Insights into MMP-TIMP interactions

Breaking the Cycle: Matrix Metalloproteinase Inhibitors as an Alternative Approach in Managing Tuberculosis Pathogenesis and Progression

Mycobacterium tuberculosis (Mtb) has long posed a significant challenge to global public health, resulting in approximately 1.6 million deaths annually. Pulmonary tuberculosis (TB) instigated by Mtb is characterized by extensive lung tissue damage, leading to lesions and dissemination within the tissue matrix. Matrix metalloproteinases (MMPs) exhibit endopeptidase activity, contributing to inflammatory tissue damage and, consequently, morbidity and mortality in TB patients. MMP activities in TB are intricately regulated by various components, including cytokines, chemokines, cell receptors, and growth factors, through intracellular signaling pathways. Primarily, Mtb-infected macrophages induce MMP expression, disrupting the balance between MMPs and tissue inhibitors of metalloproteinases (TIMPs), thereby impairing extracellular matrix (ECM) deposition in the lungs. Recent research underscores the significance of immunomodulatory factors in MMP secretion and granuloma formation during Mtb pathogenesis. Several studies have investigated both the activation and inhibition of MMPs using endogenous MMP inhibitors (i.e., TIMPs) and synthetic inhibitors. However, despite their promising pharmacological potential, few MMP inhibitors have been explored for TB treatment as host-directed therapy. Scientists are exploring novel strategies to enhance TB therapeutic regimens by suppressing MMP activity to mitigate Mtb-associated matrix destruction and reduce TB induced lung inflammation. These strategies include the use of MMP inhibitor molecules alone or in combination with anti-TB drugs. Additionally, there is growing interest in developing novel formulations containing MMP inhibitors or MMP-responsive drug delivery systems to suppress MMPs and release drugs at specific target sites. This review summarizes MMPs' expression and regulation in TB, their role in immune response, and the potential of MMP inhibitors as effective therapeutic targets to alleviate TB immunopathology.

Role of inflammatory mediators in intracranial aneurysms: A review

The formation, growth, and rupture of intracranial aneurysms (IAs) involve hemodynamics, blood pressure, external stimuli, and a series of hormonal changes. In addition, inflammatory response causes the release of a series of inflammatory mediators, such as IL, TNF-α, MCP-1, and MMPs, which directly or indirectly promote the development process of IA. However, the specific role of these inflammatory mediators in the pathophysiological process of IA remains unclear. Recently, several anti-inflammatory, lipid-lowering, hormone-regulating drugs have been found to have a potentially protective effect on reducing IA formation and rupture in the population. These therapeutic mechanisms have not been fully elucidated, but we can look for potential therapeutic targets that may interfere with the formation and breakdown of IA by studying the relevant inflammatory response and the mechanism of IA formation and rupture involved in inflammatory mediators.

Core genes of biomineralization and cis-regulatory long non-coding RNA regulate shell growth in bivalves

INTRODUCTION

Bivalve molluscs are abundant in marine and freshwater systems and contribute essential ecosystem services. They are characterized by an exuberant diversity of biomineralized shells and typically have two symmetric valves (a.k.a shells), but oysters (Ostreidae), some clams (Anomiidae and Chamidae) and scallops (Pectinida) have two asymmetrical valves. Predicting and modelling the likely consequences of ocean acidification on bivalve survival, biodiversity and aquaculture makes understanding shell biomineralization and its regulation a priority.

OBJECTIVES

This study aimed to a) exploit the atypical asymmetric shell growth of some bivalves and through comparative analysis of the genome and transcriptome pinpoint candidate biomineralization-related genes and regulatory long non-coding RNAs (LncRNAs) and b) demonstrate their roles in regulating shell biomineralization/growth.

METHODS

Meta-analysis of genomes, de novo generated mantle transcriptomes or transcriptomes and proteomes from public databases for six asymmetric to symmetric bivalve species was used to identify biomineralization-related genes. Bioinformatics filtering uncovered genes and regulatory modules characteristic of bivalves with asymmetric shells and identified candidate biomineralization-related genes and lncRNAs with a biased expression in asymmetric valves. A shell regrowth model in oyster and gene silencing experiments, were used to characterize candidate gene function.

RESULTS

Shell matrix genes with asymmetric expression in the mantle of the two valves were identified and unique cis-regulatory lncRNA modules characterized in Ostreidae. LncRNAs that regulate the expression of the tissue inhibitor of metalloproteinases gene family (TIMPDR) and of the shell matrix protein domain family (SMPDR) were identified. In vitro and in vivo silencing experiments revealed the candidate genes and lncRNA were associated with divergent shell growth rates and modified the microstructure of calcium carbonate (CaCO3) crystals.

CONCLUSION

LncRNAs are putative regulatory factors of the bivalve biomineralization toolbox. In the Ostreidae family of bivalves biomineralization-related genes are cis-regulated by lncRNA and modify the planar growth rate and spatial orientation of crystals in the shell.

Evaluation of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in human cases with orofacial clefts: A systematic review

INTRODUCTION

The interaction between several cell populations or many genes and the coordination of multiple signal transmission pathways can lead to defects such as orofacial clefts (OFCs). Herein, a systematic review was designed to evaluate a group of important biomarkers (matrix metalloproteinases [MMPs] and tissue inhibitors of metalloproteinases [TIMPs]) in human cases with OFCs.

MATERIAL AND METHODS

Four databases including PubMed, Scopus, Web of Science, and Cochrane Library databases were searched until March 10, 2023, without any restriction. STRING, the protein-protein interaction (PPI) network software, was applied to investigate the functional interactions among the examined genes. The effect sizes including odds ratio (OR) dealing with a 95% confidence interval (CI), were extracted by the Comprehensive Meta-Analysis version 2.0 (CMA 2.0) software.

RESULTS

Thirty-one articles were entered into the systematic review that four articles were analyzed in the meta-analysis. Single studies reported that several polymorphisms of MMPs (rs243865, rs9923304, rs17576, rs6094237, rs7119194, and rs7188573); and TIMPs (rs8179096, rs7502916, rs4789936, rs6501266, rs7211674, rs7212662, and rs242082) had an association with OFC risk. There was no significant difference for MMP-3 rs3025058 polymorphism in allelic (OR: 0.832; P=0.490), dominant (OR: 1.177; P=0.873), and recessive (OR: 0.363; P=0.433) models and MMP-9 rs17576 polymorphism in an allelic model (OR: 0.885; P=0.107) between the OFC cases and the controls. Based on immunohistochemistry reports, three MMPs (MMP-2, MMP-8, and MMP-9) and TIMP-2 had significant correlations with several other biomarkers in OFC cases.

CONCLUSIONS

MMPs and TIMPs can impact the tissue and cells affected by OFCs and the process of apoptosis. The interaction between some biomarkers with MMPs and TIMPs (e.g., TGFb1) in OFCs can be interesting for future research.

Inhibition of discoidin domain receptor (DDR)-1 with nilotinib alters CSF miRNAs and is associated with reduced inflammation and vascular fibrosis in Alzheimer's disease

Discoidin Domain Receptor (DDR)-1 is activated by collagen. Nilotinib is a tyrosine kinase inhibitor that is FDA-approved for leukemia and potently inhibits DDR-1. Individuals diagnosed with mild-moderate Alzheimer's disease (AD) treated with nilotinib (versus placebo) for 12 months showed reduction of amyloid plaque and cerebrospinal fluid (CSF) amyloid, and attenuation of hippocampal volume loss. However, the mechanisms are unclear. Here, we explored unbiased next generation whole genome miRNA sequencing from AD patients CSF and miRNAs were matched with their corresponding mRNAs using gene ontology. Changes in CSF miRNAs were confirmed via measurement of CSF DDR1 activity and plasma levels of AD biomarkers. Approximately 1050 miRNAs are detected in the CSF but only 17 miRNAs are specifically altered between baseline and 12-month treatment with nilotinib versus placebo. Treatment with nilotinib significantly reduces collagen and DDR1 gene expression (upregulated in AD brain), in association with inhibition of CSF DDR1. Pro-inflammatory cytokines, including interleukins and chemokines are reduced along with caspase-3 gene expression. Specific genes that indicate vascular fibrosis, e.g., collagen, Transforming Growth Factors (TGFs) and Tissue Inhibitors of Metalloproteases (TIMPs) are altered by DDR1 inhibition with nilotinib. Specific changes in vesicular transport, including the neurotransmitters dopamine and acetylcholine, and autophagy genes, including ATGs, indicate facilitation of autophagic flux and cellular trafficking. Inhibition of DDR1 with nilotinib may be a safe and effective adjunct treatment strategy involving an oral drug that enters the CNS and adequately engages its target. DDR1 inhibition with nilotinib exhibits multi-modal effects not only on amyloid and tau clearance but also on anti-inflammatory markers that may reduce cerebrovascular fibrosis.

