Monosodium urate crystals (MSU) activate inflammatory immune cells (e.g. monocytes/neutrophils), which potentiate acute gout attacks. Ultrasound and dual energy CT scans have shown the presence of MSU crystal deposits in joints of asymptomatic gout patients. These observations lead experts to agree that other unknown molecular factors are triggers for gout and recurrent flares. Our ancillary project's aims address two main questions: 1) Do neutrophils and/or monocytes, upon ex vivo activation by MSU crystals, exhibit gene expression and DNA methylation differences between gout patients with recurrent gout flares compared to those that do not? 2) Among gout patients from a clinical trial setting, where treat-to-target urate lowering therapy (ULT) is administered, are there gene expression and DNA methylation differences from the peripheral blood between individuals with or without recurrent flares? In aim 1 in a mechanistic/functional approach we will isolate neutrophils and CD14+ monocytes using fresh samples of peripheral blood from gout patients newly recruited into UAB's Gout Registry, the time sensitive parent project for this R01. The UAB Gout Registry is administered by UAB's NIAMS funded Center of Research Translation (CORT) ?INvestigationS In Gout, Hyperuricemia, and comorbidiTies (INSIGHT)? (NIH P50 060772), which is the parent project for our ancillary study. The cells will be activated with MSU and we will use RNAseq to compare gene expression between groups (recurrent flares vs no flares). We will determine whether DNA methylation changes may be associated with observed transcription differences.
In aim 2 we will utilize clinical data and biological samples from the clinical trial, VA-CSP594, the ?Stop Gout? trial. The trial is a non-inferiority comparison between the ULT agents, febuxostat and allopurinol, of the primary outcome, the proportion of participants who flare at least once. The Stop Gout trial organizers agreed to augment their biospecimen collection to allow the collection of RNA for our ancillary study. We will analyze ~300 samples of RNA from the trial's participants. We will compare baseline gene expression and DNA methylation associations with recurrent flares. We will utilize Mendelian randomization to assess the causality of differentially methylated CpGs and expressed transcripts with recurrent gout flares. The results from aims 1 and 2 will expand our knowledge of the transcriptomic and methylomic changes that precipitate gout flares, which will translate to improved gout patient care and treatment.
PROJECT NARATIVE Leading experts agree that unknown molecular factors may trigger individuals with gout to have recurrent flares, therefore we propose to quantify the epigenetic and transcriptional activity of genes within specific inflammatory cell types and to compare these between gout patients that subsequently flare and those that do not flare. We will use biological samples from two cohorts of gout patients: The first from the University of Alabama at Birmingham NIAMS funded P50 INSIGHT CORT and the second from the Veterans Administration ?Stop Gout? clinical trial (VA-CSP 594). We will gain new knowledge of the transcriptional and epigenetic triggers of gout flares that may translate to improved care and treatment of gout patients.