T-cell trans-synaptic vesicles are distinct and carry greater effector content than constitutive extracellular vesicles

The immunological synapse is a molecular hub that facilitates the delivery of three activation signals, namely antigen, costimulation/corepression and cytokines, from antigen-presenting cells (APC) to T cells. T cells release a fourth class of signaling entities, trans-synaptic vesicles (tSV), to mediate bidirectional communication. Here we present bead-supported lipid bilayers (BSLB) as versatile synthetic APCs to capture, characterize and advance the understanding of tSV biogenesis. Specifically, the integration of juxtacrine signals, such as CD40 and antigen, results in the adaptive tailoring and release of tSV, which differ in size, yields and immune receptor cargo compared with steadily released extracellular vesicles (EVs). Focusing on CD40L+ tSV as model effectors, we show that PD-L1 trans-presentation together with TSG101, ADAM10 and CD81 are key in determining CD40L vesicular release. Lastly, we find greater RNA-binding protein and microRNA content in tSV compared with EVs, supporting the specialized role of tSV as intercellular messenger

Extracellular Vesicle-Mediated Immune Regulation of Tissue Remodeling and Angiogenesis After Myocardial Infarction

Myocardial ischemia-related disorders constitute a major health problem, being a leading cause of death in the world. Upon ischemia, tissue remodeling processes come into play, comprising a series of inter-dependent stages, including inflammation, cell proliferation and repair. Neovessel formation during late phases of remodeling provides oxygen supply, together with cellular and soluble components necessary for an efficient myocardial reconstruction. Immune system plays a central role in processes aimed at repairing ischemic myocardium, mainly in inflammatory and angiogenesis phases. In addition to cellular components and soluble mediators as chemokines and cytokines, the immune system acts in a paracrine fashion through small extracellular vesicles (EVs) release. These vesicular structures participate in multiple biological processes, and transmit information through bioactive cargoes from one cell to another. Cell therapy has been employed in an attempt to improve the outcome of these patients, through the promotion of tissue regeneration and angiogenesis. However, clinical trials have shown variable results, which put into question the actual applicability of cell-based therapies. Paracrine factors secreted by engrafted cells partially mediate tissue repair, and this knowledge has led to the hypothesis that small EVs may become a useful tool for cell-free myocardial infarction therapy. Current small EVs engineering strategies allow delivery of specific content to selected cell types, thus revealing the singular properties of these vesicles for myocardial ischemia treatment

Control of Immunoregulatory Molecules by miRNAs in T Cell Activation

MiRNA targeting of key immunoregulatory molecules fine-tunes the immune response. This mechanism boosts or dampens immune functions to preserve homeostasis while supporting the full development of effector functions. MiRNA expression changes during T cell activation, highlighting that their function is constrained by a specific spatiotemporal frame related to the signals that induce T cell-based effector functions. Here, we update the state of the art regarding the miRNAs that are differentially expressed during T cell stimulation. We also revisit the existing data on miRNA function in T cell activation, with a special focus on the modulation of the most relevant immunoregulatory molecules

Thinking small: zinc-sensing by the gut epithelium.

pre-print341 K

Señalización derivada de la interacción leucocito-endotelio durante la inflamación

Leukocyte trafficking throughout the vasculature is a crucial step for the development of innate and adaptive immunity (1). The coordinate function of adhesion receptors, cytoskeleton and signaling molecules in both cellular types is fundamental during leukocyte extravasation. Hence, the correct integration of “outside-in” and “inside-out” signals in leukocytes and endothelium during each stage of the process is critical to allow the completion of the so-called “multi-step paradigm” (leukocyte tethering and rolling involving selectins and their ligands, followed by leukocyte firm adhesion and crawling mediated by integrins and their endothelial counter-receptors and the subsequent diapedesis also mediated by junctional proteins) (2, 3). This review focuses on the signaling pathways triggered during the extravasation that allow leukocytes to efficiently migrate towards the inflammatory foci to exert their effector functions.Key Words: Inflammation, Leukocyte adhesion, Transendothelial migration, Adhesion receptor signaling.El tráfico leucocitario a través de la vasculatura es un paso crucial para el desarrollo de la inmunidad innata y adaptativa. El funcionamiento coordinado de los receptores de adhesión, el citoesqueleto y las moléculas señalizadoras tanto en el leucocito como en el endotelio es fundamental durante el proceso de extravasación. Así, la correcta integración de las señales del exterior hacia el interior y del interior hacia el exterior en ambos tipos celulares durante cada etapa del proceso es crítica para la consecución del llamado “paradigma multi-secuencial” (el rodamiento de los leucocitos en el que están implicadas las selectinas y sus ligandos, seguido de la adhesión firme mediada por las integrinas leucocitarias y sus contra-receptores endoteliales, así como el subsiguiente paso de diapedesis en el que también están implicadas moléculas típicas de uniones intercelulares). Esta revisión se centra en las vías de señalización que se desencadenan durante la extravasación que permiten a los leucocitos migrar de manera eficiente hacia los focos inflamatorios donde ejercen sus funciones efectoras. Palabras clave: Inflamación, Adhesión leucocitaria, Migración transendotelial, Señalización mediada por receptores de adhesión

