Haemolysis, elevated liver enzymes and low platelets: Diagnosis and management in critical care.

A thirty-year-old pregnant woman was admitted to hospital with headache and gastrointestinal discomfort. She developed peripheral oedema and had an emergency caesarean section following an episode of tonic-clonic seizures. Her delivery was further complicated by postpartum haemorrhage and she was admitted to the Intensive Care Unit (ICU) for further resuscitation and seizure control which required infusions of magnesium and multiple anticonvulsants. Despite haemodynamic optimisation she developed an acute kidney injury with evidence of liver damage, thrombocytopenia and haemolysis. Haemolysis, Elevated Liver enzymes and Low Platelets (HELLP) syndrome, a multisystem disease of advanced pregnancy which overlaps with pre-eclampsia, was diagnosed. HELLP syndrome is associated with a range of complications which may require critical care support, including placental abruption and foetal loss, acute kidney injury, microangiopathic haemolytic anaemia, acute liver failure and liver capsule rupture. Definitive treatment of HELLP is delivery of the fetus and in its most severe forms requires admission to the ICU for multiorgan support. Therapeutic strategies in ICU are mainly supportive and include blood pressure control, meticulous fluid balance and possibly escalation to renal replacement therapy, mechanical ventilation, neuroprotection, seizure control, and management of liver failure-related complications. Multidisciplinary input is essential for optimal treatment.

Pleiotrophin selectively binds to vascular endothelial growth factor receptor 2 and inhibits or stimulates cell migration depending on ανß3 integrin expression.

Pleiotrophin (PTN) has a moderate stimulatory effect on endothelial cell migration through ανß3 integrin, while it decreases the stimulatory effect of vascular endothelial growth factor A (VEGFA) and inhibits cell migration in the absence of ανß3 through unknown mechanism(s). In the present work, by using a multitude of experimental approaches, we show that PTN binds to VEGF receptor type 2 (VEGFR2) with a KD of 11.6 nM. Molecular dynamics approach suggests that PTN binds to the same VEGFR2 region with VEGFA through its N-terminal domain. PTN inhibits phosphorylation of VEGFR2 at Tyr1175 and still stimulates endothelial cell migration in the presence of a selective VEGFR2 tyrosine kinase inhibitor. VEGFR2 downregulation by siRNA or an anti-VEGFR2 antibody that binds to the ligand-binding VEGFR2 domain also induce endothelial cell migration, which is abolished by a function-blocking antibody against ανß3 or the peptide PTN112-136 that binds ανß3 and inhibits PTN binding. In cells that do not express ανß3, PTN decreases both VEGFR2 Tyr1175 phosphorylation and cell migration in a VEGFR2-dependent manner. Collectively, our data identify VEGFR2 as a novel PTN receptor involved in the regulation of cell migration by PTN and contribute to the elucidation of the mechanism of activation of endothelial cell migration through the interplay between VEGFR2 and ανß3.

Insight into the role of chondroitin sulfate E in angiogenesis.

Chondroitin sulfate E (CS-E) is a glycosaminoglycan containing type-E disaccharide units (sulfated at C-4 and C-6 of N-acetylgalactosamine). CS-E is covalently linked to a core protein to form chondroitin sulfate proteoglycans (PGs) that are secreted or associated with the plasma membrane of several types of cells. CS-E-containing PGs selectively interact with growth factors and chemokines and control various cellular and/or tissue processes. Angiogenesis is a process that is highly regulated in physiological conditions but deregulated in pathologies, leading to excess or deficient blood vessel formation. Angiogenesis regulation is orchestrated by numerous growth factors, such as vascular endothelial growth factor A, fibroblast growth factors and pleiotrophin, whose functions can be affected by CS-containing PGs. In the present review, we focus on the emerging area of CS-mediated angiogenesis and particularly on the critical assessment of data related to a potential role of CS-E in controlling endothelial cell functions, focusing on angiogenesis regulation and vascular homeostasis in health and disease.

Vascular endothelial growth factor A (VEGF-A) decreases expression and secretion of pleiotrophin in a VEGF receptor-independent manner.

Vascular endothelial growth factor A (VEGF-A) is a key molecule in angiogenesis acting through VEGF receptors (VEGFRs), ανß3 integrin, receptor protein tyrosine phosphatase beta/zeta (RPTPß/ζ) and cell surface nucleolin (NCL). Pleiotrophin (PTN) stimulates endothelial cell migration and limits the angiogenic effects of VEGF-A165 to the levels of its own effect, possibly acting as a VEGF-A165 modifier. Since PTN and VEGF-A165 share receptors and actions on endothelial cells, in the present work we studied whether and how VEGF-A165 affects PTN expression or secretion. VEGF-A165 decreased PTN mRNA and protein levels acting at the transcriptional level. Bevacizumab, a selective VEGFR2 tyrosine kinase inhibitor and down-regulation of VEGFR2 expression by siRNA did not affect this decrease, suggesting that it is VEGFR-independent. VEGF-A121 also decreased PTN mRNA and protein levels, suggesting that heparin binding of VEGF-A165 is not involved. Blockage of cell surface NCL, lack of expression or mutation of ß3 integrin and down-regulation of RPTPß/ζ abolished the inhibitory effect of VEGF-A165 on PTN expression and secretion. Down-regulation of endogenous PTN in endothelial cells enhanced VEGF-A165-induced increase in migration and tube formation on matrigel. Collectively, these data suggest that VEGF-A down-regulates PTN expression and secretion through the RPTPß/ζ-ανß3-NCL axis to enhance its own effect on cell migration and further highlight the role of RPTPß/ζ in VEGF-A actions.

