Gelatin degradation assay reveals MMP-9 inhibitors and function of O-glycosylated domain

Tuneable gelatin methacryloyl (GelMA) hydrogels for the directed specification of renal cell types for hiPSC-derived kidney organoid maturation

Diabetic Kidney Disease (DKD) represents a significant global health burden and is recognised as the leading cause of end-stage renal disease. Kidney organoids derived from human induced Pluripotent Stem Cells (hiPSCs) have the potential to transform how we model renal disease and may provide personalised replacement tissues for patients with renal failure. However, kidney organoids remain poorly reproducible, and are structurally and functionally immature. Three-dimensional cultures that more appropriately mimic the complexity of the in vivo microenvironment are required to improve organoid maturation and structural authenticity. Here, we describe the application of semi-synthetic Gelatin Methacryloyl (GelMA) hydrogels as extracellular support matrices for the differentiation of hiPSC-derived kidney organoids. Hydrogels of defined mechanical strengths were generated by varying the concentration of GelMA solution in the presence of low concentration photo-initiator. After confirming a high level of mechanical stability of the hydrogels over extended culture periods, their effect on kidney organoid maturation was investigated. Organoids differentiated within GelMA hydrogels generated typical renal cell types including podocytes, tubular epithelia, renal interstitial cells, and some nascent vascularisation. Interestingly, kidney organoids derived within hydrogels that closely approximate the stiffness of the adult human kidney (∼5000-10,000 Pa) demonstrated improved podocyte maturation and were shown to upregulate renal vesicle-associated genes at an earlier stage following encapsulation when compared to organoids derived within softer hydrogels (∼400 Pa). A model of TGFβ-induced injury was also developed to investigate the influence of the mechanical environment in propagating early, fibrotic-like features of DKD within organoids. Growth within the softer matrix was shown to reduce pSMAD3 expression following TGFβ1 treatment, and accordingly ameliorate the expression of the myofibroblast marker α-Smooth Muscle Actin (α-SMA). This work demonstrates the suitability of GelMA hydrogels as mechanically-stable, highly-tuneable, batch-to-batch reproducible three-dimensional supports for hiPSC-derived kidney organoid growth and differentiation, and further substantiates the role of the biophysical environment in guiding processes of cell fate determination and organoid maturation.

DCLK1-mediated regulation of invadopodia dynamics and matrix metalloproteinase trafficking drives invasive progression in head and neck squamous cell carcinoma

BACKGROUND

HNSCC presents a significant health challenge due to its high mortality resulting from treatment resistance and locoregional invasion into critical structures in the head and neck region. Understanding the invasion mechanisms of HNSCC has the potential to guide targeted therapies, improving patient survival. Previously, we demonstrated the involvement of doublecortin like kinase 1 (DCLK1) in regulating HNSCC cell invasion. Here, we investigated the hypothesis that DCLK1 modulates proteins within invadopodia, specialized subcellular protrusions that secrete matrix metalloproteinases to degrade the ECM.

METHODS

We employed tandem mass tag (TMT)-based proteomics to identify the role of DCLK1 in regulating proteins involved in HNSCC invasion and validated the findings using immunoblotting. The Cancer Genome Atlas (TCGA) database was interrogated to correlate DCLK1 expression with tumor stage, grade, and invasion-associated proteins. In vitro invasion was assessed using a Boyden chamber assay, and immunohistochemistry on patient samples determined DCLK1's distribution within tumors. Gelatin invadopodia assay was used to establish DCLK1 localization to invadopodia related gelatin degradation. Super-resolution confocal microscopy demonstrated colocalization of DCLK1 with invadopodia markers and MMP trafficking proteins. ECM degradation by MMPs in HNSCC cells with wild-type and knockdown DCLK1 was evaluated using a dye-quenched tracer, while gel zymography and MMP array identified secreted proteases. Proximity ligation assay (PLA) and co-immunoprecipitation assays were used to confirm interactions between DCLK1, MMP9, KIF16B, and RAB40B.

RESULTS

Proteomic analysis demonstrate DCLK1's role in regulating proteins involved in cytoskeletal and ECM remodeling. Clinically, rising DCLK1 levels correlate with higher histological grade and lymph node metastasis, with heightened expression observed at the leading edge of HNSCC patient tissue. DCLK1 is localized with markers of mature invadopodia including TKS4, TKS5, cortactin, and MT1-MMP. Knockdown of DCLK1 led to reductions in invadopodia numbers and decreased in vitro invasion and ECM degradation. MMP9 colocalizes with DCLK1 within invadopodia structures and its secretion is disrupted by DCLK1 knockdown. Further, PLA and co-immunoprecipitations studies demonstrate DLCK1 complexes with KIF16B and RAB40B enabling trafficking of degradative MMP9 cargo along the invadopodia to degrade local ECM.

CONCLUSION

This work unveils a novel function of DCLK1 in regulating KIF16B and RAB40B to traffic matrix degrading MMP9 cargo to the distal end of the invadopodia facilitating HNSCC invasion.

Gelatinolytic activity in dentin upon adhesive treatment

In this multi-parameter study, the effect of diverse factors related to adhesive application on the activation of host-derived gelatinases was investigated by gelatin zymography, in-situ zymography, fluorogenic DQ-gelatin assay and micro-tensile bond-strength (μTBS) testing. Gelatin zymography disclosed the presence of gelatinases in phosphoric acid-etched dentin powder, while two gold-standard adhesives generated no measurable MMP activation. In-situ zymography revealed that the interfacial gelatinolytic activity from specimens treated with the two adhesives appeared similar as that of the EDTA negative control, indicating no detectable gelatinases were activated upon adhesive treatment. In solution, MMP-2/9 activity significantly decreased upon interaction with both adhesives (two-way linear mixed effects model [LMEM]: p < 0.05); gelatinases were almost completely deactivated upon 1-week incubation at 37 °C (general linear model: p < 0.05); light-curing adhesives increased temperature up to 55 °C, which appeared sufficient to dramatically decrease MMP-2/9 activity (two-way ANOVA: p < 0.05). Finally, challenging adhesive-dentin interfaces with highly concentrated MMP-9 (at a much higher concentration than present in saliva) for 1 m did not significantly affect μTBS (two-way LMEM: p > 0.05). Taken together, the two adhesives did not activate but rather inhibited the release and activation of dentinal gelatinases.

Protection of stromal cell-derived factor-1 SDF-1/CXCL12 against proteases yields improved skin wound healing

SDF-1/CXCL12 is a unique chemotactic factor with multiple functions on various types of precursor cells, all carrying the cognate receptor CXCR4. Whereas individual biological functions of SDF-1/CXCL12 have been well documented, practical applications in medicine are insufficiently studied. This is explained by the complex multifunctional biology of SDF-1 with systemic and local effects, critical dependence of SDF-1 activity on aminoterminal proteolytic processing and limited knowledge of applicable modulators of its activity. We here present new insights into modulation of SDF-1 activity in vitro and in vivo by a macromolecular compound, chlorite-oxidized oxyamylose (COAM). COAM prevented the proteolytic inactivation of SDF-1 by two inflammation-associated proteases: matrix metalloproteinase-9/MMP-9 and dipeptidylpeptidase IV/DPPIV/CD26. The inhibition of proteolytic inactivation was functionally measured by receptor-mediated effects, including intracellular calcium mobilization, ERK1/2 phosphorylation, receptor internalization and chemotaxis of CXCR4-positive cells. Protection of SDF-1/CXCL12 against proteolysis was dependent on electrostatic COAM-SDF-1 interactions. By in vivo experiments in mice, we showed that the combination of COAM with SDF-1 delivered through physiological fibrin hydrogel had beneficial effect for the healing of skin wounds. Collectively, we show that COAM protects SDF-1 from proteolytic inactivation, maintaining SDF-1 biological activities. Thus, protection from proteolysis by COAM represents a therapeutic strategy to prolong SDF-1 bioavailability for wound healing applications.

Validation of a rapid collagenase activity detection technique based on fluorescent quenched gelatin with synovial fluid samples

BACKGROUND

Measuring collagenase activity is crucial in the field of joint health and disease management. Collagenases, enzymes responsible for collagen degradation, play a vital role in maintaining the balance between collagen synthesis and breakdown in joints. Dysregulation of collagenase activity leads to joint tissue degradation and diseases such as rheumatoid arthritis and osteoarthritis. The development of methods to measure collagenase activity is essential for diagnosis, disease severity assessment, treatment monitoring, and identification of therapeutic targets.

RESULTS

This study aimed to validate a rapid collagenase activity detection technique using synovial fluid samples. Antibody microarray analysis was initially performed to quantify the levels of matrix metalloproteinase-9 (MMP-9), a major collagenase in joints. Subsequently, the developed gelatin-based test utilizing fluorescence measurement was used to determine collagenase activity. There was a significant correlation between the presence of MMP-9 and collagenase activity. In addition, Lower Limit of Detection and Upper Limit of Detection can be preliminary estimated as 8 ng/mL and 48 ng/mL respectively.

