Mechanism of inhibition of the human matrix metalloproteinase stromelysin-1 by TIMP-1

The Role of Biomarkers in Predicting Outcomes of Anterior Cruciate Ligament Reconstruction: A Systematic Review

Background

Anterior cruciate ligament (ACL) injury is frequently associated with injuries to other parts of the knee, including the menisci and articular cartilage. After ACL injury and reconstruction, there may be progressive chondral degradation. Biomarkers in blood, urine, and synovial fluid can be measured after ACL injury and reconstruction and have been proposed as a means of measuring the associated cellular changes occurring in the knee.

Purpose

To systematically review the literature regarding biomarkers in urine, serum, or synovial fluid that have been associated with an outcome measure after ACL reconstruction.

Study Design

Systematic review; Level of evidence, 3.

Methods

This review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The MEDLINE, Embase, CINAHL, and Web of Science databases were searched to identify studies published before September 2023 that reported on patients undergoing ACL reconstruction where a biomarker was measured and related to an outcome variable. Of 9360 results, 16 studies comprising 492 patients were included. Findings were reported as descriptive summaries synthesizing the available literature.

Results

A total of 45 unique biomarkers or biomarker ratios were investigated (12 serum, 3 urine, and 38 synovial fluid; 8 biomarkers were measured from >1 source). Nineteen different outcome measures were identified, including the International Knee Documentation Committee Subjective Knee Form, Knee injury and Osteoarthritis Outcome Score, numeric pain scores, radiological outcomes (magnetic resonance imaging and radiography), rates of arthrofibrosis and cyclops lesions, and gait biomechanics. Across the included studies, 17 biomarkers were found to have a statistically significant association (P < .05) with an outcome variable. Serum interleukin 6 (s-IL-6), serum and synovial fluid matrix metalloproteinase-3 (s-MMP-3 and sf-MMP-3), urinary and synovial fluid C-terminal telopeptide of type 2 collagen (u-CTX-II and sf-CTX-II), and serum collagen type 2 cleavage product (s-C2C) showed promise in predicting outcomes after ACL reconstruction, specifically regarding patient-reported outcome measures (s-IL-6 and u-CTX-II), gait biomechanical parameters (s-IL-6, sf-MMP-3, s-MMP-3, and s-C2C), pain (s-IL-6 and u-CTX-II), and radiological osteoarthritis (ratio of u-CTX-II to serum procollagen 2 C-propeptide).

Conclusion

The results highlight several biomarkers that have been associated with clinically important postoperative outcome measures and may warrant further research to understand if they can provide meaningful information in the clinical environment.

The Effect of Tissue Inhibitor of Metalloproteinases on Scar Formation after Spinal Cord Injury

Spinal cord injury (SCI) often results in permanent loss of motor and sensory function. After SCI, the blood-spinal cord barrier (BSCB) is disrupted, causing the infiltration of neutrophils and macrophages, which secrete several kinds of cytokines, as well as matrix metalloproteinases (MMPs). MMPs are proteases capable of degrading various extracellular matrix (ECM) proteins, as well as many non-matrix substrates. The tissue inhibitor of MMPs (TIMP)-1 is significantly upregulated post-SCI and operates via MMP-dependent and MMP-independent pathways. Through the MMP-dependent pathway, TIMP-1 directly reduces inflammation and destruction of the ECM by binding and blocking the catalytic domains of MMPs. Thus, TIMP-1 helps preserve the BSCB and reduces immune cell infiltration. The MMP-independent pathway involves TIMP-1's cytokine-like functions, in which it binds specific TIMP surface receptors. Through receptor binding, TIMP-1 can stimulate the proliferation of several types of cells, including keratinocytes, aortic smooth muscle cells, skin epithelial cells, corneal epithelial cells, and astrocytes. TIMP-1 induces astrocyte proliferation, modulates microglia activation, and increases myelination and neurite extension in the central nervous system (CNS). In addition, TIMP-1 also regulates apoptosis and promotes cell survival through direct signaling. This review provides a comprehensive assessment of TIMP-1, specifically regarding its contribution to inflammation, ECM remodeling, and scar formation after SCI.

Advances and perspectives on pharmacological activities and mechanisms of the monoterpene borneol

BACKGROUND

Borneol, a highly lipid-soluble bicyclic terpene mainly extracted from plants, is representative of monoterpenoids. Modern medicine has established that borneol exhibits a range of pharmacological activities and used in the treatment of many diseases, particularly Cardio-cerebrovascular diseases (CVDs). The crucial role in enhancing drug delivery and improving bioavailability has attracted much attention. In addition, borneol is also widely utilized in food, daily chemicals, fragrances, and flavors industries.

PURPOSE

This review systematically summarized the sources, pharmacological activities and mechanisms, clinical trial, pharmacokinetics, toxicity, and application of borneol. In addition, this review describes the pharmacological effects of borneol ester and the combination of borneol with nanomaterial. This review will provide a valuable resource for those pursuing researches on borneol inspiring the pharmacological applications in the medicine, food and daily chemical products, and developing of new drugs containing borneol or its derivatives.

METHODS

This review searched the keywords ("borneol" or "bornyl esters") and ("pharmacology" or "Traditional Chinese medicine" or "Cardio-cerebrovascular diseases" or "blood-brain barrier" or "ischemic stroke" or "nanomaterials" or "neurodegenerative diseases" or "diabetes" or "toxicity") in Web of Science, PubMed, Google Scholar and China National Knowledge Infrastructure (CNKI) from January 1990 to May 2024. The search was limited to articles published in English and Chinese.

RESULTS

Borneol exhibits extensive pharmacological activities including anti-inflammatory effects, analgesia, antioxidation, and has the property of crossing biological barriers and treating CVDs. The intrinsic molecular mechanisms are involved in multiple components, such as regulation of various key factors (including Tumor necrosis factor-α, Nuclear factor kappa-B, Interleukin-1β, Malondialdehyde), inhibiting transporter protein function, regulating biochemical levels, and altering physical structural changes. In addition, this review describes the pharmacological effects of borneol ester and the combination of borneol with nanomaterial.

CONCLUSION

The pharmacological properties and applications of borneol are promising, including anti-inflammatory, analgesic, antimicrobial, and antioxidant properties, as well as enhancing drug delivery and treating CVDs. However, its clinical application is hindered by the limited research on safety, efficacy, and pharmacokinetics. Therefore, this review systemically summarized the advances on pharmacological activities and mechanisms of the borneol. Standardized clinical trials and exploration of synergistic effects with other drugs were also are outlined.

Integrating bulk and single-cell sequencing reveals metastasis-associated CAFs in head and neck squamous cell carcinoma

AIMS

Cancer-associated fibroblasts (CAFs) have been shown to promote the metastasis of head and neck squamous cell carcinoma (HNSCC), but the underlying mechanisms remain unclear. The purpose of this study is to identify gene in CAFs that are associated with metastasis and to preliminarily validate its impact on the metastasis of HNSCC.

MATERIALS AND METHODS

Scissor analysis was utilized to process single-cell and bulk RNA sequencing datasets, identifying genes associated with the metastasis of HNSCC through differential gene expression analysis. A risk model was constructed using LASSO regression analysis. Quantitative real time-PCR and Western blot were employed to measure mRNA and protein expressions, respectively. Multiplex immunohistochemistry (mIHC) was used to assess protein expression in CAFs. siRNA was utilized to achieve gene knockdown. CCK-8 and Transwell assays were employed to evaluate the biological characteristics of HNSCC cells.

KEY FINDINGS

Compare to the nonmetastatic primary CAFs (nmCAFs), tissue inhibitors of metalloproteinase-1 (TIMP1) was founded to be overexpressed in the cells and tissues of metastatic primary CAFs (mCAFs). Knocking down TIMP1 in CAFs can signifucantly inhibit the proliferation, invasion, and migration of HNSCC cells.

SIGNIFICANCE

CAFs facilitate HNSCC cell metastasis by upregulating TIMP1, highlighting TIMP1 as a potential therapeutic target in HNSCC metastasis management.

Effect of human epididymis protein 4 on hyperoxia-induced bronchial dysplasia in newborn rats

OBJECTIVE

The study aimed to elucidate the role and the underlying mechanism of human epididymis protein 4 (HE4) in the pathogenesis of hyperoxia-induced bronchial dysplasia in newborn rats.

