Genome-wide Pleiotropy Between Parkinson Disease and Autoimmune Diseases.
Oslo University Hospital1, VU University Medical Center2, University of California, San Diego3, National Institutes of Health4, German Center for Neurodegenerative Diseases5, University of Oslo6, University of Kiel7, Pierre-and-Marie-Curie University8, University College London9, University of Tübingen10
TL;DR: The study findings provide novel mechanistic insights into PD and autoimmune diseases and identify a common genetic pathway between these phenotypes, which may have implications for future therapeutic trials involving anti-inflammatory agents.
Abstract: Importance Recent genome-wide association studies (GWAS) and pathway analyses supported long-standing observations of an association between immune-mediated diseases and Parkinson disease (PD). The post-GWAS era provides an opportunity for cross-phenotype analyses between different complex phenotypes. Objectives To test the hypothesis that there are common genetic risk variants conveying risk of both PD and autoimmune diseases (ie, pleiotropy) and to identify new shared genetic variants and their pathways by applying a novel statistical framework in a genome-wide approach. Design, Setting, and Participants Using the conjunction false discovery rate method, this study analyzed GWAS data from a selection of archetypal autoimmune diseases among 138 511 individuals of European ancestry and systemically investigated pleiotropy between PD and type 1 diabetes, Crohn disease, ulcerative colitis, rheumatoid arthritis, celiac disease, psoriasis, and multiple sclerosis. NeuroX data (6927 PD cases and 6108 controls) were used for replication. The study investigated the biological correlation between the top loci through protein-protein interaction and changes in the gene expression and methylation levels. The dates of the analysis were June 10, 2015, to March 4, 2017. Main Outcomes and Measures The primary outcome was a list of novel loci and their pathways involved in PD and autoimmune diseases. Results Genome-wide conjunctional analysis identified 17 novel loci at false discovery rate less than 0.05 with overlap between PD and autoimmune diseases, including known PD loci adjacent to GAK , HLA-DRB5 , LRRK2 , and MAPT for rheumatoid arthritis, ulcerative colitis and Crohn disease. Replication confirmed the involvement of HLA , LRRK2 , MAPT , TRIM10 , and SE TD1A in PD. Among the novel genes discovered, WNT3 , KANSL1 , CRHR1 , BOLA2 , and GUCY1A3 are within a protein-protein interaction network with known PD genes. A subset of novel loci was significantly associated with changes in methylation or expression levels of adjacent genes. Conclusions and Relevance The study findings provide novel mechanistic insights into PD and autoimmune diseases and identify a common genetic pathway between these phenotypes. The results may have implications for future therapeutic trials involving anti-inflammatory agents.
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TL;DR: A systematic review of the cellular mediators, i.e., microglia, astroglia and endothelial cells, and the genetic and transcriptional control of inflammation in PD and the immunomodulatory role of dopamine and reactive oxygen species is provided.
Abstract: Parkinson’s disease (PD) is a common neurodegenerative disorder primarily characterized by the death of dopaminergic neurons that project from the substantia nigra pars compacta. Although the molecular bases for PD development are still little defined, extensive evidence from human samples and animal models support the involvement of inflammation in onset or progression. However, the exact trigger for this response remains unclear. Here, we provide a systematic review of the cellular mediators, i.e., microglia, astroglia and endothelial cells. We also discuss the genetic and transcriptional control of inflammation in PD and the immunomodulatory role of dopamine and reactive oxygen species. Finally, we summarize the preclinical and clinical approaches targeting neuroinflammation in PD.
240 citations
TL;DR: A higher incidence of PD was observed among patients with IBD than among individuals without IBD, and early exposure to antiinflammatory anti-TNF therapy was associated with substantially reduced PD incidence, suggesting a role of systemic inflammation in the pathogenesis of both diseases.
Abstract: Importance Despite established genetic and pathophysiologic links between inflammatory bowel disease (IBD) and Parkinson disease (PD), clinical data supporting this association remain scarce. Although systemic inflammation is considered a potential biological mechanism shared between the 2 diseases, the role of reduced systemic inflammation through IBD-directed anti–tumor necrosis factor (anti-TNF) therapy in PD risk is largely unknown. Objective To compare the incidence of PD among individuals with or without IBD and to assess whether PD risk among patients with IBD is altered by anti-TNF therapy. Design, Setting, and Participants This is a retrospective cohort study analyzing information in the Truven Health MarketScan administrative claims database and the Medicare Supplemental Database between January 1, 2000, and March 31, 2016. Individuals were selected who had at least 2 claims for IBD diagnoses, at least 6 months of follow-up, and no prior diagnosis of PD on or before the IBD index date. Exposure to Anti-TNF therapy was measured from the anti-TNF index date to the last date of anti-TNF coverage or the end of enrollment or PD index date, whichever was earliest. Incidence rates per 1000 person-years were calculated, and crude and adjusted incidence rate ratios were estimated by Poisson regression models and presented with 95% CIs. Main Outcomes and Measures Incidence of PD among patients with IBD with or without exposure to anti-TNF therapy. Results In total, 144 018 individuals with IBD were matched on age, sex, and year of index date with 720 090 unaffected controls. Of them, 1796 individuals had at least 2 PD diagnoses and at least 1 filled PD-related prescription. The mean (SD) age of individuals with IBD was 51 (17) years, and 44% were men. The incidence of PD among patients with IBD was 28% higher than that among unaffected matched controls (adjusted incidence rate ratio, 1.28; 95% CI, 1.14-1.44;P Conclusions and Relevance A higher incidence of PD was observed among patients with IBD than among individuals without IBD. Early exposure to antiinflammatory anti-TNF therapy was associated with substantially reduced PD incidence. These findings support a role of systemic inflammation in the pathogenesis of both diseases. Further studies are required to determine whether anti-TNF treatment administered to high-risk individuals may mitigate PD risk.
