ANGPTL7

High levels of HDL-C are correlated with a decreased risk of cardiovascular disease. HDL-C levels are modulated in part by the secreted phospholipase, endothelial lipase (EL), which hydrolyzes the phospholipids of HDL and decreases circulating HDL-C concentrations. A 584C/T polymorphism in LIPG, the gene which encodes EL, was first identified in individuals with increased HDL levels. This polymorphism results in a T111I point mutation the EL protein. The association between this variant, HDL levels, and the risk of coronary artery disease (CAD) in humans has been extensively studied, but the findings have been inconsistent. In this study, we took a biochemical approach, investigating how the T111I variant affected EL activity, structure, and stability. Moreover, we tested whether the T111I variant altered the inhibition of phospholipase activity by angiopoietin-like 3 (ANGPTL3) and angiopoietin-like 4 (ANGPTL4), two known EL inhibitors. We found that neither the stability nor enzymatic activity of EL was altered by the T111I variant. Moreover, we found no difference between wild-type and T111I EL in their ability to be inhibited by ANGPTL proteins. These data suggest that any effect this variant may have on HDL-C levels or cardiovascular disease are not mediated through alterations in these functions.

Perinatal exposure of the neonatal lung to inflammation leads to decreased lung angiogenesis and the development of bronchopulmonary dysplasia (BPD). Notably, autologous cord blood mononuclear cells (ACBMNCs) can substantially prevent severe BPD and decrease the inflammatory response in surviving very preterm neonates. Angiopoietin‑like protein 7 (Angptl7) is one of the main paracrine cytokines in cord blood stem cells, and is capable of stimulating human hematopoietic stem and progenitor cell expansion. The present study compared Angptl7 levels between the ACBMNCs infusion and control groups (cohort 1). Subsequently, the association between cord blood Angptl7 levels and BPD incidence in a cohort of very preterm neonates was assessed (cohort 2). The hypothesis was further verified in a lipopolysaccharide (LPS)‑induced lung injury mouse model. The mRNA expression levels and protein concentrations of inflammatory cytokines in the lung tissue and mouse serum were measured using reverse transcription‑quantitative PCR and ELISA, respectively. The number and diameter of lung vessels and macrophage infiltration were assessed using immunofluorescence staining. Compared with in the control group, Angptl7 levels were significantly higher in the ACBMNCs infusion group in cohort 1. In cohort 2, the cord blood Angptl7 levels were significantly lower in infants who later developed BPD. Multiple linear regression analysis showed that higher Angptl7 level was an independent protective factor for BPD. The concentrations of interleukin‑6 and monocyte chemoattractant protein‑1 were negatively correlated with cord blood Angptl7 level; whereas, vascular endothelial growth factor‑A levels were positively correlated with Angptl7 levels. In the LPS‑induced lung injury mouse model, the LPS group presented with a significant loss of pulmonary vessels and smaller vessel diameters, which were ameliorated in the Angptl7 treatment group. Furthermore, LPS‑induced lung inflammation and macrophage infiltration were alleviated by Angptl7 treatment (P<0.05). In conclusion, the anti‑inflammatory and proangiogenic effects of Angptl7 derived from cord blood stem cells may ameliorate BPD severity. The trial for cohort 1 was registered at ClinicalTrials.gov (trial registration no. NCT02999373; date registered, December 21, 2016).

The venous system has been historically understudied despite its critical roles in blood distribution, heart function, and systemic immunity. This study dissects the microanatomy of upper arm veins at the single cell level, and how it relates to wall structure, remodeling processes, and inflammatory responses to injury. We applied single-cell RNA sequencing to 4 non-diseased human veins (3 basilic, 1 cephalic) obtained from organ donors, followed by bioinformatic and histological analyses. Unsupervised clustering of 20,006 cells revealed a complex ecosystem of endothelial cell (EC) types, smooth muscle cell (SMCs) and pericytes, various types of fibroblasts, and immune cell populations. The venous endothelium showed significant upregulation of cell adhesion genes, with arteriovenous zonation EC phenotypes highlighting the heterogeneity of vasa vasorum (VV) microvessels. Venous SMCs had atypical contractile phenotypes and showed widespread localization in the intima and media. MYH11+DESlo SMCs were transcriptionally associated with negative regulation of contraction and pro-inflammatory gene expression. MYH11+DEShi SMCs showed significant upregulation of extracellular matrix genes and pro-migratory mediators. Venous fibroblasts ranging from secretory to myofibroblastic phenotypes were 4X more abundant than SMCs and widely distributed throughout the wall. Fibroblast-derived angiopoietin-like factors were identified as versatile signaling hubs to regulate angiogenesis and SMC proliferation. An abundant monocyte/macrophage population was detected and confirmed by histology, including pro-inflammatory and homeostatic phenotypes, with cell counts positively correlated with age. Ligand-receptor interactome networks identified the venous endothelium in the main lumen and the VV as a niche for monocyte recruitment and infiltration. This study underscores the transcriptional uniqueness of venous cells and their relevance for vascular inflammation and remodeling processes. Findings from this study may be relevant for molecular investigations of upper arm veins used for vascular access creation, where single-cell analyses of cell composition and phenotypes are currently lacking.