Psychiatric and cognitive symptoms in Huntington's disease are modified by polymorphisms in catecholamine regulating enzyme genes

A Comprehensive Review on Beneficial Effects of Catechins on Secondary Mitochondrial Diseases

Mitochondria are the main sites for oxidative phosphorylation and synthesis of adenosine triphosphate in cells, and are known as cellular power factories. The phrase "secondary mitochondrial diseases" essentially refers to any abnormal mitochondrial function other than primary mitochondrial diseases, i.e., the process caused by the genes encoding the electron transport chain (ETC) proteins directly or impacting the production of the machinery needed for ETC. Mitochondrial diseases can cause adenosine triphosphate (ATP) synthesis disorder, an increase in oxygen free radicals, and intracellular redox imbalance. It can also induce apoptosis and, eventually, multi-system damage, which leads to neurodegenerative disease. The catechin compounds rich in tea have attracted much attention due to their effective antioxidant activity. Catechins, especially acetylated catechins such as epicatechin gallate (ECG) and epigallocatechin gallate (EGCG), are able to protect mitochondria from reactive oxygen species. This review focuses on the role of catechins in regulating cell homeostasis, in which catechins act as a free radical scavenger and metal ion chelator, their protective mechanism on mitochondria, and the protective effect of catechins on mitochondrial deoxyribonucleic acid (DNA). This review highlights catechins and their effects on mitochondrial functional metabolic networks: regulating mitochondrial function and biogenesis, improving insulin resistance, regulating intracellular calcium homeostasis, and regulating epigenetic processes. Finally, the indirect beneficial effects of catechins on mitochondrial diseases are also illustrated by the warburg and the apoptosis effect. Some possible mechanisms are shown graphically. In addition, the bioavailability of catechins and peracetylated-catechins, free radical scavenging activity, mitochondrial activation ability of the high-molecular-weight polyphenol, and the mitochondrial activation factor were also discussed.

Uncovering the mechanism of the Shenzhi Jiannao formula against vascular dementia using a combined network pharmacology approach and molecular biology

BACKGROUND

Shenzhi Jiannao formula (SZJNF) is a herbal prescription which is used for detoxification, dredging collaterals, and activating blood circulation and Qi flow in traditional Chinese medicine. SZJNF is a clinical effective prescription for the treatment of vascular dementia (VD) first formulated based on the classical theory of traditional Chinese medicine, but its anti-VD mechanism remains ambiguous.

PURPOSE

The aim of this study was to elucidate the multi-target mechanisms of SZJNF against VD using a network pharmacology approach and verify its effects through biological experiments.

STUDY DESIGN AND METHODS

We utilized network pharmacology-based prediction and molecular docking techniques to uncover the potential micro-mechanism of SZJNF against VD. We identified active components and potential targets, and performed network analysis, functional annotation, and pathway enrichment analysis. Subsequently, glutamate-induced PC12 cells and VD rats were used to verify the molecular mechanisms of SZJNF.

RESULTS

Seventeen active compounds were identified in SZJNF rat plasma; moreover, 773 predicted targets and 1544 VD-related targets were found. Various networks, including the PPI, herb-compound-target, and compound-target-pathway network were constructed. A total of 188 shared targets were identified by network topological analysis, which were closely associated to the anti-VD effects of SZJNF. They were also enriched in various biological processes through hypoxia reaction, promotion of cell proliferation, inhibition of apoptosis, neuroactive ligand-receptor interaction, and calcium signaling pathway, as evaluated by the analysis of advanced functions and pathways. SZJNF components docked well with the key targets. Treatment with SZJNF promoted cell proliferation, ameliorated apoptosis and oxidative stress injury, and improved neurological and cognitive abilities.

CONCLUSION

This study comprehensively demonstrated the multi-target mechanisms of SZJNF in VD using network pharmacology and molecular biology experiments. This provides evidence for further mechanistic studies and for the development of SZJNF as a potential treatment for patients with VD.

Endophenotypical drift in Huntington's disease: a 5-year follow-up study

BACKGROUND

Huntington's disease (HD) is clinically characterized by progressing motor, cognitive and psychiatric symptoms presenting as varying phenotypes within these three major symptom domains. The disease is caused by an expanded CAG repeat tract in the huntingtin gene and the pathomechanism leading to these endophenotypes is assumed to be neurodegenerative. In 2012/2013 we recruited 107 HD gene expansion carriers (HDGECs) and examined the frequency of the three cardinal symptoms and in 2017/2018 we followed up 74 HDGECs from the same cohort to describe the symptom trajectories and individual drift between the endophenotypes as well as potential predictors of progression and remission.

