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Calcium‐Sensing Receptor (CaSR) Modulates Hyperoxia‐Induced Airway Hyperreactivity In a Neonatal Mouse Model of Bronchopulmonary Dysplasia
Author(s) -
Sopi Ramadan B.,
Mayer Catherine A.,
Martin Richard J.,
Pabelick Christina B.,
Prakash Y. S.,
MacFarlane Peter M.
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.06672
Subject(s) - hyperoxia , methacholine , bronchopulmonary dysplasia , medicine , calcium sensing receptor , endocrinology , lung , receptor , pathophysiology , antagonist , downregulation and upregulation , bronchoconstriction , calcium , asthma , chemistry , calcium metabolism , respiratory disease , biology , gestational age , pregnancy , genetics , biochemistry , gene
Supplemental O 2 is a primary mode of respiratory therapy for preterm infants. Numerous studies, however, have shown that supplemental O 2 may contribute to the pathophysiology of airway hyperreactivity (AHR) associated with wheezing disorders such as asthma later in childhood. The calcium‐sensitive receptor (CaSR) is a potent modulator of smooth muscle contractility and may be an underlying feature of childhood asthma. In the present study, we investigated whether CaSR is involved in neonatal hyperoxia induced AHR in a mouse model of BPD. We hypothesize that inhibition (CaSR antagonism), downregulation of expression (siRNA), or deletion (CaSR KO mice) of CaSR will attenuate the AHR induced by hyperoxia in neonatal mice. Newborn C57BL/6 wild‐type (background) or CaSR −/− (knockout) mice were randomized on the second day of life and assigned to room air (21% O 2 ) or hyperoxic (40% O 2 ) groups and exposed for seven days, then recovered in room air for two additional weeks. At day P21, AHR was assessed in vitro using precision‐cut living lung slice preparations in response to increasing doses of methacholine (MCh, 0.25–8 μM). Wild‐type lung slices were pre‐incubated for 48 h in a CaSR siRNA sequence (40 nM) or scrambled RNA as a negative control. In another set of experiments, slices were pre‐incubated in a CaSR antagonist – NPS 2143 (10 nM) for 1 h. Airways were imaged and airway reactivity was expressed as percent change from baseline airway lumen area (± SEM). Neonatal hyperoxia significantly increased airway contractile responses to MCh in wild‐type mice with a mean maximal effect (Emax) of 68.4±8.7% decrease in airway lumen area compared to room air controls (47.3±5.8%, p<0.001), indicating AHR. Pre‐incubation (48hrs) with siRNA targeting CaSR or pharmacologic inhibition (NPS 2143, 1hr incubation) of CaSR reversed the hyperoxia‐induced AHR and the contractile responses were normalized to control level, with hyperoxic groups Emax of 44.0±5.2% and 41.3±3.1%, respectively. AHR was not observed in CaSR knockout mice suggesting resistance to hyperoxia exposure. These data suggest that CaSR plays an important role in the long‐term effects of neonatal hyperoxia on AHR. We speculate that CaSR may be a novel therapeutic target to reverse airway hyperreactivity in former preterm infants who had received prior supplemental O 2 therapy. Support or Funding Information Funding: NIH: HL R01 138402 and NIH R01 HL 056470