Autophagy and Autophagy-Related Proteins in CNS Autoimmunity

The beneficial role of autophagy in multiple sclerosis: Yes or No?

Multiple sclerosis (MS) is a chronic progressive demyelinating disease of the central nervous system (CNS) due to an increase of abnormal peripherally auto-reactive T lymphocytes which elicit autoimmunity. The main pathophysiology of MS is myelin sheath damage by immune cells and a defect in the generation of myelin by oligodendrocytes. Macroautophagy/autophagy is a critical degradation process that eliminates dysfunctional or superfluous cellular components. Autophagy has the property of a double-edged sword in MS in that it may have both beneficial and detrimental effects on MS neuropathology. Therefore, this review illustrates the protective and harmful effects of autophagy with regard to this disease. Autophagy prevents the progression of MS by reducing oxidative stress and inflammatory disorders. In contrast, over-activated autophagy is associated with the progression of MS neuropathology and in this case the use of autophagy inhibitors may alleviate the pathogenesis of MS. Furthermore, autophagy provokes the activation of different immune and supporting cells that play an intricate role in the pathogenesis of MS. Autophagy functions in the modulation of MS neuropathology by regulating cell proliferation related to demyelination and remyelination. Autophagy enhances remyelination by increasing the activity of oligodendrocytes, and astrocytes. However, autophagy induces demyelination by activating microglia and T cells. In conclusion, specific autophagic activators of oligodendrocytes, and astrocytes, and specific autophagic inhibitors of dendritic cells (DCs), microglia and T cells induce protective effects against the pathogenesis of MS.Abbreviations: ALS: amyotrophic lateral sclerosis; APCs: antigen-presenting cells; BBB: blood-brain barrier; CSF: cerebrospinal fluid; CNS: central nervous system; DCs: dendritic cells; EAE: experimental autoimmune encephalomyelitis; ER: endoplasmic reticulum; LAP: LC3-associated phagocytosis; MS: multiple sclerosis; NCA: non-canonical autophagy; OCBs: oligoclonal bands; PBMCs: peripheral blood mononuclear cells; PD: Parkinson disease; ROS: reactive oxygen species; UPR: unfolded protein response.

Suppression of DAPK1 reduces ischemic brain injury through inhibiting cell death signaling and promoting neural remodeling

The role of death-associated protein kinase1 (DAPK1) in post-stroke functional recovery is controversial, as is its mechanism of action and any neural remodeling effect after ischemia. To assess the debatable role of DAPK1, we established the middle cerebral artery occlusion (MCAo) model in DAPK1 knockout mice and Sprague-Dawley (SD) rats. We identified that the genetic deletion of the DAPK1 as well as pharmacological inhibition of DAPK1 showed reduced brain infarct volume and neurological deficit. We report that DAPK1 inhibition (DI) reduces post-stroke neuronal death by inhibiting BAX/BCL2 and LC3/Beclin1 mediated apoptosis and autophagy, respectively. Histological analysis displayed a reduction in nuclear condensation, neuronal dissociation, and degraded cytoplasm in the DI group. The DI treatment showed enhanced dendrite spine density and neurite outgrowth, upregulated neural proliferation marker proteins like brain-derived neurotrophic factor, and reduced structural abnormalities of the cortical pyramidal neurons. This research shows that DAPK1 drives cell death, its activation exacerbates functional recovery after cerebral ischemia and shows that oxazolone-based DI could be an excellent candidate for stroke and ischemic injury intervention.

Grouper Atg14 promotes Singapore grouper iridovirus (SGIV) replication by inhibiting the host innate immune response

As one of the important members of the autophagy-related protein family, Atg14 plays a key role in the formation and maturation of autophagosomes. However, little is known about the potential roles of fish Atg14 and its roles in virus infection. In the present study, the homolog of Atg14 (EcAtg14) from the orange-spotted grouper (Epinephelus coioides) was cloned and characterized. The open reading frame (ORF) of EcAtg14 consists of 1530 nucleotides, encoding 509 amino acids, with a predicted molecular weight of 56.9 kDa. EcAtg14 was distributed in all tested tissues, with higher expression in liver, blood and spleen. The expression of EcAtg14 was increased in grouper spleen (GS) cells after Singapore grouper iridovirus (SGIV) infection. EcAtg14 was distributed in the cytoplasm of GS cells. Overexpression of EcAtg14 promoted SGIV replication in GS cells and inhibited IFN3, ISRE and NF-κB promoter activities. Co-immunoprecipitation results showed that there was an interaction between EcAtg14 and EcBeclin. EcAtg14 also promoted the synthesis of LC3-II in GS cells. These findings provide a basis for understanding the innate immune mechanism of grouper against viral infection.

Lysosomes, curcumin, and anti-tumor effects: how are they linked?

Curcumin is a natural active ingredient from traditional Chinese medicine (TCM) that has multi-target characteristics to exert extensive pharmacological activities and thus has been applied in the treatment of various diseases such as cancer, cardiovascular diseases, nervous system, and autoimmune disorders. As an important class of membranous organelles in the intracellular membrane system, lysosomes are involved in biological processes such as programmed cell death, cell metabolism, and immune regulation, thus affecting tumor initiation and progression. It has been shown that curcumin can modulate lysosomal function through the aforementioned pathways, thereby affecting tumor proliferation, invasion, metastasis, drug resistance, and immune function. This review briefly elaborated the regulatory mechanisms of lysosome biogenesis and summarized curcumin-related studies with its anti-tumor effect, providing a reference for the clinical application of curcumin and anti-tumor research targeting lysosomes.