METHODS

Forty neonatal Sprague-Dawley (SD) rats were separated into two groups: a normal control group (20.8% oxygen concentration) and a hyperoxia-induced group (85% oxygen concentration). Three time intervals of 24 h, 3 days and 7 days were chosen for each group. Haematoxylin-eosin staining was used to identify the pathological alterations in the lung tissue of the SD rats. Enzyme-linked immunosorbent assay was used to evaluate plasma protein levels. Real-time reverse transcription polymerase chain reaction was used to determine messenger RNA (mRNA) expression.

RESULTS

In newborn SD rats, hyperoxia intervention within 7 days may result in acute lung damage. In the plasma and tissue of newborn SD rats, hyperoxia induction may raise levels of HE4, matrix metalloproteinases (MMP) 9 and tissue inhibitors of metalloproteinases (TIMP) 1. We discovered that the HE4 protein activates the phosphorylation of extracellular regulated protein kinases (ERK) and p65, activates the downstream MMP9 signalling pathway, inhibits MMP9 mRNA expression, inhibits protein activity, reduces type I collagen degradation, increases collagen secretion and promotes matrix remodelling and fibrosis in neonatal rat primary alveolar type II epithelial cells by overexpressing and silencing the HE4 gene.

CONCLUSION

Through the ERK, MMP9 and TIMP1 signalling pathways, HE4 mediates the pathophysiological process of hyperoxia-induced lung damage in rats. Lung damage and lung basal remodelling are mediated by HE4 overexpression.

A Novel Strategy for the Treatment of Aneurysms: Inhibition of MMP-9 Activity through the Delivery of TIMP-1 Encoding Synthetic mRNA into Arteries

Aneurysms pose life-threatening risks due to the dilatation of the arteries and carry a high risk of rupture. Despite continuous research efforts, there are still no satisfactory or clinically effective pharmaceutical treatments for this condition. Accelerated inflammatory processes during aneurysm development lead to increased levels of matrix metalloproteinases (MMPs) and destabilization of the vessel wall through the degradation of the structural components of the extracellular matrix (ECM), mainly collagen and elastin. Tissue inhibitors of metalloproteinases (TIMPs) directly regulate MMP activity and consequently inhibit ECM proteolysis. In this work, the synthesis of TIMP-1 protein was increased by the exogenous delivery of synthetic TIMP-1 encoding mRNA into aortic vessel tissue in an attempt to inhibit MMP-9. In vitro, TIMP-1 mRNA transfection resulted in significantly increased TIMP-1 protein expression in various cells. The functionality of the expressed protein was evaluated in an appropriate ex vivo aortic vessel model. Decreased MMP-9 activity was detected using in situ zymography 24 h and 48 h post microinjection of 5 µg TIMP-1 mRNA into the aortic vessel wall. These results suggest that TIMP-1 mRNA administration is a promising approach for the treatment of aneurysms.

Extracellular proteolysis in cancer: Proteases, substrates, and mechanisms in tumor progression and metastasis

A vast ensemble of extracellular proteins influences the development and progression of cancer, shaped and reshaped by a complex network of extracellular proteases. These proteases, belonging to the distinct classes of metalloproteases, serine proteases, cysteine proteases, and aspartic proteases, play a critical role in cancer. They often become dysregulated in cancer, with increases in pathological protease activity frequently driven by the loss of normal latency controls, diminished regulation by endogenous protease inhibitors, and changes in localization. Dysregulated proteases accelerate tumor progression and metastasis by degrading protein barriers within the extracellular matrix (ECM), stimulating tumor growth, reactivating dormant tumor cells, facilitating tumor cell escape from immune surveillance, and shifting stromal cells toward cancer-promoting behaviors through the precise proteolysis of specific substrates to alter their functions. These crucial substrates include ECM proteins and proteoglycans, soluble proteins secreted by tumor and stromal cells, and extracellular domains of cell surface proteins, including membrane receptors and adhesion proteins. The complexity of the extracellular protease web presents a significant challenge to untangle. Nevertheless, technological strides in proteomics, chemical biology, and the development of new probes and reagents are enabling progress and advancing our understanding of the pivotal importance of extracellular proteolysis in cancer.

TIMP-1 is an activator of MHC-I expression in myeloid dendritic cells with implications for tumor immunogenicity

Immune checkpoint therapies (ICT) for advanced solid tumors mark a new milestone in cancer therapy. Yet their efficacy is often limited by poor immunogenicity, attributed to inadequate priming and generation of antitumor T cells by dendritic cells (DCs). Identifying biomarkers to enhance DC functions in such tumors is thus crucial. Tissue Inhibitor of Metalloproteinases-1 (TIMP-1), recognized for its influence on immune cells, has an underexplored relationship with DCs. Our research reveals a correlation between high TIMP1 levels in metastatic melanoma and increased CD8 + T cell infiltration and survival. Network studies indicate a functional connection with HLA genes. Spatial transcriptomic analysis of a national melanoma cohort revealed that TIMP1 expression in immune compartments associates with an HLA-A/MHC-I peptide loading signature in lymph nodes. Primary human and bone-marrow-derived DCs secrete TIMP-1, which notably increases MHC-I expression in classical type 1 dendritic cells (cDC1), especially under melanoma antigen exposure. TIMP-1 affects the immunoproteasome/TAP complex, as seen by upregulated PSMB8 and TAP-1 levels of myeloid DCs. This study uncovers the role of TIMP-1 in DC-mediated immunogenicity with insights into CD8 + T cell activation, providing a foundation for mechanistic exploration and highlighting its potential as a new target for combinatorial immunotherapy to enhance ICT effectiveness.

Timp1 Deletion Induces Anxiety-like Behavior in Mice

The hippocampus is essential for learning and memory, but it also plays an important role in regulating emotional behavior, as hippocampal excitability and plasticity affect anxiety and fear. Brain synaptic plasticity may be regulated by tissue inhibitor of matrix metalloproteinase 1 (TIMP1), a known protein inhibitor of extracellular matrix (ECM), and the expression of TIMP1 in the hippocampus can be induced by neuronal excitation and various stimuli. However, the involvement of Timp1 in fear learning, anxiety, and hippocampal synaptic function remains to be established. Our study of Timp1 function in vivo revealed that Timp1 knockout mice exhibit anxiety-like behavior but normal fear learning. Electrophysiological results suggested that Timp1 knockout mice showed hyperactivity in the ventral CA1 region, but the basic synaptic transmission and plasticity were normal in the Schaffer collateral pathway. Taken together, our results suggest that deletion of Timp1 in vivo leads to the occurrence of anxiety behaviors, but that Timp1 is not crucial for fear learning.

Hepatokine ITIH3 protects against hepatic steatosis by downregulating mitochondrial bioenergetics and de novo lipogenesis

Recent studies demonstrate that liver secretory proteins, also known as hepatokines, regulate normal development, obesity, and simple steatosis to non-alcoholic steatohepatitis (NASH) progression. Using a panel of ∼100 diverse inbred strains of mice and a cohort of bariatric surgery patients, we found that one such hepatokine, inter-trypsin inhibitor heavy chain 3 (ITIH3), was progressively lower in severe non-alcoholic fatty liver disease (NAFLD) disease states highlighting an inverse relationship between Itih3/ITIH3 expression and NAFLD severity. Follow-up animal and cell culture models demonstrated that hepatic ITIH3 overexpression lowered liver triglyceride and lipid droplet accumulation, respectively. Conversely, ITIH3 knockdown in mice increased the liver triglyceride in two independent NAFLD models. Mechanistically, ITIH3 reduced mitochondrial respiration and this, in turn, reduced liver triglycerides, via downregulated de novo lipogenesis. This was accompanied by increased STAT1 signaling and Stat3 expression, both of which are known to protect against NAFLD/NASH. Our findings indicate hepatokine ITIH3 as a potential biomarker and/or treatment for NAFLD.

Correlation of Experimental and Calculated Inhibition Constants of Protease Inhibitor Complexes

Predicting the potency of inhibitors is key to in silico screening of promising synthetic or natural compounds. Here we describe a predictive workflow that provides calculated inhibitory values, which concord well with empirical data. Calculations of the free interaction energy ΔG with the YASARA plugin FoldX were used to derive inhibition constants Ki from PDB coordinates of protease-inhibitor complexes. At the same time, corresponding KD values were obtained from the PRODIGY server. These results correlated well with the experimental values, particularly for serine proteases. In addition, analyses were performed for inhibitory complexes of cysteine and aspartic proteases, as well as of metalloproteases, whereby the PRODIGY data appeared to be more consistent. Based on our analyses, we calculated theoretical Ki values for trypsin with sunflower trypsin inhibitor (SFTI-1) variants, which yielded the more rigid Pro14 variant, with probably higher potency than the wild-type inhibitor. Moreover, a hirudin variant with an Arg1 and Trp3 is a promising basis for novel thrombin inhibitors with high potency. Further examples from antibody interaction and a cancer-related effector-receptor system demonstrate that our approach is applicable to protein interaction studies beyond the protease field.

