Neurotrophic cross-talk between the nervous and immune systems: relevance for repair strategies in multiple sclerosis?

Uncovering the Causal Link Between Obesity-Associated Genes and Multiple Sclerosis: A Systematic Literature Review

BACKGROUND

Multiple sclerosis (MS) is a multifaceted neurodegenerative disorder influenced by genetics and lifestyle. This systematic literature review investigates the role of six obesity-associated genes, including fat mass and obesity-associated (FTO), FAS apoptosis inhibitory molecule 2 (FAIM2), Niemann-Pick disease type C1-like 1 (NPC1), glucosamine-6-phosphate deaminase 2 (GNPDA2), melanocortin-4 receptor (MC4R), and brain-derived neurotrophic factor (BDNF) in the context of MS.

METHODS

A literature search was executed using Embase, Scopus, Cochrane, Web of Science, and PubMed databases from inception to July 2024. The related keywords employed during the search process are "fas apoptotic inhibitory molecule 2," "Niemann-Pick disease type C1," "fat mass and obesity-associated," "melanocortin-4 receptor," "brain-derived neurotrophic factor," "glucosamine-6-phosphate deaminase 2," and "multiple sclerosis."

RESULTS

Out of 2108 papers, 27 were entered into the present systematic literature review. The FTO gene may affect MS susceptibility through metabolic and inflammatory pathways. FAIM2 and NPC1 genes may contribute to MS pathogenesis, though their precise roles are still being elucidated. The GNPDA2 gene may have some connections with MS but requires further clarification. MC4R has demonstrated significant neuroprotective and anti-inflammatory effects, suggesting its potential impact on MS progression. BDNF plays a complex role in neuronal survival and repair and may influence the risk of MS.

CONCLUSION

Our findings demonstrated that obesity-related genes may have a significant impact on MS risk and disease course, revealing novel insights into the genetic underpinnings of MS.

The astrocyte-produced growth factor HB-EGF limits autoimmune CNS pathology

Central nervous system (CNS)-resident cells such as microglia, oligodendrocytes and astrocytes are gaining increasing attention in respect to their contribution to CNS pathologies including multiple sclerosis (MS). Several studies have demonstrated the involvement of pro-inflammatory glial subsets in the pathogenesis and propagation of inflammatory events in MS and its animal models. However, it has only recently become clear that the underlying heterogeneity of astrocytes and microglia can not only drive inflammation, but also lead to its resolution through direct and indirect mechanisms. Failure of these tissue-protective mechanisms may potentiate disease and increase the risk of conversion to progressive stages of MS, for which currently available therapies are limited. Using proteomic analyses of cerebrospinal fluid specimens from patients with MS in combination with experimental studies, we here identify Heparin-binding EGF-like growth factor (HB-EGF) as a central mediator of tissue-protective and anti-inflammatory effects important for the recovery from acute inflammatory lesions in CNS autoimmunity. Hypoxic conditions drive the rapid upregulation of HB-EGF by astrocytes during early CNS inflammation, while pro-inflammatory conditions suppress trophic HB-EGF signaling through epigenetic modifications. Finally, we demonstrate both anti-inflammatory and tissue-protective effects of HB-EGF in a broad variety of cell types in vitro and use intranasal administration of HB-EGF in acute and post-acute stages of autoimmune neuroinflammation to attenuate disease in a preclinical mouse model of MS. Altogether, we identify astrocyte-derived HB-EGF and its epigenetic regulation as a modulator of autoimmune CNS inflammation and potential therapeutic target in MS.

Therapeutic Plasma Exchange and Multiple Sclerosis Dysregulations: Focus on the Removal of Pathogenic Circulatory Factors and Altering Nerve Growth Factor and Sphingosine-1-Phosphate Plasma Levels

Multiple sclerosis (MS) is predominantly an immune-mediated disease of the central nervous system (CNS) of unknown etiology with a possible genetic predisposition and effect of certain environmental factors. It is generally accepted that the disease begins with an autoimmune inflammatory reaction targeting oligodendrocytes followed by a rapid depletion of their regenerative capacity with subsequent permanent neurodegenerative changes and disability. Recent research highlights the central role of B lymphocytes and the corresponding IgG and IgM autoantibodies in newly forming MS lesions. Thus, their removal along with the modulation of certain bioactive molecules to improve neuroprotection using therapeutic plasma exchange (TPE) becomes of utmost importance. Recently, it has been proposed to determine the levels and precise effects of both beneficial and harmful components in the serum of MS patients undergoing TPE to serve as markers for appropriate TPE protocols. In this review we discuss some relevant examples, focusing on the removal of pathogenic circulating factors and altering the plasma levels of nerve growth factor and sphingosine-1-phosphate by TPE. Altered plasma levels of the reviewed molecular compounds in response to TPE reflect a successful reduction of the pro-inflammatory burden at the expense of an increase in anti-inflammatory potential in the circulatory and CNS compartments.

A review on plant-based remedies for the treatment of multiple sclerosis

Multiple sclerosis (MS) is a complex autoimmune disease of central nervous system, which is degenerative in nature usually appears between 20-40years of age. The exact cause of MS is still not clearly known. Loss of myelin sheath and axonal damage are the main features of MS that causes induction of inflammatory process and blocks free conduction of impulses. Till date FDA has approved 18 drugs to treat or modify MS symptoms. These medicines are disease-modifying in nature directed to prevent relapses or slow down the progression of disease. The use of the synthetic drug over an extended period causes undesirable effects that prompt us to look at Mother Nature. Complementary and alternative medicine involves the use of medicinal plants as an alternative to the existing modern medical treatment. However, modern drugs cannot be replaced completely with medicinal plants, but the two types of drugs can be used harmoniously with later one can be added as an adjuvant to the existing treatment. These medicinal plants have the potential to prevent progression and improve the symptoms of MS. Various plants such like Nigella sativa, ginger, saffron, pomegranate, curcumin, resveratrol, ginsenoside have been tested as therapeutics for many neurodegenerative diseases. The purpose of this write-up is to make information available about medicinal plants in their potential to treat or modify the symptoms of MS. Chronically ill patients tend to seek medicinal plants as they are easily available and there is a general perception about these medicines of having fewer undesirable effects.

