La vitamina C, implicaciones terapéuticas en el paciente con quemaduras graves / Vitamin C, therapeutic implications in the patient with serious burns / Vitamina C, implicações terapêuticas no paciente com queimaduras graves

Resumen: La atención a pacientes con quemaduras extensas es compleja, la quemadura condiciona efectos en el sitio de la lesión y a nivel sistémico. A nivel de la microcirculación se presenta respuesta de mediadores químicos inflamatorios y excesiva producción de especies reactivas de oxígeno y nitrógeno, además condiciona disminución de la capacidad antioxidante de vitamina C, por lo que se altera el balance fisiológico de óxido-reducción, dando paso al estado de estrés oxidativo, esto trae como consecuencia un incremento en la inflamación, disfunción endotelial e incremento de la permeabilidad capilar. Uno de los objetivos de la reanimación del paciente quemado es restaurar el volumen intravascular generado por el estado de choque, en el cual se implementan estrategias como el uso de cristaloides, coloides, plasma, terapias dialíticas, uso limitado de opioides y la administración de vitamina C. El objetivo de este trabajo es dar a conocer a la comunidad médica las características físicas y químicas, los mecanismos moleculares de la vitamina C en los que se encuentra implicada en condiciones de quemaduras graves, con la finalidad de la implementación durante la fase de reanimación del quemado.

Abstract: The care of patients with extensive burns is complex, the burn conditions effects at the site of the injury and at the systemic level. At the microcirculation level, there is a response of inflammatory chemical mediators and excessive production of reactive oxygen and nitrogen species, which also causes a decrease in the antioxidant capacity of vitamin C, which is why the physiological balance of oxide-reduction is altered, giving way to the state of oxidative stress, this results in an increase in inflammation, endothelial dysfunction and an increase in capillary permeability. One of the objectives of the resuscitation of the burned patient is to restore the intravascular volume generated by the state of shock, in which strategies such as the use of crystalloids, colloids, plasma, dialysis therapies, limited use of opioids and the administration of vitamins are implemented C. The objective of this work is to make known to the medical community, the physical and chemical characteristics, the molecular mechanisms of vitamin C in which it is involved in severe burn conditions, with the purpose of implementation during the resuscitation phase of burn.

Resumo: O atendimento a pacientes com queimaduras extensas é complexo, a queimadura condiciona efeitos no local da lesão e em nível sistêmico. Ao nível da microcirculação, há uma resposta de mediadores químicos inflamatórios e produção excessiva de espécies reativas de oxigénio e nitrogênio, condiciona também uma diminuição da capacidade antioxidante da vitamina C, que altera o equilíbrio fisiológico de oxidação-redução, dando lugar a o estado de estresse oxidativo, isso resulta em aumento da inflamação, disfunção endotelial e aumento da permeabilidade capilar. Um dos objetivos da ressuscitação do paciente queimado é restaurar o volume intravascular gerado pelo estado de choque, no qual se implementam estratégias como o uso de cristalóides, colóides, plasma, terapias dialíticas, uso limitado de opióides e administração de vitamina C. O objetivo deste trabalho é dar a conhecer à comunidade médica as características físicas e químicas, os mecanismos moleculares da vitamina C em que está envolvida em condições de queimaduras graves, com vista à sua aplicação durante a fase de reanimação do paciente queimado.

Evaluation of DENV-Induced Endothelial Cell Permeability by Measurements of Transendothelial Electrical Resistance (TEER) and Extravasation of Proteins and Virus.

This chapter will discuss reliable and relatively easy and fast strategies to evaluate the integrity of endothelial cell monolayers when infected by dengue virus (DENV). Human brain microvascular endothelial cells (HBMEC) were exploited here as general model of vessel wall core, but it may also be used as an in vitro simplified model of blood brain barrier (BBB). The integrity of endothelial cells monolayer can be inferred using a transwell culture system by: (1) measuring transendothelial electrical resistance (TEER) using a Voltohmmeter; (2) analyzing the monolayer permeability to fluorescent-conjugated proteins and fluorimetric assay; (3) investigating virus extravasation by quantitative RT-PCR and plaque conventional assay. The rational to use those strategies is that vascular alterations are often observed during dengue infection, being associated to disease severity. The vasculature core consists of a barrier of endothelial cells, which are tightly adhered by the expression of adhesion molecules and tight junctions. This structure must be preserved in order to control the flux of cells and metabolites from the circulation to the tissues and to maintain vascular homeostasis. Therefore, experimental assays that allow evaluation of endothelial integrity can be useful platforms to further understand disease pathogenesis and screen pharmaceutical interventions to control vascular disturbance.

