Comparative evaluation of cigarette smoke and a heated tobacco product on microglial toxicity, oxidative stress and inflammatory response.

BACKGROUND: Tobacco smoking is the leading cause of preventable death and disease worldwide, with over 8 million annual deaths attributed to cigarette smoking. This study investigates the impact of cigarette smoke and heated tobacco products (HTPs) on microglial function, focusing on toxicological profiles, inflammatory responses, and oxidative stress using ISO standard and clinically relevant conditions of exposure. METHODS: We assessed cell viability, reactive oxygen species (ROS) production, lipid peroxidation, mitochondrial function, unfolded protein response, and inflammation in human microglial cells (HMC3) exposed to cigarette smoke, HTP aerosol or nicotine. RESULTS: Our findings show that cigarette smoke significantly reduces microglial viability, increases ROS formation, induces lipid peroxidation, and reduces intracellular glutathione levels. Cigarette smoke also alters the expression of genes involved in mitochondrial dynamics and biogenesis, leading to mitochondrial dysfunction. Additionally, cigarette smoke impairs the unfolded protein response, activates the NF-κB pathway, and induces a pro-inflammatory state characterized by increased TNF and IL-18 expression. Furthermore, cigarette smoke causes DNA damage and decreases the expression of the aging marker Klotho ß. In contrast, HTP, exhibited a lesser degree of microglial toxicity, with reduced ROS production, lipid peroxidation, and mitochondrial dysfunction compared to conventional cigarettes. CONCLUSION: These results highlight the differential toxicological profile of cigarette smoke and HTP on microglial cells, suggesting a potential harm reduction strategy for neurodegenerative disease for smokers unwilling or unable to quit.

The Neolignan Honokiol and Its Synthetic Derivative Honokiol Hexafluoro Reduce Neuroinflammation and Cellular Senescence in Microglia Cells.

Microglia-mediated neuroinflammation has been linked to neurodegenerative disorders. Inflammation and aging contribute to microglial senescence. Microglial senescence promotes the development of neurodegenerative disorders, including Alzheimer's disease (AD). In this study, we investigated the anti-neuroinflammatory and anti-senescence activity of Honokiol (HNK), a polyphenolic neolignane from Magnolia officinalis Rehder & E.H Wilson, in comparison with its synthetic analogue Honokiol Hexafluoro (CH). HNK reduced the pro-inflammatory cell morphology of LPS-stimulated BV2 microglia cells and increased the expression of the anti-inflammatory cytokine IL-10 with an efficacy comparable to CH. HNK and CH were also able to attenuate the alterations in cell morphology associated with cellular senescence in BV2 cells intermittently stimulated with LPS and significantly reduce the activity and expression of the senescence marker ß-galactosidase and the expression of p21 and pERK1/2. The treatments reduced the expression of senescence-associated secretory phenotype (SASP) factors IL-1ß and NF-kB, decreased ROS production, and abolished H2AX over phosphorylation (γ-H2AX) and acetylated H3 overexpression. Senescent microglia cells showed an increased expression of the Notch ligand Jagged1 that was reduced by HNK and CH with a comparable efficacy to the Notch inhibitor DAPT. Overall, our data illustrate a protective activity of HNK and CH on neuroinflammation and cellular senescence in microglia cells involving a Notch-signaling-mediated mechanism and suggesting a potential therapeutic contribution in aging-related neurodegenerative diseases.

GSP1-111 Modulates the Microglial M1/M2 Phenotype by Inhibition of Toll-like Receptor 2: A Potential Therapeutic Strategy for Depression.

Neuroinflammation plays a vital role in neurodegenerative diseases and neuropsychiatric disorders, and microglia and astrocytes chiefly modulate inflammatory responses in the central nervous system (CNS). Toll-like receptors (TLRs), which are expressed in neurons, astrocytes, and microglia in the CNS, are critical for innate immune responses; microglial TLRs can regulate the activity of these cells, inducing protective or harmful effects on the surrounding cells, including neurons. Therefore, regulating TLRs in microglia may be a potential therapeutic strategy for neurological disorders. We examined the protective effects of GSP1-111, a novel synthetic peptide for inhibiting TLR signaling, on neuroinflammation and depression-like behavior. GSP1-111 decreased TLR2 expression and remarkably reduced the mRNA expression of inflammatory M1-phenotype markers, including tumor necrosis factor (TNF)α, interleukin (IL)-1ß, and IL-6, while elevating that of the M2 phenotype markers, Arg-1 and IL-10. In vivo, GSP1-111 administration significantly decreased the depression-like behavior induced by lipopolysaccharide (LPS) in a forced swim test and significantly reduced the brain levels of M1-specific inflammatory cytokines (TNFα, IL-1ß, and IL-6). GSP1-111 prevented the LPS-induced microglial activation and TLR2 expression in the brain. Accordingly, GSP1-111 prevented inflammatory responses and induced microglial switching of the inflammatory M1 phenotype to the protective M2 phenotype. Thus, GSP1-111 could prevent depression-like behavior by inhibiting TLR2. Taken together, our results suggest that the TLR2 pathway is a promising therapeutic target for depression, and GSP1-111 could be a novel therapeutic candidate for various neurological disorders.

