Enhanced pial arteriolar sensitivity to bioactive agents following exposure to endothelin-1

Serum protein profile analysis via label-free quantitation proteomics in patients with early-onset preeclampsia

BACKGROUND

Preeclampsia (PE) is a serious pregnancy complication, resulting in potentially life-threatening conditions for both mother and foetus. It is worth noting that early-onset PE has become a great challenge for clinicians due to its complex manifestation, rapid progression and serious complications. This study aims to investigate differential serum proteome profiles in patients with early-onset PE.

METHODS

Each serum sample was separated using a nanoliter flow rate Easy-nLC chromatography system. Then the samples were analysed by mass spectrometry. Bioinformatics analyses were conducted to analyse the functional categories or signal transduction pathways for differentially abundant proteins. Key proteins identified by mass spectrometry were verified by ELISA.

RESULTS

We found 30 and 34 proteins were upregulated and downregulated in early-onset PE patients (n = 3) vs controls (n = 3), respectively. Functional enrichment analysis revealed differentially expressed proteins related to the immune response and regulation of peptidase activity. ELISA confirmed that there were lower CSH1 levels and higher LPA concentrations in the serum samples of early-onset PE patients (n = 22) than in healthy controls (n = 19) (p < 0.05 for CSH1 and p < 0.001 for LPA).

CONCLUSIONS

This study revealed the critical features of serum proteins in early-onset PE patients. LPA and CSH1 may serve as biomarkers for early-onset PE diagnosis and therapy.

Lysophosphatidic acid (LPA) signaling in vertebrate reproduction

Lysophosphatidic acid (LPA) is a cell membrane phospholipid metabolite that can act as an extracellular signal. Its effects are mediated through at least five G protein-coupled receptors, LPA(1-5), and probably others as well. Studies in multiple species including LPAR-deficient mice and humans have identified or implicated important roles for receptor-mediated LPA signaling in multiple aspects of vertebrate reproduction. These include ovarian function, spermatogenesis, fertilization, early embryo development, embryo implantation, embryo spacing, decidualization, pregnancy maintenance and parturition. LPA signaling can also have pathological consequences, influencing aspects of endometriosis and ovarian cancer. Here we review recent progress in LPA signaling research relevant to female and male reproduction.

Cerebrovascular response to continuous cold perfusion and hypothermic circulatory arrest

OBJECTIVE

Clinical and laboratory studies have documented changes in cerebrovascular resistance after hypothermic circulatory arrest, both with and without adjunctive cerebral perfusion modalities. This study was designed to clarify whether these changes are due to cerebral edema, resistance vessel abnormalities, or alterations in the cerebral microcirculation.

METHODS

Four mature swine underwent hypothermic circulatory arrest for 60 minutes, and 7 mature swine underwent cold cerebral perfusion for 60 minutes to simulate antegrade selective perfusion. All were rewarmed and weaned from cardiopulmonary bypass. Pial vascular diameter and reactivity were measured in vivo through a cranial window and ex vivo in an organ chamber; cerebral microvascular endothelium was studied in culture for release of vasoactive mediators. Cerebral water content was recorded.

RESULTS

Cold perfusion caused pial arteriole and venule constriction, whereas hypothermic circulatory arrest alone caused pial arteriole and venule dilatation. Cold perfusion caused a temporal loss of endothelium-dependent vasodilatation, most notably to bradykinin. Hypothermic circulatory arrest caused a loss of nitric oxide-mediated endothelium-dependent vasodilatation. Endothelium-independent vasoreactivity remained intact in both groups. Endothelial cells from the cold group had a vasoconstrictive secretory phenotype, whereas endothelial cells from the hypothermic circulatory arrest group had a vasodilatory phenotype. Cerebral water content was the same in both groups.

CONCLUSION

The increase in cerebrovascular resistance observed after cold cerebral perfusion is caused by resistance vessel constriction and may be promoted by an altered microcirculation. Hypothermic circulatory arrest alone is associated with endothelium-dependent vasoparesis. Both could contribute to cerebral injury in the early hours after operation.

