Autophagy dysfunction contributes to NLRP1 inflammasome-linked depressive-like behaviors in mice

AKT/mTOR mediated autophagy contributes to the self-replication of canine influenza virus in vivo and in vitro

The prevalence and spread of canine influenza virus (CIV) pose a threat to the health of dogs and humans. Some studies have shown that autophagy is closely related to virus replication, but the exact relationship between CIV replication and autophagy is still unclear. Therefore, this study investigated the effects of autophagy on CIV replication in vitro and in vivo. The data showed that CIV infection significantly caused respiratory tract damage in mice, upregulated the mRNA/protein levels of CIV replication-related genes and autophagy-related genes. In addition, the activation of autophagy by rapamycin (Rapa) significantly intensified the CIV replication and the respiratory tract damage of mice, while the inhibition of autophagy by 3-Methyladenine (3-MA) significantly alleviated these effects. Data of MDCK cells also demonstrated that CIV promoted self-replication through activating autophagy, and the upregulation of AKT/mTOR by insulin significantly inhibited the CIV replication. In summary, this study showed that CIV could promote self-replication by activating AKT/mTOR mediated autophagy, which provides new ideas for the prevention and treatment of canine influenza.

Polysaccharides from Scrophularia ningpoensis Hemsl. improve reserpine-induced depression-like behavior by inhibiting HTR2A/HTR2C mediated AKT/GSK3β/β-catenin/CBP/BDNF signalling

Scrophularia ningpoensis Hemsl. is a traditional Chinese medicine used to regulate blood sugar levels, immunity, etc. We previously isolated polysaccharides from S. ningpoensis Hemsl. (SNPS) and innovatively observed that SNPS exhibit antidepressant properties; however, the underlying mechanism is still unclear. Here, we employed network pharmacology to predict the potential targets and antidepressant mechanism of SNPS. Accordingly, we detected the effects of SNPS on monoamine neurotransmitter synthesis, metabolism, receptor expression and signal transduction in reserpine (RES)-treated mice using ELISA, HPLC-electrochemistry, metabonomics, Golgi-Cox staining and Western blotting. Finally, the mechanism of SNPS on key targets (HTR2A and HTR2C) was verified in vivo and in vitro. Results showed that SNPS ameliorated depression by restoring monoamine neurotransmitter homeostasis and hippocampal neurogenesis. SNPS reversed the depletion of 5-HT, NE and DA by activating the tryptophan (Trp)/5-HT and tyrosine (Tyr)/DA/NE metabolic pathways. SNPS decreased HTR2A and HTR2C contents, leading to the phosphorylation of AKT and GSK3β, followed by increases in β-catenin, CBP and BDNF levels. Mechanistically, SNPS reduced the levels of HTR2A and HTR2C proteins by inhibiting their mRNA transcription, rather than inducing protein degradation. In conclusion, by inhibiting the transcription of HTR2A and HTR2C, SNPS activated the AKT/GSK3β/β-catenin/CBP/BDNF pathway, thereby exerting dose-dependent antidepressant effects.

Combination of rTMS and oxytocin agonist attenuate depression-like behavior after postpartum depression in mice

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) categorizes postpartum depression (PPD) as a subtype of Major Depressive Disorder (MDD) with peripartum onset, generally arising within the initial trimester following delivery. This acute psychiatric condition is characterized by feelings of worthlessness, insomnia, extreme anxiety, or maternal neglect. Intranasal oxytocin (OT) and transcranial magnetic stimulation (TMS) have the potential to address impaired social cognition; nonetheless, their neuronal underpinnings, along with their safety and efficacy, are little comprehended. This study examines the effects of rTMS stimulation with an oxytocin agonist or antagonist in a PPD model. We employed the maternal separation with early weaning (MSEW) strategy for 21 days to attain our objective. Oxytocin acetate (agonist) and atosiban (antagonist) were administered by injection twice daily for three consecutive days following the model according to the established protocol. A single session of rTMS involved the application of high-frequency stimulation (20 Hz) one hour following the final injection. Behavioral testing and brain collection were conducted 12 h post-rTMS. The results indicated that treatment with OT followed by rTMS stimulation decreased neuronal cell death and microglial activation, meanwhile enhancing synaptic plasticity through the upregulation of PSD95, Synapsin I, and Synaptophysin. Simultaneously, both OT therapy and repetitive transcranial magnetic stimulation demonstrated a significant capacity to alter autophagy activity and astrocyte function. Nonetheless, OTA therapy followed by rTMS did not exhibit the same pattern of outcomes. Our findings indicate that the combination of rTMS stimulation and an oxytocin agonist in a PPD model may mitigate depression-like behavior.

