Inhibition of neuronal necroptosis mediated by RIP1/RIP3/MLKL provides neuroprotective effects on kaolin-induced hydrocephalus in mice

Metabolic Pathways in Hydrocephalus: Profiling with Proteomics and Advanced Imaging

Hemorrhagic hydrocephalus is a common pathology in neonates with high mortality and morbidity. Current imaging approaches fail to capture the mechanisms behind its pathogenesis. Here, we discuss the processes underlying this pathology, the metabolic dysfunction that occurs as a result, and the ways in which these metabolic changes inform novel methods of clinical imaging. The imaging advances described allow earlier detection of the cellular and metabolic changes, leading to better outcomes for affected neonates.

Aurantiamide mitigates acute kidney injury by suppressing renal necroptosis and inflammation via GRPR-dependent mechanism

Acute kidney injury (AKI) manifests as a clinical syndrome characterised by the rapid accumulation of metabolic wastes, such as blood creatinine and urea nitrogen, leading to a sudden decline in renal function. Currently, there is a lack of specific therapeutic drugs for AKI. Previously, we identified gastrin-releasing peptide receptor (GRPR) as a pathogenic factor in AKI. In this study, we investigated the therapeutic potential of a novel Chinese medicine monomer, aurantiamide (AA), which exhibits structural similarities to our previously reported GRPR antagonist, RH-1402. We compared the therapeutic efficacy of AA with RH-1402 both in vitro and in vivo using various AKI models. Our results demonstrated that, in vitro, AA attenuated injury, necroptosis, and inflammatory responses in human renal tubular epithelial cells subjected to repeated hypoxia/reoxygenation and lipopolysaccharide stimulation. In vivo, AA ameliorated renal tubular injury and inflammation in mouse models of ischemia/reperfusion and cecum ligation puncture-induced AKI, surpassing the efficacy of RH-1402. Furthermore, molecular docking and cellular thermal shift assay confirmed GRPR as a direct target of AA, which was further validated in primary cells. Notably, in GRPR-silenced HK-2 cells and GRPR systemic knockout mice, AA failed to mitigate renal inflammation and injury, underscoring the importance of GRPR in AA's mechanism of action. In conclusion, our study has demonstrated that AA serve as a novel antagonist of GRPR and a promising clinical candidate for AKI treatment.

GSK'872 Improves Prognosis of Traumatic Brain Injury by Switching Receptor-Interacting Serine/Threonine-Protein Kinase 3-dependent Necroptosis to Cysteinyl Aspartate Specific Proteinase-8-Dependent Apoptosis

BACKGROUND

Traumatic brain injury (TBI) is an important health concern in the society. Previous studies have suggested that necroptosis occurs following TBI. However, the underlying mechanisms and roles of necroptosis are not well understood. In this study, we aimed to assess the role of receptor-interacting serine/threonine-protein kinase 3 (RIP3)-mediated necroptosis after TBI both in vitro and in vivo.

METHODS

We established a cell-stretching injury and mouse TBI model by applying a cell injury controller and controlled cortical impactor to evaluate the relationships among necroptosis, apotosis, inflammation, and TBI both in vitro and in vivo.

RESULTS

The results revealed that necroptosis mediated by RIP1, RIP3, and mixed lineage kinase domain-like protein was involved in secondary TBI. Additionally, protein kinase B (Akt), phosphorylated Akt, mammalian target of rapamycin (mTOR), and phosphorylated mTOR potentially contribute to necroptosis. The inhibition of RIP3 by GSK'872 (a specific inhibitor) blocked necroptosis and reduced the activity of Akt/mTOR, leading to the alleviation of inflammation by reducing the levels of NOD-, LRR- and pyrin domain-containing protein 3. Moreover, the inhibition of RIP3 by GSK'872 promoted the activity of cysteinyl aspartate specific proteinase-8, an enzyme involved in apoptosis and inflammation.

CONCLUSIONS

These data demonstrate that RIP3 inhibition could improve the prognosis of TBI, based on the attenuation of inflammation by switching RIP3-dependent necroptosis to cysteinyl aspartate specific proteinase-8-dependent apoptosis.

