Matrix metalloproteinases, tumor necrosis factor and multiple sclerosis: an overview

Matrix metalloproteinase-9 and tissue inhibitors of metalloproteinases 1 in influenza-associated encephalopathy

Matrix metalloproteinase-9 (MMP-9) and tissue inhibitors of metalloproteinases 1 (TIMP-1) play important roles in the function of the blood-brain barrier. Serum MMP-9 and TIMP-1 concentrations were determined in influenza virus infection with or without neurologic complications. Our results suggest that an imbalance between MMP-9 and TIMP-1 damages the blood-brain barrier and promotes febrile seizure or encephalopathy in influenza virus infection.

Inhibition of host extracellular matrix destructive enzyme production and activity by a high-molecular-weight cranberry fraction

BACKGROUND AND OBJECTIVE

Periodontal diseases are a group of inflammatory disorders that are initiated by specific gram-negative bacteria and lead to connective tissue destruction. Proteolytic enzymes, including matrix metalloproteinases (MMPs) and elastase, produced by resident and inflammatory cells in response to periodontopathogens and their products, play a major role in gingival tissue destruction. The aim of this study was to investigate the effect of a high-molecular-weight fraction prepared from cranberry juice concentrate on MMP-3, MMP-9 and elastase activities, as well as on MMP production by human cells stimulated with lipopolysaccharide of Actinobacillus actinomycetemcomitans.

MATERIAL AND METHODS

MMP-3 and MMP-9 production by gingival fibroblasts and macrophages treated with the cranberry fraction and then stimulated with lipopolysaccharide was measured by enzyme-linked immunosorbent assay. MMP-3, MMP-9 and elastase activities in the presence of the cranberry fraction were evaluated using colorimetric or fluorogenic substrates. The changes in expression and phosphorylation state of fibroblast intracellular signaling proteins induced by A. actinomycetemcomitans lipopolysaccharide and the cranberry fraction were characterized by antibody microarrays.

RESULTS

The lipopolysaccharide-induced MMP-3 and MMP-9 responses of fibroblasts and macrophages were inhibited in a dose-dependent manner by the cranberry fraction. This fraction was found to inhibit fibroblast intracellular signaling proteins, a phenomenon that may lead to a down-regulation of activating protein-1 activity. MMP-3, MMP-9 and elastase activities were also efficiently inhibited by the cranberry fraction, even when it was used at low concentrations.

CONCLUSION

These results suggest that cranberry compounds offer promising perspectives for the development of novel host-modulating strategies for an adjunctive treatment of periodontitis.

Advances in ischemic stroke treatment: neuroprotective and combination therapies

Thrombolysis with intravenous alteplase (recombinant tissue-type plasminogen activator) continues to be the sole recourse for acute ischemic stroke therapy, provided that patients seek treatment preferably within 3 h of stroke onset. The narrow window of efficacy, coupled with the significant risk of hemorrhage and the high mortality rate, preclude the use of alteplase beyond this time frame. Moreover, in part because of safety concerns, only a small percentage (6-15%) of eligible patients is treated with alteplase. Clearly, safer and more effective treatments that focus on improving the shortcomings of the present thrombolysis for stroke need to be identified. Therefore, newer thrombolytics are being developed with the goal of minimizing side effects, while also shortening the time of cerebral reperfusion and extending the therapeutic window of efficacy. Besides thrombolytics, new and potentially useful drugs and devices are also being studied either as monotherapeutic agents or for use in conjunction with alteplase. In animal models of stroke, neuroprotective agents that affect various components of the ischemic injury cascade that results in neurodegeneration have shown promise for the latter. Examples of such agents include spin traps that block oxidative stress, metalloprotease inhibitors that prevent vascular damage, anti-inflammatory drugs that suppress inflammation and transcranial infrared laser irradiation, which promotes recovery of function. Ideally, a successful combination of neuroprotectant (drug or device) and thrombolytic therapy for stroke would minimize the side effects of thrombolysis followed by supplementary neuroprotection thereafter.

Depression and immunity: inflammation and depressive symptoms in multiple sclerosis

There is strong evidence that depression involves alterations in multiple aspects of immunity that may contribute to the development or exacerbation of a number of medical disorders and also may play a role in the pathophysiology of depressive symptoms. Accordingly, aggressive management of depressive disorders in medically ill populations or individuals at risk for disease may improve disease outcome or prevent disease development. On the other hand, in light of data suggesting that immune processes may interact with the pathophysiologic pathways known to contribute to depression, novel approaches to the treatment of depression may target relevant aspects of the immune response. Taken together, the data provide compelling evidence that a psychoimmunologic frame of reference may have profound implications regarding the consequences and treatment of depression. In addition, this approach may be used to investigate the possibility that peripheral and central production of cytokines may account for neuropsychiatric symptoms in inflammatory diseases. This article summarizes evidence for a cytokine-mediated pathogenesis of depression and fatigue in MS. The effects of central inflammatory processes may account for some of the behavioral symptoms seen in patients who have MS that cannot be explained by psychosocial factors or CNS damage. This immune-mediated hypothesis is supported by indirect evidence from experimental and clinical studies of the effect of cytokines on behavior, which have found that both peripheral and central cytokines may cause depressive symptoms. Emerging clinical data from patients who have MS support an association of central inflammation (as measured by MRI) and inflammatory markers with depressive symptoms and fatigue. Based on the literature reviewed in this article, subtypes of MS fatigue and depression may exist that are caused by different pathogenetic mechanisms, including inflammation and CNS damage as well as psychosocial factors or predisposition. The existence of these subtypes could have important clinical implications. For example, an inflammatory depression may require different therapeutic approaches than a reactive depression in MS. Future research should aim to characterize these subtypes better with the goal of optimizing treatment.

Serum levels of matrix metalloproteinase-9 and tissue inhibitors of metalloproteinases 1 in subacute sclerosing panencephalitis

We determined the relationship between the serum concentrations of matrix metalloproteinase-9 (MMP-9) and tissue inhibitors of metalloproteinases 1 (TIMP-1) in 33 patients with subacute sclerosing panencephalitis (SSPE) to investigate the function of the blood-brain-barrier (BBB) in SSPE. Serum MMP-9 and TIMP-1 levels were measured by ELISA. Serum MMP-9 levels and MMP-9/TIMP-1 ratios of SSPE patients in Papua New Guinea (n = 24), and those in Japan (n = 9) were significantly higher than the each control (MMP-9, p = 0.0390, and p = 0.0023, respectively; MMP-9/TIMP-1, p = 0.0319, and p = 0.0009, respectively). Serum MMP-9 levels and MMP-9/TIMP-1 ratios of SSPE patients with Jabbour stage III (n = 13) were significantly higher than those with Jabbour stage II (n = 18) (p = 0.003, and p = 0.0412, respectively). There were no significant differences of serum TIMP-1 levels between the SSPE patients and controls. High serum MMP-9 and MMP-9/TIMP-1 levels will promote brain invasion through the BBB by immunocompetent cells in the blood. Our findings suggest that the balance of serum MMP-9 and TIMP-1 levels modulate the inflammatory cascade of SSPE.

Loss of flow induces leukocyte-mediated MMP/TIMP imbalance in dynamic in vitro blood-brain barrier model: role of pro-inflammatory cytokines

There is substantial evidence linking blood-brain barrier (BBB) failure during cerebral ischemia to matrix metalloproteinases (MMP). BBB function may be affected by loss of shear stress under normoxia/normoglycemia, as during cardiopulmonary bypass procedures. The present study used an in vitro flow-perfused BBB model to analyze the individual contributions of flow, cytokine levels, and circulating blood leukocytes on the release/activity of MMP-9, MMP-2, and their endogenous inhibitors, the tissue inhibitors of MMPs (TIMPs), TIMP-1, and TIMP-2. The presence of circulating blood leukocytes under normoxic/normoglycemic flow cessation/reperfusion significantly increased the luminal levels of MMP-9 and activity of MMP-2, accompanied by partial reduction of TIMP-1, complete reduction of TIMP-2 and increased BBB permeability. These changes were not observed during constant flow with circulating blood leukocytes, or after normoxic/normoglycemic or hypoxic/hypoglycemic flow cessation/reperfusion without circulating blood leukocytes. The addition of anti-IL-6 or anti-TNF-α antibody in the lumen before reperfusion suppressed the levels of MMP-9 and activity of MMP-2, had no effect on TIMP-1, and completely restored TIMP-2 and BBB integrity. Injection of TIMP-2 in the lumen before reperfusion prevented the activation of MMP-2 and BBB permeability. These data indicate that blood leukocytes and loss of flow are major factors in the activation of MMP-2, and that cytokine-mediated differential regulation of TIMP-1 and TIMP-2 may contribute significantly to BBB failure.