CONCLUSIONS

The developed technique offers a potential point-of-care assessment of collagenase activity, providing real-time information for clinicians and researchers. By accurately quantifying collagenase activity, healthcare professionals can optimize patient care, improve treatment outcomes, and contribute to the understanding and management of joint-related disorders. Further research and validation are necessary to establish the full potential of this rapid collagenase activity detection method in clinical practice.

Deflamin Attenuated Lung Tissue Damage in an Ozone-Induced COPD Murine Model by Regulating MMP-9 Catalytic Activity

Chronic obstructive pulmonary disease (COPD) is comprised of histopathological alterations such as pulmonary emphysema and peribronchial fibrosis. Matrix metalloproteinase 9 (MMP-9) is one of the key enzymes involved in both types of tissue remodeling during the development of lung damage. In recent studies, it was demonstrated that deflamin, a protein component extracted from Lupinus albus, markedly inhibits the catalytic activity of MMP-9 in experimental models of colon adenocarcinoma and ulcerative colitis. Therefore, in the present study, we investigated for the first time the biological effect of deflamin in a murine COPD model induced by chronic exposure to ozone. Ozone exposure was carried out in C57BL/6 mice twice a week for six weeks for 3 h each time, and the treated group was orally administered deflamin (20 mg/kg body weight) after each ozone exposure. The histological results showed that deflamin attenuated pulmonary emphysema and peribronchial fibrosis, as evidenced by H&E and Masson's trichrome staining. Furthermore, deflamin administration significantly decreased MMP-9 activity, as assessed by fluorogenic substrate assay and gelatin zymography. Interestingly, bioinformatic analysis reveals a plausible interaction between deflamin and MMP-9. Collectively, our findings demonstrate the therapeutic potential of deflamin in a COPD murine model, and suggest that the attenuation of the development of lung tissue damage occurs by deflamin-regulated MMP-9 catalytic activity.

Guiding bone cell network formation in 3D via photosensitized two-photon ablation

A long-standing challenge in skeletal tissue engineering is to reconstruct a three-dimensionally (3D) interconnected bone cell network in vitro that mimics the native bone microarchitecture. While conventional hydrogels are extensively used in studying bone cell behavior in vitro, current techniques lack the precision to manipulate the complex pericellular environment found in bone. The goal of this study is to guide single bone cells to form a 3D network in vitro via photosensitized two-photon ablation of microchannels in gelatin methacryloyl (GelMA) hydrogels. A water-soluble two-photon photosensitizer (P2CK) was added to soft GelMA hydrogels to enhance the ablation efficiency. Remarkably, adding 0.5 mM P2CK reduced the energy dosage threshold five-fold compared to untreated controls, enabling more cell-compatible ablation. By employing low-energy ablation (100 J/cm2) with a grid pattern of 1 µm wide and 30 µm deep microchannels, we induced dendritic outgrowth in human mesenchymal stem cells (hMSC). After 7 days, the cells successfully utilized the microchannels and formed a 3D network. Our findings reveal that cellular viability after low-energy ablation was comparable to unablated controls, whereas high-energy ablation (500 J/cm2) resulted in 42 % cell death. Low-energy grid ablation significantly promoted network formation and >40 µm long protrusion outgrowth. While the broad-spectrum matrix metalloproteinase inhibitor (GM6001) reduced cell spreading by inhibiting matrix degradation, cells invaded the microchannel grid with long protrusions. Collectively, these results emphasize the potential of photosensitized two-photon hydrogel ablation as a high-precision tool for laser-guided biofabrication of 3D cellular networks in vitro. STATEMENT OF SIGNIFICANCE: The inaccessible nature of osteocyte networks in bones renders fundamental research on skeletal biology a major challenge. This limit is partly due to the lack of high-resolution tools that can manipulate the pericellular environment in 3D cultures in vitro. To create bone-like cellular networks, we employ a two-photon laser in combination with a two-photon sensitizer to erode microchannels with low laser dosages into GelMA hydrogels. By providing a grid of microchannels, the cells self-organized into a 3D interconnected network within days. Laser-guided formation of 3D networks from single cells at micron-scale resolution is demonstrated for the first time. In future, we envisage in vitro generation of bone cell networks with user-dictated morphologies for both fundamental and translational bone research.

Biological Activities of Citrus aurantium Leaf Extract by Optimized Ultrasound-Assisted Extraction

Several studies have explored the biological activities of Citrus aurantium flowers, fruits, and seeds, but the bioactivity of C. aurantium leaves, which are treated as waste, remains unclear. Thus, this study developed a pilot-scale ultrasonic-assisted extraction process using the Box-Behnken design (BBD) for the optimized extraction of active compounds from C. aurantium leaves, and their antityrosinase, antioxidant, antiaging, and antimicrobial activities were evaluated. Under optimal conditions in a 150× scaleup configuration (a 30 L ultrasonic machine) of a pilot plant, the total phenolic content was 69.09 mg gallic acid equivalent/g dry weight, which was slightly lower (3.17%) than the theoretical value. The half maximal inhibitory concentration of C. aurantium leaf extract (CALE) for 2,2-diphenyl-1-picrylhydrazyl-scavenging, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)-scavenging, antityrosinase, anticollagenase, antielastase and anti-matrix metalloprotein-1 activities were 123.5, 58.5, 181.3, 196.4, 216.3, and 326.4 mg/L, respectively. Moreover, the minimal inhibitory concentrations for bacteria and fungi were 150-350 and 500 mg/L, respectively. In total, 17 active compounds were detected in CALE-with linalool, linalyl acetate, limonene, and α-terpineol having the highest concentrations. Finally, the overall transdermal absorption and permeation efficiency of CALE was 95.9%. In conclusion, our CALE demonstrated potential whitening, antioxidant, antiaging, and antimicrobial activities; it was also nontoxic and easily absorbed into the skin as well as inexpensive to produce. Therefore, it has potential applications in various industries.

Chlorotoxin binds to both matrix metalloproteinase 2 and neuropilin 1

Chlorotoxin (CTX), a scorpion venom-derived 36-residue miniprotein, binds to and is taken up selectively by glioblastoma cells. Previous studies provided controversial results concerning target protein(s) of CTX. These included CLC3 chloride channel, matrix metalloproteinase 2 (MMP-2), regulators of MMP-2, annexin A2, and neuropilin 1 (NRP1). The present study aimed at clarifying which of the proposed binding partners can really interact with CTX using biochemical methods and recombinant proteins. For this purpose, we established two new binding assays based on anchoring the tested proteins to microbeads and quantifying the binding of CTX by flow cytometry. Screening of His-tagged proteins anchored to cobalt-coated beads indicated strong interaction of CTX with MMP-2 and NRP1, whereas binding to annexin A2 was not confirmed. Similar results were obtained with fluorophore-labeled CTX and CTX-displaying phages. Affinity of CTX to MMP-2 and NRP1 was assessed by the "immunoglobulin-coated bead" test, in which the proteins were anchored to beads by specific antibodies. This assay yielded highly reproducible data using both direct titration and displacement approach. The affinities of labeled and unlabeled CTX appeared to be similar for both MMP-2 and NRP1 with estimated KD values of 0.5 to 0.7 μM. Contrary to previous reports, we found that CTX does not inhibit the activity of MMP-2 and that CTX not only with free carboxyl end but also with carboxamide terminal end binds to NRP1. We conclude that the presented robust assays could also be applied for affinity-improving studies of CTX to its genuine targets using phage display libraries.

Application of an Extracellular Matrix-Mimicking Fluorescent Polymer for the Detection of Proteolytic Venom Toxins

The cytotoxicity caused by snake venoms is a serious medical problem that greatly contributes to the morbidity observed in snakebite patients. The cytotoxic components found in snake venoms belong to a variety of toxin classes and may cause cytotoxic effects by targeting a range of molecular structures, including cellular membranes, the extracellular matrix (ECM) and the cytoskeleton. Here, we present a high-throughput assay (384-well plate) that monitors ECM degradation by snake venom toxins via the application of fluorescent versions of model ECM substrates, specifically gelatin and collagen type I. Both crude venoms and fractionated toxins of a selection of medically relevant viperid and elapid species, separated via size-exclusion chromatography, were studied using the self-quenching, fluorescently labelled ECM-polymer substrates. The viperid venoms showed significantly higher proteolytic degradation when compared to elapid venoms, although the venoms with higher snake venom metalloproteinase content did not necessarily exhibit stronger substrate degradation than those with a lower one. Gelatin was generally more readily cleaved than collagen type I. In the viperid venoms, which were subjected to fractionation by SEC, two (B. jararaca and C. rhodostoma, respectively) or three (E. ocellatus) active proteases were identified. Therefore, the assay allows the study of proteolytic activity towards the ECM in vitro for crude and fractionated venoms.

