Extracellular regulation of metalloproteinases

Porphyromonas gingivalis GroEL accelerates abdominal aortic aneurysm formation by matrix metalloproteinase-2 SUMOylation in vascular smooth muscle cells: A novel finding for the activation of MMP-2

Infection is a known cause of abdominal aortic aneurysm (AAA), and matrix metalloproteases-2 (MMP-2) secreted by vascular smooth muscle cells (SMCs) plays a key role in the structural disruption of the middle layer of the arteries during AAA progression. The periodontal pathogen Porphyromonas gingivalis is highly associated with the progression of periodontitis. GroEL protein of periodontal pathogens is an important virulence factor that can invade the body through either the bloodstream or digestive tract and is associated with numerous systemic diseases. Although P. gingivalis aggravates AAA by increasing the expression of MMP-2 in animal studies, the molecular mechanism through which P. gingivalis regulates the expression of MMP-2 is still unknown and requires further investigation. In this study, we first confirmed through animal experiments that P. gingivalis GroEL promotes MMP-2 secretion from vascular SMCs, thereby aggravating Ang II-induced aortic remodeling and AAA formation. In addition, rat vascular SMCs and A7r5 cells were used to investigate the underlying mechanisms in vitro. The results demonstrated that GroEL can promote the interaction between the K639 site of MMP-2 and SUMO-1, leading to MMP-2 SUMOylation, which inhibits the reoccurrence of non-K639-mediated monoubiquitylation. Hence, the monoubiquitylation-mediated lysosomal degradation of MMP-2 is inhibited, consequently promoting MMP-2 stability and production. SUMOylation may facilitate intra-endoplasmic reticulum (ER) and Golgi trafficking of MMP-2, thereby enhancing its transport capacity. In conclusion, this is the first report demonstrating the presence of a novel posttranslational modification, SUMOylation, in the MMP family, suggesting that P. gingivalis GroEL may exacerbate AAA formation by increasing MMP-2 production through SUMOylation in vascular SMCs. This study also provides a novel perspective on the role of SUMOylation in MMP-2-induced systemic diseases.

Matrix metalloproteinases targeting in prostate cancer

Prostate cancer (PCa) is one of the most common tumors affecting men all over the world. PCa has brought a huge health burden to men around the world, especially for elderly men, but its pathogenesis is unclear. In prostate cancer, epigenetic inheritance plays an important role in the development, progression, and metastasis of the disease. An important role in cancer invasion and metastasis is played by matrix metalloproteinases (MMPs), zinc-dependent proteases that break down extracellular matrix. We review two important forms of epigenetic modification and the role of matrix metalloproteinases in tumor regulation, both of which may be of significant value as novel biomarkers for early diagnosis and prognosis monitoring. The author considers that both mechanisms have promising therapeutic applications for therapeutic agent research in prostate cancer, but that efforts should be made to mitigate or eliminate the side effects of drug therapy in order to maximize quality of life of patients. The understanding of epigenetic modification, MMPs, and their inhibitors in the functional regulation of prostate cancer is gradually advancing, it will provide a new technical means for the prevention of prostate cancer, early diagnosis, androgen-independent prostate cancer treatment, and drug research.

MMP2 and MMP9 are associated with the pathogenesis of recurrent pregnancy loss through protein expression rather than genetic polymorphism

Matrix metalloproteinases (MMPs) degrade extracellular matrix proteins and are important for placenta formation during early pregnancy. Recurrent pregnancy loss (RPL) is associated with abnormalities in endometrial extracellular matrix remodeling. This study aimed to elucidate the roles of MMP2 and MMP9 in RPL pathogenesis. In total, 295 women with a history of RPL and 101 controls were included in this genetic study. Genotype analysis was performed using polymerase chain reaction (PCR) restriction fragment length polymorphisms. For proteolytic analysis, decidua and villi were collected from 10 RPL-miscarried women with normal fetal chromosomes (NC) and 19 women with fetal chromosome aberrations (AC). The expression of MMP2 and MMP9 in the decidua and villi was measured by IHC and ELISA. All samples were collected after obtaining informed consent. There were no statistically significant differences in MMP2-735 C/T and MMP9-1562 C/T frequencies between women with RPL and the controls. There was no significant difference in MMP2 expression levels in the villi; however, MMP9 expression was significantly higher in normal fetal chromosomes. In the decidua, the expression of MMP2 in the NC group was significantly lower, and MMP9 in the NC group was significantly higher than in the AC group. Although no differences in MMP2-735 C/T and MMP9-1562 C/T gene polymorphisms were observed in the present study, it is suggested that differences at the protein level are involved in the pathogenesis of RPL since MMP expression is not only regulated by genes but also by local inflammation and various inductive signals.

Substrate O-glycosylation actively regulates extracellular proteolysis

Extracellular proteolysis critically regulates cellular and tissue responses and is often dysregulated in human diseases. The crosstalk between proteolytic processing and other major post-translational modifications (PTMs) is emerging as an important regulatory mechanism to modulate protease activity and maintain cellular and tissue homeostasis. Here, we focus on matrix metalloproteinase (MMP)-mediated cleavages and N-acetylgalactosamine (GalNAc)-type of O-glycosylation, two major PTMs of proteins in the extracellular space. We investigated the influence of truncated O-glycan trees, also referred to as Tn antigen, following the inactivation of C1GALT1-specific chaperone 1 (COSMC) on the general and MMP9-specific proteolytic processing in MDA-MB-231 breast cancer cells. Quantitative assessment of the proteome and N-terminome using terminal amine isotopic labelling of substrates (TAILS) technology revealed enhanced proteolysis by MMP9 within the extracellular proteomes of MDA-MB-231 cells expressing Tn antigen. In addition, we detected substantial modifications in the proteome and discovered novel ectodomain shedding events regulated by the truncation of O-glycans. These results highlight the critical role of mature O-glycosylation in fine-tuning proteolytic processing and proteome homeostasis by modulating protein susceptibility to proteolytic degradation. These data suggest a complex interplay between proteolysis and O-GalNAc glycosylation, possibly affecting cancer phenotypes.

