Human neutrophil collagenase. A distinct gene product with homology to other matrix metalloproteinases

Burn-Related Glycocalyx Derangement and the Emerging Role of MMP8 in Syndecan Shedding

Burn injuries often lead to severe complications, including acute respiratory distress syndrome (ARDS), driven in part by systemic inflammation and glycocalyx disruption. In this study, we analyzed the sera of 28 patients after burn trauma and utilized single-cell RNA sequencing (scRNA-seq) along with microarray transcriptomic analysis to decipher the impact of burn injury on glycocalyx derangement. We observed the significant upregulation of immune cell-derived degrading enzymes, particularly matrix metalloproteinase-8 (MMP8), which correlated with increased immune cell infiltration and glycocalyx derangement. Serum analyses of burn patients revealed significantly elevated levels of shed glycocalyx components and MMP8, both correlating with the presence of inhalation injury. Consequently, the treatment of human in vitro lung tissue models with MMP8 induced significant glycocalyx shedding in alveolar epithelial cells. Together, based on these findings, we propose that MMP8 plays a previously unrecognized role in glycocalyx disruption and subsequent lung injury post-burn, which implies that inhibiting MMP8 may represent a promising therapeutic strategy for alleviating lung injury after burn trauma.

Accelerated Adaptation of SARS-CoV-2 Variants in Mice Lacking IFITM3 Preserves Distinct Tropism and Pathogenesis

Here we investigated whether interferon induced transmembrane protein 3 (IFITM3), a key antiviral protein deficient in certain human populations, affects interspecies adaptation of SARS-CoV-2. We found that SARS-CoV-2 Beta and Omicron variants passaged through IFITM3-deficient versus wild type mice exhibit enhanced replication and pathogenesis in this new host species. Enhancements associated with amino acid substitutions in the viral genome, suggesting that IFITM3 limits accumulation of adaptive mutations. Mouse-adapted viruses enabled comparative studies of variants in mice. Beta caused lung dysfunction and altered cilia-associated gene programs, consistent with broad viral antigen distribution in lungs. Omicron, which shows low pathogenicity and upper respiratory tract preference in humans, replicated to high nasal titers while showing restrained spatial distribution in lungs and diminished lung inflammatory responses compared to Beta. Our findings demonstrate that IFITM3 deficiency accelerates coronavirus adaptation and reveal that intrinsic SARS-CoV-2 variant traits shape tropism, immunity, and pathogenesis across hosts.

HIGHLIGHTS

IFITM3 is a critical barrier to SARS-CoV-2 adaptation in new host speciesMouse-adapted SARS-CoV-2 strains enable comparative pathologyOmicron favors nose and large airways, leading to mild lung pathologyBeta exhibits broad lung replication, driving severe inflammation and dysfunction.

Association between metabolic syndrome and salivary MMP-8, myeloperoxidase in periodontitis

OBJECTIVE

This study investigated the effect of metabolic syndrome (MetS) on periodontal clinical parameters and salivary biomarkers' matrix metalloproteinase-8 (MMP-8) and myeloperoxidase (MPO) in patients with periodontitis.

METHODS

A total of 120 participants aged 25-55 were categorized into three groups: MetS with periodontitis (n = 40); systemically healthy with periodontitis (n = 40); and systemically and periodontally healthy controls (n = 40). Data collected included systemic parameters like waist circumference (WC), blood pressure (BP), high- and low-density lipoproteins, triglycerides (TG), fasting blood sugar (FBS), and glycated hemoglobin (HbA1c). Periodontal parameters estimated included bleeding on probing score (BoP), full-mouth plaque score (FMPS), periodontal probing depth (PPD), clinical attachment loss (CAL), and the number of missing teeth. Unstimulated whole saliva was analyzed via ELISA for active MMP-8 (aMMP-8), total MMP-8 (tMMP-8), and MPO.

RESULTS

Participants with MetS and periodontitis exhibited significantly higher periodontal parameters, salivary aMMP-8, and MPO (26.26 vs. 24.1 ng/mL and 13.53 vs. 11.55 ng/mL compared to systemically healthy periodontitis patients) (all p < 0.01). Positive correlations occurred between aMMP-8 and WC, TG, and FBS (p < 0.01), and between MPO and WC, BP, and TG (p < 0.01).

CONCLUSIONS

The positive associations between these biomarkers and metabolic parameters indicate their potential utility for monitoring cardiovascular and glycemic risk in patients with periodontal disease.

In Vivo Regulation of Active Matrix Metalloproteinase-8 (aMMP-8) in Periodontitis: From Transcriptomics to Real-Time Online Diagnostics and Treatment Monitoring

BACKGROUND

This study investigated in vivo regulation and levels of active matrix metalloproteinase-8 (aMMP-8), a major collagenolytic protease, in periodontitis.

METHODS

Twenty-seven adults with chronic periodontitis (CP) and 30 periodontally healthy controls (HC) were enrolled in immunohistochemistry and transcriptomics analytics in order to assess Treponema denticola (Td) dentilisin and MMP-8 immunoexpression, mRNA expression of MMP-8 and its regulators (IL-1β, MMP-2, MMP-7, TIMP-1). Furthermore, the periodontal anti-infective treatment effect was monitored by four different MMP-8 assays (aMMP-8-IFMA, aMMP-8-Oralyzer, MMP-8-activity [RFU/minute], and total MMP-8 by ELISA) among 12 CP (compared to 25 HC).

RESULTS

Immunohistochemistry revealed significantly more Td-dentilisin and MMP-8 immunoreactivities in CP vs. HC. Transcriptomics revealed significantly elevated IL-1β and MMP-7 RNA expressions, and MMP-2 RNA was slightly reduced. No significant differences were recorded in the relatively low or barely detectable levels of MMP-8 mRNAs. Periodontal treatment significantly decreased all MMP-8 assay levels accompanied by the assessed clinical indices (periodontal probing depths, bleeding-on-probing, and visual plaque levels). However, active but not total MMP-8 levels persisted higher in CP than in periodontally healthy controls.

CONCLUSION

In periodontal health, there are low aMMP-8 levels. The presence of Td-dentilisin in CP gingivae is associated with elevated aMMP-8 levels, potentially contributing to a higher risk of active periodontal tissue collagenolysis and progression of periodontitis. This can be detected by aMMP-8-specific assays and online/real-time aMMP-8 chair-side testing.

Active Matrix Metalloproteinase-8 (aMMP-8) Versus Total MMP-8 in Periodontal and Peri-Implant Disease Point-of-Care Diagnostics

Active matrix metalloproteinase-8 (aMMP-8) is a promising biomarker candidate for the modern periodontal and peri-implant disease diagnostics utilizing the chairside/point-of-care oral fluid technologies. These rapid biomarker analysis technologies utilize gingival crevicular fluid (GCF), peri-implant sulcular fluid (PISF), or mouth rinse as the oral fluid matrices that can be collected patient-friendly and non-invasively without causing bacteremia. aMMP-8, but not total or latent proMMP-8, has been shown to be a relevant biomarker to be implemented to the latest 2017 classification system of periodontitis and peri-implantitis. Thus, aMMP-8 point-of-care-testing (POCT)-but not total or latent proMMP-8-can be conveniently used as an adjunctive and preventive diagnostic tool to identify and screen the developing and ongoing periodontal and peri-implant breakdown and disease as well as predict its episodic progression. Similarly, aMMP-8 POCT provides an important tool to monitor the treatment effect of these diseases, but also other diseases such as head and neck cancer, where it can identify and predict the rapid tissue destructive oral side-effects during and after the radiotherapy. Additionally, recent studies support aMMP-8 POCT benefitting the identification of periodontitis and diabetes as the escalating risk diseases for COVID-19 infection. Overall, aMMP-8 POCT has launched a new clinical field in oral medicine and dentistry, i.e., oral clinical chemistry.

