Thymic stromal lymphopoietin (TSLP) pathway blockade is a potential strategy for asthma treatment because the main activities of TSLP are activation of myeloid dendritic cells (mDCs) and modulation of cytokine production by mast cells. TSLP-activated mDCs prime the differentiation of naive T cells into inflammatory T_H2 cells.

We sought to investigate mechanisms underlying the development of allergic lung inflammation in cynomolgus monkeys using gene expression profiling and to assess the effect of thymic stromal lymphopoietin receptor (TSLPR) blockade in this model.

An mAb against human TSLPR was generated and confirmed to be cross-reactive to cynomolgus monkey. Animals were dosed weekly with either vehicle or anti–TSLPR mAb for 6 weeks, and their responses to allergen challenge at baseline, week 2, and week 6 were assessed.

After 6 weeks of treatment, anti-TSLPR mAb–treated animals showed reduced bronchoalveolar lavage (BAL) fluid eosinophil counts, reduced airway resistance in response to allergen challenge, and reduced IL-13 cytokine levels in BAL fluid compared with values seen in vehicle-treated animals. Expression profiling of BAL fluid cells collected before and after challenge showed a group of genes upregulated by allergen challenge that strongly overlapped with 11 genes upregulated in dendritic cells (DCs) when in vitro stimulated by TSLP (TSLP-DC gene signature). The number of genes differentially expressed in response to challenge was reduced in antibody-treated animals after 6 weeks relative to vehicle-treated animals. Expression of the TSLP-DC gene signature was also significantly reduced in antibody-treated animals.

These results demonstrate promising efficacy for TSLPR blockade in an allergic lung inflammation model in which TSLP activation of mDCs might play a key role.