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Abstract

Background: Giant cell arteritis (GCA) is the most common form of vasculitis affecting elderly people. It is one of the few true ophthalmic emergencies but symptoms and signs are variable thereby making it a challenging disease to diagnose. A temporal artery biopsy is the gold standard to confirm GCA, but there are currently no specific biochemical markers to aid diagnosis. We aimed to identify a less invasive method to confirm the diagnosis of GCA, as well as to ascertain clinically relevant predictive biomarkers by studying the transcriptome of purified peripheral CD4+ and CD8+ T lymphocytes in patients with GCA.Methods: We recruited 16 patients with histological evidence of GCA at the Royal Victorian Eye and Ear Hospital, Melbourne, Australia, and aimed to collect blood samples at six time points: acute phase, 2-3 weeks, 6-8 weeks, 3 months, 6 months and 12 months after clinical diagnosis. CD4+ and CD8+ T-cells were positively selected at each time point through magnetic-assisted cell sorting. RNA was extracted from all 195 collected samples for subsequent RNA sequencing. The expression profiles of patients were compared to those of 16 age-matched controls.Results: Over the 12-month study period, polynomial modelling analyses identified 179 and 4 statistically significant transcripts with altered expression profiles (FDR SGTB, associated with neuronal apoptosis, and FCGR3A, associatied with Takayasu arteritis. We detected genes that correlate with both symptoms and biochemical markers used for predicting long-term prognosis. 15 genes were shared across 3 phenotypes in CD4 and 16 across CD8 cells. In CD8, IL32 was common to 5 phenotypes including Polymyalgia Rheumatica, bilateral blindness and death within 12 months.Conclusions: This is the first longitudinal gene expression study undertaken to identify robust transcriptomic biomarkers of GCA. Our results show cell type-specific transcript expression profiles, novel gene-phenotype associations, and uncover important biological pathways for this disease. In the acute phase, the gene-phenotype relationships we have identified could provide insight to potential disease severity and as such guide in initiating appropriate patient management.

Item Type:	Article
Authors/Creators:	De Smit, E and Lukowski, SW and Anderson, L and Senabouth, A and Dauyey, K and Song, S and Wyse, B and Wheeler, L and Chen, CY and Cao, K and Wong Ten Yuen, A and Shuey, N and Clarke, L and Lopez Sanchez, I and Hung, SSC and Pebay, A and Mackey, DA and Brown, MA and Hewitt, AW and Powell, JE
Keywords:	CD4 & CD8 T lymphocytes, disease biomarkers, expression profiling, giant cell arteritis, magnetic-assisted cell sorting, RNA sequencing, transcriptome
Journal or Publication Title:	BMC Medical Genomics
Publisher:	BioMed Central Ltd.
ISSN:	1755-8794
DOI / ID Number:	https://doi.org/10.1186/s12920-018-0376-4
Copyright Information:	Copyright 2018 The AuthorsLicensed under Creative Commons Attribution 4.0 International (CC BY 4.0)https://creativecommons.org/licenses/by/4.0/
Related URLs:	Google Scholar: Hewitt, AW UTAS Profile: Hewitt, AW
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