Oxidative stress in glaucomatous neurodegeneration: mechanisms and consequences

Reactive oxygen species (ROS) are generated as by-products of cellular metabolism, primarily in the mitochondria. Although ROS are essential participants in cell signaling and regulation, when their cellular production overwhelms the intrinsic antioxidant capacity, damage to cellular macromolecules such as DNA, proteins, and lipids ensues. Such a state of "oxidative stress" is thought to contribute to the pathogenesis of a number of neurodegenerative diseases. Growing evidence supports the involvement of oxidative stress as a common component of glaucomatous neurodegeneration in different subcellular compartments of retinal ganglion cells (RGCs). Besides the evidence of direct cytotoxic consequences leading to RGC death, it also seems highly possible that ROS are involved in signaling RGC death by acting as a second messenger and/or modulating protein function by redox modifications of downstream effectors through enzymatic oxidation of specific amino acid residues. Different studies provide cumulating evidence, which supports the association of ROS with different aspects of the neurodegenerative process. Oxidative protein modifications during glaucomatous neurodegeneration increase neuronal susceptibility to damage and also lead to glial dysfunction. Oxidative stress-induced dysfunction of glial cells may contribute to spreading neuronal damage by secondary degeneration. Oxidative stress also promotes the accumulation of advanced glycation end products in glaucomatous tissues. In addition, oxidative stress takes part in the activation of immune response during glaucomatous neurodegeneration, as ROS stimulate the antigen presenting ability of glial cells and also function as co-stimulatory molecules during antigen presentation. By discussing current evidence, this review provides a broad perspective on cellular mechanisms and potential consequences of oxidative stress in glaucoma.

Recruited leukocytes and local synthesis account for increased matrix metalloproteinase-9 activity in cerebrospinal fluid of dogs with central nervous system neoplasm

Matrix metalloproteinases (MMP) 2 and 9 are enzymes known to degrade several protein components of the extracellular matrix. In humans, increased concentrations of these enzymes have been demonstrated in the cerebrospinal fluid (CSF) of subjects affected by many neurological conditions including brain tumours; nevertheless comparative data in dogs are completely lacking. Aim of this study was to investigate these molecules in CSF of dogs diagnosed with CNS neurological diseases. Higher activity of MMP 2 and 9 was revealed in dogs with space occupying lesions of likely neoplastic origin in comparison to dogs with idiopathic epilepsy. Statistical modelling reveals that increased MMP 9 activity is mainly due to leukocytes recruitment and local synthesis.

Modulation of autocrine TNF-alpha-stimulated matrix metalloproteinase 9 (MMP-9) expression by mitogen-activated protein kinases in THP-1 monocytic cells

Matrix metalloproteinase 9 (MMP-9) is implicated in various physiological processes by its ability to degrade the extracellular matrix (ECM) and process multiple regulatory proteins. Normally, MMP-9 expression is tightly controlled in cells. Sustained or enhanced MMP-9 secretion, however, has been demonstrated to contribute to the pathophysiology of numerous diseases, including arthritis and tumor progression, rendering this enzyme a major target for clinical interventions. Here we show that constitutive MMP-9 secretion was abrogated in THP-1 monocytic leukemia cells by addition of neutralizing antibodies against tumor necrosis factor alpha (TNF-alpha) or TNF receptor type 1 (TNF-R1), as well as by inhibition of TNF-alpha converting enzyme (TACE). This indicates that MMP-9 production in these cells is maintained by autocrine stimulation, with TNF-alpha acting via TNF-R1. To investigate the intracellular signaling routes involved in MMP-9 gene transcription, cells were treated with different inhibitors of major mitogen-activated protein kinase (MAPK) pathways. Interruption of the extracellular signal-regulated kinase pathway 1/2 (ERK1/2) using PD98059 significantly downregulated constitutive MMP-9 release. In contrast, blockage of p38 kinase activity by addition of SB203580 or SB202190, as well as inhibition of c-Jun N-terminal kinase (JNK) using L-JNK-I1, clearly augmented MMP-9 expression and secretion by an upregulation of ERK1/2 phosphorylation. Moreover, exogenously added TNF-alpha augmented MMP-9 synthesis and secretion in THP-1 cells via enhancement of ERK1/2 activity. Taken together, our results indicate that ERK1/2 activity plays a pivotal role in TNF-alpha-induced MMP-9 production and demonstrate its negative modulation by p38 and JNK activity. These findings suggest ERK1/2 rather than p38 and JNK as a reasonable target to specifically block MMP-9 expression using MAPK inhibitors in therapeutic applications.

Response of glia, mast cells and the blood brain barrier, in transgenic mice expressing interleukin-3 in astrocytes, an experimental model for CNS demyelination

Transgenic mice overexpressing cytokines facilitate analysis of the effects of these immunomodulators on indigenous cells of the central nervous system. This study examines morphological aspects of demyelination and permeability changes, in a recently described transgenic model (termed GFAP-IL3). GFAP-IL3 mice develop progressive motor disease at approximately 5 months. Lesions identified after disease onset, showed activation of microglia, astroglial proliferation with phagocytosis of lipids, and immigration of macrophages and mast cells into neural parenchyma. Lymphocytes failed to appear until the later stages of the disease. Later, cerebellar and brain stem white matter contained focal demyelinating lesions with intense macrophage infiltration and a proliferative astrocytosis. Dystrophic axonal changes were noted, in addition to demyelination in heavily infiltrated lesions. Mast cells, variably present in the thalamus and meninges of wild type mice, were greatly increased at these sites in GFAP-IL3 mice. Blood-brain barrier (BBB) defects were documented with leakage of intravenously injected horseradish peroxidase. Mast cell infiltration into the CNS and their degranulation at the site of injury, may represent initial events in a spontaneous process of macrophage mediated demyelination in which glial cells and macrophages are both involved in the phagocytic process.

Matrix metalloproteinase-3: a novel signaling proteinase from apoptotic neuronal cells that activates microglia

Microglial activation and inflammation are associated with progressive neuronal apoptosis in neurodegenerative human brain disorders. We sought to investigate molecular signaling mechanisms that govern activation of microglia in apoptotic neuronal degeneration. We report here that the active form of matrix metalloproteinase-3 (MMP-3) was released into the serum-deprived media (SDM) of PC12 cells and other media of apoptotic neuronal cells within 2-6 h of treatment of the cells, and SDM and catalytic domain of recombinant MMP-3 (cMMP-3) activated microglia in primary microglia cultures as well as BV2 cells, a mouse microglia cell line. Both SDM and cMMP-3 induced generation of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), IL-1beta, and interleukin-1 receptor antagonist but not IL-12 and inducible nitric oxide synthase, which are readily induced by lipopolysaccharide, in microglia, suggesting that there is a characteristic pattern of microglial cytokine induction by apoptotic neurons. Neither glial cell line-derived neurotrophic factor nor anti-inflammatory cytokines, such as IL-10 and transforming growth factor-beta1, were induced. SDM and cMMP-3 extensively released TNF-alpha from microglia and activated the nuclear factor-kappaB pathway, and these microglial responses were totally abolished by preincubation with an MMP-3 inhibitor, NNGH [N-isobutyl-N-(4-methoxyphenylsulfonyl)-glycylhydroxamic acid]. MMP-3-mediated microglial activation mostly depended on ERK (extracellular signal-regulated kinase) phosphorylation but not much on either JNK (c-Jun N-terminal protein kinase) or p38 activation. Conditioned medium of SDM- or cMMP-3-activated BV2 cells caused apoptosis of PC12 cells. These results strongly suggest that the distinctive signal of neuronal apoptosis is the release of active form of MMP-3 that activates microglia and subsequently exacerbates neuronal degeneration. Therefore, the release of MMP-3 from apoptotic neurons may play a major role in degenerative human brain disorders, such as Parkinson's disease.

