Stress in Huntington's Disease: Characteristics and Correlates in Patients and At-Risk Individuals.

Background: Huntington's disease (HD) is a neurodegenerative disease that presents families with significant numbers of stressful events. However, relatively little empirical research has characterized the stressors encountered by members of HD-affected families and their correlations with psychological symptoms. Objective: This study examined frequencies of specific stressors in HD patients and at-risk individuals and the correlates of these stressors with demographics, disease characteristics, and symptoms of depression and anxiety. Methods: HD patients (n = 57) and at-risk individuals (n = 81) completed the Responses to Stress Questionnaire -Huntington's Disease Version to assess HD-related stressors. Participants completed measures of depression and anxiety symptoms. Patient health records were accessed to obtain information related to disease characteristics. Results: Patients endorsed a mean number of 5.05 stressors (SD = 2.74) out of the 10-item list. Demographics were not related to total stressors, but disease characteristics were significantly related to specific stressors. At-risk individuals endorsed a mean number of 3.20 stressors (SD = 2.65) out of the 11-item list. Age and sex were significantly related to specific stressors. Total number of stressors was significantly related to depression (ß=0.67, p <  0.001) and anxiety symptoms (ß=0.58, p <  0.001) in patients and at-risk individuals (ß=0.35, p = 0.003 and ß=0.32, p = 0.006, respectively). Conclusions: hese findings emphasize the significant burden of stress experienced by HD patients and at-risk individuals. We highlight a need for more specific stress-based measures and psychosocial support interventions for HD-affected families.

Alterations in Cerebrospinal Fluid Urea Occur in Late Manifest Huntington's Disease.

Background: Huntington's disease (HD) is a neurodegenerative disorder caused by expanded cytosine-adenine-guanine (CAG) repeats in the Huntingtin gene, resulting in the production of mutant huntingtin proteins (mHTT). Previous research has identified urea as a key metabolite elevated in HD animal models and postmortem tissues of HD patients. However, the relationship between disease course and urea elevations, along with the molecular mechanisms responsible for these disturbances remain unknown. Objective: To better understand the molecular disturbances and timing of urea cycle metabolism across different stages in HD. Methods: We completed a global metabolomic profile of cerebrospinal fluid (CSF) from individuals who were at several stages of disease: pre-manifest (PRE), manifest (MAN), and late manifest (LATE) HD participants, and compared to controls. Results: Approximately 500 metabolites were significantly altered in PRE participants compared to controls, although no significant differences in CSF urea or urea metabolites were observed. CSF urea was significantly elevated in LATE participants only. There were no changes in the urea metabolites citrulline, ornithine, and arginine. Conclusions: Overall, our study confirms that CSF elevations occur late in the HD course, and these changes may reflect accumulating deficits in cellular energy metabolism.

Racial Differences in the Presentation and Progression of Huntington's Disease.

BACKGROUND: Huntington's disease (HD) is an autosomal dominant neurodegenerative disease that predominantly impacts a Caucasian population, but few efforts have explored racial differences in presentation and progression. OBJECTIVE: The aim was to assess the presentation and progression of HD across race groups using the Enroll-HD longitudinal observational study. METHODS: We applied propensity score matching for cytosine-adenine-guanine age product score, and age, to identify White, Hispanic, Asian, and Black participants from the Enroll-HD database. We compared clinical presentations at baseline, and progression over time, using White participants as a control cohort. RESULTS: Black participants were more severe at baseline across all clinical measures. No significant differences in progression were observed between race groups. CONCLUSIONS: We consider the factors driving clinical differences at baseline for Black participants. Our data emphasize the necessary improvement in underrepresented minority recruitment for studies of rare diseases. © 2023 International Parkinson and Movement Disorder Society.

Intrapersonal and Interpersonal Disengagement Coping: Associations with Emotions of Youth At-Risk for Huntington's Disease.

