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Toxins May 2024A major pathogenic factor is the cholesterol-dependent cytolysin pneumolysin, binding membrane cholesterol and producing permanent lytic or transient pores. During...
A major pathogenic factor is the cholesterol-dependent cytolysin pneumolysin, binding membrane cholesterol and producing permanent lytic or transient pores. During brain infections, vascular damage with variable ischemia occurs. The role of ischemia on pneumolysin's pore-forming capacity remains unknown. In acute brain slice cultures and primary cultured glia, we studied acute toxin lysis (via propidium iodide staining and LDH release) and transient pore formation (by analyzing increases in the intracellular calcium). We analyzed normal peripheral tissue glucose conditions (80 mg%), normal brain glucose levels (20 mg%), and brain hypoglycemic conditions (3 mg%), in combinations either with normoxia (8% oxygen) or hypoxia (2% oxygen). At 80 mg% glucose, hypoxia enhanced cytolysis via pneumolysin. At 20 mg% glucose, hypoxia did not affect cell lysis, but impaired calcium restoration after non-lytic pore formation. Only at 3 mg% glucose, during normoxia, did pneumolysin produce stronger lysis. In hypoglycemic (3 mg% glucose) conditions, pneumolysin caused a milder calcium increase, but restoration was missing. Microglia bound more pneumolysin than astrocytes and demonstrated generally stronger calcium elevation. Thus, our work demonstrated that the toxin pore-forming capacity in cells continuously diminishes when oxygen is reduced, overlapping with a continuously reduced ability of cells to maintain homeostasis of the calcium influx once oxygen and glucose are reduced.
Topics: Streptolysins; Glucose; Animals; Bacterial Proteins; Oxygen; Cholesterol; Streptococcus pneumoniae; Brain; Calcium; Cells, Cultured; Neuroglia
PubMed: 38922127
DOI: 10.3390/toxins16060232 -
β2-Integrins Regulate Microglial Responses and the Functional Outcome of Hemorrhagic Stroke In Vivo.Journal of Immunology (Baltimore, Md. :... Jun 2024Stroke is one of the leading causes of death and long-term disabilities worldwide. In addition to interruption of blood flow, inflammation is widely recognized as an...
Stroke is one of the leading causes of death and long-term disabilities worldwide. In addition to interruption of blood flow, inflammation is widely recognized as an important factor mediating tissue destruction in stroke. Depending on their phenotype, microglia, the main leukocytes in the CNS, are capable of either causing further tissue damage or promoting brain restoration after stroke. β2-integrins are cell adhesion molecules that are constitutively expressed on microglia. The function of β2-integrins has been investigated extensively in animal models of ischemic stroke, but their role in hemorrhagic stroke is currently poorly understood. We show in this study that dysfunction of β2-integrins is associated with improved functional outcome and decreased inflammatory cytokine expression in the brain in a mouse model of hemorrhagic stroke. Furthermore, β2-integrins affect microglial phenotype and cytokine responses in vivo. Therefore, our findings suggest that targeting β2-integrins in hemorrhagic stroke may be beneficial.
PubMed: 38921973
DOI: 10.4049/jimmunol.2300815 -
Marine Drugs May 2024Neurodegenerative diseases involve neuroinflammation and a loss of neurons, leading to disability and death. Hence, the research into new therapies has been focused on...
Neurodegenerative diseases involve neuroinflammation and a loss of neurons, leading to disability and death. Hence, the research into new therapies has been focused on the modulation of the inflammatory response mainly by microglia/macrophages. The extracts and metabolites of marine sponges have been presented as anti-inflammatory. This study evaluated the toxicity of an extract and purified compound from the Brazilian marine sponge as well as its neuroprotection against inflammatory damage associated with the modulation of microglia response. PC12 neuronal cells and neonatal rat microglia were treated with the methanolic extract of (AF-MeOH, 0.1-200 μg/mL) or with its purified dimethyl ketal of 3,5-dibromoverongiaquinol (AF-H1, 0.1-100 μM). Cytotoxicity was determined by MTT tetrazolium, Trypan blue, and propidium iodide; microglia were also treated with the conditioned medium (CM) from PC12 cells in different conditions. The microglia phenotype was determined by the expression of Iba-1 and CD68. AF-MeOH and AF-H1 were not toxic to PC12 or the microglia. Inflammatory damage with lipopolysaccharide (LPS, 5 μg/mL) was not observed in the PC12 cells treated with AF-MeOH (1-10 μg/mL) or AF-H1 (1-10 μM). Microglia subjected to the CM from PC12 cells treated with LPS and AF-MeOH or AF-H1 showed the control phenotype-like (multipolar, low-CD68), highlighting the anti-neuroinflammatory and neuroprotective effect of components of this marine sponge.
