Preoperative pain sensitivity and its correlation with postoperative acute and chronic pain: a systematic review and meta-analysis.

BACKGROUND: Preoperative pain sensitivity (PPS) can be associated with postsurgical pain. However, estimates of this association are scarce. Confirming this correlation is essential to identifying patients at high risk for severe postoperative pain and for developing analgesic strategy. This systematic review and meta-analysis summarises PPS and assessed its correlation with postoperative pain. METHODS: PubMed, Scopus, Cochrane Library, and PsycINFO were searched up to October 1, 2023, for studies reporting the association between PPS and postsurgical pain. Two authors abstracted estimates of the effect of each method independently. A random-effects model was used to combine data. Subgroup analyses were performed to investigate the effect of pain types and surgical procedures on outcomes. RESULTS: A total of 70 prospective observational studies were included. A meta-analysis of 50 studies was performed. Postoperative pain was negatively associated with pressure pain threshold (PPT; r=-0.15, 95% confidence interval [CI] -0.23 to -0.07]) and electrical pain threshold (EPT; r=-0.28, 95% CI -0.42 to -0.14), but positively correlated with temporal summation of pain (TSP; r=0.21, 95% CI 0.12-0.30) and Pain Sensitivity Questionnaire (PSQ; r=0.25, 95% CI 0.13-0.37). Subgroup analysis showed that only TSP was associated with acute and chronic postoperative pain, whereas PPT, EPT, and PSQ were only associated with acute pain. A multilevel (three-level) meta-analysis showed that PSQ was not associated with postoperative pain. CONCLUSIONS: Lower PPT and EPT, and higher TSP are associated with acute postoperative pain while only TSP is associated with chronic postoperative pain. Patients with abnormal preoperative pain sensitivity should be identified by clinicians to adopt early interventions for effective analgesia. SYSTEMATIC REVIEW PROTOCOL: PROSPERO (CRD42023465727).

Sympathetic Activation Promotes Cardiomyocyte Apoptosis in a Rabbit Susceptibility Model of Hyperthyroidism-Induced Atrial Fibrillation via the p38 MAPK Signaling Pathway.

Excess thyroid hormone secretion can cause endocrine metabolic disorders, which can lead to cardiovascular diseases, including heart enlargement, atrial fibrillation (AF), and heart failure. The present study investigated the molecular mechanisms of hyperthyroidism-induced AF. A rabbit susceptibility model of hyperthyroidism-induced AF was constructed, and metoprolol treatment was administered. Norepinephrine levels were determined using enzyme-linked immunosorbent assay; quantitative reverse transcription polymerase chain reaction and immunohistochemistry were used to detect the expression of markers for sympathetic remodeling (growth associated protein 43 and tyrosine hydroxylase in atrial myocardial tissues and stellate ganglia). Primary rabbit cardiomyocytes were cultured and identified by immunofluorescence staining, and terminal deoxynucleotidyl transferase dUTP nick end labeling staining was used to measure cardiomyocyte apoptosis; western blot was used to detect the expression of apoptosis-related proteins, including Bax, Bcl-2, and cleaved caspase-3, as well as to measure the phosphorylation states of p38 mitogen-activated protein kinase (MAPK) pathway proteins. Metoprolol inhibited sympathetic activation and cardiomyocyte apoptosis in the rabbit model by inhibiting the p38 MAPK signaling pathway. Immunofluorescence staining results revealed that the rabbit cardiomyocytes were isolated successfully. Inhibition of p38 MAPK signaling alleviated norepinephrine-induced apoptosis in cardiomyocytes. Sympathetic activation promotes apoptosis in cardiomyocytes with hyperthyroidism-induced AF via the p38 MAPK signaling pathway. The results of the present study provide a novel theoretical basis for the potential clinical treatment of patients with hyperthyroidism and AF.

ROS-Targeted Depression Therapy via BSA-Incubated Ceria Nanoclusters.