Inhibition of Atherosclerosis Progression, Intimal Hyperplasia, and Oxidative Stress by Simvastatin and Ivabradine May Reduce Thoracic Aorta's Stiffness in Hypercholesterolemic Rabbits.

AIMS: This study aims to evaluate atherosclerosis, oxidative stress, and arterial stiffness attenuation by simvastatin and ivabradine in hyperlipidemic rabbits. METHODS AND RESULTS: Forty rabbits were randomly divided into 4 groups: atherogenic diet (group C), atherogenic diet plus simvastatin (group S), atherogenic diet plus ivabradine (group I), and atherogenic diet plus simvastatin and ivabradine (group S + I). After 9 weeks, rabbits were euthanized and descending aortas excised for mechanical testing. Atherogenic diet induced the development of significant atherosclerotic lesions in group C animals but in none of groups S, I, and S + I. RAM-11 and HHF-35-positive cells were significantly reduced in groups S, I, and S + I compared with group C (P < .001). A significant neointimal hyperplasia and intima-media ratio reduction was demonstrated in groups S (P = .015 and P < .001), I (P = .021 and P < .001), and S + I (P = .019 and P < .001) compared with group C. Protein nitrotyrosine levels were significantly decreased in group S compared with group C (P = .009), and reactive oxygen species levels were decreased in group I compared with group C (P = .011). Aortic stiffness was significantly reduced in groups S, I, and S + I compared with group C (P = .003, P = .011, and P = .029). CONCLUSION: Simvastatin and ivabradine significantly inhibited intimal hyperplasia and oxidative stress contributing to aortic stiffness reduction in hyperlipidemic rabbits.

Receptor protein tyrosine phosphatase beta/zeta is a functional binding partner for vascular endothelial growth factor.

BACKGROUND: Receptor protein tyrosine phosphatase beta/zeta (RPTPß/ζ) is a chondroitin sulphate (CS) transmembrane protein tyrosine phosphatase and is a receptor for pleiotrophin (PTN). RPTPß/ζ interacts with ανß3 on the cell surface and upon binding of PTN leads to c-Src dephosphorylation at Tyr530, ß3 Tyr773 phosphorylation, cell surface nucleolin (NCL) localization and stimulation of cell migration. c-Src-mediated ß3 Tyr773 phosphorylation is also observed after vascular endothelial growth factor 165 (VEGF165) stimulation of endothelial cells and is essential for VEGF receptor type 2 (VEGFR2) - ανß3 integrin association and subsequent signaling. In the present work, we studied whether RPTPß/ζ mediates angiogenic actions of VEGF. METHODS: Human umbilical vein endothelial, human glioma U87MG and stably transfected Chinese hamster ovary cells expressing different ß3 subunits were used. Protein-protein interactions were studied by a combination of immunoprecipitation/Western blot, immunofluorescence and proximity ligation assays, properly quantified as needed. RPTPß/ζ expression was down-regulated using small interference RNA technology. Migration assays were performed in 24-well microchemotaxis chambers, using uncoated polycarbonate membranes with 8 µm pores. RESULTS: RPTPß/ζ mediates VEGF165-induced c-Src-dependent ß3 Tyr773 phosphorylation, which is required for VEGFR2-ανß3 interaction and the downstream activation of phosphatidylinositol 3-kinase (PI3K) and cell surface NCL localization. RPTPß/ζ directly interacts with VEGF165, and this interaction is not affected by bevacizumab, while it is interrupted by both CS-E and PTN. Down-regulation of RPTPß/ζ by siRNA or administration of exogenous CS-E abolishes VEGF165-induced endothelial cell migration, while PTN inhibits the migratory effect of VEGF165 to the levels of its own effect. CONCLUSIONS: These data identify RPTPß/ζ as a cell membrane binding partner for VEGF that regulates angiogenic functions of endothelial cells and suggest that it warrants further validation as a potential target for development of additive or alternative anti-VEGF therapies.

Transauricular balloon angioplasty in rabbit thoracic aorta: a novel model of experimental restenosis.

