Impact of metabolic disorders on the structural, functional, and immunological integrity of the blood-brain barrier: Therapeutic avenues.

Mounting evidence has linked the metabolic disease to neurovascular disorders and cognitive decline. Using a murine model of a high-fat high-sugar diet mimicking obesity-induced type 2 diabetes mellitus (T2DM) in humans, we show that pro-inflammatory mediators and altered immune responses damage the blood-brain barrier (BBB) structure, triggering a proinflammatory metabolic phenotype. We find that disruption to tight junctions and basal lamina due to loss of control in the production of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) causes BBB impairment. Together the disruption to the structural and functional integrity of the BBB results in enhanced transmigration of leukocytes across the BBB that could contribute to an initiation of a neuroinflammatory response through activation of microglia. Using a humanized in vitro model of the BBB and T2DM patient post-mortem brains, we show the translatable applicability of our results. We find a leaky BBB phenotype in T2DM patients can be attributed to a loss of junctional proteins through changes in inflammatory mediators and MMP/TIMP levels, resulting in increased leukocyte extravasation into the brain parenchyma. We further investigated therapeutic avenues to reduce and restore the BBB damage caused by HFHS-feeding. Pharmacological treatment with recombinant annexin A1 (hrANXA1) or reversion from a high-fat high-sugar diet to a control chow diet (dietary intervention), attenuated T2DM development, reduced inflammation, and restored BBB integrity in the animals. Given the rising incidence of diabetes worldwide, understanding metabolic-disease-associated brain microvessel damage is vital and the proposed therapeutic avenues could help alleviate the burden of these diseases.

Matrix Metalloproteinases and Tissue Inhibitor of Metalloproteinases in Inflammation and Fibrosis of Skeletal Muscles.

In skeletal muscles, levels and activity of Matrix MetalloProteinases (MMPs) and Tissue Inhibitors of MetalloProteinases (TIMPs) have been involved in myoblast migration, fusion and various physiological and pathological remodeling situations including neuromuscular diseases. This has opened perspectives for the use of MMPs' overexpression to improve the efficiency of cell therapy in muscular dystrophies and resolve fibrosis. Alternatively, inhibition of individual MMPs in animal models of muscular dystrophies has provided evidence of beneficial, dual or adverse effects on muscle morphology or function. We review here the role played by MMPs/TIMPs in skeletal muscle inflammation and fibrosis, two major hurdles that limit the success of cell and gene therapy. We report and analyze the consequences of genetic or pharmacological modulation of MMP levels on the inflammation of skeletal muscles and their repair in light of experimental findings. We further discuss how the interplay between MMPs/TIMPs levels, cytokines/chemokines, growth factors and permanent low-grade inflammation favor cellular and molecular modifications resulting in fibrosis.

The molecular biology of matrix metalloproteinases and tissue inhibitors of metalloproteinases in inflammatory bowel diseases.

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are thought to be predominant proteases and protease inhibitors involved in the pathogenesis of inflammatory bowel diseases (IBD) through their ability to remodel the extracellular matrix (ECM) in response to inflammatory stimuli and by their immunomodulating effects. An imbalance between MMPs and TIMPs has been linked with acute and chronic inflammation and aberrant tissue remodeling, as seen in IBD. Moreover, recurrent phases of tissue destruction and subsequent tissue repair can cause serious complications in IBD patients such as fistulas and fibrosis. The aims of this review are (i) to summarize current literature on genetic association, mRNA, and protein expression studies with regard to MMPs and TIMPs in IBD patients and various animal models, including those with transgenic and knockout mice; (ii) to compare biochemical and molecular biological data in humans with those obtained in animal model studies and (iii) to critically evaluate and translate how this knowledge may be used in practical terms to understand better the pathophysiology and mechanisms operating in IBD and to apply this for improvement of clinical outcomes at diagnostic, prognostic and therapeutic levels.

Cytokine Expression Pattern in Bone Marrow Microenvironment after Allogeneic Stem Cell Transplantation in Primary Myelofibrosis.