Depression is one of the most fatal mental diseases, and there is currently a lack of efficient drugs for the treatment of depression. Emerging evidence has indicated oxidative stress as a key pathological feature of depression. We targeted reactive oxygen species (ROS) and synthesized CeO2@BSA nanoclusters as a novel antidepression nanodrug via a convenient, green, and highly effective bovine serum albumin (BSA) incubation strategy. CeO2@BSA has ultrasmall size (2 nm) with outstanding ROS scavenging and blood-brain barrier crossing capacity, rapid metabolism, and negligible adverse effects in vitro and in vivo. CeO2@BSA administration alleviates depressive behaviors and depression-related pathological changes of the chronic restraint stress-induced depressive model, suggesting promising therapeutic effects of CeO2@BSA for the treatment of depression. Our study proved the validity by directly using nanodrugs as antidepression drugs instead of using them as a nanocarrier, which greatly expands the application of nanomaterials in depression treatment.

Mitochondrial dysfunction in microglia: a novel perspective for pathogenesis of Alzheimer's disease.

Alzheimer's disease (AD) is the most common neurodegenerative disease in the elderly globally. Emerging evidence has demonstrated microglia-driven neuroinflammation as a key contributor to the onset and progression of AD, however, the mechanisms that mediate neuroinflammation remain largely unknown. Recent studies have suggested mitochondrial dysfunction including mitochondrial DNA (mtDNA) damage, metabolic defects, and quality control (QC) disorders precedes microglial activation and subsequent neuroinflammation. Therefore, an in-depth understanding of the relationship between mitochondrial dysfunction and microglial activation in AD is important to unveil the pathogenesis of AD and develop effective approaches for early AD diagnosis and treatment. In this review, we summarized current progress in the roles of mtDNA, mitochondrial metabolism, mitochondrial QC changes in microglial activation in AD, and provide comprehensive thoughts for targeting microglial mitochondria as potential therapeutic strategies of AD.

Salidroside Attenuates Airway Inflammation and Remodeling via the miR-323-3p/SOCS5 Axis in Asthmatic Mice.

INTRODUCTION: Salidroside (Sal) a bioactive component extracted from Rhodiola rosea is remarkable for its anti-asthmatic effects. The study aimed to explore the molecular mechanism of Sal in airway inflammation and remodeling in asthmatic mice and provide a novel theoretical basis for asthma treatment. METHODS: An asthmatic mouse model was established via ovalbumin (OVA) treatment, followed by injection of Sal and transfection of miR-323-3p-mimic and sh- suppressor of cytokine signaling 5 (SOCS5). Expressions of miR-323-3p, SOCS5 mRNA, collagen (COL)-I, and COL-III were detected via reverse transcription quantitative polymerase chain reaction. SOCS5 protein level was detected via Western blot. Levels of IgE, IL-13, IL-4, and IL-5 were detected via enzyme-linked immunosorbent assay. Inflammatory cell infiltration was observed via hematoxylin-eosin staining. Collagen disposition was observed via Masson staining. Resistance index (RI) of airway hyperresponsiveness, and the number of total cells, inflammatory cells (eosinophil, macrophage, neutrophil, and lymphocyte) in bronchoalveolar lavage fluid (BALF) were observed. The binding relationship between miR-323-3p and SOCS5 was predicted through the RNA22 website and verified via dual-luciferase reporter assay. RESULTS: miR-323-3p was highly expressed in OVA-treated mice. Sal treatment reduced inflammatory cell infiltration, COL disposition, miR-323-3p expression, and IgE, IL-13, IL-4, IL-5, COL-I, and COL-III levels, RI value, and the number of total cells and inflammatory cells in BALF. miR-323-3p inhibited SOCS5 transcription. miR-323-3p overexpression or SOCS5 downregulation reversed the protecting role of Sal in asthmatic mice. CONCLUSION: Sal inhibited miR-323-3p expression to promote SOCS5 transcription, thereby attenuating airway inflammation and remodeling in asthmatic mice.

Microglial glutaminase 1 deficiency mitigates neuroinflammation associated depression.

Glutaminase 1 (GLS1) has recently been reported to be expressed in microglia and plays a crucial role in neuroinflamation. Significantly increased level of GLS1 mRNA expression together with neuroinflammation pathway were observed in postmortem prefrontal cortex from depressed patients. To find out the function of microglial GLS1 in depression and neuroinflammation, we generated transgenic mice (GLS1 cKO), postnatally losing GLS1 in microglia, to detect changes in the lipopolysaccharide (LPS)-induced depression model. LPS-induced anxiety/depression-like behavior was attenuated in GLS1 cKO mice, paralleled by a significant reduction in pro-inflammatory cytokines and an abnormal microglia morphological phenotype in the prefrontal cortex. Reduced neuroinflammation by GLS1 deficient microglia was a result of less reactive astrocytes, as GLS1 deficiency enhanced miR-666-3p and miR-7115-3p levels in extracellular vesicles released from microglia, thus suppressing astrocyte activation via inhibiting Serpina3n expression. Together, our data reveal a novel mechanism of GLS1 in neuroinflammation and targeting GLS1 in microglia may be a novel strategy to alleviate neuroinflammation-related depression and other disease.

