Stress/cell death pathways, neuroinflammation, and neuropathic pain

Vitexin mitigates AIM2 inflammasome-mediated mitochondrial dysfunction and neuroinflammation in chronic constriction injury induced neuropathy model

The chronic constriction injury (CCI) replicates trauma-induced peripheral neuropathy by increasing oxidative-nitrosative stress, inflammation and mitochondrial dysfunction through compression of the peripheral nerves. Vitexin, a natural flavonoid was investigated for its effect on mitochondrial dysfunction -induced AIM2 inflammasome activation in CCI induced neuropathic pain in rats. The study was conducted through in vitro and in-vivo methods through vitexin treatment to LPS (1.5 μg/mL) exposed SHSY5Y cells as well as over CCI induced SD rats (3 mg/kg/day and 6 mg/kg/day, i.p.,14 days) Neuropathic pain was assessed through several behavioral evaluations. For understating the molecular mechanism, we investigated the impact of vitexin on oxidative stress, mitochondrial dysfunction, and molecular protein expressions. Our studies showed altered behaviour and functional parameters, including hyperalgesia, allodynia, damaged sciatic functions as well as increased oxidative stress, and activation of inflammasomes such as ASC, NF-κB, AIM2, and caspase 1. Furthermore, the expression of SIRT1, SIRT3, PGC-1α, and TFAM was reduced, indicating mitochondrial dysfunction. Treatment with vitexin prevented behavioral hypersensitivity, improved sciatic functions, decreased oxidative stress and inhibited AIM2 associated other inflammasome activation and mitochondrial dysfunction both in-vitro and in-vivo. Vitexin, showed neuroprotective potential by ameliorating mitochondrial dysfunction, and associated AIM2 inflammasome activation in experimental trauma induced neuropathic pain. This research offers a detailed understanding of the mechanisms involved in pathophysiology of CCI induced neuropathic pain and suggest that targeting mitochondrial dysfunction and AIM2 inflammasome may be beneficial in the management of neuropathic pain.

Neuro-Nutritional Approach to Neuropathic Pain Management: A Critical Review

Pain is a significant global public health issue that can interfere with daily activities, sleep, and interpersonal relationships when it becomes chronic or worsens, ultimately impairing quality of life. Despite ongoing efforts, the efficacy of pain treatments in improving outcomes for patients remains limited. At present, the challenge lies in developing a personalized care and management plan that helps to maintain patient activity levels and effectively manages pain. Neuropathic pain is a chronic condition resulting from damage to the somatosensory nervous system, significantly impacting quality of life. It is partly thought to be caused by inflammation and oxidative stress, and clinical research has suggested a link between this condition and diet. However, these links are not yet well understood and require further investigation to evaluate the pathways involved in neuropathic pain. Specifically, the question remains whether supplementation with dietary antioxidants, such as melatonin, could serve as a potential adjunctive treatment for neuropathic pain modulation. Melatonin, primarily secreted by the pineal gland but also produced by other systems such as the digestive system, is known for its anti-inflammatory, antioxidant, and anti-aging properties. It is found in various fruits and vegetables, and its presence alongside other polyphenols in these foods may enhance melatonin intake and contribute to improved health. The aim of this review is to provide an overview of neuropathic pain and examine the potential role of melatonin as an adjunctive treatment in a neuro-nutritional approach to pain management.

Sex Differences in the Regulation of Interleukins in Chronic Pain: A Widely Recognized but Difficult-to-Tackle Factor

Chronic pain is an extremely prevalent healthcare issue that has a profound impact on individuals and society. Sex and sex hormones regulate the pain threshold differently in males and females in pain processing. However, the regulatory mechanisms of sex differences in response to painful stimuli are still unclear, which contributes to the difficulty of analgesic drug development. Interleukins mediate neuroinflammation and are involved in the development of chronic pain. Recent studies have found that sex and sex hormones are involved in the regulation of pain thresholds by interleukins. Most previous studies used male animals to study the analgesic effects of treatments due to the complexity of estrogen. This review summarizes studies that used only female animals or both sexes to examine the impact of sex on interleukin-regulated chronic pain, to provide a theoretical basis for the development of more targeted precision medicines for pain.