Small molecular exogenous modulators of active forms of MMPs

Matrix metalloproteinases (MMPs) are endopeptidases, and their activity depends on calcium and zinc metal ions. These enzymes are expressed originally in zymogenic form, where the active site of proteins is closed by a prodomain which is removed during activation. A homeostatic balance of their activity is primarily regulated by a 'cysteine switch' located on a consensus sequence of the prodomain and natural endogenous inhibitors, called tissue inhibitors of metalloproteinases (TIMPs). Breakage of this homeostasis may lead to various pathological conditions, which may require further activation and/or inhibition of these enzymes to regenerate that balance. Here, we report four modulators, more specifically, three inhibitors (I1, I2 and I3), and one exogenous activator (L) of the active form of human collagenase MMP-1 (without prodomain). The results were confirmed by binding studies using fluorescence-based enzyme assays.

Novel insights into the multifaceted and tissue-specific roles of the endocytic receptor LRP1

Receptor-mediated endocytosis provides a mechanism for the selective uptake of specific molecules thereby controlling the composition of the extracellular environment and biological processes. The low-density lipoprotein receptor-related protein 1 (LRP1) is a widely expressed endocytic receptor that regulates cellular events by modulating the levels of numerous extracellular molecules via rapid endocytic removal. LRP1 also participates in signalling pathways through this modulation as well as in the interaction with membrane receptors and cytoplasmic adaptor proteins. LRP1 SNPs are associated with several diseases and conditions such as migraines, aortic aneurysms, cardiopulmonary dysfunction, corneal clouding, and bone dysmorphology and mineral density. Studies using Lrp1 KO mice revealed a critical, nonredundant and tissue-specific role of LRP1 in regulating various physiological events. However, exactly how LRP1 functions to regulate so many distinct and specific processes is still not fully clear. Our recent proteomics studies have identified more than 300 secreted proteins that either directly interact with LRP1 or are modulated by LRP1 in various tissues. This review will highlight the remarkable ability of this receptor to regulate secreted molecules in a tissue-specific manner and discuss potential mechanisms underpinning such specificity. Uncovering the depth of these "hidden" specific interactions modulated by LRP1 will provide novel insights into a dynamic and complex extracellular environment that is involved in diverse biological and pathological processes.

DNA methylation landscape in pregnancy-induced hypertension: progress and challenges

Gestational hypertension (PIH), especially pre-eclampsia (PE), is a common complication of pregnancy. This condition poses significant risks to the health of both the mother and the fetus. Emerging evidence suggests that epigenetic modifications, particularly DNA methylation, may play a role in initiating the earliest pathophysiology of PIH. This article describes the relationship between DNA methylation and placental trophoblast function, genes associated with the placental microenvironment, the placental vascular system, and maternal blood and vascular function, abnormalities of umbilical cord blood and vascular function in the onset and progression of PIH, as well as changes in DNA methylation in the progeny of PIH, in terms of maternal, fetal, and offspring. We also explore the latest research on DNA methylation-based early detection, diagnosis and potential therapeutic strategies for PIH. This will enable the field of DNA methylation research to continue to enhance our understanding of the epigenetic regulation of PIH genes and identify potential therapeutic targets.

Dynamic changes in immune cell populations by AXL kinase targeting diminish liver inflammation and fibrosis in experimental MASH

Background and aims

Metabolic dysfunction-associated steatohepatitis (MASH) is a significant health concern with limited treatment options. AXL, a receptor tyrosine kinase activated by the GAS6 ligand, promotes MASH through activation of hepatic stellate cells and inflammatory macrophages. This study identified cell subsets affected by MASH progression and the effect of AXL inhibition.

Methods

Mice were fed chow or different fat-enriched diets to induce MASH, and small molecule AXL kinase inhibition with bemcentinib was evaluated. Gene expression was measured by qPCR. Time-of-flight mass cytometry (CyTOF) used single cells from dissociated livers, acquired on the Fluidigm Helios, and cell populations were studied using machine learning.

Results

In mice fed different fat-enriched diets, liver steatosis alone was insufficient to elevate plasma soluble AXL (sAXL) levels. However, in conjunction with inflammation, sAXL increases, serving as an early indicator of steatohepatitis progression. Bemcentinib, an AXL inhibitor, effectively reduced proinflammatory responses in MASH models, even before fibrosis appearance. Utilizing CyTOF analysis, we detected a decreased population of Kupffer cells during MASH while promoting infiltration of monocytes/macrophages and CD8+ T cells. Bemcentinib partially restored Kupffer cells, reduced pDCs and GzmB- NK cells, and increased GzmB+CD8+ T cells and LSECs. Additionally, AXL inhibition enhanced a subtype of GzmB+CD8+ tissue-resident memory T cells characterized by CX3CR1 expression. Furthermore, bemcentinib altered the transcriptomic landscape associated with MASH progression, particularly in TLR signaling and inflammatory response, exhibiting differential cytokine expression in the plasma, consistent with liver repair and decreased inflammation.

Conclusion

Our findings highlight sAXL as a biomarker for monitoring MASH progression and demonstrate that AXL targeting shifted liver macrophages and CD8+ T-cell subsets away from an inflammatory phenotype toward fibrotic resolution and organ healing, presenting a promising strategy for MASH treatment.

Dental Pulp Stem Cells Modulate Inflammasome Pathway and Collagen Deposition of Dermal Fibroblasts

Fibrosis is a pathological condition consisting of a delayed deposition and remodeling of the extracellular matrix (ECM) by fibroblasts. This deregulation is mostly triggered by a chronic stimulus mediated by pro-inflammatory cytokines, such as TNF-α and IL-1, which activate fibroblasts. Due to their anti-inflammatory and immunosuppressive potential, dental pulp stem cells (DPSCs) could affect fibrotic processes. This study aims to clarify if DPSCs can affect fibroblast activation and modulate collagen deposition. We set up a transwell co-culture system, where DPSCs were seeded above the monolayer of fibroblasts and stimulated with LPS or a combination of TNF-α and IL-1β and quantified a set of genes involved in inflammasome activation or ECM deposition. Cytokines-stimulated co-cultured fibroblasts, compared to unstimulated ones, showed a significant increase in the expression of IL-1β, IL-6, NAIP, AIM2, CASP1, FN1, and TGF-β genes. At the protein level, IL-1β and IL-6 release as well as FN1 were increased in stimulated, co-cultured fibroblasts. Moreover, we found a significant increase of MMP-9 production, suggesting a role of DPSCs in ECM remodeling. Our data seem to suggest a crosstalk between cultured fibroblasts and DPSCs, which seems to modulate genes involved in inflammasome activation, ECM deposition, wound healing, and fibrosis.

