Zinc Promotes Microglial Autophagy Through NLRP3 Inflammasome Inactivation via XIST/miR-374a-5p Axis in Spinal Cord Injury.

Zinc has reported to play a neuroprotective role in the development of spinal cord injury (SCI). The protective mechanism of zinc remains to be uncovered. The aim of the current study was to investigate the neuroprotective mechanism of zinc in the progression of SCI. The C57BL/6J mouse SCI model was established to confirm the protective role of zinc in vivo, while the cellular model was induced in mouse microglial BV2 cells by using lipopolysaccharide (LPS). The expression levels of XIST, miR-374a-5p and NLRP3 inflammasome as well as the autophagy-related proteins were detected using real-time PCR and immunoblotting. Cell viability was assessed by CCK-8 assay. Apoptosis was evaluated by TUNEL staining, flow cytometry, the determination of apoptosis-related proteins. The target relationship was confirmed by luciferase reporter assays. Zinc improved locomotor function in SCI mice and alleviated LPS-induced BV2 cell injuries by inhibiting apoptosis and initiating autophagy processes. XIST and NLRP3 inflammasome was upregulated while miR-374a-5p was downregulated in spinal cords of SCI mice and LPS-treated BV2 cells. All these effects were inhibited by Zinc treatment. XIST knockdown triggered microglial autophagy-mediated NLRP3 inactivation in LPS-induced BV2 cells by regulating miR-374a-5p. Zinc treatment protected BV2 cells from LPS-induced cell injury by the downregulation of XIST. This process might be through autophagy­mediated NLRP3 inflammasome inactivation by targeting miR-374a-5p. Zinc downregulates XIST and induces neuroprotective effects against SCI by promoting microglial autophagy-induced NLRP3 inflammasome inactivation through regulating miR-374a-5p. Our finding provides novel opportunities for the understanding of zinc-related therapy of SCI.

A Framework for Single-Panicle Litchi Flower Counting by Regression with Multitask Learning.

The number of flowers is essential for evaluating the growth status of litchi trees and enables researchers to estimate flowering rates and conduct various phenotypic studies, particularly focusing on the information of individual panicles. However, manual counting remains the primary method for quantifying flowers, and there has been insufficient emphasis on the advancement of reliable deep learning methods for estimation and their integration into research. Furthermore, the current density map-based methods are susceptible to background interference. To tackle the challenges of accurately quantifying small and dense male litchi flowers, a framework counting the flowers in panicles is proposed. Firstly, an existing effective algorithm YOLACT++ is utilized to segment individual panicles from images. Secondly, a novel algorithm FlowerNet based on density map regression is proposed to accurately count flowers in each panicle. By employing a multitask learning approach, FlowerNet effectively captures both foreground and background information, thereby overcoming interference from non-target areas during pixel-level regression tasks. It achieves a mean absolute error of 47.71 and a root mean squared error of 61.78 on the flower dataset constructed. Additionally, a regression equation is established using a dataset of inflorescences to examine the application of the algorithm for flower counting. It captures the relationship between the predicted number of flowers by FlowerNet and the manually counted number, resulting in a determination coefficient (R2) of 0.81. The proposed algorithm shows promise for automated estimation of litchi flowering quantity and can serve as a valuable reference for litchi orchard management during flowering period.

Elimination of Senescent Osteocytes by Bone-Targeting Delivery of ß-Galactose-Modified Maytansinoid Prevents Age-Related Bone Loss.

The accumulation of senescent cells in bone during aging contributes to senile osteoporosis, and clearance of senescent cells by senolytics could effectively alleviate bone loss. However, the applications of senolytics are limited due to their potential toxicities. Herein, small extracellular vesicles (sEVs) have been modified by incorporating bone-targeting peptide, specifically (AspSerSer)6, to encapsulate galactose-modified Maytansinoids (DM1). These modified vesicles are referred to as (AspSerSer)6-sEVs/DM1-Gal, and they have been designed to specifically clear the senescent osteocytes in bone tissue. In addition, the elevated activity of lysosomal ß-galactosidase in senescent osteocytes, but not normal cells in bone tissue, could break down DM1-Gal to release free DM1 for selective elimination of senescent osteocytes. Mechanically, DM1 could disrupt tubulin polymerization, subsequently inducing senescent osteocytes apoptosis. Further, administration of bone-targeting senolytics to aged mice could alleviate aged-related bone loss without non-obvious toxicity. Overall, this bone-targeting senolytics could act as a novel candidate for specific clearance of senescent osteocytes, ameliorating age-related bone loss, with a promising therapeutic potential for senile osteoporosis.