The role of lysosomes in metabolic and autoimmune diseases

Lysosomes are catabolic organelles that contribute to the degradation of intracellular constituents through autophagy and of extracellular components through endocytosis, phagocytosis and macropinocytosis. They also have roles in secretory mechanisms, the generation of extracellular vesicles and certain cell death pathways. These functions make lysosomes central organelles in cell homeostasis, metabolic regulation and responses to environment changes including nutrient stresses, endoplasmic reticulum stress and defects in proteostasis. Lysosomes also have important roles in inflammation, antigen presentation and the maintenance of long-lived immune cells. Their functions are tightly regulated by transcriptional modulation via TFEB and TFE3, as well as by major signalling pathways that lead to activation of mTORC1 and mTORC2, lysosome motility and fusion with other compartments. Lysosome dysfunction and alterations in autophagy processes have been identified in a wide variety of diseases, including autoimmune, metabolic and kidney diseases. Deregulation of autophagy can contribute to inflammation, and lysosomal defects in immune cells and/or kidney cells have been reported in inflammatory and autoimmune pathologies with kidney involvement. Defects in lysosomal activity have also been identified in several pathologies with disturbances in proteostasis, including autoimmune and metabolic diseases such as Parkinson disease, diabetes mellitus and lysosomal storage diseases. Targeting lysosomes is therefore a potential therapeutic strategy to regulate inflammation and metabolism in a variety of pathologies.

Lithium engages autophagy for neuroprotection and neuroplasticity: translational evidence for therapy

Here an overview is provided on therapeutic/neuroprotective effects of Lithium (Li⁺) in neurodegenerative and psychiatric disorders focusing on the conspicuous action of Li⁺ through autophagy. The effects on the autophagy machinery remain the key molecular mechanisms to explain the protective effects of Li⁺ for neurodegenerative diseases, offering potential therapeutic strategies for the treatment of neuropsychiatric disorders and emphasizes a crossroad linking autophagy, neurodegenerative disorders, and mood stabilization. Sensitization by psychostimulants points to several mechanisms involved in psychopathology, most also crucial in neurodegenerative disorders. Evidence shows the involvement of autophagy and metabotropic Glutamate receptors-5 (mGluR5) in neurodegeneration due to methamphetamine neurotoxicity as well as in neuroprotection, both in vitro and in vivo models. More recently, Li⁺ was shown to modulate autophagy through its action on mGluR5, thus pointing to an additional way of autophagy engagement by Li⁺ and to a substantial role of mGluR5 in neuroprotection related to neural e neuropsychiatry diseases. We propose Li⁺ engagement of autophagy through the canonical mechanisms of autophagy machinery and through the intermediary of mGluR5.

An Immunogenic Cell Death-Related Gene Signature Reflects Immune Landscape and Predicts Prognosis in Melanoma Independently of BRAF V600E Status

Immunogenic cell death (ICD) is a type of regulated cell death that can activate adaptive immune response, and its ability to reshape the tumor microenvironment via multiple mechanisms may contribute to immunotherapy. The treatment options for patients with skin cutaneous melanoma (SKCM) vary based on BRAF V600E statuses. However, all standard treatments include immunotherapy. Therefore, it is critical to identify ICD-associated signatures that can help classify patients according to benefits from ICD immunotherapy. In this study, data on melanoma samples with BRAF V600E mutation (BRAF V600E-mutant melanoma) and melanoma samples with wild-type BRAF V600E alleles (BRAF V600E WT melanoma) were collected from The Cancer Genome Atlas (TCGA) database. The ICD-related (ICD-high and ICD-low) subgroups of patients with BRAF V600E WT melanoma were established via consensus clustering. The analyses of survival, differentially expressed genes (DEGs), functional annotation, and immune landscape were performed in these two subgroups. Results showed that ICD-high subgroup was correlated with a positive overall survival (OS) and active tumor immune landscape. A model comprising seven prognosis ICD-related gene biomarkers was developed. Survival analysis and receiver operating characteristic (ROC) curve evaluation in both cohorts with BRAF V600E WT and BRAF V600E-mutant melanoma showed an accurate prognostic estimation of ICD-related risk signature. There was a correlation between immune cell infiltration and immunotherapy response and risk score. Thus, the ICD risk signature was closely associated with the tumor's immune microenvironment. Our results may provide insights to further individualize and improve precision therapeutic decision-making in BRAF V600E-mutant and WT melanoma.

Autophagy-related genes in Egyptian patients with Behçet's disease

Background

Behçet's disease (BD) is a chronic, multi-systemic, recurrent condition that affects the vascular, ocular, mucocutaneous, and central nervous systems. The diagnosis of this disease depends on its clinical features, which are similar to those observed in several diseases, such as Parkinson’s disease, pemphigus vulgaris, systemic lupus erythematosus, Crohn ҆s disease, and Sjӧgren’s syndrome. Lysosome-mediated autophagy is a catabolic, cytoprotective mechanism that maintains cell homeostasis by degrading undesired long-lived proteins and recycling nutrients. The aim of this study was to evaluate the correlations between some autophagy-related genes (ATG5, ATG7, ATG12, LC3b, mTOR) and the pathogenesis and immunopathology of BD. The expression levels of the genes were evaluated by quantitative polymerase chain reaction (qPCR) in 101 individuals that are classified into two groups. Group 1: (n = 71) BD patients, Group 2: (n = 30) healthy controls.

