Matrix metalloproteinase profiling and their roles in disease

Targeting Matrix Metalloproteinase-1, Matrix Metalloproteinase-7, and Serine Protease Inhibitor E1: Implications in preserving lung vascular endothelial integrity and immune modulation in COVID-19

BACKGROUND

SARS-CoV-2 disrupts lung vascular endothelial integrity, contributing to severe COVID-19 complications. However, the molecular mechanisms driving endothelial dysfunction remain underexplored, and targeted therapeutic strategies are lacking.

OBJECTIVE

This study investigates Naringenin-7-O-glucoside (N7G) as a multi-target therapeutic candidate for modulating vascular integrity and immune response by inhibiting MMP1, MMP7, and SERPINE1-key regulators of extracellular matrix (ECM) remodeling and inflammation.

METHODS & RESULTS

RNA-seq analysis of COVID-19 lung tissues identified 17 upregulated N7G targets, including MMP1, MMP7, and SERPINE1, with the latter exhibiting the highest expression. PPI network analysis linked these targets to ECM degradation, IL-17, HIF-1, and AGE-RAGE signaling pathways, and endothelial dysfunction. Disease enrichment associated these genes with idiopathic pulmonary fibrosis and asthma. Molecular docking, 200 ns MD simulations (triplicate), and MMGBSA calculations confirmed N7G's stable binding affinity to MMP1, MMP7, and SERPINE1. Immune profiling revealed increased neutrophils and activated CD4+ T cells, alongside reduced mast cells, NK cells, and naïve B cells, indicating immune dysregulation. Correlation analysis linked MMP1, MMP7, and SERPINE1 to distinct immune cell populations, supporting N7G's immunomodulatory role.

CONCLUSION

These findings suggest that N7G exhibits multi-target therapeutic potential by modulating vascular integrity, ECM remodeling, and immune dysregulation, positioning it as a promising candidate for mitigating COVID-19-associated endothelial dysfunction.

Downregulation of MT2-MMP and MT5-MMP in ulcerative colitis serves a diagnostic predictor and potential therapeutic targets

BACKGROUND

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) characterized by persistent inflammation and tissue remodeling. Matrix metalloproteinases (MMPs) play a key role in extracellular matrix degradation, and their dysregulation is implicated in IBD. However, the specific role of membrane-type MMPs (MT-MMPs) in UC remains underexplored. This study investigates the expression of MT-MMPs in UC patients, including new cases and treatment-resistant patients, and evaluates their expression patterns compared to healthy people.

METHODS AND RESULTS

Colon biopsy samples were collected from three groups: healthy controls (n = 20), newly diagnosed UC patients (n = 20), and UC patients resistant to standard treatments (n = 20). The mRNA expression levels of MT-MMPs were assessed using quantitative real-time PCR. Receiver operating characteristic (ROC) curve analysis was performed to determine the diagnostic utility of these MT-MMPs. Correlation analysis was also conducted to explore the relationship between MT-MMPs and inflammatory markers (CRP, ESR) and vitamin D levels. Out of 6 members of MT-MMPs, MT2-MMP, and MT5-MMP were significantly downregulated in new cases and resistant UC patients compared to controls (P < 0.0001). ROC analysis demonstrated high sensitivity and specificity for MT2-MMP and MT5-MMP in differentiating UC patients from healthy individuals. Additionally, MT2,5-MMP expression was negatively correlated with CRP, ESR, and vitamin D levels, indicating their possible modulation of systematic inflammation.

CONCLUSION

MT2-MMP and MT5-MMP are downregulated in UC and may serve as diagnostic biomarkers for disease severity. The findings highlight the need for further investigation into their therapeutic potential in modulating inflammation and tissue remodeling in UC.

