Antineuroinflammatory effect of NF-kappaB essential modifier-binding domain peptides in the adoptive transfer model of experimental allergic encephalomyelitis

FcεRI/PLC axis promotes anandamide synthesis and the formation of CB2-GPR55 heteromers, modulating cytokine production in mast cells

Mast cells (MC) are crucial effectors in immediate allergic reactions. Monomeric IgE sensitizes MC and triggers various signaling responses. FcεRI/IgE/antigen crosslinking induces the release of several mediators, including bioactive lipids, but little is known about endocannabinoids (eCBs) secretion. Here, we studied the effects of IgE-induced sensitization and FcεRI crosslinking on anandamide (AEA) synthesis and release in bone marrow-derived mast cells (BMMC). Our results showed that mIgE induced AEA secretion through phospholipase C activation. Secreted AEA contributed to p38 phosphorylation induced by mIgE sensitization. Prolonged mIgE sensitization promoted the formation of long-lasting CB2-GPR55 heteromers. FcεRI crosslinking also caused AEA production. Notably, CB2 deficiency increased IL-2 and IL-3 cytokine expression in response to FcɛRI crosslinking. CB2 and GPR55 agonists reduced IL-2 and IL-3 mRNA expression caused by FcεRI activation. Our findings suggest that a) IgE binding to FcɛRI and its antigen-dependent activation leads to an AEA-dependent autocrine regulatory loop that contributes to intracellular signaling in MC and that b) CB2 and GPR55 receptors play a critical role in modulating the effector phase of MC activation by specifically regulating cytokine expression.

Build muscles and protect myelin

Multiple sclerosis (MS) is a chronic and debilitating autoimmune disease of the central nervous system (CNS) in which a CNS-driven immune response destroys myelin, leading to wide range of symptoms including numbness and tingling, vision problems, mobility impairment, etc. Oligodendrocytes are the myelinating cells in the CNS, which are generated from oligodendroglial progenitor cells (OPCs) via differentiation. However, for multiple reasons, OPCs fail to differentiate to oligodendrocytes in MS and as a result, stimulating the differentiation of OPCs to oligodendrocytes is considered beneficial for MS. The β-hydroxy β-methylbutyrate (HMB) is a widely-used muscle-building supplement in human and recently it has been shown that low-dose HMB is capable of stimulating the differentiation of cultured OPCs to oligodendrocytes for remyelination. Moreover, other causes of autoimmune demyelination are the decrease and/or suppression of Foxp3-expressing anti-autoimmune regulatory T cells (Tregs) and upregulation of autoimmune T-helper 1(Th1) and Th17 cells. Experimental autoimmune encephalomyelitis (EAE) is an animal model of MS in which the autoimmune demyelination is nicely visible. It has been reported that in EAE mice, oral HMB upregulates Tregs and decreases Th1 and Th17 responses, leading to remyelination in the CNS. Here, we analyze these newly-described features of HMB, highlighting the putative promyelinating nature of this supplement.

Muscle-building supplement β-hydroxy β-methylbutyrate stimulates the maturation of oligodendroglial progenitor cells to oligodendrocytes

Oligodendrocytes are the myelinating cells in the CNS and multiple sclerosis (MS) is a demyelinating disorder that is characterized by progressive loss of myelin. Although oligodendroglial progenitor cells (OPCs) should be differentiated into oligodendrocytes, for multiple reasons, OPCs fail to differentiate into oligodendrocytes in MS. Therefore, increasing the maturation of OPCs to oligodendrocytes may be of therapeutic benefit for MS. The β-hydroxy β-methylbutyrate (HMB) is a muscle-building supplement in humans and this study underlines the importance of HMB in stimulating the maturation of OPCs to oligodendrocytes. HMB treatment upregulated the expression of different maturation markers including PLP, MBP, and MOG in cultured OPCs. Double-label immunofluorescence followed by immunoblot analyses confirmed the upregulation of OPC maturation by HMB. While investigating mechanisms, we found that HMB increased the maturation of OPCs isolated from peroxisome proliferator-activated receptor β-/- (PPARβ-/-) mice, but not PPARα-/- mice. Similarly, GW6471 (an antagonist of PPARα), but not GSK0660 (an antagonist of PPARβ), inhibited HMB-induced maturation of OPCs. GW9662, a specific inhibitor of PPARγ, also could not inhibit HMB-mediated stimulation of OPC maturation. Furthermore, PPARα agonist GW7647, but neither PPARβ agonist GW0742 nor PPARγ agonist GW1929, alone increased the maturation of OPCs. Finally, HMB treatment of OPCs led to the recruitment of PPARα, but neither PPARβ nor PPARγ, to the PLP gene promoter. These results suggest that HMB stimulates the maturation of OPCs via PPARα and that HMB may have therapeutic prospects in remyelination.

Amelioration of experimental autoimmune encephalomyelitis by gemfibrozil in mice via PPARβ/δ: implications for multiple sclerosis

It is important to describe effective and non-toxic therapies for multiple sclerosis (MS), an autoimmune demyelinating disease. Experimental autoimmune encephalomyelitis (EAE) is an immune-mediated inflammatory disease that serves as a model for MS. Earlier we and others have shown that, gemfibrozil, a lipid-lowering drug, exhibits therapeutic efficacy in EAE. However, the underlying mechanism was poorly understood. Although gemfibrozil is a known ligand of peroxisome proliferator-activated receptor α (PPARα), here, we established that oral administration of gemfibrozil preserved the integrity of blood-brain barrier (BBB) and blood-spinal cord barrier (BSB), decreased the infiltration of mononuclear cells into the CNS and inhibited the disease process of EAE in both wild type and PPARα-/- mice. On the other hand, oral gemfibrozil was found ineffective in maintaining the integrity of BBB/BSB, suppressing inflammatory infiltration and reducing the disease process of EAE in mice lacking PPARβ (formerly PPARδ), indicating an important role of PPARβ/δ, but not PPARα, in gemfibrozil-mediated preservation of BBB/BSB and protection of EAE. Regulatory T cells (Tregs) play a critical role in the disease process of EAE/MS and we also demonstrated that oral gemfibrozil protected Tregs in WT and PPARα-/- EAE mice, but not PPARβ-/- EAE mice. Taken together, our findings suggest that gemfibrozil, a known ligand of PPARα, preserves the integrity of BBB/BSB, enriches Tregs, and inhibits the disease process of EAE via PPARβ, but not PPARα.

Induction of IL-2 by interleukin-12 p40 homodimer and IL-12, but not IL-23, in microglia and macrophages: Implications for multiple sclerosis

The level of IL-2 increases markedly in serum and central nervous system (CNS) of patients with multiple sclerosis (MS) and animals with experimental allergic encephalomyelitis (EAE). However, mechanisms by which IL-2 is induced under autoimmune demyelinating conditions are poorly understood. The present study underlines the importance of IL-12p40 homodimer (p402), the so-called biologically inactive molecule, in inducing the expression of IL-2 in mouse BV-2 microglial cells, primary mouse and human microglia, mouse peritoneal macrophages, RAW264.7 macrophages, and T cells. Interestingly, we found that p402 and IL-12p70 (IL-12), but not IL-23, dose-dependently induced the production of IL-2 and the expression of IL-2 mRNA in microglial cells. Similarly, p402 also induced the activation of IL-2 promoter in microglial cells and RAW264.7 cells. Among various stimuli tested, p402 was the most potent stimulus followed by IFN-γ, bacterial lipopolysaccharide, HIV-1 gp120, and IL-12 in inducing the activation of IL-2 promoter in microglial cells. Moreover, p402, but not IL-23, increased NFATc2 mRNA expression and the transcriptional activity of NFAT. Furthermore, induction of IL-2 mRNA expression by over-expression of p40, but not by p19, cDNA indicated that p40, but not p19, is responsible for the induction of IL-2 mRNA in microglia. Finally, by using primary microglia from IL to 12 receptor β1 deficient (IL-12Rβ1-/-) and IL-12 receptor β2 deficient (IL-12Rβ2-/-) mice, we demonstrate that p402 induces the expression of IL-2 via IL-12Rβ1, but not IL-12Rβ2. In experimental autoimmune encephalomyelitis, an animal model of MS, neutralization of p402 by mAb a3-1d led to decrease in clinical symptoms and reduction in IL-2 in T cells and microglia. These results delineate a new biological function of p402, which is missing in the so-called autoimmune cytokine IL-23, and raise the possibility of controlling increased IL-2 and the disease process of MS via neutralization of p402.