Serum matrix metalloproteinase-3 levels correlate with disease activity in relapsing-remitting multiple sclerosis

BACKGROUND

Adhesion molecules and matrix metalloproteinases (MMPs) are known to be relevant to the ongoing development and disappearance of areas of demyelination in the white matter of the CNS of multiple sclerosis (MS) patients. This study examined whether serum matrix metalloproteinase-3 (MMP-3) levels correlate with disease activity in MS.

METHODS

Serum MMP-3 levels in 47 consecutive patients with relapsing-remitting MS were measured by immunoassay every 4 weeks over a 15 month period.

RESULTS

During the study period, 48 clinical relapses occurred. Serum MMP-3 levels within 1 month of relapse were significantly higher than during the remission phase. Sequential analysis showed that serum MMP-3 levels had increased transiently at the time of clinical relapse but returned to the normal range within a month.

CONCLUSIONS

Circulatory MMP-3 levels are correlated with disease activity in relapsing-remitting MS. This may contribute to the breakdown of the blood-brain barrier at the time of relapse.

Matrix metalloproteinase-9 activity in the cerebrospinal fluid and serum of dogs with acute spinal cord trauma from intervertebral disk disease

OBJECTIVE

To detect matrix metalloproteinase (MMP)-9 in serum and CSF and determine relationships between MMP activity and severity of disease, duration of clinical signs, and duration of hospitalization in dogs with acute intervertebral disk disease (IVDD).

ANIMALS

35 dogs with acute IVDD and 8 clinically normal control dogs.

PROCEDURE

CSF and serum were collected from affected and control dogs. Zymography was used to detect MMP-9.

RESULTS

Activity of MMP-9 in CSF was detected in 6 of 35 dogs with IVDD; activity was significantly more common in dogs with duration of signs < 24 hours. Paraplegic dogs were more likely to have MMP-9 activity in the CSF than non-paraplegic dogs. No significant difference in hospitalization time was detected in dogs with IVDD between those with and without activity of MMP-9 in the CSF. Serum MMP-9 was detected more frequently in dogs with IVDD than in control dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Data were consistent with results of experimental rodent spinal cord injury studies that indicate that MMP-9 is expressed early during secondary injury.

A small compound that inhibits tumor necrosis factor-alpha-induced matrix metalloproteinase-9 upregulation

Matrix metalloproteinase-9 (MMP-9) is critically involved in the tumor invasion and metastasis processes. Since TNF-alpha plays a crucial role in the regulation of MMP-9 expression, the development of molecules capable of modulating TNF-alpha-induced signaling is an issue of concern. We identified a novel synthetic compound that inhibits TNF-alpha-induced MMP-9 upregulation in the HT1080 human fibrosarcoma cell line. The active compound SM-7368 inhibited TNF-alpha-induced MMP-9 upregulation in a concentration-dependent manner and showed maximal activity at 10 microM. SM-7368 inhibited TNF-alpha-induced MMP-9 mRNA transcript accumulation and protein expression. We also found that SM-7368 strongly inhibits TNF-alpha-induced NF-kappaB activity but not AP-1 activity. Moreover, we found that SM-7368 strongly inhibits the TNF-alpha-induced invasion of HT1080 human fibrosarcoma cell line. Taken together, our results demonstrate that SM-7368 is a synthetic compound that inhibits TNF-alpha-induced MMP-9 expression, and thus SM-7368 should be useful for the development of chemotherapies targeting TNF-alpha-mediated tumor invasion and metastasis.

Up-regulation of mRNA for matrix metalloproteinases-9 and -14 in advanced lesions of demyelinating canine distemper leukoencephalitis

Matrix metalloproteinases (MMPs) comprise a family of proteolytic zinc- and calcium-dependent enzymes that are capable of disrupting the blood-brain barrier and mediating the destruction of extracellular matrix and myelin components. MMPs are also involved in facilitating leukocyte migration into inflammatory sites of the central nervous system. To determine the cellular localization and the amount of mRNA for MMP-9, MMP-14 and a tissue inhibitor of metalloproteinases (TIMP-1) in dogs with spontaneous demyelinating distemper encephalitis, formalin-fixed paraffin-embedded cerebella were investigated by in situ hybridization using specific digoxigenin-labeled RNA probes. Additionally, immunohistochemistry was performed to characterize the different types of plaques of demyelinating leukoencephalitis. Furthermore, virus antigen and mRNA were detected by immunohistochemistry and in situ hybridization. Healthy control dogs revealed a weak signal for mRNA for MMP-9, MMP-14, and TIMP-1 in various numbers of neurons, astrocytes, microglial cells and oligodendrocytes. In the cerebella of dogs with distemper, a strong increase of both number and staining intensity of MMP-9, MMP-14, and TIMP-1 mRNA-expressing cells, mainly in subacute inflammatory lesions and chronic plaques, was observed. The number of cells expressing mRNA for MMP-9 and MMP-14 increased about two- to threefold compared to TIMP-1 mRNA-expressing cells, whereas staining intensity of individual cells was similar. In early lesions, especially astrocytes and activated macrophages/microglial cells displayed a positive signal for MMPs and TIMP-1, whereas in older lesions activated microglia/macrophages and infiltrating lymphocytes represented the main source for MMP-9, MMP-14, and TIMP-1 mRNA synthesis as revealed by double-labeling techniques. In summary, the proportionally higher increase of MMP mRNA-expressing cells might indicate an MMP/TIMP imbalance as a cause for lesion initiation and progression in demyelinating canine distemper leukoencephalitis.

Serum MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios in multiple sclerosis: relationships with different magnetic resonance imaging measures of disease activity during IFN-beta-1a treatment

Matrix metalloproteinase-9 (MMP-9) is involved in blood-brain barrier (BBB) disruption in active multiple sclerosis (MS), while MMP-2 seems to be associated with the chronic progressive phase of the disease. Recombinant interferon beta-1a (rIFNbeta-1a) is effective in restoring the BBB. We studied the relationships between serum MMP-9, MMP-2, TIMP-1 and TIMP-2 and different magnetic resonance imaging (MRI) measures of disease activity in MS patients during treatment with rIFNbeta-1a. Twenty-one relapsing-remitting (RR) MS patients underwent longitudinally simultaneous blood withdrawals and MRI (before and after standard dose (SD) and triple dose (TD) of gadolinium (Gd)) examinations before and during 48 weeks of rIFNbeta-1a (Rebif 22 mcg three times a week) treatment. Serum MMP-9, MMP-2, TIMP-1 and TIMP-2 were measured, MMP-9 to TIMP-1 and MMP-2 to TIMP-2 ratios were calculated and the numbers of Gd-SD, Gd-TD, new-Gd-SD, new-Gd-TD and new-T2 lesions counted. Serum MMP-9/TIMP-1 ratio (P < 0.0001), as well as the numbers of 'active' lesions (P ranging from 0.0004 to 0.005) decreased during treatment Moreover, serum MMP-9/TIMP-1 ratio proved to be a good positive predictor (estimate = 0.85; P < 0.05) of the numbers of MRI Gd-TD active lesions. These data confirm that serum MMP-9/TMIP-1 ratio may be viewed as a reliable marker and may be predictive of MRI activity in RR MS.

