Insufficient evidence exists to guide the long-term pharmacological management of Huntington’s disease (HD) although most current interventions rely on symptomatic management. The effect of many frontline treatments on potential endpoints for HD clinical trials remains unknown. Our objective was to investigate how therapies widely used to manage HD affect the symptom for which they are prescribed and other endpoints using data from TRACK-HD. We used longitudinal models to estimate effects of medication use on performance on tests of motor, cognitive and neuropsychiatric function using data from 123 TRACK-HD stage 1/2 participants across four study visits. Adjustment for confounding by prior medication use, prior clinical performance, concomitant use of other medications, and baseline variables (sex, disease group, age, CAG, study site, education) enabled a closer-to-causal interpretation of the associations. Adjusting for baseline variables only, medication use was typically associated with worse clinical performance, reflecting greater medication use in more advanced patients. After additional adjustment for longitudinal confounders such “inverse” associations were generally eliminated and in the expected directions: participants taking neuroleptics tended to have better motor performance, improved affect and poorer cognitive performance, and those taking SSRI/SNRIs had less apathy, less affect and better total behaviour scores. However, we uncovered few statistically significant associations. Limitations include sample size and unmeasured confounding. In conclusion, adjustment for confounding by prior measurements largely eliminated associations between medication use and poorer clinical performance from simple analyses. However, there was little convincing evidence of causal effects of medication on clinical performance and larger cohorts or trials are needed.
Correction The author order is incorrect. The correct order of the authors is: Lu Z, Barrows L, Fox J. Reference Fox J, Lu Z, Barrows L. Thiol-disulfide Oxidoreductases TRX1 and TMX3 Decrease Neuronal Atrophy in a Lentiviral Mouse Model of Huntington’s Disease. PLOS Currents Huntington Disease. 2015 Nov 6 . Edition 1. doi: 10.1371/currents.hd.b966ec2eca8e2d89d2bb4d020be4351e.
Huntington disease (HD) is caused by the CAG (Q) expansion in exon 1 of the IT15 gene encoding a polyglutamine (poly-Q) stretch of the Huntingtin protein (Htt). In the wild type protein, the repeats specify a stretch of up 34 Q in the N-terminal portion of Htt. In the pathological protein (mHtt) the poly-Q tract is longer. Proteolytic cleavage of the protein liberates an N-terminal fragment containing the expanded poly-Q tract becomes harmful to cells, in particular to striatal neurons. The fragments cause the transcriptional dysfunction of genes that are essential for neuronal survival. Htt, however, could also have non-transcriptional effects, e.g. it could directly alter Ca2+ homeostasis and/or mitochondrial morphology and function. Ca2+ dyshomeostasis and mitochondrial dysfunction are considered important in the molecular aetiology of the disease. Here we have analyzed the effect of the overexpression of Htt fragments (18Q, wild type form, wtHtt and 150Q mutated form, mHtt) on Ca2+ homeostasis in striatal neuronal precursor cells (Q7/7). We have found that the transient overexpression of the Htt fragments increases Ca2+ transients in the mitochondria of cells stimulated with Ca2+-mobilizing agonists. The bulk Ca2+ transients in the cytosol were unaffected, but the Ca2+ content of the endoplasmic reticulum was significantly decreased in the case of mHtt expression. To rule out possible transcriptional effects due to the presence of mHtt, we have measured the mRNA level of a subunit of the respiratory chain complex II, whose expression is commonly altered in many HD models. No effects on the mRNA level was found suggesting that, in our experimental condition, transcriptional action of Htt is not occurring and that the effects on Ca2+ homeostasis were dependent to non-transcriptional mechanisms.
Huntington’s disease (HD) is caused by a trinucleotide CAG repeat in the huntingtin gene (HTT) that results in expression of a polyglutamine-expanded mutant huntingtin protein (mHTT). N-terminal fragments of mHTT accumulate in brain neurons and glia as soluble monomeric and oligomeric species as well as insoluble protein aggregates and drive the disease process. Decreasing mHTT levels in brain provides protection and reversal of disease signs in HD mice making mHTT a prime target for disease modification. There is evidence for aberrant thiol oxidation within mHTT and other proteins in HD models. Based on this, we hypothesized that a specific thiol-disulfide oxidoreductase exists that decreases mHTT levels in cells and provides protection in HD mice. We undertook an in-vitro genetic screen of key thiol-disulfide oxidoreductases then completed secondary screens to identify those with mHTT decreasing properties. Our in-vitro experiments identified thioredoxin 1 and thioredoxin-related transmembrane protein 3 as proteins that decrease soluble mHTT levels in cultured cells. Using a lentiviral mouse model of HD we tested the effect of these proteins in striatum. Both proteins decreased mHTT-induced striatal neuronal atrophy. Findings provide evidence for a role of dysregulated protein-thiol homeostasis in the pathogenesis of HD.