Suppression of Experimental Autoimmune Encephalomyelitis in Mice by β-Hydroxy β-Methylbutyrate, a Body-Building Supplement in Humans

Although several immunomodulatory drugs are available for multiple sclerosis (MS), most present significant side effects with long-term use. Therefore, delineation of nontoxic drugs for MS is an important area of research. β-Hydroxy β-methylbutyrate (HMB) is accessible in local GNC stores as a muscle-building supplement in humans. This study underlines the importance of HMB in suppressing clinical symptoms of experimental autoimmune encephalomyelitis (EAE) in mice, an animal model of MS. Dose-dependent study shows that oral HMB at a dose of 1 mg/kg body weight/d or higher significantly suppresses clinical symptoms of EAE in mice. Accordingly, orally administered HMB attenuated perivascular cuffing, preserved the integrity of the blood-brain barrier and blood-spinal cord barrier, inhibited inflammation, maintained the expression of myelin genes, and blocked demyelination in the spinal cord of EAE mice. From the immunomodulatory side, HMB protected regulatory T cells and suppressed Th1 and Th17 biasness. Using peroxisome proliferator-activated receptor (PPAR)α-/- and PPARβ-/- mice, we observed that HMB required PPARβ, but not PPARα, to exhibit immunomodulation and suppress EAE. Interestingly, HMB reduced the production of NO via PPARβ to protect regulatory T cells. These results describe a novel anti-autoimmune property of HMB that may be beneficial in the treatment of MS and other autoimmune disorders.

Cyclic Hypoxia Induces Transcriptomic Changes in Mast Cells Leading to a Hyperresponsive Phenotype after FcεRI Cross-Linking

Mast cells (MCs) play important roles in tumor development, executing pro- or antitumoral functions depending on tumor type and tumor microenvironment (TME) conditions. Cyclic hypoxia (cyH) is a common feature of TME since tumor blood vessels fail to provide a continuous supply of oxygen to the tumor mass. Here, we hypothesized that the localization of MCs in cyH regions within solid tumors could modify their transcriptional profile and activation parameters. Using confocal microscopy, we found an important number of MCs in cyH zones of murine melanoma B16-F1 tumors. Applying microarray analysis to examine the transcriptome of murine bone-marrow-derived MCs (BMMCs) exposed to interleaved cycles of hypoxia and re-oxygenation, we identified altered expression of 2512 genes. Functional enrichment analysis revealed that the transcriptional signature of MCs exposed to cyH is associated with oxidative phosphorylation and the FcεRI signaling pathway. Interestingly, FcεRI-dependent degranulation, calcium mobilization, and PLC-γ activity, as well as Tnf-α, Il-4, and Il-2 gene expression after IgE/antigen challenge were increased in BMMCs exposed to cyH compared with those maintained in normoxia. Taken together, our findings indicate that cyH causes an important phenotypic change in MCs that should be considered in the design of inflammation-targeted therapies to control tumor growth.

Glyceryl tribenzoate: A food additive with unique properties to be a substitute for cinnamon

Cinnamon is a regularly used natural seasoning and flavoring material throughout the world for eras. Recent laboratory studies have demonstrated that oral cinnamon may be beneficial for different neuroinflammatory and neurodegenerative disorders such as multiple sclerosis (MS), Parkinson's disease (PD), Alzheimer's disease (AD), and Lewy body diseases (LBD). However, cinnamon's certain limitations (e.g. unavailability of true Ceylon cinnamon throughout the world, impurities in ground cinnamon, etc.) have initiated an interest among researchers to find an alternate of cinnamon that can potentially deliver the same efficacy in the diseases mentioned above. Glyceryl tribenzoate (GTB) is a U.S. Food and Drug Administration (FDA)-approved flavoring ingredient that is used in food and food packaging industries. It has been found that similar to cinnamon, oral GTB is capable of upregulating regulatory T cells and suppressing the autoimmune disease process of experimental autoimmune encephalomyelitis, an animal model of MS. Moreover, both GTB and cinnamon metabolite sodium benzoate (NaB) have the potency to attenuate neurodegenerative pathology in a mouse model of Huntington disease (HD). Here, we have also demonstrated anti-inflammatory property of GTB in astrocytes and macrophages, a property that is also seen with cinnamon and its metabolite sodium benzoate (NaB). Therefore, here, we have made a sincere attempt to discuss the similarities and dissimilarities between cinnamon and GTB with a focus whether GTB has the potential to be considered as a substitute of cinnamon for neuroinflammatory and neurodegenerative disorders.

The many-sided contributions of NF-κB to T-cell biology in health and disease

T cells (or T lymphocytes) exhibit a myriad of functions in immune responses, ranging from pathogen clearance to autoimmunity, cancer and even non-lymphoid tissue homeostasis. Therefore, deciphering the molecular mechanisms orchestrating their specification, function and gene expression pattern is critical not only for our comprehension of fundamental biology, but also for the discovery of novel therapeutic targets. Among the master regulators of T-cell identity, the functions of the NF-κB family of transcription factors have been under scrutiny for several decades. However, a more precise understanding of their pleiotropic functions is only just emerging. In this review we will provide a global overview of the roles of NF-κB in the different flavors of mature T cells. We aim at highlighting the complex and sometimes diverging roles of the five NF-κB subunits in health and disease.

Dual functions of CNS inflammation in food intake and metabolic regulation

Western diet (WD) consumption induces chronic mild inflammation in the hypothalamus. However, metabolic consequences of increased hypothalamic inflammatory cytokines remain unclear. This research first aimed to examine whether increased proinflammatory cytokines in the brain influenced feeding or metabolism. Rats that received an intracerebroventricular third ventricle injection (i3vt) of 0.5 pg TNFα daily for six days consumed significantly more calories than saline-injected rats, with no differences between treatment groups in terms of body weight, blood triglycerides nor glucose regulation. Continuously infusing TNFα for three weeks decreased hepatic fatty acid synthase (FAS) and increased body weight and the epididymal adipose sterol regulatory element-binding protein 1c (SREBP-1c) gene expression. Differences were not due to food intake nor voluntary wheel running activity. The second aim of this research was to examine whether inhibition of inflammation signaling in the brain at early stage of switching from chow to WD would affect diet-induced obesity development. WD-fed rats with i3vt NFκB inhibitor had greater caloric intake than rats given i3vt saline. These studies suggest elevated inflammatory cytokines in the brain induce food intake acutely and favor fat storage and weight gain in the long term. However, in the early stage of WD consumption, hypothalamic inflammatory signaling inhibits caloric intake and may serve as a warning signal of energy imbalance.

Mutant Huntingtin affects toll-like receptor 4 intracellular trafficking and cytokine production in mast cells

BACKGROUND

Huntington's disease (HD) is caused by the expression of a mutated variant of Huntingtin (mHtt), which results in the complex pathology characterized by a defective function of the nervous system and altered inflammatory responses. While the neuronal effects of mHtt expression have been extensively studied, its effects on the physiology of immune cells have not been fully described. Mast cells (MCs) are unique tissue-resident immune cells whose activation has been linked to protective responses against parasites and bacteria, but also to deleterious inflammatory allergic reactions and, recently, to neurodegenerative diseases.

METHODS

Bone marrow-derived mast cells (BMMCs) were obtained from wild-type (WT-) and mHtt-expressing (R6/1) mice to evaluate the main activation parameters triggered by the high-affinity IgE receptor (FcεRI) and the Toll-like receptor (TLR) 4. Degranulation was assessed by measuring the secretion of β-hexosaminidase, MAP kinase activation was detected by Western blot, and cytokine production was determined by RT-PCR and ELISA. TLR-4 receptor and Htt vesicular trafficking was analyzed by confocal microscopy. In vivo, MC-deficient mice (c-KitWsh/Wsh) were intraperitonally reconstituted with WT or R6/1 BMMCs and the TLR4-induced production of the tumor necrosis factor (TNF) was determined by ELISA. A survival curve of mice treated with a sub-lethal dose of bacterial lipopolysaccharide (LPS) was constructed.