Extracellular vesicles derived from glioblastoma promote proliferation and migration of neural progenitor cells via PI3K-Akt pathway.

BACKGROUND: Glioblastomas are lethal brain tumors under the current combinatorial therapeutic strategy that includes surgery, chemo- and radio-therapies. Extensive changes in the tumor microenvironment is a key reason for resistance to chemo- or radio-therapy and frequent tumor recurrences. Understanding the tumor-nontumor cell interaction in TME is critical for developing new therapy. Glioblastomas are known to recruit normal cells in their environs to sustain growth and encroachment into other regions. Neural progenitor cells (NPCs) have been noted to migrate towards the site of glioblastomas, however, the detailed mechanisms underlying glioblastoma-mediated NPCs' alteration remain unkown. METHODS: We collected EVs in the culture medium of three classic glioblastoma cell lines, U87 and A172 (male cell lines), and LN229 (female cell line). U87, A172, and LN229 were co-cultured with their corresponding EVs, respectively. Mouse NPCs (mNPCs) were co-cultured with glioblastoma-derived EVs. The proliferation and migration of tumor cells and mNPCs after EVs treatment were examined. Proteomic analysis and western blotting were utilized to identify the underlying mechanisms of glioblastoma-derived EVs-induced alterations in mNPCs. RESULTS: We first show that glioblastoma cell lines U87-, A172-, and LN229-derived EVs were essential for glioblastoma cell prolifeartion and migration. We then demonstrated that glioblastoma-derived EVs dramatically promoted NPC proliferation and migration. Mechanistic studies identify that glioblastoma-derived EVs achieve their functions via activating PI3K-Akt-mTOR pathway in mNPCs. Inhibiting PI3K-Akt pathway reversed the elevated prolfieration and migration of glioblastoma-derived EVs-treated mNPCs. CONCLUSION: Our findings demonstrate that EVs play a key role in intercellular communication in tumor microenvironment. Inhibition of the tumorgenic EVs-mediated PI3K-Akt-mTOR pathway activation might be a novel strategy to shed light on glioblastoma therapy. Video Abstract.

Insulin-incubated palladium clusters promote recovery after brain injury.

Traumatic brain injury (TBI) is a cause of disability and death worldwide, but there are currently no specific treatments for this condition. Release of excess reactive oxygen species (ROS) in the injured brain leads to a series of pathological changes; thus, eliminating ROS could be a potential therapeutic strategy. Herein, we synthesized insulin-incubated ultrasmall palladium (Pd@insulin) clusters via green biomimetic chemistry. The Pd@insulin clusters, which were 3.2 nm in diameter, exhibited marked multiple ROS-scavenging ability testified by the theoretical calculation. Pd@insulin could be rapidly excreted via kidney-urine metabolism and induce negligible adverse effects after a long-time treatment in vivo. In a TBI mouse model, intravenously injected Pd@insulin clusters aggregated in the injured cortex, effectively suppressed excessive ROS production, and significantly rescued motor function, cognition and spatial memory. We found that the positive therapeutic effects of the Pd@insulin clusters were mainly attributed to their ROS-scavenging ability, as they inhibited excessive neuroinflammation, reduced cell apoptosis, and prevented neuronal loss. Therefore, the ability of Pd@insulin clusters to effectively eliminate ROS, as well as their simple structure, easy synthesis, low toxicity, and rapid metabolism may facilitate their clinical translation for TBI treatment.

Emerging roles of extracellular vesicles in COVID-19, a double-edged sword?

