Endothelium-Treg Communication Through Extracellular Vesicle Transfer Exacerbates Acute Respiratory Distress Syndrome

Area of Science:

• Immunology
• Cell Biology
• Pulmonary Medicine

Background:

• Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are characterized by reduced Foxp3+ regulatory T cells (Tregs) in the lungs, leading to inflammation and impaired recovery.
• The role of extracellular vesicles (EVs) in the pulmonary microenvironment on Treg function remains largely unknown.

Purpose of the Study:

• To investigate the impact of endothelial cell-derived EVs on Treg function in the context of ALI and ARDS.
• To elucidate the molecular mechanisms by which these EVs modulate Treg activity and contribute to lung inflammation.

Main Methods:

• Single-EV analysis to quantify endothelial cell-derived EVs (CD31+ EVs) in LPS-induced ALI models.
• In vitro co-culture experiments exposing Tregs to EVs from activated pulmonary endothelial cells (ECs).
• Analysis of IL-21 production and Foxp3 expression in Tregs upon EV exposure.
• Investigation of Med1's role in EV-mediated IL-21 transcription in Tregs.
• Assessment of therapeutic potential by suppressing Med1 in EVs.

Main Results:

• Endothelial cell-derived EVs (CD31+ EVs) are increased in LPS-induced ALI models.
• EVs from activated pulmonary ECs suppress Treg induction and promote IL-21 production in Tregs, reducing Foxp3 expression.
• Med1, enriched in these EVs, directly binds to the IL-21 gene promoter, activating its transcription in Tregs.
• Suppression of Med1 in EVs reverses Treg differentiation and alleviates lung inflammation.
• Increased EVs carrying Med1 are found in the bronchoalveolar lavage fluid (BALF) of ARDS patients.

Conclusions:

• EV-mediated communication between pulmonary endothelium and Tregs is critical for Treg suppression in ARDS.
• The Med1-IL-21 axis in endothelial EVs represents a significant mechanism of Treg dysfunction in ARDS.
• Targeting EV-mediated endothelium-Treg communication offers potential therapeutic strategies for ARDS.