Modulation of autophagy by melatonin and its receptors: implications in brain disorders

Autophagy plays a crucial role in maintaining neuronal homeostasis and function, and its disruption is linked to various brain diseases. Melatonin, an endogenous hormone that primarily acts through MT1 and MT2 receptors, regulates autophagy via multiple pathways. Growing evidence indicates that melatonin's ability to modulate autophagy provides therapeutic and preventive benefits in brain disorders, including neurodegenerative and affective diseases. In this review, we summarize the key mechanisms by which melatonin affects autophagy and explore its therapeutic potential in the treatment of brain disorders.

Role of sirtuin 1 in depression‑induced coronary heart disease: Molecular pathways and therapeutic potential (Review)

Depression and coronary heart disease (CHD) are two interconnected diseases that profoundly impact global health. Depression is both a complex psychiatric disorder and an established risk factor for CHD. Sirtuin 1 (SIRT1) is an enzyme that requires the cofactor nicotinamide adenine dinucleotide (NAD+) to perform its deacetylation function, and its involvement is crucial in reducing cardiovascular risks that are associated with depression. SIRT1 exerts its cardioprotective effects via modulating oxidative stress, inflammation and metabolic processes, all of which are central to the pathogenesis of CHD in individuals with depression. Through influencing these pathways, SIRT1 helps to reduce endothelial dysfunction, prevent the formation of atherosclerotic plaques and stabilize existing plaques, thereby decreasing the overall risk of CHD. The present review underscores the important role of SIRT1 in serving as a therapeutic intervention molecule for tackling cardiovascular complications stemming from depression. Furthermore, it highlights the need for further studies to clarify how SIRT1 influences both depression and CHD at the molecular level. The ultimate goal of this research will be to translate these findings into practical clinical intervention strategies.

Mechanism of action of Panax ginseng alcohol extract based on orexin-mediated autophagy in the treatment of sleep and cognition in aged sleep-deprived rats

ETHNOPHARMACOLOGICAL RELEVANCE

Panax ginseng (P. ginseng) C. A. Meyer. has been used extensively globally as a medicine. It has a therapeutic effect on sleep and is an attractive alternative for patients with insomnia. The United States Patent of Invention has approved the use of P. ginseng alcohol extract (GAE) in nutraceuticals or food to improve sleep. It has shown promise as an effective therapeutic agent for improving sleep and cognition. However, its mechanism of action is not yet fully understood.

AIM OF THE STUDY

To investigate the therapeutic benefits of GAE on sleep and cognition and its underlying mechanism in aged sleep-deprived rats, with a focus on orexin-mediated autophagy function.

MATERIALS AND METHODS

We conducted in vivo tests in an aged sleep-deprivation rat model produced using p-chlorophenylalanine (PCPA) coupled with modified multi-platform method to examine the therapeutic effects and mechanisms of GAE. A pentobarbital sodium-induced sleep test and water maze were used to assess sleep and cognitive performance, respectively. An enzyme-linked immunosorbent assay was used to determine orexin levels and aging and sleep markers in serum and hypothalamic tissues. Hematoxylin-eosin staining and Nissl staining were used to assess histopathological changes, and autophagy levels were assessed using transmission electron microscopy, immunofluorescence. Western blot and immunohistochemical staining were performed to detect the levels of orexin, orexin-receptor proteins, and autophagy-associated proteins to study the effects of GAE on hippocampal neurons, and the underlying mechanisms.