Directed evolution of proteoglycan-modifying enzymes: Functional applications in cervical cancer therapy

The study investigates the therapeutic potential of enzyme variations EP-22, DS-13, and SM-47 in cervical cancer treatment using HeLa and SiHa cell lines, focusing on their effects on cell viability, migration, and molecular targets. The MTT assay findings also show that at a concentration of 50 μg/mL, EP-22 has an IC50 value of 35 % for HeLa cells and 28 % for SiHa cells, a significant dose effect (p < 0.01). EP-22 was not less potent at a lower working concentration of 25 μg/mL and could reduce HeLa cell viability to 78 %. In this case, there were significant changes in the anti-migratory effect, as evidenced by 45 % inhibition of SiHa cell migration and a 12 % wound closure rate compared with 54 % in the untreated cells. The obtained densitometric analysis indicated that in EP-22 treated HeLa cells, syndecan-1 and perlecan protein levels were reduced by approximately 65 % and 57 %, respectively, while the MMP-2 and MMP-9 levels were reduced to about 50 % and 45 %, respectively. Annexin V staining also highlighted a 40 % enhancement in early apoptosis and 25 % in late apoptosis in EP-22 handled cells. These data suggest the potential of EP-22 and its derivatives as therapeutic molecules in cervical cancer treatment, reducing HeLa proliferation by 35 % and SiHa by 28 %, inhibiting SiHa migration by 45 %, and affecting molecular targets involved in adhesion and invasiveness. Future studies must elucidate the effectiveness of in vivo experiments and how these findings were obtained. At 50 μg/mL, EP-22 reduced HeLa and SiHa cell viability by 35 % and 28 %, respectively, with significant dose-dependent effects (p < 0.01). At 25 μg/mL, EP-22 maintained potency, reducing HeLa cell viability to 78 %. EP-22 inhibited SiHa cell migration by 45 % and reduced wound closure rates to 12 % compared to 54 % in untreated cells. This work uses the HeLa and SiHa cell lines to examine the therapeutic potential of enzyme variation EP-22 in cervical cancer. EP-22 showed significant anti-cancer effects at 50 μg/mL doses, reducing cell viability at lower concentrations and achieving an IC50 of 35 % for HeLa cells and 28 % for SiHa cells. It is worth mentioning that EP-22 considerably reduced levels of essential proteins: syndecan-1 (65 %), perlecan (57 %), MMP-2 (50 %), and MMP-9 (45 %), in addition to inhibiting SiHa cell migration by 45 %. Furthermore, annexin V staining showed that treated cells exhibited a 40 % increase in early apoptosis and a 25 % increase in late apoptosis.

A high-resolution view of the immune and stromal cell response to Haemophilus ducreyi infection in human volunteers

Haemophilus ducreyi causes the genital ulcer disease chancroid and cutaneous ulcers in children. To study its pathogenesis, we developed a human challenge model in which we infect the skin on the upper arm of human volunteers with H. ducreyi to the pustular stage of disease. The model has been used to define lesional architecture, describe the immune infiltrate into the infected sites using flow cytometry, and explore the molecular basis of the immune response using bulk RNA-seq. Here, we used single cell RNA-seq (scRNA-seq) and spatial transcriptomics to simultaneously characterize multiple cell types within infected human skin and determine the cellular origin of differentially expressed transcripts that we had previously identified by bulk RNA-seq. We obtained paired biopsies of pustules and wounded (mock infected) sites from five volunteers for scRNA-seq. We identified 13 major cell types, including T- and NK-like cells, macrophages, dendritic cells, as well as other cell types typically found in the skin. Immune cell types were enriched in pustules, and some subtypes within the major cell types were exclusive to pustules. Sufficient tissue specimens for spatial transcriptomics were available from four of the volunteers. T- and NK-like cells were highly associated with multiple antigen presentation cell types. In pustules, type I interferon stimulation was high in areas that were high in antigen presentation-especially in macrophages near the abscess-compared to wounds. Together, our data provide a high-resolution view of the cellular immune response to the infection of the skin with a human pathogen.IMPORTANCEA high-resolution view of the immune infiltrate due to infection with an extracellular bacterial pathogen in human skin has not yet been defined. Here, we used the human skin pathogen Haemophilus ducreyi in a human challenge model to identify on a single cell level the types of cells that are present in volunteers who fail to spontaneously clear infection and form pustules. We identified 13 major cell types. Immune cells and immune-activated stromal cells were enriched in pustules compared to wounded (mock infected) sites. Pustules formed despite the expression of multiple pro-inflammatory cytokines, such as IL-1β and type I interferon. Interferon stimulation was most evident in macrophages, which were proximal to the abscess. The pro-inflammatory response within the pustule may be tempered by regulatory T cells and cells that express indoleamine 2,3-dioxygenase, leading to failure of the immune system to clear H. ducreyi.

