Neutrophil to lymphocyte ratio is not related to carotid atherosclerosis progression and cardiovascular events in the primary prevention of cardiovascular disease: Results from the IMPROVE study

Inflammation is a component of the pathogenesis of atherosclerosis and is associated with an increased risk of atherosclerotic cardiovascular disease (ASCVD). The neutrophil to lymphocyte ratio (NLR) is a possible inflammation metric for the detection of ASCVD risk, although results of prospective studies are highly inconsistent on this topic. We investigated the cross-sectional relationship between NLR and carotid intima-media thickness (cIMT) in subjects at moderate-to-high ASCVD risk. The prospective association between NLR, cIMT progression, and incident vascular events (VEs) was also explored. In 3341 subjects from the IMT-Progression as Predictors of VEs (IMPROVE) study, we analyzed the association between NLR, cIMT, and its 15-month progression. The association between NLR and incident VEs was also investigated. NLR was positively associated with cross-sectional measures of cIMT, but not with cIMT progression. The association between NLR and cross-sectional cIMT measures was abolished when adjusted for confounders. No association was found between NRL and incident VEs. Similarly, there were no significant differences in the hazard ratios (HRs) of VEs across NLR quartiles. NLR was neither associated with the presence and progression of carotid atherosclerosis, nor with the risk of VEs. Our findings do not support the role of NLR as a predictor of the risk of atherosclerosis progression and ASCVD events in subjects at moderate-to-high ASCVD risk, in primary prevention. However, the usefulness of NLR for patients at a different level of ASCVD risk cannot be inferred from this study.

Mapping of 79 loci for 83 plasma protein biomarkers in cardiovascular disease

Recent advances in highly multiplexed immunoassays have allowed systematic large-scale measurement of hundreds of plasma proteins in large cohort studies. In combination with genotyping, such studies offer the prospect to 1) identify mechanisms involved with regulation of protein expression in plasma, and 2) determine whether the plasma proteins are likely to be causally implicated in disease. We report here the results of genome-wide association (GWA) studies of 83 proteins considered relevant to cardiovascular disease (CVD), measured in 3,394 individuals with multiple CVD risk factors. We identified 79 genome-wide significant (p<5e-8) association signals, 55 of which replicated at P<0.0007 in separate validation studies (n = 2,639 individuals). Using automated text mining, manual curation, and network-based methods incorporating information on expression quantitative trait loci (eQTL), we propose plausible causal mechanisms for 25 trans-acting loci, including a potential post-translational regulation of stem cell factor by matrix metalloproteinase 9 and receptor-ligand pairs such as RANK-RANK ligand. Using public GWA study data, we further evaluate all 79 loci for their causal effect on coronary artery disease, and highlight several potentially causal associations. Overall, a majority of the plasma proteins studied showed evidence of regulation at the genetic level. Our results enable future studies of the causal architecture of human disease, which in turn should aid discovery of new drug targets.

Several proteins that circulate in blood have been linked to cardiovascular disease through the use of classic epidemiology and correlation studies. If individuals with higher risk of disease have higher levels of a protein, the protein may be associated with disease. However, this does not necessarily mean that the protein causes disease; it may merely be an innocent bystander or a consequence of the disease process. To establish whether a protein causes disease, a genetic approach, insensitive to reverse causation, can be used. Instead of correlating the levels of the protein itself, gene variants that regulate the protein levels are used in the analysis. This approach requires prior knowledge of which genetic variants are linked to individual proteins. Therefore we completed a map of how common genetic variants affect the blood concentration levels of 83 proteins that have been implicated in cardiovascular disease. By using this map of cause-to-effect findings, we gained insights into the regulation of a majority of the proteins under study and how they relate to risk of coronary artery disease. This study provides a map of genetic regulation of important cardiovascular plasma proteins, insights into their upstream regulatory environment, as well as novel leads for cardiovascular drug development.

Abstract 318: Matrix Metalloproteinase 12 is Causally Implicated in Cardiovascular Disease

Recent evidence suggests that single nucleotide polymorphisms (SNPs) in the matrix metalloproteinase (MMP) gene cluster located at chromosome 11q22.3 are associated with large-vessel stroke. In the present study, we evaluated and extended the reported association by examining the relationship between MMPs and vascular disease in both clinical and experimental samples. Plasma concentrations of MMP-1, MMP-3, MMP-7, MMP-10 and MMP-12 were measured in 3 394 subjects with high-risk for cardiovascular disease (CVD) using the Olink ProSeek CVD array. Plasma MMP-12 concentration showed association with incident cardiovascular events (199 events over 36 months) and intima-media thickness progression over time (p=3.6x10 -5 ). The SNP variant rs1892971 was strongly associated with plasma MMP-12 concentration (p=8x10 -29 ) and weakly with susceptibility to coronary heart disease in the CardiogramplusC4D consortium study (p=8.8x10 -5 ). The same SNP was also significantly associated with MMP-12 gene expression in peripheral blood mononuclear cells using microarrays from patients with carotid atherosclerosis (n=96; p=1.8x10 -4 ). Expression of MMP-12 was strongly increased in carotid plaques (n=127) compared with undiseased arteries (n=10; p<0.0001) and in plaques from symptomatic (n=87) compared to asymptomatic patients (n=40; p=0.03) and localised to CD68+ macrophages. Using proximity ligation assay MMP-12 and elastin was demonstrated to co-interact in plaques in situ, particularly in regions with moderate to strong MMP-12 expression. Silencing of MMP-12 using siRNA in differentiated THP-1 cells indicated that MMP-12 has a role in macrophage migration. In conclusion, our study suggests that MMP-12 is a causal factor in CVD that is highly upregulated in human atherosclerotic plaques where it interacts with elastin and appears to enhance macrophage invasion.