A cercarial invadolysin interferes with the host immune response and facilitates infection establishment of Schistosoma mansoni

Schistosoma mansoni employs immune evasion and immunosuppression to overcome immune responses mounted by its snail and human hosts. Myriad immunomodulating factors underlie this process, some of which are proteases. Here, we demonstrate that one protease, an invadolysin we have termed SmCI-1, is released from the acetabular glands of S. mansoni cercaria and is involved in creating an immunological milieu favorable for survival of the parasite. The presence of SmCI-1 in the cercarial stage of S. mansoni is released during transformation into the schistosomula. SmCI-1 functions as a metalloprotease with the capacity to cleave collagen type IV, gelatin and fibrinogen. Additionally, complement component C3b is cleaved by this protease, resulting in inhibition of the classical and alternative complement pathways. Using SmCI-1 knockdown cercariae, we demonstrate that SmCI-1 protects schistosomula from complement-mediated lysis in human plasma. We also assess the effect of SmCI-1 on cytokine release from human peripheral blood mononuclear cells, providing compelling evidence that SmCI-1 promotes an anti-inflammatory microenvironment by enhancing production of IL-10 and suppressing the production of inflammatory cytokines like IL-1B and IL-12p70 and those involved in eosinophil recruitment and activation, like Eotaxin-1 and IL-5. Finally, we utilize the SmCI-1 knockdown cercaria in a mouse model of infection, revealing a role for SmCI-1 in S. mansoni survival.

Cellular responses in the FGF10-mediated improvement of hindlimb regenerative capacity in Xenopus laevis revealed by single-cell transcriptomics

Xenopus laevis tadpoles possess regenerative capacity in their hindlimb buds at early developmental stages (stages ~52-54); they can regenerate complete hindlimbs with digits after limb bud amputation. However, they gradually lose their regenerative capacity as metamorphosis proceeds. Tadpoles in late developmental stages regenerate fewer digits (stage ~56), or only form cartilaginous spike without digits or joints (stage ~58 or later) after amputation. Previous studies have shown that administration of fibroblast growth factor 10 (FGF10) in late-stage (stage 56) tadpole hindlimb buds after amputation can improve their regenerative capacity, which means that the cells responding to FGF10 signaling play an important role in limb bud regeneration. In this study, we performed single-cell RNA sequencing (scRNA-seq) of hindlimb buds that were amputated and administered FGF10 by implanting FGF10-soaked beads at a late stage (stage 56), and explored cell clusters exhibiting a differential gene expression pattern compared with that in controls treated with phosphate-buffered saline. The scRNA-seq data showed expansion of fgf8-expressing cells in the cluster of the apical epidermal cap of FGF10-treated hindlimb buds, which was reported previously, indicating that the administration of FGF10 was successful. On analysis, in addition to the epidermal cluster, a subset of myeloid cells and a newly identified cluster of steap4-expressing cells showed remarkable differences in their gene expression profiles between the FGF10- or phosphate-buffered saline-treatment conditions, suggesting a possible role of these clusters in improving the regenerative capacity of hindlimbs via FGF10 administration.

aMMP-8 Oral Fluid PoC Test in Relation to Oral and Systemic Diseases

The manuscript uses the previously published literature and highlights the benefits of active-matrix metalloproteinase (aMMP)-8 chairside/point-of-care (PoC) diagnostic tools as adjunctive measures in oral and systemic diseases. Previous studies suggest that as a biomarker, aMMP-8 is more precise than total MMP-8, MMP-9, MMP-2, MMP-3, MMP-13, MMP-7, MMP-1, calprotectin, myeloperoxidase (MPO), human neutrophil elastase (HNE), tissue inhibitor of matrix metalloproteinase (TIMP)-1, and bleeding of probing (BOP). Therefore, aMMP-8 could be implemented as the needed key biomarker for the new disease classification for both periodontitis and peri-implantitis. With a sensitivity to the tune of 75-85% and specificity in the range of 80-90%, lateral flow aMMP-8 PoC testing is comparable to catalytic protease activity assays for aMMP-8. The test can be further applied to estimate the glycemic status of an individual, to ascertain whether a person is at risk for COVID-19, in managing the oral side effects of radiotherapy carried in head and neck cancers, and in selected cases pertaining to reproductive health. In the future, aMMP-8 could find application as a potential systemic biomarker in diseases affecting the cardiovascular system, cancers, bacteremia, sepsis, diabetes, obesity, meningitis, as well as pancreatitis. The aMMP-8 PoCT is the first practical test in the emerging new dental clinical field, that is, oral clinical chemistry representing oral medicine, clinical chemistry, peri-implantology, and periodontology.

TNF-α, IL-1β, MMP-8 Crevicular Profile in Patients with Chronic Kidney Disease and Periodontitis

Increasing evidence sustains the potential of periodontitis as a risk factor for chronic kidney disease (CKD). Our study aimed to analyze several periodontal specific inflammatory biomarkers within the gingival crevicular fluid (GCF) of patients with CKD, compared to patients with normal kidney function, providing an inflammatory profile of the dialysis patient. The study comprised 79 patients divided into: group 1 (59 subjects with periodontitis and CKD) and group 2 (20 patients with periodontitis, without other systemic conditions). Clinical diagnosis was performed via dental and periodontal examination. GCF samples were collected from each patient, and the levels of TNF-α, IL-1β and MMP-8 were determined by using ELISA assay. In group 1, the average values were: 22.85 ± 5.87 pg/mL for TNF-α, 33.00 ± 39.68 pg/mL for IL-1β and 18.80 ± 27.75 ng/mL for MMP-8. In group 2, the mean values were: 2.10 ± 1.34 pg/mL for TNF-α, 0.71 ± 2.42 pg/mL for IL-1β and 5.35 ± 0.37 ng/mL for MMP-8. Statistical analysis revealed significant differences between groups as referring to all three biomarkers and, TNF-α and MMP-8, in certain stages of periodontitis. The level of TNF-α, IL-1β and MMP-8 points out the increased inflammatory status of the dialysis patient with PD, supporting the mutual connection of the two pathologies.

