Melatonin Attenuates LPS-Induced Acute Depressive-Like Behaviors and Microglial NLRP3 Inflammasome Activation Through the SIRT1/Nrf2 Pathway

The inflammatory underpinning of depression: An historical perspective

Over the last thirty years, substantial evidence has accumulated in support of the hypothesis that dysregulation of inflammatory processes plays a critical role in the pathophysiology of depression. This review traces the evolution of research supporting this link, discussing key findings from several major investigative fronts: Alterations in inflammatory markers associated with depression; Mood changes following the exogenous administration of inflammatory challenges; The anti-inflammatory properties of traditional antidepressants and the promising antidepressant effects of anti-inflammatory drugs. Additionally, it explores how inflammatory processes interact with specific brain regions and neurochemical systems to drive depressive pathology. A thorough analysis of the 100 most-cited experimental studies on the topic ensures a comprehensive, transparent and unbiased collection of references. This methodological approach offers a panoramic view of the inflammation-depression nexus, shedding light on the complexity of its mechanisms and their connections to psychiatric categorizations, symptoms, demographics, and life events. Synthesizing insights from this extensive research, the review presents an integrative model of the biological foundations of inflammation-associated depression. It posits that we have reached a critical juncture where the translation of this knowledge into personalized immunomodulatory treatments for depression is not just possible, but imperative.

P2X7 receptors from the perspective of NLRP3 inflammasome pathway in depression: Potential role of cannabidiol

Many patients with depressive disorder do not respond to conventional antidepressant treatment. There is an ongoing interest in investigating potential mechanisms of treatment resistance in depression to provide alternative treatment options involving inflammatory mechanisms. Increasing evidence implicates the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome as a critical factor in neuroinflammation. ATP-induced P2X7 receptor (P2X7R) activation is a major trigger for inflammation, activating the canonical NLRP3 inflammatory cascade. Psychosocial stress, the primary environmental risk factor for depression, is associated with changes in ATP-mediated P2X7R signaling. Depression and stress response can be alleviated by Cannabidiol (CBD). CBD has an anti-inflammatory activity related to the regulation of NLRP3 inflammasome activation. However, CBD's effects on the inflammasome pathway are poorly understood in central nervous system (CNS) cells, including microglia, astrocytes, and neurons. This review will emphasize some findings for neuroinflammation and NLRP3 inflammasome pathway involvement in depression, particularly addressing the ATP-induced P2X7R activation. Moreover, we will underline evidence for the effect of CBD on depression and address its potential impacts on neuroinflammation through the NLRP3 inflammasome cascade.

The TLR4/NF-κB/NLRP3 and Nrf2/HO-1 pathways mediate the neuroprotective effects of alkaloids extracted from Uncaria rhynchophylla in Parkinson's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is the second most common neurodegenerative disorder with limited therapeutic options available. Neuroinflammation plays an important role in the occurrence and development of PD. Alkaloids extracted from Uncaria rhynchophylla (URA), have emerged as a potential neuroprotective agent because of its anti-inflammatory and anti-oxidant properties. Nevertheless, the underlying mechanism by which URA exerts neuroprotective effects in PD remains obscure.

AIM OF THE STUDY

The main aim of this study was to investigate the neuroprotective effects and underlying mechanism of URA in the treatment of PD through in vivo and in vitro models, focusing on the neuroinflammation and oxidative stress pathways.

MATERIALS AND METHODS

The protective effects of URA against PD were evaluated by neurobehavioral tests, immunohistochemistry, serum biochemical assays, and real-time quantitative polymerase chain reaction in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice. The role of the TLR4/NF-κB/NLRP3 pathway and the Nrf2/HO-1 pathway in URA-mediated effects was examined in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells and a microglia-neuron coculture system.

RESULTS

URA significantly alleviated motor deficits and dopaminergic neurotoxicity, and reversed the abnormal secretion of inflammatory and oxidative stress factors in the serum of MPTP-induced mice. URA suppressed the gene expression of Toll-like receptor 4 (TLR4), NOD-like receptor protein 3, and cyclooxygenase 2 (COX2) in the striatum of PD mice. Further studies indicated that URA inhibited activation of the TLR4/NF-κB/NLRP3 pathway and enhanced activation of the Nrf2/HO-1 pathway, reduced reactive oxygen species (ROS) production, and reversed the secretion of inflammatory mediators in LPS-stimulated BV-2 microglial cells, thereby alleviating neuroinflammatory damage to SH-SY5Y neuronal cells.

CONCLUSION

URA exerted neuroprotective effects against PD mainly by the inhibition of the TLR4/NF-κB/NLRP3 pathway and activation of the Nrf2/HO-1 antioxidant pathway, highlighting URA as a promising candidate for PD treatment.

Resveratrol Ameliorates Retinal Ischemia-Reperfusion Injury by Modulating the NLRP3 Inflammasome and Keap1/Nrf2/HO-1 Signaling Pathway

Glaucoma, as an ischemia-reperfusion (I/R) injury disease, leading irreversible blindness through the loss of retinal ganglion cells (RGCs), mediated by various pathways. Resveratrol (Res) is a polyphenolic compound that exerts protective effects against I/R injury in many tissues. This article aimed to expound the underlying mechanisms through which Res protects RGCs and reduces visual dysfunction in vivo. An experimental glaucoma model was created using 6-8-week wild-type male C57BL/6J mice. Res was injected intraperitoneally for 5 days. The mice were then grouped according to the number of days after surgery and whether Res treatment was administered. We applied the Brn3a-labeled immunofluorescence staining and flash electroretinography (ERG) to assess the survival of RGCs and visual function. The expression of components of the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome, the interleukin-1-beta (IL-1β), and vital indicators of kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme-oxygenase 1 (HO-1) pathway at the protein and RNA levels were detected respectively. The survival of RGCs was reduced after surgery compared to controls, whereas Res application rescued RGCs and improved visual dysfunction. In conclusion, our results discovered that Res administration showed neuroprotective effects through inhibition of the NLRP3 inflammasome pathway and activation of Keap1/Nrf2/HO-1 pathway. Thus, we further elucidated the potential of Res in glaucoma therapy.

Role of sirtuins in sepsis and sepsis-induced organ dysfunction: A review

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis causes a high mortality rate and current treatment focuses on supportive therapies but lacks specific therapeutic targets. Notably, sirtuins (SIRTs) shows potential clinical application in the treatment of sepsis. It has been demonstrated that SIRTs, the nicotinamide adenine dinucleotide+(NAD+)-dependent deacetylases that regulate key signaling pathways in eukaryotes and prokaryotes, are involved in a variety of biological processes. To date, seven mammalian yeast Sir2 homologs have been identified. SIRTs can regulate inflammation, oxidative stress, apoptosis, autophagy, and other pathways that play important roles in sepsis-induced organ dysfunction. However, the existing studies on SIRTs in sepsis are too scattered, and there is no relevant literature to integrate them. This review innovatively summarizes the different mechanisms of SIRTs in sepsis organ dysfunction according to the different systems, and focuses on SIRT agonists, inhibitors, and targeted drugs that have been proved to be effective in the treatment of sepsis, so as to integrate the clinical research and basic research closely. We searched PubMed for all literature related to SIRTs and sepsis since its inception using the following medical subject headings: sirtuins, SIRTs, and sepsis. Data on the mechanisms of SIRTs in sepsis-induced organ damage and their potential as targets for disease treatment were extracted.

Caspase-1 Inhibition Ameliorates Photoreceptor Damage Following Retinal Detachment by Inhibiting Microglial Pyroptosis

Retinal detachment (RD) is a sight-threatening condition that occurs in several retinal diseases. Microglia that reside in retina are activated after RD and play a role in the death of photoreceptor cells. The involvement of microglial pyroptosis in the early pathological process of RD is still unclear. VX-765, an inhibitor of caspase-1, may exert neuroprotective effects by targeting microglial pyroptosis in nervous system disease; however, whether it plays a role in RD is uncertain. This study detected and localized pyroptosis to specific cells by immunofluorescence co-staining and flow cytometry in rat RD models. The majority of gasdermin D N-terminal (GSDMD-N)-positive cells exhibited IBA1-positive or P2RY12-positive microglia in the early stage of RD, indicating the pyroptosis of microglia. Administration of VX-765 shifted the microglia phenotype from M1 to M2, inhibited microglial migration toward the outer nuclear layer (ONL) post-RD, and most importantly, inhibited microglial pyroptosis. The thickness of ONL increased with VX-765 administration, and the photoreceptors were more structured and orderly under hematoxylin and eosin staining and transmission electron microscopy, revealing the protective effects of VX-765 on photoreceptors. Overall, this study demonstrated that inflammation induced by pyroptosis of microglia is the early pathological process of RD. VX-765 may serve as a candidate therapeutic approach for the treatment of RD by targeting microglia.

Targeting Toll-like Receptor 4/Nuclear Factor-κB and Nrf2/Heme Oxygenase-1 Crosstalk via Trimetazidine Alleviates Lipopolysaccharide-Induced Depressive-like Behaviors in Mice

Depression is a global psychiatric illness that imposes a substantial economic burden. Unfortunately, traditional antidepressants induce many side effects which limit patient compliance thus, exploring alternative therapies with fewer adverse effects became urgent. This study aimed to investigate the effect of trimetazidine (TMZ); a well-known anti-ischemic drug in lipopolysaccharide (LPS) mouse model of depression focusing on its ability to regulate toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) as well as nuclear factor erythroid 2 related factor 2 (Nrf2)/ heme oxygenase-1 (HO-1) signaling pathways. Male Swiss albino mice were injected with LPS (500 µg/kg, i.p) every other day alone or parallel with oral doses of either escitalopram (Esc) (10 mg/kg/day) or TMZ (20 mg/kg/day) for 14 days. Treatment with TMZ attenuated LPS-induced animals' despair with reduced immobility time inforced swimming test. TMZ also diminished LPS- induced neuro-inflammation via inhibition of TLR4/NF-κB pathway contrary to Nrf2/HO-1 cascade activation with consequent increase in reduced glutathione (GSH) and HO-1 levels whereas the pro-inflammatory cytokines; tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β were evidently reduced. Besides, TMZ replenished brain serotonin levels via serotonin transporter (SERT) inhibition. Thus, TMZ hindered LPS-induced neuro-inflammation, oxidative stress, serotonin deficiency besides its anti-apoptotic effect which was reflected by decreased caspase-3 level. Neuroprotective effects of TMZ were confirmed by the histological photomicrographs which showed prominent neuronal survival. Here we showed that TMZ is an affluent nominee for depression management via targeting TLR4/NF-κB and Nrf2/HO-1 pathways. Future research addressing TMZ-antidepressant activity in humans is mandatory to enroll it as a novel therapeutic strategy for depression.