Prediction and validation of anoikis-related genes in neuropathic pain using machine learning

BACKGROUND

Neuropathic pain (NP) can be induced by a variety of clinical conditions, such as spinal cord injury, lumbar disc herniation (LDH), lumbar spinal stenosis, diabetes, herpes zoster, and spinal cord tumors, and inflammatory stimuli. The pathogenesis of NP is extremely complex. Specifically, in LDH, the herniated nucleus pulposus exerts mechanical pressure on nerve roots, triggering local inflammation and consequent NP. Anoikis, a special form of programmed cell death, is closely related to the progression of NP. In this study, we sought to clarify the molecular characteristics of anoikis-related genes in NP, providing novel insights for the diagnosis and treatment of NP.

METHODS

We screened NP-related genes based on the GSE124272 dataset and obtained 439 anoikis-related genes from the GeneCards database. Through Least Absolute Shrinkage and Selection Operator (LASSO) and Support Vector Machine (SVM) machine learning algorithms, six key hub genes were identified: hepatocyte growth factor (HGF), matrix metalloproteinase 13 (MMP13), c-abl oncogene 1, non-receptor tyrosine kinase (ABL1), elastase neutrophil expressed (ELANE), fatty acid synthase (FASN), and long non-coding RNA (Linc00324). Functional enrichment analyses, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), alongside Gene Set Enrichment Analysis (GSEA) and immune infiltration analysis, were performed on these hub genes. Additionally, transcription factors and potential therapeutic drugs were predicted. We also used rats to construct an NP model and validated the analyzed hub genes using hematoxylin and eosin (H&E) staining, real-time polymerase chain reaction (PCR), and Western blotting assays.

RESULTS

Our data indicated that anoikis-related genes have diagnostic value in NP patients, as confirmed by experimental results. Moreover, this study elucidated the role of these genes in immune infiltration during the pathogenesis of NP and identified potential therapeutic drugs targeting these key genes.

CONCLUSION

This study further explores the pathogenesis of NP and provides certain reference value for developing targeted therapeutic strategies, thereby improving NP management.

A sustained-release gel alleviates neuropathic pain in SNI mice by reversing Glu/GABA imbalance and chloride efflux disorders

Impaired spinal GABAergic inhibitory neuronal system is one popular target for developing new drugs or procedures for treatment of neuropathic pain, but effective and transferable methods are still lacking. We designed an assembled, temperature sensitive and sustained releasing hydrogel to repair the impaired GABAergic neural system by reversing imbalance of glutamic acid (Glu) and γ-aminobutyric acid (GABA) and healing impaired Cl- extrusion capacity of neurons. Hydrogel solution is a mixture of pluronic F-127, recombinant glutamate decarboxylase 67 (rGAD67) protein and CLP257, a K+-Cl- cotransporter isoform 2 (KCC2) enhancer. The temperature sensitive properties, gel properties and slow-releasing properties of the drug system were determined in vitro. After intrathecal injected in sural spared nerve injury mice model, the hydrogel solution turned into gel, capturing Glu and transforming it into GABA. CLP257 released from gel reversed the suppressed expression of KCC2 in spinal cord, maintaining a low intracellular Cl- concentration in neurons and allowing the normal work of GABA receptors. Combination of rGAD67 and CLP257 showed synergistic effects in alleviating hyperalgesia, altering glia activation, and inhibiting cell apoptosis and inflammatory response. In conclusion, the in situ assembled gel is a long-term effective tool for repairing damaged GABAergic inhibitory system and alleviating neuropathic pain.

TRIM28 Fosters Microglia Ferroptosis via Autophagy Modulation to Enhance Neuropathic Pain and Neuroinflammation

This study explores the molecular underpinnings of neuropathic pain (NPP) and neuroinflammation, focusing on the role of TRIM28 in the regulation of autophagy and microglia ferroptosis. Leveraging transcriptomic data associated with NPP, we identified TRIM28 as a critical regulator of ferroptosis. Through comprehensive analysis, including Gene Ontology enrichment and protein-protein interaction network assessments, we unveiled GSK3B as a downstream target of TRIM28. Experimental validation confirmed the capacity of TRIM28 to suppress GSK3B expression and attenuate autophagic processes in microglia. We probed the consequences of autophagy and ferroptosis on microglia physiology, iron homeostasis, oxidative stress, and the release of proinflammatory cytokines. In a murine model, we validated the pivotal role of TRIM28 in NPP and neuroinflammation. Our analysis identified 20 ferroptosis regulatory factors associated with NPP, with TRIM28 emerging as a central orchestrator. Experimental evidence affirmed that TRIM28 governs microglial iron homeostasis and cell fate by downregulating GSK3B expression and modulating autophagy. Notably, autophagy was found to influence oxidative stress and proinflammatory cytokine release through the iron metabolism pathway, ultimately fueling neuroinflammation. In vivo experiments provided conclusive evidence of TRIM28-mediated pathways contributing to heightened pain sensitivity in neuroinflammatory states. The effect of TRIM28 on autophagy and microglia ferroptosis drives NPP and neuroinflammation. These findings offer promising avenues for identifying novel therapeutic targets to manage NPP and neuroinflammation.

