[Show abstract][Hide abstract] ABSTRACT: Huntington's disease (HD) is a neurodegenerative condition characterised by pathology in the brain and peripheral tissues. Hyperactivity of the innate immune system, due in part to NFκB pathway dysregulation, is an early and active component of HD. Evidence suggests targeting immune disruption may slow disease progression. Laquinimod is an orally active immunomodulator that downregulates proinflammatory cytokine production in peripheral blood mononuclear cells, and in the brain downregulates astrocytic and microglial activation by modulating NFκB signalling. Laquinimod had beneficial effects on inflammation, brain atrophy and disease progression in multiple sclerosis (MS) in two phase III clinical trials. The present study investigated the effects of laquinimod on hyperactive proinflammatory cytokine release and NFκB signalling in HD patient myeloid cell cultures. Monocytes from manifest (manHD) and pre-manifest (preHD) HD gene-carriers and healthy volunteers (HV) were treated with laquinimod and stimulated with lipopolysaccharide. After 24 h pre-treatment with 5 μM laquinimod, manHD monocytes released lower levels of IL-1β, IL-5, IL-8, IL-10, IL-13 and TNFα in response to stimulation. PreHD monocytes released lower levels of IL-8, IL-10 and IL-13, with no reduction observed in HV monocytes. The effects of laquinimod on dysfunctional NFκB signalling in HD was assessed by inhibitor of kappa B (IκB) degradation kinetics, nuclear translocation of NFκB and interactions between IκB kinase (IKK) and HTT, in HD myeloid cells. No differences were observed between laquinimod-treated and untreated conditions. These results provide evidence that laquinimod dampens hyper-reactive cytokine release from manHD and preHD monocytes, with a much reduced effect on HV monocytes. This article is protected by copyright. All rights reserved.
No preview · Article · Jan 2016 · Journal of Neurochemistry
[Show abstract][Hide abstract] ABSTRACT: Abnormal monoamine oxidase A and B (MAO-A/B) activity and an imbalance in monoamine neurotransmitters have been suggested to underlie the pathobiology of depression, a major psychiatric symptom observed in patients with neurodegenerative diseases, such as Huntington disease (HD). Increased MAO-A/B activity has been observed in brain tissue from patients with HD and in human and rodent HD neural cells. Using the YAC128 mouse model of HD, we studied the effect of an irreversible MAO-A inhibitor, clorgyline, on the levels of select monoamine neurotransmitters associated with affective function. We observed a decrease in striatal levels of the MAO-A/B substrates, dopamine and norepinephrine, in YAC128 HD mice compared with wild-type mice, which was accompanied by increased anxiety- and depressive-like behaviour at five months of age. Treatment for 26 days with clorgyline restored dopamine, serotonin, and norepinephrine neurotransmitter levels in the striatum and reduced anxiety- and depressive-like behaviour in YAC128 HD mice. This study supports a potential therapeutic use for MAO-A inhibitors in the treatment of depression and anxiety in patients with HD.
Preview · Article · Jan 2016 · Experimental Neurology
[Show abstract][Hide abstract] ABSTRACT: Glatiramer acetate (Copaxone®; GA) is a non-biological complex drug for multiple sclerosis. GA modulated thousands of genes in genome-wide expression studies conducted in THP-1 cells and mouse splenocytes. Comparing GA with a differently-manufactured glatiramoid Polimunol (Synthon) in mice yielded hundreds of differentially expressed probesets, including biologically-relevant genes (e.g. Il18, adj p<9e-6) and pathways. In human monocytes, 700+ probesets differed between Polimunol and GA, enriching for 130+ pathways including response to lipopolysaccharide (adj. p<0.006). Key differences were confirmed by qRT-PCR (splenocytes) or proteomics (THP-1). These studies demonstrate the complexity of GA's mechanisms of action, and may help inform therapeutic equivalence assessment.