Tracing the evolution of tissue inhibitor of metalloproteinases in Metazoa with the Pteria penguin genome

Tissue inhibitors of metalloproteinase (TIMPs) play a pivotal role in regulating extracellular matrix (ECM) dynamics and have been extensively studied in vertebrates. However, understanding their evolution across invertebrate phyla is limited. Utilizing the high-quality Pteria penguin genome, we conducted phylogenomic orthology analyses across metazoans, revealing the emergence and distribution of the TIMP gene family. Our findings show that TIMP repertoires originated during eumetazoan radiation, experiencing independent duplication events in different clades, resulting in varied family sizes. Particularly, Pteriomorphia bivalves within Mollusca exhibited the most significant expansion and displayed the most diverse TIMP repertoires among metazoans. These expansions were attributed to multiple gene duplication events, potentially driven by the demands for functional diversification related to multiple adaptive traits, contributing to the adaptation of Pteriomorphia bivalves as stationary filter feeders. In this context, Pteriomorphia bivalves offer a promising model for studying invertebrate TIMP evolution.

Hypoxia-Inducible Factor and Oxidative Stress in Tendon Degeneration: A Molecular Perspective

Tendinopathy is a debilitating condition marked by degenerative changes in the tendons. Its complex pathophysiology involves intrinsic, extrinsic, and physiological factors. While its intrinsic and extrinsic factors have been extensively studied, the role of physiological factors, such as hypoxia and oxidative stress, remains largely unexplored. This review article delves into the contribution of hypoxia-associated genes and oxidative-stress-related factors to tendon degeneration, offering insights into potential therapeutic strategies. The unique aspect of this study lies in its pathway-based evidence, which sheds light on how these factors can be targeted to enhance overall tendon health.

Engineering minimal tissue inhibitors of metalloproteinase targeting MMPs via gene shuffling and yeast surface display

Overexpression of specific matrix metalloproteinases (MMPs) has a key role in development of several diseases, such as cancer, neurological disorders, and cardiovascular diseases due to their critical role in degradation and remodeling of the extracellular matrix (ECM). Tissue inhibitors of metalloproteinases (TIMPs), a family of four in humans, are endogenous inhibitors of MMPs. TIMPs have a high level of sequence and structure homology, with a broad range of binding and inhibition to the family of MMPs. It is important to identify the key motifs of TIMPs responsible for inhibition of MMPs to develop efficient therapeutics targeting specific MMPs. We used DNA shuffling between the human TIMP family to generate a minimal TIMP hybrid library in yeast to identify the dominant minimal MMP inhibitory regions. The minimal TIMP variants screened toward MMP-3 and MMP-9 using fluorescent-activated cell sorting (FACS). Interestingly, several minimal TIMP variants selected after screening toward MMP-3cd or MMP-9cd, with lengths as short as 20 amino acids, maintained or improved binding to MMP-3 and MMP-9. The TIMP-MMP binding dissociation constant (KD ), in the nM range, and MMP inhibition constants (Ki ), in the pM range, of these minimal TIMP variants were similar to the N-terminal domain of TIMP-1 on the yeast surface and in solution indicating the potency of these minimal variants as MMP inhibitors. We further used molecular modeling simulation, and molecular docking of the minimal TIMP variants in complex with MMP-3cd to understand the binding and inhibition mechanism of these variants.

Structure and computation-guided yeast surface display for the evolution of TIMP-based matrix metalloproteinase inhibitors

The study of protein-protein interactions (PPIs) and the engineering of protein-based inhibitors often employ two distinct strategies. One approach leverages the power of combinatorial libraries, displaying large ensembles of mutant proteins, for example, on the yeast cell surface, to select binders. Another approach harnesses computational modeling, sifting through an astronomically large number of protein sequences and attempting to predict the impact of mutations on PPI binding energy. Individually, each approach has inherent limitations, but when combined, they generate superior outcomes across diverse protein engineering endeavors. This synergistic integration of approaches aids in identifying novel binders and inhibitors, fine-tuning specificity and affinity for known binding partners, and detailed mapping of binding epitopes. It can also provide insight into the specificity profiles of varied PPIs. Here, we outline strategies for directing the evolution of tissue inhibitors of metalloproteinases (TIMPs), which act as natural inhibitors of matrix metalloproteinases (MMPs). We highlight examples wherein design of combinatorial TIMP libraries using structural and computational insights and screening these libraries of variants using yeast surface display (YSD), has successfully optimized for MMP binding and selectivity, and conferred insight into the PPIs involved.

Human TIMP1 Is a Growth Factor That Improves Oocyte Developmental Competence

Oocyte developmental competence is the ability of a mature oocyte to be fertilized and subsequently support embryonic development. Such competence is gained during folliculogenesis and is facilitated by the bidirectional communication into a compacted cumulus-oocyte complex (COC). Human tissue inhibitor of metalloproteinases-1 (TIMP1) participates in biological processes, including cell growth, differentiation, and apoptosis. This study aimed to evaluate the influence of TIMP1 as a growth factor on the in vitro maturation (IVM) culture of bovine COCs to improve oocyte developmental competence. All TIMP1 treatments (50, 100, and 150 ng/mL) favored the COCs' compaction structure (p < 0.05). TIMP1 at 150 ng/mL produced more oocytes in metaphase II compared to the other treatments (p < 0.05). The 150 ng/mL TIMP1 generated oocytes with the most (p < 0.05) cortical granules below the plasma membrane (pattern I). In a parthenogenesis assay, oocyte IVM in 50 ng/mL of TIMP1 produced the most blastocyst compared to the other treatments (p < 0.05). The Principal Component Analysis (PCA) showed that 50 ng/mL of TIMP1 was the best condition to develop oocyte competence because it was associated with the COC compact and cortical granule pattern I. TIMP1 influences the development of oocyte competence when added to the IVM culture medium of COCs.

The Continuing Saga of Tissue Inhibitor of Metalloproteinase 2: Emerging Roles in Tissue Homeostasis and Cancer Progression

Tissue inhibitors of metalloproteinases (TIMPs) are a conserved family of proteins that were originally identified as cytokine-like erythroid growth factors. Subsequently, TIMPs were characterized as endogenous inhibitors of matrixin proteinases. These proteinases are the primary mediators of extracellular matrix turnover in pathologic conditions, such as cancer invasion and metastasis. Thus, TIMPs were immediately recognized as important regulators of tissue homeostasis. However, TIMPs also demonstrate unique biological activities that are independent of metalloproteinase regulation. Although often overlooked, these non-protease-mediated TIMP functions demonstrate a variety of direct cellular effects of potential therapeutic value. TIMP2 is the most abundantly expressed TIMP family member, and ongoing studies show that its tumor suppressor activity extends beyond protease inhibition to include direct modulation of tumor, endothelial, and fibroblast cellular responses in the tumor microenvironment. Recent data suggest that TIMP2 can suppress both primary tumor growth and metastatic niche formation. TIMP2 directly interacts with cellular receptors and matrisome elements to modulate cell signaling pathways that result in reduced proliferation and migration of neoplastic, endothelial, and fibroblast cell populations. These effects result in enhanced cell adhesion and focal contact formation while reducing tumor and endothelial proliferation, migration, and epithelial-to-mesenchymal transitions. These findings are consistent with TIMP2 homeostatic functions beyond simple inhibition of metalloprotease activity. This review examines the ongoing evolution of TIMP2 function, future perspectives in TIMP research, and the therapeutic potential of TIMP2.

