Normobaric hyperoxia therapy in acute ischemic stroke: A literature review.

Background: Ischemic stroke is one of the most severe cerebrovascular diseases that leads to disability and death and seriously endangers health and quality of life. Insufficient oxygen supply is a critical factor leading to ischemic brain injury. However, effective therapies for ischemic stroke are lacking. Oxygen therapy has been shown to increase oxygen supply to ischemic tissues and improve prognosis after cerebral ischemia/reperfusion. Normobaric hyperoxia (NBHO) has been shown to have neuroprotective effects during ischemic stroke and is considered an appropriate neuroprotective therapy for ischemic stroke. Evidence indicates that NBHO plays a neuroprotective role through different mechanisms in acute ischemic stroke. Recent studies have also reported that combinations with other drug therapies can enhance the efficacy of NBHO in ischemic stroke. Here, we aimed to provide a summary of the potential mechanisms underlying the use of NBHO in ischemic stroke and an overview of the benefits of NBHO in ischemic stroke. Methods: We screened 83 articles on PubMed and other websites. A quick review was conducted, including clinical trials, animal trials, and reviews of studies in the field of NBHO treatment published before July 1, 2023. The results were described and synthesized, and the bias risk and evidence quality of all included studies were assessed. Results: The results were divided into four categories: the mechanism of NBHO, animal and clinical trials of NBHO, the clinical application and prospects of NBHO, and adverse reactions of NBHO. Conclusion: NBHO is a simple, non-invasive therapy that may be delivered early after stroke onset, with promising potential for the treatment of acute ischemic stroke. However, the optimal therapeutic regimen remains uncertain. Further studies are needed to confirm its efficacy and safety.

IL­4 alleviates CIRI by suppressing autophagy via the HIF­1α/Bcl­2/BNIP3 pathway in rats.

This paper was designed for delving into the mechanism adopted by interleukin­4 (IL­4) to relieve cerebral ischemia­reperfusion injury (CIRI) in rats via suppressing autophagy. Herein, rats stochastically fell into sham operation (sham), model (RI), model + IL­4 intervention (IL­4), model + HIF­1α inhibitor (2­methoxyestradiol, 2ME2) and model + IL­4 + 2ME2 (IL­4 + 2ME2) groups. Next, western blotting was utilized to examine the protein expressions of microtubule­associated protein 1 light chain 3 (LC3), p62, hypoxia­inducible factor 1­alpha (HIF­1α) and Bcl­2/adenovirus E1B 19 kDa­interacting protein 3 (BNIP3). Relative to RI group, IL­4 group had a significantly lower neurological impairment scale (NIS) score and an overtly lower apoptosis rate of neurons as well as a strikingly smaller cerebral infarction volume and number of autophagosomes (P<0.05). The LC3II/LC3I ratio and HIF­1α and BNIP3 protein expressions dropped, but p62 protein expression rose pronouncedly in IL­4 group (P<0.05). In contrast to those in RI group, the NIS score, neuronal apoptosis rate, cerebral infarction volume and autophagosome number were strikingly reduced (P<0.05). The NIS score, cerebral infarction volume, neuronal apoptosis rate, autophagosome number, LC3II/LC3I ratio and protein expressions of HIF­1α and BNIP3 plummeted, while p62 protein expression sharply rose in IL­4 + 2ME2 group relative to those in IL­4 group (P<0.05). IL­4 suppresses cell autophagy by inhibiting the HIF­1α/BNIP3 pathway, thus relieving CIRI in rats.

The protective effects of EGCG was associated with HO-1 active and microglia pyroptosis inhibition in experimental intracerebral hemorrhage.

Intracerebral hemorrhage (ICH), which has high mortality and disability rate is associated with microglial pyroptosis and neuroinflammation, and the effective treatment methods are limited Epigallocatechin-3-gallate (EGCG) has been found to play a cytoprotective role by regulating the anti-inflammatory response to pyroptosis in other systemic diseases. However, the role of EGCG in microglial pyroptosis and neuroinflammation after ICH remains unclear. In this study, we investigated the effects of EGCG pretreatment on neuroinflammation-mediated neuronal pyroptosis and the underlying neuroprotective mechanisms in experimental ICH. EGCG pretreatment was found to remarkably improved neurobehavioral performance, and decreased the hematoma volume and cerebral edema in mice. We found that EGCG pretreatment attenuated the release of hemin-induced inflammatory cytokines (IL-1ß, IL-18, and TNF-α). EGCG significantly upregulated the expression of heme oxygenase-1 (HO-1), and downregulated the levels of pyroptotic molecules and inflammatory cytokines including Caspase-1, GSDMD, NLRP3, mature IL-1ß, and IL-18. EGCG pretreatment also decreased the number of Caspase-1-positive microglia and GSDMD along with NLRP3-positive microglia after ICH. Conversely, an HO-1-specific inhibitor (ZnPP), significantly inhibited the anti-pyroptosis and anti-neuroinflammation effects of EGCG. Therefore, EGCG pretreatment alleviated microglial pyroptosis and neuroinflammation, at least in part through the Caspase-1/GSDMD/NLRP3 pathway by upregulating HO-1 expression after ICH. In addition, EGCG pretreatment promoted the polarization of microglia from the M1 phenotype to M2 phenotype after ICH. The results suggest that EGCG is a potential agent to attenuate neuroinflammation via its anti-pyroptosis effect after ICH.