Melatonin alleviates LPS-induced depression-like behavior in mice by inhibiting ferroptosis by regulating RNA methylation-mediated SIRT6/Nrf2/HO-1 pathway

PURPOSE

The objective of this study is to investigate the impact of ferroptosis on depression and elucidate the molecular mechanism underlying melatonin's inhibitory effect on ferroptosis in the treatment of depression.

METHODS

In this study, a depression-like behavior model was induced in mice using LPS, and the effect of melatonin on depression-like behavior was evaluated through behavioral experiments (such as forced swimming test (FST) and sucrose preference test (SPT)). Additionally, molecular biological techniques (including real-time fluorescence quantitative PCR, Western blotting, immunoprecipitation) were employed to detect the expression levels and interactions of METTL3, SIRT6 and ferroptosis-related genes in mouse brain tissue. Furthermore, both in vitro and in vivo experiments were conducted to verify the regulatory effect of melatonin on Nrf2/HO-1 pathway and explore its potential molecular mechanism for regulating ferroptosis.

RESULTS

Melatonin was found to significantly ameliorate depression-like behavior in mice, as evidenced by reduced immobility time in the forced swimming test and increased sucrose intake in the sucrose preference test. Subsequent investigations revealed that melatonin modulated SIRT6 stability through METTL3-mediated ubiquitination of SIRT6, leading to its degradation. As a deacetylase, SIRT6 plays a pivotal role in cellular metabolism regulation and antioxidative stress response. This study elucidated potential signaling pathways involving Nrf2/HO-1 through which SIRT6 may exert its effects.

CONCLUSION

The findings suggest that melatonin can improve depressive behavior by suppressing ferroptosis and protecting neurons through its antioxidant properties. Additionally, targeting the Nrf2/HO-1 pathway via METTL3 and NEDD4 regulation may be a potential therapeutic approach for depression.

Green Tea Diet Can Effectively Antagonize the Toxicity Induced by Environmental-Related Concentrations of BPA: An Implication from In Vivo and In Silico Studies

The neurotoxicity of bisphenol A (BPA) exposure has been confirmed in vitro and in vivo, and inflammatory response is considered the main pathway. Green tea is a healthy life habit as it is rich in various anti-inflammatory components. To confirm that green tea diet is an effective measure to antagonize BPA-induced neurotoxicity, mice were treated with 0.5 and 5000 μg/kg/day of BPA from postnatal days (PNDs) 10-50 and supplemented with green tea on PND 21. From PND 51, behavioral tests were conducted on mice to assess their emotional, cognitive, and spatial learning memory capabilities. The open field test and elevated plus maze test indicated anxiety-like behaviors induced by BPA. Interestingly, green tea diet significantly alleviated BPA-induced anxiety-like behaviors. Meanwhile, the green tea diet effectively reversed BPA-induced microglia activation and morphological changes in the hippocampus of mice. Molecularly, green tea inhibited hippocampal neuroinflammation of mice by reducing BPA-induced expressions of NLRP3, ASC, cleaved-caspase-1, GSDMD-N, IL-6, and IL-1β, as well as significantly reducing the expression of Bak1, Bax, caspase-9, and Cytc c genes (p < 0.05). Molecular docking suggests that various anti-inflammatory components of green tea can competitively bind to the estrogen receptors with BPA. In general, a green tea diet alleviates BPA-induced emotional disorders by inhibiting microglial polarization and hippocampal pyroptosis, indicating its effective antagonistic ability against the neurotoxicity induced by environmental BPA exposure.

Galantamine and wedelolactone combined treatment suppresses LPS-induced NLRP3 inflammasome activation in microglial cells

CONTEXT

Inflammasome NLR family pyrin domain-containing 3 (NLRP3) is associated with neurological disorders. Neuroinflammation can be suppressed by inhibiting NLRP3 inflammasome activation, decreasing neurodegenerative disorder progression. We devised a therapeutic technique that can reduce neuroinflammation induced by microglial activation, avoiding neurodegeneration. We aimed to investigate the mechanisms underlying the pharmacological effects of galantamine and wedelolactone by evaluating the response of the nuclear factor kappa B (NF-κB) signaling pathway and NLRP3 inflammasome in lipopolysaccharide (LPS)-activated N9 microglia.

METHODS

LPS and adenosine triphosphate were used to activate the NLRP3 inflammasome in N9 microglial cells, which were pretreated with galantamine and wedelolactone. Caspase-1, NLRP3, NF-κB, and interleukin (IL)-1β levels were measured using RT-qPCR and immunostaining.

RESULTS

Combined administration of galantamine and wedelolactone rescued microglial cells from LPS-induced cell death. Furthermore, treatment with galantamine and wedelolactone led to the suppression of NF-κB expression. NLRP3, caspase-1, and IL-1β levels were decreased by the combined treatment.

DISCUSSION AND CONCLUSION

The concurrent administration of galantamine and wedelolactone effectively suppresses the production of inflammatory cytokines and NLRP3 inflammasome activation in microglia. This inhibitory effect is likely linked to the NF-κB signaling pathway modulation. Therefore, this combined treatment is a potential therapeutic approach for neuroinflammatory diseases.

Intranasal dantrolene nanoparticles inhibit lipopolysaccharide-induced depression and anxiety behavior in mice

This study investigates the therapeutic effectiveness of intranasal dantrolene nanoparticles in the Ryanodex formulation (DNRF) pretreatment to inhibit lipopolysaccharide (LPS)-induced depressive and anxiety behavior in mice. Both wild-type (WT) B6SJLF1/J and 5XFAD adult mice were pretreated with intranasal DNRF (5mg/kg), daily, Monday to Friday, 5 days per week, for 4 weeks. Then, mice were treated with intraperitoneal injection of LPS (5mg/kg) for one time. Behavioral tests for depression and anxiety were performed 24 hours after a one-time LPS injection. Biomarkers for inflammation (IL-1β and IL-18) in blood were measured using enzyme-linked immunosorbent assay (ELISA). In both types of mice, intranasal DNRF significantly inhibited LPS-induced pathological elevation of IL-1β and IL-18 in the blood. Intranasal DNRF abolished LPS-induced depression and anxiety behaviors behavior in both WT and 5XFAD mice, without obvious side effects, which was associated with its significant inhibition of pathological elevation of pyroptosis related cytokines in blood.

Microbiota-immune-brain interactions: A new vision in the understanding of periodontal health and disease

This review highlights the significance of interactions between the microbiota, immune system, nervous and hormonal systems, and the brain on periodontal health and disease. Microorganisms in the microbiota, immune cells, and neurons communicate via homeostatic nervous and hormonal systems, regulating vital body functions. By modulating pro-inflammatory and anti-inflammatory adaptive immune responses, these systems control the composition and number of microorganisms in the microbiota. The strength of these brain-controlled responses is genetically determined but is sensitive to early childhood stressors, which can permanently alter their responsiveness via epigenetic mechanisms, and to adult stressors, causing temporary changes. Clinical evidence and research with humans and animal models indicate that factors linked to severe periodontitis enhance the responsiveness of these homeostatic systems, leading to persistent hyperactivation. This weakens the immune defense against invasive symbiotic microorganisms (pathobionts) while strengthening the defense against non-invasive symbionts at the gingival margin. The result is an increased gingival tissue load of pathobionts, including Gram-negative bacteria, followed by an excessive innate immune response, which prevents infection but simultaneously destroys gingival and periodontal tissues. Thus, the balance between pro-inflammatory and anti-inflammatory adaptive immunity is crucial in controlling the microbiota, and the responsiveness of brain-controlled homeostatic systems determines periodontal health.

Melatonin in animal husbandry: functions and applications

Melatonin (N-acetyl-5-methoxytryptamine) is an essential small molecule with diverse biological functions. It plays several key roles, including regulating the secretion of reproductive hormones and the reproductive cycle, enhancing the functionality of reproductive organs, improving the quality of sperm and eggs, and mitigating oxidative stress in the reproductive system. Melatonin effectively inhibits and scavenges excess free radicals while activating the antioxidant enzyme system and reduces the production of inflammatory factors and alleviates tissue damage caused by inflammation by regulating inflammatory pathways. Additionally, melatonin contributes to repairing the intestinal barrier and regulating the gut microbiota, thereby reducing bacterial and toxin permeation. The use of melatonin as an endogenous hormone in animal husbandry has garnered considerable attention because of its positive effects on animal production performance, reproductive outcomes, stress adaptation, disease treatment, and environmental sustainability. This review explores the characteristics and biological functions of melatonin, along with its current applications in animal production. Our findings may serve as a reference for the use of melatonin in animal farming and future developmental directions.

Microglial NLRP3 inflammasome-mediated neuroinflammation and therapeutic strategies in depression

Previous studies have demonstrated a bidirectional relationship between inflammation and depression. Activation of the nucleotide-binding oligomerization domain, leucine-rich repeat, and NLR family pyrin domain-containing 3 (NLRP3) inflammasomes is closely related to the pathogenesis of various neurological diseases. In patients with major depressive disorder, NLRP3 inflammasome levels are significantly elevated. Understanding the role that NLRP3 inflammasome-mediated neuroinflammation plays in the pathogenesis of depression may be beneficial for future therapeutic strategies. In this review, we aimed to elucidate the mechanisms that lead to the activation of the NLRP3 inflammasome in depression as well as to provide insight into therapeutic strategies that target the NLRP3 inflammasome. Moreover, we outlined various therapeutic strategies that target the NLRP3 inflammasome, including NLRP3 inflammatory pathway inhibitors, natural compounds, and other therapeutic compounds that have been shown to be effective in treating depression. Additionally, we summarized the application of NLRP3 inflammasome inhibitors in clinical trials related to depression. Currently, there is a scarcity of clinical trials dedicated to investigating the applications of NLRP3 inflammasome inhibitors in depression treatment. The modulation of NLRP3 inflammasomes in microglia holds promise for the management of depression. Further investigations are necessary to ascertain the efficacy and safety of these therapeutic approaches as potential novel antidepressant treatments.