Associations between matrix metalloproteinase, tissue inhibitor of metalloproteinase and collagen expression levels in the adjacent rectal tissue of colorectal carcinoma patients

As the commonest type of cancer in Europe and the third most common type of cancer worldwide, colorectal carcinoma (CRC) poses a challenge for numerous scientific studies. At present, the cause of this disease is remains to be elucidated, but early diagnosis is only one solution to prevent serious health complications. As a structural scaffold, the extracellular matrix (ECM) is in direct contact with tumour cells and significantly interferes with tumour progression. During the process of tumorigenesis, the ECM undergoes structural changes in which collagens serve an important role. Their life cycle is regulated by proteolytic enzymes called matrix metalloproteinases (MMPs), which are controlled by tissue inhibitors of metalloproteinases (TIMPs). The present study analysed the gene expression of MMPs (MMP1-2-8-10-13), TIMPs (TIMP1-2-4) and collagens (COL1A1 and COL3A1) and the correlation with biochemical parameters in the adjacent rectal tissue (ART) of patients with CRC. The patients who underwent standard neoadjuvant pre-therapy showed increased concentrations of collagen in the normal ART. The mRNA levels of COL3A1, TIMP1 and TIMP2 were significantly higher in the ART of CRC patients (with or without pre-therapy) when compared with the control group. This finding suggested that TIMPs served an important role in the regulation of MMPs and in the modification of collagen content in the ECM. Despite the small data set, the present study provided insights into the transcriptomic relationships between the individual genes that are an integral part of the ECM.

Protein and Microbial Biomarkers in Sputum Discern Acute and Latent Tuberculosis in Investigation of Pastoral Ethiopian Cohort

Differential diagnosis of tuberculosis (TB) and latent TB infection (LTBI) remains a public health priority in high TB burden countries. Pulmonary TB is diagnosed by sputum smear microscopy, chest X-rays, and PCR tests for distinct Mycobacterium tuberculosis (Mtb) genes. Clinical tests to diagnose LTBI rely on immune cell stimulation in blood plasma with TB-specific antigens followed by measurements of interferon-γ concentrations. The latter is an important cytokine for cellular immune responses against Mtb in infected lung tissues. Sputum smear microscopy and chest X-rays are not sufficiently sensitive while both PCR and interferon-γ release assays are expensive. Alternative biomarkers for the development of diagnostic tests to discern TB disease states are desirable. This study's objective was to discover sputum diagnostic biomarker candidates from the analysis of samples from 161 human subjects including TB patients, individuals with LTBI, negative community controls (NCC) from the province South Omo, a pastoral region in Ethiopia. We analyzed 16S rRNA gene-based bacterial taxonomies and proteomic profiles. The sputum microbiota did not reveal statistically significant differences in α-diversity comparing the cohorts. The genus Mycobacterium, representing Mtb, was only identified for the TB group which also featured reduced abundance of the genus Rothia in comparison with the LTBI and NCC groups. Rothia is a respiratory tract commensal and may be sensitive to the inflammatory milieu generated by infection with Mtb. Proteomic data supported innate immune responses against the pathogen in subjects with pulmonary TB. Ferritin, an iron storage protein released by damaged host cells, was markedly increased in abundance in TB sputum compared to the LTBI and NCC groups, along with the α-1-acid glycoproteins ORM1 and ORM2. These proteins are acute phase reactants and inhibit excessive neutrophil activation. Proteomic data highlight the effector roles of neutrophils in the anti-Mtb response which was not observed for LTBI cases. Less abundant in the sputum of the LTBI group, compared to the NCC group, were two immunomodulatory proteins, mitochondrial TSPO and the extracellular ribonuclease T2. If validated, these proteins are of interest as new biomarkers for diagnosis of LTBI.

Actions and interactions of IGF-I and MMPs during muscle regeneration

Muscle regeneration requires the coordination of several factors to mobilize satellite cells and macrophages, remodel the extracellular matrix surrounding muscle fibers, and repair existing and/or form new muscle fibers. In this review, we focus on insulin-like growth factor I and the matrix metalloproteinases, which are secreted proteins that act on cells and the matrix to resolve damage. While their actions appear independent, their interactions occur at the transcriptional and post-translational levels to promote feed-forward activation of each other. Together, these proteins assist at virtually every step of the repair process, and contribute significantly to muscle regenerative capacity.

A neutrophil activation signature predicts critical illness and mortality in COVID-19

Pathologic immune hyperactivation is emerging as a key feature of critical illness in COVID-19, but the mechanisms involved remain poorly understood. We carried out proteomic profiling of plasma from cross-sectional and longitudinal cohorts of hospitalized patients with COVID-19 and analyzed clinical data from our health system database of more than 3300 patients. Using a machine learning algorithm, we identified a prominent signature of neutrophil activation, including resistin, lipocalin-2, hepatocyte growth factor, interleukin-8, and granulocyte colony-stimulating factor, which were the strongest predictors of critical illness. Evidence of neutrophil activation was present on the first day of hospitalization in patients who would only later require transfer to the intensive care unit, thus preceding the onset of critical illness and predicting increased mortality. In the health system database, early elevations in developing and mature neutrophil counts also predicted higher mortality rates. Altogether, these data suggest a central role for neutrophil activation in the pathogenesis of severe COVID-19 and identify molecular markers that distinguish patients at risk of future clinical decompensation.

Heat Shock Factor 1-dependent extracellular matrix remodeling mediates the transition from chronic intestinal inflammation to colon cancer

In the colon, long-term exposure to chronic inflammation drives colitis-associated colon cancer (CAC) in patients with inflammatory bowel disease. While the causal and clinical links are well established, molecular understanding of how chronic inflammation leads to the development of colon cancer is lacking. Here we deconstruct the evolving microenvironment of CAC by measuring proteomic changes and extracellular matrix (ECM) organization over time in a mouse model of CAC. We detect early changes in ECM structure and composition, and report a crucial role for the transcriptional regulator heat shock factor 1 (HSF1) in orchestrating these events. Loss of HSF1 abrogates ECM assembly by colon fibroblasts in cell-culture, prevents inflammation-induced ECM remodeling in mice and inhibits progression to CAC. Establishing relevance to human disease, we find high activation of stromal HSF1 in CAC patients, and detect the HSF1-dependent proteomic ECM signature in human colorectal cancer. Thus, HSF1-dependent ECM remodeling plays a crucial role in mediating inflammation-driven colon cancer.

A neutrophil activation signature predicts critical illness and mortality in COVID-19

Pathologic immune hyperactivation is emerging as a key feature of critical illness in COVID-19, but the mechanisms involved remain poorly understood. We carried out proteomic profiling of plasma from cross-sectional and longitudinal cohorts of hospitalized patients with COVID-19 and analyzed clinical data from our health system database of over 3,300 patients. Using a machine learning algorithm, we identified a prominent signature of neutrophil activation, including resistin, lipocalin-2, HGF, IL-8, and G-CSF, as the strongest predictors of critical illness. Neutrophil activation was present on the first day of hospitalization in patients who would only later require transfer to the intensive care unit, thus preceding the onset of critical illness and predicting increased mortality. In the health system database, early elevations in developing and mature neutrophil counts also predicted higher mortality rates. Altogether, we define an essential role for neutrophil activation in the pathogenesis of severe COVID-19 and identify molecular neutrophil markers that distinguish patients at risk of future clinical decompensation.