Mitophagy in Cell Death Regulation: Insights into Mechanisms and Disease Implications

Mitophagy, a selective form of autophagy, plays a crucial role in maintaining optimal mitochondrial populations, normal function, and intracellular homeostasis by monitoring and removing damaged or excess mitochondria. Furthermore, mitophagy promotes mitochondrial degradation via the lysosomal pathway, and not only eliminates damaged mitochondria but also regulates programmed cell death-associated genes, thus preventing cell death. The interaction between mitophagy and various forms of cell death has recently gained increasing attention in relation to the pathogenesis of clinical diseases, such as cancers and osteoarthritis, neurodegenerative, cardiovascular, and renal diseases. However, despite the abundant literature on this subject, there is a lack of understanding regarding the interaction between mitophagy and cell death. In this review, we discuss the main pathways of mitophagy, those related to cell death mechanisms (including apoptosis, ferroptosis, and pyroptosis), and the relationship between mitophagy and cell death uncovered in recent years. Our study offers potential directions for therapeutic intervention and disease diagnosis, and contributes to understanding the molecular mechanism of mitophagy.

Transcriptomic insights into pseudorabies virus suppressed cell death pathways in neuroblastoma cells

Pseudorabies virus (PRV) exhibits a complex interplay of host-pathogen interactions, primarily by modulating host cell death pathways to optimize its replication and spread in Neuro-2a cells. Using high-throughput RNA sequencing, we identified 2,382 upregulated differentially expressed genes (DEGs) and 3,998 downregulated DEGs, indicating a intricate interaction between viral pathogenesis and host cellular responses. This research offers valuable insights into the molecular processes involved in PRV infection, highlighting the substantial inhibition of crucial cell death pathways in Neuro-2a cells, including necroptosis, pyroptosis, autophagy, ferroptosis, and cuproptosis. Cells infected with PRV exhibit decreased expression of genes critical in these pathways, potentially as a mechanism to avoid host immune reactions and ensure cell survival to support ongoing viral replication. This extensive inhibition of apoptosis and metabolic alterations highlights the sophisticated tactics utilized by PRV, enhancing our comprehension of herpesvirus biology and the feasibility of creating specific antiviral treatments. This research contributes to our understanding of how viruses manipulate host cell death and presents potential opportunities for therapeutic interventions to disrupt the virus's lifecycle.

A comprehensive review of traditional Chinese medicine in treating neuropathic pain

Neuropathic pain (NP) is a common, intractable chronic pain caused by nerve dysfunction and primary lesion of the nervous system. The etiology and pathogenesis of NP have not yet been clarified, so there is a lack of precise and effective clinical treatments. In recent years, traditional Chinese medicine (TCM) has shown increasing advantages in alleviating NP. Our review aimed to define the therapeutic effect of TCM (including TCM prescriptions, TCM extracts and natural products from TCM) on NP and reveal the underlying mechanisms. Literature from 2018 to 2024 was collected from databases including Web of Science, PubMed, ScienceDirect, Google academic and CNKI databases. Herbal medicine, Traditional Chinese medicines (TCM), neuropathic pain, neuralgia and peripheral neuropathy were used as the search terms. The anti-NP activity of TCM is clarified to propose strategies for discovering active compounds against NP, and provide reference to screen anti-NP drugs from TCM. We concluded that TCM has the characteristics of multi-level, multi-component, multi-target and multi-pathway, which can alleviate NP through various pathways such as anti-inflammation, anti-oxidant, anti-apoptotic pathway, regulating autophagy, regulating intestinal flora, and influencing ion channels. Based on the experimental study and anti-NP mechanism of TCM, this paper can offer analytical evidence to support the effectiveness in treating NP. These references will be helpful to the research and development of innovative TCM with multiple levels and multiple targets. TCM can be an effective treatment for NP and can serve as a treasure house for new drug development.

Cannabidiol alleviates suture-induced corneal pathological angiogenesis and inflammation by inducing myeloid-derived suppressor cells

BACKGROUND

Currently, no perfect treatment for neovascularization and lymphangiogenesis exist, and each treatment method has its complications and side effects. This study aimed to investigate the anti-angiogenic and anti-inflammatory effects of cannabidiol and its mechanism of action.