Association between Porphyromonas Gingivalis and systemic diseases: Focus on T cells-mediated adaptive immunity

The association between periodontal disease and systemic disease has become a research hotspot. Porphyromonas gingivalis (P. gingivalis), a crucial periodontal pathogen, affects the development of systemic diseases. The pathogenicity of P. gingivalis is largely linked to interference with the host's immunity. This review aims to discover the role of P. gingivalis in the modulation of the host's adaptive immune system through a large number of virulence factors and the manipulation of cellular immunological responses (mainly mediated by T cells). These factors may affect the cause of large numbers of systemic diseases, such as atherosclerosis, hypertension, adverse pregnancy outcomes, inflammatory bowel disease, diabetes mellitus, non-alcoholic fatty liver disease, rheumatoid arthritis, and Alzheimer's disease. The point of view of adaptive immunity may provide a new idea for treating periodontitis and related systemic diseases.

Neurotrophic Factors in Experimental Cerebral Acanthamoebiasis

To date, no studies have addressed the role of neurotrophins (NTs) in Acanthamoeba spp. infections in the brain. Thus, to clarify the role of NTs in the cerebral cortex and hippocampus during experimental acanthamoebiasis in relation to the host immune status, the purpose of this study was to determine whether Acanthamoeba spp. may affect the concentration of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4) in brain structures. Our results suggest that at the beginning of infection in immunocompetent hosts, BDNF and NT-3 may reflect an endogenous attempt at neuroprotection against Acanthamoeba spp. infection. We also observed a pro-inflammatory effect of NGF during acanthamoebiasis in immunosuppressed hosts. This may provide important information for understanding the development of cerebral acanthamoebiasis related to the immunological status of the host. However, the pathogenesis of brain acanthamoebiasis is still poorly understood and documented and, therefore, requires further research.

Serum BDNF Levels in Acute Stroke: A Systematic Review and Meta-Analysis

Background and objectives: Brain-derived neurotrophic factor (BDNF) is one of the most studied neurotrophins. Low BDNF concentrations have been noted in patients with traditional cardiovascular disease risk factors and have been associated with the increased risk of stroke/transient ischemic attack (TIA). We aimed to study the correlation of BDNF serum levels with acute stroke severity and its potential role as a biomarker in predicting functional outcome. Materials and methods: We systematically searched PubMed, Web of Science, and the Cochrane database using specific keywords. The endpoints examined were the correlation of BDNF with functional outcome, the National Institute of Health stroke scale (NIHSS) measured at the acute phase, and stroke infarct volume. We also compared serum BDNF levels between stroke patients and healthy controls. Results: Twenty-six records were included from the initial 3088 identified. Twenty-five studies reported NIHSS and BDNF levels on the first day after acute stroke. Nine studies were further meta-analyzed. A statistically significant negative correlation between NIHSS and BDNF levels during the acute phase of stroke was noted (COR: −0.3013, 95%CI: (−0.4725; −0.1082), z = −3.01, p = 0.0026). We also noted that BDNF levels were significantly lower in patients with stroke compared to healthy individuals. Due to the heterogeneity of studies, we only conducted a qualitative analysis regarding serum BDNF and functional outcome, while no correlation between BDNF levels and stroke infarct volume was noted. Conclusions: We conclude that in the acute stroke phase, stroke severity is negatively correlated with BDNF levels. Concurrently, patients with acute stroke have significantly lower BDNF levels in serum compared to healthy controls. No correlations between BDNF and stroke infarct volume or functional outcome at follow-up were noted.

Clinical usefulness of brain-derived neurotrophic factor and visinin-like protein-1 in early diagnostic tests for acute stroke

OBJECTIVES

Lack of a rapid biochemical test for acute stroke is a limitation in the diagnosis and management of acute stroke. The aim of this study is to evaluate the efficacy of BDNF and VILIP-1 as diagnostic markers in acute ischemic stroke and as predictors of mortality.

METHODS

The study included 75 patients with acute ischemic stroke older than 18 years. During the same period, 28 normal controls were recruited from the hospital ED. Blood samples were collected from all patients at admission to determine the levels of VILIP-1 and BDNF.

RESULTS

The mean VILIP-1 levels in the study and control groups were 0.547 ± 0.081 and 0.515 ± 0.035 ng/mL, respectively, and the difference was not significant (p = 0.071). The mean BDNF levels in the study and control groups were 3.89 ± 2.05 ng/mL and 14.9 ± 4.7 ng/mL, respectively, and the level was significantly (p < 0.0001) lower in the stroke patients.

CONCLUSION

The BDNF level showed a significant ability to discriminate stroke and control patients but did not predict mortality. The VILIP-1 level showed insignificant ability to discriminate stroke patients and again did not predict mortality.