The Contribution of Neutrophils to the Pathogenesis of RSV Bronchiolitis

Acute viral bronchiolitis causes significant mortality in the developing world, is the number one cause of infant hospitalisation in the developed world, and is associated with the later development of chronic lung diseases such as asthma. A vaccine against respiratory syncytial virus (RSV), the leading cause of viral bronchiolitis in infancy, remains elusive, and hence new therapeutic modalities are needed to limit disease severity. However, much remains unknown about the underlying pathogenic mechanisms. Neutrophilic inflammation is the predominant phenotype observed in infants with both mild and severe disease, however, a clear understanding of the beneficial and deleterious effects of neutrophils is lacking. In this review, we describe the multifaceted roles of neutrophils in host defence and antiviral immunity, consider their contribution to bronchiolitis pathogenesis, and discuss whether new approaches that target neutrophil effector functions will be suitable for treating severe RSV bronchiolitis.

Tissue Inhibitor of Metalloproteinase-1 Promotes Polymorphonuclear Neutrophil (PMN) Pericellular Proteolysis by Anchoring Matrix Metalloproteinase-8 and -9 to PMN Surfaces

Matrix metalloproteinase (MMP)-8 and -9 released by degranulating polymorphonuclear cells (PMNs) promote pericellular proteolysis by binding to PMN surfaces in a catalytically active tissue inhibitor of metalloproteinases (TIMP)-resistant forms. The PMN receptor(s) to which MMP-8 and MMP-9 bind(s) is not known. Competitive binding experiments showed that Mmp-8 and Mmp-9 share binding sites on murine PMN surfaces. A novel form of TIMP-1 (an inhibitor of soluble MMPs) is rapidly expressed on PMN surfaces when human PMNs are activated. Membrane-bound TIMP-1 is the PMN receptor for pro- and active MMP-8 and -9 as shown by the following: 1) TIMP-1 is strikingly colocalized with MMP-8 and -9 on activated human PMN surfaces and in PMN extracellular traps; 2) minimal immunoreactive and active Mmp-8 or Mmp-9 are detected on the surface of activated Timp-1^-/- murine PMNs; and 3) binding of exogenous Timp-1 (but not Timp-2) to Timp-1^-/- murine PMNs reconstitutes the binding of exogenous pro-Mmp-8 and pro-Mmp-9 to the surface of Timp-1^-/- PMNs. Unlike full-length pro-Mmp-8 and pro-Mmp-9, mutant pro-Mmp proteins lacking the COOH-terminal hemopexin domain fail to bind to Mmp-8^-/-x Mmp-9^-/- murine PMNs. Soluble hemopexin inhibits the binding of pro-Mmp-8 and pro-Mmp-9 to Mmp-8^-/-x Mmp-9^-/- murine PMNs. Thus, the COOH-terminal hemopexin domains of pro-Mmp-8 and pro-Mmp-9 are required for their binding to membrane-bound Timp-1 on murine PMNs. Exposing nonhuman primates to cigarette smoke upregulates colocalized expression of TIMP-1 with MMP-8 and MMP-9 on peripheral blood PMN surfaces. By anchoring MMP-8 and MMP-9 to PMN surfaces, membrane-bound TIMP-1 plays a counterintuitive role in promoting PMN pericellular proteolysis occurring in chronic obstructive pulmonary disease and other diseases.

Uveal melanocytes express high constitutive levels of MMP-8 which can be upregulated by TNF-α via the MAPK pathway

Matrix metalloproteinase (MMP)-8 is the most potent MMP for degrading collagen type-1 and plays an important role in inflammatory reactions and tissue remolding processes. MMP-8 is expressed mainly by polymorphonuclear leukocytes and is not expressed constitutively by most non-leukocytes. We studied the constitutive and TNF-α-induced expression of MMP-8 in cultured human uveal melanocytes (UM) and the relevant signal pathways involved. Conditioned media and cells were collected from UM and other cell types. MMP-8 proteins and mRNA were measured using ELISA kit, western blot and real time RT-PCR, respectively. Phosphorylated p38 MAPK, ERK1/2, and JNK1/2 were measured by ELISA kit and western blot. Very high levels of MMP-8 proteins and mRNA were detected in the conditioned media and cell lysates in 11 UM cell lines and three uveal melanoma cell lines cultured without serum, but not in media and cell lysates from other ocular resident cells or 12 malignant cell lines from other tissues, with exception of cutaneous melanoma cells. TNF-α moderately increased MMP-8 mRNA and protein levels in a dose- and time-dependent manner, accompanied by a significant increase of phosphorylated JNK1/2 and ERK1/2 in cell lysates. ERK1/2 (U0126) and JNK1/2 (SP600125) inhibitors significantly blocked TNF-α-induced and constitutive expression of MMP-8 in UM. This is the first report on the expression and secretion of MMP-8 by UM and uveal melanoma cells. The data suggest that UM may play a role in the remolding process and pathogenesis of inflammatory-related diseases in the eye via secretion of MMP-8.

Expression of cytokines and chemokines in mouse skin treated with sulfur mustard

Sulfur mustard (2,2'-dichlorodiethyl sulfide, SM) is a chemical warfare agent that generates an inflammatory response in the skin and causes severe tissue damage and blistering. In earlier studies, we identified cutaneous damage induced by SM in mouse ear skin including edema, erythema, epidermal hyperplasia and microblistering. The present work was focused on determining if SM-induced injury was associated with alterations in mRNA and protein expression of specific cytokines and chemokines in the ear skin. We found that SM caused an accumulation of macrophages and neutrophils in the tissue within one day which persisted for at least 7 days. This was associated with a 2-15 fold increase in expression of the proinflammatory cytokines interleukin-1β, interleukin-6, and tumor necrosis factor α at time points up to 7 days post-SM exposure. Marked increases (20-1000 fold) in expression of chemokines associated with recruitment and activation of macrophages were also noted in the tissue including growth-regulated oncogene α (GROα/CXCL1), monocyte chemoattractant protein 1 (MCP-1/CCL2), granulocyte-colony stimulating factor (GCSF/CSF3), macrophage inflammatory protein 1α (MIP1α/CCL3), and IFN-γ-inducible protein 10 (IP10/CXCL10). The pattern of cytokines/chemokine expression was coordinate with expression of macrophage elastase/MMP12 and neutrophil collagenase/MMP8 suggesting that macrophages and neutrophils were, at least in part, a source of cytokines and chemokines. These data support the idea that inflammatory cell-derived mediators contribute to the pathogenesis of SM induced skin damage. Modulating the infiltration of inflammatory cells and reducing the expression of inflammatory mediators in the skin may be an important strategy for mitigating SM-induced cutaneous injury.