Results

Patients with BD had lower mRNA expression levels of ATG5 and mTOR and higher levels of LC3b mRNA than the controls. No significant differences in the levels of both ATG7 and ATG12 were observed between the two groups. According to the area under the curve analysis, LC3b was considered the best candidate biomarker among the selected markers for the diagnosis of BD. The mRNA expression of ATG5 was significantly correlated with patient age and the presence of oral ulcers. The mRNA expression of ATG7 was significantly associated with age and the presence of erythema nodosum and vascular lesions, whereas that of LC3b was significantly correlated with the presence of pustules.

Conclusion

These findings indicated that elevated levels of LC3b were strongly associated with BD. Likewise, the levels of ATG5 and ATG7 were associated with the complications and outcomes of this disease. Additional assessments of the mRNA expression levels of these autophagy-related genes might prove beneficial in diagnosing this autoimmune disorder.

Tandem Mass Tag Analysis of the Effect of the Anterior Cingulate Cortex in Nonerosive Reflux Disease Rats with Shugan Jiangni Hewei Granules Treatment

Objective. The current study aims to analyze the improvement mechanism of visceral hypersensitivity (VH) and targets of Shugan Jiangni Hewei granules (SJHG) for nonerosive reflux disease (NERD) treatment as well as to offer an experimental foundation for its clinical use. Methods. Healthy male Sprague–Dawley rats ( $n$  = 36) were acquired in the current study that was further split into three groups: blank, model, and drug (SJHG). Subsequently, differentially expressed proteins and bioinformatics analysis were performed on the collected tissue samples acquired from the anterior cingulate cortex of the model and SJHG rat groups using a tandem mass tag- (TMT-) based proteomics. Eventually, the obtained data from the bioinformatic analysis was further verified through western blotting. Results. From the bioinformatics analysis, only 64 proteins were differentially expressed between the NC and SJHG groups. These molecules were found to be highly expressed in immunological response and neural signal transmission. Finally, we confirmed three therapeutic targets of SJHG, namely, kininogen 1 (Kng1), junctional adhesion molecule A (JAM-A), and the PI3K/Akt signaling pathway. Conclusions. SJHG is effective in treating VH, Kng1 and JAM-A may be therapeutic targets of SJHG, and the therapeutic mechanism of SJHG may be realized by influencing immune response or transmission of neural signals.

Lysosomal dysfunction is associated with NLRP3 inflammasome activation in chronic unpredictable mild stress-induced depressive mice

NLRP3 inflammasome pathway-mediated inflammatory response is closely associated with depression. Increasing attention has been recently paid to the links between autophagy and depression, however, the relationship between autophagy and NLRP3 inflammasome in depressive behavior remain poorly understood. In the present study, the potential roles of autophagy-lysosome pathway in NLRP3 inflammasome regulation were investigated both in vivo (chronic unpredictable mild stress (CUMS)-induced depressive mouse model) and in vitro (LPS-induced cellular model) model. It demonstrated that CUMS induces depressive-like behaviors in mice, accompanied by increased expression of NLRP3 inflammasome and inflammatory responses. Meanwhile, it promoted the autophagosome marker LC3 and autophagic adaptor protein p62 accumulation, accompanied by the decrease of lysosomal cathepsins B and D expression in the prefrontal cortex of mice. Notably, a significant colocalization of NLRP3 and LC3 in CUMS mice by immunofluorescence co-staining were observed. For the in vitro study, disrupting the lysosomal function with Baf A1 significantly increased the LPS-induced NLRP3 inflammasome accumulation and pro-inflammatory factors (IL-1β and IL-18) production in BV2 cells. Collectively, our results suggested that the autophagic process is related to NLRP3 inflammasome activation, and dysfunctional lysosome in autophagy-lysosomal pathway may retard NLRP3 inflammasome degradation, facilitating the production of pro-inflammatory factors, thereby contributing to depressive behavior in CUMS mice.

Autophagy modulation in multiple sclerosis and experimental autoimmune encephalomyelitis

Multiple sclerosis (MS), a white matter demyelinating disease of the central nervous system (CNS), is characterized by neuroinflammatory and neurodegenerative. Experimental autoimmune encephalomyelitis (EAE) is a commonly used animal model for investigating pathogenic mechanisms of MS, representing the destruction of the blood-brain barrier (BBB), the activation of T cells, and the infiltration of myeloid cells. An increasing number of studies have documented that autophagy plays a critical role in the pathogenesis of both MS and EAE. Autophagy maintains CNS homeostasis by degrading the damaged organelles and abnormal proteins. Furthermore, autophagy is involved in inflammatory responses by regulating the activation of immune cells and the secretion of inflammatory factors. However, the specific mechanisms of autophagy involved in MS and EAE are not completely understood. In this review, we will summarize the complex mechanisms of autophagy in MS and EAE, providing potential therapeutic approaches for the management of MS.

The polymorphism L412F in TLR3 inhibits autophagy and is a marker of severe COVID-19 in males

The polymorphism L412F in TLR3 has been associated with several infectious diseases. However, the mechanism underlying this association is still unexplored. Here, we show that the L412F polymorphism in TLR3 is a marker of severity in COVID-19. This association increases in the sub-cohort of males. Impaired macroautophagy/autophagy and reduced TNF/TNFα production was demonstrated in HEK293 cells transfected with TLR3^L412F-encoding plasmid and stimulated with specific agonist poly(I:C). A statistically significant reduced survival at 28 days was shown in L412F COVID-19 patients treated with the autophagy-inhibitor hydroxychloroquine (p = 0.038). An increased frequency of autoimmune disorders such as co-morbidity was found in L412F COVID-19 males with specific class II HLA haplotypes prone to autoantigen presentation. Our analyses indicate that L412F polymorphism makes males at risk of severe COVID-19 and provides a rationale for reinterpreting clinical trials considering autophagy pathways.

