P2X7 Receptor Regulates Collagen Expression in Human Intestinal Fibroblasts: Relevance in Intestinal Fibrosis.

Intestinal fibrosis is a common complication that affects more than 50% of Crohn´s Disease (CD) patients. There is no pharmacological treatment against this complication, with surgery being the only option. Due to the unknown role of P2X7 in intestinal fibrosis, we aim to analyze the relevance of this receptor in CD complications. Surgical resections from CD and non-Inflammatory Bowel Disease (IBD) patients were obtained. Intestinal fibrosis was induced with two different murine models: heterotopic transplant model and chronic-DSS colitis in wild-type and P2X7-/- mice. Human small intestine fibroblasts (HSIFs) were transfected with an siRNA against P2X7 and treated with TGF-ß. A gene and protein expression of P2X7 receptor was significantly increased in CD compared to non-IBD patients. The lack of P2X7 in mice provoked an enhanced collagen deposition and increased expression of several profibrotic markers in both murine models of intestinal fibrosis. Furthermore, P2X7-/- mice exhibited a higher expression of proinflammatory cytokines and a lower expression of M2 macrophage markers. Moreover, the transient silencing of the P2X7 receptor in HSIFs significantly induced the expression of Col1a1 and potentiated the expression of Col4 and Col5a1 after TGF-ß treatment. P2X7 regulates collagen expression in human intestinal fibroblasts, while the lack of this receptor aggravates intestinal fibrosis.

Abacavir causes leukocyte/platelet crosstalk by activating neutrophil P2X7 receptors thus releasing soluble lectin-like oxidized low-density lipoprotein receptor-1.

BACKGROUND AND PURPOSE: Abacavir, an antiretroviral drug used in HIV therapy associated with myocardial infarction, promotes thrombosis through P2X7 receptors. The role of platelets as pro-thrombotic cells is acknowledged whereas that of neutrophils-due to their secretory capacity-is gaining recognition. This study analyses the role of neutrophils-specifically the secretome of abacavir-treated neutrophils (SNABC )-in platelet activation that precedes thrombosis. EXPERIMENTAL APPROACH: Effects of abacavir or SNABC on platelet activation and platelet-leukocyte interactions and expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) were analysed by flow cytometry. The secretome was analysed by proteomics. The role of leukocytes in the actions of abacavir was evaluated in a mouse model of thrombosis. KEY RESULTS: Abacavir induced platelet-leukocyte interactions, not directly via effects of abacavir on platelets, but via activation of neutrophils, which triggered interactions between platelet P-selectin and neutrophil P-selectin glycoprotein ligand-1 (PSGL-1). SNABC stimulated platelet activation and platelet-leukocyte interactions through a process that was dependent on LOX-1, neutrophil P2X7 and platelet P2Y1, P2Y12 and P2X1 receptors. Abacavir induced the expression of LOX-1 on neutrophils and of the soluble form of LOX-1 (sLOX-1) in SNABC . Neutrophils, LOX-1, P2X7, P2Y1, P2Y12 and P2X1 receptors were required for the pro-thrombotic actions of abacavir in vivo. CONCLUSION AND IMPLICATIONS: Neutrophils are target cells in abacavir-induced thrombosis. Abacavir released sLOX-1 from neutrophils via activation of their P2X7 receptors, which in turn activated platelets. Hence, sLOX-1 could be the missing link in the cardiovascular risk associated with abacavir.

Macrophages Modulate Hepatic Injury Involving NLRP3 Inflammasome: The Example of Efavirenz.

Drug-induced liver injury (DILI) constitutes a clinical challenge due to the incomplete characterization of the mechanisms involved and potential risk factors. Efavirenz, an anti-HIV drug, induces deleterious actions in hepatocytes that could underlie induction of the NLRP3 inflammasome, an important regulator of inflammatory responses during liver injury. We assessed the potential of efavirenz to modulate the inflammatory and fibrogenic responses of major liver cell types involved in DILI. The effects of efavirenz were evaluated both in vitro and in vivo. Efavirenz triggered inflammation in hepatocytes, in a process that involved NF-κB and the NLRP3 inflammasome, and activated hepatic stellate cells (HSCs), thereby enhancing expression of inflammatory and fibrogenic markers. The NLRP3 inflammasome was not altered in efavirenz-treated macrophages, but these cells polarized towards the anti-inflammatory M2 phenotype and displayed upregulated anti-inflammatory mediators. Conversely, no evidence of damage was observed in efavirenz-treated animals, except when macrophages were depleted, which resulted in the in vivo manifestation of the deleterious effects detected in hepatocytes and HSCs. Efavirenz elicits a cell-specific activation of the NLRP3 inflammasome in hepatocytes and HSCs, but macrophages appear to counteract efavirenz-induced liver injury. Our results highlight the dynamic nature of the interaction among liver cell populations and emphasize the potential of targeting macrophage polarization as a strategy to treat NLRP3 inflammasome-induced liver injury.

