Central inflammation versus peripheral regulation in multiple sclerosis

The action of TH17 cells on blood brain barrier in multiple sclerosis and experimental autoimmune encephalomyelitis

Th17 cells, known as a highly pro-inflammatory subtype of Th cells, are involved very early in numerous aspects of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) neuropathology. A crucial event for the formation and accumulation of MS lesions is represented by the disruption of the blood brain barrier (BBB) in relapsing-remitting MS. Th17 cells also contribute to the progression of MS/EAE. These events will allow for the passage of inflammatory cells into the brain. Secondary to this, increased recruitment of neutrophils occurs, followed by increased protease activity that will continue to attract macrophages and monocytes, leading to brain inflammation with sustained myelin and axon damage. This review focuses mainly on the role of Th17 cells in penetrating the BBB and on their important effects on BBB disruption via their main secretion products, IL-17 and IL-22. We present the morphological aspects of Th17 cells that allow for intercellular contacts with BBB endothelial cells and the functional/secretory particularities of Th17 cells that allow for intercellular communications that enhance Th17 entry into the CNS. The cytokines and chemokines involved in these processes are described. In conclusion, Th17 cells can efficiently cross the BBB using pathways distinct from those used by Th1 cells, leading to BBB disruption, the activation of other inflammatory cells and neurodegeneration in MS patients.

Analysis of the expression of mir-34a, mir-199a, mir-30c and mir-19a in peripheral blood CD4+T lymphocytes of relapsing-remitting multiple sclerosis patients

BACKGROUND

Multiple sclerosis is an immune-mediated inflammatory disease of central nervous system. MicroRNAs play important roles in autoimmune diseases such as MS.

OBJECTIVES

The aim was to evaluate the expression pattern of miR-34a, miR-199a, miR-30c and miR-19a in peripheral blood derived CD4+ T lymphocytes of both relapsing and remitting phases of MS.

METHODS

Blood samples from 40 RRMS patients (20 in relapsing and 20 in remitting phase) and 20 healthy volunteers were taken. CD4+ T cells were isolated. The expression level of miR-34a, miR-199a, miR-30c and miR-19a, and the percentage of Th17 and Treg cells were measured. Expression of master transcription factors of Th17 and Treg cells and several targets of these miRNAs were also evaluated.

RESULTS

Data indicated an increased expression of miR-34a, miR-30c and miR-19a in relapsing phase and decreased expression of miR-199a in remitting phase. ROC curve data add other prestigious information of miR-34a, miR-199a, miR-30c and miR-19a by defining relapsing and remitting phase and also healthy cases with high specificity and sensitivity at a proposed optimum cut-off point.

CONCLUSION

Collectively, we showed a correlation between the four miRNAs with different phases of MS and their possible involvement in differentiation pathways of Th17 cells, as the most important players in MS.

Depression and fatigue in multiple sclerosis: Relation to exposure to violence and cerebrospinal fluid immunomarkers

Multiple sclerosis (MS) is a neuroinflammatory condition characterized by chronic dysregulation of immune responses leading to repeated episodes of inflammation in the central nervous system. Depression and fatigue are common among MS patients, even in early disease phases, and the disease course can be negatively affected by stressful events. IL-6 and IL-8 have been associated with depression and stressful life events in non-MS patients. The aim of this study was to examine the relationships between depression, fatigue, and exposure to violence, with IL-6 and IL-8 levels in the cerebrospinal fluid (CSF) of MS patients. Levels of IL-6 and -8 were analyzed in the CSF of 47 patients with relapsing-remitting MS. Correlations between IL-6 and IL-8 levels and self-rated depression and fatigue symptoms, as well as clinician-rated history of being exposed to interpersonal violence, were analyzed with correction for age, sex and MS disability status. IL-6 correlated significantly (p < 0.05) with depressive symptoms (adjusted Spearman's ρ = 0.39), fatigue (ρ = 0.39), and exposure to violence in adult life (ρ = 0.35). Depression correlated with both fatigue and being exposed to violence. Associations were not present among patients exposed to disease modifying drugs. In exploratory analyses, the relationship between exposure to violence and IL-6 was non-significant when controlled for depression. Further research should focus on replication of these results, as well as exploring the impact of stressful life events on immune regulation and the clinical characteristics and prognosis of MS patients.

