HBCOC attenuates cerebral ischemia-reperfusion injury in mice by inhibiting the inflammatory response and autophagy via TREM-1/ERK/NF-κB.

Objective: Hemoglobin-based carbon monoxide carrier (HBCOC) can dissociate carbon monoxide and ameliorate organ damage by inhibiting inflammation and oxidative stress. In this study, we evaluated its effect on cerebral ischemia-reperfusion injury in mice and explored its potential mechanism.

Methods: A middle cerebral artery occlusion/reperfusion (MCAO/R) mouse model was established using the wire embolization method, and HBCOC or equivalent normal saline was administered via the tail vein during reperfusion. HE staining and TEM were used to observe the injury in the tissue. The levels of IL-1β, IL-6, TNF-α were detected by ELISA and RT-qPCR, meantime, western blotting were used to detect expressions of TREM-1, ERK, NF-κB,LC3 and P62.

Results: We found that the HBCOC treatment alleviated nerve injury and reduced the cerebral infarction area caused by ischemia-reperfusion, simultaneously lowered the expression of IL-1β, IL-6, and TNF-α in plasma and brain tissues. HBCOC suppressed the levels of LC3II, lysosomes, and autophagy in the brain, suggesting potent inhibition of autophagy. Mechanistic analysis indicated that the expression of TREM-1/ERK/NF-κB pathway-related proteins and mRNA was higher in the saline group than that in the HBCOC group. HBCOC combined with the targeting TREM-1 receptor inhibitors LP17 inhibited the expression of the TREM-1 protein, further reducing the release of inflammatory factors and autophagy, restoring nerve function and infarct area after reperfusion, and exerting an overall protective effect against cerebral reperfusion injury. In summary, our results indicated that HBCOC alleviated cerebral ischemia-reperfusion injury in mice and inhibited inflammation and autophagy via TREM-1.