Maternal Exposure to Antibiotics Increases the Severity of Asthma in Offspring Mice

Abstract

The serine peptidase inhibitor kazal-type (SPINK)7 is down-regulated in eosinophilic esophagitis (EoE), a type-2 immune disease of the esophagus. Loss of SPINK7 in esophageal epithelial cells unleashes a pro-Inflammatory response and loss of barrier function. Herein, we investigated the mechanism by which SPINK7 mediates its function. METHODS: We performed SPINK7 silencing and genetic depletion of SPINK7 in human esophageal epithelial cells that were cultured at the airliquid interface. Protease activity of SPINK7 deficient epithelial cells and human esophageal tissue was measured, and receptor expression of esophageal tissue-derived eosinophils was quantified. We assessed whether genetic variants in atopic genes were associated with EoE susceptibility. In vitro assays using recombinant proteins were conducted to identify direct targets of SPINK7. Last, we used murine-EoE model to identify the role of SPINK7 target protease; Kallikrein (KLK)5. RESULTS: Epithelial deficiency of SPINK7 promoted increased urokinase plasminogen activator (uPA) and trypsin-like activities (1.8-fold and 3-fold; p50.013, p50.004 respectively). uPA activity was increased by 10-fold in the esophagus of EoE patients as compared to control individuals (p50.043). uPA had the capacity to promote eosinophil activation. Genetic studies revealed a strong epistasis between genetic variants in PLAU (gene product, uPA) with the atopy risk variant in TSLP gene. Furthermore, we revealed KLK5 as SPINK7 target (K i 5132 nM). KLK5 deficient mice had 5-fold decrease in eosinophil infiltration to the esophagus as compared to wt mice (p50.0008). CONCLUSIONS: We propose that loss of SPINK7 in the esophagus unleashes uncontrolled activity of KLK5 and uPA which regulate eosinophil infiltration and activation in the esophagus.