Matrisome Transcriptome Dynamics during Tissue Aging

The extracellular matrix (ECM) is a complex three-dimensional network of macromolecules that provides structural support for the cells and plays a significant role in tissue homeostasis and repair. Growing evidence indicates that dysregulation of ECM remodeling contributes to various pathological conditions in the body, including age-associated diseases. In this work, gene expression data of normal human tissues obtained from the Genotype-Tissue Expression project, as well as data from MatrisomeDB 2.0, the ECM-protein knowledge database, are used to estimate the age-dependent matrisome transcriptome dynamics in the blood, heart, brain, liver, kidneys, lungs, and muscle. Differential gene expression (DE) analysis revealed dozens of matrisome genes encoding both structural elements of the ECM and ECM-associated proteins, which had a tissue-specific expression profile with age. Among common DE genes that changed expression with age in at least three tissues, COL18A1, MFAP1, IGFBP7, AEBP1, LTBP2, LTBP4, LG14, EFEMP1, PRELP, BGN, FAM20B, CTSC, CTSS, and CLEC2B were observed. The findings of the study also reveal that there are sex-specific alterations during aging in the matrisome gene expression. Taken together, the results obtained in this work may help in understanding the role of the ECM in tissue aging and might prove valuable for the future development of the field of ECM research in general.

The involvement of the Wnt/β-catenin signaling cascade in fibrosis progression and its therapeutic targeting by relaxin

Organ scarring, referred to as fibrosis, results from a failed wound-healing response to chronic tissue injury and is characterised by the aberrant accumulation of various extracellular matrix (ECM) components. Once established, fibrosis is recognised as a hallmark of stiffened and dysfunctional tissues, hence, various fibrosis-related diseases collectively contribute to high morbidity and mortality in developed countries. Despite this, these diseases are ineffectively treated by currently-available medications. The pro-fibrotic cytokine, transforming growth factor (TGF)-β1, has emerged as the master regulator of fibrosis progression, owing to its ability to promote various factors and processes that facilitate rapid ECM synthesis and deposition, whilst negating ECM degradation. TGF-β1 signal transduction is tightly controlled by canonical (Smad-dependent) and non-canonical (MAP kinase- and Rho-associated protein kinase-dependent) intracellular protein activity, whereas its pro-fibrotic actions can also be facilitated by the Wnt/β-catenin pathway. This review outlines the pathological sequence of events and contributing roles of TGF-β1 in the progression of fibrosis, and how the Wnt/β-catenin pathway contributes to tissue repair in acute disease settings, but to fibrosis and related tissue dysfunction in synergy with TGF-β1 in chronic diseases. It also outlines the anti-fibrotic and related signal transduction mechanisms of the hormone, relaxin, that are mediated via its negative modulation of TGF-β1 and Wnt/β-catenin signaling, but through the promotion of Wnt/β-catenin activity in acute disease settings. Collectively, this highlights that the crosstalk between TGF-β1 signal transduction and the Wnt/β-catenin cascade may provide a therapeutic target that can be exploited to broadly treat and reverse established fibrosis.

Regulation of Peptidase Activity beyond the Active Site in Human Health and Disease

This comprehensive review addresses the intricate and multifaceted regulation of peptidase activity in human health and disease, providing a comprehensive investigation that extends well beyond the boundaries of the active site. Our review focuses on multiple mechanisms and highlights the important role of exosites, allosteric sites, and processes involved in zymogen activation. These mechanisms play a central role in shaping the complex world of peptidase function and are promising potential targets for the development of innovative drugs and therapeutic interventions. The review also briefly discusses the influence of glycosaminoglycans and non-inhibitory binding proteins on enzyme activities. Understanding their role may be a crucial factor in the development of therapeutic strategies. By elucidating the intricate web of regulatory mechanisms that control peptidase activity, this review deepens our understanding in this field and provides a roadmap for various strategies to influence and modulate peptidase activity.

Melanocyte-keratinocyte cross-talk in vitiligo

Vitiligo is a common acquired pigmentary disorder that presents as progressive loss of melanocytes from the skin. Epidermal melanocytes and keratinocytes are in close proximity to each other, forming a functional and structural unit where keratinocytes play a pivotal role in supporting melanocyte homeostasis and melanogenesis. This intimate relationship suggests that keratinocytes might contribute to ongoing melanocyte loss and subsequent depigmentation. In fact, keratinocyte dysfunction is a documented phenomenon in vitiligo. Keratinocyte apoptosis can deprive melanocytes from growth factors including stem cell factor (SCF) and other melanogenic stimulating factors which are essential for melanocyte function. Additionally, keratinocytes control the mobility/stability phases of melanocytes via matrix metalloproteinases and basement membrane remodeling. Hence keratinocyte dysfunction may be implicated in detachment of melanocytes from the basement membrane and subsequent loss from the epidermis, also potentially interfering with repigmentation in patients with stable disease. Furthermore, keratinocytes contribute to the autoimmune insult in vitiligo. Keratinocytes express MHC II in perilesional skin and may present melanosomal antigens in the context of MHC class II after the pigmented organelles have been transferred from melanocytes. Moreover, keratinocytes secrete cytokines and chemokines including CXCL-9, CXCL-10, and IL-15 that amplify the inflammatory circuit within vitiligo skin and recruit melanocyte-specific, skin-resident memory T cells. In summary, keratinocytes can influence vitiligo development by a combination of failing to produce survival factors, limiting melanocyte adhesion in lesional skin, presenting melanocyte antigens and enhancing the recruitment of pathogenic T cells.

Profiling of idiopathic macular hole vitreous proteome identifies the role of extracellular matrix remodelling, epithelial-mesenchymal transformation and unfolded protein-response pathways

Purpose

To analyze and describe the proteome of the vitreous humour in eyes with idiopathic macular holes.

Methods

We performed mass spectrometry (MS)-based label-free quantitative analysis of the vitreous proteome of idiopathic macular hole (IMH) and control donor vitreous. Comparative quantification was performed using SCAFFOLD software which calculated fold changes of differential expression. Bioinformatics analysis was performed using DAVID and STRING software.

Results

A total of 448 proteins were identified by LC-MS/MS in IMH and cadaveric eye vitreous samples, of which 199 proteins were common. IMH samples had 189 proteins that were unique and 60 proteins were present only in the control cadaveric vitreous. We found upregulation of several extracellular matrix (ECM) and cytoskeletal proteins, namely collagen alpha-1 (XVIII) chain, N-cadherin, EFEMP1/fibulin-3, basement membrane-specific heparan sulfate proteoglycan core protein, and target of Nesh-3. Several cytoskeleton proteins, namely tubulin, actin, and fibronectin levels, were significantly lower in IMH vitreous, probably reflecting increased ECM degradation. IMH vitreous also had a downregulation of unfolded protein response-mediated-mediated apoptosis proteins, possibly related to a state of increased cell survival and proliferation, along with a remodelling and aberrant production of ECM contents.

