Dendritic cell ICAM-1 strengthens synapses with CD8 T cells but is not required for their early differentiation

Toxoplasma GRA15 expression on dendritic cells inhibits B cell differentiation and antibody production

One of the dense granule proteins named GRA15 in Toxoplasma gondii (T. gondii), is known to support an innate immune response in host through activation of NF-κB. However, little is known about advantages of GRA15 for parasites. By examining the role of GRA15 in the host-parasite interactions, it was clarified that GRA15 in T. gondii suppressed acquired immune responses in host. Wild-type parasite infection to C57BL/6 mice resulted in lower titers of T. gondii antibody and lower plasma cell counts compared to Δgra15 T. gondii. To identify host cells in which GRA15 acts to suppress antibody production, we generated conditional knock-in mice that express GRA15 in specific cell lineages. Anti-T. gondii antibodies were not reduced in macrophages of conditional knock-in mice after infection with Δgra15 T. gondii, while the production of T. gondii antibody was suppressed in dendritic cells of the conditional knock-in mice (CD11c-Cre/GRA15cKI). In the CD11c-Cre/GRA15cKI immunized with ovalbumin (OVA), the titers of anti-OVA antibody were reduced compared to control mice. Furthermore, the number of OVA antigen-specific T cells was also decreased in CD11c-Cre/GRA15cKI. These data showed that GRA15 in dendritic cells suppressed T cell-mediated humoral immunity. These findings might implicate the pathological significance of GRA15 and facilitate Toxoplasma vaccines production.

Subverting Attachment to Prevent Attacking: Alteration of Effector Immune Cell Migration and Adhesion as a Key Mechanism of Tumor Immune Evasion

Cell adhesion regulates specific migratory patterns, location, communication with other cells, physical interactions with the extracellular matrix, and the establishment of effector programs. Proper immune control of cancer strongly depends on all these events occurring in a highly accurate spatiotemporal sequence. In response to cancer-associated inflammatory signals, effector immune cells navigating the bloodstream shift from their patrolling exploratory migration mode to establish adhesive interactions with vascular endothelial cells. This interaction enables them to extravasate through the blood vessel walls and access the cancer site. Further adhesive interactions within the tumor microenvironment (TME) are crucial for coordinating their distribution in situ and for mounting an effective anti-tumor immune response. In this review, we examine how alterations of adhesion cues in the tumor context favor tumor escape by affecting effector immune cell infiltration and trafficking within the TME. We discuss the mechanisms by which tumors directly modulate immune cell adhesion and migration patterns to affect anti-tumor immunity and favor tumor evasion. We also explore indirect immune escape mechanisms that involve modifications of TME characteristics, such as vascularization, immunogenicity, and structural topography. Finally, we highlight the significance of these aspects in designing more effective drug treatments and cellular immunotherapies.

ICAMs in Immunity, Intercellular Adhesion and Communication

Interactions among leukocytes and leukocytes with immune-associated auxiliary cells represent an essential feature of the immune response that requires the involvement of cell adhesion molecules (CAMs). In the immune system, CAMs include a wide range of members pertaining to different structural and functional families involved in cell development, activation, differentiation and migration. Among them, β2 integrins (LFA-1, Mac-1, p150,95 and αDβ2) are predominantly involved in homotypic and heterotypic leukocyte adhesion. β2 integrins bind to intercellular (I)CAMs, actin cytoskeleton-linked receptors belonging to immunoglobulin superfamily (IgSF)-CAMs expressed by leukocytes and vascular endothelial cells, enabling leukocyte activation and transendothelial migration. β2 integrins have long been viewed as the most important ICAMs partners, propagating intracellular signalling from β2 integrin-ICAM adhesion receptor interaction. In this review, we present previous evidence from pioneering studies and more recent findings supporting an important role for ICAMs in signal transduction. We also discuss the contribution of immune ICAMs (ICAM-1, -2, and -3) to reciprocal cell signalling and function in processes in which β2 integrins supposedly take the lead, paying particular attention to T cell activation, differentiation and migration.

The DC-T cell axis is an effective target for the treatment of non-small cell lung cancer

The dendritic cell (DC)-T cell axis is a bridge that connects innate and adaptive immunities. The initial immune response against tumors is mainly induced by mature antigen-presenting DCs. Enhancing the crosstalk between DCs and T cells may be an effective approach to improve the immune response to non-small cell lung cancer (NSCLC). In this article, a review was made of the interaction between DCs and T cells in the treatment of NSCLC and how this interaction affects the treatment outcome.