β2-adrenoceptor agonist formoterol attenuates NLRP3 inflammasome activation and GSDMD-mediated pyroptosis in microglia through enhancing IκBα/NF-κB inhibition, SQSTM1/p62-dependent selective autophagy and ESCRT-III-mediated plasma membrane repair

Microglia are immune cells that play important roles in the formation of the innate immune response within the central nervous system (CNS). The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a multiple protein complex that is crucial for innate immunity, and excessive activation of the inflammasome for various reasons contributes to the pathogenesis of neurodegenerative diseases (NDs). β2-adrenoceptor agonists have become the focus of attention in studies on NDs due to the high synthesis of β2-adrenoceptors in the central nervous system (CNS). Promising results have been obtained from these studies targeting anti-inflammatory and neuroprotective effects. Formoterol is an effective, safe for long-term use, and FDA-approved β2-adrenoceptor agonist with demonstrated anti-inflammatory features in the CNS. In this study, we researched the effects of formoterol on LPS/ATP-stimulated NLRP3 inflammasome activation, pyroptosis, NF-κB, autophagy, and ESCRT-III-mediated plasma membrane repair pathways in the N9 microglia cells. The results showed that formoterol, through the IκBα/NF-κB axis, significantly inhibited NLRP3 inflammasome activation, reduced the level of active caspase-1, secretion of IL-1β and IL-18 proinflammatory cytokine levels, and the levels of pyroptosis. Additionally, we showed that formoterol activates autophagy, autophagosome formation, and ESCRT-III-mediated plasma membrane repair, which are significant pathways in the inhibition of NLRP3 inflammasome activation and pyroptosis. Our study suggests that formoterol efficaciously prevents the NLRP3 inflammasome activation and pyroptosis in microglial cells regulation through IκBα/NF-κB, autophagy, autophagosome formation, and ESCRT-III-mediated plasma membrane repair.

Pyroptosis in Skeleton Diseases: A Potential Therapeutic Target Based on Inflammatory Cell Death

Skeletal disorders, including fractures, osteoporosis, osteoarthritis, rheumatoid arthritis, and spinal degenerative conditions, along with associated spinal cord injuries, significantly impair daily life and impose a substantial burden. Many of these conditions are notably linked to inflammation, with some classified as inflammatory diseases. Pyroptosis, a newly recognized form of inflammatory cell death, is primarily triggered by inflammasomes and executed by caspases, leading to inflammation and cell death through gasdermin proteins. Emerging research underscores the pivotal role of pyroptosis in skeletal disorders. This review explores the pyroptosis signaling pathways and their involvement in skeletal diseases, the modulation of pyroptosis by other signals in these conditions, and the current evidence supporting the therapeutic potential of targeting pyroptosis in treating skeletal disorders, aiming to offer novel insights for their management.

Nrf2 Signaling Pathway: Focus on Oxidative Stress in Spinal Cord Injury

Spinal cord injury (SCI) is a serious, disabling injury to the central nervous system that can lead to motor, sensory, and autonomic dysfunction below the injury plane. SCI can be divided into primary injury and secondary injury according to its pathophysiological process. Primary injury is irreversible in most cases, while secondary injury is a dynamic regulatory process. Secondary injury involves a series of pathological events, such as ischemia, oxidative stress, inflammatory events, apoptotic pathways, and motor dysfunction. Among them, oxidative stress is an important pathological event of secondary injury. Oxidative stress causes a series of destructive events such as lipid peroxidation, DNA damage, inflammation, and cell death, which further worsens the microenvironment of the injured site and leads to neurological dysfunction. The nuclear factor erythrocyte 2-associated factor 2 (Nrf2) is considered to be a key pathway of antioxidative stress and is closely related to the pathological process of SCI. Activation of this pathway can effectively inhibit the oxidative stress process and promote the recovery of nerve function after SCI. Therefore, the Nrf2 pathway may be a potential therapeutic target for SCI. This review deeply analyzed the generation of oxidative stress in SCI, the role and mechanism of Nrf2 as the main regulator of antioxidant stress in SCI, and the influence of cross-talk between Nrf2 and related pathways that may be involved in the pathological regulation of SCI on oxidative stress, and summarized the drugs and other treatment methods based on Nrf2 pathway regulation. The objective of this paper is to provide evidence for the role of Nrf2 activation in SCI and to highlight the important role of Nrf2 in alleviating SCI by elucidating the mechanism, so as to provide a theoretical basis for targeting Nrf2 pathway as a therapy for SCI.

Geniposide alleviates heart failure with preserved ejection fraction in mice by regulating cardiac oxidative stress via MMP2/SIRT1/GSK3β pathway

Heart failure with preserved ejection fraction (HFpEF) is a complex clinical syndrome with cardiac dysfunction, fluid retention and reduced exercise tolerance as the main manifestations. Current treatment of HFpEF is using combined medications of related comorbidities, there is an urgent need for a modest drug to treat HFpEF. Geniposide (GE), an iridoid glycoside extracted from Gardenia Jasminoides, has shown significant efficacy in the treatment of cardiovascular, digestive and central nervous system disorders. In this study we investigated the therapeutic effects of GE on HFpEF experimental models in vivo and in vitro. HFpEF was induced in mice by feeding with HFD and L-NAME (0.5 g/L) in drinking water for 8 weeks, meanwhile the mice were treated with GE (25, 50 mg/kg) every other day. Cardiac echocardiography and exhaustive exercise were performed, blood pressure was measured at the end of treatment, and heart tissue specimens were collected after the mice were euthanized. We showed that GE administration significantly ameliorated cardiac oxidative stress, inflammation, apoptosis, fibrosis and metabolic disturbances in the hearts of HFpEF mice. We demonstrated that GE promoted the transcriptional activation of Nrf2 by targeting MMP2 to affect upstream SIRT1 and downstream GSK3β, which in turn alleviated the oxidative stress in the hearts of HFpEF mice. In H9c2 cells and HL-1 cells, we showed that treatment with GE (1 μM) significantly alleviated H2O2-induced oxidative stress through the MMP2/SIRT1/GSK3β pathway. In summary, GE regulates cardiac oxidative stress via MMP2/SIRT1/GSK3β pathway and reduces cardiac inflammation, apoptosis, fibrosis and metabolic disorders as well as cardiac dysfunction in HFpEF. GE exerts anti-oxidative stress properties by binding to MMP2, inhibiting ROS generation in HFpEF through the SIRT1/Nrf2 signaling pathway. In addition, GE can also affect the inhibition of the downstream MMP2 target GSK3β, thereby suppressing the inflammatory and apoptotic responses in HFpEF. Taken together, GE alleviates oxidative stress/apoptosis/fibrosis and metabolic disorders as well as HFpEF through the MMP2/SIRT1/GSK3β signaling pathway.

The investigation of relationship between serum melatonin levels with Beck Depression Inventory and Beck Scale for Suicidal Ideation in suicide patients

OBJECTIVE

Melatonin plays a role in many biological and physiological events. There are studies in the literature relating melatonin levels to many psychiatric disorders such as schizophrenia, bipolar disorder, and major depressive disorder. We aimed to investigate the relationship between serum melatonin levels with the Beck Depression Inventory and the Beck Scale for Suicidal Ideation in suicide patients.

METHODS

The study was conducted prospectively with volunteer patients aged 20-50 years who were admitted to the emergency department after a suicide attempt. The social and occupational status, educational levels, marital status, and stressor factors of patients were questioned. Beck Depression Inventory and Beck Scale for Suicidal Ideation were applied to each patient included in the study. Blood melatonin levels were evaluated using the enzyme-linked immunosorbent assay method. The data were analyzed with the SPSS 23.00 statistical program. Descriptive values were expressed by the number of cases (n), percentage (%), median (interquartile range), and mean±standard deviation. The Kolmogorov-Smirnov test was used to assess the distribution of continuous variables, and the Pearson or Spearman correlation test was used to assess the relationship between disease severity and melatonin level. A value of p<0.05 was considered statistically significant.

RESULTS

No statistically significant correlation was found between melatonin level and the Beck Depression Inventory score (r=-0.098, p=0.44). However, a statistically weak, inverse, and significant correlation was discovered between melatonin levels and the Beck Scale for Suicidal Ideation score (r=-0.465, p=0.00).

CONCLUSION

According to our results, it was determined that there was a significant negative relationship between melatonin level and the Beck Scale for Suicidal Ideation scoring.

The Combination of Molecular Hydrogen and Heme Oxygenase 1 Effectively Inhibits Neuropathy Caused by Paclitaxel in Mice

Chemotherapy-provoked peripheral neuropathy and its associated affective disorders are important adverse effects in cancer patients, and its treatment is not completely resolved. A recent study reveals a positive interaction between molecular hydrogen (H2) and a heme oxygenase (HO-1) enzyme inducer, cobalt protoporphyrin IX (CoPP), in the inhibition of neuropathic pain provoked by nerve injury. Nevertheless, the efficacy of CoPP co-administered with hydrogen-rich water (HRW) on the allodynia and emotional disorders related to paclitaxel (PTX) administration has not yet been assessed. Using male C57BL/6 mice injected with PTX, we examined the effects of the co-administration of low doses of CoPP and HRW on mechanical and thermal allodynia and anxiodepressive-like behaviors triggered by PTX. Moreover, the impact of this combined treatment on the oxidative stress and inflammation caused by PTX in the amygdala (AMG) and dorsal root ganglia (DRG) were studied. Our results indicated that the antiallodynic actions of the co-administration of CoPP plus HRW are more rapid and higher than those given by each of them when independently administered. This combination inhibited anxiodepressive-like behaviors, the up-regulation of the inflammasome NLRP3 and 4-hydroxynonenal, as well as the high mRNA levels of some inflammatory mediators. This combination also increased the expression of NRF2, HO-1, superoxide dismutase 1, glutathione S-transferase mu 1, and/or the glutamate-cysteine ligase modifier subunit and decreased the protein levels of BACH1 in the DRG and/or AMG. Thus, it shows a positive interaction among HO-1 and H2 systems in controlling PTX-induced neuropathy by modulating inflammation and activating the antioxidant system. This study recommends the co-administration of CoPP plus HRW as an effective treatment for PTX-provoked neuropathy and its linked emotive deficits.

β-Hydroxybutyrate and melatonin suppress maladaptive UPR, excessive autophagy and pyroptosis in Aβ 1-42 and LPS-Induced SH-SY5Y cells

BACKGROUND

Alzheimer's disease is a neurological disease characterized by the build-up of amyloid beta peptide (Aβ) and lipopolysaccharide (LPS), which causes synapse dysfunction, cell death, and neuro-inflammation. A maladaptive unfolded protein response (UPR), excessive autophagy, and pyroptosis aggravate the disease. Melatonin (MEL) and hydroxybutyrate (BHB) have both shown promise in terms of decreasing Aβ pathology. The goal of this study was to see how BHB and MEL affected the UPR, autophagy, and pyroptosis pathways in Aβ1-42 and LPS-induced SH-SY5Y cells.

