Molecular nucleation mechanisms and control strategies for crystal polymorph selection.

TDP-43 (43-kDa TAR DNA-binding domain protein) is a major constituent of ubiquitin-positive cytoplasmic aggregates present in neurons of patients with fronto-temporal lobular dementia and amyotrophic lateral sclerosis (ALS). The pathologic significance of TDP-43 aggregation is not known; however, dominant mutations in TDP-43 cause a subset of ALS cases, suggesting that misfolding and/or altered trafficking of TDP-43 is relevant to the disease process. Here, we show that the presenilin-binding protein ubiquilin 1 (UBQLN) plays a role in TDP-43 aggregation. TDP-43 interacted with UBQLN both in yeast and in vitro, and the carboxyl-terminal ubiquitin-associated domain of UBQLN was both necessary and sufficient for binding to polyubiquitylated forms of TDP-43. Overexpression of UBQLN recruited TDP-43 to detergent-resistant cytoplasmic aggregates that colocalized with the autophagosomal marker, LC3. UBQLN-dependent aggregation required the UBQLN UBA domain, was mediated by non-overlapping regions of TDP-43, and was abrogated by a mutation in UBQLN previously linked to Alzheimer disease. Four ALS-associated alleles of TDP-43 also coaggregated with UBQLN, and the extent of aggregation correlated with in vitro UBQLN binding affinity. Our findings suggest that UBQLN is a polyubiquitin-TDP-43 cochaperone that mediates the autophagosomal delivery and/or proteasome targeting of TDP-43 aggregates.

EAAT2 is a high affinity, Na+-dependent glutamate transporter with predominant astroglial localization. It accounts for the clearance of the bulk of glutamate released at central nervous system synapses and therefore has a crucial role in shaping glutamatergic neurotransmission and limiting excitotoxicity. Caspase-3 activation and impairment in expression and activity of EAAT2 are two distinct molecular mechanisms occurring in human amyotrophic lateral sclerosis (ALS) and in the transgenic rodent model of the disease. Excitotoxicity caused by down-regulation of EAAT2 is thought to be a contributing factor to motor neuron death in ALS. In this study, we report the novel evidence that caspase-3 cleaves EAAT2 at a unique site located in the cytosolic C-terminal domain of the transporter, a finding that links excitotoxicity and activation of caspase-3 as converging mechanisms in the pathogenesis of ALS. Caspase-3 cleavage of EAAT2 leads to a drastic and selective inhibition of this transporter. Heterologous expression of mutant SOD1 proteins linked to the familial form of ALS leads to inhibition of EAAT2 through a mechanism that largely involves activation of caspase-3 and cleavage of the transporter. In addition, we found evidence in spinal cord homogenates of mutant SOD1 ALS mice of a truncated form of EAAT2, likely deriving from caspase-3-mediated proteolytic cleavage, which appeared concurrently to the loss of EAAT2 immunoreactivity and to increased expression of activated caspase-3. Taken together, our findings suggest that caspase-3 cleavage of EAAT2 is one mechanism responsible for the impairment of glutamate uptake in mutant SOD1-linked ALS.

It has been suggested that cytokine-mediated inflammation plays a key role for the onset and/or development of neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic lateral sclerosis (ALS). However, clinical studies have yielded inconsistent results for the aberrant cytokine levels in circulation of patients with AD, PD, and ALS. Previous studies have used meta-analysis to address the inconsistent data for blood cytokine levels in the patients with AD, PD, and ALS. Here, we performed a systemic review of cerebrospinal fluid inflammatory cytokine data in patients with AD, PD and ALS, and sought to quantitatively summarize the CSF inflammatory cytokine data with a meta-analytical technique. The systematic search from Pubmed and Web of Science identified 71 articles with 2629 patients and 2049 controls for the meta-analysis. Random-effects meta-analysis demonstrated that CSF TGF-β, MCP-1, and YKL-40 levels were significantly elevated in AD patients when compared with controls. In addition, patients with PD had heightened levels of TGF-β1, IL-6, and IL-1β in CSF. Furthermore, G-CSF, IL-2, IL-15, IL-17, MCP-1, MIP-1α, TNF-α, and VEGF levels were significantly increased in patients with ALS as compared with controls. Taken together, these results not only strengthen the clinical evidence that neurodegenerative diseases are accompanied by the increased inflammatory response, but also reveal the unique inflammatory response profile in the central nervous system of patients with AD, PD and ALS. Given the robust associations between some cytokines and neurodegenerative diseases found in this meta-analysis, CSF inflammatory cytokines may be used as biomarkers for these diseases in the future.