Leukocyte depletion does not affect the in vitro healing ability of platelet rich plasma

The clinical use of platelet-rich plasma (PRP) containing or deprived of leukocytes remains a subject of debate and a controversial issue. It is not yet clear whether leukocyte content has a positive or negative effect on tissue healing processes. Several studies, conducted mainly in the orthopedic field, support the use of leukocyte-poor (LP) PRP, whereas other studies have not identified any significant differences between the use of LP and leukocyte-rich PRP. In the present study, the role of leukocytes contained in PRP was assessed to verify their in vitro effect on fibroblasts and endothelial cells, which have a leading role in the biological processes associated with wound healing (including angiogenesis and matrix remodeling). The original sample of PRP was divided into two aliquots, one of which remained unaltered, while the other was deprived of leukocytes. The two aliquots were used in in vitro tests in order to verify the effects of leukocytes on proliferation, wound healing and tube formation, and in molecular analyses of growth factor and enzyme content. The present results highlighted a substantial overlap between the two formulations. This may be explained by similar levels of growth factors (vascular endothelial growth factor, thrombospondin-1, interferon-γ, platelet-derived growth factor-BB, -AA and -B, tumor growth factor-β1, fibroblast growth factor 7 and tumor necrosis factor-α) and enzymes (gelatinases and plasminogen activators) in the two formulations. These results support the hypothesis that the ability of the PRP to affect the in vitro biological response of endothelial cells and fibroblasts does not rely on the presence of leukocytes.

Photoprotective effects of topical ginseng leaf extract using Ultraflo L against UVB-induced skin damage in hairless mice

BACKGROUND

Abnormal activation of matrix metalloproteinases (MMPs) plays an important role in UV-induced wrinkle formation, which is a major dermatological problem. This formation occurs due to the degeneration of the extracellular matrix (ECM). In this study, we investigated the cutaneous photoprotective effects of Ultraflo L treated ginseng leaf (UTGL) in hairless mice.

METHODS

SKH-1 hairless mice (6 weeks of age) were randomly divided into four groups (8 mice/group). UTGL formulation was applied topically to the skin of the mice for 10 weeks. The normal control group received nonvehicle and was not irradiated with UVB. The UV control (UVB) group received nonvehicle and was exposed to gradient-UVB irradiation. The groups (GA) receiving topical application of UTGL formulation were subjected to gradient-UVB irradiation on 0.5 mg/cm2 [GA-low (GA-L)] and 1.0 mg/cm2 [(GA-high (GA-H)] of dorsal skin area, respectively.

RESULTS

We found that topical treatment with UTGL attenuated UVB-induced epidermal thickness and impairment of skin barrier function. Additionally, UTGL suppressed the expression of MMP-2, -3, and -13 induced by UVB irradiation. Our results show that topical application of UTGL protects the skin against UVB-induced damage in hairless mice and suggest that UTGL can act as a potential agent for preventing and/or treating UVB-induced photoaging.

CONCLUSION

UTGL possesses sunscreen properties and may exhibit photochemoprotective activities inside the skin of mice. Therefore, UTGL could be used as a potential therapeutic agent to protect the skin against UVB-induced photoaging.

Biochemical and Biological Attributes of Matrix Metalloproteinases

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that are involved in the degradation of various proteins in the extracellular matrix (ECM). Typically, MMPs have a propeptide sequence, a catalytic metalloproteinase domain with catalytic zinc, a hinge region or linker peptide, and a hemopexin domain. MMPs are commonly classified on the basis of their substrates and the organization of their structural domains into collagenases, gelatinases, stromelysins, matrilysins, membrane-type (MT)-MMPs, and other MMPs. MMPs are secreted by many cells including fibroblasts, vascular smooth muscle (VSM), and leukocytes. MMPs are regulated at the level of mRNA expression and by activation of their latent zymogen form. MMPs are often secreted as inactive pro-MMP form which is cleaved to the active form by various proteinases including other MMPs. MMPs cause degradation of ECM proteins such as collagen and elastin, but could influence endothelial cell function as well as VSM cell migration, proliferation, Ca²⁺ signaling, and contraction. MMPs play a role in tissue remodeling during various physiological processes such as angiogenesis, embryogenesis, morphogenesis, and wound repair, as well as in pathological conditions such as myocardial infarction, fibrotic disorders, osteoarthritis, and cancer. Increases in specific MMPs could play a role in arterial remodeling, aneurysm formation, venous dilation, and lower extremity venous disorders. MMPs also play a major role in leukocyte infiltration and tissue inflammation. MMPs have been detected in cancer, and elevated MMP levels have been associated with tumor progression and invasiveness. MMPs can be regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs), and the MMP/TIMP ratio often determines the extent of ECM protein degradation and tissue remodeling. MMPs have been proposed as biomarkers for numerous pathological conditions and are being examined as potential therapeutic targets in various cardiovascular and musculoskeletal disorders as well as cancer.

Serum collagenase-2 and BMI levels in pregnant women with striae gravidarum

OBJECTIVE

Striae gravidarum is a form of scarring on the skin observed during pregnancy and can cause serious cosmetic problems. Striae gravidarum may be influenced by hormonal changes, although the etiology is not clear. The aim of this study was to investigate whether body mass index (BMI) and serum collagenase-2 levels in pregnant women are related to the development of striae gravidarum.

METHODS

Thirty pregnant women with striae, 30 pregnant women without striae, and 32 health controls were enrolled in the study.

RESULTS

BMI and serum collagenase-2 levels were measured in the participants.

CONCLUSION

Pregnant women with striae gravidarum had increased serum collagenase-2 and BMI levels when compared to pregnant women without striae gravidarum and healthy controls (P < 0.05). The increase in serum collagenase-2 levels was related to the development of striae gravidarum alone, or secondary to BMI increase.

The Role of Matrix Metalloproteinase Polymorphisms in Ischemic Stroke

Stroke remains the fifth leading cause of mortality in the United States with an annual rate of over 128,000 deaths per year. Differences in incidence, pathogenesis, and clinical outcome have long been noted when comparing ischemic stroke among different ethnicities. The observation that racial disparities exist in clinical outcomes after stroke has resulted in genetic studies focusing on specific polymorphisms. Some studies have focused on matrix metalloproteinases (MMPs). MMPs are a ubiquitous group of proteins with extensive roles that include extracellular matrix remodeling and blood-brain barrier disruption. MMPs play an important role in ischemic stroke pathophysiology and clinical outcome. This review will evaluate the evidence for associations between polymorphisms in MMP-1, 2, 3, 9, and 12 with ischemic stroke incidence, pathophysiology, and clinical outcome. The role of polymorphisms in MMP genes may influence the presentation of ischemic stroke and be influenced by racial and ethnic background. However, contradictory evidence for the role of MMP polymorphisms does exist in the literature, and further studies will be necessary to consolidate our understanding of these multi-faceted proteins.

Anatomical Localization of Cartilage Degradation Markers in a Surgically Induced Rat Osteoarthritis Model

Osteoarthritis (OA) is a degenerative disease characterized by an irreversible loss of articular cartilage. Although surgically induced animal OA models are commonly used in drug efficacy assessment, degradation of type II collagen, an important component of articular cartilage is not routinely evaluated. Here, the medial meniscectomy surgical model (MMT) in Lewis rats was evaluated for proteoglycan loss with toluidine blue staining and collagen degradation with immunohistochemical staining for a collagen cleavage C-neoepitope, using a novel anti-type II collagen neoepitope antigen (TIINE) antibody. Femorotibial joints were collected for histology at 0 (no surgery), 3, 7, 14, 21, 28, 35, and 42 days postsurgery. Following MMT surgery, the medial tibial articular cartilage had proteoglycan matrix loss by day 3 that reached subchondral bone by days 28–42. Femoral cartilage damage occurred by day 14. TIINE staining was present at basal levels in growth plates and articular cartilage of all joints while all MMT-treated animals had increased intensity and area of staining in erosions that colocalized with proteoglycan loss. The MMT model produces a progressive pattern of cartilage damage resembling human OA lesions, making it useful, when evaluated with cartilage biomarkers, for assessing changes in cartilage degradation.