Lipoprotein Lipase Is a Feature of Alternatively-Activated Microglia and May Facilitate Lipid Uptake in the CNS During Demyelination

Severe demyelinating disorders of the central nervous system (CNS) such as multiple sclerosis (MS), can be devastating for many young lives. To date, the factors resulting in poor remyelination and repair are not well understood, and reparative therapies that benefit MS patients have yet to be developed. We have previously shown that the activity and abundance of Lipoprotein Lipase (LPL)—the rate-limiting enzyme in the hydrolysis of triglyceride-rich lipoproteins—is increased in Schwann cells and macrophages following nerve crush injury in the peripheral nervous system (PNS), suggesting that LPL may help scavenge myelin-derived lipids. We hypothesized that LPL may play a similar role in the CNS. To test this, mice were immunized with MOG_35–55 peptide to induce experimental allergic encephalomyelitis (EAE). LPL activity was increased (p < 0.05) in the brain at 30 days post-injection, coinciding with partial remission of clinical symptoms. Furthermore, LPL abundance and activity was up-regulated (p < 0.05) at the transition between de- and re-myelination in lysolecithin-treated ex vivo cerebellar slices. Since microglia are the key immune effector cells of the CNS we determined the role of LPL in microglia. Lipid uptake was decreased (p < 0.001) in LPL-deficient BV-2 microglial cells compared to WT. In addition, LPL-deficient cells showed dramatically reduced expression of anti-inflammatory markers, YM1 (−22 fold, p < 0.001), and arginase 1 (Arg1; −265 fold, p < 0.001) and increased expression of pro-inflammatory markers, such as iNOS compared to WT cells (+53 fold, p < 0.001). This suggests that LPL is a feature of reparative microglia, further supported by the metabolic and inflammatory profile of LPL-deficient microglia. Taken together, our data strongly suggest that LPL expression is a novel feature of a microglial phenotype that supports remyelination and repair through the clearance of lipid debris. This mechanism may be exploited to develop future reparative therapies for MS and primary neurodegenerative disorders (Alzheimer’s disease (AD) and Parkinson’s disease).

Neuregulin1 modulation of experimental autoimmune encephalomyelitis (EAE)

Neuregulin1 (NRG1) is a differentiation factor that regulates glial development, survival, synaptogenesis, axoglial interactions, and microglial activation. We previously reported that a targeted NRG1 antagonist (HBD-S-H4) given intrathecally, reduces inflammatory microglial activation in a spinal cord pain model and a neurodegenerative disease mouse model in vivo, suggesting that it may have effects in neuroninflammatory and neuronal disorders. We hypothesized that expression of HBD-S-H4 in the central nervous system (CNS) could reduce disease severity in experimental autoimmune encephalomyelitis (EAE), a widely used animal model for multiple sclerosis (MS). In the present study, we generated tetO-HBD-S-H4, a single transgenic (Tg) mouse line in, which the fusion protein in expressed in the brain, resulting in reduction of disease severity in both male and female mice when compared to sex- and age-matched wild type littermates. We also generated GFAP-tTA:tetO-HBD-S-H4 double Tg mice, which express this fusion protein in the brain and the spinal cord, they displayed sex differences in the reduction of disease severity. In healthy mice, expression of HBD-S-H4 in the CNS does not result in any significant neurological or other overt phenotypes. In myelin oligodendrocyte glycoprotein (MOG)-induced EAE, female double Tg mice show delayed disease onset and reduced disease severity compared to male double Tg as well as wild type littermates. In male double Tg mice, the levels of HBD-S-H4 gene expression negatively correlates with disease severity and increased microglia associated genes' expression. In conclusion, expression of neuregulin antagonist in the brain and spinal cord protects females but not males, suggesting a complex interplay between NRG1 and sex difference in EAE that may be associated with microglia-mediated inflammation. This study provides important information for understanding the heterogeneity of disease pathology and the therapeutic potential of targeting microglial activation in male and female MS patients.

Progressive multiple sclerosis: from pathogenic mechanisms to treatment

During the past decades, better understanding of relapsing-remitting multiple sclerosis disease mechanisms have led to the development of several disease-modifying therapies, reducing relapse rates and severity, through immune system modulation or suppression. In contrast, current therapeutic options for progressive multiple sclerosis remain comparatively disappointing and challenging. One possible explanation is a lack of understanding of pathogenic mechanisms driving progressive multiple sclerosis. Furthermore, diagnosis is usually retrospective, based on history of gradual neurological worsening with or without occasional relapses, minor remissions or plateaus. In addition, imaging methods as well as biomarkers are not well established. Magnetic resonance imaging studies in progressive multiple sclerosis show decreased blood-brain barrier permeability, probably reflecting compartmentalization of inflammation behind a relatively intact blood-brain barrier. Interestingly, a spectrum of inflammatory cell types infiltrates the leptomeninges during subpial cortical demyelination. Indeed, recent magnetic resonance imaging studies show leptomeningeal contrast enhancement in subjects with progressive multiple sclerosis, possibly representing an in vivo marker of inflammation associated to subpial demyelination. Treatments for progressive disease depend on underlying mechanisms causing central nervous system damage. Immunity sheltered behind an intact blood-brain barrier, energy failure, and membrane channel dysfunction may be key processes in progressive disease. Interfering with these mechanisms may provide neuroprotection and prevent disability progression, while potentially restoring activity and conduction along damaged axons by repairing myelin. Although most previous clinical trials in progressive multiple sclerosis have yielded disappointing results, important lessons have been learnt, improving the design of novel ones. This review discusses mechanisms involved in progressive multiple sclerosis, correlations between histopathology and magnetic resonance imaging studies, along with possible new therapeutic approaches.

Progranulin expression in brain tissue and cerebrospinal fluid levels in multiple sclerosis

Background: Progranulin (PGRN) is a fundamental neurotrophic factor, and is also involved in inflammation and wound repair. PGRN may have pro- or anti-inflammatory properties, depending upon proteolysis of the anti-inflammatory parent PGRN protein and the generation of pro-inflammatory granulin peptides.