The only curative therapy for primary myelofibrosis (PMF) is allogeneic stem cell transplantation (ASCT). However, although we know that patients can benefit from ASCT, we do not know the extent of the changes of the expression profile of cytokines and matrix modulation factors. In this first systematic analysis, we evaluated the expression profile of 103 factors before and after transplantation to identify potential biomarkers. The expression of fibrosis-, inflammation-, and angiogenesis-associated genes was analyzed in a total of 52 bone marrow biopsies: PMF patients (n = 14) before and after ASCT and, for control purposes, post-ASCT multiple myeloma patients (n = 14) and non-neoplastic hematopoiesis (n = 10). In post-ASCT PMF cases, decreased expression of tissue inhibitor of metalloproteinases (TIMP) and platelet-derived growth factor alpha (PDGFA) correlated with bone marrow remodeling and hematological remission. Expression of several other matrix factors remained at high levels and may contribute to post-ASCT remodeling. This is the first systematic analysis of cytokine expression in post-ASCT PMF bone marrow that shows that normalization of bone marrow microenvironment is paralleled by decreased expression of TIMP and PDGFA.

Economic evaluation in the context of rare diseases: is it possible? / Evaluación económica en el contexto de enfermedades raras: ¿es posible? / Avaliação econômica no âmbito das doenças raras: isto é possível?

This study analyzes the available evidence on the adequacy of economic evaluation for decision-making on the incorporation or exclusion of technologies for rare diseases. The authors conducted a structured literature review in MEDLINE via PubMed, CRD, LILACS, SciELO, and Google Scholar (gray literature). Economic evaluation studies had their origins in Welfare Economics, in which individuals maximize their utilities based on allocative efficiency. There is no widely accepted criterion in the literature to weigh the expected utilities, in the sense of assigning more weight to individuals with greater health needs. Thus, economic evaluation studies do not usually weigh utilities asymmetrically (that is, everyone is treated equally, which in Brazil is also a Constitutional principle). Healthcare systems have ratified the use of economic evaluation as the main tool to assist decision-making. However, this approach does not rule out the use of other methodologies to complement cost-effectiveness studies, such as Person Trade-Off and Rule of Rescue.

El objetivo fue sistematizar las evidencias disponibles sobre la pertinencia de utilizar la evaluación económica para la incorporación/exclusión de tecnología en enfermedades raras. Se realizó una revisión sistemática de la literatura en MEDLINE vía PubMed, CRD, LILACS, SciELO y Google Académico (literatura gris). Los estudios de evaluación económica se originan de la Economía del Bienestar, en la que los individuos maximizan sus utilidades, basándose en la eficiencia de asignación. No existe un criterio ampliamente aceptado para examinar las utilidades, a fin de dar más peso a los individuos con mayores necesidades. Generalmente, los estudios no equilibran asimétricamente las utilidades, todas son consideradas iguales, lo que en Brasil es también un principio constitucional. Los sistemas de salud han ratificado el uso de la evaluación económica como la principal herramienta para ayudar en la toma de decisiones. Sin embargo, este abordaje no excluye el uso de otras metodologías complementarias a los estudios de coste-efectividad, como la técnica de compensación personal o la regla del rescate.

O objetivo deste estudo foi analisar as evidências disponíveis sobre a adequação do uso de avaliação econômica sobre incorporação/exclusão de tecnologias para doenças raras. Foi realizada uma revisão estruturada da literatura, nas bases MEDLINE, via PubMed, CRD, LILACS, SciELO e Google Acadêmico (literatura cinzenta). Os estudos de avaliação econômica têm origem na Economia do Bem-Estar, na qual os indivíduos maximizam suas utilidades, fundamentando-se na eficiência alocativa. Não há um critério amplamente aceito para ponderar as utilidades esperadas, no sentido de dar mais peso aos indivíduos com maiores necessidades em saúde. Geralmente não se ponderam assimetricamente as utilidades; todas são tratadas de forma igualitária, que, no caso brasileiro, também é um princípio constitucional. Os sistemas de saúde têm ratificado o uso de avaliação econômica como principal instrumento para auxiliar na tomada de decisão. No entanto, essa postura não exclui o uso de outras metodologias complementares aos estudos de custo-efetividade, como Person Trade-Off e regra de resgate.

Metalloproteinases and their natural inhibitors in inflammation and immunity.

Over the past 50 years, steady growth in the field of metalloproteinase biology has shown that the degradation of extracellular matrix components represents only a fraction of the functions performed by these enzymes and has highlighted their fundamental roles in immunity. Metalloproteinases regulate aspects of immune cell development, effector function, migration and ligand-receptor interactions. They carry out ectodomain shedding of cytokines and their cognate receptors. Together with their endogenous inhibitors TIMPs (tissue inhibitor of metalloproteinases), these enzymes regulate signalling downstream of the tumour necrosis factor receptor and the interleukin-6 receptor, as well as that downstream of the epidermal growth factor receptor and Notch, which are all pertinent for inflammatory responses. This Review discusses the metalloproteinase family as a crucial component in immune cell development and function.