RESULTS

We found higher age to reduce the probability of improving on psychiatric symptoms; increasing disease burden score ((CAG-35.5) * age) to increase the risk of developing cognitive impairment; increasing disease burden score and shorter education to increase the risk of motor onset while lower disease burden score and higher Mini Mental State Examination increased the probability of remaining asymptomatic. We found 23.5% (N = 8) to improve from their psychiatric symptoms.

CONCLUSIONS

There is no clear pattern in the development of or drift between endophenotypes. In contrast to motor and cognitive symptoms we find that psychiatric symptoms may resolve and thereby not entirely be caused by neurodegeneration. The probability of improving from psychiatric symptoms is higher in younger age and advocates for a potential importance of early treatment.

Astrocyte molecular signatures in Huntington's disease

Astrocytes are implicated in neurodegenerative disorders and may contribute to striatal neuron loss or dysfunction in Huntington's disease (HD). Here, we assessed striatal astrocyte gene and protein signatures in two HD mouse models at three stages and compared our results to human HD data at four clinical grades and to mice exhibiting polyglutamine length-dependent pathology. We found disease-model and stage-specific alterations and discovered a core disease-associated astrocyte molecular signature comprising 62 genes that were conserved between mice and humans. Our results show little evidence of neurotoxic A1 astrocytes that have been proposed to be causal for neuronal death in neurodegenerative disorders such as HD. Furthermore, 61 of the 62-core gene expression changes within astrocytes were reversed in a HD mouse model by lowering astrocyte mutant huntingtin protein (mHTT) expression using zinc finger protein (ZFP) transcriptional repressors. Our findings indicate that HD astrocytes progressively lose essential normal functions, some of which can be remedied by lowering mHTT. The data have implications for neurodegenerative disease rescue and repair strategies as well as specific therapeutic relevance for mHTT reduction and contribute to a better understanding of fundamental astrocyte biology and its contributions to disease.

Glial evolution as a determinant of human behavior and its disorders

Astroglial complexity and pleomorphism have increased significantly with hominid evolution. This suggests a potential association between glial evolution and the development of human cognition, as well as between glial evolution and the advent of human-selective neurodegenerative and neuropsychiatric disorders.

Disease-modifying effects of ganglioside GM1 in Huntington's disease models

Huntington's disease (HD) is a progressive neurodegenerative disorder characterized by motor, cognitive and psychiatric problems. Previous studies indicated that levels of brain gangliosides are lower than normal in HD models and that administration of exogenous ganglioside GM1 corrects motor dysfunction in the YAC128 mouse model of HD In this study, we provide evidence that intraventricular administration of GM1 has profound disease-modifying effects across HD mouse models with different genetic background. GM1 administration results in decreased levels of mutant huntingtin, the protein that causes HD, and in a wide array of beneficial effects that include changes in levels of DARPP32, ferritin, Iba1 and GFAP, modulation of dopamine and serotonin metabolism, and restoration of normal levels of glutamate, GABA, L-Ser and D-Ser. Treatment with GM1 slows down neurodegeneration, white matter atrophy and body weight loss in R6/2 mice. Motor functions are significantly improved in R6/2 mice and restored to normal in Q140 mice, including gait abnormalities that are often resistant to treatments. Psychiatric-like and cognitive dysfunctions are also ameliorated by GM1 administration in Q140 and YAC128 mice. The widespread benefits of GM1 administration, at molecular, cellular and behavioural levels, indicate that this ganglioside has strong therapeutic and disease-modifying potential in HD.

Huntingtin Is Required for Neural But Not Cardiac/Pancreatic Progenitor Differentiation of Mouse Embryonic Stem Cells In vitro

Mutation in the huntingtin (HTT) gene causes Huntington's disease (HD). It is an autosomal dominant trinucleotide-repeat expansion disease in which CAG repeat sequence expands to >35. This results in the production of mutant HTT protein with an increased stretch of glutamines near the N-terminus. The wild type HTT gene encodes a 350 kD protein whose function remains elusive. Mutant HTT protein has been implicated in transcription, axonal transport, cytoskeletal structure/function, signal transduction, and autophagy. HD is characterized by the appearance of nuclear inclusions and degeneration of the striatum. Although HTT protein is expressed early in embryos, most patients develop symptoms in mid-life. It is also unclear why the ubiquitously expressed mutant HTT specifically causes striatal atrophy. Wild type Htt is essential for development as Htt knockout mice die at day E7.5. Increasing evidence suggests mutant Htt may alter neurogenesis and development of striatal neurons resulting in neuronal loss. Using a mouse embryonic stem cell model, we examined the role of Htt in neural differentiation. We found cells lacking Htt inefficient in generating neural stem cells. In contrast differentiation into progenitors of mesoderm and endoderm lineages was not affected. The data suggests Htt is essential for neural but not cardiac/pancreatic progenitor differentiation of embryonic stem cells in vitro.