Leukocyte-Reduced Platelet-Rich Plasma Normalizes Matrix Metabolism in Torn Human Rotator Cuff Tendons

BACKGROUND

The optimal platelet-rich plasma (PRP) for treatment of supraspinatus tendinopathy has not been determined.

PURPOSE

To evaluate the effect of low- versus high-leukocyte concentrated PRP products on catabolic and anabolic mediators of matrix metabolism in diseased rotator cuff tendons.

STUDY DESIGN

Controlled laboratory study.

METHODS

Diseased supraspinatus tendons were treated with PRP made by use of 2 commercial systems: Arthrex Autologous Conditioned Plasma Double Syringe System (L(lo) PRP) and Biomet GPS III Mini Platelet Concentrate System (L(hi) PRP). Tendon explants were placed in 6-well plates and cultured in L(lo) PRP, L(hi) PRP, or control media (Dulbecco's Modified Eagle Medium + 10% fetal bovine serum) for 96 hours. Tendons were processed for hematoxylin-eosin histologic results and were scored with the modified Bonar scale. Group 1 tendons were defined as moderate tendinopathy (Bonar score <3); group 2 tendons were assessed as severely affected (Bonar score = 3). Transforming growth factor β-1 (TGFβ-1), interleukin-1β (IL-1β), interleukin-1 receptor antagonist (IL-1Ra), interleukin-6 (IL-6), interleukin-8 (IL-8), and matrix metalloproteinase-9 (MMP-9) concentrations in PRP media were measured by use of enzyme-linked immunosorbent assay after 96 hours of culture with diseased tendon. Tendon messenger RNA expression of collagen type I (COL1A1), collagen type III (COL3A1), cartilage oligomeric matrix protein (COMP), MMP-9, MMP-13, and IL-1β was measured with real-time quantitative polymerase chain reaction.

RESULTS

Leukocytes and platelets were significantly more concentrated in L(hi) PRP compared with L(lo) PRP. Increased IL-1β was present in L(hi) PRP after culture with group 1 tendons. IL-6 was increased in L(hi) PRP after culture with group 2 tendons. Both TGFβ-1 and MMP-9 were increased in L(hi) PRP after culture with either tendon group. In L(lo) PRP cultures, IL-1Ra:IL-1β in PRP used as media and COL1A1:COL3A1 gene expression were increased for group 1 tendon cultures. Gene expression of MMP-9 and IL-1β was increased in group 2 tendons cultured in L(lo) PRP. There was no significant difference in the expression of MMP-13 or COMP in either group of tendons cultured in L(lo) PRP or L(hi) PRP.

CONCLUSION

L(lo) PRP promotes normal collagen matrix synthesis and decreases cytokines associated with matrix degradation and inflammation to a greater extent than does L(hi) PRP in moderately degenerative tendons. In severely degenerative tendons, neither PRP preparation enhanced matrix synthesis.

CLINICAL RELEVANCE

L(lo) PRP may promote healing in moderately degenerative rotator cuff tendons.

A metaproteomics approach to elucidate host and pathogen protein expression during catheter-associated urinary tract infections (CAUTIs)

Long-term catheterization inevitably leads to a catheter-associated bacteriuria caused by multispecies bacterial biofilms growing on and in the catheters. The overall goal of the presented study was (1) to unravel bacterial community structure and function of such a uropathogenic biofilm and (2) to elucidate the interplay between bacterial virulence and the human immune system within the urine. To this end, a metaproteomics approach combined with in vitro proteomics analyses was employed to investigate both, the pro- and eukaryotic protein inventory. Our proteome analyses demonstrated that the biofilm of the investigated catheter is dominated by three bacterial species, that is, Pseudomonas aeruginosa, Morganella morganii, and Bacteroides sp., and identified iron limitation as one of the major challenges in the bladder environment. In vitro proteome analysis of P. aeruginosa and M. morganii isolated from the biofilm revealed that these opportunistic pathogens are able to overcome iron restriction via the production of siderophores and high expression of corresponding receptors. Notably, a comparison of in vivo and in vitro protein profiles of P. aeruginosa and M. morganii also indicated that the bacteria employ different strategies to adapt to the urinary tract. Although P. aeruginosa seems to express secreted and surface-exposed proteases to escape the human innate immune system and metabolizes amino acids, M. morganii is able to take up sugars and to degrade urea. Most interestingly, a comparison of urine protein profiles of three long-term catheterized patients and three healthy control persons demonstrated the elevated level of proteins associated with neutrophils, macrophages, and the complement system in the patient's urine, which might point to a specific activation of the innate immune system in response to biofilm-associated urinary tract infections. We thus hypothesize that the often asymptomatic nature of catheter-associated urinary tract infections might be based on a fine-tuned balance between the expression of bacterial virulence factors and the human immune system.

Mouse matrix metalloprotease-1a (Mmp1a) gives new insight into MMP function

Matrix metalloprotease-1 (MMP1) has been implicated in many human disease processes, however the lack of a well characterized murine homologue has significantly limited the study of MMP1 and the development of MMP-targeted therapeutics. The discovery of murine Mmp1a in 2001, the functional mouse homologue of MMP1, offers a valuable tool for modeling MMP1-mediated processes in mice. Variation in physiologic expression levels of Mmp1a in mice as compared to MMP1 in humans highlights the importance of understanding the similarities and differences between the homologues. Recent studies have demonstrated tumor growth-, invasion-, and angiogenesis-promoting functions of Mmp1a in lung cancer models, consistent with the analogous functions observed for human MMP1. Biochemical investigations have shown that point mutations in the pro-domain of mouse Mmp1a weaken docking between the pro- and catalytic domains, generating an unstable zymogen primed for activation. The difficulty to effectively maintain Mmp1a in the zymogen form may account for the tight control of Mmp1a expression and reduced expression in normal tissue as compared to inflammatory states or cancer. This discovery raises important questions about the activation mechanisms and regulation of the MMP family in general.

Matrix metalloproteinases in inflammation

BACKGROUND

Matrix metalloproteinases (MMPs) are a family of ubiquitously expressed zinc-dependent endopeptidases with broad substrate specificity and strictly regulated tissue specific expression. They are expressed in physiological situations and pathological conditions involving inflammation. MMPs regulate several functions related to inflammation including bioavailability and activity of inflammatory cytokines and chemokines. There is also evidence that MMPs regulate inflammation in tumor microenvironment, which plays an important role in cancer progression.

SCOPE OF REVIEW

Here, we discuss the current view on the role of MMPs in the regulation of inflammation.

MAJOR CONCLUSIONS

MMPs modulate inflammation by regulating bioavailability and activity of cytokines, chemokines, and growth factors, as well as integrity of physical tissue barriers. MMPs are also involved in immune evasion of tumor cells and in regulation of inflammation in tumor microenvironment.

