A co-ultramicronized palmitoylethanolamide/luteolin composite mitigates clinical score and disease-relevant molecular markers in a mouse model of experimental autoimmune encephalomyelitis.

BACKGROUND: Persistent and/or recurrent inflammatory processes are the main factor leading to multiple sclerosis (MS) lesions. The composite ultramicronized palmitoylethanolamide, an endogenous N-acylethanolamine, combined with the flavonoid luteolin, PEALut, have been found to exert neuroprotective activities in experimental models of spinal and brain injury and Alzheimer disease, as well as a clinical improvement in human stroke patients. Furthermore, PEALut enhances the expression of different myelin proteins in oligodendrocyte progenitor cells suggesting that this composite might have protective effects in MS experimental models. METHODS: The mouse model of experimental autoimmune encephalomyelitis (EAE) based on active immunization with a fragment of myelin oligodendrocyte glycoprotein (MOG35-55) was used. The daily assessment of clinical score and the expression of serum amyloid A (SAA1), proinflammatory cytokines TNF-α, IL-1ß, IFN-γ, and NLRP3 inflammasome, as well as TLR2, Fpr2, CD137, CD3-γ, and TCR-ζ chain, heterodimers that form T cell surface glycoprotein (TCR), and cannabinoid receptors CB1, CB2, and MBP, were evaluated in the brainstem and cerebellum at different postimmunization days (PIDs). RESULTS: Vehicle-MOG35-55-immunized (MOG35-55) mice developed ascending paralysis which peaked several days later and persisted until the end of the experiment. PEALut, given intraperitoneally daily starting on day 11 post-immunization, dose-dependently improved clinical score over the range 0.1-5 mg/kg. The mRNA expression of SAA1, TNF-α, IL-1ß, IFN-γ, and NLRP3 were significantly increased in MOG35-55 mice at 14 PID. In MOG35-55 mice treated with 5 mg /kg PEALut, the increase of SAA1, TNF- α, IL-1ß, and IFN-γ transcripts at 14 PID was statistically downregulated as compared to vehicle-MOG35-55 mice (p < 0.05). The expression of TLR2, Fpr2, CD137, CD3-γ, TCR-ζ chain, and CB2 receptors showed a significant upregulation in vehicle-MOG35-55 mice at 14 PID. Instead, CB1 and MBP transcripts have not changed in expression at any time. In MOG/PEALut-treated mice, TLR2, Fpr2, CD137, CD3-γ, TCR-ζ chain, and CB2 mRNAs were significantly downregulated as compared to vehicle MOG35-55 mice. CONCLUSIONS: The present results demonstrate that the intraperitoneal administration of the composite PEALut significantly reduces the development of clinical signs in the MOG35-55 model of EAE. The dose-dependent improvement of clinical score induced by PEALut was associated with a reduction in transcript expression of the acute-phase protein SAA1, TNF-α, IL-1ß, IFN-γ, and NLRP3 proinflammatory proteins and TLR2, Fpr2, CD137, CD3-γ, TCR-ζ chain, and CB2 receptors.

Serum amyloid A primes microglia for ATP-dependent interleukin-1ß release.