Objectives: Our objectives were as follows: (1) to evaluate the presence and distribution of PGRN in multiple sclerosis (MS) brain tissue, correlating it with demyelination and inflammation; (2) to evaluate cerebrospinal fluid (CSF) PGRN concentrations in patients with MS and controls, in relationship to the clinical features of the disease.

Methods: Our study involved the following: (1) neuropathological study of PGRN on post-mortem tissue of 19 MS and six control brains; (2) evaluation of PGRN CSF concentration in 40 MS patients, 15 non-inflammatory controls and five inflammatory controls (viral encephalitis).

Results: In active demyelinating lesions, PGRN was expressed on macrophages/microglia. In the normal-appearing white matter (NAWM), expression of PGRN was observed on activated microglia. PGRN was expressed by neurons and microglia in cortical lesions and in normal-appearing cortex. No expression of PGRN was observed in controls, except on neurons. PGRN CSF concentrations were significantly higher in patients with relapsing–remitting MS during relapses and in progressive MS patients, compared with relapsing–remitting MS patients during remissions and with non-inflammatory controls.

Conclusions: PGRN is strongly expressed in MS brains, by macrophages/microglia in active lesions, and by activated microglia in the NAWM; PGRN CSF concentrations in MS are correspondingly increased in conditions of enhanced macrophage/microglia activation, such as during relapses and in progressive MS.

Blood Biomarkers as Outcome Measures in Inflammatory Neurologic Diseases

Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system. Only a few biomarkers are available in MS clinical practice, such as cerebrospinal fluid oligoclonal bands and immunoglobulin index, serum anti-aquaporin 4 antibodies, and serum anti-John Cunningham virus antibodies. Thus, there is a significant unmet need for biomarkers to assess prognosis, response to therapy, or potential treatment complications. Here we describe emerging biomarkers that are in development, focusing on those from peripheral blood. There are several limitations in the process of discovery and validation of a good biomarker, such as the pathophysiological complexity of MS and the technical difficulties in globally standardizing methods for sampling, processing, and conserving biological specimens. In spite of these limitations, ongoing international collaborations allow the exploration of many interesting molecules and markers to validate diagnostic, prognostic, and therapeutic-response biomarkers.

Porphyromonas gingivalis suppresses adaptive immunity in periodontitis, atherosclerosis, and Alzheimer's disease

Porphyromonas gingivalis, a keystone pathogen in chronic periodontitis, has been found to associate with remote body organ inflammatory pathologies, including atherosclerosis and Alzheimer’s disease (AD). Although P. gingivalis has a plethora of virulence factors, much of its pathogenicity is surprisingly related to the overall immunosuppression of the host. This review focuses on P. gingivalis aiding suppression of the host’s adaptive immune system involving manipulation of cellular immunological responses, specifically T cells and B cells in periodontitis and related conditions. In periodontitis, this bacterium inhibits the synthesis of IL-2 and increases humoral responses. This reduces the inflammatory responses related to T- and B-cell activation, and subsequent IFN-γ secretion by a subset of T cells. The T cells further suppress upregulation of programmed cell death-1 (PD-1)-receptor on CD⁺cells and its ligand PD-L1 on CD11b⁺-subset of T cells. IL-2 downregulates genes regulated by immune response and induces a cytokine pattern in which the Th17 lineage is favored, thereby modulating the Th17/T-regulatory cell (Treg) imbalance. The suppression of IFN-γ-stimulated release of interferon-inducible protein-10 (IP-10) chemokine ligands [ITAC (CXCL11) and Mig (CXCL9)] by P. gingivalis capsular serotypes triggers distinct T cell responses and contributes to local immune evasion by release of its outer membrane vesicles. In atherosclerosis, P. gingivalis reduces Tregs, transforms growth factor beta-1 (TGFβ-1), and causes imbalance in the Th17 lineage of the Treg population. In AD, P. gingivalis may affect the blood–brain barrier permeability and inhibit local IFN-γ response by preventing entry of immune cells into the brain. The scarcity of adaptive immune cells in AD neuropathology implies P. gingivalis infection of the brain likely causing impaired clearance of insoluble amyloid and inducing immunosuppression. By the effective manipulation of the armory of adaptive immune suppression through a plethora of virulence factors, P. gingivalis may act as a keystone organism in periodontitis and in related systemic diseases and other remote body inflammatory pathologies.

Preventing the BDNF and NGF loss involved in the effects of cornel iridoid glycoside on attenuation of experimental autoimmune encephalomyelitis in mice

The present study was designed to investigate the beneficial effects of cornel iridoid glycoside (CIG), a main component extract from Cornus officinalis, on neurotrophin expression in mouse experimental autoimmune encephalomyelitis (EAE), a classical model of multiple sclerosis (MS). After EAE initiation, CIG was intragastrically administered daily for 32 days and reduced disease severity. Histopathological staining and western blotting both showed that CIG could prevent brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) loss in the spinal cord of EAE mice. In conclusion, our findings indicated that CIG treatment suppressed disease severity of EAE partially through blocking downregulation of neurotrophic factor expression such as BDNF and NGF, suggesting that CIG may have beneficial effects for the treatment of demyelinating diseases such as MS.

VGF expression by T lymphocytes in patients with Alzheimer's disease

Secretion of VGF is increased in cerebrospinal fluid and blood in neurodegenerative disorders like Alzheimer's disease (AD) and VGF is a potential biomarker for these disorders. We have shown that VGF is expressed in peripheral T cells and is correlated with T cell survival and cytokine secretion. The frequency of VGF+CD3+ T cells increases with normal aging. We found an increased number of VGF-expressing T cells in patients with AD compared to aged healthy controls, which was associated with enhanced HbA1c levels in blood. Upon treatment with rivastigmine, T cell proliferation and VGF expression in AD patients decreased to the level found in controls. Moreover, rapamycin treatment in vitro reduced the number of VGF+CD3+ cells in AD patients to control levels.