MATERIALS AND METHODS

Human neuroblastoma SH-SY5Y cells were treated with BHB, MEL, or a combination of the two after being exposed to A β1-42 and LPS. Cell viability was determined using the MTT test, and gene expression levels of UPR (ATF6, PERK, and CHOP), autophagy (Beclin-1, LC3II, P62, and Atg5), and pyroptosis-related markers (NLRP3, TXNIP, IL-1β, and NFκB1) were determined using quantitative Real-Time PCR (qRT-PCR). For statistical analysis, one-way ANOVA was employed, followed by Tukey's post hoc test.

RESULTS

BHB and MEL significantly increased SH-SY5Y cell viability in the presence of A β1-42 and LPS. Both compounds inhibited the expression of maladaptive UPR and autophagy-related genes, as well as inflammatory and pyroptotic markers caused by Aβ1-42 and LPS-induced SH-SY5Y cells.

CONCLUSION

BHB and MEL rescue neurons in A β1-42 and LPS-induced SH-SY5Y cells by reducing maladaptive UPR, excessive autophagy, and pyroptosis. More research is needed to fully comprehend the processes behind their beneficial effects and to discover their practical applications in the treatment of neurodegenerative disorders.

Knocking out Selenium Binding Protein 1 Induces Depressive-Like Behavior in Mice

Selenium binding protein 1 (SELENBP1) is involved in neurologic disorders, such as multiple sclerosis, spinal cord injury, Parkinson's disease, epilepsy, and schizophrenia. However, the role of SELENBP1 in the neurogenesis of depression, which is a neurologic disorder, and the underlying mechanisms of oxidative stress and inflammation in depression remain unknown. In this study, we evaluated the changes in the expression levels of SELENBP1 in the hippocampus of a mouse model of depression and in the serum of human patients with depression using the Gene Expression Omnibus database. These changes were validated using blood samples from human patients with depression and mouse models with chronic unpredictable mild stress (CUMS)-induced depressive-like behavior. We also investigated the effects of SELENBP1 knockout (KO) on inflammation, oxidative stress, and hippocampal neurogenesis in mice with CUMS-induced depression. Our results revealed that SELENBP1 levels was decreased in the blood of human patients with depression and in the hippocampus of mice with CUMS-induced depression. SELENBP1 KO increased CUMS-induced depressive behavior in mice and caused dysregulation of inflammatory cytokines and oxidative stress. This led to a decrease in the numbers of doublecortin- and Ki67-positive cells, which might aggravate CUMS-induced depressive symptoms. These findings suggest that SELENBP1 might be involved in the regulation of neurogenesis in mice with depression and could be served as a potential target for diagnosing and treating depression.

P2Y6 Receptor Activation Aggravates NLRP3-dependent Microglial Pyroptosis via Downregulation of the PI3K/AKT Pathway in a Mouse Model of Intracerebral Hemorrhage

Pro-inflammatory signals generated after intracerebral hemorrhage (ICH) trigger a form of regulated cell death known as pyroptosis in microglia. White matter injury (WMI) refers to the condition where the white matter area of the brain suffers from mechanical, ischemic, metabolic, or inflammatory damage. Although the p2Y purinoceptor 6 (P2Y6R) plays a significant role in the control of inflammatory reactions in central nervous system diseases, its roles in the development of microglial pyroptosis and WMI following ICH remain unclear. In this study, we sought to clarify the role of P2Y6R in microglial pyroptosis and WMI by using an experimental mouse model of ICH. Type IV collagenase was injected into male C57BL/6 mice to induce ICH. Mice were then treated with MRS2578 and LY294002 to inhibit P2Y6R and phosphatidylinositol 3-kinase (PI3K), respectively. Bio-conductivity analysis was performed to examine PI3K/AKT pathway involvement in microglial pyroptosis. Quantitative Real-Time PCR, immunofluorescence staining, and western blot were conducted to examine microglial pyroptosis and WMI following ICH. A modified Garcia test, corner turning test, and forelimb placement test were used to assess neurobehavior. Hematoxylin-eosin staining (HE) was performed to detect cells damage around hematoma. Increases in the expression of P2Y6R, NLRP3, ASC, Caspase-1, and GSDMD were observed after ICH. P2Y6R was only expressed on microglia. MRS2578, a specific inhibitor of P2Y6R, attenuated short-term neurobehavioral deficits, brain edema and hematoma volume while improving both microglial pyroptosis and WMI. These changes were accompanied by decreases in pyroptosis-related proteins and pro-inflammatory cytokines both in vivo and vitro. Bioinformatic analysis revealed an association between the PI3K/AKT pathway and P2Y6R-mediated microglial pyroptosis. The effects of MRS2578 were partially reversed by treatment with LY294002, a specific PI3K inhibitor. P2Y6R inhibition alleviates microglial pyroptosis and WMI and ameliorates neurological deficits through the PI3K/AKT pathway after ICH. Consequently, targeting P2Y6R might be a promising approach for ICH treatment.

Escherichia coli K88 activates NLRP3 inflammasome-mediated pyroptosis in vitro and in vivo

Pyroptosis induced by lipopolysaccharide (LPS) has an obvious impact on intestinal inflammation and immune regulation. Enterotoxigenic Escherichia coli (ETEC) K88 has been proved to induce inflammatory responses in several models, but whether E. coli K88 participates in the same process of pyroptotic cell death as LPS remains to be identified. We conducted a pilot experiment to confirm that E. coli K88, instead of Escherichia coli O157 and Salmonella typhimurium, promotes the secretion of interleukin-1 beta (IL-1β) and interleukin-18 (IL-18) in macrophages. Further experiments were carried out to dissect the molecular mechanism both in vitro and in vivo. The Enzyme-Linked Immunosorbent Assay (ELISA) results suggested that E. coli K88 treatment increased the expression of pro-inflammatory cytokines IL-18 and IL-1β in both C57BL/6 mice and the supernatant of J774A.1 cells. Intestinal morphology observations revealed that E. coli K88 treatment mainly induced inflammation in the colon. Real-time PCR and Western blot analysis showed that the mRNA and protein expressions of pyroptosis-related factors, such as NLRP3, ASC, and Caspase1, were significantly upregulated by E. coli K88 treatment. The RNA-seq results confirmed that the effect was associated with the activation of NLRP3, ASC, Caspase1, GSDMD, IL-18, and IL-1β, and might also be related to inflammatory bowel disease and the tumor necrosis factor pathway. The pyroptosis-activated effect of E. coli K88 was significantly blocked by NLRP3 siRNA. Our data suggested that E. coli K88 caused inflammation by triggering pyroptosis, which provides a theoretical basis for the prevention and treatment of ETEC in intestinal infection.

Gut microbiota dysbiosis contributes to depression-like behaviors via hippocampal NLRP3-mediated neuroinflammation in a postpartum depression mouse model

Postpartum depression (PPD) is a severe mental disorder that affects approximately 10---20% of women after childbirth. The precise mechanism underlying PPD pathogenesis remains elusive, thus limiting the development of therapeutics. Gut microbiota dysbiosis is considered to contribute to major depressive disorder. However, the associations between gut microbiota and PPD remain unanswered. Here, we established a mouse PPD model by sudden ovarian steroid withdrawal after hormone-simulated pseudopregnancy-human (HSP-H) in ovariectomy (OVX) mouse. Ovarian hormone withdrawal induced depression-like and anxiety-like behaviors and an altered gut microbiota composition. Fecal microbiota transplantation (FMT) from PPD mice to antibiotic cocktail-treated mice induced depression-like and anxiety-like behaviors and neuropathological changes in the hippocampus of the recipient mice. FMT from healthy mice to PPD mice attenuated the depression-like and anxiety-like behaviors as well as the inflammation mediated by the NOD-like receptor protein (NLRP)-3/caspase-1 signaling pathway both in the gut and the hippocampus, increased fecal short-chain fatty acids (SCFAs) levels and alleviated gut dysbiosis with increased SCFA-producing bacteria and reduced Akkermansia in the PPD mice. Also, downregulation of NLRP3 in the hippocampus mitigated depression-like behaviors in PPD mice and overexpression of NLRP3 in the hippocampal dentate gyrus induced depression-like behaviors in naïve female mice. Intriguingly, FMT from healthy mice failed to alleviate depression-like behaviors in PPD mice with NLRP3 overexpression in the hippocampus. Our results highlighted the NLRP3 inflammasome as a key component within the microbiota-gut-brain axis, suggesting that targeting the gut microbiota may be a therapeutic strategy for PPD.

Cannabidiol prevents LPS-induced inflammation by inhibiting the NLRP3 inflammasome and iNOS activity in BV2 microglia cells via CB2 receptors and PPARγ

Neuroinflammation stands as a critical player in the pathogenesis of diverse neurological disorders, with microglial cells playing a central role in orchestrating the inflammatory landscape within the central nervous system. Cannabidiol (CBD) has gained attention for its potential to elicit anti-inflammatory responses in microglia, offering promising perspectives for conditions associated with neuroinflammation. Here we investigated whether the NLRP3 inflammasome and inducible nitric oxide synthase (iNOS) are involved in the protective effects of CBD, and if their modulation is dependent on cannabinoid receptor 2 (CB2) and PPARγ signalling pathways. We found that treatment with CBD attenuated pro-inflammatory markers in lipopolysaccharide (LPS)-challenged BV2 microglia in a CB2- and PPARγ-dependent manner. At a molecular level, CBD inhibited the LPS-induced pro-inflammatory responses by suppressing iNOS and NLRP3/Caspase-1-dependent signalling cascades, resulting in reduced nitric oxide (NO), interleukin-1β (IL-1β), and tumour necrosis factor-alpha (TNF-α) concentrations. Notably, the protective effects of CBD on NLRP3 expression, Caspase-1 activity, and IL-1β concentration were partially hindered by the antagonism of both CB2 receptors and PPARγ, while iNOS expression and NO secretion were dependent exclusively on PPARγ activation, with no CB2 involvement. Interestingly, CBD exhibited a protective effect against TNF-α increase, regardless of CB2 or PPARγ activation. Altogether, these findings indicate that CB2 receptors and PPARγ mediate the anti-inflammatory effects of CBD on the NLRP3 inflammasome complex, iNOS activity and, ultimately, on microglial phenotype. Our results highlight the specific components responsible for the potential therapeutic applications of CBD on neuroinflammatory conditions.

