Circulating CD14+CD16- classical monocytes do not associate with a vulnerable plaque phenotype, and do not predict secondary events in severe atherosclerotic patients.

AIMS: Mouse studies have established distinct monocyte subtypes that participate in the process of atherosclerotic lesion formation. The pro-inflammatory Ly6Chigh monocyte subtype actively contributes to murine plaque progression and destabilization. Also in humans, different peripheral monocyte subtypes have been identified, of which the CD14+CD16- classical monocyte is suggested to display similar pro-atherosclerotic properties as the murine Ly6Chigh subtype. We aimed to investigate if circulating CD14+CD16- classical monocytes associate with characteristics of a vulnerable carotid atherosclerotic plaque and if they associate with the risk of secondary adverse manifestations of atherosclerotic disease. METHODS AND RESULTS: We enrolled 175 carotid endarterectomy patients of the Athero-Express biobank in our study. Just prior to surgical procedure, blood was collected and peripheral blood mononuclear cells were isolated. Characterization of monocyte subsets was performed by flow cytometry. Plaque characteristics were semi-quantitatively scored for the presence of fat, collagen, intraplaque hemorrhage and calcification. Vessel density, smooth muscle cells and macrophages were assessed quantitatively on a continuous scale. All features of a vulnerable plaque phenotype, including low amounts of collagen and smooth muscle cells, and increased fat content, vessel density, intraplaque hemorrhage and plaque macrophages were not significantly associated with differential levels of peripheral classical CD14+CD16- monocytes or other monocyte subsets. Using Cox regression models to evaluate the prognostic value of circulating monocyte subtypes, we found that total counts of peripheral monocytes, as well as CD14+CD16- classical and other monocyte subtypes were not associated with the risk of secondary cardiovascular events during 3 years follow-up. CONCLUSION: Circulating classical CD14+CD16- monocytes do not associate with specific vulnerable plaque characteristics. In addition, they do not predict secondary adverse manifestations. This suggests that in patients with established carotid artery disease, the circulating monocytes do not reflect plaque characteristics and have no value in identifying patients at risk for future cardiovascular events.

Noncanonical NF-κB signaling in microvessels of atherosclerotic lesions is associated with inflammation, atheromatous plaque morphology and myocardial infarction.

BACKGROUND AND AIMS: Neovascularization is associated with atherosclerotic plaque instability and increased chance of myocardial infarction (MI). Patients with chronic inflammatory diseases (CID) have increased risk of atherosclerosis, and evidence demonstrates that NF-κB inducing kinase (NIK)-mediated noncanonical NF-κB signaling in endothelial cells (EC) is linked to inflammation and angiogenesis. Here, we hypothesized NIK may also be activated in EC of atherosclerotic lesion microvessels. METHODS: Using cohorts of atherosclerotic lesions from coronary and carotid arteries, we quantified NIK expression in plaque microvessels and compared it to pathological markers, including inflammatory cell content, plaque characteristics and MI. Differences in gene transcripts were evaluated between stable and ruptured lesions. RESULTS: NIK+EC were present in both coronary and carotid lesions. In CID patients, plaques with stenosis >40% had an increased number of NIK+EC and higher content of immune cells (p < .05) as compared to controls. Immune cells per NIK+EC were also greater in CID patients (p < .05), with pronounced differences as stenosis increased. In unstable lesions, NIK+EC were elevated as were EC expressing CXCL12 (p < .05). NIK+EC were increased in lesions with lipid content >40% (p < .05) and more abundant in coronary artery lesions implicated in MI (p < .05). These vessels also associated with atheromatous rather than fibrous plaque morphology (p < .05). Transcriptomic profiling demonstrated components of noncanonical NF-κB pathway were also upregulated in ruptured plaques (p < .05). CONCLUSIONS: NIK+EC associate with chronic inflammation in advanced lesions and are linked to markers of local inflammation, lipid content, unstable plaque phenotype and development of MI. Therefore, targeting noncanonical NF-κB signaling may hold therapeutic potential for patients with atherosclerosis and cardiovascular disease.

High Levels of (Un)Switched Memory B Cells Are Associated With Better Outcome in Patients With Advanced Atherosclerotic Disease.

BACKGROUND: Atherosclerosis is an inflammatory lipid disorder and the main underlying pathology of acute ischemic events. Despite a vast amount of data from murine atherosclerosis models, evidence of B-cell involvement in human atherosclerotic disease is limited. We therefore investigated the association of circulating B-cell subtypes with the occurrence of secondary cardiovascular events in advanced atherosclerotic disease. METHODS AND RESULTS: This cohort study consists of 168 patients who were included in the Athero-Express biobank between 2009 and 2011. Before surgery, peripheral blood mononuclear cells were isolated and stored in liquid nitrogen. After gentle thawing of the peripheral blood mononuclear cells, different B-cell subtypes including naïve, (un)switched memory, and CD27+CD43+ B1-like B cells, were analyzed by flow cytometry. Univariable and multivariable Cox proportional hazard models were used to analyze associations between B-cell subtypes, circulating antibodies and secondary cardiovascular manifestations during the 3-year follow-up period. Mean age was 70.1±9.6 years, males represented 62.8% of the population, and 54 patients had secondary manifestations during follow-up. High numbers of unswitched memory cells were protective against secondary outcome (hazard ratio, 0.30 [95% CI, 0.13-0.69]; P<0.01). Similar results were obtained for the switched memory cells that also showed to be protective against secondary outcome (hazard ratio, 0.33 [95% CI, 0.14-0.77]; P=0.01). CONCLUSIONS: A high number of (un)switched memory B cells is associated with better outcome following carotid artery endarterectomy. These findings suggest a potential role for B-cell subsets in prediction and prevention of secondary cardiovascular events in patients with atherosclerosis.