Background: Recently a profound depletion of cystathionine γ-lyase (CSE), the principal enzyme involved in the generation of cysteine from cystathionine, was shown in Huntington disease (HD) patients and several transgenic HD mouse models. We therefore hypothesized that blood and urine cystathionine levels may be increased in HD patients and that this increase might correlate with disease progression. Methods: We measured concentrations of cystathionine as well as 22 other amino acids in fasting plasma and 24-h urine samples of nine early-stage HD patients and nine age, sex, and body mass index matched controls. Results: There were no significant differences in the plasma or urine concentrations of cystathionine or any other amino acid between HD patients and controls. Conclusion: We found no evidence for changes in plasma or urine concentrations of cystathionine in early-stage HD patients. Therefore, cystathionine levels are unlikely to be useful as a state biomarker in HD.
Background: We investigated the use of a simple novel nut and bolt task in premanifest and manifest Huntington’s disease (HD) patients to detect and quantify motor impairments at all stages of the disease.
Methods: Premanifest HD (n=24), manifest HD (n=27) and control (n=32) participants were asked to screw a nut onto a bolt in one direction, using three different sized bolts with their left and right hand in turn.
Results: We identified some impairments at all stages of HD and in the premanifest individuals, deficits in the non-dominant hand correlated with disease burden scores.
Conclusion: This simple, cheap motor task was able to detect motor impairments in both premanifest and manifest HD and as such might be a useful quantifiable measure of motor function for use in clinical studies.
Weight loss is an important complication of Huntington’s disease (HD), however the mechanism for weight loss in HD is not entirely understood. Mutant huntingtin is expressed in the gastrointestinal (GI) tract and, in HD mice, mutant huntingtin inclusions are found within the enteric nervous system along the GI tract. A reduction of neuropeptides, decreased mucosal thickness and villus length, as well as gut motility impairment, have also been shown in HD mice. We therefore set out to study gastric mucosa of patients with HD, looking for abnormalities of mucosal cells using immunohistochemistry. In order to investigate possible histological differences related to gastric acid production, we evaluated the cell density of acid producing parietal cells, as well as gastrin producing cells (the endocrine cell controlling parietal cell function). In addition, we looked at chief cells and somatostatin-containing cells. In gastric mucosa from HD subjects, compared to control subject biopsies, a reduced expression of gastrin (a marker of G cells) was found. This is in line with previous HD mouse studies showing reduction of GI tract neuropeptides.
Huntington’s disease (HD) is a neurodegenerative illness, where selective neuronal loss in the brain caused by expression of mutant huntingtin protein leads to motor dysfunction and cognitive decline in addition to peripheral metabolic changes. In this study we confirm our previous observation of impairment of lactate-based hepatic gluconeogenesis in the transgenic HD mouse model R6/2 and determine that the defect manifests very early and progresses in severity with disease development, indicating a potential to explore this defect in a biomarker context. Moreover, R6/2 animals displayed lower blood glucose levels during prolonged fasting compared to wild type animals.
Objective: To assess effects of a two year intensive, multidisciplinary rehabilitation program for patients with early- to mid-stage Huntington’s disease.
Design: A prospective intervention study.
Setting: One inpatient rehabilitation center in Norway.
Subjects: 10 patients, with early- to mid-stage Huntington’s disease.
Interventions: A two year rehabilitation program, consisting of six admissions of three weeks each, and two evaluation stays approximately three months after the third and sixth rehabilitation admission. The program focused on physical exercise, social activities, and group/teaching sessions.
Main outcome measures: Standard measures for motor function, including gait and balance, cognitive function, including MMSE and UHDRS cognitive assessment, anxiety and depression, activities of daily living (ADL), health related quality of life (QoL) and Body Mass Index (BMI).
Results: Six out of ten patients completed the full program. Slight, but non-significant, decline was observed for gait and balance from baseline to the evaluation stay after two years. Non-significant improvements were observed in physical QoL, anxiety and depression, and BMI. ADL-function remained stable with no significant decline. None of the cognitive measures showed a significant decline. An analysis of individual cases revealed that four out of the six participants who completed the program sustained or improved their motor function, while motor function declined in two participants. All the six patients who completed the program reported improved or stable QoL throughout the study period.
Conclusion: Our findings suggest that participation in an intensive rehabilitation program is well tolerated among motivated patients with early to mid-stage HD. The findings should be interpreted with caution due to the small sample size in this study.
Huntington’s disease (HD), an autosomal dominant neurodegenerative syndrome, has a world-wide distribution. An estimated 2.5-10/100,000 people of European ancestry are affected with HD, while the Asian populations have lower prevalence (0.6-3.8/100,000). The epidemiology of HD is not well described in India, and the distribution of the pathogenic CAG expansion, and the associated haplotype, in this population needs to be better understood. This study demonstrates a distribution of CAG repeats, at the HTT locus, comparable to the European population in both normal and HD affected chromosomes. Further, we provide an evidence for similarity of the HD halpotype in Indian sample to the European HD haplogroup.