230 citations
TL;DR: An overview of the clinical and preclinical evidence that immune system dysfunction is involved in Parkinson disease is provided, and how increasing knowledge of the underlying mechanisms is driving development of immune-based therapeutic approaches is discussed.
Abstract: Multiple lines of evidence indicate that immune system dysfunction has a role in Parkinson disease (PD); this evidence includes clinical and genetic associations between autoimmune disease and PD, impaired cellular and humoral immune responses in PD, imaging evidence of inflammatory cell activation and evidence of immune dysregulation in experimental models of PD. However, the mechanisms that link the immune system with PD remain unclear, and the temporal relationships of innate and adaptive immune responses with neurodegeneration are unknown. Despite these challenges, our current knowledge provides opportunities to develop immune-targeted therapeutic strategies for testing in PD, and clinical studies of some approaches are under way. In this Review, we provide an overview of the clinical observations, preclinical experiments and clinical studies that provide evidence for involvement of the immune system in PD and that help to define the nature of this association. We consider autoimmune mechanisms, central and peripheral inflammatory mechanisms and immunogenetic factors. We also discuss the use of this knowledge to develop immune-based therapeutic approaches, including immunotherapy that targets α-synuclein and the targeting of immune mediators such as inflammasomes. We also consider future research and clinical trials necessary to maximize the potential of targeting the immune system. In this Review, Tan et al. provide an overview of the clinical and preclinical evidence that immune system dysfunction is involved in Parkinson disease, and discuss how increasing knowledge of the underlying mechanisms is driving development of immune-based therapeutic approaches.
219 citations
TL;DR: Parkinson disease (PD) is a progressive neurodegenerative disease that affects peripheral organs as well as the central nervous system and involves a fundamental role of neuroinflammation in its pathophysiology as mentioned in this paper .
Abstract: Parkinson disease (PD) is a progressive neurodegenerative disease that affects peripheral organs as well as the central nervous system and involves a fundamental role of neuroinflammation in its pathophysiology. Neurohistological and neuroimaging studies support the presence of ongoing and end-stage neuroinflammatory processes in PD. Moreover, numerous studies of peripheral blood and cerebrospinal fluid from patients with PD suggest alterations in markers of inflammation and immune cell populations that could initiate or exacerbate neuroinflammation and perpetuate the neurodegenerative process. A number of disease genes and risk factors have been identified as modulators of immune function in PD and evidence is mounting for a role of viral or bacterial exposure, pesticides and alterations in gut microbiota in disease pathogenesis. This has led to the hypothesis that complex gene-by-environment interactions combine with an ageing immune system to create the 'perfect storm' that enables the development and progression of PD. We discuss the evidence for this hypothesis and opportunities to harness the emerging immunological knowledge from patients with PD to create better preclinical models with the long-term goal of enabling earlier identification of at-risk individuals to prevent, delay and more effectively treat the disease.
204 citations
TL;DR: This nationwide, unselected, cohort study shows a significant association between IBD and later occurrence of PD, which is consistent with recent basic scientific findings of a potential role of GI inflammation in development of parkinsonian disorders.
Abstract: Objective Intestinal inflammation has been suggested to play a role in development of Parkinson’s disease (PD) and multiple system atrophy (MSA). To test the hypothesis that IBD is associated with risk of PD and MSA, we performed a nationwide population-based cohort study. Design The cohort consisted of all individuals diagnosed with IBD in Denmark during 1977–2014 (n=76 477) and non-IBD individuals from the general population, who were comparable in terms of gender, age and vital status (n=7 548 259). All cohort members were followed from IBD diagnosis/index date to occurrence of PD and MSA (according to the Danish National Patient Register). Results Patients with IBD had a 22% increased risk of PD as compared with non-IBD individuals (HR=1.22; 95% CI 1.09 to 1.35). The increased risk was present independently of age at IBD diagnosis, gender or length of follow-up. The overall incidence of MSA was low in our study, and the regression analysis suggested a tendency towards higher risk of developing MSA in patients with IBD as compared with non-IBD individuals (HR=1.41; 95% CI 0.82 to 2.44). Estimates were similar for women and men. The increased risk of parkinsonism was significantly higher among patients with UC (HR=1.35; 95% CI 1.20 to 1.52) and not significantly different among patients with Crohn’s disease (HR=1.12; 95% CI 0.89 to 1.40). Conclusions This nationwide, unselected, cohort study shows a significant association between IBD and later occurrence of PD, which is consistent with recent basic scientific findings of a potential role of GI inflammation in development of parkinsonian disorders.