Extracellular Vesicle-Mediated Immune Regulation of Tissue Remodeling and Angiogenesis After Myocardial Infarction

Myocardial ischemia-related disorders constitute a major health problem, being a leading cause of death in the world. Upon ischemia, tissue remodeling processes come into play, comprising a series of inter-dependent stages, including inflammation, cell proliferation and repair. Neovessel formation during late phases of remodeling provides oxygen supply, together with cellular and soluble components necessary for an efficient myocardial reconstruction. Immune system plays a central role in processes aimed at repairing ischemic myocardium, mainly in inflammatory and angiogenesis phases. In addition to cellular components and soluble mediators as chemokines and cytokines, the immune system acts in a paracrine fashion through small extracellular vesicles (EVs) release. These vesicular structures participate in multiple biological processes, and transmit information through bioactive cargoes from one cell to another. Cell therapy has been employed in an attempt to improve the outcome of these patients, through the promotion of tissue regeneration and angiogenesis. However, clinical trials have shown variable results, which put into question the actual applicability of cell-based therapies. Paracrine factors secreted by engrafted cells partially mediate tissue repair, and this knowledge has led to the hypothesis that small EVs may become a useful tool for cell-free myocardial infarction therapy. Current small EVs engineering strategies allow delivery of specific content to selected cell types, thus revealing the singular properties of these vesicles for myocardial ischemia treatment.This work was supported by grants to AA-S (FIS PI15/01491) and to FS-M (grants SAF2014-55579-R and SAF2017-82886-R to FS-M), BIOIMID PIE13/041 and CIBER CARDIOVASCULAR from the Instituto de Salud Carlos III (Fondo de Investigación Sanitaria del Instituto de Salud Carlos III with co-funding from the Fondo Europeo de Desarrollo Regional; FEDER), Programa de Actividades en Biomedicina de la Comunidad de Madrid-B2017/BMD-3671-INFLAMUNE to FS-M, and ERC2011-AdG294340-GENTRIS to FS-M, and Fundació La Marató TV3 (20152330 31). The Centro Nacional de Investigaciones Cardiovasculares (CNIC) is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) and the ProCNIC Foundation and is a Severo Ochoa Center of Excellence (MINECO award SEV-2015-0505).S

Avizores del Sistema Inmune, Guardianes del Organismo

The immune response begins when our body comes in contact with foreign substances (antigens), for example pathogens such as bacteria or viruses. The cells involved in the initiation of the response (dendritic cells and tissue macrophages) are strategically placed at sites of antigen concentration where they are locally activated. Recognition of pathogens by these cells is mediated by a plethora of receptors from different molecular families, such as Toll-­‐like (TLRs), NLRs, RIG-­‐like and C-­‐lectin receptors. These cells migrate to lymphoid organs such as lymph nodes,where they alert and activate other cells initiating a cascade of processes to eliminate the pathogen. These processes include the generation of “memory lymphocytes”, which perpetuate the memory of the antigen initially recognized and wait for a recurrence of the attack. These memory cells are able to act much more effectively, preventing possible re-­‐infection. The phenomenon of immunological memory is the base of the processes of immunization and vaccines.La respuesta inmune comienza cuando nuestro cuerpo entra en contacto con sustancias extrañas (antígenos), por ejemplo patógenos tales como bacterias o virus. Las células implicadas en la iniciación de la respuesta (células dendríticas y macrófagos tisulares) están situadas estratégicamente en los sitios de concentración de antígeno, donde son activadas localmente. El reconocimiento de los patógenos es mediado por un conjunto de receptores de diferentes familias de moléculas tales como los de tipo Toll (TLRs), tipo Nod (NLRs), tipo RIG o lectinas tipo C. Estas células emigran a los órganos linfoides, como los ganglios linfáticos, donde alertan y activan a otras células que inician una reacción en cadena para eliminar el patógeno. Estos procesos incluyen el “recuerdo” del antígeno a través de la generación de linfocitos de memoria, que perpetúan el recuerdo del antígeno que los activó inicialmente y esperan una recurrencia del ataque. Estas células de memoria pueden actuar mucho más eficazmente, previniendo la posible re-­‐infección. El fenómeno de la memoria inmunológica es la base de los procesos de inmunización y de las vacunas

