Acciones de los prostanoides en la fisiopatología cardiovascular

Prostaglandins (PGs) and thromboxanes (TXs) play a pivotal role in cardiovascular physiopathology. They are synthesized from arachidonic acid by the enzymatic action of cyclooxygenases (COXs), leading to the production of an unstable intermediate, PGH2 that is subsequently converted to the different prostaglandins and thromboxanes (PGE2, PGD2, PGI2, PGF2a and TXA2) by the action of different synthases and isomerases. There are two well characterized COX enzymes, termed COX-1 and COX-2, with different properties. While COX-1 is expressed constitutively in most tissues and is thought to be involved in homeostatic prostanoid biosynthesis, COX-2 is transcriptionally up-regulated in response to mitogens and pro-inflammatory stimuli being the predominant isoform involved in the inflammatory response. In the cardiovascular system, prostanoids have been shown to modulate the pathogenesis of vascular diseases as thrombosis and atherosclerosis through a variety of processes, including platelet aggregation, vasorelaxation and vasoconstriction, local inflammatory response and leukocyte-endothelial cell adhesion. Multiple studies using pharmacological inhibitors and genetically deficient mice have demonstrated the importance of prostanoid-mediated actions on cardiovascular physiology. However, recent withdrawal of COX-2 selective inhibitors from the clinic because of their adverse effects in patients with potential cardiovascular risk has opened a debate about the role of COX–derived prostanoids in vascular pathologies and the benefits and risks for the use of COX inhibitors in cardiovascular diseases.Key Words: Prostaglandins, Thromboxanes, Cyclooxygenases, Prostanoid receptors, NSAIDs, Cardiovascular physiopathology.Las prostaglandinas (PGs) y los tromboxanos (TXs) juegan un papel esencial en la fisiopatología cardiovascular. Estos prostanoides son sintetizados a través de la acción enzimática de las ciclooxigenasas (COXs) sobre el ácido araquidónico, lo que lleva a la producción de un intermediario inestable, la PGH2, a partir de la cual diversas sintetasas e isomerasas generarán las diferentes prostaglandinas y tromboxanos (PGE2, PGD2, PGI2, PGF2a and TXA2). Existen dos ciclooxigenasas bien caracterizadas denominadas COX-1 y COX-2, con diferentes propiedades. COX-1 se expresa constitutivamente en la mayoría de los tejidos, estando implicada en la biosíntesis de prostanoides con funciones homeostáticas. Por otro lado, la expresión de COX-2 se induce en respuesta a mitógenos y estímulos pro-inflamatorios, constituyendo la isoforma predominantemente implicada en la respuesta inflamatoria. Los prostanoides modulan la patogénesis de enfermedades vasculares como la trombosis y la aterosclerosis a través de una serie de procesos como: la agregación plaquetaria, la vasodilatación y vasoconstricción, y la respuesta inflamatoria local. Múltiples estudios han demostrado la importancia de las acciones mediadas por los prostanoides en la fisiopatología cardiovascular, bien mediante el uso de inhibidores farmacológicos o a través del análisis de ratones genéticamente deficientes. Sin embargo, la reciente retirada del mercado de inhibidores selectivos de COX-2 a causa de sus efectos adversos en pacientes con riesgo cardiovascular, ha abierto el debate sobre el papel de los prostanoides en la patología vascular y sobre las ventajas o inconvenientes del uso de inhibidores de COXs en las enfermedades cardiovasculares.Palabras clave: Prostaglandinas, Tromboxanos, Ciclooxigenasas, Receptores de prostanoides, AINEs, Fisiopatología cardiovascular

Role of Peroxisome Proliferator-Activated Receptor Alpha in the Control of Cyclooxygenase 2 and Vascular Endothelial Growth Factor: Involvement in Tumor Growth

A growing body of evidence indicates that PPAR (peroxisome proliferator-activated receptor) α agonists might have therapeutic usefulness in antitumoral therapy by decreasing abnormal cell growth, and reducing tumoral angiogenesis. Most of the anti-inflammatory and antineoplastic properties of PPAR ligands are due to their inhibitory effects on transcription of a variety of genes involved in inflammation, cell growth and angiogenesis. Cyclooxygenase (COX)-2 and vascular endothelial growth factor (VEGF) are crucial agents in inflammatory and angiogenic processes. They also have been significantly associated to cell proliferation, tumor growth, and metastasis, promoting tumor-associated angiogenesis. Aberrant expression of VEGF and COX-2 has been observed in a variety of tumors, pointing to these proteins as important therapeutic targets in the treatment of pathological angiogenesis and tumor growth. This review summarizes the current understanding of the role of PPARα and its ligands in the regulation of COX-2 and VEGF gene expression in the context of tumor progression