Insulin attenuates LPS-induced cognitive impairment and ferroptosis through regulation of glucose metabolism in hippocampus

AIMS

Neuroinflammation is a recognized contributor to cognitive disorders like Alzheimer's disease, with ferroptosis emerging as a novel mechanism underlying cognitive dysfunction associated with neuroinflammation. Insulin, pivotal in the central nervous system, holds promise for cognitive function enhancement. This study aimed to establish a cognitive impairment model through intracerebroventricular injection of lipopolysaccharide (LPS) and explore the impact of intracerebroventricular insulin injection on cognitive function in mice.

METHODS

We employed diverse experimental techniques, including animal behavior testing, molecular assays, targeted metabolomics, nuclear medicine, and electron microscopy, to assess neurodegenerative changes, brain insulin resistance (IR), glucose uptake and metabolism, and ferroptosis. The model of cognitive impairment was induced via intracerebroventricular injection of LPS, followed by intracerebroventricular administration of insulin to evaluate its effects.

RESULTS

Insulin treatment effectively mitigated LPS-induced cognitive decline and safeguarded against neuronal degeneration. Furthermore, insulin alleviated LPS-induced insulin resistance, enhanced glucose uptake in the hippocampus, and promoted the Pentose Phosphate Pathway (PPP) and nicotinamide adenine dinucleotide phosphate (NADPH) production. Additionally, insulin activated the glutathione (GSH)-glutathione peroxidase 4 (GPX4) pathway, reducing lipid peroxidation, and mitochondrial damage characteristic of LPS-induced ferroptosis in the hippocampus.

CONCLUSION

Our findings underscore the therapeutic potential of insulin in alleviating LPS-induced cognitive impairment and ferroptosis by modulating glucose metabolism. This study offers a promising avenue for future interventions targeting cognitive decline.

Necrostatin-1: a promising compound for neurological disorders

Necrostatin-1, a small molecular alkaloid, was identified as an inhibitor of necroptosis in 2005. Investigating the fundamental mechanism of Necrostatin-1 and its role in various diseases is of great significance for scientific and clinical research. Accumulating evidence suggests that Necrostatin-1 plays a crucial role in numerous neurological disorders. This review aims to provide a comprehensive overview of the potential functions of Necrostatin-1 in various neurological disorders, offering valuable insights for future research.

Targeting osteopontin alleviates endometriosis and inflammation by inhibiting the RhoA/ROS axis and achieves non-invasive in vitro detection via menstrual blood

STUDY QUESTION

How does osteopontin (OPN) in endometriosis ectopic stromal cells (EESCs) participate in the pathogenesis of endometriosis and achieve non-invasive detection in vitro?

SUMMARY ANSWER

Targeted OPN regulates endometriosis's necroptosis and inflammatory state by inhibiting the RhoA/reactive oxygen species (ROS) axis, thereby alleviating endometriosis and enabling non-invasive detection of menstrual blood in vitro.

WHAT IS KNOWN ALREADY

Endometriosis is a chronic inflammatory disease. Recent studies have shown that OPN plays an important role in disease progression by regulating cell death and inflammation.

STUDY DESIGN, SIZE, DURATION

The study included 20 patients diagnosed with endometriosis (confirmed by laparoscopy and histology) and 10 controls without endometriosis. Endometriotic stromal cells were isolated from endometrial samples, while menstrual blood endometrial cells (MESCs) were isolated from menstrual blood. These cells were then cultured in vitro and utilized in subsequent experiments.

PARTICIPANTS/MATERIALS, SETTING, METHODS

OPN expression in EESCs was assessed using inflammatory factor sequencing, immunohistochemical staining (IHC), quantitative real-time PCR (qRT-PCR) analysis, and Western blotting (WB). The biological behavior of OPN and its effects on inflammatory factors were examined using EdU, wound-healing, Transwell, and ELISA assays. Necroptosis in EESCs and its impact on inflammatory factors were detected through qRT-PCR, WB, and Calcein-AM/PI fluorescence assays. The examination of mitochondrial stress in EESCs involved the use of the Mitochondrial Membrane Potential (ΔΨm) Assay, ROS detection, and Calcein-AM Loading/cobalt chloride Quenching. qRT-PCR, WB, and other experiments were conducted to verify the regulation of necroptosis and inflammatory factor levels in EESCs by OPN through the RhoA/ROS axis. Knockdown of OPN and its inhibitory effect on endometriosis lesion size were confirmed using AAV9 virus, IHC, qRT-PCR, WB, and other experiments. Additionally, OPN expression in MESCs was detected using transcriptome sequencing, RT-PCR, WB, and other experiments.