Hypercholesterolemic patients have higher eryptosis and erythrocyte adhesion to human endothelium independently of statin therapy.

BACKGROUND: Phosphatidylserine (PS) externalization out of the membrane facilitates the eryptotic erythrocytes (EE) binding to endothelial cells (EC), potentially leading to atherosclerosis. Thus, the levels of eryptosis and interactions of EE-EC in hypercholesterolemic patients, either non-medicated or medicated, compared with healthy subjects were studied. METHODS: A total of 56 subjects clustered into three groups: (control (n = 20), hypercholesterolemic non-treated (HCNT) (n = 15), and statin-treated (HCT) (n = 21)) were enrolled in this cross-sectional study. Biochemical parameters were determined with validated and standard methods. PS exposure was estimated from annexin-V-binding, cell volume from forward scatter (FSC), and GSH from CMFDA fluorescence by flow cytometry. The erythrocyte-EC adhesion assay was performed by using the parallel-plate flow chamber technique. RESULTS: Higher PS externalization and adhesion of erythrocytes to EC (P < .05) was found in hypercholesterolemic subjects, regardless of statin treatment, compared with the control group. Although no correlation between FSC and PS externalization with other parameters was found, GSH was inversely correlated with erythrocyte adhesion, which was significantly correlated with total cholesterol, LDL-c, and apolipoprotein B. CONCLUSION: The link between hypercholesterolemia and eryptosis suggests a possible detrimental impact of this binomial on endothelial function with possible further development of atherosclerosis and microcirculation problems in hypercholesterolemic patients, independently of statin therapy.

Abacavir Increases Purinergic P2X7 Receptor Activation by ATP: Does a Pro-inflammatory Synergism Underlie Its Cardiovascular Toxicity?

The cardiovascular toxicity of Abacavir is related to its purinergic structure. Purinergic P2X7-receptors (P2X7R), characterized by activation by high concentrations of ATP and with high plasticity, seem implicated. We appraise the nature of the interplay between Abacavir and P2X7R in generating vascular inflammation. The effects of Abacavir on leukocyte-endothelium interactions were compared with those of its metabolite carbovir triphosphate (CBV-TP) or ATP in the presence of apyrase (ATP-ase) or A804598 (P2X7R-antagonist). CBV-TP and ATP levels were evaluated by HPLC, while binding of Abacavir, CBV-TP and ATP to P2X7R was assessed by radioligand and docking studies. Hypersensitivity studies explored a potential allosteric action of Abacavir. Clinical concentrations of Abacavir (20 µmol/L) induced leukocyte-endothelial cell interactions by specifically activating P2X7R, but the drug did not show affinity for the P2X7R ATP-binding site (site 1). CBV-TP levels were undetectable in Abacavir-treated cells, while those of ATP were unaltered. The effects of Abacavir were Apyrase-dependent, implying dependence on endogenous ATP. Exogenous ATP induced a profile of proinflammatory actions similar to Abacavir, but was not entirely P2X7R-dependent. Docking calculations suggested ATP-binding to sites 1 and 2, and Abacavir-binding only to allosteric site 2. A combination of concentrations of Abacavir (1 µmol/L) and ATP (0.1 µmol/L) that had no effect when administered separately induced leukocyte-endothelium interactions mediated by P2X7R and involving Connexin43 channels. Therefore, Abacavir acts as a positive allosteric modulator of P2X7R, turning low concentrations of endogenous ATP themselves incapable of stimulating P2X7R into a functional proinflammatory agonist of the receptor.

The Neutrophil Secretome as a Crucial Link between Inflammation and Thrombosis.