A novel tissue inhibitor of metalloproteinase in blood clam Tegillarca granosa: molecular cloning, tissue distribution and expression analysis.

Tissue inhibitor of metalloproteinases (TIMPs) were originally characterized as inhibitors of matrix metalloproteinases (MMPs), but their range of activities has been found to be broader as it includes the inhibition of several of the MMPs, etc. The cDNA encoding TIMP-4-like gene from blood clam Tegillarca granosa (designated as Tg-TIMP-4-like) which is the first tissue inhibitor of metalloproteinase identified in blood clams, was cloned and characterized. It was of 1164 bp, and an open reading frame (ORF) of 666 bp encoding a putative protein of 222 amino acids. The predicted amino acid sequence comprised all recognized functional domains found in other TIMP homologues and showed the highest (30.56%) identity to the TIMP-1.3 from Crassostrea gigas. Several highly conserved motifs including several TIMP signatures, amino acid residue Cys³° responsible for coordinating the metal ions, the Cys-X-Cys motif and the putative NTR (netrin) domain were almost completely conserved in the deduced amino acid of Tg-TIMP-4 like, which indicated that Tg-TIMP-4-like should be a member of the TIMP family. The mRNA expression of Tg-TIMP-4-like in the tissues of mantle, adductor muscle, foot, gill, hemocyte and hepatopancreas was examined by quantitative real-time PCR (qT-PCR) and mRNA transcripts of Tg-TIMP-4-like were mainly detected in hemocyte, and weakly detected in the other tissues. We also observed that Tg-TIMP-4 like mRNA accumulated significantly during Vibrio parahaemolyticus, Peptidogylcan (PGN) and Lipopolysaccharide (LPS) challenge, whereas the timing and quantitative differences of mRNA expression against different challenge indicated that Tg-TIMP-4-like may play a pivotal role in mollusc defense mechanisms.

Serum levels of metalloproteinases and their inhibitors during infection with pathogens having integrin receptor-mediated cellular entry.

BACKGROUND: Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes with numerous roles in the normal immune response to infection. However, excess MMP activity following infection may lead to immunopathological processes that cause tissue damage. Their activity in normal tissues is subject to tight control, which is regulated by its specific endogenous tissue inhibitors (TIMPs). It is known that MMPs bind to cell surface proteins (e.g. integrins) and that such interactions can have modulatory effects on MMP functionality. The objective of this study was to determine whether there are differences in MMP and TIMP production during the acute phase of infection with different pathogens that use ß-integrins as their receptors for cell entry. METHODS: We measured the total amounts of soluble MMP-2, MMP-9, TIMP-1, and TIMP-2 in the sera from patients infected with Dobrava virus (DOBV), Coxiella burnetii, or uropathogenic Escherichia coli. Statistical analyses were used to correlate MMP/TIMP serum levels with different clinical laboratory parameters. RESULTS: The results showed that both of the bacterial infections generally manifested the stronger effect on MMP production, while in contrast, viral infection introduced stronger changes to metalloproteinase inhibitors. MMPs and TIMPs were significantly correlated with some of the clinical laboratory parameters in both bacterial infections, but no correlations were found for DOBV infection. CONCLUSIONS: These findings suggest diverse mechanisms by which MMP activity could be implicated in the pathology of these 2 bacterial infections versus the viral DOBV infection, despite the type of their cellular entry receptors.

Strain-dependent production of interleukin-17/interferon-γ and matrix remodeling-associated genes in experimental Candida albicans keratitis.

