Protective Role of Adipose-Derived Stem Cells in Staphylococcus aureus-Induced Lung Injury is Mediated by RegIIIγ Secretion.

Effective and specific therapeutic approaches are still needed for treating acute lung injury caused by severe pneumonia. Adipose-derived stem cells (ADSCs) are well-characterized adult stem cells that have antibacterial and anti-inflammatory effects. In this study, we evaluated the therapeutic effect of ADSCs on Staphylococcus aureus-induced acute lung injury in mice. Our results showed that intratracheal injection of ADSCs could attenuate the severity of lung inflammation, and reduce the bacterial load as well as mortality among infected mice. Our experiments also revealed that the secretion of regenerating islet-derived IIIγ (RegIIIγ) is responsible for the protective effect of ADSCs. Moreover, the expression of RegIIIγ requires TLR2, MyD88, and JAK2/STAT3 activation. In conclusion, ADSCs exhibit a direct antimicrobial activity that is mediated primarily by the TLR2-MyD88-JAK2/STAT3-dependent secretion of RegIIIγ. Stem Cells 2016;34:1947-1956.