Low-Intensity Ultrasound-Induced Anti-inflammatory Effects Are Mediated by Several New Mechanisms Including Gene Induction, Immunosuppressor Cell Promotion, and Enhancement of Exosome Biogenesis and Docking

Abstract

Background: Low-intensity ultrasound (LIUS) was shown to be beneficial in mitigating inflammation and facilitating tissue repair in various pathologies. Determination of the molecular mechanisms underlying the anti-inflammatory effects of LIUS allows to optimize this technique as a therapy for the treatment of malignancies and aseptic inflammatory disorders.Methods: We conducted cutting-edge database mining approaches to determine the anti-inflammatory mechanisms exerted by LIUS.Results: Our data revealed following interesting findings: (1) LIUS anti-inflammatory effects are mediated by upregulating anti-inflammatory gene expression; (2) LIUS induces the upregulation of the markers and master regulators of immunosuppressor cells including MDSCs (myeloid-derived suppressor cells), MSCs (mesenchymal stem cells), B1-B cells and Treg (regulatory T cells); (3) LIUS not only can be used as a therapeutic approach to deliver drugs packed in various structures such as nanobeads, nanospheres, polymer microspheres, and lipidosomes, but also can make use of natural membrane vesicles as small as exosomes derived from immunosuppressor cells as a novel mechanism to fulfill its anti-inflammatory effects; (4) LIUS upregulates the expression of extracellular vesicle/exosome biogenesis mediators and docking mediators; (5) Exosome-carried anti-inflammatory cytokines and anti-inflammatory microRNAs inhibit inflammation of target cells via multiple shared and specific pathways, suggesting exosome-mediated anti-inflammatory effect of LIUS feasible; and (6) LIUS-mediated physical effects on tissues may activate specific cellular sensors that activate downstream transcription factors and signaling pathways.Conclusions: Our results have provided novel insights into the mechanisms underlying anti-inflammatory effects of LIUS, and have provided guidance for the development of future novel therapeutic LIUS for cancers, inflammatory disorders, tissue regeneration and tissue repair.

Low‐intensity pulsed ultrasound affects growth, differentiation, migration, and epithelial‐to‐mesenchymal transition of colorectal cancer cells

“…Cancer cells actively release EVs into the surrounding microenvironment and these vesicles have been reported to play multiple functions in the regulation of tumor growth and progression. Since Rac1 is involved in EVs biogenesis (Yang et al, 2017) and we found that Rac1 was affected by LIPUS treatment (Figure 7), we also aimed at analyzing whether LIPUS might affect cellular release and/or uptake of EVs. We aimed to quantify this increase and we used a flow cytometry‐based method that we have set up for the evaluation of EVs directly in supernatant of cancer cells and, as shown in Figure 8, we found that LIPUS treatment increased the release of EVs up to 20% and 10% in Caco2 and HT29 cells, respectively (Figure 8a,b).…”

“…Our study confirmed the involvement of Rho GTPase in cell motility induced by LIPUS. Moreover, analyzing the gene expression profiles of microarray datasets on US‐treated cells, Yang et al (2017) showed that LIPUS enhanced EVs biogenesis and internalization. D'Souza et al also showed that US can be used to amplify and localize biomarkers in blood with a relatively simple and noninvasive strategy (D'Souza et al, 2009; Paproski, Jovel, Wong, Lewis, & Zemp, 2017).…”

“…Cancer cells actively release EVs into the surrounding microenvironment and these vesicles have been reported to play multiple functions in the regulation of tumor growth and progression. Since Rac1 is involved in EVs biogenesis (Yang et al, 2017) and we found that Rac1 was affected by LIPUS treatment (Figure 7), we also aimed × 105 cells of the indicated cell lines were plated in 24 well plates and allowed to reach confluence (2 days). A scratch wound was made using a pipette tip.…”

Exosomes Derived From Low‐Intensity Pulsed Ultrasound‐Treated Dendritic Cells Suppress Tumor Necrosis Factor–Induced Endothelial Inflammation

“…These mechanisms include LIPUS inhibiting expression of inflammatory factors like IL‐1α, upregulating expression of anti‐inflammatory genes 25 and reducing infiltration of inflammatory cells into the synovium . It was reported recently that LIPUS enhanced DC‐derived exosome biogenesis and docking . Exosome‐carried anti‐inflammatory cytokines and anti‐inflammatory miRNAs are able to inhibit inflammation of target cells .…”

Ultrasound-mediated microbubble destruction: a new method in cancer immunotherapy

“…Low-frequency US combined with microbubbles simultaneously promotes dendritic cells (DCs) to differentiate and mature in the cancer microenvironment 45. In addition, this phenomenon promotes T lymphocytes to trigger antitumor immunity mediated by T lymphocytes, which enhance the efficacy of angiogenesis targeting 46.…”