Low Concentration of BDNF in the Acute Phase of Ischemic Stroke as a Factor in Poor Prognosis in Terms of Functional Status of Patients

BACKGROUND According to recent studies, brain-derived neurotrophic factor (BDNF) probably plays a role in development of cerebral ischemia and can be significant for the prognosis of improved mobility after stroke. The aim of this prospective study was to evaluate the blood concentration of BDNF during the 1st day of first-ever ischemic stroke and find a potential association between BDNF concentration and the neurological status in the acute period, as well as between BDNF and the functional status in the sub-acute phase of stroke. MATERIAL AND METHODS The prospective study involved 87 patients aged 39-99 years (42 women, 45 men) with first-in-life complete ischemic stroke. All study subjects underwent analysis as follows: BDNF blood concentration and neurological status according to NIHSS on the 1st day of stroke, comorbidities, etiological type of ischemic stroke by ASCOD, and functional status on the 14th and 90th day after the onset according to mRankin scale. RESULTS Mean concentration of BDNF in the study group was 9.96 ng/mL±5.21, median 10.39 ng/mL. Patients aged ≤65 years (25 individuals) had a significantly higher mean concentration of BDNF (11.94 ng/mL±4.46; median 12.34 ng/mL) than the older subjects (62 individuals) with a mean concentration of 9.17 ng/mL±5.32 (median 8.66 ng/mL). The mean score by mRankin scale on the 90th day was significantly higher among patients with lower concentrations of BDNF on the 1st day of stroke, which reflects their poorer functional status. The functional status on the 90th day was significantly worse (3-6 points by Rankin scale) in patients who had BDNF below the mean value in the acute phase of stroke. The independent factors for poor functional status of patients on the 90th day after stroke were a score >4 points by NIHSS (RR 1.14; 95% CI: 1.00-1.31; p=0.027) and the concentration of BDNF below the mean value (assessed on the 1st day of stroke) (RR 14.49; CI 4.60-45.45; p=0.000). CONCLUSIONS The neurological status and concentration of BDNF on the 1st day of ischemic stroke are independent prognostic factors in medium-term observation. Reduction in the concentration of BDNF in the acute phase of stroke is a factor for poor prognosis in terms of the functional status of patients on the 90th day after onset.

Progranulin genetic polymorphisms influence progression of disability and relapse recovery in multiple sclerosis

BACKGROUND

Progranulin (GRN) is a multifunctional protein involved in inflammation and repair, and also a neurotrophic factor critical for neuronal survival. Progranulin is strongly expressed in multiple sclerosis (MS) brains by macrophages and microglia.

METHODS

In this study we evaluated GRN genetic variability in 400 MS patients, in correlation with clinical variables such as disease severity and relapse recovery. We also evaluated serum progranulin levels in the different groups of GRN variants carriers.

RESULTS

We found that incomplete recovery after a relapse is correlated with an increased frequency of the rs9897526 A allele (odds ratio (OR) 4.367, p = 0.005). A more severe disease course (Multiple Sclerosis Severity Score > 5) is correlated with an increased frequency of the rs9897526 A allele (OR 1.886, p = 0.002) and of the rs5848 T allele (OR 1.580, p = 0.019). Carriers of the variants associated with a more severe disease course (rs9897526 A, rs5848 T) have significantly lower levels of circulating progranulin (80.5 ± 9.1 ng/mL vs. 165.7 ng/mL, p = 0.01).

CONCLUSION

GRN genetic polymorphisms likely influence disease course and relapse recovery in MS.

The usefulness of immunotherapy in pediatric neurodegenerative disorders: A systematic review of literature data

Immunotherapeutic strategies to treat neurodegenerative disorders have inspired the scientific community. The aim of our review is to address the translational aspects of neuroimmunology to describe the efficacy of immunotherapy in the treatment of pediatric neurodegenerative disorders. In the studies we analyzed IVIG were found to be efficient in the treatment of post-streptococcal neurodegenerative disorders, even if in PANDAS, plasma-exchange (PE) showed a higher efficiency. IVIG were also successfully used in ADEM and Guillan-Barré syndrome. In Sydenham Chorea the use of methylprednisolone was found in most cases as efficient as IVIG, while in Tourette's Syndrome, Colecoxib was successfully used in one patient. Pediatric Multiple Sclerosis seems to respond better to immunosuppressant agents (Mitoxantrone, Cyclophosphamide, Natalizumab), as well as Neuromyelitis optica (Rituximab, Mycofenolate). The importance of this review relies in the attempt to draw standardized guidelines for immunotherapy in pediatric neurodegeneratve disorders.