Inflammatory Fibroblast-Like Synoviocyte-Derived Exosomes Aggravate Osteoarthritis via Enhancing Macrophage Glycolysis.

The severity of osteoarthritis (OA) and cartilage degeneration is highly associated with synovial inflammation. Although recent investigations have revealed a dysregulated crosstalk between fibroblast-like synoviocytes (FLSs) and macrophages in the pathogenesis of synovitis, limited knowledge is available regarding the involvement of exosomes. Here, increased exosome secretion is observed in FLSs from OA patients. Notably, internalization of inflammatory FLS-derived exosomes (inf-exo) can enhance the M1 polarization of macrophages, which further induces an OA-like phenotype in co-cultured chondrocytes. Intra-articular injection of inf-exo induces synovitis and exacerbates OA progression in murine models. In addition, it is demonstrated that inf-exo stimulation triggers the activation of glycolysis. Inhibition of glycolysis using 2-DG successfully attenuates excessive M1 polarization triggered by inf-exo. Mechanistically, HIF1A is identified as the determinant transcription factor, inhibition of which, both pharmacologically or genetically, relieves macrophage inflammation triggered by inf-exo-induced hyperglycolysis. Furthermore, in vivo administration of an HIF1A inhibitor alleviates experimental OA. The results provide novel insights into the involvement of FLS-derived exosomes in OA pathogenesis, suggesting that inf-exo-induced macrophage dysfunction represents an attractive target for OA therapy.

Osteocyte-derived sclerostin impairs cognitive function during ageing and Alzheimer's disease progression.

Ageing increases susceptibility to neurodegenerative disorders, such as Alzheimer's disease (AD). Serum levels of sclerostin, an osteocyte-derived Wnt-ß-catenin signalling antagonist, increase with age and inhibit osteoblastogenesis. As Wnt-ß-catenin signalling acts as a protective mechanism for memory, we hypothesize that osteocyte-derived sclerostin can impact cognitive function under pathological conditions. Here we show that osteocyte-derived sclerostin can cross the blood-brain barrier of old mice, where it can dysregulate Wnt-ß-catenin signalling. Gain-of-function and loss-of-function experiments show that abnormally elevated osteocyte-derived sclerostin impairs synaptic plasticity and memory in old mice of both sexes. Mechanistically, sclerostin increases amyloid ß (Aß) production through ß-catenin-ß-secretase 1 (BACE1) signalling, indicating a functional role for sclerostin in AD. Accordingly, high sclerostin levels in patients with AD of both sexes are associated with severe cognitive impairment, which is in line with the acceleration of Αß production in an AD mouse model with bone-specific overexpression of sclerostin. Thus, we demonstrate osteocyte-derived sclerostin-mediated bone-brain crosstalk, which could serve as a target for developing therapeutic interventions against AD.

Resveratrol inhibits LPS-induced apoptosis in VSC4.1 motoneurons through enhancing SIRT1-mediated autophagy.

OBJECTIVES: Resveratrol has been recognized as a potential therapeutic drug in spinal cord injury (SCI). Sirtuin 1 (SIRT1) is vital in the regulation of apoptosis and cell stress response. In this research, our purpose was to explore the mechanisms of resveratrol on neuroprotection and to explore the role of SIRT1. MATERIALS AND METHODS: We used lipopolysaccharide (LPS) in the VSC4.1 spinal cord neuron cell line to mimic the micro-environment of the injured spinal cord. The apoptosis of VSC4.1 motoneurons was assessed by TUNEL staining, Western blot, and RT-PCR. Immunofluorescence staining was used to observe the expression site of SIRT1, LC3-B, and Beclin-1, and their protein levels were measured by Western blot and RT-PCR. RESULTS: Our results showed that resveratrol inhibits LPS-induced apoptosis in VSC4.1 motoneurons. Levels of LC3-B, beclin-1, and SIRT1 indicated a significant increase after resveratrol treatment. But, if autophagy was inhibited, apoptosis in VSC4.1 motoneurons significantly increased. When the cells were treated with EX527, a SIRT1 inhibitor, the protein contents of LC3-B and Beclin-1 were suppressed. CONCLUSION: Resveratrol inhibits apoptosis through promoting autophagy in VSC4.1 motoneurons. SIRT1 was involved in autophagy activated by resveratrol in VSC4.1 motoneurons.