Conclusion

The pathogenesis of macular holes may involve ECM remodelling, epithelial-mesenchymal transformation, downregulation of apoptosis, protein folding defects, and complement pathway. The vitreo-retinal milieu in macular holes contain molecules related to both ECM degradation and inhibition of the same, thereby maintaining a homeostasis.

CAMSAP3 negatively regulates lung cancer cell invasion and angiogenesis through nucleolin/HIF-1α mRNA complex stabilization

AIMS

Cancer metastasis is a major cause of lung cancer-related mortality, so identification of related molecular mechanisms is of interest. Calmodulin-regulated spectrin-associated protein 3 (CAMSAP3) has been implicated in lung cancer malignancies; however, its role in metastatic processes, including invasion and angiogenesis, is largely unknown.

MAIN METHOD

The clinical relevance of CAMSAP3 expression in lung cancer was evaluated. The relevance of CAMSAP3 expression to in vitro cell invasion and angiogenesis was assessed in human lung cancer cells and endothelial cells, respectively. The molecular mechanism was identified by qRT-PCR, immunoprecipitation, mass spectrometry, and RNA immunoprecipitation. The in vivo metastatic and angiogenic activities of lung cancer cells were assessed.

KEY FINDINGS

Low CAMSAP3 expression was found in malignant lung tissues and strongly correlated with a poor prognosis in lung adenocarcinoma (LUAD). CAMSAP3-knockout NSCLC exhibited high invasive ability, and CAMSAP3 knockout induced HUVEC proliferation and tube formation; these effects were significantly attenuated by reintroduction of exogenous wild-type CAMSAP3. Mechanistically, in the absence of CAMSAP3, the expression of hypoxia-inducible factor-1α (HIF-1α) was upregulated, which increased the levels of downstream HIF-1α targets such as vascular endothelial growth factor A (VEGFA) and matrix metalloproteinases (MMPs) 2 and 9. Proteomic analysis revealed that nucleolin (NCL) bound to CAMSAP3 to regulate HIF-1α mRNA stabilization. In addition, CAMSAP3-knockout lung cancer cells displayed highly aggressive behavior in metastasis and angiogenesis in vivo.

SIGNIFICANCE

This study reveals that CAMSAP3 plays a negative regulatory role in lung cancer cell metastatic behavior both in vitro and in vivo through NCL/HIF-1α mRNA complex stabilization.

The Role of MMPs in the Era of CFTR Modulators: An Additional Target for Cystic Fibrosis Patients?

Cystic fibrosis (CF) is a high-prevalence disease characterized by significant lung remodeling, responsible for high morbidity and mortality worldwide. The lung structural changes are partly due to proteolytic activity associated with inflammatory cells such as neutrophils and macrophages. Matrix metalloproteases (MMPs) are the major proteases involved in CF, and recent literature data focused on their potential role in the pathogenesis of the disease. In fact, an imbalance of proteases and antiproteases was observed in CF patients, resulting in dysfunction of protease activity and loss of lung homeostasis. Currently, many steps forward have been moved in the field of pharmacological treatment with the recent introduction of triple-combination therapy targeting the CFTR channel. Despite CFTR modulator therapy potentially being effective in up to 90% of patients with CF, there are still patients who are not eligible for the available therapies. Here, we introduce experimental drugs to provide updates on therapy evolution regarding a proportion of CF non-responder patients to current treatment, and we summarize the role of MMPs in pathogenesis and as future therapeutic targets of CF.

ADAM9: A regulator between HCMV infection and function of smooth muscle cells

Lots of epidemiological and clinical studies have shown that human cytomegalovirus (HCMV) is related to the pathogenesis of atherosclerosis. Released by inflammatory cells and vascular smooth muscle cell (VSMCs), metalloproteinases are observed in many pathological vessel conditions, including atherosclerosis and restenosis. This study was designed to investigate the effect of HCMV infection on the expression of metalloproteinases and their involvements in the HCMV-induced functional changes of VSMCs. Differential metalloproteinase after HCMV infection was assayed using reverse transcription-polymerase chain reaction (RT-PCR) microarray. The most significant increased a disintegrin and metalloprotease 9 (ADAM9) was chosen to investigate the mechanism of its specific increase after infection using the treatment of UV-irradiated replication-deficient HCMV, HCMV-infected cell lysate filters or Foscarnet. The function of proliferation, migration, production of inflammatoty factors and phenotypic transformation were determined by using cell counting kit-8, transwell, Enzyme-linked immunosorbent assay, RT-quantitative PCR (qPCR) and Western blot, respectively. Moreover, the effect of ADAM9 deficiency on HCMV replication was also determined using RT-qPCR and immunofluorescence. The expression levels of 6 genes were upregulated and 14 genes were downregulated at different time points after HCMV infection. Among these, the expression level of ADAM9 increased most significantly at each time point and the abnormal expression of ADAM9 might be induced by the early gene products of HCMV. Further studies found that ADAM9 promoted the proliferation, the migration, the production of inflammatory factors and the transit from the contractile phenotype (decreased ACTA2 expression) to the synthetic phenotype (increased osteopontin [OPN] expression). Knockdown theADAM9 expression could rescue the decreased ACTA2 expression, but has no effect on OPN expression. ADAM-9 deficiency didn't affect the replication of HCMV. The findings of our study suggest that HCMV infection changed VSMC function through ADAM9 expression, which may contribute to the understanding of the underlying pathological mechanisms of HCMV-induced atherosclerosis.

Immunomodulatory role of metalloproteases in cancers: Current progress and future trends

Metalloproteinases (MPs) is a large family of proteinases with metal ions in their active centers. According to the different domains metalloproteinases can be divided into a variety of subtypes mainly including Matrix Metalloproteinases (MMPs), A Disintegrin and Metalloproteases (ADAMs) and ADAMs with Thrombospondin Motifs (ADAMTS). They have various functions such as protein hydrolysis, cell adhesion and remodeling of extracellular matrix. Metalloproteinases expressed in multiple types of cancers and participate in many pathological processes involving tumor genesis and development, invasion and metastasis by regulating signal transduction and tumor microenvironment. In this review, based on the current research progress, we summarized the structure of MPs, their expression and especially immunomodulatory role and mechanisms in cancers. Additionally, a relevant and timely update of recent advances and future directions were provided for the diagnosis and immunotherapy targeting MPs in cancers.

