Activation of the CD200/CD200R1 axis attenuates neuroinflammation and improves postoperative cognitive dysfunction via the PI3K/Akt/NF-κB signaling pathway in aged mice

Investigating the Interplay Between the Nrf2/Keap1/HO-1/SIRT-1 Pathway and the p75NTR/PI3K/Akt/MAPK Cascade in Neurological Disorders: Mechanistic Insights and Therapeutic Innovations

Neurological illnesses are debilitating diseases that affect brain function and balance. Due to their complicated aetiologies and progressive nature, neurodegenerative and neuropsychiatric illnesses are difficult to treat. These incurable conditions damage brain functions like mobility, cognition, and emotional regulation, but medication, gene therapy, and physical therapy can manage symptoms. Disruptions in cellular signalling pathways, especially those involving oxidative stress response, memory processing, and neurotransmitter modulation, contribute to these illnesses. This review stresses the interplay between key signalling pathways involved in neurological diseases, such as the Nrf2/Keap1/HO-1/SIRT-1 axis and the p75NTR/PI3K/Akt/MAPK cascade. To protect neurons from oxidative damage and death, the Nrf2 transcription factor promotes antioxidant enzyme production. The Keap1 protein releases Nrf2 during oxidative stress for nuclear translocation and gene activation. The review also discusses how neurotrophin signalling through the p75 neurotrophin receptor (p75NTR) determines cell destiny, whether pro-survival or apoptotic. The article highlights emerging treatment approaches targeting these signalling pathways by mapping these connections. Continued research into these molecular pathways may lead to new neurological disease treatments that restore cellular function and neuronal survival. In addition to enhanced delivery technologies, specific modulators and combination therapies should be developed to fine-tune signalling responses. Understanding these crosstalk dynamics is crucial to strengthening neurological illness treatment options and quality of life.

Role of dexmedetomidine in postoperative cognitive dysfunction and sleep improvement in aged rats by regulating the PI3K/Akt signaling pathway and its mechanism

OBJECTIVE

This study aims to explore the mechanism of dexmedetomidine (Dex) in improving postoperative cognitive dysfunction (POCD) and postoperative sleep in aged rats through the PI3K/Akt signaling pathway.

METHODS

Splenectomy was used to establish a POCD model in aged rats. Open field test (OFT) and new object recognition test (NORT) were used to observe the cognitive function of rats The awakening and sleep times of rats were recorded. Hematoxylin-eosin, Nissl, and TUNEL staining were adopted to examine histopathological alterations, neuronal cell damage, and apoptosis, respectively; western blot to detect the activation of the PI3K/Akt signaling pathway and the protein level of apoptosis factors Bcl-2, Bax, and cleaved caspase-3; enzyme-linked immunosorbent assay to quantify the concentrations of inflammatory factors IL-6, IL-1β, and TNF-α.

RESULTS

On days 1, 7, and 14 post-splenectomy surgery, aged rats exhibited shortened moving distance in OFT, reduced discrimination rate in NORT, prolonged awakening time, and shortened sleep time, while such effect was reversed by further Dex treatment. In addition, neuronal damage, inflammatory response, and apoptosis occurred in the hippocampal CA1 area in aged rats but can be attenuated by Dex treatment. Dex triggered the activation of the PI3K/Akt signaling pathway in the hippocampus in aged rats after surgery, and inhibition of the PI3K/Akt signaling pathway can result in a partial reversal of the alleviating effects observed with Dex treatment.

CONCLUSION

Dex improves POCD and postoperative sleep in aged rats by activating the PI3K/Akt signaling pathway to reduce inflammatory response and apoptosis in the hippocampal CA1 area.

Prenatal Exposure to Valproic Acid may Alter CD200/CD200R Signaling Pathways in a Rat Model of Autism Spectrum Disorder

Objective

To investigate the potential toxic effects of prenatal exposure to valproic acid (VPA) on microglia-neuron communication in the brain, with a specific focus on the alterations in key molecules involved in this process, namely CX3CL1/CX3CR1 and CD200/CD200R, during the early stages of life in a rat model of autism.

Methods

Pregnant female rats were administered either sterile saline or VPA on embryonic day 12.5. The brains of the rat offspring were collected on postnatal day 30 for analysis. Immunohistochemical techniques and enzyme-linked immunosorbent assay (ELISA) were employed to assess changes in microglia-neuron crosstalk.

Results

The study revealed a significant reduction in CD200 levels within the hippocampus of rats on postnatal day 30 following prenatal exposure to VPA, indicating an impairment in CD200/CD200R signaling. Additionally, there was no observed increase in microglial numbers or any pathological alterations in the hippocampus. Additionally, no significant changes in the levels of CX3CL1 and CX3CR1 were noted in the VPA-exposed rats compared with the control group.

