The relationship between inflammatory cytokines, dyslipidemia, and disease extends from rheumatoid arthritis (RA) to diabetes, obesity, atherosclerosis, and beyond. Dyslipidemia is traditionally thought of as an important risk factor for cardiovascular disease (CVD), highlighting it for rheumatologists, since CVD is the main cause of death in patients with RA. Studies have also shown that dyslipidemia is more common in patients with RA than in the general population. The increased prevalence of dyslipidemia in RA is believed to be due to the inflammatory activity associated with RA, although scientists have yet to correlate dyslipidemia with RA severity and prognosis.
A new study investigates the relationship between cumulative lipid burden and radiographic severity and progression in patients with RA over a two-year period. The results suggest that patients diagnosed with RA as well as dyslipidemia may benefit from more aggressive antirheumatic therapy.
Yune-Jung Park, MD, a researcher in the division of rheumatology at the Catholic University of Korea in Seoul, and colleagues published the results of their longitudinal study in PLOS ONE. They evaluated patients with RA who had persistently higher low-density lipoprotein (LDL) cholesterol levels and were in a persistently elevated inflammatory state. The authors used time-integrated values to estimate cumulative lipid burden in the patient population. They also measured levels of the immune-modifying adipokine leptin that has also been identified as playing a role in RA and other diseases.
The investigators found that cumulative LDL cholesterolemia and triglyceridemia were associated with elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels. Patients with higher LDL cholesterol and/or triglyceride levels had higher disease activity parameters: Disease Activity Score 28 (DAS28), serum adipokine levels, and radiographic severity. The authors identified a particularly close relationship between LDL cholesterol levels and serum leptin concentrations.
“In the present study, LDL cholesterolemia remained significant as a prognostic factor, even after adjusting for inflammatory burden (e.g., time-integrated ESR/CRP levels), indicating that dyslipidemia itself contributed to radiographic progression in our patients,” the authors explain in their discussion.
Their results suggest that dyslipidemia, inflammatory activity, and RA disease progression are all intertwined. “Lipid-lowering therapy may be protective against RA development, reducing disease activity and the number of swollen joints,” added lead investigator Wan-Uk Kim, MD, PhD, also of the Catholic University of Korea, in an e-mail to The Rheumatologist.
The results follow on the heels of genetic studies by the same group. “Previously, our group also postulated that there could be common genetic mechanism(s) that can simultaneously increase the susceptibility of both dyslipidemia and RA. We investigated if LDL cholesterol single-nucleotide polymorphisms could affect susceptibility, severity, and progression of RA. We demonstrated, for the first time, that LDL cholesterol polymorphisms (rs688 and rs4420638), regarded as irrelevant before, were actually involved in susceptibility to RA. In RA patients carrying more unfavorable alleles, disease activity parameters including DAS28, serum adipokine levels, and radiographic severity were all increased,” explained Dr. Kim.
