Interleukin-6 expression in human multiple sclerosis lesions

Could NCOA5 a novel candidate gene for multiple sclerosis susceptibility?

BACKGROUND

Multiple sclerosis (MS) is an inflammatory immune-mediated demyelinating disease that causes a challenging and disabling condition. Environmental and genetic factors play a role in appearing the state of the disease. Recent studies have shown that nuclear cofactor genes may play a role in the pathogenesis of MS. NCOA5 is a nuclear receptor coactivator independent of AF2 that modulates ERa-mediated transcription. This gene is involved in the pathogenesis of diseases such as psoriasis, Behcet's disease, and cancer.

METHODS AND RESULTS

We investigated the relationship between the rs2903908 polymorphism of the NCOA5 gene and MS among 157 unrelated MS patients and 160 healthy controls by RT-PCR. The frequencies of the CC, CT, and TT genotypes were 19.87%, 37.82%, and 42.31%, respectively, for the MS group and 5.63%, 43.75%, and 50.62%, respectively, for the control group. The CC genotype and the C allele were found to be significantly higher in the patient group (the p values were 0.0002 and 0.003, respectively).

CONCLUSIONS

The fact that the CC genotype was found to be significantly higher in the patient group compared to the control group (p = 0.0002) and that it had a statistically significantly higher OR value (OR, 95% CI = 4.16, 1.91-9.05) suggests that the C allele may recessively predispose to MS for this polymorphism. These results suggest for the first time that the NCOA5 gene may have an effect on the occurrence of MS through different molecular pathways, which are discussed in the manuscript.

Astrogliosis in multiple sclerosis and neuro-inflammation: what role for the notch pathway?

Multiple sclerosis is an autoimmune inflammatory disease of the central nervous system leading to neurodegeneration. It affects 2.3 million people worldwide, generally younger than 50. There is no known cure for the disease, and current treatment options - mainly immunotherapies to limit disease progression - are few and associated with serious side effects. In multiple sclerosis, disruption of the blood-brain barrier is an early event in the pathogenesis of lesions, predisposing to edema, excito-toxicity and inflammatory infiltration into the central nervous system. Recently, the vision of the blood brain barrier structure and integrity has changed and include contributions from all components of the neurovascular unit, among which astrocytes. During neuro-inflammation, astrocytes become reactive. They undergo morphological and molecular changes named "astrogliosis" driving the conversion from acute inflammatory injury to a chronic neurodegenerative state. Astrogliosis mechanisms are minimally explored despite their significance in regulating the autoimmune response during multiple sclerosis. Therefore, in this review, we take stock of the state of knowledge regarding astrogliosis in neuro-inflammation and highlight the central role of NOTCH signaling in the process of astrocyte reactivity. Indeed, a very detailed nomenclature published in nature neurosciences in 2021, listing all the reactive astrocyte markers fully identified in the literature, doesn't cover the NOTCH signaling. Hence, we discuss evidence supporting NOTCH1 receptor as a central regulator of astrogliosis in the pathophysiology of neuro-inflammation, notably multiple sclerosis, in human and experimental models.

Mitogen-activated protein kinase inhibitor PD98059 improves neuroimmune dysfunction in experimental autoimmune encephalomyelitis in SJL/J mice through the inhibition of nuclear factor-kappa B signaling in B cells

Multiple sclerosis (MS) is a severe autoimmune disease leading to demyelination, followed by consequent axonal degeneration, causing sensory, motor, cognitive, and visual symptoms. Experimental autoimmune encephalomyelitis (EAE) is the most well-studied animal model of MS. Most current MS treatments are not completely effective, and severe side effects remain a great challenge. In this study, we report the therapeutic efficacy of PD98059, a potent mitogen-activated protein kinase inhibitor, on proteolipid protein (PLP)_139-151-induced EAE in SJL/J mice. Following the induction of EAE, mice were intraperitoneally treated with PD98059 (5 mg/kg for 14 days) daily from day 14 to day 28. This study investigated the effects of PD98059 on C-C motif chemokine receptor 6 (CCR6), CD14, NF-κB p65, IκBα, GM-CSF, iNOS, IL-6, TNF-α in CD45R⁺ B lymphocytes using flow cytometry. Furthermore, we analyzed the effect of PD98059 on CCR6, CD14, NF-κB p65, GM-CSF, iNOS, IL-6, and TNF-α mRNA and protein expression levels using qRT-PCR analysis in brain tissues. Mechanistic investigations revealed that PD98059-treated in mice with EAE had reduced CD45R⁺CCR6⁺, CD45R⁺CD14⁺, CD45R⁺NF-κB p65⁺, CD45R⁺GM-CSF⁺, CD45R⁺iNOS⁺, CD45R⁺IL-6⁺, and CD45R⁺TNF-α⁺ cells and increased CD45R⁺IκBα⁺ cells compared with vehicle-treated control mice in the spleen. Moreover, downregulation of CCR6, CD14, NF-κB p65, GM-CSF, iNOS, IL-6, and TNF-α mRNA expression level was observed in PD98059-treated mice with EAE compared with vehicle-treated control mice in the brain tissue. The results of this study demonstrate that PD98059 modulates inflammatory mediators through multiple cellular mechanisms. The results of this study suggest that PD98059 may be pursued as a therapeutic agent for the treatment of MS.

Secretomics Alterations and Astrocyte Dysfunction in Human iPSC of Leukoencephalopathy with Vanishing White Matter

Leukoencephalopathy with vanishing white matter (VWM) is an inherited leukoencephalopathy characterized by progressive rarefaction of cerebral white matter. Dysfunction of patient astrocyte plays a central role in the pathogenesis, while the immaturity of oligodendrocyte is probably secondary. How eIF2B mutant astrocytes affect the maturation and myelination of oligodendrocyte precursor cells (OPCs) is unclear yet. We used induced pluripotent stem cells (iPSCs) derived from our patient with EIF2B5 mutations to differentiate into astrocytes (AS) and OPCs, and aimed to verify that patient astrocytes inhibited the differentiation of OPCs by abnormalities of secreted proteins. eIF2B mutant astrocytes and astrocyte-conditioned medium (ACM) both inhibited the maturation of OPCs. It was revealed that 13 promising proteins exhibited a similar up- or downregulation by the PRM method correlated well with TMT results. eIF2B mutant astrocytes may secrete abnormal extracellular matrix (HA, LAMA4, BGN, FBN1, VASN, PCOLCE, MFAP4), cytokines (IL-6, CRABP1, ISG15), growth factors (PDGF-AA, CNTF, IGF-II, sFRP1, SERPINF1) and increased FABP7, which might lead to the differentiation and maturation disorder of OPCs. We analyzed the astrocyte-conditioned medium to find the key secretory molecules affecting the differentiation and maturation of OPCs, which provides potential clues for further research on the mechanism of VWM.

Serum levels of interleukin-6 and Vitamin D at the onset of multiple sclerosis and neuromyelitis optica: A pilot study

BACKGROUND

Interleukin-6 (IL-6) is an important mediator in the acute phase of inflammatory diseases such as neuromyelitis optica (NMO) and multiple sclerosis (MS). The level of IL-6 is higher in cerebrospinal fluid and serum of NMO patients compare to MS. Vitamin D has a regulatory effect on IL-6, so it may have a negative correlation with IL-6 in the acute phase of these diseases. This study was performed to evaluate the serum levels of IL-6 and Vitamin D in NMO and MS patients at the onset of disease to find differences that may help in early diagnosis.

MATERIALS AND METHODS

This case-control study was done on patients with the first episode of optic neuritis, transverse myelitis, and area postrema syndrome who were referred to Kashani MS Center in Isfahan, Iran, between January 2018 and January 2020. The serum levels of Vitamin D and IL-6 were assessed using enzyme-linked immunosorbent assay in blood sample taken at the time of first presentation in patients who had a definitive diagnosis of NMO and MS during subsequent workup.

