Tino Prell

The ER mitochondria calcium cycle and ER stress response as therapeutic targets in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive loss of upper and lower motor neurons. Although the etiology remains unclear, disturbances in calcium homoeostasis and protein folding are essential features of neurodegeneration in this disorder. Here, we review recent research findings on the interaction between endoplasmic reticulum (ER) and mitochondria, and its effect on calcium signaling and oxidative stress. We further provide insights into studies, providing evidence that structures of the ER mitochondria calcium cycle serve as a promising targets for therapeutic approaches for treatment of ALS.

Longitudinal diffusion tensor imaging in amyotrophic lateral sclerosis

BackgroundAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder, caused by progressive loss of motor neurons. Changes are widespread in the subcortical white matter in ALS. Diffusion tensor imaging (DTI) detects pathological changes in white matter fibres in vivo, based on alterations in the degree (diffusivity, ADC) and directedness (fractional anisotropy, FA) of proton movement.Methods24 patients with ALS and 24 age-matched controls received 1.5T DTI. FA and ADC were analyzed using statistical parametric mapping. In 15 of the 24 ALS patients, a second DTI was obtained after 6 months.ResultsDecreased FA in the corticospinal tract (CST) and frontal areas confirm existing results. With a direct comparison of baseline and follow-up dataset, the progression of upper motor neuron degeneration, reflected in FA decrease, could be captured along the CST and in frontal areas. The involvement of cerebellum in the pathology of ALS, as suspected from functional MRI studies, could be confirmed by a reduced FA (culmen, declive). These structural changes correlated well with disease duration, ALSFRS-R, and physical and executive functions.ConclusionDTI detects changes that are regarded as prominent features of ALS and thus, shows promise in its function as a biomarker. Using the technique herein, we could demonstrate DTI changes at follow-up which correlated well with clinical progression.

Muscle ultrasonography as an additional diagnostic tool for the diagnosis of amyotrophic lateral sclerosis.

OBJECTIVE We aimed to determine the utility of muscle ultrasonography (MUS) in addition to electromyography (EMG) in the diagnosis of amyotrophic lateral sclerosis (ALS). METHODS In all, 60 patients with ALS and 20 with other neuromuscular disorders underwent MUS and EMG. In addition, 30 healthy controls underwent only MUS. Occurrence of fasciculations and fibrillations was evaluated. Ultrasonic echogenicity was graded semiquantitatively. RESULTS The incidence of fasciculations was significantly higher in patients undergoing MUS than in those undergoing EMG (p<0.05), even in muscles of full strength (p<0.001). However, EMG was more sensitive in detecting fibrillations (p<0.05). MUS had an overall higher sensitivity in detecting spontaneous activity in the tongue (p<0.05). Patients with ALS showed significantly increased muscle echo intensity (EI) compared to patients who were initially suspected as having ALS and normal controls (p<0.05), irrespective of the clinical or electrophysiological status. CONCLUSION Our results showed that the sensitivity and specificity of MUS in diagnosing ALS was almost equivalent to those of EMG, using the Awaji criteria. Combination of MUS and EMG enhances the diagnostic accuracy compared to EMG alone (p<0.05). SIGNIFICANCE The combination of EMG and MUS can be used to evaluate the lower motor neuron affection by reducing the use of the often painful and uncomfortable EMG examinations but without decreasing the diagnostic sensitivity and specificity.

The involvement of the cerebellum in amyotrophic lateral sclerosis

Abstract Amyotrophic lateral sclerosis is a multisystemic neurodegenerative disease in which degenerative processes are not exclusively restricted to the upper and lower motor neurons. Herein, imaging and neuropathological evidence for involvement of the cerebellum, which to date is not thought to be involved in ALS, is reviewed. Evidence for involvement of the cerebellum in ALS comes from several neuropathological studies. Especially ubiquitinated forms of TDP-43 and ubiquitinated p62-positive inclusions were frequently observed. The widely used transgenic SOD1-G93A ALS mice model showed prominent cerebellar immunostaining of pERK and alterations of tau expression. Studies using advanced MRI techniques demonstrated that several cerebral areas, including the cerebellum, were recruited in order to compensate for functional motor decline. Functional MRI, voxel based morphometry, and diffusion-tensor imaging showed these cerebellar alterations as being of functional and structural nature.

