Matrix metalloproteinase-19 is highly expressed in active multiple sclerosis lesions

Diagnostic performance of perfusion-weighted imaging combined with serum MMP-2 and -9 levels in tumor recurrence after postoperative concomitant chemoradiotherapy of glioblastoma

OBJECTIVE

To evaluate diagnostic accuracy of dynamic susceptibility contrast- perfusion weighted imaging (DSC-PWI) combined with serum MMP-2 and -9 levels in differentiating recurrent glioblastoma (GBM).

METHODS

We enrolled a total of 220 GBM patients, including recurrent cases (n = 150) and non-recurrent cases (n = 70) after postoperative concomitant chemoradiotherapy. All patients performed preoperative and follow-up DSC-PWI, and two parameters [normalized cerebral blood volume (nCBV) and cerebral blood flow (nCBF)] were obtained. Preoperative serum levels of MMP-2 and MMP-9 were detected using ELISA. The diagnostic performance was evaluated by analyzing receiver operating characteristic (ROC) and area under the curve (AUC).

RESULTS

At baseline, the recurrence patients had higher nCBF and nCBV than the non-recurrence patients, accompanying by the increased MMP-2 and MMP-9 levels in serum. Serum MMP-2 level were positively associated with MMP-9 in recurrent patients. In patients classified as recurrence, both MMP-9 and MMP-2 in serum had a significant correlation with nCBV and nCBF. A sensitivity and specificity of nCBF for recurrence vs. non-recurrence were 94.29% and 63.33%, respectively. nCBV also could provide high discrimination between recurrence and non-recurrence patients (sensitivity: 84.29%, specificity: 62.67%, AUC: 0.821). In ROC analyses, both MMP-2 and MMP-9 distinguished recurrence from non-recurrence with AUC values of 0.883 and 0.900, respectively. Finally, the combination of DSC-PWI parameters (nCBF and nCBV) and serum MMP-2 and -9 levels showed much better discrimination capacity between recurrence and non-recurrence patients with a sensitivity of 92.86%, specificity of 79.33% and AUC of 0.899.

CONCLUSION

The combination of DSC-PWI parameters together with serum MMP-2 and -9 levels offered an attractive approach to noninvasively distinguish recurrence after postoperative radiotherapy of GBM.

Perivascular spaces and their role in neuroinflammation

It is uncontested that perivascular spaces play critical roles in maintaining homeostasis and priming neuroinflammation. However, despite more than a century of intense research on perivascular spaces, many open questions remain about the anatomical compartment surrounding blood vessels within the CNS. The goal of this comprehensive review is to summarize the literature on perivascular spaces in human neuroinflammation and associated animal disease models. We describe the cell types taking part in the morphological and functional aspects of perivascular spaces and how those spaces can be visualized. Based on this, we propose a model of the cascade of events occurring during neuroinflammatory pathology. We also discuss current knowledge gaps and limitations of the available evidence. An improved understanding of perivascular spaces could advance our comprehension of the pathophysiology of neuroinflammation and open a new therapeutic window for neuroinflammatory diseases such as multiple sclerosis.

Acute and Delayed Effects of Stress Eliciting Post-Traumatic Stress-Like Disorder Differentially Alters Fecal Microbiota Composition in a Male Mouse Model

The association between the shift in fecal resident microbiome and social conflicts with long-term consequences on psychological plasticity, such as the development of post-traumatic stress disorder (PTSD), is yet to be comprehended. We developed an aggressor-exposed (Agg-E) social stress (SS) mouse model to mimic warzone-like conflicts, where random life-threatening interactions took place between naïve intruder mice and aggressive resident mice. Gradually these Agg-E mice developed distinct characteristics simulating PTSD-like aspects, whereas the control mice not exposed to Agg-E SS demonstrated distinct phenotypes. To further investigate the role of Agg-E SS on the resident microbiome, 16S rRNA gene sequencing was assayed using fecal samples collected at pre-, during, and post-SS time points. A time agonist shift in the fecal microbial composition of Agg-E mice in contrast to its controls suggested a persistent impact of Agg-E SS on resident microbiota. At the taxonomic level, Agg-E SS caused a significant shift in the time-resolved ratios of Firmicutes and Bacteroidetes abundance. Furthermore, Agg-E SS caused diverging shifts in the relative abundances of Verrucomicrobia and Actinobacteria. An in silico estimation of genomic potential identified a potentially perturbed cluster of bioenergetic networks, which became increasingly enriched with time since the termination of Agg-E SS. Supported by a growing number of studies, our results indicated the roles of the microbiome in a wide range of phenotypes that could mimic the comorbidities of PTSD, which would be directly influenced by energy deficiency. Together, the present work suggested the fecal microbiome as a potential tool to manage long-term effects of social conflicts, including the management of PTSD.

The matrix metalloproteinase inhibitor IPR-179 has antiseizure and antiepileptogenic effects

Matrix metalloproteinases (MMPs) are synthesized by neurons and glia and released into the extracellular space, where they act as modulators of neuroplasticity and neuroinflammatory agents. Development of epilepsy (epileptogenesis) is associated with increased expression of MMPs, and therefore, they may represent potential therapeutic drug targets. Using quantitative PCR (qPCR) and immunohistochemistry, we studied the expression of MMPs and their endogenous inhibitors tissue inhibitors of metalloproteinases (TIMPs) in patients with status epilepticus (SE) or temporal lobe epilepsy (TLE) and in a rat TLE model. Furthermore, we tested the MMP2/9 inhibitor IPR-179 in the rapid-kindling rat model and in the intrahippocampal kainic acid mouse model. In both human and experimental epilepsy, MMP and TIMP expression were persistently dysregulated in the hippocampus compared with in controls. IPR-179 treatment reduced seizure severity in the rapid-kindling model and reduced the number of spontaneous seizures in the kainic acid model (during and up to 7 weeks after delivery) without side effects while improving cognitive behavior. Moreover, our data suggest that IPR-179 prevented an MMP2/9-dependent switch-off normally restraining network excitability during the activity period. Since increased MMP expression is a prominent hallmark of the human epileptogenic brain and the MMP inhibitor IPR-179 exhibits antiseizure and antiepileptogenic effects in rodent epilepsy models and attenuates seizure-induced cognitive decline, it deserves further investigation in clinical trials.