Topics: Animals; Microglia; Rats; Porifera; Neuroprotective Agents; PC12 Cells; Brazil; Anti-Inflammatory Agents; Hydrocarbons, Brominated; Inflammation
PubMed: 38921546
DOI: 10.3390/md22060235 -
Cells Jun 2024In the context of glaucoma, intraocular pressure (IOP) and age are recognized as the primary factors contributing to its onset and progression. However, significant...
In the context of glaucoma, intraocular pressure (IOP) and age are recognized as the primary factors contributing to its onset and progression. However, significant reductions in IOP fail to completely halt its advancement. An emerging body of literature highlights the role of neuroinflammation in glaucoma. This study aimed to explore Bromfenac's anti-inflammatory properties in mitigating neuroinflammation associated with glaucoma using an ischemia-reperfusion (IR) glaucoma model. Bromfenac's impact on microglia and astrocytes under pressure was assessed via Western blotting and an enzyme-linked immunosorbent assay. Immunohistochemical staining was used to evaluate glial activation and changes in inflammatory marker expression in the IR model. Bromfenac led to the downregulation of inflammatory markers, which were elevated in the conditions of elevated pressure, and necroptosis markers were downregulated in astrocytes. In the IR model, elevated levels of GFAP and Iba-1 indicated glial activation. Following Bromfenac administration, levels of iNOS, COX-2, and PGE2-R were reduced, suggesting a decrease in neuroinflammation. Furthermore, Bromfenac administration in the IR model resulted in the improved survival of retinal ganglion cells (RGCs) and preservation of retinal function, as demonstrated by immunohistochemical staining and electroretinography. In summary, Bromfenac proved effective in diminishing neuroinflammation and resulted in enhanced RGC survival.
Topics: Bromobenzenes; Animals; Benzophenones; Reperfusion Injury; Glaucoma; Disease Models, Animal; Astrocytes; Neuroinflammatory Diseases; Retinal Ganglion Cells; Microglia; Male; Intraocular Pressure; Rats
PubMed: 38920673
DOI: 10.3390/cells13121046 -
Cells Jun 2024Oligodendrocyte progenitor cells (OPCs) represent a subtype of glia, giving rise to oligodendrocytes, the myelin-forming cells in the central nervous system (CNS). While... (Review)
Review
Oligodendrocyte progenitor cells (OPCs) represent a subtype of glia, giving rise to oligodendrocytes, the myelin-forming cells in the central nervous system (CNS). While OPCs are highly proliferative during development, they become relatively quiescent during adulthood, when their fate is strictly influenced by the extracellular context. In traumatic injuries and chronic neurodegenerative conditions, including those of autoimmune origin, oligodendrocytes undergo apoptosis, and demyelination starts. Adult OPCs become immediately activated; they migrate at the lesion site and proliferate to replenish the damaged area, but their efficiency is hampered by the presence of a glial scar-a barrier mainly formed by reactive astrocytes, microglia and the deposition of inhibitory extracellular matrix components. If, on the one hand, a glial scar limits the lesion spreading, it also blocks tissue regeneration. Therapeutic strategies aimed at reducing astrocyte or microglia activation and shifting them toward a neuroprotective phenotype have been proposed, whereas the role of OPCs has been largely overlooked. In this review, we have considered the glial scar from the perspective of OPCs, analysing their behaviour when lesions originate and exploring the potential therapies aimed at sustaining OPCs to efficiently differentiate and promote remyelination.
