Adenosine A<Subscript>2A</Subscript> receptor regulates expression of vascular endothelial growth factor in feto-placental endothelium from normal and late-onset pre-eclamptic pregnancies

We aim to investigate whether A_2A/nitric oxide-mediated regulation of vascular endothelial growth factor (VEGF) expression is impaired in feto-placental endothelial cells from late-onset pre-eclampsia. Cultures of human umbilical vein endothelial cells (HUVECs) and human placental microvascular endothelial cells (hPMECs) from normal and pre-eclamptic pregnancies were used. Assays by using small interference RNA (siRNA) for A_2A were performed, and transfected cells were used for estimation of messenger RNA (mRNA) levels of VEGF, as well as for cell proliferation and angiogenesis in vitro. CGS-21680 (A_2A agonist, 24 h) increases HUVEC and hPMEC proliferation in a dose response manner. Furthermore, similar to CGS-21680, the nitric oxide donor, S-nitroso-N-acetyl-penicillamine oxide (SNAP), increased cell proliferation in a dose response manner (logEC₅₀ 10^?9.2 M). In hPMEC, CGS-21680 increased VEGF protein levels in both normal (～1.5-fold) and pre-eclamptic pregnancies (～1.2-fold), an effect blocked by the A_2A antagonist, ZM-241385 (10^?5 M) and the inhibitor of NO synthase, N _ω-nitro-L-arginine methyl ester hydrochloride (L-NAME). Subsequently, SNAP partially recovered cell proliferation and in vitro angiogenesis capacity of cells from normal pregnancies exposed to siRNA for A_2A. CGS-21680 also increased (～1.5-fold) the level of VEGF mRNA in HUVEC from normal pregnancies, but not in pre-eclampsia. Additionally, transfection with siRNA for A_2A decrease (～30 %) the level of mRNA for VEGF in normal pregnancy compared to untransfected cells, an effect partially reversed by co-incubation with SNAP. The A_2A-NO-VEGF pathway is present in endothelium from microcirculation and macrocirculation in both normal and pre-eclamptic pregnancies. However, NO signaling pathway seems to be impaired in HUVEC from pre-eclampsia.     

Impaired A2A adenosine receptor/nitric oxide/VEGF signaling pathway in fetal endothelium during late- and early-onset preeclampsia

To investigate whether fetal endothelial cell proliferation and migration are modulated by the A_2A adenosine receptor (A_2AAR), nitric oxide (NO) and the vascular endothelial growth factor (VEGF) signaling pathway, we isolated human umbilical vein endothelial cells from normal pregnancy (n?=?23), preterm delivery (n?=?4), and late-onset (LOPE, n?=?10) and early-onset preeclampsia (EOPE, n?=?8). We used the non-selective adenosine receptor agonist (NECA) and the selective agonist (CGS-21680) and/or selective antagonist (ZM-241385) for A_2AAR. Also, the nitric oxide synthase (NOS) inhibitor, l-NAME, was used in co-incubation with CGS-21680. Compared to normal pregnancy, EOPE exhibited low cell proliferation and migration associated with reduced expressions of A_2AAR and VEGF and NO synthesis (i.e., total and phosphorylated serine¹¹⁷⁷ endothelial NOS and nitrite formation). In contrast, LOPE exhibited the opposite behavior in all these markers compared to normal pregnancy or EOPE. Cell proliferation and migration were increased by CGS-21680 (or NECA) in all analyzed groups (EOPE>LOPE>normal pregnancy) compared to their respective basal conditions, an effect that was associated with high NO and VEGF synthesis and blocked by ZM-241385 with significantly different IC₅₀ for each group (EOPE>LOPE>normal pregnancy). The differences seem independent of gestational age. l-NAME blocked the CGS-21680-mediated cell proliferation and migration in normal pregnancy and LOPE (IC₅₀?=?36.2?±?2.5 and 8.6?±?2.2 nM, respectively) as well as the VEGF expression in normal pregnancy. Therefore, the A_2AAR/NO/VEGF signaling pathway exhibits a pro-angiogenic effect in normal pregnancies and LOPE, whereas impairment in this pathway seems related to the reduced angiogenic capacity of the fetal endothelium in EOPE.     

Deletion of the adenosine A2A receptor increases the survival rate in a mice model of polymicrobial sepsis

Purinergic Signalling - We aim to investigate the role of A2A receptor in peritonitis-related sepsis by injection of a fecal solution (FS) as a model of polymicrobial infection. C57/black J6...     

High plasma adenosine levels in overweight/obese pregnant women

We aim to investigate whether overweight/obese pregnant women have elevated plasma levels of adenosine associated with increased consumption of high-calorie food. Sixty women were included. They were divided into lean (n = 23 and n = 12) or overweight/obese (n = 7 and n = 18) non-pregnant and pregnant women, respectively. Clinical records and maternal blood samples were collected after informed consent. A self-reported dietary questionnaire was also completed. Plasma adenosine levels were determined with high-performance liquid chromatography. Biochemical parameters, including glucose, total protein, and lipid profile, were determined using standard colorimetric assays. Adenosine levels were higher in pregnant women than in non-pregnant women (18.7 ± 1.6 vs 10.8 ± 1.3 nM/μg protein, respectively, p < 0.0001). Overweight/obese pregnant women (21.9 ± 2.5 nM/μg protein) exhibited higher adenosine levels than lean pregnant (14.5 ± 1.0 nM/μg protein, p = 0.04) or non-pregnant women (11.7 ± 1.5 nM/μg protein, p = 0.0005). Also, pregnant women with elevated weight gain exhibited higher (26.2 ± 3.7 nM/μg protein) adenosine levels than those with adequate weight gain (14.9 ± 1.4 nM/μg protein, p = 0.03). These differences were not statistically significant compared with those of pregnant women with reduced weight gain (17.4 ± 2.1 nM/μg protein, p = 0.053). Body mass index and adenosine only in pregnant women were positively correlated (r = 0.39, p = 0.02). While, polyunsaturated fatty acid (PUFA) consumption was negatively correlated with plasma adenosine levels only in non-pregnant women (r = ?0.33, p = 0.03). Pregnancy is associated with high plasma adenosine levels, which are further elevated in pregnant women who are overweight/obese. High PUFA intake might reduce plasma adenosine levels in non-pregnant women.