Amyotrophic lateral sclerosis (ALS) is the most frequent motor neuron disease. Cytoplasmic fused in sarcoma (FUS) aggregates are pathological hallmarks of FUS-ALS. Proper shuttling between the ...nucleus and cytoplasm is essential for physiological cell function. However, the initial event in the pathophysiology of FUS-ALS remains enigmatic. Using human induced pluripotent stem cell (hiPSCs)-derived motor neurons (MNs), we show that impairment of poly(ADP-ribose) polymerase (PARP)-dependent DNA damage response (DDR) signaling due to mutations in the FUS nuclear localization sequence (NLS) induces additional cytoplasmic FUS mislocalization which in turn results in neurodegeneration and FUS aggregate formation. Our work suggests that a key pathophysiologic event in ALS is upstream of aggregate formation. Targeting DDR signaling could lead to novel therapeutic routes for ameliorating ALS.
The shift in cellular energy production from oxidative phosphorylation (OXPHOS) to glycolysis, even under aerobic conditions, called the Warburg effect, is a feature of most solid tumors. The ...activity levels of OXPHOS complexes and citrate synthase were determined in astrocytomas. A gradual decrease of citrate synthase and OXPHOS complexes was observed depending on tumor grade. In low‐grade astrocytomas (WHO grade II), enzyme activities of citrate synthase, complex I, and complex V were comparable to those of normal brain tissue. A trend to reduced activities was observed for complexes II–IV. In glioblastoma (WHO grade IV), activities of citrate synthase and complexes I–IV were decreased by 56–92% as compared with normal brain. Immunohistochemical staining for porin revealed that the tumorpil of low‐grade astrocytomas displays characteristics of the mitochondria‐rich neuropil of normal brain tissue. In high‐grade tumors (WHO grades III and IV), the tumorpil was characterized by severe morphologic alterations as well as loss of “pilem” structures. Specific alterations of OXPHOS complexes were observed in all astrocytic tumors by immunohistochemical analysis: 80% of astrocytomas exhibited severe deficiency of complex IV; complex I showed a gradual reduction in amount with increasing tumor grade, whereas complex II showed reduced levels only in high‐grade (WHO grade IV) tumors (9/12); complexes III and V did not show significant alterations compared with normal brain tissue. OXPHOS defects were present not only in the cell bodies of tumor cells but also in the pilem structures, indicating that the ramifications/protuberances (tumorpil) in general originate from tumor cells. GLIA 2014;62:514–525
Main Points
Astrocytic tumors show a high frequency of OXPHOS defects. These alterations are not only present in the cell bodies of tumor cells, but also in pilem structures, indicating that the tumorpil originates from tumor cells.
•Hand muscle denervation was studied in adult spinal muscular atrophy (SMA) patients with MUNIX.•Adult SMA patients had a pathophysiological remarkable denervation pattern of hand muscles, a ...‘reversed split hand’.•MUNIX is a biomarker for upcoming questions in adult SMA.
There is still insufficient knowledge about natural history in adult spinal muscular atrophy, thus valid markers for treatment and disease monitoring are urgently needed.
We studied hand muscle innervation pattern of 38 adult genetically confirmed 5q spinal muscular atrophy (SMA) patients by the motor unit number index (MUNIX) method. Data were compared to healthy controls and amyotrophic lateral sclerosis (ALS) patients and systematically correlated to typical disease-relevant scores and other clinical as well as demographic characteristics.
Denervation of hand muscles in adult SMA was not evenly distributed. By calculation of the MUNIX ratios, we identified a specific hand muscle wasting pattern for SMA which is different to the split hand in ALS. Furthermore, MUNIX parameters strongly correlated with established disease course parameters independent of disease stages.
We found a pathophysiological remarkable denervation pattern of hand muscles, a ‘reversed split hand’. MUNIX of single hand muscles correlated well with disease severity and thus represents an easily available biomarker for adult SMA.
Our data show the power of the MUNIX method as a biomarker for upcoming questions in adult SMA.
Objective
To determine the diagnostic and monitoring value of serum neurofilament light chain (NfL) in spinal muscular atrophy (SMA).
Methods
We measured serum NfL in 46 SMA patients at baseline and ...over 14 months of treatment with the antisense-oligonucleotide (ASO) nusinersen using the ultrasensitive single molecule array (Simoa) technology. Serum NfL levels of SMA patients were compared to controls and related to cerebrospinal fluid (CSF) NfL, blood-CSF barrier function quantified by the albumin blood/CSF ratio (Qalb) and motor scores (Hammersmith Functional Motor Scale Expanded, HFMSE; Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised, ALSFRS-R).