Conclusion

Prenatal exposure to VPA resulted in a decrease in CD200 expression within the hippocampus, potentially disrupting the communication between microglia and neurons. The findings suggest that VPA may modify the interactions between microglia and neurons, which could lead to neuroinflammation due to hyperactivated microglia. These disruptions have the potential to affect synaptic connectivity and contribute to the development of neurodevelopmental disorders, including autism. Further research is necessary to clarify the underlying mechanisms and implications for pathological conditions associated with autism spectrum disorder (ASD).

Microglia efferocytosis: an emerging mechanism for the resolution of neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by significant neuroinflammatory responses. Microglia, the immune cells of the central nervous system, play a crucial role in the pathophysiology of AD. Recent studies have indicated that microglial efferocytosis is an important mechanism for clearing apoptotic cells and cellular debris, facilitating the resolution of neuroinflammation. This review summarizes the biological characteristics of microglia and the mechanisms underlying microglial efferocytosis, including the factors and signaling pathways that regulate efferocytosis, the interactions between microglia and other cells that influence this process, and the role of neuroinflammation in AD. Furthermore, we explore the role of microglial efferocytosis in AD from three perspectives: its impact on the clearance of amyloid plaques, its regulation of neuroinflammation, and its effects on neuroprotection. Finally, we summarize the current research status on enhancing microglial efferocytosis to alleviate neuroinflammation and improve AD, as well as the future challenges of this approach as a therapeutic strategy for AD.

Study on the Molecular Mechanism of Baicalin Phosphorylation of Tau Protein Content in a Cell Model of Intervention Cognitive Impairment

Objective

This study aimed to predict the molecular mechanism of baicalein through network pharmacology, cell experiments and molecular docking. The goal was to elucidate the mechanism for the treatment of mild cognitive impairment.

Materials and Methods

The protein-protein interaction network (PPI) and Cytoscape software were used to screen the hub genes of intersection genes, while the therapeutic mechanism of baicalein was predicted through the Gene ontology (GO) and Kyoto Encyclopedia of Gene and Genomes (KEGG) enrichment analysis. Molecular docking of the core target and baicalein was conducted using AutoDock software. The neuroprotective effect of Baicalein with different concentrations on okadaic acid-treated SH-SY5Y cells was investigated in cell experiments. Scratch experiments were conducted to explore the effect of baicalein on cell migration ability, and enzyme linked immunosorbent assay was employed to measure the content of extracellular pathological proteins. Western Blot and Cellular immunofluorescence pinpointed differences in the relevant protein content.

Results

Enrichment analysis revealed significant enrichment in the PI3K-Akt signaling pathway, and molecular docking demonstrated a favorable binding energy between baicalein and AKT1. In cell experiments, baicalein presented a positive impact on mild cognitive impairment by elevating P-AKT1 and P-GSK-3β levels while reducing the overall amount of P-tau.

Conclusion

As demonstrated by the present study, the low concentration of baicalein (15μmol/L) effectively managed the mild cognitive impairment by regulating the phosphorylation of AKT1 and GSK-3β.

Intranasal insulin administration affecting perioperative neurocognitive dysfunction by regulating calcium transport protein complex IP3R/GRP75/VDAC1 on MAMs

Perioperative neurocognitive disorders (PND) are common complications following surgery and anesthesia, especially in the elderly. These disorders are associated with disruptions in neuronal energy metabolism and mitochondrial function. This study explores the potential of intranasal insulin administration as a therapeutic strategy to prevent PND by targeting the calcium transport protein complex IP3R/GRP75/VDAC1 on mitochondria-associated endoplasmic reticulum membranes (MAMs).

METHODS

Male C57BL/6J mice underwent partial hepatectomy to induce PND and were subsequently treated with either intranasal insulin or saline. Cognitive function was evaluated using the Morris water maze test, and hippocampal tissue was analyzed for calcium transport protein complex IP3R/GRP75/VDAC1 expression and apoptosis markers. In vitro, HT22 and BV2 cell co-cultures were utilized to simulate surgical injury, with IP3R knockdown employed to assess its effects on oxidative stress and apoptosis.

