Pretreatment with interleukin 35-engineered mesenchymal stem cells protected against lipopolysaccharide-induced acute lung injury via pulmonary inflammation suppression

Acute lung injury (ALI)-triggered pulmonary injury has been associated with high mortality, despite advances in drug treatment and supportive therapy. Remarkable progress has been made in attenuating the inflammatory injury associated with ALI using mesenchymal stem cells (MSCs)-based cell and gene therapy. However, to date, the benefits of interleukin-35 (IL-35)-modified MSCs in ALI intervention have not been investigated. In the present study, adult male C57BL/6 mice randomly received intravenous infusion of adipose-derived mesenchymal stem cells (ADSCs) constitutively expressing IL-35 (IL-35-GFP-ADSCs) or GFP (GFP-ADSCs) via retrovirus-mediated transduction (8 × 10(5) cells per mice) or isotonic saline 7 days before ALI modeling to investigate the effect and related mechanism. ALI was performed by lipopolysaccharide (LPS) inhalation for 24 h. Normal mice served as the sham group. The results indicated that compared with GFP-ADSCs, IL-35-modified ADSCs significantly increased cellular and pulmonary IL-10 and IL-35 production. Pretreatment with IL-35-ADSCs markedly reduced body weight loss, pulmonary wet/dry weight ratio and pathological injury. The PO(2) was rescued to normal levels in mice that received IL-35-ADSCs. IL-35-ADSCs infusion apparently inhibited IL-6 release, protein leakage and MPO activity but greatly elevated IL-35 level in the bronchoalveolar lavage fluid (BALF). Splenic regulatory T cells in IL-35-ADSCs-pretreated mice got effective increase. Moreover, IL-35-ADSCs pretreatment remarkably inhibited neutrophil and macrophage infiltration and greatly decreased IL-6, tumor necrosis factor α (TNF-α) and Toll-like receptor 4 (TLR4) expression. In conclusion, pretreatment with IL-35-engineered ADSCs provided effective protection against LPS-induced ALI through suppression of pulmonary inflammation and, thus, might be a promising strategy to improve outcomes after ALI. The enhanced paracrine and immunosuppressive capacity of IL-35-ADSCs might contribute to their beneficial effects. However, further studies are needed to illuminate the detailed mechanism.