RESULTS

R6/1 BMMCs showed normal β-hexosaminidase release levels in response to FcεRI, but lower cytokine production upon LPS stimulus. Impaired TLR4-induced TNF production was associated to the lack of intracellular dynamin-dependent TLR-4 receptor trafficking to perinuclear regions in BMMCs, a diminished ERK1/2 and ELK-1 phosphorylation, and a decrease in c-fos and TNF mRNA accumulation. R6/1 BMMCs also failed to produce TLR4-induced anti-inflammatory cytokines (like IL-10 and TGF-β). The detected defects were also observed in vivo, in a MCs-dependent model of endotoxemia. R6/1 and c-KitWsh/Wsh mice reconstituted with R6/1 BMMCs showed a decreased TLR4-induced TNF production and lower survival rates to LPS challenge than WT mice.

CONCLUSIONS

Our data show that mHtt expression causes an impaired production of pro- and anti-inflammatory mediators triggered by TLR-4 receptor in MCs in vitro and in vivo, which could contribute to the aberrant immunophenotype observed in HD.

Nuclear Factor κB (NF-κB)-Mediated Inflammation in Multiple Sclerosis

The nuclear factor κB (NF-κB) signaling cascade has been implicating in a broad range of biological processes, including inflammation, cell proliferation, differentiation, and apoptosis. The past three decades have witnessed a great progress in understanding the impact of aberrant NF-κB regulation on human autoimmune and inflammatory disorders. In this review, we discuss how aberrant NF-κB activation contributes to multiple sclerosis, a typical inflammatory demyelinating disease of the central nervous system, and its involvement in developing potential therapeutic targets.

Upregulation of Suppressor of Cytokine Signaling 3 in Microglia by Cinnamic Acid

BACKGROUND

Neuroinflammation plays an important role in the pathogenesis of various neurodegenerative diseases including Alzheimer's disease (AD). Suppressor of cytokine signaling 3 (SOCS3) is an anti-inflammatory molecule that suppresses cytokine signaling and inflammatory gene expression in different cells including microglia.

OBJECTIVE

The pathways through which SOCS3 could be upregulated are poorly described. Cinnamic acid is a metabolite of cinnamon, a natural compound that is being widely used all over the world as a spice or flavoring agent. Here, we examined if cinnamic acid could upregulate SOCS3 in microglia.

METHOD

Microglia and astroglia isolated from mouse brain as well as BV-2 microglial cells were treated with cinnamic acid followed by monitoring the level of SOCS3 and different proinflammatory molecules by RT-PCR and real-time PCR. To nail down the mechanism, we also performed ChIP analysis to monitore the recruitment of cAMP response element binding (CREB) to the socs3 gene promoter and carried out siRNA knockdown of CREB.

RESULTS

Cinnamic acid upregulated the expression of SOCS3 mRNA and protein in mouse BV-2 microglial cells in dose- and time-dependent manner. Accordingly, cinnamic acid also increased the level of SOCS3 and suppressed the expression of inducible nitric oxide synthase and proinflammatory cytokines (TNFα, IL-1β and IL-6) in LPSstimulated BV-2 microglial cells. Similar to BV-2 microglial cells, cinnamic acid also increased the expression of SOCS3 in primary mouse microglia and astrocytes. We have seen that cAMP response element is present in the promoter of socs3 gene, that cinnamic acid induces the activation of CREB, that siRNA knockdown of CREB abrogates cinnamic acid-mediated upregulation of SOCS3, and that cinnamic acid treatment leads to the recruitment of CREB to the socs3 gene.

CONCLUSIONS

These studies suggest that cinnamic acid upregulates the expression of SOCS3 in glial cells via CREB pathway, which may be of importance in neuroinflammatory and neurodegenerative disorders.

Upregulation of tripeptidyl-peptidase 1 by 3-hydroxy-(2,2)-dimethyl butyrate, a brain endogenous ligand of PPARα: Implications for late-infantile Batten disease therapy

The late-infantile Batten disease or late-infantile neuronal ceroid lipofuscinosis (LINCL) is an autosomal recessive lysosomal storage disorder caused by mutations in the Cln2 gene leading to deficiency of lysosomal enzyme tripeptidyl peptidase 1 (TPP1). At present, available options for this fatal disorder are enzyme replacement therapy and gene therapy, which are extensively invasive and expensive. Our study demonstrates that 3-hydroxy-(2,2)-dimethyl butyrate (HDMB), a brain endogenous molecule, is capable of stimulating TPP1 expression and activity in mouse primary astrocytes and a neuronal cell line. HDMB activated peroxisome proliferator-activated receptor-α (PPARα), which, by forming heterodimer with Retinoid X receptor-α (RXRα), transcriptionally upregulated the Cln2 gene. Moreover, by using primary astrocytes from wild type, PPARα-/- and PPARβ-/- mice, we demonstrated that HDMB specifically required PPARα for inducing TPP1 expression. Finally, oral administration of HDMB to Cln2 heterozygous (Cln2+/-) mice led to a marked upregulation of TPP1 expression in the motor cortex and striatum in a PPARα-dependent fashion. Our study suggests that HDMB, a brain endogenous ligand of PPARα, might have therapeutic importance for LINCL treatment.

Aspirin ameliorates experimental autoimmune encephalomyelitis through interleukin-11-mediated protection of regulatory T cells

Multiple sclerosis (MS) is a human disease that results from autoimmune T cells targeting myelin protein that is expressed within the central nervous system. In MS, the number of FoxP3-expressing regulatory T cells (T_regs) is reduced, which facilitates the activation of autoreactive T cells. Because aspirin (acetylsalicylic acid) is the most widely used nonsteroidal anti-inflammatory drug, we examined its immunomodulatory effect in mice with experimental autoimmune encephalomyelitis (EAE), an animal model of MS. We found that low-dose aspirin suppressed the clinical symptoms of EAE in mouse models of both relapsing-remitting and chronic disease. Aspirin reduced the development of EAE driven by myelin basic protein (MBP)-specific T cells and the associated perivascular cuffing, inflammation, and demyelination. The effects of aspirin required the presence of CD25⁺FoxP3⁺ T_regs Aspirin increased the amounts of Foxp3 and interleukin-4 (IL-4) in T cells and suppressed the differentiation of naïve T cells into T helper 17 (T_H17) and T_H1 cells. Aspirin also increased the transcription of Il11 mediated by the transcription factor CREB, which was necessary for the generation of T_regs Neutralization of IL-11 negated the effects of aspirin on T_reg development and exacerbated EAE. Furthermore, we found that IL-11 alone was sufficient to maintain the percentage of FoxP3⁺ T_regs and protect mice from EAE. These results identify a previously uncharacterized mode of action of aspirin.

Anandamide inhibits FcεRI-dependent degranulation and cytokine synthesis in mast cells through CB2 and GPR55 receptor activation. Possible involvement of CB2-GPR55 heteromers

Activation of high affinity receptor for IgE (FcεRI) by IgE/antigen complexes in mast cells (MCs) leads to the release of preformed pro-inflammatory mediators stored in granules by a Ca²⁺-dependent process known as anaphylactic degranulation. Degranulation inhibition has been proposed as a strategy to control allergies and chronic inflammation conditions. Cannabinoids are important inhibitors of inflammatory reactions but their effects on IgE/Ag-mediated MCs responses are not well described. In this study, we analyzed the effect of the endocannabinoid anandamide (AEA), the selective CB₂ receptor agonist HU308, and the GPR55 receptor agonist lysophosphatidylinositol (LPI) on FcεRI-induced activation in murine bone marrow-derived mast cells (BMMCs). Our results show that AEA, HU380 and LPI inhibited FcεRI-induced degranulation in a concentration-dependent manner. This effect was mediated by CB₂ and GPR55 receptor activation through a mechanism insensitive to pertussis toxin. Degranulation inhibition was prevented by CB₂ and GPR55 antagonism, but not by CB₁ receptor blockage. AEA also inhibited calcium-dependent cytokine mRNA synthesis induced by FcεRI crosslinking, without affecting early phosphorylation events. In addition, AEA, HU308 and LPI inhibited intracellular Ca²⁺ rise in response to IgE/Ag. CB₂ and GPR55 receptor antagonism could not prevent the inhibition produced by AEA and HU308, but partially blocked the one caused by LPI. These results indicate that AEA inhibits IgE/Ag-induced degranulation through a mechanism that includes the participation of CB₂ and GPR55 receptors acting in close crosstalk, and show that CB₂-GPR55 heteromers are important negative regulators of FcεRI-induced responses in MCs.