Endothelin in the perinatal circulation

During the fetal period, blood is oxygenated through the placenta, and most of the cardiac output bypasses the lung through the ductus arteriosus. At birth, pulmonary vascular resistance falls with the initiation of ventilation. Coincidentally, the ductus arteriosus constricts. Endothelin-1 (ET-1) appears to play an important role during that transition period and postnatally. ET-1 can dramatically increase resistance in the placental microcirculation and may be involved in blood flow redistribution with hypoxia. At birth, the increase in oxygen tension is important in triggering ductus vasoconstriction. It is proposed that oxygen triggers closure of the ductus arteriosus by activating a specific, cytochrome P450-linked reaction, which in turn stimulates the synthesis of ET-1. On the neonatal heart, ET-1 has a positive chronotropic but negative inotropic effect. In the newborn piglet and the fetal lamb, both term and preterm, ET-1 causes a potent, long-lasting pulmonary vasoconstriction. Furthermore, a transient dilator response has been identified, and it is ascribed to nitric oxide formation. ET receptors are abundant in the piglet pulmonary vasculature. They are predominantly of the ETA constrictor subtype, though ETB2 constrictor receptors may also be present in certain species. The dilator response is linked to the ETB1 receptor, and the number of ETB1 receptors is reduced in hypoxia-induced pulmonary hypertension. ET-1 appears to be a causative agent in the pathogenesis of hypoxia- and hyperoxia-induced pulmonary hypertension as demonstrated by reversal of hemodynamic and morphological changes with treatment with an ETA receptor antagonist. Findings are amenable to practical applications in the management of infants with pulmonary hypertension or requiring persistent patency of the ductus arteriosus.

Highly enhanced permeability of blood-brain barrier induced by repeated administration of endothelin-1 in dogs and rats

The effects of intracisternal administration of endothelin-1 on blood-brain barrier permeability were examined in dogs and rats. Single doses of endothelin-1 elevated blood-brain barrier permeability about two times compared with control groups in both species. However, repeated dosing with endothelin-1 at a 24 hr intervals caused a highly enhanced disruption of blood-brain barrier permeability in dogs, but not in rats, whereas the repeated administration with a 48 hr interval markedly increased the blood-brain barrier permeability in both species of animals (dogs: 923%, rats: more than 661%). Moreover, this abnormally enhanced permeability of blood-brain barrier in dogs was completely blocked by pretreatment with the endothelin ET-A receptor selective antagonist, S-0139, administered prior to either the first or second dosing with endothelin-1. From these results, we conclude that a repeated attack of endothelin-1 from the adventitial site of brain blood vessels produces a severe disruption of blood-brain barrier permeability through an endothelin ET-A receptor-mediated process.

Chronic hypoxia increases MCA contractile response to U-46619 by reducing NO production and/or activity

Chronic hypoxia alters contractile sensitivity of isolated arteries to alpha-adrenergic stimulation and other agonists. However, most studies have been performed in thoracic aortas or other large vessels making little contribution to vascular resistance in their respective circulations. To determine the effect of chronic hypoxia on the vasoconstrictor response in a small, resistance-sized vessel, we studied second and third generation middle cerebral arteries (MCA; approximately 75-microm internal diameter before mounting). MCA were isolated from normoxic (inspired oxygen = 125 Torr) and hypoxic (8 wk at 3,960 m; inspired oxygen = 90 Torr) guinea pigs, and their vasoconstrictor responses were determined to the thromboxane mimetic U-46619 by using dual-pipette video microscopy. Arteries from hypoxic animals had greater contractile sensitivity to U-46619 compared with those of the normoxic animals (-log EC50 = 7.86 +/- 0.11 vs. 7.62 +/- 0.06, respectively, P < 0.05). Addition of the nitric oxide (NO) inhibitor nitro-L-arginine (200 microM) to the vessel bath eliminated the differences in contractile sensitivity between the MCA from the normoxic and chronically hypoxic groups. Supplementation with L-arginine in the drinking water sufficient to raise plasma L-arginine levels 41% reduced MCA contractile sensitivity to U-46619 in the normoxic group (-log EC50 = 7.22 +/- 0.31, P < 0.05 compared with the nonsupplemented normoxic group) but not in the chronically hypoxic group. These results show that chronic hypoxia increases the sensitivity of the MCA to the vasoconstrictor U-46619, likely because of a reduction in NO production and/or activity.

Myocardial expression of endothelin-1 in murine Trypanosoma cruzi infection

Chagas' disease, caused by Trypanosoma cruzi, is an important cause of myocarditis and chronic cardiomyopathy and is accompanied by microvascular spasm and myocardial ischemia. We reported previously that infection of cultured endothelial cells with T. cruzi increased the synthesis of biologically active endothlein-1 (ET-1). In the present study, we examined the role of ET-1 in the cardiovascular system of CD1 mice infected with the Brazil strain of T. cruzi and C57BL/6 mice infected with the Tulahuen strain during acute infection. In the myocardium of infected mice myonecrosis and multiple pseudocysts were observed. There was also an intense vasculitis of the aorta, coronary artery, smaller myocardial vessels and the endocardial endothelium. Immunohistochemistry studies employing anti-ET-1 antibody revealed increased expression of ET-1 that was most intense in the endocardial and vascular endothelium. Elevated levels of mRNA for preproET-1, endothelin converting enzyme and ET-1 were observed in the same myocardial samples. Plasma ET-1 levels were significantly elevated in infected CD1 mice 10-15 days post infection. These observations suggest that increased levels of ET-1 are a consequence of the initial invasion of the cardiovascular system and provide a mechanism for infection-associated myocardial dysfunction.