Characterization of the MMP9 Gene and Its Association with Cryptocaryon irritans Resistance Traits in Trachinotus ovatus (Linnaeus, 1758)

The MMPs are endogenous proteolytic enzymes that require zinc and calcium as cofactors. MMP9 is one of the most complex matrix metalloproteinases in the gelatinase family and has many biological functions. In mammals, mmp9 is thought to be closely associated with cancer. However, studies in fish have rarely been reported. In this study, to understand the expression pattern of the ToMMP9 gene and its association with the resistance of Trachinotus ovatus to Cryptocaryon irritans, the sequence of the MMP9 gene was obtained from the genome database. The expression profiles were measured by qRT-PCR, the SNPs were screened by direct sequencing, and genotyping was performed. The ToMMP9 gene contained a 2058 bp ORF encoding a putative amino acid sequence of 685 residues. The homology of the ToMMP9 in teleosts was more than 85%, and the genome structure of ToMMP9 was conserved in chordates. The ToMMP9 gene was expressed in different tissues of healthy individuals and was highly expressed in the fin, the gill, the liver and the skin tissues. The ToMMP9 expression in the skin of the infected site and its adjacent sites increased significantly after C. irritans infection. Two SNPs were identified in the ToMMP9 gene, and the SNP (+400A/G) located in the first intron was found to be significantly associated with the susceptibility/resistance to C. irritans. These findings suggest that ToMMP9 may play an important role in the immune response of T. ovatus against C. irritans.

Immunomodulatory Microgels Support Proregenerative Macrophage Activation and Attenuate Fibroblast Collagen Synthesis

Scars composed of fibrous connective tissues are natural consequences of injury upon incisional wound healing in soft tissues.  Hydrogels that feature a sustained presentation of immunomodulatory cytokines are known to modulate wound healing. However, existing immunomodulatory hydrogels lack interconnected micropores to promote cell ingrowth. Other limitations include invasive delivery procedures and harsh synthesis conditions that are incompatible with drug molecules. Here, hybrid nanocomposite microgels containing interleukin-10 (IL-10) are reported to modulate tissue macrophage phenotype during wound healing. The intercalation of laponite nanoparticles in the polymer network yields microgels with tissue-mimetic elasticity (Young's modulus in the range of 2-6 kPa) and allows the sustained release of IL-10 to promote the differentiation of macrophages toward proregenerative phenotypes. The porous interstitial spaces between microgels promote fibroblast proliferation and fast trafficking (an average speed of ≈14.4 µm h^-1 ). The incorporation of hyaluronic acid further enhances macrophage infiltration. The coculture of macrophages and fibroblasts treated with transforming growth factor-beta 1 resulted in a twofold reduction in collagen-I production for microgels releasing IL-10 compared to the IL-10 free group. The new microgels show potential toward regenerative healing by harnessing the antifibrotic behavior of host macrophages.

Endothelial LRP1 protects against neurodegeneration by blocking cyclophilin A

The low-density lipoprotein receptor–related protein 1 (LRP1) is an endocytic and cell signaling transmembrane protein. Endothelial LRP1 clears proteinaceous toxins at the blood–brain barrier (BBB), regulates angiogenesis, and is increasingly reduced in Alzheimer’s disease associated with BBB breakdown and neurodegeneration. Whether loss of endothelial LRP1 plays a direct causative role in BBB breakdown and neurodegenerative changes remains elusive. Here, we show that LRP1 inactivation from the mouse endothelium results in progressive BBB breakdown, followed by neuron loss and cognitive deficits, which is reversible by endothelial-specific LRP1 gene therapy. LRP1 endothelial knockout led to a self-autonomous activation of the cyclophilin A–matrix metalloproteinase-9 pathway in the endothelium, causing loss of tight junctions underlying structural BBB impairment. Cyclophilin A inhibition in mice with endothelial-specific LRP1 knockout restored BBB integrity and reversed and prevented neuronal loss and behavioral deficits. Thus, endothelial LRP1 protects against neurodegeneration by inhibiting cyclophilin A, which has implications for the pathophysiology and treatment of neurodegeneration linked to vascular dysfunction.

Hydrogen sulfide attenuates hyperhomocysteinemia-induced blood-brain barrier permeability by inhibiting MMP-9

Backgroud: Hyperhomocysteinemia (HHcy) is implicated in various neurovascular disorders including vascular dementia, subarachnoid hemorrhage and stroke. Elevated homocysteine (Hcy) levels are associated with increased oxidative stress and compromised blood-brain barrier (BBB) integrity. Hydrogen sulfide (H₂S) has recently emerged as potent neuroprotective molecule in various neurological conditions including those associated with HHcy. The present study evaluates the protective effect of sodium hydrogen sulfide (NaHS; a source of H₂S) on HHcy-induced BBB dysfunction and underpin molecular mechanisms.Materials and methods: Supplementation of NaHS restored the increased BBB permeability in the cortex and hippocampus of HHcy animals assessed in terms of diffused sodium fluorescein and Evans blue tracer dyes in the brain. Activity of matrix metalloproteinases (MMPs) assessed by gelatinase activity and in situ gelatinase assay was restored to the normal in the cortex and hippocampus of HHcy animals supplemented with NaHS.Results: Application of gelatin zymography revealed that specifically MMP-9 activity was increased in the cortex and hippocampus of HHcy animals, which was inhibited by NaHS supplementation. Real-time RT-PCR analysis showed that NaHS administration also decreased mRNA expression of MMP-9 in the hippocampus of HHcy animals. NaHS supplementation was further observed to reduce water retention in the brain regions of Hcy treated animals.Conclusion: Taken together, these findings suggest that NaHS supplementation ameliorates HHcy-induced BBB permeability and brain edema by inhibiting the mRNA expression and activity of MMP-9. Therefore, H₂S and H₂S releasing drugs may be used as a novel therapeutic approach to treat HHcy-associated neurovascular disorders.

Natural Marine and Terrestrial Compounds as Modulators of Matrix Metalloproteinases-2 (MMP-2) and MMP-9 in Alzheimer's Disease

Several studies have reported neuroprotective effects by natural products. A wide range of natural compounds have been investigated, and some of these may play a beneficial role in Alzheimer's disease (AD) progression. Matrix metalloproteinases (MMPs), a family of zinc-dependent endopeptidases, have been implicated in AD. In particular, MMP-2 and MMP-9 are able to trigger several neuroinflammatory and neurodegenerative pathways. In this review, we summarize and discuss existing literature on natural marine and terrestrial compounds, as well as their ability to modulate MMP-2 and MMP-9, and we evaluate their potential as therapeutic compounds for neurodegenerative and neuroinflammatory diseases, with a focus on Alzheimer's disease.

Citrullination as a novel posttranslational modification of matrix metalloproteinases

Matrix metalloproteinases (MMPs) are enzymes with critical roles in biology and pathology. Glycosylation, nitrosylation and proteolysis are known posttranslational modifications (PTMs) regulating intrinsically the activities of MMPs. We discovered MMP citrullination by peptidyl arginine deiminases (PADs) as a new PTM. Upon hypercitrullination, MMP-9 acquired a higher affinity for gelatin than control MMP-9. Furthermore, hypercitrullinated proMMP-9 was more efficiently activated by MMP-3 compared to control MMP-9. JNJ0966, a specific therapeutic inhibitor of MMP-9 activation, inhibited the activation of hypercitrullinated proMMP-9 by MMP-3 significantly less in comparison with control proMMP-9. The presence of citrullinated/homocitrullinated MMP-9 was detected in vivo in neutrophil-rich sputum samples of cystic fibrosis patients. In addition to citrullination of MMP-9, we report efficient citrullination of MMP-1 and lower citrullination levels of MMP-3 and MMP-13 by PAD2 in vitro. In conclusion, citrullination of MMPs is a new PTM worthy of additional biochemical and biological studies.

The Role of Matrix Metalloproteinase-9 in Atherosclerotic Plaque Instability

Matrix metalloproteinase-9 (MMP-9) belongs to the MMP family and has been widely investigated. Excessive MMP-9 expression can enhance extracellular matrix degradation and promote plaque instability. Studies have demonstrated that MMP-9 levels are higher in vulnerable plaques than in stable plaques. Additionally, several human studies have demonstrated that MMP-9 may be a predictor of atherosclerotic plaque instability and a risk factor for future adverse cardiovascular and cerebrovascular events. MMP-9 deficiency or blocking MMP-9 expression can inhibit plaque inflammation and prevent atherosclerotic plaque instability. All of these results suggest that MMP-9 may be a useful predictive biomarker for vulnerable atherosclerotic plaques, as well as a therapeutic target for preventing atherosclerotic plaque instability. In this review, we describe the structure, function, and regulation of MMP-9. We also discuss the role of MMP-9 in predicting and preventing atherosclerotic plaque instability.