Complexity of trophic factor signaling in experimental autoimmune encephalomyelitis: differential expression of neurotrophic and gliotrophic factors

Soluble factors that promote survival and differentiation of glia and neurons during development are likely to play key roles in neurodegeneration and demyelinating diseases such as multiple sclerosis (MS) and have the potential to be important therapeutic targets. We examined the effect of TrkB signaling and the expression patterns of neurotrophic and gliotrophic factors in the mouse brain in MOG-induced experimental allergic encephalomyelitis (EAE). With induction of mild disease, TrkB heterozygous mice were more severely affected compared to their wild type littermates. However, with more potent disease induction, TrkB heterozygotes fared similar to their wild type littermates, suggesting complex modulatory roles for TrkB signaling. One possible explanation for this difference is that the expression patterns of neurotrophic factors correlate with disease severity in individual mice with mild disease, but not in more severe disease. With the less potent induction in C57BL/6 mice, we found that BDNF was consistently increased at EAE onset, while the soluble gliotrophic factor neuregulin (NRG1) was increased only in the chronic phase of the disease. Treatment of these animals with glatiramer acetate (GA) to decrease disease severity resulted in lower levels of both BDNF and NRG1 expression in some mice at 35days after immunization compared to those in untreated EAE mice, but had no direct effect on these factors in the absence of EAE. Our results suggest a complex interplay between neurotrophic and gliotrophic factors in EAE that is dependent on disease stage and severity. While signaling by BDNF through TrkB is protective in mild disease, this effect was not seen in more severe disease. The late induction of NRG1 in the chronic stage of disease could also worsen disease severity through its known ability to activate microglial, inflammatory pathways. While complex, these studies begin to define underlying axoglial trophic activities that are likely involved in both disease pathogenesis and repair.

TH17-Driven Inflammation is Present in All Clinical Forms of Multiple Sclerosis; Disease Quiescence is Associated with Gata3-Expressing Cells

Multiple Sclerosis (MS) presents in a variety of clinical forms associated with a diverse grade of neurological impairment, different prognosis and, possibly, multiple pathogenic mechanisms. Thus, whereas relapsing-remitting (RR) MS appears to be largely driven by inflammatory processes, neurodegeneration, partially independent from inflammation, drives primary progressive (PP) and secondary progressive (SP) MS. An extensive analysis of neuroinflammation in the different forms of MS was performed by evaluating immunophenotypic and functional parameters in MBP-stimulated T lymphocytes of 103 MS patients (26 benign (BE) MS, 30 RRMS, 33 SPMS and 14 PPMS) and 40 healthy controls (HC). Results showed that: i) IL-17-producing and RORC/γt-expressing CD4+ T cells (TH17 lymphocytes), as well as IL-6 expressing CD14+ cell were augmented in all patients; ii) IL-22-expressing cells were increased in all forms of MS with the exception of PPMS; iii) TGF-β-expressing B cells were increased only in RRMS; and iv) GATA3-, NFATc-1, IL-13-, and IL-25-expressing cells (TH2 lymphocytes) were augmented in RRMS and BEMS patients alone. Data herein indicate a pivotal pathogenic role of TH17-driven inflammation in all clinical forms of MS and suggest that control over disease (RRMS and BEMS) is associated not with lack of inflammation per se, but rather with the activation of immune-mediated anti-inflammatory mechanisms. These results could help the design of novel diagnostic and therapeutic approaches.

The role of neurotrophins in multiple sclerosis-pathological and clinical implications

Multiple sclerosis (MS) is a chronic inflammatory demyelinating and neurodegenerative disease of the central nervous system (CNS) with unknown etiology. It was recently suggested that autoimmunity, which had long been considered to be destructive in MS, might also play a protective role in the CNS of MS patients. Neurotrophins are polypeptides belonging to the neurotrophic factor family. While neurotrophins mediate cell survival and proliferation in the nervous system, they are also expressed within peripheral blood mononuclear cells fraction (PBMCs) of immunological system. In MS additional neurotrophic support from PBMCs might compensate relative neurotrophins deficiency in the damaged CNS tissue that needs to be repaired. Failure to produce the adequate neurotrophins concentrations might result in decreased protection of the CNS, consequently leading to increased atrophy, which is the main determinant of MS patients' end-point disability. There are several lines of evidence, both from clinical research and animal models, suggesting that neurotrophins play a pivotal role in neuroprotective and neuroregenerative processes that are often defective in the course of MS. It seems that neuroprotective strategies might be used as potentially valuable add-on therapies, alongside traditional immunomodulatory treatment in multiple sclerosis.

Immune response during interferon beta-1b treatment in patients with multiple sclerosis who experienced relapses and those who were relapse-free in the START study

We measured immune markers in subjects with multiple sclerosis (MS) treated with IFNβ-1b for 12 months. IL-17 levels were significantly higher at Month 6 (p=0.036) in relapsing subjects while BDNF levels were significantly higher at Month 3 (p=0.028) in relapse-free subjects. Change from baseline in IL-4 levels inversely correlated with disability score whereas change from baseline in IL-10/IFN-gamma ratio inversely correlated with occurrence of relapses. CXCR3+CD8+ T-cells tended to be higher but declined with treatment in relapse-free compared with relapsing subjects. Findings show the potential of cytokine and neurotrophic factors as biomarkers of clinical response to IFNβ-1b.

Altered serum content of brain-derived neurotrophic factor isoforms in multiple sclerosis

In multiple sclerosis (MS), brain-derived neurotrophic factor (BDNF) provides neuroprotection, but can also promote disease through the maintenance of autoreactive T cells. One aspect that has not been explored yet in MS is related to the opposite functions of BDNF protein isoforms consisting of the pro-BDNF precursor, which has pro-apoptotic effects, and two proteolytic isoforms, the mature BDNF with pro-survival effects and truncated BDNF, with unknown functions. Using ELISA and semi-quantitative Western-blot we determined the relative serum levels of BDNF isoforms in 20 relapsing-remitting MS patients without any disease modifying therapy and 20 age and gender-matched healthy controls and searched for clinical correlates. Total serum BDNF was lower in MS than in HC. We demonstrate that the capture and detection antibodies of the ELISA kit from Promega are able to recognize all three isoforms but with different efficiency. Using Western-blot analysis, we show that the percentage of serum mature BDNF and pro-BDNF with respect to total serum BDNF was significantly decreased, while truncated BDNF was increased. No correlation between BDNF isoform percentage and clinical or demographic features was found. Serum Fas (sFas) was increased. These results support and expand the current hypothesis on the role of BDNF in multiple sclerosis, in that low pro-BDNF and high sFas might result in a failure to limit autoreactive T cells by apoptotic deletion and decreased mature BDNF may not provide enough neuroprotection, while truncated BDNF percent increase could be a compensatory mechanism. Hence, future studies on MS should take into account BDNF proteolytic processing.

