Chromatography is often used as a method for reducing sample complexity prior to analysis by mass spectrometry, the use of retention time (RT) is becoming increasingly popular to add valuable supporting information in lipid identification.The RT of lipids with the same headgroup in reverse-phase separation can be predicted using the effective carbon number (ECN) model. This model describes the effect of acyl chain length and degree of saturation on lipid RT, which increases predictably with acyl chain length and degree of saturation. Furthermore, we have found a robust correlation in the chromatographic separation of lipids with different headgroups that share the same fatty acid motive. By measuring a small number of lipids from each subclass it is possible to build a model that allows for the prediction of the RT of one lipid subclass based on another.Here, we utilise ECN modelling and inter-class retention time conversion (IC-RTC) to build a glycerophospholipid RT library with 481 entries based on 136 MS/MS characterised lipid RTs from NIST SRM-1950 plasma and lipid standards.The library was tested on a patient cohort undergoing coronary artery bypass grafting surgery (n=37). A total of 129 unique circulating glycerophospholipids were identified, of which, 57 (4 PC, 24 PE, 4 PG, 15 PI, 10 PS) were detected with IC-RTC, thereby demonstrating the utility of this technique for the identification of lipid species not found in commercial standards.

Introduction Recurrent event rates after myocardial infarction (MI) remain unacceptably high, in part because of the continued growth and destabilization of residual coronary atherosclerotic plaques, which may occur despite lipid-lowering therapy. Inflammation is an important contributor to this ongoing risk. Recent studies have shown that the broad-acting anti-inflammatory agent, colchicine, may reduce adverse cardiovascular events in patients post-MI, although the mechanistic basis for this remains unclear. Advances in endovascular arterial wall imaging have allowed detailed characterization of the burden and compositional phenotype of coronary plaque, along with its natural history and responsiveness to treatment. One such example has been the use of optical coherence tomography (OCT) to demonstrate the plaque-stabilizing effects of statins on both fibrous cap thickness and the size of lipid pools within plaque. Methods The Phase 2, multi-centre, double-blind colchicine for coronary plaque modification in acute coronary syndrome (COCOMO-ACS) study will evaluate the effect of colchicine 0.5 mg daily on coronary plaque features using serial OCT imaging in patients following MI. Recruitment for the trial has been completed with 64 participants with non-ST elevation MI randomized 1:1 to colchicine or placebo in addition to guideline recommended therapies, including high-intensity statins. The primary endpoint is the effect of colchicine on the minimal fibrous cap thickness of non-culprit plaque over an 18-month period. Summary The COCOMO-ACS study will determine whether addition of colchicine 0.5 mg daily to standard post-MI treatment has incremental benefits on high-risk features of coronary artery plaques. If confirmed, this will provide new mechanistic insights into how colchicine may confer clinical benefits in patients with atherosclerotic cardiovascular disease. Trial Registration ANZCTR trial registration number: ACTRN12618000809235. Date of trial registration: 11th of May 2018.

Colchicine is a broad-acting anti-inflammatory agent that has attracted interest for repurposing in atherosclerotic cardiovascular disease. Here, we studied its ability at a human equivalent dose of 0.5 mg/day to modify plaque formation and composition in murine atherosclerosis and investigated its actions on macrophage responses to atherogenic stimuli in vitro. In atherosclerosis induced by high-cholesterol diet, Apoe −/− mice treated with colchicine had 50% reduction in aortic oil Red O + plaque area compared to saline control (p = .001) and lower oil Red O + staining of aortic sinus lesions (p = .03). In vitro, addition of 10 nM colchicine inhibited foam cell formation from murine and human macrophages after treatment with oxidized LDL (ox-LDL). Mechanistically, colchicine downregulated glycosylation and surface expression of the ox-LDL uptake receptor, CD36, and reduced CD36 + staining in aortic sinus plaques. It also decreased macrophage uptake of cholesterol crystals, resulting in lower intracellular lysosomal activity, inhibition of the NLRP3 inflammasome, and reduced secretion of

Eukaryotic elongation factor 2 kinase (eEF2K) is an atypical protein kinase that controls protein synthesis in cells under stress. Although well studied in cancer, less is known about its roles in chronic inflammatory diseases. Here, we examined its regulation of macrophage cholesterol handling in the context of atherosclerosis. eEF2K mRNA expression and protein activity were upregulated in murine bone marrow‐derived macrophages (BMDMs) exposed to oxidized low‐density lipoprotein cholesterol (oxLDL). When incubated with oxLDL, BMDMs from eEF2K knockout (Eef2k−/−) mice formed fewer Oil Red O+ foam cells than Eef2k+/+ BMDMs (12.5% ± 2.3% vs. 32.3% ± 2.0%, p < .01). Treatment with a selective eEF2K inhibitor, JAN‐384, also decreased foam cell formation for C57BL/6J BMDMs and human monocyte‐derived macrophages. Disabling eEF2K selectively decreased protein expression of the CD36 cholesterol uptake receptor, mediated by a reduction in the proportion of translationally active Cd36 mRNA. Eef2k−/− mice bred onto the Ldlr−/− background developed aortic sinus atherosclerotic plaques that were 30% smaller than Eef2k+/+‐Ldlr−/− mice after 16 weeks of high cholesterol diet (p < .05). Although accompanied by a reduction in plaque CD36+ staining (p < .05) and lower CD36 expression in circulating monocytes (p < .01), this was not associated with reduced lipid content in plaques as measured by oil red O staining. Finally, EEF2K and CD36 mRNA levels were higher in blood mononuclear cells from patients with coronary artery disease and recent myocardial infarction compared to healthy controls without coronary artery disease. These results reveal a new role for eEF2K in translationally regulating CD36 expression and foam cell formation in macrophages. Further studies are required to explore therapeutic targeting of eEF2K in atherosclerosis.

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