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Oxidative stress in the lumbar disc leads to the degeneration of nucleus pulposus (NP). However, the molecular mechanisms underlying this process remain unclear. In this study, we delineated a key calcium‐binding protein, S100A9, which was induced by oxidative stress and was highly expressed in the degenerative NP. Immunofluorescence staining and Western blotting revealed that S100A9 induced NP cell apoptosis in vitro by up‐regulating the expression of pro‐apoptotic markers, including cleaved caspase‐3, cytochrome c and Bax. Moreover, RT‐PCR analyses revealed that the expression of S100A9 caused NP matrix degradation by up‐regulating the expression of matrix degradation enzymes and increased the inflammatory response by up‐regulating cytokine expression. Therefore, S100A9 induced NP cell degeneration by exerting pro‐apoptotic, pro‐degradation and pro‐inflammatory effects. The detailed mechanism underlying S100A9‐induced NP degeneration was explored by administering SC75741, a specific NF‐κB inhibitor in vitro. We concluded that S100A9 induced NP cell apoptosis, caused matrix degradation and amplified the inflammatory response through the activation of the NF‐κB signalling pathway. Inhibition of these pro‐apoptotic, pro‐degradation and pro‐inflammatory effects induced by S100A9 in NP may be a favourable therapeutic strategy to slow lumbar disc degeneration.

ObjectiveThe aim of this study is to verify whether melatonin (Mel) could mitigate intervertebral disk degeneration (IVDD) in rats and to investigate the potential mechanism of it.MethodA rat acupuncture model of IVDD was established with intraperitoneal injection of Mel. The effect of Mel on IVDD was analyzed via radiologic and histological evaluations. The specific Mel receptors were investigated in both the nucleus pulposus (NP) and cartilaginous endplates (EPs). In vitro, EP cartilaginous cells (EPCs) were treated by different concentrations of Mel under lipopolysaccharide (LPS) and Luzindole conditions. In addition, LPS-induced inflammatory response and matrix degradation following nuclear factor kappa-B (NF-κB) pathway activation were investigated to confirm the potential mechanism of Mel on EPCs.ResultsThe percent disk height index (%DHI) and MRI signal decreased after initial puncture in the degeneration group compared with the control group, while Mel treatment protected disk height from decline and prevented the loss of water during the degeneration process. In the meantime, the histological staining of the Mel groups showed more integrity and well-ordered construction of the NP and EPs in both low and high concentration than that of the degeneration group. In addition, more deep-brown staining of type II collagen (Coll-II) was shown in the Mel groups compared with the degeneration group. Furthermore, in rat samples, immunohistochemical staining showed more positive cells of Mel receptors 1a and 1b in the EPs, instead of in the NP. Moreover, evident osteochondral lacuna formation was observed in rat EPs in the degeneration group; after Mel treatment, the osteochondral destruction alleviated accompanying fewer receptor activator for nuclear factor-κB ligand (RANKL) and tartrate-resistant acid phosphatase (TRAP)-stained positive cells expressed in the EPs. In vitro, Mel could promote the proliferation of EPCs, which protected EPCs from degeneration under LPS treatment. What is more, Mel downregulated the inflammatory response and matrix degradation of EPCs activated by NF-κB pathway through binding to its specific receptors.ConclusionThese results indicate that Mel protects the integrity of the EPs and attenuates IVDD by binding to the Mel receptors in the EPs. It may alleviate the inflammatory response and matrix degradation of EPCs activated by NF-κB pathway.

Cardiovascular diseases represent the leading cause of death in developed countries. Modern surgical methods show poor efficiency in the substitution of small-diameter arteries (