RESULTS

In aged sleep-deprived rats, GAE treatment prolonged sleep duration, improved cognitive function, prevented hippocampal neuronal damage, increased the number of Nissl bodies, improved aging and sleep markers, and enhanced the LC3A/B expression in autophagosomes and neurons. The amount of orexin in serum and hypothalamic tissue and OX1R, OX2R, and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) proteins also reduced, which resulted in the inhibition of the PI3K/Akt/mTOR pathway and activation of the autophagy process.

CONCLUSIONS

GAE may reduce hypothalamic orexin secretion and interact with orexin receptors to inhibit the PI3K/Akt/mTOR signalling network and activate autophagy. This may be a potential mechanism of action of GAE in regulating sleep-related cognitive function.

Exogenous L-fucose attenuates depression induced by chronic unpredictable stress: Implicating core fucosylation has an antidepressant potential

Core fucosylation is one of the most essential modifications of the N-glycans, catalyzed by α1,6-fucosyltransferase (Fut8), which transfers fucose from guanosine 5'-diphosphate (GDP)-fucose to the innermost N-acetylglucosamine residue of N-glycans in an α1-6 linkage. Our previous studies demonstrated that lipopolysaccharide (LPS) can induce a more robust neuroinflammatory response in Fut8 homozygous knockout (KO) (Fut8-/-) and heterozygous KO (Fut8+/-) mice contrasted to the wild-type (Fut8+/+) mice. Exogenous administration of L-fucose suppressed LPS-induced neuroinflammation. Numerous studies indicate that neuroinflammation plays a vital role in the development of depression. Here, we investigated whether core fucosylation regulates depression induced by chronic unpredictable stress (CUS), a well-established model for depression. Our results showed that Fut8+/- mice exhibited depressive-like behaviors and increased neuroinflammation earlier than Fut8+/+ mice. Administration of L-fucose significantly reduced CUS-induced depressive-like behaviors and pro-inflammatory cytokine levels in Fut8+/- mice. The L-fucose treatment produced antidepressant effects by attenuating the complex formation between gp130 and the interleukin-6 (IL-6) receptor and the JAK2/STAT3 signaling pathway. Notably, L-fucose treatment increased dendritic spine density and postsynaptic density protein 95 (PSD-95) expression, which were suppressed in CUS-induced depression. Furthermore, the effects of L-fucose on the CUS-induced depression were also observed in Fut8+/+ mice. Our results clearly demonstrate that L-fucose ameliorates neuroinflammation and synaptic defects in CUS-induced depression, implicating that core fucosylation has significant anti-neuroinflammatory activity and an antidepressant potential.

The Comorbidity of Depression and Diabetes Is Involved in the Decidual Protein Induced by Progesterone 1 (Depp1) Dysfunction in the Medial Prefrontal Cortex

BACKGROUND

There is a high rate of depressive symptoms such as irritability, anhedonia, fatigue, and hypersomnia in patients with type 2 diabetes mellitus (T2DM). However, the causes and underlying mechanisms of the comorbidity of depression and diabetes remain unknown.

METHODS

For the first time, we identified Decidual protein induced by progesterone 1 (Depp1), also known as DEPP autophagy regulator 1, as a hub gene in both depression and T2DM models. Depp1 levels were increased in the mPFC but not in other brain regions, such as the hippocampus or nucleus accumbens, according to Western blot and PCR assays.

RESULTS

Glucose dysregulation and synaptic loss occur in both depression and T2DM. The typical hyperglycemia in T2DM was observed in two models of depression, namely, chronic social defeat stress (CSDS) and chronic restraint stress (CRS). Hyperglycemia, which occurred in T2DM, was observed, and metabolomics data clearly showed the perturbation of glucose levels and glucose metabolism in the medial prefrontal cortex (mPFC). Decreased protein levels of BDNF and PSD95 suggested significant synaptic loss in depressed and diabetic mice.

CONCLUSION

These findings suggest that the comorbidity of depression and diabetes is involved in the dysfunction of Depp1 in the mPFC.