Unravelling interplay of serum MMP-7 and TGF- β in diabetic nephropathy - A study from a tertiary centre in eastern India

Background

Diabetic Nephropathy (DN) constitutes nearly half of cases of end stage renal disease. Despite decrease in kidney function, eGFR in the early stages may remain unaltered, making diagnosis difficult pointing towards need of more accurate biomarkers for early detection. Altered serum Matrix Metallo-Proteinase-7 (MMP-7) and transforming growth factor- β (TGF-β) has been noted independently in diabetic complications. The role of MMP-7 with TGF-β together has been highlighted in extracellular matrix remodelling in kidneys of diabetic rats. Interaction between MMP-7 with TGF- β in DN cases is scarce. Hence, the objective of present study is to evaluate role of serum MMP-7 and TGF-β in DN.

Methods

This case control Study included 61 DN cases, 61 diabetes Mellitus controls and 61 healthy controls. After clinical evaluation routine biochemical parameters were estimated along with serum MMP-7 and TGF-β. They were analysed in relation to glycemia and eGFR along with correlation analysis.

Results

Serum MMP-7 and TGF-β registered significant rise (P value-<0.001) in DN cases in comparison to control groups. Their substantial association with each other and with glycaemic status and renal function was noted in the correlational analysis. Diagnostic accuracy of MMP-7 and TGF-β for DN was also noted with significant sensitivity and specificity. Multiple regression analysis documented MMP-7 as an independent determinant for Diabetic nephropathy.

Conclusion

Serum MMP-7 along with TGF-β play significant role in the pathogenesis of DN. Prospective longitudinal study with future Genetic analysis for their expression is needed to establish their role in disease diagnosis and progression.

Matrix metalloproteinases: Master regulators of tissue morphogenesis

The matrix metalloproteinases (MMPs) are a class of zinc proteases that aid in breaking most of the extracellular matrix's (ECM) constituents. Additionally, MMPs play a part in processing elements that affect inflammation, cell development and proliferation, and many more. In vivo genetic study of the Drosophila MMPs Mmp1 and Mmp2 reveals they are essential for tissue remodeling but not embryonic development. The canonical and conserved MMP domain organization is present in both fly MMPs. Because Mmp2 appeared to be membrane-anchored and Mmp1 appeared to be released, the pericellular localization of Drosophila MMPs has been used to classify them. This suggests that the protein's localization is the critical distinction in this small MMP family. The signal sequence, the propeptide, the catalytic domain, and the hemopexin-like domain are among the numerous domains found in MMPs. Following secretion from the extracellular environment to the endoplasmic reticulum, the pre-domain, also known as the signal sequence, serves to direct MMP production. MMPs of the secretory and membrane types (MT-MMPs) are two groups of MMPs that have been widely recognized. Subgroups of MMPs are categorized based on their structure and function. While analysis of the intracellular activity of human MMPs is challenging because the human genome contains around 23 distinct MMPs with overlapping functions, only two MMPs, dMMP1 and dMMP2, are encoded by the Drosophila melanogaster genome. On the other hand, the balance between MMPs and the family members are implicated in various pathophysiology/progression of diseases, but whether or not the mechanisms of MMP inhibition are not clearly understood as master regulators. In this review, we outline the role of MMPs as master regulators of tissue morphogenesis.