Abbreviations: AP: autophagosome; AUC: area under the curve; BafA1: bafilomycin A1; COVID-19: coronavirus disease-2019; HCQ: hydroxychloroquine; RAP: rapamycin; ROC: receiver operating characteristic; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; TLR: toll like receptor; TNF/TNF-α: tumor necrosis factor

DL-3-n-butylphthalide suppressed autophagy and promoted angiogenesis in rats with vascular dementia by activating the Shh/Ptch1 signaling pathway

DL-3-n-butylphthalide (NBP) has neuroprotective effect on chronic cerebral hypoperfusion animals. Here, we explored the role and underlying mechanism of NBP on autophagy and angiogenesis in rats with vascular dementia (VD). Adult male Sprague-Dawley (SD) rats were subjected to permanent bilateral occlusion of the common carotid arteries (2VO) to establish VD model. These rats were randomly divided into five groups: sham, model, NBP₁₂₀ (120 mg/kg), Shh siRNA (50 nM), and NBP₁₂₀ + Shh siRNA groups. Our results showed that NBP treatment attenuated memory damage in rats with VD, as demonstrated by Morris water maze tests. Immunofluorescence (IF) assay revealed that NBP induced neuronal process length and neuronal activity in hippocampus, which were reversed by Shh silencing. Furthermore, NBP treatment also reduced the expression of autophagy marker proteins B-cell lymphoma-2 interacting protein 1 (Beclin 1) and microtubule-associated protein 1 light chain 3 (LC3), which were further enhanced by Shh silencing. Meanwhile, NBP promoted the angiogenesis, which was accompanied by upregulated vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF)-1, and Angiopoietin (Ang) expression in the hippocampus. And Shh siRNA co-treatment blocked the angiogenesis induced by NBP. Altogether, our results established that NBP treatment suppressed autophagy and improved angiogenesis and neurobehavioral recovery in VD rats partly by activating the Shh/Ptch1 signaling pathway.

Sestrin2 and Beclin1 levels in Polycystic Ovary Syndrome

Background

Sestrin2 and beclin1 are two newly found proteins that have essential roles in autophagy. This study attempted to evaluate the plasma concentrations of sestrin2 and beclin1 in women with polycystic ovary syndrome (PCOS) and healthy controls and to explore the clinical value of these proteins as novel biomarkers for PCOS.

Methods

In this case‐control study, plasma levels of sestrin2 and beclin1, fasting blood sugar (FBS), lipid profile, insulin, and androgens were evaluated in 63 women (31 patients and 32 controls). Sestrin2 and beclin1 levels were determined using enzyme‐linked immunosorbent assay (ELISA). Descriptive statistics, correlation coefficients, logistic regression, and ROC curve analyses were used in this study.

Results

Plasma sestrin2 levels of the subjects with PCOS (40.74 [24.39–257.70]) were significantly lower than those of healthy subjects (255.78 [25.46–528.66]; p‐value = 0.040). ROC curve analysis showed that a cutoff value of 420.5 ng/L had an appropriate sensitivity (83.87%) and specificity (46.88%) for discriminating individuals with and without PCOS, with the area under the curve (95% CI) of 0.648 (0.518 to 0.764), p = 0.036. There were no statistically significant differences between the two groups concerning plasma levels of beclin1, biochemical parameters, blood pressure, and anthropometric features.

Conclusion

Our findings highlight the dysregulation of sestrin2 as a marker of autophagy in PCOS and its potential usefulness as a novel biomarker for PCOS. Further research is needed to better understand the role of this protein in the pathophysiology of PCOS and its value as a diagnostic tool for the evaluation of PCOS patients.

Antipsychotic drugs counteract autophagy and mitophagy in multiple sclerosis

Multiple sclerosis (MS) is a neuroinflammatory and neurodegenerative disease characterized by myelin damage followed by axonal and ultimately neuronal loss. The etiology and physiopathology of MS are still elusive, and no fully effective therapy is yet available. We investigated the role in MS of autophagy (physiologically, a controlled intracellular pathway regulating the degradation of cellular components) and of mitophagy (a specific form of autophagy that removes dysfunctional mitochondria). We found that the levels of autophagy and mitophagy markers are significantly increased in the biofluids of MS patients during the active phase of the disease, indicating activation of these processes. In keeping with this idea, in vitro and in vivo MS models (induced by proinflammatory cytokines, lysolecithin, and cuprizone) are associated with strongly impaired mitochondrial activity, inducing a lactic acid metabolism and prompting an increase in the autophagic flux and in mitophagy. Multiple structurally and mechanistically unrelated inhibitors of autophagy improved myelin production and normalized axonal myelination, and two such inhibitors, the widely used antipsychotic drugs haloperidol and clozapine, also significantly improved cuprizone-induced motor impairment. These data suggest that autophagy has a causal role in MS; its inhibition strongly attenuates behavioral signs in an experimental model of the disease. Therefore, haloperidol and clozapine may represent additional therapeutic tools against MS.