Regulation of inflammatory cytokines for spinal cord injury recovery.

Spinal cord injury (SCI) is one of the most destructive traumatic diseases in human beings. The balance of inflammation in the microenvironment is crucial to the repair process of spinal cord injury. Inflammatory cytokines are direct mediators of local lesion inflammation and affect the prognosis of spinal cord injury to varying degrees. In spinal cord injury models, some inflammatory cytokines are beneficial for spinal cord repair, while others are harmful. A large number of animal studies have shown that local targeted administration can effectively regulate the secretion and delivery of inflammatory cytokines and promote the repair of spinal cord injury. In addition, many clinical studies have shown that drugs can promote the repair of spinal cord injury by regulating the content of inflammatory cytokines. However, topical administration affects only a small portion of inflammatory cytokines. In addition, different individuals have different inflammatory cytokine profiles during spinal cord injury. Therefore, future research should aim to develop a personalized local delivery therapeutic cocktail strategy to effectively and accurately regulate inflammation and obtain substantial functional recovery from spinal cord injury.

Berberine-loaded M2 macrophage-derived exosomes for spinal cord injury therapy.

Spinal cord injury (SCI) causes immune activation of resident macrophages/microglia. Activated macrophages/microglia have two different phenotypes, the pro-inflammatory classically activated (M1) phenotype and the anti-inflammatory alternatively activated (M2) phenotype. M1 phenotype macrophages/microglia are the key factor in inflammation. The treatment of SCI remains a huge challenge due to the nontargeting and inefficiency of anti-inflammatory drugs through the blood-brain barrier (BBB). The purpose of this experiment was to design M2-type primary peritoneal macrophages exosomes (Exos) as a drug carrier for berberine (Ber), which can be efficiently targeted to deliver drugs to the injured spinal cord due to the natural advantage of Exos across the BBB. The Exos with particle size of 125±12 nm were loaded with by an ultrasonic method and the drug loading reached 17.13 ±1.64%. The Ber release experiment showed that the loaded sample (Exos-Ber) exhibited sustained release effect, and the cumulative release amount reached 71.44±2.86% within 48 h. In vitro and in vivo experiments confirmed that the Exos-Ber could decrease the M1 protein marker iNOS, elevate the M2 protein marker CD206 and reduce inflammatory and apoptotic cytokines (TNF-α, IL-1ß, IL-6, Caspase 9, Caspase 8), which showed that Exos-Ber had a good anti-inflammatory and anti-apoptotic effect by inducing macrophages/microglia from the M1 phenotype to M2 phenotype polarization. Moreover, the motor function of SCI mice was significantly improved after Exos-Ber treatment, indicating that Exos-Ber is a potential agent for SCI therapy. STATEMENT OF SIGNIFICANCE: Efficient targeting strategy for drug delivery. In addition to good biocompatibility and stealth ability, M2 macrophage-derived Exosomes present natural inflammatory targeting ability. The inflammatory microenvironment after spinal cord injury provides motivation for the targeting of exosomes. Natural drug carrier with higher safety. With the rapid development of nanomaterials, drug carriers have become more selective. However, due to the special microenvironment after central nervous system damage, some non-degradable inorganic materials will increase the pressure of self-healing and even secondary damage to neurons, which has been solved by the emergence of exosomes. Some previous studies used tumor cell line exosomes as drug carriers, but the carcinogenic factors carried by themselves have extremely high hidden dangers, and endogenous macrophage exosomes have absolute advantages over their safety.

Zinc provides neuroprotection by regulating NLRP3 inflammasome through autophagy and ubiquitination in a spinal contusion injury model.

