Nigrostriatal degeneration determines dynamics of glial inflammatory and phagocytic activity.

Glial cells are key players in the initiation of innate immunity in neurodegeneration. Upon damage, they switch their basal activation state and acquire new functions in a context and time-dependent manner. Since modulation of neuroinflammation is becoming an interesting approach for the treatment of neurodegenerative diseases, it is crucial to understand the specific contribution of these cells to the inflammatory reaction and to select experimental models that recapitulate what occurs in the human disease. Previously, we have characterized a region-specific activation pattern of CD11b+ cells and astrocytes in the α-synuclein overexpression mouse model of Parkinson´s disease (PD). In this study we hypothesized that the time and the intensity of dopaminergic neuronal death would promote different glial activation states. Dopaminergic degeneration was induced with two administration regimens of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), subacute (sMPTP) and chronic (cMPTP). Our results show that in the sMPTP mouse model, the pro-inflammatory phenotype of striatal CD11b+ cells was counteracted by an anti-inflammatory astrocytic profile. In the midbrain the roles were inverted, CD11b+ cells exhibited an anti-inflammatory profile and astrocytes were pro-inflammatory. The overall response generated resulted in decreased CD4 T cell infiltration in both regions. Chronic MPTP exposure resulted in a mild and prolonged neuronal degeneration that generated a pro-inflammatory response and increased CD4 T cell infiltration in both regions. At the onset of the neurodegenerative process, microglia and astrocytes cooperated in the removal of dopaminergic terminals. With time, only microglia maintained the phagocytic activity. In the ventral midbrain, astrocytes were the main phagocytic mediators at early stages of degeneration while microglia were the major phagocytic cells in the chronic state. In this scenario, we questioned which activation pattern recapitulates better the features of glial activation in PD. Glial activation in the cMPTP mouse model reflects many pathways of their corresponding counterparts in the human brain with advanced PD. Altogether, our results point toward a context-dependent cooperativity of microglia/myeloid cells and astrocytes in response to neuronal damage and the relevance of selecting the right experimental models for the study of neuroinflammation.

Relevance of mutation-derived neoantigens and non-classical antigens for anticancer therapies.

Efficacy of cancer immunotherapies relies on correct recognition of tumor antigens by lymphocytes, eliciting thus functional responses capable of eliminating tumor cells. Therefore, important efforts have been carried out in antigen identification, with the aim of understanding mechanisms of response to immunotherapy and to design safer and more efficient strategies. In addition to classical tumor-associated antigens identified during the last decades, implementation of next-generation sequencing methodologies is enabling the identification of neoantigens (neoAgs) arising from mutations, leading to the development of new neoAg-directed therapies. Moreover, there are numerous non-classical tumor antigens originated from other sources and identified by new methodologies. Here, we review the relevance of neoAgs in different immunotherapies and the results obtained by applying neoAg-based strategies. In addition, the different types of non-classical tumor antigens and the best approaches for their identification are described. This will help to increase the spectrum of targetable molecules useful in cancer immunotherapies.

Tethered IL15-IL15Rα augments antitumor activity of CD19 CAR-T cells but displays long-term toxicity in an immunocompetent lymphoma mouse model.

BACKGROUND: Adoptive cell therapy using genetically modified T cells to express chimeric antigen receptors (CAR-T) has shown encouraging results, particularly in certain blood cancers. Nevertheless, over 40% of B cell malignancy patients experience a relapse after CAR-T therapy, likely due to inadequate persistence of the modified T cells in the body. IL15, known for its pro-survival and proliferative properties, has been suggested for incorporation into the fourth generation of CAR-T cells to enhance their persistence. However, the potential systemic toxicity associated with this cytokine warrants further evaluation. METHODS: We analyzed the persistence, antitumor efficacy and potential toxicity of anti-mouse CD19 CAR-T cells which express a membrane-bound IL15-IL15Rα chimeric protein (CD19/mbIL15q CAR-T), in BALB/c mice challenged with A20 tumor cells as well as in NSG mice. RESULTS: Conventional CD19 CAR-T cells showed low persistence and poor efficacy in BALB/c mice treated with mild lymphodepletion regimens (total body irradiation (TBI) of 1 Gy). CD19/mbIL15q CAR-T exhibits prolonged persistence and enhanced in vivo efficacy, effectively eliminating established A20 B cell lymphoma. However, this CD19/mbIL15q CAR-T displays important long-term toxicities, with marked splenomegaly, weight loss, transaminase elevations, and significant inflammatory findings in some tissues. Mice survival is highly compromised after CD19/mbIL15q CAR-T cell transfer, particularly if a high TBI regimen is applied before CAR-T cell transfer. CONCLUSION: Tethered IL15-IL15Rα augments the antitumor activity of CD19 CAR-T cells but displays long-term toxicity in immunocompetent mice. Inducible systems to regulate IL15-IL15Rα expression could be considered to control this toxicity.