The sudden outbreak of SARS-CoV-2-infected disease (COVID-19), initiated from Wuhan, China, has rapidly grown into a global pandemic. Emerging evidence has implicated extracellular vesicles (EVs), a key intercellular communicator, in the pathogenesis and treatment of COVID-19. In the pathogenesis of COVID-19, cells that express ACE2 and CD9 can transfer these viral receptors to other cells via EVs, making recipient cells more susceptible for SARS-CoV-2 infection. Once infected, cells release EVs packaged with viral particles that further facilitate viral spreading and immune evasion, aggravating COVID-19 and its complications. In contrast, EVs derived from stem cells, especially mesenchymal stromal/stem cells, alleviate severe inflammation (cytokine storm) and repair damaged lung cells in COVID-19 by delivery of anti-inflammatory molecules. These therapeutic beneficial EVs can also be engineered into drug delivery platforms or vaccines to fight against COVID-19. Therefore, EVs from diverse sources exhibit distinct effects in regulating viral infection, immune response, and tissue damage/repair, functioning as a double-edged sword in COVID-19. Here, we summarize the recent progress in understanding the pathological roles of EVs in COVID-19. A comprehensive discussion of the therapeutic effects/potentials of EVs is also provided.

Dual and opposing roles of the androgen receptor in VETC-dependent and invasion-dependent metastasis of hepatocellular carcinoma.

BACKGROUND & AIMS: Contradictory roles of the androgen receptor (AR) in hepatocellular carcinoma (HCC) metastasis have been reported. We have shown that VETC (vessels encapsulating tumor clusters) mediates invasion-independent metastasis, whereas VETC- HCCs metastasize in an invasion-dependent manner. Herein, we aimed to reveal the roles of AR in HCC metastasis. METHODS: Mouse xenograft models, clinical samples, and cell models were used. RESULTS: AR expression was significantly lower in HCCs with a VETC pattern, portal vein tumor thrombus, endothelium-coated microemboli or high recurrence rates. Overexpressing AR in VETC+ hepatoma cells suppressed VETC formation and intrahepatic metastasis but promoted pulmonary metastasis of mouse xenografts. AR decreased the transcription of Angiopoietin-2 (Angpt2), a factor essential for VETC formation, by binding to the Angpt2 promoter. The roles of AR in inhibiting VETC formation and intrahepatic metastasis were attenuated by restoring Angpt2 expression, suggesting that AR may repress VETC-dependent intrahepatic metastasis by inhibiting Angpt2 expression and VETC formation. On the other hand, AR upregulated Rac1 expression, promoted lamellipodia formation and increased cell migration/invasion. A Rac1 inhibitor abrogated the AR-mediated promotion of migration/invasion and pulmonary metastasis of VETC+ hepatoma cells, but did not affect the AR-mediated inhibition of intrahepatic metastasis. Furthermore, an AR inhibitor decreased Rac1 expression and attenuated both intrahepatic and pulmonary metastasis of VETC- xenografts, an effect which was abrogated by restoring Rac1 expression. These data indicate that AR may facilitate the lung metastasis of VETC+ HCCs and both the liver/lung metastases of VETC- HCCs by upregulating Rac1 expression and then promoting migration/invasion. CONCLUSION: AR plays dual and opposing roles in VETC-dependent and invasion-dependent metastasis, which highlights the complex functions of AR and the importance of individualized cancer therapy. LAY SUMMARY: In this study, we uncovered the dual and opposing roles of the androgen receptor in VETC (vessels encapsulating tumor clusters)-dependent and invasion-dependent metastasis of hepatocellular carcinoma (HCC). We elucidated the underlying mechanisms of these processes, which provided novel insights into the complex regulatory network of the androgen receptor in HCC metastasis and may have important implications for precision medicine.

Glutaminase in microglia: A novel regulator of neuroinflammation.

Neuroinflammation is the inflammatory responses that are involved in the pathogenesis of most neurological disorders. Glutaminase (GLS) is the enzyme that catalyzes the hydrolysis of glutamine to produce glutamate. Besides its well-known role in cellular metabolism and excitatory neurotransmission, GLS has recently been increasingly noticed to be up-regulated in activated microglia under pathological conditions. Furthermore, GLS overexpression induces microglial activation, extracellular vesicle secretion, and neuroinflammatory microenvironment formation, which, are compromised by GLS inhibitors in vitro and in vivo. These results indicate that GLS has more complicated implications in brain disease etiology than what are previously known. In this review, we introduce GLS isoforms, expression patterns in the body and the brain, and expression/activities regulation. Next, we discuss the metabolic and neurotransmission functions of GLS. Afterwards, we summarize recent findings of GLS-mediated microglial activation and pro-inflammatory extracellular vesicle secretion, which, in turns, induces neuroinflammation. Lastly, we provide a comprehensive discussion for the involvement of microglial GLS in the pathogenesis of various neurological disorders, indicating microglial GLS as a promising target to treat these diseases.