Cardiovascular diseases are a leading cause of death. Blood-cell interactions and endothelial dysfunction are fundamental in thrombus formation, and so further knowledge of the pathways involved in such cellular crosstalk could lead to new therapeutical approaches. Neutrophils are secretory cells that release well-known soluble inflammatory signaling mediators and other complex cellular structures whose role is not fully understood. Studies have reported that neutrophil extracellular vesicles (EVs) and neutrophil extracellular traps (NETs) contribute to thrombosis. The objective of this review is to study the role of EVs and NETs as key factors in the transition from inflammation to thrombosis. The neutrophil secretome can promote thrombosis due to the presence of different factors in the EVs bilayer that can trigger blood clotting, and to the release of soluble mediators that induce platelet activation or aggregation. On the other hand, one of the main pathways by which NETs induce thrombosis is through the creation of a scaffold to which platelets and other blood cells adhere. In this context, platelet activation has been associated with the induction of NETs release. Hence, the structure and composition of EVs and NETs, as well as the feedback mechanism between the two processes that causes pathological thrombus formation, require exhaustive analysis to clarify their role in thrombosis.

Role of Neutrophil Extracellular Traps in COVID-19 Progression: An Insight for Effective Treatment.

The coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, has resulted in a pandemic with over 270 million confirmed cases and 5.3 million deaths worldwide. In some cases, the infection leads to acute respiratory distress syndrome (ARDS), which is triggered by a cytokine storm and multiple organ failure. Clinical hematological, biochemical, coagulation, and inflammatory markers, such as interleukins, are associated with COVID-19 disease progression. In this regard, neutrophilia, neutrophil-to-lymphocyte ratio (NLR), and neutrophil-to-albumin ratio (NAR), have emerged as promising biomarkers of disease severity and progression. In the pathophysiology of ARDS, the inflammatory environment induces neutrophil influx and activation in the lungs, promoting the release of cytokines, proteases, reactive oxygen species (ROS), and, eventually, neutrophil extracellular traps (NETs). NETs components, such as DNA, histones, myeloperoxidase, and elastase, may exert cytotoxic activity and alveolar damage. Thus, NETs have also been described as potential biomarkers of COVID-19 prognosis. Several studies have demonstrated that NETs are induced in COVID-19 patients, and that the highest levels of NETs are found in critical ones, therefore highlighting a correlation between NETs and severity of the disease. Knowledge of NETs signaling pathways, and the targeting of points of NETs release, could help to develop an effective treatment for COVID-19, and specifically for severe cases, which would help to manage the pandemic.

Transfusión de plasma convaleciente de pacientes con COVID-19 / Transfusion of convalescent plasma from patients with COVID -19

RESUMEN Actualmente no existe vacuna disponible ni medicación específica contra la enfermedad por coronavirus 2019 (COVID-19). El tratamiento se basa fundamentalmente en medidas de soporte. En este contexto, se han aprobado múltiples terapias de potencial utilidad para su uso en ensayos clínicos, como la transfusión de plasma convaleciente (TPC). Se realizó una búsqueda en PubMed de estudios sobre plasma convaleciente y COVID-19, SARS o MERS. Los estudios sobre la eficacia clínica en enfermedades causadas por otros coronavirus (SARS-CoV y MERS-CoV) evidenciaron mejoría clínica, aumento de anticuerpos neutralizantes, disminución de la mortalidad y ausencia de eventos adversos durante y después del tratamiento. En el caso de la COVID-19, se encontraron 13 estudios en pacientes con la COVID-19 grave y crítica. Aunque existen limitaciones en la metodología, en el número de pacientes y en los protocolos para el análisis del plasma convaleciente de los donantes, los pacientes que recibieron TPC evidenciaron mejoría clínica, mejoría de patrones ventilatorios, resolución de lesiones pulmonares, disminución de mortalidad, mejoría de parámetros laboratoriales, aumento de anticuerpos neutralizantes, disminución de carga viral y baja frecuencia de eventos adversos.