Peripheral Inflammation and Demyelinating Diseases

In recent decades, several neurodegenerative diseases have been shown to be exacerbated by systemic inflammatory processes. There is a wide range of literature that demonstrates a clear but complex relationship between the central nervous system (CNS) and the immunological system, both under naïve or pathological conditions. In diseased brains, peripheral inflammation can transform "primed" microglia into an "active" state, which can trigger stronger pathological responses. Demyelinating diseases are a group of neurodegenerative diseases characterized by inflammatory lesions associated with demyelination, which in turn induces axonal damage, neurodegeneration, and progressive loss of function. Among them, the most important are multiple sclerosis (MS) and neuromyelitis optica (NMO). In this review, we will analyze the effect of specific peripheral inflammatory stimuli in the progression of demyelinating diseases and discuss their animal models. In most cases, peripheral immune stimuli are exacerbating.

Chronic lung disease and multiple sclerosis: Incidence, prevalence, and temporal trends

OBJECTIVES

We aimed to estimate the incidence and prevalence of chronic lung disease (CLD), including asthma and chronic obstructive pulmonary disease, in the MS population versus a matched cohort from the general population.

METHODS

We used population-based administrative data from four Canadian provinces to identify 44,452 persons with MS and 220,849 age-, sex- and geographically-matched controls aged 20 years and older. We employed a validated case definition to estimate the incidence and prevalence of CLD over the period 1995-2005, and used Poisson regression to assess temporal trends.

RESULTS

In 2005, the crude incidence of CLD per 100,000 persons was 806 (95%CI: 701-911) in the MS population, and 757 in the matched population (95%CI: 712-803). In 2005, the crude prevalence of CLD was 13.5% (95%CI: 13.1-14.0%) in the MS population, and 12.4% (95%CI: 12.3-12.6%) in the matched population. Among persons aged 20-44 years, the average annual incidence of CLD was higher in the MS population than in the matched population (RR 1.15; 95%CI: 1.02-1.30), but did not differ between populations for those aged ≥45 years. The incidence of CLD was stable, but the prevalence of CLD increased 60% over the study period.

CONCLUSION

CLD is relatively common in the MS population. The incidence of CLD has been stable over time, but the prevalence of CLD has increased. Among persons aged 20-44 years, CLD is more common in the MS population than in a matched population. Given the prevalence of CLD in the MS population, further attention to the effects of CLD on outcomes in MS and approaches to mitigating those effects are warranted.

CD28 costimulatory signals in T lymphocyte activation: Emerging functions beyond a qualitative and quantitative support to TCR signalling

CD28 is one of the most important co-stimulatory receptors necessary for full T lymphocyte activation. By binding its cognate ligands, B7.1/CD80 or B7.2/CD86, expressed on the surface of professional antigen presenting cells (APC), CD28 initiates several signalling cascades, which qualitatively and quantitatively support T cell receptor (TCR) signalling. More recent data evidenced that human CD28 can also act as a TCR-independent signalling unit, by delivering specific signals, which regulate the expression of pro-inflammatory cytokine/chemokines. Despite the enormous progresses made in identifying the mechanisms and molecules involved in CD28 signalling properties, much remains to be elucidated, especially in the light of the functional differences observed between human and mouse CD28. In this review we provide an overview of the current mechanisms and molecules through which CD28 support TCR signalling and highlight recent findings on the specific signalling motifs that regulate the unique pro-inflammatory activity of human CD28.

Parallel Aspects of the Microenvironment in Cancer and Autoimmune Disease

Cancer and autoimmune diseases are fundamentally different pathological conditions. In cancer, the immune response is suppressed and unable to eradicate the transformed self-cells, while in autoimmune diseases it is hyperactivated against a self-antigen, leading to tissue injury. Yet, mechanistically, similarities in the triggering of the immune responses can be observed. In this review, we highlight some parallel aspects of the microenvironment in cancer and autoimmune diseases, especially hypoxia, and the role of macrophages, neutrophils, and their interaction. Macrophages, owing to their plastic mode of activation, can generate a pro- or antitumoral microenvironment. Similarly, in autoimmune diseases, macrophages tip the Th1/Th2 balance via various effector cytokines. The contribution of neutrophils, an additional plastic innate immune cell population, to the microenvironment and disease progression is recently gaining more prominence in both cancer and autoimmune diseases, as they can secrete cytokines, chemokines, and reactive oxygen species (ROS), as well as acquire an enhanced ability to produce neutrophil extracellular traps (NETs) that are now considered important initiators of autoimmune diseases. Understanding the contribution of macrophages and neutrophils to the cancerous or autoimmune microenvironment, as well as the role their interaction and cooperation play, may help identify new targets and improve therapeutic strategies.

