Fra-1 induces apoptosis and neuroinflammation by targeting S100A8 to modulate TLR4 pathways in spinal cord ischemia/reperfusion injury

Tungsten-based polyoxometalate nanoclusters as ferroptosis inhibitors modulating S100A8/A9-mediated iron metabolism pathway for managing intracerebral haemorrhage

BACKGROUND

Intracerebral haemorrhage (ICH) is a devastating neurological disorder with high morbidity and mortality rates, largely owing to the lack of effective therapeutic strategies. Growing evidence has underscored the pivotal role of ferroptosis in intracerebral haemorrhage, and its contribution to neuronal death and exacerbation of brain injury, thus establishing it as a crucial target for therapeutic intervention. In recent years, polyoxometalate nanoclusters (NCs) have been applied in various neurodegenerative diseases, demonstrating neuroprotective effects. However, their impact on brain iron content and neurological function following ICH has yet to be reported. Here, we explored the potential of tungsten-based polyoxometalate (W-POM) NCs as ferroptosis inhibitors targeting the iron metabolic pathway mediated by S100A8/A9 for the treatment of ICH.

RESULTS

We successfully synthesized ultra-small reduced W-POM NCs that can rapidly cross the blood-brain barrier and are cleared through the kidney. In vitro experiments demonstrated that W-POM NCs exhibit significant and stable ROS scavenging activity while effectively alleviating iron overload and associated neuronal damage. In vivo, W-POM NCs treatment restored iron metabolism homeostasis, suppressed neuroinflammation and oxidative stress, ultimately alleviating severe neurological damage and motor deficits in ICH mice. Proteomic combined with bioinformatic analyses identified two core genes, S100A8 and S100A9, most associated with W-POM NCs intervention in ICH. Further experiments confirmed that W-POM NCs act by modulating the toll-like receptor 4/hepcidin/ferroportin signaling pathway, thereby regulating iron metabolism and reducing secondary brain injury.

CONCLUSIONS

This study pioneers the application of polyoxometalates in intracerebral haemorrhage, offering a novel and promising therapeutic approach for the management of ferroptosis-related brain injuries.

Aspergillus oryzae Fermented Plumula Nelumbinis Against Atopic Dermatitis Through AKT/mTOR and Jun Pathways

Background/Objectives: Atopic dermatitis (AD) is a chronic inflammatory skin disorder that has attracted global attention, and alkaloids from Plumula Nelumbinis have been shown to have anti-inflammatory activity. Fermentation has been used for the structural modification of natural compounds to improve bioavailability and activity, but the AD therapeutic efficacy and mechanism of the fermented Plumula Nelumbinis (FPN) are still unclear. Methods: The potential targets of FPN for AD were preliminarily screened using network pharmacology, and then PCR and WB were used to prove the therapeutic effect of FPN in AD. Results: Network pharmacology indicated that mTOR and Jun were key targets for AD. The experiments in vitro showed that FPN could effectively block AKT/mTOR and AKT/Jun-mediated inflammatory signaling pathways. Moreover, FPN can also alleviate SDS-induced inflammation in zebrafish. It is also found that the anti-inflammatory activity of Plumula Nelumbinis was enhanced by Aspergillus oryzae fermentation, and the oil phase of the fermentation product showed better activity, which may be due to microbial fermentation changing the structure of the original alkaloids. Conclusions: This study elucidated the potential mechanisms of alkaloids derived from fermented Plumula Nelumbinis against AD; it may also provide a scientific basis for the development of new drugs for AD.

S100A8 knockdown activates the PI3K/AKT signaling pathway to inhibit microglial autophagy and improve cognitive impairment mediated by chronic sleep deprivation

OBJECTIVE

Cognitive dysfunction is one of the major symptoms of chronic sleep deprivation (CSD). Abnormal autophagy and apoptosis are thought to be important mechanisms. S100 Calcium Binding Protein A8 (S100A8) plays a key role in autophagy and apoptosis of microglia. This study investigated whether S100A8 knockdown can effectively inhibit aberrant autophagy in microglia and improve cognitive function by activating the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway under CSD conditions.

METHODS

CSD mouse models and BV2 cell autophagy models were established in vivo and in vitro. Transcriptome sequencing was used to determine the key regulator related to autophagy. The Morris water maze test was used to evaluate the cognitive behavior of the mice. RT-qPCR and western blot were conducted to examine S100A8 expression and autophagy signalling. HE, TUNEL, transmission electron microscopy, immunofluorescence, and histochemistry were performed to detect pathological changes, neuronal autophagy, apoptosis, or positive cells in hippocampal tissues, respectively.