Homotrimeric MMP-9 is an active hitchhiker on alpha-2-macroglobulin partially escaping protease inhibition and internalization through LRP-1

Proteolysis is a crucial process in life, tightly controlled by numerous natural protease inhibitors. In human blood, alpha-2-macroglobulin is an emergency protease inhibitor preventing coagulation and damage to endothelia and leukocytes. With the use of a unique protease trapping mechanism, alpha-2-macroglobulin lures active proteases into its snap-trap, shields these from potential substrates and 'flags' their complex for elimination by receptor-mediated endocytosis. Matrix metalloprotease-9/gelatinase B is a secreted protease increased in blood of patients with inflammations, vascular disorders and cancers. Matrix metalloprotease-9 occurs as monomers and stable homotrimers, but the reason for their co-existence remains obscure. We discovered that matrix metalloprotease-9 homotrimers undergo reduced anti-proteolytic regulation by alpha-2-macroglobulin and are able to travel as a proteolytically active hitchhiker on alpha-2-macroglobulin. As a comparison, we revealed that monomeric active matrix metalloprotease-9 is efficiently trapped by human plasma alpha-2-macroglobulin and this masks the detection of activated matrix metalloprotease-9 with standard analysis techniques. In addition, we show that alpha-2-macroglobulin/trimer complexes escape clearance through the receptor low-density lipoprotein receptor-related protein 1, also known as the alpha-2-macroglobulin receptor. Thus, the biochemistry and biology of matrix metalloprotease-9 monomers and trimers are completely different as multimerization enables active matrix metalloprotease-9 to partially avoid alpha-2-macroglobulin regulation both by direct protease inhibition and by removal from the extracellular space by receptor-mediated endocytosis. Finally, for the biomarker field, the analysis of alpha-2-macroglobulin/protease complexes with upgraded technology is advocated as a quotum for protease activation in human plasma samples.

Zinc-Calcium-Fluoride Bioglass-Based Innovative Multifunctional Dental Adhesive with Thick Adhesive Resin Film Thickness

Apart from producing high bond strength to tooth enamel and dentin, a dental adhesive with biotherapeutic potential is clinically desirable, aiming to further improve tooth restoration longevity. In this laboratory study, an experimental two-step universal adhesive, referred to as Exp_2UA, applicable in both the etch-and-rinse (E&R) and self-etch (SE) modes and combining a primer, containing 10-methacryloyloxydecyldihydrogen phosphate as a functional monomer with chemical binding potential to hydroxyapatite, with a bioglass-containing hydrophobic adhesive resin, was multifactorially investigated. In addition to primary property assessment, including measurement of bond strength, water sorption, solubility, and polymerization efficiency, the resultant adhesive-dentin interface was characterized by transmission electron microscopy (TEM), the filler composition was analyzed by energy-dispersive X-ray spectroscopy, and the bioactive potential of the adhesive was estimated by measuring the long-term ion release and assessing its antienzymatic and antibacterial potential. Four representative commercial adhesives were used as reference/controls. Application in both the E&R and SE modes resulted in a durable bonding performance to dentin, as evidenced by favorable 1 year aged bond strength data and a tight interfacial ultrastructure that, as examined by TEM, remained ultramorphologically unaltered upon 1 year of water storage aging. TEM revealed a 20 μm thick hydrophobic adhesive layer with a homogeneous bioglass filler distribution. Adequate polymerization conversion resulted in extremely low water sorption and solubility. In situ zymography revealed reduced endogenous proteolytic activity, while Streptococcus mutans biofilm formation was inhibited. In conclusion, the three-/two-step E&R/SE Exp_2UA combines the high bonding potential and bond degradation resistance with long-term ion release, rendering the adhesive antienzymatic and antibacterial potential.

Bivalent Inhibitor with Selectivity for Trimeric MMP-9 Amplifies Neutrophil Chemotaxis and Enables Functional Studies on MMP-9 Proteoforms

A fundamental part of the immune response to infection or injury is leukocyte migration. Matrix metalloproteinases (MMPs) are a class of secreted or cell-bound endopeptidases, implicated in every step of the process of inflammatory cell migration. Hence, specific inhibition of MMPs is an interesting approach to control inflammation. We evaluated the potential of a bivalent carboxylate inhibitor to selectively inhibit the trimeric proteoform of MMP-9 and compared this with a corresponding monovalent inhibitor. The bivalent inhibitor efficiently inhibited trimeric MMP-9 (IC₅₀ = 0.1 nM), with at least 500-fold selectivity for MMP-9 trimers over monomers. Surprisingly, in a mouse model for chemotaxis, the bivalent inhibitor amplified leukocyte influxes towards lipopolysaccharide-induced inflammation. We verified by microscopic and flow cytometry analysis increased amounts of neutrophils. In a mouse model for endotoxin shock, mice treated with the bivalent inhibitor had significantly increased levels of MMP-9 in plasma and lungs, indicative for increased inflammation. In conclusion, we propose a new role for MMP-9 trimers in tempering excessive neutrophil migration. In addition, we have identified a small molecule inhibitor with a high selectivity for the trimeric proteoform of MMP-9, which will allow further research on the functions of MMP-9 proteoforms.

Acute pharmacological inhibition of matrix metalloproteinase-9 activity during development restores perineuronal net formation and normalizes auditory processing in Fmr1 KO mice

Individuals with Fragile X Syndrome (FXS) and autism spectrum disorder (ASD) exhibit cognitive impairments, social deficits, increased anxiety, and sensory hyperexcitability. Previously, we showed that elevated levels of matrix metalloproteinase-9 (MMP-9) may contribute to abnormal development of parvalbumin (PV) interneurons and perineuronal nets (PNNs) in the developing auditory cortex (AC) of Fmr1 knock-out (KO) mice, which likely underlie auditory hypersensitivity. Thus, MMP-9 may serve as a potential target for treatment of auditory hypersensitivity in FXS. Here, we used the MMP-2/9 inhibitor, SB-3CT, to pharmacologically inhibit MMP-9 activity during a specific developmental period and to test whether inhibition of MMP-9 activity reverses neural oscillation deficits and behavioral impairments by enhancing PNN formation around PV cells in Fmr1 KO mice. Electroencephalography (EEG) was used to measure resting state and sound-evoked electrocortical activity in auditory and frontal cortices of postnatal day (P)22-23 male mice before and one-day after treatment with SB-3CT (25 mg/kg) or vehicle. At P27-28, animal behaviors were tested to measure the effects of the treatment on anxiety and hyperactivity. Results show that acute inhibition of MMP-9 activity improved evoked synchronization to auditory stimuli and ameliorated mouse behavioral deficits. MMP-9 inhibition enhanced PNN formation, increased PV levels and TrkB phosphorylation yet reduced Akt phosphorylation in the AC of Fmr1 KO mice. Our results show that MMP-9 inhibition during early postnatal development is beneficial in reducing some auditory processing deficits in the FXS mouse model and may serve as a candidate therapeutic for reversing sensory hypersensitivity in FXS and possibly other ASDs.

Post-Translational Modification-Dependent Activity of Matrix Metalloproteinases

Due to their capacity to process different proteins of the extracellular matrix (ECM), matrix metalloproteinases (MMPs) were initially described as a family of secreted proteases, functioning as main ECM regulators. However, through proteolytic processing of various biomolecules, MMPs also modulate intra- and extracellular pathways and networks. Thereby, they are functionally implicated in the regulation of multiple physiological and pathological processes. Consequently, MMP activity is tightly regulated through a combination of epigenetic, transcriptional, and post-transcriptional control of gene expression, proteolytic activation, post-translational modifications (PTMs), and extracellular inhibition. In addition, MMPs, their substrates and ECM binding partners are frequently modified by PTMs, which suggests an important role of PTMs in modulating the pleiotropic activities of these proteases. This review summarizes the recent progress towards understanding the role of PTMs (glycosylation, phosphorylation, glycosaminoglycans) on the activity of several members of the MMP family.

Mechanism of Pseudomonas aeruginosa Small Protease (PASP), a Corneal Virulence Factor

Purpose

Pseudomonas aeruginosa is the leading cause of contact lens-associated bacterial keratitis. Secreted bacterial proteases have a key role in keratitis, including the P. aeruginosa small protease (PASP), a proven corneal virulence factor. We investigated the mechanism of PASP and its importance to corneal toxicity.

Methods

PASP, a serine protease, was tested for activity on various substrates. The catalytic triad of PASP was sought by bioinformatic analysis and site-directed mutagenesis. All mutant constructs were expressed in a P. aeruginosa PASP-deficient strain; the resulting proteins were purified using ion-exchange, gel filtration, or affinity chromatography; and the proteolytic activity was assessed by gelatin zymography and a fluorometric assay. The purified PASP proteins with single amino acid changes were injected into rabbit corneas to determine their pathological effects.

