Negative regulation of human IL-33 in endothelium during allergic airway inflammation
Maile K. Hollinger, Chanie L. Howard, Donna C. Decker, Kelly M. Blaine, Ivy Aneas, Emily M. Grayson, Tania E. Velez, Fernando A. Oliveira, Riley T. Hannan, Daniel F. Camacho, Philip A. Verhoef, Cara L. Hrusch, Rebecca S. Griffes, Jeffrey M. Sturek, Marcelo A. Nobrega, Nathan Schoettler, Anne I. Sperling
Maile K. Hollinger, Chanie L. Howard, Donna C. Decker, Kelly M. Blaine, Ivy Aneas, Emily M. Grayson, Tania E. Velez, Fernando A. Oliveira, Riley T. Hannan, Daniel F. Camacho, Philip A. Verhoef, Cara L. Hrusch, Rebecca S. Griffes, Jeffrey M. Sturek, Marcelo A. Nobrega, Nathan Schoettler, Anne I. Sperling
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Research Article Immunology Vascular biology

Negative regulation of human IL-33 in endothelium during allergic airway inflammation

Abstract

Lung IL-33 is involved in pathogen defense, barrier homeostasis, and development of allergic responses. We previously identified a 5 kb noncoding region within a GWAS-defined segment that regulates expression of human IL33 (hIL33) but is absent in the murine locus. To understand how this region affects IL-33 expression in vivo, we engineered 2 BAC-transgenic strains in which 166 kb of the human genome upstream of the hIL33 locus, along with a fluorescent reporter, was inserted into the murine genome, both with and without the 5 kb region. Comparison to a murine Il33 (mIl33) reporter strain revealed species-specific tropism; hIL33 reporter was mostly expressed in the endothelium, while mIl33 reporter was expressed in type 2 alveolar epithelium. hIL33 reporter expression in tracheal basal epithelium, submucosal glands, and lung microvasculature required the 5 kb region. Surprisingly, allergen and exogenous IL-33 downregulated hIL33 reporter in lung endothelium only when the 5 kb region was present. Similar IL-33–dependent downregulation of IL33 transcripts was observed in human endothelial cell lines, validating that our hIL33 reporter strain recapitulated human endothelial biology. Together, these data reveal the importance of the asthma-associated human 5 kb region in regulating human IL33 expression in a cell type– and context-dependent manner.

Authors

Maile K. Hollinger, Chanie L. Howard, Donna C. Decker, Kelly M. Blaine, Ivy Aneas, Emily M. Grayson, Tania E. Velez, Fernando A. Oliveira, Riley T. Hannan, Daniel F. Camacho, Philip A. Verhoef, Cara L. Hrusch, Rebecca S. Griffes, Jeffrey M. Sturek, Marcelo A. Nobrega, Nathan Schoettler, Anne I. Sperling

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Figure 3

hIL33 reporter is downregulated in the lung following intratracheal administration of house dust mite (HDM) extract.

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hIL33 reporter is downregulated in the lung following intratracheal adm...
(A) Schematic describing HDM extract treatment in hIL33CrimBAC (BAC+) mice. Mice received 50 μg HDM extract on day 0 and 25 μg HDM extract on days 7–10. Control mice received 50 μL PBS at days 0 and 7–10. (B) Confocal microscopy of lungs from hIL33CrimBAC mice treated with PBS (left) or HDM (right). (C) Confocal microscopy of lungs from mIL33GFP mice treated as in A. Scale bars: 100 μm. (D) Percentage of LECs, VECs, and fibroblasts expressing Crimson in hIL33CrimBAC mice treated as in A. (E) Percentage of LECs, VECs, and fibroblasts expressing mIL33-GFP in mIL33GFP mice treated as in A. (F) Percentage of LECs, VECs, and fibroblasts expressing Crimson in hIL33CrimBAC5KbDel mice treated as in A. Data from D are from 2 independent experiments, with n ≥ 3 mice per group. Data from E depict a single representative experiment (of 2 experiments) with n ≥ 3 mice per group. Data from F depict a single experiment with n ≥ 4 mice per group. Quantifications in D–F are represented as mean ± first and third quartile. *P < 0.05; **P < 0.01 by unpaired t test. Scale bars: 500 μm.