BACKGROUND: Families in which a parent has Huntington's disease (HD) are faced with significant stressors that can contribute to difficulties in communicating together about illness-related concerns. Family members who use more disengagement coping strategies, including denial and avoidance, to deal with illness-related stressors may have the greatest challenges to effective communication. OBJECTIVE: The current study examined the associations of intrapersonal and interpersonal disengagement coping responses with observed and reported emotions of adolescents and young adults (AYA) at genetic risk for HD. METHODS: Families included 42 AYA (n = 26 females) ages 10 to 34 (M = 19 years, 11 months; SD = 7 years, 6 months) and their parent with HD (n = 22 females, M age = 46 years, 10 months; SD = 9 years, 2 months). Dyads participated in observations of communication and completed questionnaires about disengagement coping and internalizing symptoms. RESULTS: Disengagement coping of AYA was unrelated to their observed and reported emotional difficulties (intrapersonal coping). However, there was evidence for the importance of interpersonal disengagement coping, as AYA's negative affect was observed and reported to be highest when both AYA and their parents reported using high levels of avoidance, denial, and wishful thinking to cope with HD-related stress. CONCLUSION: The findings underscore the importance of a family-oriented approach to coping and communication in families affected by HD.

A disease concept model for STXBP1-related disorders.

OBJECTIVE: STXBP1-related disorders are rare genetic epilepsies and neurodevelopmental disorders, but the impact of symptoms across clinical domains is poorly understood. Disease concept models are formal frameworks to assess the lived experience of individuals and their families and provide a basis for generating outcome measures. METHODS: We conducted semistructured, qualitative interviews with 19 caregivers of 16 individuals with STXBP1-related disorders and 7 healthcare professionals. We systematically coded themes using NVivo software and grouped concepts into the domains of symptoms, symptom impact, and caregiver impact. We quantified the frequency of concepts throughout the lifespan and across clinical subgroups stratified by seizure history and developmental trajectories. RESULTS: Over 25 hours of interviews, we coded a total of 3626 references to 38 distinct concepts. In addition to well-recognized clinical features such as developmental delay (n = 240 references), behavior (n = 201), and seizures (n = 147), we identified previously underrepresented symptoms including gastrointestinal (n = 68) and respiratory symptoms (n = 24) and pain (n = 30). The most frequently referenced symptom impacts were autonomy (n = 96), socialization (n = 64), and schooling (n = 61). Emotional impact (n = 354), support (n = 200), and daily life & activities (n = 108) were highly cited caregiver impacts. We found that seizures were more commonly referenced in infancy than in other age groups, while behavior and socialization were more likely to be referred to in childhood. We found that caregivers of individuals with ongoing seizures were less likely to reference developmental delay, possibly due to the relatively high impact of seizures. SIGNIFICANCE: STXBP1-related disorders are complex conditions affecting a wide range of clinical and social domains. We comprehensively mapped symptoms and their impact on families to generate a comprehensive disease model as a foundation for clinical endpoints in future trials.

Impairments to executive function in emerging adults with Huntington disease.

BACKGROUND AND OBJECTIVES: The clinical diagnosis of Huntington disease (HD) is typically made once motor symptoms and chorea are evident. Recent reports highlight the onset of cognitive and psychiatric symptoms before motor manifestations. These findings support further investigations of cognitive function across the lifespan of HD sufferers. METHODS: To assess cognitive symptoms in the developing brain, we administered assessments from the National Institutes of Health Toolbox Cognitive Battery, an age-appropriate cognitive assessment with population norms, to a cohort of children, adolescents and young adults with (gene-expanded; GE) and without (gene-not-expanded; GNE) the trinucleotide cytosine, adenine, guanine (CAG) expansion in the Huntingtin gene. These five assessments that focus on executive function are well validated and form a composite score, with population norms. We modelled these scores across age, and CAP score to estimate the slope of progression, comparing these results to motor symptoms. RESULTS: We find significant deficits in the composite measure of executive function in GE compared with GNE participants. GE participant performance on working memory was significantly lower compared with GNE participants. Modelling these results over age suggests that these deficits occur as early as 18 years of age, long before motor manifestations of HD. CONCLUSIONS: This work provides strong evidence that impairments in executive function occur as early as the second decade of life, well before anticipated motor onset. Future investigations should delineate whether these impairments in executive function are due to abnormalities in neurodevelopment or early sequelae of a neurodegenerative process.

Alterations in metal homeostasis occur prior to canonical markers in Huntington disease.

