Raised endothelial shear stress is protective against atherosclerosis but such protection may be lost at sites of inflammation. We found that four splice variants of the peptidase inhibitor 16 (PI16) mRNA are among the most highly shear stress regulated transcripts in human coronary artery endothelial cells (HCAECs), in vitro but that expression is reduced by inflammatory mediators TNFα and IL-1β. Immunohistochemistry demonstrated that PI16 is expressed in human coronary endothelium and in a subset of neointimal cells and medial smooth muscle cells. Adenovirus-mediated PI16 overexpression inhibits HCAEC migration and secreted matrix metalloproteinase (MMP) activity. Moreover, PI16 inhibits MMP2 in part by binding an exposed peptide loop above the active site. Our results imply that, at high endothelial shear stress, PI16 contributes to inhibition of protease activity; protection that can be reversed during inflammation.

HighlightsHuman coronary artery endothelial cells show a biological response to cigarette smoke.This response was not seen following exposure to e-cigarette aerosol.Using e-cigarettes instead of cigarettes may reduce immediate cardiovascular harms.

Endothelial dysfunction caused by the combined action of disturbed flow, inflammatory mediators and oxidants derived from cigarette smoke is known to promote coronary atherosclerosis and increase the likelihood of myocardial infarctions and strokes. Conversely, laminar flow protects against endothelial dysfunction, at least in the initial phases of atherogenesis. We studied the effects of TNFα and cigarette smoke extract on human coronary artery endothelial cells under oscillatory, normal laminar and elevated laminar shear stress for a period of 72 hours. We found, firstly, that laminar flow fails to overcome the inflammatory effects of TNFα under these conditions but that cigarette smoke induces an anti-oxidant response that appears to reduce endothelial inflammation. Elevated laminar flow, TNFα and cigarette smoke extract synergise to induce expression of the transcriptional regulator activating transcription factor 3 (ATF3), which we show by adenovirus driven overexpression, decreases inflammatory gene expression independently of activation of nuclear factor-κB. Our results illustrate the importance of studying endothelial dysfunction in vitro over prolonged periods. They also identify ATF3 as an important protective factor against endothelial dysfunction. Modulation of ATF3 expression may represent a novel approach to modulate proinflammatory gene expression and open new therapeutic avenues to treat proinflammatory diseases.

Objectives-To determine if assaying the neutrophil enzymes, neutrophil elastase (NE) and myeloperoxidase (MPO) showing the test to be more sensitive in younger men. We decided to extend this strategy by investigating the levels of two other neutrophil enzymes in urine and whether these might be better markers of infection or urethritis. We therefore investigated assays of neutrophil elastase (NE) and myeloperoxidase (MPO), two enzymes which are found in the azurophil granules of PMNLs. MPO reacts with H202 and chloride to produce hypochlorous acid, an oxidant which is thought to be bactericidal,9 whilst elastase is a non-specific proteinase, capable of cleaving a wide range of proteins, including human elastin and collagen. NE is a powerful enzyme; its activity is regulated by alpha-1 antitrypsin, a protease inhibitor secreted mainly by the liver. The nature of unregulated neutrophil elastase activity is illustrated by hereditary deficiency of alpha-i antitrypsin where those affected usually develop pulmonary emphysema.'0 NE is also thought to play a significant role in the lung injury which occurs in the adult respiratory distress syndrome." We investigated urine samples of symptomatic and asymptomatic men attending a genitourinary medicine clinic to determine if those with infections could be identified by the new assays. LET was also performed to compare its sensitivity and specificity.Materials and methods Any male undergoing full genital screening tests in the Department of Genito-urinary Medicine, whether symptomatic or asymptomatic, was considered eligible for the study. One hundred males (age range 18-68 years) were entered into the study. First voided urine samples were collected into sterile containers

Background: DNA hypomethylation at the F2RL3 locus has been associated with both smoking and atherosclerotic cardiovascular disease; whether these smoking-related associations form a pathway to disease is unknown. F2RL3 encodes protease-activated receptor 4, a potent thrombin receptor expressed on platelets. Given the role of thrombin in platelet activation and the role of thrombus formation in myocardial infarction, alterations to this biological pathway could be important for ischemic cardiovascular disease. Methods: We conducted multiple independent experiments to assess whether DNA hypomethylation at F2RL3 in response to smoking is associated with risk of myocardial infarction via changes to platelet reactivity. Using cohort data (N=3,205), we explored the relationship between smoking, DNA hypomethylation at F2RL3 and myocardial infarction. We compared platelet reactivity in individuals with low versus high DNA methylation at F2RL3 (N=41). We used an in vitro model to explore the biological response of F2RL3 to cigarette smoke extract (CSE). Finally, a series of reporter constructs were used to investigate how differential methylation could impact F2RL3 gene expression. Results: Observationally, DNA methylation at F2RL3 mediated an estimated 34% of the smoking effect on increased risk of myocardial infarction. An association between methylation group (low/high) and platelet reactivity was observed in response to PAR4 stimulation. In cells, CSE exposure was associated with a 4.9 to 9.3% reduction in DNA methylation at F2RL3 and a corresponding 1.7 (95% CI: 1.2, 2.4, p=0.04) fold increase in F2RL3 mRNA. Results from reporter assays suggest the exon 2 region of F2RL3 may help control gene expression. Conclusions: Smoking-induced epigenetic DNA hypomethylation at F2RL3 appears to increase PAR4 expression with potential downstream consequences for platelet reactivity. Combined evidence here not only identifies F2RL3 DNA methylation as a possible contributory pathway from smoking to cardiovascular disease risk, but from any feature potentially influencing F2RL3 regulation in a similar manner.