Results
Serum NfL levels of SMA patients were in the range of controls (
p
= 0.316) and did not correlate with CSF NfL (
ρ
= 0.302,
p
= 0.142) or Qalb (
ρ
= − 0.160,
p
= 0.293). During therapy, serum NfL levels were relatively stable with notable concentration changes in single SMA patients, however, within the control range. Higher NfL levels were associated with worse motor performance in SMA (baseline: HFMSE
ρ
= − 0.330,
p
= 0.025, ALSFRS-R
ρ
= − 0.403,
p
= 0.005; after 10 months: HFMSE
ρ
= − 0.525,
p
= 0.008, ALSFRS-R
ρ
= − 0.537,
p
= 0.007), but changes in motor scores did not correlate with changes in serum NfL.
Conclusion
Diagnostic and monitoring performance of serum NfL measurement seems to differ between SMA subtypes. Unlike to SMA type 1, in adolescent and adult SMA type 2 and 3 patients, neurodegeneration is not reflected by increased NfL levels and short-term therapeutic effects cannot be observed. Long-term follow-up has to be performed to see if even low levels of NfL might be good prognostic markers.
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder causing progressive loss of motor neurons. Mutations in Fused in sarcoma (FUS) leading to its cytoplasmic mislocalization cause a ...subset of ALS. Under stress, mutant FUS localizes to stress granules (SGs)—cytoplasmic condensates composed of RNA and various proteins. Aberrant dynamics of SGs is linked to the pathology of ALS. Here, using motor neurons (MNs) derived from human induced pluripotent stem cells, we show that, in mutant FUS, MN dynamics of SGs is disturbed. Additionally, heat-shock response (HSR) and integrated stress response (ISR) involved in the regulation of SGs are upregulated in mutant MNs. HSR activation correlates with the amount of cytoplasmic FUS mislocalization. While inhibition of SG formation, translation, or ISR does not influence survival of FUS ALS neurons, proteotoxicity that cannot be compensated with the activation of stress pathways is the main driver of neurodegeneration in early FUS ALS.
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•FUS ALS motor neurons show early activation of major stress response pathways•Blocking SG formation does not influence survival of neurons early in FUS ALS•Proteotoxicity is the main driver of cell death in the early stages of FUS ALS•Stress pathways preventing proteotoxicity are a rescue mechanism in early FUS ALS
Szewczyk et al. show that, in FUS ALS motor neurons, major stress response pathways are activated early, preventing proteotoxicity-driven cell death. Blocking integrated stress responses early in FUS ALS might not be beneficial. Similarly, preventing early stress granule formation is not protective in spite of signs of their aberrant dynamics.
Spinal muscular atrophy (SMA) is a genetic neuromuscular disease caused by mutations of the SMN1 gene. Deficient SMN protein causes irreversible degeneration of alpha motor neurons characterized by ...progressive muscle weakness and atrophy. Considering that SMA is a multi-systemic disorder and SMN protein was found to be expressed in cortical structures, the cognitive profile of adult patients with SMA has recently been of particular interest. With nusinersen, a novel, disease-modifying drug has been established, but its effects on neuropsychological functions have not been validated yet. Aim of this study was to investigate the cognitive profile of adult patients with SMA during treatment initiation with nusinersen and to reveal improvement or deterioration in cognitive performance.
This monocentric longitudinal study included 23 patients with SMA type 2 and 3. All patients were assessed with the Edinburgh Cognitive and Behavioral ALS Screen (ECAS) before and after 14 months of treatment initiation with nusinersen. Additionally, motor function was evaluated by Hammersmith Functional Motor Scale Expanded (HFMSE), Revised Upper Limb Module (RULM) and Amyotrophic Lateral Sclerosis Functional Rating Scale Revised (ALSFRS-R).
Of the treatment-naive patients, only three were below the age- and education-matched cut-off for cognitive impairment in the ECAS total score. Significant differences between SMA type 2 and 3 were only detected in the domain of Language. After 14 months of treatment, patients showed significant improvement of absolute scores in all three ALS-specific domains, in the non-ALS-specific domain of Memory, in both subscores and in the ECAS total score. No associations were detected between cognitive and functional outcome measures.