The importance of metal biology in neurodegenerative diseases such as Huntingtin Disease is well documented with evidence of direct interactions between metals such as copper, zinc, iron and manganese and mutant Huntingtin pathobiology. To date, it is unclear whether these interactions are observed in humans, how this impacts other metals, and how mutant Huntington alters homeostatic mechanisms governing levels of copper, zinc, iron and manganese in cerebrospinal fluid and blood in HD patients. Plasma and cerebrospinal fluid from control, pre-manifest, manifest and late manifest HD participants were collected as part of HD-Clarity. Levels of cerebrospinal fluid and plasma copper, zinc, iron and manganese were measured as well as levels of mutant Huntingtin and neurofilament in a sub-set of cerebrospinal fluid samples. We find that elevations in cerebrospinal fluid copper, manganese and zinc levels are altered early in disease prior to alterations in canonical biomarkers of HD although these changes are not present in plasma. We also evidence that CSF iron is elevated in manifest patients. The relationships between plasma and cerebrospinal fluid metal are altered based on disease stage. These findings demonstrate that there are alterations in metal biology selectively in the CSF which occur prior to changes in known canonical biomarkers of disease. Our work indicates that there are pathological changes related to alterations in metal biology in individuals without elevations in neurofilament and mutant Huntingtin.

Inhibitory control, working memory and coping with stress: Associations with symptoms of anxiety and depression in adults with Huntington's disease.

OBJECTIVE: Huntington's disease (HD) is an autosomal dominant neurodegenerative disease characterized by neuropsychiatric symptoms (e.g., anxiety and depression), where individuals suffer high levels of stress from the social, physical, and cognitive burden of the disease. The present study examined two factors associated with increased risk for symptoms of anxiety and depression: executive function skills (inhibitory control/attention and working memory) and skills to cope with stress. METHOD: Adults with HD completed the NIH Toolbox measures of inhibitory control/attention and working memory, as well as self-report measures of coping with HD-related stress and symptoms of anxiety and depression. Path analyses were used to test direct and indirect associations among the subtypes of executive functioning, coping, and symptoms. RESULTS: No significant associations were found in the full sample (n = 47), due to a significant portion of the sample with very low executive function abilities. Additional analyses were conducted on a subset of the sample (participants in the top three quartiles on both measures of executive functioning, n = 32). Significant indirect associations emerged among inhibitory control/attention skills, secondary control coping (e.g., acceptance and reappraisal), and symptoms of anxiety and depression in the subsample. Higher inhibitory control/attention skills were associated with greater use of secondary control coping, and greater use of these coping skills was related to lower symptoms of anxiety and depression. No direct or indirect associations were found among working memory skills, coping, and symptoms of anxiety and depression. CONCLUSIONS: Implications for interventions to enhance executive function and coping skills in adults with HD are highlighted. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Diagnosis and management of sleep disorders in Prader-Willi syndrome.

Clinical experience and a growing body of evidence suggest that sleep disturbances are common in people with Prader-Willi syndrome (PWS). PWS is a rare neuroendocrine disorder characterized by early hypotonia and feeding difficulties; developmental delays; endocrinopathies; and behavioral concerns, especially rigidity, anxiety, and behavioral outbursts. PWS is also characterized by decreased resting energy expenditure and transition to hyperphagia and obesity. We propose that, for many people with PWS, clinical diagnosis and management of sleep disorders is an unmet need. We present current information to suggest disordered sleep is a significant burden for individuals with PWS and often overlooked. While central and obstructive sleep apnea are more widely recognized in PWS, other sleep disorders have increasingly gained recognition, including hypersomnia, narcolepsy-like phenotypes, and insomnia. Sleep disorders can impact behavior, cognition, and quality of life and health for individuals with PWS. Our goal is to bring sleep disorders to the forefront of therapeutic intervention for patients with PWS. This paper presents a review of the literature and recommendations for clinical practice based on published research and our clinical experience as sleep specialists, geneticists, psychiatrists, pediatricians, otolaryngologists, and pulmonologists with extensive experience with this patient population. We recommend that management of sleep be considered an integral part of successful medical management of PWS. Further research concerning sleep problems in PWS is urgently needed to develop best practices and work toward a consensus statement for medical management to meet the needs of people with PWS. CITATION: Duis J, Pullen LC, Picone M, et al. Diagnosis and management of sleep disorders in Prader-Willi syndrome. J Clin Sleep Med. 2022;18(6):1687-1696.

A draft conceptual model of SLC6A1 neurodevelopmental disorder.

