Background: Dipeptidyl peptidase-4 (DPP4) is a transmembrane
glycoprotein, prevalent across a variety of tissues and cells and can be foundin
a solubilised in peripheral blood. This paper aims at determining the role of
sCD26/sDPP4 in Th17 cell polarization and airway epithelial cell to epithelial
mesenchymal transition (EMT) in asthma. Methods: Female C57BL/6J mice
were treated with ovalbumin to constructed asthma mice. The CD4 T cell, and
bronchial epithelial cells (BECs) were purified from the spleens and bronchus of
mice. The KRT8 expression in BECs were identified by immunofluorescence (IF).
Th17 cells were differentiated from a CD4 T cell. Flow cytometry was usewd
to identify and calculate the Th17 and Treg cells. Mice woth asthma were treated
by DPP4 overexpressing lentivirus or DPP4 inhibitor. Histopathological
modifications were assessed by hematoxylin-eosin (HE), periodic acid Schiff
(PAS), and Masson staining. The total number of leucocytes was detected using a
hemocytometer. For detection, quantitative
Real-time PCR (qRT-PCR), western blotting (WB), and IF were used to evaluate the
expression of E-cadherin and alpha-smooth muscle actin (-SMA).
Enzyme-linked immunosorbent assay (ELISA) was performed to analyze the DPP4,
IL-4, IL-5, IL-13 and IL-17 levels. Results: The findings suggest that
sCD26/sDPP4 promote CD4 T cells differentiation into Th17 cells in a
depending on the applied dose. sCD26/sDPP4 up-regulated the expression of
-SMA and down-regulated the expression of E-cadherin in
TGF-1-induced mouse BECs, which was reversed by DPP4 inhibitor.
Co-culture induced a synergic effect between Th17 cells and sCD26/sDPP4 on the
formation of airway EMT in BECs. Furthermore, DPP4 inhibitor prevented
lung-bronchial inflammatory infiltration, mucus secretion, goblet cell
hyperplasia and collagen deposition in asthma mice. Meanwhile, DPP4 inhibitor
decreased the levels of DPP4, IL-4, IL-5, IL-13, IL-17 and increased the total
number of leukocytes in bronchoalveolar lavage fluid of asthma mice. In addition,
DPP4 inhibitor also inhibited airway EMT and Th17 cell polarization in asthma
mice. Conclusions: The results in this paper show that up-regulation of
DPP4 enabled airway inflammation and airway remodeling in asthmatic mice by
modulating the Th17/IL-17 axis and accelerating the airway EMT, which isa
therapeutic target in asthma.