Adenosine triphosphate release inhibitors targeting pannexin1 improve recovery after spinal cord injury.

Traumatic spinal cord injury is characterized by immediate and irreversible tissue loss at the lesion site and secondary tissue damage. Secondary injuries should, in principle, be preventable, although no effective treatment options currently exist for patients with acute spinal cord injury. Traumatized tissues release excessive amounts of adenosine triphosphate and activate the P2X purinoceptor 7/pannexin1 complex, which is associated with secondary injury. We investigated the neuroprotective effects of the blue dye Brilliant Blue FCF, a selective inhibitor of P2X purinoceptor 7/pannexin1 that is approved for use as a food coloring, by comparing it with Brilliant Blue G, a P2X7 purinoceptor antagonist, and carbenoxolone, which attenuates P2X purinoceptor 7/pannexin1 function, in a rat spinal cord injury model. Brilliant Blue FCF administered early after spinal cord injury reduced spinal cord anatomical damage and improved motor recovery without apparent toxicity. Brilliant Blue G had the highest effect on this neurological recovery, with Brilliant Blue FCF and carbenoxolone having comparable improvement. Furthermore, Brilliant Blue FCF administration reduced local astrocytic and microglial activation and neutrophil infiltration, and no differences in these histological effects were observed between compounds. Thus, Brilliant Blue FCF protects spinal cord neurons after spinal cord injury and suppresses local inflammatory responses as well as Brilliant Blue G and carbenoxolone.

Revealing the Novel Role of Purinergic Receptor P2X4 in Phagocytic Uptake After Ischemic Stroke.

BACKGROUND: Purinergic receptor P2X4 (P2X4R), highly expressed on microglia and macrophages, is activated by ATP released from damaged cells and linked to poststroke inflammation. Previous studies showed that short-term P2X4R inhibition reduces inflammation and promotes long term recovery, but the mechanism underlying P2X4R and inflammation remains unclear. We hypothesized that P2X4R absence or pharmacological blockade can enhance macrophage phagocytic function by alleviating excessive inflammation after stroke. METHODS AND RESULTS: We divided P2X4R knockout and littermate control mice into 2 groups either naive or mice subjected to ischemic stroke surgery. Additionally, the regular WT mice subjected to ischemic stroke were treated with 5-(3-Bromophenyl)-1,3-dihydro-2H-Benzofuro[3,2-e]-1,4-diazepin-2-one BD (a P2X4R inhibitor) or vehicle. We isolated phagocytic cells from mice in each group and assayed phagocytic activity by quantifying uptake of fluorescent beads and bioparticles using flow cytometry or confocal microscopy and by measuring protein expression related to phagocytosis. Short-term inhibition of P2X4R with with 5-(3-Bromophenyl)-1,3-dihydro-2H-Benzofuro[3,2-e]-1,4-diazepin-2-one treatment upregulated ANXA1 (annexinA1). P2X4R absence prevented ATP-induced decline in phagocytic uptake in macrophages. Microglia or macrophages derived from P2X4R knockout mice showed significantly increased phagocytic activity compared with microglia/macrophages taken from littermate control mice. Cell surface expression of CD36, a scavenger receptor protein, increased after stroke, and was higher in P2X4R knockout mice. CONCLUSIONS: This study suggests that blockade or absence of P2X4R increases phagocytic uptake of damaged tissue following ischemic stroke. Taken together with previous reports detailing how P2X4R inhibition is protective following stroke, our results demonstrate P2X4R may mediate long-term resolution after ischemic stroke by enhancing phagocytic clearance.

Morphine induces inflammatory responses via both TLR4 and cGAS-STING signaling pathways.