Non-Canonical Amino Acids in Analyses of Protease Structure and Function

All known organisms encode 20 canonical amino acids by base triplets in the genetic code. The cellular translational machinery produces proteins consisting mainly of these amino acids. Several hundred natural amino acids serve important functions in metabolism, as scaffold molecules, and in signal transduction. New side chains are generated mainly by post-translational modifications, while others have altered backbones, such as the β- or γ-amino acids, or they undergo stereochemical inversion, e.g., in the case of D-amino acids. In addition, the number of non-canonical amino acids has further increased by chemical syntheses. Since many of these non-canonical amino acids confer resistance to proteolytic degradation, they are potential protease inhibitors and tools for specificity profiling studies in substrate optimization and enzyme inhibition. Other applications include in vitro and in vivo studies of enzyme kinetics, molecular interactions and bioimaging, to name a few. Amino acids with bio-orthogonal labels are particularly attractive, enabling various cross-link and click reactions for structure-functional studies. Here, we cover the latest developments in protease research with non-canonical amino acids, which opens up a great potential, e.g., for novel prodrugs activated by proteases or for other pharmaceutical compounds, some of which have already reached the clinical trial stage.

Salivary Chemical Barrier Proteins in Oral Squamous Cell Carcinoma-Alterations in the Defense Mechanism of the Oral Cavity

Oral squamous cell carcinoma (OSCC) is one of the most frequent types of head and neck cancer. Despite the genetic and environmental risk factors, OSCC is also associated with microbial infections and/or dysbiosis. The secreted saliva serves as the chemical barrier of the oral cavity and, since OSCC can alter the protein composition of saliva, our aim was to analyze the effect of OSCC on the salivary chemical barrier proteins. Publicly available datasets regarding the analysis of salivary proteins from patients with OSCC and controls were collected and examined in order to identify differentially expressed chemical barrier proteins. Network analysis and gene ontology (GO) classification of the differentially expressed chemical barrier proteins were performed as well. One hundred and twenty-seven proteins showing different expression pattern between the OSCC and control groups were found. Protein-protein interaction networks of up- and down-regulated proteins were constructed and analyzed. The main hub proteins (IL-6, IL-1B, IL-8, TNF, APOA1, APOA2, APOB, APOC3, APOE, and HP) were identified and the enriched GO terms were examined. Our study highlighted the importance of the chemical barrier of saliva in the development of OSCC.

Proteomics Identifies Circulating TIMP-1 as a Prognostic Biomarker for Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease, although disease stratification using in-depth plasma proteomics has not been performed to date. By measuring more than 1000 proteins in the plasma of 147 DLBCL patients using data-independent acquisition mass spectrometry and antibody array, DLBCL patients were classified into four proteomic subtypes (PS-I-IV). Patients with the PS-IV subtype and worst prognosis had increased levels of proteins involved in inflammation, including a high expression of metalloproteinase inhibitor-1 (TIMP-1) that was associated with poor survival across two validation cohorts (n = 180). Notably, the combination of TIMP-1 with the international prognostic index (IPI) identified 64.00% to 88.24% of relapsed and 65.00% to 80.49% of deceased patients in the discovery and two validation cohorts, which represents a 24.00% to 41.67% and 20.00% to 31.70% improvement compared to the IPI score alone, respectively. Taken together, we demonstrate that DLBCL heterogeneity is reflected in the plasma proteome and that TIMP-1, together with the IPI, could improve the prognostic stratification of patients.

TIMP-1 Protects Tight Junctions of Brain Endothelial Cells From MMP-Mediated Degradation

OBJECTIVE

The blood-brain barrier (BBB) plays a critical role in central nervous system homeostasis, and the integrity of BBB is disrupted in many neurodegenerative diseases. Matrix metalloproteinases (MMPs) degrade the tight junctions (TJs) of endothelial cells and basement membrane components essential to BBB integrity, which leads to increased BBB permeability and allows inflammatory cells and neurotoxic substances to enter the brain. Tissue inhibitors of metalloproteinases (TIMPs), endogenous inhibitors of MMPs, regulate MMP activity, thereby maintaining BBB integrity.

METHODS

The disruptive impacts of MMP-3 and MMP-9 on BBB and protective effect of TIMP-1 were investigated in a simplified in vitro model of the BBB, which was generated using rat brain microvascular endothelial cells (RBMEC). The main features of BBB formation, including permeability and the trans-endothelial electrical resistance (TEER), were monitored over time after the addition of MMP-3 and MMP-9 and their complexes with TIMP-1 inhibitor.

RESULTS

Our results indicated that MMP-3 and MMP-9 caused a dose-dependent disruption of the BBB, with 1.5 µM MMPs resulting in an over threefold increase in permeability, while TIMP-1 inhibition protected the integrity of the BBB model and recovered TEER and permeability of RBMECs. The disruption and recovery of tight junction proteins of RBMECs after MMP and TIMP treatment were also detected using fluorescent microscopy.

CONCLUSION

MMP-9 and MMP-3 disrupt the BBB by degrading tight junctions in endothelial cells, and TIMP-1 could inhibit the disruptive effect of MMP-3 and MMP-9 by showing potential as therapeutic protein against MMP-related diseases where BBB disruption plays a role.

NMR structure of emfourin, a novel protein metalloprotease inhibitor: Insights into the mechanism of action

Emfourin (M4in) is a protein metalloprotease inhibitor recently discovered in the bacterium Serratia proteamaculans and the prototype of a new family of protein protease inhibitors with an unknown mechanism of action. Protealysin-like proteases (PLPs) of the thermolysin family are natural targets of emfourin-like inhibitors widespread in bacteria and known in archaea. The available data indicate the involvement of PLPs in interbacterial interaction as well as bacterial interaction with other organisms and likely in pathogenesis. Arguably, emfourin-like inhibitors participate in the regulation of bacterial pathogenesis by controlling PLP activity. Here, we determined the 3D structure of M4in using solution NMR spectroscopy. The obtained structure demonstrated no significant similarity to known protein structures. This structure was used to model the M4in-enzyme complex and the complex model was verified by small-angle X-ray scattering. Based on the model analysis, we propose a molecular mechanism for the inhibitor, which was confirmed by site-directed mutagenesis. We show that two spatially close flexible loop regions are critical for the inhibitor-protease interaction. One region includes aspartic acid forming a coordination bond with catalytic Zn2+ of the enzyme and the second region carries hydrophobic amino acids interacting with protease substrate binding sites. Such an active site structure corresponds to the noncanonical inhibition mechanism. This is the first demonstration of such a mechanism for protein inhibitors of thermolysin family metalloproteases, which puts forward M4in as a new basis for the development of antibacterial agents relying on selective inhibition of prominent factors of bacterial pathogenesis belonging to this family.

A unique network of attack, defence and competence on the outer membrane of the periodontitis pathogen Tannerella forsythia

Periodontopathogenic Tannerella forsythia uniquely secretes six peptidases of disparate catalytic classes and families that operate as virulence factors during infection of the gums, the KLIKK-peptidases. Their coding genes are immediately downstream of novel ORFs encoding the 98-132 residue potempins (Pot) A, B1, B2, C, D and E. These are outer-membrane-anchored lipoproteins that specifically and potently inhibit the respective downstream peptidase through stable complexes that protect the outer membrane of T. forsythia, as shown in vivo. Remarkably, PotA also contributes to bacterial fitness in vivo and specifically inhibits matrix metallopeptidase (MMP) 12, a major defence component of oral macrophages, thus featuring a novel and highly-specific physiological MMP inhibitor. Information from 11 structures and high-confidence homology models showed that the potempins are distinct β-barrels with either a five-stranded OB-fold (PotA, PotC and PotD) or an eight-stranded up-and-down fold (PotE, PotB1 and PotB2), which are novel for peptidase inhibitors. Particular loops insert like wedges into the active-site cleft of the genetically-linked peptidases to specifically block them either via a new "bilobal" or the classic "standard" mechanism of inhibition. These results discover a unique, tightly-regulated proteolytic armamentarium for virulence and competence, the KLIKK-peptidase/potempin system.

TIMP-1 is a novel ligand of Amyloid Precursor Protein and triggers a proinflammatory phenotype in human monocytes

The emerging cytokine tissue inhibitor of metalloproteinases-1 (TIMP-1) correlates with the progression of inflammatory diseases, including cancer. However, the effects of TIMP-1 on immune cell activation and underlying molecular mechanisms are largely unknown. Unbiased ligand-receptor-capture-screening revealed TIMP-1-interaction with Amyloid Precursor Protein (APP) family members, namely APP and Amyloid Precursor-like Protein-2 (APLP2), which was confirmed by pull-down assays and confocal microscopy. We found that TIMP-1 triggered glucose uptake and proinflammatory cytokine expression in human monocytes. In cancer patients, TIMP-1 expression positively correlated with proinflammatory cytokine expression and processes associated with monocyte activation. In pancreatic cancer, TIMP-1 plasma levels correlated with the monocyte activation marker sCD163, and the combined use of both clinically accessible plasma proteins served as a powerful prognostic indicator. Mechanistically, TIMP-1 triggered monocyte activation by its C-terminal domain and via APP as demonstrated by in vitro interference, in silico docking, and the employment of recombinant TIMP-1 variants. Identification of TIMP-1 as a trigger of monocyte activation opens new therapeutic perspectives for inflammatory diseases.