Introduction: SLC6A1 Neurodevelopmental Disorder (SLC6A1-NDD), first described in 2015, is a rare syndrome caused by a mutation in the SLC6A1 gene which encodes for the GABA Transporter 1 (GAT-1) protein. Epilepsy is one of the most common symptoms in patients and is often the primary treatment target, though the severity of epilepsy is variable. The impact of seizures and other symptoms of SLC6A1-NDD on patients and caregivers is wide-ranging and has not been described in a formal disease concept study. Methods: A literature search was performed using the simple search term, "SLC6A1." Papers published before 2015, and those which did not describe the human neurodevelopmental disorder were removed from analysis. Open-ended interviews on lived experiences were conducted with two patient advocate key opinion leaders. An analysis of de-identified conversations between families of people with SLC6A1-NDD on social media was performed to quantify topics of concern. Results: Published literature described symptoms in all of the following domains: neurological, visual, motor, cognitive, communication, behavior, gastrointestinal, sleep, musculo-skeletal, and emotional in addition to epilepsy. Key opinion leaders noted two unpublished features: altered hand use in infants, and developmental regression with onset of epilepsy. Analysis of social media interactions confirmed that the core symptoms of epilepsy and autistic traits were prominent concerns, but also demonstrated that other symptoms have a large impact on family life. Discussion: For rare diseases, analysis of published literature is important, but may not be as comprehensive as that which can be gleaned from spontaneous interactions between families and through qualitative interviews. This report reflects our current understanding of the lived experience of SLC6A1-NDD. The discrepancy between the domains of disease reported in the literature and those discussed in patient conversations suggests that a formal qualitative interview-based disease concept study of SLC6A1-NDD is warranted.

YAC128 mouse model of Huntington disease is protected against subtle chronic manganese (Mn)-induced behavioral and neuropathological changes.

Manganese (Mn) is an essential micronutrient but excessive levels induce neurotoxic effects. Increasing evidence suggests a deficit of bioavailable Mn in Huntington disease (HD), an inherited neurodegenerative disease characterized by motor and cognitive disturbances. Previous studies have shown rescue of some molecular HD phenotypes by acute Mn exposure. This study simultaneously examined the potential for chronic Mn exposure to attenuate HD behavioral phenotypes, and for the HD genotype to offer protection against detrimental effects of chronic Mn exposure. In two independent studies a chronic Mn exposure paradigm was implemented in the YAC128 mouse model of HD and behavior was assessed at several timepoints. Study 1 exposed WT and YAC128 mice to twice weekly subcutaneous injections of 0, 5, 15, or 50 mg/kg MnCl[2] tetrahydrate from 12 to 32 weeks of age. A promising protective effect against motor coordination decline in 5 mg/kg MnCl[2] tetrahydrate-treated YAC128 mice was detected. Study 2 thus exposed WT and YAC128 mice to either 0 or 5 mg/kg MnCl[2] tetrahydrate from 12 to 52 weeks of age (with a partial randomized treatment crossover at 31 weeks). The same protective effect was not observed under these conditions at higher statistical power. We report subtle toxicological changes in exploratory behavior and total activity induced by chronic Mn exposure in WT mice only, despite similar total increases in brain Mn in WT and YAC128 mice. Further, chronic Mn treatment resulted in a 10-12 % decrease in striatal NeuN positive cell density in WT mice but not YAC128 mice, despite vehicle cell counts already being reduced compared to WT mice as expected for the HD genotype. The subtle changes observed in specific outcome measures, but not others, following long-term low-level Mn exposure in WT mice delineate the neurobehavioral and neuropathological effects at the threshold of chronic Mn toxicity. We conclude that these chronic low-dose Mn exposures do not significantly rescue behavioral HD phenotypes, but YAC2128 mice are protected against the subtle Mn-induced behavioral changes and decreased striatal neuron density observed in Mn-exposed WT mice.

Rodent hair is a Poor biomarker for internal manganese exposure.