BACKGROUND: Acute-phase response is a systemic reaction to environmental/inflammatory insults and involves production of acute-phase proteins, including serum amyloid A (SAA). Interleukin-1ß (IL-1ß), a master regulator of neuroinflammation produced by activated inflammatory cells of the myeloid lineage, in particular microglia, plays a key role in the pathogenesis of acute and chronic diseases of the peripheral nervous system and CNS. IL-1ß release is promoted by ATP acting at the purinergic P2X7 receptor (P2X7R) in cells primed with toll-like receptor (TLR) ligands. METHODS: Purified (> 99%) microglia cultured from neonatal rat cortex and cerebellum were first primed with the putative TLR4/TLR2 agonist SAA (recombinant human Apo-SAA) or the established TLR4 agonist lipopolysaccharide (LPS) followed by addition of ATP. Expression of genes for the NLRP3 inflammasome, IL-1ß, tumor necrosis factor-α (TNF-α), and SAA1 was measured by quantitative real-time polymerase chain reaction (q-PCR). Intracellular and extracellular amounts of IL-1ß were determined by ELISA. RESULTS: Apo-SAA stimulated, in a time-dependent manner, the expression of NLRP3, IL-1ß, and TNF-α in cortical microglia, and produced a concentration-dependent increase in the intracellular content of IL-1ß in these cells. A 2-h 'priming' of the microglia with Apo-SAA followed by addition of ATP for 1 h, resulting in a robust release of IL-1ß into the culture medium, with a concomitant reduction in its intracellular content. The selective P2X7R antagonist A740003 blocked ATP-dependent release of IL-1ß. Microglia prepared from rat cerebellum displayed similar behaviors. As with LPS, Apo-SAA upregulated SAA1 and TLR2 mRNA, and downregulated that of TLR4. LPS was less efficacious than Apo-SAA, perhaps reflecting an action of the latter at TLR4 and TLR2. The TLR4 antagonist CLI-095 fully blocked the action of LPS, but only partially that of Apo-SAA. Although the TLR2 antagonist CU-CPT22 was inactive against Apo-SAA, it also failed to block the TLR2 agonist Pam3CSK4. CONCLUSIONS: Microglia are central to the inflammatory process and a major source of IL-1ß when activated. P2X7R-triggered IL-1ß maturation and export is thus likely to represent an important contributor to this cytokine pool. Given that SAA is detected in Alzheimer disease and multiple sclerosis brain, together with IL-1ß-immunopositive microglia, these findings propose a link between P2X7R, SAA, and IL-1ß in CNS pathophysiology.

Bisdemethoxycurcumin and Its Cyclized Pyrazole Analogue Differentially Disrupt Lipopolysaccharide Signalling in Human Monocyte-Derived Macrophages.

Several studies suggest that curcumin and related compounds possess antioxidant and anti-inflammatory properties including modulation of lipopolysaccharide- (LPS-) mediated signalling in macrophage cell models. We here investigated the effects of curcumin and the two structurally unrelated analogues GG6 and GG9 in primary human blood-derived macrophages as well as the signalling pathways involved. Macrophages differentiated from peripheral blood monocytes for 7 days were activated with LPS or selective Toll-like receptor agonists for 24 h. The effects of test compounds on cytokine production and immunophenotypes evaluated as CD80+/CCR2+ and CD206+/CD163+ subsets were examined by ELISA and flow cytometry. Signalling pathways were probed by Western blot. Curcumin (2.5-10 µM) failed to suppress LPS-induced inflammatory responses. While GG6 reduced LPS-induced IκB-α degradation and showed a trend towards reduced interleukin-1ß release, GG9 prevented the increase in proinflammatory CD80+ macrophage subset, downregulation of the anti-inflammatory CD206+/CD163+ subset, increase in p38 phosphorylation, and increase in cell-bound and secreted interleukin-1ß stimulated by LPS, at least in part through signalling pathways not involving Toll-like receptor 4 and nuclear factor-κB. Thus, the curcumin analogue GG9 attenuated the LPS-induced inflammatory response in human blood-derived macrophages and may therefore represent an attractive chemical template for macrophage pharmacological targeting.

An intracellular adrenomedullin system reduces IL-6 release via a NF-kB-mediated, cAMP-independent transcriptional mechanism in rat thymic epithelial cells.