197 citations
References
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TL;DR: H hierarchical and self-consistent orthology annotations are introduced for all interacting proteins, grouping the proteins into families at various levels of phylogenetic resolution in the STRING database.
Abstract: The many functional partnerships and interactions that occur between proteins are at the core of cellular processing and their systematic characterization helps to provide context in molecular systems biology. However, known and predicted interactions are scattered over multiple resources, and the available data exhibit notable differences in terms of quality and completeness. The STRING database (http://string-db.org) aims to provide a critical assessment and integration of protein-protein interactions, including direct (physical) as well as indirect (functional) associations. The new version 10.0 of STRING covers more than 2000 organisms, which has necessitated novel, scalable algorithms for transferring interaction information between organisms. For this purpose, we have introduced hierarchical and self-consistent orthology annotations for all interacting proteins, grouping the proteins into families at various levels of phylogenetic resolution. Further improvements in version 10.0 include a completely redesigned prediction pipeline for inferring protein-protein associations from co-expression data, an API interface for the R computing environment and improved statistical analysis for enrichment tests in user-provided networks.
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TL;DR: By better understanding AD inflammatory and immunoregulatory processes, it should be possible to develop anti-inflammatory approaches that may not cure AD but will likely help slow the progression or delay the onset of this devastating disorder.
4,319 citations
Tanya M. Teslovich1, Kiran Musunuru, Albert V. Smith2, Andrew C. Edmondson3 +215 more•Institutions (46)
TL;DR: The results identify several novel loci associated with plasma lipids that are also associated with CAD and provide the foundation to develop a broader biological understanding of lipoprotein metabolism and to identify new therapeutic opportunities for the prevention of CAD.
Abstract: Plasma concentrations of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides are among the most important risk factors for coronary artery disease (CAD) and are targets for therapeutic intervention. We screened the genome for common variants associated with plasma lipids in >100,000 individuals of European ancestry. Here we report 95 significantly associated loci (P < 5 x 10(-8)), with 59 showing genome-wide significant association with lipid traits for the first time. The newly reported associations include single nucleotide polymorphisms (SNPs) near known lipid regulators (for example, CYP7A1, NPC1L1 and SCARB1) as well as in scores of loci not previously implicated in lipoprotein metabolism. The 95 loci contribute not only to normal variation in lipid traits but also to extreme lipid phenotypes and have an impact on lipid traits in three non-European populations (East Asians, South Asians and African Americans). Our results identify several novel loci associated with plasma lipids that are also associated with CAD. Finally, we validated three of the novel genes-GALNT2, PPP1R3B and TTC39B-with experiments in mouse models. Taken together, our findings provide the foundation to develop a broader biological understanding of lipoprotein metabolism and to identify new therapeutic opportunities for the prevention of CAD.
3,469 citations
University of Oxford1, Wellcome Trust Centre for Human Genetics2, University of Michigan3, Fred Hutchinson Cancer Research Center4, Duke University5, University of Ottawa6, Foundation for Research & Technology – Hellas7, Tufts University8, Harvard University9, Boston Children's Hospital10, Broad Institute11
TL;DR: This Review highlights the knowledge gained, defines areas of emerging consensus, and describes the challenges that remain as researchers seek to obtain more complete descriptions of the susceptibility architecture of biomedical traits of interest and to translate the information gathered into improvements in clinical management.
Abstract: The past year has witnessed substantial advances in understanding the genetic basis of many common phenotypes of biomedical importance. These advances have been the result of systematic, well-powered, genome-wide surveys exploring the relationships between common sequence variation and disease predisposition. This approach has revealed over 50 disease-susceptibility loci and has provided insights into the allelic architecture of multifactorial traits. At the same time, much has been learned about the successful prosecution of association studies on such a scale. This Review highlights the knowledge gained, defines areas of emerging consensus, and describes the challenges that remain as researchers seek to obtain more complete descriptions of the susceptibility architecture of biomedical traits of interest and to translate the information gathered into improvements in clinical management.
2,908 citations
TL;DR: High-resolution recombination mapping and candidate gene sequencing in 46 families found six disease-segregating mutations in a gene encoding a large, multifunctional protein, LRRK2 (leucine-rich repeat kinase 2), which may be central to the pathogenesis of several major neurodegenerative disorders associated with parkinsonism.
2,757 citations