BACKGROUND: The aim of this study was to demonstrate a percutaneous transauricular method of balloon angioplasty in high-cholesterol fed rabbits, as an innovative atherosclerosis model. METHODS: Twenty male New Zealand rabbits were randomly divided into two groups of ten animals, as follows: atherogenic diet plus balloon angioplasty (group A) and atherogenic diet alone (group B). Balloon angioplasty was performed in the descending thoracic aorta through percutaneous catheterization of the auricular artery. Eight additional animals fed regular diet were served as long term control. At the end of 9 week period, rabbits were euthanized and thoracic aortas were isolated for histological, immunohistochemical and biochemical analysis. RESULTS: Atherogenic diet induced severe hypercholesterolemia in both group A and B (2802 ± 188.59 and 4423 ± 493.39 mg/dl respectively) compared to the control animals (55.5 ± 11.82 mg/dl; P < 0.001). Group A atherosclerotic lesions appeared to be more advanced histologically (20% type IV and 80% type V) compared to group B lesions (50% type III and 50% type IV). Group A compared to group B atherosclerotic lesions demonstrated similar percentage of macrophages (79.5 ± 9.56% versus 84 ± 12.2%; P = 0.869), more smooth muscle cells (61 ± 14.10% versus 40.5 ± 17.07; P = 0.027), increased intima/media ratio (1.20 ± 0.50 versus 0.62 ± 0.13; P = 0.015) despite the similar degree of intimal hyperplasia (9768 ± 1826.79 µm² versus 12205 ± 8789.23 µm²; P = 0.796), and further significant lumen deterioration (23722 ± 4508.11 versus 41967 ± 20344.61 µm²; P = 0.05) and total vessel area reduction (42350 ± 5819.70 versus 73190 ± 38902.79 µm²; P = 0.022). Group A and B animals revealed similar nitrated protein percentage (P = NS), but significantly higher protein nitration compared to control group (P < 0.01; P < 0.01, respectively). No deaths or systemic complications were reported. CONCLUSION: Transauricular balloon angioplasty constitutes a safe, minimally invasive and highly successful model of induced atherosclerosis in hyperlipidaemic rabbits.

Serum stimulates Pleiotrophin gene expression in an AP-1-dependent manner in human endothelial and glioblastoma cells.

BACKGROUND: Despite the fact that pleiotrophin (PTN) exhibits important biological activities related to tumor growth and angiogenesis, little is known about the regulation of its expression. In the present work, the effect of serum on PTN expression and secretion in the culture medium of human umbilical vein endothelial (HUVECs) and glioblastoma M059K cells was studied. MATERIALS AND METHODS: The protein levels of PTN were estimated by Western blot and pin transcription was estimated by measuring luciferase activity of a reporter gene vector carrying the wild-type or mutated full length promoter of the ptn gene. RESULTS: Serum induced PTN protein secretion in both types of cells and up-regulated luciferase activity of the ptn promoter in a time- and concentration-dependent manner. Use of a mutant construct that lacked the serum response element (SRE) showed that serum-induced luciferase activity was partially abolished in HUVECs but not affected in M059K cells. Transfection with a construct mutated at both AP-1 binding sites led to complete abolishment of the serum-induced ptn transcription in both types of cells. CONCLUSION: The two AP-1 binding sites of the ptn promoter are involved in the serum stimulation of its expression, while SRE involvement seems to be partial and cell type-specific.

Nitric oxide stimulates migration of human endothelial and prostate cancer cells through up-regulation of pleiotrophin expression and its receptor protein tyrosine phosphatase beta/zeta.

Pleiotrophin (PTN) is a secreted growth factor involved in angiogenesis and tumor growth. We have recently shown that low concentrations of hydrogen peroxide (HP) stimulate PTN expression, through activation of the transcription factor AP-1. In the present work, we studied the possible involvement of endothelial nitric oxide synthase (eNOS) and the role of nitric oxide (NO) in the regulation of PTN expression, as well as involvement of the latter in the NO-induced human endothelial and prostate cancer cell migration. Inhibition of eNOS or the downstream effector soluble guanylate cyclase (sGC) completely suppressed HP-induced AP-1 activities that lead to PTN expression and cell migration. The NO donor sodium nitroprusside (SNP) through activation of sGC significantly and concentration-dependently increased expression of PTN, through transcriptional activation of the corresponding gene. Moreover, SNP had no effect on the migration of stably transfected prostate cancer cells that do not express PTN and knockdown of PTN receptor protein tyrosine phosphatase beta/zeta (RPTPbeta/zeta) completely abolished SNP-induced cell migration. NO added exogenously or produced endogenously by low concentrations of HP through stimulation of sGC activates extracellular signal-regulated kinase[1/2] (ERK[1/2]) and leads to PTN expression and cell migration. On the other hand, p38, which also intervenes in the up-regulation of PTN expression by low concentrations of HP, seems to act upstream of eNOS and does not intervene in the SNP-induced PTN expression and cell migration. The above data suggest that PTN through its receptor RPTPbeta/zeta is a mediator of the stimulatory effects of eNOS/NO on human endothelial and prostate cancer cell migration.