Sildenafil Alleviates Murine Experimental Autoimmune Encephalomyelitis by Triggering Autophagy in the Spinal Cord

Multiple Sclerosis (MS) is a neuroinflammatory and chronic Central Nervous System (CNS) disease that affects millions of people worldwide. The search for more promising drugs for the treatment of MS has led to studies on Sildenafil, a phosphodiesterase type 5 Inhibitor (PDE5I) that has been shown to possess neuroprotective effects in the Experimental Autoimmune Encephalomyelitis (EAE), an animal model of MS. We have previously shown that Sildenafil improves the clinical score of EAE mice via modulation of apoptotic pathways, but other signaling pathways were not previously covered. Therefore, the aim of the present study was to further investigate the effects of Sildenafil treatment on autophagy and nitrosative stress signaling pathways in EAE. 24 female C57BL/6 mice were divided into the following groups: (A) Control - received only water; (B) EAE - EAE untreated mice; (C) SILD - EAE mice treated with 25mg/kg of Sildenafil s.c. The results showed that EAE mice presented a pro-nitrosative profile characterized by high tissue nitrite levels, lowered levels of p-eNOS and high levels of iNOS. Furthermore, decreased levels of LC3, beclin-1 and ATG5, suggests impaired autophagy, and decreased levels of AMPK in the spinal cord were also detected in EAE mice. Surprisingly, treatment with Sildenafil inhibited nitrosative stress and augmented the levels of LC3, beclin-1, ATG5, p-CREB and BDNF and decreased mTOR levels, as well as augmented p-AMPK. In conclusion, we propose that Sildenafil alleviates EAE by activating autophagy via the eNOS-NO-AMPK-mTOR-LC3-beclin1-ATG5 and eNOS-NO-AMPK-mTOR-CREB-BDNF pathways in the spinal cord.

Autophagy in Multiple Sclerosis: Two Sides of the Same Coin

Multiple sclerosis (MS) is a complex auto-immune disorder of the central nervous system (CNS) that involves a range of CNS and immune cells. MS is characterized by chronic neuroinflammation, demyelination, and neuronal loss, but the molecular causes of this disease remain poorly understood. One cellular process that could provide insight into MS pathophysiology and also be a possible therapeutic avenue, is autophagy. Autophagy is an intracellular degradative pathway essential to maintain cellular homeostasis, particularly in neurons as defects in autophagy lead to neurodegeneration. One of the functions of autophagy is to maintain cellular homeostasis by eliminating defective or superfluous proteins, complexes, and organelles, preventing the accumulation of potentially cytotoxic damage. Importantly, there is also an intimate and intricate interplay between autophagy and multiple aspects of both innate and adaptive immunity. Thus, autophagy is implicated in two of the main hallmarks of MS, neurodegeneration, and inflammation, making it especially important to understand how this pathway contributes to MS manifestation and progression. This review summarizes the current knowledge about autophagy in MS, in particular how it contributes to our understanding of MS pathology and its potential as a novel therapeutic target.

Pyrroloquinoline Quinone Inhibits Rotenone-Induced Microglia Inflammation by Enhancing Autophagy

Neuroinflammation is a feature common to neurodegenerative diseases, such as Parkinson’s disease (PD), which might be responsive to therapeutic intervention. Rotenone has been widely used to establish PD models by inducing mitochondrial dysfunction and inflammation. Our previous studies have reported that pyrroloquinoline quinone (PQQ), a naturally occurring redox cofactor, could prevent mitochondrial dysfunction in rotenone induced PD models by regulating mitochondrial functions. In the present study, we aimed to investigate the effect of PQQ on neuroinflammation and the mechanism involved. BV2 microglia cells were pre-treated with PQQ followed by rotenone incubation. The data showed that PQQ did not affect the cell viability of BV2 cells treated with rotenone, while the conditioned medium (CM) of BV2 cells pre-treated with PQQ significantly increased cell viability of SH-SY5Y cells. In rotenone-treated BV2 cells, PQQ dose-dependently decreased lactate dehydrogenase (LDH) release and suppressed the up-regulation of pro-inflammation factors, such as interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) in the cultured media, as well as nitric oxide (NO) release induced by rotenone. PQQ pretreatment also increased the ratio of LC3-II/LC3-I and expression of Atg5 in BV2 cells stimulated with rotenone. Additionally, the autophagosome observed by transmission electron microscopy (TEM) and co-localization of mitochondria with lysosomes indicated that mitophagy was induced by PQQ in rotenone-injured BV2 cells, and the PINK1/parkin mediated mitophagy pathway was regulated by PQQ. Further, autophagy inhibitor, 3-methyladenine (3-MA), partially abolished the neuroprotective effect of PQQ and attenuated the inhibition of inflammation with PQQ pretreatment. Taken together, our data extend our understanding of the neuroprotective effect of PQQ against rotenone-induced injury and provide evidence that autophagy enhancement might be a novel therapeutic strategy for PD treatment.

Role of ABT888, a Novel Poly(ADP-Ribose) Polymerase (PARP) Inhibitor in Countering Autophagy and Apoptotic Processes Associated to Spinal Cord Injury

Accidents are the cause of some 50 deaths per 100,000 population each year; some 3% of these are from traumatic spinal cord injury (SCI), a damage that causes temporary or permanent motor deficits, often leading to permanent neurological alterations. The activation of poly(ADP-ribose) polymerase (PARP) as DNA damage response, together with autophagy and apoptosis processes contributes to the secondary injury processes seen after SCI. Thus, in the present study, a mouse compression model of SCI was used to determine whether the treatment with ABT888, as PARP-1/2 inhibitor, could restore the neuronal damage induced by SCI. Mice were orally administered with ABT888 (at a dose of 25 mg/kg) 1 h and 6 h after SCI induction. Histological analysis, myeloperoxidase (MPO) activity, and Basso Mouse scale (BMS) were performed. The expression of autophagy-related proteins and apoptosis-inducing factors was quantified in the cytosolic fraction from spinal cord tissue collected after 24 h after SCI. TUNEL assay was performed in SCI-tissues 24 h after damage. ABT888 treatment significantly reduced histological damage and neutrophilic infiltration, improving motor skills. PARP-1/2 inhibition by ABT888 slowed cell death, decreasing autophagy-activation proteins. These results showed that ABT888, inhibiting PARP-1/2 activity, through a reduction in the apoptosis-autophagy machinery, plays a protective role after SCI, suggesting a new insight into the potential application of ABT888 as novel candidate in SCI therapies.

