Dyslipidaemia in Rheumatoid Arthritis

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Abstract

Introduction: Rheumatoid arthritis (RA) is known to be associated with an increased risk of cardiovascular disease (CVD), resulting in excess mortality. Dyslipidaemia has been identified as a major CVD risk factor in the general population. Current evidence would suggest that lipid metabolism is altered in RA due to inflammation, and that use of anti-inflammatory therapy may reverse some of these changes. However, the impact of such lipid changes on CVD in RA remains unknown. Data regarding the effects of RA/drug therapy on lipid structure and function are sparse. Genetic factors are important in the pathogenesis of RA and play a central role in the regulation of lipid metabolism. To date, no studies have assessed the impact of genetic polymorphisms on lipids in RA.The aim of this thesis is to: 1) assess the prevalence of dyslipidaemia in RA and the CVD risk this confers 2) establish the effects of inflammation on lipid levels and lipid ratios 3) assess the impact of anti-inflammatory drug therapy (anti-TNF, rituximab and intravenous glucocorticoids) on lipid levels, structure and function 4) assess the prevalence and associations of particular genetic polymorphisms (RA susceptibility and lipid metabolism regulating genes) with lipids in RA.Methods: Data from 400 RA patients were used to address aims 1, 2 and 4 in cross-sectional studies. All patients had a clinical assessment and fasting blood taken. Blood was processed to provide data on the lipid profile, ESR, CRP and DNA was extracted for genotyping. Aim 2 and 4 also utilised a retrospective longitudinal cohort of 550 RA patients and the DNA from 400 healthy controls, respectively. Aim 3 was addressed using a longitudinal cohort including: patients due to commence anti-TNF (n=35), rituximab (n=10), intravenous glucocorticoids (n=12); 15 RA controls on stable therapy; and 40 healthy controls. Assessments and blood samples were taken at baseline, 2 weeks and 3 months.Results: Dyslipidaemia was highly prevalent (56.8%), but undertreated in many RA patients at risk of developing CVD. Systemic inflammation associated with many of the changes in lipid levels and structure. Lipid ratios were found to be less susceptible to fluctuations due to inflammation. The use of anti-inflammatory drug therapy produced changes in lipid structure and function through both generic suppression of inflammation and drug specific mechanisms (particularly in the case of glucocorticoids). The prevalence of cholesterol ester transfer protein (CETP) and Apolipoprotein C3 genetic polymorphisms differed between RA patients and local population controls. RA susceptibility genes (HLA-DRB1-SE and TRAF1C5) and several ’lipid metabolism genes’ (Apolipoprotein E, ATP-binding cassette transporter 1 (ABCA1) and CETP) were found to associate with lipid levels within the RA population. Conclusion: Dyslipidaemia is highly prevalent in RA and currently undertreated. Dyslipidaemia in RA is regulated by numerous factors including inflammation, drug therapy and genetic factors. Further longitudinal studies are required to assess whether these findings have an impact on hard CVD endpoints.

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Keyword(s)

Dyslipidaemia; Rheumatoid Arthritis

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