A20 protects neuronal apoptosis stimulated by lipopolysaccharide-induced microglial exosomes

Identification of Metabolism-Related Prognostic Biomarkers and Immune Features of Head and Neck Squamous Cell Carcinoma

We aimed to identify an effective metabolic subtype and risk score to predict survival and immunotherapy response in head and neck squamous cell carcinoma (HNSCC). Data were obtained from an online database. We screened significant prognostic metabolism-related genes between the normal and tumor groups using a series of bioinformatics methods. Based on the selected prognostic genes, we conducted a subtype analysis to identify significantly different subtypes in HNSCC. We then investigated survival, immune features, and hallmark differences among different subtypes. LASSO was utilized to identify optimal genes for the risk score model construction. Finally, distribution of the risk score samples was analyzed for different subtypes. A total of 32 significantly prognostic metabolism-related genes were screened, and all samples were grouped into two subtypes: cluster 1 and cluster 2. Cluster 1 had worse survival. Different immune cell infiltration (CD8 T cells, macrophages, and regulatory T cells) and immune checkpoint gene expression (PD-1 and CLAT-4) were observed between the two clusters. Twelve optimal genes were involved in risk score model, and high-risk group had poorer survival. Cluster 1 contained more high-risk samples (60%). Finally, four genes CAV1, GGT6, PYGL, and HS3ST1 were identified as significantly related to immune cells, and these genes were differentially expressed in the normal oral epithelial cells and HNSCC cells. The subtypes and risk score model in the study provide a promising biomarker for prognosis and immunotherapy response.

Omega-3 Polyunsaturated Fatty Acids Protect Neurological Function After Traumatic Brain Injury by Suppressing Microglial Transformation to the Proinflammatory Phenotype and Activating Exosomal NGF/TrkA Signaling

The transformation of microglia to a pro-inflammatory phenotype at the site of traumatic brain injury (TBI) drives the progression of secondary neurodegeneration and irreversible neurological impairment. Omega-3 polyunsaturated fatty acids (PUFA) have been shown to suppress this phenotype transformation, thereby reducing neuroinflammation following TBI, but the molecular mechanisms are unknown. We found that Omega-3 PUFA suppressed the expression of disintegrin metalloproteinase (ADAM17), the enzyme required to convert tumor necrosis factor-α (TNF-α) to the soluble form, thereby inhibiting the TNF-α/NF-κB pathway both in vitro and in a mouse model of TBI. Omega-3 PUFA also prevented the reactive transformation of microglia and promoted the secretion of microglial exosomes containing nerve growth factor (NGF), activating the neuroprotective NGF/TrkA pathway both in culture and TBI model mice. Moreover, Omega-3 PUFA suppressed the pro-apoptotic NGF/P75NTR pathway at the TBI site and reduced apoptotic neuronal death, brain edema, and disruption of the blood-brain barrier. Finally, Omega-3 PUFA preserved sensory and motor function as assessed by two broad-spectrum test batteries. The beneficial effects of Omega-3 PUFA were blocked by an ADAM17 promotor and by a NGF inhibitor, confirming the pathogenic function of ADAM17 and the central neuroprotective role of NGF. Collectively, these findings provide a strong experimental basis for Omega-3 PUFA as a potential clinical treatment for TBI.

Increased level of exosomal miR-20b-5p derived from hypothermia-treated microglia promotes neurite outgrowth and synapse recovery after traumatic brain injury

