Delivery of miR-26a-5p by Subcutaneous Adipose Tissue-Derived Extracellular Vesicles Alleviates Acute Lung Injury in Mice Through CHUK/NF-κB Pathway.

Background: Acute respiratory distress syndrome (ARDS) is characterized by diffuse lung injury and high mortality rates due to severe inflammation. Adipose tissue, functioning as both an endocrine and immune organ, plays a crucial role in immune regulation by secreting a variety of adipokines. Among these, adipose tissue-derived extracellular vesicles (EVs) have emerged as novel mediators of intercellular communication, capable of delivering bioactive molecules such as microRNAs to target cells. This study aimed to elucidate the immunomodulatory roles and underlying mechanisms of adipose tissue-derived EVs in the pathogenesis of ARDS.

Methods: Subcutaneous adipose tissue extracellular vesicles (SAT-EVs) were collected from the mice via ultracentrifugation. C57BL/6 mice were administered SAT-EVs (1×10^9 particles per mouse) via tail vein injection, followed by an intraperitoneal Lipopolysaccharide (LPS) injection three hours later to induce acute respiratory distress syndrome (ARDS). The mice were euthanized after 18 h to evaluate the permeability of the microvessels and level of inflammation in the lungs. For in vitro experiments, RAW 264.7 macrophages were stimulated with LPS, with or without SAT-EVs, as a control, to evaluate the inflammatory response of the macrophages.

Results: SAT-EVs treatment enhanced the survival rate of ARDS mice and reduced pulmonary vascular permeability. SAT-EVs were internalized by alveolar macrophages, leading to an attenuation of inflammation, as indicated by decreased levels of TNF-α, IL-1β, iNOS, PTGS2, and CCL2. Notably, SAT-EVs transferred miR-26a-5p to alveolar macrophages, which directly targeted conserved helix-loop-helix ubiquitous kinase (CHUK), a key regulator of the NF-κB pathway. This inhibition resulted in reduced transcription of inflammatory mediators (iNOS, PTGS2, and IL-1β). In vitro, SAT-EVs were internalized by RAW 264.7 macrophages, leading to the suppression of LPS-induced inflammation, as shown by decreased expression of TNF-α, IL-1β, iNOS, PTGS2, and CCL2. These findings suggest that miR-26a-5p plays a crucial role in the anti-inflammatory effects of SAT-EVs by suppressing CHUK and modulating the NF-κB pathway.

Conclusion: SAT-EVs significantly attenuated LPS-induced ARDS, potentially through the CHUK/NF-κB pathway mediated by miR-26a-5p, thereby exerting protective effects against inflammatory lung injury. These findings provide mechanistic insights into the role of SAT-EVs in immune modulation and suggest their potential as a therapeutic strategy for ARDS.