Vitamin A and its active metabolite retinoic acid (RA) are essential for lung formation, though it is not clear if prenatal vitamin A deficiency influences postnatal lung development and function. In this episode, Wellington Cardoso provides evidence that prenatal disruption of RA signaling results in aberrant, overly differentiated smooth muscle in airways. RA deficiency-associated defects persisted, regardless of the adult vitamin A status, and manifested in airway hyperresponsiveness and structural changes in the bronchial smooth muscle. The study indicates that RA signaling in the developing lung prevents excessive smooth muscle formation.
There is increasing evidence that vitamin A deficiency in utero correlates with abnormal airway smooth muscle (SM) function in postnatal life. The bioactive vitamin A metabolite retinoic acid (RA) is essential for formation of the lung primordium; however, little is known about the impact of early fetal RA deficiency on postnatal lung structure and function. Here, we provide evidence that during murine lung development, endogenous RA has a key role in restricting the airway SM differentiation program during airway formation. Using murine models of pharmacological, genetic, and dietary vitamin A/RA deficiency, we found that disruption of RA signaling during embryonic development consistently resulted in an altered airway SM phenotype with markedly increased expression of SM markers. The aberrant phenotype persisted postnatally regardless of the adult vitamin A status and manifested as structural changes in the bronchial SM and hyperresponsiveness of the airway without evidence of inflammation. Our data reveal a role for endogenous RA signaling in restricting SM differentiation and preventing precocious and excessive SM differentiation when airways are forming.
Felicia Chen, Hector Marquez, Youn-Kyung Kim, Jun Qian, Fengzhi Shao, Alan Fine, William W. Cruikshank, Loredana Quadro, Wellington V. Cardoso