In some adult patients with SMA abnormal cognitive performance in ALS-specific functions of the ECAS was evident. However, the presented results suggest no clinically significant cognitive changes during the observed treatment period with nusinersen.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The oral, selective SMN2-splicing modifier risdiplam obtained European approval in March 2021 for the treatment of patients greater than or equal to 2 months old with a clinical diagnosis of ...5q-associated spinal muscular atrophy (SMA) 1/2/3 or with 1-4 SMN2 gene copies. For the preceding 12 months, this compassionate use program (CUP) made risdiplam available to patients with SMA1/2 in Germany who could not receive any approved SMA therapy. Between March 12, 2020 and March 30, 2021, 36 patients with SMA1 and 98 patients with SMA2 were enrolled, with 31 patients and 80 patients receiving greater than or equal to 1 risdiplam dose, respectively. The median (range) age was 10.5 (3-52) years in the SMA1 cohort, and 26.5 (3-60) years in the SMA2 cohort. 22.2% of patients with SMA1 and 48.0% with SMA2 were treatment-naïve. Most patients were not eligible/could not continue to receive nusinersen due to scoliosis/safety risk (SMA1: 75.0%; SMA2: 96.9%), risks associated with sedation (77.8%; 63.3%), or loss of efficacy (30.6%; 12.2%). Safety data were generally in line with the safety profile of risdiplam in ongoing clinical studies. Gastrointestinal disorders were the most common AEs. For patients with SMA1, 30 AEs were reported in 13 cases with 2 serious AEs in 1 patient. For SMA2, 100 AEs were documented in 31 case reports, including 8 serious AEs in 2 patients. We present the first real-world safety data of risdiplam in patients with SMA in Germany. Our observations indicated no new safety signals under real-world conditions. Real-world SMA1/2 populations comprise considerable numbers of patients who are not eligible for gene therapy and cannot tolerate or have failed nusinersen treatment. This medical need may be addressed by oral risdiplam.
Background:
There is limited information on neurochemical markers being used to support and monitor the affection of motoneurons in patients with spinal muscular atrophy (SMA). The objective of this ...study was to examine neurochemical markers in cerebrospinal fluid (CSF) under treatment with the antisense-oligonucleotide (ASO), nusinersen.
Methods:
We measured markers of axonal degeneration neurofilament light chain (NfL) and phosphorylated neurofilament heavy chain (pNfH) along with basic CSF parameters in 25 adolescent and adult SMA type 2 and 3 patients at baseline and after four intrathecal injections of nusinersen. Neurochemical markers were compared with controls. In addition, neurochemical markers in SMA patients were related to the Hammersmith Functional Rating Scale Expanded (HFMSE).
Results:
No significant difference in neurofilament (Nf) values was observed between SMA and control group, neither at baseline nor after four injections of nusinersen. NfL, protein and quotients of albumin (Qalb) increased slightly in SMA patients after the fourth injection. The slight increase of NfL could be related to the development of mild CSF flow change. No relations were observed between changes in Nf and HFMSE.
Conclusion:
We assume that Nf levels in CSF in these patients may result from slow disease progression in this stage of disease, pre-existing loss of motoneurons due to long disease duration besides affection of the LMN only. Therefore, we conclude that Nf levels in CSF do not seem useful as diagnostic and monitoring markers in adolescent and adult SMA type 2 and 3 patients.
Objective
To investigate diagnostic accuracy of a nerve ultrasound (US) protocol that is individualized to a patient’s clinical deficits for the differentiation of amyotrophic lateral sclerosis with ...predominant lower motoneuron disease (ALS/LMND) and multifocal motor neuropathy (MMN).
Methods
Single-center, prospective, examiner-blinded, diagnostic study in two cohorts. Cohort I (model development): Convenience sample of subjects with ALS/LMND or MMN according to revised El-Escorial or EFNS guidelines. Cohort II (model validation): Consecutively recruited treatment-naïve subjects with suspected diagnosis of ALS/LMND or MMN.
Cutoffs for 28 different US values were determined by Receiver Operating Curve (ROC) in cohort I. Area Under The Curve (AUC) of US was compared to nerve conduction studies (NCS). Diagnostic accuracy of US protocols, individualized according to clinical deficits, was compared to former rigid non-individualized protocols and to random examination site selection in cohort II.
Results
48 patients were recruited. In cohort I (28 patients), US had higher ROC AUCs than NCS, US 0.82 (0.12) (mean (standard deviation)), NCS (compound muscle action potential (CMAP) 0.60 (0.09),
p
< .001; two-sided
t
-test).
US models based on the nerve innervating the clinically most affected muscles had higher correct classification rates (CCRs, 93%) in cohort II than former rigid protocols (85% and 80%), or models with random measurement site selection (66% and 80%).
Conclusions
Clinically guided US protocols for differentiation of ALS/LMND from MMN increase diagnostic accuracy when compared to clinically unguided protocols. They also require less measurements sites to achieve this accuracy.
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