RESULTS

Transcriptome sequencing showed that S100A8 was significantly elevated in CSD mice, and fluorescence colocalization results further suggested that S100A8 mainly colocalizes with microglia. In vivo studies revealed that knockdown of S100A8 alleviated CSD-induced cognitive impairment in mice. Through further mechanistic investigations employing both in vivo and in vitro models, we demonstrated that silencing S100A8 can activate the PI3K/AKT pathway, thereby reducing CSD-induced abnormal autophagy and apoptosis in microglia. Aberrant autophagy and apoptosis in microglia were reversed with the PI3K/AKT pathway inhibitor LY294002.

CONCLUSION

The S100A8/PI3K/AKT axis plays a crucial role in chronic sleep deprivation-mediated autophagy and apoptosis in microglia.

Time varying characteristic in somatosensory evoked potentials as a biomarker of spinal cord ischemic-reperfusion injury in rat

Spinal cord ischemic-reperfusion injury (SCIRI) could occurs during surgical procedures without detection, presenting a complex course and an unfavorable prognosis. This may lead to postoperative sensory or motor dysfunction in areas innervated by the spinal cord, and in some cases, permanent paralysis. Timely detection of SCIRI and immediate waring can help surgeons implement remedial intervention to prevent irreversible spinal cord injury. Therefore, it is crucial to develop a precise and effective method for early detection of SCIRI. This study utilized rat models to simulate intraoperative SCIRI and employed somatosensory evoked potentials (SEP) for continuous monitoring during surgery. In this study, SEP signal changes were examined in six groups with varying severities of SCIRI and one normal control group. SEP signal changes were examined during operations in different groups and correlated with postoperative behavioral and histopathological data. The result demonstrated specific changes in SEP signals during SCIRI, termed as time-varying characteristics, which are associated with the duration of ischemia and subsequent reperfusion. Time-varying characteristics in SEP could potentially serve as a new biomarker for the intraoperative detection of SCIRI. This finding is significant for clinical surgeons to identify and guide early intervention of SCIRI timely. Additionally, this measurement is easily translatable to clinical application.

Quercetin, Main Active Ingredient of Moutan Cortex, Alleviates Chronic Orofacial Pain via Block of Voltage-Gated Sodium Channel

BACKGROUND

Chronic orofacial pain (COP) therapy is challenging, as current medical treatments are extremely lacking. Moutan Cortex (MC) is a traditional Chinese medicine herb widely used for chronic inflammatory diseases. However, the mechanism behind MC in COP therapy has not been well-established. The purpose of this study was to identify the active ingredients of MC and their specific underlying mechanisms in COP treatment.

METHODS

In this study, the main active ingredients and compound-target network of MC in COP therapy were identified through network pharmacology and bioinformatics analysis. Adult male Sprague-Dawley rats received oral mucosa lipopolysaccharide (LPS) injection to induce COP. Pain behaviors were evaluated by orofacial mechanical nociceptive assessment after intraganglionar injection. In vitro inflammatory cytokines in LPS-pretreated human periodontal ligament stem cells (hPDLSCs) and rat primary cultural trigeminal ganglion (TG) neurons were quantified by real-time quantitative polymerase chain reaction (RT-qPCR). Schrödinger software was used to verify the molecular docking of quercetin and critical targets. Whole-cell recording electrophysiology was used to evaluate the effect of quercetin on voltage-gated sodium (Na v ) channel in rat TG neurons.

RESULTS

The assembled compound-target network consisted of 4 compounds and 46 targets. As 1 of the active components of MC correlated with most related targets, quercetin alleviated mechanical allodynia in LPS-induced rat model of COP (mechanical allodynia threshold median [interquartile range (IQR) 0.5 hours after drug administration: vehicle 1.3 [0.6-2.0] g vs quercetin 7.0 [6.0-8.5] g, P = .002). Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that immune response and membrane functions play essential roles in MC-COP therapy. Five of the related targets were identified as core targets by protein-protein interaction analysis. Quercetin exerted an analgesic effect, possibly through blocking Na v channel in TG sensory neurons (peak current density median [IQR]: LPS -850.2 [-983.6 to -660.7] mV vs LPS + quercetin -589.6 [-711.0 to -147.8] mV, P = .006) while downregulating the expression level of proinflammatory cytokines-FOS (normalized messenger RNA [mRNA] level mean ± standard error of mean [SEM]: LPS [2. 22 ± 0.33] vs LPS + quercetin [1. 33 ± 0.14], P = .034) and TNF-α (normalized mRNA level mean ± SEM: LPS [8. 93 ± 0.78] vs LPS + quercetin [3. 77 ± 0.49], P < .0001).

CONCLUSIONS

Identifying Na v as the molecular target of quercetin clarifies the analgesic mechanism of MC, and provides ideas for the development of novel selective and efficient chronic pain relievers.