Utilizing genetic code expansion to modify N-TIMP2 specificity towards MMP-2, MMP-9, and MMP-14

Matrix metalloproteinases (MMPs) regulate the degradation of extracellular matrix (ECM) components in biological processes. MMP activity is controlled by natural tissue inhibitors of metalloproteinases (TIMPs) that non-selectively inhibit the function of multiple MMPs via interaction with the MMPs' Zn2+-containing catalytic pocket. Recent studies suggest that TIMPs engineered to confer MMP specificity could be exploited for therapeutic purposes, but obtaining specific TIMP-2 inhibitors has proved to be challenging. Here, in an effort to improve MMP specificity, we incorporated the metal-binding non-canonical amino acids (NCAAs), 3,4-dihydroxyphenylalanine (L-DOPA) and (8-hydroxyquinolin-3-yl)alanine (HqAla), into the MMP-inhibitory N-terminal domain of TIMP2 (N-TIMP2) at selected positions that interact with the catalytic Zn2+ ion (S2, S69, A70, L100) or with a structural Ca2+ ion (Y36). Evaluation of the inhibitory potency of the NCAA-containing variants towards MMP-2, MMP-9 and MMP-14 in vitro revealed that most showed a significant loss of inhibitory activity towards MMP-14, but not towards MMP-2 and MMP-9, resulting in increased specificity towards the latter proteases. Substitutions at S69 conferred the best improvement in selectivity for both L-DOPA and HqAla variants. Molecular modeling provided an indication of how MMP-2 and MMP-9 are better able to accommodate the bulky NCAA substituents at the intermolecular interface with N-TIMP2. The models also showed that, rather than coordinating to Zn2+, the NCAA side chains formed stabilizing polar interactions at the intermolecular interface with MMP-2 and MMP-9. Our findings illustrate how incorporation of NCAAs can be used to probe-and possibly exploit-differential tolerance for substitution within closely related protein-protein complexes as a means to improve specificity.

Senescent cells and SASP in cancer microenvironment: New approaches in cancer therapy

Cellular senescence was first described as a state characterized by telomere shortening, resulting in limiting cell proliferation in aging. Apart from this type of senescence, which is called replicative senescence, other senescence types occur after exposure to different stress factors. One of these types of senescence induced after adjuvant therapy (chemotherapy and radiotherapy) is called therapy-induced senescence. The treatment with chemotherapeutics induces cellular senescence in normal and cancer cells in the tumor microenvironment. Thus therapy-induced senescence in the cancer microenvironment is accepted one of the drivers of tumor progression. Recent studies have revealed that senescence-associated secretory phenotype induction has roles in pathological processes such as inducing epithelial-mesenchymal transition and promoting tumor vascularization. Thus senolytic drugs that specifically kill senescent cells and senomorphic drugs that inhibit the secretory activity of senescent cells are seen as a new approach in cancer treatment. Developing and discovering new senotherapeutic agents targeting senescent cells is also gaining importance. In this review, we attempt to summarize the signaling pathways regarding the metabolism, cell morphology, and organelles of the senescent cell. Furthermore, we also reviewed the effects of SASP in the cancer microenvironment and the senotherapeutics that have the potential to be used as adjuvant therapy in cancer treatment.

Polymorphisms and gene expression of metalloproteinases and their inhibitors associated with cerebral ischemic stroke in young patients with sickle cell anemia

BACKGROUND

Sickle cell anemia (SCA) is a genetic disease with great clinical heterogeneity and few viable strategies for treatment; hydroxyurea (HU) is the only widely used drug. Thus, the study of single nucleotide polymorphisms (SNPs) and the gene expression of MMPs 1, 2, 9, 7 and TIMPs 1 and 2, which are involved in the regulation of extracellular matrix, inflammation, and neuropathies, may provide further insights into the pathophysiology of the disease and elucidate biomarkers and molecules as potential therapeutic targets for patients with SCA.

METHODS AND RESULTS

We evaluated 251 young individuals with SCA from northeastern Brazil. The groups were divided according to vaso-occlusive crisis (VOC) and cerebrovascular disease (CVD), compared to control individuals. SNP detection and gene expression assays were performed by real-time PCR, TaqMan system®. Both the expression levels of MMP1 gene, and the SNP MMP1-1607 1G/2G were associated with the risk of cerebral ischemic stroke (IS), and the expression of MMP1 was also associated with a higher frequency of VOC/year. Expression levels of MMP7, TIMP1, and TIMP2 were increased in patients conditioned to IS. The SNP 372T>C (rs4898) TIMP1 T alleles were more frequent in patients with > 5 VOC events/year. The SNP rs17576 of MMP9 showed differences in gene expression levels; it was increased in the genotypes AG, and AG+GG.

CONCLUSION

The findings of this study, the SNPs, and expression provide initial support for understanding the role of MMPs-TIMPs in the pathophysiology of SCA in young patients.

Utilizing genetic code expansion to modify N-TIMP2 specificity towards MMP-2, MMP-9, and MMP-14

Matrix metalloproteinases (MMPs) regulate the degradation of extracellular matrix (ECM) components in biological processes. MMP activity is controlled by natural tissue inhibitors of metalloproteinases (TIMPs) that non-selectively inhibit the function of multiple MMPs via interaction with the MMPs' Zn ²⁺ -containing catalytic pocket. Recent studies suggest that TIMPs engineered to confer MMP specificity could be exploited for therapeutic purposes, but obtaining specific TIMP-2 inhibitors has proved to be challenging. Here, in an effort to improve MMP specificity, we incorporated the metal-binding non-canonical amino acids (NCAAs), 3,4-dihydroxyphenylalanine (L-DOPA) and (8-hydroxyquinolin-3-yl)alanine (HqAla), into the MMP-inhibitory N-terminal domain of TIMP2 (N-TIMP2) at selected positions that interact with the catalytic Zn ²⁺ ion (S2, S69, A70, L100) or with a structural Ca ²⁺ ion (Y36). Evaluation of the inhibitory potency of the NCAA-containing variants towards MMP-2, MMP-9 and MMP-14 in vitro revealed that most showed a significant loss of inhibitory activity towards MMP-14, but not towards MMP-2 and MMP-9, resulting in increased specificity towards the latter proteases. Substitutions at S69 conferred the best improvement in selectivity for both L-DOPA and HqAla variants. Molecular modeling revealed how MMP-2 and MMP-9 are better able to accommodate the bulky NCAA substituents at the intermolecular interface with N-TIMP2. The models also showed that, rather than coordinating to Zn ²⁺ , the NCAA side chains formed stabilizing polar interactions at the intermolecular interface with MMP-2 and MMP-9. The findings illustrate how incorporation of NCAAs can be used to probe and exploit differential tolerance for substitution within closely related protein-protein complexes to achieve improved specificity.

CS12192, a Novel JAK3/JAK1/TBK1 Inhibitor, Synergistically Enhances the Anti-Inflammation Effect of Methotrexate in a Rat Model of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a common disease worldwide and is treated commonly with methotrexate (MTX). CS12192 is a novel JAK3 inhibitor discovered by Chipscreen Biosciences for the treatment of autoimmune diseases. In the present study, we examined the therapeutic effect of CS12192 against RA and explored if the combinational therapy of CS12192 and MTX produced a synergistic effect against RA in rat collagen-induced arthritis (CIA). Arthritis was induced in male Sprague-Dawley rats by two intradermal injections of bovine type II collagen (CII) and treated with MTX, CS12192, or the combination of CS12192 and MTX daily for two weeks. Effects of different treatments on arthritis score, X-ray score, pathology, and expression of inflammatory cytokines and biomarkers were examined. We found that treatment with either CS12192 or MTX produced a comparable therapeutic effect on CIA including: (1) significantly lowering the arthritis score, X-ray score, serum levels of rheumatic factor (RF), C-reactive protein (CRP), and anti-nuclear antibodies (ANA); (2) largely alleviating histopathological damage, reducing infiltration of Th17 cells while promoting Treg cells; (3) inhibiting the expression of inflammatory cytokines and chemokines such as IL-1β, TNF-α, IL-6, CCL2, and CXCL1. All these inhibitory effects were further improved by the combinational therapy with MTX and CS12192. Of importance, the combinational treatment also resulted in a marked switching of the Th17 to Treg and the M1 to M2 immune responses in synovial tissues of CIA. Thus, when compared to the monotherapy, the combination treatment with CS12192 and MTX produces a better therapeutic effect against CIA with a greater suppressive effect on T cells and macrophage-mediated joint inflammation.

