Homeodomain interacting protein kinase 2 activation compromises endothelial cell response to laminar flow: protective role of p21(waf1,cip1,sdi1)

Using Yoda-1 to mimic laminar flow in vitro: A tool to simplify drug testing

The endothelium is an attractive drug target and an important site of adverse drug reactions. Endothelial dysfunction is strongly associated with inflammation and contributes to drug-induced cardiovascular toxicity. Endothelial cells in the circulation are exposed to haemodynamic forces including shear stress. Including shear stress may improve future endothelial cell drug discovery or toxicity screening. Piezo-1 is required for endothelial cells to respond to shear stress. In this study, we investigated whether a small molecule activator of Piezo-1, Yoda-1, can mimic the effect of laminar flow-induced shear stress on endothelial cell inflammation, and endothelial cytotoxicity in response to the chemotherapy agent, doxorubicin.

First, we tested whether Yoda-1 could mimic the effects of shear stress of expression of the endothelial adhesion molecules, ICAM-1 and VCAM-1. Human umbilical vein endothelial cells (HUVEC) were cultured in static conditions (with or without Yoda-1) or under laminar flow-induced shear stress (5 dyn/cm²). Yoda-1 and laminar flow had similar anti-inflammatory effects, reducing the ability of TNF-α to induce ICAM-1 and VCAM-1 expression. We then tested whether Yoda-1 could mimic the effect of shear stress on doxorubicin-induced cytotoxicity. Both laminar flow and Yoda-1 treatment of static cultures increased the cytotoxicity of doxorubicin. These findings show that Piezo-1 activation with Yoda-1 in static culture leads to an endothelial cell phenotype that mimics endothelial cells under laminar flow. Pharmacological activation of Piezo-1 may be a useful approach to mimic constant shear stress in static cultures, which may improve endothelial drug discovery and toxicity testing.

Role of Homeodomain-Interacting Protein Kinase 2 in the Pathogenesis of Tissue Fibrosis in Keloid-Derived Keratinocytes

Epithelial-mesenchymal transition (EMT) plays a critical role in fibrotic keloid formation, which is characterized by excessive collagen and extracellular matrix synthesis and deposition. Growing evidence suggests that the serine/threonine kinase homeodomain-interacting protein kinase 2 (HIPK2) acts upstream of several major fibrosis signaling pathways; however, the role of HIPK2 in the keloid fibrogenesis remains unknown. In the current study, we investigated the roles of HIPK2 in the pathogenesis of keloids. Primary normal skin and keloid keratinocytes were cultured and pretreated with transforming growth factor (TGF)-β1. Next, keratinocytes were transfected with scrambled small interfering RNA (siRNA) and anti-HIPK2 siRNA. The TGF-β1-associated HIPK2 alterations were investigated by quantitative real-time polymerase chain reaction. Protein levels were analyzed by western blotting. The HIPK2 was markedly increased in the keloid-derived keratinocytes compared with normal skin keratinocytes. In addition, HIPK2 induced the expression of EMT markers in normal skin keratinocytes by TGF-β1-SMAD family member 3 (SMAD3). The effect of TGF-β1-related EMT markers and SMAD3 phosphorylation in response to added TGF-β1 was significantly abrogated when the cells were transfected with HIPK2 siRNA. We conclude that HIPK2 is a crucial factor in the pathogenesis of keloids, suggesting that HIPK2 might be a novel potential drug target for antikeloid therapy.

Oxidative stress as common trait of endothelial dysfunction in chorionic arteries from fetuses with IUGR and LGA

INTRODUCTION

Fetal macrosomia and intrauterine growth restriction (IUGR) associate with increased morbidity in the neonate. Placental vascular relaxation is impaired in fetal macrosomia, as well as in IUGR, and this could result from increased oxidative stress present in both conditions. We determined the role of pro- and anti-oxidants on NOS dependent relaxation in placental chorionic arteries from pregnancies with LGA babies from overweight and/or obese mothers (LOOM) and IUGR fetuses from normal BMI women.