To identify the role of the Hippo signaling pathway in the extracellular matrix degradation of chondrocytes induced by fluoride exposure. Environmental response genes (ERGs) of bone injury induced by fluoride exposure were obtained from the Comparative Toxicogenomics Database, and annotated by STRING for KEGG pathway enrichment analysis. The CCK-8 kit was used to measure the proliferation of ATDC5 cells. The malondialdehyde (MDA), total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), and glutathione peroxidase (GSH-PX) levels in ATDC5 cells were measured using oxidative stress detection kit. Western blot analysis was used to measure the p-MST1/2, p-LATS1/2, and p-YAP/YAP1 expression levels in the Hippo pathway and the COL2A1, ACAN and MMP13 expression levels in the cartilage matrix. Localizations of YAP1 and COL2A1 proteins in chondrocytes were performed using cell immunofluorescence. Continuous data from the multiple groups were compared using one-way analysis of variance, and then the differences between groups were tested with Dunnett's t-test, with the test level α = 0.05. The 145 ERGs of bone injury induced by fluoride exposure were identified, and KEGG enrichment analysis revealed Hippo signaling pathways significantly related to bone injury. A CCK-8 assay revealed that the viability of the ATDC5 cells was significantly decreased with increased fluorine concentration. The MDA content in 20 mg/L sodium fluoride (NaF) exposure group was significantly higher than that in the control group, the T-SOD, T-AOC and GSH-PX activities in 15 and 20 mg/L NaF exposure groups were significantly lower than those in the control group (P

// Shijing Yue 1,* , Wei Mu 1,* , Ulrike Erb 1 and Margot Zoller 1 1 Department of Tumor Cell Biology, University Hospital of Surgery, Heidelberg, Germany * These authors contributed equally to this work Correspondence: Margot Zoller, email: // Keywords : Tetraspanins, exosomes, metastasis, matrix degradation, EMT Received : October 17, 2014 Accepted : December 09, 2014 Published : December 10, 2014 Abstract Tspan8 and CD151 are metastasis-promoting tetraspanins and a knockdown (kd) of Tspan8 or CD151 and most pronounced of both tetraspanins affects the metastatic potential of the rat pancreatic adenocarcinoma line ASML. Approaching to elaborate the underlying mechanism, we compared ASML wt , -CD151 kd and/or Tspan8 kd clones. We focused on tumor exosomes, as exosomes play a major role in tumor progression and tetraspanins are suggested to be engaged in exosome targeting. ASML-CD151/Tspan8 kd cells poorly metastasize, but regain metastatic capacity, when rats are pretreated with ASML wt , but not ASML-CD151 kd and/or -Tspan8 kd exosomes. Both exosomal CD151 and Tspan8 contribute to host matrix remodelling due to exosomal tetraspanin-integrin and tetraspanin-protease associations. ASML wt exosomes also support stroma cell activation with upregulation of cytokines, cytokine receptors and proteases and promote inflammatory cytokine expression in hematopoietic cells. Finally, CD151-/Tspan8-competent exosomes support EMT gene expression in poorly-metastatic ASML-CD151/Tspan8 kd cells. These effects are not seen or are weakened using ASML-CD151 kd or -Tspan8 kd exosomes, which is at least partly due to reduced binding/uptake of CD151- and/or Tspan8-deficient exosomes. Thus, CD151- and Tspan8-competent tumor exosomes support matrix degradation, reprogram stroma and hematopoietic cells and drive non-metastatic ASML-CD151/Tspan8 kd cells towards a motile phenotype.

WOS: 000348334900004, Objective: Alzheimer's disease (AD) is a progressive and irreversible central nervous system disease, which slowly destroys cognitive skills and memory, and eventually even the ability to handle the simplest tasks. The initiation and progression of AD is a poorly understood complex process. Here, we have investigated possible biological mechanisms that could be responsible for the increased risk for diminished brain function associated with diabetes in AD. Method: The U87 cell line (human primary glioblastoma cell line) was cultured in Dulbecco's modified Eagle's medium. Cells were incubated with insulin (10 mu g/ml), low glucose (11 mM, 2 mg/ml) and high glucose (55 mM, 10 mg/ml) for 48 hours. Cells were harvested and protein isolations were performed. Primary anti-ADAMTS5, anti-IL-33, anti-NF kappa B, and anti-GAPDH antibodies were used to detect corresponding proteins and to measure band densities in Western membranes using a specific program. Results: Western blot analysis showed ADAMTS5 protein decreases in insulin-applied U87 cells. High glucose application led to a notable increase in ADAMTS5 levels in cells, while low glucose application caused a moderate increase in ADAMTS5 levels. An apparent induction of IL-33 protein was observed in high glucose-applied cells, while a moderate decrease was noted in the low-glucose applied group. Insulin administration led to a decrease in IL-33 levels. Immunoreaction of NF kappa B with corresponding antibody was found to be sharply decreased in insulin-applied cells while low and high glucose application led to a moderate decrease in NF kappa B. Conclusion: This is the first reported study that has investigated both aggrecanases and inflammation mediators in the same experimental setup with U87 cells and interpreted the results in the various aspects of AD pathophysiology related to diabetes and hyperglycemia. Our findings suggest that insulin and glucose may have important functions in the synthesis of ADAMTS, IL-33, and NF kappa B through undefined mechanism(s). Further investigations dealing with all aggrecanases and other class of ADAMTS enzymes should be carried out together with the above-mentioned parameters with the collaboration of molecular biology, genetics, immunology, and other related disciplines in order to elaborate the pathophysiological importance of ADAMTS enzymes and inflammation mediators in AD.