Blockade of the ADAM8-Fra-1 complex attenuates neuroinflammation by suppressing the Map3k4/MAPKs axis after spinal cord injury

BACKGROUND

Mechanical spinal cord injury (SCI) is a deteriorative neurological disorder, causing secondary neuroinflammation and neuropathy. ADAM8 is thought to be an extracellular metalloproteinase, which regulates proteolysis and cell adherence, but whether its intracellular region is involved in regulating neuroinflammation in microglia after SCI is unclear.

METHODS

Using animal tissue RNA-Seq and clinical blood sample examinations, we found that a specific up-regulation of ADAM8 in microglia was associated with inflammation after SCI. In vitro, microglia stimulated by HMGB1, the tail region of ADAM8, promoted microglial inflammation, migration and proliferation by directly interacting with ERKs and Fra-1 to promote activation, then further activated Map3k4/JNKs/p38. Using SCI mice, we used BK-1361, a specific inhibitor of ADAM8, to treat these mice.

RESULTS

The results showed that administration of BK-1361 attenuated the level of neuroinflammation and reduced microglial activation and recruitment by inhibiting the ADAM8/Fra-1 axis. Furthermore, treatment with BK-1361 alleviated glial scar formation, and also preserved myelin and axonal structures. The locomotor recovery of SCI mice treated with BK-1361 was therefore better than those without treatment.

CONCLUSIONS

Taken together, the results showed that ADAM8 was a critical molecule, which positively regulated neuroinflammatory development and secondary pathogenesis by promoting microglial activation and migration. Mechanically, ADAM8 formed a complex with ERK and Fra-1 to further activate the Map3k4/JNK/p38 axis in microglia. Inhibition of ADAM8 by treatment with BK-1361 decreased the levels of neuroinflammation, glial formation, and neurohistological loss, leading to favorable improvement in locomotor functional recovery in SCI mice.

Steroid inhibited Serpina3n expression which was positively correlated with the degrees of spinal cord injury

Aims

The aim of our project was to identify proteins associated with the extent of spinal cord injury (SCI) and subsequent long-term neurological recovery.

Methods

Through proteomic analysis, we identified proteins that are differentially expressed specifically in the acute phase of injury. We analyzed the concentrations of differentially expressed proteins in serum and the injured spinal cord segment by ELISA.

Results

Serpina3n protein expression in the injured spinal cord segment was increased 101-fold at 12 h after severe SCI and 89-fold at 12 h after mild SCI, as determined by LC‒MS/MS. In the mild and severe SCI groups, serum Serpina3n levels began to increase at 12 h and peaked at 24 h. At 12 h, 24 h and 3 d after injury, serum Serpina3n protein levels were significantly correlated with the severity of injury (12 h: r = 0.6034, P = 0.008; 24 h: r = 0.7542, P = 0.0003; 3 d: r = 0.862, P < 0.001). Serum Serpina3n levels at 2 h, 24 h and 3 d post injury were significantly correlated with long-term neurological recovery at 28 d after SCI (2 h: r = -0.5781, P = 0.012; 24 h: r = -0.5912, P = 0.0098; 3 d: r = -0.7792, P < 0.0001). Methylprednisolone treatment would decrease the serum Serpina3n levels in mice with mild and severe SCI compared with those in placebo-group mice at 12 h and 24 h after SCI. The serum Serpina3n concentration in the severe SCI group was significantly reduced on the third day after steroid treatment.

Conclusion

Taken together, these data suggest that serpina3n may be a circulating biomarker of acute SCI and may be closely associated with injury severity and long-term motor function recovery.

TAK-242, a toll-like receptor 4 antagonist, against brain injury by alleviates autophagy and inflammation in rats

Inhibition of Toll-like receptor 4 (TLR4)-mediated inflammatory pathways exerts a critical effect on neuronal death; therefore, it is a possible new therapeutic approach for traumatic brain injury (TBI). Resatorvid (TAK-242) is a novel small-molecule compound widely used to inhibit TLR4-mediated pathways, but the protective mechanism of TAK-242 in TBI remains unclear. Herein, we analyzed the neuroprotective effects of TAK-242 in rats after TBI. The rat model of brain injury was established using a modified Free-fall device, and the rats were injected with TAK-242 (0.5 mg/kg) through the caudal vein before TBI. The rats were allocated into four groups: a sham group, a TBI group, a TBI + vehicle group, and a TBI + TAK-242 group. The brain tissue was extracted for histology and determination of the expression of autophagy-related proteins and inflammatory mediators. TAK-242 pretreatment significantly reduced the damage to hippocampal neurons. Neuronal autophagy increased after brain injury, whereas TAK-242 significantly reduced autophagy marker protein LC3-II in the hippocampus. In addition, TAK-242 pretreatment significantly downregulated NF-κB p65, TNF-α, and IL-1β in the hippocampus. In conclusion, TAK-242 significantly reduced hippocampal neuronal damage by inhibiting autophagy and neuroinflammatory activity, possibly via the NF-κB signaling pathway.