METHOD

An in vivo corneal neovascularization (CNV) model was established using the suture method to investigate the inhibitory effects of CBD on suture-induced corneal inflammation, pathological blood vessel formation, and lymphangiogenesis. Additionally, the impact of CBD on immune cells was studied. In vitro methodologies, including cell sorting and co-culture, were employed to elucidate its mechanism of action.

RESULTS

Compared with the CNV group, CBD can inhibit CNV, lymphangiogenesis, and inflammation induced via the suture method. In addition, CBD specifically induced CD45+CD11b+Gr-1+ cell upregulation, which significantly inhibited the proliferation of CD4+ T lymphocytes in vitro and exhibited a CD31+ phenotype, proving that they were myeloid-derived suppressor cells (MDSCs). We administered anti-Gr-1 to mice to eliminate MDSCs in vivo and found that anti-Gr-1 partially reversed the anti-inflammatory and angiogenic effects of CBD. Furthermore, we found that compared with MDSCs in the normal group, CBD-induced MDSCs overexpress peroxisome proliferator-activated receptor-gamma (PPAR-γ). Administering PPAR-γ inhibitor in mice almost reversed the induction of MDSCs by CBD, demonstrating the role of PPAR-γ in the function of CBD.

CONCLUSION

This study indicates that CBD may induce MDSCs upregulation by activating the nuclear receptor PPAR-γ, exerting anti-inflammatory, antiangiogenic, and lymphangiogenic effects, and revealing potential therapeutic targets for corneal neovascularization and lymphangiogenesis.

New Insight into Neuropathic Pain: The Relationship between α7nAChR, Ferroptosis, and Neuroinflammation

Neuropathic pain, which refers to pain caused by a lesion or disease of the somatosensory system, represents a wide variety of peripheral or central disorders. Treating neuropathic pain is quite demanding, primarily because of its intricate underlying etiological mechanisms. The central nervous system relies on microglia to maintain balance, as they are associated with serving primary immune responses in the brain next to cell communication. Ferroptosis, driven by phospholipid peroxidation and regulated by iron, is a vital mechanism of cell death regulation. Neuroinflammation can be triggered by ferroptosis in microglia, which contributes to the release of inflammatory cytokines. Conversely, neuroinflammation can induce iron accumulation in microglia, resulting in microglial ferroptosis. Accumulating evidence suggests that neuroinflammation, characterized by glial cell activation and the release of inflammatory substances, significantly exacerbates the development of neuropathic pain. By inhibiting microglial ferroptosis, it may be possible to prevent neuroinflammation and subsequently alleviate neuropathic pain. The activation of the homopentameric α7 subtype of the neuronal nicotinic acetylcholine receptor (α7nAChR) has the potential to suppress microglial activation, transitioning M1 microglia to an M2 phenotype, facilitating the release of anti-inflammatory factors, and ultimately reducing neuropathic pain. Recent years have witnessed a growing recognition of the regulatory role of α7nAChR in ferroptosis, which could be a potential target for treating neuropathic pain. This review summarizes the mechanisms related to α7nAChR and the progress of ferroptosis in neuropathic pain according to recent research. Such an exploration will help to elucidate the relationship between α7nAChR, ferroptosis, and neuroinflammation and provide new insights into neuropathic pain management.

GPX4, ferroptosis, and diseases

GPX4 (Glutathione peroxidase 4) serves as a crucial intracellular regulatory factor, participating in various physiological processes and playing a significant role in maintaining the redox homeostasis within the body. Ferroptosis, a form of iron-dependent non-apoptotic cell death, has gained considerable attention in recent years due to its involvement in multiple pathological processes. GPX4 is closely associated with ferroptosis and functions as the primary inhibitor of this process. Together, GPX4 and ferroptosis contribute to the pathophysiology of several diseases, including sepsis, nervous system diseases, ischemia reperfusion injury, cardiovascular diseases, and cancer. This review comprehensively explores the regulatory roles and impacts of GPX4 and ferroptosis in the development and progression of these diseases, with the aim of providing insights for identifying potential therapeutic strategies in the future.