ABSTRACT There is currently no vaccine available and no specific medication against Coronavirus 2019 disease (COVID-19). The treatment is mainly based on support measures. In this context, several potentially useful therapies have been approved for use in clinical trials, such as convalescent plasma transfusion (CPT). PubMed was searched for studies on convalescent plasma and COVID-19, SARS or MERS. Studies on clinical efficacy in diseases caused by other coronaviruses (SARS-CoV and MERS-CoV) showed clinical improvement, increase of neutralizing antibodies, decreased mortality and absence of adverse events during and after treatment. We found 13 studies on this type of treatment used in patients with severe and critical COVID-19. Despite limitations regarding methodology, number of patients and the protocols for the analysis of donors' convalescent plasma, patients who received CPT showed clinical improvement, improvement of ventilatory patterns, resolution of lung injuries, decreased mortality, improvement of laboratory parameters, increase of neutralizing antibodies, decreased viral load and low frequency of adverse events.

Structural and Functional Basis for Understanding the Biological Significance of P2X7 Receptor.

The P2X7 receptor (P2X7R) possesses a unique structure associated to an as yet not fully understood mechanism of action that facilitates cell permeability to large ionic molecules through the receptor itself and/or nearby membrane proteins. High extracellular adenosine triphosphate (ATP) levels-inexistent in physiological conditions-are required for the receptor to be triggered and contribute to its role in cell damage signaling. The inconsistent data on its activation pathways and the few studies performed in natively expressed human P2X7R have led us to review the structure, activation pathways, and specific cellular location of P2X7R in order to analyze its biological relevance. The ATP-gated P2X7R is a homo-trimeric receptor channel that is occasionally hetero-trimeric and highly polymorphic, with at least nine human splice variants. It is localized predominantly in the cellular membrane and has a characteristic plasticity due to an extended C-termini, which confers it the capacity of interacting with membrane structural compounds and/or intracellular signaling messengers to mediate flexible transduction pathways. Diverse drugs and a few endogenous molecules have been highlighted as extracellular allosteric modulators of P2X7R. Therefore, studies in human cells that constitutively express P2X7R need to investigate the precise endogenous mediator located nearby the activation/modulation domains of the receptor. Such research could help us understand the possible physiological ATP-mediated P2X7R homeostasis signaling.

Leukocyte-Endothelium Interaction Is Associated with Fat Mass in Children.

OBJECTIVE: To study leukocyte-endothelium interaction, a measure of the initial phase of atheromatosis, in children with overweight or obesity. STUDY DESIGN: A prospective study was conducted in 77 children aged 7-16 years; 47 were children with overweight/obesity and 30 were normal weight. Polymorphonuclear neutrophils (PMNs) and peripheral blood mononuclear cells were isolated from venous blood samples and the interaction of leukocytes over a monolayer of human umbilical vein endothelial cells was analyzed using flow chamber microscopy. The variables studied included leukocyte rolling velocity, rolling flux, and adhesion to endothelial cells. These were compared between children with overweight/obesity and control children. Correlation between the measures of leukocyte-endothelium interaction and anthropometric and biochemical variables was evaluated. RESULTS: In comparison with normal weight children, the PMNs and peripheral blood mononuclear cells of the overweight/obesity group showed a reduction in rolling velocity (P = .000 and P = .001, respectively) and an increase in rolling flux (P = .001 and P = .004), and adhesion (P = .003 and P = .002). The homeostasis model of insulin resistance was correlated inversely with rolling velocity and positively with rolling flux in PMNs. C-reactive protein was correlated positively with rolling flux and adhesion in both types of leucocytes. Fat mass index was correlated with all measures of leukocyte-endothelial interaction and proved to be the main predictor of leukocyte adhesion in the multiple regression analysis (P = .001 for PMNs and P = .006 for peripheral blood mononuclear cells). CONCLUSIONS: Excess fat mass in children is related to the activation of the leukocyte-endothelium interaction, potentially contributing to the development of atherosclerosis.