Increase in Mitochondrial Biogenesis in Neuronal Cells by RNS60, a Physically-Modified Saline, via Phosphatidylinositol 3-Kinase-Mediated Upregulation of PGC1α

This study highlights a novel approach to upregulate mitochondrial biogenesis in neuronal cells. RNS60 is a 0.9% saline solution containing oxygenated nanobubbles that is generated by subjecting normal saline to Taylor-Couette-Poiseuille (TCP) flow under elevated oxygen pressure. RNS60, but not NS (normal saline), PNS60 (saline containing a comparable level of oxygen without the TCP modification), or RNS10.3 (TCP-modified normal saline without excess oxygen), increased the expression of Nrf1, Tfam, Mcu, and Tom20 (genes associated with mitochondrial biogenesis) and upregulated mitochondrial biogenesis in MN9D dopaminergic neuronal cells. Similarly RNS60 also increased mitochondrial biogenesis in primary dopaminergic neurons and in the nigra of MPTP-intoxicated mice. However, RNS60 had no effect on lysosomal biogenesis. Interestingly, we found that RNS60 upregulated PGC1α and siRNA knockdown of PGC1α abrogated the ability of RNS60 to increase mitochondrial biogenesis. Furthermore, we delineated that RNS60 increased the transcription of Pgc1a via type IA phosphatidylinositol (PI) 3-kinase-mediated activation of cAMP-response element-binding protein (CREB). Accordingly, knockdown of the PI3K – CREB pathway suppressed RNS60-mediated mitochondrial biogenesis. These results describe a novel property of RNS60 of enhancing mitochondrial biogenesis via PI 3-kinase-CREB-mediated up-regulation of PGC1α, which may be of therapeutic benefit in different neurodegenerative disorders.

Upregulation of Myelin Gene Expression by a Physically-Modified Saline via Phosphatidylinositol 3-Kinase-Mediated Activation of CREB: Implications for Multiple Sclerosis

An increase in central nervous system (CNS) remyelination and a decrease in CNS inflammation are important steps to halt the progression of multiple sclerosis (MS). RNS60 is a bioactive aqueous solution generated by subjecting normal saline to Taylor–Couette–Poiseuille flow under elevated oxygen pressure. Recently we have demonstrated that RNS60 exhibits anti-inflammatory properties. Here, we describe promyelinating property of RNS60. RNS60, but not normal saline (NS), RNS10.3 (TCP-modified saline without excess oxygen) or PNS60 (saline containing excess oxygen without TCP modification), stimulated the expression of myelin-specific genes and proteins (myelin basic protein, MBP; myelin oligodendrocyte glycoprotein, MOG and proteolipid protein, PLP) in primary mouse oligodendroglia and mixed glial cells. While investigating the mechanisms, we found that RNS60 treatment induced the activation of cAMP response element binding protein (CREB) in oligodendrocytes, ultimately leading to the recruitment of CREB to the promoters of myelin-specific genes. Furthermore, activation of type 1A p110β/α, but not type 1B p110γ, phosphatidylinositol-3 (PI-3) kinase by RNS60 together with abrogation of RNS60-mediated activation of CREB and upregulation of myelin genes by LY294002 (a specific inhibitor of PI-3 kinase) suggest that RNS60 upregulates the activation of CREB and the expression of myelin-specific molecules in oligodendrocytes via activation of PI3 kinase. These results highlight a novel promyelinating property of RNS60, which may be of benefit for MS and other demyelinating disorders.

Stimulation of nAchRα7 Receptor Inhibits TNF Synthesis and Secretion in Response to LPS Treatment of Mast Cells by Targeting ERK1/2 and TACE Activation

The cholinergic anti-inflammatory pathway is recognized as one of the main mechanisms of neuromodulation of the immune system. Activation of the α7 nicotinic acetylcholine receptor (nAchRα7) suppresses cytokine synthesis in distinct immune cells but the molecular mechanisms behind this effect remain to be fully described. Mast cells (MCs) are essential players of allergic reactions and innate immunity responses related to chronic inflammation. Activation of TLR4 receptor in MCs leads to the rapid secretion of pre-synthesized TNF from intracellular pools and to the activation of NFκB, necessary for de novo synthesis of TNF and other cytokines. Here we report that the nAchRα7 receptor specific agonist GTS-21 inhibits TLR4-induced secretion of preformed TNF from MCs in vivo and in vitro. Utilizing bone marrow-derived mast cells (BMMCs) it was found that GTS-21 also diminished secretion of de novo synthesized TNF, TNF mRNA accumulation and IKK-dependent p65-NFκB phosphorylation in response to LPS. nAchRα7 triggering prevented TLR4-induced ERK1/2 phosphorylation, which resulted an essential step for TNF secretion due to the phosphorylation of the metallopeptidase responsible for TNF maturation (TACE). Main inhibitory actions of GTS-21 were prevented by AG490, an inhibitor of JAK-2 kinase. Our results show for the first time, that besides the prevention of NFκB-dependent transcription, inhibitory actions of nAchRα7 triggering include the blockade of pathways leading to exocytosis of granule-stored cytokines in MCs.

Nebulization of RNS60, a Physically-Modified Saline, Attenuates the Adoptive Transfer of Experimental Allergic Encephalomyelitis in Mice: Implications for Multiple Sclerosis Therapy

Developing a new and effective therapeutic approach against multiple sclerosis (MS) is always an important area of research. RNS60 is a bioactive aqueous solution generated by subjecting normal saline to Taylor-Couette-Poiseuille flow under elevated oxygen pressure. Recently we have demonstrated that RNS60, administered through intraperitoneal injection, ameliorated clinical symptoms and disease progression of experimental allergic encephalomyelitis (EAE), an animal model of MS. Since the intravenous route is not preferred for treating a chronic condition, we tested if nebulization of RNS60 could attenuate the disease process of adoptively-transferred EAE in mice. Although we could not directly image RNS60 after nebulization, nebulized Alexa680 reached spleen, spinal cord and different parts of the brain. Nebulization of RNS60 starting from the acute phase attenuated clinical symptoms of relapsing-remitting EAE in female SJL/J mice. RNS60 nebulization also inhibited perivascular cuffing, maintained the integrity of blood-brain and blood-spinal cord barriers, suppressed inflammation, normalized the expression of myelin genes, and blocked demyelination in the CNS of EAE mice. On the immunomodulatory front, nebulization of RNS60 to EAE mice led to the enrichment of anti-autoimmune regulatory T cells (Tregs) and suppression of autoimmune Th17 cells. Together, these results suggest that nebulization of RNS60 may be used to control aberrant immune responses in MS and other autoimmune disorders.

Piperlongumine attenuates experimental autoimmune encephalomyelitis through inhibition of NF-kappaB activity

Multiple sclerosis (MS) is a chronic, autoimmune and neurodegenerative disease in which demyelination sporadically and repeatedly occurs in the central nervous system (CNS). The activity of nuclear factor kappa B (NF-κB), a family of transcription factors, was increased in the cerebrospinal fluid (CSF) and/or the serum and brain and/or spinal cord of MS patients than in a healthy donors. In our study, we investigated whether piperlongumine (PL), which is known to have inhibitory effect on activity of NF-κB, can alleviate an experimental autoimmune encephalomyelitis (EAE). The mice were immunized with myelin oligodendrocyte glycoprotein 35-55 (MOG35-55), and then we injected PL (1.5mg/kg/day or 3.0mg/kg/day) into the mice intraperitoneally on every second day from days 2 to 28. For in vitro study, we treated PL (0.5, 1 and 2.5μM) to RAW 264.7 and Jurkat cells with each stimulator. We observed that the paralytic severity and neuropathology of EAE in PL-treated group were decreased compared with the EAE group. PL showed a suppressed effect on demyelination, immune cells infiltration, astrocytes/microglials activation, level of inflammatory cytokines and proteins as well as NF-κB activity. Production of inflammatory cytokines and proteins as well as translocation of NF-κB into nucleus by treatment stimulators in RAW 264.7 and Jurkat cells were reduced by PL. Moreover, treatment of NF-κB inhibitor further inhibited production of inflammatory cytokines and proteins. These results suggest that PL can mitigate MOG-induced EAE symptoms and activation of macrophages and T cells by inhibiting NF-κB signaling. Therefore, PL could be useful for the treatment for MS.