Interferon producing killer dendritic cells (IKDC): a matter of controversy

La división de tareas entre las células del sistema inmunitario es undenominador común en la organización de las diferentes respuestas quelleva a cabo. Como excepción a este paradigma, una subpoblación leucocitaria de ratones parece estar equipada para matar células transformadas einfectadas con virus y, a la vez, con la capacidad de procesamiento antigé-nico y presentación a linfocitos T. Estas funciones se adscriben clásicamente de forma separada a linfocitos NK y a células dendríticas. Las IKDC (“Interferon-producing killer dendritic cells”) fueron definidas en ratón como células que expresan en su superficie CD11c con menor intensidad que las células dendríticas convencionales mientras que coexpresan B220, NK1.1, CD49b(VLA-2) y MHC de Clase II. La ausencia de CD3, CD19 y Gr1 (Ly49C) caracteriza también esta subpoblación cuando se estudia mediante citometría de (..) (AU)

Division of labour among cells of the immune system is a prevailingtheme in the orchestration of immune responses. Contrary to this paradigm, a particular leukocyte population in the mouse seems to be equipped with the ability to kill transformed and virally infected cells and withthe capability to mediate antigen processing and presentation to T cells.Those two functions are classically ascribed separately to Natural Killer(NK) cells and Dendritic cells (DC). IKDC (interferon-producing killerdendritic cell) were defined in mice as cells expressing CD11c, althoughto a lesser extent than conventional DCs (cDCs), while coexpressing B220,NK1.1, CD49b (VLA-2) and MHC Class II molecules. Absence of CD3,CD19 and Gr1(Ly49c) expression also featured this minor subset uponmulticolour FACS characterization. These cells kill a variety tumor celllines in a TRAIL-dependent fashion. Furthermore, IKDC produce high (..) (AU)

Polly Matzinger’s “danger model” finds its predicted danger-denoting self moieties

La teoría de la “alarma” (danger) es un conjunto de postulados formalmente propuestos por Polly Matzinger hace quince años. Como teoría surgió para explicar la aparición de respuesta inmunitaria en ausencia de infección. Ha sido una teoría provocadora al proponer que el sistema inmunitario no ha evolucionado para discernir entre lo propio y lo extraño, sino para responder frente a aquello que está causando daño tisular. La propuesta del modelo coincidió en el tiempo con el descubrimiento de la potenciación de la respuesta inmunitaria por patrones moleculares presentes en microorganismos. Charles Janeway y sus colaboradores propusieron que la situación de infección se detecta mediante receptores innatos para patrones estructurales de biomoléculas microbiológicas que están ausentes en organismos superiores sanos. Se descubrió que estos agentes estimulan a las células presentadoras de antígeno para proporcionar a los linfocitos T señales coestimuladoras complementarias para las que reciben al reconocer el antígeno. La coestimulación sería crítica para que la respuesta inmunitaria se ponga en marcha y se sostenga en el tiempo. La teoría del “danger” postula la existencia de moléculas endógenas liberadas o modificadas por la destrucción o daño tisular que pueden hacer sonar la alarma en condiciones de asepsia. Hay varios hallazgos experimentales recientes que apuntan que una serie demoléculas cumplen estas condiciones: La proteína nuclear HMGB-1, el ácidoúrico, el interferon-α, el ATP extracelular, chaperonas de la familia de proteínas de stress térmico, dominios alternativos de la fibronectina y ácidos nucleicos endógenos. Algunos de estos agentes son detectados por los mismos receptores tipo Toll que detectan los patrones de biomoléculas de microbios. La identificación de estos mecanismos moleculares presta apoyo experimental a la teoría del “danger”, y sus implicaciones tienen extraordinaria importancia en inmunología tumoral y en transplante (AU)

The “danger theory” is a set of postulates formally proposed by Polly Matzinger fifteen years ago. As a theory, it explains how it is possible that immune responses take place without infection. It provokingly proposed that the immune systems have not evolved for self/non-self discrimination, but to respond against what is causing tissue damage. The proposal of the “danger model” coincided in time with the discovery of the immune potentiating effects of microbial molecular patterns. Charles Janewayet al. proposed that infection would be detected by innate receptors for microbiological biomolecules that are either absent or different in mammals. These agents were found to stimulate antigen presenting cells in such a way that would provide T lymphocytes with appropriate costimulatory molecules that critically complement the signals raised by antigen recognition. This was considered absolutely critical to ignite and sustain immune responses. The danger theory predicted the existence of endogenous molecules released or modified by danger that would act in a similar fashion to the microbial molecular patterns on dendritic cell costimulatory functions. Recent evidence points to various molecules capable of sounding the alarm in aseptic conditions. These include: the nuclear protein HBGM-1, uric acid, Interferon-α, chaperones of the heat shockprotein family, alternatively spliced domains of fibronectin, and self nucleicacids. Some of these agents act through the same Toll like receptors involved in microbial pattern recognition. Identification of these mechanisms provides molecular support for the danger theory and has an extraordinary importance for tumor and transplantation immunology (AU)