Accumulating evidence demonstrates that ferroptosis may be important in the pathophysiological process of traumatic brain injury (TBI). As a major hormone of the pineal gland, melatonin exerts many beneficial effects on TBI, but there is no information regarding the effects of melatonin on ferroptosis after TBI. As expected, TBI resulted in the time‐course changes of ferroptosis‐related molecules expression and iron accumulation in the ipsilateral cortex. Importantly, we found that treating with melatonin potently rescued TBI induced the changes mentioned above and improved functional deficits versus vehicle. Similar results were obtained with a ferroptosis inhibitor, liproxstatin‐1. Moreover, the protective effect of melatonin is likely dependent on melatonin receptor 1B (MT2). Although ferritin plays a vital role in iron metabolism by storing excess cellular iron, its precise function in the brain, and whether it involves melatonin's neuroprotection remain unexplored. Considering ferritin H (Fth) is expressed predominantly in the neurons and global loss of Fth in mice induces early embryonic lethality, we then generated neuron‐specific Fth conditional knockout (Fth‐KO) mice, which are viable and fertile but have altered iron metabolism. In addition, Fth‐KO mice were more susceptible to ferroptosis after TBI, and the neuroprotection by melatonin was largely abolished in Fth‐KO mice. In vitro siFth experiments further confirmed the results mentioned above. Taken together, these data indicate that melatonin produces cerebroprotection, at least partly by inhibiting neuronal Fth‐mediated ferroptosis following TBI, supporting the notion that melatonin is an excellent ferroptosis inhibitor and its anti‐ferroptosis provides a potential therapeutic target for treating TBI.

No abstract

Interleukin-33 (IL-33) is a recently identified member of the IL-1 family that exerts biologic functions by binding to a heterodimer composed of IL-1 receptor-related protein ST2L and IL-1RAcP. However, the role of IL-33 and whether IL-33 accounts for inflammation, apoptotic, and autophagic neuropathology after intracerebral hemorrhage (ICH) are not clear. Here, we established a mouse ICH model in this study, to determine the role of IL-33 and explore the underlying mechanism. Male mice were subjected to an infusion of type IV collagenase/saline into the left striatum to induce ICH/sham model. IL-33, soluble ST2 (sST2), or saline were also administered by a single intracerebroventricular (i.c.v.) injection, respectively. The results showed that the expression level of IL-33 markedly decreased within 6 h and reached the valleys at 6 and 72 h after ICH vs. sham group. In parallel, ST2L (a transmembrane form receptor of IL-33) significantly increased within 6 h and reached the peaks at 6 h and 24 h after ICH vs. sham group. In addition, administration of IL-33 alleviated cerebral water contents, reduced the number of PI- and TUNEL-positive cells, and improved neurological function after ICH. Moreover, IL-33 treatment apparently suppressed the expression of pro-inflammation cytokines IL-1β and TNF-α, evidently increased Bcl-2 but decreased cleaved-caspase-3, and obviously decreased the levels of autophagy-associated proteins LC3-II and Beclin-1 but maintained P62 at high level after ICH. On the contrary, treatment with sST2, a decoy receptor of IL-33, exacerbated ICH-induced brain damage and neurological dysfunction by promoting apoptosis, and enhancing autophagic activity. In conclusion, IL-33 provides neuroprotection through suppressing inflammation, apoptotic, and autophagic activation in collagenase-induced ICH model.

Blood-brain barrier (BBB) disruption and brain edema formation play important roles in the secondary neuronal death and neurological dysfunction induced by intracerebral hemorrhage (ICH). Poloxamer 188 (P188), a multiblock copolymer surfactant, has been shown to be capable of sealing damaged cell membranes and decrease neuronal cell death. In this study, we explored whether P188 had a protective effect against ICH and its underlying mechanisms. Male ICR mice were subjected to infusion of type IV collagenase (to induce ICH) of saline (for shams) into the left striatum. The results showed that P188-12 mg post-treatment by tail intravenous injection significantly ameliorated the neurological symptoms and brain edema, attenuated BBB permeability, and decreased cell insults and injury volume at 24 and 72 h after ICH. Furthermore, P188 maintained the protein levels of tight junction (TJ) proteins including claudin-5, occludin, and zonula occludens-1, and reversed the increases of nuclear factor-kappaB (NF-κB), matrix metalloproteinase (MMP)-2, and MMP-9 protein expression at 72 h post ICH. Immunofluorescence showed P188 treatment rearranged the structure of TJ proteins in a continuous and linear pattern. Therefore, the present study concludes that P188 can protect against ICH, and the protective effect was associated with preventing BBB disruption through NF-κB-MMPs-mediated TJ proteins degradation.

Necroptosis was recently discovered as one form of programmed cell death (PCD) and could be specifically inhibited by necrostatin-1. The aim of this study was to examine the effect of necrostatin-1 on brain injury and investigate the role of necrostatin-1 on the other two types PCD (apoptosis and autophagic cell death) in a mouse intracerebral hemorrhage (ICH) model. Male ICR mice received an infusion of type IV collagenase to induce ICH or saline as control into the left striatum. In the presence of vehicle, 3-MA, zVAD, and necrostatin-1 were pretreated with a single intracerebroventricular (i.c.v.) injection in the ipsilateral ventricle 15 min before ICH, respectively. Compared with vehicle groups, necrostatin-1 treatment significantly reduced injury volume and propidium iodide-positive cells at 24 and 72 h after ICH. Immunoblotting analysis showed that necrostatin-1 treatment suppressed autophagic-associated proteins (LC3-II, Beclin-1) and maintained p62 at normal level at 24 and 72 h after ICH. In addition, necrostatin-1 treatment enhanced the protein level of Bcl-2 and decreased the protein level of cleaved caspase-3 and the Beclin-1/Bcl-2 ratio at 24 and 72 h after ICH. Moreover, both 3-MA and necrostatin-1 treatment could suppress cleaved caspase-3 and LC3-II production, whereas zVAD treatment could inhibit caspase-3 cleavage but increased LC3-II protein levels at 72 h after ICH. Taken together, the data demonstrated for the first time that the specific inhibitor necrostatin-1 suppressed apoptosis and autophagy to exert these neuroprotective effects after ICH and that there existed a cross-talk among necroptosis, apoptosis, and autophagy after ICH.