MAIN RESULTS AND THE ROLE OF CHANCE

In vitro assays demonstrated a significant upregulation of OPN in EESCs, and the knockdown of OPN effectively inhibited necroptosis and the release of inflammatory factors. OPN inhibited necroptosis and inflammatory factor release by mediating RhoA-dependent ROS production and blocking mixed lineage kinase domain-like protein phosphorylation at the cell membrane. In vivo, targeting of OPN can inhibit the growth of endometriosis lesions. Clinically, OPN was also significantly upregulated in the menstrual blood of patients with endometriosis.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Due to limitations in obtaining surgical specimens, our study primarily involved collecting endometriosis tissues from women during the proliferative and secretory phases of the menstrual cycle. We observed a significant overexpression of OPN in the samples used for our investigation. However, the expression of OPN in endometriosis tissues during the intermenstrual phase remains unknown.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings highlight the pivotal role of the OPN/RhoA/ROS axis in the regulation of necroptosis and the release of inflammatory factors. OPN knockdown exerts a therapeutic effect in vivo, and the high expression detection of OPN in menstrual blood in vitro. In summary, targeting OPN provides possibilities for the treatment and detection of endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Natural Science Foundation of China (82071626), the Zhejiang Province Public Welfare Technology Application Research Project (LGF21H040010), and the Clinical Research project of the Second Affiliated Hospital of Wenzhou Medical University (1010293). The authors have no conflicts of interest.

HIST3H2A promotes the progression of prostate cancer through inhibiting cell necroptosis

In recent years, there has been an increase in the incidence and mortality rates of prostate cancer (PCa). However, the specific molecular mechanisms underlying its occurrence and development remain unclear, necessitating the identification of new therapeutic targets. Through bioinformatics analysis, we discovered a previously unstudied differential gene called HIST3H2A in prostate cancer. Our study revealed that HIST3H2A is highly expressed in PCa tissues, as confirmed by analysis of both the GEO and UALCAN databases. Further analysis using the KEGG database demonstrated that HIST3H2A regulates the pathway of programmed necroptosis in cells. Additionally, we observed significant up-regulation of HIST3H2A in PCa tissues and cell lines. HIST3H2A was found to regulate cell proliferation, migration, invasion, and the epithelial-mesenchymal transition (EMT) process in tumors. Notably, HIST3H2A's role in regulating programmed necroptosis in prostate cancer cells differs from its role in apoptosis. In vitro and in vivo experiments collectively support the key role of HIST3H2A in promoting the development of prostate cancer, highlighting its potential as a therapeutic target for patients with PCa.

RIPK3 signaling and its role in regulated cell death and diseases

Receptor-interacting protein kinase 3 (RIPK3), a member of the receptor-interacting protein kinase (RIPK) family with serine/threonine protein kinase activity, interacts with RIPK1 to generate necrosomes, which trigger caspase-independent programmed necrosis. As a vital component of necrosomes, RIPK3 plays an indispensable role in necroptosis, which is crucial for human life and health. In addition, RIPK3 participates in the pathological process of several infections, aseptic inflammatory diseases, and tumors (including tumor-promoting and -suppressive activities) by regulating autophagy, cell proliferation, and the metabolism and production of chemokines/cytokines. This review summarizes the recent research progress of the regulators of the RIPK3 signaling pathway and discusses the potential role of RIPK3/necroptosis in the aetiopathogenesis of various diseases. An in-depth understanding of the mechanisms and functions of RIPK3 may facilitate the development of novel therapeutic strategies.

