HMOX1 and Alzheimer disease: The rationale to explain HO-1 induction in AD is related to the neuroprotective features of this early gene/protein whose ability to prevent heme toxicity, enhanced during excessive free radical generation, and to release the antinflammatory gaseous molecule CO (Nitti et al., 2018), make this enzyme a pivotal player in the cell stress response (Mancuso et al., 2013; Motterlini and Foresti, 2017).