Interleukin-8 Secreted by Glioblastoma Cells Induces Microvascular Hyperpermeability Through NO Signaling Involving S-Nitrosylation of VE-Cadherin and p120 in Endothelial Cells.

Glioblastoma is a highly aggressive brain tumor, characterized by the formation of dysfunctional blood vessels and a permeable endothelial barrier. S-nitrosylation, a post-translational modification, has been identified as a regulator of endothelial function. In this work we explored whether S-nitrosylation induced by glioblastoma tumors regulates the endothelial function. As proof of concept, we observed that S-nitrosylation is present in the tumoral microenvironment of glioblastoma in two different animal models. Subsequently, we measured S nitrosylation and microvascular permeability in EAhy296 endothelial cells and in cremaster muscle. In vitro, conditioned medium from the human glioblastoma cell line U87 activates endothelial nitric oxide synthase, causes VE-cadherin- S-nitrosylation and induces hyperpermeability. Blocking Interleukin-8 (IL-8) in the conditioned medium inhibited S-nitrosylation of VE-cadherin and hyperpermeability. Recombinant IL-8 increased endothelial permeability by activating eNOS, S-nitrosylation of VE-cadherin and p120, internalization of VE-cadherin and disassembly of adherens junctions. In vivo, IL-8 induced S-nitrosylation of VE-cadherin and p120 and conditioned medium from U87 cells caused hyperpermeability in the mouse cremaster muscle. We conclude that eNOS signaling induced by glioma cells-secreted IL-8 regulates endothelial barrier function in the context of glioblastoma involving S-nitrosylation of VE-cadherin and p120. Our results suggest that inhibiting S-nitrosylation may be an effective way to control and/or block damage to the endothelial barrier and prevent cancer progression.

Role of Monocytes in the Pathogenesis of Dengue.

Diseases caused by dengue virus (DENV) are a major public health problem worldwide, considered one of the infections with more prevalence in tropical and subtropical zones of the world. Despite the intense research in the pathogenesis of DENV, this feature is not well understood. One of the main target cells for DENV infection is monocytes; these phagocytes can play a dual role, since they are essential to control viremia, but they also participate in the induction of tissue damage during DENV infection. Monocytes produce different pro-inflammatory cytokines and chemokines in response to infection, and also mediate endothelial damage. In peripheral blood, monocytes can be divided into three different subpopulations, namely classical, intermediate and non-classical, which differ in frequency, cytokine production, among others. Studies in the last years suggest that non-classical monocytes have higher affinity for microvasculature endothelium compared to other type of monocytes, which implies that they could be more involved in the increase of endothelial permeability observed during DENV infection. This review provides a general view of the role of monocytes and their subpopulations in DENV pathogenesis and its effect in viral replication. Finally, the potential contribution of these phagocytes in the alterations of endothelial permeability is discussed.

ATL-1, a synthetic analog of lipoxin, modulates endothelial permeability and interaction with tumor cells through a VEGF-dependent mechanism.

Lipoxins (LX) and 15-epi-LX are lipids with a potent inhibitory effect on angiogenesis, in different models in vivo and in vitro. ATL-1, a synthetic analog of 15-epi-LXA4, inhibits various actions stimulated by vascular endothelial growth factor (VEGF). However, LX actions on endothelial cells (EC) in tumor-related contexts are still unknown. Here, we investigated the modulation of EC by ATL-1, in a model that mimics tumor extravasation. We observed that the analog inhibited endothelial permeability induced by VEGF, through the stabilization of VE-cadherin/ß-catenin-dependent adherens junctions. We tested the ability of MV3 cells, a highly metastatic melanoma cell line, to transmigrate across unchallenged EC monolayers for 18 h, as compared to NGM normal melanocytes. ATL-1 was able to inhibit only melanoma extravasation. MV3 cells secrete large amounts of VEGF and we observed that ATL-1 per se did not alter this ability. Melanoma cells skills to crossing endothelial monolayers were due to the steady accumulation of tumor-derived VEGF. When endothelial cells were challenged with exogenous VEGF, added at levels comparable to those secreted by MV3 cells over 18 h, and a short-term (4h) transendothelial migration assay was performed, both melanoma and melanocyte cells were able to extravasate, and ATL-1 was able to block the passage of both cells. These results indicate that ATL-1 has a potent inhibitory effect on the permeability induced by VEGF, and that this pharmacological effect could be used to block tumor extravasation across endothelial barriers, with a possible prospect of reducing the haematogenic spread of cancer cells.