Implication of lncRNA MSTRG.81401 in Hippocampal Pyroptosis Induced by P2X7 Receptor in Type 2 Diabetic Rats with Neuropathic Pain Combined with Depression

Major depressive disorder (MDD) is a common complication of diabetes and is often observed alongside diabetic neuropathic pain (DNP) as a comorbidity in diabetic patients. Long non-coding RNA (lncRNA) plays an important role in various pathophysiological processes. The P2X7 receptor is responsible for triggering inflammatory responses, such as pyroptosis, linked to pain and depression. The aim of this study was to investigate the effect of lncRNA MSTRG.81401 on hippocampal pyroptosis induced by the P2X7 receptor in diabetic rats with DNP combined with MDD (DNP + MDD). Our results showed that the expression of lncRNA MSTRG.81401 was significantly elevated in the hippocampus of DNP + MDD rats compared with the control group. Following the administration of shRNA targeting lncRNA MSTRG.81401, a notable elevation in mechanical and thermal pain thresholds was observed in rats with comorbid DNP and MDD. Additionally, significant improvements in depression-like behaviors were evident in the open-field test (OFT), sucrose preference test (SPT), and forced swim test (FST). In the DNP + MDD rats, elevated levels in hippocampal P2X7 receptor mRNA and protein were observed, along with increased co-expression of P2X7 and the astrocytic marker glial fibrillary acidic protein (GFAP). Meanwhile, in DNP + MDD rats, the heightened mRNA expression of NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein (ASC), pyroptosis-related protein Gasdermin D (GSDMD), caspase-1, IL-1β, IL-18, and TNF-α was detected, in addition to increased serum levels of IL-1β, IL-18 and TNF-α. After shRNA treatment with lncRNA MSTRG.81401, the above abnormal changes in indicators for pyroptosis and inflammation were improved. Therefore, our study demonstrates that shRNA of lncRNA MSTRG.81401 can alleviate the pain and depression-like behaviors in diabetic rats associated with the comorbidity of DNP and MDD by inhibiting the hippocampal P2X7 receptor-mediated pyroptosis pathway and pro-inflammatory responses. This suggests that the P2X7R/NLRP3/caspase-1 implicated pyroptosis and inflammatory scenario may serve as a potential target for the management of comorbid DNP and MDD in diabetes.

Mitochondrial dysfunction and disulfidptosis co-regulate neuronal cell in neuropathic pain based on bioinformatics analysis

Neuropathic pain (NP) affects approximately 6.9-10% of the world's population and necessitates the development of novel treatments. Mitochondria are essential in the regulation of cell death. Neuroimmune mechanisms are implicated in various forms of cell death associated with NP. However, the specific involvement of mitochondrial dysfunction and disulfidptosis in NP remains uncertain. Further research is required to gain a better understanding of their combined contribution. Our comprehensive study employs a variety of bioinformatic analysis methods, including differential gene analysis, weighted gene co-expression network analysis, machine learning, functional enrichment analysis, immune infiltration, sub-cluster analysis, single-cell dimensionality reduction and cell-cell communication to gain insight into the molecular mechanisms behind these processes. Our study rationally defines a list of key gene sets for mitochondrial dysfunction and disulfidptosis. 6 hub mitochondrial genes and 3 disulfidptosis-related genes (DRGs) were found to be associated with NP. The key genes were predominantly expressed in neurons and were lowly expressed in the NP group compared to SHAM. In addition, our macrophages used the APP (Amyloid precursor protein)-CD74 (MHC class II invariant chain) pathway to interact with neurons. These results suggest that NP is interconnected with the mechanistic processes of mitochondrial dysfunction and disulfidptosis, which may contribute to clinically targeted therapies.

Neuroinflammation and Neurodegenerative Diseases: How Much Do We Still Not Know?

The term "neuroinflammation" defines the typical inflammatory response of the brain closely related to the onset of many neurodegenerative diseases (NDs). Neuroinflammation is well known, but its mechanisms and pathways are not entirely comprehended. Some progresses have been achieved through many efforts and research. Consequently, new cellular and molecular mechanisms, diverse and conventional, are emerging. In listing some of those that will be the subject of our description and discussion, essential are the important roles of peripheral and infiltrated monocytes and clonotypic cells, alterations in the gut-brain axis, dysregulation of the apelinergic system, alterations in the endothelial glycocalyx of the endothelial component of neuronal vascular units, variations in expression of some genes and levels of the encoding molecules by the action of microRNAs (miRNAs), or other epigenetic factors and distinctive transcriptional factors, as well as the role of autophagy, ferroptosis, sex differences, and modifications in the circadian cycle. Such mechanisms can add significantly to understanding the complex etiological puzzle of neuroinflammation and ND. In addition, they could represent biomarkers and targets of ND, which is increasing in the elderly.