Glyceryl Tribenzoate: A Flavoring Ingredient, Inhibits the Adoptive Transfer of Experimental Allergic Encephalomyelitis via TGF-β: Implications for Multiple Sclerosis Therapy

Multiple sclerosis (MS) is the most common autoimmune demyelinating disease of the central nervous system (CNS). Here, we have explored a novel use of glyceryl tribenzoate (GTB), a flavoring ingredient, in ameliorating the disease process of experimental allergic encephalomyelitis (EAE), an animal model of MS, via TGF-β. Oral feeding of GTB suppressed clinical symptoms of adoptively-transferred relapsing-remitting (RR) EAE in recipient mice and suppressed the generation of encephalitogenic T cells in donor mice. GTB also attenuated clinical symptoms of RR-EAE in PLP-TCR transgenic mice and chronic EAE in male C57/BL6 mice. Accordingly, GTB also suppressed perivascular cuffing, preserved the integrity of blood-brain barrier and blood-spinal cord barrier, inhibited inflammation, and stopped demyelination in the CNS of EAE mice. Interestingly, GTB treatment upregulated TGF-β and enriched regulatory T cells (Tregs) in splenocytes as well as in vivo in EAE mice. Blocking TGF-β by neutralizing antibodies abrogated GTB-mediated enrichment of Tregs and protection of EAE. These results suggest that oral GTB may be considered as a possible therapy for MS patients.

Lipopolysaccharide (LPS)-stimulated iNOS Induction Is Increased by Glucosamine under Normal Glucose Conditions but Is Inhibited by Glucosamine under High Glucose Conditions in Macrophage Cells

We investigated the regulatory effect of glucosamine (GlcN) for the production of nitric oxide (NO) and expression of inducible NO synthase (iNOS) under various glucose conditions in macrophage cells. At normal glucose concentrations, GlcN dose dependently increased LPS-stimulated production of NO/iNOS. However, GlcN suppressed NO/iNOS production under high glucose culture conditions. Moreover, GlcN suppressed LPS-induced up-regulation of COX-2, IL-6, and TNF-α mRNAs under 25 mm glucose conditions yet did not inhibit up-regulation under 5 mm glucose conditions. Glucose itself dose dependently increased LPS-induced iNOS expression. LPS-induced MAPK and IκB-α phosphorylation did not significantly differ at normal and high glucose conditions. The activity of LPS-induced nuclear factor-κB (NF-κB) and DNA binding of c-Rel to the iNOS promoter were inhibited under high glucose conditions in comparison with no significant changes under normal glucose conditions. In addition, we found that the LPS-induced increase in O-GlcNAcylation as well as DNA binding of c-Rel to the iNOS promoter were further increased by GlcN under normal glucose conditions. However, both O-GlcNAcylation and DNA binding of c-Rel decreased under high glucose conditions. The NF-κB inhibitor, pyrrolidine dithiocarbamate, inhibited LPS-induced iNOS expression under high glucose conditions but it did not influence iNOS induction under normal glucose conditions. In addition, pyrrolidine dithiocarbamate inhibited NF-κB DNA binding and c-Rel O-GlcNAcylation only under high glucose conditions. By blocking transcription with actinomycin D, we found that stability of LPS-induced iNOS mRNA was increased by GlcN under normal glucose conditions. These results suggest that GlcN regulates inflammation by sensing energy states of normal and fuel excess.

Antigen presentation for priming T cells in central system

Generation of myelin antigen-specific T cells is a major event in neuroimmune responses that causes demyelination. The antigen-priming of T cells and its location is important in chronic and acute inflammation. In autoimmune multiple sclerosis, the effector T cells are considered to generate in periphery. However, the reasons for chronic relapsing-remitting events are obscure. Considering mechanisms, a feasible aim of research is to investigate the role of antigen-primed T cells in lupus cerebritis. Last thirty years of investigations emphasize the relevance of microglia and infiltrated dendritic cells/macrophages as antigen presenting cells in the central nervous system. The recent approach towards circulating B-lymphocytes is an important area in the context. Here, we analyze the existing findings on antigen presentation in the central nervous system. The aim is to visualize signaling events of myelin antigen presentation to T cells and lead to the strategy of future goals on immunotherapy research.

Oxymatrine inhibits microglia activation via HSP60-TLR4 signaling

Oxymatrine (OMT) is an alkaloid extracted from Sophora flavescens, which has broad anti-inflammatory, antitumor and immunosuppressant actions. However, the underlying molecular mechanisms have remained elusive. Heat shock protein 60 (HSP60) has recently been shown to have an important role in autoimmune reactions. The present study aimed to investigate whether OMT exerts its anti-inflammatory effects by inhibiting microglial activation and examined the role of HSP60 in this process. Western blot analysis and ELISA showed that OMT decreased the expression and release of HSP60 by LPS-activated BV2 cells. The expression of heat shock factor 1, the transcription factor of HSP60, was also suppressed by OMT. Extracellular HSP60 has been previously indicated to induce microglial apoptosis through the Toll-like receptor (TLR)-4 pathway. Flow cytometric analysis demonstrated that LPS treatment induced apoptosis of BV2 cells, which was inhibited by OMT in parallel with inhibition of LPS-induced expression of TLR-4. Furthermore, OMT was shown to suppress the levels of myeloid differentiation factor (MYD)88, nuclear factor (NF)-κB, caspase-3, inducible nitric oxide synthase, tumor necrosis factor-α, interleukin (IL)-1β and IL-6. In light of these results, it was concluded that OMT may exert its neuroprotective effects via HSP60/TLR-4/MYD88/NF-κB signaling pathways to inhibit microglial activation. OMT may therefore offer substantial therapeutic potential for treating neurodegenerative diseases associated with microglial activation.

NF-κB Pathways in the Pathogenesis of Multiple Sclerosis and the Therapeutic Implications

Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathways are involved in cell immune responses, apoptosis and infections. In multiple sclerosis (MS), NF-κB pathways are changed, leading to increased levels of NF-κB activation in cells. This may indicate a key role for NF-κB in MS pathogenesis. NF-κB signaling is complex, with many elements involved in its activation and regulation. Interestingly, current MS treatments are found to be directly or indirectly linked to NF-κB pathways and act to adjust the innate and adaptive immune system in patients. In this review, we will first focus on the intricacies of NF-κB signaling, including the activating pathways and regulatory elements. Next, we will theorize about the role of NF-κB in MS pathogenesis, based on current research findings, and discuss some of the associated therapeutic implications. Lastly, we will review four new MS treatments which interrupt NF-κB pathways—fingolimod, teriflunomide, dimethyl fumarate (DMF) and laquinimod (LAQ)—and explain their mechanisms, and the possible strategy for MS treatments in the future.