RIP3 in Necroptosis: Underlying Contributions to Traumatic Brain Injury

Traumatic brain injury (TBI) is a global public safety issue that poses a threat to death, characterized by high fatality rates, severe injuries and low recovery rates. There is growing evidence that necroptosis regulates the pathophysiological processes of a variety of diseases, particularly those affecting the central nervous system. Thus, moderate necroptosis inhibition may be helpful in the management of TBI. Receptor-interacting protein kinase (RIP) 3 is a key mediator in the necroptosis, and its absence helps restore the microenvironment at the injured site and improve cognitive impairment after TBI. In this report, we review different domains of RIP3, multiple analyses of necroptosis, and associations between necroptosis and TBI, RIP3, RIP1, and mixed lineage kinase domain-like. Next, we elucidate the potential involvement of RIP3 in TBI and highlight how RIP3 deficiency enhances neuronal function.

ChemR23 activation attenuates cognitive impairment in chronic cerebral hypoperfusion by inhibiting NLRP3 inflammasome-induced neuronal pyroptosis

Neuroinflammation plays critical roles in vascular dementia (VaD), the second leading cause of dementia, which can be induced by chronic cerebral hypoperfusion (CCH). NLRP3 inflammasome-induced pyroptosis, the inflammatory programmed cell death, has been reported to contribute to the development of VaD. ChemR23 is a G protein-coupled receptor that has emerging roles in regulating inflammation. However, the role of ChemR23 signalling in NLRP3 inflammasome-induced pyroptosis in CCH remains elusive. In this study, a CCH rat model was established by permanent bilateral common carotid artery occlusion (BCCAO) surgery. Eight weeks after the surgery, the rats were intraperitoneally injected with the ChemR23 agonist Resolvin E1 (RvE1) or chemerin-9 (C-9). Additionally, primary rat hippocampal neurons and SH-SY5Y cells were adopted to mimic CCH injury in vitro. Our results showed that the levels of ChemR23 expression were decreased from the 8th week after BCCAO, accompanied by significant cognitive impairment. Further analysis revealed that CCH induced neuronal damage, synaptic injury and NLRP3-related pyroptosis activation in hippocampal neurons. However, pharmacologic activation of ChemR23 with RvE1 or C-9 counteracted these changes. In vitro experiments also showed that ChemR23 activation prevented primary neuron pyroptosis induced by chronic hypoxia. In addition, manipulating ChemR23 expression markedly regulated NLRP3 inflammasome-induced neuronal pyroptosis through PI3K/AKT/Nrf2 signalling in SH-SY5Y cells under hypoglycaemic and hypoxic conditions. Collectively, our data demonstrated that ChemR23 activation inhibits NLRP3 inflammasome-induced neuronal pyroptosis and improves cognitive function via the PI3K/AKT/Nrf2 signalling pathway in CCH models. ChemR23 may serve as a potential novel therapeutic target to treat CCH-induced cognitive impairment.

Necroptosis in CNS diseases: Focus on astrocytes

In the last few years, necroptosis, a recently described type of cell death, has been reported to play an important role in the development of various brain pathologies. Necroptosis is a cell death mechanism that has morphological characteristics similar to necrosis but is mediated by fundamentally different molecular pathways. Necroptosis is initiated by signaling through the interaction of RIP1/RIP3/MLKL proteins (receptor-interacting protein kinase 1/receptor-interacting protein kinase 3/mixed lineage kinase domain-like protein). RIPK1 kinase is usually inactive under physiological conditions. It is activated by stimulation of death receptors (TNFR1, TNFR2, TLR3, and 4, Fas-ligand) by external signals. Phosphorylation of RIPK1 results in the formation of its complex with death receptors. Further, complexes with the second member of the RIP3 and MLKL cascade appear, and the necroptosome is formed. There is enough evidence that necroptosis plays an important role in the pathogenesis of brain ischemia and neurodegenerative diseases. In recent years, a point of view that both neurons and glial cells can play a key role in the development of the central nervous system (CNS) pathologies finds more and more confirmation. Astrocytes play complex roles during neurodegeneration and ischemic brain damage initiating both impair and protective processes. However, the cellular and molecular mechanisms that induce pathogenic activity of astrocytes remain veiled. In this review, we consider these processes in terms of the initiation of necroptosis. On the other hand, it is important to remember that like other types of programmed cell death, necroptosis plays an important role for the organism, as it induces a strong immune response and is involved in the control of cancerogenesis. In this review, we provide an overview of the complex role of necroptosis as an important pathogenetic component of neuronal and astrocyte death in neurodegenerative diseases, epileptogenesis, and ischemic brain damage.