Thymic epithelial cells (TECs) play a key role in the regulation of central immune tolerance by expressing autoantigens and eliminating self-reactive T cells. In a previous paper we reported that adrenomedullin (ADM) and its co-receptor protein RAMP2 are located intracellularly in newborn human thymic epithelial cells (TECs). This work has two main aims: (1) to examine the cellular localization of ADM and its receptor in TECs of adult Wistar rats to validate this animal model for the study of the ADM system and its function(s) in thymus; (2) to investigate the potential modulating effect of ADM on the NF-kB pathway, which is involved through the production of cytokines such as IL-6, in the maturation of T-lymphocytes and immunological tolerance. Our results show that, similarly to human newborn TECs, ADM is localized to the cytoplasm of adult rat TECs, and RAMP2 is expressed in the nucleus but not in the plasma membrane. Pretreatment of TECs for 4h with ADM significantly reduced lipopolysaccharide (LPS)-induced release of IL-6 (P<0.001) and expression of the p65 subunit of NF-kB, while doubled the expression of IkBα (P<0.001), the physiological inhibitor of NF-kB nuclear translocation. These effects were not mediated by activation of the cAMP pathway, a signalling cascade that is rapidly activated by ADM in cells that express plasma membrane RAMP2, but were the consequence of a reduction in the transcription of p65 (P<0.001) and an increase in the transcription of IkBα (P<0.05). On the basis of these findings we propose that in rat TECs ADM reduces IL-6 secretion by modulating NF-kB genes transcription through an interaction with a receptor localized to the nucleus. This may partly explain the protective effects of ADM in autoimmune diseases and points to the ADM system of TECs as a novel potential target for immunomodulating drugs.

Ligand engagement of Toll-like receptors regulates their expression in cortical microglia and astrocytes.

BACKGROUND: Toll-like receptor (TLR) activation on microglia and astrocytes are key elements in neuroinflammation which accompanies a number of neurological disorders. While TLR activation on glia is well-established to up-regulate pro-inflammatory mediator expression, much less is known about how ligand engagement of one TLR may affect expression of other TLRs on microglia and astrocytes. METHODS: In the present study, we evaluated the effects of agonists for TLR2 (zymosan), TLR3 (polyinosinic-polycytidylic acid (poly(I:C)), a synthetic analogue of double-stranded RNA) and TLR4 (lipopolysaccaride (LPS)) in influencing expression of their cognate receptor as well as that of the other TLRs in cultures of rat cortical purified microglia (>99.5 %) and nominally microglia-free astrocytes. Elimination of residual microglia (a common contaminant of astrocyte cultures) was achieved by incubation with the lysosomotropic agent L-leucyl-L-leucine methyl ester (L-LME). RESULTS: Flow cytometric analysis confirmed the purity (essentially 100 %) of the obtained microglia, and up to 5 % microglia contamination of astrocytes. L-LME treatment effectively removed microglia from the latter (real-time polymerase chain reaction). The three TLR ligands robustly up-regulated gene expression for pro-inflammatory markers (interleukin-1 and interleukin-6, tumor necrosis factor) in microglia and enriched, but not purified, astrocytes, confirming cellular functionality. LPS, zymosan and poly(I:C) all down-regulated TLR4 messenger RNA (mRNA) and up-regulated TLR2 mRNA at 6 and 24 h. In spite of their inability to elaborate pro-inflammatory mediator output, the nominally microglia-free astrocytes (>99 % purity) also showed similar behaviours to those of microglia, as well as changes in TLR3 gene expression. LPS interaction with TLR4 activates downstream mitogen-activated protein kinase and nuclear factor-κB signalling pathways and subsequently causes inflammatory mediator production. The effects of LPS on TLR2 mRNA in both cell populations were antagonized by a nuclear factor-κB inhibitor. CONCLUSIONS: TLR2 and TLR4 activation in particular, in concert with microglia and astrocytes, comprise key elements in the initiation and maintenance of neuropathic pain. The finding that both homologous (zymosan) and heterologous (LPS, poly(I:C)) TLR ligands are capable of regulating TLR2 gene expression, in particular, may have important implications in understanding the relative contributions of different TLRs in neurological disorders associated with neuroinflammation.

Reply to: "Palmitoylethanolamide: problems regarding micronization, ultra-micronization and additives" Inflammopharmacology DOI:10.1007/s10787-014-0202-3.

