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A2301 - Microvesicle-Containing miRNAs Regulate Macrophage Migration Via Modulating Integrin Recycling and Trafficking
Author Block: H. Lee, D. Zhang, Y. Jin; Boston University, Boston, MA, United States.
Background and significance: Acute lung injury (ALI) is a disorder of acute inflammation which causes unacceptably high mortality rate. Because of the complexity and redundancy of the pathogenesis, effective treatments are currently still limited. Recently, the interests focusing on the microvesicle vesicle (MV)-mediated intercellular transfer of microRNAs are emerging. MV-containing miRNAs are known to regulate various cellular process through targeting multiple genes. However, our understanding on the MV-containing miRNAs in ALI remains unclear. Methods: Acid (0.1N HCl) was instilled into mouse lung to generate ALI model. Primary lung epithelial cells, alveolar macrophages, and bone-marrow derived macrophages were isolated from WT or HCl-injured mice. MVs were isolated from the bronchoalveolar lavage fluid (BALF). MV-containing miRNAs were analyzed using real-time qPCR. Macrophage migration/integrin recycling assays were performed using BALF MVs transfected with specific miRNA mimics or inhibitors. Integrin expression and trafficking in macrophages were explored using western blotting and Biotin-based immunofluorescence technique. Result: We confirmed that acid instillation promotes the macrophage migration into the lung alveoli. Next, we demonstrated that miR-17/221 were upregulated in BALF-MVs after acid instillation and the MV-containing miR-17/221 were efficiently delivered to the macrophage in vivo. Notably, we found that delivery of miR-17/221 via MVs significantly induce macrophage migration in vitro and in vivo. Mechanistically, we demonstrated that MV-containing miR-17/221 upregulate expression level of Rab11 which is responsible for integrin recycling and integrin-mediated cell migration. The upregulated Rab11 was highly co-localized with integrin β1 in macrophage cytoplasm. Interestingly, the MV-containing miR-17/221 significantly promoted recycling of surface integrin β1 and suppressed degradation of the integrin. Summary: we have demonstrated that miR-17/221 are upregulated in BALF MVs in the acid-induced ALI model. The MV-containing miR-17/221 are effectively delivered into macrophage and induce migration of the macrophage via controlling integrin-recycling process, demonstrating functional significance of the BALF MVs-containing miRNAs for the immune responses in the development of ALI.