Protección del epitelio respiratorio frente a la infección y el daño celular por lípidos y proteínas del fluido alveolar
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2023
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21/10/2022
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Universidad Complutense de Madrid
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Abstract
El sistema respiratorio es el encargado de la obtención del oxígeno necesario para la respiración celular y de expulsar el dióxido de carbono producido como desecho en este proceso. El intercambio gaseoso tiene lugar en los alveolos, donde el oxígeno y el dióxido de carbono difunden entre el epitelio alveolar y los eritrocitos del torrente sanguíneo. Para realizar esta función, el epitelio alveolar es la mayor superficie del organismo expuesta al medio externo y está en contacto con una variedad de agentes extraños, como patógenos, partículas y otras sustancias tóxicas (1). Para hacer frente a estos potenciales agentes dañinos y al mismo tiempo mantener la homeostasis del tejido que permite el intercambio gaseoso, se requiere un sistema inmune eficaz, pero sin disparar una inflamación excesiva que genere daños en el tejido. El primer encargado de llevar a cabo estas funciones es el sistema inmune innato (2). En los alveolos, este sistema consta de un componente humoral: péptidos y proteínas antimicrobianas así como lípidos del fluido alveolar; y un componente celular: macrófagos alveolares, células dendríticas y células epiteliales (3).En el fluido alveolar se encuentra el surfactante pulmonar, que es un complejo lipoproteico que recubre el epitelio alveolar y es esencial para reducir la tensión superficial en la interfase aire-líquido, evitando el colapso alveolar y permitiendo el intercambio de gases. Además, el surfactante pulmonar es un componente integral del sistema inmune innato del pulmón, que ayuda a controlar la inflamación y a prevenir las infecciones microbianas (4,5). Estas dos funciones esenciales (disminución de la tensión superficial y defensa del huésped) dependen de la complejidad de sus componentes, haciendo que ambas funciones estén coordinadas para que los mecanismos de defensa no interfieran con las propiedades tensioactivas del surfactante (5)...
The respiratory system is needed to obtain the oxygen required for cellular metabolism and to expel the carbon dioxide produced as a waste in this process. The gas exchange takes place in the alveoli, where oxygen and carbon dioxide diffuse between the alveolar epithelium and erythrocytes of the bloodstream. To carry out this function, the alveolar epithelium is the largest surface of the body exposed to the external environment and it is in contact with a variety of agents, such as pathogens, particles and other toxic substances (1). To control these potential harmful agents while maintaining tissue homeostasis that allows gas exchange, an effective immune system is required. The immune system also may limit excessive inflammation that can lead to tissue damage. The innate immune system is in charge of controlling these functions (2). In the alveoli, this system consists of a humoral component: antimicrobial peptides and proteins as well as lipids from the alveolar fluid; and a cellular component: alveolar macrophages, dendritic cells, and epithelial cells (3).The alveolar fluid contains the pulmonary surfactant, which is a lipoprotein complex that covers the alveolar epithelium and is essential to reduce surface tensionat the air-liquid interface, preventing alveolar collapse and allowing gas exchange. In addition, pulmonary surfactant is an integral component of the lung's innate immune system, controlling inflammation and preventing microbial infections (4,5). These two essential functions (decreased surface tension and host defense) depend on the complexity of their components, coordinating both functions so that defense mechanisms do not interfere with tensioactive properties (5)...
The respiratory system is needed to obtain the oxygen required for cellular metabolism and to expel the carbon dioxide produced as a waste in this process. The gas exchange takes place in the alveoli, where oxygen and carbon dioxide diffuse between the alveolar epithelium and erythrocytes of the bloodstream. To carry out this function, the alveolar epithelium is the largest surface of the body exposed to the external environment and it is in contact with a variety of agents, such as pathogens, particles and other toxic substances (1). To control these potential harmful agents while maintaining tissue homeostasis that allows gas exchange, an effective immune system is required. The immune system also may limit excessive inflammation that can lead to tissue damage. The innate immune system is in charge of controlling these functions (2). In the alveoli, this system consists of a humoral component: antimicrobial peptides and proteins as well as lipids from the alveolar fluid; and a cellular component: alveolar macrophages, dendritic cells, and epithelial cells (3).The alveolar fluid contains the pulmonary surfactant, which is a lipoprotein complex that covers the alveolar epithelium and is essential to reduce surface tensionat the air-liquid interface, preventing alveolar collapse and allowing gas exchange. In addition, pulmonary surfactant is an integral component of the lung's innate immune system, controlling inflammation and preventing microbial infections (4,5). These two essential functions (decreased surface tension and host defense) depend on the complexity of their components, coordinating both functions so that defense mechanisms do not interfere with tensioactive properties (5)...
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Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, leída el 21-10-2022