Mild hypothermia has been proven to inhibit microglia activation after TBI. Exosomal microRNA derived from microglia played a critical role in promoting neurite outgrowth and synapse recovery. Here, we aimed to investigate the role of microRNAs in microglial exosomes after hypothermia treatment on neuronal regeneration after TBI. For in vitro study, stretch-injured neurons were co-cultured with microglial exosomes. For in vivo study, C57BL/6 mice were under controlled cortical impact and injected with microglial exosomes. The results showed that MG-LPS-EXO^HT increased the number of dendrite branches and total length of dendrites both in vitro and in vivo, elevated the expression levels of PSD-95 and GluR1 in stretch-injured neurons, and increased spine density in the pericontusion region. Moreover, MG-LPS-EXO^HT improved motor function and motor coordination. A high-throughput sequencing showed that miR-20b-5p was upregulated in MG-LPS-EXO^HT. Elevating miR-20b-5p promoted neurite outgrowth and synapse recovery of injured neurons both in vitro and in vivo. Following mechanistic study demonstrated that miR-20b-5p might promote neurite outgrowth and synapse recovery by directly targeting PTEN and activating PI3K-AKT pathway. In conclusion, mild hypothermia could modify the microRNA prolife of exosomes derived from LPS activated BV2 cells. Furthermore, high level of microglial exosomal miR-20b-5p induced by mild hypothermia could transfer into injured neurons and promote neurite outgrowth and synapse recovery after TBI via activating the PI3K-AKT pathway by suppressing PTEN expression.

Tumor necrosis factor α–induced protein 3 mediates inflammation and neuronal autophagy in Parkinson's disease via the NFκB and mTOR pathways

This study aimed to probe the function of tumor necrosis factor α-induced protein 3 (TNFAIP3) in the pathogenesis of Parkinson disease (PD) with its association with autophagy and inflammatory response. TNFAIP3 was reduced in the SN of PD patients (the GSE54282 dataset) and mice and in the MPP⁺-treated SK-N-SH cells. TNFAIP3 inhibited inflammatory response and enhanced autophagy, thereby alleviating PD in mice. NFκB and mTOR pathways were activated in the SN of PD mice and MPP⁺-treated cells. TNFAIP3 blocked the two pathways by preventing the p65 nuclear translocation and stabilizing DEPTOR, an endogenous inhibitor of mTOR. NFκB activator LPS and mTOR activator MHY1485 reversed the effects of TNFAIP3 on mitigation of injury in PD mice and in SK-N-SH cells induced with MPP⁺. Altogether, TNFAIP3 played a neuroprotective role in MPTP-induced mice by restricting NFκB and mTOR pathways.

The link between neuroinflammation and the neurovascular unit in synucleinopathies

The neurovascular unit (NVU) is composed of vascular cells, glial cells, and neurons. As a fundamental functional module in the central nervous system, the NVU maintains homeostasis in the microenvironment and the integrity of the blood-brain barrier. Disruption of the NVU and interactions among its components are involved in the pathophysiology of synucleinopathies, which are characterized by the pathological accumulation of α-synuclein. Neuroinflammation contributes to the pathophysiology of synucleinopathies, including Parkinson's disease, multiple system atrophy, and dementia with Lewy bodies. This review aims to summarize the neuroinflammatory response of glial cells and vascular cells in the NVU. We also review neuroinflammation in the context of the cross-talk between glial cells and vascular cells, between glial cells and pericytes, and between microglia and astroglia. Last, we discuss how α-synuclein affects neuroinflammation and how neuroinflammation influences the aggregation and spread of α-synuclein and analyze different properties of α-synuclein in synucleinopathies.

Advances in the Study of the Ubiquitin-Editing Enzyme A20

Ubiquitin modification is a common post-translational protein modification and an important mechanism whereby the body regulates protein levels and functions. As a common enzyme associated with ubiquitin modification, the ubiquitin-editing enzyme A20 may be closely associated with the development of numerous pathological processes through its different structural domains. The aim of this paper is to provide an overview of the following: advances in ubiquitination research, the structure and function of A20, and the relationships between A20 and immune inflammatory response, apoptosis, necroptosis, pyroptosis, and autophagy.

Extracellular Vesicles in the Pathogenesis, Treatment, and Diagnosis of Spinal Cord Injury: A Mini-Review

BACKGROUND

Benefiting from in-depth research into stem cells, extracellular vesicles (EVs), which are byproducts of cells and membrane-wrapped microvesicles (30-120 nm) containing lipids, proteins, and nucleic acids, may cast light on the research and development of therapeutics capable of improving the neurological recovery of spinal cord injury (SCI) animals. However, the mechanistic modes of action for EVs in alleviating the lesion size of SCI remain to be solved, thus presenting a tremendous gap existing in translation from the laboratory to the clinic.