RESULTS

Intranasal insulin effectively alleviated cognitive impairment as demonstrated by improved performance in the Morris water maze. It significantly reduced neuronal apoptosis and modulated the expression of the IP3R/GRP75/VDAC1 complex, enhancing mitochondrial ATP production and stabilizing MAMs. Furthermore, insulin administration also increased PI3K/AKT signaling, counteracting the impact of surgical stress. In vitro experiments confirmed that IP3R knockdown mitigated inflammation-induced oxidative stress and neuronal apoptosis, while insulin's beneficial effects were blocked by inhibition of the PI3K/AKT pathway.

CONCLUSION

Intranasal insulin mitigates PND by modulating the IP3R/GRP75/VDAC1 complex and enhancing mitochondrial function through the PI3K/AKT signaling pathway. This study supports the potential of intranasal insulin as a promising therapeutic strategy for preventing and managing PND, potentially leading to improved surgical outcomes for elderly patients.

Red light-induced localized release of carbon monoxide for alleviating postoperative cognitive dysfunction

Inflammation within the central nervous system (CNS), which may be triggered by surgical trauma, has been implicated as a significant factor contributing to postoperative cognitive dysfunction (POCD). The relationship between mitigating inflammation at peripheral surgical sites and its potential to attenuate the CNS inflammatory response, thereby easing POCD symptoms, remains uncertain. Notably, carbon monoxide (CO), a gasotransmitter, exhibits pronounced anti-inflammatory effects. Herein, we have developed carbon monoxide-releasing micelles (CORMs), a nanoparticle that safely and locally liberates CO upon exposure to 650 nm light irradiation. In a POCD mouse model, treatment with CORMs activated by light (CORMs + hv) markedly reduced the concentrations of interleukin (IL)-6, IL-1β, and tumor necrosis factor-alpha (TNF-α) in both the peripheral blood and the hippocampus, alongside a decrease in ionized calcium-binding adapter molecule 1 in the hippocampal CA1 region. Furthermore, CORMs + hv treatment diminished Evans blue extravasation, augmented the expression of tight junction proteins zonula occludens-1 and occludin, enhanced neurocognitive functions, and fostered fracture healing. Bioinformatics analysis and experimental validation has identified Htr1b and Trhr as potential key regulators in the neuroactive ligand-receptor interaction signaling pathway implicated in POCD. This work offers new perspectives on the mechanisms driving POCD and avenues for therapeutic intervention.

Bioactive peptides and proteins for tissue repair: microenvironment modulation, rational delivery, and clinical potential

Bioactive peptides and proteins (BAPPs) are promising therapeutic agents for tissue repair with considerable advantages, including multifunctionality, specificity, biocompatibility, and biodegradability. However, the high complexity of tissue microenvironments and their inherent deficiencies such as short half-live and susceptibility to enzymatic degradation, adversely affect their therapeutic efficacy and clinical applications. Investigating the fundamental mechanisms by which BAPPs modulate the microenvironment and developing rational delivery strategies are essential for optimizing their administration in distinct tissue repairs and facilitating clinical translation. This review initially focuses on the mechanisms through which BAPPs influence the microenvironment for tissue repair via reactive oxygen species, blood and lymphatic vessels, immune cells, and repair cells. Then, a variety of delivery platforms, including scaffolds and hydrogels, electrospun fibers, surface coatings, assisted particles, nanotubes, two-dimensional nanomaterials, and nanoparticles engineered cells, are summarized to incorporate BAPPs for effective tissue repair, modification strategies aimed at enhancing loading efficiencies and release kinetics are also reviewed. Additionally, the delivery of BAPPs can be precisely regulated by endogenous stimuli (glucose, reactive oxygen species, enzymes, pH) or exogenous stimuli (ultrasound, heat, light, magnetic field, and electric field) to achieve on-demand release tailored for specific tissue repair needs. Furthermore, this review focuses on the clinical potential of BAPPs in facilitating tissue repair across various types, including bone, cartilage, intervertebral discs, muscle, tendons, periodontal tissues, skin, myocardium, nervous system (encompassing brain, spinal cord, and peripheral nerve), endometrium, as well as ear and ocular tissue. Finally, current challenges and prospects are discussed.

The NF-κB pathway: Key players in neurocognitive functions and related disorders

Perioperative neurocognitive disorder (PND) is a common complication of surgical anesthesia, yet its precise etiology remains unclear. Neuroinflammation is a key feature of PND, influenced by both patient -related and surgical variables. The nuclear factor-κB (NF-κB) transcription factor family plays a critical role in regulating the body's immunological proinflammatory response, which is pivotal in the development of PND. Surgery and anesthesia trigger the activation of the NF-κB signaling pathway, leading to the initiation of inflammatory cascades, disruption of the blood-brain barrier, and neuronal injury. Immune cells and glial cells are central to these pathological processes in PND. Furthermore, this study explores the interactions between NF-κB and various signaling molecules, including Tlr4, P2X, α7-nAChR, ROS, HIF-1α, PI3K/Ak, MicroRNA, Circular RNA, and histone deacetylases, within the context of PND. Targeting NF-κB as a therapeutic approach for PND shows promise as a potential treatment strategy.