Convalescent plasma transfusion of COVID-19 patients: Proposal from the Peruvian Immunology Society and the Peruvian Medical Association of Clinical Pathology for its implementation in our country / Transfusión de plasma convaleciente de pacientes con COVID-19: Propuesta de la Sociedad Peruana de Inmunología y la Asociación Médica Peruana de Patología Clínica para su implementación en nuestro país

Currently, there is no available vaccine or specific medication against Coronavirus Disease 2019 (COVID-19). The treatment is fundamentally based on supportive measures. In recent weeks, in various parts of the world, including our country, there have been flexibilities for the scientific community to conduct clinical trials with potentially useful therapies, such as the case of convalescent plasma transfusion (CPT) of patients with COVID-19. A MEDLINE search of studies on convalescent plasma and COVID-19, SARS or MERS was performed. Studies on the clinical efficacy of this treatment in diseases caused by other coronaviruses (SARS-CoV and MERS-CoV) showed clinical improvement, increased neutralizing antibodies, decreased mortality and the absence of adverse events during and after treatment. In the case of COVID-19, 6 studies were found of the use of this treatment in patients with severe COVID-19 (in mechanical ventilation and with acute respiratory distress syndrome). Although there are limitations in the methodology, number of patients and protocols for the analysis of convalescent plasma from donors, the patients who received CPT showed clinical improvement, improvement in ventilatory patterns, resolution of lung lesions, decreased mortality, improvement in laboratory parameters, increased neutralizing antibodies, decreased viral load and absence of adverse events. We also present a protocol for carrying out TPC and proposals for its implementation and use in our country.

Actualmente no existe vacuna disponible ni medicación específica contra la enfermedad de Coronavirus 2019 (COVID-19). El tratamiento se basa fundamentalmente en medidas de soporte. En las últimas semanas, en varias partes del mundo, incluido nuestro país, se han dado flexibilidades para que la comunidad científica conduzca ensayos clínicos con terapias de potencial utilidad, como es el caso de la transfusión de plasma convaleciente (TPC) de pacientes con COVID-19. Se realizó una búsqueda en MEDLINE de estudios sobre plasma convaleciente y COVID-19, SARS o MERS. Los estudios sobre la eficacia clínica de este tratamiento en enfermedades causadas por otros coronavirus (SARS-CoV y MERS-CoV) evidenciaron mejoría clínica, aumento de anticuerpos neutralizantes, disminución de mortalidad y ausencia de eventos adversos durante y después del tratamiento. En el caso del COVID-19, se encontraron 6 estudios del uso de este tratamiento en pacientes con COVID-19 severo (en ventilación mecánica y con síndrome de distrés respiratorio agudo). Aunque existen limitaciones en la metodología, número de pacientes y protocolos para el análisis del plasma convaleciente de los donantes, los pacientes que recibieron TPC evidenciaron mejoría clínica, mejoría de patrones ventilatorios, resolución de lesiones pulmonares, disminución de mortalidad, mejoría de parámetros laboratoriales, aumento de anticuerpos neutralizantes, disminución de carga viral y ausencia de eventos adversos. Presentamos además un protocolo de realización de TPC y propuestas para su implementación y uso en nuestro país.

[Transfusion of convalescent plasma from patients with COVID -19]. / Transfusión de plasma convaleciente de pacientes con COVID-19.

There is currently no vaccine available and no specific medication against Coronavirus 2019 disease (COVID-19). The treatment is mainly based on support measures. In this context, several potentially useful therapies have been approved for use in clinical trials, such as convalescent plasma transfusion (CPT). PubMed was searched for studies on convalescent plasma and COVID-19, SARS or MERS. Studies on clinical efficacy in diseases caused by other coronaviruses (SARS-CoV and MERS-CoV) showed clinical improvement, increase of neutralizing antibodies, decreased mortality and absence of adverse events during and after treatment. We found 13 studies on this type of treatment used in patients with severe and critical COVID-19. Despite limitations regarding methodology, number of patients and the protocols for the analysis of donors' convalescent plasma, patients who received CPT showed clinical improvement, improvement of ventilatory patterns, resolution of lung injuries, decreased mortality, improvement of laboratory parameters, increase of neutralizing antibodies, decreased viral load and low frequency of adverse events.

