Flow Perturbation Mediates Neutrophil Recruitment and Potentiates Endothelial Injury via TLR2 in MiceNovelty and Significance

Rationale: Superficial erosion currently causes up to a third of acute coronary syndromes; yet, we lack understanding of its mechanisms. Thrombi because of superficial intimal erosion characteristically complicate matrix-rich atheromata in regions of flow perturbation. Objective: This study tested in vivo the involvement of disturbed flow and of neutrophils, hyaluronan, and Toll-like receptor 2 ligation in superficial intimal injury, a process implicated in superficial erosion. Methods and Results: In mouse carotid arteries with established intimal lesions tailored to resemble the substrate of human eroded plaques, acute flow perturbation promoted downstream endothelial cell activation, neutrophil accumulation, endothelial cell death and desquamation, and mural thrombosis. Neutrophil loss-of-function limited these findings. Toll-like receptor 2 agonism activated luminal endothelial cells, and deficiency of this innate immune receptor decreased intimal neutrophil adherence in regions of local flow disturbance, reducing endothelial cell injury and local thrombosis ( P &lt;0.05). Conclusions: These results implicate flow disturbance, neutrophils, and Toll-like receptor 2 signaling as mechanisms that contribute to superficial erosion, a cause of acute coronary syndrome of likely growing importance in the statin era. </jats:sec

LncRNA VINAS regulates atherosclerosis by modulating NF-κB and MAPK signaling

Long noncoding RNAs (lncRNAs) play important roles in regulating diverse cellular processes in the vessel wall, including atherosclerosis. RNA-Seq profiling of intimal lesions revealed a lncRNA, VINAS (Vascular INflammation and Atherosclerosis lncRNA Sequence), that is enriched in the aortic intima and regulates vascular inflammation. Aortic intimal expression of VINAS fell with atherosclerotic progression and rose with regression. VINAS knockdown reduced atherosclerotic lesion formation by 55% in LDL receptor–deficient (LDLR–/–) mice, independent of effects on circulating lipids, by decreasing inflammation in the vessel wall. Loss- and gain-of-function studies in vitro demonstrated that VINAS serves as a critical regulator of inflammation by modulating NF-κB and MAPK signaling pathways. VINAS knockdown decreased the expression of key inflammatory markers, such as MCP-1, TNF-α, IL-1β, and COX-2, in endothelial cells (ECs), vascular smooth muscle cells, and bone marrow–derived macrophages. Moreover, VINAS silencing decreased expression of leukocyte adhesion molecules VCAM-1, E-selectin, and ICAM-1 and reduced monocyte adhesion to ECs. DEP domain containing 4 (DEPDC4), an evolutionary conserved human ortholog of VINAS with approximately 74% homology, showed similar regulation in human and pig atherosclerotic specimens. DEPDC4 knockdown replicated antiinflammatory effects of VINAS in human ECs. These findings reveal a potentially novel lncRNA that regulates vascular inflammation, with broad implications for vascular diseases

Roles of PAD4 and NETosis in Experimental Atherosclerosis and Arterial Injury: Implications for Superficial Erosion

Neutrophils likely contribute to the thrombotic complications of human atheromata. In particular, neutrophil extracellular traps (NETs) could exacerbate local inflammation and amplify and propagate arterial intimal injury and thrombosis. PAD4 (peptidyl arginine deiminase 4) participates in NET formation, but an understanding of this enzyme's role in atherothrombosis remains scant

S-Nitrosothiol Signaling Regulates Liver Development and Improves Outcome following Toxic Liver Injury

Toxic liver injury is a leading cause of liver failure and death because of the organ’s inability to regenerate amidst massive cell death, and few therapeutic options exist. The mechanisms coordinating damage protection and repair are poorly understood. Here, we show that S-nitrosothiols regulate liver growth during development and after injury in vivo; in zebrafish, nitric-oxide (NO) enhanced liver formation independently of cGMP-mediated vasoactive effects. After acetaminophen (APAP) exposure, inhibition of the enzymatic regulator S-nitrosoglutathione reductase (GSNOR) minimized toxic liver damage, increased cell proliferation, and improved survival through sustained activation of the cytoprotective Nrf2 pathway. Preclinical studies of APAP injury in GSNOR-deficient mice confirmed conservation of hepatoprotective properties of S-nitrosothiol signaling across vertebrates; a GSNOR-specific inhibitor improved liver histology and acted with the approved therapy N-acetylcysteine to expand the therapeutic time window and improve outcome. These studies demonstrate that GSNOR inhibitors will be beneficial therapeutic candidates for treating liver injury

Long noncoding RNA SNHG12 integrates a DNA-PK-mediated DNA damage response and vascular senescence

Long noncoding RNAs (lncRNAs) are emerging regulators of biological processes in the vessel wall; however, their role in atherosclerosis remains poorly defined. We used RNA sequencing to profile lncRNAs derived specifically from the aortic intima of Ldlr(-/-) mice on a high-cholesterol diet during lesion progression and regression phases. We found that the evolutionarily conserved lncRNA small nucleolar host gene-12 (SNHG12) is highly expressed in the vascular endothelium and decreases during lesion progression. SNHG12 knockdown accelerated atherosclerotic lesion formation by 2.4-fold in Ldlr(-/-) mice by increased DNA damage and senescence in the vascular endothelium, independent of effects on lipid profile or vessel wall inflammation. Conversely, intravenous delivery of SNHG12 protected the tunica intima from DNA damage and atherosclerosis. LncRNA pulldown in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis showed that SNHG12 interacted with DNA-dependent protein kinase (DNA-PK), an important regulator of the DNA damage response. The absence of SNHG12 reduced the DNA-PK interaction with its binding partners Ku70 and Ku80, abrogating DNA damage repair. Moreover, the anti-DNA damage agent nicotinamide riboside (NR), a clinical-grade small-molecule activator of NAD(+), fully rescued the increases in lesional DNA damage, senescence, and atherosclerosis mediated by SNHG12 knockdown. SNHG12 expression was also reduced in pig and human atherosclerotic specimens and correlated inversely with DNA damage and senescent markers. These findings reveal a role for this lncRNA in regulating DNA damage repair in the vessel wall and may have implications for chronic vascular disease states and aging