The Monocyte, a Maestro in the Tumor Microenvironment (TME) of Breast Cancer

Breast cancer (BC) is well-known for being a leading cause of death worldwide. It is classified molecularly into luminal A, luminal B HER2-, luminal B HER2+, HER2+, and triple-negative breast cancer (TNBC). These subtypes differ in their prognosis; thus, understanding the tumor microenvironment (TME) makes new treatment strategies possible. The TME contains populations that exhibit anti-tumorigenic actions such as tumor-associated eosinophils. Moreover, it contains pro-tumorigenic populations such as tumor-associated neutrophils (TANs), or monocyte-derived populations. The monocyte-derived populations are tumor-associated macrophages (TAMs) and MDSCs. Thus, a monocyte can be considered a maestro within the TME. Moreover, the expansion of monocytes in the TME depends on many factors such as the BC stage, the presence of macrophage colony-stimulating factor (M-CSF), and the presence of some chemoattractants. After expansion, monocytes can differentiate into pro-inflammatory populations such as M1 macrophages or anti-inflammatory populations such as M2 macrophages according to the nature of cytokines present in the TME. Differentiation to TAMs depends on various factors such as the BC subtype, the presence of anti-inflammatory cytokines, and epigenetic factors. Furthermore, TAMs and MDSCs not only have a role in tumor progression but also are key players in metastasis. Thus, understanding the monocytes further can introduce new target therapies.

Structure of the proteolytic enzyme PAPP-A with the endogenous inhibitor stanniocalcin-2 reveals its inhibitory mechanism

The metzincin metalloproteinase PAPP-A plays a key role in the regulation of insulin-like growth factor (IGF) signaling by specific cleavage of inhibitory IGF binding proteins (IGFBPs). Using single-particle cryo-electron microscopy (cryo-EM), we here report the structure of PAPP-A in complex with its endogenous inhibitor, stanniocalcin-2 (STC2), neither of which have been reported before. The highest resolution (3.1 Å) was obtained for the STC2 subunit and the N-terminal approximately 1000 residues of the PAPP-A subunit. The 500 kDa 2:2 PAPP-A·STC2 complex is a flexible multidomain ensemble with numerous interdomain contacts. In particular, a specific disulfide bond between the subunits of STC2 and PAPP-A prevents dissociation, and interactions between STC2 and a module located in the very C-terminal end of the PAPP-A subunit prevent binding of its main substrate, IGFBP-4. While devoid of activity towards IGFBP-4, the active site cleft of the catalytic domain is accessible in the inhibited PAPP-A·STC2 complex, as shown by its ability to hydrolyze a synthetic peptide derived from IGFBP-4. Relevant to multiple human pathologies, this unusual mechanism of proteolytic inhibition may support the development of specific pharmaceutical agents, by which IGF signaling can be indirectly modulated.

A top-down approach to uncover the hidden ligandome of low-density lipoprotein receptor-related protein 1 in cartilage

The low-density lipoprotein receptor-related protein 1 (LRP1) is a cell-surface receptor ubiquitously expressed in various tissues. It plays tissue-specific roles by mediating endocytosis of a diverse range of extracellular molecules. Dysregulation of LRP1 is involved in multiple conditions including osteoarthritis (OA) but little information is available about the specific profile of direct binding partners of LRP1 (ligandome) for each tissue, which would lead to a better understanding of its role in disease states. Here, we investigated adult articular cartilage where impaired LRP1-mediated endocytosis leads to tissue destruction. We used a top-down approach involving proteomic analysis of the LRP1 interactome in human chondrocytes, direct binding assays using purified LRP1 and ligand candidates, and validation in LRP1-deficient fibroblasts and human chondrocytes, as well as a novel Lrp1 conditional knockout (KO) mouse model. We found that inhibition of LRP1 and ligand interaction results in cell death, alteration of the entire secretome and transcriptional modulations in human chondrocytes. We identified a chondrocyte-specific LRP1 ligandome consisting of more than 50 novel ligand candidates. Surprisingly, 23 previously reported LRP1 ligands were not regulated by LRP1-mediated endocytosis in human chondrocytes. We confirmed direct LRP1 binding of HGFAC, HMGB1, HMGB2, CEMIP, SLIT2, ADAMTS1, TSG6, IGFBP7, SPARC and LIF, correlation between their affinity for LRP1 and the rate of endocytosis, and some of their intracellular localization. Moreover, a conditional LRP1 KO mouse model demonstrated a critical role of LRP1 in regulating the high-affinity ligands in cartilage in vivo. This systematic approach revealed the specificity and the extent of the chondrocyte LRP1 ligandome and identified potential novel therapeutic targets for OA.

Altered gene expression of selected matrix metalloproteinase system proteins in the broiler chicken gastrointestinal tract during post-hatch development and coccidia infection*

Matrix metalloproteinases (MMPs) are a family of proteases, that can process extracellular matrix (ECM) components and non-ECM molecules. MMPs can also function intracellularly in proteolytic and nonproteolytic functions. The participation of MMPs in the remodeling of the chicken gastrointestinal tract is largely unknown. The aim of the present study was to examine 1) the early neonatal developmental changes and effect of delayed access to feed immediately post-hatch (PH) and 2) the effect of Eimeria infection on mRNA expression of selected MMPs, their tissue inhibitors (TIMPs), and a disintegrin and metalloproteinase (ADAM) metallopeptidase with thrombospondin type 1 motif 8 (ADAMTS8) in the gastrointestinal tract of chicken. Protein localization of MMPs and TIMPs was also carried out in the normal ileal wall at −48, 24, and 336 h relative to hatch using immunofluorescence. In experiment 1, newly hatched Ross 708 chicks received feed and water immediately PH or were subjected to 48 h delayed access to feed. Chickens were sampled at −48, 0, 4, 24, 48, 72, 96, 144, 192, 240, 288, and 336 h PH. Ileum was collected for investigation of gene expression or fixed in paraformaldehyde for immunofluorescence. In experiments 2 and 3, Ross 708 male broilers were infected, at 21 d of age with Eimeria maxima or E. acervulina or sham-infected with water. Intestinal tissues were collected at 7 and 10 d postinfection for gene expression analysis. In general, mRNA expression patterns of all examined genes showed downregulation during the first 2 wk PH and were not affected by delay in feed access. These development-dependent changes in expression and tissue-dependent localization in the ileum of selected MMPs and TIMPs indicate that these molecules participate in the remodeling of chicken intestinal tissues during PH development. Increased expression of MMP-7 and MMP-9 transcripts in the intestine of Eimeria infected birds suggests an important role for these enzymes in the process of tissue remodeling and destruction in pathological conditions. The findings of this study are important for understanding the relationship between the expression of the MMP system and intestinal development, as well its role in gastrointestinal infection and subsequent recovery.