Tics are caused by alterations in prefrontal areas, thalamus and putamen, while changes in the cingulate gyrus reflect secondary compensatory mechanisms

BackgroundDespite strong evidence that the pathophysiology of Tourette syndrome (TS) involves structural and functional disturbances of the basal ganglia and cortical frontal areas, findings from in vivo imaging studies have provided conflicting results. In this study we used whole brain diffusion tensor imaging (DTI) to investigate the microstructural integrity of white matter pathways and brain tissue in 19 unmedicated, adult, male patients with TS “only” (without comorbid psychiatric disorders) and 20 age- and sex-matched control subjects.ResultsCompared to normal controls, TS patients showed a decrease in the fractional anisotropy index (FA) bilaterally in the medial frontal gyrus, the pars opercularis of the left inferior frontal gyrus, the middle occipital gyrus, the right cingulate gyrus, and the medial premotor cortex. Increased apparent diffusion coefficient (ADC) maps were detected in the left cingulate gyrus, prefrontal areas, left precentral gyrus, and left putamen. There was a negative correlation between tic severity and FA values in the left superior frontal gyrus, medial frontal gyrus bilaterally, cingulate gyrus bilaterally, and ventral posterior lateral nucleus of the right thalamus, and a positive correlation in the body of the corpus callosum, left thalamus, right superior temporal gyrus, and left parahippocampal gyrus. There was also a positive correlation between regional ADC values and tic severity in the left cingulate gyrus, putamen bilaterally, medial frontal gyrus bilaterally, left precentral gyrus, and ventral anterior nucleus of the left thalamus.ConclusionsOur results confirm prior studies suggesting that tics are caused by alterations in prefrontal areas, thalamus and putamen, while changes in the cingulate gyrus seem to reflect secondary compensatory mechanisms. Due to the study design, influences from comorbidities, gender, medication and age can be excluded.

Calcium-dependent protein folding in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a neurodegenerative disease characterized by a progressive loss of motor neurons. Although the etiology remains unclear, disturbances in Ca2+ homoeostasis and protein folding are essential features of neurodegeneration. The correct folding of proteins is managed by folding proteins, which are regulated by Ca2+ levels. Therefore, Ca(2+)-sensitive folding proteins represent an important link between disturbed Ca2+ handling and protein misfolding in amyotrophic lateral sclerosis. In the first part of this review, we focus on Ca2+ handling in the endoplasmic reticulum and mitochondria in terms of their roles in protein misfolding. In the second part, we draw attention to the main Ca(2+)-sensitive folding proteins that play a role in motor neuron degeneration such as calreticulin and calnexin, which are involved in the folding of glycosylated proteins. In addition, calmodulin and the Ca2+/calmodulin-dependent protein kinase are discussed as one correlation to oxidative stress. The heat shock protein endoplasmin is associated with the anti-apoptotic insulin-like growth factor pathway that is altered in amyotrophic lateral sclerosis. Grp78, which influences Ca2+ homeostasis in the intraluminal endoplasmic reticulum is upregulated in mice models and amyotrophic lateral sclerosis patients and constitutes a core component of the unfolded protein response. Lastly, the protein disulfide isomerase family is responsible for mediating oxidative protein folding in the endoplasmic reticulum.

Endoplasmic reticulum stress is accompanied by activation of NF-κB in amyotrophic lateral sclerosis

BACKGROUND Recent studies have indicated that endoplasmic reticulum (ER) stress is involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). ER stress occurs when the ER-mitochondria calcium cycle is disturbed and misfolded proteins accumulate in the ER. To cope with ER stress, cells activate the unfolded protein response (UPR). Accumulating evidence from non-neuronal cell models suggests that there is extensive cross-talk between the UPR and the NF-κB pathway. METHODS Here we investigated the expression of NF-κB and the main UPR markers X-box binding protein 1 (XBP1), basic leucine-zipper transcription factor 6 (ATF6) and phosphorylated eukaryotic initiation factor-2α (p-eIF2) in mutated SOD1(G93A) cell models of ALS, as well as their modulation by lipopolysaccharide and ER-stressing (tunicamycin) stimuli. RESULTS Expression of NF-κB was enhanced in the presence of SOD1(G93A). Lipopolysaccharide did not induce the UPR in NSC34 cells and motor neurons in a mixed motor neuron-glia coculture system. The induction of the UPR by tunicamycin was accompanied by activation of NF-κB in NSC34 cells and motor neurons. CONCLUSION Our data linked two important pathogenic mechanisms of ALS, ER stress and NF-κB signalling, in motor neurons.