Results

PASP substrates were cleaved at arginine or lysine residues. Alanine substitution of PASP residues Asp-29, His-34, or Ser-47 eliminated protease activity, whereas PASP with substitution for Ser-59 (control) retained activity. Computer modeling and Western blot analysis indicated that formation of a catalytic triad required dimer formation, and zymography demonstrated the protease activity of the homodimer, but not the monomer. PASP with the Ser-47 mutation, but not with the control mutation, lacked corneal toxicity, indicating the importance of protease activity.

Conclusions

PASP is a secreted serine protease that can cleave proteins at arginine or lysine residues and PASP activity requires dimer or larger aggregates to create a functional active site. Most importantly, proteolytic PASP molecules demonstrated highly significant toxicity for the rabbit cornea.

Propeptide glycosylation and galectin-3 binding decrease proteolytic activation of human proMMP-9/progelatinase B

Matrix metalloproteinases (MMPs) are secreted as proenzymes, containing propeptides that interact with the catalytic zinc, thereby controlling MMP activation. The MMP‐9 propeptide is unique in the MMP family because of its post‐translational modification with an N‐linked oligosaccharide. ProMMP‐9 activation by MMP‐3 occurs stepwise by cleavage of the propeptide in an aminoterminal (pro‐AT) and carboxyterminal (pro‐CT) peptide. We chemically synthesized aglycosyl pro‐AT and pro‐CT and purified recombinant glycosylated pro‐AT^Sf−9. First, we report new cleavage sites in the MMP‐9 propeptide by MMP‐3 and neutrophil elastase. Additionally, we demonstrated with the use of western blot analysis a higher resistance of glycosylated versus aglycosyl pro‐AT against proteolysis by MMP‐3, MMP‐9, meprin α, neutrophil elastase and by protease‐rich synovial fluids from rheumatoid arthritis patients. Moreover, we investigated the effect of glycosylation on proteolytic activation of human proMMP‐9 with the use of zymography and dye‐quenched gelatin cleavage analysis. Compared to recombinant Sf‐9 proMMP‐9 glycoforms, larger oligosaccharides of human neutrophil proMMP‐9 increased resistance against proteolytic activation. Additionally, proMMP‐9 from Congenital Disorder of Glycosylation patients, compared to healthy controls, showed a higher activation rate by MMP‐3. Finally, we demonstrated that glycan‐galectin‐3 interactions reduced proMMP‐9 activation. In conclusion, modification of MMP‐9 propeptide glycosylation is a fine‐tuning mechanism and co‐determines the specific activity of MMP‐9 in physiology and pathology.

Enzymes

MMP‐9 EC 3.4.24.35, MMP‐3 EC 3.4.24.17, meprin α EC 3.4.24.18, neutrophil elastase EC 3.4.21.37, trypsin EC 3.4.21.4 and PNGase F EC 3.5.1.52.

Evaluation of Tyrosinase Inhibitory, Antioxidant, Antimicrobial, and Antiaging Activities of Magnolia officinalis Extracts after Aspergillus niger Fermentation

This study intended to improve physiological characteristics of Magnolia officinalis bark (MOB) extracts by Aspergillus niger fermentation. M. officinalis bark was extracted using distilled water, 95% ethanol, and methanol, and it was then fermented by A. niger. The physiological characteristics of the fermented extracts, namely, tyrosinase inhibitory activity, antioxidant activity, antibacterial activity, and anti-skin-aging activity, were evaluated and compared with those of unfermented extracts. To determine the safety of the fermented extracts, their cytotoxicity was analyzed by measuring the cell viability of CCD-966SK and human epidermal melanocytes (HEMn) after exposure. The fermented methanol extract exhibited the highest antityrosinase activity, total phenolic content, and antioxidant activity. The total phenolic content of the extracts fermented by A. niger was 3.52 times greater than that of the unfermented extracts. The optimal IC₅₀ values for tyrosinase inhibition and 2,2-diphenyl-1-picrylhydrazyl (DPPH) removal by the A. niger-fermented extracts were 30 and 12 μg/mL, respectively. The fermented methanol extracts inhibited skin-aging-related enzymes such as collagenase, elastase, MMP-1, and MMP-2. Compared with the unfermented extracts, the fermented extracts also contained greater antibacterial activity against tested stains including MRSA. These results could be attributed to an increase in the concentration of original active compounds and the biosynthesis of new compounds during fermentation. In cytotoxicity assays, the A. niger-fermented extracts were nontoxic to CCD-966SK cells, even at 500 μg/mL. Hence, in general, methanol-extracted M. officinalis fermented by A. niger for 72 h has the most active antioxidant, skincare, or antiaging compounds for healthy food or cosmetics applications.

Interactions between Triterpenes and a P-I Type Snake Venom Metalloproteinase: Molecular Simulations and Experiments

Small molecule inhibitors of snake venom metalloproteinases (SVMPs) could provide a means to rapidly halt the progression of local tissue damage following viperid snake envenomations. In this study, we examine the ability of candidate compounds based on a pentacyclic triterpene skeleton to inhibit SVMPs. We leverage molecular dynamics simulations to estimate the free energies of the candidate compounds for binding to BaP1, a P-I type SVMP, and compare these results with experimental assays of proteolytic activity inhibition in a homologous enzyme (Batx-I). Both simulation and experiment suggest that betulinic acid is the most active candidate, with the simulations predicting a standard binding free energy of ΔG∘=−11.0±1.4 kcal/mol. The simulations also reveal the atomic interactions that underlie binding between the triterpenic acids and BaP1, most notably the electrostatic interaction between carboxylate groups of the compounds and the zinc cofactor of BaP1. Together, our simulations and experiments suggest that occlusion of the S1′ subsite is essential for inhibition of proteolytic activity. While all active compounds make hydrophobic contacts in the S1′ site, β-boswellic acid, with its distinct carboxylate position, does not occlude the S1′ site in simulation and exhibits negligible activity in experiment.

Skin Anti-aging Assays of Proanthocyanidin Rich Red Rice Extract, Oryzanol and Other Phenolic Compounds

Red rice is a variety of rice that has more nutritious than white or brown rice. It is also a good source of many potent anti-aging phytochemicals. However, the compounds in red rice extract that exhibit skin anti-aging properties have not been investigated. In this study, the main bioactive compounds in red rice extract (RRE) including proanthocyanidin, catechin, hydroxybenzoic acid, vanillic acid and oryzanol were studied in order to determine their anti-skin aging properties. The effects on skin degradation were assessed by inhibitory enzymatic activity against collagenase and matrixmetalloproteinase-2 (MMP-2). The production levels of collagen and hyaluronic acid obtained from human skin fibroblasts were determined by ELISA. Anti-melanogenesis activity of the bioactive compounds were investigated in B16-F10 mouse melanoma cells. The activity of collagenase and MMP-2 was strongly inhibited by proanthocyanidin and catechin, while hydroxybenzoic acid, vanillic acid and oryzanol had no effect. Moreover, proanthocyanindin and catechin significantly induced collagen and hyaluronic acid synthesis in human fibroblast cells. Proanthocyanidin and oryzanol reduced the melanin content in B16-F10 mouse melanoma cells. Proanthocyanidin, but not oryzanol, significantly decreased cellular tyrosinase activity. However, the bioactive compounds obtained from red rice extract had no effect on mushroom tyrosinase activity. In addition, proanthocynidin and catechin, exhibited strong DPPH radical scavenging activity, whereas oryzanol slightly inhibited this action. Taken together, these results suggest that proanthocyanidin, catechin, and oryzanol are the bioactive compounds in red rice that exhibit the greatest levels of anti-skin aging properties.