Estudio de las acciones de la prostaglandina F2 alfa y de los glucocorticoides sobre la activación de linfocitos T

Tesis doctoral inédita, leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 18-03-2010Cyclooxygenase (COX) is the enzyme responsible for the conversion of arachidonic acid to prostaglandin PGH2, which is further metabolized by a series of downstream synthases to the prostanoids. Indeed, the expression of the particular downstream enzyme and its coupling either to constitutively expressed COX-1 or to inducible COX-2 will determine the profile and levels of arachidonic metabolites released by cells. In T cells, it has been shown that transcriptional induction of COX-2 occurs early after T cell receptor triggering, suggesting functional implications of COX-2 activity in this process. However, little is known about the expression of terminal prostanoid synthases in T cells. Therefore, in the present study, we analized the expression of these enzymes in activated T cells and characterized the profile of prostanoid production. Our results show an up-regulated PGE2 and PGF2α production and a concomitant up-regulated expression of the prostaglandin F synthase whereas up-regulated expression of any of the PGE2 synthases was not observed. Because the role of PGE2 in T cells has been extensively studied, we focused on the role of prostaglandin F2α showing that this prostaglandin, upon binding to its receptor (FP), is able to induce the expression of proinflammatory genes involved in T cell activation, including COX-2 and several cytokines. In addition, we show that PGF2α activates the NFAT transcription factor that plays an essential role in the regulation of these genes in T cells. It is well known that optimal NFAT activation requires low sustained increases of [Ca2+i]. Accordingly, our results suggest the involvement of signalling triggered by Gq -coupled receptors as FP in the activation of NFAT and the induction of the expression of NFAT–dependent genes. Another aim of this work has been to analyze the anti-inflammatory properties of GCs in T lymphocytes. Our results show that the synthetic GC Dexamethasone (Dex) decreased the expression of pro-inflammatory genes as COX-2. This effect took place also at the transcriptional level, since this drug decreased the induction of the promoter activity of these genes. Studies with the promoter region of COX-2 have determined that inhibition of COX-2 transcriptional induction in T cells by Dex/GR is due to transcriptional interference with NFAT mediated activation of COX-2 promoter. Our results are suggestive for the existence of protein-protein interactions between activated GR and NFAT within the nuclear environment, what mediates interference with NFAT-dependent transactivation of several genes implicated in T cell activation. These interactions are mediated by glucocorticoid binding to the GR but are independent of the presence of a functional DBD in this receptor. On the other hand, Dex induced the mRNA levels of haematopoietic prostaglandin D synthase (hPGDS) and peroxisome proliferator-activated receptor (PPAR), being both considered anti-inflammatory genes. The observed effects are dependent on the presence of the GC receptor (GR). These results can explain some of the anti-inflammatory properties of GCs, not only through their inhibitory actions on pro-inflammatory genes but also through the induction of anti-inflammatory genes as hPGDS and PPAR

Circulating immune complexes levels correlate with the progression of canine leishmaniosis in naturally infected dogs

Dogs are the main domestic reservoir of Leishmania infantum, and in cases of uncontrolled infection, a strong humoral immune response is elicited, which is inefficient against the parasites. Previous studies have suggested that an adequate antigen/antibody ratio, with a moderate prevalence of antigens with respect to the antibodies, could result in the formation of circulating immune complexes (CIC) in canine leishmaniosis (CanL). Deposition of these complexes in tissues has been associated with vasculitis, uveitis, arthritis, dermatitis and especially glomerulonephritis and renal failure. However, little is known about the relationship between the presence of CIC and disease progression. The aim of this study was to evaluate serum CIC level and its correlation with disease severity in infected dogs with different stages of disease and non-infected animals as a control. A total of 60 dogs were included in the study, classified according to the proposed LeishVet classification criteria: healthy non-infected (n = 13); healthy infected (n = 12); sick stage I (n = 9); sick stage II (n = 17); sick stage III (n = 8); and sick stage IV (n = 1). CIC were isolated from serum samples using a modified polyethylene glycol precipitation method, and their levels measured by ELISA and bicinchoninic acid protein assay. A nanoparticle tracking analysis was performed to investigate the relationship between the molecular size distribution of the CIC and disease progression. In conclusion, the results confirmed a positive association between CIC levels, their molecular size and disease progression that suggests a potential use of CIC as biomarkers of CanL