Solar radiation leads to increased collagenase gene expression (MMP1) in HERDA (Hereditary equine regional dermal asthenia) affected horses and may explain the typical dorsal distribution of their lesions

BACKGROUND

Hereditary equine regional dermal asthenia (HERDA) is a genetic disease that alters collagen biosynthesis. Affected horses exhibit fragile, hyperextensible skin, especially over the dorsal region. Although ultraviolet (UV) radiation seems to contribute to the regional distribution of lesions and worsening of clinical signs, the molecular mechanisms involved are largely unknown.

OBJECTIVES

To evaluate the effect of solar radiation on matrix metalloproteinase MMP1, MMP8 and MMP13 gene expression in the dorsal and ventral skin of HERDA-affected and HERDA-unaffected horses [wild-type (WT) horses].

ANIMALS

Six HERDA-affected and six unaffected Quarter horses (WT) were paired according to age, sex and coat colour.

MATERIALS AND METHODS

Horses were submitted to 30 day sunlight restriction, followed by 15 day sunlight exposure. Dorsal and ventral skin biopsies were obtained at six sampling times over 45 days. The expression of MMP1, MMP8 and MMP13 genes was measured by quantitative PCR.

RESULTS

Although solar radiation modulated MMP1, MMP8 and MMP13 expression, the effects were more pronounced on MMP1. Sun exposure for three days significantly upregulated MMP1 in the dorsal region when compared to the ventral skin in both unaffected and HERDA-affected horses.

CONCLUSIONS AND CLINICAL RELEVANCE

This study shows that solar irradiation leads to upregulation of skin collagenase genes particularly MMP1 in the dorsal, sun-exposed skin of horses. Furthermore, this was more marked in HERDA-affected horses. The increased activity of collagenases on the disorganised collagen present in HERDA affected horses would explain why UV radiation leads to deterioration of clinical signs in affected individuals.

There and back again: Intracellular trafficking, release and recycling of matrix metalloproteinases

Matrix metalloproteinases are a family of zinc-dependent endopeptidases that are involved in a large variety of proteolytic processes in physiological and pathological scenarios, including immune cell surveillance, tissue homeostasis, or tumor cell metastasis. This is based on their ability to cleave a plethora of substrates that include components of the extracellular matrix, but also cell surface-associated and intracellular proteins. Accordingly, a tight regulatory web has evolved that closely regulates spatiotemporal activity of specific MMPs. An often underappreciated mechanism of MMP regulation involves their trafficking to and from specific subcellular sites that require MMP activity only for a certain period. In this review, we focus on the current knowledge of MMP intracellular trafficking, their secretion or surface exposure, as well as their recycling back from the cell surface. We discuss molecular mechanisms that enable these steps, in particular microtubule-dependent motility of vesicles that is driven by molecular motors and directed by vesicle regulatory proteins. Finally, we also point out open questions in the field of MMP motility that may become important in the future.

Assessment of serum concentrations of matrix metalloproteinase 1, matrix metalloproteinase 2 and tissue inhibitors of metalloproteinases 1 in atopic dermatitis in correlation with disease severity and epidermal barrier parameters

Introduction

Matrix metalloproteinases (MMPs) are a group of proteolytic enzymes, conditioning the integrity of skin cells, however, their role in the inflammatory process of atopic dermatitis (AD) and the direct effect on the epidermal barrier parameters remain unexplained.

Aim

To assess MMP-1, MMP-2, tissue inhibitors of metalloproteinases (TIMP)-1 concentrations in blood serum in the context of transepidermal water loss (TEWL) and stratum corneum hydration in AD. Moreover, serum levels of MMPs and TIMP-1 were analysed in relation to the Eczema Area and Severity Index (EASI).

Material and methods

Forty-three AD patients and 22 control group subjects have been investigated. Serum concentrations of MMP-1, MMP-2, and TIMP-1 have been evaluated with ELISA. TEWL and stratum corneum hydration have been assessed with a TM300 Tewameter and a CM825 Corneometer. Skin lesions in patients with AD have been evaluated with the Eczema Area and Severity Index.

Results

MMP-1 and MMP-2 serum concentrations were significantly higher in the AD group. The results of TIMP-1 serum concentration were similar for both groups. The correlation between the serum concentration and the EASI was demonstrated only for MMP-2 for patients with severe and moderate AD. Patients with AD and TIMP-1 serum concentration greater than MMP-1 presented lower TEWL and higher epidermal hydration.

Conclusions

The results of this study warrant further investigation. The predominance of TIMP-1 over MMP-1 in blood serum can potentially limit TEWL and maintain the proper water content of the epidermis. Future work is necessary to establish how reliable the role of MMP-2 concentration is as an indicator of the severity of AD.

Metalloproteinases in Endometrial Cancer-Are They Worth Measuring?

Endometrial cancer is one of the most common gynecological malignancies, yet the molecular mechanisms that lead to tumor development and progression are still not fully established. Matrix metalloproteinases (MMPs) are a group of enzymes that play an important role in carcinogenesis. They are proteases involved in the degradation of the extracellular matrix (ECM) that surrounds the tumor and the affected tissue allows cell detachment from the primary tumor causing local invasion and metastasis formation. Recent investigations demonstrate significantly increased metalloproteinase and metalloproteinase inhibitor levels in patients with endometrial cancer compared to those with normal endometrium. In this review, we aim to show their clinical significance and possible use in the diagnosis and treatment of patients with endometrial cancer. We have critically summarized and reviewed the research on the role of MMPs in endometrial cancer.

Mechanisms of Lower Extremity Vein Dysfunction in Chronic Venous Disease and Implications in Management of Varicose Veins

Chronic venous disease (CVD) is a common venous disorder of the lower extremities. CVD can be manifested as varicose veins (VVs), with dilated and tortuous veins, dysfunctional valves and venous reflux. If not adequately treated, VVs could progress to chronic venous insufficiency (CVI) and lead to venous leg ulcer (VLU). Predisposing familial and genetic factors have been implicated in CVD. Additional environmental, behavioral and dietary factors including sedentary lifestyle and obesity may also contribute to CVD. Alterations in the mRNA expression, protein levels and proteolytic activity of matrix metalloproteinases (MMPs) have been detected in VVs and VLU. MMP expression/activity can be modulated by venous hydrostatic pressure, hypoxia, tissue metabolites, and inflammation. MMPs in turn increase proteolysis of different protein substrates in the extracellular matrix particularly collagen and elastin, leading to weakening of the vein wall. MMPs could also promote venous dilation by increasing the release of endothelium-derived vasodilators and activating potassium channels, leading to smooth muscle hyperpolarization and relaxation. Depending on VVs severity, management usually includes compression stockings, sclerotherapy and surgical removal. Venotonics have also been promoted to decrease the progression of VVs. Sulodexide has also shown benefits in VLU and CVI, and recent data suggest that it could improve venous smooth muscle contraction. Other lines of treatment including induction of endogenous tissue inhibitors of metalloproteinases (TIMPs) and administration of exogenous synthetic inhibitors of MMPs are being explored, and could provide alternative strategies in the treatment of CVD.

Combined Radiochemotherapy: Metalloproteinases Revisited

Besides cytotoxic DNA damage irradiation of tumor cells triggers multiple intra- and intercellular signaling processes, that are part of a multilayered, treatment-induced stress response at the unicellular and tumor pathophysiological level. These processes are intertwined with intrinsic and acquired resistance mechanisms to the toxic effects of ionizing radiation and thereby co-determine the tumor response to radiotherapy. Proteolysis of structural elements and bioactive signaling moieties represents a major class of posttranslational modifications regulating intra- and intercellular communication. Plasma membrane-located and secreted metalloproteinases comprise a family of metal-, usually zinc-, dependent endopeptidases and sheddases with a broad variety of substrates including components of the extracellular matrix, cyto- and chemokines, growth and pro-angiogenic factors. Thereby, metalloproteinases play an important role in matrix remodeling and auto- and paracrine intercellular communication regulating tumor growth, angiogenesis, immune cell infiltration, tumor cell dissemination, and subsequently the response to cancer treatment. While metalloproteinases have long been identified as promising target structures for anti-cancer agents, previous pharmaceutical approaches mostly failed due to unwanted side effects related to the structural similarities among the multiple family members. Nevertheless, targeting of metalloproteinases still represents an interesting rationale alone and in combination with other treatment modalities. Here, we will give an overview on the role of metalloproteinases in the irradiated tumor microenvironment and discuss the therapeutic potential of using more specific metalloproteinase inhibitors in combination with radiotherapy.