PURPOSE: The aim of this study was to investigate the role of genetic background in determining the development or prognosis of experimental fungal keratitis by comparing the disease courses and related molecules of experimental Candida albicans in two common mouse strains. METHODS: After intrastromal inoculation of 1 × 10(5)C. albicans blastospores into corneas of Balb/c and C57BL/6 mice, all mice developed typical keratitis. The disease was monitored using a slit lamp microscope and scored for comparison of symptoms. At desired time points, blood was collected and corneal homogenates were prepared for enzyme-linked immunosorbent assay measurement of interferon (IFN)γ or interleukin (IL)17. Other corneas were processed for histological evaluation, pathogen load measurement, or total RNA extraction, the last of which was subjected to reverse transcription in conjunction with real-time PCR to measure genes of interest in terms of collagens, matrix metalloproteinases (MMPs), and the tissue inhibitors of MMPs (TIMPs). RESULTS: The infected corneas from the two strains presented different manifestations. Corneal transparency was less affected in Balb/c mice than in C57BL/6 mice, and Balb/c corneas contained fewer pathogens than C57BL/6 corneas during the measured period (10 days). In both strains, keratitis started to resolve around days 7-10, but C57BL/6 mice healed slower than Balb/c mice as indicated by disease presentation, histology, and pathogen burden assay. By day 7 post infection, pseudohyphae were rare but cellular infiltration remained intensive in both strains. The surface of the Balb/c corneas remained relatively intact and smooth, and C57BL/6 corneal lesions produced open erosion areas. Perforation was never seen in the current study setting. In both sera and corneas, IL17 expression increased earlier than IFNγ, and C57BL/6 mice produced higher IL17 levels and lower IFNγ levels than Balb/c mice. Compared with C57BL/6 mice, Balb/c corneas produced more MMP-2, Col3a1, and Col4a1, and less or equivalent TIMP-2 at all detected time points. They also produced more MMP-13, less MMP-8, MMP-9, and TIMP-1 at day 3 post infection, but less MMP-13, basically equivalent MMP-8, and more MMP-9 at later time points. CONCLUSIONS: The disease course of experimental C. albicans keratitis depends on the genetic background of the host animals. The balance between IL17 and IFNγ, as well as among the common injury- and wound healing-related proteins, may contribute to the pathogenesis of C. albicans keratitis. This study suggests that great variance of disease presentation should be expected for human subjects with Candida keratitis.

[Immune mechanisms in pathogenesis of chronic heart failure].

In the review the new information about a participation of immune mechanisms in a pathogenesis of a chronic heart failure (CHF) is presented. Significance of a bacterial endotoxin, as inductor of activation of immune system at CHF, and factors of a system inflammation in a pathogenesis of the disease, breaking balance of matrix metalloproteinases and tissue inhibitors of metalloproteinases system, leading to change of structure of an extracellular matrix of a myocardium, are discussed.

Mecanismos celulares e moleculares envolvidos na reabsorção radicular fisiológica de dentes decíduos / Cellular and molecular mechanisms involved in the physiological root resorption of primary teeth

Introdução: A reabsorção fisiológica dos dentes decíduos constitui um fenômeno fisiológico complexo não completamente conhecido; assunto de grande interesse clínico. Os mecanismos celulares e moleculares envolvidos no fenômeno de reabsorção radicular fisiológica parecem ser similares aos mecanismos envolvidos na reabsorção óssea, mediada por osteoclastos. As principais células responsáveis pela reabsorção ativa dos tecidos dentais são os odontoclastos, também denominados de clastos ou osteoclastos; células gigantes multinucleadas originadas de precursores hematopoiéticos de monócitos ou macrófagos. Avanços recentes na literatura específica têm mostrado que a diferenciação e atividade dos osteoclastos, fenômeno também conhecido como osteoclastogênese, são iniciadas e reguladas por diferentes estímulos e sinalizadores moleculares como as citocinas, quimiocinas, produtos de degradação liberados pela superfície radicular afetada, moléculas de adesão, metaloproteinases e pelo sistema RANK/RANKL/OPG. Ainda, o contato físico entre os precursores de osteoclastos e osteoblastos ou células estromais também parece ser necessário para a ativação da osteoclastogênese. Entretanto, o papel específico dos fatores envolvidos no início e modulação da reabsorção radicular dos dentes decíduos permanece desconhecido. Objetivo: Realizar uma revisão de literatura sobre os mecanismos celulares e moleculares envolvidos no processo de reabsorção fisiológica dos dentes decíduos, enfatizando suas implicações clínicas.