Amyotrophic lateral sclerosis is a rapidly progressing fatal neurodegenerative disease characterized by the presence of protein inclusions within affected motor neurons. Endoplasmic reticulum stress leading to apoptosis was recently recognized to be an important process in the pathogenesis of sporadic human amyotrophic lateral sclerosis as well as in transgenic models of mutant superoxide dismutase 1-linked familial amyotrophic lateral sclerosis. Endoplasmic reticulum stress occurs early in disease, indicating a critical role in pathogenesis, and involves upregulation of an important endoplasmic reticulum chaperone, protein disulphide isomerase. We aimed to investigate the involvement of protein disulphide isomerase in endoplasmic reticulum stress induction, protein aggregation, inclusion formation and toxicity in amyotrophic lateral sclerosis. Motor neuron-like NSC-34 cell lines were transfected with superoxide dismutase 1 and protein disulphide isomerase encoding vectors and small interfering RNA, and examined by immunocytochemistry and immunoblotting. Expression of mutant superoxide dismutase 1 induced endoplasmic reticulum stress, predominantly in cells bearing mutant superoxide dismutase 1 inclusions but also in a proportion of cells expressing mutant superoxide dismutase 1 without visible inclusions. Over-expression of protein disulphide isomerase decreased mutant superoxide dismutase 1 aggregation, inclusion formation, endoplasmic reticulum stress induction and toxicity, whereas small interfering RNA targeting protein disulphide isomerase increased mutant superoxide dismutase 1 inclusion formation, indicating a protective role for protein disulphide isomerase against superoxide dismutase 1 misfolding. Aberrant modification of protein disulphide isomerase by S-nitrosylation of active site cysteine residues has previously been shown as an important process in neurodegeneration in Parkinson's and Alzheimer's disease brain tissue, but has not been described in amyotrophic lateral sclerosis. Using a biotin switch assay, we detected increased levels of S-nitrosylated protein disulphide isomerase in transgenic mutant superoxide dismutase 1 mouse and human sporadic amyotrophic lateral sclerosis spinal cord tissues. Hence, despite upregulation, protein disulphide isomerase is also functionally inactivated in amyotrophic lateral sclerosis, which may prevent its normal protective function and contribute to disease. We also found that a small molecule mimic of the protein disulphide isomerase active site, (+/-)-trans-1,2-bis(mercaptoacetamido)cyclohexane, protected against mutant superoxide dismutase 1 inclusion formation. These studies reveal that endoplasmic reticulum stress is important in the formation of mutant superoxide dismutase 1 inclusions, and protein disulphide isomerase has an important function in ameliorating mutant superoxide dismutase 1 aggregation and toxicity. Functional inhibition of protein disulphide isomerase by S-nitrosylation may contribute to pathophysiology in both mutant superoxide dismutase 1-linked disease and sporadic amyotrophic lateral sclerosis. Protein disulphide isomerase is therefore a novel potential therapeutic target in amyotrophic lateral sclerosis and (+/-)-trans-1,2-bis(mercaptoacetamido)cyclohexane and other molecular mimics of protein disulphide isomerase could be of benefit in amyotrophic lateral sclerosis and other neurodegenerative diseases related to protein misfolding.

Madness in the garden or worm in the apple?