Molecular biomarkers in cerebrospinal fluid of multiple sclerosis patients

Multiple sclerosis (MS) is a chronic immune-mediated disease of the central nervous system, usually occurring in young adults and leading to disability. Despite the progress in technology and intensive research work of the last years, diagnosing MS can still be challenging. A heterogenic and complex pathophysiology with various types of disease courses makes MS unique for each patient. There is an urgent need to identify markers facilitating rapid and accurate diagnosis and prognostic assessments with regard to optimal therapy for each MS patient. Cerebrospinal fluid (CSF) is an outstanding source of specific markers related to MS pathology. Molecules reflecting specific pathological processes, such as inflammation, cellular damage, and loss of blood-brain-barrier integrity, are detectable in CSF. Clinically used biomarkers of CSF are oligoclonal bands, IgG-index, measles-rubella-zoster-reaction, anti-aquaporin 4 antibodies, and antibodies against John Cunningham virus. Many other potential biomarkers have been proposed in recent years. In this review we examine the current scientific knowledge on CSF molecular markers that could guide diagnosis and discrimination of different MS forms, support treatment decisions, or be helpful in monitoring and predicting disease progression, therapy response, and complications such as opportunistic infections.

Multiple sclerosis course and clinical outcomes in patients with comorbid asthma: a survey study

OBJECTIVE

To determine if comorbid asthma is associated with accumulation of multiple sclerosis (MS)-related impairment and disability.

METHOD

We sent a comprehensive questionnaire to a cohort of patients with MS and examined the association between comorbid asthma and reaching Expanded Disability Status Scale (EDSS) scores 4.0 and 6.0. Multiple Sclerosis Impact Scale (MSIS-29) scores were compared between patients with MS with and without comorbid asthma.

RESULTS

680 patients participated in our study of whom 88 (12.9%) had comorbid asthma. There was no difference in the prevalence of asthma between our MS cohort and the England general population (OR: 0.89, 95% CI 0.68 to 1.17). We did not observe a significant association between having asthma and the risk of reaching EDSS scores 4.0 and 6.0 (HR: 1.29, 95% CI 0.93 to 1.77, and HR: 1.33, 95% CI 0.93 to 1.89, respectively) after controlling for confounders. Patients with MS with asthma reported higher level of psychological impairments (coefficient: 2.29, 95% CI 0.1 to 4.49).

CONCLUSIONS

Asthma is a prevalent condition among patients with MS and it may contribute to the psychological impairment in MS. Although we did not observe significant association between comorbid asthma and physical disability in MS, it seems that the two conditions influence one another.

miR-141 and miR-200a, Revelation of New Possible Players in Modulation of Th17/Treg Differentiation and Pathogenesis of Multiple Sclerosis

Background

One of the main issues in pathogenesis of MS is Th17/Treg imbalance. There are growing interests in nominating miRNAs involved in Th17 cell differentiation, suggesting them as new therapeutic agents that may reduce progression of different autoimmune diseases specially MS.

Objectives

We assessed transcript levels of miR-141 and miR-200a in MS patients, during relapsing and remitting phases. We also investigated possible role of miR-141, miR-200a in inducing differentiation to Th17 cells.

Materials and Methods

Forty RR-MS patient samples including relapsing (n=20) and remitting (n=20) phases were chosen. Expression level of miR-141 and miR-200a were measured by RT-q PCR and compared to healthy control group (n=10). In-silico analyses on miR-141 and miR-200a targetome showed involvement of both miRNAs in T helper cell differentiation pathways including TGF-β, mTOR and JAK/STAT.

Results

We observed that percentage of RORγt⁺ CD4⁺ T cells increase in relapsing phase while FOXP3⁺ CD4⁺ increase in remitting phase of MS patients. Furthermore, both miR-141 and miR-200a show up-regulation in relapsing phase of MS patients compared to remitting and control groups. Interestingly, expression level of target genes of miR-141 and miR-200a, which were assessed through in-silico methods, show down-regulation in relapsing phase of MS patients.

Conclusions

According to our results, miR-141 and miR-200a may be key miRNAs in progression of symptoms of MS through inducing differentiation of Th17 cells and inhibiting differentiation to Treg cells. Our data suggest that these miRNAs may probably inhibit negative regulators of Th17 cell differentiation, thus promoting its differentiation.