CD200-CD200R Pathway: A Regulator of Microglial Polarization in Postoperative Cognitive Dysfunction

Microglial polarization refers to the ability of microglia to exhibit different functional states under various conditions. As the resident immune cells of the brain, changes in the functional state of microglia play a crucial role in the progression of postoperative cognitive dysfunction. Recent studies have indicated that CD200-CD200R signaling is associated with microglial polarization. This review focuses on the latest advancements regarding whether CD200-CD200R signaling can regulate microglial polarization and thereby influence postoperative cognitive dysfunction.

ML365 ameliorates postoperative cognitive impairment in aged mice by inhibiting NLRP3 inflammasome activation in the hippocampus

The aim of this study was to examine the effects of ML365, a two-pore potassium channel (K2P) inhibitor, on postoperative cognitive impairment (POCD). A mouse model of POCD was constructed by subjecting aged C57BL/6 mice to exploratory laparotomy. Changes in cognitive function were assessed using the Morris water maze test. Western blotting and qPCR were used to detect hippocampal NLRP3, Caspase-1 and IL-1β expression levels on days 3 and 7 post-surgery. Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) expression level was also assessed by western blotting. Pathological changes and nerve damage in the hippocampal CA1 and CA3 regions were detected by H&E staining, while the concentration of malondialdehyde (MDA) in the plasma was measured. We found that pretreatment with ML365 (administered intraperitoneally at a dose of 10 mg/kg) 30 min prior to exploratory laparotomy effectively ameliorated POCD in mice. ML365 pretreatment also reduced NLRP3, Caspase-1, ASC and IL-1β expression levels in the hippocampus, improved POCD-induced pathological changes in the hippocampal CA1 and CA3 areas of aged mice, and decreased levels of plasma MDA and oxidative stress. Together, our findings indicate that ML365 can alleviate POCD in mice by inhibiting NLRP3 inflammasome activation in the hippocampus.

miR-206-3p Targets Brain-Derived Neurotrophic Factor and Affects Postoperative Cognitive Function in Aged Mice

Postoperative cognitive dysfunction (POCD) occurs after surgery and severely impairs patients' quality of life. Finding POCD-associated variables can aid in its diagnosis and prognostication. POCD is associated with noncoding RNAs, such as microRNAs (miRNAs), involved in metabolic function, immune response alteration, and cognitive ability impairment; however, the underlying mechanisms remain unclear. The aim of this study was to investigate hub miRNAs (i.e., miRNAs that have an important regulatory role in diseases) regulating postoperative cognitive function and the associated mechanisms. Hub miRNAs were identified by bioinformatics, and their expression in mouse hippocampus tissues was determined using real-time quantitative polymerase chain reaction. Hub miRNAs were overexpressed or knocked down in cell and animal models to test their effects on neuroinflammation and postoperative cognitive function. Six differentially expressed hub miRNAs were identified. miR-206-3p was the only broadly conserved miRNA, and it was used in follow-up studies and animal experiments. Its inhibitors reduced the release of proinflammatory cytokines in BV-2 microglia by regulating its target gene, brain-derived neurotrophic factor (BDNF), and the downstream signaling pathways. miR-206-3p inhibition suppressed microglial activation in the hippocampi of mice and improved learning and cognitive decline. Therefore, miR-206-3p significantly affects POCD, implying its potential as a therapeutic target.

In Silico Exploration of CD200 as a Therapeutic Target for COVID-19

SARS-CoV-2, the pathogen causing COVID-19, continues to pose a significant threat to public health and has had major economic implications. Developing safe and effective vaccines and therapies offers a path forward for overcoming the COVID-19 pandemic. The presented study, performed by using the informational spectrum method (ISM), representing an electronic biology-based tool for analysis of protein-protein interactions, identified the highly conserved region of spike protein (SP) from SARS-CoV-2 virus, which is essential for recognition and targeting between the virus and its protein interactors on the target cells. This domain is suggested as a promising target for the drug therapy and vaccines, which could be effective against all currently circulating variants of SARS-CoV-2 viruses. The analysis of the virus/host interaction, performed by the ISM, also revealed OX-2 membrane glycoprotein (CD200) as a possible interactor of SP, which could serve as a novel therapeutic target for COVID-19 disease.