Nanostructured lipid carriers for enhanced batimastat delivery across the blood-brain barrier: an in vitro study for glioblastoma treatment

Glioblastoma presents a significant treatment challenge due to the blood-brain barrier (BBB) hindering drug delivery, and the overexpression of matrix metalloproteinases (MMPs), which promotes tumor invasiveness. This study introduces a novel nanostructured lipid carrier (NLC) system designed for the delivery of batimastat, an MMP inhibitor, across the BBB and into the glioblastoma microenvironment. The NLCs were functionalized with epidermal growth factor (EGF) and a transferrin receptor-targeting construct to enhance BBB penetration and entrapment within the tumor microenvironment. NLCs were prepared by ultrasonicator-assisted hot homogenization, followed by surface functionalization with EGF and the construct though carbodiimide chemistry. The construct was successfully conjugated with an efficiency of 81%. Two functionalized NLC formulations, fMbat and fNbat, differing in the surfactant amount, were characterized. fMbat had a size of 302 nm, a polydispersity index (PDI) of 0.298, a ζ-potential (ZP) of -27.1 mV and an 85% functionalization efficiency (%FE), whereas fNbat measured 285 nm, with a PDI of 0.249, a ZP of -28.6 mV and a %FE of 92%. Both formulations achieved a drug loading of 0.42 μg/mg. In vitro assays showed that fNbat was cytotoxic and failed to cross the BBB, while fMbat showed cytocompatibility at concentrations 10 times higher than the drug's IC50. Additionally, fMbat inhibited MMP-2 activity between 11 and 62% across different cell lines and achieved a three-fold increase in BBB penetration upon functionalization. Our results suggest that the fMbat formulation has potential for enhancing GB treatment by overcoming current drug delivery limitations and may be combined with other therapeutic strategies for improved outcomes.

Causal relationship between matrix metalloproteinase and pulmonary embolism: a bidirectional two-sample Mendelian randomization study

This study evaluated the causal relationship between matrix metalloproteinases (MMPs) and pulmonary embolism using data from the genome-wide association study (GWAS) of pulmonary embolism from the UK Biobank and a GWAS dataset of MMPs based on 5,457 Icelanders aged 65 years and older. MR-Egger, MR-PRESSO, Cochran's Q, and leave-one-out were used for sensitivity analysis. The Mendelian randomization (MR) analysis, based on the IVW analysis, indicated an elevated risk for pulmonary embolism in association with MMP19 (OR = 1.0009, 95%CI: 1-1.0017, P = 0.041), consistent with the weighted median method results (P = 0.015). In addition, despite the negative result from the IVW method (P = 0.554), the weighted median analysis suggested a reduced risk for pulmonary embolism related to MMP12 (OR = 0.9992, 95%CI: 0.9984-1, P = 0.038). No causal associations were found for the other MMPs (including MMP1, MMP2, MMP3, MMP7, MMP8, MMP9, MMP10, MMP13, MMP14, MMP16, MMP17, and MMP20) on pulmonary embolism (all P > 0.05). The reverse MR analysis revealed no causal associations between pulmonary embolism as exposure and MMPs as outcomes. Sensitivity analyses confirmed the robustness of these findings. In conclusion, this MR analysis revealed the potential causal relationship between MMPs and pulmonary embolism, suggesting that measuring MMPs could help identify people at higher risk of pulmonary embolism, but further research is needed.

Derivatives of D(-)-glutamine-based MMP-2 inhibitors as an effective remedy for the management of chronic myeloid leukemia-Part-III: Synthesis, biological screening and in silico binding interaction analysis