Background & Aims The mannose 6-phosphate/insulin-like growth factor II receptor (M6P/IGF2R), a multifunctional protein, plays a central role in intracellular targeting of lysosomal enzymes and control of insulin-like growth factor II (IGF-II) bioactivity. Importantly, the gene encoding this receptor is frequently inactivated in a wide range of malignant tumors including hepatocellular carcinomas. Thus, M6P/IGF2R is considered a putative liver tumor suppressor. The aim of this study was to establish the impact of the receptor on the invasive properties of liver cells. Methods Reconstitution experiments were performed by expression of wild type and mutant M6P/IGF2R in receptor-deficient FRL14 fetal rat liver cells. RNA interference was used to induce M6P/IGF2R downregulation in receptor-positive MIM-1–4 mouse hepatocytes. Results We show that the M6P/IGF2R status exerts a strong impact on the invasiveness of tumorigenic rodent liver cells. M6P/IGF2R-deficient fetal rat liver cells hypersecrete lysosomal cathepsins and penetrate extracellular matrix barriers in a cathepsin-dependent manner. Forced expression of M6P/IGF2R restores intracellular transport of cathepsins to lysosomes and concomitantly reduces the tumorigenicity and invasive potential of these cells. Conversely, M6P/IGF2R knock-down in receptor-positive mouse hepatocytes causes increased cathepsin secretion as well as enhanced cell motility and invasiveness. We also demonstrate that functional M6P-binding sites are important for the anti-invasive properties of M6P/IGF2R, whereas the capacity to bind IGF-II is dispensable for the anti-invasive activity of the receptor in liver cells. Conclusions M6P/IGF2R restricts liver cell invasion by preventing the pericellular action of M6P-modified proteins.

Summary Objective To determine the time sequence of biochemical and structural events associated with, and hypothesized to underlie, age-associated tensile weakening of macroscopically normal adult human articular cartilage of the knee. Methods Macroscopically normal human articular cartilage of the lateral and medial femoral condyles (LFC and MFC) from Young (21–39 yrs), Middle (40–59 yrs), and Old (≥60 yrs) age donors were analyzed for tensile properties, surface wear, and cell and matrix composition. Results Variations in tensile, compositional, and surface structural properties were indicative of early, intermediate, and late stages of age-associated cartilage deterioration, occurring at an earlier age in the MFC than the LFC. Differences between Young and Middle age groups (indicative of early-to-intermediate stage changes) included decreased mechanical function in the superficial zone, with a loss of (or low) tensile integrity, and surface wear, with faint striations and mild staining on the articular surface after application of India ink. Differences between Middle and Old age groups (indicative of intermediate-to-late stage changes) included maintenance of moderate level biomechanical function, a decrease in cellularity, and a decrease in matrix glycosaminoglycan content. Tissue fluorescence increased steadily with age. Conclusions Many of these age-associated differences are identical to those regarded as pathological features of cartilage degeneration in early osteoarthritis. These findings provide evidence for the roles of mechanical wear, cell death, and enzymatic degradation in mediating the progression through successive and distinguishable stages of early cartilage deterioration.