Sodium Benzoate, a Food Additive and a Metabolite of Cinnamon, Enriches Regulatory T Cells via STAT6-Mediated Upregulation of TGF-β

Upregulation and/or maintenance of regulatory T cells (Tregs) during autoimmune insults may have therapeutic efficacy in autoimmune diseases. Earlier we have reported that sodium benzoate (NaB), a metabolite of cinnamon and a Food and Drug Administration-approved drug against urea cycle disorders, upregulates Tregs and protects mice from experimental allergic encephalomyelitis, an animal model of multiple sclerosis. However, mechanisms by which NaB increases Tregs are poorly understood. Because TGF-β is an important inducer of Tregs, we examined the effect of NaB on the status of TGF-β. In this study, we demonstrated that NaB induced the expression of TGF-β mRNA and protein in normal as well as proteolipid protein-primed splenocytes. The presence of a consensus STAT6 binding site in the promoter of the TGF-β gene, activation of STAT6 in splenocytes by NaB, recruitment of STAT6 to the TGF-β promoter by NaB, and abrogation of NaB-induced expression of TGF-β in splenocytes by small interfering RNA knockdown of STAT6 suggest that NaB induces the expression of TGF-β via activation of STAT6. Furthermore, we demonstrated that blocking of TGF-β by neutralizing Abs abrogated NaB-mediated protection of Tregs and experimental allergic encephalomyelitis. These studies identify a new function of NaB in upregulating TGF-β via activation of STAT6, which may be beneficial in MS patients.

IKKβ-mediated inflammatory myeloid cell activation exacerbates experimental autoimmune encephalomyelitis by potentiating Th1/Th17 cell activation and compromising blood brain barrier

Background

The inflammatory myeloid cell activation is one of the hallmarks of experimental autoimmune encephalomyelitis (EAE), yet the in vivo role of the inflammatory myeloid cell activation in EAE has not been clearly resolved. It is well-known that IKK/NF-κB is a key signaling pathway that regulates inflammatory myeloid activation.

Methods

We investigated the in vivo role of inflammatory myeloid cell activation in myelin oligodendrocyte glycoprotein (MOG) peptides-induced EAE using myeloid cell type-specific ikkβ gene conditional knockout-mice (LysM-Cre/Ikkβ^F/F).

Results

In our study, LysM-Cre/Ikkβ^F/F mice had alleviated clinical signs of EAE corresponding to the decreased spinal demyelination, microglial activation, and immune cell infiltration in the spinal cord, compared to the wild-type mice (WT, Ikkβ^F/F). Myeloid ikkβ gene deletion significantly reduced the percentage of CD4⁺/IFN-γ⁺ (Th1) and CD4⁺/IL-17⁺ (Th17) cells but increased the percentages of CD4⁺/CD25⁺/Foxp3⁺ (Treg) cells in the spinal cord and lymph nodes, corresponding to the altered mRNA expression of IFN-γ, IL-17, IL-23, and Foxp3 in the spinal cords of LysM-Cre/Ikkβ^F/F EAE mice. Also, the beneficial effect of myeloid IKKβ deletion in EAE corresponded to the decreased permeability of the blood brain barrier (BBB).

Conclusions

Our findings strongly suggest that IKK/NF-kB-induced myeloid cell activation exacerbates EAE by activating Th1 and Th17 responses and compromising the BBB. The development of NF-κB inhibitory agents with high efficacy through specific targeting of IKKβ in myeloid cells might be of therapeutic potential in MS and other autoimmune disorders.

Electronic supplementary material

The online version of this article (doi:10.1186/s13024-016-0116-1) contains supplementary material, which is available to authorized users.

LRP1 expression in microglia is protective during CNS autoimmunity

Multiple sclerosis is a devastating neurological disorder characterized by the autoimmune destruction of the central nervous system myelin. While T cells are known orchestrators of the immune response leading to MS pathology, the precise contribution of CNS resident and peripheral infiltrating myeloid cells is less well described. Here, we explore the myeloid cell function of Low-density lipoprotein receptor-related protein-1 (LRP1), a scavenger receptor involved in myelin clearance and the inflammatory response, in the context of Multiple sclerosis. Supporting its central role in Multiple sclerosis pathology, we find that LRP1 expression is increased in Multiple sclerosis lesions in comparison to the surrounding healthy tissue. Using two genetic mouse models, we show that deletion of LRP1 in microglia, but not in peripheral macrophages, negatively impacts the progression of experimental autoimmune encephalomyelitis, an animal model of Multiple sclerosis. We further show that the increased disease severity in experimental autoimmune encephalomyelitis is not due to haplodeficiency of the Cx3cr1 locus. At the cellular level, microglia lacking LRP1 adopt a pro-inflammatory phenotype characterized by amoeboid morphology and increased production of the inflammatory mediator TNF-α. We also show that LRP1 functions as a robust inhibitor of NF-kB activation in myeloid cells via a MyD88 dependent pathway, potentially explaining the increase in disease severity observed in mice lacking LRP1 expression in microglia. Taken together, our data suggest that the function of LRP1 in microglia is to keep these cells in an anti-inflammatory and neuroprotective status during inflammatory insult, including experimental autoimmune encephalomyelitis and potentially in Multiple sclerosis.

Cucurbitacin E Potently Modulates the Activity of Encephalitogenic Cells

Cucurbitacin E (CucE) is a highly oxidized steroid consisting of a tetracyclic triterpene. It is a member of a Cucurbitacin family of biomolecules that are predominantly found in Cucurbitaceae plants. CucE has already been identified as a potent anti-inflammatory compound. Here, its effects on CD4(+) T helper (Th) cells and macrophages, as the major encephalitogenic cells in the autoimmunity of the central nervous system, were investigated. Production of major pathogenic Th cell cytokines: interferon-gamma and interleukin-17 were inhibited under the influence of CucE. The effects of CucE on CD4(+) T cells were mediated through the modulation of aryl hydrocarbon receptor, STAT3, NFκB, p38 MAPK, and miR-146 signaling. Further, production of nitric oxide and reactive oxygen species, as well as phagocytic ability, were inhibited in macrophages treated with CucE. These results imply that CucE possesses powerful antiencephalitogenic activity.

Inducible nitric oxide synthase (NOS-2) in subarachnoid hemorrhage: Regulatory mechanisms and therapeutic implications

Aneurysmal subarachnoid hemorrhage (SAH) typically carries a poor prognosis. Growing evidence indicates that overabundant production of nitric oxide (NO) may be responsible for a large part of the secondary injury that follows SAH. Although SAH modulates the activity of all three isoforms of nitric oxide synthase (NOS), the inducible isoform, NOS-2, accounts for a majority of NO-mediated secondary injuries after SAH. Here, we review the indispensable physiological roles of NO that must be preserved, even while attempting to downmodulate the pathophysiologic effects of NO that are induced by SAH. We examine the effects of SAH on the function of the various NOS isoforms, with a particular focus on the pathological effects of NOS-2 and on the mechanisms responsible for its transcriptional upregulation. Finally, we review interventions to block NOS-2 upregulation or to counteract its effects, with an emphasis on the potential therapeutic strategies to improve outcomes in patients afflicted with SAH. There is still much to be learned regarding the apparently maladaptive response of NOS-2 and its harmful product NO in SAH. However, the available evidence points to crucial effects that, on balance, are adverse, making the NOS-2/NO/peroxynitrite axis an attractive therapeutic target in SAH.

Modulation of NF-κB Signaling as a Therapeutic Target in Autoimmunity

Autoimmune diseases arise from the loss of tolerance to endogenous self-antigens, resulting in a heterogeneous range of chronic conditions that cause considerable morbidity and mortality worldwide. In Western countries, over 5% of the population is affected by some form of autoimmune disease, with enhanced or inappropriate activation of nuclear factor (NF)-κB implicated in a number of these conditions. Although treatment strategies for autoimmunity have improved significantly in recent years, current therapeutics are still not capable of achieving satisfactory disease management in all patients, and as such, the therapeutic modulation of NF-κB is an attractive target in autoimmunity. To date, no NF-κB inhibitors have progressed to the clinic for the treatment of autoimmunity, but a variety of promising approaches targeting multiple stages of the NF-κB pathway are currently being explored. This review focuses on the current strategies being investigated for the inhibition of the NF-κB pathway in autoimmune diseases and considers potential future strategies for the therapeutic targeting of this crucial transcription factor.

Peptide-based inhibition of IκB kinase/nuclear factor-κB pathway protects against diabetes-associated nephropathy and atherosclerosis in a mouse model of type 1 diabetes

AIMS/HYPOTHESIS

The canonical nuclear factor-κB (NF-κB) pathway mediated by the inhibitor of NF-κB kinase (IKK) regulates the transcription of inflammatory genes involved in the pathogenesis of diabetes, from the early phase to progression and final complications. The NF-κB essential modulator binding domain (NBD) contained in IKKα/β is essential for IKK complex assembly. We therefore investigated the functional consequences of targeting the IKK-dependent NF-κB pathway in the progression of diabetes-associated nephropathy and atherosclerosis.