Early Phase Increase in Serum TIMP-1 in Patients with Acute Encephalopathy with Biphasic Seizures and Late Reduced Diffusion

BACKGROUND

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most frequent subtype of acute encephalopathy syndrome among Japanese children. Exanthem subitum is the most common causative infectious disease of AESD. We herein retrospectively analyzed serum and cerebrospinal fluid (CSF) concentrations of matrix metalloproteinase-9 (MMP-9), tissue inhibitor matrix metalloproteinase-1 (TIMP-1), and seven cytokines in patients with AESD or prolonged febrile seizure (FS) to assess the pathophysiology of AESD and detect biomarkers for diagnosing AESD in the early phase.

METHODS

Serum and CSF samples were obtained from 17 patients with AESD (1st seizure phase group, n = 7; 2nd seizure phase group, n = 10) and 8 with FS. The concentrations of MMP-9, TIMP-1, and seven cytokines were measured by enzyme-linked immunosorbent assays or cytometric bead arrays.

RESULTS

Serum concentrations of TIMP-1 were significantly higher in the 1st seizure phase group than in the 2nd seizure phase group. No significant differences were observed in serum concentrations of MMP-9 or the MMP-9/TIMP-1 ratio.

CONCLUSIONS

The MMP-9-independent increase in circulating TIMP-1 concentrations observed in the present study may be associated with the pathophysiology of AESD in the 1st seizure phase.

Overview of Anti-Inflammatory and Anti-Nociceptive Effects of Polyphenols to Halt Osteoarthritis: From Preclinical Studies to New Clinical Insights

Knee osteoarthritis (OA) is one of the most multifactorial joint disorders in adults. It is characterized by degenerative and inflammatory processes that are responsible for joint destruction, pain and stiffness. Despite therapeutic advances, the search for alternative strategies to target inflammation and pain is still very challenging. In this regard, there is a growing body of evidence for the role of several bioactive dietary molecules (BDMs) in targeting inflammation and pain, with promising clinical results. BDMs may be valuable non-pharmaceutical solutions to treat and prevent the evolution of early OA to more severe phenotypes, overcoming the side effects of anti-inflammatory drugs. Among BDMs, polyphenols (PPs) are widely studied due to their abundance in several plants, together with their benefits in halting inflammation and pain. Despite their biological relevance, there are still many questionable aspects (biosafety, bioavailability, etc.) that hinder their clinical application. This review highlights the mechanisms of action and biological targets modulated by PPs, summarizes the data on their anti-inflammatory and anti-nociceptive effects in different preclinical in vitro and in vivo models of OA and underlines the gaps in the knowledge. Furthermore, this work reports the preliminary promising results of clinical studies on OA patients treated with PPs and discusses new perspectives to accelerate the translation of PPs treatment into the clinics.

RANTES Concentration at the Time of Surgery Is Associated With Postoperative Stiffness in Patients Undergoing ACL Reconstruction

BACKGROUND

Patients undergoing anterior cruciate ligament (ACL) reconstruction have been shown to be at risk for postoperative arthrofibrosis. Diagnostic biomarkers associated with the development of postoperative stiffness are unknown.

HYPOTHESIS

Biomarkers found in the synovial fluid at the time of surgery are associated with the development of postoperative arthrofibrosis in a cohort of patients undergoing ACL reconstruction.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Patients undergoing ACL reconstruction were prospectively enrolled. Synovial fluid was collected before surgical incision. A cohort of patients with postoperative stiffness requiring manipulation under anesthesia (MUA) and/or lysis of adhesions (LOA) was retrospectively identified. Matching of cases to controls was performed using a 1:2 pair matching algorithm. Risk factor-adjusted single-biomarker and multivariable models were used to assess the association of synovial fluid biomarkers with postoperative stiffness requiring MUA/LOA. Stepwise logistic regression controlling for clinical risk factors was used to identify biomarkers that are possible predictors of postoperative stiffness.

RESULTS

A total of 11 cases (3 male, 8 female) were identified and matched with 21 controls (6 male, 15 female) with no significant differences in age, sex, smoking history, or days from injury to surgery. Concentrations of the biomarker regulated upon activation, normal T-cell expressed and presumably secreted (RANTES) were significantly higher in patients requiring MUA/LOA versus controls (694.20 pg/mL [interquartile range, 214.75-3428.79] vs 113.04 pg/mL [interquartile range, 32.81-517.91], respectively; P = .034). On single-biomarker models, RANTES (odds ratio, 2.28; 95% CI, 1.29-5.37; P = .019) and basic fibroblast growth factor (bFGF) (odds ratio, 1.91; 95% CI, 1.07-3.99; P = .047) were associated with increased risk of postoperative stiffness requiring MUA/LOA after ACL reconstruction. Stepwise logistic regression identified 3 biomarkers that are possible predictors of postoperative stiffness, which were included in the final model: Interleukin 1 receptor antagonist (IL-1RA) (P = .198), bFGF (P = .157), and RANTES (P = .046).

CONCLUSION

Higher concentrations of synovial fluid biomarkers bFGF and RANTES were associated with increased risk for stiffness requiring intervention after ACL reconstruction. Interleukin 6 (IL-6), vascular endothelial growth factor A (VEGF-A), tissue inhibitor of metalloproteinases 1 (TIMP-1), interleukin 1 receptor antagonist (IL-1RA), matrix metalloproteinase 3 (MMP-3), monocyte chemotactic protein 1 (MCP-1), and macrophage inflammatory protein 1B (MIP-1B) were not associated with the development of postoperative arthrofibrosis.

Cut loose TIMP-1: an emerging cytokine in inflammation

Appreciation of the entire biological impact of an individual protein can be hampered by its original naming based on one function only. Tissue inhibitor of metalloproteinases-1 (TIMP-1), mostly known for its eponymous function to inhibit metalloproteinases, exhibits only a fraction of its cellular effects via this feature. Recently, TIMP-1 emerged as a potent cytokine acting via various cell-surface receptors, explaining a so-far under-appreciated role of TIMP-1-mediated signaling on immune cells. This, at least partly, resolved why elevated blood levels of TIMP-1 correlate with progression of numerous inflammatory diseases. Here, we emphasize the necessity of unbiased name-independent recognition of structure-function relationships to properly appreciate the biological potential of TIMP-1 and other cytokines in complex physiological processes such as inflammation.

The Role of Extracellular Matrix in Human Neurodegenerative Diseases

The dense neuropil of the central nervous system leaves only limited space for extracellular substances free. The advent of immunohistochemistry, soon followed by advanced diagnostic tools, enabled us to explore the biochemical heterogeneity and compartmentalization of the brain extracellular matrix in exploratory and clinical research alike. The composition of the extracellular matrix is critical to shape neuronal function; changes in its assembly trigger or reflect brain/spinal cord malfunction. In this study, we focus on extracellular matrix changes in neurodegenerative disorders. We summarize its phenotypic appearance and biochemical characteristics, as well as the major enzymes which regulate and remodel matrix establishment in disease. The specifically built basement membrane of the central nervous system, perineuronal nets and perisynaptic axonal coats can protect neurons from toxic agents, and biochemical analysis revealed how the individual glycosaminoglycan and proteoglycan components interact with these molecules. Depending on the site, type and progress of the disease, select matrix components can either proactively trigger the formation of disease-specific harmful products, or reactively accumulate, likely to reduce tissue breakdown and neuronal loss. We review the diagnostic use and the increasing importance of medical screening of extracellular matrix components, especially enzymes, which informs us about disease status and, better yet, allows us to forecast illness.

