Extracellular Vesicles Derived from Lipopolysaccharide-Pretreated Periodontal Ligament Stem Cells Ameliorate Inflammatory Responses in Experimental Colitis via the PI3K/AKT Signaling Pathway.

Introduction: Inflammatory bowel disease is a complex chronic inflammatory condition characterized by dysbiosis of the gut microbiota and dysregulation of immune system. In recent years, extracellular vesicles (EVs) derived from mesenchymal stem cells have garnered significant attention for their beneficial potentials in immune modulation and tissue repair. This study aims to evaluate the therapeutic effects and underlying mechanisms of EVs derived from lipopolysaccharide (LPS)-pretreated periodontal ligament stem cells (PDLSCs) in mice with colitis.

Methods: A mouse model of colitis was established using 3.0% dextran sulfate sodium (DSS). Following the induction of colitis, mice were treated via tail vein injection with either conventional PDLSC-derived EVs (P-EVs) or LPS-pretreated PDLSC-derived EVs (LPS pre-EVs). The EVs were characterized using transmission electron microscopy, nanoparticle tracking analysis, and Western blot analysis. The therapeutic effects and mechanisms were evaluated through a combination of small animal live imaging, disease activity index (DAI) scoring, histopathological staining, qRT-PCR, 16S rRNA gene sequencing, and mass spectrometry analysis.

Results: The LPS pre-EVs exhibited typical EVs characteristics in terms of morphology, particle size distribution, and marker protein expression. Compared to P-EVs, LPS pre-EVs significantly ameliorated weight loss, DAI scores, colon length, and perianal symptoms in DSS-induced murine colitis. Additionally, LPS pre-EVs up-regulated the expression of Arginase-1, a typical M2 macrophage marker, and tight junction proteins, including ZO-1, Occludin, and Claudin-1, enhanced gut microbial diversity, and significantly regulated intestinal protein expression and activation of the PI3K/AKT signaling pathway.

Conclusion: LPS pre-EVs exhibit significant anti-inflammatory and tissue repair effects in a mouse model of colitis. The underlying mechanisms may involve the regulation of macrophage polarization, maintenance of intestinal barrier function, modulation of the gut microbiota, and activation of the PI3K/AKT signaling pathway.