Abraham, N. | Search bioRxiv

bioRxiv2023

Effect of homotypic vs. heterotypic interactions on the cellular uptake of extracellular vesicles

Extracellular vehicles (EVs) are an emerging class of drug carriers and are primarily reported to be internalized into recipient cells via a combination of endocytic routes such as clathrin-mediated, caveolae-mediated and macropinocytosis pathways. In this work, (1) we investigated potential effects of homotypic vs. heterotypic interactions by studying the cellular uptake of homologous EVs (EV donor cells and recipient cells of the same type) vs. heterologous EVs (EV donor cells and recipient cells of different types) and (2) determined the route of EV internalization into low pinocytic/hard-to-deliver cell models such as brain endothelial cells (BECs). We used BECs and macrophages as low-pinocytic and phagocytic cell models, respectively, to study the effect of homotypic vs. heterotypic interactions on EV uptake in the recipient cells. Homotypic interactions led to a greater extent of uptake into the recipient BECs compared to heterotypic interactions. However, we did not see a complete reduction in EV uptake into recipient BECs when endocytic pathways were blocked using pharmacological inhibitors. Our results suggest that EVs primarily use membrane fusion to enter low-pinocytic recipient BECs instead of relying on endocytosis. Lipophilic PKH67 dye-labeled EVs but not intravesicular esterase-activated calcein ester-labeled EVs severely reduced particle uptake into BECs while phagocytic macrophages internalized both types of EV-labeled particles to comparable extents. Our results also highlight the importance of carefully choosing labeling dye chemistry to study EV uptake, especially in the case of low pinocytic cells such as BECs. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=171 HEIGHT=200 SRC="FIGDIR/small/563628v2_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@d5cb50org.highwire.dtl.DTLVardef@172d1dorg.highwire.dtl.DTLVardef@192caf6org.highwire.dtl.DTLVardef@4b16ba_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2021

IL-7 is essential for accumulation of antigen-specific CD8 T cells and to generate clonotype-specific effector responses during airway influenza/A infection.

Airborne diseases are the leading cause of infectious disease-related deaths in the world. In particular, the influenza virus activates a network of immune cells that leads to clearance or an overzealous response that can be fatal. Tight regulation of the cytokines that enable proper activation and function of immune cells is necessary to clear infections efficiently while minimizing damage to the host. Interleukin-7 (IL-7) is a cytokine known for its importance in T cell development and survival. How IL-7 shapes CD8 T cell responses during an acute viral infection is less understood. We had previously shown that IL-7 signaling deficient mice have reduced accumulation of influenza-specific CD8 T cells following infection. We sought to determine whether IL-7 affects early CD8 T cell expansion in the mediastinal lymph node and effector function in the lungs. Using IL-7R signaling deficient mice, we show that IL-7 is required for a normal sized mediastinal lymph node and the early clonal expansion of antigen-specific CD8 T cells therein. Bone marrow chimeric models and adoptive transfer of transgenic TCR CD8 T cells reveal a cell-intrinsic role for IL-7 in the accumulation of NP366-374 and PA224-233-specific CD8 T cells. We also found that IL-7 dictates terminal differentiation, degranulation and cytokine production in PA224-233-specific but not NP366-374-specific CD8 T cells. We further demonstrate that IL-7 is induced in the lung tissue by viral infection and we characterize multiple cellular sources that contribute to IL-7 production. Drugs that manipulate IL-7 signaling are currently under clinical trial for multiple conditions. Our findings on IL-7 and its effects on lower respiratory diseases will be important for expanding the utility of these therapeutics. Author SummaryInterleukin-7 plays an important role in development of immune cells such as lymphocytes. In recent years, its role in the immune system has been expanded beyond the development of immune cells to include revitalizing of lymphocytes during tumor and chronic viral response. We show here that IL-7 is required for accumulation and function of specialized lymphocytes in the lungs during an acute influenza infection.

immunology↗