RESULTS

During a 2-year follow-up, definitive diagnosis of NMO was given in 25 cases, and they were compared with 25 cases that were randomly selected from patients with definite MS. Nineteen patients in the NMO group and 21 patients in the MS group were female. The mean age of patients in the NMO and MS groups was 29.64 ± 1.47 and 30.20 ± 1.42, respectively (P = 0.46). The mean of serum level of Vitamin D was 24.88 ± 15.2 in NMO patients and 21.56 ± 18.7 in MS patients without significant difference (P = 0.48). The mean of IL-6 was 30.1 ± 22.62 in the NMO group and 23.35 ± 18.8 in the MS group without significant difference (P = 0.28). The serum levels of Vitamin D were insufficient in both groups. No correlation between Vitamin D and IL-6 levels was found in our study (P > 0.05).

CONCLUSION

Our results showed that serum IL-6 levels were higher at the onset of NMO disease compared with MS. The serum levels of Vitamin D were low in both groups and there was no association between serum levels of Vitamin D and IL-6 in either group. Future studies with large sample size are needed to confirm these findings.

Oligodendrocyte death and myelin loss in the cuprizone model: an updated overview of the intrinsic and extrinsic causes of cuprizone demyelination

The dietary consumption of cuprizone – a copper chelator – has long been known to induce demyelination of specific brain structures and is widely used as model of multiple sclerosis. Despite the extensive use of cuprizone, the mechanism by which it induces demyelination are still unknown. With this review we provide an updated understanding of this model, by showcasing two distinct yet overlapping modes of action for cuprizone-induced demyelination; 1) damage originating from within the oligodendrocyte, caused by mitochondrial dysfunction or reduced myelin protein synthesis. We term this mode of action ‘intrinsic cell damage’. And 2) damage to the oligodendrocyte exerted by inflammatory molecules, brain resident cells, such as oligodendrocytes, astrocytes, and microglia or peripheral immune cells – neutrophils or T-cells. We term this mode of action ‘extrinsic cellular damage’. Lastly, we summarize recent developments in research on different forms of cell death induced by cuprizone, which could add valuable insights into the mechanisms of cuprizone toxicity. With this review we hope to provide a modern understanding of cuprizone-induced demyelination to understand the causes behind the demyelination in MS.

Therapeutic Potential of Astrocyte Purinergic Signalling in Epilepsy and Multiple Sclerosis

Epilepsy and multiple sclerosis (MS), two of the most common neurological diseases, are characterized by the establishment of inflammatory environment in the central nervous system that drives disease progression and impacts on neurodegeneration. Current therapeutic approaches in the treatments of epilepsy and MS are targeting neuronal activity and immune cell response, respectively. However, the lack of fully efficient responses to the available treatments obviously shows the need to search for novel therapeutic candidates that will not exclusively target neurons or immune cells. Accumulating knowledge on epilepsy and MS in humans and analysis of relevant animal models, reveals that astrocytes are promising therapeutic candidates to target as they participate in the modulation of the neuroinflammatory response in both diseases from the initial stages and may play an important role in their development. Indeed, astrocytes respond to reactive immune cells and contribute to the neuronal hyperactivity in the inflamed brain. Mechanistically, these astrocytic cell to cell interactions are fundamentally mediated by the purinergic signalling and involve metabotropic P2Y1 receptors in case of astrocyte interactions with neurons, while ionotropic P2X7 receptors are mainly involved in astrocyte interactions with autoreactive immune cells. Herein, we review the potential of targeting astrocytic purinergic signalling mediated by P2Y1 and P2X7 receptors to develop novel approaches for treatments of epilepsy and MS at very early stages.

Transcriptomic Analysis of Fumarate Compounds Identifies Unique Effects of Isosorbide Di-(Methyl Fumarate) on NRF2, NF-kappaB and IRF1 Pathway Genes

Dimethyl fumarate (DMF) has emerged as a first-line therapy for relapsing-remitting multiple sclerosis (RRMS). This treatment, however, has been limited by adverse effects, which has prompted development of novel derivatives with improved tolerability. We compared the effects of fumarates on gene expression in astrocytes. Our analysis included diroximel fumarate (DRF) and its metabolite monomethyl fumarate (MMF), along with a novel compound isosorbide di-(methyl fumarate) (IDMF). Treatment with IDMF resulted in the largest number of differentially expressed genes. The effects of DRF and MMF were consistent with NRF2 activation and NF-κB inhibition, respectively. IDMF responses, however, were concordant with both NRF2 activation and NF-κB inhibition, and we confirmed IDMF-mediated NF-κB inhibition using a reporter assay. IDMF also down-regulated IRF1 expression and IDMF-decreased gene promoters were enriched with IRF1 recognition sequences. Genes altered by each fumarate overlapped significantly with those near loci from MS genetic association studies, but IDMF had the strongest overall effect on MS-associated genes. These results show that next-generation fumarates, such as DRF and IDMF, have effects differing from those of the MMF metabolite. Our findings support a model in which IDMF attenuates oxidative stress via NRF2 activation, with suppression of NF-κB and IRF1 contributing to mitigation of inflammation and pyroptosis.

Molecular Mechanisms of Immunosenescene and Inflammaging: Relevance to the Immunopathogenesis and Treatment of Multiple Sclerosis

Aging is characterized, amongst other features, by a complex process of cellular senescence involving both innate and adaptive immunity, called immunosenescence and associated to inflammaging, a low-grade chronic inflammation. Both processes fuel each other and partially explain increasing incidence of cancers, infections, age-related autoimmunity, and vascular disease as well as a reduced response to vaccination. Multiple sclerosis (MS) is a lifelong disease, for which considerable progress in disease-modifying therapies (DMTs) and management has improved long-term survival. However, disability progression, increasing with age and disease duration, remains. Neurologists are now involved in caring for elderly MS patients, with increasing comorbidities. Aging of the immune system therefore has relevant implications for MS pathogenesis, response to DMTs and the risks mediated by these treatments. We propose to review current evidence regarding markers and molecular mechanisms of immunosenescence and their relevance to understanding MS pathogenesis. We will focus on age-related changes in the innate and adaptive immune system in MS and other auto-immune diseases, such as systemic lupus erythematosus and rheumatoid arthritis. The consequences of these immune changes on MS pathology, in interaction with the intrinsic aging process of central nervous system resident cells will be discussed. Finally, the impact of immunosenescence on disease evolution and on the safety and efficacy of current DMTs will be presented.

Nobiletin attenuates inflammation via modulating proinflammatory and antiinflammatory cytokine expressions in an autoimmune encephalomyelitis mouse model

The aim of this study is to investigate the potential preventive and therapeutic effects of nobiletin by evaluating the expression of cytokines associated with inflammatory reactions in an autoimmune encephalomyelitis mouse model. A total of 60 male C57BL/6 mice aged between 8 and 10 weeks were used. Mice were divided into six groups (n = 10 mice per group): control, EAE, low-prophylaxis, high-prophylaxis, low-treatment and high-treatment. Experimental autoimmune encephalomyelitis (EAE) was induced by myelin oligodendrocyte glycoprotein (MOG) and pertussis toxin. Nobiletin was administered in low (25 mg/kg) and high (50 mg/kg) doses, intraperitoneally. The prophylactic and therapeutic effects of nobiletin on brain tissue and spinal cord were evaluated by expression of interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), interferon gamma (IFNγ), IL-6, IL-10 and transforming growth factor-beta (TGF-β) using immunohistochemistry and real-time polymerase chain reaction (RT-PCR). Prophylactic and therapeutic use of nobiletin inhibited EAE-induced increase of TNF-α, IL-1β and IL-6 activities to alleviate inflammatory response in brain and spinal cord. Moreover, nobiletin supplement dramatically increased the IL-10, TGF-β and IFNγ expressions in prophylaxis and treatment groups compared with the EAE group in the brain and spinal cord. The results obtained from this study show that prophylactic and therapeutic nobiletin modulates expressions of proinflammatory and antiinflammatory cytokines in brain and spinal cord dose-dependent manner in EAE model. These data demonstrates that nobiletin has a potential to attenuate inflammation in EAE mouse model. These experimental findings need to be supported by clinical studies.