OBJECTIVE

The purpose of this minireview was to cover a wide range of basic views on EVs involved in SCI treatment, including the effects of EVs on the pathogenesis, treatment, and diagnosis of spinal cord injury.

METHODS

We searched databases (i.e., PubMed, Web of Science, Scopus, Medline, and EMBASE) and acquired all accessible articles published in the English language within five years. Studies reporting laboratory applications of EVs in the treatment of SCI were included and screened to include studies presenting relevant molecular mechanisms.

RESULTS

This review first summarized the basic role of EVs in cell communication, cell death, inflammatory cascades, scar formation, neuronal regrowth, and angiogenesis after SCI, thereby providing insights into neuroprotection and consolidated theories for future clinical application of EVs.

CONCLUSION

EVs participate in an extremely wide range of cell activities, play a critical role in cell communication centring neurons, and are considered potential therapies and biomarkers for SCI. miRNAs are the most abundant nucleic acids shipped by EVs and effluent cytokines, and they may represent important messengers of EVs and important factors in SCI treatment.

MicroRNA miR-27b-3p regulate microglial inflammation response and cell apoptosis by inhibiting A20 (TNF-α-induced protein 3)

Inflammatory reaction exerts a pivotal role in secondary damage after cerebral hemorrhage and spinal cord injury. miRNAs can both promote and inhibit inflammatory actions among microglial cells. The objective of the present paper was to figure out whether miR-27b-3p produced regulatory effects during processes of microglial inflammation. Lipopolysaccharides (LPS) were used to prepare microglial activation models. Following miR-27b-3p overexpression and interference, the RNA and protein levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β were subjected to real-time fluorescent quantitative PCR (qPCR) and western blot assays, respectively. Cellular apoptosis was subjected to flow cytometry and miR-27b-3p target genes were visualized using a dual luciferase reporter system for verification. The levels of TNF-α, IL-6, and IL-1β mRNA in miR-27b-3p-overexpressed microglial cells were markedly increased compared to the control. Apoptosis of microglial cells was increased markedly in the overexpressed miR-27b-3p group compared to the negative control. Conversely, a different result was presented in the microglial transfected with miR-27b-3p inhibitors. The downregulation of A20, a miR-27b-3p target gene, mediated levels of TNF-α, IL-6, and IL-1β. Furthermore, A20 reduced microglial apoptosis. These data revealed that miR-27b-3p could mediate not only microglia activation but also neuroinflammation via downregulating A20 expression. Thus, miR-27b-3p is regarded as gene therapy in treating cerebral hemorrhage and spinal cord injury.

Exosomes in Ageing and Motor Neurone Disease: Biogenesis, Uptake Mechanisms, Modifications in Disease and Uses in the Development of Biomarkers and Therapeutics

Intercellular communication between neurons and their surrounding cells occurs through the secretion of soluble molecules or release of vesicles such as exosomes into the extracellular space, participating in brain homeostasis. Under neuro-degenerative conditions associated with ageing, such as amyotrophic lateral sclerosis (ALS), Alzheimer's or Parkinson's disease, exosomes are suspected to propagate toxic proteins. The topic of this review is the role of exosomes in ageing conditions and more specifically in ALS. Our current understanding of exosomes and exosome-related mechanisms is first summarized in a general sense, including their biogenesis and secretion, heterogeneity, cellular interaction and intracellular fate. Their role in the Central Nervous System (CNS) and ageing of the neuromotor system is then considered in the context of exosome-induced signaling. The review then focuses on exosomes in age-associated neurodegenerative disease. The role of exosomes in ALS is highlighted, and their use as potential biomarkers to diagnose and prognose ALS is presented. The therapeutic implications of exosomes for ALS are considered, whether as delivery vehicles, neurotoxic targets or as corrective drugs in and of themselves. A diverse set of mechanisms underpin the functional roles, both confirmed and potential, of exosomes, generally in ageing and specifically in motor neurone disease. Aspects of their contents, biogenesis, uptake and modifications offer many plausible routes towards the development of novel biomarkers and therapeutics.