Actualmente no existe vacuna disponible ni medicación específica contra la enfermedad por coronavirus 2019 (COVID-19). El tratamiento se basa fundamentalmente en medidas de soporte. En este contexto, se han aprobado múltiples terapias de potencial utilidad para su uso en ensayos clínicos, como la transfusión de plasma convaleciente (TPC). Se realizó una búsqueda en PubMed de estudios sobre plasma convaleciente y COVID-19, SARS o MERS. Los estudios sobre la eficacia clínica en enfermedades causadas por otros coronavirus (SARS-CoV y MERS-CoV) evidenciaron mejoría clínica, aumento de anticuerpos neutralizantes, disminución de la mortalidad y ausencia de eventos adversos durante y después del tratamiento. En el caso de la COVID-19, se encontraron 13 estudios en pacientes con la COVID-19 grave y crítica. Aunque existen limitaciones en la metodología, en el número de pacientes y en los protocolos para el análisis del plasma convaleciente de los donantes, los pacientes que recibieron TPC evidenciaron mejoría clínica, mejoría de patrones ventilatorios, resolución de lesiones pulmonares, disminución de mortalidad, mejoría de parámetros laboratoriales, aumento de anticuerpos neutralizantes, disminución de carga viral y baja frecuencia de eventos adversos.

Malnutrition impairs mitochondrial function and leukocyte activation.

BACKGROUND: The aim of this study was to evaluate markers of inflammation, oxidative stress and endothelial function in a disease-related malnutrition (DRM) outpatient population. METHODS: For this cross-sectional study, a total of 83 subjects were included and clustered in 3 groups: 34 with normonutrition (NN), 21 with DRM without inflammation (DRM-I) and 28 with DRM and inflammation (DRM + I). Nutritional diagnosis was conducted for all subjects according to ASPEN. Biochemical parameters, proinflammatory cytokines, reactive oxygen species production, glutathione, mitochondrial membrane potential, oxygen consumption, adhesion molecules and leukocyte-endothelium interactions were evaluated. RESULTS: DRM + I patients showed lower albumin, prealbumin, transferrin, and retinol-binding protein levels with respect to the NN group (p < 0.05), differences that were less noticeable in the DRM-I group. DRM + I was associated with a significant increase in hsCRP and IL6 vs the NN and DRM-I groups, and TNFα was increased in both DRM vs NN. DRM was characterised by increased oxidative stress, which was marked by a significant increase in ROS levels and a decrease in mitochondrial membrane potential in the DRM + I group. An evident reduction in mitochondrial oxygen consumption and glutathione concentration was observed in both DRM groups, and was accompanied by increased leukocyte adhesion and adhesion molecules and decreased rolling velocity in the DRM + I group. Furthermore, percentage of weight loss was negatively correlated with albumin, prealbumin, transferrin, O2 consumption, glutathione and leukocyte rolling velocity, and positively correlated with hsCRP, IL6, TNFα, ROS, leukocyte adhesion, and VCAM-1. CONCLUSIONS: Our results show that DRM is associated with oxidative stress and an inflammatory state, with a deterioration of endothelial dysfunction in the DRM + I population.

Obesity impairs leukocyte-endothelium cell interactions and oxidative stress in humans.

BACKGROUND: To evaluate the relationship between leukocyte-endothelial cell interactions and oxidative stress parameters in non-diabetic patients with different grades of obesity. MATERIAL AND METHODS: For this cross-sectional study, 225 subjects were recruited from January 1, 2014 to December 31, 2016 and divided into groups according to BMI (<30 kg/m2 , 30-40 kg/m2 and >40 kg/m²). We determined clinical parameters, systemic inflammatory markers, soluble cellular adhesion molecules, leukocyte-endothelium cell interactions-rolling flux, velocity and adhesion-, oxidative stress parameters-total ROS, total superoxide, glutathione-and mitochondrial membrane potential in leukocytes. RESULTS: We verified that HOMA-IR and hsCRP increased progressively as obesity developed, whereas A1c, IL6 and TNFα were augmented in the BMI > 40 kg/m² group. The cellular adhesion molecule sP-selectin was increased in patients with obesity, while sICAM, total ROS, total superoxide and mitochondrial membrane potential were selectively higher in the BMI > 40 kg/m² group. Obesity induced a progressive decrease in rolling velocity and an enhancement of rolling flux and leukocyte adhesion. CONCLUSION: Our findings reveal that endothelial dysfunction markers are altered in human obesity and are associated with proinflammatory cytokines and increased oxidative stress parameters.

Abacavir Induces Arterial Thrombosis in a Murine Model.

