Canadian Adalimumab Postmarketing Observational Epidemiological Study Assessing Effectiveness in Psoriatic Arthritis (COMPLETE-PsA): 12-month Results of Comparative Effectiveness of Adalimumab and nbDMARDs.

OBJECTIVE: COMPLETE-PsA was an observational study of biologic-naïve Canadian adults with active psoriatic arthritis (PsA) treated with adalimumab (ADA) or a nonbiologic disease-modifying antirheumatic drug (nbDMARD) regimen, after inadequate response/intolerance to a current nbDMARD treatment regimen. The aim of this analysis was to assess the 12-month effectiveness of ADA vs nbDMARDs. METHODS: Patients enrolled between March 2012 and November 2017 were included. The following clinical variables and patient-reported outcomes were collected/calculated per routine care: Disease Activity Index for Psoriatic Arthritis in 28 joints (DAPSA28), Disease Activity Score in 28 joints (DAS28), erythrocyte sedimentation rate (ESR), C-reactive protein, physician global assessment (PGA), patient global assessment (PtGA), pain, Health Assessment Questionnaire-Disability Index (HAQ-DI), 12-item Short Form Health Survey, enthesitis, dactylitis, body surface area (BSA), and time to achieving American College of Rheumatology (ACR) 50, ACR70, and modified minimal disease activity (mMDA). RESULTS: Two hundred and seventy-seven ADA-treated and 148 nbDMARD-treated patients were included. At baseline, ADA-treated patients were less likely to be employed, had longer morning stiffness, higher DAPSA28, DAS28, PGA, PtGA, pain, and HAQ-DI, and lower prevalence of dactylitis (all P < 0.05). ADA-treated patients showed lower baseline-adjusted DAPSA28 (16.5 vs 26.6), DAS28 (2.8 vs 3.9), PGA (25.3 vs 37.1), and ESR (10.4 vs 15.0 mm/h) after 3 months compared to nbDMARD-treated patients, with observed improvements maintained to month 12. Time to achievement of ACR50, ACR70, and mMDA was significantly shorter (P < 0.001) among ADA-treated patients, with the likelihood of having dactylitis (odds ratio [OR] 0.4, 95% CI 0.2-0.6) and BSA< 3% (OR 2.7, 95% CI 1.5-5.0) significantly lower and higher, respectively. Switching to another biologic was less likely in ADA-treated vs nbDMARD-treated patients (hazard ratio 0.3, 95% CI 0.2-0.5). CONCLUSION: In a real-world Canadian population of patients with PsA, ADA was more effective than nbDMARDs at reducing disease activity and the severity of skin involvement, and demonstrated higher retention. [ClinicalTrials.gov: NCT01559038].

Post-translational modifications clustering within proteolytic domains decrease mutant huntingtin toxicity.

Huntington's disease (HD) is caused in large part by a polyglutamine expansion within the huntingtin (Htt) protein. Post-translational modifications (PTMs) control and regulate many protein functions and cellular pathways, and PTMs of mutant Htt are likely important modulators of HD pathogenesis. Alterations of selected numbers of PTMs of Htt fragments have been shown to modulate Htt cellular localization and toxicity. In this study, we systematically introduced site-directed alterations in individual phosphorylation and acetylation sites in full-length Htt constructs. The effects of each of these PTM alteration constructs were tested on cell toxicity using our nuclear condensation assay and on mitochondrial viability by measuring mitochondrial potential and size. Using these functional assays in primary neurons, we identified several PTMs whose alteration can block neuronal toxicity and prevent potential loss and swelling of the mitochondria caused by mutant Htt. These PTMs included previously described sites such as serine 116 and newly found sites such as serine 2652 throughout the protein. We found that these functionally relevant sites are clustered in protease-sensitive domains throughout full-length Htt. These findings advance our understanding of the Htt PTM code and its role in HD pathogenesis. Because PTMs are catalyzed by enzymes, the toxicity-modulating Htt PTMs identified here may be promising therapeutic targets for managing HD.

Post-Translational Modifications (PTMs), Identified on Endogenous Huntingtin, Cluster within Proteolytic Domains between HEAT Repeats.