Intestinal Metabolism of Crocin and a Pharmacokinetics and Pharmacodynamics Study in the Chronic Social Defeat Stress Mouse Model

Orally administered crocin rapidly and efficiently rescues depressive-like behaviors in depression models; however, crocin levels in the circulatory and central nervous systems are rather low. The underlying mechanism responsible for the inconsistency between pharmacokinetics and pharmacodynamics is unknown. To identify the active metabolites and clarify the underlying mechanisms, the pharmacokinetics and metabolic effects of the gut flora and hepatic and intestinal microsomes on crocin were examined, and the pharmacodynamics of crocin and its major metabolite, crocetin, were also evaluated in both normal and pseudo germ-free mice subjected to chronic social defeat stress. The results showed that oral administration of 300 mg/kg crocin significantly improved the depression-like behaviors of chronic social defeat stress mice, although the levels of crocin in the circulatory system were rather low (Cmax = 43.5 ± 8.6 μg/L; AUC = 151 ± 20.8 μg·h/L). However, the primary metabolite of crocetin was much more abundant in vivo (Cmax = 4662.5 ± 586.1 μg/L; AUC = 33,451.9 ± 3323.6 μg·h/L). Orally administered crocin was primarily metabolized into crocetin by the gut flora instead of hepatic or intestinal microsomal enzymes, and less than 10% of crocin was transformed into crocetin in the liver or intestinal microsomes. Inhibition of the gut flora dramatically reduced the production of and in vivo exposure to crocetin, and the rapid antidepressant effect of crocin disappeared. Moreover, crocetin showed rapid antidepressant effects similar to those of crocin, and the effects were independent of the gut flora. In conclusion, the metabolic transformation of crocin to crocetin primarily contributes to the rapid antidepressant effects of crocin and is dependent on the gut flora.

Melatonin Delays Arthritis Inflammation and Reduces Cartilage Matrix Degradation through the SIRT1-Mediated NF-κB/Nrf2/TGF-β/BMPs Pathway

Cartilage, a flexible and smooth connective tissue that envelops the surfaces of synovial joints, relies on chondrocytes for extracellular matrix (ECM) production and the maintenance of its structural and functional integrity. Melatonin (MT), renowned for its anti-inflammatory and antioxidant properties, holds the potential to modulate cartilage regeneration and degradation. Therefore, the present study was devoted to elucidating the mechanism of MT on chondrocytes. The in vivo experiment consisted of three groups: Sham (only the skin tissue was incised), Model (using the anterior cruciate ligament transection (ACLT) method), and MT (30 mg/kg), with sample extraction following 12 weeks of administration. Pathological alterations in articular cartilage, synovium, and subchondral bone were evaluated using Safranin O-fast green staining. Immunohistochemistry (ICH) analysis was employed to assess the expression of matrix degradation-related markers. The levels of serum cytokines were quantified via Enzyme-linked immunosorbent assay (ELISA) assays. In in vitro experiments, primary chondrocytes were divided into Control, Model, MT, negative control, and inhibitor groups. Western blotting (WB) and Quantitative RT-PCR (q-PCR) were used to detect Silent information regulator transcript-1 (SIRT1)/Nuclear factor kappa-B (NF-κB)/Nuclear factor erythroid-2-related factor 2 (Nrf2)/Transforming growth factor-beta (TGF-β)/Bone morphogenetic proteins (BMPs)-related indicators. Immunofluorescence (IF) analysis was employed to examine the status of type II collagen (COL2A1), SIRT1, phosphorylated NF-κB p65 (p-p65), and phosphorylated mothers against decapentaplegic homolog 2 (p-Smad2). In vivo results revealed that the MT group exhibited a relatively smooth cartilage surface, modest chondrocyte loss, mild synovial hyperplasia, and increased subchondral bone thickness. ICH results showed that MT downregulated the expression of components related to matrix degradation. ELISA results showed that MT reduced serum inflammatory cytokine levels. In vitro experiments confirmed that MT upregulated the expression of SIRT1/Nrf2/TGF-β/BMPs while inhibiting the NF-κB pathway and matrix degradation-related components. The introduction of the SIRT1 inhibitor Selisistat (EX527) reversed the effects of MT. Together, these findings suggest that MT has the potential to ameliorate inflammation, inhibit the release of matrix-degrading enzymes, and improve the cartilage condition. This study provides a new theoretical basis for understanding the role of MT in decelerating cartilage degradation and promoting chondrocyte repair in in vivo and in vitro cultured chondrocytes.

L- lactate inhibits lipopolysaccharide-induced inflammation of microglia in the hippocampus

Objective: Depression is a common psychological and physiological disease in the world, which seriously affects the quality of life of patients and families. Exercise is an economic and noninvasive antidepressant measure, which has been widely recognized and applied in daily life and clinical practice, and the related mechanism research has also been paid attention to. In recent years, a new research report pointed out that peripheral administration of L-lactate can reverse depression-like behavior in mice, which suggesting that the lactic acid produced during exercise may be one of the factors leading to antidepressant effect, but the detailed mechanism is not clear. Inflammation is the pathogenic factor of many diseases and a large number of experiments have proved that inflammation is also an important pathogenic factor leading to depression. The purpose of our experiment is to explore whether lactic acid has anti-inflammatory and antidepressant effects.Methods: Based on the LPS induced inflammatory model, animal behavior observation, protein extraction, Western blotting, immunofluorescence and other techniques were used in this experiment.Results: Lactic acid could inhibit the change of some important inflammatory factors, such as TNF-αIL-1βphospho-NF-κB (p-NF-κB) and NLRP3 inflammasome complex (NLRP3/ASC/caspase-1) induced by LPS.Conclusion: Our current research suggested that lactic acid maybe exert antiinflammatory effect by inhibiting inflammatory factors.

Propofol modulates Nrf2/NLRP3 signaling to ameliorate cigarette smoke-induced damage in human bronchial epithelial cells

Cigarette smoke extract (CSE) is known as a significant contributor to chronic obstructive pulmonary disease (COPD). Propofol, an anesthetic agent, has been studied for its potential protective effects against lung damage. This study aimed to elucidate the protective mechanisms of propofol against CSE-induced damage in human bronchial epithelial 16HBE cells. In CSE-induced 16HBE cells treated by propofol with or without transfection of nuclear factor erythroid 2-related factor 2 (Nrf2) interference plasmids, CCK-8 assay and lactate dehydrogenase (LDH) assay evaluated cytotoxicity. TUNEL assay and Western blot appraised cell apoptosis. ELISA and relevant assay kits severally measured inflammatory and oxidative stress levels. DCFH-DA fluorescent probe detected intracellular reactive oxygen species (ROS) activity. Immunofluorescence staining and Western blot estimated pyroptosis. Also, Western blot analyzed the expression of Nrf2/NLR family pyrin domain containing 3 (NLRP3) signaling-related proteins. Propofol was found to enhance the viability, reduce LDH release, and alleviate the apoptosis, inflammatory response, oxidative stress and pyroptosis in CSE-induced 16HBE cells in a concentration-dependent manner. Meanwhile, propofol decreased NLRP3 expression while raised Nrf2 expression. Further, after Nrf2 was silenced, the impacts of propofol on Nrf2/NLRP3 signaling, LDH release, apoptosis, inflammatory response, oxidative stress and pyroptosis in CSE-exposed 16HBE cells were eliminated. Conclusively, propofol may exert protective effects against CSE-induced damage in 16HBE cells, partly through the modulation of the Nrf2/NLRP3 signaling pathway, suggesting a potential therapeutic role for propofol in CSE-induced bronchial epithelial cell damage.

Modulation of neural circuits by melatonin in neurodegenerative and neuropsychiatric disorders

Neurodegenerative and neuropsychiatric disorders are two broad categories of neurological disorders characterized by progressive impairments in movement and cognitive functions within the central and peripheral nervous systems, and have emerged as a significant cause of mortality. Oxidative stress, neuroinflammation, and neurotransmitter imbalances are recognized as prominent pathogenic factors contributing to cognitive deficits and neurobehavioral anomalies. Consequently, preventing neurodegenerative and neuropsychiatric diseases has surfaced as a pivotal challenge in contemporary public health. This review explores the investigation of neurodegenerative and neuropsychiatric disorders using both synthetic and natural bioactive compounds. A central focus lies on melatonin, a neuroregulatory hormone secreted by the pineal gland in response to light-dark cycles. Melatonin, an amphiphilic molecule, assumes multifaceted roles, including scavenging free radicals, modulating energy metabolism, and synchronizing circadian rhythms. Noteworthy for its robust antioxidant and antiapoptotic properties, melatonin exhibits diverse neuroprotective effects. The inherent attributes of melatonin position it as a potential key player in the pathophysiology of neurological disorders. Preclinical and clinical studies have demonstrated melatonin's efficacy in alleviating neuropathological symptoms across neurodegenerative and neuropsychiatric conditions (depression, schizophrenia, bipolar disorder, and autism spectrum disorder). The documented neuroprotective prowess of melatonin introduces novel therapeutic avenues for addressing neurodegenerative and psychiatric disorders. This comprehensive review encompasses many of melatonin's applications in treating diverse brain disorders. Despite the strides made, realizing melatonin's full neuroprotective potential necessitates further rigorous clinical investigations. By unravelling the extended neuroprotective benefits of melatonin, future studies promise to deepen our understanding and augment the therapeutic implications against neurological deficits.

Potential Neuroprotective Effect of Melatonin in the Hippocampus of Male BTBR Mice

Autism spectrum disorder (ASD) is a neurodevelopmental disorder identified by impairments in common social interactions and repetitive behaviors. In ASD patients, substantial morphological alterations have been observed in the hippocampus, which represents an important region for the development of social skills. Melatonin, commonly found in many foods and plants, is also produced by the pineal gland. This indolamine, known to regulate the circadian rhythm, shows antioxidant and anti-inflammatory properties. We therefore hypothesized that melatonin may reduce oxidative stress and inflammation in the hippocampus of ASD patients. We explored our hypothesis using the BTBR mouse, a well-regarded murine transgenic model for ASD. Immediately after weaning, male BTBR and C57BL/6 mice underwent an 8-week treatment with melatonin or vehicle. Later, through immunohistochemistry and the immunoblotting analysis of the hippocampus, we evaluated the overall expression and cellular localization of Nrf2 and SOD1, two enzymes involved in the oxidative stress response. Similarly, we evaluated NLRP3 and NFkB, two mediators of inflammation, and GAD67, an enzyme responsible for the synthesis of GABA. Ultimately, we addressed melatonin's potential to regulate iron metabolism through a DAB-enhanced Perls reaction assay. Results showed melatonin's potential for modulating the analyzed markers in BTBR mice, suggesting a potential neuroprotective effect in ASD patients.