Assessment of serum and synovial fluid MMP-3 and MPO as biomarkers for psoriatic arthritis and their relation to disease activity indices

Research on biomarkers for the diagnosis and monitoring of psoriatic arthritis (PsA) is ongoing. The purpose of this study was to assess the potential of serum and synovial fluid matrix metalloproteinase-3 (MMP-3) and myeloperoxidase (MPO) as biomarkers for PsA and their relation to disease activity indices. This case-control study involved 156 psoriatic arthritis patients, 50 gonarthrosis patients, and 30 healthy controls. The target parameters were measured with the enzyme-linked immunosorbent assay (ELISA) kits. Serum MMP-3 and MPO levels were elevated in the PsA patients in comparison to the two control groups (p < 0.001) and distinguished PsA from GoA patients and healthy controls with 100% accuracy. Synovial MMP-3 discriminated PsA from GoA patients irrespective of the presence of crystals (AUC = 1.00). PsA patients with crystals in the synovial fluid had elevated synovial MPO (p < 0.001) and were distinguished from PsA patients without crystals with accuracy of 88.50% and from GoA patients with accuracy of 88.30%. Synovial fluid MPO was positively associated with the following indicators of disease activity: VAS (r_s = 0.396); DAPSA (r_s = 0.365); mCPDAI (r_s = 0.323). Synovial MMP-3 showed a weaker positive association with DAPSA (r_s = 0.202) and mCPDAI (r_s = 0.223). Our results suggest that serum MMP-3 and MPO could serve as biomarkers for PsA. Synovial fluid MMP-3 showed a potential as a biomarker for PsA versus GoA. Synovial MPO could be utilized as a marker for the presence of crystals in PsA patients.

Synovial Fluid Cytokine Profile at the Time of Arthroscopy Explains Intermediate-Term Functional Outcomes

BACKGROUND

The intra-articular immune response after ligamentous, meniscal, or focal chondral knee injuries likely plays a role in intra-articular healing and the onset and progression of posttraumatic osteoarthritis.

PURPOSE

To evaluate the association of synovial fluid cytokine concentrations measured at the time of knee arthroscopy with intermediate-term functional outcomes after knee arthroscopy based on the Lysholm score.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

This was a prospective cohort study of patients undergoing arthroscopic knee surgery. Synovial fluid was aspirated from the injured knee immediately before surgical incision, and the concentrations of 10 cytokines were analyzed using immunoassay. Principal component regression was used to create a model to predict patient-reported Lysholm score at a minimum of 5 years postoperatively. Hierarchical clustering was performed to identify groups of patients with similar synovial fluid inflammatory phenotypes. Lysholm scores and cytokine concentrations were compared between clusters.

RESULTS

A total of 26 patients (mean age, 40.33 ± 16.40 years) were included in the analysis. The mean duration between surgery and follow-up was 6.69 ± 0.72 years. A model consisting of 2 principal components (PC1, PC2) explained 62.48% of the variance in the cytokine data and 52.03% of the variance in intermediate-term Lysholm score. Hierarchical clustering resulted in 3 patient clusters based on the principal components used in the regression model. Despite no baseline differences in Lysholm score, cluster 3 demonstrated significantly greater intermediate-term Lysholm score compared with cluster 2 (94.33 vs 76.09, respectively; 95% CI, 5.96-30.52; P = .006) and cluster 1 (94.33 vs 52.33, respectively; 95% CI, 24.09-59.91; P = .003). Cluster 3, when compared with the overall means, was characterized by greater PC1 value (1.01 vs 0.00, respectively; P = .030) and greater PC2 value (0.86 vs 0.00, respectively; P = .002).

CONCLUSION

The concentrations of select synovial fluid cytokines assessed at the time of knee arthroscopy can be used to explain more than half of the variance in intermediate-term functional outcomes.

Proteome and Transcriptome Analysis of Gonads Reveals Intersex in Gigantidas haimaensis

Sex has proven to be one of the most intriguing areas of research across evolution, development, and ecology. Intersex or sex change occurs frequently in molluscs. The deep-sea mussel Gigantidas haimaensis often dominates within Haima cold seep ecosystems, but details of their reproduction remain unknown. Herein, we conducted a combined proteomic and transcriptomic analysis of G. haimaensis gonads to provide a systematic understanding of sexual development in deep-sea bivalves. A total of 2,452 out of 42,238 genes (5.81%) and 288 out of 7,089 proteins (4.06%) were significantly differentially expressed between ovaries and testes with a false discovery rate (FDR) <0.05. Candidate genes involved in sexual development were identified; among 12 differentially expressed genes between sexes, four ovary-biased genes (β-catenin, fem-1, forkhead box L2 and membrane progestin receptor α) were expressed significantly higher in males than females. Combining histological characteristics, we speculate that the males maybe intersex undergoing sex change, and implied that these genes may be involved in the process of male testis converting into female gonads in G. haimaensis. The results suggest that this adaptation may be based on local environmental factors, sedentary lifestyles, and patchy distribution, and sex change may facilitate adaptation to a changing environment and expansion of the population. The findings provide a valuable genetic resource to better understand the mechanisms of sex change and survival strategies in deep-sea bivalves.

Omeprazole prevents stress induced gastric ulcer by direct inhibition of MMP-2/TIMP-3 interactions

The healing of damaged tissues in gastric tract starts with the extracellular matrix (ECM) remodeling by the action of matrix metalloproteinases (MMPs). Particularly, MMP-2 (gelatinase-A) maintains ECM structure and function by degrading type IV collagen, the major component of basement membranes and by clearing denatured collagen. The proteolytic activities of MMPs are critically balanced by endogenous tissue inhibitors of metalloproteinases (TIMPs) and disruption of this balance results in several diseases. The well-known drug omeprazole is a proton pump inhibitor used for curing gastric ulcer. However, the action of omeprazole in ECM remodeling on gastroprotection has never been explored. Herein, using rat model of gastric ulcer, we report that restraint cold stress caused increase apoptosis to surface epithelia of gastric tissues along with TIMP-3 upregulation and inhibition of MMP-2 activity thereon. In contrast, omeprazole treatment suppressed TIMP-3 while increasing MMP-2 activity and thereby, restoring MMP-2/TIMP-3 balance. Additionally, nanomolar binding constant (K_d = 318 nM) of omeprazole with purified MMP-2 indicates a direct effect of omeprazole in restoring MMP-2 activity. Further in silico simulations revealed a plausible mechanism of action of omeprazole for TIMP-3 deactivation. Altogether, omeprazole restores MMP-2 activity and reduces apoptosis while preventing acute stress-induced gastric ulcer that occurs via suppression of nuclear factor kappa B (NF-κB) activity and peroxisome proliferator-activated receptor gamma activity (PPAR-γ). This represents an unprecedented correlation between physical docking of drug molecule to a protease and the severity of organ injury and provides a novel therapeutic approach to prevent stress induced tissue damage.

Melatonin rescues swim stress induced gastric ulceration by inhibiting matrix metalloproteinase-3 via down-regulation of inflammatory signaling cascade

AIM

This study investigated the link between forced swim induced acute gastric ulceration, inflammation and MMP-3 along with the possible mechanism of protective efficacy of melatonin.

MAIN METHODS

We distributed Balb/c mice into four different groups. Group 1 and 2 were given PBS gavage. Group 3 and 4 were given melatonin (60 mg/kg b.wt.) and omeprazole (25 mg/kg b.wt.), respectively, an hour prior to forced swim. Ulcer index, tissue histology, immunohistochemistry, protein carbonylation, lipid peroxidation, Myeloperoxidase, Zymography, Western blotting, reactive oxygen species (ROS), mitochondrial dehydrogenase, mitochondrial transmembrane potential and bioinformatical analysis were performed.

KEY FINDINGS

Our data revealed that gastric ulceration due to forced swim stress is responsible for overproduction of ROS, which may be a prime reason for mitochondrial dysfunction and induction of apoptosis via activation of Caspase-3. ROS is also responsible for p38 phosphorylation which in turn increases the activity of MMP-3 in ulcerated milieu, along with the oxidation of proteins, peroxidation of lipids and altered expression patterns of heat shock protein (HSP)-70. Melatonin is shown to reduce the inflammatory burden in gastric milieu and offers gastroprotection by binding to the active site of MMP-3; thereby inhibiting its activity, as suggested by in silico studies. Melatonin also inhibits the downregulation of HSP-70 and activates p38 dephosphorylation and thereby, it rescues gastric mucosal cells from stress-induced ulceration.

SIGNIFICANCE

Our findings suggest that, melatonin imparts its gastroprotective effect by down-regulating the activation of MAPK-ERK pathway along with binding to the active site of MMP-3.

Changes in the Synovial Fluid Cytokine Profile of the Knee Between an Acute Anterior Cruciate Ligament Injury and Surgical Reconstruction

BACKGROUND

Changes in the intra-articular inflammatory state during the immediate period after an acute anterior cruciate ligament (ACL) rupture are not well defined.