Crosstalk between Inflammation and the BBB in Stroke

The blood-brain barrier (BBB), which is located at the interface between the central nervous system (CNS) and the circulatory system, is instrumental in establishing and maintaining the microenvironmental homeostasis of the CNS. BBB disruption following stroke promotes inflammation by enabling leukocytes, T cells and other immune cells to migrate via both the paracellular and transcellular routes across the BBB and to infiltrate the CNS parenchyma. Leukocytes promote the removal of necrotic tissues and neuronal recovery, but they also aggravate BBB injury and exacerbate stroke outcomes, especially after late reperfusion. Moreover, the swelling of astrocyte endfeet is thought to contribute to the ‘no-reflow’ phenomenon observed after cerebral ischemia, that is, blood flow cannot return to capillaries after recanalization of large blood vessels. Pericyte recruitment and subsequent coverage of endothelial cells (ECs) alleviate BBB disruption, which causes the transmigration of inflammatory cells across the BBB to be a dynamic process. Furthermore, interneurons and perivascular microglia also make contacts with ECs, astrocytes and pericytes to establish the neurovascular unit. BBB-derived factors after cerebral ischemia triggered microglial activation. During the later stage of injury, microglia remain associated with brain ECs and contribute to repair mechanisms, including postinjury angiogenesis, by acquiring a protective phenotype, which possibly occurs through the release of microglia-derived soluble factors. Taken together, we reviewed dynamic and bidirectional crosstalk between inflammation and the BBB during stroke and revealed targeted interventions based on the crosstalk between inflammation and the BBB, which will provide novel insights for developing new therapeutic strategies.

Differential Expression and miRNA-Gene Interactions in Early and Late Mild Cognitive Impairment

Mild cognitive impairment (MCI) and Alzheimer's Disease (AD) are complex diseases with their molecular architecture not elucidated. APOE, Amyloid Beta Precursor Protein (APP), and Presenilin-1 (PSEN1) are well-known genes associated with both MCI and AD. Recently, epigenetic alterations and dysregulated regulatory elements, such as microRNAs (miRNAs), have been reported associated with neurodegeneration. In this study, differential expression analysis (DEA) was performed for genes and miRNAs based on microarray and RNA-Seq data. Global gene profile of healthy individuals, early and late mild cognitive impairment (EMCI and LMCI, respectively), and AD was obtained from ADNI Cohort. miRNA global profile of healthy individuals and AD patients was extracted from public RNA-Seq data. DEA performed with limma package on ADNI Cohort data highlighted eight differential expressed (DE) genes (AGER, LINC00483, MMP19, CATSPER1, ARFGAP1, GPER1, PHLPP2, TRPM2) (false discovery rate (FDR) p-value < 0.05) between EMCI and LMCI patients. Previous molecular studies showed associations between these genes with dementia and neurological-related pathways. Five dysregulated miRNAs were identified by DEA performed with RNA-Seq data and edgeR (FDR p-value < 0.002). All reported miRNAs in AD interact with the aforementioned genes. Our integrative transcriptomic analysis was able to identify a set of miRNA-gene interactions that may be involved in cognitive and neurodegeneration processes.

Matrix metalloproteinases shape the oligodendrocyte (niche) during development and upon demyelination

The oligodendrocyte lineage cell is crucial to proper brain function. During central nervous system development, oligodendrocyte progenitor cells (OPCs) migrate and proliferate to populate the entire brain and spinal cord, and subsequently differentiate into mature oligodendrocytes that wrap neuronal axons in an insulating myelin layer. When damage occurs to the myelin sheath, OPCs are activated and recruited to the demyelinated site, where they differentiate into oligodendrocytes that remyelinate the denuded axons. The process of OPC attraction and differentiation is influenced by a multitude of factors from the cell's niche. Matrix metalloproteinases (MMPs) are powerful and versatile enzymes that do not only degrade extracellular matrix proteins, but also cleave cell surface receptors, growth factors, signaling molecules, proteases and other precursor proteins, leading to their activation or degradation. MMPs are markedly upregulated during brain development and upon demyelinating injury, where their broad functions influence the behavior of neural progenitor cells (NPCs), OPCs and oligodendrocytes. In this review, we focus on the role of MMPs in (re)myelination. We will start out in the developing brain with describing the effects of MMPs on NPCs, OPCs and eventually oligodendrocytes. Then, we will outline their functions in oligodendrocyte process extension and developmental myelination. Finally, we will review their potential role in demyelination, describe their significance in remyelination and discuss the evidence for a role of MMPs in remyelination failure, focusing on multiple sclerosis. In conclusion, MMPs shape the oligodendrocyte (niche) both during development and upon demyelination, and thus are important players in directing the fate and behavior of oligodendrocyte lineage cells throughout their life cycle.

Remodeling of the interstitial extracellular matrix in white matter multiple sclerosis lesions: Implications for remyelination (failure)

The extracellular matrix (ECM) provides protection, rigidity, and structure toward cells. It consists, among others, of a wide variety of glycoproteins and proteoglycans, which act together to produce a complex and dynamic environment, most relevant in transmembrane events. In the brain, the ECM occupies a notable proportion of its volume and maintains the homeostasis of central nervous system (CNS). In addition, remodeling of the ECM, that is transient changes in ECM proteins regulated by matrix metalloproteinases (MMPs), is an important process that modulates cell behavior upon injury, thereby facilitating recovery. Failure of ECM remodeling plays an important role in the pathogenesis of multiple sclerosis (MS), a neurodegenerative demyelinating disease of the CNS with an inflammatory response against protective myelin sheaths that surround axons. Remyelination of denuded axons improves the neuropathological conditions of MS, but this regeneration process fails over time, leading to chronic disease progression. In this review, we uncover abnormal ECM remodeling in MS lesions by discussing ECM remodeling in experimental demyelination models, that is when remyelination is successful, and compare alterations in ECM components to the ECM composition and MMP expression in the parenchyma of demyelinated MS lesions, that is when remyelination fails. Inter- and intralesional differences in ECM remodeling in the distinct white matter MS lesions are discussed in terms of consequences for oligodendrocyte behavior and remyelination (failure). Hence, the review will aid to understand how abnormal ECM remodeling contributes to remyelination failure in MS lesions and assists in developing therapeutic strategies to promote remyelination.