The collagen receptor uPARAP/Endo180, the product of the MRC2 gene, is a central component in the collagen turnover process governed by various mesenchymal cells. Through the endocytosis of collagen or large collagen fragments, this recycling receptor serves to direct basement membrane collagen as well as interstitial collagen to lysosomal degradation. This capacity, shared only with the mannose receptor from the same protein family, endows uPARAP/Endo180 with a critical role in development and homeostasis, as well as in pathological disruptions of the extracellular matrix structure. Important pathological functions of uPARAP/Endo180 have been identified in various cancers and in several fibrotic conditions. With a particular focus on matrix turnover in cancer, this review presents the necessary background for understanding the function of uPARAP/Endo180 at the molecular and cellular level, followed by an in-depth survey of the available knowledge of the expression and role of this receptor in various types of cancer and other degenerative diseases.

Joint injuries are common, especially among young adults aged 18 to 44 years. They are accompanied by a cascade of events that increase the risk of posttraumatic osteoarthritis (PTOA). Therefore, understanding of biological responses that predispose to PTOA should help in determining treatment modalities to delay and/or prevent the onset and progression of the disease. The vast majority of the literature pointed to chondrocyte death and apoptosis, inflammation and matrix damage/fragmentation being the earliest events that follow joint trauma. Together these events lead to the development of osteoarthritis-like focal cartilage lesions that if untreated have a tendency to expand and progress to fully developed disease. Currently, the only treatments available for joint trauma are surgical interventions. Experimental biologic approaches involve engineering of cartilage with the use of cells (stem cells or chondrocytes), juvenile or adult cartilage pieces, scaffolds, and various polymeric matrices. The major challenge for all of them is regeneration of normal functional mature hyaline cartilage that can sustain the load, resist compression, and most important, integrate with the host tissue. If the tissue is spontaneously repaired it fails to reproduce original structure and function and thus, may be more susceptible to re-injury. Thus, there is a critical need to develop novel molecular mechanism-based therapeutic approaches to biologic chondral and/or osteochondral repair. The focus of this review is on the earliest molecular and cellular manifestations of injury that can be grouped based on the following therapeutic options for PTOA: chondroprotection, anti-inflammatory, matrix protection, and matrix remodeling/matrix synthesis.

Due to its aggressive behavior, pancreatic cancer is one of the principal causes of cancer-related deaths. The highly metastatic potential of pancreatic tumor cells demands the development of more effective anti-metastatic approaches for this disease. Although polyethylenimine-coated superparamagnetic iron oxide nanoparticles (PEI-coated SPIONs) have been studied for their utility as transfection agents, little is known of their effect on tumor cell biology. Here we demonstrated that PEI-coated SPIONs have potent inhibitory effects on pancreatic tumor cell migration/invasion, through inhibition of Src kinase and decreased expression of MT1-MMP and MMP2 metalloproteinases. When treated with PEI-coated SPIONs, the pancreatic tumor cell line Pan02 showed reduced invadosome density and thus, a decrease in their ability to invade through basement membrane. These nanoparticles temporarily downmodulated microRNA-21, thereby upregulating the cell migration inhibitors PTEN, PDCD4 and Sprouty-1. PEI-coated SPIONs thus show intrinsic, possibly anti-metastatic properties for modulating pancreatic tumor cell migration machinery, which indicates their potential as anti-metastatic agents for treatment of pancreatic cancer., VMA is a PhD fellow of the La Caixa Foundation International Fellowship Programme (La Caixa/CNB). JMR was supported by a JAEdoc contract from the Spanish Ministry of Economy and Competitiveness (MINECO), co-financed by the European Social Fund. This work was supported in part by grants from the MINECO (SAF-2011-23639 and SAF-2014-54057-R to DFB; MAT2011-23641 to MPM).

