Fig 2: Partial loss of polymerase I and transcript release factor (PTRF) led to enhanced local type 2 immune responses. Mice were intraperitoneally injected with PBS or ovalbumin (OVA) on days 0, 7, and 14, and then challenged with PBS or OVA on days 21–27. (A) Representative figure shown the IL-13+IL-4+CD4+T cells from WT and PTRF+/− littermates. (B) Percentages of IL-4+, IL-5+, IL-13+ CD4+ T cells from lung of WT and PTRF+/− littermates. (C) Percentages of IL-4+, IL-5+, IL-13+ CD4+ T cells from spleen and peripheral lymph nodes of WT and PTRF+/− littermates. (D) IL-4, IL-5, and IL-13 levels in culture supernatant of lymphocytes from lung, spleen, and peripheral lymph nodes of WT and PTRF+/− littermates. *p < 0.05, **p < 0.01, as determined by Student’s t-test. Results are pooled data from four independent experiments (mean ± SEM of n = 4 mice in each group).

Fig 3: Phosphorylation of polymerase I and transcript release factor (PTRF) critically controls IL-33 release. (A) Whole cell lysates from wild type PTRF and various single tyrosine mutants (Y13F; Y158F; Y310F; Y318F) transfected HBE cell were immunoprecipitated with GFP antibody followed by SDS-PAGE and blotted with indicated antibodies. (B) IL-33 level of culture supernatant of wild type PTRF and Y158F mutated PTRF transfected HBE cell with or without LPS (1 ng/µl) or HDM (30 µg/µl) treatment. (C) Nuclear and cytoplasmic protein extraction from wild type PTRF and Y158F mutated PTRF transfected HBE cell with or without LPS (1 ng/µl) treatment were blotted with indicated antibodies. (D) Nuclear and cytoplasmic protein extraction from wild type PTRF and PTRF Y158F mutant transfected HBE cell with or without HDM (30 µg/µl) treatment were blotted with indicated antibodies. (E) Representative images of IL-33 (red) and PTRF (green) immunofluorescence of wide type PTRF or Y158F mutated PTRF transfected HBE with or without LPS (1 ng/µl) or HDM (30 µg/µl) treatment. (F) Whole cell lysates from wild type PTRF and Y158F mutated PTRF transfected HBE cell were immunoprecipitated with anti-HA antibody followed by SDS-PAGE and blotted with indicated antibodies. *p < 0.05, **p < 0.01, ***p < 0.001, as determined by Student’s t-test.

Fig 4: Partial loss of polymerase I and transcript release factor (PTRF) led to airway hyperresponsiveness (AHR) and eosinophilic airway inflammation. Mice were intraperitoneally injected with phosphate-buffered saline (PBS) or ovalbumin (OVA) on days 0, 7, and 14, and then challenged with PBS or OVA on days 21–27. (A) AHR in response to inhaled methacholine was measured in PBS- or OVA-challenged mice. Maximal responses to increasing doses of methacholine are shown for lung resistance (Rl) and dynamic compliance (Cdyn). (B) Representative images of hematoxylin and eosin staining of lung tissue (upper panel), and periodic acid-schiff stain (lower panel). (C) Inflammation scores of lung tissues. (D) Cell classification in bronchoalveolar lavage fluid. *p < 0.05, **p < 0.01, ***p < 0.001. Results are pooled data from four independent experiments (mean ± SEM of n = 3–4 mice in each group).

Fig 5: Polymerase I and transcript release factor (PTRF) controls IL-33 subcellular location. (A) Representative images of IL-33 (red) and PTRF (green) immunofluorescence of wide type PTRF or PTRF truncation 121-392 transfected HBE with or without LPS (1 ng/µl) treatment. (B) IL-33 levels in culture supernatants from wide type PTRF or PTRF truncation 121-392 transfected HBE with or without LPS (1 ng/µl) treatment.