Tyrosine kinase inhibitors (TKIs) have markedly improved the overall survival rate of patients with chronic myeloid leukemia (CML), enabling them to achieve a normal life expectancy. However, toxicity, relapse, and drug resistance continue to pose major challenges in the clinical treatment of CML. The progression of leukemia is directly connected to higher expression levels and enzymatic actions of matrix metalloproteinase-2 (MMP-2). It is also associated with increased expression and enzymatic actions of matrix metalloproteinase-9 (MMP-9). From this perspective, MMP-2 and MMP-9 offers a promising strategy for developing novel therapeutic molecules that could be effective in treating CML. This study is the Part-III of D(-)-glutamine-based MMP-2 inhibitors series for the management of chronic myeloid leukemia. Fourteen newly synthesized p-tosyl-D(-)-glutamine derivatives were examined in cell culture-based antileukemic assays and also evaluated for their ability to inhibit MMPs. The lead compounds 5g and 5j demonstrated the most promising antileukemic potential. Compounds 5g and 5j are safe for normal cells and effectively block gelatinases (MMP-2 and MMP-9). The best active molecule 5g induced significant apoptosis. Compound 5g reduced MMP-2 levels in the K562 cell line. It also had strong antiangiogenic effects in the ACHN cell line. The strongest MMP-2 inhibitor, 5g, had stable binding at the MMP-2 active site, which is linked to its effective inhibition of MMP-2. In conclusion, these p-tosyl-D(-)-glutamine derivatives are promising MMP-2 inhibitors. They have strong anti-CML effects and should be studied more for future CML treatment.

Escherichia coli induced matrix metalloproteinase-9 activity and type IV collagen degradation is regulated by progesterone in human maternal decidual

BACKGROUND

Escherichia coli (E. coli) is one of the main bacteria associated with preterm premature rupture of membranes by increasing pro-matrix metalloproteinase 9 (proMMP-9) and degradation of type IV collagen in human feto-maternal interface (HFMi). proMMP-9 is regulated by progesterone (P4) but it is unclear whether P4 inhibits proMMP in human maternal decidual (MDec). This study aimed to determine a role of P4 on proMMP-2 and - 9 and type IV collagen induced by E. coli infection in MDec.

METHODS

Nine HFMi were mounted in a Transwell system. MDec was stimulated with P4 or E. coli for 3-, 6-, or 24-hours. proMMP-2, -9 and type IV collagen were assessed.

RESULTS

Gelatin zymography revealed an increase in proMMP-9 after 3, 6, and 24 h of stimulating MDec with E. coli. Using immunofluorescence, it was confirmed the increase in the HFMi tissue and a reduction on the amount of type IV collagen leading to the separation of fetal amniochorion and MDEc. The degradative activity of proMMP-9 was reduced by 20% by coincubation with P4.

CONCLUSIONS

P4 modulates the activity of proMMP-9 induced by E. coli stimulation but it was unable to completely reverse the degradation of type IV collagen in human MDec tissue.

Deciphering Collagen Phenotype Dynamics Regulators: Insights from In-Silico Analysis

Collagen (Col) types I and III are integral components in wound healing and tissue regeneration, influencing tissue development, homeostasis, and related pathologies. Col I and Col III expression changes during different stages of wound healing and understanding the regulation of collagen phenotype determination is crucial for unraveling the complexities of these processes. Transcription factors and microRNAs, directly and indirectly, play a critical role in regulating collagen expression, however, a comprehensive understanding of the factors regulating Col I and III phenotypes remains elusive. This critically analyzed published reports with focuses on various factors regulating the expression of Col I and Col III at the transcriptional and translational levels. We performed bioinformatics analysis with an input of proinflammatory mediators, growth factors, elastases, and matrix metalloproteinases and predicted transcription factors and microRNAs involved in the regulation of collagen expression. Network analysis revealed an interaction between genes, transcription factors, and microRNAs and provided a holistic view of the regulatory landscape governing collagen expression and unveils intricate interconnections. This analysis lays a founda-tional framework for guiding future research and therapeutic interventions to promote extracellular matrix remodeling, wound healing, and tissue regeneration after an injury by modulating collagen expression. In essence, this scientific groundwork offers a comprehensive exploration of the regulatory dynamics in collagen synthesis, serving as a valuable resource for advancing both basic research and clinical interventions in tissue repair.