Infection risk in patients on multiple sclerosis therapeutics

The interface of multiple sclerosis (MS) and infection occurs on several levels. First, infectious disease has been postulated as a potential trigger, if not cause, of MS. Second, exacerbation of MS has been well-documented as a consequence of infection, and, lastly, infectious diseases have been recognized as a complication of the therapies currently employed in the treatment of MS. MS is a disease in which immune dysregulation is a key component. Examination of central nervous system (CNS) tissue of people affected by MS demonstrates immune cell infiltration, activation and inflammation. Therapies that alter the immune response have demonstrated efficacy in reducing relapse rates and evidence of brain inflammation on magnetic resonance imaging (MRI). Despite the altered immune response in MS, there is a lack of evidence that these patients are at increased risk of infectious disease in the absence of treatment or debility. Links between infections and disease-modifying therapies (DMTs) used in MS will be discussed in this review, as well as estimates of occurrence and ways to potentially minimize these risks. We address infection in MS in a comprehensive fashion, including (1) the impact of infections on relapse rates in patients with MS; (2) a review of available infection data from pivotal trials and postmarketing studies for the approved and experimental DMTs, including frequency, types and severity of infections; and (3) relevant risk minimization strategies, particularly as they pertain to progressive multifocal leukoencephalopathy (PML).

Helminth Therapy for MS

In the last 50 years, environmental factors such as helminth infections have been proposed to explain why autoimmunity is less prevalent in the developing world; this proposal has been termed the hygiene or old friends hypothesis. The epidemiology of MS shows an inverse correlation with helminth infections. Positive effects of helminths in animal models of MS and observational studies in people with MS naturally infected with helminths suggest that those organisms can act as immune regulators and led to clinical trials of helminth therapy. The goal of helminth therapy is to introduce parasitic organisms into people with MS in a controlled and predictable fashion, and to prevent immune-mediated disease without increasing the risk of pathology with high parasite load. This chapter focuses on intestinal worms as they are the current choice as a therapeutic strategy in a number of autoimmune diseases, including MS. Here we review current data regarding the rationale and the current state of research in the field of helminth therapies in MS.

Biased Treg/Th17 balance away from regulatory toward inflammatory phenotype in relapsed multiple sclerosis and its correlation with severity of symptoms

The opposing immune functions of Treg and Th17 lymphocytes and the plasticity of Treg/Th17 differentiation, has led us to investigate the effects of their fluctuations and counterbalance in autoimmune condition of multiple sclerosis (MS). Evaluation of Treg and Th17 frequency in peripheral blood of a group of relapsed MS patients, showed a decrease in Treg/Th17 ratio compared to that of healthy controls. A reverse correlation between these subsets was observed in controls but not in patient groups. Both Treg frequency and Treg/Th17 ratio were negatively correlated with severity of symptoms. There was shown to be an enduring increase in Treg frequency associated with MS disease.

Special issue commentary: the changing face of inflammation in the brain

The study of inflammation in the brain has been extended to include a wide range of conditions, but there remains plenty of argument over semantics and the precise definition of what constitutes inflammation in these pathologies. In this special issue, we sought to highlight the diversity of what is considered to be inflammation in the brain, and we have accepted that the presence of microglia cells with altered morphology remains a useful starting point. However, it is clear that whatever is the molecular expression profile that accompanies an activated microglial cell, it is not static and it is influenced by factors both intrinsic and extrinsic to the brain. This article is part of a Special Issue entitled 'Neuroinflammation in neurodegeneration and neurodysfunction'.

CNS response to a second pro-inflammatory event depends on whether the primary demyelinating lesion is active or resolved

Interleukin-1β (IL-1β) is considered to be one of the most important mediators in the pathogenesis of inflammatory diseases, particularly in neurodegenerative diseases such as multiple sclerosis (MS). MS is a chronic inflammatory disease characterized by demyelination and remyelination events, with unpredictable relapsing and remitting episodes that seldom worsen MS lesions. We proposed to study the effect of a unique component of the inflammatory process, IL-1β, and evaluate its effect in repeated episodes, similar to the relapsing-remitting MS pathology. Using adenoviral vectors, we developed a model of focal demyelination/remyelination triggered by the chronic expression of IL-1β. The long-term expression of IL-1β in the striatum produced blood-brain barrier (BBB) breakdown, demyelination, microglial/macrophage activation, and neutrophil infiltration but no overt neuronal degeneration. This demyelinating process was followed by complete remyelination of the area. This simple model allows us to study demyelination and remyelination independently of the autoimmune and adaptive immune components. Re-exposure to this cytokine when the first inflammatory response was still unresolved generated a lesion with decreased neuroinflammation, demyelination, axonal injury and glial response. However, a second long-term expression of IL-1β when the first lesion was resolved could not be differentiated from the first event. In this study, we demonstrated that the response to a second inflammatory stimulus varies depending on whether the initial lesion is still active or has been resolved. Considering that anti-inflammatory treatments have shown little improvement in MS patients, studies about the behavior of specific components of the inflammatory process should be taken into account to develop new therapeutic tools.