T-2 toxin triggers depression-like behaviors via upregulation of dopamine transporter in nucleus accumbens of male mice

The T-2 toxin is a frequent contaminant in the global environment and agricultural production. Existing evidence suggests that the ingested T-2 toxin can enter the brain and exhibit neurotoxicity. However, it is still unknown whether T-2 toxin causes the depression-like behaviors. In this study, the mice were orally administrated with 1.5 mg/kg T-2 toxin daily for 14 d, and the depression-like behaviors were assessed by the tail suspension test (TST) and sucrose preference test (SPT). Here, the results showed that T-2 toxin exposure induced depression-like behaviors, manifested as behavioral despair and anhedonia, without anxiety-like behaviors. In addition, the reduced dopamine (DA) level and elevated dopamine transporter (DAT) level were found in reward center nucleus accumbens (NAc) receiving DAergic projection from ventral tegmental area (VTA) in brain after T-2 toxin administration, while there was no significant alteration in DA synthesis-related tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC) in VTA and DA storage-related vesicle monoamine transporter 2 (VMAT2) in NAc. The local administration of DAT inhibitor AHN 1-055 hydrochloride into NAc alleviated T-2 toxin caused the depression-like behaviors. Importantly, the chemogenetic activation of the VTADA-NAc circuit increased the DA content in NAc and reversed the T-2 toxin-produced behavioral despair and anhedonia. Thus, our study for the first time illustrates DA dysregulation by upregulated DAT in NAc mediates T-2 toxin-triggered depression-like symptoms in mice. Meanwhile, this study establishes a novel causal relation between the neurotoxicant T-2 toxin exposure and the etiology of depression-like behaviors, and provides reference for the prevention and treatment for mycotoxin-induced depression-like symptoms.

Xiaoyaosan against depression through suppressing LPS mediated TLR4/NLRP3 signaling pathway in "microbiota-gut-brain" axis

ETHNOPHARMACOLOGICAL RELEVANCE

Depression impairs not only central nervous system, but also peripheral systems of the host. Gut microbiota have been proved to be involved in the pathogenesis of depression. Xiaoyaosan (XYS) has a history of over a thousand years in China for treating depression, dramatically alleviating anxiety, cognitive disorders, and especially gastrointestinal dysfunctions. Yet, it still just scratches the surface of the anti-depression mechanisms of XYS.

AIM OF THE STUDY

This study aims to elucidate the mechanism of actions of XYS from the perspective of "microbiota-gut-brain" axis.

MATERIALS AND METHODS

We firstly evaluated the effects of XYS on the macroscopic behaviors of depressed rats that induced by chronic unpredictable mild stress (CUMS). Secondly, the effects of XYS on intestinal homeostasis of depressed rats were revealed by using dysbacteriosis model. Subsequently, the underlying mechanisms were demonstrated by 16S rRNA gene sequencing technology and molecular biology methods. Finally, correlation analysis and visualization of the anti-depression effects of XYS were performed from the "microbiota - gut - brain" perspective.

RESULTS

Our data indicated that XYS ameliorated the depression-like symptoms of CUMS rats, partly depending on the presence of gut microbiota. Furthermore, we illustrated that XYS reversed CUMS-induced gut dysbiosis of depressed rats in terms of decreasing the Bacteroidetes/Firmicutes ratio and the abundances of Bacteroides, and Corynebacterium, while increasing the abundances of Lactobacillus and Adlercreutzia. The significant enrichment of Bacteroides and the level of lipopolysaccharides (LPS) suggested that depression damaged the immune responses and gut barrier. Mechanistically, XYS significantly down-regulated the expression levels of factors that involved in TLR4/NLRP3 signaling pathway in the colon and brain tissues of depressed rats. In addition, XYS significantly increased the levels of claudin 1 and ZO-1, showing that XYS positively maintained the integrity of gut and blood-brain barriers (BBB).

CONCLUSION

Our study offers insights into the anti-depression effects of XYS through a lens of "microbiota-TLR4/NLRP3 signaling pathway-barriers", providing a foundation for enhancing clinical efficiency and enriching drug selection, and contributing to our understanding of the mechanisms of traditional Chinese medicines (TCMs) in treating depression.