Adhesive Interactions Delineate the Topography of the Immune Synapse

T cells form adhesive contacts with antigen-presenting cells (APCs) as part of the normal surveillance process that occurs in lymph nodes and other tissues. Most of these adhesive interactions are formed by integrins that interact with ligands expressed on the surface of the APC. The interactive strength of integrins depends on their degree of membrane proximity as well as intracellular signals that dictate the conformation of the integrin. Integrins appear in different conformations that endow them with different affinities for their ligand(s). Integrin conformation and thus adhesive strength between the T cell and the APC is tuned by intracellular signals that are turned on by ligation of the T cell receptor (TCR) and chemokine receptors. During the different stages of the process, integrins, the TCR and chemokine receptors may be interconnected by the actin cytoskeleton underneath the plasma membrane, forming a chemical and physical network that facilitates the spatiotemporal dynamics, positioning, and function of these receptors and supports cell-cell adhesion during T cell activation, allowing it to perform its effector function

MicroRNAs in T Cell-Immunotherapy.

MicroRNAs (miRNAs) act as master regulators of gene expression in homeostasis and disease. Despite the rapidly growing body of evidence on the theranostic potential of restoring miRNA levels in pre-clinical models, the translation into clinics remains limited. Here, we review the current knowledge of miRNAs as T-cell targeting immunotherapeutic tools, and we offer an overview of the recent advances in miRNA delivery strategies, clinical trials and future perspectives in RNA interference technologies.This manuscript was funded by grants AEI/10.13039/501100011033, PID-2020-120412RBI100 and PDC2021-121797-I00 (F.S.-M.) from the Spanish Ministry of Economy and Competitiveness; CAM (S2017/BMD-3671-INFLAMUNE-CM) from the Comunidad de Madrid (F.S.-M.), CIBERCV (CB16/11/00272) and BIOIMID PIE13/041 from the Instituto de Salud Carlos “la Caixa” Foundation under the project code HR17-00016. The current research is supported by AECC-Coordinated Grant 2022 (PRYCO223002PEIN). The CNIC is supported by the Ministerio de Ciencia, Innovacion y Universidades and the Pro-CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015- 0505). IMDEA Nanociencia acknowledges support from the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (MINECO, CEX2020-001039-S). S.G.D. is supported by a grant from the Spanish Ministry of Universities.S

The swing of lipids at peroxisomes and endolysosomes in t cell activation

The immune synapse (IS) is a well-known intercellular communication platform, organized at the interphase between the antigen presenting cell (APC) and the T cell. After T cell receptor (TCR) stimulation, signaling from plasma membrane proteins and lipids is amplified by molecules and downstream pathways for full synapse formation and maintenance. This secondary signaling event relies on intracellular reorganization at the IS, involving the cytoskeleton and components of the secretory/recycling machinery, such as the Golgi apparatus and the endolysosomal system (ELS). T cell activation triggers a metabolic reprogramming that involves the synthesis of lipids, which act as signaling mediators, and an increase of mitochondrial activity. Then, this mitochondrial activity results in elevated reactive oxygen species (ROS) production that may lead to cytotoxicity. The regulation of ROS levels requires the concerted action of mitochondria and peroxisomes. In this review, we analyze this reprogramming and the signaling implications of endolysosomal, mitochondrial, peroxisomal, and lipidic systems in T cell activation.This review was funded by grant SAF2017-82886-R from the Spanish Ministry of Economy and Competitiveness (MINECO), grant S2017/BMD-3671-INFLAMUNE-CM from the Comunidad de Madrid, a grant from the Ramón Areces Foundation “Ciencias de la Vida y la Salud” (CIVP19A5941 XIX Concurso-2018) and a grant from Ayudas Fundación BBVA a Equipos de Investigación Científica (BIOMEDICINA-2018), the Fundació Marató TV3 (grant 122/C/2015) and “La Caixa” Banking Foundation (HR17-00016). BIOIMID (PIE13/041) from Instituto de Salud Carlos III, CIBER Cardiovascular (CB16/11/00272, Fondo de Investigación Sanitaria del Instituto de Salud Carlos III and co-funding by Fondo Europeo de Desarrollo Regional FEDER). SGD and ARG are funded by fellowship FPU and FPI programs, from Ministry of Science and Universities, respectively