Deubiquitinases: Modulators of Different Types of Regulated Cell Death

The mechanisms and physiological implications of regulated cell death (RCD) have been extensively studied. Among the regulatory mechanisms of RCD, ubiquitination and deubiquitination enable post-translational regulation of signaling by modulating substrate degradation and signal transduction. Deubiquitinases (DUBs) are involved in diverse molecular pathways of RCD. Some DUBs modulate multiple modalities of RCD by regulating various substrates and are powerful regulators of cell fate. However, the therapeutic targeting of DUB is limited, as the physiological consequences of modulating DUBs cannot be predicted. In this review, the mechanisms of DUBs that regulate multiple types of RCD are summarized. This comprehensive summary aims to improve our understanding of the complex DUB/RCD regulatory axis comprising various molecular mechanisms for diverse physiological processes. Additionally, this review will enable the understanding of the advantages of therapeutic targeting of DUBs and developing strategies to overcome the side effects associated with the therapeutic applications of DUB modulators.

The influence of the R47H triggering receptor expressed on myeloid cells 2 variant on microglial exosome profiles

Variants in the triggering receptor expressed on myeloid cells 2 gene are linked with an increased risk of dementia, in particular the R47Hhet triggering receptor expressed on myeloid cells 2 variant is linked to late-onset Alzheimer's disease. Using human induced pluripotent stem cells-derived microglia, we assessed whether variations in the dynamics of exosome secretion, including their components, from these cells might underlie some of this risk. We found exosome size was not altered between common variant controls and R47Hhet variants, but the amount and constitution of exosomes secreted were different. Exosome quantities were rescued by incubation with an ATP donor or with lipids via a phosphatidylserine triggering receptor expressed on myeloid cells 2 ligand. Following a lipopolysaccharide or phagocytic cell stimulus, exosomes from common variant and R47Hhet microglia were found to contain cytokines, chemokines, APOE and triggering receptor expressed on myeloid cells 2. Differences were observed in the expression of CCL22, IL-1β and triggering receptor expressed on myeloid cells 2 between common variant and R47Hhet derived exosomes. Furthermore unlike common variant-derived exosomes, R47Hhet exosomes contained additional proteins linked to negative regulation of transcription and metabolic processes. Subsequent addition of exosomes to stressed neurones showed R47Hhet-derived exosomes to be less protective. These data have ramifications for the responses of microglia in Alzheimer's disease and may point to further targets for therapeutic intervention.

The Role of Lipopolysaccharide-Induced Extracellular Vesicles in Cardiac Cell Death

Exosomes play a crucial role in the progression of infectious diseases, as exosome release and biogenesis are affected by external factors, such as pathogenic infections. Pyrogens may aide in the progression of diseases by triggering inflammation, endothelial cell injury, and arterial plaque rupture, all of which can lead to acute coronary disease, resulting in cardiac tissue death and the onset of a cardiac event (CE). To better understand the effects of Gram-negative bacterial infections on exosome composition and biogenesis, we examined exosome characteristics after treatment of AC16 human cardiomyocytes with lipopolysaccharide (LPS), which served as a model system for Gram-negative bacterial infection. Using increasing doses (0, 0.1, 1, or 10 µg) of LPS, we showed that treatment with LPS substantially altered the composition of AC16-derived exosomes. Both the relative size and the quantity (particles/mL) of exosomes were decreased significantly at all tested concentrations of LPS treatment compared to the untreated group. In addition, LPS administration reduced the expression of exosomal proteins that are related to exosomal biogenesis. Conversely, we observed an increase in immunomodulators present after LPS administration. This evaluation of the impact of LPS on cardiac cell death and exosome composition will yield new insight into the importance of exosomes in a variety of physiological and pathological processes as it relates to disease progression, diagnosis, and treatment.