Discoidin Domain Receptor 1, a Potential Biomarker and Therapeutic Target in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is still one of the most lethal human cancers in the world due to its high degree of malignancy, easy invasion and metastasis, poor therapeutic effect and poor prognosis. Nowadays, there is no very effective diagnosis and treatment method. It is crucial to elucidate the underlying pathogenesis and mechanisms of HCC for developing new and effective diagnostic/prognostic biomarkers and therapies. Discoidin domain receptors (DDRs) belong to the family of transmembrane receptor tyrosine kinases (RTKs) and are recognized as playing central regulatory roles in a variety of high incidence human diseases, including tumors. DDRs have two members, DDR1 and DDR2. The role of DDR1 in several tumors has been extensively studied, and many researchers have identified it as a powerful candidate target for the development of functional and effective tumor treatment inhibitors. However, its role and mechanism in HCC are ill defined. In this article, we review the advanced insights into the progression of DDR1 in HCC, particularly the ligands and mechanisms in invasion and metastasis, which may open new avenues for the therapeutic utility of HCC.

The essential anti-angiogenic strategies in cartilage engineering and osteoarthritic cartilage repair

In the cartilage matrix, complex interactions occur between angiogenic and anti-angiogenic components, growth factors, and environmental stressors to maintain a proper cartilage phenotype that allows for effective load bearing and force distribution. However, as seen in both degenerative disease and tissue engineering, cartilage can lose its vascular resistance. This vascularization then leads to matrix breakdown, chondrocyte apoptosis, and ossification. Research has shown that articular cartilage inflammation leads to compromised joint function and decreased clinical potential for regeneration. Unfortunately, few articles comprehensively summarize what we have learned from previous investigations. In this review, we summarize our current understanding of the factors that stabilize chondrocytes to prevent terminal differentiation and applications of these factors to rescue the cartilage phenotype during cartilage engineering and osteoarthritis treatment. Inhibiting vascularization will allow for enhanced phenotypic stability so that we are able to develop more stable implants for cartilage repair and regeneration.

Evaluation of matrix metalloproteinases and tissue inhibitors of metalloproteinases in aqueous humor of dogs with versus without naturally occurring primary angle-closure glaucoma

OBJECTIVE

To compare concentrations of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in aqueous humor from ophthalmologically normal dogs and dogs with naturally occurring primary angle-closure glaucoma (cPACG).

SAMPLE

Aqueous humor samples from 12 eyes with cPACG and 18 ophthalmologically normal eyes of dogs.

PROCEDURES

A multiplex fluorescence-based ELISA was used to measure concentrations of MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, MMP-10, MMP-13, TIMP-1, TIMP-2, and TIMP-4. Results for eyes with versus without cPACG were compared.

RESULTS

Significantly higher mean concentrations of MMP-1 (45% higher), MMP-2 (55% higher), MMP-3 (39% higher), MMP-8 (79% higher), MMP-9 (29% higher), MMP-10 (60% higher), TIMP-1 (63% higher), and TIMP-2 (136% higher) were detected in aqueous humor from eyes with cPACG, compared with ophthalmologically normal eyes.

CLINICAL RELEVANCE

MMPs and TIMPs have pivotal roles in extracellular matrix turnover and homeostasis in the outflow pathways of the eye. Results of the present study documented higher concentrations of MMPs and TIMPs in aqueous humor samples from dog eyes with late-stage cPACG. Although, to our knowledge, TIMPs have not previously been evaluated in the context of cPACG, the markedly higher concentration of TIMPs in eyes with cPACG suggested that inhibition of proteolysis and extracellular matrix turnover might be a factor in the development of glaucoma in susceptible individuals. However, because the present study used samples from dogs with late-stage cPACG, further work is required to characterize the temporal relationship between MMP and TIMP concentration changes and onset or progression of disease.

A guide to the composition and functions of the extracellular matrix

Extracellular matrix (ECM) is a dynamic 3-dimensional network of macromolecules that provides structural support for the cells and tissues. Accumulated knowledge clearly demonstrated over the last decade that ECM plays key regulatory roles since it orchestrates cell signaling, functions, properties and morphology. Extracellularly secreted as well as cell-bound factors are among the major members of the ECM family. Proteins/glycoproteins, such as collagens, elastin, laminins and tenascins, proteoglycans and glycosaminoglycans, hyaluronan, and their cell receptors such as CD44 and integrins, responsible for cell adhesion, comprise a well-organized functional network with significant roles in health and disease. On the other hand, enzymes such as matrix metalloproteinases and specific glycosidases including heparanase and hyaluronidases contribute to matrix remodeling and affect human health. Several cell processes and functions, among them cell proliferation and survival, migration, differentiation, autophagy, angiogenesis, and immunity regulation are affected by certain matrix components. Structural alterations have been also well associated with disease progression. This guide on the composition and functions of the ECM gives a broad overview of the matrisome, the major ECM macromolecules, and their interaction networks within the ECM and with the cell surface, summarizes their main structural features and their roles in tissue organization and cell functions, and emphasizes the importance of specific ECM constituents in disease development and progression as well as the advances in molecular targeting of ECM to design new therapeutic strategies.