The Pluripotent Activities of Caffeic Acid Phenethyl Ester

Caffeic acid phenethyl ester (CAPE) is a strong antioxidant extracted from honey bee-hive propolis. The mentioned compound, a well-known NF-κB inhibitor, has been used in traditional medicine as a potent anti-inflammatory agent. CAPE has a broad spectrum of biological properties including anti-viral, anti-bacterial, anti-cancer, immunomodulatory, and wound-healing activities. This review characterizes published data about CAPE biological properties and potential therapeutic applications, that can be used in various diseases.

Challenges with matrix metalloproteinase inhibition and future drug discovery avenues

INTRODUCTION

Matrix metalloproteinases have been in the scope of pharmaceutical drug discovery for decades as promising targets for drug development. Until present, no modulator of the enzyme class survived clinical trials, all failing for various reasons. Nevertheless, the target family did not lose its attractiveness and there is ever more evidence that MMP modulators are likely to overcome the hurdles and result in successful clinical therapies.

AREAS COVERED

This review provides an overview of past efforts that were taken in the development of MMP inhibitors and insight into promising strategies that might enable drug discovery in the field in the future. Small molecule inhibitors as well as biomolecules are reviewed.

EXPERT OPINION

Despite the lack of successful clinical trials in the past, there is ongoing research in the field of MMP modulation, proving the target class has not lost its appeal to pharmaceutical research. With ever-growing insights from different scientific fields that shed light on previously unknown correlations, it is now time to use synergies deriving from biological knowledge, chemical structure generation, and clinical application to reach the ultimate goal of bringing MMP derived drugs on a broad front for the benefit of patients into therapeutic use.

Protective Effects of Phellinus linteus Mycelium on the Development of Osteoarthritis after Monosodium Iodoacetate Injection

Objective

The aim of this study was to identify the protective effects of Phellinus linteus mycelium (PLM) and its possible mechanisms in a model of monosodium iodoacetate- (MIA-) induced osteoarthritis (OA).

Methods

Intra-articular injection of MIA was injected to 50 μL with 80 mg/mL using a 0.3 mL insulin syringe into the right knee joint. Changes in hindpaw weight-bearing distribution between the right (osteoarthritic) and left (contralateral control) legs were used as an index of joint discomfort. PLM (50, 100, and 200 mg/kg body weight) was orally administered once daily for 14 days from day 7 after MIA treatment. And then, various factors associated with inflammatory response and cartilage degeneration in cartilage tissues detected by western blotting.

Results

PLM treatment showed a concentration-dependent elevation in change in hindpaw weight-bearing distribution (HWBD). PLM200 demonstrated the capacity to significantly increase HWBD, indicating that the change in weight-bearing distribution means the reduction of spontaneous pain. Our results indicate that PLM suppressed the inflammatory factors via NF-κB signaling pathway induced by p38 phosporlyation. Moreover, PLM200 exhibited a significant reduction of ROS produced by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. PLM100 and PLM200 inhibited the levels of matrix metalloproteinase (MMP)-1, one of proteinase that degrades extracellular matrix (ECM).

Conclusions

Taken together, our results indicated that PLM has a strong chondroprotective effect through the suppression both ROS production and inflammation.

Collagen Hydrolysates for Skin Protection: Oral Administration and Topical Formulation

Antioxidants are molecules that delay or inhibit the oxidation of other molecules. Its use significantly increased in recent years in the diet of people. Natural antioxidants are replacing the use of synthetic antioxidant ingredients due to their safety, nutritional, and therapeutic values. Hydrolyzed collagen (HC) is a popular ingredient considered to be an antioxidant. This low molecular weight protein has been widely utilized due to its excellent biocompatibility, easy biodegradability, and weak antigenicity. It is a safe cosmetic biomaterial with good moisturizing properties on the skin. The antioxidant properties of HC are conditioned to the size of the molecule: the lower the molecular weight of peptides, the greater the ability to donate an electron or hydrogen to stabilize radicals. The antioxidant capacity of HC is mostly due to the presence of hydrophobic amino acids in the peptide. The exact mechanism of peptides acting as antioxidants is not clearly known but some aromatic amino acids and histidine are reported to play an important role in the antioxidant activity. Oral ingestion of HC increases the levels of collagen-derived peptides in the blood torrent and improves the skin properties such as elasticity, skin moisture, and transepidermal water loss. Additionally, daily intakes of HC protect the skin against UV melasma, enhances the fibroblast production and extracellular matrix of the skin. HC has been identified as a safe cosmetic ingredient for topical formulations with good moisturizing properties at the stratum corneum layer of the skin. It reduces the effects of skin aging (dryness, laxity, and wrinkles). The use of HC as a principal ingredient in safe formulations for skin protection was reviewed and compared when it is used by topical and/or oral administration.

Regulation of matrix metalloproteinases 2 and 9 in corneal neovascularization

Corneal neovascularization (CNV), a pathological process of angiogenesis, can lead to serious consequences in the cornea. CNV is generally proved to associate with inflammation in the cornea closely, which is mainly elicited by the disruption of equilibrium between angiogenic and antiangiogenic factors. Angiogenic factors including vascular endothelial growth factors (VEGFs), basic fibroblast growth factors (bFGFs), and matrix metalloproteinases (MMPs) are vital factors in the formation of CNV. Especially VEGFs are convinced to be the core angiogenic factors in CNV, and MMPs are proved to exert dual effects on the process. Strikingly, matrix metalloproteinase 2 (MMP-2) and matrix metalloproteinase 9 (MMP-9) are determined to play key roles in the formation of CNV, while the mechanism is still vague. In this review, the latest researches are reviewed to discuss the role of MMP-2 and MMP-9 in CNV, respectively, and some inhibitors of them are presented. We hope to provide a new direction of drug research for CNV.

Tissue inhibitor of matrix metalloproteinase-3 has both anti-metastatic and anti-tumourigenic properties

TIMP-3 is one of four tissue inhibitors of matrix metalloproteinases, the endogenous inhibitors of the matrix metalloproteinase enzymes. These enzymes have an important role in metastasis, in the invasion of cancer cells through the basement membrane and extracellular matrix. TIMP-1, -2 and -4 both promote and inhibit tumour development, in a context-dependent manner, however TIMP-3 is consistently anti-tumourigenic. TIMP-3 is also the only insoluble member of the family, being either bound to the extracellular matrix or the low density lipoprotein-related protein-1, through which it can be endocytosed. Levels of TIMP-3 have also been shown to be regulated by micro RNAs and promoter hypermethylation, resulting in frequent silencing in many tumour types, to the extent that its expression has been suggested as a prognostic marker in some tumours, being associated with lower levels of metastasis, or better response to treatment. TIMP-3 has been shown to have anti-metastatic effects, both through inhibition of matrix metalloproteinases and ADAM family members and downregulation of angiogenesis. This occurs via interactions with receptors including VEGF, via modulation of signaling pathways and due to protease inhibition. TIMP-3 has also been shown to reduce tumour growth rate, most often by inducing apoptosis by stabilisation of death receptors. A number of successful mechanisms of delivery of TIMP-3 to tumour or inflammatory sites have been investigated in vitro or in animal studies. It may therefore be worthwhile further exploring the use of TIMP-3 as a potential anti-metastatic or anti-tumorigenic therapy for many tumour types.

Tissue inhibitor of metalloproteinase proteins inhibit teratoma growth in mice transplanted with pluripotent stem cells

Pluripotent stem cells (PSCs) can serve as an unlimited cell source for transplantation therapies for treating various devastating diseases, such as cardiovascular diseases, diabetes, and Parkinson's disease. However, PSC transplantation has some associated risks, including teratoma formation from the remaining undifferentiated PSCs. Thus, for successful clinical application, it is essential to ablate the proliferative PSCs before or after transplantation. In this study, neural stem cell-derived conditioned medium (NSC-CM) inhibited the proliferation of PSCs and PSC-derived neural precursor (NP) cells without influencing the potential of PSC-NP cells to differentiate into neurons in vitro and prevented teratoma growth in vivo. Moreover, we found that the NSC-CM remarkably decreased the expression levels of Oct4 and cyclin D1 that Oct4 directly binds to and increased the cleaved-caspase 3-positive cell death through the DNA damage response in PSCs and PSC-NPs. Interestingly, we found that NSCs distinctly secreted the tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 proteins. These proteins suppressed not only the proliferation of PSCs in cell culture but also teratoma growth in mice transplanted with PSCs through inhibition of matrix metalloproteinase (MMP)-2 and MMP-9 activity. Taken together, these results suggest that the TIMP proteins may improve the efficacy and safety of the PSC-based transplantation therapy.