This is a reply to a recently published Commentary: "Palmitoylethanolamide: problems regarding micronization, ultra-micronization and additives" Inflammopharmacology DOI: 10.1007/s10787-014-0202-3 , written in relation to our review article: Skaper SD, Facci L, Fusco M, della Valle MF, Zusso M, Costa B, Giusti P (2014) "Palmitoylethanolamide, a naturally occurring disease-modifying agent in neuropathic pain" Inflammopharmacology 22:79-94 DOI: 10.1007/s10787-013-0191-7 . We believe that the Commentary by Kriek contains a number of erroneous statements and misinterpretations of the published scientific/medical literature which our reply shall elaborate on. Further, the writer of the Commentary has a direct connection to a company, JP Russell Science Ltd that sells palmitoylethanolamide. The take-home message of our review remains as originally stated: "Collectively, the findings presented here propose that palmitoylethanolamide merits further consideration as a disease-modifying agent for controlling inflammatory responses and related chronic and neuropathic pain".

Mast cells, glia and neuroinflammation: partners in crime?

Glia and microglia in particular elaborate pro-inflammatory molecules that play key roles in central nervous system (CNS) disorders from neuropathic pain and epilepsy to neurodegenerative diseases. Microglia respond also to pro-inflammatory signals released from other non-neuronal cells, mainly those of immune origin such as mast cells. The latter are found in most tissues, are CNS resident, and traverse the blood-spinal cord and blood-brain barriers when barrier compromise results from CNS pathology. Growing evidence of mast cell-glia communication opens new perspectives for the development of therapies targeting neuroinflammation by differentially modulating activation of non-neuronal cells that normally control neuronal sensitization - both peripherally and centrally. Mast cells and glia possess endogenous homeostatic mechanisms/molecules that can be up-regulated as a result of tissue damage or stimulation of inflammatory responses. Such molecules include the N-acylethanolamine family. One such member, N-palmitoylethanolamine is proposed to have a key role in maintenance of cellular homeostasis in the face of external stressors provoking, for example, inflammation. N-Palmitoylethanolamine has proven efficacious in mast-cell-mediated experimental models of acute and neurogenic inflammation. This review will provide an overview of recent progress relating to the pathobiology of neuroinflammation, the role of microglia, neuroimmune interactions involving mast cells and the possibility that mast cell-microglia cross-talk contributes to the exacerbation of acute symptoms of chronic neurodegenerative disease and accelerates disease progression, as well as promoting pain transmission pathways. We will conclude by considering the therapeutic potential of treating systemic inflammation or blockade of signalling pathways from the periphery to the brain in such settings.

Palmitoylethanolamide, a naturally occurring disease-modifying agent in neuropathic pain.

Persistent pain affects nearly half of all people seeking medical care in the US alone, and accounts for at least $80 billion worth of lost productivity each year. Among all types of chronic pain, neuropathic pain stands out: this is pain resulting from damage or disease of the somatosensory nervous system, and remains largely untreatable. With few available treatment options, neuropathic pain represents an area of significant and growing unmet medical need. Current treatment of peripheral neuropathic pain involves several drug classes, including opioids, gabapentinoids, antidepressants, antiepileptic drugs, local anesthetics and capsaicin. Even so, less than half of patients achieve partial relief. This review discusses a novel approach to neuropathic pain management, based on knowledge of: the role of glia and mast cells in pain and neuroinflammation; the body's innate mechanisms to maintain cellular homeostasis when faced with external stressors provoking, for example, inflammation. The discovery that palmitoylethanolamide, a member of the N-acylethanolamine family which is produced from the lipid bilayer on-demand, is capable of exerting anti-allodynic and anti-hyperalgesic effects by down-modulating both microglial and mast cell activity has led to the application of this fatty acid amide in several clinical studies of neuropathic pain, with beneficial outcome and no indication of adverse effects at pharmacological doses. Collectively, the findings presented here propose that palmitoylethanolamide merits further consideration as a disease-modifying agent for controlling inflammatory responses and related chronic and neuropathic pain.

Microglia and mast cells: two tracks on the road to neuroinflammation.