Connecting Neuroinflammation and Neurodegeneration in Multiple Sclerosis: Are Oligodendrocyte Precursor Cells a Nexus of Disease?

The pathology in neurodegenerative diseases is often accompanied by inflammation. It is well-known that many cells within the central nervous system (CNS) also contribute to ongoing neuroinflammation, which can promote neurodegeneration. Multiple sclerosis (MS) is both an inflammatory and neurodegenerative disease in which there is a complex interplay between resident CNS cells to mediate myelin and axonal damage, and this communication network can vary depending on the subtype and chronicity of disease. Oligodendrocytes, the myelinating cell of the CNS, and their precursors, oligodendrocyte precursor cells (OPCs), are often thought of as the targets of autoimmune pathology during MS and in several animal models of MS; however, there is emerging evidence that OPCs actively contribute to inflammation that directly and indirectly contributes to neurodegeneration. Here we discuss several contributors to MS disease progression starting with lesion pathology and murine models amenable to studying particular aspects of disease. We then review how OPCs themselves can play an active role in promoting neuroinflammation and neurodegeneration, and how other resident CNS cells including microglia, astrocytes, and neurons can impact OPC function. Further, we outline the very complex and pleiotropic role(s) of several inflammatory cytokines and other secreted factors classically described as solely deleterious during MS and its animal models, but in fact, have many neuroprotective functions and promote a return to homeostasis, in part via modulation of OPC function. Finally, since MS affects patients from the onset of disease throughout their lifespan, we discuss the impact of aging on OPC function and CNS recovery. It is becoming clear that OPCs are not simply a bystander during MS progression and uncovering the active roles they play during different stages of disease will help uncover potential new avenues for therapeutic intervention.

Immune mediating molecules and pathogenesis of COVID-19-associated neurological disease

Background

Long period of SARS-CoV-2 infection has been associated with psychiatric and cognitive disorders in adolescents and children. SARS-CoV-2 remains dormant in the CNS leading to neurological complications. The wide expression of ACE2 in the brain raises concern for its involvement in SARS-CoV-2 infection. Though, the mechanistic insights about blood-brain barriers (BBB) crossing by SARS-CoV-2 and further brain infection are still not clear. Moreover, the mechanism behind dormant SARS-CoV-2 infections leading to chronic neurological disorders needs to be unveiled. There is an urgent need to find out the risk factor involved in COVID-19-associated neurological disease. Therefore, the role of immune-associated genes in the pathogenesis of COVID-19 associated neurological diseases is presented which could contribute to finding associated genetic risk factors.

Method

The search utilizing multiple databases, specifically, EMBASE, PubMed (Medline), and Google Scholar was performed. Moreover, the literature survey on the involvement of COVID-19, neuropathogenesis, and its consequences was done.

Description

Persistent inflammatory stimuli may promote the progression of neurodegenerative diseases. An increased expression level of cytokine, chemokine, and decreased expression level of immune cells has been associated with the COVID-19 patient. Cytokine storm was observed in severe COVID-19 patients. The nature of SARS-CoV-2 infection can be neuroinflammatory. Genes of immune response could be associated with neurodegenerative diseases.

Conclusion

The present review will provide a useful framework and help in understanding COVID-19-associated neuropathogenesis. Experimental studies on immune-associated genes in COVID-19 patients with neurological manifestations could be helpful to establish its neuropathogenesis.

Role of IL-6 in the regulation of neuronal development, survival and function

The pleiotropic cytokine interleukin-6 (IL-6) is emerging as a molecule with both beneficial and destructive potentials. It can exert opposing actions triggering either neuron survival after injury or causing neurodegeneration and cell death in neurodegenerative or neuropathic disorders. Importantly, neurons respond differently to IL-6 and this critically depends on their environment and whether they are located in the peripheral or the central nervous system. In addition to its hub regulator role in inflammation, IL-6 is recently emerging as an important regulator of neuron function in health and disease, offering exciting possibilities for more mechanistic insight into the pathogenesis of mental, neurodegenerative and pain disorders and for developing novel therapies for diseases with neuroimmune and neurogenic pathogenic components.

Altered astrocytic function in experimental neuroinflammation and multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) that affects about 2.5 million people worldwide. In MS, the patients' immune system starts to attack the myelin sheath, leading to demyelination, neurodegeneration, and, ultimately, loss of vital neurological functions such as walking. There is currently no cure for MS and the available treatments only slow the initial phases of the disease. The later-disease mechanisms are poorly understood and do not directly correlate with the activity of immune system cells, the main target of the available treatments. Instead, evidence suggests that disease progression and disability are better correlated with the maintenance of a persistent low-grade inflammation inside the CNS, driven by local glial cells, like astrocytes and microglia. Depending on the context, astrocytes can (a) exacerbate inflammation or (b) promote immunosuppression and tissue repair. In this review, we will address the present knowledge that exists regarding the role of astrocytes in MS and experimental animal models of the disease.

RAM-589.555 favors neuroprotective and anti-inflammatory profile of CNS-resident glial cells in acute relapse EAE affected mice

Background

Targeting RNA polymerase-1 (POL1) machinery is a new strategy for suppression of multiple sclerosis (MS) relapse activity. Oral administration of POL1 inhibitor RAM-589.555, which is characterized by high permeability and bioavailability in naïve mice, ameliorates proteolipid protein (PLP)-induced experimental autoimmune encephalomyelitis (EAE) by suppressing activated autoreactive lymphocytes. We assessed the accessibility of RAM-589.555 to the central nervous system (CNS) of EAE-mice and further investigated its immunomodulatory effects on CNS-resident astro- and micro-glial cells in-vitro and in-vivo.

Methods

Effects of RAM-589.555 on activated microglia and astrocyte viability, proliferation, and secretion of neurotrophic factors were assessed in-vitro. The pharmacokinetic of RAM-589.555 was evaluated in the blood and central nervous system (CNS) of EAE-affected mice. High-dimensional single-cell mass cytometry was applied to characterize the effect of RAM-589.555 on EAE-affected mice’s CNS-resident micro- and astroglial cells and CNS-infiltrating immune cells, which were obtained seven days after RAM-589.555 administration at EAE onset. Simultaneously, the expression level of pre-rRNA, the POL1 end product, was assessed in blood cells, microglia, and astrocytes to monitor RAM-589.555 effects.

Results

RAM-589.555 demonstrated blood and CNS permeability in EAE mice. In-vitro, incubation with 400 nM of RAM-589.555 significantly reduced viability and proliferation of lipopolysaccharide (LPS)-activated microglia by 70% and 45% (p < 0.05), respectively, while tumor necrosis factor α (TNFα)-activated astrocytes were not affected. The secretion of neurotrophic factors was preserved. Furthermore, 7 days after administration of RAM-589.555 at EAE onset, the level of pre-rRNA transcript in peripheral blood mononuclear cells (PBMC) was decreased by 38.6% (p = 0.02), while levels of pre-rRNA transcript in microglia and astrocytes remained unchanged. The high-dimensional single-cell mass cytometry analysis showed decreased percentages of CNS-resident microglia and astrocytes, diminished pro-inflammatory cytokines (IL-1β, IL-6, IL-12, IL-17, TNFα, and IFNγ), and an increase of their anti-inflammatory cytokines (IL-4, IL-10, and TGFβ) in RAM-589.555-treated compared to vehicle-treated mice (p < 0.05).

Conclusions

These data correlate RAM-589.555-induced clinical amelioration and its CNS-permeability to decreased CNS-inflammation, and decreased micro- and astrogliosis, while restoring micro- and astroglial anti-inflammatory and neuroprotective capacity.