Kangfuxin Oral Liquid Attenuates Bleomycin-Induced Pulmonary Fibrosis via the TGF-β1/Smad Pathway

Idiopathic pulmonary fibrosis (IPF) is a fatal respiratory disease with a poor prognosis characterized by transforming growth factor (TGF)-β-induced proliferation, migration, and differentiation of fibroblasts, resulting in excessive extracellular matrix (ECM) deposition. Whether Kangfuxin oral liquid (KFXOL) has a protective function in pulmonary fibrosis is largely unknown. The goal of this study was to investigate the potential efficacy of KFXOL, as well as the underlying mechanism by which KFXOL regulates pulmonary fibrosis in vivo and in vitro. We found that KFXOL dramatically attenuated intratracheal bleomycin (BLM)-induced pulmonary fibrosis in terms of both severe alveolar architecture destruction and collagen deposition. KFXOL treatment significantly inhibited the proliferation, migration, and differentiation of pulmonary fibroblasts following activation using BLM/TGF-β1 and normalized the expression of ECM deposition-related proteins, including matrix metalloproteinase (MMP)-1, MMP-9, and tissue inhibitor of metalloproteinases 1. These effects were mediated via the inhibition of TGF-β1 and phosphorylated Smad2/3 activation in vivo. Taken together, our data suggest that KFXOL attenuates the development of pulmonary fibrosis via the TGF-β1/Smad signaling pathway and thus has potential utility in the treatment of pulmonary fibrosis.

Neural stem cells and the secreted proteins TIMPs ameliorate UVB-induced skin photodamage

UV-induced skin damage is involved in ROS overproduction and the overexpression of matrix metalloproteinases (MMPs), which are inhibited by TIMPs (tissue inhibitor of neural stem cells (NSCs)). These proteins may be associated with skin regeneration through the activation of TIMP proteins, but there have been no reports of treatment of skin photodamage using NSCs and their secreted proteins TIMP-1 and TIMP-2. Here we investigated the photoprotective role of NSCs and their TIMP proteins for the inhibition of UVB-irradiation damage in fibroblasts in SKH-1 mice. SKH-1 hairless mice were divided into three groups (n = 4 per group): normal, treatment, and control groups. The latter two groups were dorsally exposed to UVB irradiation for 12 weeks. After UVB irradiation, treatments with NSC-CM and its secreted factors TIMP-1 and TIMP-2, markedly ameliorated the photodamage triggered by the increase in MMP expression and activity through ROS production, and the subsequent activation of the NF-κB pathway in UVB-irradiated fibroblasts and the treatment mouse group. In addition, the topical application of NSC-CM to mice in the treatment group after irradiation clearly inhibited the expression of γ-H2AX, a DNA damage marker, through the activation of the DNA repair enzyme Rad50. These results demonstrate that NSC-CM or TIMPs proteins can ameliorate skin photodamage induced by UVB-irradiation in in vitro and in vivo systems.

Inhibitory Antibodies Designed for Matrix Metalloproteinase Modulation

The family of matrix metalloproteinases (MMPs) consists of a set of biological targets that are involved in a multitude of severe pathogenic events such as different forms of cancers or arthritis. Modulation of the target class with small molecule drugs has not led to the anticipated success until present, as all clinical trials failed due to unacceptable side effects or a lack of therapeutic outcome. Monoclonal antibodies offer a tremendous therapeutic potential given their high target selectivity and good pharmacokinetic profiles. For the treatment of a variety of diseases there are already antibody therapies available and the number is increasing. Recently, several antibodies were developed for the selective inhibition of single MMPs that showed high potency and were therefore investigated in in vivo studies with promising results. In this review, we highlight the progress that has been achieved toward the design of inhibitory antibodies that successfully modulate MMP-9 and MMP-14.

Design, cyclization, and optimization of MMP13-TIMP1 interaction-derived self-inhibitory peptides against chondrocyte senescence in osteoarthritis

The matrix metallopeptidase 13 (MMP13) is a central regulator of chondrocyte senescence that contributes to the development and progression of osteoarthritis (OA). In the present study, the native inhibitory structure of MMP13 in complex with its natural cognate inhibitor, the tissue inhibitor of metalloproteinases 1 (TIMP1), was modeled at atomic level using a grafting-based structural bioinformatics method with existing crystal structures. The modeled complex structure was then examined in detail, from which a TIMP1 inhibitory site that directly inserts into the active site of MMP13 enzyme was identified. The inhibitory site contains a coiled inhibitory loop (ILP) and a stretched N-terminal tail (NTT); they are highly structured in the intact MMP13-TIMP1 complex interface, but exhibit a large flexibility and intrinsic disorder when split from the interface context. In vitro binding assays demonstrated that the isolated ILP and NTT peptides cannot effectively rebind at the MMP13 active site (K_d > ~100 μM or = n.d.), although they have all key interacting residues in the enzyme inhibition. In silico simulations revealed that splitting of the peptide segments from TIMP1 inhibitory site does not influence the direct intermolecular interaction between MMP13 and the peptides substantially; instead, the large conformational flexibility of these isolated peptides in absence of interface context is primarily responsible for the affinity impairment, which would incur a considerable entropy penalty upon the peptide binding to MMP13. An extended version of ILP peptide, namely eILP (⁶³TPAMESVCGY⁷²), was redesigned with a rational strategy to derive a number of its cyclized counterparts by introducing a disulfide bridge across the peptide two-termini; the redesign reduces the peptide flexibility in free state and constrains the peptide pre-folding to a native-like conformation, which would help the peptide binding with minimized entropy penalty. Binding assays substantiated that the affinity K_d values of four designed cyclic peptides (, , and ) were improved to 23, 67, 42 and 18 μM, respectively, from the 96 μM of linear eILP peptide.

UV-induced DNA methyltransferase 1 promotes hypermethylation of tissue inhibitor of metalloproteinase 2 in the human skin

BACKGROUND

Ultraviolet (UV) radiation has been reported to influence epigenetic regulation by affecting the expression of genome regulators such as DNA methyltransferase 1 (DNMT1). DNMT1 is a "gene silencer," that is responsible for the maintenance of DNA methylation and contribution to de novo methylation. Implications of DNMT1's involvement in the expression of UV-induced proteins have been previously reported.

OBJECTIVE

To investigate for changes in DNA methylation-associated gene expressions by UV and to analyze the role of DNA methylation in the suppression of TIMP2 in UV-irradiated human skin.

METHODS

The expression of DNA methylation-associated proteins and TIMP2 were analyzed in UV-irradiated human skin in vivo and in human dermal fibroblasts in vitro. To investigate the relationship between DNMT1 and TIMP2, we assessed the effect of DNMT1 knockdown, inhibition and overexpression on TIMP2 levels in human dermal fibroblasts. Lastly, methylation-specific PCR was used to confirm increased DNA methylation in TIMP2 promoter in response to UV.

RESULTS

DNMT1 expression significantly increased whereas TIMP2 expression decreased in UV-irradiated human skin in vivo and in vitro. Downregulation of DNMT1 by knockdown or inhibition resulted in increased TIMP2 expression, whereas the overexpression of DNMT1 resulted in decreased TIMP2 expression. Lastly, methylation-specific PCR confirmed increased methylation on the CpG island residing in TIMP2 promoter in UV-irradiated human dermal fibroblasts.

CONCLUSION

These findings suggest that UV-induced expression of DNMT1 may be responsible for mediating DNA hypermethylation in TIMP2, and thus, silencing its expression, in UV-exposed human skin.

Degradation pattern of a porcine collagen membrane in an in vivo model of guided bone regeneration

BACKGROUND AND OBJECTIVE

Although collagen membranes have been clinically applied for guided tissue/bone regeneration for more than 30 years, their in vivo degradation pattern has never been fully clarified. A better understanding of the different stages of in vivo degradation of collagen membranes is extremely important, considering that the biology of bone regeneration requires the presence of a stable and cell/tissue-occlusive barrier during the healing stages in order to ensure a predictable result. Therefore, the aim of this study was to investigate the degradation pattern of a porcine non-cross-linked collagen membrane in an in vivo model of guided bone regeneration (GBR).

MATERIAL AND METHODS

Decalcified and paraffin-embedded specimens from calvarial defects of 18, 10-month-old Wistar rats were used. The defects were treated with a double layer of collagen membrane and a deproteinized bovine bone mineral particulate graft. At 7, 14 and 30 days of healing, qualitative evaluation with scanning electron microscopy and atomic force microscopy, and histomorphometric measurements were performed. Markers of collagenase activity and bone formation were investigated using an immunofluorescence technique.

RESULTS

A significant reduction of membrane thickness was observed from 7 to 30 days of healing, which was associated with progressive loss of collagen alignment, increased collagen remodeling and progressive invasion of woven bone inside the membranes. A limited inflammatory infiltrate was observed at all time points of healing.

CONCLUSION

The collagen membrane investigated was biocompatible and able to promote bone regeneration. However, pronounced signs of degradation were observed starting from day 30. Since successful regeneration is obtained only when cell occlusion and space maintenance exist for the healing time needed by the bone progenitor cells to repopulate the defect, the suitability of collagen membranes in cases where long-lasting barriers are needed needs to be further reviewed.