AIM: Spinal cord injury (SCI) is a serious disabling injury worldwide, and the excessive inflammatory response it causes plays an important role in secondary injury. Regulating the inflammatory response can be a potential therapeutic strategy for improving the prognosis of SCI. Zinc has been demonstrated to have a neuroprotective effect in experimental spinal cord injury models. In this study, we aimed to explore the neuroprotective effect of zinc through the suppression of the NLRP3 inflammasome. METHOD: Allen's method was used to establish an SCI model in C57BL/6J mice. The Basso Mouse Scale (BMS), Nissl staining were employed to confirm the protective effect of zinc on neuronal survival and functional recovery in vivo. Western blotting (WB), immunofluorescence (IF), and enzyme-linked immunosorbent assay (ELISA) were used to detect the expression levels of NLRP3 inflammasome and autophagy-related proteins. Transmission electron microscopy (TEM) was used to confirm the occurrence of zinc-induced autophagy. In vitro, lipopolysaccharide (LPS) and ATP polarized BV2 cells to a proinflammatory phenotype. 3-Methyladenine (3-MA) and bafilomycin A1 (BafA1) were chosen to explore the relationship between the NLRP3 inflammasome and autophagy. A coimmunoprecipitation assay was used to detect the ubiquitination of the NLRP3 protein. RESULTS: Our data showed that zinc significantly promoted motor function recovery after SCI. In vivo, zinc treatment inhibited the protein expression level of NLRP3 while increasing the level of autophagy. These effects were fully validated by the polarization of BV2 cells to a proinflammatory phenotype. The results showed that when 3-MA and BafA1 were applied, the promotion of autophagy by zinc was blocked and that the inhibitory effect of zinc on NLRP3 was reversed. Furthermore, co-IP confirmed that the promotion of autophagy by zinc also activated the protein expression of ubiquitin and suppressed high levels of NLRP3. CONCLUSION: Zinc provides neuroprotection by regulating NLRP3 inflammasome through autophagy and ubiquitination after SCI.

Zinc Regulates Glucose Metabolism of the Spinal Cord and Neurons and Promotes Functional Recovery after Spinal Cord Injury through the AMPK Signaling Pathway.

Spinal cord injury (SCI) is a traumatic disease that can cause severe nervous system dysfunction. SCI often causes spinal cord mitochondrial dysfunction and produces glucose metabolism disorders, which affect neuronal survival. Zinc is an essential trace element in the human body and plays multiple roles in the nervous system. This experiment is intended to evaluate whether zinc can regulate the spinal cord and neuronal glucose metabolism and promote motor functional recovery after SCI. Then we explore its molecular mechanism. We evaluated the function of zinc from the aspects of glucose uptake and the protection of the mitochondria in vivo and in vitro. The results showed that zinc elevated the expression level of GLUT4 and promoted glucose uptake. Zinc enhanced the expression of proteins such as PGC-1α and NRF2, reduced oxidative stress, and promoted mitochondrial production. In addition, zinc decreased neuronal apoptosis and promoted the recovery of motor function in SCI mice. After administration of AMPK inhibitor, the therapeutic effect of zinc was reversed. Therefore, we concluded that zinc regulated the glucose metabolism of the spinal cord and neurons and promoted functional recovery after SCI through the AMPK pathway, which is expected to become a potential treatment strategy for SCI.

MICAL1 (molecule interacting with CasL 1) protects oligodendrocyte cells from oxidative injury through regulating apoptosis, autophagy in spinal cord injury.

Molecule's mechanism of action interacting with CasL 1 (MICAL1) in spinal cord injury (SCI) is unclear. This study aimed to detect the function of MICAL1 in SCI. Western blot was used to analyze the change of MICAL1 in vivo. Immunofluorescence staining was used to detect the location of MICAL1 expression. Oligodendrocyte cells were treated with H2O2 to induce oxidative injury. Subsequently, siRNA transfection was performed to decrease MICAL1 expression in oligodendrocyte cells. Then, the effects of MICAL1 on oxidative stress, apoptosis, and autophagy were assessed. We found that silencing of MICAL1 could significantly reduce the levels of the nuclear factor erythroid 2-related factor 2 (Nrf2), increase the expression of pro-apoptotic factors (Bax and C-caspase 3), decrease the levels of anti-apoptotic factor (Bcl-2) and pro-autophagy factors (Beclin1 and LC3B). Therefore, MICAL1 is a potential target gene for SCI clinical therapy.

Zinc attenuates ferroptosis and promotes functional recovery in contusion spinal cord injury by activating Nrf2/GPX4 defense pathway.