Hair is used as a biomarker of manganese (Mn) exposure, yet there is limited evidence to support its utility to quantify internal vs external Mn exposure. C57BL/6 J mice and Sprague-Dawley rats were exposed in two blocks of 3 subcutaneous injections every 3 days starting on day 0 or 20. The control group received two blocks of saline (vehicle); Treatment A received the first block as Mn (50 mg/kg MnCl2 tetrahydrate), with the second block as either methylmercury (MeHg at 2.6 or 1.3 mg/kg) for mice or vehicle for rats; and Treatment B received Mn for both blocks. Hair was collected on days 0 and 60 from all treatment groups and Mn quantified by inductively coupled plasma-mass spectrometry (ICP-MS) and total Hg by Direct Mercury Analyzer (DMA). No correlation between internal Mn dose and hair Mn was observed, whereas hair Hg was significantly elevated in MeHg exposed vs non-exposed mice. Whole body Mn content at day 60 was quantified postmortem by neutron activation analysis, which detected significantly elevated Mn for Treatment B in mice and rats. Overall, we find no evidence to support the use of hair as a valid biomarker for internal exposure to Mn at a neurotoxic level.

Neurobiological and Psychosocial Correlates of Communication Between Huntington's Disease Patients and Their Offspring.

OBJECTIVE: Huntington's disease (HD) is an autosomal dominant neurodegenerative disease that presents significant challenges to family communication. The investigators examined observations of communication between parents with HD and their offspring talking about the challenges of HD and explored potential correlates of their communication. METHODS: The sample included parents with HD and their adolescent and young-adult offspring (N=64). Parent communication and chorea were independently coded from video recordings. Parents and offspring completed working memory assessments and self-reports of neuropsychiatric symptoms, stress, and coping. RESULTS: Evidence was found for the association of observed parent-offspring communication with disease markers, psychosocial characteristics, and neurocognitive function. For parents, disease markers and working memory were correlates of communication, whereas offspring's psychiatric symptoms, stress, and coping were associated with their communication. CONCLUSIONS: These findings have potential implications for clinical interventions to enhance communication and quality of life for HD families.

Empowering the Clinical Research Coordinator in Academic Medical Centers.

OBJECTIVE: To identify factors associated with job satisfaction and retention, we surveyed a large cohort of clinical research coordinators (CRCs). In recent years, the clinical research coordinator has changed from a semi-permanent role to one that has a high turnover rate. The CRCs are integral to clinical research and instability in this role can cause patient stress and increase the burden on clinical teams through unnecessary delegation of resources toward hiring and retraining new talent. The cultural shift toward CRCs as a temporary position may be driven by the perspective that the role positions an individual for other health care careers, but understanding what influences low retention rates are necessary. METHODS: A survey containing 13 multiple choice or open-ended and 32 Likert scale questions was distributed to previous and current CRCs using REDCap. The questionnaires were self-administered and completed over a 12-month period between October 11, 2017, and September 16, 2018. RESULTS: A total of 85 CRCs completed the study. From the 32 potential predictors of retention, we investigated 9 significant predictors: salary, work setting, understanding the role, level of CRC, understanding protocol development, actively engaged principal investigator (PI), having a collaborative role with PI, feeling respected by PI, and having a close relationship with PI. Adequate salary, greater respect, collaboration, and engagement from the PI were significantly associated with higher retention. Surprisingly, greater workload and lack of opportunity for professional growth were not associated with retention. CONCLUSION: The CRCs who feel respected and engaged by the PI and are adequately compensated are more likely to have higher job satisfaction and retention.

Healthcare Delivery and Huntington's Disease During the Time of COVID-19.

BACKGROUND: Safer-at-home orders during the COVID-19 pandemic altered the structure of clinical care for Huntington's disease (HD) patients. This shift provided an opportunity to identify limitations in the current healthcare infrastructure and how these may impact the health and well-being of persons with HD. OBJECTIVE: The study objectives were to assess the feasibility of remote healthcare delivery in HD patients, to identify socioeconomic factors which may explain differences in feasibility and to evaluate the impact of safer-at-home orders on HD patient stress levels. METHODS: This observational study of a clinical HD population during the 'safer-at-home' orders asked patients or caregivers about their current access to healthcare resources and patient stress levels. A chart review allowed for an assessment of socioeconomic status and characterization of HD severity. RESULTS: Two-hundred and twelve HD patients were contacted with 156 completing the survey. During safer-at-home orders, the majority of HD patients were able to obtain medications and see a physician; however, 25% of patients would not commit to regular telehealth visits, and less than 50% utilized an online healthcare platform. We found that 37% of participants were divorced/single, 39% had less than a high school diploma, and nearly 20% were uninsured or on low-income health insurance. Patient stress levels correlated with disease burden. CONCLUSION: A significant portion of HD participants were not willing to participate in telehealth services. Potential explanations for these limitations may include socioeconomic barriers and caregiving structure. These observations illustrate areas for clinical care improvement to address healthcare disparities in the HD community.