Unbiased analysis of senescence associated secretory phenotype (SASP) to identify common components following different genotoxic stresses

Senescent cells secrete senescence-associated secretory phenotype (SASP) proteins to carry out several functions, such as sensitizing surrounding cells to senesce; immunomodulation; impairing or fostering cancer growth; and promoting tissue development. Identifying secreted factors that achieve such tasks is a challenging issue since the profile of secreted proteins depends on genotoxic stress and cell type. Currently, researchers are trying to identify common markers for SASP. The present investigation compared the secretome composition of five different senescent phenotypes in two different cell types: bone marrow and adipose mesenchymal stromal cells (MSC). We induced MSC senescence by oxidative stress, doxorubicin treatment, X-ray irradiation, and replicative exhaustion. We took advantage of LC-MS/MS proteome identification and subsequent gene ontology (GO) evaluation to perform an unbiased analysis (hypothesis free manner) of senescent secretomes. GO analysis allowed us to distribute SASP components into four classes: extracellular matrix/cytoskeleton/cell junctions; metabolic processes; ox-redox factors; and regulators of gene expression.

We used Ingenuity Pathway Analysis (IPA) to determine common pathways among the different senescent phenotypes. This investigation, along with identification of eleven proteins that were exclusively expressed in all the analyzed senescent phenotypes, permitted the identification of three key signaling paths: MMP2 - TIMP2; IGFBP3 - PAI-1; and Peroxiredoxin 6 - ERP46 - PARK7 - Cathepsin D - Major vault protein. We suggest that these paths could be involved in the paracrine circuit that induces senescence in neighboring cells and may confer apoptosis resistance to senescent cells.

Structural modeling of osteoarthritis ADAMTS4 complex with its cognate inhibitory protein TIMP3 and rational derivation of cyclic peptide inhibitors from the complex interface to target ADAMTS4

The ADAMTS4 (a disintegrin and metalloproteinase with thrombospondin motifs 4) enzyme is a matrix-associated zinc metalloendopeptidase that plays an essential role in the degradation of cartilage aggrecan in arthritic diseases and has been recognized as one of the most primary targets for therapeutic intervention in osteoarthritis (OA). Here, we reported computational modeling of the atomic-level complex structure of ADAMTS4 with its cognate inhibitory protein TIMP3 based on high-resolution crystal template. By systematically examining the modeled complex structure we successfully identified a short inhibitory loop (⁶²EASESLC⁶⁸) in TIMP3 N-terminal inhibitory domain (NID) that directly participates in blocking the enzyme's active site, which, and its extended versions, were then broken from the full-length protein to serve as the peptide inhibitor candidates of ADAMTS4. Atomistic molecular dynamics simulation, binding energetic analysis, and fluorescence-based assay revealed that the TIMP3-derived linear peptides can only bind weakly to the enzyme (K_d = 74 ± 8 μM), which would incur a considerable entropy penalty due to the high conformational flexibility and intrinsic disorder of these linear peptides. In this respect, we proposed a cyclization strategy to improve enzyme-peptide binding affinity by, instead of traditionally maximizing enthalpy contribution, minimizing entropy cost of the binding, where a disulfide bond was added across the two terminal residues of linear peptides, resulting in a number of TIMP3-derived cyclic peptides. Our studies confirmed that the cyclization, as might be expected, can promote peptide binding capability against ADAMTS4 substantially, with affinity increase by 3-fold, 9-fold and 7-fold for cyclic peptides , and , respectively.

Matrix Metalloproteinases, Vascular Remodeling, and Vascular Disease

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that degrade 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 through removal of the propeptide domain from their latent zymogen form. MMPs are often secreted in an inactive proMMP form, which is cleaved to the active form by various proteinases including other MMPs. MMPs degrade various protein substrates in ECM including collagen and elastin. MMPs could also influence endothelial cell function as well as VSM cell migration, proliferation, Ca²⁺ signaling, and contraction. MMPs play a role in vascular tissue remodeling during various biological processes such as angiogenesis, embryogenesis, morphogenesis, and wound repair. Alterations in specific MMPs could influence arterial remodeling and lead to various pathological disorders such as hypertension, preeclampsia, atherosclerosis, aneurysm formation, as well as excessive venous dilation and lower extremity venous disease. MMPs are often 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 may serve as biomarkers and potential therapeutic targets for certain vascular disorders.

Decreased homodimerization and increased TIMP-1 complexation of uteroplacental and uterine arterial matrix metalloproteinase-9 during hypertension-in-pregnancy

Preeclampsia is a complication of pregnancy manifested as hypertension-in-pregnancy (HTN-Preg) and often intrauterine growth restriction (IUGR). Placental ischemia could be an initiating event, but the molecular mechanisms are unclear. To test the hypothesis that dimerization of matrix metalloproteinases (MMPs) plays a role in HTN-Preg and IUGR, the levels/activity of MMP-9, tissue inhibitor of metalloproteinase (TIMP-1), and their dimerization forms were measured in the placenta, uterus, and uterine artery of normal pregnant (Preg) rats and a rat model of reduced uteroplacental perfusion pressure (RUPP). Consistent with our previous report, blood pressure (BP) was higher, pup weight was lower, and gelatin zymography showed different gelatinolytic activity for pro-MMP-9, MMP-9, pro-MMP-2 and MMP-2 in RUPP vs Preg rats. Careful examination of the zymograms showed additional bands at 200 and 135kDa. Western blots with MMP-9 antibody suggested that the 200kDa band was a MMP-9 homodimer. Western blots with TIMP-1 antibody as well as reverse zymography suggested that the 135kDa band was a MMP-9/TIMP-1 complex. The protein levels and gelatinase activity of MMP-9 homodimer were decreased while MMP-9/TIMP-1 complex was increased in placenta, uterus and uterine artery of RUPP vs Preg rats. The epidermal growth factor (EGF) receptor blocker erlotinib and protein kinase C (PKC) inhibitor bisindolylmaleimide decreased MMP-9 homodimer and increased MMP-9/TIMP-1 complex in placenta, uterus and uterine artery of Preg rats. EGF and the PKC activator phorbol-12,13-dibutyrate (PDBu) reversed the decreases in MMP-9 homodimer and the increases in MMP-9/TIMP-1 complex in tissues of RUPP rats. Thus, the increased BP and decreased pup weight in placental ischemia model of HTN-Preg are associated with a decrease in MMP-9 homodimer and an increase in MMP-9/TIMP-1 complex in placenta, uterus, and uterine artery, which together would cause a net decrease in MMP-9 activity and reduce uteroplacental and vascular remodeling in the setting of HTN-Preg and IUGR. Enhancing EGFR/PKC signaling may reverse the MMP-9 unfavorable dimerization patterns and thereby promote uteroplacental and vascular remodeling in preeclampsia.

Matrix Metalloproteinase Inhibitors as Investigational and Therapeutic Tools in Unrestrained Tissue Remodeling and Pathological Disorders

Matrix metalloproteinases (MMPs) are zinc-dependent proteolytic enzymes that degrade various proteins in the extracellular matrix (ECM). MMPs may also regulate the activity of membrane receptors and postreceptor signaling mechanisms and thereby affect cell function. The MMP family includes collagenases, gelatinases, stromelysins, matrilysins, membrane-type MMPs, and other MMPs. Inactive proMMPs are cleaved by other MMPs or proteases into active MMPs, which interact with various protein substrates in ECM and cell surface. MMPs regulate important biological processes such as vascular remodeling and angiogenesis and may be involved in the pathogenesis of cardiovascular disorders such as hypertension, atherosclerosis, and aneurysm. The role of MMPs is often assessed by measuring their mRNA expression, protein levels, and proteolytic activity using gel zymography. MMP inhibitors are also used to assess the role of MMPs in different biological processes and pathological conditions. MMP activity is regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs), and the MMP/TIMP balance could determine the net MMP activity, ECM turnover, and tissue remodeling. Also, several synthetic MMP inhibitors have been developed. Synthetic MMP inhibitors include a large number of zinc-binding globulins (ZBGs), in addition to non-ZBGs and mechanism-based inhibitors. MMP inhibitors have been proposed as potential tools in the management of osteoarthritis, cancer, and cardiovascular disorders. However, most MMP inhibitors have broad-spectrum actions on multiple MMPs and could cause undesirable musculoskeletal side effects. Currently, doxycycline is the only MMP inhibitor approved by the Food and Drug Administration. New generation biological and synthetic MMP inhibitors may show greater MMP specificity and fewer side effects and could be useful in targeting specific MMPs, reducing unrestrained tissue remodeling, and the management of MMP-related pathological disorders.