Background: The purinergic system is known to underlie prothrombotic and proinflammatory vascular programs, making the profile of experimental actions demonstrated by abacavir compatible with thrombogenesis. However, direct evidence of a prothrombotic effect by the drug has been lacking. Methods: The present study appraised the effects of abacavir in a well-validated animal model of arterial thrombosis. The role of ATP-P2X7 receptors in the actions of the drug was also assessed, and the actions of recognized vascular-damaging agents and other nucleoside reverse-transcriptase inhibitors (NRTIs) were evaluated and compared to those of abacavir. Results: Abacavir dose-dependently promoted thrombus formation. This effect was reversed by a P2X7-receptor antagonist and was nonexistent in P2X7 knockout mice. The effects of abacavir were similar to those of diclofenac and rofecoxib. Other NRTIs had no thrombosis-related effects. Conclusion: Abacavir promotes arterial thrombosis through interference with purinergic signaling, suggesting a possible biological mechanism for the clinical association of abacavir with cardiovascular diseases.

Características hematológicas y bioquímicas en pacientes con y sin diabetes mellitus tipo 2 (DM2) sometidos a hemodiálisis durante un año de seguimiento / Hematologic and biochemical characteristics in patients with and without type 2 diabetes mellitus undergoing hemodialysis during a one-year follow-up period

Objetivo: Reportar si existen diferencias hematológicas y bioquímicas entre los pacientes con y sin diabetes mellitus tipo 2 (DM2) bajo tratamiento de hemodiálisis (HD). Materiales y métodos: Estudio observacional de cohorte retrospectiva de pacientes atendidos por el Programa de Salud renal en el Centro de Prevención de Enfermedad Renal S.A.C (CENPER) de Lima, Perú. Se compararon los parámetros hematológicos y bioquímicos de 3 pacientes con DM2 y 3 pacientes sin DM2 sometidos a HD. Resultados: Se encontraron diferencias significativas (p<0,05) en el porcentaje de linfocitos, el cociente linfocito/ monocito (LMR), la concentración de hemoglobina y hematocrito (menor en pacientes diabéticos), en el porcentaje de monocitos y en el cociente neutrófilo/ linfocitos (NLR) (mayor en pacientes diabéticos). En los parámetros bioquímicos solo se encontró diferencia significativa en la transaminasa TGO que está más elevada en pacientes diabéticos comparados con pacientes no diabéticos (p<0.005). Conclusiones: Diabetes es un factor importante asociado con inflamación, anemia, linfopenia y monocitosis en pacientes sometidos a HD. LMR fue el marcador más potente de inflamación en esta serie de pacientes. Estudios a mayor escala son requeridos para corroborar esta evidencia.

Objective: To report if there are hematologic and biochemical differences among patients with and without type 2 diabetes mellitus (T2DM) undergoing hemodialysis (HD). Materials and methods: An observational, retrospective, cohort study of patients treated in the Renal Health Program at the Centro de Prevención de Enfermedad Renal S.A.C. (CENPER) in Lima, Peru. The hematologic and biochemical parameters of 3 patients with T2DM and 3 patients without T2DM undergoing HD were compared. Results: Significant differences (p < 0.05) were found in the lymphocyte percentage, lymphocyte/monocyte ratio (LMR), hemoglobin and hematocrit concentration (lower in diabetic patients), monocyte percentage, and neutrophil/ lymphocyte ratio (NLR) (higher in diabetic patients). In the biochemical parameters, the only significant difference was found in the glutamic-oxaloacetic transaminase (GOT) value, which was higher in the diabetic patients compared with the non-diabetic patients (p < 0.005). Conclusions: Diabetes is an important factor linked to inflammation, anemia, lymphopenia and monocytosis in patients undergoing HD. The LMR was the most powerful marker of inflammation in this patient series. Larger-scale studies are required to verify this evidence.

Cardiovascular toxicity of abacavir: a clinical controversy in need of a pharmacological explanation.