Cultured fibroblasts from the dermis of normal subjects and of Pseudoxanthoma elasticum (PXE) patients were analysed for enzyme activity, protein and mRNA expression of metalloproteases (MMP-2, MMP-3, MMP-9, MT1-MMP) and of their specific inhibitors (TIMP-1, TIMP-2 and TIMP-3). MMP-3, MMP-9 and TIMP-3 mRNAs and proteins failed to be detected in both the medium and the cell layer of both controls and PXE patients. MMP-2 mRNA was significantly more expressed in PXE than in control cell lines, whereas MT1-MMP, TIMP-1 and TIMP-2 mRNAs appeared unchanged. MMP-2 was significantly higher in the cell extracts from PXE fibroblasts than in control cells, whereas differences were negligible in the cell medium. Data suggest that PXE fibroblasts have an increased proteolytic potential, and that MMP-2 may actively contribute to connective tissue alterations in this genetic disorder.

Objective: The damage to cartilage collagen is a central event in the pathogenesis of cartilage aging and osteoarthritis (OA). We have previously developed an in vitro model of cartilage degradation which shows that chondrocyte-dependent lipid peroxidation mediates cartilage collagen degradation. The goal of our study was to investigate the role of vitamin C in this degradation model and to investigate effect of chondrocyte-dependent lipid peroxidation in the oxidation of cartilage collagen. Methods: We studied primary articular chondrocytes. Effect of vitamin C was investigated in the previously described model. Serum-free stimulated and unstimulated chondrocyte-matrix extracts were subjected to SDS-PAGE and immunoblot analysis. Malondialdehyde (MDA)-protein oxidation of cartilage proteins was demonstrated by the reactivity of chondrocyte extracts to a monoclonal antibody, MDA2, which detects MDA–lysine adducts. Results: Vitamin C treatment of chondrocyte cultures resulted in significant enhanced incorporation of 3H-proline label in cell-matrix. Cells treated with vitamin C, as compared to control untreated cells showed decreased spontaneous release of labeled matrix. Vitamin C treated or not treated chondrocytes responded comparably to stimulation with the agonist calcium ionophore A23187. The serum-free in vitro culture of chondrocytes resulted in MDA-protein oxidation. The treatment of chondrocytes with A23187 resulted in the enhancement of MDA-protein oxidation. The immunoblot reactivity pattern of extracts to MDA2 antibody and to polyclonal anti-type II collagen antibody was somewhat similar, which suggests that these two different types of antisera exibit a crossreaction to chondrocyte proteins. Chondrocyte extracts were pretreated both with and without pure collagenase, and then subjected to immunoblot analysis. Only collagenase treated extracts showed a disappearence, or significant reduction, of larger than 60kDa size MDA2 immunoreactive proteins. This suggests that the proteins that disappeared after the enzyme treatment were collagen proteins and which had also been modified by MDA oxidation. Conclusions: These observations suggest that collagen hydroxylation of matrix by vitamin C does not play a role in this model of chondrocyte-dependent collagen degradation. Also, this study demonstrates that chondrocyte-derived lipid peroxidation product MDA mediates oxidation of cartilage collagens. Oxidative modification of cartilage collagen in vivo could result in alteration of biochemical and biophysical properties of cartilage collagen fibrils, making them prone to degradation, thus initiating the changes observed in aging and OA.

One of the major reasons for failure after total joint arthroplasty is aseptic loosening of the implant. At articulating surfaces, defined as the interface between implant and surrounding bone cement, wear particles can be generated and released into the periprosthetic tissue, resulting in inflammation and osteolysis. The aim of the present study was to evaluate the extent to which osteoblasts and macrophages are responsible for the osteolytic and inflammatory reactions following contact with generated wear particles from Ti‑6Al‑7Nb and Co‑28Cr‑6Mo hip stems. To this end, human osteoblasts and THP‑1 monocytic cells were incubated with the experimentally generated wear particles as well as reference particles (0.01 and 0.1 mg/ml) for 48 h under standard culture conditions. To evaluate the impact of these particles on the two cell types, the release of different bone matrix degrading matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs), and relevant cytokines were determined by multiplex enzyme‑linked immunosorbent assays. Following incubation with wear particles, human osteoblasts showed a significant upregulation of MMP1 and MMP8, whereas macrophages reacted with enhanced MMP3, MMP8 and MMP10 production. Moreover, the synthesis of TIMPs 1 and 2 was inhibited. The osteoblasts and macrophages also responded with modified expression of the inflammatory mediators interleukin (IL)‑6, IL‑8, monocyte chemoattractant protein‑1 and vascular endothelial growth factor. These results demonstrate that the release of wear particles affects the release of proinflammatory cytokines and has a negative impact on bone matrix formation during the first 48 h of particle exposure. Human osteoblasts are directly involved in the proinflammatory cascade of bone matrix degradation. The simultaneous activation and recruitment of monocytes/macrophages boosted osteolytic processes in the periprosthetic tissue. By the downregulation of TIMP production and the concomitant upregulation of MMPs as a response to particle exposure, bone formation around implants may be suppressed, resulting in implant failure.

