Anti-DLL4 ameliorates toluene diisocyanate-induced experimental asthma by inhibiting Th17 response

Toluene diisocyanate (TDI) exhibits an ability to induce steroid insensitive asthma with the involvement of Th17 cells. And emerging evidence has indicated that DLL4 signaling promotes Th17 differentiation through directly upregulating Rorc and IL-17 transcription. Thus, we sought to evaluate the effects of DLL4 blocking antibody on TDI-induced asthma model. Female BALB/c mice were sensitized and challenged with TDI to generate an asthma model. TDI-exposed mice were intraperitoneally injected with anti-DLL4 antibody and then analyzed for various parameters of the airway inflammatory responses. Increased expression of DLL4 in spleen and lung was detected in TDI-exposed mice. Furthermore, anti-DLL4 treatment alleviated TDI-induced airway hyperreactivity (AHR), airway inflammation, airway epithelial injury and airway smooth muscle (ASM) thickening. In the meantime, neutralizing DLL4 also blunted Th17 response via downregulation of ROR-γt expression, while had no effect on Th2 cells and regulatory T (Treg) cells. Overall, anti-DLL4 ameliorated TDI-induced experimental asthma by inhibiting Th17 response, implying the feasibility of targeting DLL4 for therapy of Th17-predominant severe asthma.