Topics: Humans; Remyelination; Animals; Oligodendrocyte Precursor Cells; Cicatrix; Neuroglia; Oligodendroglia; Myelin Sheath; Cell Differentiation
PubMed: 38920654
DOI: 10.3390/cells13121024 -
Cells Jun 2024Multiple sclerosis (MS) is a clinically heterogeneous disease underpinned by inflammatory, demyelinating and neurodegenerative processes, the extent of which varies...
BACKGROUND
Multiple sclerosis (MS) is a clinically heterogeneous disease underpinned by inflammatory, demyelinating and neurodegenerative processes, the extent of which varies between individuals and over the course of the disease. Recognising the clinicopathological features that most strongly associate with disease outcomes will inform future efforts at patient phenotyping.
AIMS
We used a digital pathology workflow, involving high-resolution image acquisition of immunostained slides and opensource software for quantification, to investigate the relationship between clinical and neuropathological features in an autopsy cohort of progressive MS.
METHODS
Sequential sections of frontal, cingulate and occipital cortex, thalamus, brain stem (pons) and cerebellum including dentate nucleus (n = 35 progressive MS, females = 28, males = 7; age died = 53.5 years; range 38-98 years) were immunostained for myelin (anti-MOG), neurons (anti-HuC/D) and microglia/macrophages (anti-HLA). The extent of demyelination, neurodegeneration, the presence of active and/or chronic active lesions and quantification of brain and leptomeningeal inflammation was captured by digital pathology.
RESULTS
Digital analysis of tissue sections revealed the variable extent of pathology that characterises progressive MS. Microglia/macrophage activation, if found at a higher level in a single block, was typically elevated across all sampled blocks. Compartmentalised (perivascular/leptomeningeal) inflammation was associated with age-related measures of disease severity and an earlier death.
CONCLUSION
Digital pathology identified prognostically important clinicopathological correlations in MS. This methodology can be used to prioritise the principal pathological processes that need to be captured by future MS biomarkers.
Topics: Humans; Middle Aged; Female; Male; Multiple Sclerosis; Aged; Adult; Biomarkers; Aged, 80 and over; Inflammation; Brain; Microglia; Macrophages
PubMed: 38920650
DOI: 10.3390/cells13121020 -
Cells Jun 2024Microglia activity can drive excessive synaptic loss during the prodromal phase of Alzheimer's disease (AD) and is associated with lowered cyclic adenosine monophosphate...
Microglia activity can drive excessive synaptic loss during the prodromal phase of Alzheimer's disease (AD) and is associated with lowered cyclic adenosine monophosphate (cAMP) due to cAMP phosphodiesterase 4B (PDE4B). This study aimed to investigate whether long-term inhibition of PDE4B by A33 (3 mg/kg/day) can prevent synapse loss and its associated cognitive decline in APPswe/PS1dE9 mice. This model is characterized by a chimeric mouse/human APP with the Swedish mutation and human PSEN1 lacking exon 9 (dE9), both under the control of the mouse prion protein promoter. The effects on cognitive function of prolonged A33 treatment from 20 days to 4 months of age, was assessed at 7-8 months. PDE4B inhibition significantly improved both the working and spatial memory of APPswe/PSdE9 mice after treatment ended. At the cellular level, in vitro inhibition of PDE4B induced microglial filopodia formation, suggesting that regulation of PDE4B activity can counteract microglia activation. Further research is needed to investigate if this could prevent microglia from adopting their 'disease-associated microglia (DAM)' phenotype in vivo. These findings support the possibility that PDE4B is a potential target in combating AD pathology and that early intervention using A33 may be a promising treatment strategy for AD.
Topics: Animals; Cyclic Nucleotide Phosphodiesterases, Type 4; Mice; Mice, Transgenic; Alzheimer Disease; Cognition; Phosphodiesterase 4 Inhibitors; Microglia; Disease Models, Animal; Presenilin-1; Humans; Amyloid beta-Protein Precursor; Male
PubMed: 38920631
DOI: 10.3390/cells13121000 -
Cells Jun 2024Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron degeneration in the central nervous system. Recent research has...