Conclusão: Uma complexa interação entre osteclastos, osteoblastos, macrófagos, citocinas, quimiocinas, metaloproteinases, moléculas de adesão e o sistema RANK/RANKL/OPG parecem contribuir para a reabsorção dentária fisiológica. O conhecimento dos mecanismos celulares e moleculares envolvidos no processo de reabsorção fisiológica dos dentes decíduos pode contribuir para o estudo da imunopatogenia das reabsorções dentárias e futuramente resultar na aplicação clínica de mediadores moleculares para atrasar ou mesmo inibir esse processo

Introduction: The physiological resorption of primary teeth is a complex physiological phenomenon that is not completely known and is a subject of great interest. The cellular and molecular mechanisms involved in the phenomenon of physiological root resorption seem to be similar to those involved in bone resorption mediated by osteoclasts. The main cells responsible for the active resorption of the dental tissues are the odontoclasts, which are also known as clasts or osteoclasts; multi nucleated giant cells originated from hematopoietic precursors of monocytes or macrophages. Recent advances published in the literature have shown that the differentiation and activity of osteoclasts, a phenomenon that is also known as osteoclastgenesis, are initiated and regulated by different stimuli and molecular signalizing agents such as cytokines, chemokines, products of degradation released by the affected root surface, adhesion molecules, metalloproteinases, and the RANK/RANKL/OPG system. Moreover, the physical contact between the osteoclasts and osteoblast precursors or stromal cells also seems to be necessary for the activation of osteoclastgenesis. However, the specific role of the factors involved in the initiation and modulation of root resorption of the primary teeth remains unknown. Objective: To perform a review of the literature about the cellular and molecular mechanisms involved in the process of physiological resorption of the primary teeth, emphasizing their clinical implications.

Conclusion: A complex integration among osteoclasts, osteoblasts, macrophages, cytokines, chemokines, metalloproteinases, adhesion molecules and the RANK/RANKL/OPG system seems to contribute to the physiological resorption of teeth. Knowing the cellular and molecular mechanisms involved in the process of physiological root resorption of primary teeth may contribute to the investigation of the immunepathogenesis of dental resorptions, and allow for the clinical application of molecular mediators to delay or even inhibit this process

Development of a monoclonal antibody that specifically detects tissue inhibitor of metalloproteinase-4 (TIMP-4) in formalin-fixed, paraffin-embedded human tissues.

Overexpression of the extracellular metalloproteinase inhibitor TIMP-4 in estrogen receptor-negative breast cancers was found recently to be associated with a poor prognosis for survival. To pursue exploration of the theranostic applications of TIMP-4, specific antibodies with favorable properties for immunohistochemical use and other clinical assays are needed. Here we report the characterization of a monoclonal antibody (clone 9:4-7) specific for full-length human TIMP-4 with suitable qualities. The antibody was determined to be an IgG(2b) immunoglobulin. In enzyme-linked immunosorbent assay (ELISA) and immunoblotting assays, it did not exhibit any detectable crossreactivity with recombinant forms of the other human TIMPs 1, 2, and 3. In contrast, the antibody displayed high specificity and sensitivity for TIMP-4 including in formalin-fixed and paraffin-embedded specimens of human breast specimens. An analysis of tissue microarrays of human cancer and corresponding normal tissues revealed specific staining patterns with excellent signal-to-noise ratios. This study documents TIMP-4 monoclonal antibody clone 9:4-7 as an effective tool for preclinical and clinical investigations.

Vulnerable atherosclerotic plaque metalloproteinases and foam cell phenotypes.

Plaque rupture underlies most myocardial infarctions. Plaques vulnerable to rupture have thin fibrous caps, an excess of macrophages over vascular smooth muscle cells, large lipid cores, and depletion of collagen and other matrix proteins form the cap and lipid core. Production of matrix metalloproteinases from macrophages is prominent in human plaques, and studies in genetically modified mice imply a causative role for metalloproteinases in plaque vulnerability. Recent in-vitro studies on human monocyte-derived macrophages and on foam-cell macrophages generated in vivo suggest the existence of several macrophage phenotypes with distinct patterns of metalloproteinase expression. These phenotypes could play differing roles in cap, core and aneurysm formation.

Porphyromonas gingivalis decreases osteoblast proliferation through IL-6-RANKL/OPG and MMP-9/TIMPs pathways.