One of the more important recent advances in neuroscience research is the understanding that there is extensive communication between the immune system and the central nervous system (CNS). Proinflammatory cytokines play a key role in this communication. The emerging realization is that glia and microglia, in particular, (which are the brain's resident macrophages), constitute an important source of inflammatory mediators and may have fundamental roles in CNS disorders from neuropathic pain and epilepsy to neurodegenerative diseases. Microglia respond also to proinflammatory signals released from other non-neuronal cells, principally those of immune origin. Mast cells are of particular relevance in this context. These immunity-related cells, while resident in the CNS, are capable of migrating across the blood-spinal cord and blood-brain barriers in situations where the barrier is compromised as a result of CNS pathology. Emerging evidence suggests the possibility of mast cell-glia communications and opens exciting new perspectives for designing therapies to target neuroinflammation by differentially modulating the activation of non-neuronal cells normally controlling neuronal sensitization, both peripherally and centrally. This review aims to provide an overview of recent progress relating to the pathobiology of neuroinflammation, the role of microglia, neuroimmune interactions involving mast cells, in particular, and the possibility that mast cell-microglia crosstalk may contribute to the exacerbation of acute symptoms of chronic neurodegenerative disease and accelerate disease progression, as well as promote pain transmission pathways. We conclude by considering the therapeutic potential of treating systemic inflammation or blockade of signaling pathways from the periphery to the brain in such settings.

Intracellular ion channel CLIC1: involvement in microglia-mediated ß-amyloid peptide(1-42) neurotoxicity.

Microglia can exacerbate central nervous system disorders, including stroke and chronic progressive neurodegenerative diseases such as Alzheimer disease. Mounting evidence points to ion channels expressed by microglia as contributing to these neuropathologies. The Chloride Intracellular Channel (CLIC) family represents a class of chloride intracellular channel proteins, most of which are localized to intracellular membranes. CLICs are unusual in that they possess both soluble and integral membrane forms. Amyloid ß-peptide (Aß) accumulation in plaques is a hallmark of familial Alzheimer disease. The truncated Aß25-35 species was shown previously to increase the expression of CLIC1 chloride conductance in cortical microglia and to provoke microglial neurotoxicity. However, the highly pathogenic and fibrillogenic full-length Aß1-42 species was not examined, nor was the potential role of CLIC1 in mediating microglial activation and neurotoxicity by other stimuli (e.g. ligands for the Toll-like receptors). In the present study, we utilized a two chamber Transwell™ cell culture system to allow separate treatment of microglia and neurons while examining the effect of pharmacological blockade of CLIC1 in protecting cortical neurons from toxicity caused by Aß1-42- and lipopolysaccaride-stimulated microglia. Presentation of Aß1-42 to the upper, microglia-containing chamber resulted in a progressive loss of neurons over 3 days. Neuronal cell injury was prevented by the CLIC1 ion channel blockers IAA-94 [(R(+)-[(6,7-dichloro-2-cyclopentyl-2,3-dihydro-2-methyl-1-oxo-1H-inden-5yl)-oxy] acetic acid)] and niflumic acid (2-{[3-(trifluoromethyl)phenyl]amino}nicotinic acid) when presented to the upper chamber only. Incubation of microglia with lipopolysaccharide plus interferon-γ led to neuronal cell injury which, however, was insensitive to inhibition by the CLIC1 channel blockers, suggesting a degree of selectivity in agents leading to CLIC1 activation.

2-Pentadecyl-2-oxazoline inhibits lipopolysaccharide-induced microglia activation interfering with TLR4 signaling.

