PTGDR2 and asthma: Despite prior data demonstrating upregulation of the CRTH2-PGD2 pathway in asthma20 and that targeting the CRTH2 receptor reduces type 2 inflammation in vitro16 17 and, to some degree, in vivo (reduction of sputum eosinophils, although no change in blood eosinophils or FeNO),41 in the current study the CRTH2 antagonist timapiprant did not attenuate the clinicopathological changes induced by RV infection in asthma.