Schallner et al. (2015) suggested that heme oxygenase-1 is the major enzyme responsible for clearing heme from the subarachnoid space following subarachnoid hemorrhage. Biliverdin is reduced to bilirubin by biliverdin reductase, which has been found also in brain tissue, where it appears to be co-expressed with heme oxygenase isoforms (Ewing et al., 1993; Maines, 2005). We hypothesize that these two enzymes may contribute to the development of the inflammatory response in the choroid plexus following subarachnoid hemorrhage described in our previous work (Solár et al., 2020a). This evidence concerns the gene HMOX1 and subarachnoid hemorrhage.