Depression and Eye Disease-A Narrative Review of Common Underlying Pathophysiological Mechanisms and their Potential Applications

Background: Depression has been shown to be associated with eye diseases, including dry eye disease (DED), cataracts, glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy (DR). This narrative review explores potential pathophysiological connections between depression and eye disease, as well as its potential correlations with ocular parameters. Methods: A literature search was conducted in August 2022 in PUBMED, EMBASE, and PsycINFO. Published articles related to the subject were consolidated and classified according to respective eye diseases and pathophysiological mechanisms. Results: The literature reviewed suggests that common pathophysiological states like inflammation and neurodegeneration may contribute to both depression and certain eye diseases, while somatic symptoms and altered physiology, such as disruptions in circadian rhythm due to eye diseases, can also influence patients' mood states. Grounded in the shared embryological, anatomical, and physiological features between the eye and the brain, depression is also correlated to changes observed in non-invasive ophthalmological imaging modalities, such as changes in the retinal nerve fibre layer and retinal microvasculature. Conclusions: There is substantial evidence of a close association between depression and eye diseases. Understanding the underlying concepts can inform further research on treatment options and monitoring of depression based on ocular parameters.

Exploring the pathophysiological influence of heme oxygenase-1 on neuroinflammation and depression: A study of phytotherapeutic-based modulation

BACKGROUND

The heme oxygenase (HO) system plays a significant role in neuroprotection and reduction of neuroinflammation and neurodegeneration. The system, via isoforms HO-1 and HO-2, regulates cellular redox balance. HO-1, an antioxidant defense enzyme, is highlighted due to its association with depression, characterized by heightened neuroinflammation and impaired oxidative stress responses.

METHODOLOGY

We observed the pathophysiology of HO-1 and phytochemicals as its modulator. We explored Science Direct, Scopus, and PubMed for a comprehensive literature review. Bibliometric and temporal trend analysis were done using VOSviewer.

RESULTS

Several phytochemicals can potentially alleviate neuroinflammation and oxidative stress-induced depressive symptoms. These effects result from inhibiting the MAPK and NK-κB pathways - both implicated in the overproduction of pro-inflammatory factors - and from the upregulation of HO-1 expression mediated by Nrf2. Bibliometric and temporal trend analysis further validates these associations.

CONCLUSION

In summary, our findings suggest that antidepressant agents can mitigate neuroinflammation and depressive disorder pathogenesis via the upregulation of HO-1 expression. These agents suppress pro-inflammatory mediators and depressive-like symptoms, demonstrating that HO-1 plays a significant role in the neuroinflammatory process and the development of depression.

Potential antidepressant effects of Traditional Chinese botanical drug formula Chaihu-Shugan-San and its active ingredients

Background: Depression is a severe mental disorder that poses a significant threat to both the physical and mental wellbeing of individuals. Currently, there are various methods for treating depression, including traditional Chinese herbal formulations like Chaihu-Shugan-San (CSS), which have shown effective antidepressant effects in both clinical and animal research. Objective: This review aims to provide a comprehensive synthesis of evidence related to CSS, considering both preclinical and clinical studies, to uncover its potential multi-level, multi-pathway, and multi-target mechanisms for treating depression and identify its active ingredients. Methods: A thorough search was conducted in electronic databases, including PubMed, MEDLINE, Web of Science, Google Scholar, CNKI, and Wanfang, using keywords such as "Chaihu Shugan" and "depression" to retrieve relevant literature on CSS and its active ingredients. The review process adhered to the PRISMA guidelines. Results: This review consolidates the mechanisms underlying antidepressant effects of CSS and its active ingredients. It emphasizes its involvement in the regulation of monoaminergic neurotransmitter systems, synaptic plasticity, and the hypothalamic-pituitary-adrenal axis, among other aspects. Conclusion: CSS exerts a pivotal role in treating depression through various pathways, including the monoaminergic neurotransmitter system, the hypothalamic-pituitary-adrenal axis, synaptic plasticity, inflammation, brain-derived neurotrophic factor levels, and the brain-gut axis. This review facilitates a comprehensive understanding of the current state of CSS research, fostering an in-depth exploration of the etiological mechanisms of depression and the potential discovery of novel antidepressant drugs.

Decoupling the mutual promotion of inflammation and oxidative stress mitigates cognitive decline and depression-like behavior in rmTBI mice by promoting myelin renewal and neuronal survival

BACKGROUND

Repetitive mild traumatic brain injury (rmTBI) can lead to somatic, emotional, and cognitive symptoms that persist for years after the initial injury. Although the ability of various treatments to promote recovery after rmTBI has been explored, the optimal time window for early intervention after rmTBI is unclear. Previous research has shown that hydrogen-rich water (HRW) can diffuse through the blood-brain - barrier, attenuate local oxidative stress, and reduce neuronal apoptosis in patients with severe traumatic brain injury. However, research on the effect of HRW on rmTBI is scarce.

AIMS

The objectives of this study were to explore the following changes after rmTBI and HRW treatment: (i) temporal changes in inflammasome activation and oxidative stress-related protein expression through immunoblotting, (ii) temporal changes in neuron/myelin-related metabolite concentrations in vivo through magnetic resonance spectroscopy, (iii) myelin structural changes in late-stage rmTBI via immunofluorescence, and (iv) postinjury anxiety/depression-like behaviors and spatial learning and memory impairment.

RESULTS

NLRP-3 expression in the rmTBI group was elevated at 7 and 14 DPI, and inflammasome marker levels returned to normal at 30 DPI. Oxidative stress persisted throughout the first month postinjury. HRW replacement significantly decreased Nrf2 expression in the prefrontal cortex and hippocampal CA2 region at 14 and 30 DPI, respectively. Edema and local gliosis in the hippocampus and restricted diffusion in the thalamus were observed on MR-ADC images. The tCho/tCr ratio in the rmTBI group was elevated, and the tNAA/tCr ratio was decreased at 30 DPI. Compared with the mice in the other groups, the mice in the rmTBI group spent more time exploring the open arms in the elevated plus maze (P < 0.05) and were more active in the maze (longer total distance traveled). In the sucrose preference test, the rmTBI group exhibited anhedonia. In the Morris water maze test, the latency to find the hidden platform in the rmTBI group was longer than that in the sham and HRW groups (P < 0.05).

CONCLUSION

Early intervention with HRW can attenuate inflammasome assembly and reduce oxidative stress after rmTBI. These changes may restore local oligodendrocyte function, promote myelin repair, prevent axonal damage and neuronal apoptosis, and alleviate depression-like behavior and cognitive impairment.

Mechanically tough, adhesive, self-healing hydrogel promotes annulus fibrosus repair via autologous cell recruitment and microenvironment regulation

Annulus fibrosus (AF) defect is an important cause of disc re-herniation after discectomy. The self-regeneration ability of the AF is limited, and AF repair is always hindered by the inflammatory microenvironment after injury. Hydrogels represent one of the most promising materials for AF tissue engineering strategies. However, currently available commercial hydrogels cannot withstand the harsh mechanical load within intervertebral disc. In the present study, an innovative triple cross-linked oxidized hyaluronic acid (OHA)-dopamine (DA)- polyacrylamide (PAM) composite hydrogel, modified with collagen mimetic peptide (CMP) and supplied with transforming growth factor beta 1 (TGF-β1) (OHA-DA-PAM/CMP/TGF-β1 hydrogel) was developed for AF regeneration. The hydrogel exhibited robust mechanical strength, strong bioadhesion, and significant self-healing capabilities. Modified with collagen mimetic peptide, the hydrogel exhibited extracellular-matrix-mimicking properties and sustained the AF cell phenotype. The sustained release of TGF-β1 from the hydrogel was pivotal in recruiting AF cells and promoting extracellular matrix production. Furthermore, the composite hydrogel attenuated LPS-induced inflammatory response and promote ECM synthesis in AF cells via suppressing NFκB/NLRP3 pathway. In vivo, the composite hydrogel successfully sealed AF defects and alleviated intervertebral disk degeneration in a rat tail AF defect model. Histological evaluation showed that the hydrogel integrated well with host tissue and facilitated AF repair. The strategy of recruiting endogenous cells and providing an extracellular-matrix-mimicking and anti-inflammatory microenvironment using the mechanically tough composite OHA-DA-PAM/CMP/TGF-β1 hydrogel may be applicable for AF defect repair in the clinic. STATEMENT OF SIGNIFICANCE: Annulus fibrosus (AF) repair is challenging due to its limited self-regenerative capacity and post-injury inflammation. In this study, a mechanically tough and highly bioadhesive triple cross-linked composite hydrogel, modified with collagen mimetic peptide (CMP) and supplemented with transforming growth factor beta 1 (TGF-β1), was developed to facilitate AF regeneration. The sustained release of TGF-β1 enhanced AF cell recruitment, while both TGF-β1 and CMP could modulate the microenvironment to promote AF cell proliferation and ECM synthesis. In vivo, this composite hydrogel effectively promoted the AF repair and mitigated the intervertebral disc degeneration. This research indicates the clinical potential of the OHA-DA-PAM/CMP/TGF-β1 composite hydrogel for repairing AF defects.

LPS priming-induced immune tolerance mitigates LPS-stimulated microglial activation and social avoidance behaviors in mice

In this study, we investigated the regulatory mechanisms underlying the effects of LPS tolerance on the inflammatory homeostasis of immune cells. LPS priming-induced immune tolerance downregulated cyclooxygenase-2, and lowered the production of prostaglandin-E2 in microglial cells. In addition, LPS tolerance downregulated the expression of suppressor of cytokine signaling 3, and inducible nitric oxide synthase/nitric oxide; suppressed the LPS-mediated induction of tumor necrosis factor-α, interleukin (IL)-6, and IL-1; and reduced reactive oxygen species production in microglial cells. LPS stimulation increased the levels of the adaptive response-related proteins heme oxygenase-1 and superoxide dismutase 2, and the levels of heme oxygenase-1 (HO-1) enhanced after LPS priming. Systemic administration of low-dose LPS (0.5 mg/kg) to mice for 4 consecutive days attenuated high-dose LPS (5 mg/kg)-induced inflammatory response, microglial activation, and proinflammatory cytokine expression. Moreover, repeated exposure to low-dose LPS suppressed the recruitment of peripheral monocytes or macrophages to brain regions and downregulated the expression of proinflammatory cytokines. Notably, LPS-induced social avoidance behaviors in mice were mitigated by immune tolerance. In conclusion, immune tolerance may reduce proinflammatory cytokine expression and reactive oxygen species production. Our findings provide insights into the effects of endotoxin tolerance on innate immune cells and social behaviors.