Opportunities, risks and challenges in global mental health and population neuroscience: a case of Sino-German cooperation.

Large scale prospective cohorts have now been established across several countries, and continents, and among the aims include an assessment of the developmental trajectory of mental disorders. This level of international cooperation helps transfer research findings to new social contexts as well as enabling an assessment of which findings can be replicated, and which interventions are most effective, in different social and cultural settings. However, data sharing across different regional and national health care systems requires a careful consideration of different standards in ethical research, data protection and patient care, including respect for patients' rights, in cooperating jurisdictions. In our review, we discuss ethical, legal and practical challenges associated with such cooperation with a focus on research participants, specifically patient recruitment, by considering the instance of China and Germany. Our broader aim is to promote international cooperation by identifying key challenges that arise in international cooperation, and to facilitate an exchange in relation to legal and practical approaches.

Vessels That Encapsulate Tumor Clusters (VETC) Pattern Is a Predictor of Sorafenib Benefit in Patients with Hepatocellular Carcinoma.

Sorafenib is the most recommended first-line systemic therapy for advanced hepatocellular carcinoma (HCC). Yet there is no clinically applied biomarker for predicting sorafenib response. We have demonstrated that a vascular pattern, named VETC (Vessels that Encapsulate Tumor Clusters), facilitates the release of whole tumor clusters into the bloodstream; VETC-mediated metastasis relies on vascular pattern, but not on migration and invasion of cancer cells. In this study, we aimed to explore whether vascular pattern could predict sorafenib benefit. Two cohorts of patients were recruited from four academic hospitals. The survival benefit of sorafenib treatment for patients with or without the VETC pattern (VETC+ /VETC- ) was investigated. Kaplan-Meier analyses revealed that sorafenib treatment significantly reduced death risk and prolonged overall survival (OS; in cohort 1/2, P = 0.004/0.005; hazard ratio [HR] = 0.567/0.408) and postrecurrence survival (PRS; in cohort 1/2, P = 0.001/0.002; HR = 0.506/0.384) in VETC+ patients. However, sorafenib therapy was not beneficial for VETC- patients (OS in cohort 1/2, P = 0.204/0.549; HR = 0.761/1.221; PRS in cohort 1/2, P = 0.121/0.644; HR = 0.728/1.161). Univariate and multivariate analyses confirmed that sorafenib treatment significantly improved OS/PRS in VETC+ , but not VETC- , patients. Further mechanistic investigations showed that VETC+ and VETC- HCCs displayed similar levels of light chain 3 (LC3) and phosphorylated extracellular signal-regulated kinase (ERK) in tumor tissues (pERK) or endothelial cells (EC-pERK), and greater sorafenib benefit was consistently observed in VETC+ HCC patients than VETC- irrespective of levels of pERK/EC-pERK/LC3, suggesting that the different sorafenib benefit between VETC+ and VETC- HCCs may not result from activation of Raf/mitogen-activated protein kinase kinase (MEK)/ERK and vascular endothelial growth factor (VEGF)A/VEGF receptor 2 (VEGFR2)/ERK signaling or induction of autophagy. Conclusion: Sorafenib is effective in prolonging the survival of VETC+ , but not VETC- , patients. VETC pattern may act as a predictor of sorafenib benefit for HCC.

Induced neural progenitor cells abundantly secrete extracellular vesicles and promote the proliferation of neural progenitors via extracellular signal-regulated kinase pathways.

Neural stem/progenitor cells (NPCs) are known to have potent therapeutic effects in neurological disorders through the secretion of extracellular vesicles (EVs). Despite the therapeutic potentials, the numbers of NPCs are limited in the brain, curbing the further use of EVs in the disease treatment. To overcome the limitation of NPC numbers, we used a three transcription factor (Brn2, Sox2, and Foxg1) somatic reprogramming approach to generate induced NPCs (iNPCs) from mouse fibroblasts and astrocytes. The resulting iNPCs released significantly higher numbers of EVs compared with wild-type NPCs (WT-NPCs). Furthermore, iNPCs-derived EVs (iNPC-EVs) promoted NPC function by increasing the proliferative potentials of WT-NPCs. Characterizations of EV contents through proteomics analysis revealed that iNPC-EVs contained higher levels of growth factor-associated proteins that were predicted to activate the down-stream extracellular signal-regulated kinase (ERK) pathways. As expected, the proliferative effects of iNPC-derived EVs on WT-NPCs can be blocked by an ERK pathway inhibitor. Our data suggest potent therapeutic effects of iNPC-derived EVs through the promotion of NPC proliferation, release of growth factors, and activation of ERK pathways. These studies will help develop highly efficient cell-free therapeutic strategies for the treatment of neurological diseases.

