Notably, HO-1 upregulation was also observed in the CD11b+ cells isolated from the ipsilateral hemisphere of IRG1−/− MCAO mice compared to those isolated from the contralateral hemisphere of IRG1−/− MCAO mice, indicating IRG1-independent mechanism of inducing HO-1 expression exists in MG after ischaemic strokes, such as the direct activation of Nrf2/HO-1 pathway by ischaemia-induced oxidative stress. Here, HMOX1 is linked to ischemic stroke.