Nanowired Delivery of Cerebrolysin with Mesenchymal Stem Cells Attenuates Heat Stress-Induced Exacerbation of Neuropathology Following Brain Blast Injury

Blast brain injury (bBI) following explosive detonations in warfare is one of the prominent causes of multidimensional insults to the central nervous and other vital organs injury. Several military personnel suffered from bBI during the Middle East conflict at hot environment. The bBI largely occurs due to pressure waves, generation of heat together with release of shrapnel and gun powders explosion with penetrating and/or impact head trauma causing multiple brain damage. As a result, bBI-induced secondary injury causes breakdown of the blood-brain barrier (BBB) and edema formation that further results in neuronal, glial and axonal injuries. Previously, we reported endocrine imbalance and influence of diabetes on bBI-induced brain pathology that was significantly attenuated by nanowired delivery of cerebrolysin in model experiments. Cerebrolysin is a balanced composition of several neurotrophic factors, and active peptide fragment is capable of neuroprotection in several neurological insults. Exposure to heat stress alone causes BBB damage, edema formation and brain pathology. Thus, it is quite likely that hot environment further exacerbates the consequences of bBI. Thus, novel therapeutic strategies using nanodelivery of stem cell and cerebrolysin may further enhance superior neuroprotection in bBI at hot environment. Our observations are the first to show that combined nanowired delivery of mesenchymal stem cells (MSCs) and cerebrolysin significantly attenuated exacerbation of bBI in hot environment and induced superior neuroprotection, not reported earlier. The possible mechanisms of neuroprotection with MSCs and cerebrolysin in bBI are discussed in the light of current literature.

Role of spinal RIP3 in inflammatory pain and electroacupuncture-mediated analgesic effect in mice

AIMS

Electroacupuncture (EA) is a potentially useful treatment for inflammatory pain. Receptor-interacting protein 3 (RIP3) triggers the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome; activation independent of necroptosis has been reported. However, the role of RIP3 in inflammatory pain and its EA-induced analgesic effects remains unclear.

MAIN METHODS

Mice were treated with EA (2 Hz, 2 mA) after complete Freund's adjuvant (CFA) pain models were established. Inhibition or activation of spinal RIP3 was achieved by intrathecal administration of GSK-843 (a specific RIP3 inhibitor) or microinjection of lentivirus-RIP3, respectively. Mechanical analgesiometry and thermal analgesiometry were used to assess paw withdrawal threshold and paw withdrawal latency in mice. Quantitative polymerase chain reaction (qRT-PCR) and Western blotting were used to evaluate the expression of RIP3 and NLPR3 in spinal dorsal horn (SDH) of mice.

KEY FINDINGS

The expression of spinal RIP3 and NLPR3 increased significantly after CFA injection. Both intrathecal administration of GSK-843 and EA alleviated mechanical and thermal pain behaviors induced by CFA and inhibited the expression of RIP3 and NLRP3 in the SDH of CFA mice. Over-expression of RIP3 induces pain-like symptoms in mice and inhibits the regulatory effects of EA on inflammatory pain.

SIGNIFICANCE

Our results indicate that the EA analgesia effect may be related to suppression of RIP3 and NLRP3 expression in the SDH. This study could provide potential insights into the underlying spinal mechanisms involved in the analgesic effect of EA.

Necrostatin-1 attenuates Caspase-1-dependent pyroptosis induced by the RIPK1/ZBP1 pathway in ventilator-induced lung injury

BACKGROUND

Ventilator-induced lung injury (VILI) is a complex pathophysiological process leading to acute respiratory distress syndrome (ARDS) and poor outcomes in affected patients. As a form of programmed cell death, pyroptosis is proposed to play an important role in the development of ARDS. Here we investigated whether treating mice with the specific RIPK1 inhibitor Necrostatin-1 (Nec-1) before mechanical ventilation could inhibit pyroptosis and alleviate lung injury in a mouse model.