Idiopathic pulmonary fibrosis (IPF): Diagnostic routes using novel biomarkers

Idiopathic pulmonary fibrosis (IPF) diagnosis is still the diagnosis of exclusion. Differentiating from other forms of interstitial lung diseases (ILDs) is essential, given the various therapeutic approaches. The IPF course is now unpredictable for individual patients, although some genetic factors and several biomarkers have already been associated with various IPF prognoses. Since its early stages, IPF may be asymptomatic, leading to a delayed diagnosis. The present review critically examines the recent literature on molecular biomarkers potentially useful in IPF diagnostics. The examined biomarkers are grouped into breath and sputum biomarkers, serologically assessed extracellular matrix neoepitope markers, and oxidative stress biomarkers in lung tissue. Fibroblasts and complete blood count have also gained recent interest in that respect. Although several biomarker candidates have been profiled, there has yet to be a single biomarker that proved specific to the IPF disease. Nevertheless, various IPF biomarkers have been used in preclinical and clinical trials to verify their predictive and monitoring potential.

Time trajectories and within-subject correlations of matrix metalloproteinases 3, 8, 9, 10, 12, and 13 serum levels and their ability to predict mortality in polytraumatized patients: a pilot study

BACKGROUND

Managing polytrauma victims poses a significant challenge to clinicians since applying the same therapy to patients with similar injury patterns may result in different outcomes. Using serum biomarkers hopefully allows for treating each multiple injured in the best possible individual way. Since matrix metalloproteinases (MMPs) play pivotal roles in various physiological processes, they might be a reliable tool in polytrauma care.

METHODS

We evaluated 24 blunt polytrauma survivors and 12 fatalities (mean age, 44.2 years, mean ISS, 45) who were directly admitted to our Level I trauma center and stayed at the intensive care unit for at least one night. We determined their MMP3, MMP8, MMP9, MMP10, MMP12, and MMP13 serum levels at admission (day 0) and on days 1, 3, 5, 7, and 10.

RESULTS

Median MMP8, MMP9, and MMP12 levels immediately rose after the polytrauma occurred; however, they significantly decreased from admission to day 1 and significantly increased from day 1 to day 10, showing similar time trajectories and (very) strong correlations between each two of the three enzyme levels assessed at the same measurement point. For a two-day lag, autocorrelations were significant for MMP8 (- 0.512) and MMP9 (- 0.302) and for cross-correlations between MMP8 and MMP9 (- 0.439), MMP8 and MMP12 (- 0.416), and MMP9 and MMP12 (- 0.307). Moreover, median MMP3, MMP10, and MMP13 levels significantly increased from admission to day 3 and significantly decreased from day 3 to day 10, showing similar time trajectories and an (almost) strong association between every 2 levels until day 7. Significant cross-correlations were detected between MMP3 and MMP10 (0.414) and MMP13 and MMP10 (0.362). Finally, the MMP10 day 0 level was identified as a predictor for in-hospital mortality. Any increase of the MMP10 level by 200 pg/mL decreased the odds of dying by 28.5%.

CONCLUSIONS

The time trajectories of the highly varying individual MMP levels elucidate the involvement of these enzymes in the endogenous defense response following polytrauma. Similar time courses of MMP levels might indicate similar injury causes, whereas lead-lag effects reveal causative relations between several enzyme pairs. Finally, MMP10 abundantly released into circulation after polytrauma might have a protective effect against dying.