Preview · Article · Nov 2015 · Journal of Neuroimmunology
[Show abstract][Hide abstract] ABSTRACT: Background Interpopulation differences in drug responses are well documented, and in some cases they correspond to differences in the frequency of associated genetic markers. Understanding the diversity of genetic markers associated with drug response across different global populations is essential to infer population rates of drug response or risk for adverse drug reactions, and to guide implementation of pharmacogenomic testing. Sri Lanka is a culturally and linguistically diverse nation, but little is known about the population genetics of the major Sri Lankan ethnic groups. The objective of this study was to investigate the diversity of pharmacogenomic variants in the major Sri Lankan ethnic groups. Methods We examined the allelic diversity of more than 7000 variants in genes involved in drug biotransformation and response in the three major ethnic populations of Sri Lanka (Sinhalese, Sri Lankan Tamils, and Moors), and compared them with other South Asian, South East Asian, and European populations using Wright's Fixation Index, principal component analysis, and STRUCTURE analysis. Results We observed overall high levels of similarity within the Sri Lankan populations (median F ST =0.0034), and between Sri Lankan and other South Asian populations (median F ST =0.0064). Notably, we observed substantial differentiation between Sri Lankan and European populations for important pharmacogenomic variants related to warfarin (VKORC1 rs9923231) and clopidogrel (CYP2C19 rs4986893) response. Conclusion These data expand our understanding of the population structure of Sri Lanka, provide a resource for pharmacogenomic research, and have implications for the clinical use of genetic testing of pharmacogenomic variants in these populations.
No preview · Article · Oct 2015 · Pharmacogenetics and Genomics
[Show abstract][Hide abstract] ABSTRACT: Anthracyclines are used in over 50% of childhood cancer treatment protocols, but their clinical usefulness is limited by anthracycline-induced cardiotoxicity (ACT) manifesting as asymptomatic cardiac dysfunction and congestive heart failure in up to 57% and 16% of patients, respectively. Candidate gene studies have reported genetic associations with ACT, but these studies have in general lacked robust patient numbers, independent replication or functional validation. Thus, the individual variability in ACT susceptibility remains largely unexplained. We performed a genome-wide association study in 280 patients of European ancestry treated for childhood cancer, with independent replication in similarly treated cohorts of 96 European and 80 non-European patients. We identified a nonsynonymous variant (rs2229774, p.Ser427Leu) in RARG highly associated with ACT (P = 5.9 × 10(-8), odds ratio (95% confidence interval) = 4.7 (2.7-8.3)). This variant alters RARG function, leading to derepression of the key ACT genetic determinant Top2b, and provides new insight into the pathophysiology of this severe adverse drug reaction.
[Show abstract][Hide abstract] ABSTRACT: Author Summary
Protein localization is essential for mediating protein function within the cellular context. Mislocalization of proteins can offset cellular balance, influencing whether a cell lives or dies. Many proteins are directed to cellular membranes through the addition of fats, or lipidation. In particular, palmitoylation involves the reversible addition of the fatty acid palmitate to cysteines. Its reversibility makes it a unique form of lipidation allowing its dynamic regulation. Recent advancements in fast, sensitive, non-radioactive methods to detect palmitoylation have led to an explosion in the identification of palmitoylated proteins through proteomics studies. However, the data is hidden in large supplemental tables in various formats. Thus, we curated a list of palmitoylated proteins revealing that approximately 10 percent of the human genome encodes for a proteoform that is palmitoylated. Computational analysis confirmed that palmitoylation is involved in protein localization and indicated a new role in metabolism. Importantly, we found that palmitoylation was enriched at neuronal synapses and in disorders of the nervous system, including Schizophrenia and Huntington disease. Interestingly, palmitoylation was equally enriched in cancers. Consequently, we suggest that palmitoylation plays a critical role in cell fate and our compendium provides a plethora of targets for neurodegeneration and cancer.