Oligodendrocytes modulate the immune-inflammatory response in EAE via TNFR2 signaling

The pleotropic cytokine tumor necrosis factor (TNF) is involved in the pathophysiology of multiple sclerosis (MS). In various models of MS, including experimental autoimmune encephalomyelitis (EAE), the membrane-bound form of TNF (tmTNF), which signals primarily via TNFR2, mediates protective and reparative effects, whereas the soluble form (solTNF), which signals primarily via TNFR1, promotes pro-inflammatory and detrimental functions. In this study, we investigated the role of TNFR2 expressed in oligodendrocytes in the early phase of EAE pathogenesis. We demonstrated that mice with specific ablation of oligodendroglial TNFR2 displayed early onset and higher peak of motor dysfunction when subjected to EAE, in advance of which accelerated infiltration of immune cells was observed as early as 10 days post EAE induction. The immune cell influx was preceded by microglial activation and increased blood brain barrier permeability. Lack of oligodendroglial TNFR2 accelerated the expression of inflammatory cytokines as well as expression and activation of the inflammasome. Gene expression profiling of oligodendrocytes sorted from the spinal cord 14 days post EAE induction showed robust upregulation of inflammatory genes, some of which were elevated in cells lacking TNFR2 compared to controls. Together, our data demonstrate that oligodendrocytes are directly involved in inflammation and immune modulation in CNS disease and this function is regulated, at least in part, by TNFR2.

Interleukin-6 Derived from the Central Nervous System May Influence the Pathogenesis of Experimental Autoimmune Encephalomyelitis in a Cell-Dependent Manner

Background: Interleukin-6 (IL-6) is a pleiotropic and multifunctional cytokine that plays a critical role in induction of experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis (MS). Although EAE has always been considered a peripherally elicited disease, Il6 expression exclusively within central nervous system is sufficient to induce EAE development. Neurons, astrocytes, and microglia can secrete and respond to IL-6. Methods: To dissect the relevance of each cell source for establishing EAE, we generated and immunized conditional Il6 knockout mice for each of these cell types with myelin oligodendrocyte glycoprotein 35-55 (MOG_35-55) peptide dissolved in complete Freund’s adjuvant (CFA) and supplemented with Mycobacterium tuberculosis. Results and conclusions: The combined results reveal a minor role for Il6 expression in both astrocytes and microglia for symptomatology and neuropathology of EAE, whereas neuronal Il6 expression was not relevant for the variables analyzed.

Co-stimulation with IL-1β and TNF-α induces an inflammatory reactive astrocyte phenotype with neurosupportive characteristics in a human pluripotent stem cell model system

Astrocyte reactivation has been discovered to be an important contributor to several neurological diseases. In vitro models involving human astrocytes have the potential to reveal disease-specific mechanisms of these cells and to advance research on neuropathological conditions. Here, we induced a reactive phenotype in human induced pluripotent stem cell (hiPSC)-derived astrocytes and studied the inflammatory natures and effects of these cells on human neurons. Astrocytes responded to interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) treatment with a typical transition to polygonal morphology and a shift to an inflammatory phenotype characterized by altered gene and protein expression profiles. Astrocyte-secreted factors did not exert neurotoxic effects, whereas they transiently promoted the functional activity of neurons. Importantly, we engineered a novel microfluidic platform designed for investigating interactions between neuronal axons and reactive astrocytes that also enables the implementation of a controlled inflammatory environment. In this platform, selective stimulation of astrocytes resulted in an inflammatory niche that sustained axonal growth, further suggesting that treatment induces a reactive astrocyte phenotype with neurosupportive characteristics. Our findings show that hiPSC-derived astrocytes are suitable for modeling astrogliosis, and the developed in vitro platform provides promising novel tools for studying neuron-astrocyte crosstalk and human brain disease in a dish.

Setmelanotide, a Novel, Selective Melanocortin Receptor-4 Agonist Exerts Anti-inflammatory Actions in Astrocytes and Promotes an Anti-inflammatory Macrophage Phenotype

To date, available treatment strategies for multiple sclerosis (MS) are ineffective in preventing or reversing progressive neurologic deterioration, creating a high, and unmet medical need. One potential way to fight MS may be by limiting the detrimental effects of reactive astrocytes, a key pathological hallmark for disease progression. One class of compounds that may exert beneficial effects via astrocytes are melanocortin receptor (MCR) agonists. Among the MCR, MC4R is most abundantly expressed in the CNS and several rodent studies have described that MC4R is—besides neurons—expressed by astrocytes. Activation of MC4R in astrocytes has shown to have potent anti-inflammatory as well as neuroprotective effects in vitro, suggesting that this could be a potential target to ameliorate ongoing inflammation, and neurodegeneration in MS. In this study, we set out to investigate human MC4R expression and analyze its downstream effects. We identified MC4R mRNA and protein to be expressed on astrocytes and observed increased astrocytic MC4R expression in active MS lesions. Furthermore, we show that the novel, highly selective MC4R agonist setmelanotide ameliorates the reactive phenotype in astrocytes in vitro and markedly induced interleukin−6 and −11 production, possibly through enhanced cAMP response element-binding protein (CREB) phosphorylation. Notably, stimulation of human macrophages with medium from astrocytes that were exposed to setmelanotide, skewed macrophages toward an anti-inflammatory phenotype. Taken together, these findings suggest that targeting MC4R on astrocytes might be a novel therapeutic strategy to halt inflammation-associated neurodegeneration in MS.

The contribution of astrocytes to the neuroinflammatory response in multiple sclerosis and experimental autoimmune encephalomyelitis

Neuroinflammation is the coordinated response of the central nervous system (CNS) to threats to its integrity posed by a variety of conditions, including autoimmunity, pathogens and trauma. Activated astrocytes, in concert with other cellular elements of the CNS and immune system, are important players in the modulation of the neuroinflammatory response. During neurological disease, they produce and respond to cellular signals that often lead to dichotomous processes, which can promote further damage or contribute to repair. This occurs also in multiple sclerosis (MS), where astrocytes are now recognized as key components of its immunopathology. Evidence supporting this role has emerged not only from studies in MS patients, but also from animal models, among which the experimental autoimmune encephalomyelitis (EAE) model has proved especially instrumental. Based on this premise, the purpose of the present review is to summarize the current knowledge of astrocyte behavior in MS and EAE. Following a brief description of the pathological characteristics of the two diseases and the main functional roles of astrocytes in CNS physiology, we will delve into the specific responses of this cell population, analyzing MS and EAE in parallel. We will define the temporal and anatomical profile of astroglial activation, then focus on key processes they participate in. These include: (1) production and response to soluble mediators (e.g., cytokines and chemokines), (2) regulation of oxidative stress, and (3) maintenance of BBB integrity and function. Finally, we will review the state of the art on the available methods to measure astroglial activation in vivo in MS patients, and how this could be exploited to optimize diagnosis, prognosis and treatment decisions. Ultimately, we believe that integrating the knowledge obtained from studies in MS and EAE may help not only better understand the pathophysiology of MS, but also uncover new signals to be targeted for therapeutic intervention.