METHODOLOGYS

Anesthetized C57BL/6J mice received a transtracheal injection of Nec-1 (5 mg/kg) or vehicle (DMSO) 30 min before the experiment which was ventilated for up to 4 h. Lung damage was assessed macroscopically and histologically with oedema measured as the wet/dry ratio of lung tissues. The release of inflammatory mediators into bronchoalveolar lavage fluid (BALF) was assessed by ELISA measurements of TNF-α,interleukin-1β (IL-1β), and IL-6. The expression of RIPK1, ZBP1, caspase-1, and activated (cleaved) caspase-1 were analyzed using western blot and immunohistochemistry, and the levels of gasdermin-D (GSDMD) and IL-1β were analyzed by immunofluorescence staining.

RESULTS

High tidal ventilation produced time-dependent inflammation and lung injury in mice which could be significantly reduced by pretreatment with Nec-1. Notably, Nec-1 reduced the expression of key pyroptosis mediator proteins in lung tissues exposed to mechanical ventilation, including caspase-1, cleaved caspase-1, and GSDMD together with inhibiting the release of inflammatory cytokines.

CONCLUSION

Nec-1 pretreatment alleviates pulmonary inflammatory responses and protects the lung from mechanical ventilation damage. The beneficial effects were mediated at least in part by inhibiting caspase-1-dependent pyroptosis through the RIPK1/ZBP1 pathway.

Triclosan-induced neuroinflammation develops caspase-independent and TNF-α signaling pathway associated necroptosis in Neuro-2a cells

Triclosan (TCS) is widely used in cosmetics and healthcare industry as a broad-spectrum antibacterial agent. The lipophilic property and persistent nature of TCS has led to severe health issues. In the present study, we have evaluated the neuroinflammatory effect of TCS on mouse Neuro-2a cells. Initial investigation confirmed a dose-dependent loss in viability and morphology of cells in presence of TCS. The transcription and translation studies confirmed a downregulation in the expression of autophagy markers in Neuro-2a cells. The confocal microscopy study revealed that the abrogated autophagy in TCS-treated cells occurred due to loss in the autophagy flux and prevention in the lipidation of autophagosome bilayer. The fluorescence microscopy also confirmed a loss in the formation of autophagolysosomes in neuronal cells with increasing TCS concentrations. TCS treatment resulted in loss of mitochondrial integrity in cells as evidenced by a decrease in mitochondrial membrane potential in JC-1 staining. Further, the transcriptional and translational studies confirmed the activation of TNF-α signaling pathway in TCS-treated cells thus enhancing the expression of RIPK1, RIPK3 and MLKL proteins and their phosphorylated forms. TCS was also found to increase the tau protein pathogenesis in Neuro-2a cells, which alludes to the development of tau-associated neurodegeneration. Altogether, this study confirms the neuroinflammatory actions of TCS in Neuro-2a cells involving a TNF-α-induced MLKL-mediated signaling.

Hydrogen-rich saline alleviates early brain injury through inhibition of necroptosis and neuroinflammation via the ROS/HO-1 signaling pathway after traumatic brain injury