Dear editors, Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease. It affects motor neurons in the brain and spinal cord resulting in bulbar palsy and respiratory failure. It also causes weakness of limbs. The disease usually progresses to fatal outcome within 2–4 years. Neural stem cell research for diagnosis and treatment of neurodegenerative disorders is highly promising. But more data are required to prove their efficacy. There is evidence regarding stem cell application in traumatic brain injury and other neurological disorders (Mouhieddine et al., 2014). Neurotrophic factors (NTFs) have been reported to increase the survival of motor neurons in ALS (Petrou et al., 2016). A culture-based method has been developed to promote the secretion of NTFs by mesenchymal stem cells (MSCs) (Petrou et al., 2016). NTFs have been shown to protect neurons in an animal model of neurodegenerative diseases (Chen et al., 2015). One phase I/II pilot trial (identifier {type:clinical-trial,attrs:{text:NCT00781872,term_id:NCT00781872}}NCT00781872) used intrathecal combined intravenous injections of bone marrow-derived MSCs in 34 patients with multiple sclerosis and ALS. Long-term (6–25 months) follow up observations did not show any severe adverse outcomes. MSCs transplantation was found to be a clinically feasible and relatively safe procedure (Karussis et al., 2010). Recently, in open-label proof-of-concept studies (Petrou et al., 2016), all patients enrolled between June 2011 and October 2014 were followed up from 3 months prior to transplantation to 6 months after transplantation. In six patients with early-stage ALS, MSC-secreting NTF (MSC-NTF) cells were intramuscularly administered in the phase I/II of the trial. Another six patients with more advanced diseases received intrathecal administration of MSC-NTF cells. In a phase IIa study, 14 patients who had early-stage ALS received a combined intramuscular and intrathecal transplantation of autologous MSC-NTF cells. The primary endpoints of the studies were tolerability and safety of this treatment. The secondary endpoint was the impact of such intervention on various clinical parameters, including the ALS Functional Rating Scale-Revised score and the respiratory function. In the phase I/II trial, the treatment was well tolerated by all included 12 patients over the study follow up period. A similar effect was shown in 14 patients in the phase IIa trial. The rate of deterioration in lung function and the ALS Functional Rating Scale-Revised score in the intrathecal (or intrathecal + intramuscular) group was found to be reduced (P < 0.04) in comparison with the pre-treatment phase. The result suggests the safety of intrathecal and intramuscular transplantation of MSC-NTF cells in patients with ALS (identifier {type:clinical-trial,attrs:{text:NCT01051882,term_id:NCT01051882}}NCT01051882 and {type:clinical-trial,attrs:{text:NCT01777646,term_id:NCT01777646}}NCT01777646) (Petrou et al., 2016). Bone marrow-derived MSCs have many advantages. For example, MSCs can be obtained safely from adult bone marrow; they can be cultured in vitro. Autologous MSCs can be administered safely without immunosuppressive therapy. Adult MSCs were shown to be associated with a low risk for induction of treatment-related malignant neoplasms (Karussis et al., 2010). We can focus on some other studies regarding the safety profile of stem cell transplant in the treatment of ALS. Animal studies have shown no clinically significant alteration of cytokine levels (involved in cell-mediated and humoral immunity) after MSC-NTF cell transplantation. Repeated injections of human MSC-NTF cells are found to be well tolerated in the studied animals (mice) (Gothelf et al., 2014). Pre-clinical and clinical trials have suggested that MSCs are safe and feasible as a therapeutic option. They are not immunogenic and have immunosuppressive features (Thomsen et al., 2014). Genetic stability and opportunity for cryopreservation for future use of MSCs are still in the research stage. Cryopreservation can preserve the biological behavior of MSCs including differentiation potential, growth capacity, and surface marker. Therefore, cryopreserved MSCs can be used safely in future (Wang et al., 2012). A meta-analysis of randomized controlled trials did not reveal any adverse effects of MSC transplants like infusion toxicity, any disorder of organ systems, infection, malignant transformation or fatal outcome (Dulamea, 2015). Another open-label phase I clinical trial showed the safety profile of two repeated intrathecal injections of autologous MSCs in ALS patients (Oh et al., 2015). Safety and Efficiency of Umbilical Cord-derived Mesenchymal Stem Cells (UC-MSC) in Patients with Alzheimer's Disease (SEMAD) [identifier {type:clinical-trial,attrs:{text:NCT01547689,term_id:NCT01547689}}NCT01547689] is an ongoing study, and hopefully, it will provide more definite results (https://clinicaltrials.gov/ct2/show/{type:clinical-trial,attrs:{text:NCT01547689,term_id:NCT01547689}}NCT01547689, last accessed on 27/03/2016). Before conclusion, we want to raise another issue about some biological markers of the efficacy of such therapy. The levels of vascular endothelial growth factor, angiogenin, and transforming growth factor-β were reported to be significantly higher in responders than in nonresponders after autologous MSC therapy in patients with ALS. The disease outcomes were evaluated by their scores on the revised ALS Functional Rating Scale (ALSFRS-R) (Kim et al., 2014). So this new treatment modality is hoped to be successful in ALS patients. More study results will enlighten us about it.