Risk-Taking Behaviors in Huntington's Disease.

BACKGROUND: Risky behaviors are common in Huntington's disease (HD) and can lead to significant adverse consequences. However, the prevalence and scope of these symptoms have not been studied systematically, and no empirically validated measures are available to screen for them. OBJECTIVE: To test a novel screening tool designed to assess risk-taking behaviors in HD. METHODS: We administered the Risk Behavior Questionnaire (RBQ-HD) to HD patients and caregivers at Vanderbilt University Medical Center between 2018-2019. Patients completed the questionnaire based on self-report; caregivers provided collateral reports. Clinical and demographic information were obtained from the electronic medical record. RESULTS: 60 patients and 60 caregivers completed the RBQ-HD. 80% of patients (n = 48) and 91.7% of caregivers (n = 60) reported at least one risky behavior. Adverse social behaviors, impulsive/compulsive behaviors, and reckless driving were the most common behavioral domains reported. Male patients were more likely to report risky behaviors than females (92.3% vs. 70.6%, p = 0.04). The number of risky behaviors reported by patients and caregivers was negatively correlated with patient age (r = -0.32, p = 0.01; r = -0.47, p = 0.0001, respectively). Patient and caregiver reports were highly correlated in matched pairs (n = 30; r = 0.63, p = 0.0002). CONCLUSION: These findings emphasize that risky behaviors are highly prevalent in HD and can be effectively identified through the use of a novel screening measure. We hypothesize that early pathological involvement of frontostriatal and mesolimbic networks may be important factors in the development of these behaviors.

Investigating the interplay of working memory, affective symptoms, and coping with stress in offspring of parents with Huntington's disease.

OBJECTIVE: The offspring of parents with Huntington's disease (HD) are faced with substantial levels of chronic uncontrollable and unpredictable stress. These stressors may place them at heightened risk of psychological distress and negative effects on executive functioning. This study investigated working memory, secondary control coping strategies (e.g., cognitive reappraisal, acceptance, distraction), and symptoms of anxiety/depression in offspring at risk for HD. METHOD: Adolescent (ages 10-19) and young adult (ages 20-29) offspring (n = 33; mean [M] age = 19.12 years, standard deviation [SD] = 6.01 years; 61% female) of parents with HD were recruited in a Huntington Disease Society of America Level 1 Center of Excellence. Participants completed self-report measures of coping and neuropsychiatric symptoms (i.e., anxiety, depression) and a standardized working memory assessment. Pearson correlations and path analyses were used to test associations. RESULTS: Participant scores on the working memory assessment were significantly lower compared with normative data, and scores on a mixed anxiety/depression scale revealed a significant elevation compared with normative data. Working memory, secondary control coping, and symptoms of anxiety/depression were significantly correlated. Analyses of the full model revealed that the total indirect effect of working memory on anxiety/depression through secondary control coping was significant (ß = -0.20). CONCLUSION: Secondary control coping skills are an important factor in understanding the relationship between working memory and symptoms of anxiety/depression in the offspring of parents with HD. Future longitudinal research is needed to establish the direction of these associations. Working memory and coping skills represent potential targets for intervention to reduce the risk of anxiety/depression in this population. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Huntington's disease genotype suppresses global manganese-responsive processes in pre-manifest and manifest YAC128 mice.

Manganese (Mn) is an essential micronutrient required for the proper function of several enzymes. Accumulating evidence demonstrates a selective decrease of bioavailable Mn in vulnerable cell types of Huntington's Disease (HD), an inherited progressive neurodegenerative disorder with no cure. Amelioration of underlying pathophysiology, such as alterations in Mn-dependent biology, may be therapeutic. We therefore sought to investigate global Mn-dependent and Mn-responsive biology following various Mn exposures in a mouse model of HD. YAC128 and wildtype (WT) littermate control mice received one of three different Mn exposure paradigms by subcutaneous injection of 50 mg kg-1 MnCl2·4(H2O) across two distinct HD disease stages. "Pre-manifest" (12-week old mice) mice received either a single (1 injection) or week-long (3 injections) exposure of Mn or vehicle (H2O) and were sacrificed at the pre-manifest stage. "Manifest" (32-week old) mice were sacrificed following either a week-long Mn or vehicle exposure during the manifest stage, or a 20-week-long chronic (2× weekly injections) exposure that began in the pre-manifest stage. Tissue Mn, mRNA, protein, and metabolites were measured in the striatum, the brain region most sensitive to neurodegeneration in HD. Across all Mn exposure paradigms, pre-manifest YAC128 mice exhibited a suppressed response to transcriptional and protein changes and manifest YAC128 mice showed a suppressed metabolic response, despite equivalent elevations in whole striatal Mn. We conclude that YAC128 mice respond differentially to Mn compared to WT as measured by global transcriptional, translational, and metabolomic changes, suggesting an impairment in Mn homeostasis across two different disease stages in YAC128 mice.