RGC-32 regulates reactive astrocytosis and extracellular matrix deposition in experimental autoimmune encephalomyelitis

Extracellular matrix (ECM) deposition in active demyelinating multiple sclerosis (MS) lesions may impede axonal regeneration and can modify immune reactions. Response gene to complement (RGC)-32 plays an important role in the mediation of TGF-β downstream effects, but its role in gliosis has not been investigated. To gain more insight into the role played by RGC-32 in gliosis, we investigated its involvement in TGF-β-induced ECM expression and the upregulation of the reactive astrocyte markers α-smooth muscle actin (α-SMA) and nestin. In cultured neonatal rat astrocytes, collagens I, IV, and V, fibronectin, α-SMA, and nestin were significantly induced by TGF-β stimulation, and RGC-32 silencing resulted in a significant reduction in their expression. Using astrocytes isolated from RGC-32 knock-out (KO) mice, we found that the expression of TGF-β-induced collagens I, IV, and V, fibronectin, and α-SMA was significantly reduced in RGC-32 KO mice when compared with wild-type (WT) mice. SIS3 inhibition of Smad3 phosphorylation was also associated with a significant reduction in RGC-32 nuclear translocation and TGF-β-induced collagen I expression. In addition, during experimental autoimmune encephalomyelitis (EAE), RGC-32 KO mouse astrocytes displayed an elongated, bipolar phenotype, resembling immature astrocytes and glial progenitors whereas those from WT mice had a reactive, hypertrophied phenotype. Taken together, our data demonstrate that RGC-32 plays an important role in mediating TGF-β-induced reactive astrogliosis in EAE. Therefore, RGC-32 may represent a new target for therapeutic intervention in MS.

Decidual leucocytes infiltrating human spiral arterioles are rich source of matrix metalloproteinases and degrade extracellular matrix in vitro and in situ

PROBLEM

During pregnancy, the decidual spiral arterioles (SpAs) that supply maternal blood to the placenta undergo a series of changes to optimise the transfer of nutrients and oxygen to the developing foetus. Recent studies have shown that initiation of SpA transformation coincides with decidual leucocyte infiltration. Leucocytes are known to be a source of matrix metalloproteinases (MMPs); however, the complete profile of MMPs expressed by decidual NK cells (dNK) and macrophages has not been characterised. We hypothesised that leucocyte-derived MMPs contribute to SpA remodelling.

METHODS

Decidual NK cells and macrophages were isolated from first trimester decidua and their MMP repertoire profiled by qRT-PCR (n = 10; 5-11 weeks). Dual immunofluorescence was used to localise MMP expression in situ (n = 3; 5-12 weeks). Gelatin zymography was carried out to assess whether leucocyte-derived MMPs can degrade ECM. In situ zymography and immunofluorescence identified MMP activity in tissue-resident dNK and macrophages.

RESULTS

Decidual NK cells cells and macrophages expressed MMP2, -7, -9, -11, -16, -19 and tissue inhibitors of metalloproteinase-1, -2, and -3. Both cell types degraded gelatin using MMP2 and MMP9 and broke down collagen in an in vitro model of the SpA. Extravillous trophoblasts (EVTs) expressed a similar repertoire of MMPs.

CONCLUSION

We suggest that matrix remodelling in SpA is initiated by infiltrating leucocytes, while EVTs become involved at later stages.

Traditional Chinese Medicine Extract from Huaier Increases the Expression of Duffy Antigen Receptor for Chemokines and Reduces the Expression of Its Ligands

Aims

The aim of the present study is to investigate whether the aqueous extract from Huaier, a traditional Chinese medicine (TCM), can affect the expression of Duffy antigen receptor for chemokines (DARC) and its ligands. Moreover, we compare the status of DARC in primary and metastatic breast cancer tissues from the same patient.

Methods

Immunohistochemistry was used to detect the expression of DARC in primary and metastatic focuses in 30 patients with breast cancer. The effect of Huaier aqueous extract on the expression of DARC and its ligands was investigated by quantitative real-time polymerase chain reaction, Western blotting, and enzyme-linked immunosorbent assay.

Results

The expression score of DARC in primary focuses was significantly higher than that in metastatic focuses, while changes of ER, PR, and HER2 receptors were not significantly different between primary and metastatic focuses. Huaier aqueous extract promoted the expression of DARC and reduced the secretion of CC chemokine ligand 2 (CCL-2), CXC chemokine ligand 8 (CXCL-8, IL-8), matrix metalloproteinase 2 (MMP-2), and CXC chemokine ligand 1 (CXCL-1).

Conclusion

The present study demonstrates that difference in expression level of DARC between primary and metastatic focuses of breast cancer was significant, while differences in expression of ER, PR, and HER2 between primary and metastatic focuses were not significant. DARC may play a negative role in the metastasis of breast cancer. Traditional Chinese medicine extract from Huaier can increase DARC expression and reduce the expression of its ligands such as CCL-2, IL-8, MMP-2, and CXCL-1.

Association of MMP-2 (⁻1306 C/T) Gene Polymorphism with Predisposition to Optic Neuritis and Optic Neuritis Together with Multiple Sclerosis

Background and objective: Optic neuritis (ON) is characterized by painful, usually monocular vision loss with decreased visual acuity and defects of the visual field and color vision. The etiology and pathophysiology of ON is not completely clear. It is thought that a matrix metalloproteinase 2 (MMP-2) gene plays an essential role in this autoimmune inflammatory disease. The aim of this study was to determine the relationship between the MMP-2 (-1306 C/T)rs243865 gene polymorphism and ON, and that of ON with multiple sclerosis. Materials and methods: Patients with ON/ON and multiple sclerosis and a control group of healthy individuals were enrolled in this study. The genotyping test of the MMP-2 (-1306 C/T) was carried out using a real-time polymerase chain reaction (PCR) method. Results: Analysis revealed that T allele at the MMP-2 (-1306 C/T) was less frequent in the ON group compared to the control group (14.5% vs. 23.3%, p = 0.031), and was associated with decreased likelihood of ON development (OR = 0.566; 95% CI: 0.333-0.962; p = 0.036). No significant associations were revealed while comparing the subgroups of ON patients with and without multiple sclerosis. Conclusion: The MMP-2 (-1306 C/T) gene polymorphism was found to be associated with ON development.

Gene Expression Profiling in the Injured Spinal Cord of Trachemys scripta elegans: An Amniote with Self-Repair Capabilities

Slider turtles are the only known amniotes with self-repair mechanisms of the spinal cord that lead to substantial functional recovery. Their strategic phylogenetic position makes them a relevant model to investigate the peculiar genetic programs that allow anatomical reconnection in some vertebrate groups but are absent in others. Here, we analyze the gene expression profile of the response to spinal cord injury (SCI) in the turtle Trachemys scripta elegans. We found that this response comprises more than 1000 genes affecting diverse functions: reaction to ischemic insult, extracellular matrix re-organization, cell proliferation and death, immune response, and inflammation. Genes related to synapses and cholesterol biosynthesis are down-regulated. The analysis of the evolutionary distribution of these genes shows that almost all are present in most vertebrates. Additionally, we failed to find genes that were exclusive of regenerating taxa. The comparison of expression patterns among species shows that the response to SCI in the turtle is more similar to that of mice and non-regenerative Xenopus than to Xenopus during its regenerative stage. This observation, along with the lack of conserved “regeneration genes” and the current accepted phylogenetic placement of turtles (sister group of crocodilians and birds), indicates that the ability of spinal cord self-repair of turtles does not represent the retention of an ancestral vertebrate character. Instead, our results suggest that turtles developed this capability from a non-regenerative ancestor (i.e., a lineage specific innovation) that was achieved by re-organizing gene expression patterns on an essentially non-regenerative genetic background. Among the genes activated by SCI exclusively in turtles, those related to anoxia tolerance, extracellular matrix remodeling, and axonal regrowth are good candidates to underlie functional recovery.