Treatment with Melittin Induces Apoptosis and Autophagy of Fibroblast-like Synoviocytes in Patients with Rheumatoid Arthritis

Background:

Melittin, the major medicinal component of honeybee venom, exerts antiinflammatory, analgesic, and anti-arthritic effects in patients with Rheumatoid Arthritis (RA). RA is an inflammatory autoimmune joint disease that leads to irreversible joint destruction and functional loss. Fibroblast-Like Synoviocytes (FLS) are dominant, special mesenchymal cells characterized by the structure of the synovial intima, playing a crucial role in both the initiation and progression of RA.

Objective:

In this study, we evaluated the effects of melittin on the viability and apoptosis of FLS isolated from patients with RA.

Methods:

Cell viability was determined using CCK-8 assays; apoptosis was evaluated by flow cytometry, and the expression levels of apoptosis-related proteins (caspase-3, caspase-9, BAX, and Bcl-2) were also determined. To explore whether melittin alters inflammatory processes in RA-FLS, IL-1β levels were determined using an enzyme-linked immunosorbent assay (ELISA). Furthermore, we performed GFP-LC3 punctate fluorescence dot assays and western blotting (for LC3, ATG5, p62, and Beclin 1) to assess autophagy in RA-FLS.

Results:

Our results show that melittin can significantly impair viability, promote apoptosis and autophagy, and inhibit IL-1β secretion in RA-FLS.

Conclusion:

Melittin may be useful in preventing damage to the joints during accidental local stimulation.

Allicin ameliorates obesity comorbid depressive-like behaviors: involvement of the oxidative stress, mitochondrial function, autophagy, insulin resistance and NOX/Nrf2 imbalance in mice

The increased prevalence of obesity has been a major medical and public health problem in the past decades. In obese status, insulin resistance and sustained oxidative stress damage might give rise to behavioral deficits. The anti-obesity and anti-oxidant effects of allicin have been previously reported in peripheral tissues. In the present study, the functions and mechanisms of allicin involved in the prevention of high-fat diet (HFD)-induced depressive-like behaviors were investigated to better understand the pharmacological activities of allicin. Obese mice (five weeks of age) were treated with allicin (50, 100, and 200 mg/kg) by gavage for 15 weeks and behavioral test (sucrose preference, open field, and tail suspension) were performed. Furthermore, markers of oxidative stress, mitochondrial function, autophagy, and insulin resistance were measured in the hippocampal tissue. Finally, the levels of NADPH oxidase (NOX2, NOX4) and the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway were evaluated in the hippocampus. The body weight, metabolic disorders, and depressive-like behaviors in obese mice were ameliorated by allicin. The depressive-like behaviors presented in the obese mice were accompanied by remarkably excessive reactive oxygen species (ROS) production and oxidative stress, damaged mitochondrial function, imbalanced autophagy, and enhanced insulin resistance in the hippocampus. We found that allicin improved the above undesirable effects in the obese mice. Furthermore, allicin significantly decreased NOX2 and NOX4 levels and activated the Nrf2 pathway. Allicin attenuated depressive-like behaviors triggered by long-term HFD consumption by inhibiting ROS production and oxidative stress, improving mitochondrial function, regulating autophagy, and reducing insulin resistance in the hippocampus via optimization of NOX/Nrf2 imbalance.

Modulating T Cell Responses via Autophagy: The Intrinsic Influence Controlling the Function of Both Antigen-Presenting Cells and T Cells

Autophagy is a homeostatic and inducible process affecting multiple aspects of the immune system. This intrinsic cellular process is involved in MHC-antigen (Ag) presentation, inflammatory signaling, cytokine regulation, and cellular metabolism. In the context of T cell responses, autophagy has an influential hand in dictating responses to self and non-self by controlling extrinsic factors (e.g., MHC-Ag, cytokine production) in antigen-presenting cells (APC) and intrinsic factors (e.g., cell signaling, survival, cytokine production, and metabolism) in T cells. These attributes make autophagy an attractive therapeutic target to modulate T cell responses. In this review, we examine the impact autophagy has on T cell responses by modulating multiple aspects of APC function; the importance of autophagy in the activation, differentiation and homeostasis of T cells; and discuss how the modulation of autophagy could influence T cell responses.

Exploring the Role of Autophagy-Related Gene 5 (ATG5) Yields Important Insights Into Autophagy in Autoimmune/Autoinflammatory Diseases

Autophagy is a highly conserved process that degrades certain intracellular contents in both physiological and pathological conditions. Autophagy-related proteins (ATG) are key players in this pathway, among which ATG5 is indispensable in both canonical and non-canonical autophagy. Recent studies demonstrate that ATG5 modulates the immune system and crosstalks with apoptosis. However, our knowledge of the pathogenesis and regulatory mechanisms of autophagy in various immune related diseases is lacking. Thus, a deeper understanding of ATG5's role in the autophagy mechanism may shed light on the link between autophagy and the immune response, and lead to the development of new therapies for autoimmune diseases and autoinflammatory diseases. In this focused review, we discuss the latest insights into the role of ATG5 in autoimmunity. Although these studies are at a relatively early stage, ATG5 may eventually come to be regarded as a “guardian of immune integrity.” Notably, accumulating evidence indicates that other ATG genes may have similar functions.