Evaluation of the Size-Dependent Cytotoxicity of DLC (Diamondlike Carbon) Wear Debris in Arthroplasty Applications

Patients with DLC (diamond like carbon)-coated artificial joints may be exposed to a wide size range of DLC wear debris (DW). In this study, the cytotoxicity of DW of different size ranges (0-0.22, 0.22-0.65, 0.65-1.0, and 1.0-5.0 μm) was evaluated. The microstructure and physical characteristics of DW were investigated by Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscope (SEM), and dynamic light scattering (DLS). Macrophages, osteoblasts, and fibroblasts were incubated with DW of different size ranges respectively followed by cytotoxicity evaluations of inflammatory cytokines, alkaline phosphatase (ALP) assays, and related signal protein expression analysis. The results showed that, except for the size range of 0-0.22 μm, DW cytotoxicity showed a size-dependent (0.22-5.0 μm) decrease with increasing size. Within the range of 0.22-5.0 μm, DW of larger size resulted in lessened inflammatory response and enhanced osteoblastogenesis and fibrogenesis, with increased viability of cells (macrophages, osteoblasts, and fibroblasts), better morphology, less release of pro-inflammatory factors and more release of anti-inflammatory factors. The results demonstrated that DW sizes below 0.22 μm had less negative effects on cell adhesion and growth because of the BSA (bovine serum albumin) encapsulation effect. These findings provide valuable knowledge about the comprehensive mechanism of promotion of inflammatory response and inhibition of osteoblastogenesis and fibrogenesis induced by DW. In conclusion, an effective system of biocompatibility evaluation for different sizes of DW was derived.

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.

Matrix Metalloproteinases in Remodeling of Lower Extremity Veins and Chronic Venous Disease

The veins of the lower extremity are equipped with efficient wall, contractile vascular smooth muscle (VSM), and competent valves in order to withstand the high venous hydrostatic pressure in the lower limb and allow unidirectional movement of deoxygenated blood toward the heart. The vein wall structure and function are in part regulated by matrix metalloproteinases (MMPs). MMPs are zinc-dependent endopeptidases that are secreted as inactive pro-MMPs by different cells in the venous wall including fibroblasts, VSM, and leukocytes. Pro-MMPs are activated by other MMPs, proteinases, and other endogenous and exogenous activators. MMPs degrade various extracellular matrix (ECM) proteins including collagen and elastin, and could affect other cellular processes including endothelium-mediated dilation, VSM cell migration, and proliferation as well as modulation of Ca²⁺ signaling and contraction in VSM. It is thought that increased lower limb venous hydrostatic pressure increases hypoxia-inducible factors and other MMP inducers such as extracellular matrix metalloproteinase inducer, leading to increased MMP expression/activity, ECM protein degradation, vein wall relaxation, and venous dilation. Vein wall inflammation and leukocyte infiltration cause additional increases in MMPs, and further vein wall dilation and valve degradation, that could lead to chronic venous disease and varicose veins (VVs). VVs are often presented as vein wall dilation and tortuosity, incompetent venous valves, and venous reflux. Different regions of VVs show different MMP levels and ECM proteins with atrophic regions showing high MMP levels/activity and little ECM compared to hypertrophic regions with little or inactive MMPs and abundant ECM. Treatment of VVs includes compression stockings, venotonics, sclerotherapy, or surgical removal. However, these approaches do not treat the cause of VVs, and other lines of treatment may be needed. Modulation of endogenous tissue inhibitors of metalloproteinases (TIMPs), and exogenous synthetic MMP inhibitors may provide new approaches in the management of VVs.

TIMPs: versatile extracellular regulators in cancer

A compelling long-term goal of cancer biology is to understand the crucial players during tumorigenesis in order to develop new interventions. Here, we review how the four non-redundant tissue inhibitors of metalloproteinases (TIMPs) regulate the pericellular proteolysis of a vast range of matrix and cell surface proteins, generating simultaneous effects on tumour architecture and cell signalling. Experimental studies demonstrate the contribution of TIMPs to the majority of cancer hallmarks, and human cancers invariably show TIMP deregulation in the tumour or stroma. Of the four TIMPs, TIMP1 overexpression or TIMP3 silencing is consistently associated with cancer progression or poor patient prognosis. Future efforts will align mouse model systems with changes in TIMPs in patients, will delineate protease-independent TIMP function, will pinpoint therapeutic targets within the TIMP-metalloproteinase-substrate network and will use TIMPs in liquid biopsy samples as biomarkers for cancer prognosis.

Zymography as a Research Tool in the Study of Matrix Metalloproteinase Inhibitors

Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade various components of the extracellular matrix (ECM) and play a role in tissue remodeling. Changes in MMPs have been observed in cancer, connective tissue disorders, and vascular disease, and both endogenous tissue inhibitors of MMPs (TIMPs) and synthetic MMP inhibitors (MMPIs) have been evaluated as modulators of MMP activity in various biological systems. Zymography is a simple technique that is commonly used to assess MMP activity and the efficacy of MMPIs. Also, reverse zymography is a modified technique to study the activity of endogenous TIMPs. However, problems are often encountered during the zymography procedure, which could interfere with accurate assessment of MMP activity in control specimens, and thus make it difficult to determine the pathological changes in MMPs and their responsiveness to MMPIs. Simplified protocols for preparation of experimental solutions, tissue preparation, regular and reverse zymography procedures, and zymogram analysis are presented. Additional helpful tips to troubleshoot problems in the zymography technique and to enhance the quality of the zymograms should make it more feasible to determine the changes in MMPs and assess the efficacy of MMPIs in modulating MMP activity in various biological systems and pathological conditions.

Novel Role for Matrix Metalloproteinase 9 in Modulation of Cholesterol Metabolism

Background

The development of atherosclerosis is strongly linked to disorders of cholesterol metabolism. Matrix metalloproteinases (MMPs) are dysregulated in patients and animal models with atherosclerosis. Whether systemic MMP activity influences cholesterol metabolism is unknown.

Methods and Results

We examined MMP‐9–deficient (Mmp9^−/−) mice and found them to have abnormal lipid gene transcriptional responses to dietary cholesterol supplementation. As opposed to Mmp9^+/+ (wild‐type) mice, Mmp9^−/− mice failed to decrease the hepatic expression of sterol regulatory element binding protein 2 pathway genes, which control hepatic cholesterol biosynthesis and uptake. Furthermore, Mmp9^−/− mice failed to increase the expression of genes encoding the rate‐limiting enzymes in biliary cholesterol excretion (eg, Cyp7a and Cyp27a). In contrast, MMP‐9 deficiency did not impair intestinal cholesterol absorption, as shown by the ¹⁴C‐cholesterol and ³H‐sitostanol absorption assay. Similar to our earlier study on Mmp2^−/− mice, we observed that Mmp9^−/− mice had elevated plasma secreted phospholipase A₂ activity. Pharmacological inhibition of systemic circulating secreted phospholipase A₂ activity (with varespladib) partially normalized the hepatic transcriptional responses to dietary cholesterol in Mmp9^−/− mice. Functional studies with mice deficient in other MMPs suggested an important role for the MMP system, as a whole, in modulation of cholesterol metabolism.

Conclusions

Our results show that MMP‐9 modulates cholesterol metabolism, at least in part, through a novel MMP‐9–plasma secreted phospholipase A₂ axis that affects the hepatic transcriptional responses to dietary cholesterol. Furthermore, the data suggest that dysregulation of the MMP system can result in metabolic disorder, which could lead to atherosclerosis and coronary heart disease.

Depletion of Neutrophils Promotes the Resolution of Pulmonary Inflammation and Fibrosis in Mice Infected with Paracoccidioides brasiliensis

Chronic stages of paracoccidioidomycosis (PCM) are characterized by granulomatous lesions which promote the development of pulmonary fibrosis leading to the loss of respiratory function in 50% of patients; in addition, it has been observed that neutrophils predominate during these chronic stages of P. brasiliensis infection. The goal of this study was to evaluate the role of the neutrophil during the chronic stages of experimental pulmonary PCM and during the fibrosis development and tissue repair using a monoclonal specific to this phagocytic cell. Male BALB/c mice were inoculated intranasally with 1.5x106 P. brasiliensis yeast cells. A monoclonal antibody specific to neutrophils was administered at 4 weeks post-inoculation followed by doses every 48h during two weeks. Mice were sacrificed at 8 and 12 weeks post-inoculation to assess cellularity, fungal load, cytokine/chemokine levels, histopathological analysis, collagen and expression of genes related to fibrosis development. Depletion of neutrophils was associated with a significant decrease in the number of eosinophils, dendritic cells, B cells, CD4-T cells, MDSCs and Treg cells, fungal load and levels of most of the pro-inflammatory cytokines/chemokines evaluated, including IL-17, TNF-α and TGF-β1. Recovery of lung architecture was also associated with reduced levels of collagen, high expression of TGF-β3, matrix metalloproteinase (MMP)-12 and -14, and decreased expression of tissue inhibitor metalloproteinase (TIMP)-2, and MMP-8. Depletion of neutrophils might attenuate lung fibrosis and inflammation through down-regulating TGF-β1, TNF-α, IL-17, MMP-8 and TIMP-2. These results suggest that neutrophil could be considered as a therapeutic target in pulmonary fibrosis induced by P. brasiliensis.