Cynaroside improved depressive-like behavior in CUMS mice by suppressing microglial inflammation and ferroptosis

Depression is a common mental health disorder, and in recent years, the incidence of various forms of depression has been on the rise. Most medications for depression are highly dependency-inducing and can lead to relapse upon discontinuation. Therefore, novel treatment modalities and therapeutic targets are urgently required. Traditional Chinese medicine (TCM) offers advantages in the treatment of depression owing to its multi-target, multi-dimensional approach that addresses the root cause of depression by regulating organ functions and balancing Yin and Yang, with minimal side effects. Cynaroside (CNS), an extract from the traditional Chinese herb honeysuckle, is a flavonoid compound with antioxidant properties. In this study, network pharmacology identified 44 potential targets of CNS associated with depression and several highly correlated inflammatory signaling pathways. CNS alleviated LPS-induced M1 polarization and the release of inflammatory factors in BV-2 cells. Transcriptomic analysis and validation revealed that CNS reduced inflammatory polarization, lipid peroxidation, and ferroptosis via the IRF1/SLC7A11/GPX4 signaling pathway. In vivo experiments showed that CNS treatment had effects similar to those of fluoxetine (FLX). It effectively ameliorated anxiety-, despair-, and anhedonia-like states in chronic unpredictable mild stress (CUMS)-induced mice and reduced microglial activation in the hippocampus. Thus, we conclude that CNS exerts its therapeutic effect on depression by inhibiting microglial cells from polarizing into the M1 phenotype and reducing inflammation and ferroptosis levels. This study provides further evidence that CNS is a potential antidepressant, offering new avenues for the treatment of depression.

Inhibition of xanthine oxidase by allopurinol suppresses HMGB1 secretion and ameliorates experimental asthma

BACKGROUND

Extracellular high mobility group box 1 (HMGB1) is a key mediator in driving allergic airway inflammation and contributes to asthma. Yet, mechanism of HMGB1 secretion in asthma is poorly defined. Pulmonary metabolic dysfunction is recently recognized as a driver of respiratory pathology. However, the altered metabolic signatures and the roles of metabolic to allergic airway inflammation remain unclear.

METHODS

Male C57BL/6 J mice were sensitized and challenged with toluene diisocyanate (TDI) to generate a chemically induced asthma model. Pulmonary untargeted metabolomics was employed. According to results, mice were orally administered allopurinol, a xanthine oxidase (XO) inhibitor. Human bronchial epithelial cells (16HBE) were stimulated by TDI-human serum albumin (HSA).

RESULTS

We identified the purine metabolism was the most enriched pathway in TDI-exposed lungs, corresponding to the increase of xanthine and uric acid, products of purine degradation mediated by XO. Inhibition of XO by allopurinol ameliorates TDI-induced oxidative stress and DNA damage, mixed granulocytic airway inflammation and Th1, Th2 and Th17 immunology as well as HMGB1 acetylation and secretion. Mechanistically, HMGB1 acetylation was caused by decreased activation of the NAD+-sirtuin 1 (SIRT1) axis triggered by hyperactivation of the DNA damage sensor poly (ADP-ribose)-polymerase 1 (PARP-1). This was rescued by allopurinol, PARP-1 inhibitor or supplementation with NAD+ precursor in a SIRT1-dependent manner. Meanwhile, allopurinol attenuated Nrf2 defect due to SIRT1 inactivation to help ROS scavenge.

CONCLUSIONS

We demonstrated a novel regulation of HMGB1 acetylation and secretion by purine metabolism that is critical for asthma onset. Allopurinol may have therapeutic potential in patients with asthma.

The role of ncRNAs in depression

Depressive disorders have a significant impact on public health, and depression have an unsatisfactory recurrence rate and are challenging to treat. Non-coding RNAs (ncRNAs) are RNAs that do not code protein, which have been shown to be crucial for transcriptional regulation. NcRNAs are important to the onset, progress and treatment of depression because they regulate various physiological functions. This makes them distinctively useful as biomarkers for diagnosing and tracking responses to therapy among individuals with depression. It is important to seek out and summarize the research findings on the impact of ncRNAs on depression since significant advancements have been made in this area recently. Hence, we methodically outlined the findings of published researches on ncRNAs and depression, focusing on microRNAs. Above all, this review aims to improve our understanding of ncRNAs and provide new insights of the diagnosis and treatment of depression.

Melatonin Enhanced Microglia M2 Polarization in Rat Model of Neuro-inflammation Via Regulating ER Stress/PPARδ/SIRT1 Signaling Axis

Neuro-inflammation involves distinct alterations of microglial phenotypes, containing nocuous pro-inflammatory M1-phenotype and neuroprotective anti-inflammatory M-phenotype. Currently, there is no effective treatment for modulating such alterations. M1/M2 marker of primary microglia influenced by Melatonin were detected via qPCR. Functional activities were explored by western blotting, luciferase activity, EMSA, and ChIP assay. Structure interaction was assessed by molecular docking and LIGPLOT analysis. ER-stress detection was examined by ultrastructure TEM, calapin activity, and ERSE assay. The functional neurobehavioral evaluations were used for investigation of Melatonin on the neuroinflammation in vivo. Melatonin had targeted on Peroxisome Proliferator Activated Receptor Delta (PPARδ) activity, boosted LPS-stimulated alterations in polarization from the M1 to the M2 phenotype, and thereby inhibited NFκB-IKKβ activation in primary microglia. The PPARδ agonist L-165,041 or over-expression of PPARδ plasmid (ov-PPARδ) showed similar results. Molecular docking screening, dynamic simulation approaches, and biological studies of Melatonin showed that the activated site was located at PPARδ (phospho-Thr256-PPARδ). Activated microglia had lowered PPARδ activity as well as the downstream SIRT1 formation via enhancing ER-stress. Melatonin, PPARδ agonist and ov-PPARδ all effectively reversed the above-mentioned effects. Melatonin blocked ER-stress by regulating calapin activity and expression in LPS-activated microglia. Additionally, Melatonin or L-165,041 ameliorated the neurobehavioral deficits in LPS-aggravated neuroinflammatory mice through blocking microglia activities, and also promoted phenotype changes to M2-predominant microglia. Melatonin suppressed neuro-inflammation in vitro and in vivo by tuning microglial activation through the ER-stress-dependent PPARδ/SIRT1 signaling cascade. This treatment strategy is an encouraging pharmacological approach for the remedy of neuro-inflammation associated disorders.

Phoenixin 20 ameliorates pulmonary arterial hypertension via inhibiting inflammation and oxidative stress

Pulmonary arterial hypertension (PAH) is a severe pathophysiological syndrome resulting in heart failure, which is found to be induced by pulmonary vascular remodeling mediated by oxidative stress (OS) and inflammation. Phoenixin-20 (PNX-20) is a reproductive peptide first discovered in mice with potential suppressive properties against OS and inflammatory response. Our study will explore the possible therapeutic functions of PHN-20 against PAH for future clinical application. Rats were treated with normal saline, PHN-20 (100 ng/g body weight daily), hypoxia, hypoxia+PHN-20 (100 ng/g body weight daily), respectively. A signally elevated RVSP, mPAP, RV/LV + S, and W%, increased secretion of cytokines, enhanced malondialdehyde (MDA) level, repressed superoxide dismutase (SOD) activity, and activated NLRP3 signaling were observed in hypoxia-stimulated rats, which were notably reversed by PHN-20 administration. Pulmonary microvascular endothelial cells (PMECs) were treated with hypoxia with or without PHN-20 (10 and 20 nM). Marked elevation of inflammatory cytokine secretion, increased MDA level, repressed SOD activity, and activated NLRP3 signaling were observed in hypoxia-stimulated PMECs, accompanied by a downregulation of SIRT1. Furthermore, the repressive effect of PHN-20 on the domains-containing protein 3 (NLRP3) pathway in hypoxia-stimulated PMECs was abrogated by sirtuin1 (SIRT1) knockdown. Collectively, PHN-20 alleviated PAH via inhibiting OS and inflammation by mediating the transcriptional function of SIRT1.

Platycodon D protects human nasal epithelial cells from pyroptosis through the Nrf2/HO-1/ROS signaling cascade in chronic rhinosinusitis

BACKGROUND

Pyroptosis has been demonstrated being closely associated with the inflammatory progression in chronic rhinosinusitis (CRS). However, platycodon D (PLD) has emerged as a key anti-inflammatory mediator in the inflammatory progression of various respiratory diseases. This study aims at investigating whether PLD could reduce inflammatory progression of CRS by inhibiting pyroptosis.

METHODS

Nasal mucosal tissues from patients with CRS and the control group (simple nasal septal deviation) were analyzed for morphological difference using hematoxylin & eosin staining and for the expression of pyroptosis-related makers by immunofluorescence (IF). Human nasal epithelial cells (HNEpCs) were cultured and co-stimulated with lipopolysaccharide (LPS)/adenosine triphosphate (ATP) to construct an in vitro cellular model simulating CRS. After pretreatment with PLD, EthD-I staining, TUNEL staining, transmission electron microscopy (TEM), and GSDMD-NT detection were performed to evaluate pyroptosis markers. The NLRP3 inflammasome was detected by IF and western blotting (WB). Reactive oxygen species (ROS) were detected by H2DCFDA staining, and mitochondrial membrane potential was evaluated by JC-1 staining. Mitochondrial morphology and structure were observed using TEM. The Nrf2/HO-1 antioxidant signaling pathway was detected using WB.

RESULTS

The nasal mucosa structure of patients with CRS exhibited significant damage, with a marked increase in the expression of pyroptosis-related proteins compared with the control group. LPS/ATP co-stimulation resulted in an increased expression of IL-18 and IL-1β in HNEpCs, causing significant damage to nuclear and cell membranes, GSDMD-NT accumulation around the cell membrane, and intracellular NLRP3 inflammasome activation. Furthermore, it led to increased ROS expression, significantly decreased mitochondrial membrane potential, and damaged mitochondrial structure. However, pretreatment with PLD significantly reversed the aforementioned trends and activated the Nrf2/HO-1 antioxidant signaling pathway.