METHODS

Apolipoprotein E-deficient mice with diabetes induced by streptozotocin were treated with a cell-permeable peptide derived from the IKKα/β NBD region. Kidneys and aorta were analysed for morphology, leucocyte infiltrate, collagen, NF-κB activity and gene expression. In vitro studies were performed in renal and vascular cells.

RESULTS

NBD peptide administration did not affect the metabolic severity of diabetes but resulted in renal protection, as evidenced by dose-dependent decreases in albuminuria, renal lesions (mesangial expansion, leucocyte infiltration and fibrosis), intranuclear NF-κB activity and proinflammatory and pro-fibrotic gene expression. Furthermore, peptide treatment limited atheroma plaque formation in diabetic mice by decreasing the content of lipids, leucocytes and cytokines and increasing plaque stability markers. This nephroprotective and anti-atherosclerotic effect was accompanied by a decline in systemic T helper 1 cytokines. In vitro, NBD peptide prevented IKK assembly/activation, p65 nuclear translocation, NF-κB-regulated gene expression and cell proliferation induced by either high glucose or inflammatory stimulation.

CONCLUSIONS/INTERPRETATION

Peptide-based inhibition of IKK complex formation attenuates NF-κB activation, suppresses inflammation and retards the progression of renal and vascular injury in diabetic mice, thus providing a feasible approach against diabetes inflammatory complications.

The role of the ubiquitin-editing enzyme A20 in diseases of the central nervous system and other pathological processes

In recent years, the ubiquitin-editing enzyme A20 has been shown to control a large set of molecular pathways involved in the regulation of protective as well as self-directed immune responses. Here, we assess the current and putative roles of A20 in inflammatory, vascular and degenerative diseases of the central nervous system and explore future directions of research.

Activation of peroxisome proliferator-activated receptor α induces lysosomal biogenesis in brain cells: implications for lysosomal storage disorders

Lysosomes are ubiquitous membrane-enclosed organelles filled with an acidic interior and are central to the autophagic, endocytic, or phagocytic pathway. In contrast to its classical function as the waste management machinery, lysosomes are now considered to be an integral part of various cellular signaling processes. The diverse functionality of this single organelle requires a very complex and coordinated regulation of its activity with transcription factor EB (TFEB), a master regulator of lysosomal biogenesis, at its core. However, mechanisms by which TFEB is regulated are poorly understood. This study demonstrates that gemfibrozil, an agonist of peroxisome proliferator-activated receptor (PPAR) α, alone and in conjunction with all-trans-retinoic acid is capable of enhancing TFEB in brain cells. We also observed that PPARα, but not PPARβ and PPARγ, is involved in gemfibrozil-mediated up-regulation of TFEB. Reporter assay and chromatin immunoprecipitation studies confirmed the recruitment of retinoid X receptor α, PPARα, and PGC1α on the PPAR-binding site on the Tfeb promoter as well. Subsequently, the drug-mediated induction of TFEB caused an increase in lysosomal protein and the lysosomal abundance in cell. Collectively, this study reinforces the link between lysosomal biogenesis and lipid metabolism with TFEB at the crossroads. Furthermore, gemfibrozil may be of therapeutic value in the treatment of lysosomal storage disorders in which autophagy-lysosome pathway plays an important role.

Significance of NF-κB as a pivotal therapeutic target in the neurodegenerative pathologies of Alzheimer's disease and multiple sclerosis

INTRODUCTION

Advances in molecular pathogenesis suggest that the chronic inflammation is a shared mechanism in the initiation and progression of multiple neurodegenerative diseases with diverse clinical manifestations such as Alzheimer's disease (AD) and Multiple sclerosis (MS). Restricted cell renewal and regenerative capacity make the neural tissues extremely vulnerable to the uncontrolled inflammatory process leading to irreversible tissue damage.

AREAS COVERED

A predominant consequence of increased inflammatory signaling is the upregulation of the transcription factor, NF-κB with subsequent neuroprotective or deleterious effects depending on the strength of the signal and the type of NF-κB dimers activated. We discuss the interplay between neuroinflammation and neurodegeneration keeping in focus NF-κB signaling as the point of convergence of multiple pathways associated with the development of the neurodegenerative pathologies, AD and MS.

EXPERT OPINION

Considerable interest exists in developing efficient NF-κB inhibitors for neurodegenerative diseases. The review includes an overview of natural compounds and rationally designed agents that inhibit NF-κB and mediate neuroprotection in AD and MS. The key chemical moieties of the natural and the synthetic compounds provide efficient leads for the development of effective small molecule inhibitors that selectively target NF-κB activation; this would result in the desired benefit to risk therapeutic effects.

Cinnamon ameliorates experimental allergic encephalomyelitis in mice via regulatory T cells: implications for multiple sclerosis therapy

Upregulation and/or maintenance of regulatory T cells (Tregs) during an autoimmune insult may have therapeutic efficacy in autoimmune diseases. Although several immunomodulatory drugs and molecules are available, most present significant side effects over long-term use. Cinnamon is a commonly used natural spice and flavoring material used for centuries throughout the world. Here, we have explored a novel use of cinnamon powder in protecting Tregs and treating the disease process of experimental allergic encephalomyelitis (EAE), an animal model of MS. Oral feeding of cinnamon (Cinnamonum verum) powder suppresses clinical symptoms of relapsing-remitting EAE in female PLP-TCR transgenic mice and adoptive transfer mouse model. Cinnamon also inhibited clinical symptoms of chronic EAE in male C57/BL6 mice. Dose-dependent study shows that cinnamon powder at a dose of 50 mg/kg body wt/d or higher significantly suppresses clinical symptoms of EAE in mice. Accordingly, oral administration of cinnamon also inhibited perivascular cuffing, maintained the integrity of blood-brain barrier and blood-spinal cord barrier, suppressed inflammation, normalized the expression of myelin genes, and blocked demyelination in the central nervous system of EAE mice. Interestingly, cinnamon treatment upregulated Tregs via reduction of nitric oxide production. Furthermore, we demonstrate that blocking of Tregs by neutralizing antibodies against CD25 abrogates cinnamon-mediated protection of EAE. Taken together, our results suggest that oral administration of cinnamon powder may be beneficial in MS patients and that no other existing anti-MS therapies could be so economical and trouble-free as this approach.

O-GlcNAcylation and p50/p105 binding of c-Rel are dynamically regulated by LPS and glucosamine in BV2 microglia cells

BACKGROUND AND PURPOSE

Previously, we demonstrated that glucosamine (GlcN) exerts a suppressive effect on LPS-induced inducible NOS (iNOS) through the inhibition of NF-κB activation in BV2 mouse microglial cells. The purpose of the present study was to examine the mechanisms by which GlcN inhibits NF-κB activation.

EXPERIMENTAL APPROACH

BV2 cells were stimulated with LPS with or without GlcN. NF-κB/c-Rel activities were studied by EMSA, nuclear translocation, reporter assay or chromatin immunoprecipitation. Wheat germ agglutinin precipitation or galactosyltransferase assay were used to measure O-linked N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) of c-Rel. Protein-protein interactions were examined by co-immunoprecipitation.

KEY RESULTS

LPS stimulated the activation of c-Rel, increased the O-GlcNAcylation of c-Rel and enhanced the binding of c-Rel to the NF-κB site in the iNOS promoter; GlcN attenuated these effects of LPS. O-GlcNAcylation of both nuclear and cytosolic forms of c-Rel was increased by LPS and reduced by GlcN. LPS increased the interaction of c-Rel with O-GlcNAc transferase (OGT) and p50/p105, and GlcN suppressed these interactions. Knockdown of OGT reduced the c-Rel O-GlcNAcylation and c-Rel-p50 interaction in response to LPS, but did not affect either the binding of c-Rel to the iNOS promoter or the transcriptional activity of c-Rel.