BACKGROUND: Opioid activation of the microglia or macrophage Toll-like receptor 4 (TLR4) and associated inflammatory cytokine release are implicated in opioid-induced hyperalgesia and tolerance. The cyclic GMP-AMP synthase/stimulator of interferon genes (cGAS-STING) signaling pathway, activated by double-stranded DNA including mitochondrial DNA (mtDNA), has emerged as another key mediator of inflammatory responses. This study tested the hypothesis that morphine induces immune inflammatory responses in microglia and macrophages involving TLR4 and cGAS-STING pathway. METHODS: BV2 microglia and Raw 264.7 (Raw) macrophage cells were exposed to morphine with and without a STING inhibitor (C176) for 6 h or TLR 4 inhibitor (TAK242) for 24 h. Western blotting and RT-qPCR analyses assessed TLR4, cGAS, STING, nuclear factor-kappa B (NF-κB), and pro-inflammatory cytokine expression. Morphine-induced mitochondria dysfunction was quantified by reactive oxygen species (ROS) release using MitoSOX, mtDNA release by immunofluorescence, and RT-qPCR. Polarization of BV2 and Raw cells was assessed by inducible nitric oxide (iNOS) and CD86 expression. The role of mtDNA on morphine-related inflammation was investigated by mtDNA depletion of the cells with ethidium bromide (EtBr) or cell transfection of mtDNA extracted from morphine-treated cells. RESULTS: Morphine significantly increased the expression of TLR4, cGAS, STING, p65 NF-κB, and cytokines (IL-6 and TNF-α) in BV2 and Raw cells. Morphine-induced mitochondrial dysfunction by increased ROS and mtDNA release; the increased iNOS and CD86 evidenced inflammatory M1-like phenotype polarization. TLR4 and STING inhibitors reduced morphine-induced cytokine release in both cell types. The transfection of mtDNA activated inflammatory signaling proteins, cytokine release, and polarization. Conversely, mtDNA depletion led to the reversal of these effects. CONCLUSION: Morphine activates the cGAS-STING pathway in macrophage cell types. Inhibition of the STING pathway can be an additional method to overcome immune cell inflammation-related morphine tolerance and opioid-induced hyperalgesia.

Facile engineered macrophages-derived exosomes-functionalized PLGA nanocarrier for targeted delivery of dual drug formulation against neuroinflammation by modulation of microglial polarization in a post-stroke depression rat model.

Post-stroke depression (POSD) is a common difficulty and most predominant emotional syndrome after stroke often consequences in poor outcomes. In the present investigation, we have designed and studied the neurologically active celastrol/minocycline encapsulated with macrophages-derived exosomes functionalized PLGA nanoformulations (CMC-EXPL) to achieve enhanced anti-inflammatory behaviour and anti-depressant like activity in a Rat model of POSD. The animal model of POSD was established through stimulating process with chronic unpredictable mild stress (CUM) stimulations after procedure of middle cerebral artery occlusion (MCAO). Neuronal functions and Anti-inflammation behaviours were observed by histopathological (H&E) examination and Elisa analyses, respectively. The anti-depressive activity of the nanoformulations treated Rat models were evaluated by open-field and sucrose preference test methods. Microglial polarization was evaluated via flow-cytometry and qRT-PCR observations. The observed results exhibited that prepared nanoformulations reduced the POSD-stimulated depressive-like activities in rat models as well alleviated the neuronal damages and inflammatory responses in the cerebral hippocampus. Importantly, prepared CMC-EXPL nanoformulation effectively prevented the M1 pro-inflammatory polarization and indorsed M2 anti-inflammatory polarization, which indicates iNOS and CD86 levels significantly decreased and upsurged Arg-1 and CD206 levels. CMC-EXPL nanoformulation suggestively augmented anti-depressive activities and functional capability and also alleviated brain inflammation in POSD rats, demonstrating its therapeutic potential for POSD therapy.

[Protective effect and mechanism of Zuogui Jiangtang Jieyu Formula on damage to hippocampal synaptic microenvironment in rats with diabetes-related depression based on microglia-neuron crosstalk signal CD300f/TLR4].

This study aims to reveal the protective effect and mechanism of Zuogui Jiangtang Jieyu Formula on the damage to hippo-campal synaptic microenvironment in rats with diabetes-related depression(DD) via regulating microglia immune receptor molecule-like family member f(CD300f)/Toll-like receptor 4(TLR4) signal. Firstly, the model of DD rats was established by a two-week high-fat diet+STZ injection+chronic mild and unpredictable stress plus isolation for 28 days. The rats were randomly divided into normal group, model group, CD300f blocker(CLM1, 2 µg·kg~(-1)) group, CD300f agonist(Fcγ, 5 µg·kg~(-1)) group, positive drug(0.18 g·kg~(-1) metformin+1.8 mg·kg~(-1) fluoxetine) group, and high-dose and low-dose(20.52 and 10.26 g·kg~(-1)) Zuogui Jiangtang Jieyu Formula groups. Depression-like behavior of rats was evaluated by open field and forced swimming experiments. The levels of blood glucose and insulin were detected by biochemical analysis. The levels of tumor necrosis factor α(TNF-α), interleukin-1ß(IL-1ß), indoleamine 2, 3-dioxygenase(IDO), 5-hydroxytryptamine(5-HT), and dopamine(DA) in the hippocampus were detected by enzyme-linked immunosorbent assay. The changes in the synaptic ultrastructure in hippocampal neurons of rats were observed by transmission electron microscopy. The protein expressions of CD300f, TLR4, synaptophysin(SYN), and postsynaptic density protein 95(PSD-95) in microglial cells of the hippocampus were detected by immunofluorescence and Western blot. The results indicated that compared with that in the normal group, the total movement distance in open field experiments was reduced in the model group, and the immobility time in forced swimming experiments increased, with an elevated insulin level in serum, as well as TNF-α, IL-1ß, and IDO levels in the hippocampus. The 5-HT and DA levels in the hippocampus were reduced. In addition, the CD300f expression was down-regulated in microglial cells of the hippocampus, and the TLR4 expression was up-regulated. Moreover, the expression of synapse-related proteins SYN and PSD-95 in hippocampal neurons decreased, and the synaptic ultrastructure of hippocampal neurons was significantly damaged. Compared with the model group, the CD300f blocker and agonist aggravated and alleviated the above abnormal changes, respectively. High-dose and low-dose Zuogui Jiangtang Jieyu Formula could significantly improve the above depression-like beha-vior in rats, inhibit the abnormal increase of TNF-α, IL-1ß, and IDO and the decrease of 5-HT and DA, effectively increase the expression of CD300f in microglial cells, and decrease the expression of TLR4. They could up-regulate the protein expression of presyna-ptic membrane SYN and postsynaptic membrane PSD-95 in hippocampal neurons and finally improve the damage to the hippocampal synaptic microenvironment. In conclusion, this research confirmed that Zuogui Jiangtang Jieyu Formula effectively alleviated the depression-like behavior and inhibited inflammatory activation of microglial cells in the hippocampus of rats with DD, and the mechanism might be related to the regulation of CD300f/TLR4 signal to alleviate the damage to hippocampal synaptic microenvironment.