Lymphocyte Autophagy in Homeostasis, Activation, and Inflammatory Diseases

Autophagy is a catabolic mechanism, allowing the degradation of cytoplasmic content via lysosomal activity. Several forms of autophagy are described in mammals. Macroautophagy leads to integration of cytoplasmic portions into vesicles named autophagosomes that ultimately fuse with lysosomes. Chaperone-mediated autophagy is in contrast the direct translocation of protein in lysosomes. Macroautophagy is central to lymphocyte homeostasis. Although its role is controversial in lymphocyte development and in naive cell survival, it seems particularly involved in the maintenance of certain lymphocyte subtypes. Its importance in memory B and T cells biology has recently emerged. Moreover, some effector cells like plasma cells rely on autophagy for survival. Autophagy is central to glucose and lipid metabolism, and to the maintenance of organelles like mitochondria and endoplasmic reticulum. In addition macroautophagy, or individual components of its machinery, are also actors in antigen presentation by B cells, a crucial step to receive help from T cells, this crosstalk favoring their final differentiation into memory or plasma cells. Autophagy is deregulated in several autoimmune or autoinflammatory diseases like systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis, and Crohn’s disease. Some treatments used in these pathologies impact autophagic activity, even if the causal link between autophagy regulation and the efficiency of the treatments has not yet been clearly established. In this review, we will first discuss the mechanisms linking autophagy to lymphocyte subtype survival and the signaling pathways involved. Finally, potential impacts of autophagy modulation in lymphocytes on the course of these diseases will be approached.

Depletion of gamma-glutamylcyclotransferase in cancer cells induces autophagy followed by cellular senescence

Gamma-glutamylcyclotransferase (GGCT) was originally identified as a protein highly expressed in bladder cancer tissues by proteomic analysis, and its higher expression in a variety of cancers compared to normal tissues have been shown. Depletion of GGCT in various cancer cells results in antiproliferative effects both in vitro and in vivo; thus it is considered a promising therapeutic target. Although it has been shown that knockdown of GGCT induces cellular senescence and non-apoptotic cell death, associated with upregulation of cyclin-dependent kinase inhibitors (CDKIs) including p21^WAF1/CIP1, the cellular events that follow GGCT depletion are not fully understood. Here, we show that GGCT depletion induced autophagy in MCF7 breast and PC3 prostate cancer cells. Conversely, overexpression of GGCT in NIH3T3 fibroblast under conditions of serum deprivation inhibited autophagy and increased proliferation. Simultaneous knockdown of autophagy related-protein 5, a critical effector of autophagy, along with GGCT in MCF7 and PC3 cells led to significant attenuation of the multiple cellular responses, including upregulation of CDKIs, increased numbers of senescence-associated β-galactosidase positive senescent cells, and growth inhibition. Furthermore, we show that autophagy-promoting signaling cascades including activation of the AMPK-ULK1 pathway and/or inactivation of the mTORC2-Akt pathway were triggered in GGCT-depleted cells. These results indicate that autophagy plays an important role in the growth inhibition of cancer cells caused by GGCT depletion.

Recent Advances in the Molecular Mechanisms Underlying Pyroptosis in Sepsis

Sepsis is recognized as a life-threatening organ dysfunctional disease that is caused by dysregulated host responses to infection. Up to now, sepsis still remains a dominant cause of multiple organ dysfunction syndrome (MODS) and death among severe condition patients. Pyroptosis, originally named after the Greek words “pyro” and “ptosis” in 2001, has been defined as a specific programmed cell death characterized by release of inflammatory cytokines. During sepsis, pyroptosis is required for defense against bacterial infection because appropriate pyroptosis can minimize tissue damage. Even so, pyroptosis when overactivated can result in septic shock, MODS, or increased risk of secondary infection. Proteolytic cleavage of gasdermin D (GSDMD) by caspase-1, caspase-4, caspase-5, and caspase-11 is an essential step for the execution of pyroptosis in activated innate immune cells and endothelial cells stimulated by cytosolic lipopolysaccharide (LPS). Cleaved GSDMD also triggers NACHT, LRR, and PYD domain-containing protein (NLRP) 3-mediated activation of caspase-1 via an intrinsic pathway, while the precise mechanism underlying GSDMD-induced NLRP 3 activation remains unclear. Hence, this study provides an overview of the recent advances in the molecular mechanisms underlying pyroptosis in sepsis.

miR-142-3p regulates autophagy by targeting ATG16L1 in thymic-derived regulatory T cell (tTreg)

Thymic-derived regulatory T cell (tTreg) clinical trials show therapeutic promise in the prevention of acute graft-versus-host disease (GVHD) in allogeneic hematopoietic stem cell transplantation patients. However, strategies are needed to improve tTreg proliferative ability and survival as a means to improve tTreg therapy and reduce the requirement for producing large numbers of Treg cells for adoptive tTreg transfer. Autophagy is a self-degradative process for cytosolic components, which is involved in cells death, differentiation, lymphocyte homeostasis, and tTreg function. Studies have shown that mice with tTreg cells that have a disrupted autophagy process have defective tTreg cell generation and function, resulting in autoimmune disease and failed GVHD prevention by adoptively transferred tTreg cells. We found the attenuated autophagy status during ex vivo expansion, which leads us to determine whether tTreg cell survival could be augmented by miR-142-3p, the miRNA which is highly expressed in tTreg cells and potentially targets autophagy-related protein (ATG)-1, ATG16L1. We demonstrate that miR-142-3p downregulates ATG16L1 mRNA and production of ATG16L1, that has been linked to autoimmune diseases. Conversely, miR-142-3p knock-down improved tTreg cell expansion, survival and function in vitro and vivo. In aggregate, these studies provide a new approach that uses miR-142-3p knockdown to increase tTreg cell efficacy by increasing ATG16L1 mRNA and protein and the autophagy process.