AIM: 2-Pentadecyl-2-oxazoline (PEA-OXA), the oxazoline derivative of N-palmitoylethanolamine, exerts anti-inflammatory activity; however, very little is known about the molecular mechanisms underlying this effect. Here, we tested the anti-neuroinflammatory effect of PEA-OXA in primary microglia and we also investigated the possible interaction of the molecule with the Toll-like receptor 4 (TLR4)-myeloid differentiation protein-2 (MD-2) complex. MAIN METHODS: The anti-inflammatory effect of PEA-OXA was analyzed by measuring the expression and release of pro-inflammatory mediators in primary microglia by real-time PCR and ELISA, respectively. The effect of PEA-OXA on the activation of TLR4 signaling was assessed using two stably TLR4-transfected cell lines (i.e., HEK-293 and Ba/F3 cells). Finally, the putative binding mode of PEA-OXA to TLR4-MD-2 was investigated by molecular docking simulations. KEY FINDINGS: Treatment with PEA-OXA resulted in the following effects: (i) it down-regulated gene expression of several pro-inflammatory molecules and the secretion of pro-inflammatory cytokines in LPS stimulated microglia cells; (ii) it did not prevent microglia activation after stimulation with TLR2 ligands; (iii) it prevented TLR4/NF-κB activation triggered by LPS in HEK-Blue™ hTLR4 cells; and (iv) it interfered with the binding of LPS to TLR4-MD-2 complex. Furthermore, molecular docking studies suggested that PEA-OXA could bind MD-2 with a 1:3 (MD-2/PEA-OXA) stoichiometry. CONCLUSION: We show for the first time that the anti-neuroinflammatory effect of PEA-OXA involves its activity against TLR4 signaling, making this molecule a valuable tool for the development of new compounds directed to control neuroinflammation via inhibiting TLR4 signaling.

TASTPM mice expressing amyloid precursor protein and presenilin-1 mutant transgenes are sensitive to γ-secretase modulation and amyloid-ß42 lowering by GSM-10h.

BACKGROUND: Cleavage of the amyloid precursor protein (APP) by ß-site APP-cleaving enzyme and γ-secretase results in the generation of amyloid-ß (Aß) peptides that aggregate and deposit as senile plaques in brains of Alzheimer disease patients. Due to the fundamental role γ-secretase plays in the proteolysis of a number of proteins including Notch, pharmacological inhibition of γ-secretase has been associated with mechanism-based toxicities. Therefore, efforts have focussed on the modulation of γ-secretase activity to selectively decrease levels of Aß42 peptide while avoiding deleterious activity on Notch processing. OBJECTIVE: Here, we describe the in vitro and in vivo characterisation of a novel γ-secretase modulator, GSM-10h, and investigate the potential for shorter Aß peptides to induce neurotoxicity in rat primary cortical neurons. METHODS: The effect of GSM-10h on Aß levels was investigated in SH-SY5Y cells expressing mutant APP and in TASTPM mice expressing APP and presenilin-1 mutant transgenes. The effect of GSM-10h on Notch processing was also determined. RESULTS: In cells, GSM-10h decreased levels of Aß42 while concomitantly increasing levels of Aß38 in the absence of effects on Aß40 levels. In TASTPM mice, GSM-10h effectively lowered brain Aß42 and increased brain Aß38, with no effect on Notch signalling. Unlike Aß42, which causes neuronal cell death, neither Aß37 nor Aß38 were neurotoxic. CONCLUSIONS: These findings confirm GSM-10h exhibits the profile of a γ-secretase modulator. In addition, TASTPM mice are shown to be responsive to treatment with a γ-secretase modulator, thereby highlighting the utility of this bitransgenic mouse model in drug discovery efforts focussed on the development of γ-secretase modulators.

Co-Ultramicronized Palmitoylethanolamide/Luteolin-Induced Oligodendrocyte Precursor Cell Differentiation is Associated With Tyro3 Receptor Upregulation.

