Small dense LDL cholesterol in human subjects with different chronic inflammatory diseases

Chronic inflammatory diseases (CID) are associated with a profound increase in cardiovascular (CV) risk resulting in reduced life expectancy. However, LDL-cholesterol is reported to be low in CID patients which is referred to as the "LDL paradoxon". The aim of the present study was to investigate whether LDL-particles in CID exhibit an increased content of the highly atherogenic small-dense LDL subfraction (sdLDL).

In this prospective, single center, observational study we enrolled 141 patients with CID (RA n = 59, inflammatory bowel disease (IBD) n = 35, ankylosing spondylitis (SpA) n = 25, Psoriasis n = 22) in 2011 through 2013 to evaluate sdLDL levels before as well as 6 and 26 weeks after initiation of different anti-cytokine therapies (anti-TNFα, anti-IL-6R antibodies). sdLDL levels were compared to 141 healthy individuals in a case control design. Compared to healthy controls, all CID patients displayed a significantly higher sdLDL content within the LDL cholesterol fraction: RA 35.0 ± 9.2% (p < 0.001), SpA 42.5 ± 10.5% (p < 0.001), IBD 37.5 ± 7.1% (p < 0.001), Psoriasis 33.6 ± 4.6% (p < 0.01). Furthermore, the sdLDL/LDL ratio was significantly higher in male compared to female RA subjects (p < 0.05). Neither anti-TNFα nor anti-IL6R medication altered sdLDL levels despite a significant improvement of disease activity.

In several different chronic inflammatory disease entities, LDL-cholesterol is shifted toward a pro-atherogenic phenotype due to an increased sdLDL content which might in part explain the LDL paradoxon. Since premature CV disease is a major burden of affected patients, specifically targeting lipid metabolism should be considered routinely in clinical patient care.

Registration at German Clinical Trial Register (DRKS): DRKS00005285.