Is there a role for neurotrophins in the pathology of multiple sclerosis?

The effect of combined functional training on BDNF, IGF-1, and their association with health-related fitness in the multiple sclerosis women

OBJECTIVE

Exercise-induced changes in the neurotrophic factors and the physical function are essential for the rehabilitation of the multiple sclerosis (MS) persons. The aim of this study was investigating of effectiveness of the combined functional training (CFT) on brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), and their association with health-related fitness in the MS women.

DESIGN

Twenty women with relapsing-remitting MS randomly assigned to CFT and control (CON) groups. The CFT consisted of 8 weeks (3 days per week) rhythmic aerobic exercise, TRX suspension training, elastic band training, and bodyweight training. BDNF, IGF-1, and health-related fitness components were assessed before and after the intervention.

RESULTS

There was no significant difference in BDNF level between the CFT and the CON group. In contrast, IGF-1, walking speed, and strength of the right- and left-hand was significantly increased in the CFT compared with the CON group. Furthermore, there was a significant and positive correlation between IGF-1 and some fitness components.

CONCLUSIONS

The findings indicated that CFT might a useful training mode in the rehabilitation of the MS women. CFT improved IGF-1 level that is a neuroprotective agent in MS. Positive and significant association between IGF-1 and some health-related fitness components indicates of the importance of IGF-1 in the rehabilitation of the MS persons than BDNF.

[Brain-derived neurotrophic factor in multiple sclerosis]

The review presents data on brain-derived neurotrophic factor (BDNF), its structure and functions, the effect on the pathogenesis of experimental autoimmune encephalomyelitis and multiple sclerosis (MS). The correlation of BDNF level with clinical manifestations of MS and the changes of its level during disease-modifying therapy is considered.

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.

Cognitive deficit is related to immune-cell beta-NGF in multiple sclerosis patients

OBJECTIVES

Multiple sclerosis (MS) is a chronic inflammatory demyelinating and neurodegenerative disease of the central nervous system (CNS), causing cognitive impairment in 45-65% of patients. Beta-NGF facilitates proper cholinergic transmission in the healthy CNS. In MS-damaged tissue there is a relative deficit of neurotrophins that might be compensated by peripheral blood mononuclear cells (PBMCs) synthesis. Our aim was to evaluate the relationship between PBMCs neurotrophins' expression and cognitive performance in relapsing-remitting MS (RRMS) patients.

PATIENTS AND METHODS

Beta-NGF, NT-3 and NT-4/5 levels were measured in sera and in PBMCs by ELISA method in 41 RRMS patients in remission. All patients underwent neuropsychological assessment with a battery of 10 tests evaluating a wide range of cognitive functions.

RESULTS

PBMCs beta-NGF concentration correlated significantly with spontaneous word list generation test (Pearson R=0.37, p=0.02) and 15-Word List Recall Test results (Pearson R=0.40, p<0.00). Both tests assessing semantic memory correlated significantly with the cognitive composite score, defined as a number of tests in which patients performed below group median for the given test.

CONCLUSIONS

In RRMS beta-NGF is strongly linked to cognitive performance, which makes it an attractive therapeutic target. It might play a neuroprotective role in MS, especially in the cognitive domain.

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.

Altered production of brain-derived neurotrophic factor by peripheral blood immune cells in multiple sclerosis

Background: Within multiple sclerosis lesions, brain-derived neurotrophic factor is detected in neurons and immunocytes.

Objective: To clarify brain-derived neurotrophic factor production by peripheral blood immunocytes and its relationship with clinical parameters in multiple sclerosis.

Methods: Serum brain-derived neurotrophic factor levels were measured by conventional enzyme-linked immunosorbent assay while brain-derived neurotrophic factor production by immunocytes was determined by an in situ enzyme-linked immunosorbent assay in 74 multiple sclerosis patients, 32 healthy controls, and 86 patients with other neurological diseases. The tyrosine kinase receptor TrkB expression level in peripheral blood mononuclear cells was measured by real-time polymerase chain reaction.

Results: Multiple sclerosis patients showed significantly higher serum brain-derived neurotrophic factor levels than healthy controls and patients with other neurological diseases. Multiple sclerosis patients with high brain-derived neurotrophic factor levels were younger, and showed fewer relapse numbers than those with low brain-derived neurotrophic factor levels. Brain-derived neurotrophic factor production by T cells increased with age in healthy controls, but not in multiple sclerosis patients. Interferon beta induced a significant increase in serum brain-derived neurotrophic factor levels. Brain-derived neurotrophic factor production from T cells and TrkB expression levels in peripheral blood mononuclear cells were significantly enhanced in interferon beta-treated multiple sclerosis patients compared with untreated ones. Conclusions: A high brain-derived neurotrophic factor level is related to early mild disease in young multiple sclerosis patients. Interferon beta potentiates brain-derived neurotrophic factor production and brain-derived neurotrophic factor receptor expression in peripheral blood mononuclear cells, which may act beneficially.