Remyelination in patients with multiple sclerosis frequently fails, especially in the chronic phase of the disease promoting axonal and neuronal degeneration and progressive disease disability. Drug-based therapies able to promote endogenous remyelination capability of oligodendrocytes are thus emerging as primary approaches to multiple sclerosis. We have recently reported that the co-ultramicronized composite of palmitoylethanolamide and the flavonoid luteolin (PEALut) promotes oligodendrocyte precursor cell (OPC) maturation without affecting proliferation. Since TAM receptor signaling has been reported to be important modulator of oligodendrocyte survival, we here evaluated the eventual involvement of TAM receptors in PEALut-induced OPC maturation. The mRNAs related to TAM receptors -Tyro3, Axl, and Mertk- were all present at day 2 in vitro. However, while Tyro3 gene expression significantly increased upon cell differentiation, Axl and Mertk did not change during the first week in vitro. Tyro3 gene expression developmental pattern resembled that of MBP myelin protein. In OPCs treated with PEALut the developmental increase of Tyro3 mRNA was significantly higher as compared to vehicle while was reduced gene expression related to Axl and Mertk. Rapamycin, an inhibitor of mTOR, prevented oligodendrocyte growth differentiation and myelination. PEALut, administered to the cultures 30 min after rapamycin, prevented the alteration of mRNA basal expression of the TAM receptors as well as the expression of myelin proteins MBP and CNPase. Altogether, data obtained confirm that PEALut promotes oligodendrocyte differentiation as shown by the increase of MBP and CNPase and Tyro3 mRNAs as well as CNPase and Tyro3 immunostainings. The finding that these effects are reduced when OPCs are exposed to rapamycin suggests an involvement of mTOR signaling in PEALut effects.

Pre- and Early Post-treatment With Arthrospira platensis (Spirulina) Extract Impedes Lipopolysaccharide-triggered Neuroinflammation in Microglia.

Background: Uncontrolled neuroinflammation and microglia activation lead to cellular and tissue damage contributing to neurodegenerative and neurological disorders. Spirulina (Arthrospira platensis (Nordstedt) Gomont, or Spirulina platensis), a blue-green microalga, which belongs to the class of cyanobacteria, has been studied for its numerous health benefits, which include anti-inflammatory properties, among others. Furthermore, in vivo studies have highlighted neuroprotective effects of Spirulina from neuroinflammatory insults in different brain areas. However, the mechanisms underlying the anti-inflammatory effect of the microalga are not completely understood. In this study we examined the effect of pre- and post-treatment with an acetone extract of Spirulina (E1) in an in vitro model of LPS-induced microglia activation. Methods: The effect of E1 on the release of IL-1ß and TNF-α, expression of iNOS, nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1), and the activation of NF-κB was investigated in primary microglia by ELISA, real-time PCR, and immunofluorescence. Results: Pre- and early post-treatment with non-cytotoxic concentrations of E1 down-regulated the release of IL-1ß and TNF-α, and the over-expression of iNOS induced by LPS. E1 also significantly blocked the LPS-induced nuclear translocation of NF-κB p65 subunit, and upregulated gene and protein levels of Nrf2, as well as gene expression of HO-1. Conclusions: These results indicate that the extract of Spirulina can be useful in the control of microglia activation and neuroinflammatory processes. This evidence can support future in vivo studies to test pre- and post-treatment effects of the acetone extract from Spirulina.

Apoptosis-associated tyrosine kinase and neuronal cell death.

Apoptosis-associated tyrosine kinase (AATYK) is up-regulated by phosphorylation in cultured cerebellar granule neurons (CGN) undergoing apoptosis upon switch to low KCl-containing medium. However, the underlying signaling pathways remain to be fully characterized. When CGN at culture day 7 were switched from 25 mM KCl (K25) to 5 mM (K5) medium, AATYK band migration on SDS-PAGE shifted to a more slowly migrating position expected for the hyperphosphorylated protein. The apoptosis-inducing agent C(2)-ceramide also caused a mobility shift of the AATYK protein. Exposing CGN (K25) to L-type voltage-dependent Ca(2+) channel antagonists shifted the AATYK band to the K5-induced position, while the Ca(2+) channel activator FPL-64176 had the contrary effect. FK-506, a calcineurin inhibitor caused AATYK hyperphosphorylation under high KCl conditions. CGN death in K5 medium is linked to inhibition of the PI 3-kinase/Akt survival pathway and concomitant activation of the pro-apoptotic downstream target glycogen synthase kinase-3 (GSK-3). GSK-3 inhibitors blocked the K5-induced mobility shift of AATYK. Moreover, CGN cultured from AATYK-deficient mice remained sensitive to death in K5 medium. Thus, AATYK activation may not be a physiologically relevant principal regulatory target of the GSK-3 death pathway in KCl-deprived CGN.

