Exosomes Represent an Immune Suppressive T Cell Checkpoint in Human Chronic Inflammatory Microenvironments

Area of Science:

• Immunology
• Cell Biology
• Exosome Biology

Background:

• T cells in chronic inflammatory tissues show hypo-responsiveness.
• Exosomes are implicated in tumor-associated T cell suppression.
• The role of exosomes in chronic inflammation-induced T cell suppression is unknown.

Purpose of the Study:

• To investigate if exosomes from chronic inflammatory microenvironments suppress T cell function.
• To identify mechanisms of T cell suppression by these exosomes.

Main Methods:

• Exosomes isolated via ultracentrifugation and characterized using nanoparticle tracking analysis, SEM, antibody arrays, and flow exometry.
• T cell activation assessed by NFκB nuclear translocation.
• Exosomes derived from nasal polyps and rheumatoid arthritis synovial fluid.

Main Results:

• Exosomes from chronic inflammatory tissues were successfully isolated and characterized.
• These exosomes were found to inhibit T cell activation via the T cell receptor (TCR).
• Ganglioside GD3 on the exosomal surface partially mediates this immune suppression.

Conclusions:

• Immunosuppressive exosomes in non-malignant chronic inflammation act as a novel T cell checkpoint.
• These exosomes represent a potential therapeutic target to improve T cell responses.
• Targeting these exosomes could enhance current therapies and prevent disease recurrence.