Post-translational regulation and proteolytic activity of the metalloproteinase ADAMTS8

A disintegrin-like and metalloprotease domain with thrombospondin type 1 motifs (ADAMTS)8 is a secreted protease, which was recently implicated in pathogenesis of pulmonary arterial hypertension (PAH). However, the substrate repertoire of ADAMTS8 and regulation of its activity are incompletely understood. Although considered a proteoglycanase because of high sequence similarity and close phylogenetic relationship to the proteoglycan-degrading proteases ADAMTS1, 4, 5, and 15, as well as tight genetic linkage with ADAMTS15 on human chromosome 11, its aggrecanase activity was reportedly weak. Several post-translational factors are known to regulate ADAMTS proteases such as autolysis, inhibition by endogenous inhibitors, and receptor-mediated endocytosis, but their impacts on ADAMTS8 are unknown. Here, we show that ADAMTS8 undergoes autolysis at six different sites within its spacer domain. We also found that in contrast to ADAMTS4 and 5, ADAMTS8 levels were not regulated through low-density lipoprotein receptor-related protein 1 (LRP1)-mediated endocytosis. Additionally, ADAMTS8 lacked significant activity against the proteoglycans aggrecan, versican, and biglycan. Instead, we found that ADAMTS8 cleaved osteopontin, a phosphoprotein whose expression is upregulated in PAH. Multiple ADAMTS8 cleavage sites were identified using liquid chromatography–tandem mass spectrometry. Osteopontin cleavage by ADAMTS8 was efficiently inhibited by TIMP-3, an endogenous inhibitor of ADAMTS1, 4, and 5, as well as by TIMP-2, which has no previously reported inhibitory activity against other ADAMTS proteases. These differences in post-translational regulation and substrate repertoire differentiate ADAMTS8 from other family members and may help to elucidate its role in PAH.

Mapping the Secretome of Dental Pulp Stem Cells Under Variable Microenvironmental Conditions

There is substantial evidence supporting the anti-inflammatory and regenerative potential of dental pulp stem cells (DPSCs) through direct cell transplantation or paracrine action. However, DPSC secretome profile remains inadequately studied. This study provides proteomic profiling of the human DPSC secretome by comparatively analysising cell lysates and respective culture supernatants (i.e. conditioned media-CM) under variable oxygen tension conditions (normoxia-20% O₂/CM_Norm vs. hypoxia 2% O₂/CM_Hyp) and/or stimulation with Tumor Necrosis Factor alpha (TNF-α). DPSC-CM samples and respective crude lysates (DPSC-CL) were collected and subjected to SDS-PAGE, followed by LC-MS/MS analysis. The identified proteins were analyzed by Gene Ontology, Reactome, and String databases. The anti-inflammatory properties of DPSC-CMs were validated via an in vitro RAW_246.7 murine macrophages model through evaluation of the expression of pro-and anti-inflammatory markers by real-time PCR. Results showed a total of 2413 proteins identified in CM_Norm, 2479 in CM_Norm+TNF-α, 1642 in CM_Hyp, and 2002 in CM_Hyp + TNF-α samples. CM_Norm contained 122 proteins statistically significantly upregulated compared to the CM_Hyp and involved in pathways related to "ECM organization", "cellular response to hypoxia", and "IL signaling". Functional network analysis showed that TGFβ1, TIMP1 and TIMP2 were key nodes among proteins significantly upregulated in the CM_Norm compared to the CM_Hyp, interacting with more than 10 proteins, each. DPSC-CM application in the in vitro RAW_246.7 model decreased the expression of pro-inflammatory markers (MMP-3, MMP-9, MMP-13, MCP-1), while increasing anti-inflammatory markers (IL-10). Overall, DPSC-CM collected under normoxic conditions is enriched with anti-inflammatory, tissue repair and regenerative factors, which prompts further investigation on its therapeutic applications.

Key miRNAs in Modulating Aging and Longevity: A Focus on Signaling Pathways and Cellular Targets

Aging is a multifactorial procedure accompanied by gradual deterioration of most biological procedures of cells. MicroRNAs (miRNAs) are a class of short non-coding RNAs that post-transcriptionally regulate the expression of mRNAs through sequence-specific binding, and contributing to many crucial aspects of cell biology. Several miRNAs are expressed differently in various organisms through aging. The function of miRNAs in modulating aging procedures has been disclosed recently with the detection of miRNAs that modulate longevity in the invertebrate model organisms, through the IIS pathway. In these model organisms, several miRNAs have been detected to both negatively and positively regulate lifespan via commonly aging pathways. miRNAs modulate age-related procedures and disorders in different mammalian tissues by measuring their tissue-specific expression in older and younger counterparts, including heart, skin, bone, brain, and muscle tissues. Moreover, several miRNAs have been contributed to modulating senescence in different human cells, and the roles of these miRNAs in modulating cellular senescence have allowed illustrating some mechanisms of aging. The review discusses the available data on miRNAs through the aging process and we highlight the roles of miRNAs as aging biomarkers and regulators of longevity in cellular senescence, tissue aging, and organism lifespan.

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.

Matrix Metalloproteinases (MMPs) and Inhibitors of MMPs in the Avian Reproductive System: An Overview

Many matrix metalloproteinases (MMPs) are produced in the mammalian reproductive system and participate in the regulation of its functions. In birds, the limited information available thus far indicates that MMPs are significant regulators of avian ovarian and oviductal functions, too. Some MMPs and inhibitors of MMPs are present in the hen reproductive tissues and their abundances and/or activities change according to the physiological state. The intraovarian role of MMPs likely includes the remodeling of the extracellular matrix (ECM) during folliculogenesis, follicle atresia, and postovulatory regression. In the oviduct, MMPs are also involved in ECM turnover during oviduct development and regression. This study provides a review of the current knowledge on the presence, activity, and regulation of MMPs in the female reproductive system of birds.

Combined Radiochemotherapy: Metalloproteinases Revisited

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

Response of the matrix metalloproteinase system of the chicken ovary to prolactin treatment

The expression and activity of several matrix metalloproteinases (MMPs) has been demonstrated in the chicken ovary during various physiological states; these data indicate that MMPs are involved in the remodeling of the extracellular matrix (ECM) during follicle development, ovulation, atresia, and regression. The regulation of MMPs in the avian ovary, however, remains largely unknown. The present study aimed to examine the effect of recombinant chicken prolactin (chPRL) treatment on the expression of selected MMPs and their tissue inhibitors (TIMPs), as well as MMP-2 and MMP-9 activity in the hen ovary. Real-time polymerase chain reaction revealed changes in the mRNA expression of MMP-2, MMP-7, MMP-9, MMP-10, MMP-13, TIMP-2, and TIMP-3 in the following ovarian follicles: white, yellowish, small yellow, and the largest yellow preovulatory (F3-F1). Western blot analysis showed alterations in the abundance of latent and active forms of the MMP-2 protein, as well as the abundance of the MMP-9 protein. Moreover, minor changes in MMP-2 and MMP-9 total activities were found in ovarian follicles of chPRL-treated hens. The response to chPRL treatment depended upon the stage of follicle development, the layer of follicular wall, and the type of MMPs or TIMPs studied. In general, the results indicate that chPRL, is a positive regulator of MMP expression in the yellow preovulatory follicles. Our findings suggest that PRL participates in the mechanisms orchestrating ECM turnover during ovarian follicular development in the hen ovary via regulating the transcription, translation, and/or activity of some constituents of the MMP system.