Post-translational modifications (PTMs) of proteins regulate various cellular processes. PTMs of polyglutamine-expanded huntingtin (Htt) protein, which causes Huntington's disease (HD), are likely modulators of HD pathogenesis. Previous studies have identified and characterized several PTMs on exogenously expressed Htt fragments, but none of them were designed to systematically characterize PTMs on the endogenous full-length Htt protein. We found that full-length endogenous Htt, which was immunoprecipitated from HD knock-in mouse and human post-mortem brain, is suitable for detection of PTMs by mass spectrometry. Using label-free and mass tag labeling-based approaches, we identified near 40 PTMs, of which half are novel (data are available via ProteomeXchange with identifier PXD005753). Most PTMs were located in clusters within predicted unstructured domains rather than within the predicted α-helical structured HEAT repeats. Using quantitative mass spectrometry, we detected significant differences in the stoichiometry of several PTMs between HD and WT mouse brain. The mass-spectrometry identification and quantitation were verified using phospho-specific antibodies for selected PTMs. To further validate our findings, we introduced individual PTM alterations within full-length Htt and identified several PTMs that can modulate its subcellular localization in striatal cells. These findings will be instrumental in further assembling the Htt PTM framework and highlight several PTMs as potential therapeutic targets for HD.

Quantitative Proteomic Analysis Reveals Similarities between Huntington's Disease (HD) and Huntington's Disease-Like 2 (HDL2) Human Brains.

The pathogenesis of HD and HDL2, similar progressive neurodegenerative disorders caused by expansion mutations, remains incompletely understood. No systematic quantitative proteomics studies, assessing global changes in HD or HDL2 human brain, were reported. To address this deficit, we used a stable isotope labeling-based approach to quantify the changes in protein abundances in the cortex of 12 HD and 12 control cases and, separately, of 6 HDL2 and 6 control cases. The quality of the tissues was assessed to minimize variability due to post mortem autolysis. We applied a robust median sweep algorithm to quantify protein abundance and performed statistical inference using moderated test statistics. 1211 proteins showed statistically significant fold changes between HD and control tissues; the differences in selected proteins were verified by Western blotting. Differentially abundant proteins were enriched in cellular pathways previously implicated in HD, including Rho-mediated, actin cytoskeleton and integrin signaling, mitochondrial dysfunction, endocytosis, axonal guidance, DNA/RNA processing, and protein transport. The abundance of 717 proteins significantly differed between control and HDL2 brain. Comparative analysis of the disease-associated changes in the HD and HDL2 proteomes revealed that similar pathways were altered, suggesting the commonality of pathogenesis between the two disorders.

PRMT5- mediated symmetric arginine dimethylation is attenuated by mutant huntingtin and is impaired in Huntington's disease (HD).

Abnormal protein interactions of mutant huntingtin (Htt) triggered by polyglutamine expansion are thought to mediate Huntington's disease (HD) pathogenesis. Here, we explored a functional interaction of Htt with protein arginine methyltransferase 5 (PRMT5), an enzyme mediating symmetrical dimethylation of arginine (sDMA) of key cellular proteins, including histones, and spliceosomal Sm proteins. Gene transcription and RNA splicing are impaired in HD. We demonstrated PRMT5 and Htt interaction and their co-localization in transfected neurons and in HD brain. As a result of this interaction, normal (but to a lesser extend mutant) Htt stimulated PRMT5 activity in vitro. SDMA of histones H2A and H4 was reduced in the presence of mutant Htt in primary cultured neurons and in HD brain, consistent with a demonstrated reduction in R3Me2s occupancy at the transcriptionally repressed promoters in HD brain. SDMA of another PRMT5 substrate, Cajal body marker coilin, was also reduced in the HD mouse model and in human HD brain. Finally, compensation of PRMT5 deficiency by ectopic expression of PRMT5/MEP50 complexes, or by the knock-down of H4R3Me2 demethylase JMJD6, reversed the toxic effects of mutant Htt in primary cortical neurons, suggesting that PRMT5 deficiency may mediate, at least in part, HD pathogenesis. These studies revealed a potential new mechanism for disruption of gene expression and RNA processing in HD, involving a loss of normal function of Htt in facilitation of PRMT5, supporting the idea that epigenetic regulation of gene transcription may be involved in HD and highlighting symmetric dimethylation of arginine as potential new therapeutic target.