Traumatic brain injury (TBI) has been recognized as a serious public health issue and a key contributor to disability and death, with a huge economic burden worldwide. Hydrogen, which is a slight and specific cytotoxic oxygen radical scavenger, has been demonstrated to ameliorate early brain injury (EBI) through reactive oxygen species (ROS), oxidative stress injury, apoptosis and necroptosis. Necroptosis refers to a type of programmed cell death process that has a vital function in neuronal cell death following TBI. The specific function of necroptosis in hydrogen-mediated neuroprotection after TBI, however, has yet to be determined. The present study aimed to examine the neuroprotective effects and possible molecular basis that underly hydrogen-rich saline in TBI-stimulated EBI by examining neural necroptosis in the C57BL/6 mouse model. The brain water content, neurological score, neuroinflammatory cytokines (NF-κΒ, TNF-α, IL-6 and IL-1β) and ROS were evaluated using flow cytometry. Malondialdehyde, superoxide dismutase (SOD) and glutathione (GSH) levels were evaluated using a biochemical kit. Receptor-interacting protein kinase (RIP)1, RIP3, Nrf2 and Heme oxygenase-1 (HO-1) were evaluated using western blotting. mRNA of Nrf2 and HO-1 were evaluated using quantitative PCR. Neuronal death was evaluated by TUNEL staining. The outcomes illustrated that hydrogen-rich saline treatment considerably enhanced the neurological score, increased neuronal survival, decreased the levels of serum MDA and brain ROS, increased the levels of serum GSH and SOD. In addition the protein expression levels of RIP1 and RIP3 and the cytokines NF-κB, TNF-α, IL-1β and IL-6 were downregulated compared with the TBI group, which demonstrated that hydrogen-rich saline-induced inhibition of necroptosis and neuroinflammation ameliorated neuronal death following TBI. The neuroprotective capacity of hydrogen-rich saline was demonstrated to be partly dependent on the ROS/heme oxygenase-1 signaling pathway. Taken together, the findings of the present study indicated that hydrogen-rich saline enhanced neurological outcomes in mice and minimized neuronal death by inducing protective effects against neural necroptosis as well as neuroinflammation.

Antidepressant Mechanism of Traditional Chinese Medicine Formula Xiaoyaosan in CUMS-Induced Depressed Mouse Model via RIPK1-RIPK3-MLKL Mediated Necroptosis Based on Network Pharmacology Analysis

Background: Depression is a stress-related disorder that seriously threatens people's physical and mental health. Xiaoyaosan is a classical traditional Chinese medicine formula, which has been used to treat mental depression since ancient times. More and more notice has been given to the relationship between the occurrence of necroptosis and the pathogenesis of mental disorders. Objective: The purpose of present study is to explore the potential mechanism of Xiaoyaosan for the treatment of depression using network pharmacology and experimental research, and identify the potential targets of necroptosis underlying the antidepressant mechanism of Xiaoyaosan. Methods: The mice model of depression was induced by chronic unpredictable mild stress (CUMS) for 6 weeks. Adult C57BL/6 mice were randomly divided into five groups, including control group, chronic unpredictable mild stress group, Xiaoyaosan treatment group, necrostatin-1 (Nec-1) group and solvent group. Drug intervention performed from 4^th to 6^th week of modeling. The mice in Xiaoyaosan treatment group received Xiaoyaosan by intragastric administration (0.254 g/kg/d), and mice in CUMS group received 0.5 ml physiological saline. Meanwhile, the mice in Nec-1 group were injected intraperitoneally (i.p.) with Nec-1 (10 mg/kg/d), and the equivalent volume of DMSO/PBS (8.3%) was injected into solvent group mice. The behavior tests such as sucrose preference test, forced swimming test and novelty-suppressed feeding test were measured to evaluate depressive-like behaviors of model mice. Then, the active ingredients in Xiaoyaosan and the related targets of depression and necroptosis were compiled through appropriate databases, while the "botanical drugs-active ingredients-target genes" network was constructed by network pharmacology analysis. The expressions of RIPK1, RIPK3, MLKL, p-MLKL were detected as critical target genes of necroptosis and the potential therapeutic target compounds of Xiaoyaosan. Furthermore, the levels of neuroinflammation and microglial activation of hippocampus were measured by detecting the expressions of IL-1β, Lipocalin-2 and IBA1, and the hematoxylin and eosin (H&E) stained was used to observe the morphology in hippocampus sections. Results: After 6-weeks of modeling, the behavioral data showed that mice in CUMS group and solvent group had obvious depressive-like behaviors, and the medication of Xiaoyaosan or Nec-1 could improve these behavioral changes. A total of 96 active ingredients in Xiaoyaosan which could regulate the 23 key target genes were selected from databases. Xiaoyaosan could alleviate the core target genes in necroptosis and improve the hippocampal function and neuroinflammation in depressed mice. Conclusion: The activation of necroptosis existed in the hippocampus of CUMS-induced mice, which was closely related to the pathogenesis of depression. The antidepressant mechanism of Xiaoyaosan included the regulation of multiple targets in necroptosis. It also suggested that necroptosis could be a new potential target for the treatment of depression.