Serum amyloid A stimulates matrix-metalloproteinase-9 upregulation via formyl peptide receptor like-1-mediated signaling in human monocytic cells

In the present study, we found that serum amyloid A (SAA) stimulated matrix-metalloproteinase-9 (MMP-9) upregulation at the transcription and translational levels in THP-1 cells. SAA stimulated the activation of nuclear factor kappaB (NF-kappaB), which was required for the MMP-9 upregulation by SAA. The signaling events induced by SAA included the activation of ERK and intracellular calcium rise, which were found to be required for MMP-9 upregulation. Formyl peptide receptor like 1 (FPRL1) was found to be involved in the upregulation of MMP-9 by SAA. Among several FPRL1 agonists, including Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm), SAA selectively stimulated MMP-9 upregulation. With respect to the molecular mechanisms involved in the differential action of SAA and WKYMVm, we found that SAA could not competitively inhibit the binding of 125I-labeled WKYMVm to FPRL1. Taken together, we suggest that SAA plays a role in the modulation of inflammatory and immune responses via FPRL1, by inducing MMP-9 upregulation in human monocytic cells.

Molecular events in tendinopathy: a role for metalloproteases

Disorganized, haphazard ineffective healing is a constant feature of chronic tendinopathy. Normal tendon is composed mostly of type I collagen. Tendinopathic tendons, conversely, have a greater proportion of type III collagen, which is associated with tendon rupture. Matrix metalloproteinases (MMPs) are involved in remodelling of the extracellular matrix (ECM) of tendons, because they are either up- or down-regulated in tendinopathy. A balance between MMPs and tissue inhibitors of metalloproteinases is required to maintain tendon homeostasis. The mechanism of activation of MMPs is poorly understood, and their precise role in tendinopathy is unclear.

Ultrastructural and immunohistochemical similarities of two distinct entities; multiple sclerosis and hereditary motor sensory neuropathy

In the present study, we present the ultrastructural and immunohistochemical properties of the sural nerves of two patients, one of whom was diagnosed as having multiple sclerosis with involvement of the peripheral nervous system (PNS), and the other as having hereditary motor sensory neuropathy type-I with involvement of the central nervous system (CNS). Expression of several extracellular matrix (ECM) proteins (fibronectin, laminin, and collagen type-IV), intermediate filaments (vimentin) and S-100 protein (marker for the axon-Schwann cell interface) was investigated by means of immunohistochemical methods. In addition, the tissue samples were evaluated ultrastructurally. Immunohistochemical staining revealed increased expression of the ECM molecules mentioned above in relation with the sural nerves of the patients. We hypothesize that this enhanced expression is due to Schwann cell-axon interactions. Vimentin expression was different in Schwann cells and S-100 immunostaining was decreased near the Schwann cell-axon interface. Myelin fragmentation, axon vacuolization, onion bulbs, tomoculous formation, axonal degeneration were found to occur. These results suggest that there is active ECM reorganization in the sural nerve of these patients, and some ultrastructural changes are similar in the damaged axonal organization and in Schwann cells although the changes are not completely the same in the two patients. In conclusion, our study demonstrates that there is an association between the demyelinization process in the CNS and the PNS even though they are affected by different mechanisms.

The potential use of MMP inhibitors to treat CNS diseases

The matrix metalloproteinases (MMPs) are considered to be the physiological mediators of extracellular matrix remodelling. MMPs are involved in a variety of functions and in the nervous system, these include angiogenesis and the extension of neuronal growth cones during development. However, it has become increasingly evident that the aberrant expression of MMPs in the nervous system contributes to diseases that include among others, multiple sclerosis, malignant gliomas, Alzheimer's disease and stroke. This review highlights the evidence that MMPs are involved in diseases of the nervous system, and provides information for the potential beneficial use of MMP inhibitors in NS disorders. However, the application of MMP inhibitors to treat CNS diseases must be balanced carefully against the beneficial roles normally played by MMPs in CNS physiology or recovery.

Cytokines and major depression

In the research field of psychoneuroimmunology, accumulating evidence has indicated the existence of reciprocal communication pathways between nervous, endocrine and immune systems. In this respect, there has been increasing interest in the putative involvement of the immune system in psychiatric disorders. In the present review, the role of proinflammatory cytokines, such as interleukin (IL)-1, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma, in the aetiology and pathophysiology of major depression, is discussed. The 'cytokine hypothesis of depression' implies that proinflammatory cytokines, acting as neuromodulators, represent the key factor in the (central) mediation of the behavioural, neuroendocrine and neurochemical features of depressive disorders. This view is supported by various findings. Several medical illnesses, which are characterised by chronic inflammatory responses, e.g. rheumatoid arthritis, have been reported to be accompanied by depression. In addition, administration of proinflammatory cytokines, e.g. in cancer or hepatitis C therapies, has been found to induce depressive symptomatology. Administration of proinflammatory cytokines in animals induces 'sickness behaviour', which is a pattern of behavioural alterations that is very similar to the behavioural symptoms of depression in humans. The central action of cytokines may also account for the hypothalamic-pituitary-adrenal (HPA) axis hyperactivity that is frequently observed in depressive disorders, as proinflammatory cytokines may cause HPA axis hyperactivity by disturbing the negative feedback inhibition of circulating corticosteroids (CSs) on the HPA axis. Concerning the deficiency in serotonergic (5-HT) neurotransmission that is concomitant with major depression, cytokines may reduce 5-HT levels by lowering the availability of its precursor tryptophan (TRP) through activation of the TRP-metabolising enzyme indoleamine-2,3-dioxygenase (IDO). Although the central effects of proinflammatory cytokines appear to be able to account for most of the symptoms occurring in depression, it remains to be established whether cytokines play a causal role in depressive illness or represent epiphenomena without major significance.

Hormone regulation of microglial cell activation: relevance to multiple sclerosis

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of proteins. The role of PPARs in regulating the transcription of genes involved in glucose and lipid metabolism has been extensively characterized. Interestingly, PPARs have also been demonstrated to mediate inflammatory responses. Microglia participate in pathology associated with multiple sclerosis (MS). Upon activation, microglia produce molecules including NO and TNF-alpha that can be toxic to CNS cells including myelin-producing oligodendrocytes and neurons, which are compromised in the course of MS. Previously, we and others demonstrated that PPAR-gamma agonists including 15d-PGJ(2) are effective in the treatment of experimental autoimmune encephalomyelitis (EAE), an animal model of MS. PPAR-gamma modulation of EAE may occur, at least in part, by inhibition of microglial cell activation. Here, we indicate that 15d-PGJ(2) is a more potent inhibitor of microglial activation than thiazolidinediones, which are currently used to treat diabetes. Furthermore, 15d-PGJ(2) acts cooperatively with 9-cis retinoic acid, the ligand for the retinoid X receptor (RXR), in inhibiting microglial cell activation. This suggests that 15d-PGJ(2) and 9-cis RA inhibit cell activation through the formation of PPAR-gamma/RXR heterodimers. Interestingly, PGA(2), which like 15d-PGJ(2) is a cyclopentenone prostaglandin, but which unlike 15d-PGJ(2) does not bind PPAR-gamma, is a potent inhibitor of microglial cell activation. Collectively, these studies suggest that 15d-PGJ(2) inhibits microglial cell activation by PPAR-gamma-dependent as well as PPAR-gamma-independent mechanisms. The studies further suggest that the PPAR-gamma agonist 15d-PGJ(2) in combination with retinoids may be effective in the treatment of MS.

