HSF1 enhances the attenuation of exosomes from mesenchymal stem cells to hemorrhagic shock induced lung injury by altering the protein profile of exosomes.

Severe hemorrhagic shock (HS) leads to lung injury, resulting in respiratory insufficiency. Mesenchymal stem cell (MSC)-derived exosomes have therapeutic effects on the organ injury. HSF1 has been reported to protect the lung against injury. In this study, the role of exosomes from HSF1-overexpressed MSCs (HSF1-EVs) in HS-induced lung injury was investigated. We constructed a mouse model of lung injury by induction with HS and pre-treated it with HSF1-EVs. It was clarified that HSF1-EVs manifested better protective effects on HS-induced lung injury compared with the exosomes derived from control MSCs. Inhalation of HSF1-EVs declined the ratio of wet to dry and total protein concentration in bronchoalveolar lavage fluids. Besides, HSF1-EVs greatly inhibited the production of inflammatory cytokines (IL-1ß, IL-6, MCP-1 and HMGB1), and constrained the pulmonary neutrophilic infiltration induced by HS. A reduction of oxidative stress was observed in HSF1-EV-treated mice. HSF1-EVs suppressed the HS-induced apoptosis of lung cell and downregulated Bcl-2 expression, while promoting Bax expression. The key proteins of pulmonary epithelial barrier, E-cadherin, ZO-1 and Occludin, were all upregulated in HS-treated mice after HSF1-EV inhalation, suggesting that HSF1-EVs played a protective role in the epithelial barrier of lung. Additionally, the results of proteomics showed that HSF1 overexpression altered the protein profile of MSC-derived exosomes, which might explain the more significant relief effect of HSF1-EVs on lung injury compared with that of Plasmid-EVs. These new findings demonstrated that the exosomes secreted by HSF1-overexpressed MSCs can be an effective precautionary measure for lung injury induced by HS.