Increased LL37 in psoriasis and other inflammatory disorders promotes low-density lipoprotein uptake and atherosclerosis

Patients with chronic inflammatory disorders such as psoriasis have an increased risk of cardiovascular disease and elevated levels of LL37, a cathelicidin host defense peptide that has both antimicrobial and proinflammatory properties. To explore if LL37 could contribute to the risk of heart disease, we examined its effects on lipoprotein metabolism and show that LL37 enhances LDL uptake in macrophages through LDLR, SR-B1 and CD36. This interaction led to increased cytosolic cholesterol in macrophages and changes in expression of lipid metabolism genes consistent with increased cholesterol uptake. Structure-function analysis and synchrotron small angle X-ray scattering show structural determinants of the LL37-LDL complex that underlie its ability to bind its receptors and promote uptake. This function of LDL uptake is unique to cathelicidins from humans and some primates and was not observed with cathelicidins from mice or rabbits. Notably, Apoe-/- mice expressing LL37 develop larger atheroma plaques than control mice and a positive correlation between plasma LL37 and OxPL-apoB levels was observed in human subjects with cardiovascular disease. These findings provide evidence that LDL uptake can be increased via interaction with LL37 and may explain the increased risk of cardiovascular disease associated with the chronic inflammatory disorders.