CONCLUSIONS AND IMPLICATIONS

In BV2 microglial cells, the anti-inflammatory effect of GlcN is mediated by prevention of the prolonged activation of transcription factors, c-Rel and NF-κB. Further clarification of the mechanism by which GlcN exerts this effect will facilitate the development of pharmacological strategies for preventing excessive NO formation when targeting inflammatory diseases of the periphery or CNS.

A phase I clinical trial of systemically delivered NEMO binding domain peptide in dogs with spontaneous activated B-cell like diffuse large B-cell lymphoma

Activated B-Cell (ABC) Diffuse Large B-Cell Lymphoma (DLBCL) is a common, aggressive and poorly chemoresponsive subtype of DLBCL, characterized by constitutive canonical NF-κB signaling. Inhibition of NF-κB signaling leads to apoptosis of ABC-DLBCL cell lines, suggesting targeted disruption of this pathway may have therapeutic relevance. The selective IKK inhibitor, NEMO Binding Domain (NBD) peptide effectively blocks constitutive NF-κB activity and induces apoptosis in ABC-DLBCL cells in vitro. Here we used a comparative approach to determine the safety and efficacy of systemic NBD peptide to inhibit constitutive NF-κB signaling in privately owned dogs with spontaneous newly diagnosed or relapsed ABC-like DLBCL. Malignant lymph nodes biopsies were taken before and twenty-four hours after peptide administration to determine biological effects. Intravenous administration of <2 mg/kg NBD peptide was safe and inhibited constitutive canonical NF-κB activity in 6/10 dogs. Reductions in mitotic index and Cyclin D expression also occurred in a subset of dogs 24 hours post peptide and in 3 dogs marked, therapeutically beneficial histopathological changes were identified. Mild, grade 1 toxicities were noted in 3 dogs at the time of peptide administration and one dog developed transient subclinical hepatopathy. Long term toxicities were not identified. Pharmacokinetic data suggested rapid uptake of peptide into tissues. No significant hematological or biochemical toxicities were identified. Overall the results from this phase I study indicate that systemic administration of NBD peptide is safe and effectively blocks constitutive NF-κB signaling and reduces malignant B cell proliferation in a subset of dogs with ABC-like DLBCL. These results have potential translational relevance for human ABC-DLBCL.

Interleukin-12 (IL-12), but not IL-23, induces the expression of IL-7 in microglia and macrophages: implications for multiple sclerosis

Interleukin-12 (IL-12) p70 and IL-23 are bioactive cytokines and their biological functions are becoming clear. Increased expression of IL-7 in the central nervous system as well as in peripheral immune cells is associated with multiple sclerosis and experimental allergic encephalomyelitis. Here, we describe the induction of IL-7 in primary mouse and human microglia, BV-2 microglial cells, mouse peritoneal macrophages and astrocytes by IL-12p70. Interestingly, IL-12 strongly induced the expression of IL-7 whereas IL-23 and other p40 family members remained weak inducers of IL-7 in these cell types. Consistently, IL-12, but not IL-23 and other p40 family members, induced IL-7 promoter-driven luciferase activity in microglial cells. Among various stimuli tested, IL-12 emerged as the most potent stimulus followed by bacterial lipopolysaccharide and HIV-1 gp120 in inducing the activation of IL-7 promoter in microglial cells. Furthermore, increase in IL-7 mRNA expression by over-expression of IL-12p35 subunit, but not p40 and IL-23 p19 subunit, confirm that p35, but not p40 and p19, is responsible for the induction of IL-7. Finally, by using primary microglia from IL-12 receptor β1-deficient (IL-12Rβ1(-/-)) and IL-12Rβ2(-/-) mice, we demonstrate that IL-12 induces the expression of IL-7 in microglia and macrophages via both IL-12Rβ2 and IL-12Rβ1. These studies delineate a novel biological function of IL-12 that is absent in IL-23 and other p40 family members.

A novel caffeic acid-1-piperonylpiperazine hybridization compound HBU-47 inhibits LPS-mediated inflammation in RAW264.7 macrophage cells

In the present study, we synthesized a new hybrid compound by coupling caffeic acid and 1-piperonylpiperazine. The synthetic compound, acetyl-caffeic acid-1-piperonylpiperazine (HBU-47), showed potent anti-inflammatory effects inhibiting lipopolysaccharide (LPS)-induced production of nitric oxide (NO) in RAW264.7 macrophage cells. HBU-47 inhibited LPS-caused induction of inducible NO synthase (iNOS), cyclooxygenase-2, interleukin-6 and interleukin-1β in RAW264.7 cells in time- and dose-dependent manner. Compared to HBU-47, neither caffeic acid nor 1-piperonylpiperazine displayed significant inhibition of LPS responses. HBU-47 did not affect LPS-caused activation of mitogen-activated kinases (MAPKs) or IκB-α degradation. Instead, LPS-mediated NF-κB activation and DNA bindings of p65, p50 and c-Rel to the NF-κB binding site of iNOS promoter were inhibited by HBU-47. Overall, our data suggest that the novel caffeic acid hybrid compound downregulates inflammatory responses through inhibition of NF-κB and NF-κB-dependent gene expressions, thus, further suggesting its efficacy as a promising therapeutic agent.

Developmentally regulated GTP-binding protein 2 ameliorates EAE by suppressing the development of TH17 cells

Developmentally regulated GTP-binding protein 2 (DRG2) represents a novel subclass of GTP-binding proteins. We here report that transgenic overexpression of DRG2 in mice ameliorates experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS). The protective effect of DRG2 in EAE was mediated by the inhibition of the development of T(H)17 cells. DRG2 enhanced the activity of PPARγ, which led to an inhibition of the nuclear factor kappa B (NF-κB) activity and IL-6 production in antigen presenting cells and an inhibition of the development of T(H)17 cells. Our results demonstrate that DRG2 is an essential modulator of EAE.

Clinical implications of shared genetics and pathogenesis in autoimmune diseases

Many endocrine diseases, including type 1 diabetes mellitus, Graves disease, Addison disease and Hashimoto disease, originate as an autoimmune reaction that affects disease-specific target organs. These autoimmune diseases are characterized by the development of specific autoantibodies and by the presence of autoreactive T cells. They are caused by a complex genetic predisposition that is attributable to multiple genetic variants, each with a moderate-to-low effect size. Most of the genetic variants associated with a particular autoimmune endocrine disease are shared between other systemic and organ-specific autoimmune and inflammatory diseases, such as rheumatoid arthritis, coeliac disease, systemic lupus erythematosus and psoriasis. Here, we review the shared and specific genetic background of autoimmune diseases, summarize their treatment options and discuss how identifying the genetic and environmental factors that predispose patients to an autoimmune disease can help in the diagnosis and monitoring of patients, as well as the design of new treatments.

Nuclear factor kappa B (NF-κB) in multiple sclerosis pathology

The nuclear factor kappa B (NF-κB) signaling cascade plays a critical role in the regulation of immune and inflammatory responses and has been implicated in the pathogenesis of autoimmune demyelinating diseases such as multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), the main animal model of MS. NF-κB is essential for peripheral immune cell activation and the induction of pathology, but also plays crucial roles in resident cells of the central nervous system (CNS) during disease development. Here we review recent evidence clarifying the role of NF-κB in the different cell compartments contributing to MS pathology and its implications for the development of therapeutic strategies for the treatment of MS and other demyelinating pathologies of the CNS.

Reining in nuclear factor-kappaB in skeletal muscle disorders

PURPOSE OF REVIEW

Nuclear factor-kappaB (NF-κB) activation is associated with a wide range of muscle-related diseases. Here, we review the evidence implicating specific NF-κB components in different disease pathologies and discuss therapies designed to target aberrant NF-κB signaling for the treatment of those pathologies.

RECENT FINDINGS

Many components of the NF-κB signaling pathway contribute to muscle pathologies, presumably through activation of the transcription factor. In addition, an increasing number of upstream factors have been connected to disease progression. Genetic models and therapeutic approaches affecting these upstream targets associate with ameliorating disease progression.

SUMMARY

Dissecting the crosstalk between NF-κB, its upstream mediators, and other signaling pathways is vital to our understanding of how activation of this signaling pathway is mediated in various diseases. The strides made in therapeutically inhibiting the NF-κB pathway provide some promise for the treatment of these diseases.