Multiple Sclerosis - A Vascular Etiology?

From the earliest pathological studies the perivenular localization of the demyelination in multiple sclerosis (MS) has been observed. It has recently been suggested that obstructions to venous flow or inadequate venous valves in the great veins in the neck, thorax and abdomen can cause damaging backflow into the cerebral and spinal cord circulations. Paolo Zamboni and colleagues have demonstrated abnormal venous circulation in some multiple sclerosis patients using non-invasive sonography and invasive venography. Furthermore, they have obtained apparent clinical improvement or stabilization by endovascular ballooning of points of obstruction in the great veins in some, at least temporarily. If non-invasive observations by others validate their initial observations of a significantly increased prevalence of venous obstructions in MS then trials of angioplasty/stenting would be justified in selected cases in view of the biological plausibility of the concept.

Matrix metalloproteinases in the brain and blood-brain barrier: Versatile breakers and makers

Matrix metalloproteinases are versatile endopeptidases with many different functions in the body in health and disease. In the brain, matrix metalloproteinases are critical for tissue formation, neuronal network remodeling, and blood-brain barrier integrity. Many reviews have been published on matrix metalloproteinases before, most of which focus on the two best studied matrix metalloproteinases, the gelatinases MMP-2 and MMP-9, and their role in one or two diseases. In this review, we provide a broad overview of the role various matrix metalloproteinases play in brain disorders. We summarize and review current knowledge and understanding of matrix metalloproteinases in the brain and at the blood-brain barrier in neuroinflammation, multiple sclerosis, cerebral aneurysms, stroke, epilepsy, Alzheimer's disease, Parkinson's disease, and brain cancer. We discuss the detrimental effects matrix metalloproteinases can have in these conditions, contributing to blood-brain barrier leakage, neuroinflammation, neurotoxicity, demyelination, tumor angiogenesis, and cancer metastasis. We also discuss the beneficial role matrix metalloproteinases can play in neuroprotection and anti-inflammation. Finally, we address matrix metalloproteinases as potential therapeutic targets. Together, in this comprehensive review, we summarize current understanding and knowledge of matrix metalloproteinases in the brain and at the blood-brain barrier in brain disorders.

Role of Sortilin in Models of Autoimmune Neuroinflammation

The proneurotrophin receptor sortilin is a protein with dual functions, being involved in intracellular protein transport, as well as cellular signal transduction. The relevance of the receptor for various neuronal disorders, such as dementia, seizures, and brain injury, is well established. In contrast, little is known about the role of sortilin in immune cells and inflammatory diseases. The aim of our study was to elucidate the distribution of sortilin in different immune cell types in mice and humans and to analyze its function in autoimmune CNS inflammation. Sortilin was expressed most profoundly in murine and human macrophages and dendritic cells and to a much lesser extent in B and T cells. In dendritic cells, sortilin had an impact on Ag processing. Accordingly, sortilin was highly expressed by infiltrated perivascular myeloid cells, mainly in vessel cuffs, in the CNS of patients suffering from multiple sclerosis, the most common inflammatory autoimmune disease of the CNS. Yet, sortilin gene-targeted mice (Sort1(-/-)) and chimeras deficient in sortilin in the immune system were as susceptible as wild-type littermates to T cell-dependent experimental autoimmune encephalomyelitis. Considering our results and recent data from other investigators, we conclude that the proneurotrophin receptor sortilin plays a role in innate, rather than in adaptive, immune processes and, thus, not in autoimmune neuroinflammation.

Glial influences on BBB functions and molecular players in immune cell trafficking

The blood-brain barrier (BBB) constitutes an elaborate structure formed by specialized capillary endothelial cells, which together with pericytes and perivascular glial cells regulates the exchanges between the central nervous system (CNS) and the periphery. Intricate interactions between the different cellular constituents of the BBB are crucial in establishing a functional BBB and maintaining the delicate homeostasis of the CNS microenvironment. In this review, we discuss the role of astrocytes and microglia in inducing and maintaining barrier properties under physiological conditions as well as their involvement during neuroinflammatory pathologies. This article is part of a Special Issue entitled: Neuro Inflammation edited by Helga E. de Vries and Markus Schwaninger.

The role of Duffy antigen receptor for chemokines in keloids

This study aims to determine the relationship between Duffy antigen receptor for chemokines (DARC) and keloid pathogenesis. DARC expression was determined by immunohistochemistry, real-time PCR, and Western blot analysis. Cell proliferation was assessed by CCK-8 assay. Cell migration and invasion abilities were measured by the shift assay. Levels of CC chemokine ligand 2 (CCL2), CXC chemokine ligand 8 (CXCL8), and matrix metalloproteinase 2 (MMP2) were detected by real-time PCR and ELISA. Our results showed that DARC levels were elevated in human keloid fibroblasts. After knocking down DARC, cell proliferation was not altered, whereas the migration and invasion abilities of keloid fibroblasts were significantly elevated. Additionally, the mRNA expression levels of CCL2, CXCL8, and MMP2 were not influenced by DARC knockdown. However, the secretion of CCL2, but not CXCL8 or MMP2, was significantly increased after DARC knockdown. Our results suggest that DARC might inhibit the secretion of CCL2. Moreover, DARC knockdown increases the migration and invasion abilities of keloid fibroblasts.

GM-CSF promotes migration of human monocytes across the blood brain barrier

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). Infiltration of monocytes into the CNS is crucial for disease onset and progression. Animal studies indicate that granulocyte-macrophages colony-stimulating factor (GM-CSF) may play an essential role in this process, possibly by acting on the migratory capacities of myeloid cells across the blood-brain barrier. This study describes the effect of GM-CSF on human monocytes, macrophages, and microglia. Furthermore, the expression of GM-CSF and its receptor was investigated in the CNS under healthy and pathological conditions. We show that GM-CSF enhances monocyte migration across human blood-brain barrier endothelial cells in vitro. Next, immunohistochemical analysis on human brain tissues revealed that GM-CSF is highly expressed by microglia and macrophages in MS lesions. The GM-CSF receptor is expressed by neurons in the rim of combined gray/white matter lesions and astrocytes. Finally, the effect of GM-CSF on human macrophages was determined, revealing an intermediate activation status, with a phenotype similar to that observed in active MS lesions. Together our data indicate that GM-CSF is a powerful stimulator of monocyte migration, and is abundantly present in the inflamed CNS where it may act as an activator of macrophages and microglia.