Endothelial erosion of atherosclerotic plaques and resulting thrombosis causes approximately 30% of acute coronary syndromes (ACS). As changes in the haemodynamic environment strongly influence endothelial function and contribute to plaque development, we reconstructed the coronary artery geometries of plaques with thrombi overlying intact fibrous caps from 17 ACS patients and performed computational fluid dynamic analysis. The results demonstrated that erosions frequently occur within areas of stenosis exposed to elevated flow. We recapitulated this flow environment in vitro, exposing human coronary artery endothelial cells to elevated flow and modelled smoking (a risk factor for erosion) by exposure to a combination of aqueous cigarette smoke extract and TNFα. This treatment induced endothelial detachment, which increased with pharmacological activation of the antioxidant system controlled by transcription factor Nrf2 (encoded by NFE2L2). The expression of Oxidative Stress Growth INhibitor genes OSGIN1 and OSGIN2 increased under these conditions and also in the aortas of mice exposed to cigarette smoke. Sustained high level expression of OSGIN1+2 resulted in cell cycle arrest, induction of senescence, loss of focal adhesions and actin stress fibres, and dysregulation of autophagy. Overexpression of either Nrf2 or OSGIN1+2 induced cell detachment, which did not depend on apoptosis, and could be partially rescued by inhibition of HSP70 using VER-155008, or AMP kinase activation using metformin. These findings demonstrate that under elevated flow, smokinginduced hyperactivation of Nrf2 can trigger endothelial cell detachment, highlighting a novel mechanism that could contribute to ACS involving endothelial erosion overlying stenotic plaques.

Aims Endothelial erosion of plaques is responsible for ∼30% of acute coronary syndromes (ACS). Smoking is a risk factor for plaque erosion, which most frequently occurs on the upstream surface of plaques where the endothelium experiences elevated shear stress. We sought to recreate these conditions in vitro to identify potential pathological mechanisms that might be of relevance to plaque erosion. Methods and results Culturing human coronary artery endothelial cells (HCAECs) under elevated flow (shear stress of 7.5 Pa) and chronically exposing them to cigarette smoke extract (CSE) and tumour necrosis factor-alpha (TNFα) recapitulated a defect in HCAEC adhesion, which corresponded with augmented Nrf2-regulated gene expression. Pharmacological activation or adenoviral overexpression of Nrf2 triggered endothelial detachment, identifying Nrf2 as a mediator of endothelial detachment. Growth/Differentiation Factor-15 (GDF15) expression was elevated in this model, with protein expression elevated in the plasma of patients experiencing plaque erosion compared with plaque rupture. The expression of two Nrf2-regulated genes, OSGIN1 and OSGIN2, was increased by CSE and TNFα under elevated flow and was also elevated in the aortas of mice exposed to cigarette smoke in vivo. Knockdown of OSGIN1&2 inhibited Nrf2-induced cell detachment. Overexpression of OSGIN1&2 induced endothelial detachment and resulted in cell cycle arrest, induction of senescence, loss of focal adhesions and actin stress fibres, and disturbed proteostasis mediated in part by HSP70, restoration of which reduced HCAEC detachment. In ACS patients who smoked, blood concentrations of HSP70 were elevated in plaque erosion compared with plaque rupture. Conclusion We identified a novel Nrf2-OSGIN1&2-HSP70 axis that regulates endothelial adhesion, elevated GDF15 and HSP70 as biomarkers for plaque erosion in patients who smoke, and two therapeutic targets that offer the potential for reducing the risk of plaque erosion.

A persistent sciatic artery is a rare congenital anomaly where the internal iliac artery and the original axial artery of the embry continue to provide the major blood supply to the lower limb after birth. Its predisposition to atherosclerosis, aneurysmal degeneration of its gluteal segment and association with other congenital anomalies are important for its management. W report a patient who highlights these aspects and we provide a brief review of this unusual condition.