α-linolenic acid mitigates microglia-mediated neuroinflammation of schizophrenia in mice by suppressing the NF-κB/NLRP3 pathway via binding GPR120-ß-arrestin 2.

BACKGROUND: Schizophrenia (SCZ) is a heterogeneous psychiatric disorder that is poorly treated by current therapies. Emerging evidence indicates that SCZ is closely correlated with a persistent neuroinflammation. α-linolenic acid (ALA) is highly concentrated in the brain and represents a modulator of the immune system by decreasing the inflammatory response in chronic metabolic diseases. This study was first designed to investigate the potential role of dietary ALA on cognitive function and neuroinflammation in mice with SCZ. METHODS: In vivo, after 2 weeks of modeling, mice were treated with dietary ALA treatment for 6 weeks. In vitro, inflammation model was created using lipopolysaccharide as an inducer in BV2 microglial cells. RESULTS: Our results demonstrated that ALA alleviated cognitive impairment and enhanced synaptic plasticity in mice with SCZ. Moreover, ALA mitigated systematic and cerebral inflammation through elevating IL-10 and inhibiting IL-1ß, IL-6, IL-18 and TNF-α. Furthermore, ALA notably inhibited microglia and pro-inflammatory monocytes, as well as microglial activation andpolarization. Mechanistically, ALA up-regulated the expressions of G protein coupled receptor (GPR) 120 and associated ß-inhibitor protein 2 (ß-arrestin2), accompanied by observable weakened levels of transforming growth factor-ß activated kinase 1 (TAK1), NF-κB p65, cysteine proteinase-1 (caspase-1), pro-caspase-1, associated speck-like protein (ASC) and NLRP3. In vitro, ALA directly restrained the inflammation of microglia by decreasing the levels of pro-inflammatory factors and regulating microglial polarization via GPR120-NF-κB/NLRP3inflammasome signaling pathway, whereas AH7614 definitely eliminated this anti-inflammatory effect of ALA. CONCLUSION: Dietary ALA ameliorates microglia-mediated neuroinflammation by suppressing the NF-κB/NLRP3 pathway via binding GPR120-ß-arrestin2.

Solanesol Ameliorates Anxiety-like Behaviors via the Downregulation of Cingulate T Cell-Restricted Intracellular Antigen-1 in a Complete Freund's Adjuvant-Induced Mouse Model.

Anxiety disorder is a universal disease related to neuro-inflammation. Solanesol has shown positive effects because of its anti-inflammatory, anti-tumor, and anti-ulcer properties. This study focused on determining whether solanesol could ameliorate anxiety-like behaviors in a mouse model of neuro-inflammation and identify its working targets. Complete Freund's adjuvant (CFA)-induced mice that were intra-peritoneally administered with solanesol (50 mg/kg) for 1 week showed a statistically significant reduction in anxiety-like behaviors, as measured by open field and elevated plus-maze tests. Western blot analysis revealed that CFA-induced upregulation of the levels of pro-inflammatory cytokines interleukin (IL)-1ß and tumor necrosis factor α (TNF-α), which played crucial roles in regulating anxiety, returned to normal in the anterior cingulate cortex (ACC) after solanesol treatment. The level of T cell-restricted intracellular antigen-1 (TIA1), a key component of stress granules, also decreased in the ACC. Moreover, immunofluorescence results indicated that solanesol suppressed CFA-induced microglial and astrocytic activation in the ACC. CFA was injected in the hind paws of TIA1Nestin conditional knockout (cKO) mice to confirm whether TIA1 is a potential modulatory molecule that influences pro-inflammatory cytokines and anxiety-like behaviors. Anxiety-like behaviors could not be observed in cKO mice after CFA injection with IL-1ß and TNF-α levels not remarkedly increasing. Our findings suggest that solanesol inhibits neuro-inflammation by decreasing the TIA1 level to reduce IL-1ß and TNF-α expression, meanwhile inhibiting microglial and astrocytic activation in the ACC and ultimately ameliorating anxiety-like behaviors in mice.