Assessing Sarcocornia as a Salt Substitute: Effects on Lipid Profile and Gelatinase Activity

Sodium, although essential for life, is a key factor in changes in vascular function and cardiovascular disease when consumed in excess. Sarcocornia spp., a halophyte plant with many nutritional benefits, presents itself as a promising substitute for the consumption of purified salt. Matrix metalloproteinases (MMPs) 2 and 9 are widely studied due to their action in physiological processes and as biomarkers at the diagnostic level due to their increased expression in inflammatory processes. This study aimed to evaluate whether replacing salt with Sarcocornia perennis (S. perennis) powder in healthy young people leads to an improvement in biochemical profiles and the attenuation of MMP-2 and MMP-9 activity. In the present study, 30 participants were randomized into a control group that consumed salt and an intervention group that replaced salt with powdered S. perennis. The evaluation of the biochemical parameters was carried out by the spectrophotometry method, and the evaluation of MMP activity was carried out by zymography. A significant decrease was observed in the intervention group in total cholesterol, high-density lipoprotein cholesterol (HDL-c), and creatinine (p-value ≤ 0.05), along with lower but not significantly different mean values of triglycerides. Regarding MMP activity after the intervention, a lower mean value was observed for MMP-9 activity, with there being higher mean values for MMP-2 activity, both with p-values ≥ 0.05. The results confirmed that the consumption of S. perennis is a beneficial choice for health regarding the lipid profile. The evaluation of MMP activity indicated the potential of S. perennis in the regulation of MMP-9 activity in healthy individuals, along with the need for the further study of these proteases in individuals with pathologies.

Serum levels of matrix metalloproteinases 1, 2, and 7, and their tissue inhibitors 1, 2, 3, and 4 in polytraumatized patients: Time trajectories, correlations, and their ability to predict mortality

There has been limited research on assessing metalloproteinases (MMPs) 1, 2, and 7, as well as their tissue inhibitors (TIMPs) 1, 2, 3, and 4 in the context of polytrauma. These proteins play crucial roles in various physiological and pathological processes and could be a reliable tool in polytrauma care. We aimed to determine their clinical relevance. We assessed 24 blunt polytrauma survivors and 12 fatalities (mean age, 44.2 years, mean ISS, 45) who were directly admitted to our Level I trauma center and spent at least one night in the intensive care unit. We measured serum levels of the selected proteins on admission (day 0) and days 1, 3, 5, 7, and 10. The serum levels of the seven proteins varied considerably among individuals, resulting in similar median trend curves for TIMP1 and TIMP4 and for MMP1, MMP2, TIMP2, and TIMP3. We also found a significant interrelationship between the MMP2, TIMP2, and TIMP3 levels at the same measurement points. Furthermore, we calculated significant cross-correlations between MMP7 and MMP1, TIMP1 and MMP7, TIMP3 and MMP1, TIMP3 and MMP2, and TIMP4 and TIMP3 and an almost significant correlation between MMP7 and TIMP1 for a two-day-lag. The autocorrelation coefficient reached statistical significance for MMP1 and TIMP3. Finally, lower TIMP1 serum levels were associated with in-hospital mortality upon admission. The causal effects and interrelationships between selected proteins might provide new insights into the interactions of MMPs and TIMPs. Identifying the underlying causes might help develop personalized therapies for patients with multiple injuries. Administering recombinant TIMP1 or increasing endogenous production could improve outcomes for those with multiple injuries. However, before justifying further investigations into basic research and clinical relevance, our findings must be validated in a multicenter study using independent cohorts to account for clinical and biological variability.

Matrix metalloproteinases at a glance

Matrix metalloproteinases (MMPs) are a family of zinc-dependent proteinases that belong to the group of endopeptidases or matrixins. They are able to cleave a plethora of substrates, including components of the extracellular matrix and cell-surface-associated proteins, as well as intracellular targets. Accordingly, MMPs play key roles in a variety of physiological and pathological processes, such as tissue homeostasis and cancer cell invasion. MMP activity is exquisitely regulated at several levels, including pro-domain removal, association with inhibitors, intracellular trafficking and transport via extracellular vesicles. Moreover, the regulation of MMP activity is currently being rediscovered for the development of respective therapies for the treatment of cancer, as well as infectious, inflammatory and neurological diseases. In this Cell Science at a Glance article and the accompanying poster, we present an overview of the current knowledge regarding the regulation of MMP activity, the intra- and extra-cellular trafficking pathways of these enzymes and their diverse groups of target proteins, as well as their impact on health and disease.

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.