How Do Bone Marrow Lesions Cause Osteoarthritis Pain? a Structural and Functional Tissue-Based Study

Background/Purpose: Susceptibility to ankylosing spondylitis (AS) is primarily genetic; thus far 113 susceptibility variants for AS have been identified. However, most of the AS associated SNPs do not directly affect protein-coding genes. Studies of disease- and trait-associated SNPs suggest they may act by affecting gene regulatory regions in specific cell types or tissues. Therefore, identifying the AS relevant cell types is crucial for further mechanistic studies. Methods: We applied several bioinformatics methods to utilize epigenetic, gene and protein expression information to identify the primary relevant cell types through which genetic variants associated with AS operate. In total, there are 113 AS associated loci; 39 of them show genome-wide significance in AS-only analyses, whereas the remainder are genome-wide significant in analyses leveraging pleiotrophy with other related diseases (Crohn’s disease (CD), psoriasis, primary sclerosing cholangitis (PSC) and ulcerative colitis (UC))1. Results: AS-associated SNPs are disproportionately found in regions bearing epigenetic marks indicating transcriptional activity found in immune cell types including monocytes, CD4+ and CD8+ T cells, NK cells, regulatory T cells, and B cells. Gene expression studies showed enrichment of AS associated loci in genes specifically expressed in monocytes and NK cells while protein expression study shows protein products of AS associated loci were significantly enriched in CD8+ T cells. Epigenetic analyses also showed evidence that AS-associated signals operate in gut cell types including in mucosa from the small intestine, sigmoid colon and rectum. These findings particularly relate to pleiotropic loci also associated with IBD, psoriasis, and PSC. Conclusion: These findings highlight the role of key immune cell types in the mechanism by which genetic associations with AS drive the disease, as well as providing further evidence for the involvement of the gut in the pathogenesis of AS. 1Ellinghaus D. at al, Nature Genetics 201

Health-related quality of life in ANCA-associated vasculitis and item generation for a disease-specific patient-reported outcome measure

Joanna C Robson,1,2 Jill Dawson,3 Peter F Cronholm,4 Nataliya Milman,5 Katherine S Kellom,6 Susan Ashdown,7 Ebony Easley,8 John T Farrar,9 Don Gebhart,10,11 Georgia Lanier,10,11 Carol A McAlear,12 Jacqueline Peck,7 Raashid A Luqmani,7 Judy A Shea,13 Gunnar Tomasson,14 Peter A Merkel10,11 1Department of Rheumatology, Faculty of Health and Applied Sciences, University of the West of England, Bristol, UK; 2School of Clinical Sciences, University of Bristol, Bristol, UK; 3Department of Population Health (HSRU), University of Oxford, Oxford, UK; 4Department of Family Medicine and Community Health, University of Pennsylvania, Philadelphia, PA, USA; 5Division of Rheumatology, Department of Medicine, University of Ottawa, Ottawa Hospital Research Institute, Ottawa, ON, Canada; 6PolicyLab, Children’s Hospital of Philadelphia, Philadelphia, PA, USA; 7Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK; 8Department of Family Medicine and Community Health, Mixed Methods Research Laboratory, University of Pennsylvania, Philadelphia, PA, USA; 9Biostatistics and Epidemiology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA; 10Division of Rheumatology, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA; 11Department of Biostatistics and Clinical Epidemiology, University of Pennsylvania, Philadelphia, PA, USA; 12Vasculitis Research, University of Pennsylvania, Philadelphia, PA, USA; 13School of Medicine, University of Pennsylvania, Philadelphia, PA, USA; 14Department of Public Health Sciences, University of Iceland, Reykjavik, Iceland Objective: The antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs) are multisystem diseases of the small blood vessels. Patients experience irreversible damage and psychological effects from AAV and its treatment. An international collaboration was created to investigate the impact of AAV on health-related quality of life (HRQoL), and develop a disease-specific patient-reported outcome measure to assess outcomes of importance to patients.Methods: Patients with AAV from the UK, USA, and Canada were interviewed to identify salient aspects of HRQoL affected by AAV. The study was overseen by a steering committee including four patient research partners. Purposive sampling of interviewees ensured representation of a range of disease manifestations and demographics. Inductive analysis was used to identify themes of importance to patients; these were further confirmed by a free-listing exercise in the US. Individual themes were recast into candidate items, which were scrutinized by patients, piloted through cognitive interviews and received a linguistic and translatability evaluation.Results: Fifty interviews, conducted to saturation, with patients from the UK, USA, and Canada, identified 55 individual themes of interest within seven broad domains: general health perceptions, impact on function, psychological perceptions, social perceptions, social contact, social role, and symptoms. Individual themes were constructed into >100 candidate questionnaire items, which were then reduced and refined to 35 candidate items.Conclusion: This is the largest international qualitative analysis of HRQoL in AAV to date, and the results have underpinned the development of 35 candidate items for a disease-specific, patient-reported outcome questionnaire. Keywords: ANCA-associated vasculitis, quality of life, patient-reported outcomes, granulomatosis with polyangiitis, microscopic polyangiitis, eosinophilic granulomatosis with polyangiiti