BACKGROUND: Porphyromonas gingivalis, an important periodontal pathogen, is closely associated with inflammatory alveolar bone resorption. This bacterium exerts its pathogenic effect indirectly through multiple virulence factors, such as lipopolysaccharides, fimbriae, and proteases. Another possible pathogenic path may be through a direct interaction with the host's soft and hard tissues (e.g., alveolar bone), which could lead to periodontitis. AIMS AND OBJECTIVES: The aim of the present study was to investigate the direct effect of live and heat-inactivated P gingivalis on bone resorption, using an in vitro osteoblast culture model. RESULTS: Optical microscopy and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide MTT assay revealed that live P gingivalis induced osteoblast detachment and reduced their proliferation. This effect was specific to live bacteria and was dependent on their concentration. Live P gingivalis increased IL-6 mRNA expression and protein production and downregulated RANKL and OPG mRNA expression. The effect of live P gingivalis on bone resorption was strengthened by an increase in MMP-9 expression and its activity. This increase was accompanied by an increase in TIMP-1 and TIMP-2 mRNA expression and protein production by osteoblasts infected with live P gingivalis. CONCLUSION: Overall, the results suggest that direct contact of P gingivalis with osteoblasts induces bone resorption through an inflammatory pathway that involves IL-6, RANKL/OPG, and MMP-9/TIMPs.

The outer wall of small airways is a major site of remodeling in fatal asthma.

BACKGROUND: Structural and inflammatory changes in asthma involve both the large and small airways, with involvement of the distal lung being related to disease severity. We have previously shown that changes in the extracellular matrix (ECM) composition of the distal lung are associated with loss of alveolar attachments in patients with fatal asthma. However, major ECM elements, such as collagen I and fibronectin and their regulators, have not been addressed at the distal level. OBJECTIVE: We sought to evaluate ECM remodeling in the distal lungs of asthmatic patients. METHODS: Using immunohistochemistry and image analysis, we determined the content of collagen I and III, fibronectin, and matrix metalloproteinases (MMPs) 1, 2, and 9 and tissue inhibitors of metalloproteinase (TIMPs) 1 and 2 in the large and small airways and lung parenchyma of 24 patients with fatal asthma and compared the results with those of 11 nonasthmatic control subjects. Protein content was defined as the area of positive staining divided by basement membrane or septum length. RESULTS: We observed increased collagen I and decreased collagen III content in the small airways of asthmatic patients compared with that seen in control subjects. Greater fibronectin and MMP-1, MMP-2, and MMP-9 content was observed at the outer area of the small airways in asthmatic patients. MMP content was also increased in the peribronchiolar parenchyma in asthmatic patients. In contrast, TIMP expression was only increased in the large airways of asthmatic patients compared with that seen in control subjects. CONCLUSIONS: The outer area of the small airways is a major site of ECM remodeling in fatal asthma, potentially contributing to functional changes and the loss of airway-parenchyma interdependence observed in patients with fatal asthma.

Diverse roles of matrix metalloproteinases and tissue inhibitors of metalloproteinases in neuroinflammation and cerebral ischemia.

Regulation of the extracellular matrix by proteases and protease inhibitors is a fundamental biological process for normal growth, development and repair in the CNS. Matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs) are the major extracellular-degrading enzymes. Two other enzyme families, a disintegrin and metalloproteinase (ADAM), and the serine proteases, plasminogen/plasminogen activator (P/PA) system, are also involved in extracellular matrix degradation. Normally, the highly integrated action of these enzyme families remodels all of the components of the matrix and performs essential functions at the cell surface involved in signaling, cell survival, and cell death. During the inflammatory response induced in infection, autoimmune reactions and hypoxia/ischemia, abnormal expression and activation of these proteases lead to breakdown of the extracellular matrix, resulting in the opening of the blood-brain barrier (BBB), preventing normal cell signaling, and eventually leading to cell death. There are several key MMPs and ADAMs that have been implicated in neuroinflammation: gelatinases A and B (MMP-2 and -9), stromelysin-1 (MMP-3), membrane-type MMP (MT1-MMP or MMP-14), and tumor necrosis factor-alpha converting enzyme (TACE). In addition, TIMP-3, which is bound to the cell surface, promotes cell death and impedes angiogenesis. Inhibitors of metalloproteinases are available, but balancing the beneficial and detrimental effects of these agents remains a challenge.

Clipping, shedding and RIPping keep immunity on cue.

Exposure to infectious agents elicits defense mechanisms that necessitate a timely immune response. The immediate delivery of essential cues for immune activation is provided, in part, by proteolytic processing. A large repertoire of molecules orchestrates the activation, migration, and effector function of immune cells. The diversity of this repertoire matches well with the broad array of substrates that can be cleaved by proteinases, and many of these substrates are proving to be essential for proper immune-cell function. Here, we discuss how two specific classes of metal-dependent proteinases, the matrix metalloproteinases and the disintegrin metalloproteinases, have consequences well beyond classical cell-matrix and cell-cell interactions and motility, and we review their roles in immune-cell maturation, clonal expansion, and cytotoxic functions.