Single-cell RNA sequencing integrated with bulk RNA sequencing analysis reveals the protective effects of lactate-mediated lactylation of microglia-related proteins on spinal cord injury.

BACKGROUND AND OBJECTIVES: Spinal cord injury (SCI) results in significant neurological deficits, and microglia play the critical role in regulating the immune microenvironment and neurological recovery. Protein lactylation has been found to modulate the function of immune cells. Therefore, this study aimed to elucidate the effects of glycolysis-derived lactate on microglial function and its potential neuroprotective mechanisms via lactylation after SCI. METHODS: Single-cell RNA sequencing (scRNA-seq) data were obtained from figshare to analyze cellular and molecular alterations within the spinal cord post-SCI, further focusing on the expression of microglia-related genes for cell sub-clustering, trajectory analysis, and glycolysis function analysis. We also evaluated the expression of lactylation-related genes in microglia between day 7 after SCI and sham group. Additionally, we established the mice SCI model and performed the bulk RNA sequencing in a time-dependent manner. The expression of glycolysis- and lactylation-related genes was evaluated, as well as the immune infiltration analysis based on the lactylation-related genes. Then, we investigated the bio-effects of lactate on the inflammation and polarization phenotype of microglia. Finally, adult male C57BL/6 mice were subjected to exercise first to increase lactate level, before SCI surgery, aiming to evaluate the protective effects of lactate-mediated lactylation of microglia-related proteins on SCI. RESULTS: scRNA-seq identified a subcluster of microglia, recombinant chemokine C-X3-C-motif receptor 1+ (CX3CR1+) microglia, which is featured by M1-like phenotype and increased after SCI. KEGG analysis revealed the dysfunctional glycolysis in microglia after SCI surgery, and AUCell analysis suggested that the decreased glycolysis an increased oxidative phosphorylation in CX3CR1+ microglia. Differential gene analysis suggested that several lactylation-related genes (Fabp5, Lgals1, Vim, and Nefl) were downregulated in CX3CR1+ microglia at day 7 after SCI, further validated by the results from bulk RNA sequencing. Immunofluorescence staining indicated the expression of lactate dehydrogenase A (LDHA) in CX3CR1+ microglia also decreased at day 7 after SCI. Cellular experiments demonstrated that the administration of lactate could increase the lactylation level and inhibit the pro-inflammatory phenotype in microglia. Functionally, exercise-mediated lactate production resulted in improved locomotor recovery and decreased inflammatory markers in SCI mice compared to SCI alone. CONCLUSIONS: In the subacute phase of SCI, metabolic remodeling in microglia may be key therapeutic targets to promote nerve regeneration, and lactate contributed to neuroprotection after SCI by influencing microglial lactylation and inflammatory phenotype, which offered a novel approach for therapeutic intervention.

Microglia either promote or restrain TRAIL-mediated excitotoxicity caused by Aß1-42 oligomers.

BACKGROUND: Alzheimer's disease (AD) features progressive neurodegeneration and microglial activation that results in dementia and cognitive decline. The release of soluble amyloid (Aß) oligomers into the extracellular space is an early feature of AD pathology. This can promote excitotoxicity and microglial activation. Microglia can adopt several activation states with various functional outcomes. Protective microglial activation states have been identified in response to Aß plaque pathology in vivo. However, the role of microglia and immune mediators in neurotoxicity induced by soluble Aß oligomers is unclear. Further, there remains a need to identify druggable molecular targets that promote protective microglial states to slow or prevent the progression of AD. METHODS: Hippocampal entorhinal brain slice culture (HEBSC) was employed to study mechanisms of Aß1-42 oligomer-induced neurotoxicity as well as the role of microglia. The roles of glutamate hyperexcitation and immune signaling in Aß-induced neurotoxicity were assessed using MK801 and neutralizing antibodies to the TNF-related apoptosis-inducing ligand (TRAIL) respectively. Microglial activation state was manipulated using Gi-hM4di designer receptor exclusively activated by designer drugs (DREADDs), microglial depletion with the colony-stimulating factor 1 receptor (CSF1R) antagonist PLX3397, and microglial repopulation (PLX3397 withdrawal). Proteomic changes were assessed by LC-MS/MS in microglia isolated from control, repopulated, or Aß-treated HEBSCs. RESULTS: Neurotoxicity induced by soluble Aß1-42 oligomers involves glutamatergic hyperexcitation caused by the proinflammatory mediator and death receptor ligand TRAIL. Microglia were found to have the ability to both promote and restrain Aß-induced toxicity. Induction of microglial Gi-signaling with hM4di to prevent pro-inflammatory activation blunted Aß neurotoxicity, while microglial depletion with CSF1R antagonism worsened neurotoxicity caused by Aß as well as TRAIL. HEBSCs with repopulated microglia, however, showed a near complete resistance to Aß-induced neurotoxicity. Comparison of microglial proteomes revealed that repopulated microglia have a baseline anti-inflammatory and trophic phenotype with a predicted pathway activation that is nearly opposite that of Aß-exposed microglia. mTORC2 and IRF7 were identified as potential targets for intervention. CONCLUSION: Microglia are key mediators of both protection and neurodegeneration in response to Aß. Polarizing microglia toward a protective state could be used as a preventative strategy against Aß-induced neurotoxicity.