Matrix Metalloproteinase-9-Generated COOH-, but Not NH2-Terminal Fragments of Serum Amyloid A1 Retain Potentiating Activity in Neutrophil Migration to CXCL8, With Loss of Direct Chemotactic and Cytokine-Inducing Capacity

Serum amyloid A1 (SAA1) is a prototypic acute phase protein, induced to extremely high levels by physical insults, including inflammation and infection. Human SAA and its NH₂-terminal part have been studied extensively in the context of amyloidosis. By contrast, little is known about COOH-terminal fragments of SAA. Intact SAA1 chemoattracts leukocytes via the G protein-coupled receptor formyl peptide receptor like 1/formyl peptide receptor 2 (FPR2). In addition to direct leukocyte activation, SAA1 induces chemokine production by signaling through toll-like receptor 2. We recently discovered that these induced chemokines synergize with intact SAA1 to chemoattract leukocytes in vitro and in vivo. Gelatinase B or matrix metalloproteinase-9 (MMP-9) is also induced by SAA1 during infection and inflammation and processes many substrates in the immune system. We demonstrate here that MMP-9 rapidly cleaves SAA1 at a known consensus sequence that is also present in gelatins. Processing of SAA1 by MMP-9 at an accessible loop between two alpha helices yielded predominantly three COOH-terminal fragments: SAA1(52–104), SAA1(57–104), and SAA1(58–104), with a relative molecular mass of 5,884.4, 5,327.3, and 5,256.3, respectively. To investigate the effect of proteolytic processing on the biological activity of SAA1, we chemically synthesized the COOH-terminal SAA fragments SAA1(52–104) and SAA1(58–104) and the complementary NH₂-terminal peptide SAA1(1–51). In contrast to intact SAA1, the synthesized SAA1 peptides did not induce interleukin-8/CXCL8 in monocytes or fibroblasts. Moreover, these fragments possessed no direct chemotactic activity for neutrophils, as observed for intact SAA1. However, comparable to intact SAA1, SAA1(58–104) cooperated with CXCL8 in neutrophil activation and migration, whereas SAA1(1–51) lacked this potentiating activity. This cooperative interaction between the COOH-terminal SAA1 fragment and CXCL8 in neutrophil chemotaxis was mediated by FPR2. Hence, proteolytic cleavage of SAA1 by MMP-9 fine tunes the inflammatory capacity of this acute phase protein in that only the synergistic interactions with chemokines remain to prolong the duration of inflammation.

Endotoxemia shifts neutrophils with TIMP-free gelatinase B/MMP-9 from bone marrow to the periphery and induces systematic upregulation of TIMP-1

Lipopolysaccharides or endotoxins elicit an excessive host inflammatory response and lead to life-threatening conditions such as endotoxemia and septic shock. Lipopolysaccharides trigger mobilization and stimulation of leukocytes and exaggerated production of pro-inflammatory molecules including cytokines and proteolytic enzymes. Matrix metalloproteinase-9 (MMP-9) or gelatinase B, a protease stored in the tertiary granules of polymorphonuclear leukocytes, has been implicated in such inflammatory reactions. Moreover, several studies even pinpointed MMP-9 as a potential target molecule to counter excessive inflammation in endotoxemia. Whereas the early effect of lipopolysaccharide-induced inflammation in vivo on the expression of MMP-9 in various peripheral organs has been described, the effects on the bone marrow and during late stage endotoxemia remain elusive. We demonstrate that TIMP-free MMP-9 is a major factor in bone marrow physiology and pathology. By using a mouse model for late-stage endotoxemia, we show that lipopolysaccharides elicited a depletion of neutrophil MMP-9 in the bone marrow and a shift of MMP-9 and MMP-9-containing cells towards peripheral organs, a pattern which was primarily associated with a relocation of CD11b^highGr-1^high cells. In contrast, analysis of the tissue inhibitors of metalloproteinases was in line with a natural, systematic upregulation of TIMP-1, the main tissue inhibitor of TIMP-free MMP-9, and a general shift toward control of matrix metalloproteinase activity by tissue inhibitors of metalloproteinases.

Blood-Brain Barrier Permeability Is Exacerbated in Experimental Model of Hepatic Encephalopathy via MMP-9 Activation and Downregulation of Tight Junction Proteins

The present study was designed to investigate the mechanisms involved in blood-brain barrier (BBB) permeability in bile duct ligation (BDL) model of chronic hepatic encephalopathy (HE). Four weeks after BDL surgery, a significant increase was observed in serum bilirubin levels. Masson trichrome staining revealed severe hepatic fibrosis in the BDL rats. ^99mTc-mebrofenin retention was increased in the liver of BDL rats suggesting impaired hepatobiliary transport. An increase in permeability to sodium fluorescein, Evans blue, and fluorescein isothiocyanate (FITC)-dextran along with increase in water and electrolyte content was observed in brain regions of BDL rats suggesting disrupted BBB. Increased brain water content can be attributed to increase in aquaporin-4 mRNA and protein expression in BDL rats. Matrix metalloproteinase-9 (MMP-9) mRNA and protein expression was increased in brain regions of BDL rats. Additionally, mRNA and protein expression of tissue inhibitor of matrix metalloproteinases (TIMPs) was also increased in different regions of brain. A significant decrease in mRNA expression and protein levels of tight junction proteins, viz., occludin, claudin-5, and zona occluden-1 (ZO-1) was observed in different brain regions of BDL rats. VCAM-1 mRNA and protein expression was also found to be significantly upregulated in different brain regions of BDL animals. The findings from the study suggest that increased BBB permeability in HE involves activation of MMP-9 and loss of tight junction proteins.

Differential inhibition of activity, activation and gene expression of MMP-9 in THP-1 cells by azithromycin and minocycline versus bortezomib: A comparative study

Gelatinase B or matrix metalloproteinase-9 (MMP-9) (EC 3.4.24.35) is increased in inflammatory processes and cancer, and is associated with disease progression. In part, this is due to MMP-9-mediated degradation of extracellular matrix, facilitating influx of leukocytes into inflamed tissues and invasion or metastasis of cancer cells. MMP-9 is produced as proMMP-9 and its propeptide is subsequently removed by other proteases to generate proteolytically active MMP-9. The significance of MMP-9 in pathologies triggered the development of specific inhibitors of this protease. However, clinical trials with synthetic inhibitors of MMPs in the fight against cancer were disappointing. Reports on active compounds which inhibit MMP-9 should be carefully examined in this regard. In a considerable set of recent publications, two antibiotics (minocycline and azythromycin) and the proteasome inhibitor bortezomib, used in cancers, were reported to inhibit MMP-9 at different stages of its expression, activation or activity. The current study was undertaken to compare and to verify the impact of these compounds on MMP-9. With exception of minocycline at high concentrations (>100 μM), the compounds did not affect processing of proMMP-9 into MMP-9, nor did they affect direct MMP-9 gelatinolytic activity. In contrast, azithromycin specifically reduced MMP-9 mRNA and protein levels without affecting NF-κB in endotoxin-challenged monocytic THP-1 cells. Bortezomib, although being highly toxic, had no MMP-9-specific effects but significantly upregulated cyclooxygenase-2 (COX-2) activity and PGE₂ levels. Overall, our study clarified that azithromycin decreased the levels of MMP-9 by reduction of gene and protein expression while minocycline inhibits proteolytic activity at high concentrations.

Mechanosensitive microRNA-181b Regulates Aortic Valve Endothelial Matrix Degradation by Targeting TIMP3

Calcific aortic valve disease (CAVD) is a major cause of morbidity in the aging population, but the underlying mechanisms of its progression remain poorly understood. Aortic valve calcification preferentially occurs on the fibrosa, which is subjected to disturbed flow. The side-specific progression of the disease is characterized by inflammation, calcific lesions, and extracellular matrix (ECM) degradation. Here, we explored the role of mechanosensitive microRNA-181b and its downstream targets in human aortic valve endothelial cells (HAVECs). Mechanistically, miR-181b is upregulated in OS and fibrosa, and it targets TIMP3, SIRT1, and GATA6, correlated with increased gelatinase/MMP activity. Overexpression of miR-181b led to decreased TIMP3 and exacerbated MMP activity as shown by gelatinase assay, and miR-181b inhibition decreased gelatinase activity through the repression of TIMP3 levels. Luciferase assay showed specific binding of miR-181b to the TIMP3 gene. Overexpression of miR-181b in HAVECs subjected to either LS or OS increased MMP activity, and miR-181b inhibition abrogated shear-sensitive MMP activity. These studies suggest that targeting this shear-dependent miRNA may provide a novel noninvasive treatment for CAVD.

Biochemical characterization and structure determination of a potent, selective antibody inhibitor of human MMP9

Matrix metalloproteinase 9 (MMP9) is a member of a large family of proteases that are secreted as inactive zymogens. It is a key regulator of the extracellular matrix, involved in the degradation of various extracellular matrix proteins. MMP9 plays a pathological role in a variety of inflammatory and oncology disorders and has long been considered an attractive therapeutic target. GS-5745, a potent, highly selective humanized monoclonal antibody inhibitor of MMP9, has shown promise in treating ulcerative colitis and gastric cancer. Here we describe the crystal structure of GS-5745·MMP9 complex and biochemical studies to elucidate the mechanism of inhibition of MMP9 by GS-5745. GS-5745 binds MMP9 distal to the active site, near the junction between the prodomain and catalytic domain, and inhibits MMP9 by two mechanisms. Binding to pro-MMP9 prevents MMP9 activation, whereas binding to active MMP9 allosterically inhibits activity.

