Investigating the role of microRNA in inflammatory cytokine production of macrophages in rheumatoid arthritis

Rainey, Ashleigh-Ann (2015) Investigating the role of microRNA in inflammatory cytokine production of macrophages in rheumatoid arthritis. PhD thesis, University of Glasgow.

Abstract

Rheumatoid Arthritis (RA) is a chronic systemic inflammatory disease, which targets the synovial membrane and joints of patients, resulting in irreversible bone damage, and disability. The development of new treatments for RA is limited by our incomplete understanding of disease pathogenesis. Macrophages are critically important in the pathogenesis of RA due to their ability to initiate and amplify both systemic inflammation and local tissue damage through the production of cytokines such as Tumour necrosis factor (TNF) α and Interleukin (IL)-6. Our understanding of the molecular mechanisms underlying monocyte and macrophage activation in arthritis remains unclear. MicroRNAs (miRs) are a novel class of post-transcriptional regulators. They are short, non-coding RNA molecules that bind to complementary sequences, typically in the 3’untranslated region (UTR) of target genes, resulting in mRNA degradation or sequestration. miRs have been shown to impact various aspects of mammalian biology including cell proliferation, differentiation and the immune response. We identified a miR profile of SF CD14+ cells in RA. The majority of this study concentrated on miR-125a which was shown to be upregulated in SF CD14+ cells and PB CD14+ cells of patients who responded well to cDMARD therapy when compared to healthy controls. Using miR sponge technology we generated macrophage like, miR-125a null cells, and demonstrated that these cells display a hyper inflammatory response to LPS by producing significantly higher levels of TNFα, IL-6, CCL4 and CCL5 when compared to a reporter control. This phenotype was confirmed in primary human macrophages in which miR-125a was inhibited. These cells produced significantly higher levels of TNFα, IL-6, IL-12, CCL4 and lower levels of anti-inflammatory IL-10. Prediction algorithms identified members of the Toll Like Receptor 4 (TLR4) signalling pathway and inflammatory cytokines as potential miR-125a targets. Interestingly, overexpression of miR-125a in primary human macrophages resulted in increased IL-10 production, but also increased TNFα production, highlighting the complicated nature of miR regulation. This study has identified miR-125a as a potential negative regulator of macrophage activation, which may be impaired at sites of chronic inflammation. Future work will therefore aim to characterise the pathways regulated by this miR in macrophages, and the relationship to their activation within the RA joint.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Rheumatoid Arthritis, microRNA, miR, macrophage
• Subjects: Q Science > Q Science (General); Q Science > QR Microbiology > QR180 Immunology
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Infection & Immunity > Immunology & Infection
• Supervisor's Name: Iain, Prof McInnes and Mariola, Dr Kurowska-Stolarska
• Date of Award: 2015
• Depositing User: Miss Ashleigh Rainey
• Unique ID: glathesis:2015-6418
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 03 Jun 2015 08:26
• Last Modified: 27 Jun 2016 09:56
• URI: https://theses.gla.ac.uk/id/eprint/6418