Fasudil attenuates syncytin-1-mediated activation of microglia and impairments of motor neurons and motor function in mice.

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease. Syncytin-1 (Syn), an envelope glycoprotein encoded by the env gene of the human endogenous retrovirus-W family, has been resorted to be highly expressed in biopsies from the muscles from ALS patients; however, the specific regulatory role of Syn during ALS progression remains uncovered. In this study, C57BL/6 mice were injected with adeno-associated virus-overexpressing Syn, with or without Fasudil administration. The Syn expression was assessed by quantitative real-time polymerase chain reaction and immunohistochemistry analysis. The histological change of anterior tibial muscles was determined by hematoxylin-eosin staining. Qualitative ultrastructural analysis of electron micrographs obtained from lumbar spinal cords was carried out. Serum inflammatory cytokines were assessed by enzyme linked immunosorbent assay (ELISA) assay and motor function was recorded using Basso, Beattie, and Bresnahan (BBB) scoring, climbing test and treadmill running test. Immunofluorescence and western blot assays were conducted to examine microglial- and motor neurons-related proteins. Syn overexpression significantly caused systemic inflammatory response, muscle tissue lesions, and motor dysfunction in mice. Meanwhile, Syn overexpression promoted the impairment of motor neuron, evidenced by the damaged structure of the neurons and reduced expression of microtubule-associated protein 2, HB9, neuronal nuclei and neuron-specific enolase in Syn-induced mice. In addition, Syn overexpression greatly promoted the expression of CD16/CD32 and inducible nitric oxide synthase (M1 phenotype markers), and reduced the expression of CD206 and arginase 1 (M2 phenotype markers). Importantly, the above changes caused by Syn overexpression were partly abolished by Fasudil administration. This study provides evidence that Syn-activated microglia plays a pivotal role during the progression of ALS.

Tyrosine phosphorylation and palmitoylation of TRPV2 ion channel tune microglial beta-amyloid peptide phagocytosis.

Alzheimer's disease (AD) is the leading form of dementia, characterized by the accumulation and aggregation of amyloid in brain. Transient receptor potential vanilloid 2 (TRPV2) is an ion channel involved in diverse physiopathological processes, including microglial phagocytosis. Previous studies suggested that cannabidiol (CBD), an activator of TRPV2, improves microglial amyloid-ß (Aß) phagocytosis by TRPV2 modulation. However, the molecular mechanism of TRPV2 in microglial Aß phagocytosis remains unknown. In this study, we aimed to investigate the involvement of TRPV2 channel in microglial Aß phagocytosis and the underlying mechanisms. Utilizing human datasets, mouse primary neuron and microglia cultures, and AD model mice, to evaluate TRPV2 expression and microglial Aß phagocytosis in both in vivo and in vitro. TRPV2 was expressed in cortex, hippocampus, and microglia.Cannabidiol (CBD) could activate and sensitize TRPV2 channel. Short-term CBD (1 week) injection intraperitoneally (i.p.) reduced the expression of neuroinflammation and microglial phagocytic receptors, but long-term CBD (3 week) administration (i.p.) induced neuroinflammation and suppressed the expression of microglial phagocytic receptors in APP/PS1 mice. Furthermore, the hyper-sensitivity of TRPV2 channel was mediated by tyrosine phosphorylation at the molecular sites Tyr(338), Tyr(466), and Tyr(520) by protein tyrosine kinase JAK1, and these sites mutation reduced the microglial Aß phagocytosis partially dependence on its localization. While TRPV2 was palmitoylated at Cys 277 site and blocking TRPV2 palmitoylation improved microglial Aß phagocytosis. Moreover, it was demonstrated that TRPV2 palmitoylation was dynamically regulated by ZDHHC21. Overall, our findings elucidated the intricate interplay between TRPV2 channel regulated by tyrosine phosphorylation/dephosphorylation and cysteine palmitoylation/depalmitoylation, which had divergent effects on microglial Aß phagocytosis. These findings provide valuable insights into the underlying mechanisms linking microglial phagocytosis and TRPV2 sensitivity, and offer potential therapeutic strategies for managing AD.