: There is a long-lasting controversy surrounding an association between abacavir (ABC) and an increased risk of cardiovascular disease in HIV-positive patients. Although differing in their specifics, a number of published cohort studies and clinical trials support such an association, usually relating it to recent exposure to the drug, independently of traditional predisposing factors. However, other clinical trials have failed to reveal such a relation and have pointed to methodological differences to explain discrepancies. Significantly, the controversy has been fueled by the lack of a credible mechanism of action to justify the putative detrimental actions of ABC. There is a myriad of contradictory clinical indicators which are not clearly compatible with known profiles of either vascular physiopathology or pharmacological interference. However, basic research has recently hinted at altered homeostatic mechanisms, though this requires clinical validation. In particular, recurrent evidence - both clinical and experimental - relates ABC with vascular inflammation, a leading contributor to the atherosclerotic plaque and thrombosis. ABC's chemical structure is very close to that of endogenous purines (ATP, ADP and AMP), major paracrine signaling molecules capable of triggering prothrombotic and proinflammatory vascular programs. Other proposed mechanisms are a competitive inhibition of guanylyl cyclase in platelets and a subsequent decrease in cyclic guanosine monophosphate (cGMP). The present review aims to shed light on this complex subject by summarizing and critically evaluating all the available clinical data regarding a relationship between ABC and cardiovascular disease, and to put forward potential pharmacological explanations compatible with both the clinical scenario and experimental findings.

Abacavir induces platelet-endothelium interactions by interfering with purinergic signalling: A step from inflammation to thrombosis.

The controversy connecting Abacavir (ABC) with cardiovascular disease has been fuelled by the lack of a credible mechanism of action. ABC shares structural similarities with endogenous purines, signalling molecules capable of triggering prothrombotic/proinflammatory programmes. Platelets are leading actors in the process of thrombosis. Our study addresses the effects of ABC on interactions between platelets and other vascular cells, while exploring the adhesion molecules implicated and the potential interference with the purinergic signalling pathway. The effects of ABC on platelet aggregation and platelet-endothelium interactions were evaluated, respectively, with an aggregometer and a flow chamber system that reproduced conditions in vivo. The role of adhesion molecules and purinergic receptors in endothelial and platelet populations was assessed by selective pre-incubation with specific antagonists and antibodies. ABC and carbovir triphosphate (CBT) levels were evaluated by HPLC. The results showed that ABC promoted the adherence of platelets to endothelial cells, a crucial step for the formation of thrombi. This was not a consequence of a direct effect of ABC on platelets, but resulted from activation of the endothelium via purinergic ATP-P2X7 receptors, which subsequently triggered an interplay between P-selectin and ICAM-1 on endothelial cells with constitutively expressed GPIIb/IIIa and GPIbα on platelets. ABC did not induce platelet activation (P-selectin expression or Ca2+ mobilization) or aggregation, even at high concentrations. CBT levels in endothelial cells were lower than those required to induce platelet-endothelium interactions. Thus, ABC interference with endothelial purinergic signalling leads to platelet recruitment. This highlights the endothelium as the main cell target of ABC in this interaction, which is in line with previous experimental evidence that ABC induces manifestations of vascular inflammation.

The mitochondria-targeted antioxidant MitoQ modulates oxidative stress, inflammation and leukocyte-endothelium interactions in leukocytes isolated from type 2 diabetic patients.

It is not known if the mitochondria-targeted antioxidants such as mitoquinone (MitoQ) can modulate oxidative stress and leukocyte-endothelium interactions in T2D patients. We aimed to evaluate the beneficial effect of MitoQ on oxidative stress parameters and leukocyte-endothelium interactions in leukocytes of T2D patients. The study population consisted of 98 T2D patients and 71 control subjects. We assessed metabolic and anthropometric parameters, mitochondrial reactive oxygen species (ROS) production, glutathione peroxidase 1 (GPX-1), NFκB-p65, TNFα and leukocyte-endothelium interactions. Diabetic patients exhibited higher weight, BMI, waist circumference, SBP, DBP, glucose, insulin, HOMA-IR, HbA1c, triglycerides, hs-CRP and lower HDL-c with respect to controls. Mitochondrial ROS production was enhanced in T2D patients and decreased by MitoQ. The antioxidant also increased GPX-1 levels and PMN rolling velocity and decreased PMN rolling flux and PMN adhesion in T2D patients. NFκB-p65 and TNFα were augmented in T2D and were both reduced by MitoQ treatment. Our findings support that the antioxidant MitoQ has an anti-inflammatory and antioxidant action in the leukocytes of T2D patients by decreasing ROS production, leukocyte-endothelium interactions and TNFα through the action of NFκB. These data suggest that mitochondria-targeted antioxidants such as MitoQ should be investigated as a novel means of preventing cardiovascular events in T2D patients.