Anti-aging and tyrosinase inhibition effects of Cassia fistula flower butanolic extract

BACKGROUND

Natural products made from plant sources have been used in a variety of cosmetic applications as a source of nutrition and as a whitening agent. The flowers of Cassia fistula L, family Fabaceae, have been used as a traditional medicine for skin diseases and wound healing and have been reported to possess anti-oxidant properties. The anti-aging effect of C. fistula flower extract on human skin fibroblast was investigated.

METHODS

The butanolic extraction of C. fistula flowers was completed and the active compounds were classified. The cytotoxicity of fibroblasts was evaluated by SRB assay for the purposes of selecting non-toxic doses for further experiments. The collagen and hyaluronic acid (HA) synthesis was then measured using the collagen kit and ELISA, respectively. Moreover, the enzyme activity, including collagenase, matrixmelloproteinase-2 (MMP-2) and tyrosinase, were also evaluated.

RESULTS

It was found that the flower extract did not affect skin fibroblast cell growth (IC₅₀ > 200 μg/mL). The results did show that the flower extract significantly increased collagen and HA synthesis in a dose dependent manner. The flower extract (50-200 μg/mL) also significantly inhibited collagenase and MMP-2 activity. Furthermore, this flower extract could inhibit the tyrosinase activity that causes hyperpigmentation, which induces skin aging.

CONCLUSIONS

The C. fistula flower extract displayed a preventive effect when used for anti-aging purposes in human skin fibroblasts and may be an appropriate choice for cosmetic products that aim to provide whitening effects, and which are designated as anti-aging facial skin care products.

Inhibition of the MAPK Signaling Pathway by Red Rice Extract in UVB-irradiated Human Skin Fibroblasts

Red rice has demonstrated several biological properties including anti-oxidant and anti-inflammation properties. However, the anti-photoaging activity has not yet been investigated. The aim of this study relates to the photo-protective effects of red rice extract (RRE) on UVB-induced skin aging. RRE was prepared and the active compounds and anti-oxidant activity were determined. The cytotoxicity of fibroblasts and secretions of IL-6 and IL-8 were evaluated. The effects of RRE on collagen and hyaluronic acid (HA) synthesis from fibroblasts were evaluated. Then, the collagenase and MMP-2 activity was determined. The effect of RRE on UV-induced MMP-1, nuclear factor kappa B (NF-κB), activator protein-1 (AP-1) and phosphorylation of MAPK protein expression was determined by western blot analysis. The RRE exerted a free radical scavenging property. RRE significantly increased collagen and HA synthesis in UVB-irradiated human fibroblasts. Moreover, RRE significantly inhibited UVB induced MMP-1 expression, MMP-2 and collagenase activity. Upon UVB irradiation, mitogen activated protein kinases (MAPKs) is activated and this pathway stimulates the expression of interleukin-6 and-8 (IL-6 and-8). Our results show that RRE decreases UVB-induced IL-6 and -8 production and the phosphorylation of c-Jun NH2-terminal kinase (JNK) and the p38 MAPK signaling process. In addition, RRE reduced UVB-induced activation of NF-κB and AP-1. RRE could suppress UV-induced inflammation and skin aging via the inhibition of the MAPK signaling pathway leading to the decrease of NF-κB and AP-1 activation resulting in a decrease in ECM degradation and an increase in ECM synthesis.

Genetic Deletion of Tissue Inhibitor of Metalloproteinase-1/TIMP-1 Alters Inflammation and Attenuates Fibrosis in Dextran Sodium Sulphate-induced Murine Models of Colitis

BACKGROUND AND AIMS

Increased levels of tissue inhibitor of metalloproteinase-1 [TIMP-1] have been detected in both inflammatory and fibrotic lesions in Crohn's disease. In a murine model of chronic inflammation, fibrosis was associated with an increase in TIMP-1 and inhibition of matrix metalloproteinase [MMP]-mediated degradation. We investigated the effect of TIMP-1 deficiency in acute and chronic murine models of colitis.

METHODS

Colitis was induced via oral administration of dextran sodium sulphate [DSS] to B6.129S4-Timp1^tm1Pds/J knock-out [KO] and C57BL/6J wild-type [WT] mice. Levels of inflammation and fibrosis were assessed and gelatin zymographies and gene expression microarrays were performed.

RESULTS

Compared with WT mice, TIMP-1 KO mice had higher inflammatory parameters after acute DSS administration and developed less fibrosis after chronic DSS administration. MMP-2 levels were increased in WT versus TIMP-1 KO mice with acute colitis, whereas a trend for higher proMMP-9 levels was observed in WT versus TIMP-1 KO mice with chronic colitis. In control conditions, several immune-related genes [e.g Ido1, Cldn8] were differentially expressed between young TIMP-1 KO and WT mice, but to a lesser extent between older TIMP-1 KO and WT mice. In response to DSS, the gene expression pattern was significantly different between young TIMP-1 KO and WT mice, whereas it was similar in older TIMP-1 KO and WT mice.

CONCLUSIONS

TIMP-1 deficiency leads to differential expression of immune-related genes and to attenuated development of fibrosis. Unravelling the role of TIMP-1 in intestinal remodelling is necessary to develop more effective and more targeted therapeutic strategies for intestinal fibrosis.

Humoral immunity in phenotypes of chronic lung allograft dysfunction: A broncho-alveolar lavage fluid analysis

BACKGROUND

Recently, antibody mediated rejection (AMR) has been associated with a higher incidence of chronic lung allograft dysfunction (CLAD) and mortality after lung transplantation (LTx). We investigated markers related to AMR and matrix remodeling in CLAD, with special attention for its two phenotypes being bronchiolitis obliterans syndrome (BOS) and restrictive CLAD (rCLAD).

METHODS

Immunoglobulins (IgA, IgE, IgG1-IgG4, total IgG and IgM) and complement (C4d and C1q) were quantified in lung lavage samples at the moment of BOS (n=15) or RAS (n=16) diagnosis; and were compared to stable transplant patients who served as control (n=14). Also, airway remodeling and metalloproteinases (MMPs) were investigated via zymography and gelatin degradation. The presence of DSA was additionally assessed in blood.

RESULTS

Total IgG, IgG1-IgG4 and IgM were increased in rCLAD versus control (p<0.001) and BOS patients (p<0.01). IgA and IgE were increased in rCLAD compared to control (respectively p<0.05 and p<0.01), but not to BOS. Total IgG and IgE were increased in BOS versus control (respectively p<0.01 and p<0.05). Complement proteins were exclusively present in rCLAD and correlated positively with immunoglobulins. Additionally, in blood, DSA were more present in rCLAD (p=0.041). MMP-9 levels increased in RAS and BOS versus control (p<0.001) and MMP-9 induced gelatin degradation was only increased in BOS compared to control (p<0.01).

CONCLUSION

We demonstrated increased levels of immunoglobulins and complement proteins dominantly present in rCLAD. This leads to the belief that antibodies and AMR might play a more important role in rCLAD compared to BOS. Therefore, anti B-cell therapy could offer beneficial therapeutic effects in patients diagnosed with rCLAD, which needs further research.

Intratumoral oxygen gradients mediate sarcoma cell invasion

Hypoxia is a critical factor in the progression and metastasis of many cancers, including soft tissue sarcomas. Frequently, oxygen (O2) gradients develop in tumors as they grow beyond their vascular supply, leading to heterogeneous areas of O2 depletion. Here, we report the impact of hypoxic O2 gradients on sarcoma cell invasion and migration. O2 gradient measurements showed that large sarcoma mouse tumors (>300 mm(3)) contain a severely hypoxic core [≤0.1% partial pressure of O2 (pO2)] whereas smaller tumors possessed hypoxic gradients throughout the tumor mass (0.1-6% pO2). To analyze tumor invasion, we used O2-controllable hydrogels to recreate the physiopathological O2 levels in vitro. Small tumor grafts encapsulated in the hydrogels revealed increased invasion that was both faster and extended over a longer distance in the hypoxic hydrogels compared with nonhypoxic hydrogels. To model the effect of the O2 gradient accurately, we examined individual sarcoma cells embedded in the O2-controllable hydrogel. We observed that hypoxic gradients guide sarcoma cell motility and matrix remodeling through hypoxia-inducible factor-1α (HIF-1α) activation. We further found that in the hypoxic gradient, individual cells migrate more quickly, across longer distances, and in the direction of increasing O2 tension. Treatment with minoxidil, an inhibitor of hypoxia-induced sarcoma metastasis, abrogated cell migration and matrix remodeling in the hypoxic gradient. Overall, we show that O2 acts as a 3D physicotactic agent during sarcoma tumor invasion and propose the O2-controllable hydrogels as a predictive system to study early stages of the metastatic process and therapeutic targets.

