Estudio de la interacción funcional de la tetraspanina CD9 con la integrina LFA-1 en la superficie leucocitaria

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología. Fecha de lectura: 18-01-2016La tetraspanina CD9 interacciona con distintos miembros de las subfamilias β1, β3 y β4 de las integrinas. A través de esta interacción CD9 regula la adhesión, la migración y la señalización celular. Sin embargo, hasta este momento no se había descrito ninguna interacción de esta tetraspanina con miembros de la subfamilia β2. Los resultados de colocalización, hibridación por proximidad y co-inmunoprecipitación, que se presentan en esta tesis, muestran que CD9 se asocia con la integrina de la subfamilia β2 LFA-1 en la superficie de distintos tipos de leucocitos (linfocitos T, B y células monocíticas). Esta interacción es resistente a condiciones de solubilización fuertes, lo que apunta, junto con los resultados de los ensayos de pull-down y entrecruzamiento químico, a una interacción directa entre las dos moléculas que se produce a través del dominio extracelular grande de CD9. Además, CD9 regula funcionalmente a la integrina LFA-1, puesto que la presencia de esta tetraspanina inhibe la adhesión de LFA-1 a su ligando ICAM-1 y la citotoxicidad celular dependiente de esta unión. La regulación de CD9 sobre LFA-1 no implica cambios en la afinidad de la integrina, pero sí cambios en su avidez que se evidencian por la alteración causada por CD9 en el patrón de distribución de LFA-1 en la superficie celular. Curiosamente, la regulación que ejerce CD9 sobre la adhesión de integrinas de la subfamilia β1 es inversa a la observada para la integrina LFA-1.The tetraspanin CD9 interacts with different members of the β1, β3 and β4 subfamilies of integrins and through these interactions regulates cell adhesion, migration and signalling. However, the interaction of CD9 with any member of the β2 subfamily of integrins had not been reported so far. The confocal microscopy co-localization, in situ Proximity Ligation Assays and co-immunoprecipitation results that are presented here show that CD9 associates with the β2 integrin LFA-1 on the surface of different types of leukocytes (including T, B and monocytic cells). This association is resistant to stringent solubilisation conditions which, together with data from chemical crosslinking and pull-down experiments, suggests a primary/direct type of interaction mediated by the large extracellular loop (LEL) of the tetraspanin. CD9 exerts inhibitory effects on the adhesive function of LFA-1 and on LFA-1-dependent leukocyte cytotoxic activity. The mechanism responsible for the negative regulation exerted by CD9 on LFA-1 adhesion does not involve changes in the affinity state of this integrin but seems to be related to alterations in its state of aggregation. Interestingly, CD9 regulates in an inverse manner the adhesive properties of the β1 and β2 integrins expressed on the same leukocytes

Enhancing Regulatory T Cells to Treat Inflammatory and Autoimmune Diseases

Regulatory T cells (Tregs) control immune responses and are essential to maintain immune homeostasis and self-tolerance. Hence, it is no coincidence that autoimmune and chronic inflammatory disorders are associated with defects in Tregs. These diseases have currently no cure and are treated with palliative drugs such as immunosuppressant and immunomodulatory agents. Thereby, there is a great interest in developing medical interventions against these diseases based on enhancing Treg cell function and numbers. Here, we give an overview of Treg cell ontogeny and function, paying particular attention to mucosal Tregs. We review some notable approaches to enhance immunomodulation by Tregs with therapeutic purposes including adoptive Treg cell transfer therapy and discuss relevant clinical trials for inflammatory bowel disease. We next introduce ways to expand mucosal Tregs in vivo using microbiota and dietary products that have been the focus of clinical trials in various autoimmune and chronic-inflammatory diseases

Enhancing Regulatory T Cells to Treat Inflammatory and Autoimmune Diseases

Regulatory T cells (Tregs) control immune responses and are essential to maintain immune homeostasis and self-tolerance. Hence, it is no coincidence that autoimmune and chronic inflammatory disorders are associated with defects in Tregs. These diseases have currently no cure and are treated with palliative drugs such as immunosuppressant and immunomodulatory agents. Thereby, there is a great interest in developing medical interventions against these diseases based on enhancing Treg cell function and numbers. Here, we give an overview of Treg cell ontogeny and function, paying particular attention to mucosal Tregs. We review some notable approaches to enhance immunomodulation by Tregs with therapeutic purposes including adoptive Treg cell transfer therapy and discuss relevant clinical trials for inflammatory bowel disease. We next introduce ways to expand mucosal Tregs in vivo using microbiota and dietary products that have been the focus of clinical trials in various autoimmune and chronic-inflammatory diseases.Comunidad Autonoma de MadridDepto. de Inmunología, Oftalmología y ORLFac. de MedicinaTRUEpu