Social Cognition, Executive Functions and Self-Report of Psychological Distress in Huntington's Disease

Objective: Huntington’s disease (HD) is characterized by motor symptoms, psychiatric symptoms and cognitive impairment in, inter alia, executive functions and social cognition. The aim of this study was to investigate the relationship between subjective feeling of psychological distress using a self-report questionnaire and performances on tests of executive functions and social cognition in a large consecutive cohort of HD patients.

Method: 50 manifest HD patients were tested in social cognition and executive functions and each answered a self-report questionnaire about current status of perceived psychological distress (the Symptom Checklist-90-Revised (SCL-90-R)). Correlation analyses of test performance and SCL-90-R scores were made as well as stepwise linear regression analyses with the SCL-90-R GSI score and test performances as dependent variables.

Results: We found that less psychological distress was significantly associated with worse performances on social cognitive tests (mean absolute correlation .34) and that there were no significant correlations between perceived psychological distress and performance on tests of executive functions. The correlations between perceived psychological distress and performance on social cognitive tests remained significant after controlling for age, Unified Huntington’s Disease Rating Scale-99 total motor score and performance on tests of executive functions.

Conclusions: Based on previous findings that insight and apathy are closely connected and may be mediated by overlapping neuroanatomical networks involving the prefrontal cortex and frontostriatal circuits, we speculate that apathy/and or impaired insight may offer an explanation for the correlation between self-report of psychological distress and performance on social cognitive tests in this study.

Personality traits in Huntington's disease: An exploratory study of gene expansion carriers and non-carriers

Huntington's disease (HD) is associated with risk for developing psychiatric symptoms. Vulnerability or resilience to psychiatric symptoms may be associated with personality traits. This exploratory study, aimed to investigate personality traits in a large cohort of HD carriers and at risk gene-expansion negative individuals (HD non-carriers), exploring whether carrying the HD gene or growing up in an HD family influences personality traits. Forty-seven HD carriers, Thirty-nine HD non-carriers, and 121 healthy controls answered the Danish version of the revised NEO personality inventory. Comparisons between HD carriers and HD non-carriers were mostly non-significant but the combined group of HD carriers and non-carriers showed significantly higher scores on the facets: "hostility," "assertiveness," and "activity" and on the trait "Conscientiousness" relative to controls, "Conscientiousness" have been associated with resilience to psychiatric symptoms. Twelve HD carriers and non-carriers were classified as depressed and showed significantly lower scores on "Extraversion" and "Conscientiousness" and significantly higher scores on "Neuroticism," which are associated with vulnerability to psychiatric symptoms. Our findings suggest that, there is no direct effect of the HD gene on personality traits, but that personality assessment may be relevant to use when identifying individuals from HD families who are vulnerable to develop psychiatric symptoms. © 2016 Wiley Periodicals, Inc.

COMT Val158Met Polymorphism Modulates Huntington's Disease Progression

Little is known about the genetic factors modulating the progression of Huntington's disease (HD). Dopamine levels are affected in HD and modulate executive functions, the main cognitive disorder of HD. We investigated whether the Val158Met polymorphism of the catechol-O-methyltransferase (COMT) gene, which influences dopamine (DA) degradation, affects clinical progression in HD. We carried out a prospective longitudinal multicenter study from 1994 to 2011, on 438 HD gene carriers at different stages of the disease (34 pre-manifest; 172 stage 1; 130 stage 2; 80 stage 3; 17 stage 4; and 5 stage 5), according to Total Functional Capacity (TFC) score. We used the Unified Huntington's Disease Rating Scale to evaluate motor, cognitive, behavioral and functional decline. We genotyped participants for COMT polymorphism (107 Met-homozygous, 114 Val-homozygous and 217 heterozygous). 367 controls of similar ancestry were also genotyped. We compared clinical progression, on each domain, between groups of COMT polymorphisms, using latent-class mixed models accounting for disease duration and number of CAG (cytosine adenine guanine) repeats. We show that HD gene carriers with fewer CAG repeats and with the Val allele in COMT polymorphism displayed slower cognitive decline. The rate of cognitive decline was greater for Met/Met homozygotes, which displayed a better maintenance of cognitive capacity in earlier stages of the disease, but had a worse performance than Val allele carriers later on. COMT polymorphism did not significantly impact functional and behavioral performance. Since COMT polymorphism influences progression in HD, it could be used for stratification in future clinical trials. Moreover, DA treatments based on the specific COMT polymorphism and adapted according to disease duration could potentially slow HD progression.