NLRP1 inflammasome in neurodegenerative disorders: From pathology to therapies

Neuroinflammation is a critical component in neurodegenerative disorders. The inflammasome, facilitates the cleavage of caspase-1, leading to the maturation and subsequent secretion of inflammatory factors interleukin (IL)-1β and IL-18. Consequently, pyroptosis mediated by gasdermin D, exacerbates neuroinflammation. Among the inflammasomes, NLRP1/3 are predominant in the central nervous system (CNS), Although NLRP1 was the earliest discovered inflammasome, the specific involvement of NLRP1 in neurodegenerative diseases remains to be fully elucidated. Recently, the discovery of an endogenous inhibitor of NLRP1, dipeptidyl peptidase 9, suggests the feasibility of producing of small-molecule drugs targeting NLRP1. This review describes the latest findings on the role of the NLRP1 inflammasome in the pathology of neurodegenerative disorders, including Alzheimer's disease, and summarises the regulatory mechanisms of NLRP1 inflammasome activation in the CNS. Furthermore, we highlight the recent progress in developing small-molecule and biological inhibitors that modulate the NLRP1 infammasome for the treatment of neurodegenerative disorders, some of which are advancing to preclinical testing. SIGNIFICANCE STATEMENT: The objective of this review is to synthesise the research on the structure, activation, and regulatory mechanisms of the NLRP1 inflammasome, along with its potential impact on both acute and chronic neurodegenerative conditions. The discovery of endogenous inhibitors, such as dipeptidyl peptidase 9 and thioredoxin, and their interaction with NLRP1 suggest the possibility of developing NLRP1-targeted small-molecule drugs for the treatment of neurodegenerative disorders. This review also discusses the use of both direct and indirect NLRP1 inhibitors as prospective therapeutic strategies for these conditions.

The characterization of BCL-xL displays a non-apoptotic role in suppression of NLRP1 inflammasome assembly in common carp (Cyprinus carpio L.)

The NLRP1 inflammasome is a crucial muti-protein complex in the host anti-pathogen immune response. The previous studies have revealed that the anti-apoptotic protein BCL-xL played a non-apoptotic role by impeding the activation of NLRP1 inflammasome in mammals. However, the potential role of BCL-xL in regulating the inflammasome in fish remains unclear. In the present study, the BCL-xL (CcBCL-xL) was cloned from the head kidney of common carp (Cyprinus carpio L.), and its regulatory effect on the NLRP1 inflammasome was explored. It was found that CcBCL-xL predominantly localized in the brain, spleen and head kidney of common carp, and upon stimulation with Aeromonas hydrophila (A. hydrophila), Edwardsiella tarda (E. tarda), or spring viremia of carp virus (SVCV), the expression of CcBCL-xL significantly increased in multiple immune organs. The interaction between CcBCL-xL and CcNLRP1 was confirmed by co-immunoprecipitation and immunofluorescence. Meanwhile, we also found that CcBCL-xL significantly inhibited the assembly of the CcNLRP1 inflammasome, through ASC oligomerization, ASC specks formation and cytotoxicity experiments. Furthermore, our results revealed that CcBCL-xL interacted with the NACHT, LRR, FIIND, and CARD domains of CcNLRP1. Taken together, the results provide a theoretical foundation for further exploring the regulatory mechanism of NLRP1, and for the prevention and treatment of infectious diseases in fish.

The impact of neuroinflammation on neuronal integrity

Neuroinflammation, characterized by a complex interplay among innate and adaptive immune responses within the central nervous system (CNS), is crucial in responding to infections, injuries, and disease pathologies. However, the dysregulation of the neuroinflammatory response could significantly affect neurons in terms of function and structure, leading to profound health implications. Although tremendous progress has been made in understanding the relationship between neuroinflammatory processes and alterations in neuronal integrity, the specific implications concerning both structure and function have not been extensively covered, with the exception of perspectives on glial activation and neurodegeneration. Thus, this review aims to provide a comprehensive overview of the multifaceted interactions among neurons and key inflammatory players, exploring mechanisms through which inflammation influences neuronal functionality and structural integrity in the CNS. Further, it will discuss how these inflammatory mechanisms lead to impairment in neuronal functions and architecture and highlight the consequences caused by dysregulated neuronal functions, such as cognitive dysfunction and mood disorders. By integrating insights from recent research findings, this review will enhance our understanding of the neuroinflammatory landscape and set the stage for future interventions that could transform current approaches to preserve neuronal integrity and function in CNS-related inflammatory conditions.

