TREM2 expression was increased in spinal cord samples from ALS patients and SOD1G93A mice (P = 2.8×10-4 and P = 2.8×10-9, respectively), confirming dysregulated TREM2 in disease. Expression of TREM2 in the human spinal cord was negatively correlated with survival (P = .04) but not with other phenotypic aspects of disease.
This study demonstrates that the TREM2 p.R47H variant is a potent risk factor for sporadic ALS. To our knowledge, these findings identify the first genetic influence on neuroinflammation in ALS and highlight the TREM2 signaling pathway as a therapeutic target in ALS and other neurodegenerative diseases.
Answer ALS is a biological and clinical resource of patient-derived, induced pluripotent stem (iPS) cell lines, multi-omic data derived from iPS neurons and longitudinal clinical and smartphone data ...from over 1,000 patients with ALS. This resource provides population-level biological and clinical data that may be employed to identify clinical-molecular-biochemical subtypes of amyotrophic lateral sclerosis (ALS). A unique smartphone-based system was employed to collect deep clinical data, including fine motor activity, speech, breathing and linguistics/cognition. The iPS spinal neurons were blood derived from each patient and these cells underwent multi-omic analytics including whole-genome sequencing, RNA transcriptomics, ATAC-sequencing and proteomics. The intent of these data is for the generation of integrated clinical and biological signatures using bioinformatics, statistics and computational biology to establish patterns that may lead to a better understanding of the underlying mechanisms of disease, including subgroup identification. A web portal for open-source sharing of all data was developed for widespread community-based data analytics.
As potential treatments for C9ORF72‐associated amyotrophic lateral sclerosis (c9ALS) approach clinical trials, the identification of prognostic biomarkers for c9ALS becomes a priority. We show that ...levels of phosphorylated neurofilament heavy chain (pNFH) in cerebrospinal fluid (CSF) predict disease status and survival in c9ALS patients, and are largely stable over time. Moreover, c9ALS patients exhibit higher pNFH levels, more rapid disease progression, and shorter survival after disease onset than ALS patients without C9ORF72 expansions. These data support the use of CSF pNFH as a prognostic biomarker for clinical trials, which will increase the likelihood of successfully developing a treatment for c9ALS. Ann Neurol 2017;82:139–146
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