Neuro-immune crosstalk in CNS diseases

Immune cells infiltrate the central nervous system (CNS) in many neurological diseases, with a primary or secondary inflammatory component. In the CNS, immune cells employ shared mediators to promote crosstalk with neuronal cells. The net effect of this neuro-immune crosstalk critically depends on the context of the interaction. It has long been established that inflammatory reactions in the CNS can cause or augment tissue injury in many experimental paradigms. However, emerging evidence suggests that in other paradigms inflammatory cells can contribute to neuroprotection and repair. This dual role of CNS inflammation is also reflected on the molecular level as it is becoming increasingly clear that immune cells can release both neurodestructive and neuroprotective molecules into CNS lesions. It is thus the balance between destructive and protective factors that ultimately determines the net result of the neuro-immune interaction.

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.

Higher expression of BDNF receptor gp145trkB is associated with lower apoptosis intensity in T cell lines in multiple sclerosis

Conflicting data exist on expression of gp145trkB, the high affinity receptor for brain-derived neurotrophic factor (BDNF), on peripheral blood immunocompetent cells in multiple sclerosis (MS). We analyzed expression of gp145trkB by western blotting and flow cytometry in myelin basic protein (MBP)- and ovalbumin (OVA)-T cell lines prepared from 12 patients with relapsing-remitting MS and 12 normal healthy subjects (NHS) and correlated it with activation-induced apoptosis. We found a higher percentage of gp145trkB-expressing MBP-T cells in MS patients than in NHS (p=0.011). gp145trkB was mainly expressed by CD8(+) T cells to a higher extent in MS patients than in NHS (p=0.04). MBP-T cell lines from MS patients showed significantly lower apoptosis intensity than those from NHS (p=0.011). We found also a significant negative correlation between gp145trkB expression and apoptosis intensity in MS patients only (p=0.02). OVA-T cell lines showed a gp145trkB expression similar to that of MBP-T cell lines, with a higher expression in MS patients than NHS, and similar correlations with apoptosis intensity in MS. These findings suggest that gp145trkB is mainly expressed on T cell lines from MS patients and that the BDNF/gp145trkB axis is involved in the regulation of peripheral T cell apoptosis in MS.

Neuro-immune crosstalk in CNS diseases

Immune cells infiltrate the CNS in many neurological diseases with a primary or secondary inflammatory component. In the CNS, immune cells employ shared mediators to promote crosstalk with neuronal cells. The net effect of this neuro-immune crosstalk critically depends on the context of the interaction. It has long been established that inflammatory reactions in the CNS can cause or augment tissue injury in many experimental paradigms. However emerging evidence suggests that in other paradigms inflammatory cells can contribute to neuroprotection and repair. This dual role of CNS inflammation is also reflected on the molecular level as it is becoming increasingly clear that immune cells can release both neurodestructive and neuroprotective molecules in CNS lesions. It is thus the balance between destructive and protective factors that ultimately determines the net result of the neuro-immune interaction.

The immunocompetence of Schwann cells

Schwann cells are the myelinating glial cells of the peripheral nervous system that support and ensheath axons with myelin to enable rapid saltatory signal propagation in the axon. Immunocompetence, however, has only recently been recognized as an important feature of Schwann cells. An autoimmune response against components of the peripheral nervous system triggers disabling inflammatory neuropathies in patients and corresponding animal models. The immune system participates in nerve damage and disease manifestation even in non-inflammatory hereditary neuropathies. A growing body of evidence suggests that Schwann cells may modulate local immune responses by recognizing and presenting antigens and may also influence and terminate nerve inflammation by secreting cytokines. This review summarizes current knowledge on the interaction of Schwann cells with the immune system, which is involved in diseases of the peripheral nervous system.

Fortschritte im Verständnis von Pathogenese und Immuntherapie der Multiplen Sklerose

In this article recent advances in research on the pathogenesis of multiple sclerosis (MS) are summarized. New evidence from molecular histopathology is discussed focussing on neurodegenerative aspects. In addition findings with a direct effect on therapeutic decisions are presented which have contributed to improved immunotherapy. During the last decade important advances in immunotherapy have proven especially useful for patients with relapsing-remitting MS. Escalating algorithms are available for both relapses and long-term immunotherapy. Novel therapeutic approaches with monoclonal antibodies have increasing importance, yet side effects are not completely understood. The pathogenetic insights presented here may open new avenues for novel immunotherapies and lead to individualized MS therapy in the future. Limitations are given for primary progressive MS due to the lack of suitable tissue specimens and experimental models. Neuroprotective treatment strategies aiming at the protection of glial and neuronal cells are still in early stages of development.