Carnosol inhibits the invasion of B16/F10 mouse melanoma cells by suppressing metalloproteinase-9 through down-regulating nuclear factor-kappaB and c-Jun

Carnosol, a constant constituent of Rosmarinus officinalis extracts, is a phenolic diterpene shown to have antioxidant and anticarcinogen properties. In our studies, carnosol inhibited the invasion of highly metastatic mouse melanoma B16/F10 cells in vitro. First, the antimetastatic potentials of carnosol were examined by soft agar colony formation assay. Second, carnosol dose-dependently inhibited B16/F10 cell migration and invasion by in vitro transwell assay. Third, the decreasing activity of metalloproteinase was observed by zymographic assay. The result revealed that the treatment of carnosol could diminish the activity of MMP-9 more than MMP-2. Next, we analyzed the amounts of MMP-9 and MMP-2 proteins in the cells. The data indicated MMP-9 protein was also suppressed by carnosol in the same manner. In accordance with the above data, the results of reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed a reduced level of MMP-9 mRNA. Furthermore, carnosol significantly inhibited the tyrosine phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, AKT, p38, JNK and inhibition of activation of transcription factors NFkappa-B and c-Jun. These results lead us to conclude that carnosol could restrict the invasive ability of B16/F10 mouse melanoma cells by reducing MMP-9 expression and activity through suppressing (ERK) 1/2, AKT, p38, and JNK signaling pathway and inhibition of NF-kappaB and AP-1 binding activity. Taken together, these results indicate that carnosol targets MMP-mediated cellular events in cancer cells and provides a new mechanism for its anticancer activity.

Molecular mechanisms in Schwann cell survival and death during peripheral nerve development, injury and disease

The mechanisms determining the fate of Schwann cells during disease and injury of the adult mammalian peripheral nervous system (PNS) are becoming defined by current advances in molecular neurobiology. It is now apparent that the molecular pathways which regulate the production of the mature myelinating Schwann cell during development may also apply to degenerative and regenerative mechanisms following PNS disease. This review outlines neurobiological responses of Schwann cells during development, injury and disease in order to define the molecular pathways which regulate these crucial events. These mechanisms have implications for our attempts to intervene pharmacologically during pathologies of the PNS.

Interferon-beta inhibits the expression of metalloproteinases in rat glial cell cultures: implications for multiple sclerosis pathogenesis and treatment

Matrix metalloproteinases (MMPs) have been identified as mediators of brain injury in multiple sclerosis (MS) and it has recently been reported that treatment of MS patients with interferon-beta (IFN-beta) reduces MMP-9 serum levels and in vitro release from monocytes. We investigated whether IFN-beta is able to modulate the expression of MMPs in glial cell cultures. Rat microglial and astrocyte cultures were treated with different doses of IFN-beta, then activated by exposure to LPS. In another set of experiments cells were simultaneously activated with LPS and treated with IFN-beta. Culture supernatants collected from astrocytes and microglia were subjected to zymography for the assessment of MMP-2 and MMP-9. Increased amounts of MMP-9 and MMP-2 were observed in supernatants from LPS-treated astrocytes in comparison with supernatants from nontreated control cells. MMP-9 also increased in LPS-treated microglia. The treatment of astrocytes and microglia with IFN-beta inhibited dose-dependently the expression of both MMP-2 and MMP-9 in LPS-treated astrocytes and of MMP-9 in LPS-treated microglia. These results demonstrate a modulating effect of IFN-beta on the release of MMPs from CNS cells. This effect represents an additional mechanism by which IFN-beta, may decrease the development of new CNS lesions in the course of MS.

Autoimmunity gene expression portrait: specific signature that intersects or differentiates between multiple sclerosis and systemic lupus erythematosus

Autoimmune diseases are either tissue-specific like multiple sclerosis (MS) or multisystemic like systemic lupus erythematosus (SLE), although clinically both exhibit common features. To gain insight into the properties of the genes involved in each disease we have investigated the gene expression signature of peripheral blood mononuclear cells (PBMC) in MS and SLE in comparison to healthy subjects. Total RNA was purified, hybridized to Genechip array and analysed in 36 subjects (13 relapsing-remitting MS patients, five SLE patients and 18 age-matched healthy subjects that served as controls). Additional blood samples from 15 relapsing-remitting MS patients, 8 SLE patients and 10 healthy subjects were used for confirmation of microarray gene expression findings by ELISA and RT-PCR. MS and SLE patients demonstrated a common gene expression autoimmune signature of 541 genes which differentiated them from healthy subjects. The autoimmune signature included genes that encode proteins involved in apoptosis, cell cycle, inflammation and regulation of matrix metalloproteinase pathways. Specifically, decreased TIMP1 gene expression in the autoimmunity signature suggests increased MMP activity in target tissues as a result of the lack of feedback mechanism. An additional different disease specific signature identified the gene expression pattern for MS (1031 genes), mainly associated with over-expression of adhesion molecules and down-expression of heat shock proteins; the SLE specific signature (1146 genes) mainly involved DNA damage/repair pathways that result in production of nuclear autoantibodies. These results provide insights into the genetic pathways underlying autoimmune diseases, and identify specific disease-associated signatures that may enable targetted disease-related specific therapies to be developed.

Synthesis and evaluation of novel oxazoline MMP inhibitors

MMP inhibitors with novel oxazoline zinc binding groups have been synthesized and evaluated. Selectivity for the inhibition of MMP-9 over MMP-1, MMP-2, and MMP-12 has been achieved in several cases.

Cortical spreading depression activates and upregulates MMP-9

Cortical spreading depression (CSD) is a propagating wave of neuronal and glial depolarization and has been implicated in disorders of neurovascular regulation such as stroke, head trauma, and migraine. In this study, we found that CSD alters blood-brain barrier (BBB) permeability by activating brain MMPs. Beginning at 3-6 hours, MMP-9 levels increased within cortex ipsilateral to the CSD, reaching a maximum at 24 hours and persisting for at least 48 hours. Gelatinolytic activity was detected earliest within the matrix of cortical blood vessels and later within neurons and pia arachnoid (> or =3 hours), particularly within piriform cortex; this activity was suppressed by injection of the metalloprotease inhibitor GM6001 or in vitro by the addition of a zinc chelator (1,10-phenanthroline). At 3-24 hours, immunoreactive laminin, endothelial barrier antigen, and zona occludens-1 diminished in the ipsilateral cortex, suggesting that CSD altered proteins critical to the integrity of the BBB. At 3 hours after CSD, plasma protein leakage and brain edema developed contemporaneously. Albumin leakage was suppressed by the administration of GM6001. Protein leakage was not detected in MMP-9-null mice, implicating the MMP-9 isoform in barrier disruption. We conclude that intense neuronal and glial depolarization initiates a cascade that disrupts the BBB via an MMP-9-dependent mechanism.

Cortical spreading depression activates and upregulates MMP-9

Cortical spreading depression (CSD) is a propagating wave of neuronal and glial depolarization and has been implicated in disorders of neurovascular regulation such as stroke, head trauma, and migraine. In this study, we found that CSD alters blood-brain barrier (BBB) permeability by activating brain MMPs. Beginning at 3-6 hours, MMP-9 levels increased within cortex ipsilateral to the CSD, reaching a maximum at 24 hours and persisting for at least 48 hours. Gelatinolytic activity was detected earliest within the matrix of cortical blood vessels and later within neurons and pia arachnoid (> or =3 hours), particularly within piriform cortex; this activity was suppressed by injection of the metalloprotease inhibitor GM6001 or in vitro by the addition of a zinc chelator (1,10-phenanthroline). At 3-24 hours, immunoreactive laminin, endothelial barrier antigen, and zona occludens-1 diminished in the ipsilateral cortex, suggesting that CSD altered proteins critical to the integrity of the BBB. At 3 hours after CSD, plasma protein leakage and brain edema developed contemporaneously. Albumin leakage was suppressed by the administration of GM6001. Protein leakage was not detected in MMP-9-null mice, implicating the MMP-9 isoform in barrier disruption. We conclude that intense neuronal and glial depolarization initiates a cascade that disrupts the BBB via an MMP-9-dependent mechanism.