Association of Delta-6-Desaturase Expression with Aggressiveness of Cancer, Diabetes Mellitus, and Multiple Sclerosis: A Narrative Review

Background: The phosphatidylinositol 3-kinase/ protein kinase B /mammalian target of rapamycin (PI3K/Akt/ mTOR) signaling regulates multiple cellular processes and organizes cell proliferation, survival, and differentiation with the available nutrients, in particular, fatty acids. Polyunsaturated fatty acids (PUFAs) are cytotoxic to cancer cells and play a critical role in the treatment of multiple sclerosis (MS) and diabetes mellitus (DM). PUFAs are produced in the body by desaturases and elongases from dietary essential fatty acids (EFAs), primarily involving delta-6-desaturase (D6D). D6D is a rate-limiting enzyme for maintaining many aspects of lipid homeostasis and normal health. D6D is important to recognize the mechanisms that regulate the expression of this enzyme in humans. A lower level of D6D was seen in breast tumors compared to normal tissues. Interestingly, the elevated serum level of D6D was seen in MS and DM, which explains the critical role of D6D in inflammatory diseases. Methods: We searched databases of PubMed, Web of Science (WOS), Google Scholar, Scopus and related studies by predefined eligibility criteria. We assessed their quality and extracted data. Results: Regarding the mTOR signaling pathway, there is remarkable contributions of many inflammatory diseases to attention to common metabolic pathways are depicted. Of course, we need to have the insights into each disorder and their pathological process. The first step in balancing the intake of EFAs is to prevent the disruption of metabolism and expression of the D6D enzyme. Conclusions: The ω6 and ω3 pathways are two major pathways in the biosynthesis of PUFAs. In both of these, D6D is a vital bifunctional enzyme desaturating linoleic acid or alpha-linolenic acid. Therefore, if ω6 and ω3 EFAs are given together in a ratio of 2: 1, the D6D expression will be down-regulated and normalized.

Nox2-dependent Neuroinflammation in An EAE Model of Multiple Sclerosis

Background

Multiple sclerosis (MS) is an inflammatory disease of the CNS, characterized by demyelination, focal inflammatory infiltrates and axonal damage. Oxidative stress has been linked to MS pathology. Previous studies have suggested the involvement of NADPH oxidase 2 (Nox2), an enzyme that catalyzes the reduction of oxygen to produce reactive oxygen species, in the MS pathogenesis. The mechanisms of Nox2 activation on MS are unknown. The purpose of this study was to investigate the effect of Nox2 deletion on experimental autoimmune encephalomyelitis (EAE) onset and severity, on astrocyte activation as well as on pro-inflammatory and anti-inflammatory cytokine induction in striatum and motor cortex.

Methodology

Subcutaneous injection of MOG35-55 emulsified with complete Freund’s adjuvant was used to evaluate the effect of Nox2 depletion on EAE-induced encephalopathy. Striatum and motor cortices were isolated and evaluated by immunoblotting and RT-PCR.

Results

Nox2 deletion resulted in clinical improvement of the disease and prevented astrocyte activation following EAE induction. Nox2 deletion prevented EAE-induced induction of pro-inflammatory cytokines and stimulated the expression of the anti-inflammatory cytokines IL-4 and IL-10.

Conclusions

Our data suggest that Nox2 is involved on the EAE pathogenesis. IL-4 and IL-10 are likely to be involved on the protective mechanism observed following Nox2 deletion.

The formation of a glial scar does not prohibit remyelination in an animal model of multiple sclerosis

The role of astrocytes in the pathophysiology of multiple sclerosis (MS) is discussed controversially. Especially the formation of the glial scar is often believed to act as a barrier for remyelination. At the same time, astrocytes are known to produce factors that influence oligodendrocyte precursor cell (OPC) survival. To explore these mechanisms, we investigated the astrocytic reaction in an animal model induced by immunization with myelin oligodendrocyte glycoprotein (MOG) in Dark Agouti (DA) rats, which mimics most of the histological features of MS. We correlated the astroglial reaction by immunohistochemistry (IHC) for glial fibrillary acidic protein (GFAP) to the remyelination capacity by in situ hybridization for mRNA of proteolipid protein (PLP), indicative of OPCs, over the full course of the disease. PLP mRNA peaked in early remyelinating lesions while the amount of GFAP positive astrocytes was highest in remyelinated lesions. In shadow plaques, we found at the same time all features of a glial scar and numbers of OPCs and mature oligodendrocytes, which were nearly equal to that in unaffected white matter areas. To assess the plaque environment, we furthermore quantitatively analyzed factors expressed by astrocytes previously suggested to influence remyelination. From our data, we conclude that remyelination occurs despite an abundant glial reaction in this animal model. The different patterns of astrocytic factors and the occurrence of different astrocytic phenotypes during lesion evolution furthermore indicate a finely regulated, balanced astrocytic involvement leading to successful repair.

Mitochondrial Impairment in Oligodendroglial Cells Induces Cytokine Expression and Signaling

Widespread inflammatory lesions within the central nervous system grey and white matter are major hallmarks of multiple sclerosis. The development of full-blown demyelinating multiple sclerosis lesions might be preceded by preactive lesions which are characterized by focal microglia activation in close spatial relation to apoptotic oligodendrocytes. In this study, we investigated the expression of signaling molecules of oligodendrocytes that might be involved in initial microglia activation during preactive lesion formation. Sodium azide was used to trigger mitochondrial impairment and cellular stress in oligodendroglial cells in vitro. Among various chemokines and cytokines, IL6 was identified as a possible oligodendroglial cell-derived signaling molecule in response to cellular stress. Relevance of this finding for lesion development was further explored in the cuprizone model by applying short-term cuprizone feeding (2-4 days) on male C57BL/6 mice and subsequent analysis of gene expression, in situ hybridization and histology. Additionally, we analyzed the possible signaling of stressed oligodendroglial cells in vitro as well as in the cuprizone mouse model. In vitro, conditioned medium of stressed oligodendroglial cells triggered the activation of microglia cells. In cuprizone-fed animals, IL6 expression in oligodendrocytes was found in close vicinity of activated microglia cells. Taken together, our data support the view that stressed oligodendrocytes have the potential to activate microglia cells through a specific cocktail of chemokines and cytokines among IL6. Further studies will have to identify the temporal activation pattern of these signaling molecules, their cellular sources, and impact on neuroinflammation.

Human Induced Pluripotent Stem Cell-Derived Astrocytes Are Differentially Activated by Multiple Sclerosis-Associated Cytokines

Recent studies highlighted the importance of astrocytes in neuroinflammatory diseases, interacting closely with other CNS cells but also with the immune system. However, due to the difficulty in obtaining human astrocytes, their role in these pathologies is still poorly characterized. Here, we develop a serum-free protocol to differentiate human induced pluripotent stem cells (hiPSCs) into astrocytes. Gene expression and functional assays show that our protocol consistently yields a highly enriched population of resting mature astrocytes across the 13 hiPSC lines differentiated. Using this model, we first highlight the importance of serum-free media for astrocyte culture to generate resting astrocytes. Second, we assess the astrocytic response to IL-1β, TNF-α, and IL-6, all cytokines important in neuroinflammation, such as multiple sclerosis. Our study reveals very specific profiles of reactive astrocytes depending on the triggering stimulus. This model provides ideal conditions for in-depth and unbiased characterization of astrocyte reactivity in neuroinflammatory conditions.

Association of interleukin 6, interleukin 7 receptor alpha, and interleukin 12B gene polymorphisms with multiple sclerosis

Pro-inflammatory and anti-inflammatory cytokines have been shown to play a crucial role in the pathophysiology of multiple sclerosis (MS). We investigated the association between interleukin (IL) IL6-174 G/C (rs1800795), IL7RA C/T (rs6897932), and IL-12B A1188C (rs3212227) gene polymorphisms (SNPs) and MS. The study consisted of 297 unrelated MS patients and 135 healthy individuals. In IL6-174G/C (rs1800795), a significant association between the C allele and MS risk [OR 1.41, 95% CI (1.05-1.92); P = 0.025] was found. Carriage of genotypes CC and CG were more common in MS patients [OR 1.58, 95% CI (1.04-2.39); P = 0.031] and also in female MS patients [OR 1.68, 95% CI (1.02-2.79); P = 0.043]. However, after applying Bonferroni's correction the differences did not remain significant. No significant association between the IL7RA C/T (rs6897932) and IL12B A1188C (rs3212227) gene polymorphisms and MS susceptibility was observed. Regarding IL-12B A1188C (rs3212227), a significant association between the CC genotype and MS progression, expressed as MSSS, was demonstrated in the female MS group. Our results indicate that the distribution of IL6-174G/C (rs1800795) SNP was marginally associated with MS susceptibility. We also showed that IL-12B A1188C (rs3212227) can contribute to the progression of the disease in the Czech population.