AIM: Spinal cord injury (SCI) involves multiple pathological processes. Ferroptosis has been shown to play a critical role in the injury process. We wanted to explore whether zinc can inhibit ferroptosis, reduce inflammation, and then exert a neuroprotective effect. METHODS: The Alice method was used to establish a spinal cord injury model. The Basso Mouse Scale (BMS), Nissl staining, hematoxylin-eosin staining, and immunofluorescence analysis were used to investigate the protective effect of zinc on neurons on spinal cord neurons and the recovery of motor function. The regulation of the nuclear factor E2/heme oxygenase-1 (NRF2/HO-1) pathway was assessed, the levels of essential ferroptosis proteins were measured, and the changes in mitochondria were confirmed by transmission electron microscopy and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide (JC-1) staining. In vitro experiments using VSC4.1 (spinal cord anterior horn motor neuroma cell line), 4-hydroxynonenal (4HNE), reactive oxygen species (ROS), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), lipid peroxides, and finally the levels of inflammatory factors were detected to assess the effect of zinc. RESULTS: Zinc reversed behavioral and structural changes after SCI. Zinc increased the expression of NRF2/HO-1, thereby increasing the content of glutathione peroxidase 4 (GPX4), SOD, and GHS and reducing the levels of lipid peroxides, MDA, and ROS. Zinc also rescued injured mitochondria and effectively reduced spinal cord injury and the levels of inflammatory factors, and the NRF2 inhibitor Brusatol reversed the effects of zinc. CONCLUSION: Zinc promoted the degradation of oxidative stress products and lipid peroxides through the NRF2/HO-1 and GPX4 signaling pathways to inhibit ferroptosis in neurons.

Zinc promotes autophagy and inhibits apoptosis through AMPK/mTOR signaling pathway after spinal cord injury.

Autophagy is a intracellular biological process that controls the homeostasis of nutrition deprivation and starvation and has been associated with the development of traumatic diseases. Zinc, an important chemical element involved in life activities, has improved nerve recovery effects through intraperitoneal injection. The purpose of this study was to probe the possible modulation of autophagy and apoptosis from the injured spinal cord and neurons by zinc administration. It was shown that zinc significantly induced the level of Beclin1 and LC3B by activating adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) signaling pathway. In addition, zinc suppressed apoptosis in the injured spinal cord. Taken together, these findings suggested that zinc through promoting neurons autophagy and inhibiting apoptosis.

Zinc promotes functional recovery after spinal cord injury by activating Nrf2/HO-1 defense pathway and inhibiting inflammation of NLRP3 in nerve cells.

AIMS: To study the specific therapeutic effect of zinc on spinal cord injury (SCI) and its specific protective mechanism. MAIN METHODS: The effects of zinc ions on neuronal cells were examined in a mouse SCI model and in vitro. In vivo, neurological function was assessed by Basso Mouse Scaleat (BMS) at 1, 3, 5, 7, 10, 14, 21, and 28 days after spinal cord injury. The number of neurons and histomorphology were observed by nissl staining and hematoxylin-eosin staining (HE). The chromatin and mitochondrial structure of neurons were detected by transmission electron microscopy (TEM). The expression of nuclear factor erythroid 2 related factor 2 (Nrf2)-related antioxidant protein and NLRP3 inflammation-related protein were detected in vivo and in vitro by western blot (WB) and immunofluorescence (IF), respectively. KEY FINDINGS: Zinc treatment promoted motor function recovery on days 3, 5, 7, 14, 21 and 28 after SCI. In addition, zinc reduces the mitochondrial void rate in spinal neuronal cells and promotes neuronal recovery. At the same time, zinc reduced the levels of reactive oxygen species (ROS) and malondialdehyde in spinal cord tissue after SCI, while increasing superoxide dismutase activity and glutathione peroxidase production. Zinc treatment resulted in up-regulation of Nrf2/Ho-1 levels and down-regulation of nlrp3 inflammation-associated protein expression in vitro and in vivo. SIGNIFICANCE: Zinc has a protective effect on spinal cord injury by inhibiting oxidative damage and nlrp3 inflammation. Potential mechanisms may include activation of the Nrf 2/Ho-1 pathway to inhibit nlrp3 inflammation following spinal cord injury. Zinc has the potential to treat SCI.