Exosomes derived from LPS-preconditioned bone marrow-derived MSC modulate macrophage plasticity to promote allograft survival via the NF-κB/NLRP3 signaling pathway

Abstract

Objectives This study investigated whether exosomes from LPS pretreated bone marrow mesenchymal stem cells (LPS pre-MSCs) could prolong skin graft survival. Methods The exosomes were isolated from the supernatant of MSCs pretreated with LPS. LPS pre-Exo and rapamycin were injected via the tail vein into C57BL/6 mice allografted with BALB/c skin; graft survival was observed and evaluated. The accumulation and polarization of macrophages were examined by immunohistochemistry. The differentiation of macrophages in the spleen was analyzed by flow cytometry. For in vitro, an inflammatory model was established. Specifically, bone marrow-derived macrophages (BMDMs) were isolated and cultured with LPS (100 ng/ml) for 3 h, and were further treated with LPS pre-Exo for 24 h or 48 h. The molecular signaling pathway responsible for modulating inflammation was examined by Western blotting. The expressions of downstream inflammatory cytokines were determined by Elisa, and the polarization of macrophages was analyzed by flow cytometry. Results LPS pre-Exo could better ablate inflammation compared to untreated MSC-derived exosomes (BM-Exo). These loaded factors inhibited the expressions of inflammatory factors via a negative feedback mechanism. In vivo, LPS pre-Exo significantly attenuated inflammatory infiltration, thus improving the survival of allogeneic skin graft. Flow cytometric analysis of BMDMs showed that LPS pre-Exo were involved in the regulation of macrophage polarization and immune homeostasis during inflammation. Further investigation revealed that the NF-κB/NLRP3/procaspase-1/IL-1β signaling pathway played a key role in LPS pre-Exo-mediated regulation of macrophage polarization. Inhibiting NF-κB in BMDMs could abolish the LPS-induced activation of inflammatory pathways and the polarization of M1 macrophages while increasing the proportion of M2 cells. Conclusion LPS pre-Exo are able to switch the polarization of macrophages and enhance the resolution of inflammation. This type of exosomes provides an improved immunotherapeutic potential in prolonging graft survival.

The MSC-EV-microRNAome: A Perspective on Therapeutic Mechanisms of Action in Sepsis and ARDS

“…Several licensing strategies reliably enhance MSC-derived EV immunoregulatory and therapeutic effects. These priming strategies include pre-exposure to TNFα, IL-1β, IFN-γ alone or in combination [28,75,76,105,[108][109][110][111][112][113][114][115][116][117]; TLR ligands such as LPS [118][119][120], hypoxia [121,122], or other factors, including thrombin [107], the endoplasmic reticulum stress inducer, thapsigargin [123], and the lipophilic photosensitizer, hexyl-5-aminolevulinate hydrochloride (HAL) in combination with pro-inflammatory cytokines [113]; transfection with miR [124]; or serum from injury models [20,34,43], BALF, as above; or secretome from LPS-activated cells such as microglia [125]. EVs derived from licensed or primed MSCs have been investigated in an array of inflammatory conditions and while the pathogenic factors driving specific diseases may differ, there is a large consensus across studies demonstrating the protective and immunoregulatory effects of MSC-derived EVs.…”

“…EVs derived from licensed or primed MSCs have been investigated in an array of inflammatory conditions and while the pathogenic factors driving specific diseases may differ, there is a large consensus across studies demonstrating the protective and immunoregulatory effects of MSC-derived EVs. Much attention has been centered on the relevance of priming strategies on macrophage polarization [43,75,76,105,109,113,116,[119][120][121][122][123]125] or transition toward pro-resolution of infection or inflammatory cellular phenotypes [112,118].…”

Dexamethasone and IFN-γ primed mesenchymal stem cells conditioned media immunomodulates aberrant NETosis in SLE via PGE2 and IDO

“…Stem cell derived secretory factors or the secretome collected from the culture media is referred as cell free conditioned media (CM) and has several advantages over the use of MSCs. Further, preconditioning the MSCs prior to preparing the CM (pre-conditioned CM) enhance the ability of the secretome to regulate both the innate and adaptive immune responses in patients affected by immune system related diseases (Ti et al, 2015, Yang et al, 2021and Zhang et al, 2023, hence, this approach can be explored for immunomodulating NETosis in SLE.…”

Functional extracellular vesicles from SHEDs combined with gelatin methacryloyl promote the odontogenic differentiation of DPSCs for pulp regeneration

“…External stimulation and pre-culture are some of the engineering strategies to tailor EVs for better therapeutic potency in tissue regeneration [ 11 ]. By altering the cell culture medium or inducing cells to differentiate in a specific direction, the EVs secreted by their parental cells will possess corresponding biological effects [ 11 , 12 ]. Although a better osteogenic/odontogenic capacity of EVs than pre-differentiated cells was demonstrated in the literature [ 13 – 15 ], comprehensive evaluations of preconditioned EVs on the biological behavior of recipient cells remain limited.…”