GENERAL SIGNIFICANCE

There is increasing evidence for non-matrix substrates of MMPs that are related to regulation of inflammatory processes. New methods have been employed for identification of the substrates of MMPs in inflammatory processes in vivo. Detailed information on the substrates of MMPs may offer more specific and effective ways of inhibiting MMP function by blocking the cleavage site in substrate or by inhibition of the bioactivity of the substrate. It is expected, that more precise information on the MMP-substrate interaction may offer novel strategies for therapeutic intervention in inflammatory diseases and cancer without blocking beneficial actions of MMPs. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Exhaustive exercise with different rest periods changes the collagen content and MMP-2 activation on the calcaneal tendon

Tendons adapt to different mechanical stimuli through a remodeling process involving metalloproteinases (MMPs) and collagen synthesis. The purpose of this study was to investigate the activities of MMP-2 and MMP-9 and the collagen content in tendons after exhaustive acute exercise sessions over the course of 1, 3, or 6 days, with 1-hr or 3-hr rest periods between each session. Wistar rats were grouped into control (C), trained with 1-hr (groups 1d1h, 3d1h, and 6d1h) and trained with 3-hr (groups 1d3h, 3d3h and 6d3h) groups with rest periods between the treadmill running sessions, for 1, 3, and 6 days. The analysis of MMP-2 showed a larger presence of the latent isoform in the 1d3h group and a larger presence of the active isoform in the 6d3h group compared to the control. No differences were detected for MMP-9. A lower concentration of hydroxyproline was found in the 6d3h group compared to the 6d1h group. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed more prominent collagen bands in the 6d3h group, which was confirmed by Western blotting for collagen type I. A higher concentration of glycosaminoglycans was observed in the 3d3h group compared to the 3d1h group, and the 6d3h group presented the highest value for non-collagenous proteins compared to other groups. In conclusion, different rest periods between exercise sessions had different effects on the composition of the calcaneal tendon because a greater activation of MMP-2 and a reduction of total collagen were observed on day 6 of exercise with 3-hr rest periods compared to 1-hr rest periods.

CIINE Reflects Collagenase-Specific CII Breakdown in Cartilage Explant and Whole Body of Canine

To evaluate collagenase inhibitors for the treatment of osteoarthritis and to correlate them with clinical pathology, canine cartilage explant and anterior cruciate ligament transection (ACLT) models were examined by quantifying the CII neoepitope (CIINE). This peptide is a putative marker for collagenase-specific type II collagen (CII) degradation, which is a critical step in osteoarthritis pathology.

The concentration of CIINE in supernatants of canine cartilage explants showed increase upon IL-1β—stimulation and collagenase inhibitors suppressed this elevation of CIINE. In the canine ACLT model, levels of CIINE in urine (uCIINE) increased as lesions of knee joint cartilage developed and decreased in response to collagenase inhibitors.

Our results suggest that CIINE reflects collagenase-specific CII degradation in canine explants and whole bodies. It is anticipated that these data will establish a tool for clarifying and bridging the efficacy and mechanism of collagenase inhibitors at the preclinical stage of drug discovery.

Matrix metalloproteinase 8 (collagenase 2) induces the expression of interleukins 6 and 8 in breast cancer cells

Matrix metalloproteinase 8 (MMP-8) is a tumor-suppressive protease that cleaves numerous substrates, including matrix proteins and chemokines. In particular, MMP-8 proteolytically activates IL-8 and, thereby, regulates neutrophil chemotaxis in vivo. We explored the effects of expression of either a WT or catalytically inactive (E198A) mutant version of MMP-8 in human breast cancer cell lines. Analysis of serum-free conditioned media from three breast cancer cell lines (MCF-7, SK-BR-3, and MDA-MB-231) expressing WT MMP-8 revealed elevated levels of IL-6 and IL-8. This increase was mirrored at the mRNA level and was dependent on MMP-8 catalytic activity. However, sustained expression of WT MMP-8 by breast cancer cells was non-permissive for long-term growth, as shown by reduced colony formation compared with cells expressing either control vector or E198A mutant MMP-8. In long-term culture of transfected MDA-MB-231 cells, expression of WT but not E198A mutant MMP-8 was lost, with IL-6 and IL-8 levels returning to base line. Rare clonal isolates of MDA-MB-231 cells expressing WT MMP-8 were generated, and these showed constitutively high levels of IL-6 and IL-8, although production of the interleukins was no longer dependent upon MMP-8 activity. These studies support a causal connection between MMP-8 activity and the IL-6/IL-8 network, with an acute response to MMP-8 involving induction of the proinflammatory mediators, which may in part serve to compensate for the deleterious effects of MMP-8 on breast cancer cell growth. This axis may be relevant to the recognized ability of MMP-8 to orchestrate the innate immune system in inflammation in vivo.

Matrix metalloproteinase (MMP)-9: a proximal biomarker for cardiac remodeling and a distal biomarker for inflammation

Adverse cardiac remodeling following myocardial infarction (MI) remains a significant cause of congestive heart failure. Additional and novel strategies that improve our ability to predict, diagnose, or treat remodeling are needed. Numerous groups have explored single and multiple biomarker strategies to identify diagnostic prognosticators of remodeling progression, which will improve our ability to promptly and accurately identify high-risk individuals. The identification of better clinical indicators should further lead to more effective prediction and timely treatment. Matrix metalloproteinase (MMP-9) is one potential biomarker for cardiac remodeling, as demonstrated by both animal models and clinical studies. In animal MI models, MMP-9 expression significantly increases and is linked with inflammation, diabetic microvascular complications, extracellular matrix degradation and synthesis, and cardiac dysfunction. Clinical studies have also established a relationship between MMP-9 and post-MI remodeling and mortality, making MMP-9 a viable candidate to add to the multiple biomarker list. By definition, a proximal biomarker shows a close relationship with its target disease, whereas a distal biomarker exhibits non-targeted disease modifying outcomes. In this review, we explore the ability of MMP-9 to serve as a proximal biomarker for cardiac remodeling and a distal biomarker for inflammation. We summarize the current molecular basis and clinical platform that allow us to include MMP-9 as a biomarker in both categories.

Role of matrix metalloproteinase-8 in atherosclerosis

Plaque rupture is the main cause of acute myocardial infarction and stroke. Atherosclerotic plaques have been described to be vulnerable and more prone to rupture when they are characterized by thin, highly inflamed, and collagen-poor fibrous caps and contain elevated levels of proteases, including metalloproteinases (MMPs). Initiation of collagen breakdown in plaques requires interstitial collagenases, a MMP subfamily consisting of MMP-1, MMP-8, and MMP-13. Previous reports demonstrated that MMP-1 and MMP-13 might be overexpressed in both human and experimental atherosclerosis. Since neutrophils have been only recently reported in atherosclerotic plaques, the role of MMP-8 (formerly known as "neutrophil collagenase") was only marginally evaluated. In this paper, we will update and comment on evidence of the most relevant regulatory pathways and activities mediated by MMP-8 in atherogenesis.