Exosomes released from neural progenitor cells and induced neural progenitor cells regulate neurogenesis through miR-21a.

Neural stem/progenitor cells (NPCs) are known to have potent therapeutic effects in neurological disorders through secreting exosomes. The limited numbers of NPCs in adult brain and the decline of NPC pool in many neurological disorders restrain the further use of exosomes in treating these diseases. The direct conversion of somatic cells into induced NPCs (iNPCs) provides abundant NPC-like cells to study the therapeutic effects of NPCs-originated exosomes (EXOs). Our recent study demonstrated that iNPCs-derived exosomes (iEXOs) exhibit distinct potential in facilitating the proliferation of NPCs, compared to EXOs, indicating the importance to investigate the effects of EXOs and iEXOs on the differentiation of NPCs, which remains unknown. Here, our results suggest that EXOs, but not iEXOs, promoted neuronal differentiation and neither of them had effect on glial generation. Microarray analysis revealed different miRNA signatures in EXOs and iEXOs, in which miR-21a was highly enriched in EXOs. Perturbation of function assay demonstrated the key roles of miR-21a in the generation of neurons and mediating the neurogenic potential of exosomes. Our data suggest that EXOs and iEXOs may achieve their therapeutic effects in promoting neurogenesis through transferring key miRNAs, which sheds light on the development of highly efficient cell-free therapeutic strategies for treating neurological diseases.

Glutaminase 1 regulates the release of extracellular vesicles during neuroinflammation through key metabolic intermediate alpha-ketoglutarate.

BACKGROUND: Extracellular vesicles (EVs) are important in the intercellular communication of the central nervous system, and their release is increased during neuroinflammation. Our previous data demonstrated an increased release of EVs during HIV-1 infection and immune activation in glial cells. However, the molecular mechanism by which infection and inflammation increase EV release remains unknown. In the current study, we investigated the role of glutaminase 1 (GLS1)-mediated glutaminolysis and the production of a key metabolic intermediate α-ketoglutarate on EV release. METHODS: Human monocyte-derived macrophage primary cultures and a BV2 microglia cell line were used to represent the innate immune cells in the CNS. Transmission electron microscopy, nanoparticle tracking analysis, and Western blots were used to determine the EV regulation. GLS1 overexpression was performed using an adenovirus vector in vitro and transgenic mouse models in vivo. Data were evaluated statistically by ANOVA, followed by the Bonferroni post-test for paired observations. RESULTS: Our data revealed an increased release of EVs in GLS1-overexpressing HeLa cells. In HIV-1-infected macrophages and immune-activated microglia BV2 cells, treatment with bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl)ethyl sulfide (BPTES) or CB839, two specific GLS inhibitors, significantly decreased EV release, suggesting a critical role of GLS1 in EV release. Furthermore, addition of α-ketoglutarate or ceramide rescued EV release during BPTES treatment, implicating α-ketoglutarate and ceramide as critical downstream effectors for GLS inhibitors. These findings were further corroborated with the investigation of brain tissues in GLS1-transgenic mice. The EV levels were significantly higher in GLS1 transgenic mice than those in control mice, suggesting that GLS1 increases EV release in vivo. CONCLUSIONS: These findings suggest that GLS1-mediated glutaminolysis and its downstream production of α-ketoglutarate are essential in regulating EV release during HIV-1 infection and immune activation. These new mechanistic regulations may help understand how glutamine metabolism shapes EV biogenesis and release during neuroinflammation.

TNF-α promotes extracellular vesicle release in mouse astrocytes through glutaminase.