Striatal Cholesterol Precursors Are Altered with Age in Female Huntington's Disease Model Mice.

BACKGROUND: Cholesterol is necessary for proper neurodevelopment and neuronal health. The brain relies on neural and astrocytic de novo cholesterol synthesis. Huntington's disease presents with altered levels of cholesterol precursors however it is unknown when the disruption in this molecular pathway occurs and whether Manganese (Mn) may alter these metabolic alterations. OBJECTIVE: To examine the effect of Mn exposure on cholesterol biosynthesis in pre-manifest and manifest Huntington's disease mice. METHODS: 12-week (pre-manifest) male and female and 42-week old (manifest) female YAC128 and littermate control (WT) mice received 3 subcutaneous Mn or vehicle injections. Animals were sacrificed 24 hours after the final injection and striatum, cerebral cortex and cerebellum were collected to measure cholesterol and cholesterol precursors using LC/MS-MS. RESULTS: Striatal desmosterol and cholesterol are increased in pre-manifest HD females compared to age-matched WT female mice. Striatal lanosterol, 8-DHC and desmosterol and cholesterol are reduced in manifest HD females compared to age-and sex-matched WT mice with minimal effects in the cortex and cerebellum. Mn treatment had no effect in the pre-manifest or manifest female brain except reduced lanosterol levels in the cortex of pre-manifest female mice. Neither Mn or HD altered brain cholesterol precursor levels in the pre-manifest HD or WT male mouse. CONCLUSIONS: Cholesterol biosynthesis is impaired in early disease stage in female HD mice only and continues throughout disease. These alterations appear largely striatal-specific. Acute systemic exposure to Mn did not significantly alter cholesterol biosynthesis in the striatum at any disease stage.

Incremental Elevations in TNFα and IL6 in the Human Colon and Procancerous Changes in the Mucosal Transcriptome Accompany Adiposity.

BACKGROUND: Obesity, a risk factor for colorectal cancer, raises systemic levels of proinflammatory mediators. Whether increased levels also reside in the colons of obese individuals and are accompanied by procancerous alterations in the mucosal transcriptome is unknown. METHODS: Concentrations of TNFα, IL1ß, and IL6 in blood and colonic mucosa of 16 lean and 26 obese individuals were examined. Differences in the mucosal transcriptome between the two groups were defined. RESULTS: Plasma IL6 and TNFα were 1.4- to 3-fold elevated in obese subjects [body mass index (BMI) ≥ 34 kg/m2] compared with the lean controls (P < 0.01). Among individuals with BMI ≥ 34 kg/m2 colonic concentrations of IL6 and TNFα were 2- to 3-fold greater than in lean subjects (P < 0.03). In a general linear model, adjusted for NSAID use, colonic IL6 (partial r = 0.41; P < 0.01) and TNFα (partial r = 0.41; P = 0.01) increased incrementally over the entire range of BMIs (18.1-45.7). Regular use of nonsteroidal anti-inflammatory drugs (NSAIDs) was associated with a reduction in colonic IL6 (ß = -0.65, P < 0.02). RNA sequencing (NSAID users excluded) identified 182 genes expressed differentially between lean and obese subjects. The two gene networks most strongly linked to changes in expression included several differentially expressed genes known to regulate the procarcinogenic signaling pathways, NFκB and ERK 1/2, in a pattern consistent with upregulation of each in the obese subjects. CONCLUSIONS: Incremental increases in two major proinflammatory colonic cytokines are associated with increasing BMI, and in the obese state are accompanied by procancerous changes in the transcriptome. IMPACT: These observations delineate means by which an inflammatory milieu may contribute to obesity-promoted colon cancer.