Abstract Body: Background
Atherosclerosis is a chronic inflammation characterized by accumulation of immune cells, oxidized low density lipoprotein (OxLDL) and dead cells in the lesions, both of the latter have the hapten phosphorylcholine (PC) as an important antigen. PC is also exposed on microorganisms and other compounds and needs a carrier to be antigenic. Antibodies against PC (anti-PC) ameliorates deleterious effects of both OxLDL and dead cells. Oxidized-1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphatidylcholine (Ox-PAPC) is a major compound in the lipid moiety of OxLDL exposing PC.
Methods
We studied effect of Ox-PAPC and PC with keyhole limpet cyanid (KLH) on T cells, dendritic cells (DC) and macrophages (MQ). We examined the influence of Ox-PAPC and PC conjugated to KLH (PC-KLH) on T cells, DC, and MQ from peripheral blood or atherosclerotic plaques.
We investigated phospholipid and glutathione (GSH) levels in the blood plasma of healthy controls (n=30) and patients (n=30).
Results
Ox-PAPC, in contrast to PAPC and PC-KLH, independently of DC, induced proinflammatory T cell activation, which was inhibited by mito tempo, inhibitor of reactive oxygen species (ROS). Ox-PAPC triggered inflammatory activities while reducing metabolic activities in T cells. PC-KLH, on the other hand, reduced CD86 and CD11C, proinflammatory cytokines, and induced anti-inflammatory IL-10 in DC. Ox-PAPC induced ROS, GSH, and proinflammatory MQ activation, inhibited by Mito tempo or GSH inhibitor. Additionally, Ox-PAPC, in the presence of PCSK9, elevated CD86 expression and lipid peroxidation. Patients exhibited higher GSH levels comapre to control groups, associated with phospholipid levels.
Conclusions
The study reveals the differential effects of Ox-PAPC on various immune cell types, showcasing T cell activation independent of DC and heightened macrophage activation in the presence of PCSK9. Ox-PAPC-induced redox imbalance regulates T cell activation, apoptosis, and MQ activation, potentially rendering plaques more vulnerable and contributing to lesion formation and thus plaque rupture. In contrast, PC-KLH had anti-inflammatory effects, inducing anti-inflammatory cytokines from T cells, DC and MQ. PC-effects thus vary from proinflammatory to anti-inflammatory depending on presentation. Inhibition of OxPAPC effects by agents such as anti-PC could thus be anti-atherogenic, while on the other hand PC presented on a protein as KLH could be anti-atherogenic and anti-inflammatory itself.