Neuroprotective potential beyond immunoregulation of helminth infection as a therapeutic target in multiple sclerosis

Multiple sclerosis (MS) is a common disabling autoimmune disease in young adults which does not have an effective treatment. The prevalence of immune-mediated diseases is higher in developed countries with hygienic environments, suggesting that helminthic infection may protect from autoimmune diseases. Previously, we reported that soluble egg antigens (SEA) from Schistosoma japonicum suppressed experimental autoimmune encephalomyelitis (EAE), an animal model of MS, through up-regulating T helper-2 (Th2) immune responses in both the peripheral and central target organs. Neurotrophins (NTs) are not exclusive to the nervous system. While immune cells, especially Th2 cells, can produce and secrete a variety of NTs resulting in neuroprotective immunity. NTs can also modulate immune responses by augmenting Th2 responses and downregulating Th1 responses. Interestingly, nerve growth factor (NGF) has been found in liver granulomas of Schistosoma mansoni-infected mice. Moreover, in the central nervous system of chronic schistosomiasis, NGF is increased. A hypothesis is hereby proposed - SEA derived from S. japonicum bears neuroprotective properties beyond its immunomodulatory effects. SEA can induce the expression of NTs, which in turn augment Th2 immune responses induced by SEA; whereby a positive regulatory circuit between Th2 responses and NTs comes into being.

Immune cell NT-3 expression is associated with brain atrophy in multiple sclerosis patients

While neurotrophins mediate cell survival and proliferation in the nervous system, they are also expressed within peripheral blood mononuclear cells (PBMCs) of the immunological system. In multiple sclerosis (MS) neurotrophins released from PBMCs might play a neuroprotective role, delaying neurodegeneration within central nervous system. We aimed for identifying the link between neurotrophins' PBMCs expression and brain atrophy markers in relapsing-remitting MS (RRMS) patients. We have found that neurotrophin-3 PBMCs concentration is strongly correlated with brain-parenchymal fraction and corpus callosum cross-sectional area, which are well-established brain atrophy measures. Thus, PBMC-derived neurotrophin-3 might exert a direct or indirect neuroprotective effect in MS.

Brain-derived neurotrophic factor plasma variation during the different phases of the menstrual cycle in women with premenstrual syndrome

Premenstrual syndrome (PMS) is characterized by a cluster of psychological and somatic symptoms that begin during the late luteal phase of the menstrual cycle and disappear after the onset of menses. Since PMS might be caused by an alteration in the cyclical hormonal modifications and ovarian steroids are directly involved in the regulation of mood, affective and cognitive functions and influence neurotrophins expression, in particular the brain-derived neurotrophic factor (BDNF), we aimed to evaluate whether plasma BDNF levels in women with PMS differ from those of normally menstruating women without PMS. Sixty-two women were divided into two groups: one group of women (n=35) with PMS and one group (n=27) composed by normally menstruating women. Plasma samples were collected at day 7 (follicular phase) and day 21 (luteal phase) of the menstrual cycle. Plasma BDNF of the control group significantly increased (p<0.001) from the follicular phase (402.90±74.41pg/ml) to the luteal phase (1098.79±146.49pg/ml). On the other hand, in the PMS group plasma BDNF levels significantly decreased (p<0.001) from the follicular phase (412.45±78.35pg/ml) to the luteal phase (233.03±75.46pg/ml) Luteal BDNF levels of the PMS women were significantly lower than those of the control group (p<0.001). In women with PMS, plasma BDNF followed a decreasing trend during the ovarian cycle, in opposition to the increasing trend observed in women without PMS. The lower luteal BDNF levels of the PMS women might be a consequence of an altered hormonal response and might play a role in the onset of the symptoms PMS related.

Inflammation in neurodegenerative diseases

Neurodegeneration, the slow and progressive dysfunction and loss of neurons and axons in the central nervous system, is the primary pathological feature of acute and chronic neurodegenerative conditions such as Alzheimer's disease and Parkinson's disease, neurotropic viral infections, stroke, paraneoplastic disorders, traumatic brain injury and multiple sclerosis. Despite different triggering events, a common feature is chronic immune activation, in particular of microglia, the resident macrophages of the central nervous system. Apart from the pathogenic role of immune responses, emerging evidence indicates that immune responses are also critical for neuroregeneration. Here, we review the impact of innate and adaptive immune responses on the central nervous system in autoimmune, viral and other neurodegenerative disorders, and discuss their contribution to either damage or repair. We also discuss potential therapies aimed at the immune responses within the central nervous system. A better understanding of the interaction between the immune and nervous systems will be crucial to either target pathogenic responses, or augment the beneficial effects of immune responses as a strategy to intervene in chronic neurodegenerative diseases.

The role of neurotrophic factors in the pathology and treatment of multiple sclerosis

Multiple sclerosis (MS) is a chronic demyelinating disease of primary autoimmune origin with essential component of subsequent axonal degeneration. It has been found that inflammatory cells crucial for MS pathogenesis are able to release neurotrophic factors (NFs). Thus the concept of neuroprotective effect of inflammation has arisen. Over recent years, increasing number of studies has revealed that NFs play an important role in MS and its animal model - experimental autoimmune encephalomyelitis (EAE). In the current review the evidence for the role of NFs in MS pathogenesis the same as their remarkable potential in MS therapy is presented.