PURPOSE

To evaluate changes in the concentration of select proinflammatory and anti-inflammatory synovial fluid cytokines during the interval between an ACL injury and surgical reconstruction.

STUDY DESIGN

Descriptive laboratory study.

METHODS

In patients with an acute ACL injury, a synovial fluid sample was obtained from the injured knee during the initial office visit within 2 weeks of the inciting traumatic event. An additional synovial fluid sample was collected at the time of ACL reconstruction just before the surgical incision. Synovial fluid samples from both the acute injury and the surgery time points were processed with a protease inhibitor, and the concentrations of 10 cytokines of interest were measured using a multiplex magnetic bead immunoassay. The primary outcome was the change in cytokine concentrations between time points.

RESULTS

A total of 20 patients with a mean age of 30.2 ± 8.3 years were included. The acute injury synovial fluid samples were collected at 6.6 ± 3.8 days after the injury. The surgical synovial fluid samples were collected at 31.6 ± 15.6 days after the acute injury samples. Based on a series of linear mixed-effects models to control for the effect of concomitant meniscal injuries and by-patient variability, there was a statistically significant increase in the concentrations of RANTES and bFGF and a statistically significant decrease in the concentrations of IL-6, MCP-1, MIP-1β, TIMP-1, IL-1Ra, and VEGF between time points.

CONCLUSION

This study demonstrates the ongoing alterations in the intra-articular microenvironment during the initial inflammatory response in the acute postinjury period. We identified 6 synovial fluid cytokines that significantly decreased and 2 that significantly increased between the first clinical presentation shortly after the injury and the time of surgery 1 month later.

CLINICAL RELEVANCE

This study describes the molecular profile of the inflammatory changes between the time of an acute ACL injury and the time of surgical reconstruction 1 month later. A greater understanding of the acute inflammatory response within the knee may be helpful in identifying the optimal timing for a surgical intervention that balances the risk of chondral damage with the likelihood of successful, well-healed reconstruction.

Tissue inhibitor of metalloproteinases 1 is involved in ROS-mediated inflammation via regulating matrix metalloproteinase 1 expression in the sea cucumber Apostichopus japonicus

Tissue inhibitors of metalloproteinases (TIMPs) serve as matrix metalloproteinase (MMP) inhibitors in the pathogenesis of inflammatory diseases in vertebrates. We cloned and characterised the TIMP1 gene from Apostichopus japonicus using RACE approaches (designated as AjTIMP1). For Vibrio splendidus-challenged sea cucumbers, the peak expression of AjTIMP1 mRNAs in coelomocytes was detected at 24 h (23.44-fold) and remained at high levels (4.01-fold) until 72 h. Similarly, AjTIMP1 expression was upregulated in primary coelomocytes exposed to 10 μg mL^-1 LPS. AjTIMP1 was expressed in all tissues, and the highest expression was observed in the body wall. Functional investigation revealed an imbalance in the ratio of AjMMP1/AjTIMP1 in the skin ulceration syndrome (SUS) diseased group; it was sharply up-regulated to 3.97:1 compared with the healthy group. Furthermore, when AjTIMP1 was knocked down using small interfering RNA (siRNA-KD) to 0.4-fold, AjMMP1 and AjMMP19 were upregulated to 1.99- and 1.85-fold, respectively. AjTIMP1 siRNA-KD can promote ROS production by 26.2%, whereas AjMMP1 siRNA-KD can eliminate the increase in ROS. In inflamed tissues, collagen I and III levels were decreased by 33.1% and 33.6%, respectively, in the AjTIMP1 siRNA group at 24 h AjTIMP1 was involved in the inflammatory response by mediating ROS formation and collagen degradation.

Engineering of tissue inhibitor of metalloproteinases TIMP-1 for fine discrimination between closely-related stromelysins MMP-3 and MMP-10

Matrix metalloproteinases (MMPs) have long been known as key drivers in the development and progression of diseases, including cancer and neurodegenerative, cardiovascular, and many other inflammatory and degenerative diseases, making them attractive potential drug targets. Engineering selective inhibitors based upon tissue inhibitors of metalloproteinases (TIMPs), endogenous human proteins that tightly yet nonspecifically bind to the family of MMPs, represents a promising new avenue for therapeutic development. Here, we used a counter-selective screening strategy for directed evolution of yeast-displayed human TIMP-1 to obtain TIMP-1 variants highly selective for the inhibition of MMP-3 in preference over MMP-10. As MMP-3 and MMP-10 are the most similar MMPs in sequence, structure, and function, our results thus clearly demonstrate the capability for engineering full-length TIMP proteins to be highly selective MMP inhibitors. We show using protein crystal structures and models of MMP-3-selective TIMP-1 variants bound to MMP-3 and counter-target MMP-10 how structural alterations within the N-terminal and C-terminal TIMP-1 domains create new favorable and selective interactions with MMP-3 and disrupt unique interactions with MMP-10. While our MMP-3-selective inhibitors may be of interest for future investigation in diseases where this enzyme drives pathology, our platform and screening strategy can be employed for developing selective inhibitors of additional MMPs implicated as therapeutic targets in disease.

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.

Structure-based molecular insights into matrix metalloproteinase inhibitors in cancer treatments

Protease inhibitors are of considerable interest as anticancer agents. Matrix metalloproteinases (MMPs) were the earliest type of proteases considered as anticancer targets. The developments of MMP inhibitors (MMPIs) by pharmaceutical companies can be dated from the early 1980s. Thus far, none of the over 50 MMPIs entering clinical trials have been approved. This work summarizes the reported studies on the structure of MMPs and complexes with ligands and inhibitors, based on which, the authors analyzed the clinical failures of MMPIs in a structural biological manner. Furthermore, MMPs were systematically compared with urokinase, a protease-generating plasmin, which plays similar pathological roles in cancer development; the reasons for the clinical successes of urokinase inhibitors and the clinical failures of MMPIs are discussed.

Regulation of Tumor Metabolism and Extracellular Acidosis by the TIMP-10-CD63 Axis in Breast Carcinoma

A hallmark of malignant solid tumor is extracellular acidification coupled with metabolic switch to aerobic glycolysis. Using the human MCF10A progression model of breast cancer, we show that glycolytic switch and extracellular acidosis in aggressive cancer cells correlate with increased expression of tissue inhibitor of metalloproteinase-1 (TIMP-1), known to induce intracellular signal transduction through the interaction with its cell surface receptor CD63, independent of its metalloproteinase inhibitory function. We found that, in aggressive breast carcinoma, the TIMP-1–CD63 signaling axis induced a metabolic switch by upregulating the rate of aerobic glycolysis, lowering mitochondrial respiration, preventing intracellular acidification, and inducing extracellular acidosis. Carbonic anhydrase IX (CAIX), a regulator of cellular pH through the hydration of metabolically released pericellular CO₂, was identified as a downstream mediator of the TIMP-1–CD63 signaling axis responsible for extracellular acidosis. Consistently with our previous study, the TIMP-1–CD63 signaling promoted survival of breast cancer cells. Interestingly, breast carcinoma cell survival was drastically reduced upon shRNA-mediated knockdown of CAIX expression, demonstrating the significance of CAIX-regulated pH in the TIMP-1–CD63-mediated cancer cell survival. Taken together, the present study demonstrates the functional significance of TIMP-1–CD63–CAXI signaling axis in the regulation of tumor metabolism, extracellular acidosis, and survival of breast carcinoma. We propose that this axis may serve as a novel therapeutic target.

Targeting Dysregulation of Metalloproteinase Activity in Osteoarthritis

Metalloproteinases were first identified as collagen cleaving enzymes and are now appreciated to play important roles in a wide variety of biological processes. The aberrant activity and dysregulation of the metalloproteinase family are linked to numerous diseases including cardiovascular and pulmonary diseases, chronic wounds, cancer, fibrosis and arthritis. Osteoarthritis (OA) is the most prevalent age-related joint disorder that causes pain and disability, but there are no disease-modifying drugs available. The hallmark of OA is loss of articular cartilage and elevated activities of matrix-degrading metalloproteinases are responsible. These enzymes do not exist in isolation and their activity is tightly regulated by a number of processes, such as transcription, proteolytic activation, interaction with their inhibitors, cell surface and extracellular matrix molecules, and endocytic clearance from the extracellular milieu. Here, we describe the functions and roles of metalloproteinase family in OA pathogenesis. We highlight recent studies that have illustrated novel mechanisms regulating their extracellular activity and impairment of such regulations that lead to the development of OA. We also discuss how to stop or slow down the degenerative processes by targeting aberrant metalloproteinase activity, which may in future become therapeutic interventions for the disease.