HSV-1 immune escapes in microglia by down-regulating GM130 to inhibit TLR3-mediated innate immune responses.

BACKGROUND: To investigate the mechanism of Golgi matrix protein 130(GM130) regulating the antiviral immune response of TLR3 after herpes simplex virus type 1(HSV-1) infection of microglia cells. We explored the regulatory effects of berberine on the immune response mediated by GM130 and TLR3. METHODS: An in vitro model of HSV-1 infection was established by infecting BV2 cells with HSV-1. RESULTS: Compared to the uninfected group, the Golgi apparatus (GA) fragmentation and GM130 decreased after HSV-1 infection; TLR3 increased at 6 h and began to decrease at 12 h after HSV-1 infection; the secretion of interferon-beta(IFN-ß), tumour necrosis factor alpha(TNF-α), and interleukin-6(IL-6) increased after infection. Knockdown of GM130 aggravated fragmentation of the GA and caused TLR3 to further decrease, and the virus titer also increased significantly. GM130 knockdown inhibits the increase in TLR3 and inflammatory factors induced by TLR3 agonists and increases the viral titer. Overexpression of GM130 alleviated fragmentation of the GA induced by HSV-1, partially restored the levels of TLR3, and reduced viral titers. GM130 overexpression reversed the reduction in TLR3 and inflammatory cytokine levels induced by TLR3 inhibitors. Therefore, the decrease in GM130 levels caused by HSV-1 infection leads to increased viral replication by inhibiting TLR3-mediated innate immunity. Berberine can protect the GA and reverse the downregulation of GM130, as well as the downregulation of TLR3 and its downstream factors after HSV-1 infection, reducing the virus titer. CONCLUSIONS: In microglia, one mechanism of HSV-1 immune escape is disruption of the GM130/TLR3 pathway. Berberine protects the GA and enhances TLR3-mediated antiviral immune responses.

ROS exhaustion reverses the effects of hyperbaric oxygen on hemorrhagic transformation through reactivating microglia in post-stroke hyperglycemic mice.

Acute ischemic stroke (AIS) is a major global health concern due to its high mortality and disability rates. Hemorrhagic transformation, a common complication of AIS, leads to poor prognosis yet lacks effective treatments. Preclinical studies indicate that hyperbaric oxygen (HBO) treatment within 12 h of AIS onset alleviates ischemia/reperfusion injuries, including hemorrhagic transformation. However, clinical trials have yielded conflicting results, suggesting some underlying mechanisms remain unclear. In this study, we confirmed that HBO treatments beginning within 1 h post reperfusion significantly alleviated the haemorrhage and neurological deficits in hyperglycemic transient middle cerebral arterial occlusion (tMCAO) mice, partly due to the inhibition of the NLRP3 inflammasome-mediated pro-inflammatory response in microglia. Notably, reactive oxygen species (ROS) mediate the anti-inflammatory and protective effect of early HBO treatment, as edaravone and N-Acetyl-L-Cysteine (NAC), two commonly used antioxidants, reversed the suppressive effect of HBO treatment on NLRP3 inflammasome-mediated inflammation in microglia. Furthermore, NAC countered the protective effect of early HBO treatment in tMCAO mice with hyperglycemia. These findings support that early HBO treatment is a promising intervention for AIS, however, caution is warranted when combining antioxidants with HBO treatment. Further assessments are needed to clarify the role of antioxidants in HBO therapy for AIS.

SMAC mimetic drives microglia phenotype and glioblastoma immune microenvironment.

Tumor-associated macrophages/microglia (TAMs) are highly plastic and heterogeneous immune cells that can be immune-supportive or tumor-supportive depending of the microenvironment. TAMs are the most abundant immune cells in glioblastoma (GB), and play a key role in immunosuppression. Therefore, TAMs reprogramming toward immune-supportive cells is a promising strategy to overcome immunosuppression. By leveraging scRNAseq human GB databases, we identified that Inhibitor of Apoptosis Proteins (IAP) were expressed by TAMs. To investigate their role in TAMs-related immunosuppression, we antagonized IAP using the central nervous system permeant SMAC mimetic GDC-0152 (SMg). On explants and cultured immune cells isolated from human GB samples, SMg modified TAMs activity. We showed that SMg treatment promoted microglia pro-apoptotic and anti-tumoral function via caspase-3 pro-inflammatory cleavage and the inhibition of tumoroids growth. Then we designed a relevant immunogenic mouse GB model to decipher the spatio-temporal densities, distribution, phenotypes and function of TAMs with or without SMg treatment. We used 3D imaging techniques, a transgenic mouse with fluorescent TAM subsets and mass cytometry. We confirmed that SMg promoted microglia activation, antigen-presenting function and tumor infiltration. In addition, we observed a remodeling of blood vessels, a decrease in anti-inflammatory macrophages and an increased level of monocytes and their mo-DC progeny. This remodeling of the TAM landscape is associated with an increase in CD8 T cell density and activation. Altogether, these results demonstrated that SMg drives the immunosuppressive basal microglia toward an active phenotype with pro-apoptotic and anti-tumoral function and modifies the GB immune landscape. This identifies IAP as targets of choice for a potential mechanism-based therapeutic strategy and SMg as a promising molecule for this application.