BACKGROUND: Extracellular vesicles (EVs) are membrane-contained vesicles shed from cells. EVs contain proteins, lipids, and nucleotides, all of which play important roles in intercellular communication. The release of EVs is known to increase during neuroinflammation. Glutaminase, a mitochondrial enzyme that converts glutamine to glutamate, has been implicated in the biogenesis of EVs. We have previously demonstrated that TNF-α promotes glutaminase expression in neurons. However, the expression and the functionality of glutaminase in astrocytes during neuroinflammation remain unknown. We posit that TNF-α can promote the release of EVs in astrocytes through upregulation of glutaminase expression. RESULTS: Release of EVs, which was demonstrated by electron microscopy, nanoparticle tracking analysis (NTA), and Western Blot, increased in mouse astrocytes when treated with TNF-α. Furthermore, TNF-α treatment significantly upregulated protein levels of glutaminase and increased the production of glutamate, suggesting that glutaminase activity is increased after TNF-α treatment. Interestingly, pretreatment with a glutaminase inhibitor blocked TNF-α-mediated generation of reactive oxygen species in astrocytes, which indicates that glutaminase activity contributes to stress in astrocytes during neuroinflammation. TNF-α-mediated increased release of EVs can be blocked by either the glutaminase inhibitor, antioxidant N-acetyl-L-cysteine, or genetic knockout of glutaminase, suggesting that glutaminase plays an important role in astrocyte EV release during neuroinflammation. CONCLUSIONS: These findings suggest that glutaminase is an important metabolic factor controlling EV release from astrocytes during neuroinflammation.

Glutaminase C overexpression in the brain induces learning deficits, synaptic dysfunctions, and neuroinflammation in mice.

Glutaminolysis, a metabolic process that converts glutamine to glutamate, is particularly important for the central nervous system since glutamate is the major transmitter of excitatory synapses. Glutaminase is the mitochondrial enzyme that catalyzes the first step of glutaminolysis. Two genes encode at least four isoforms of glutaminase in humans. Gls1 gene encodes isoforms kidney-type glutaminase (KGA) and glutaminase C (GAC) through alternative splicing, whereas Gls2 gene encodes liver-type glutaminase isoforms. KGA and GAC have been associated with several neurological diseases. However, it remains unclear whether changes in their expressions can directly cause brain abnormalities. Using a transgenic approach, we generated mice that overexpressed GAC in the brain. The resulting transgenic mice had severe impairments in spatial and fear learning compared with littermate controls. The learning deficits were consistent with diminished hippocampal long-term potentiation in the hippocampal slices of the GAC transgenic mice. Furthermore, we found increases in astrocyte and microglia markers, inflammatory factors, and a decrease in synapse marker synaptophysin, suggesting neuroinflammation and synaptic changes in the GAC transgenic mouse brains. In conclusion, these findings provide the first evidence that GAC overexpression in the brain has deleterious effects on learning and synaptic integrity in vivo.

Effects of Baicalin on Blood Pressure and Left Ventricular Remodeling in Rats with Renovascular Hypertension.

BACKGROUND This study aimed to explore the effect of baicalin, which is a kind of bioactive flavonoid, on blood pressure and left ventricular remodeling in rats with renovascular hypertension. MATERIAL AND METHODS A total of 40 male Wistar rats were randomly assigned into sham-operation (n=10) and renal hypertension model groups (2-kidney-1 clip; 2K-1C, n=30). The rats in the renal hypertension model group were randomly subdivided into 2K-1C (n=13) and 2K-1C/Baicalin groups (n=14). The cardiac function indexes were determined after 4 weeks. The morphological changes in the myocardial tissue were observed using hematoxylin and eosin and Masson staining. The myocardial apoptosis was detected using the terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling method, and the expression of C/EBP homologous protein and caspase-3 was monitored by Western blot. The expression of GRP78 and GRP94 in myocardial cells of rats was detected by qPCR and Western blot technology. RESULTS No significant change in blood pressure was observed in the 2K-1C/Baicalin group compared with the 2K-1C group, but the indexes of left ventricular remodeling significantly improved. Pathological myocardial fibrosis and expression of fibrosis-related factors significantly decreased in the 2K-1C/Baicalin group compared with the 2K-1C group. The expression of glucose-regulated protein (GRP)78, GRP94, CHOP, and caspase-3, and apoptosis of cardiomyocytes also decreased in the 2K-1C/Baicalin group. CONCLUSIONS Baicalin has no significant antihypertensive effect, but reduced pathological changes in the myocardium, alleviated endoplasmic reticulum stress, and reduced myocardial apoptosis, reverting left ventricular remodeling in rats with renovascular hypertension.