Low-Intensity Pulsed Ultrasound Promotes a Treg-Like Phenotype and Suppresses a Th17-Like Phenotype in CD4+ T Cells via YAP/TAZ Activation in vitro

Renli Yang,1 Xirui Zhang,2 Yanjun Zhang,3 Yi Man,2 Xingmei Yang2 1State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Jinjiang Clinic, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, 610041, People’s Republic of China; 2State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Implantology, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, 610041, People’s Republic of China; 3Department of Stomatology, West China Xiamen Hospital of Sichuan University, Xiamen, Fujian, People’s Republic of ChinaCorrespondence: Xingmei Yang, State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Implantology, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, 610041, People’s Republic of China, Tel +86-28-85503571, Email [email protected]: CD4+ T cell subpopulations, particularly T helper 17 (Th17) and regulatory T (Treg) cells, exhibit antagonistic functions and play essential roles in inflammatory responses. Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are critical modulators of cell proliferation and differentiation. Low-intensity pulsed ultrasound (LIPUS) has been shown to regulate YAP/TAZ activity, but its role in Th17/Treg balance remains unclear.Methods: CD4+ T cells were purified from rat peripheral blood mononuclear cells (PBMCs) using magnetic-activated cell sorting (MACS). The cells were then treated with low-intensity pulsed ultrasound (LIPUS) at a set of parameters (1.0 MHz, 20 mW/cm², 20% duty cycle, 2h/day for 3 days) optimized based on preliminary proliferation and apoptosis assays. The effects of LIPUS on the expression of key functional markers (Foxp3 for Treg-like cells and IL-17A for Th17-like cells) were evaluated by flow cytometry, quantitative PCR, and ELISA. The activation and subcellular localization of YAP/TAZ were examined using immunofluorescence staining. Furthermore, siRNA-mediated knockdown was performed to investigate the functional involvement of YAP/TAZ in the LIPUS-mediated effects.Results: LIPUS treatment significantly increased the frequency of Foxp3-expressing cells while decreasing the frequency of IL-17A-producing cells. Additionally, LIPUS promoted the activation and nuclear translocation of YAP and TAZ, as evidenced by enhanced protein expression and a shift in subcellular localization. siRNA-mediated knockdown of YAP/TAZ attenuated the LIPUS-induced increase in Foxp3+ cells and potentiated the population of IL-17A+ cells. Importantly, LIPUS treatment effectively rescued the expression patterns of these functional markers following YAP/TAZ inhibition.Discussion: Our findings demonstrate that LIPUS promotes a Treg-like phenotype and suppresses a Th17-like phenotype in CD4+ T cells, a process that is mediated, at least in part, by the activation of the YAP/TAZ signaling pathway. This immunomodulatory effect suggests that LIPUS could be explored as a novel non-invasive strategy for managing autoimmune diseases and chronic inflammatory conditions associated with an imbalance in T cell responses.Keywords: low-intensity pulsed ultrasound, Treg, Th17, YAP, TAZ