A1 adenosine receptor upregulation and activation attenuates neuroinflammation and demyelination in a model of multiple sclerosis

The neuromodulator adenosine regulates immune activation and neuronal survival through specific G-protein-coupled receptors expressed on macrophages and neurons, including the A1 adenosine receptor (A1AR). Here we show that A1AR null (A1AR-/-) mice developed a severe progressive-relapsing form of experimental allergic encephalomyelitis (EAE) compared with their wild-type (A1AR+/+) littermates. Worsened demyelination, axonal injury, and enhanced activation of microglia/macrophages were observed in A1AR-/- animals. In addition, spinal cords from A1AR-/- mice demonstrated increased proinflammatory gene expression during EAE, whereas anti-inflammatory genes were suppressed compared with A1AR+/+ animals. Macrophages from A1AR-/- animals exhibited increased expression of the proinflammatory genes, interleukin-1beta, and matrix metalloproteinase-12 on immune activation when matched with A1AR+/+ control cells. A1AR-/- macrophage-derived soluble factors caused significant oligodendrocyte cytotoxicity compared with wild-type controls. The A1AR was downregulated in microglia in A1AR+/+ mice during EAE accompanied by neuroinflammation, which recapitulated findings in multiple sclerosis (MS) patients. Caffeine treatment augmented A1AR expression on microglia, with ensuing reduction of EAE severity, which was further enhanced by concomitant treatment with the A1AR agonist, adenosine amine congener. Thus, modulation of neuroinflammation by the A1AR represents a novel mechanism that provides new therapeutic opportunities for MS and other demyelinating diseases.

Developmental expression of matrix metalloproteinases 2 and 9 and their potential role in the histogenesis of the cerebellar cortex

The development of the cerebellar cortex depends on intrinsic genetic programs and orchestrated cell-cell/cell-matrix interactions. Matrix metalloproteinases (MMPs) are proteolytic enzymes that play an important role in these interactions. MMP-2 and MMP-9 are involved in diverse neuronal functions including migration, process extension, and synaptic plasticity. We investigated the spatiotemporal pattern of expression/activity of MMP-2/MMP-9 in the developing cerebellum and their role in the histogenesis of the cerebellar cortex. The levels of transcripts of MMP-2/MMP-9 were measured with real-time quantitative polymerase chain reaction. An initial decrease in MMP-2/MMP-9 transcripts was observed between postnatal days 3 (PD3) and PD6, and the mRNA levels remained relatively constant thereafter. Zymographic analysis revealed that the expression/activity of MMP-2/MMP-9 persisted longer than their transcripts; the downregulation occurred around PD9, suggesting a mechanism of translational or post-translational regulation. The gelatinase activity was localized in the external granule layer (EGL) and the internal granule layer during PD3-PD12. The immunoreactivity of MMP-2 was mainly localized in the EGL, the Bergmann glial fibers, and the Purkinje cell layer (PCL), whereas MMP-9 immunoreactivity was detected intensively in the PCL and the extracellular space of the molecular layer. Expression of MMP-9 was relatively weak in the EGL. The immunoreactivity of MMP-2/MMP-9 became undetectable after PD21. A similar expression pattern of MMP-2/MMP-9 was observed in organotypic cerebellar slice cultures. Exposure of organotypic slices to a specific MMP-2/MMP-9 inhibitor significantly increased the thickness of the EGL and concurrently decreased the number of migrating granule neurons in the molecular layer. Thus, MMP-2 and MMP-9 play a role in the postnatal cerebellar morphogenesis.

Increase of matrix metalloproteinase-9 in peripheral blood of multiple sclerosis patients treated with high doses of methylprednisolone

Matrix metalloproteinases (MMPs) are believed to play a role in the pathogenesis of multiple sclerosis (MS). As methylprednisolone is the treatment of choice for a relapse, we investigated the effect of methylprednisolone on blood levels of MMPs. Baseline TIMP-1 and MMP-2 levels were lower in MS patients than in healthy controls. MMP-9 levels tended to be elevated. During therapy, MMP-9 levels demonstrate a dose-dependent increase. No effect was noted on TIMP-1 and MMP-2 levels. The short-lived increase of MMP-9 plasma levels may be at least in part due to an activation and an increase of granulocytes and monocytes by methylprednisolone.

Synthetic retinoids as inducers of apoptosis in ovarian carcinoma cell lines

Apoptosis is also known as programmed cell death. Apoptosis plays an essential role in maintaining normal tissue and cell physiology in multicellular organisms. Clearance of aberrant or pre-cancerous cells occurs through the induction of apoptosis. It has been reported that many tumors and tumor cell lines have dysfunctional apoptosis signaling, causing these tumors to escape immune monitoring and internal cellular control mechanisms. One potential cause of this dysfunctional apoptosis is the tumor suppressor p53, an important regulator of growth arrest and apoptosis that is mutated in over 50% of all cancers. Retinoids have great potential in the areas of cancer therapy and chemoprevention. While some tumor cells are sensitive to the growth inhibitory effects of natural retinoids such as all-trans-retinoic acid (ATRA), many ovarian tumor cells are not. 6-[3-(1-Admantyl)]-4-hydroxyphenyl]-2-naphthalene carboxylic acid (CD437) and fenretinide N-[4-hydroxyphenyl] retinamide (4-HPR) are conformationally restricted synthetic retinoids that induce growth arrest and apoptosis in both ATRA-sensitive and ATRA-resistant ovarian tumor cell lines. Recently, we have identified the molecular pathways of apoptosis induced by treatment of ovarian carcinoma cells with mutated p53 by CD437 and 4-HPR.

Expression of matrix metalloproteinases in vasculitic neuropathy

The aim of this study was to investigate the expression pattern and cellular source of matrix metalloproteinases (MMP) in vasculitic neuropathy. Matrix metalloproteinases are endopeptidases degrading components of extracellular matrix proteins, and they have been implicated in the pathogenesis of inflammatory demyelination. They are induced by cytokines, secreted by inflammatory cells, and enhance T cell migration. Vasculitic neuropathy occurs as a component of systemic vasculitis or as an isolated angiitis of the peripheral nervous system, and T cell-mediated inflammation is detected in its pathogenesis. Nerve biopsy sections of eight patients with nonsystemic vasculitic neuropathy (NSVN) and four with systemic vasculitic neuropathy were examined for the presence of CD4+, CD8+, and CD68+ cells and immunohistochemically for MMP-2 and MMP-9 expression. Nerve biopsies of eight patients with noninflammatory neuropathy were used as a control group. Semiquantitative polymerase chain reaction analysis was performed to detect MMP-2 and MMP-9 mRNA. The predominant cells were CD8+ and CD68+ T cells. Expression of MMP-9, but not MMP-2, was increased in perivascular inflammatory infiltrate in nerve tissues of vasculitic neuropathy patients. This MMP-9 expression correlated positively with immunostaining of CD8+ T cells. No difference was detected between immunostaining patterns of nonsystemic and systemic vasculitic neuropathies with the antibodies used, except in MMP-9 immunostaining, which was found to be enhanced in NSVN group. Polymerase chain reaction analysis revealed elevated mRNA levels of MMP-9 and MMP-2 compared with controls, but this did not reach statistical significance. Our results imply a pathogenic role for MMP-9 secreted from CD8+ cells in vasculitic neuropathy.

Changes in water content, collagen degradation, collagen content, and concentration in repeated biopsies of the cervix of pregnant cows

The objective of the present study was to assess if cervical ripeness could be quantified by measuring the percentage of denaturation of the collagen network of the stromal layer. Biopsy specimens from the caudal part of the cervix were obtained from nine pluriparous cows between Days 149 and 157 of gestation (second-trimester biopsy), at exactly Day 275 of gestation (term biopsy), and shortly after calving (calving biopsy). The samples were divided into a superficial stromal part and a deep stromal part. The water content was derived from the weight of the samples before and after lyophilization. A colorimetric assay was used to assess the percentage of collagen denaturation by determining the extinction at 570 nm of hydroxyproline released from alpha-chymotrypsine-treated samples. By incorporating a hydroxyproline standard series in the measurements, the insoluble collagen content (mug/mg dry wt) as well as the insoluble collagen concentration (mug/mg wet wt) could be derived. The water content of both layers of the cervix significantly increased between midpregnancy and parturition (P < 0.01). The insoluble collagen content and the insoluble collagen concentration were significantly increased at term (P < 0.01 and P < 0.05, respectively) but were significantly decreased at calving (P < 0.05 and P < 0.01, respectively). Both parameters showed no significant differences between the superficial and deep stromal layer, and they were significantly correlated with each other. A significant increase in the percentage denaturation of the deep stromal layer occurred between the second trimester and term pregnancy (P < 0.01), whereas at calving, the percentage denaturation had not significantly increased compared to term. The percentage of collagen denaturation of the superficial stromal layer did not significantly change with stage of gestation or at parturition. Our findings indicate that cervical ripening is a combination of increased collagen synthesis and increased percentage of collagen denaturation, whereas at calving, an increased digestion of the denatured collagen leads to increased collagen loss from the cervical connective tissue. The finding that cervical ripening mainly takes place in the deep stromal layer of the cervix emphasizes the importance of a detailed description of the tissue sampling sites for a proper interpretation of the results obtained from biochemical studies of the cervix.

