Methods: We used an in vitro system of human esophageal epithelial cells that were subjected to air-liquid interface (ALI) to induce squamous cell differentiation. Cells were stably transduced with either non-silencing control or SPINK7 shRNAs. The integrity of the epithelium was examined by barrier function assays complemented by histological and ultrastractural analyses and immune-fluorescence of junctional proteins. Protease activity, transcriptional alterations and identification SPINK7’s downstream targets were assessed. Last, cytokines and chemokines secretion was analyzed after SPINK7gene silencing.
Results: we determined that depletion of SPINK7 results in transcriptional alterations including down-regulation of other SPINKs and unleashes trypsin-like serine protease activity. In vitro, SPINK7 inhibits the serine protease- kallikrein 5 that is known to be involved in the regulation of the skin barrier. Furthermore, we demonstrated that SPINK7 gene silencing is sufficient for induction of architectural alterations in junctional complexes and a profound loss of the “zipper-like” structures in between the epithelial cells that characterize the healthy esophageal epithelium and is missing in EoE. These alterations followed by impaired barrier function. In addition, loss of SPINK7 induces a series of pro-inflammatory cytokines and Chemokines.
Conclusions: we suggest that deficiency of SPINK7 results in uncontrolled proteases activity which is a novel checkpoint for regulating pro-inflammatory esophageal epithelial responses.