Abdominal aortic aneurysm (AAA) is a common disease with substantial heritability. In this study, we performed a genome-wide association meta-analysis from 14 discovery cohorts and uncovered 141 independent associations, including 97 previously unreported loci. A polygenic risk score derived from meta-analysis explained AAA risk beyond clinical risk factors. Genes at AAA risk loci indicate involvement of lipid metabolism, vascular development and remodeling, extracellular matrix dysregulation and inflammation as key mechanisms in AAA pathogenesis. These genes also indicate overlap between the development of AAA and other monogenic aortopathies, particularly via transforming growth factor β signaling. Motivated by the strong evidence for the role of lipid metabolism in AAA, we used Mendelian randomization to establish the central role of nonhigh-density lipoprotein cholesterol in AAA and identified the opportunity for repurposing of proprotein convertase, subtilisin/kexin-type 9 (PCSK9) inhibitors. This was supported by a study demonstrating that PCSK9 loss of function prevented the development of AAA in a preclinical mouse model.

—This study was undertaken to investigate the enzymatic regulation of the biosynthesis of vasoconstrictor prostanoids by resting and interleukin (IL)-1β–stimulated human umbilical vein endothelial cells (HUVECs). Biosynthesis of eicosanoids in response to IL-1β, exogenous labeled arachidonic acid (AA), or histamine, as well as their spontaneous release, was evaluated by means of HPLC and RIA. HUVECs exposed to IL-1β produced prostaglandin (PG) I₂for no longer than 30 seconds after the substrate was added irrespective of the cyclooxygenase (COX) activity, whereas the time course of PGE₂and PGD₂formation was parallel to the COX activity. The ratio of PGE₂to PGD₂produced by HUVECs was similar to that obtained by purified COX-1 and COX-2. Production of PGF_2αfrom exogenous AA was limited and similar in both resting and IL-1β–treated cells. PGF_2αwas the main prostanoid released into the medium during exposure to IL-1β, whereas when HUVECs treated with IL-1β were stimulated with histamine or exogenous AA, PGE₂was released in a higher quantity than PGF_2α. PGF_2αreleased into the medium during treatment with IL-1β and the biosynthesis of PGE₂and PGD₂in response to exogenous AA or histamine increased with COX-2 expression, whereas this did not occur in the case of PGI₂. We observed that PGI synthase (PGIS) mRNA levels were not modified by the exposure to IL-1β, but the enzyme was partially inactivated. When SnCl₂was added to the incubation medium, the transformation of exogenous AA-derived PGH₂into PGE₂and PGD₂was totally diverted toward PGF_2α. Overall, these results support the conclusions that PGE₂and PGD₂(and also probably PGF_2α) were nonenzymatically derived from PGH₂in HUVECs. The concept that a high ratio of PGH₂was released by the IL-1β–treated HUVECs and isomerized outside the cell into PGE₂and PGD₂was supported by the biosynthesis of thromboxane B₂by COX-inactivated platelets, indicating the uptake by platelets of HUVEC-derived PGH₂. The IL-1β–induced increase in the release of PGH₂by HUVECs was suppressed by the COX-2–selective inhibitor SC-58125 and correlated with both COX-2 expression and PGIS inactivation. An approach to the mechanism of inactivation of PGIS by the exposure to IL-1β was performed by using labeled endoperoxides as substrate. The involvement of HO· in the PGIS inactivation was supported by the fact that deferoxamine, pyrrolidinedithiocarbamate, DMSO, mannitol, and captopril antagonized the effect of IL-1β on PGIS to different degrees. The NO synthase inhibitorN^G-monomethyl-l-arginine also antagonized the PGIS inhibitory effect of IL-1β, indicating that NO· was also involved. NO· reacts with O₂⁻· to form peroxynitrite, which has been reported to inactivate PGIS. Homolytic fission of the O-O bond of peroxynitrite yields NO₂· and HO·. The fact that 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO), which reacts with NO· to form NO₂·, dramatically potentiated the IL-1β effect suggests that NO₂· could be a species implicated in the inactivation of PGIS. Cooperation of HO· was supported by the fact that DMSO partially antagonized the effect of carboxy-PTIO. Although our results on the exact mechanism of the inactivation of PGIS caused by IL-1β were not conclusive, they strongly suggest that both NO· and HO· were involved.