Endogenous Neuroprotective Molecules and Their Mechanisms in the Central Nervous System

Functions of the central nervous system (CNS) are based on a complex neural network. It is believed that the CNS has several neuroprotective mechanisms operated by neurons, glia and other types of cells against various types of neuronal damage. Since mature, differentiated neurons are not able to divide, it is important to protect neurons from damage prior to death. The neuroprotective effects of a number of pharmaceutical agents and natural products against necrosis and apoptosis of the CNS neurons have been reported, thus this review will mainly discuss several endogenous neuroprotectants and their mechanisms.

Matrix metalloproteinases as candidate biomarkers in adults with congenital heart disease

Context Matrix metalloproteinases (MMPs) are associated with diastolic dysfunction and heart failure in acquired heart disease. Objective To investigate the role of MMPs as novel biomarkers in clinically stable adults with congenital heart disease. Methods We measured serum MMP-2, -3, -9 and tissue inhibitor of matrix metalloproteinase-1 in 425 patients and analysed the association with cardiac function and exercise capacity. Results MMP-2 was significantly associated with exercise capacity, ventilatory efficiency and left ventricular deceleration time, independently of age, sex, body surface area and NT-proBNP. Conclusion MMP-2 may provide new information in the clinical evaluation of adults with congenital heart disease.

Loss of Endothelial Barrier in Marfan Mice (mgR/mgR) Results in Severe Inflammation after Adenoviral Gene Therapy

Objectives

Marfan syndrome is an autosomal dominant inherited disorder of connective tissue. The vascular complications of Marfan syndrome have the biggest impact on life expectancy. The aorta of Marfan patients reveals degradation of elastin layers caused by increased proteolytic activity of matrix metalloproteinases (MMPs). In this study we performed adenoviral gene transfer of human tissue inhibitor of matrix metalloproteinases-1 (hTIMP-1) in aortic grafts of fibrillin-1 deficient Marfan mice (mgR/mgR) in order to reduce elastolysis.

Methods

We performed heterotopic infrarenal transplantation of the thoracic aorta in female mice (n = 7 per group). Before implantation, mgR/mgR and wild-type aortas (WT, C57BL/6) were transduced ex vivo with an adenoviral vector coding for human TIMP-1 (Ad.hTIMP-1) or β-galactosidase (Ad.β-Gal). As control mgR/mgR and wild-type aortas received no gene therapy. Thirty days after surgery, overexpression of the transgene was assessed by immunohistochemistry (IHC) and collagen in situ zymography. Histologic staining was performed to investigate inflammation, the neointimal index (NI), and elastin breaks. Endothelial barrier function of native not virus-exposed aortas was evaluated by perfusion of fluorescent albumin and examinations of virus-exposed tissue were performed by transmission electron microscopy (TEM).

Results

IHC and ISZ revealed sufficient expression of the transgene. Severe cellular inflammation and intima hyperplasia were seen only in adenovirus treated mgR/mgR aortas (Ad.β-Gal, Ad.hTIMP-1 NI: 0.23; 0.43), but not in native and Ad.hTIMP-1 treated WT (NI: 0.01; 0.00). Compared to native mgR/mgR and Ad.hTIMP-1 treated WT aorta, the NI is highly significant greater in Ad.hTIMP-1 transduced mgR/mgR aorta (p = 0.001; p = 0.001). As expected, untreated Marfan grafts showed significant more elastolysis compared to WT (p = 0.001). However, elastolysis in Marfan aortas was not reduced by adenoviral overexpression of hTIMP-1 (compared to untreated Marfan aorta: Ad.hTIMP-1 p = 0.902; control Ad.β-Gal. p = 0.165). The virus-untreated and not transplanted mgR/mgR aorta revealed a significant increase of albumin diffusion through the endothelial barrier (p = 0.037). TEM analysis of adenovirus-exposed mgR/mgR aortas displayed disruption of the basement membrane and basolateral space.

Conclusions

Murine Marfan aortic grafts developed severe inflammation after adenoviral contact. We demonstrated that fibrillin-1 deficiency is associated with relevant dysfunction of the endothelial barrier that enables adenovirus to induce vessel-harming inflammation. Endothelial dysfunction may play a pivotal role in the development of the vascular phenotype of Marfan syndrome.

Circulating levels of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases during Japanese encephalitis virus infection

Matrix metalloproteinases (MMPs) are widely implicated in modulating blood brain barrier (BBB) integrity and affect the entry of peripheral immune cells into the central nervous system (CNS). The expression of MMPs is tightly regulated at the level of gene transcription, conversion of pro-enzyme to active MMPs and by the action of tissue inhibitors of metalloproteinases (TIMP). The crucial role of MMPs in inflammation indicates that perturbation of the MMP/TIMP balance decisively plays an important role in pathogenesis during viral encephalitis. The study was performed to evaluate the production of MMP-2, MMP-7, MMP-9, TIMP-1 and TIMP-3 in the sera of JEV i.e. GP 78668A (GP-78) infected BALB/c mouse model of encephalitis and gel zymography was performed for MMP-2 and MMP-9 activities. The estimation of MMP-2, MMP-7, MMP-9, TIMP-1, and TIMP-3 in JEV-infected mouse serum was analyzed by ELISA along with brain histopathology and immunohistochemistry. Evan's blue dye exclusion test was done to check the BBB integrity. Gelatin gel zymography was performed for MMP-2 and MMP-9 activities. We noticed an upregulated expression of MMPs in the sera of virus infected groups compared to controls at different days post inoculation (dpi). Post hoc analysis between days also reveals significant increase (p < 0.05) in virus infected groups with disease progression. In contrast, TIMPs expressions were significantly (p < 0.005) down regulated in the virus infected group. We provide preliminary evidence for a pattern of TIMP response in JEV infection distinct from that seen in acute inflammatory CNS conditions in JE, shown in our previous findings. Increased MMP-2 and MMP-9 activities were also found in a virus infected group with disease progression and are consistent with our previous finding of MMP-2 and MMP-9 activities in the CNS which clearly demonstrate worsen role of these immune mediators in JEV infection. This study will help to identify new targets for the therapeutic treatment of inflammatory mediated CNS disorders in JEV infection and may lead to the development of potential pharmacological targets in future.

Matrix Metalloproteinases as Regulators of Vein Structure and Function: Implications in Chronic Venous Disease

Lower-extremity veins have efficient wall structure and function and competent valves that permit upward movement of deoxygenated blood toward the heart against hydrostatic venous pressure. Matrix metalloproteinases (MMPs) play an important role in maintaining vein wall structure and function. MMPs are zinc-binding endopeptidases secreted as inactive pro-MMPs by fibroblasts, vascular smooth muscle (VSM), and leukocytes. Pro-MMPs are activated by various activators including other MMPs and proteinases. MMPs cause degradation of extracellular matrix (ECM) proteins such as collagen and elastin, and could have additional effects on the endothelium, as well as VSM cell migration, proliferation, Ca(2+) signaling, and contraction. Increased lower-extremity hydrostatic venous pressure is thought to induce hypoxia-inducible factors and other MMP inducers/activators such as extracellular matrix metalloproteinase inducer, prostanoids, chymase, and hormones, leading to increased MMP expression/activity, ECM degradation, VSM relaxation, and venous dilation. Leukocyte infiltration and inflammation of the vein wall cause further increases in MMPs, vein wall dilation, valve degradation, and different clinical stages of chronic venous disease (CVD), including varicose veins (VVs). VVs are characterized by ECM imbalance, incompetent valves, venous reflux, wall dilation, and tortuosity. VVs often show increased MMP levels, but may show no change or decreased levels, depending on the VV region (atrophic regions with little ECM versus hypertrophic regions with abundant ECM) and MMP form (inactive pro-MMP versus active MMP). Management of VVs includes compression stockings, venotonics, and surgical obliteration or removal. Because these approaches do not treat the causes of VVs, alternative methods are being developed. In addition to endogenous tissue inhibitors of MMPs, synthetic MMP inhibitors have been developed, and their effects in the treatment of VVs need to be examined.