Salvianolic acid B protects against lipopolysaccharide-induced behavioral deficits and neuroinflammatory response: involvement of autophagy and NLRP3 inflammasome

Background

The NLRP3 inflammasome activation and neuroinflammation are known to be involved in the pathology of depression, whereas autophagy has multiple effects on immunity, which is partly mediated by the regulation of inflammasome and clearance of proinflammatory cytokines. Given the emerging evidence that autophagy dysfunction plays an essential role in depression, it is very likely that autophagy may interact with the inflammatory process in the development and treatment of depression. Salvianolic acid B (SalB), a naturally occurring compound extracted from Salvia miltiorrhiza, contains anti-inflammatory and antidepression properties and has recently been proven to modulate autophagy. In this study, we sought to investigate whether autophagy is involved in the inflammation-induced depression and the antidepressant effects of SalB.

Methods

The effects of prolonged lipopolysaccharide (LPS) treatment and SalB administration on behavioral changes, neuroinflammation, autophagic markers and NLRP3 activation in rat hippocampus were determined by using behavioral tests, real-time PCR analysis, western blot, and immunostaining.

Results

Our data showed that periphery immune challenge by LPS for 2 weeks successfully induced the rats to a depression-like state, accompanied with enhanced expression of pro-inflammatory cytokines and NLRP3 inflammasome activation. Interestingly, autophagic markers, including Beclin-1, and the ratio of LC3II to LC3I were suppressed following prolonged LPS exposure. Meanwhile, co-treatment with SalB showed robust antidepressant effects and ameliorated the LPS-induced neuroinflammation. Additionally, SalB restored the compromised autophagy and overactivated NLRP3 inflammasome in LPS-treated rats.

Conclusions

Collectively, these data suggest that autophagy may interact with NLRP3 activation to contribute to the development of depression, whereas SalB can promote autophagy and induce the clearance of NLRP3, thereby resulting in neuroprotective and antidepressant actions.

Rifampicin inhibits rotenone-induced microglial inflammation via enhancement of autophagy

Mitochondrial and autophagic dysfunction, as well as neuroinflammation, are associated with the pathophysiology of Parkinson's disease (PD). Rotenone, an inhibitor of mitochondrial complex I, has been associated as an environmental neurotoxin related to PD. Our previous studies reported that rifampicin inhibited microglia activation and production of proinflammatory mediators induced by rotenone, but the precise mechanism has not been completely elucidated. BV2 cells were pretreated for 2h with rifampicin followed by 0.1μM rotenone, alone or in combination with chloroquine. Here, we demonstrate that rifampicin pretreatment alleviated rotenone induced release of IL-1β and IL-6, and its effects were suppressed when autophagy was inhibited by chloroquine. Moreover, preconditioning with 50μM rifampicin significantly increased viability of SH-SY5Y cells cocultured with rotenone-treated BV2 cells in the transwell coculture system. Chloroquine partially abolished the neuroprotective effects of rifampicin pretreatment. Rifampicin pretreatment significantly reversed rotenone-induced mitochondrial membrane potential reduction and reactive oxygen species accumulation. We suggest that the mechanism for rifampicin-mediated anti-inflammatory and antioxidant effects is the enhancement of autophagy. Indeed, the ratio of LC3-II/LC3-I in rifampicin-pretreated BV2 cells was significantly higher than that in cells without pretreatment. Fluorescence and electron microscopy analyses indicate an increase of lysosomes colocalized with mitochondria in cells pretreated with rifampicin, which confirms that the damaged mitochondria were cleared through autophagy (mitophagy). Taken together, the data provide further evidence that rifampicin exerts neuroprotection against rotenone-induced microglia inflammation, partially through the autophagy pathway. Modulation of autophagy by rifampicin is a novel therapeutic strategy for PD.

Berberine attenuated pro-inflammatory factors and protect against neuronal damage via triggering oligodendrocyte autophagy in spinal cord injury

Berberine exerts neuroprotective effect in neuroinflammation and neurodegeneration disease. However, berberine effect in acute spinal cord injury is yet to be elucidated. Herein, we investigated the neuroprotective effect of berberine in spinal cord injury (SCI). Sprague-Dawley rats were subjected to SCI by an intraperitoneal injection of berberine post-injury. The neurobehavioral recovery, cytokines of pro-inflammatory factors (TNF-α and IL-1β), autophagy-related proteins (LC3B, ATG16L, ATG7), and apoptosis-related protein cleaved caspase-3 were determined. The expressions of 2', 3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase), marker of oligodendrocyte, autophagy-related proteins ATG5 and neurons at the ventral horn were assessed. In vitro, the contents of the pro-inflammatory factors, TNF-α and IL-1β, were detected in the lipopolysaccharide (LPS)-treated primary spinal neuron. Berberine significantly improved the neurobehavior BBB score and attenuated the cytokines of pro-inflammatory factors in cerebrospinal fluid post-SCI. In addition, berberine upregulated CNPase positive oligodendrocyte expressing ATG5, promoted neuronal survival and reduced the cleaved caspase-3 expression after SCI. In primary spinal neuron, the LPS-induced inflammatory factors could be reduced by berberine, whereas the autophagy inhibitor, 3-Methyladenine reverses the effect. Berberine attenuated inflammation of the injured spinal cord and reduced the neuronal apoptosis via triggering oligodendrocyte autophagy in order to promote neuronal recovery.