Mechanical properties of the extracellular matrix of the aorta studied by enzymatic treatments

The microarchitecture of different components of the extracellular matrix (ECM) is crucial to our understanding of the properties of a tissue. In the study presented here, we used a top-down approach to understand how the interplay among different fibers determines the mechanical properties of real tissues. By selectively removing different elements of the arterial wall, we were able to measure the contribution of the different constituents of the ECM to the mechanical properties of the whole tissue. Changes in the network structure were imaged with the use of two-photon microscopy. We used an atomic force microscope to measure changes in the mechanical properties by performing nanoindentation experiments. We show that although the removal of a key element of the ECM reduced the local stiffness by up to 50 times, the remaining tissue still formed a coherent network. We also show how this method can be extended to study the effects of cells on real tissues. This new (to our knowledge) way of studying the ECM will not only help physicists gain a better understanding of biopolymers, it will be a valuable tool for biomedical researchers studying processes such as wound healing and cervix ripening.

The history of matrix metalloproteinases: milestones, myths, and misperceptions

Since the discovery of tadpole collagenase in 1962, the matrix metalloproteinase (MMP) family has emerged as a significant proteinase group with recognized effects on the cardiovascular system. Over the last 40 years, many milestones have been achieved, from the identification of the first MMP, to the generation of the first MMP cDNA clone and null mouse, to the clinical approval of the first MMP inhibitor. Over the years, a few myths and misunderstandings have interwoven into the truths. In this review, we will discuss the major milestones of MMP research, as well as review the misinterpretations and misperceptions that have evolved. Clarifying the confusions and dispelling the myths will both provide a better understanding of MMP properties and functions and focus the cardiovascular field on the outstanding research questions that need to be addressed.

Emerging roles of endothelial cells in multiple sclerosis pathophysiology and therapy

Although multiple sclerosis (MS) has traditionally been viewed and researched as an immune-mediated demyelinating and neurodegenerative disease of the human central nervous system (CNS), its highly complex pathogenesis clearly includes a significant vascular inflammatory component and many therapeutic approaches achieve benefit by direct or indirect effects on cerebrovascular endothelial cells. Cerebral endothelial cells create and separate the compartments of the peripheral circulation and CNS creating the blood-brain barrier (BBB), a selectively permeable boundary layer between these spaces. Interactions between activated leukocytes and cerebral endothelium play essential roles in mediating their trans-BBB diapedesis during normal immune surveillance and during pathogenesis of neuroinflammatory diseases like MS. Extravasation of activated and committed leukocytes from the peripheral circulation through the endothelial layer of the BBB into the CNS milieu is the most fundamental step in formation of MS lesions. During MS pathogenesis, once the activated leukocytes enter the CNS environment, they propagate a massive wave of destruction which culminates in the loss of both myelin/oligodendrocyte complex and neurodegeneration. Multiple clinical and basic scientific observations support endothelial cell 'stress' and apoptosis as a hallmark characteristic of MS. The manipulation of the endothelial biology aiming to block trans-endothelial migration of activated immune cells into the CNS is a potent form of treatment for MS achieving significant reductions in disease activity and new lesion formation. In particular, endothelial microparticles are now well-recognized as important biomarkers and mediators of this type of stress. In this review, we discuss recent findings and new advances in our knowledge regarding leukocyte migration through the endothelial frontier of the BBB and how this can be exploited toward treating MS patients.

Moderate joint loading reduces degenerative actions of matrix metalloproteinases in the articular cartilage of mouse ulnae

Joint loading is a recently developed loading modality, which can enhance bone formation and accelerate healing of bone fracture. Since mechanical stimulation alters expression of matrix metalloproteinases (MMPs) in chondrocytes, a question addressed herein was, does joint loading alter actions of MMPs in the articular cartilage? We hypothesized that expression and activity of MMPs are regulated in a load-intensity-dependent manner and that moderate load scan downregulates MMPs. To test this hypothesis, a mouse elbow-loading model was employed. In the articular cartilage of an ulna, the mRNA levels of a group of MMPs as well as their degenerative activities were determined. The result revealed that elbow loading altered the expression and activities of MMPs depending on its loading intensity. Collectively, the data in this study indicate that 0.2 and 0.5 N joint loading significantly reduced the expression of multiple MMPs, that is, MMP-1, MMP-3, MMP-8, and MMP-13, and overall activities of collagenases or gelatinases in articular cartilage, while higher loads increased the expression and activity of MMP-1 and MMP-13. Furthermore, moderate loads at 1 N elevated the mRNA level of CBP/p300-interacting transactivator with ED-rich tail 2 (CITED2), but higher loads at 4 N did not induce a detectable amount of CITED2 mRNA. Since CITED2 is known to mediate the downregulation of MMP-1 and MMP-13, the result indicates that joint loading at moderate intensity reduces MMP activities through potential induction of CITED2. MMPs such as MMP-1 and MMP-13 are predominant collagenases in the pathology of osteoarthritis. Therefore, joint loading could offer an interventional regimen for maintenance of joint tissues.

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

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

Physiology and pathophysiology of matrix metalloproteases

Matrix metalloproteases (MMPs) comprise a family of enzymes that cleave protein substrates based on a conserved mechanism involving activation of an active site-bound water molecule by a Zn(2+) ion. Although the catalytic domain of MMPs is structurally highly similar, there are many differences with respect to substrate specificity, cellular and tissue localization, membrane binding and regulation that make this a very versatile family of enzymes with a multitude of physiological functions, many of which are still not fully understood. Essentially, all members of the MMP family have been linked to disease development, notably to cancer metastasis, chronic inflammation and the ensuing tissue damage as well as to neurological disorders. This has stimulated a flurry of studies into MMP inhibitors as therapeutic agents, as well as into measuring MMP levels as diagnostic or prognostic markers. As with most protein families, deciphering the function(s) of MMPs is difficult, as they can modify many proteins. Which of these reactions are physiologically or pathophysiologically relevant is often not clear, although studies on knockout animals, human genetic and epigenetic, as well as biochemical studies using natural or synthetic inhibitors have provided insight to a great extent. In this review, we will give an overview of 23 members of the human MMP family and describe functions, linkages to disease and structural and mechanistic features. MMPs can be grouped into soluble (including matrilysins) and membrane-anchored species. We adhere to the 'MMP nomenclature' and provide the reader with reference to the many, often diverse, names for this enzyme family in the introduction.

Myricetin inhibits IL-1beta-induced inflammatory mediators in SW982 human synovial sarcoma cells

Rheumatoid arthritis (RA) synovial fibroblasts produce inflammatory mediators, which destruct cartilage and bone in RA joint. The aim of this study is to investigate the effect of myricetin on inflammatory cytokine/matrix metalloproteinase (MMP) production and mitogen-activated protein kinases (MAPKs) in IL-1beta-stimulated SW982 synovial cells. Myricetin significantly decreased IL-1beta-induced production of IL-6 and MMP-1 in synovial cells. Moreover, myricetin diminished the phosphorylation of Jun NH2-terminal kinase (JNK) and p38 MAPK. These results suggest that myricetin reduces the production of MMP and IL-6 in SW982 cells by inhibiting MAPKs (JNK and p38).