Psoriasis is genetically influenced and can be triggered by factors such as infections, stress, and lifestyle. Chronic plaque psoriasis, the most prevalent form, involves key roles for IL-17 and IL-23 in its pathogenesis. Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the degeneration of motor neurons, resulting in muscle weakness and atrophy. Currently, there is no cure for ALS, and treatment is symptomatic, aimed at improving quality of life. The combination of psoriasis and ALS is relatively rare. Although biologic agents have shown remarkable efficacy in the treatment of chronic plaque psoriasis, we have not found any case reports regarding the use of biologic agents for treating psoriasis accompanied by ALS. Our study presents a patient with severe plaque psoriasis and ALS who exhibited a positive response to Guselkumab, without worsening of ALS symptoms, suggesting a promising therapeutic strategy. This could provide a treatment option for patients with psoriasis combined with ALS.We conducted a comprehensive review of the literature on the comorbidity of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), and ALS, with plaque psoriasis. This review highlights the differential impact of treatment modalities. Specifically, we found that TNF-α inhibitors may have adverse effects in MS but could provide protective benefits in AD and PD. In ALS patients with psoriasis, IL-17A and IL-23 inhibitors, exemplified by Guselkumab, are suggested as a more suitable alternative due to their lower risk of worsening ALS symptoms.

The role of soluble intercellular adhesion molecules in neurodegenerative disorders

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of motor neurons characterized by muscle weakness, muscle twitching, and muscle wasting. ALS is regarded as the third-most frequent neurodegenerative disease, subsequent to Alzheimer's disease (AD) and Parkinson's disease (PD). The World Health Organization (WHO) in 2007 declared that prolonged use of statins may induce development of ALS-like syndrome and may increase ALS risk. Subsequently, different studies have implicated statins in the pathogenesis of ALS. In contrast, results from preclinical and clinical studies highlighted the protective role of statins against ALS neuropathology. Recently, meta-analyses and systematic reviews illustrated no association between long-term use of statins and ALS risk. These findings highlighted controversial points regarding the effects of statins on ALS pathogenesis and risk. The neuroprotective effects of statins against the development and progression of ALS may be mediated by regulating dyslipidemia and inflammatory changes. However, the mechanism for induction of ALS neuropathology by statins may be related to the dysregulation of liver X receptor signaling (LXR) signaling in the motor neurons and reduction of cholesterol, which has a neuroprotective effect against ALS neuropathology. Nevertheless, the exact role of statins on the pathogenesis of ALS was not fully elucidated. Therefore, this narrative review aims to discuss the role of statins in ALS neuropathology.

Background: We aimed to explore the genetic correlation and bidirectional causal relationships between low back pain (LBP) and three neurodegenerative diseases, Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS).Methods: Summary-level statistics were obtained from genome-wide association studies of LBP (n = 177,860), AD (n = 63,926), PD (n = 482,730), and ALS (n = 80,610). We implemented linkage disequilibrium score regression to calculate heritability estimates and genetic correlations. To investigate possible causal associations between LBP and three neurodegenerative diseases, we also conducted a bidirectional two-sample Mendelian randomization (MR) study. Inverse variance-weighted MR was employed as the primary method to generate overall estimates, whereas complementary approaches and sensitivity analyses were conducted to confirm the consistency and robustness of the findings.Results: There was no evidence of genetic correlations between LBP and AD (Rg = −0.033, p = 0.766). MR analyses did not support the causal effect of LBP on AD (OR = 1.031; 95% CI, 0.924–1.150; p = 0.590) or the effect of AD on LBP (OR = 0.963; 95% CI, 0.923–1.006; p = 0.090). Likewise, this study failed to identify genetic correlations between LBP and two other neurodegenerative diseases. MR results of the associations of LBP with PD and ALS, and the reverse associations, did not reach Bonferroni-corrected significance.Conclusion: The study did not support genetic correlations or causations between LBP and three common neurodegenerative diseases, AD, PD, and ALS in the European population.

Amyotrophic lateral sclerosis (ALS) is characterized by degeneration of upper and lower motor neurons. In some ALS patients, dementia or aphasia may be present (ALS-D). The dementia is most commonly a frontotemporal dementia (FTD), and many of these cases have ubiquitin-positive, tau-negative inclusions in neurons of the dentate gyrus and superficial layers of the frontal and temporal lobes. Identical inclusions have been found in cases presenting with FTD and have been designated motor neuron disease (MND)-inclusions. Cases of ALS-D without MND-inclusions have been reported to show neocortical gliosis, neuronal loss, and superficial spongiosis, but there have also been scattered case reports of ALS with Alzheimer's disease (AD). To determine whether AD pathology may play a role in the dementia or aphasia syndromes in ALS, we reviewed 30 cases of sporadic ALS diagnosed at the University of Pittsburgh Medical Center. A clinical history of ALS-D was found in 24.1% of the cases, of which 57% had MND-inclusions. Although the ALS-D cases with MND-inclusions typically had amyloid-beta (Abeta) plaques, there were no neuritic plaques. Three cases of ALS-D had no MND-inclusions, and two of these fulfilled pathological criteria for AD. One ALS-D case showed severe amyloid angiopathy but no neuritic plaques or MND-inclusions. MND-inclusions were not found in any ALS case without dementia; however, four patients without dementia or aphasia showed moderate or frequent numbers of neuritic plaques. In conclusion, we found that approximately 30% of ALS cases with dementia have AD and that some ALS cases without frank dementia have significant AD pathology.