Apolipoprotein A-II (apoA-II), the second major high-density lipoprotein (HDL) apolipoprotein, has been linked to familial combined hyperlipidemia. Human apoA-II transgenic mice constitute an animal model for this proatherogenic disease. We studied the ability of human apoA-II transgenic mice HDL to protect against oxidative modification of apoB-containing lipoproteins. When challenged with an atherogenic diet, antigens related to low-density lipoprotein (LDL) oxidation were markedly increased in the aorta of 11.1 transgenic mice (high human apoA-II expressor). HDL from control mice and 11.1 transgenic mice were coincubated with autologous very LDL (VLDL) or LDL, or with human LDL under oxidative conditions. The degree of oxidative modification of apoB lipoproteins was then evaluated by measuring relative electrophoretic mobility, dichlorofluorescein fluorescence, 9- and 13-hydroxyoctadecadienoic acid content, and conjugated diene kinetics. In all these different approaches, and in contrast to control mice, HDL from 11.1 transgenic mice failed to protect LDL from oxidative modification. A decreased content of apoA-I, paraoxonase (PON1), and platelet-activated factor acetyl-hydrolase activities was found in HDL of 11.1 transgenic mice. Liver gene expression of these HDL-associated proteins did not differ from that of control mice. In contrast, incubation of isolated human apoA-II with control mouse plasma at 37°C decreased PON1 activity and displaced the enzyme from HDL. Thus, overexpression of human apoA-II in mice impairs the ability of HDL to protect apoB-containing lipoproteins from oxidation. Further, the displacement of PON1 by apoA-II could explain in part why PON1 is mostly found in HDL particles with apoA-I and without apoA-II, as well as the poor antiatherogenic properties of apoA-II–rich HDL.

—In a previous work, we postulated that endothelial cells possess only the following 2 enzymes involved in prostanoid synthesis: cyclooxygenase and prostacyclin synthase. The present work focused on investigating the expression of prostaglandin (PG) E synthase (PGES) in vascular cells. After incubation of vascular smooth muscle cells (SMCs) and human umbilical vein endothelial cells (HUVECs) with [ ¹⁴ C]arachidonic acid, the profile of prostanoid synthesis was assessed by HPLC. Untransformed PGH ₂ released by the cells was evaluated as the difference in the formation of PGF _2α in the incubations performed in the presence and in the absence of SnCl ₂ . Resting SMCs and SMCs stimulated with phorbol 12-myristate 13-acetate (PMA), lipopolysaccharide (LPS), interleukin (IL)-1β, and tumor necrosis factor (TNF)-α formed PGE ₂ and PGI ₂ (evaluated as 6-oxo-PGF _1α ), and in the presence of SnCl ₂ only a small amount of PGE ₂ was deviated toward PGF _2α . In contrast, resting and stimulated HUVECs produced PGI ₂ , PGE ₂ , PGF _2α , and PGD ₂ , and SnCl ₂ completely diverted PGE ₂ and PGD ₂ toward PGF _2α . Reverse transcriptase–polymerase chain reaction analysis shows that mRNA encoding for PGES was not present in HUVECs and in endothelial cells from saphenous vein. Nevertheless, PGES was expressed in SMCs and induced by IL-1β and TNF-α, and by PMA and LPS, although to a lesser extent. Whereas SMC stimulation led to an increase in the synthesis of PGE ₂ and PGI ₂ but not of untransformed PGH ₂ , stimulation of endothelial cells resulted in an enhanced release of the vasoconstricting prostanoid PGH ₂ .

The presence of IL-1 in human cancers is associated with aggressive tumor biology but its prognostic value is unknown. We studied whether IL-1α expression is a prognostic marker of distant metastasis in patients with head and neck squamous cell carcinoma (HNSCC). IL-1α mRNA and protein levels were determined in tumor samples and cancer cell lines using RT-PCR and ELISA. The effects of constitutive IL-1α expression by tumor lines were characterized. IL-1α mRNA and protein secretion were higher in tumor samples from patients who later developed distant metastasis than in patients who did not. By using distant metastasis as a dependent variable, patients were classified into two categories of IL-1α transcript-levels. The high-IL-1α group had a significantly lower five-year distant metastasis-free survival than the low-IL-1α group [70.0% (CI 95%: 55.9-84.1%) vs 94.7% (CI 95%:90.2-99.2%)]. When IL-1α transcript-levels were combined with clinical factors related to tumor metastasis, the predictive power of the model increased significantly. Additionally, transcript levels of IL-1α correlated significantly with those of the IL-1 family genes and genes related to the metastatic process. IL-1 treatment of microvascular endothelial cells increased adhesion of HNSCC cells but no differences were found based on constitutive IL-1α expression by tumor cells. Nevertheless, IL-1α produced by tumor cells effectively increased their transmigration across the endothelium. We found a significant relationship between IL-1α expression and development of distant metastasis in HNSCC patients. IL-1α expression could help to define a subset of patients at high risk of distant metastasis who could benefit from adjuvant treatment.