Batimastat reduces Mycobacterium tuberculosis-induced apoptosis in macrophages

In this study, we report evidences that Mycobacterium tuberculosis (MTB)-induced apoptosis in macrophages is reduced by a broad-spectrum hydroxamic acid-based matrix metalloproteinase (MMP) inhibitor, Batimastat (BB-94). In particular, we show that BB-94 administration to MTB-infected macrophages inhibits apoptosis and the downmodulation of membrane CD14 expression. Moreover, the addition of broad spectrum matrix metalloproteinase inhibitor to cell culture, during MTB infection, decreases the release of soluble TNF-alpha and leads to a simultaneous increase of membrane TNF-alpha. These results show that MTB-induced apoptosis in macrophages is reduced by a MMP inhibitor and most probably is related to TNF-alpha release. This identifies BB-94 as a simultaneous anti-apoptotic and anti-inflammatory molecule during MTB infection.

Adhesion molecules and matrix metalloproteinases in Multiple Sclerosis: effects induced by Interferon-beta

In Multiple Sclerosis (MS) pathology, early inflammation involves leukocyte migration across the blood-brain barrier (BBB) within the central nervous system. In this process, adhesion molecules (AMs), both membrane-bound and soluble-circulating forms, and matrix metalloproteinases (MMPs) certainly play a regulatory role. In MS, recombinant Interferon-beta (rIFNbeta) is effective in reducing gadolinium contrast-enhancing lesions on magnetic resonance imaging and this suggests that it may reduce BBB damage or even restore its integrity by different mechanisms that include interference with both AM and MMP pathways. This review will highlight the effects induced by rIFNbeta, both in vitro and in vivo, on cell-bound and soluble forms of AMs and on MMPs.

Inhibition of matrix metalloproteinases ameliorates blood-brain barrier disruption and neuropathological lesions caused by avirulent Semliki Forest virus infection

Semliki Forest virus (SFV) infection of mice is a useful model of viral neuropathogenesis in animals and avirulent strains such as SFV-A7 induce immune-mediated demyelination and death of neurones by necrosis and apoptosis. Matrix metalloproteinases (MMPs) have been implicated in various diseases including arthritis and cancer in many species. In this report, we show that MMP-2 and MMP-9 expression is induced in the brains of mice infected i.n. with SFV-A7. Treatment of mice with the pan MMP inhibitor GM6001 ameliorated the development of SFV-induced neuropathological lesions via an effect on the integrity of the blood-brain barrier. Low levels of neuronal necrosis and demyelination in GM6001-treated mice correlated with localisation of fibrinogen staining to thin-walled blood vessels and less intense staining of the perivascular neuropil.

Pathogenic A beta induces the expression and activation of matrix metalloproteinase-2 in human cerebrovascular smooth muscle cells

Cerebral amyloid angiopathy (CAA) is a major pathological feature of Alzheimer's disease and related disorders. Human cerebrovascular smooth muscle (HCSM) cells, which are intimately associated with CAA, have been used as an in vitro model system to investigate pathologic interactions with amyloid beta protein (A beta). Previously we have shown that pathogenic forms of A beta induce several pathologic responses in HCSM cells including fibril assembly at the cell surface, increase in the levels of A beta precursor, and apoptotic cell death. Here we show that pathogenic A beta stimulates the expression and activation of matrix metalloproteinase-2 (MMP-2). Furthermore, we demonstrate that the increase in MMP-2 activation is largely caused by increased expression of membrane type-1 (MT1)-MMP expression, the primary MMP-2 activator. Finally, treatment with MMP-2 inhibitors resulted in increased HCSM cell viability in the presence of pathogenic A beta. Our findings suggest that increased expression and activation of MMP-2 may contribute to HCSM cell death in response to pathogenic A beta. In addition, these activities may also contribute to loss of vessel wall integrity in CAA resulting in hemorrhagic stroke. Therefore, further understanding into the role of MMPs in HCSM cell degeneration may facilitate designing therapeutic strategies to treat CAA found in AD and related disorders.

TIMPs and MMPs expression in CSF from patients with TSP/HAM

The tropical spastic paraparesis or human T-cell lymphotropic virus associated myelopathy (TSP/HAM), has been related with an overexpression of matrix metalloproteinases (MMPs), especially MMP-9. Initial studies of reverse zymography with cerebrospinal fluid (CSF) from TSP/HAM patients, and controls showed the presence of TIMPs, endogenous MMP inhibitors. We determined in CSF the levels of TIMPs by immunoanalysis in 25 patients with TSP/HAM, and compared with two groups: controls and patients with acute and subacute inflammatory neurological diseases. We found that TIMP-2, TIMP-3 and TIMP-4 levels were significantly higher than in controls in both TSP/HAM and inflammatory patients, while TIMP-1 was increased only in the inflammatory group. Levels of MMP-3 and MMP-9 from the two groups of patients showed a significant upregulation in CSF. In the CSF of around the 70% of TSP-HAM and inflammatory patients the presence MMP-9 was detected by zymography, but not in controls. MMP-2 was only overexpressed in the acute inflammatory group. The active form of MMP-2 was observed in both groups of patients with a similar high frequency (60%). MMPs overexpressions are independent of the evolution time of the disease in TSP/HAM. The chronic overexpression of these extracelullar matrix proteins detected in CSF of TSP/HAM should be indirectly produced by secreted viral proteins being responsible for the progression of this disease, accounting for the observed differences with acute inflammatory patients. Our results support the existence of an imbalance between MMPs and their endogenous tissue inhibitors, which could be a pathogenic factor in the chronicity of TSP/HAM.

Matrix metalloproteinase-12 is expressed in phagocytotic macrophages in active multiple sclerosis lesions

Matrix metalloproteinases (MMPs) are proteases involved in extracellular matrix (ECM) remodeling, leukocyte infiltration into lesions and myelin degradation in the central nervous system (CNS) disease multiple sclerosis (MS). We have investigated whether MMP-12 (macrophage metalloelastase) is expressed in MS lesions at various stages. In control patient tissue and (p)reactive MS lesions, only occasional microglial and astrocyte staining was detected. In contrast, in active demyelinating lesions, phagocytic macrophages were MMP-12 positive. A lower proportion of phagocytes was positive for MMP-12 in chronic active demyelinating lesions and inactive lesions. This suggests a role for MMP-12 during demyelination in MS.

Serum MMP-2 and MMP-9 are elevated in different multiple sclerosis subtypes

In multiple sclerosis (MS), matrix metalloproteinase (MMP) activity in tissues is the result of a balance between MMPs and their tissue inhibitors (TIMPs). MMP-9 predominates in acute MS lesions and is inhibited by TIMP-1, while MMP-2 may participate in the remodeling of the extracellular matrix (ECM) such as in chronic disease and is inhibited by TIMP-2. These differences may be reflected in serum and cerebrospinal fluid (CSF). We have tried to characterize MMP-2 and MMP-9 activities, in relation to their respective TIMPs, 2 and 1, as a factor of different types of the disease, as this information was not previously clearly stated. We found the MMP-2/TIMP-2 ratio in serum to show higher values in secondary progressive (SP, p=0.02) and primary progressive (PP, p=0.01) MS than short disease duration (SDD) relapsing-remitting (RR) MS, but not different from the healthy control (HC) group. Whereas the MMP-9/TIMP-1 ratio in serum showed higher (p=0.04) values in SDD RR MS than PP but also in active patients, evaluated either clinically (p=0.006) or from the magnetic resonance imaging (MRI, p<0.05), compared to inactive disease. CSF MMP to TIMP ratios did not differ between MS subtypes, suggesting systemic rather CNS-restricted changes. These results show that an increase in MMP-2/TIMP-2 ratio marks chronic progression in MS, but it is as high as in HC, and also confirm that high MMP-9 activity characterizes short duration relapsing and active forms of the disease.