The impact of microglial activation on blood-brain barrier in brain diseases

The blood-brain barrier (BBB), constituted by an extensive network of endothelial cells (ECs) together with neurons and glial cells, including microglia, forms the neurovascular unit (NVU). The crosstalk between these cells guarantees a proper environment for brain function. In this context, changes in the endothelium-microglia interactions are associated with a variety of inflammation-related diseases in brain, where BBB permeability is compromised. Increasing evidences indicate that activated microglia modulate expression of tight junctions, which are essential for BBB integrity and function. On the other hand, the endothelium can regulate the state of microglial activation. Here, we review recent advances that provide insights into interactions between the microglia and the vascular system in brain diseases such as infectious/inflammatory diseases, epilepsy, ischemic stroke and neurodegenerative disorders.

Pathology of multiple sclerosis and related inflammatory demyelinating diseases

This article provides a comprehensive overview of the pathology of multiple sclerosis (MS), including recent insights into its molecular neuropathology and immunology. It shows that all clinical manifestations of relapsing and progressive MS display the same basic features of pathology, such as chronic inflammation, demyelination in the white and gray matter, and diffuse neurodegeneration within the entire central nervous system. However, the individual components of the pathological spectrum vary quantitatively between early relapsing and late progressive MS. Widespread confluent and plaque-like demyelination with oligodendrocyte destruction is the unique pathological hallmark of the disease, but axonal injury and neurodegeneration are additionally present and in part extensive. Remyelination of existing lesions may occur in MS brains; it is extensive in a subset of patients, while it fails in others. Active tissue injury in MS is always associated with inflammation, consistent with T-cell and macrophage infiltration and microglia activation. Recent data suggest that oxidative injury and subsequent mitochondrial damage play a major pathogenetic role in neurodegeneration. Finally we discuss similarities and differences of the pathology between classical MS and other inflammatory demyelinating diseases, such as neuromyelitis optica, concentric sclerosis, or acute disseminated encephalomyelitis.

The significance of matrix metalloproteinases in the immunopathogenesis and treatment of multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS). The major pathological outcomes of the disease are the loss of blood-brain barrier (BBB) integrity and the development of reactive astrogliosis and MS plaque. For the disease to occur, the non-resident cells must enter into the immune-privileged CNS through a breach in the relatively impermeable BBB. It has been demonstrated that matrix metalloproteinases (MMPs) play an important role in the immunopathogenesis of MS, in part through the disruption of the BBB and the recruitment of inflammatory cells into the CNS. Moreover, MMPs can also enhance the cleavage of myelin basic protein (MBP) and the demyelination process. Regarding the growing data on the roles of MMPs and their tissue inhibitors (TIMPs) in the pathogenesis of MS, this review discusses the role of different types of MMPs, including MMP-2, -3, -7, -9, -12 and -25, in the immunopathogenesis and treatment of MS.

Macrophages in inflammatory multiple sclerosis lesions have an intermediate activation status

Background

Macrophages play a dual role in multiple sclerosis (MS) pathology. They can exert neuroprotective and growth promoting effects but also contribute to tissue damage by production of inflammatory mediators. The effector function of macrophages is determined by the way they are activated. Stimulation of monocyte-derived macrophages in vitro with interferon-γ and lipopolysaccharide results in classically activated (CA/M1) macrophages, and activation with interleukin 4 induces alternatively activated (AA/M2) macrophages.

Methods

For this study, the expression of a panel of typical M1 and M2 markers on human monocyte derived M1 and M2 macrophages was analyzed using flow cytometry. This revealed that CD40 and mannose receptor (MR) were the most distinctive markers for human M1 and M2 macrophages, respectively. Using a panel of M1 and M2 markers we next examined the activation status of macrophages/microglia in MS lesions, normal appearing white matter and healthy control samples.

Results

Our data show that M1 markers, including CD40, CD86, CD64 and CD32 were abundantly expressed by microglia in normal appearing white matter and by activated microglia and macrophages throughout active demyelinating MS lesions. M2 markers, such as MR and CD163 were expressed by myelin-laden macrophages in active lesions and perivascular macrophages. Double staining with anti-CD40 and anti-MR revealed that approximately 70% of the CD40-positive macrophages in MS lesions also expressed MR, indicating that the majority of infiltrating macrophages and activated microglial cells display an intermediate activation status.

Conclusions

Our findings show that, although macrophages in active MS lesions predominantly display M1 characteristics, a major subset of macrophages have an intermediate activation status.

The Role of ATP-Binding Cassette Transporters in Neuro-Inflammation: Relevance for Bioactive Lipids

ATP-binding cassette (ABC) transporters are highly expressed by brain endothelial cells that form the blood–brain barrier (BBB). These efflux pumps play an important role in maintaining brain homeostasis as they actively hinder the entry of unwanted blood-derived compounds into the central nervous system (CNS). Consequently, their high activity at the BBB has been a major hurdle for the treatment of several brain diseases, as they prevent numerous drugs to reach their site of action within the brain. Importantly, recent data indicate that endogenous substrates for ABC transporters may include inflammatory mediators, such as prostaglandins, leukotrienes, cytokines, chemokines, and bioactive lipids, suggesting a potential role for ABC transporters in immunological responses, and more specifically in inflammatory brain disorders, such as multiple sclerosis (MS). In this review, we will give a comprehensive overview of recent findings that illustrate this novel role for ABC transporters in neuro-inflammatory processes. Moreover, we will provide first insights into underlying mechanisms and focus on the importance for bioactive lipids, in particular platelet-activating factor, herein. A thorough understanding of these events may form the basis for the development for selective treatment modalities to dampen the neuro-inflammatory attack in MS and thereby reducing tissue damage.

Human matrix metalloproteinases: an ubiquitarian class of enzymes involved in several pathological processes

Human matrix metalloproteinases (MMPs) belong to the M10 family of the MA clan of endopeptidases. They are ubiquitarian enzymes, structurally characterized by an active site where a Zn(2+) atom, coordinated by three histidines, plays the catalytic role, assisted by a glutamic acid as a general base. Various MMPs display different domain composition, which is very important for macromolecular substrates recognition. Substrate specificity is very different among MMPs, being often associated to their cellular compartmentalization and/or cellular type where they are expressed. An extensive review of the different MMPs structural and functional features is integrated with their pathological role in several types of diseases, spanning from cancer to cardiovascular diseases and to neurodegeneration. It emerges a very complex and crucial role played by these enzymes in many physiological and pathological processes.