Current State of Synovial Fluid Biomarkers in Sports Medicine

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While the gross mechanical abnormalities contributing to posttraumatic osteoarthritis (PTOA) have been well described, new research is demonstrating that these insults to the articular cartilage may also initiate changes in the joint microenvironment that seed the development of PTOA.

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A growing amount of literature has identified key biomarkers that exhibit altered expression in the synovial fluid following a knee injury, with a portion of these molecules remaining elevated in the years following an injury.

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These biomarkers have the potential to aid in the early detection of PTOA before radiographic evidence becomes apparent. Furthermore, deciphering the processes that occur within the articular microenvironment after trauma may allow for better identification of therapeutic targets for the prevention and earlier treatment of PTOA.

Identification of invariant chain CD74 as a functional receptor of tissue inhibitor of metalloproteinases-1 (TIMP-1)

Multifunctionality of tissue inhibitor of metalloproteinases-1 (TIMP-1) comprising antiproteolytic as well as cytokinic activity has been attributed to its N-terminal and C-terminal domains, respectively. The molecular basis of the emerging proinflammatory cytokinic activity of TIMP-1 is still not completely understood. The cytokine receptor invariant chain (CD74) is involved in many inflammation-associated diseases and is highly expressed by immune cells. CD74 triggers zeta chain–associated protein kinase-70 (ZAP-70) signaling–associated activation upon interaction with its only known ligand, the macrophage migration inhibitory factor. Here, we demonstrate TIMP-1–CD74 interaction by coimmunoprecipitation and confocal microscopy in cells engineered to overexpress CD74. In silico docking in HADDOCK predicted regions of the N-terminal domain of TIMP-1 (N-TIMP-1) to interact with CD74. This was experimentally confirmed by confocal microscopy demonstrating that recombinant N-TIMP-1 lacking the entire C-terminal domain was sufficient to bind CD74. Interaction of TIMP-1 with endogenously expressed CD74 was demonstrated in the Namalwa B lymphoma cell line by dot blot binding assays as well as confocal microscopy. Functionally, we demonstrated that TIMP-1–CD74 interaction triggered intracellular ZAP-70 activation. N-TIMP-1 was sufficient to induce ZAP-70 activation and interference with the cytokine-binding site of CD74 using a synthetic peptide–abrogated TIMP-1-mediated ZAP-70 activation. Altogether, we here identified CD74 as a receptor and mediator of cytokinic TIMP-1 activity and revealed TIMP-1 as moonlighting protein harboring both cytokinic and antiproteolytic activity within its N-terminal domain. Recognition of this functional TIMP-1–CD74 interaction may shed new light on clinical attempts to therapeutically target ligand-induced CD74 activity in cancer and other inflammatory diseases.

A Biomimetic of Endogenous Tissue Inhibitors of Metalloproteinases: Inhibition Mechanism and Contribution of Composition, Polymer Size, and Shape to the Inhibitory Effect

A biomimetic of endogenous tissue inhibitors of metalloproteinases (TIMPs) was engineered by introducing three binding elements to a synthetic tetrapolymer. We evaluated the contribution of composition, size, and shape of the TIMP-mimicking polymers to the inhibition of BaP1, a P-I class snake venom metalloproteinase (SVMP). Inhibition was achieved when the size of the linear polymer (LP) was comparable to or greater than that of the enzyme, indicating the efficacy requires binding to a significant portion of the enzyme surface in the vicinity of the active site. The efficacy of a low cross-linked polymer hydrogel nanoparticle (NP) of substantially greater molecular weight was comparable to that of the LPs despite differences in size and shape, an important finding for in vivo applications. The abiotic TIMP was effective against two classes of SVMPs in whole snake venom. The results can serve as a design principle for biomimetic polymer inhibitors of enzymes.

Clinical influence of calcium hydroxide intracanal medications on matrix metalloproteinases and tissue inhibitors of metalloproteinases in apical periodontitis

OBJECTIVES

This study investigated the influence of calcium hydroxide intracanal medications on the levels of metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in apical periodontitis (AP).

MATERIALS AND METHODS

Twenty primarily infected root canals with AP were randomly divided into two groups: Ca(OH)₂ + sterile saline solution (SSL) group and Ca(OH)₂ + 2% chlorhexidine gel (CHX gel) group. We collected samples from the periradicular tissue fluid (PTF) before (s1) and after 14 days of intracanal medication (s2). MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 were measured by ELISA assay.

RESULTS

MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 were detected in all PTF samples at s1 and s2 (20/20). At s1, MMP-2 and MMP-9 were detected at higher levels than MMP-1 (p < .05). Higher levels of TIMP-1 than TIMP-2 were found in AP (p < .05). Additionally, we detected higher MMP-1, MMP-2, and MMP-9 over TIMP-1 and TIMP-2 levels in AP (p < .05). At s2, Ca(OH)₂ + SSL was as effective as Ca(OH)₂ + 2% CHX gel in lowering the levels of MMP-1, MMP-2, and MMP-9 after 14 days of intracanal medication, with no significant difference between them (p > .05). Both Ca(OH) ₂ intracanal medications had no significant impact on the levels of TIMP-1 and TIMP-2 (both p > .05). At s2, TIMP-1 levels were higher than TIMP-2 (p < .05). Moreover, there were positive correlations between the levels of MMP-1 and TIMP-1 and MMP-1 and TIMP-2 (p < .05).

CONCLUSIONS

Calcium hydroxide medications effectively lowered the levels of MMP-1, MMP-2, and MMP-9 in periapical tissues after 14 days of treatment, with no difference between them. Moreover, the calcium hydroxide intracanal medications tested here had no impact in TIMP-1 and TIMP-2 in periapical tissues.

CLINICAL RELEVANCE

MMPs and TIMPs play an essential role in the degradation of the extracellular matrix. The imbalance MMPs and TIMPs can cause periapical tissue destruction. Therefore, the reestablishment of the balance between activated MMPs and TIMPs with root canal therapy is essential to restore tissue homeostasis.

Structural characterisation of inhibitory and non-inhibitory MMP-9-TIMP-1 complexes and implications for regulatory mechanisms of MMP-9

MMP-9 plays a number of important physiological functions but is also responsible for many pathological processes, including cancer invasion, metastasis, and angiogenesis. It is, therefore, crucial to understand its enzymatic activity, including activation and inhibition mechanisms. This enzyme may also be partially involved in the "cytokine storm" that is characteristic of COVID-19 disease (SARS-CoV-2), as well as in the molecular mechanisms responsible for lung fibrosis. Due to the variety of processing pathways involving MMP-9 in biological systems and its uniqueness due to the O-glycosylated domain (OGD) and fibronectin-like (FBN) domain, specific interactions with its natural TIMP-1 inhibitor should be carefully studied, because they differ significantly from other homologous systems. In particular, earlier experimental studies have indicated that the newly characterised circular form of a proMMP-9 homotrimer exhibits stronger binding properties to TIMP-1 compared to its monomeric form. However, molecular structures of the complexes and the binding mechanisms remain unknown. The purpose of this study is to fill in the gaps in knowledge. Molecular modelling methods are applied to build the inhibitory and non-inhibitory MMP-9-TIMP-1 complexes, which allows for a detailed description of these structures and should allow for a better understanding of the regulatory processes in which MMP-9 is involved.

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

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

Metalloproteinases in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD) are chronic inflammatory diseases of the gastrointestinal tract, encompassing two main disorders: Crohn's disease (CD) and ulcerative colitis (UC). In both these pathologies, excessive and local immune response against luminal antigens promotes a pathological process leading to various degrees of gut damage. Matrix metalloproteinases (MMPs) are a family of neutral proteases with the ability to degrade all components of extracellular matrix. In physiological conditions, MMPs are produced at very low level and generally in the latent form and are involved in the normal tissue turnover. Their function is inhibited by tissue inhibitors of metalloproteinases (TIMPs). However, in inflamed tissue of IBD patients, MMPs are produced in excess and/or the activity of TIMPs is not sufficient to block MMPs, thereby making a major contribution to the IBD-related mucosal degradation. In this review, we summarize the available evidence on the expression and role of MMPs in IBD.