Effects of inflammatory cytokines IFN-γ, TNF-α and IL-6 on the viability and functionality of human pluripotent stem cell-derived neural cells

Multiple Sclerosis (MS) is an inflammatory neurodegenerative disease, where neural progenitor cell (NPC) transplantation has been suggested as a potential neuroprotective therapeutic strategy. Since the effect of inflammation on NPCs is poorly known, their effect on the survival and functionality of human NPCs were studied. Treatment with interleukin (IL)-6, tumor necrosis factor (TNF)-α and interferon (IFN)-γ did not induced cytotoxicity, but IFN-γ treatment showed decreased proliferation and neuronal migration. By contrast, increased proliferation and inhibition of electrical activity were detected after TNF-α treatment. Treatments induced secretion of inflammatory factors. Inflammatory cytokines appear to modulate proliferation as well as the cellular and functional properties of human NPCs.

Deciphering sex differences in the immune system and depression

Certain mood disorders and autoimmune diseases are predominately female diseases but we do not know why. Here, we explore the relationship between depression and the immune system from a sex-based perspective. This review characterizes sex differences in the immune system in health and disease. We explore the contribution of gonadal and stress hormones to immune function at the cellular and molecular level in the brain and body. We propose hormonal and genetic sex specific immune mechanisms that may contribute to the etiology of mood disorders.

B cells in multiple sclerosis therapy-A comprehensive review

For decades, B cells were ignored in multiple sclerosis (MS) pathogenesis, and the disease was always regarded as a T cell-mediated disorder. Recent evidence shows that there is an antigen-driven B-cell response in the central nervous system of patients with MS, and memory B cells/plasma cells are detectable in MS lesions. The striking efficacy of B cell-depleting therapies in reducing the inflammatory activity of the disease highlights that B cells may play more pathogenetic roles than expected. B cells express several unique characteristic markers on their surface, for example, CD19, CD20 molecules, that provide selective targets for monoclonal antibodies. In this respect, several B cell-targeted therapies emerged, including anti-CD20 antibodies (rituximab, ocrelizumab, and ofatumumab), anti-CD19 antibody (inebilizumab), and agents targeting the BAFF/APRIL signaling pathway (atacicept, belimumab, and LY2127399). In this review, we discuss, in detail, the immunobiology of B cells and their protective and destructive roles in MS pathogenesis. In the second part, we list the completed and ongoing clinical trials investigating the safety and efficacy of B cell-related monoclonal antibodies in MS.

Analysis of IL-6, IL-1β and TNF-α production in monocytes isolated from multiple sclerosis patients treated with disease modifying drugs

OBJECTIVE AND DESIGN

The etiology of multiple sclerosis (MS) is unknown, but blood derived monocytes/macrophages are believed to be involved in the pathogenesis through phagocytosis of myelin and production of inflammatory mediators. The objective of this study is to examine inflammatory cytokines that are present at elevated levels in active MS lesions to determine whether there are differences between classically stimulated monocytes isolated from healthy control (HC) and relapsing-remitting MS (RRMS) subjects taking disease modifying drugs (DMDs), including dimethyl fumarate (DMF).

SUBJECTS

Thirty-nine veterans of the US Armed Forces were enrolled, 21 health controls (HC), and 18 with relapsing-remitting MS (RRMS), all taking DMDs.

METHODS

Use ELISAs to measure production of IL-6, IL-1β and TNF-α by LPS-stimulated peripheral monocytes.

RESULTS

Activation of monocytes from MS subjects produced significantly more IL-6 than healthy controls (49531 ± 20795 vs 10526 ± 4845), and IL-6 production trended higher in MS subjects taking DMF than those taking other DMDs (72186.9 ± 35156.2 vs 32585.8 ± 17135.4). There were no significant differences in IL-1β or TNF-α secretion.

CONCLUSIONS

Our data suggest that not all DMDs may provide disease modification by suppressing monocyte/macrophage production of pro-inflammatory mediators.

High-mobility group box-1 as an autocrine trophic factor in white matter stroke

Maintenance of white matter integrity in health and disease is critical for a variety of neural functions. Ischemic stroke in the white matter frequently results in degeneration of oligodendrocytes (OLs) and myelin. Previously, we found that toll-like receptor 2 (TLR2) expressed in OLs provides cell-autonomous protective effects on ischemic OL death and demyelination in white matter stroke. Here, we identified high-mobility group box-1 (HMGB1) as an endogenous TLR2 ligand that promotes survival of OLs under ischemic stress. HMGB1 rapidly accumulated in the culture medium of OLs exposed to oxygen-glucose deprivation (OGD). This conditioned medium exhibited a protective activity against ischemic OL death that was completely abolished by immunodepletion of HMGB1. Knockdown of HMGB1 or application of glycyrrhizin, a specific HMGB1 inhibitor, aggravated OGD-induced OL death, and recombinant HMGB1 application reduced the extent of OL death in a TLR2-dependent manner. We confirmed that cytosolic translocation of HMGB1 and activation of TLR2-mediated signaling pathways occurred in a focal white matter stroke model induced by endothelin-1 injection. Animals with glycyrrhizin coinjection showed an expansion of the demyelinating lesion in a TLR2-dependent manner, accompanied by aggravation of sensorimotor behavioral deficits. These results indicate that HMGB1/TLR2 activates an autocrine trophic signaling pathways in OLs and myelin to maintain structural and functional integrity of the white matter under ischemic conditions.

Astrocyte-targeted production of interleukin-6 reduces astroglial and microglial activation in the cuprizone demyelination model: Implications for myelin clearance and oligodendrocyte maturation

Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system. Interleukin (IL)-6 is a pleiotropic cytokine with a potential role in MS. Here we used transgenic mice with astrocyte-targeted production of IL-6 (GFAP-IL6Tg) to study the effect of IL-6 in the cuprizone-induced demyelination paradigm, which is an experimental model of de- and re-myelination, both hallmarks of MS. Our results demonstrated that cuprizone-treated GFAP-IL6Tg mice showed a significant reduction in astroglial and especially microglial activation/accumulation in the corpus callosum in comparison with the corresponding cuprizone-treated wild type (WT). Production of a key microglial attracting chemokine CXCL10, as well as CXCL1 and CCL4 was lower in cuprizone-treated GFAP-IL6Tg mice compared with cuprizone-treated WT. Reduced microglial cell accumulation was associated with inefficient removal of degraded myelin and axonal protection in cuprizone-treated GFAP-IL6Tg mice, compared with WT mice at the peak of demyelination. In addition, transgenic production of IL-6 did not alter initial oligodendrocyte (OL) apoptosis and oligodendrocyte precursor cell recruitment to the lesion site, but it impaired early OL differentiation, possibly due to impaired removal of degraded myelin. Indeed, a microglial receptor involved in myelin phagocytosis, TREM2, as well as the phagolysosomal protein CD68 were lower in cuprizone-treated GFAP-IL6Tg compared with WT mice. Our results show for the first time that astrocyte-targeted production of IL-6 may play a role in modulating experimental demyelination induced by cuprizone. Further understanding of the IL-6-mediated molecular mechanisms involved in the regulation of demyelination is needed, and may have implications for the development of future therapeutic strategies for the treatment of MS. GLIA 2016;64:2104-2119.

Alterations in immune cells and mediators in the brain: it's not always neuroinflammation!