METHODS

Chorionic arteries were mounted in a wire-myograph, where responses to the NOS-dependent agent CGRP in presence or absence of the antioxidant N-acetyl cysteine (NAC), the pro-oxidant SIN-1, the SOD inhibitor DDC, and the GPx inhibitor MS were determined. Additionally the presence of pro- and antioxidant enzymes (NOX-4, SOD-1, SOD-2 and GPx-1) and eNOS in chorionic and umbilical vessels were addressed by immunohistochemistry.

RESULTS

Maximal CGRP-induced relaxation was comparable to controls but presented a reduced potency in chorionic arteries from LOOM placentae, whilst in IUGR vessels both maximal response and potency were reduced. NAC increased maximal relaxation in controls, IUGR and LOOM arteries, whilst SIN-1 completely abolished the CGRP-induced relaxation only in IUGR and LOOM samples, the later effect was paralleled by SOD or GPx inhibition. These responses associated with the presence of NOX-4, SOD-1 and GPx-1 in the endothelium and vascular wall of chorionic and umbilical arteries in the different groups studied.

DISCUSSION

These data suggest that NOS dependent relaxation in placental vessels from IUGR and LOOM pregnancies present a higher sensitivity to oxidative stress.

Shear stress inhibits apoptosis of ischemic brain microvascular endothelial cells

As a therapeutic strategy for ischemic stroke, to restore or increase cerebral blood flow (CBF) is the most fundamental option. Laminar shear stress (LS), as an important force generated by CBF, mainly acts on brain microvascular endothelial cells (BMECs). In order to study whether LS was a protective factor in stroke, we investigated LS-intervented ischemic apoptosis of rat BMECs (rBMECs) through PE Annexin V/7-AAD, JC-1 and Hoechst 33258 staining to observe the membranous, mitochondrial and nuclear dysfunction. Real-time PCR and western blot were also used to test the gene and protein expressions of Tie-2, Bcl-2 and Akt, which were respectively related to maintain membranous, mitochondrial and nuclear norm. The results showed that LS could be a helpful stimulus for ischemic rBMECs survival. Simultaneously, membranous, mitochondrial and nuclear regulation played an important role in this process.

Arginine-based inhibitors of nitric oxide synthase: therapeutic potential and challenges

In the past three decades, nitric oxide has been well established as an important bioactive molecule implicated in regulation of cardiovascular, nervous, and immune systems. Therefore, it is not surprising that much effort has been made to find specific inhibitors of nitric oxide synthases (NOS), the enzymes responsible for production of nitric oxide. Among the many NOS inhibitors developed to date, inhibitors based on derivatives and analogues of arginine are of special interest, as this category includes a relatively high number of compounds with good potential for experimental as well as clinical application. Though this group of inhibitors covers early nonspecific compounds, modern drug design strategies such as biochemical screening and computer-aided drug design have provided NOS-isoform-specific inhibitors. With an emphasis on major advances in this field, a comprehensive list of inhibitors based on their structural characteristics is discussed in this paper. We provide a summary of their biochemical properties as well as their observed effects both in vitro and in vivo. Furthermore, we focus in particular on their pharmacology and use in recent clinical studies. The potential of newly designed specific NOS inhibitors developed by means of modern drug development strategies is highlighted.

Role of nitric oxide in placental vascular development and function

Nitric oxide (NO) is one of the most pleiotropic signaling molecules at systemic and cellular levels, participating in vascular tone regulation, cellular respiration, proliferation, apoptosis and gene expression. Indeed NO actively participates in trophoblast invasion, placental development and represents the main vasodilator in this tissue. Despite the large number of studies addressing the role of NO in the placenta, its participation in placental vascular development and the effect of altered levels of NO on placental function remains to be clarified. This review draws a time-line of the participation of NO throughout placental vascular development, from the differentiation of vascular precursors to the consolidation of vascular function are considered. The influence of NO on cell types involved in the origin of the placental vasculature and the expression and function of the nitric oxide synthases (NOS) throughout pregnancy are described. The developmental processes involved in the placental vascular bed are considered, such as the participation of NO in placental vasculogenesis and angiogenesis through VEGF and Angiopoietin signaling molecules. The role of NO in vascular function once the placental vascular tree has developed, in normal pregnancy as well as in pregnancy-related diseases, is then discussed.