Matrix metalloproteinases and their inhibitors in the foreign body reaction on biomaterials.

Matrix metalloproteinases (MMPs) can degrade structural components within the extracellular matrix and at the cellular surface producing changes in cellular behavior (i.e., adhesion and migration) and subsequent pathological responses (i.e., the foreign body reaction and wound healing). We continue to study the foreign body reaction that occurs following biomaterial implantation by investigating secretory responses of biomaterial-adherent macrophages and foreign body giant cells (FBGCs) as directed by material surface chemistry and further this research by determining whether secreted MMPs play a role in macrophage adhesion and fusion. We have identified numerous MMPs and their tissue inhibitors (TIMPs) in in vitro cell-culture supernatants using antibody arrays and quantified select MMP/TIMPs with ELISAs. MMP-9 concentrations were significantly greater than both TIMP-1 and TIMP-2 on all materials. The ratios of MMP-9/TIMP-1 and MMP-9/TIMP-2 increased with time because of an increase in MMP-9 concentrations over time, while the TIMP concentrations remained constant. Total MMP-9 concentrations in the supernatants were comparable on all materials at each timepoint, while TIMP-1 and TIMP-2 concentrations tended to be greater on hydrophilic/anionic surfaces. Analysis of the MMP/TIMP quantities produced per cell revealed that the hydrophilic/neutral surfaces, which inhibited macrophage adhesion, activated the adherent macrophages/FBGCs to produce a greater quantity of MMP-9, TIMP-1, and TIMP-2 per cell. Pharmacological inhibition of MMP-1,-8,-13, and -18 reduced macrophage fusion without affecting adhesion, while inhibitors of MMP-2,-3,-9, and -12 did not affect adhesion or fusion. These findings demonstrate that material surface chemistry does modulate macrophage/FBGC-derived MMP/TIMP secretion and implicates MMP involvement in macrophage fusion.

First evidence of the activation of Cg-timp, an immune response component of Pacific oysters, through a damage-associated molecular pattern pathway.

In a previous work, we characterized a Crassostrea gigas cDNA (Cg-timp) encoding a protein which presents all the features of vertebrate tissue inhibitor of metalloproteinase (TIMP). The expression pattern of this gene led us to propose that Cg-timp is an important factor in oyster wound healing and defense mechanisms. Here we describe the analysis of Cg-timp expression in oysters challenged by live or dead bacteria as well as by bacterial secretory/excretory products and metalloproteinase. Surprisingly, bacterial secretory/excretory products activate Cg-timp gene expression whereas heat-inactivated ones do not. To address the question of the signal transduction pathway involved in Cg-timp gene activation, we isolated and sequenced Cg-timp promoter and upstream region. A 1-kb genomic DNA fragment flanking the 5'-end of the gene contains several regulatory elements and notably three NF-kappaB binding sites. The potential involvement of these motifs in Cg-timp gene regulation is discussed.

Angiogenic proteins are expressed by brain blood vessels in Alzheimer's disease.

Data are emerging to support the idea that mediators of angiogenesis are found in the Alzheimer's disease (AD) brain. The objective of this study is to compare the expression of the angiogenic mediators vascular endothelial growth factor (VEGF), angiopoietin, and matrix metalloproteinases (MMPs) in the microcirculation of AD patients and age-matched controls. Our results indicate that angiopoietin-2 and VEGF are expressed by AD- but not control-derived microvessels. AD-derived microvessels also release higher levels of MMP-2 and MMP-9 compared to controls. The data show that despite high levels of MMP-9, assessed by western blot, MMP-9 activity is not detectable in AD microvessels. In this regard we find high levels of the tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) in AD, but not control vessels. Furthermore, we explore the ability of thrombin, previously shown to be present in AD microvessels, to affect TIMP expression in cultured brain endothelial cells and find that thrombin causes up regulation of TIMP-1. These data show that angiogenic changes occur in the microcirculation of the AD brain and suggest that if these changes are contributory to disease pathogenesis, targeting the abnormal brain endothelial cell would provide a novel therapeutic approach for the treatment of this disease.