Investigating the modulatory effects of lactoferrin on depressed rats through 16S rDNA gene sequencing and LC-MS metabolomics analysis

Lactoferrin is a natural multifunctional glycoprotein with potential antidepressant-like effects. However, the mechanism of its antidepressant effect has not been explored from the perspective of gut flora metabolism. Therefore, we employed both 16S rDNA gene sequencing and LC-MS metabolomics analysis to investigate the regulatory effects and mechanisms of lactoferrin in a rat model of depression. After one week of acclimatization, twenty-four 7-week-old male Sprague-Dawley rats were randomly and equally assigned into three groups: the control group, the model group, and the lactoferrin intervention group. The control group rats were housed under standard conditions, while the rats in the model and lactoferrin intervention groups were individually housed and exposed to chronic unpredictable mild stress for 44 days simultaneously. The lactoferrin intervention group was provided with water containing 2% lactoferrin (2 g/100 ml). Behavioural tests were conducted at week 7. Upon completion of the behavioral tests, the rats were anesthetized with isoflurane, humanely euthanized using a rat guillotine, and tissue samples were collected for further experiments. The results indicated that lactoferrin intervention led to an increase in sucrose solution consumption, horizontal movement distance, number of cross platforms, and residence time in the target quadrant. Additionally, it resulted in an increase in jejunal tight junction protein ZO-1 expression and a suppression of serum expression of inflammatory factors, Lipopolysaccharide and Diamine oxidase. In summary, lactoferrin can regulate the metabolic disorder of intestinal flora, reduce intestinal permeability, and further regulate the metabolic balance of hippocampal tissues through the microbiota-gut-brain axis. This process ultimately alleviates the depression-like behavior in rats.

Targeting inflammasome complexes as a novel therapeutic strategy for mood disorders

INTRODUCTION

Inflammasome complexes, especially NLRP3, have gained great attention as a potential therapeutic target in mood disorders. NLRP3 triggers a caspase 1-dependent release of the inflammatory cytokines IL-1β and IL-18, and seems to interact with purinergic and kynurenine pathways, all of which are implicated in mood disorders development and progression.

AREAS COVERED

Emerging evidence supports NLRP3 inflammasome as a promising pharmacological target for mood disorders. We discussed the available evidence from animal models and human studies and provided a reflection on drawbacks and perspectives for this novel target.

EXPERT OPINION

Several studies have supported the involvement of NLRP3 inflammasome in MDD. However, most of the evidence comes from animal models. The role of NLRP3 inflammasome in BD as well as its anti-manic properties is not very clear and requires further exploration. There is evidence of anti-manic effects of P2×R7 antagonists associated with reduction in the brain levels of IL-1β and TNF-α in a murine model of mania. The involvement of other NLRP3 inflammasome expressing cells besides microglia, like astrocytes, and of other inflammasome complexes in mood disorders also deserves further investigation. Preclinical and clinical characterization of NLRP3 and other inflammasomes in mood disorders is needed before considering translational approaches, including clinical trials.

Targeting autophagy to counteract neuroinflammation: A novel antidepressant strategy

Depression is a common disease that affects physical and mental health and imposes a considerable burden on afflicted individuals and their families worldwide. Depression is associated with a high rate of disability and suicide. It causes a severe decline in productivity and quality of life. Unfortunately, the pathophysiological mechanisms underlying depression have not been fully elucidated, and the risk of its treatment is still presented. Studies have shown that the expression of autophagic markers in the brain and peripheral inflammatory mediators are dysregulated in depression. Autophagy-related genes regulate the level of autophagy and change the inflammatory response in depression. Depression is related to several aspects of immunity. The regulation of the immune system and inflammation by autophagy may lead to the development or deterioration of mental disorders. This review highlights the role of autophagy and neuroinflammation in the pathophysiology of depression, sumaries the autophagy-targeting small moleculars, and discusses a novel therapeutic strategy based on anti-inflammatory mechanisms that target autophagy to treat the disease.