Journal of hepatology 63(4), 1038-1039 (2015). doi:10.1016/j.jhep.2015.03.039, Published by Elsevier Science, Amsterdam [u.a.]

Effects of glucose on matrix metalloproteinase and plasmin activities in mesangial cells: Possible role in diabetic nephropathy. Diabetic nephropathy is characterized by an accumulation of mesangium matrix that correlates well with the loss of kidney function. High glucose concentration is known to increase the synthesis of many matrix components. Recently, we have shown that degradation of matrix also decreases in diabetes. The major enzymes responsible for matrix degradation are the matrix metalloproteinases. The physiology of these enzymes is complex and their activity is tightly regulated at many levels. At the transcriptional level matrix metalloproteinase (MMP) expression is increased by protein kinase C (PKC) agonists, and some growth factors. In contrast transforming growth factor (TGF)-β can decrease MMP expression. Once synthesized, MMPs are secreted as inactive pro-enzymes that are activated by other MMPs or plasmin. To effect this, plasmin must be liberated from plasminogen in the pericellular environment. In turn, activated MMPs can be inhibited by binding to specific inhibitors known as tissue inhibitor of metalloproteinases (TIMP). Cell culture and animal studies have shown that high glucose (HG) decreases expression of MMPs and increases expression of TIMPs. HG can also affect MMP activation by decreasing plasmin availability and reducing expression of a membrane-bound MMP called MT1-MMP. How HG induces these changes remains to be fully elucidated. One possibility is that HG can increase TGF-β, which may in turn alter MMP promoter activity; this area is currently being studied in our laboratory.

Bacterial enzymes have long been considered solely accountable for the degradation of the dentin matrix during the carious process. However, the emerging literature suggests that host-derived enzymes, and in particular the matrix metalloproteinases (MMPs) contained in dentin and saliva can play a major role in this process by their ability to degrade the dentin matrix from within. These findings are important since they open new therapeutic options for caries prevention and treatment. The possibility of using MMP inhibitors to interfere with dentin caries progression is discussed. Furthermore, the potential release of bioactive peptides by the enzymatic cleavage of dentin matrix proteins by MMPs during the carious process is discussed. These peptides, once identified, may constitute promising therapeutical tools for tooth and bone regeneration.

Chronic Obstructive Pulmonary Disease (COPD) is one of the foremost causes of death worldwide. It is primarily caused by tobacco smoke, making it an easily preventable disease, but facilitated by genetic α-1 antitrypsin deficiency. In addition to active smokers, health problems also occur in people involuntarily exposed to second hand smoke (SHS). Currently, the relationship between SHS and COPD is not well established. Knowledge of pathogenic mechanisms is limited, thereby halting the advancement of new treatments for this socially and economically detrimental disease. Here, we attempt to summarize tobacco smoke studies undertaken in animal models, applying both mainstream (direct, nose only) and side stream (indirect, whole body) smoke exposures. This overview of 155 studies compares cellular and molecular mechanisms as well as proteolytic, inflammatory, and vasoreactive responses underlying COPD development. This is a difficult task, as listing of exposure parameters is limited for most experiments. We show that both mainstream and SHS studies largely present similar inflammatory cell populations dominated by macrophages as well as elevated chemokine/cytokine levels, such as TNF-α. Additionally, SHS, like mainstream smoke, has been shown to cause vascular remodeling and neutrophil elastase-mediated proteolytic matrix breakdown with failure to repair. Disease mechanisms and therapeutic interventions appear to coincide in both exposure scenarios. One of the more widely applied interventions, the anti-oxidant therapy, is successful for both mainstream and SHS. The comparison of direct with indirect smoke exposure studies in this review emphasizes that, even though there are many overlapping pathways, it is not conclusive that SHS is using exactly the same mechanisms as direct smoke in COPD pathogenesis, but should be considered a preventable health risk. Some characteristics and therapeutic alternatives uniquely exist in SHS-related COPD.