Neuroinflammation was once a clearly defined term denoting pathological immune processes within the central nervous system (CNS). Historically, this term was used to indicate the four hallmarks of peripheral inflammaton that occur following severe CNS injuries, such as stroke, injury or infection. Recently, however, the definition of neuroinflammation has relaxed to the point that it is often now assumed to be present when even only a single classical hallmark of inflammation is measured. As a result, a wide range of disorders, from psychiatric to degenerative diseases, are now assumed to have an integral inflammatory component. Ironically, at the same time, research has revealed unexpected nonclassical immune actions of immune mediators and cells in the CNS in the absence of pathology, increasing the likelihood that homeostatic and adaptive immune processes in the CNS will be mistaken for neuroinflammation. Thus, we suggest reserving the term neuroinflammation for contexts where multiple signs of inflammation are present to avoid erroneously classifying disorders as inflammatory when they may instead be caused by nonimmune etiologies or secondary immune processes that serve adaptive roles.

Seeking balance: Potentiation and inhibition of multiple sclerosis autoimmune responses by IL-6 and IL-10

The cytokines IL-6 and IL-10 are produced by cells of the adaptive and innate arms of the immune system and they appear to play key roles in genetically diverse autoimmune diseases such as relapsing remitting multiple sclerosis (MS), rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Whereas previous intense investigations focused on the generation of autoantibodies and their contribution to immune-mediated pathogenesis in these diseases; more recent attention has focused on the roles of cytokines such as IL-6 and IL-10. In response to pathogens, antigen presenting cells (APC), including B cells, produce IL-6 and IL-10 in order to up-or down-regulate immune cell activation and effector responses. Evidence of elevated levels of the proinflammatory cytokine IL-6 has been routinely observed during inflammatory responses and in a number of autoimmune diseases. Our recent studies suggest that MS peripheral blood B cells secrete higher quantities of IL-6 and less IL-10 than B cells from healthy controls. Persistent production of IL-6, in turn, contributes to T cell expansion and the functional hyperactivity of APC such as MS B cells. Altered B cell activity can have a profound impact on resultant T cell effector functions. Enhanced signaling through the IL-6 receptor can effectively inhibit cytolytic activity, induce T cell resistance to IL-10-mediated immunosuppression and increase skewing of autoreactive T cells to a pathogenic Th17 phenotype. Our recent findings and studies by others support a role for the indirect attenuation of B cell responses by Glatiramer acetate (GA) therapy. Our studies suggest that GA therapy temporarily permits homeostatic regulatory mechanisms to be reinstated. Future studies of mechanisms underlying dysregulated B cell cytokine production could lead to the identification of novel targets for improved immunoregulatory therapies for autoimmune diseases.

Neurotrophic factors and their effects in the treatment of multiple sclerosis

Neurotrophins are small molecules of polypeptides, which include nerve growth factor (NGF) family, glial cell line–derived neurotrophic factor (GDNF) family ligands, and neuropoietic cytokines. These factors have an important role in neural regeneration, remyelination, and regulating the development of the peripheral and central nervous systems (PNS and CNS, respectively) by intracellular signaling through specific receptors. It has been suggested that the pathogenesis of human neurodegenerative disorders may be due to an alteration in the neurotrophic factors and their receptors. The use of neurotrophic factors as therapeutic agents is a novel strategy for restoring and maintaining neuronal function during neurodegenerative disorders such as multiple sclerosis. Innate and adaptive immune responses contribute to pathology of neurodegenerative disorders. Furthermore, autoimmune and mesenchymal stem cells, by the release of neurotrophic factors, have the ability to protect neuronal population and can efficiently suppress the formation of new lesions. So, these cells may be an alternative source for delivering neurotrophic factors into the CNS.

Astroglial PGC-1alpha increases mitochondrial antioxidant capacity and suppresses inflammation: implications for multiple sclerosis

Recent evidence suggests that reactive oxygen species (ROS) produced by inflammatory cells drive axonal degeneration in active multiple sclerosis (MS) lesions by inducing mitochondrial dysfunction. Mitochondria are endowed with a variety of antioxidant enzymes, including peroxiredoxin-3 and thioredoxin-2, which are involved in limiting ROS-induced damage. In this study, we explored the distribution and role of the mitochondrial antioxidants peroxiredoxin-3 and thioredoxin-2 as well as their regulator peroxisome proliferator-activated receptor gamma coactivator1-alpha (PGC-1α) in MS pathogenesis.

Immunohistochemical analysis of a large cohort of MS patients revealed a striking upregulation of PGC-1α and downstream mitochondrial antioxidants in active demyelinating MS lesions. Enhanced expression was predominantly observed in reactive astrocytes. To elucidate the functional role of astrocytic PGC-1α in MS pathology, we generated human primary astrocytes that genetically overexpressed PGC-1α. Upon an oxidative insult, these cells were shown to produce less ROS and were found to be more resistant to ROS-induced cell death compared to control cells. Intriguingly, also neuronal cells co-cultured with PGC-1α-overexpressing astrocytes were protected against an exogenous oxidative attack compared to neuronal cells co-cultured with control astrocytes. Finally, enhanced astrocytic PGC-1α levels markedly reduced the production and secretion of the pro-inflammatory mediators interleukin-6 and chemokine (C-C motif) ligand 2. Our findings suggest that increased astrocytic PGC-1α in active MS lesions might initially function as an endogenous protective mechanism to dampen oxidative damage and inflammation thereby reducing neurodegeneration. Activation of PGC-1α therefore represents a promising therapeutic strategy to improve mitochondrial function and repress inflammation.

MS14, a Marine Herbal Medicine, an Immunosuppressive Drug in Experimental Autoimmune Encephalomyelitis

Background:

Cytokines are secreted signaling proteins which play essential roles in immune responses during experimental autoimmune encephalomyelitis (EAE), a demyelinating model that mimics many features of multiple sclerosis (MS). Interleukin 6 (IL-6) is a multifunctional cytokine produced by different cells, mediating inflammatory reactions and immune-mediated processes. Several studies have described immunosuppressive potentials of several herbal medicines. MS14 as an Iranian marine herbal medicine has anti-inflammatory and immunomodulatory activities.

Objectives:

The present study investigated the immunosuppressive potential of MS14 as an herbal drug as well as the IL-6 level in EAE model. We hope it will be a new approach for neurologic diseases and autoimmune originated diseases therapy.

Patients and Methods:

The present experimental study was a collaboration between Department of Anatomical Sciences of Tabriz University of Medical Sciences and Shefa Neuroscience Research Center of Tehran. We used 30 C57BL/6 mice. The animals were immunized with myelin oligodendrocyte glycoprotein (MOG) to induce EAE and treated with MS14-containing (30%) diets. Subjects were selected by simple random sampling and then they were randomly allocated to two groups. EAE symptoms were assessed using the standard 10–point EAE scoring system from the seventh to the 35th day after immunization. Afterwards, the spleen was removed and its cells were cultured with or without MOG 35-55; then, the IL-6 level was analyzed by ELISA. In addition, histopathological studies were carried out for demyelination lesion evaluation in the spinal cord.

Results:

MS14 significantly improved clinical symptoms of EAE compared with the control (P < 0.05). It also suppressed proliferative responses of T cells and decreased IL-6 expression (16.93 ± 2.7 vs. 21.4 ± 3.33) (P < 0.05).

Conclusions:

Our results strongly suggested that IL-6 as a potential molecule could have a role in neuroimmunology and neuroinflammation, which is in congruent with previous studies. Therefore, it can be a clear target in strategic therapies and support effective properties of phytotherapy in EAE and MS treatment.

Role of toll-like receptor 2 in ischemic demyelination and oligodendrocyte death

White matter is frequently involved in ischemic stroke, and progressive ischemic white matter injuries are associated with various neurologic dysfunctions in the elderly population. Demyelination and oligodendrocyte (OL) loss are prominent features of ischemic white matter injury. Endothelin-1 injection into the internal capsule resulted in a localized demyelinating lesion in mice, where loss of OL lineage cells and inflammatory cell infiltration were observed accompanied by upregulation of toll-like receptor 2 (TLR2). Intriguingly, the extent of demyelinating pathology was markedly larger in TLR2 deficient mice than that of wild-type (WT) mice. TLR2 deficient mice showed enhanced OL death and decreased phosphorylation of ERK1/2 compared with WT animals. Cultured OLs from TLR2 deficient mice were more vulnerable to oxygen-glucose deprivation than WT OLs. Applying TLR2 agonists Pam3CSK4 or Zymosan after oxygen-glucose deprivation substantially rescued WT OL death with augmentation of ERK1/2 phosphorylation. Treatment with Pam3CSK4 also reduced the extent of endothelin-1 induced ischemic demyelination in vivo. Our data indicate TLR2 may provide endogenous protective effects on ischemic demyelination and OL degeneration.