Full-text · Article · Aug 2015 · PLoS Computational Biology
[Show abstract][Hide abstract] ABSTRACT: To identify novel variants associated with anthracycline-induced cardiotoxicity and to assess these in a genotype-guided risk prediction model.
Two cohorts treated for childhood cancer (n = 344 and 218, respectively) were genotyped for 4578 SNPs in drug ADME and toxicity genes.
Significant associations were identified in SLC22A17 (rs4982753; p = 0.0078) and SLC22A7 (rs4149178; p = 0.0034), with replication in the second cohort (p = 0.0071 and 0.047, respectively). Additional evidence was found for SULT2B1 and several genes related to oxidative stress. Adding the SLC22 variants to the prediction model improved its discriminative ability (AUC 0.78 vs 0.75 [p = 0.029]).
Two novel variants in SLC22A17 and SLC22A7 were significantly associated with anthracycline-induced cardiotoxicity and improved a genotype-guided risk prediction model, which could improve patient risk stratification. Original submitted 26 November 2014; Revision submitted 12 May 2015.
No preview · Article · Jul 2015 · Pharmacogenomics
[Show abstract][Hide abstract] ABSTRACT: Huntington disease (HD) is a dominant neurodegenerative disorder caused by a CAG repeat expansion in the Huntingtin gene (HTT). Heterozygous polymorphisms in cis with the mutation allow for allele-specific suppression of the pathogenic HTT transcript as a therapeutic strategy. To prioritize target selection, precise heterozygosity estimates are needed across diverse HD patient populations. Here we present the first comprehensive investigation of all common target alleles across the HTT gene, using 738 reference haplotypes from the 1000 Genomes Project and 2364 haplotypes from HD patients and relatives in Canada, Sweden, France, and Italy. The most common HD haplotypes (A1, A2, and A3a) define mutually exclusive sets of polymorphisms for allele-specific therapy in the greatest number of patients. Across all four populations, a maximum of 80% are treatable using these three target haplotypes. We identify a novel deletion found exclusively on the A1 haplotype, enabling potent and selective silencing of mutant HTT in approximately 40% of patients. Antisense oligonucleotides complementary to the deletion reduce mutant A1 HTT mRNA by 78% in patient cells while sparing wild-type HTT expression. By suppressing specific haplotypes on which expanded CAG occurs, we demonstrate a rational approach to the development of allele-specific therapy for a monogenic disorder.Molecular Therapy (2015); doi:10.1038/mt.2015.128.
[Show abstract][Hide abstract] ABSTRACT: Quantitation of huntingtin protein in the brain is needed, both as a marker of Huntington disease (HD) progression and for use in clinical gene silencing trials. Measurement of huntingtin in cerebrospinal fluid could be a biomarker of brain huntingtin, but traditional protein quantitation methods have failed to detect huntingtin in cerebrospinal fluid. Using micro-bead based immunoprecipitation and flow cytometry (IP-FCM), we have developed a highly sensitive mutant huntingtin detection assay. The sensitivity of huntingtin IP-FCM enables accurate detection of mutant huntingtin protein in the cerebrospinal fluid of HD patients and model mice, demonstrating that mutant huntingtin levels in cerebrospinal fluid reflect brain levels, increasing with disease stage and decreasing following brain huntingtin suppression. This technique has potential applications as a research tool and as a clinical biomarker.
[Show abstract][Hide abstract] ABSTRACT: We describe a novel, inherited 16q13 microdeletion that removes CETP and several nearby genes. The proband was originally referred for severe childhood-onset obesity and moderate developmental delay, but his fasting lipid profile revealed relatively high HDL-cholesterol and low LDL-cholesterol for age, despite his obesity. Testing first-degree relatives identified two other microdeletion carriers. Functional assays in affected individuals showed decreased CETP mRNA expression and enzymatic activity. This microdeletion may or may not be pathogenic for obesity and developmental delay, but based on the lipid profile, the functional studies, and the phenotype of other patients with loss-of-function mutations of CETP, we believe this microdeletion to be antipathogenic for cardiovascular disease.