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron degeneration in the central nervous system. Recent research has increasingly linked the activation of nucleotide oligomerization domain-like receptor protein 3 (NLRP3) inflammasome to ALS pathogenesis. NLRP3 activation triggers Caspase 1 (CASP 1) auto-activation, leading to the cleavage of Gasdermin D (GSDMD) and pore formation on the cellular membrane. This process facilitates cytokine secretion and ultimately results in pyroptotic cell death, highlighting the complex interplay of inflammation and neurodegeneration in ALS. This study aimed to characterize the NLRP3 inflammasome components and their colocalization with cellular markers using the wobbler mouse as an ALS animal model. Firstly, we checked the levels of miR-223-3p because of its association with NLRP3 inflammasome activity. The wobbler mice showed an increased expression of miR-223-3p in the ventral horn, spinal cord, and cerebellum tissues. Next, increased levels of NLRP3, pro-CASP 1, cleaved CASP 1 (c-CASP 1), full-length GSDMD, and cleaved GDSMD revealed NLRP3 inflammasome activation in wobbler spinal cords, but not in the cerebellum. Furthermore, we investigated the colocalization of the aforementioned proteins with neurons, microglia, and astrocyte markers in the spinal cord tissue. Evidently, the wobbler mice displayed microgliosis, astrogliosis, and motor neuron degeneration in this tissue. Additionally, we showed the upregulation of protein levels and the colocalization of NLRP3, c-CASP1, and GSDMD in neurons, as well as in microglia and astrocytes. Overall, this study demonstrated the involvement of NLRP3 inflammasome activation and pyroptotic cell death in the spinal cord tissue of wobbler mice, which could further exacerbate the motor neuron degeneration and neuroinflammation in this ALS mouse model.
Topics: Animals; Amyotrophic Lateral Sclerosis; NLR Family, Pyrin Domain-Containing 3 Protein; Motor Neurons; Inflammasomes; Mice; MicroRNAs; Spinal Cord; Disease Models, Animal; Nerve Degeneration; Microglia; Mice, Inbred C57BL; Caspase 1
PubMed: 38920626
DOI: 10.3390/cells13120995 -
Frontiers in Immunology 2024
Topics: Spinal Cord Injuries; Humans; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Animals
PubMed: 38919627
DOI: 10.3389/fimmu.2024.1354118 -
Journal of Neurophysiology Jun 2024Alpha-synuclein (α-syn) is a major component of lewy bodies, which is biomarker of Parkinson's disease (PD). It accumulates in substantia nigra pars compacts (SNpc) to...
OBJECTIVE
Alpha-synuclein (α-syn) is a major component of lewy bodies, which is biomarker of Parkinson's disease (PD). It accumulates in substantia nigra pars compacts (SNpc) to form insoluble aggregates and cause neurotoxicity, which is often accompanied by iron deposition.
METHOD
We compared the iron reductase activity between monomeric α-syn (M-α-syn) and oligomeric α-syn (O-α-syn), investigated the effect of α-syn on iron metabolism of BV2 microglia cells as well.
RESULTS
α-syn had ferric reductase activity, and O-α-syn had stronger enzyme activity than M-α-syn. M-α-syn upregulated iron uptake protein, divalent metal transporter1 (DMT1) expression and iron influx, but did not regulate iron release protein, ferroportin1 (FPN1) expression and iron efflux. O-α-syn elevated the expression of both DMT1 and FPN1, thus increased the iron influx and efflux in BV2 microglial cells, but the expressions of iron regulatory protein1 (IRP1) and hypoxia inducible factor2α (HIF-2α) had no significant change. Moreover, both M-α-syn and O-α-syn could increase the mRNA expressions of TNF-α and IL-1β in BV2 microglia cells.
CONCLUSION
Both types of α-syn can activate microglia, which leads to increased expressions of pro-inflammatory factors. α-syn can affect DMT1 and FPN1 expressions in BV2 microglia cells, which might be through its ferric reductase activity.
PubMed: 38919150
DOI: 10.1152/jn.00106.2024