Association between IL-6-174G/C polymorphism and risk of multiple sclerosis: a meta-analysis

OBJECTIVE

Interleukin-6 (IL-6) is a pleiotropic cytokine and important mediator of many inflammatory processes, which might affect susceptibility to multiple sclerosis (MS). The aim of this study was to assess the effect of IL-6-174G/C polymorphism on the risk of MS using a meta-analysis.

MATERIALS AND METHODS

The Pubmed, ISI Web of Science, Wanfang, VIP, and China National Knowledge Infrastructure databases were screened and six studies were included in the meta-analysis. Pooled odds ratios (ORs) with corresponding 95% confidence intervals (CI) were calculated to evaluate the association between the IL-6-174G/C polymorphism and risk of MS.

RESULTS

No significant association between the IL-6-174G/C polymorphism and risk of MS was observed in overall analyses. With stratification according to ethnicity, we found that carriers with the IL-6-174CC genotype had a 1.87-fold increased risk for the development of MS in Asians (recessive model: OR=1.87, 95% CI, 1.08-3.24), but not in Caucasians.

CONCLUSION

This meta-analysis provides evidence that the IL-6-174G/C polymorphism may be a risk factor for the development of MS in Asians. Further association studies with a larger sample size are required to confirm the result in different populations.

Astrocyte-specific activation of TNFR2 promotes oligodendrocyte maturation by secretion of leukemia inhibitory factor

Tumor necrosis factor (TNF) and its receptors TNFR1 and TNFR2 have pleiotropic effects in neurodegenerative disorders. For example, while TNFR1 mediates neurodegenerative effects in multiple sclerosis, TNFR2 is protective and contributes to remyelination. The exact mode of TNFR2 action, however, is poorly understood. Here, we show that TNFR2-mediated activation of the PI3K-PKB/Akt pathway in primary astrocytes increased the expression of neuroprotective genes, including that encoding the neurotrophic cytokine leukemia inhibitory factor (LIF). To investigate whether intercellular signaling between TNFR2-stimulated astrocytes and oligodendrocytes plays a role in oligodendrocyte maturation, we established an astrocyte-oligodendrocyte coculture model, composed of primary astrocytes from huTNFR2-transgenic (tgE1335) mice and oligodendrocyte progenitor cells (OPCs) from wild-type mice, capable of differentiating into mature myelinating oligodendrocytes. In this model, selective stimulation of human TNFR2 on astrocytes, promoted differentiation of cocultured OPCs to myelin basic protein-positive mature oligodendrocytes. Addition of LIF neutralizing antibodies inhibited oligodendrocyte differentiation, indicating a crucial role of TNFR2-induced astrocyte derived LIF for oligodendrocyte maturation.

Cytokine profile in relapsing‑remitting multiple sclerosis patients and the association between progression and activity of the disease

Multiple sclerosis (MS) is a progressive immune‑ mediated disease caused by demyelination of the central nervous system. Cytokines and their receptors have an important role in the evolution of MS lesions, and pro‑ and anti‑inflammatory cytokine levels have been found to correlate with changes in MS disease activity. The aims of the present study were to evaluate the pro‑inflammatory [tumor necrosis factor (TNF)‑α and interleukin (IL) ‑1β, ‑6 and ‑12], T helper (Th) 1 [interferon (IFN)‑γ], Th17 (IL‑17) and Th2 (IL‑4 and ‑10) cytokine serum levels in relapsing‑remitting (RR)‑MS patients and to evaluate the association between the cytokine profile and the progression and activity of the disease. Serum cytokine levels were assessed using enzyme linked‑immunosorbent assays in 169 RR‑MS patients in the remission clinical phase and 132 healthy individuals who were age‑, gender‑, ethnicity‑ and body mass index‑matched. Disability and activity of the disease were evaluated using the Expanded Disability Status Scale and magnetic resonance imaging with gadolinium, respectively. IFN‑γ and IL‑6, ‑12 and ‑4 levels were higher in RR‑MS patients compared to controls (P=0.0009, 0.0114, 0.0297 and 0.0004, respectively). IL‑1 levels were higher in controls compared with RR‑MS patients. IL‑4 levels were higher in RR‑MS patients with mild disability compared to those with moderate and severe disability (P=0.0375). TNF‑α and IL‑10 levels were higher in RR‑MS patients with inactive disease compared with those with active disease. IL‑17 levels showed a trend towards being higher in RR‑MS patients with inactive disease compared to those with active disease (P=0.0631). Low TNF‑α and high IFN‑γ levels were independently associated with RR‑MS (P=0.0078 and 0.0056, respectively) and also with the activity of the disease (P=0.0348 and 0.0133, respectively). Results indicated that RR‑MS patients, even in the remission clinical phase, exhibit a complex system of inflammatory and anti‑inflammatory cytokines that may interact to modulate the progression and activity of the disease.

Poor cerebral inflammatory response in eIF2B knock-in mice: implications for the aetiology of vanishing white matter disease

Background

Mutations in any of the five subunits of eukaryotic translation initiation factor 2B (eIF2B) can lead to an inherited chronic-progressive fatal brain disease of unknown aetiology termed leucoencephalopathy with vanishing white matter (VWM). VWM is one of the most prevalent childhood white matter disorders, which markedly deteriorates after inflammation or exposure to other stressors. eIF2B is a major housekeeping complex that governs the rate of global protein synthesis under normal and stress conditions. A previous study demonstrated that Eif2b5^R132H/R132H mice suffer delayed white matter development and fail to recover from cuprizone-induced demyelination, although eIF2B enzymatic activity in the mutant brain is reduced by merely 20%.

Principal Findings

Poor astrogliosis was observed in Eif2b5^R132H/R132H mice brain in response to systemic stress induced by peripheral injections of lipopolysaccharide (LPS). Even with normal rates of protein synthesis under normal conditions, primary astrocytes and microglia isolated from mutant brains fail to adequately synthesise and secrete cytokines in response to LPS treatment despite proper induction of cytokine mRNAs.

Conclusions

The mild reduction in eIF2B activity prevents the appropriate increase in translation rates upon exposure to the inflammatory stressor LPS. The data underscore the importance of fully-functional translation machinery for efficient cerebral inflammatory response upon insults. It highlights the magnitude of proficient translation rates in restoration of brain homeostasis via microglia-astrocyte crosstalk. This study is the first to suggest the involvement of microglia in the pathology of VWM disease. Importantly, it rationalises the deterioration of clinical symptoms upon exposure of VWM patients to physiological stressors and provides possible explanation for their high phenotypic variability.

Drug targeting systems for inflammatory disease: one for all, all for one

In various systemic disorders, structural changes in the microenvironment of diseased tissues enable both passive and active targeting of therapeutic agents to these tissues. This has led to a number of targeting approaches that enhance the accumulation of drugs in the target tissues, making drug targeting an attractive strategy for the treatment of various diseases. Remarkably, the strategic principles that form the basis of drug targeting are often employed for tumor targeting, while chronic inflammatory diseases appear to draw much less attention. To provide the reader with a general overview of the current status of drug targeting to inflammatory diseases, the passive and active targeting strategies that have been used for the treatment of rheumatoid arthritis (RA) and multiple sclerosis (MS) are discussed. The last part of this review addresses the dualism of platform technology-oriented ("one for all") and disease-oriented drug targeting research ("all for one"), both of which are key elements of effective drug targeting research.