Inhibition of MMP-9-dependent Degradation of Gelatin, but Not Other MMP-9 Substrates, by the MMP-9 Hemopexin Domain Blades 1 and 4

Degradation and remodeling of the extracellular matrix by matrix metalloproteinases (MMPs) plays important roles in normal development, inflammation, and cancer. MMP-9 efficiently degrades the extracellular matrix component gelatin, and the hemopexin domain of MMP-9 (PEX9) inhibits this degradation. To study the molecular basis of this inhibition, we generated GST fusion proteins containing PEX9 or truncated forms corresponding to specific structural blades (B1-B4) of PEX9. GST-PEX9 inhibited MMP-9-driven gelatin proteolysis, measured by gelatin zymography, FITC-gelatin conversion, and DQ-gelatin degradation assays. However, GST-PEX9 did not prevent the degradation of other MMP-9 substrates, such as a fluorogenic peptide, αB crystalline, or nonmuscular actin. Therefore, PEX9 may inhibit gelatin degradation by shielding gelatin and specifically preventing its binding to MMP-9. Accordingly, GST-PEX9 also abolished the degradation of gelatin by MMP-2, confirming that PEX9 is not an MMP-9 antagonist. Moreover, GST-B4 and, to a lesser extent, GST-B1 also inhibited gelatin degradation by MMP-9, indicating that these regions are responsible for the inhibitory activity of PEX9. Accordingly, ELISAs demonstrated that GST-B4 and GST-B1 specifically bound to gelatin. Our results establish new functions of PEX9 attributed to blades B4 and B1 and should help in designing specific inhibitors of gelatin degradation.

Characterization of MMP-9 gene from a normalized cDNA library of kidney tissue of yellow catfish (Pelteobagrus fulvidraco)

Matrix metalloproteinase-9 (MMP-9), one of members of the MMP family, is important for the cleaving of structural extracellular matrix (ECM) molecules and involved in inflammatory processes. In this study, MMP-9 cDNA was isolated and characterized from a normalized cDNA library of kidney tissue of yellow catfish (designated as YcMMP-9). The complete sequence of YcMMP-9 cDNA consisted of 2561 nucleotides. The open reading frame potentially encoded a protein of 685 amino acids with a calculated molecular mass of approximately 77.182 kDa. Amino acid sequence of YcMMP-9 have typical characteristics of MMP-9 family and showed highest identity (85.3%) to channel catfish MMP-9. The YcMMP-9 genomic DNA contains 13 exons and 12 introns. Quantitative RT-PCR (qRT-PCR) analysis showed that YcMMP-9 mRNA was constitutively expressed in all examined tissues in normal fish with high expression in head kidney, trunk kidney, blood, and spleen. However, expression of YcMMP-9 mRNA was induced by Aeromonas hydrophila stimulation, especially in these four tissues mentioned above. It indicated that YcMMP-9 was involved in innate immune responses against bacterial infection.

Circular trimers of gelatinase B/matrix metalloproteinase-9 constitute a distinct population of functional enzyme molecules differentially regulated by tissue inhibitor of metalloproteinases-1

Gelatinase B/matrix metalloproteinase-9 (MMP-9) (EC 3.4.24.35) cleaves many substrates and is produced by most cell types as a zymogen, proMMP-9, in complex with the tissue inhibitor of metalloproteinases-1 (TIMP-1). Natural proMMP-9 occurs as monomers, homomultimers and heterocomplexes, but our knowledge about the overall structure of proMMP-9 monomers and multimers is limited. We investigated biochemical, biophysical and functional characteristics of zymogen and activated forms of MMP-9 monomers and multimers. In contrast with a conventional notion of a dimeric nature of MMP-9 homomultimers, we demonstrate that these are reduction-sensitive trimers. Based on the information from electrophoresis, AFM and TEM, we generated a 3D structure model of the proMMP-9 trimer. Remarkably, the proMMP-9 trimers possessed a 50-fold higher affinity for TIMP-1 than the monomers. In vivo, this finding was reflected in a higher extent of TIMP-1 inhibition of angiogenesis induced by trimers compared with monomers. Our results show that proMMP-9 trimers constitute a novel structural and functional entity that is differentially regulated by TIMP-1.

S-nitrosoglutathione prevents blood-brain barrier disruption associated with increased matrix metalloproteinase-9 activity in experimental diabetes

Hyperglycemia is known to induce microvascular complications, thereby altering blood-brain barrier (BBB) permeability. This study investigated the role of matrix metalloproteinases (MMPs) and their endogenous inhibitors in increased BBB permeability and evaluated the protective effect of S-nitrosoglutathione (GSNO) in diabetes. Diabetes was induced in mice by intraperitoneal injection of streptozotocin (40 mg/kg body weight) for 5 days and GSNO was administered orally (100 μg/kg body weight) daily for 8 weeks after the induction of diabetes. A significant decline in cognitive functions was observed in diabetic mice assessed by Morris water maze test. Increased permeability to different molecular size tracers accompanied by edema and ion imbalance was observed in cortex and hippocampus of diabetic mice. Furthermore, activity of both pro and active MMP-9 was found to be significantly elevated in diabetic animals. Increased in situ gelatinase activity was observed in tissue sections and isolated microvessels from diabetic mice brain. The increase in activity of MMP-9 was attributed to increased mRNA and protein expression in diabetic mice. In addition, a significant decrease in mRNA and protein expression of tissue inhibitor of matrix metalloproteinase-1 was also observed in diabetic animals. However, GSNO supplementation to diabetic animals was able to abridge MMP-9 activation as well as tissue inhibitor of matrix metalloproteinase-1 levels, restoring BBB integrity and also improving learning and memory. Our findings clearly suggest that GSNO could prevent hyperglycemia-induced disruption of BBB by suppressing MMP-9 activity.

Infliximab restores the dysfunctional matrix remodeling protein and growth factor gene expression in patients with inflammatory bowel disease

BACKGROUND

Matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), a disintegrin and metalloprotease with thrombospondin motifs [ADAM(TS)s] and growth factors are involved in inflammation and tissue damage and repair, all occurring in inflammatory bowel disease (IBD). We studied the impact of anti-inflammatory therapy with infliximab on mucosal expression of these tissue remodeling genes in patients with IBD.

METHODS

Mucosal gene expression of 23 MMPs, 4 TIMPs, 50 ADAM(TS)s, and 158 growth factors was investigated in 61 patients with IBD before and after the first infliximab therapy and in 12 controls, with microarrays and quantitative RT-PCR. Protein localization, mucosal gelatinase levels, and net gelatinolytic activity were investigated by immunohistochemistry, zymography analysis, and gelatin degradation assay, respectively.

RESULTS

In patients with active IBD before infliximab versus controls, gene expression of many MMPs, TIMPs, ADAM(TS)s, and growth factors was upregulated, whereas colonic expression of MMP28 and TGFA and ileal expression of ADAMDEC1 and AGT were downregulated. After controlling inflammation with infliximab, most gene dysregulations observed at baseline were restored in responders. Increased ratio of MMP1/TIMP1 expression at baseline in active IBD was restored in responders with colonic mucosal healing. With immunohistochemistry, protein localization differences of MMP1, MMP3, REG1A, and TIMP1 were shown between active IBD and control mucosa. With zymography analysis and gelatin degradation assay, higher gelatinase levels and net gelatinolytic activity were measured before infliximab and levels normalized after infliximab.

CONCLUSIONS

Our data suggest that suppression of inflammation results in the arrest of epithelial damage and subsequent mucosal healing. Therefore, the therapeutic potential of agents targeting MMPs or growth factors as primary therapy seems rather complex.

Gelatinase B/MMP-9 in Tumour Pathogenesis and Progression

Since its original identification as a leukocyte gelatinase/type V collagenase and tumour type IV collagenase, gelatinase B/matrix metalloproteinase (MMP)-9 is now recognised as playing a central role in many aspects of tumour progression. In this review, we relate current concepts concerning the many ways in which gelatinase B/MMP-9 influences tumour biology. Following a brief outline of the gelatinase B/MMP-9 gene and protein, we analyse the role(s) of gelatinase B/MMP-9 in different phases of the tumorigenic process, and compare the importance of gelatinase B/MMP-9 source in the carcinogenic process. What becomes apparent is the importance of inflammatory cell-derived gelatinase B/MMP-9 in tumour promotion, early progression and triggering of the "angiogenic switch", the integral relationship between inflammatory, stromal and tumour components with respect to gelatinase B/MMP-9 production and activation, and the fundamental role for gelatinase B/MMP-9 in the formation and maintenance of tumour stem cell and metastatic niches. It is also apparent that gelatinase B/MMP-9 plays important tumour suppressing functions, producing endogenous angiogenesis inhibitors, promoting inflammatory anti-tumour activity, and inducing apoptosis. The fundamental roles of gelatinase B/MMP-9 in cancer biology underpins the need for specific therapeutic inhibitors of gelatinase B/MMP-9 function, the use of which must take into account and substitute for tumour-suppressing gelatinase B/MMP-9 activity and also limit inhibition of physiological gelatinase B/MMP-9 function.