This article is protected by copyright. All rights reserved.
No preview · Article · Jun 2015 · Clinical Genetics
[Show abstract][Hide abstract] ABSTRACT: Glatiramer Acetate (GA) has provided safe and effective treatment for multiple sclerosis (MS) patients for two decades. It acts as an antigen, yet the precise mechanism of action remains to be fully elucidated, and no validated pharmacokinetic or pharmacodynamic biomarkers exist. In order to better characterize GA's biological impact, genome-wide expression studies were conducted with a human monocyte (THP-1) cell line. Consistent with previous literature, branded GA upregulated anti-inflammatory markers (e.g. IL10), and modulated multiple immune-related pathways. Despite some similarities, significant differences were observed between expression profiles induced by branded GA and Probioglat, a differently-manufactured glatiramoid purported to be a generic GA. Key results were verified using qRT-PCR. Genes (e.g. CCL5, adj. p < 4.1 × 10(-5)) critically involved in pro-inflammatory pathways (e.g. response to lipopolysaccharide, adj. p = 8.7 × 10(-4)) were significantly induced by Probioglat compared with branded GA. Key genes were also tested and confirmed at the protein level, and in primary human monocytes. These observations suggest differential biological impact by the two glatiramoids and warrant further investigation.
No preview · Article · May 2015 · Scientific Reports
[Show abstract][Hide abstract] ABSTRACT: Cis-regulatory variants that alter gene expression can modify disease expressivity, but none have previously been identified in Huntington disease (HD). Here we provide in vivo evidence in HD patients that cis-regulatory variants in the HTT promoter are bidirectional modifiers of HD age of onset. HTT promoter analysis identified a NF-κB binding site that regulates HTT promoter transcriptional activity. A non-coding SNP, rs13102260:G > A, in this binding site impaired NF-κB binding and reduced HTT transcriptional activity and HTT protein expression. The presence of the rs13102260 minor (A) variant on the HD disease allele was associated with delayed age of onset in familial cases, whereas the presence of the rs13102260 (A) variant on the wild-type HTT allele was associated with earlier age of onset in HD patients in an extreme case-based cohort. Our findings suggest a previously unknown mechanism linking allele-specific effects of rs13102260 on HTT expression to HD age of onset and have implications for HTT silencing treatments that are currently in development.
Full-text · Article · May 2015 · Nature Neuroscience
[Show abstract][Hide abstract] ABSTRACT: Huntington disease is devastating to patients and their families — with autosomal dominant inheritance, onset typically in the prime of adult life, progressive course, and a combination of motor, cognitive and behavioural features. The disease is caused by an expanded CAG trinucleotide repeat (of variable length) in HTT, the gene that encodes the protein huntingtin. In mutation carriers, huntingtin is produced with abnormally long polyglutamine sequences that confer toxic gains of function and predispose the protein to fragmentation, resulting in neuronal dysfunction and death. In this Primer, we review the epidemiology of Huntington disease, noting that prevalence is higher than previously thought, geographically variable and increasing. We describe the relationship between CAG repeat length and clinical phenotype, as well as the concept of genetic modifiers of the disease. We discuss normal huntingtin protein function, evidence for differential toxicity of mutant huntingtin variants, theories of huntingtin aggregation and the many different mechanisms of Huntington disease pathogenesis. We describe the genetic and clinical diagnosis of the condition, its clinical assessment and the multidisciplinary management of symptoms, given the absence of effective disease-modifying therapies. We review past and present clinical trials and therapeutic strategies under investigation, including impending trials of targeted huntingtin-lowering drugs and the progress in development of biomarkers that will support the next generation of trials. For an illustrated summary of this Primer, visit: http://go.nature.com/hPMENh