Oligodendrocytes are a novel source of amyloid peptide generation.

Alzheimer's disease is characterised by regional neuronal degeneration, synaptic loss, and the progressive deposition of the 4 kDa ß-amyloid peptide (Aß) in senile plaques and accumulation of tau protein as neurofibrillary tangles. Aß derives from the larger precursor molecule, amyloid precursor protein (APP) by proteolytic processing via ß- and γ-secretases. While APP expression is well documented in neurons and astrocytes, the case for oligodendrocytes is less clear. The latter cell type is reported to express different isoforms of APP, and we have confirmed this observation by immunocytochemistry in cultures of differentiated rat cortical oligodendrocytes. Moreover, by means of a sensitive electrochemiluminescent immunoassay employing Aß C-terminal specific antibodies, mature oligodendrocytes are shown to secrete the 40 and 42 amino acid Aß species (Aß40 and Aß42). Secretion of Aß peptides was reduced by incubating oligodendrocytes with α- and ß-secretase inhibitors, or a γ-secretase inhibitor. Disturbances of APP processing and/ or synthesis in oligodendrocytes may account for some myelin disorders observed in Alzheimer's disease and other senile dementias.

Corrigendum: An Inflammation-Centric View of Neurological Disease: Beyond the Neuron.

[This corrects the article DOI: 10.3389/fncel.2018.00072.].

Abeta(1-42) reduces synapse number and inhibits neurite outgrowth in primary cortical and hippocampal neurons: a quantitative analysis.

Synaptic loss represents one of the earliest signs of neuronal damage and is observed within both Alzheimer's disease patients and transgenic mouse models of the disease. We have developed a novel in vitro assay using high content screening technology to measure changes in a number of cell physiological parameters simultaneously within a neuronal population. Using Hoechst-33342 to label nuclei, betaIII-tubulin as a neuron-specific marker, and synapsin-I as an indicator of pre-synaptic sites, we have designed software to interrogate triple-labelled images, counting only those synaptic puncta associated with tubulin-positive structures. Here we demonstrate that addition of amyloid beta peptide (Abeta(1-42)), to either primary hippocampal or cortical neurons for 4 days in vitro has deleterious effects upon synapse formation, neurite outgrowth and arborisation in a concentration-dependent manner. Control reverse peptide showed no effect over the same concentration range. The effects of Abeta(1-42) were inhibited by D-KLVFFA, which contains residues 16-20 of Abeta that function as a self-recognition element during Abeta assembly and bind to the homologous region of Abeta and block its oligomerisation. These effects of Abeta(1-42) on synapse number and neurite outgrowth are similar to those described within AD patient pathology and transgenic mouse models.

Culture of Rodent Cortical, Hippocampal, and Striatal Neurons.

Neurons cultured from rodent central nervous system tissues represent important tools in the study of neurodegenerative disease mechanisms and neuroregenerative processes, including the survival- and axon growth-promoting properties of neurotrophic factors. This chapter presents a detailed protocol for the preparation of rat and mouse cortical, hippocampal, and striatal neuron cell cultures, using either embryonic or postnatal tissue with enzymatic digestion.

Culture of Neonatal Rodent Microglia, Astrocytes, and Oligodendrocytes from the Cortex, Spinal Cord, and Cerebellum.

The protocol described in this chapter covers the preparation and culture of enriched populations of microglia, astrocytes, and oligodendrocytes from the cortex and spinal cord of neonatal rat and mouse. The procedure is based on enzymatic digestion of the tissue, followed by the culture of a mixed glial cell population which is then utilized as the starting point for the isolation, via differential attachment, of the different cell types.