Soluble E-cadherin contributes to inflammation in acute lung injury via VEGF/VEGFR2 signaling

As a gatekeeper of the airway epithelial cells, E-cadherin is not only a critical component for the maintenance of epithelial integrity, but also engaged in pathological processes through the release of a soluble form (sE-cadherin). This study was aimed to investigate the role of sE-cadherin in ALI/ARDS. Serum samples from patients with ARDS and healthy volunteers were collected for the detection of sE-cadherin. An LPS-induced mouse model was induced to analyze the expression of sE-cadherin, and a neutralizing antibody against sE-cadherin (DECMA-1) was given to the LPS-exposed mice. The effects of recombinant sE-cadherin were tested both in vitro and in vivo, and VEGFR2 inhibition was used to explore a possible mechanism for sE-cadherin-induced pulmonary inflammation. We observed an increased level of sE-cadherin in ARDS patients as well as in LPS-exposed mice. In vivo treatment of DECMA-1 significantly attenuated LPS-induced inflammation. In vitro, exogenous sE-cadherin can dramatically upregulate the expression of VEGF in THP1-derived macrophages and human primary macrophages. In addition, intratracheal instillation of recombinant sE-cadherin leads to significant increased infiltration of neutrophils as well as overproduction of IL-6 and IL1β, which could be attenuated by inhibition of VEGF/VEGFR2 signaling. While blockade of the VEGF/VEGFR2 pathway inhibited pulmonary inflammatory responses in LPS-exposed mice. Taken together, our data demonstrated that sE-cadherin contributes to lung inflammation in ALI/ARDS, which is related to activation of the VEGF/VEGFR2 pathway.