Overexpression of human mutated G93A SOD1 changes dynamics of the ER mitochondria calcium cycle specifically in mouse embryonic motor neurons

Motor neurons vulnerable to the rapidly progressive deadly neurodegenerative disease amyotrophic lateral sclerosis (ALS) inherently express low amounts of calcium binding proteins (CaBP), likely to allow physiological motor neuron firing frequency modulation. At the same time motor neurons are susceptible to AMPA receptor mediated excitotoxicity and internal calcium deregulation which is not fully understood. We analysed ER mitochondria calcium cycle (ERMCC) dynamics with subsecond resolution in G93A hSOD1 overexpressing motor neurons as a model of ALS using fluorescent calcium imaging. When comparing vulnerable motor neurons and non-motor neurons from G93A hSOD1 mice and their non-transgenic littermates, we found a decelerated cytosolic calcium clearance in the presence of G93A hSOD1. While both non-transgenic as well as G93A hSOD1 motor neurons displayed large mitochondrial calcium uptake by the mitochondrial uniporter (mUP), the mitochondrial calcium extrusion system was altered in the presence of G93A hSOD1. In addition, ER calcium uptake by the sarco-/endoplasmic reticulum ATPase (SERCA) was increased in G93A hSOD1 motor neurons. In survival assays, blocking the mitochondrial sodium calcium exchanger (mNCE) by CGP37157 as well as inhibiting SERCA by cyclopiazonic acid showed protective effects against kainate induced excitotoxicity. Thus, our study shows for the first time that the functional consequence of G93A hSOD1 overexpression in intact motor neurons is indeed a disturbance of the ER mitochondria calcium cycle, and identified two promising targets for therapeutic intervention in the pathology of ALS.

Neurofilament markers for ALS correlate with extent of upper and lower motor neuron disease

Objective: To determine the diagnostic performance and prognostic value of phosphorylated neurofilament heavy chain (pNfH) and neurofilament light chain (NfL) in CSF as possible biomarkers for amyotrophic lateral sclerosis (ALS) at the diagnostic phase. Methods: We measured CSF pNfH and NfL concentrations in 220 patients with ALS, 316 neurologic disease controls (DC), and 50 genuine disease mimics (DM) to determine and assess the accuracy of the diagnostic cutoff value for pNfH and NfL and to correlate with other clinical parameters. Results: pNfH was most specific for motor neuron disease (specificity 88.2% [confidence interval (CI) 83.0%–92.3%]). pNfH had the best performance to differentially diagnose patients with ALS from DM with a sensitivity of 90.7% (CI 84.9%–94.8%), a specificity of 88.0% (CI 75.7%–95.5%) and a likelihood ratio of 7.6 (CI 3.6–16.0) at a cutoff of 768 pg/mL. CSF pNfH and NfL levels were significantly lower in slow disease progressors, however, with a poor prognostic performance with respect to the disease progression rate. CSF pNfH and NfL levels increased significantly as function of the number of regions with both upper and lower motor involvement. Conclusions: In particular, CSF pNfH concentrations show an added value as diagnostic biomarkers for ALS, whereas the prognostic value of pNfH and NfL warrants further investigation. Both pNfH and NfL correlated with the extent of motor neuron degeneration. Classification of evidence: This study provides Class II evidence that elevated concentrations of CSF pNfH and NfL can accurately identify patients with ALS.

Diffusion tensor imaging patterns differ in bulbar and limb onset amyotrophic lateral sclerosis

BACKGROUND Amyotrophic lateral sclerosis (ALS) is characterized by pronounced clinical heterogeneity in terms of onset and disease progression. Widespread changes in white matter fibres could be observed by diffusion tensor imaging (DTI), which detects alterations in the degree (diffusivity, ADC) and directedness (fractional anisotropy, FA) of proton movement. The aim of the current study was to determine whether different ALS onset types were reflected in different DTI brain patterns. METHODS Seventeen patients with a diagnosis of ALS (6 bulbar, 11 limb onset) and seventeen age-matched controls received 1.5T DTI, where FA and ADC were analyzed using statistical parametric mapping. RESULTS In ALS patients, an increased diffusivity in the white matter was found below the precentral gyrus and along the corticospinal tract (CST) right into the internal capsule. The FA was decreased in the posterior limb of internal capsule and in the subcortical white matter in the precentral gyrus. In bulbar onset increased diffusivity was found in the CST, whilst in limb onset, frontal subcortical areas displayed an increased diffusivity. CONCLUSION DTI changes can be regarded as prominent features in ALS. Herein we were able to demonstrate discriminating brain DTI patterns due to bulbar or limb onset.