NFkappaB and AP-1 DNA binding activity in patients with multiple sclerosis

Current evidence suggests that multiple sclerosis (MS) results from an autoimmune response mediated by T lymphocytes, which would be activated in the peripheral blood and migrate into the central nervous system. NFkappaB and AP-1 are two main transcription factors involved in T-cell activation. To investigate possible alterations in the activity of these factors in MS individuals, we have assayed NFkappaB and AP-1 DNA binding activity in peripheral blood mononuclear cells (PBMC). Binding activity was analyzed by gel mobility shift assay in MS patients compared with controls. No significant differences were found between the two groups, indicating no evidence of abnormalities associated with MS in NFkappaB or AP-1 binding activities in PBMC, both basally and after PMA+anti-CD3 antibody induction.

Effects of peroxisome proliferator-activated receptor-gamma agonists on central nervous system inflammation

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) plays a critical role in glucose and lipid metabolism. More recently, PPAR-gamma ligands have been reported to inhibit the expression of proinflammatory molecules by monocytes/macrophages. Of relevance to CNS disease is that PPAR-gamma agonists have been demonstrated to have similar effects on microglia. PPAR-gamma agonists also ameliorate experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. This Mini-Review summarizes the effects of PPAR-gamma agonists in mediating immune responses and the potential of these agonists in the treatment of inflammatory disorders of the CNS.

A comparison of the mechanisms of action of interferon beta and glatiramer acetate in the treatment of multiple sclerosis

BACKGROUND

The development of immunomodulatory agents has represented a major advance in the treatment of multiple sclerosis (MS). To date, immunomodulatory agents approved for the treatment of relapsing MS in the United States include 3 forms of recombinant interferon (IFN) beta (2 formulations of IFN beta-1a and 1 of IFN beta-1b) and synthetic glatiramer acetate (GA). Recognition of how these agents work to regulate the immune system may lead to a better understanding of disease mechanisms, as well as to development of more effective therapies or combinations of therapy.

OBJECTIVE

This article reviews the potential mechanisms of action of IFN beta products and GA in the context of their regulatory effects on autoimmune components that may be of importance in MS.

METHODS

MEDLINE and Current Contents/Clinical Medicine were searched for articles published in English from 1993 to the present using the search terms interferon beta, glatiramer acetate, and multiple sclerosis.

RESULTS

IFN beta products affect the disease process in MS through multiple potential mechanisms of action, including antiviral, antiproliferative, and anti-inflammatory effects. The mechanisms of action of GA are less clear, but may involve immune regulation induced by a gradual shift of T-cell phenotype from proinflammatory (type 1 T-helper cells) to anti-inflammatory (type 2 T-helper cells) and interference with antigen presentation.

CONCLUSION

Understanding the mechanisms of action of IFN beta products and GA provides important insights into the disease processes involved in MS.

P0 and myelin basic protein-like immunoreactivities following ligation of the sciatic nerve in the rat

In this work we analyzed variations in the expression of MBPs and P0 in ligated sciatic nerves of young and adult rats at 3, 7, and 14 days postligation (PL), by immunohistochemistry and SDS-PAGE of isolated myelin. A protein redistribution was seen in the distal stump of ligated nerves with the appearance of immunoreactive clusters. Using the KS400 image analyzer, immunostained area values were obtained from the different nerves dissected. In adult rats, there was an increase of the immunostained area for MBP from 3 to 7 days PL, coincident with a reorganization of the marker in clusters, followed by a marked decrease at 14 days. P0 immunolabeling gave similar results without, however, a decrease of the immunostained area at the longer survival time tested. Young animals showed an acceleration in the process of protein redistribution and digestion within ligated nerves, which followed a similar pattern as that of adult animals. Analysis by electrophoresis showed a marked decrease in P0 and MBP at 7 days PL in young rats and 14 days PL in adult rats. The functional significance of protein clustering within myelin in injured nerves deserves further analysis.

Penta-O-galloyl-beta-D-glucose inhibits the invasion of mouse melanoma by suppressing metalloproteinase-9 through down-regulation of activator protein-1

Penta-O-galloyl-beta-D-glucose (5GG) inhibited the invasion of highly metastatic mouse melanoma B16F10 cells in vitro, as demonstrated by transwell assay. Its ability to diminish the activity of matrix metalloproteinase (MMP) was demonstrated by zymographic assay. Our data showed 5GG could diminish the activity of MMP-9 more than that of MMP-2. The effect on MMP-9 was elicited in a dose- and time-dependent manner, with IC50 of 15 microM. Next, we analyzed the amounts of MMP-9 and MMP-2 protein in conditioned media and in the cells. The data indicated MMP-9 proteins were also suppressed by 5GG in the same manner. In accordance with these data above, the results of reverse transcriptase polymerase chain reaction (RT-PCR) and Northern blot analysis showed a reduced level of MMP-9 mRNA. Furthermore, we studied transcription factor binding to MMP-2 and MMP-9 promoter regions by electrophoretic mobility shift assay (EMSA) in the nucleus. The results suggested that the transcription factor binding activities of Activator protein-1 (AP-1) and Sp-1 sites was mainly down-regulated by 5GG in the concentration range of 5-15 microM, but not that of nuclear factor kappaB (NF-kappaB), polioma enhancer activator 3 (PEA-3), and Activator protein-2 (AP-2) sites. The Western blot analysis of AP-1 nuclear protein showed a reduced level of c-Jun but not of c-Fos. In addition, the expression of Sp-1 and c-Jun protein was also suppressed. To elucidate whether the transcriptional activity of AP-1 or Sp-1 sites is more important, we transfected MMP-9/luciferase reporter vector, under MMP-9 promoter control, into the cells. We found that a decreased transcriptional activity of AP-1 sites is sufficient to reduce MMP-9 promoter activity. These results lead us to conclude that 5GG restricts the invasive ability of B16F10 mouse melanoma cells by reducing MMP-9 activity, by suppressing the transcriptional activity of AP-1 sites and the expression of c-Jun protein. The result may provide a potential mechanism for 5GG in cancer chemopreventive action.

Cytokines in multiple sclerosis: methodological aspects and pathogenic implications

Multiple sclerosis (MS) is one of the leading causes of disability among young adults of Caucasian origin. One hundred and fifty years after the first description of the disease, the cause of MS remains unknown. Ironically, the few hypotheses concerning MS pathogenesis that are valid today were first proposed over a hundred years ago. However, equipped with the advanced technology of molecular biology and imaging systems, we are at present progressively uncovering dues to understanding the pathogenesis of the disease. It is dearly evident that aberrant immune responses occur in MS, and it is likely that the spectrum of cytokines produced decisively influences disease outcome. The detrimental consequences of IFN-gamma and the beneficial effects of IFN-beta treatment in MS support this hypothesis. However, there are still major gaps in our knowledge of the involvement of cytokines in MS. Numerous studies have addressed the question of cytokine levels in MS, often with conflicting results; elevated, normal and decreased levels of almost all cytokines have been reported. This scenario most probably reflects methodological dilemmas as well as the complex biology of cytokines. Here we focus on possible reasons for the discrepancies of results reported on cytokines in MS and summarize findings obtained in particular by the application of enzyme-linked immunospot (ELISPOT) assays to cytokine studies in MS.