Enzymes that hydrolyze adenine nucleotides in lymphocytes and platelets of immunosuppressed rats

Antenatal Dexamethasone Treatment Induces Sex-dependent Upregulation of NTPDase1/CD39 and Ecto-5'-nucleotidase/CD73 in the Rat Fetal Brain

Dexamethasone (DEX) is frequently used to treat women at risk of preterm delivery, but although indispensable for the completion of organ maturation in the fetus, antenatal DEX treatment may exert adverse sex-dimorphic neurodevelopmental effects. Literature findings implicated oxidative stress in adverse effects of DEX treatment. Purinergic signaling is involved in neurodevelopment and controlled by ectonucleotidases, among which in the brain the most abundant are ectonucleoside triphosphate diphosphohydrolase 1 (NTPDase1/CD39) and ecto-5'-nucleotidase (e5'NT/CD73), which jointly dephosphorylate ATP to adenosine. They are also involved in cell adhesion and migration, processes integral to brain development. Upregulation of CD39 and CD73 after DEX treatment was reported in adult rat hippocampus. We investigated the effects of maternal DEX treatment on CD39 and CD73 expression and enzymatic activity in the rat fetal brain of both sexes, in the context of oxidative status of the brain tissue. Fetuses were obtained at embryonic day (ED) 21, from Wistar rat dams treated with 0.5 mg DEX/kg/day, at ED 16, 17, and 18, and brains were processed and used for further analysis. Sex-specific increase in CD39 and CD73 expression and in the corresponding enzyme activities was induced in the brain of antenatally DEX-treated fetuses, more prominently in males. The oxidative stress induction after antenatal DEX treatment was confirmed in both sexes, although showing a slight bias in males. Due to the involvement of purinergic system in crucial neurodevelopmental processes, future investigations are needed to determine the role of these observed changes in the adverse effects of antenatal DEX treatment.

Upregulation of nucleoside triphosphate diphosphohydrolase-1 and ecto-5'-nucleotidase in rat hippocampus after repeated low-dose dexamethasone administration

Although dexamethasone (DEX), a synthetic glucocorticoid receptor (GR) analog with profound effects on energy metabolism, immune system, and hypothalamic-pituitary-adrenal axis, is widely used therapeutically, its impact on the brain is poorly understood. The aim of the present study was to explore the effect of repeated low-dose DEX administration on the activity and expression of the ectonucleotidase enzymes which hydrolyze and therefore control extracellular ATP and adenosine concentrations in the synaptic cleft. Ectonucleotidases tested were ectonucleoside triphosphate diphosphohydrolase 1-3 (NTPDase1-3) and ecto-5'-nucleotidase (eN), whereas the effects were evaluated in two brain areas that show different sensitivity to glucocorticoid action, hippocampus, and cerebral cortex. In the hippocampus, but not in cerebral cortex, modest level of neurodegenerative changes as well as increase in ATP, ADP, and AMP hydrolysis and upregulation of NTPDase1 and eN mRNA expression ensued under the influence of DEX. The observed pattern of ectonucleotidase activation, which creates tissue volume with enhanced capacity for adenosine formation, is the hallmark of the response after different insults to the brain.

Interleukin-17A Exacerbates Ferric Chloride-Induced Arterial Thrombosis in Rat Carotid Artery

Interleukin-17A (IL-17A), the most widely studied member of the IL-17 cytokine family, is a cytokine which emerged to be critical for host defense as well as in the pathogenesis of autoimmune disorders. Moreover, IL-17A is involved in the pathogenesis of cardiovascular diseases, such as atherosclerosis and acute coronary syndrome and in the cardiovascular risk associated with systemic immunological disorders. Consistent with this, we have recently shown that IL-17A increases human and murine platelet response to ADP. In this study we expanded our previous observation and we describe for the first time an in vivo prothrombotic effect of the cytokine. Our results show that IL-17A is synergic with a low FeCl₃ concentration in inducing carotid thrombus in rats and suggest that the effect is likely related to a downregulation of CD39 vascular expression and hydrolyzing activity. Our findings indicate that IL-17A might be an important molecule at the interface between hemostasis and inflammation.

“This paper is dedicated to the memory of Professor Alfredo Colonna”

Activities of enzymes that hydrolyze adenine nucleotides in lymphocytes from patients with rheumatoid arthritis

The purpose of this study was to investigate the activities of ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase; EC 3.6.1.5; CD39) and adenosine deaminase (E-ADA; EC 3.5.4.4) in lymphocytes from patients with rheumatoid arthritis (RA). Thirty patients diagnosed with RA through American College of Rheumatology criteria as well as 30 healthy patients were selected. Peripheral blood lymphocytes were isolated, and E-NTPDase and E-ADA activities were assayed. The results demonstrated an increased E-NTPDase activity (both ATP and ADP as substrates) and a decreased E-ADA activity in RA patients. These data suggest an organic effort to preserve the adenosine level, which is known to have anti-inflammatory and analgesic properties, working as a potent suppressor of immune response.

Effects of curcumin on the activities of the enzymes that hydrolyse adenine nucleotides in platelets from cigarette smoke-exposed rats

The aim of the present study was to investigate the effect of curcumin (Cur) on the activity of ectonucleoside triphosphate diphosphohydrolase (CD39), 5'-nucleotidase (CD73) and adenosine deaminase in platelets of cigarette smoke-exposed rats. For that purpose, we subjected male Wistar rats to a treatment with Cur and cigarette smoke, once a day, 5 days each week, for 30 days. The rats were treated by gavage with Cur or corn oil and then exposed to cigarette smoke. The experimental procedures were divided into two sets of experiments. In the first, the animals were divided into four groups: vehicle (corn oil) or Cur 12·5, 25 or 50 mg·kg(-1) . In the second, the animals were divided into five groups: vehicle (corn oil), smoke, or smoke and Cur 12·5, 25 or 50 mg·kg(-1) . The results showed that treatment with Cur significantly prevented the increased adenosine triphosphate (ATP) (121%) and adenosine monophosphate (AMP) (159%) and the decreased adenosine diphosphate (ADP) (51%) hydrolysis observed in the cigarette smoke-exposed rats Our results suggest that those purinergic enzyme alterations observed in the cigarette smoke-exposed rats could be related to an excessive platelet aggregation and point toward the potential of Cur to modulate purinergic signalling and, consequently, regulate the thrombus formation.

A method for isolation of rat lymphocyte-rich mononuclear cells from lung tissue useful for determination of nucleoside triphosphate diphosphohydrolase activity

Methods for the isolation of peripheral blood mononuclear cells (PBMCs) and human lung mononuclear cells (LMCs) have been proposed previously. This study describes a method that allows the separation of lymphocyte-rich LMCs from rats. Trypan blue was applied to determine cell viability. White blood cell and differential cell counts were also performed. Relationships between nucleoside triphosphate diphosphohydrolase (NTPDase, EC 3.6.1.5) activities expressed in milligrams of protein, millions of cells, and millions of viable cells were examined as linear correlations. The lung tissue yielded 82.46% lymphocytes, 8.6% macrophages, 2.20% monocytes, and 1.27% polymorphonuclear cells (PMNs). In LMCs, a very strong correlation was observed as follows: between NTPDase activity, as determined using ATP or ADP as a substrate, expressed in milligrams of protein and that expressed in millions of cells (r ≥ 0.91), between that expressed in milligrams of protein and that expressed in millions of viable cells (r ≥ 0.91), and between that expressed in millions of cells and that expressed in millions of viable cells (r ≥ 0.98). Based on our results, we affirm that NTPDase activity could be expressed in millions of viable cells, millions of cells, or milligrams of protein.