Regulation of Cyclooxygenase-2 Expression in Human T Cells by Glucocorticoid Receptor-Mediated Transrepression of Nuclear Factor of Activated T Cells

Cyclooxygenase (COX) is the key enzyme in prostanoid synthesis from arachidonic acid (AA). Two isoforms, named COX-1 and COX-2, are expressed in mammalian tissues. The expression of COX-2 isoform is induced by several stimuli including cytokines and mitogens, and this induction is inhibited by glucocorticoids (GCs). We have previously shown that the transcriptional induction of COX-2 occurs early after T cell receptor (TCR) triggering, suggesting functional implications of this enzyme in T cell activation. Here, we show that dexamethasone (Dex) inhibits nuclear factor of activated T cells (NFAT)-mediated COX-2 transcriptional induction upon T cell activation. This effect is dependent on the presence of the GC receptor (GR), but independent of a functional DNA binding domain, as the activation-deficient GRLS7 mutant was as effective as the wild-type GR in the repression of NFAT-dependent transcription. Dex treatment did not disturb NFAT dephosphorylation, but interfered with activation mediated by the N-terminal transactivation domain (TAD) of NFAT, thus pointing to a negative cross-talk between GR and NFAT at the nuclear level. These results unveil the ability of GCs to interfere with NFAT activation and the induction of pro-inflammatory genes such as COX-2, and explain some of their immunomodulatory properties in activated human T cells

Clinical validation of circulating immune complexes for use as a diagnostic marker of canine leishmaniosis

Author contributions: JS: Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Writing – original draft, Writing – review & editing. NP: Investigation, Validation, Writing – review & editing. AM: Resources, Writing – review & editing. CC-L: Investigation, Validation, Writing – review & editing. JB: Resources, Writing – review & editing. RC: Resources, Writing – review & editing. MD: Resources, Writing – review & editing. JC: Conceptualization, Funding acquisition, Project administration, Supervision, Writing – review & editing. GM: Conceptualization, Funding acquisition, Methodology, Project administration, Resources, Supervision, Writing – review & editing.Canine leishmaniosis (CanL) is a systemic disease that affects dogs. When multiplication of the parasite cannot be controlled, dogs consistently show high levels of antigen and IgG antibodies, which lead to the formation of circulating immune complexes (CIC). Timely intervention to reduce the parasite load and CIC levels is crucial for preventing irreversible organ damage. However, a diagnostic test to quantify CIC levels is currently lacking. In this real-world study, we aimed to examine the performance of a new ELISA to measure CIC levels in dogs naturally infected with Leishmania infantum. Thirty-four dogs were treated according to their clinical condition and followed for 360 days. Before (day 0) and after treatment (days 30, 90, 180, 270, and 360), all dogs underwent a physical examination, and blood samples were obtained for CBC, biochemical profile, serum protein electrophoresis and IFAT. Serum PEG-precipitated CIC were determined by ELISA. Our results indicate higher CIC levels in dogs in advanced disease stages showing higher antibody titres (p  <  0.0001, r  =  0.735), anemia (p  <  0.0001), dysproteinemia (p  <  0.0001), and proteinuria (p  =  0.004). Importantly, dogs responding well to treatment exhibited declining CIC levels (p  <  0.0001), while in poor responders and those experiencing relapses, CIC were consistently elevated. CIC emerged as a robust discriminator of relapse, with an area under the curve (AUC) of 0.808. The optimal cut-off to accurately identify relapse was an optical density of 1.539. Our findings suggest that declining CIC levels should be expected in dogs showing a favorable treatment response. Conversely, in dogs displaying a poor response and recurrent clinical relapses, CIC levels will be high, emphasizing the need for vigilant monitoring. These findings suggest that CIC could serve as a valuable biomarker for disease progression, treatment efficacy, and relapse detection in CanL. Our study contributes to enhancing diagnostic approaches for CanL and underscores the potential of CIC as a complementary tool in veterinary practice. As we move forward, larger studies will be essential to confirm these findings and establish definitive cut-offs for clinical application.Depto. de Sanidad AnimalFac. de VeterinariaTRUEpu