A longitudinal observation of brain-derived neurotrophic factor mRNA levels in patients with relapsing-remitting multiple sclerosis

This report is part of a 2-year study assessing the functional effect of Brain-Derived Neurotrophic Factor (BDNF) and its Val66Met polymorphism on a selected population of Relapsing-Remitting Multiple Sclerosis (RRMS) patients from Southern Italy. For this purpose, we measured the peripheral BDNF expression in RRMS patients compared to healthy controls. The influence of concomitant IFNbeta therapy was also evaluated. Thirty-six inactive RRMS patients and 37 healthy controls were genotyped for BDNF Val66Met, and total RNA was extracted at time-points 0-24 months. The BDNF level was quantified by ABI Prism 7900 HT Sequence Detection System, and its relative expression was calculated by the comparative method of 2(-DeltaDeltaCt). At baseline and after 24 months, the BDNF levels of RRMS patients resulted significantly higher than controls (p=0.001), independently of the concomitant IFNbeta treatment; no correlations were found with the investigated clinical and MRI features of MS. Otherwise, carriers of the Met-allele showed significantly higher levels of BDNF in RRMS patients than healthy controls (p=0.005). These data was replicated after a 24-month interval. The present study confirms the increased levels of peripheral BDNF levels in RRMS, even during the inactive phase of the disease. Although with caution due to the small sample size, it also underscores the potential role of the Val66Met polymorphism on the peripheral BDNF expression in RRMS. Functional studies are needed to better clarify this issue.

Immune modulation and increased neurotrophic factor production in multiple sclerosis patients treated with testosterone

BACKGROUND

Multiple sclerosis is a chronic inflammatory disease of the central nervous system with a pronounced neurodegenerative component. It has been suggested that novel treatment options are needed that target both aspects of the disease. Evidence from basic and clinical studies suggests that testosterone has an immunomodulatory as well as a potential neuroprotective effect that could be beneficial in MS.

METHODS

Ten male MS patients were treated with 10 g of gel containing 100 mg of testosterone in a cross-over design (6 month observation period followed by 12 months of treatment). Blood samples were obtained at three-month intervals during the observation and the treatment period. Isolated blood peripheral mononuclear cells (PBMCs) were used to examine lymphocyte subpopulation composition by flow cytometry and ex vivo protein production of cytokines (IL-2, IFNgamma, TNFalpha, IL-17, IL-10, IL-12p40, TGFbeta1) and growth factors (brain-derived neurotrophic factor BDNF, platelet-derived growth factor PDGF-BB, nerve growth factor NGF, and ciliary neurotrophic factor CNTF). Delayed type hypersensitivity (DTH) skin recall tests were obtained before and during treatment as an in vivo functional immune measure.

RESULTS

Testosterone treatment significantly reduced DTH recall responses and induced a shift in peripheral lymphocyte composition by decreasing CD4+ T cell percentage and increasing NK cells. In addition, PBMC production of IL-2 was significantly decreased while TGFbeta1 production was increased. Furthermore, PBMCs obtained during the treatment period produced significantly more BDNF and PDGF-BB.

CONCLUSION

These results are consistent with an immunomodulatory effect of testosterone treatment in MS. In addition, increased production of BDNF and PDGF-BB suggests a potential neuroprotective effect.

TRIAL REGISTRATION

NCT00405353 http://www.clinicaltrials.gov.

Interferon-beta induces brain-derived neurotrophic factor in peripheral blood mononuclear cells of multiple sclerosis patients

Interferon-beta (IFN-beta) achieves its beneficial effect on multiple sclerosis (MS) via anti-inflammatory properties. In this study, we assessed the expression of the brain-derived neurotrophic factor (BDNF) in peripheral blood mononuclear cells (PBMC) from relapsing-remitting multiple sclerosis (RRMS) patients treated or not with IFN-beta. Intracellular BDNF was measured by Western blot and ELISA and compared with serum BDNF. We found higher levels of BDNF in PBMC of IFN-beta-treated versus non-treated patients, whereas serum levels of BDNF were similar. We hypothesize that the increased intracellular BDNF secondary to IFN-beta is not released in the periphery. This release is probably not tissue specific but in MS patients, BDNF could be specifically delivered by PBMC at the site of re-activation, i.e. within the central nervous system.

Myelin repair strategies: a cellular view

PURPOSE OF REVIEW

The development of successful myelin repair strategies depends on the detailed knowledge of the cellular and molecular processes underlying demyelination and remyelination in the central nervous system of animal models and in patients with multiple sclerosis (MS). Based on the complexity of the demyelination and remyelination processes, it should be expected that effective therapeutic approaches will require a combination of strategies for immunomodulation, neuroprotection, and myelin replacement. This brief review highlights recent cellular and molecular findings and indicates that future therapeutic strategies to enhance remyelination may also require combinatorial treatment to accomplish.

RECENT FINDINGS

The relapsing-remitting course of some forms of multiple sclerosis has typically fueled hope for effective repair of multiple sclerosis lesions, if demyelinating activity could be attenuated. Recent findings support the potential of endogenous neural stem cells and progenitor cells to generate remyelinating oligodendrocytes. Importantly, interactions with viable axons and supportive astrocytic responses are required for endogenous immature cells to fulfill their potential remyelinating capacity.

SUMMARY

The research described here will help in identifying the major obstacles to effective remyelination and potential therapeutic targets to guide development of comprehensive approaches for testing in animal models and eventual treatment of patients with multiple sclerosis.