We have investigated the susceptibility of both the helical and non-helical regions of isolated rat chondrosarcoma collagens, types II, IX and XI, to degradation by the cysteine proteinases, cathepsins B and L. Both enzymes degrade these collagens at temperatures from 20 to 37°C and pH values from 3.5 to 7.0. Cleavage occurs only within the non-helical domains unless the helix is destabilized. Cathepsin L is more effective than cathepsin B on a molar basis and they appear to cleave at different sites. Since these cathepsins can degrade cartilage collagens at pH values near neutrality, they may contribute to the destruction of cartilage observed in arthritis.

The membrane-type matrix metalloproteinases (MT-MMPs) are a subclass of the matrix metalloproteinase (MMP) family which uniquely possess a C-terminal transmembrane domain and are initiators of an activation cascade for progelatinase A (MMP-2). Recent studies have shown that they can also efficiently directly degrade a number of matrix macromolecules. We now show that cells expressing MT1-MMP on their cell surfaces cause subjacent proteolysis of a gelatin film and that this proteolysis is inhibited by TIMP-2 but not by TIMP-1. These data indicate that expression of MT1-MMP on the cell surface may lead to both progelatinase A activation and extracellular matrix degradation.

Optical and electron microscopical evidences of focal matrix degradation were frequently seen in liver sections of periportal fibrosis caused by schistosomiasis mansoni in man. The material came from 14 wedge hepatic biopsies taken from patients with chronic advanced hepatosplenic disease and undergoing operations for the relief of portal hypertension. Besides the presence of focal areas of rarefaction, fragmentation and dispersion of collagen fibers, the enlarged portal spaces also showed hyperplasia of elastic tissue and disarray of smooth muscle fibers following destruction of portal vein branches. Eggs were scanty in the tissue sections, and matrix degradation probably represented involuting changes related to the progressive diminution of parasite-related aggression, which occurs spontaneously with age or after cure by chemotherapy. The changes indicative of matrix degradation now described are probably the basic morphological counterpart of periportal fibrosis involution currently being documented by ultrasonography in hepatosplenic patients submitted to curative chemotherapy. Um estudo feito com microscopia ótica e eletrônica permitiu verificar sinais de degradação da matriz extracelular na fibrose periportal humana causada pela esquistossomose avançada. O material de estudo proveio de 14 biópsias hepáticas em cunha feitas em portadores de esquistossomose hepato-esplênica, no momento em que eles foram submetidos a cirurgia para o alívio das manifestações de hipertensão porta. Além da presença de áreas focais de rarefação, fragmentação e dispersão dos feixes colgenos, os espaços porta alargados e fibrosados também mostraram hiperplasia do tecido elástico e dissociação de fibras musculares lisas em seguida à destruição de ramos da veia porta. Os ovos do parasito eram escassos nas secções histológicas. A degradação da matriz provavelmente representa processo involutivo relacionado com a progressiva diminuição da agressão parasitária, o que pode ocorrer espontaneamente em casos de longa duração ou após a cura pela quimioterapia. As alterações indicativas de degradação da matriz aqui descritas representam provavelmente a face morfológica da involução da fibrose periportal que vem sendo atualmente documentada pela ultrasonografia em pacientes hepato-esplênicos submetidos à quimioterapia curativa.

The fibronectin-related region of the 72 kDa type IV procollagenase has been expressed in E. coli as a β-galactosidase fusion product. The fragment containing the three type II units of the protein was found to have affinity for denatured collagen, suggesting that these domains may be responsible for the collagen-affinity of type IV collagenase. We have also shown that segment Ala-Ala-His-Glu of type IV collagenase (residues 372–375), which is similar to a fibronectin-segment previously implicated in collagen-binding, is not essential for binding activity.