CONCLUSIONS

The results of this study confirm that NLRP3-mediated pyroptosis plays a crucial role in the pathological process of nasal mucosal impairment in patients with CRS. PLD inhibits NLRP3-mediated pyroptosis, preventing inflammatory damage in HNEpCs of patients with CRS by activating the Nrf2/HO-1 antioxidant signaling pathway, which in turn reduces ROS production and ameliorates mitochondrial damage.

Low-dose Esketamine suppresses NLRP3-mediated apoptotic and pyroptotic cell death in microglial cells to ameliorate LPS-induced depression via ablating GSK-3β

Esketamine is verified as a potential therapeutic drug for the treatment of depression, but it is still unclear the detailed underlying mechanisms by which Esketamine ameliorates depression-related symptoms, which seriously limits the utilization of this drug in clinical practices. In this study, the C57BL6/J mice and mouse primary microglial cells were subjected to lipopolysaccharide (LPS)-induced depressive models in vivo and in vitro, and our results confirmed that LPS-induced neuroinflammation, pyroptotic and apoptotic death contributed to the development of LPS-induced depressive symptoms. Then, the following experiments verified that low-dose Esketamine treatment decreased the expression levels of IL-6, TNF-α and IL-18 to restrain cellular inflammation, downregulated NLRP3, cleaved Caspase-1, IL-1β and GSDMD-N to hamper pyroptotic cell death, and inhibited cleaved caspase-3 and Bax, but upregulated Bcl-2 to restrict apoptotic cell death in the LPS-treated mice hippocampus tissues and mouse microglial cells, leading to the suppression of depression development. However, high-dose Esketamine did not have those effects. Next, by conducting mechanical experiments, we verified that low-dose Esketamine downregulated GSK-3β to inactivate NLRP3 inflammasome, and the effects of low-dose Esketamine on cell pyroptosis, neuroinflammation and apoptosis in the LPS-treated microglial cells were all abrogated by overexpressing GSK-3β and NLRP3. Taken together, low-dose Esketamine ameliorated LPS-induced depressive symptoms in mice through regulating the GSK-3β/NLRP3 pathway, and our work suggested that appropriate doses of Esketamine were essential for the treatment of depression in clinic.

PD protects Müller cells through the SIRT1/NLRP3 inflammasome pathway

PURPOSE

Polydatin (PD) has widely pharmacological activities. However, the effects of PD on high glucose (HG)-induced Müller cells in diabetic retinopathy (DR) are rarely studied.

METHODS

The protective effects of PD were evaluated in HG-induced human retinal Müller cells. The levels of pro-angiogenic factors and pro-inflammatory factors were detected using the ELISA kits. The expressions of nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing-3 (NLRP3) and sirtuin-1 (SIRT1) were determined by western blot.

RESULTS

PD inhibited proliferation and activation of HG-induced MIO-M1 cells. PD treatment reduced the levels of pro-angiogenic factors, pro-inflammatory factors, and oxidative stress, while these effects were attenuated by NLRP3 agonist ATP in HG-induced MIO-M1 cells. Furthermore, PD inhibited the activation of NLRP3 inflammasome by regulating the SIRT1 expression after HG stimulation, and knockdown of SIRT1 reversed the inhibition effects of PD on NLRP3 inflammasome, pro-angiogenic factors, pro-inflammatory factors, and oxidative stress in HG-induced MIO-M1 cells.

CONCLUSION

PD may inhibit HG-induced Müller cells proliferation and activation and suppress pro-angiogenic factors, pro-inflammatory factors, and oxidative stress through the SIRT1/NLRP3 inflammasome pathway. In summary, PD treatment may be an effective therapeutic strategy for DR.

Apolipoprotein C3 (ApoC3) facilitates NLRP3 mediated pyroptosis of macrophages through mitochondrial damage by accelerating of the interaction between SCIMP and SYK pathway in acute lung injury

Respiratory failure caused by severe acute lung injury (ALI) is the main cause of mortality in patients with COVID-19.This study aimed to investigate the effects and underlying biological mechanism of Apolipoprotein C3 (ApoC3) in ALI. To establish an in vivo model, C57BL/6 mice were exposed by lipopolysaccharide (LPS). For the in vitro model, murine bone marrow-derived macrophages (BMDMs) or RAW264.7 cells were stimulated with LPS + adenosine triphosphate (ATP). Serum levels of ApoC3 were found to be upregulated in patients with COVID-19 or pneumonia-induced ALI. Inhibition of ApoC3 reduced lung injury in an ALI model, while overexpression of ApoC3 promoted lung injury. ApoC3 induced mitochondrial damage-mediated pyroptosis in ALI through the activation of the NOD-like receptorprotein 3 (NLRP3) inflammasome. ApoC3 recombinant protein significantly increased SCIMP expression in the lung tissue of mice models with ALI. ApoC3 also facilitated the interaction between the SLP adapter and CSK-interacting membrane protein (SCIMP) protein and Spleen tyrosine kinase (SYK) protein in the ALI model. Moreover, ApoC3 accelerated calcium-dependent reactive oxygen species (ROS) production in the ALI model. The effects of ApoC3 on pyroptosis were mitigated by the use of a pyroptosis inhibitor or an ROS inhibitor in the ALI model. Furthermore, ApoC3 activated the expression of SYK, which in turn induced NLRP3 inflammasome-regulated pyroptosis in the ALI model. METTL3 was found to mediate the m6A mRNA expression of ApoC3. Overall, our study highlights the crucial role of ApoC3 in promoting macrophage pyroptosis in ALI through calcium-dependent ROS production and NLRP3 inflammasome activation via the SCIMP-SYK pathway, providing a potential therapeutic strategy for ALI and other inflammatory diseases.

Fucoidan modulates SIRT1 and NLRP3 to alleviate hypertensive retinopathy: in vivo and in vitro insights

BACKGROUND

Hypertension influences the inflammatory pathological changes in the retina. The function of the inflammasomes is significant. To see if Sirtuin 1 (SIRT1) regulates angiotensin II (Ang II)-induced hypertensive retinopathy and inflammation by modulating NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome activation and the potential protective effects of fucoidan (FO) in mouse retinal vascular endothelial cells (mRECs) and mice retina.

METHODS

The diagnosis of hypertensive retinopathy was made after three weeks of Ang II infusion (3000 ng/kg/min). One day prior to the commencement of Ang II infusion, the mice were treatment with NLRP3 inhibitor MCC950 (10 mg/kg/day, intraperitoneal injections) or FO (300 mg/kg/day, oral gavage). A blood pressure was recorded. Hematoxylin and eosin (H&E) staining was used to conduct pathological alterations, dihydroethidium bromide (DHE) was utilized to assess oxidative stress damage in the retina, and fluorescence angiography was used to identify vascular disorders in the eye. Using immunohistochemical labeling, NLRP3 expression was found. Reactive protein and mRNA expression levels in mouse retina and cells were assessed using Western blot and real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

NLRP3 inflammasome activation and SIRT1 decrease were brought about by Ang II infusion. Retinopathy and dysfunction were lessened by MCC950 target-induced NLRP3 inflammasome activation, while overexpression of SIRT1 had the opposite impact on NLRP3 inflammasome activation, indicating that SIRT1 functions as an upstream regulator of NLRP3 activity. FO may improve SIRT1 expression and decrease NLRP3 activation in retinopathy and dysfunction brought on by Ang II, and the effects were consistent across both in vivo and in vitro models.

CONCLUSIONS

SIRT1 adversely regulates the NLRP3 inflammasome pathway, which in turn increases Ang II-induced inflammation and hypertensive retinopathy. FO may mitigate Ang II-induced retinopathy and dysfunction via modulating the expression of SIRT1/NLRP3. This implies practical approaches to the management of hypertensive retinopathy.

Inflammasome modulation with P2X7 inhibitor A438079-loaded dressings for diabetic wound healing

The inflammasome is a multiprotein complex critical for the innate immune response to injury. Inflammasome activation initiates healthy wound healing, but comorbidities with poor healing, including diabetes, exhibit pathologic, sustained activation with delayed resolution that prevents healing progression. In prior work, we reported the allosteric P2X7 antagonist A438079 inhibits extracellular ATP-evoked NLRP3 signaling by preventing ion flux, mitochondrial reactive oxygen species generation, NLRP3 assembly, mature IL-1β release, and pyroptosis. However, the short half-life in vivo limits clinical translation of this promising molecule. Here, we develop a controlled release scaffold to deliver A438079 as an inflammasome-modulating wound dressing for applications in poorly healing wounds. We fabricated and characterized tunable thickness, long-lasting silk fibroin dressings and evaluated A438079 loading and release kinetics. We characterized A438079-loaded silk dressings in vitro by measuring IL-1β release and inflammasome assembly by perinuclear ASC speck formation. We further evaluated the performance of A438079-loaded silk dressings in a full-thickness model of wound healing in genetically diabetic mice and observed acceleration of wound closure by 10 days post-wounding with reduced levels of IL-1β at the wound edge. This work provides a proof-of-principle for translating pharmacologic inhibition of ATP-induced inflammation in diabetic wounds and represents a novel approach to therapeutically targeting a dysregulated mechanism in diabetic wound impairment.

Major depressive disorder: hypothesis, mechanism, prevention and treatment

Worldwide, the incidence of major depressive disorder (MDD) is increasing annually, resulting in greater economic and social burdens. Moreover, the pathological mechanisms of MDD and the mechanisms underlying the effects of pharmacological treatments for MDD are complex and unclear, and additional diagnostic and therapeutic strategies for MDD still are needed. The currently widely accepted theories of MDD pathogenesis include the neurotransmitter and receptor hypothesis, hypothalamic-pituitary-adrenal (HPA) axis hypothesis, cytokine hypothesis, neuroplasticity hypothesis and systemic influence hypothesis, but these hypothesis cannot completely explain the pathological mechanism of MDD. Even it is still hard to adopt only one hypothesis to completely reveal the pathogenesis of MDD, thus in recent years, great progress has been made in elucidating the roles of multiple organ interactions in the pathogenesis MDD and identifying novel therapeutic approaches and multitarget modulatory strategies, further revealing the disease features of MDD. Furthermore, some newly discovered potential pharmacological targets and newly studied antidepressants have attracted widespread attention, some reagents have even been approved for clinical treatment and some novel therapeutic methods such as phototherapy and acupuncture have been discovered to have effective improvement for the depressive symptoms. In this work, we comprehensively summarize the latest research on the pathogenesis and diagnosis of MDD, preventive approaches and therapeutic medicines, as well as the related clinical trials.