Distinct spatio-temporal extracellular matrix accumulation within demyelinated spinal cord lesions in Theiler's murine encephalomyelitis

The accumulation of extracellular matrix (ECM) and glial scar formation are considered important factors for the failure of regeneration in central nervous system (CNS) injury and multiple sclerosis. Theiler's murine encephalomyelitis (TME) as a model of multiple sclerosis served to evaluate the spatio-temporal course of ECM alterations in demyelinating conditions. Microarray analysis revealed only mildly upregulated gene expression of ECM molecules, their biosynthesis pathways and pro-fibrotic factors, while upregulation of matrix remodeling enzymes was more prominent. Immunohistochemistry demonstrated progressive accumulation of chondroitin sulfate proteoglycans, glycoproteins and collagens within demyelinated TME lesions, paralleling the development of astrogliosis. Deposition of collagen IV, laminin, perlecan and tenascin-C started 28 days postinfection (dpi), collagen I, decorin, entactin and neurocan accumulated from 56 dpi on, and fibronectin from 98 dpi on. The basement membrane (BM) molecules collagen IV, entactin, fibronectin, laminin and perlecan showed perivascular and parenchymal deposition, while the non-BM components collagen I, decorin, neurocan and tenascin-C only accumulated in a nonvascular pattern in demyelinated areas. Contrary, phosphacan expression progressively decreased during TME. The immunoreactivity of aggrecan and brevican remained unchanged. The spatio-temporal association of matrix accumulation with astrogliosis suggests a mainly astrocytic origin of ECM deposits, which in turn may contribute to remyelination failure in TME.

How do immune cells overcome the blood-brain barrier in multiple sclerosis?

The presence of the blood-brain barrier (BBB) restricts the movement of soluble mediators and leukocytes from the periphery to the central nervous system (CNS). Leukocyte entry into the CNS is nonetheless an early event in multiple sclerosis (MS), an inflammatory disorder of the CNS. Whether BBB dysfunction precedes immune cell infiltration or is the consequence of perivascular leukocyte accumulation remains enigmatic, but leukocyte migration modifies BBB permeability. Immune cells of MS subjects express inflammatory cytokines, reactive oxygen species (ROS) and enzymes that can facilitate their migration to the CNS by influencing BBB function, either directly or indirectly. In this review, we describe how immune cells from the peripheral blood overcome the BBB and promote CNS inflammation in MS through BBB disruption.

PM 2.5 collected in a residential area induced Th1-type inflammatory responses with oxidative stress in mice

Epidemiologists have tried to establish an association between human health and exposure to particulate matter (PM). In addition, many researchers have investigated the adverse effects of PM as a trigger of cardiovascular and pulmonary diseases. It is known that a number of environmental contaminants are attached to PM and the toxicity of PM may depend on the sources. We investigated the effects of PM collected in a residential area of Seoul on the immunotoxic responses including cytokine production in BAL fluid and in blood after a single intratracheal instillation in mice with the characterization of physico-chemical properties of PM 2.5 samples. As results, pro-inflammatory cytokines (IL-1, TNF-α, and IL-6), Th0-type cytokine (IL-2), and Th1-type cytokines (IL-12 and IFN-γ) were increased by a dose-dependent manner. Cell infiltration in the alveolar area and phagocytosis by macrophage was observed until day 28 after instillation. The expressions of oxidative stress-related genes (HSP 1a, HSP 8, and SOD) and tissue damage-related genes (MMP-15, -19, and Slpi) were time-dependently increased. PM 2.5 also induced an increase of T cell distribution in lymphocyte and decreased the CD4+/CD8+ ratio. Based on the results, we suggest that PM 2.5 collected in a residential area of Seoul may induce Th1 type-inflammatory responses with oxidative stress and trigger adverse effects in human health.

Adenosine triphosphate-binding cassette transporters mediate chemokine (C-C motif) ligand 2 secretion from reactive astrocytes: relevance to multiple sclerosis pathogenesis

Adenosine triphosphate-binding cassette efflux transporters are highly expressed at the blood-brain barrier and actively hinder passage of harmful compounds, thereby maintaining brain homoeostasis. Since, adenosine triphosphate-binding cassette transporters drive cellular exclusion of potential neurotoxic compounds or inflammatory molecules, alterations in their expression and function at the blood-brain barrier may contribute to the pathogenesis of neuroinflammatory disorders, such as multiple sclerosis. Therefore, we investigated the expression pattern of different adenosine triphosphate-binding cassette efflux transporters, including P-glycoprotein, multidrug resistance-associated proteins-1 and -2 and breast cancer resistance protein in various well-characterized human multiple sclerosis lesions. Cerebrovascular expression of P-glycoprotein was decreased in both active and chronic inactive multiple sclerosis lesions. Interestingly, foamy macrophages in active multiple sclerosis lesions showed enhanced expression of multidrug resistance-associated protein-1 and breast cancer resistance protein, which coincided with their increased function of cultured foamy macrophages. Strikingly, reactive astrocytes display an increased expression of P-glycoprotein and multidrug resistance-associated protein-1 in both active and inactive multiple sclerosis lesions, which correlated with their enhanced in vitro activity on astrocytes derived from multiple sclerosis lesions. To investigate whether adenosine triphosphate-binding cassette transporters on reactive astrocytes can contribute to the inflammatory process, primary cultures of reactive human astrocytes were generated through activation of Toll-like receptor-3 to mimic the astrocytic phenotype as observed in multiple sclerosis lesions. Notably, blocking adenosine triphosphate-binding cassette transporter activity on reactive astrocytes inhibited immune cell migration across a blood-brain barrier model in vitro, which was due to the reduction of astrocytic release of the chemokine (C-C motif) ligand 2. Our data point towards a novel (patho)physiological role for adenosine triphosphate-binding cassette transporters, suggesting that limiting their activity by dampening astrocyte activation may open therapeutic avenues to diminish tissue damage during multiple sclerosis pathogenesis.

Matrix metalloproteinases and neurotrauma: evolving roles in injury and reparative processes

Matrix metalloproteinases (MMPs) are involved in a wide range of proteolytic events in fetal development and normal tissue remodeling as well as wound healing and inflammation. In the CNS, they have been implicated in a variety of neurodegenerative diseases ranging from multiple sclerosis to Alzheimer disease and are integral to stroke-related cell damage. Although studies implicate increased activity of MMPs in pathogenesis in the CNS, there is also a growing literature to support their participation in events that support recovery processes. Here the authors provide a brief overview of MMPs and their regulation, address their complex roles following traumatic injuries to the adult and developing CNS, and consider their time- and context-dependent signatures that influence both injury and reparative processes.