AXL, a receptor tyrosine kinase expressed in neurons and glial cells, involved in neuronal survival, myelination, and regulation of immune responses, can undergo shedding due to the activation of metalloproteases in neuroinflammatory conditions. Indeed, CSF and serum levels of soluble AXL (sAXL) have been correlated with neurodegeneration and cognitive decline in Alzheimer’s disease (AD). Based on these observations, we explored whether sAXL is implicated in amyotrophic lateral sclerosis (ALS). sAXL levels were measured in biofluids (CSF and serum) from two biorepositories, totalling 107 ALS patients, 76 healthy controls, 25 AD patients, 22 patients with multiple sclerosis and 51 patients with ALS disease mimicking disorders (i.e. patients that displayed symptoms resembling ALS, in whom eventually ALS was excluded after a thorough clinical examination). Gender and age were considered as covariate in the statistical analyses. Our results provide the first evidence of sAXL alterations in the CSF and serum of ALS patients at diagnosis and demonstrate a significant association between CSF sAXL levels and disease progression, as well as its prognostic value in ALS. While these observations require validation through multicentre studies, they suggest the involvement of the AXL pathway in ALS pathology and pave the way for leveraging CSF sAXL levels as a biomarker to aid ALS disease stratification.

Fitting TDP-43 into the APOE ε4 and neurodegeneration story

Metallothionein (MT) is a small molecular and multi-functional protein containing four atoms of copper (Cu) and three atoms of zinc (Zn) per molecule. It was isolated from the horse kidney in 1957 and half a century has passed since then. Although MT was found to work as a modulator of Zn and induce anti-oxidant reaction, the precise functions and its functional mechanisms remain to be elucidated. Over the years, a new isoform of MT, MT-III (also called growth inhibitory factor (GIF)), has been found in the brain, which was markedly diminished in the brain of Alzheimer's disease (AD). Many new findings on MT have been discovered in neurodegenerative diseases other than AD such as amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), prion disease, brain trauma, brain ischemia, and psychiatric diseases. In ALS in particular, MTs were markedly diminished in the spinal cord of patients with ALS. Initially, MT, which easily binds to cadmium (Cd) and copper (Cu), was considered to be toxic to our bodies. Molecular biological technologies enabled the production of recombinant MT saturated with zinc (Zn). MT has a high potential for the treatment of neurodegenerative diseases such as ALS, AD, and PD owing to its various functions including anti-oxidant properties and modulators not only for Zn but for Cu in the extra- and intracellular spaces. On the other hand, there are still various problems on MT to be elucidated in detail, including their binding proteins and functional mechanisms.

While cognitive deficits are increasingly recognized as common symptoms in amyotrophic lateral sclerosis (ALS), the underlying histopathologic basis for this is not known, nor has the relevance of neuroinflammatory mechanisms and microglial activation to cognitive impairment (CI) in ALS been systematically analyzed. Staining for neurodegenerative disease pathology, TDP-43, and microglial activation markers (CD68, Iba1) was performed in 102 autopsy cases of ALS, and neuropathology data were related to clinical and neuropsychological measures. ALS with dementia (ALS-D) and ALS with impaired executive function (ALS-Ex) patients showed significant microglial activation in middle frontal and superior or middle temporal (SMT) gyrus regions, as well as significant neuronal loss and TDP-43 pathology in these regions. Microglial activation and TDP-43 pathology in middle frontal and superior or middle temporal regions were highly correlated with measures of executive impairment, but not with the MMSE. In contrast, only one ALS-D patient showed moderate Alzheimer's disease (AD) pathology. Tau and Aβ pathology increased with age. A lower MMSE score correlated with tau pathology in hippocampus and SMT gyrus, and with Aβ pathology in limbic and most cortical regions. Tau and Aβ pathology did not correlate with executive measures. We conclude that microglial activation and TDP-43 pathology in frontotemporal areas are determinants of FTLD spectrum dementia in ALS and correlate with neuropsychological measures of executive dysfunction. In contrast, AD pathology in ALS is primarily related to increasing age and associated with a poorer performance on the MMSE.