Figure 1.

NT4 was required for mucus overproduction after early life allergen exposure. A) Experimental scheme of early life OVA exposure in mice. Control mice were challenged with saline (PBS). Lungs were collected at P21. B) Serum levels of IL-13 measured by ELISA. Each mark represents 1 mouse. C) Differential immune cell counts in BAL. Relative abundance of macrophages (Mac), eosinophils (Eos), neutrophils (Neut), and lymphocytes (Lymph) was quantified as percentage of cells in BAL; n = 9 per group. D) Representative images of PAS staining in airways of WT and NT4^−/− mice challenged with PBS or OVA. Mucin⁺ cells are marked by arrows. Enlarged epithelium staining is shown in inserts. E) Muc5ac mRNA expression in WT and NT4^−/− mice that were challenged with PBS or OVA; n = 14 mice for each group. F) Muc5ac mRNA levels in lung slices of P21 WT mice (n = 3) after 48 h in culture. Results were normalized to PBS-challenged controls. G) Muc5ac mRNA levels in lung slices of P21 NT4^−/− mice (n = 6) after 48 h in culture with and without neurotransmitter treatment. Results were normalized to PBS-challenged slices without treatment. Neurotransmitters tested included GABA (10 mg/ml), CGRP (10 µM), substance P (SP, 10 µM), dopamine (dopa, 10 µM), and Mch (10 μM). Data in C–E represent means ± sem from 3 independent experiments. *P < 0.05, **P < 0.01. Scale bar, 100 µm.