MMP19 is upregulated during melanoma progression and increases invasion of melanoma cells

During the progression of cutaneous melanomas, matrix metalloproteinases (MMPs) facilitate the tumour cells to traverse the basement membrane and invade the dermis. In this study, we analysed the expression of MMP19 in the course of melanoma progression. Although MMP19 was absent in melanocytes and melanoma cells of early stages of melanoma development, its expression was strongly upregulated in the neighbouring keratinocytes that may facilitate the vertical outgrowth of melanoma cells. In contrast to early stages, MMP19 was upregulated during the vertical growth phase of melanoma and in metastases. The upregulation of MMP19 in melanoma of Clark levels IV and V correlates with that of MMP2 and also simultaneously with ceased expression of E-cadherin. To reveal whether MMP19 facilitates the invasion of melanomas, we examined adhesion and migratory capacity of selected melanoma cell lines. Melanoma cell lines with low expression of MMP19 exhibited increased adhesion to various substrates and lower migration in comparison with the cell line with higher expression of MMP19. Moreover, ectopic expression of MMP19 could restore the migratory capacity of melanoma cells with low endogenous level of MMP19. These results suggest that the increase of MMP19 expression hallmarks the progression of cutaneous melanoma and might augment melanoma growth by promoting the invasion of tumour cells.

Extracellular matrix in multiple sclerosis lesions: Fibrillar collagens, biglycan and decorin are upregulated and associated with infiltrating immune cells

Extracellular matrix (ECM) proteins can modify immune reactions, e.g. by sequestering or displaying growth factors and by interacting with immune and glial cells. Here we quantified by quantitative polymerase chain reaction (qPCR) expression of 50 ECM components and 34 ECM degrading enzymes in multiple sclerosis (MS) active and inactive white matter lesions. COL1A1, COL3A1, COL5A1 and COL5A2 chains were induced strongly in active lesions and even more in inactive lesions. These chains interact to form collagen types I, III and V, which are fibrillar collagens. Biglycan and decorin, which can decorate fibrillar collagens, were also induced strongly. The fibrillar collagens, biglycan and decorin were largely found between the endothelium and astrocytic glia limitans in the perivascular space where they formed a meshwork which was closely associated with infiltrating immune cells. In active lesions collagen V was also seen in the heavily infiltrated parenchyma. Fibrillar collagens I and III inhibited in vitro human monocyte production of CCL2 (MCP-1), an inflammatory chemokine involved in recruitment of immune cells. Together, ECM changes in lesions with different activities were quantified and proteins forming a perivascular fibrosis were identified. Induced fibrillar collagens may contribute to limiting enlargement of MS lesions by inhibiting the production of CCL2 by monocytes.

Inflammatory proprotein convertase-matrix metalloproteinase proteolytic pathway in antigen-presenting cells as a step to autoimmune multiple sclerosis

Multiple sclerosis (MS) is a disease of the central nervous system with autoimmune etiology. Susceptibility to MS is linked to viral and bacterial infections. Matrix metalloproteinases (MMPs) play a significant role in the fragmentation of myelin basic protein (MBP) and demyelination. The splice variants of the single MBP gene are expressed in the oligodendrocytes of the central nervous system (classic MBP) and in the immune cells (Golli-MBPs). Our data suggest that persistent inflammation caused by environmental risk factors is a step to MS. We have discovered biochemical evidence suggesting the presence of the inflammatory proteolytic pathway leading to MS. The pathway involves the self-activated furin and PC2 proprotein convertases and membrane type-6 MMP (MT6-MMP/MMP-25) that is activated by furin/PC2. These events are followed by MMP-25 proteolysis of the Golli-MBP isoforms in the immune system cells and stimulation of the specific autoimmune T cell clones. It is likely that the passage of these autoimmune T cell clones through the disrupted blood-brain barrier to the brain and the recognition of neuronal, classic MBP causes inflammation leading to the further up-regulation of the activity of the multiple individual MMPs, the massive cleavage of MBP in the brain, demyelination, and MS. In addition to the cleavage of Golli-MBPs, MMP-25 proteolysis readily inactivates crystallin alphaB that is a suppressor of MS. These data suggest that MMP-25 plays an important role in MS pathology and that MMP-25, especially because of its restricted cell/tissue expression pattern and cell surface/lipid raft localization, is a promising drug target in MS.

Regulation of matrix metalloproteinases and their inhibitors by interferon-beta: a longitudinal study in multiple sclerosis patients

BACKGROUND

Matrix metalloproteinases (MMPs) represent a large family of proteolytic enzymes, with some members being implicated in the immunopathogenesis of multiple sclerosis (MS). Interferon (IFN)-beta is one of the current mainstays in MS therapy and known to downregulate the expression of MMP-9. However, only sparse information is available on the effects of IFN-beta on the other 20 members of the MMP family.

METHODS

This is a longitudinal analysis on the RNA expression pattern of all known MMPs and their endogenous inhibitors before and after 1 and 6 months of IFN-beta therapy. RNA expression levels were assessed in peripheral venous blood cells from 14 MS patients and 8 matched controls by real time-PCR.

RESULTS

RNA expression levels before treatment differed in part in MS patients compared to healthy controls (MMP-9, MMP-14, MMP-19, TIMP-1, TIMP-2). Some of the MMPs responded to therapy specifically (MMP-8, MMP-9, MMP-19), whereas others remained unchanged over time.

CONCLUSIONS

These data suggest that MMPs may differ in their expression levels in MS patients and that this group of enzymes is differentially regulated during the treatment with IFN-beta in MS for at least 6 months.

Matrix metalloproteinase proteolysis of the myelin basic protein isoforms is a source of immunogenic peptides in autoimmune multiple sclerosis

Background

Matrix metalloproteinases (MMPs) play a significant role in the fragmentation of myelin basic protein (MBP) and demyelination leading to autoimmune multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). The classic MBP isoforms are predominantly expressed in the oligodendrocytes of the CNS. The splice variants of the single MBP gene (Golli-MBP BG21 and J37) are widely expressed in the neurons and also in the immune cells. The relative contribution of the individual MMPs to the MBP cleavage is not known.

