As novel agonists of Wnt/β-catenin signaling pathway, R-spondin proteins constitute a class of ligands, including R-spondin 1/2/3/4, functioning through their receptors leucine-rich repeat-containing G-protein coupled receptor (LGR)4/5/6 to enhance Wnt/β-catenin activity. Since Wnt signaling plays pivotal roles in the regulation of many life processes involved in embryogenesis and adulthood, R-spondin proteins also take part in cell proliferation, differentiation and morphogenesis. For example, in the formation of respiratory system，R-spondin 2 is required for normal laryngeal-tracheal and lung morphogenesis，and the lack of R-spondin 1 expression results in the absence of duct side-branching development and subsequent alveolar formation. In addition, R-spondins show protective effect in tissue injury and diseases. R-spondin 1 and R-spondin 3 have been reported to prevent chemotheraphy- or radiotherapy-induced mucous membrane lesion. R-spondin 1 attenuates oral mucositis contributed by radiotherapy in mouse models and R-spondin 3 potentiates intestinal regeneration elicited via gastrointestinal toxic effect of chemoradiotherapy treatment. However, whether R-spondin proteins exert salient influence on acute lung injury especially induced by mechanical ventilation is deficient. Therefore, this study aims to ascertain the implication of R-spondin proteins in the pathology of mechanical ventilation induced lung injury through detecting human plasma concentration change of R-spondin 1/2/3/4 after mechanical ventilation and interference effects in mouse model, which is helpful for prevention and treatment of ventilation induced lung injury.