Human NGF "Painless" Ocular Delivery for Retinitis Pigmentosa: An In Vivo Study.

Retinitis pigmentosa (RP) is a family of genetically heterogeneous diseases still without a cure. Despite the causative genetic mutation typically not expressed in cone photoreceptors, these cells inevitably degenerate following the primary death of rods, causing blindness. The reasons for the "bystander" degeneration of cones are presently unknown but decrement of survival factors, oxidative stress, and inflammation all play a role. Targeting these generalized biological processes represents a strategy to develop mutation-agnostic therapies for saving vision in large populations of RP individuals. A classical method to support neuronal survival is by employing neurotrophic factors, such as NGF. This study uses painless human NGF (hNGFp), a TrkA receptor-biased variant of the native molecule with lower affinity for nociceptors and limited activity as a pain inducer; the molecule has identical neurotrophic power of the native form but a reduced affinity for the p75NTR receptors, known to trigger apoptosis. hNGFp has a recognized activity on brain microglial cells, which are induced to a phenotype switch from a highly activated to a more homeostatic configuration. hNGFp was administered to RP-like mice in vivo with the aim of decreasing retinal inflammation and also providing retinal neuroprotection. However, the ability of this treatment to counteract the bystander degeneration of cones remained limited.

Small Molecule Decoy of Amyloid-ß Aggregation Blocks Activation of Microglia-Like Cells.

Background: Aggregated forms of the amyloid-ß (Aß) peptides which form protofibrils and fibrils in the brain are signatures of Alzheimer's disease (AD). Aggregates are also recognized by microglia, which in early phases may be protective and in later phases contribute to the pathology. We have identified several small molecules, decoys which interfere with Aß oligomerization and induce other aggregation trajectories leading to aggregated macrostructures which are non-toxic. Objective: This study investigates whether the small-molecule decoys affect microglial activation in terms of cytokine secretion and phagocytosis of Aß peptide. Methods: The effects of the decoys (NSC 69318, NSC 100873, NSC 16224) were analyzed in a model of human THP-1 monocytes differentiated to microglia-like cells. The cells were activated by Aß40 and Aß42 peptides, respectively, and after treatment with each decoy the secreted levels of pro-inflammatory cytokines and the Aß phagocytosis were analyzed. Results: NSC16224, which generates a double-stranded aggregate of thin protofibrils, was found to block Aß40- and Aß42-induced increase in microglial secretion of pro-inflammatory cytokines. NSC 69318, selective for neurotoxicity of Aß42, and NSC 100873 did not significantly reduce the microglial activation in terms of cytokine secretion. The uptake of Aß42 was not affected by anyone of the decoys. Conclusions: Our findings open the possibility that the molecular decoys of Aß aggregation may block microglial activation by Aß40 and Aß42 in addition to blocking neurotoxicity as shown previously.

Understanding the molecular pathway of triclosan-induced ADHD-like behaviour: Involvement of the hnRNPA1-PKM2-STAT3 feedback loop.

Triclosan (TCS) is an environmental pollutant. In recent years, there has been increasing level of concern regarding the potential toxicity of TCS in animals and humans, especially its effects on the nervous system. However, whether TCS induces ADHD-like behaviour and the mechanism by which it affects neural function are unclear. The impact of 60 days of continuous exposure to TCS on the behaviour of offspring rats was assessed in this research. According to the results of this study, TCS exposure led to ADHD-like behaviour in offspring rats and activated microglia in the prefrontal cortex (PFC), inducing inflammatory factor release. In vitro studies showed that TCS increased the levels of inflammatory cytokines, including interleukin (IL)-1ß, IL-6 and tumour necrosis factor (TNF)-α, in HMC3 cells. More importantly, we found that TCS regulated the STAT3 pathway by upregulating PKM2 via hnRNPA1. In summary, this study suggested that TCS can induce ADHD-like behaviour in offspring rats and continuously activate HMC3 microglia through the hnRNPA1-PKM2-STAT3 feedback loop, promoting inflammatory cytokine secretion.