Methodology/Principal Findings

To elucidate which MMP plays the primary role in cleaving MBP, we determined the efficiency of MMP-2, MMP-8, MMP-9, MMP-10, MMP-12, MT1-MMP, MT2-MMP, MT3-MMP, MT4-MMP, MT5-MMP and MT6-MMP in the cleavage of the MBP, BG21 and J37 isoforms in the in vitro cleavage reactions followed by mass-spectroscopy analysis of the cleavage fragments. As a result, we identified the MMP cleavage sites and the sequence of the resulting fragments. We determined that MBP, BG21 and J37 are highly sensitive to redundant MMP proteolysis. MT6-MMP (initially called leukolysin), however, was superior over all of the other MMPs in cleaving the MBP isoforms. Using the mixed lymphocyte culture assay, we demonstrated that MT6-MMP proteolysis of the MBP isoforms readily generated, with a near quantitative yield, the immunogenic N-terminal 1–15 MBP peptide. This peptide selectively stimulated the proliferation of the PGPR7.5 T cell clone isolated from mice with EAE and specific for the 1–15 MBP fragment presented in the MHC H-2^U context.

Conclusions/Significance

In sum, our biochemical observations led us to hypothesize that MT6-MMP, which is activated by furin and associated with the lipid rafts, plays an important role in MS pathology and that MT6-MMP is a novel and promising drug target in MS especially when compared with other individual MMPs.

Severe oxidative damage in multiple sclerosis lesions coincides with enhanced antioxidant enzyme expression

Reactive oxygen species (ROS) and subsequent oxidative damage may contribute to the formation and persistence of multiple sclerosis (MS) lesions by acting on distinct pathological processes. ROS initiate lesion formation by inducing blood-brain barrier disruption, enhance leukocyte migration and myelin phagocytosis, and contribute to lesion persistence by mediating cellular damage to essential biological macromolecules of vulnerable CNS cells. Relatively little is known about which CNS cell types are affected by oxidative injury in MS lesions. Here, we show the presence of extensive oxidative damage to proteins, lipids, and nucleotides occurring in active demyelinating MS lesions, predominantly in reactive astrocytes and myelin-laden macrophages. Oxidative stress can be counteracted by endogenous antioxidant enzymes that confer protection against oxidative damage. Here, we show that antioxidant enzymes, including superoxide dismutase 1 and 2, catalase, and heme oxygenase 1, are markedly upregulated in active demyelinating MS lesions compared to normal-appearing white matter and white matter tissue from nonneurological control brains. Particularly, hypertrophic astrocytes and myelin-laden macrophages expressed an array of antioxidant enzymes. Enhanced antioxidant enzyme production in inflammatory MS lesions may reflect an adaptive defense mechanism to reduce ROS-induced cellular damage.

Brain extracellular matrix in neurodegeneration

The role of extracellular matrix (ECM) in neurological development, function and degeneration has evolved from a simplistic physical adhesion to a system of intricate cellular signaling. While most cells require ECM adhesion to survive, it is now clear that differentiated function is intimately dependent upon cellular interaction with the ECM. Therefore, it is not surprising that the ECM is increasingly found to be involved in the enigmatic process of neurodegeneration. Descriptive studies of human neurodegenerative disorders and experimental studies of animal models of neurodegeneration have begun to define potential mechanisms of ECM disruption that can lead to synaptic and neuronal loss.

MMP19 is essential for T cell development and T cell-mediated cutaneous immune responses

Matrix metalloproteinase-19 (MMP19) affects cell proliferation, adhesion, and migration in vitro but its physiological role in vivo is poorly understood. To determine the function of MMP19, we generated mice deficient for MMP19 by disrupting the catalytic domain of mmp19 gene. Although MMP19-deficient mice do not show overt developmental and morphological abnormalities they display a distinct physiological phenotype. In a model of contact hypersensitivity (CHS) MMP19-deficient mice showed impaired T cell-mediated immune reaction that was characterized by limited influx of inflammatory cells, low proliferation of keratinocytes, and reduced number of activated CD8(+) T cells in draining lymph nodes. In the inflamed tissue, the low number of CD8(+) T cells in MMP19-deficient mice correlated with low amounts of proinflammatory cytokines, especially lymphotactin and interferon-inducible T cell alpha chemoattractant (I-TAC). Further analyses showed that T cell populations in the blood of immature, unsensitized mice were diminished and that this alteration originated from an altered maturation of thymocytes. In the thymus, thymocytes exhibited low proliferation rates and the number of CD4(+)CD8(+) double-positive cells was remarkably augmented. Based on the phenotype of MMP19-deficient mice we propose that MMP19 is an important factor in cutaneous immune responses and influences the development of T cells.

Astrocytes--friends or foes in multiple sclerosis?

In multiple sclerosis (MS), the presence of demyelinating plaques has concentrated researchers' minds on the role of the oligodendrocyte in its pathophysiology. Recently, with the rediscovery of early and widespread loss of axons in the disease, new emphasis has been put on the role of axons and axon-oligodendrocyte interactions in MS. Despite the fact that, in 1904, Müller claimed that MS was a disease of astrocytes, more recently, astrocytes have taken a back seat, except as the cells that form the final glial scar after all hope of demyelination is over. However, perhaps it is time for the return of the astrocyte to popularity in the pathogenesis of MS, with recent reports on the dual role of astrocytes in aiding degeneration and demyelination, by promoting inflammation, damage of oligodendrocytes and axons, and glial scarring, but also in creating a permissive environment for remyelination by their action on oligodendrocyte precursor migration, oligodendrocyte proliferation, and differentiation. We review these findings to try to provide a cogent view of astrocytes in the pathology of MS.

The extracellular matrix in multiple sclerosis pathology

The extracellular matrix (ECM) is a substrate upon which cells migrate, proliferate and differentiate. It is involved in the maintenance of cytoarchitecture, regulation of homeostasis, and it influences interactions between cells and molecules via specific receptors. Although a substantial body of knowledge has accumulated concerning the role of the ECM in peripheral tissues, little is known of the structure and function of the ECM in the CNS. However, marked changes in the expression of ECM constituents have been documented in various neurological disorders, including multiple sclerosis. This review focuses on the structure and function of the ECM in the CNS and in particular on the occurrence and involvement of ECM changes in the pathology of multiple sclerosis. Increased knowledge of the expression and functional role of ECM proteins in the CNS can lead to a better understanding of complex neurobiological processes both under normal as well as pathological conditions.

Interleukin 7 receptor alpha chain (IL7R) shows allelic and functional association with multiple sclerosis

Multiple sclerosis is a demyelinating neurodegenerative disease with a strong genetic component. Previous genetic risk studies have failed to identify consistently linked regions or genes outside of the major histocompatibility complex on chromosome 6p. We describe allelic association of a polymorphism in the gene encoding the interleukin 7 receptor alpha chain (IL7R) as a significant risk factor for multiple sclerosis in four independent family-based or case-control data sets (overall P = 2.9 x 10(-7)). Further, the likely causal SNP, rs6897932, located within the alternatively spliced exon 6 of IL7R, has a functional effect on gene expression. The SNP influences the amount of soluble and membrane-bound isoforms of the protein by putatively disrupting an exonic splicing silencer.