Key Matrix Remodeling Enzymes: Functions and Targeting in Cancer

Tissue functionality and integrity demand continuous changes in distribution of major components in the extracellular matrices (ECMs) under normal conditions aiming tissue homeostasis. Major matrix degrading proteolytic enzymes are matrix metalloproteinases (MMPs), plasminogen activators, atypical proteases such as intracellular cathepsins and glycolytic enzymes including heparanase and hyaluronidases. Matrix proteases evoke epithelial-to-mesenchymal transition (EMT) and regulate ECM turnover under normal procedures as well as cancer cell phenotype, motility, invasion, autophagy, angiogenesis and exosome formation through vital signaling cascades. ECM remodeling is also achieved by glycolytic enzymes that are essential for cancer cell survival, proliferation and tumor progression. In this article, the types of major matrix remodeling enzymes, their effects in cancer initiation, propagation and progression as well as their pharmacological targeting and ongoing clinical trials are presented and critically discussed.

Progress in the use of mesenchymal stromal cells for osteoarthritis treatment

LITERATURE REVIEW OF MSCS IN THE TREATMENT OF OSTEOARTHRITIS IN THE PAST FIVE YEARS: Osteoarthritis (OA) is one of the most common chronic joint diseases, with prominent symptoms caused by many factors. However, current medical interventions for OA have resulted in poor clinical outcomes, demonstrating that there are huge unmet medical needs in this area. Cell therapy has opened new avenues of OA treatment. Different sources of mesenchymal stromal cells (MSCs) may have different phenotypes and cellular functions. Pre-clinical and clinical studies have demonstrated the feasibility, safety and efficacy of MSC therapy. Mitogen-activated protein kinase, Wnt and Notch signaling pathways are involved in the chondrogenesis of MSC-mediated treatments. MSCs may also exert effective immunoregulatory and paracrine effects to stimulate tissue repair. Therapy with extracellular vesicles containing cytokines, which are secreted by MSCs, might be a potential treatment for OA.

Alterations of Extracellular Matrix Components in the Course of Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is the most common group of chronic connective tissue diseases in children that is accompanied by joint structure and function disorders. Inflammation underlying the pathogenic changes in JIA, caused by hypersecretion of proinflammatory cytokines, leads to the destruction of articular cartilage. The degradation which progresses with the duration of JIA is not compensated by the extent of repair processes. These disorders are attributed in particular to changes in homeostasis of extracellular matrix (ECM) components, including proteoglycans, that forms articular cartilage. Changes in metabolism of matrix components, associated with the disturbance of their degradation and biosynthesis processes, are the basis of the progressive wear of joint structures observed in the course of JIA. Clinical evaluation and radiographic imaging are current methods to identify the destruction. The aim of this paper is to review enzymatic and non-enzymatic factors involved in catabolism of matrix components and molecules stimulating their biosynthesis. Therefore, we discuss the changes in these factors in body fluids of children with JIA and their potential diagnostic use in the assessment of disease activity. Understanding the changes in ECM components in the course of the child-hood arthritis may provide the introduction of both new diagnostic tools and new therapeutic strategies in children with JIA.

ADAMTS proteases in cardiovascular physiology and disease

The a disintegrin-like and metalloproteinase with thrombospondin motif (ADAMTS) family comprises 19 proteases that regulate the structure and function of extracellular proteins in the extracellular matrix and blood. The best characterized cardiovascular role is that of ADAMTS-13 in blood. Moderately low ADAMTS-13 levels increase the risk of ischeamic stroke and very low levels (less than 10%) can cause thrombotic thrombocytopenic purpura (TTP). Recombinant ADAMTS-13 is currently in clinical trials for treatment of TTP. Recently, new cardiovascular roles for ADAMTS proteases have been discovered. Several ADAMTS family members are important in the development of blood vessels and the heart, especially the valves. A number of studies have also investigated the potential role of ADAMTS-1, -4 and -5 in cardiovascular disease. They cleave proteoglycans such as versican, which represent major structural components of the arteries. ADAMTS-7 and -8 are attracting considerable interest owing to their implication in atherosclerosis and pulmonary arterial hypertension, respectively. Mutations in the ADAMTS19 gene cause progressive heart valve disease and missense variants in ADAMTS6 are associated with cardiac conduction. In this review, we discuss in detail the evidence for these and other cardiovascular roles of ADAMTS family members, their proteolytic substrates and the potential molecular mechanisms involved.

Alternations in the expression of selected matrix metalloproteinases (MMP-2, -9, -10, and -13) and their tissue inhibitors (TIMP-2 and -3) and MMP-2 and -9 activity in the chicken ovary during pause in laying induced by fasting

Matrix metalloproteinases (MMPs) are a large group of proteolytic enzymes involved in extracellular matrix turnover in the ovary. Under physiological conditions, the activity of MMPs is controlled by specific tissue inhibitors of MMPs (TIMPs). Information concerning the role and regulation of MMPs in the chicken ovary is scarce. This study was undertaken to examine the expression of selected MMPs and their TIMPs in the chicken ovary during a pause in egg laying induced by feed deprivation. The activities of MMP-2 and MMP-9 were investigated as well. Real-time polymerase chain reaction and Western blot analyses showed changes in the expression of gelatinases (MMP-2, MMP-9), stromelysin (MMP-10), collagenase (MMP-13), TIMP-2, and TIMP-3 on mRNA and/or protein levels in the prehierarchical white (WFs) and yellowish (YFs) follicles, as well as in the largest yellow preovulatory (F3-F1) follicles. In feed-deprived hens, the occurrence of ovarian regression was accompanied by (1) a pronounced decrease in mRNA expression of the examined MMPs and TIMP-3 in all tissues except the YFs where the expression of MMP-13 was higher than in the control hen ovary; (2) an increase in the transcript abundance of TIMP-2 in the yellow atretic follicles; (3) a decrease or no changes in MMP-2 and MMP-9 protein expression in all tissues; (4) an increase in the total activity of gelatinases in the YFs and theca layer of F3; and (5) a decrease in the activity of MMP-2 in F3-F1 follicles and MMP-9 in the theca of F3. In summary, the results of the current study suggest that the selected MMPs and TIMPs may not be involved in the regulation of the advanced stages of atresia of the largest yellow preovulatory follicles in the chicken ovary. This event may require different cell signaling pathways.

Effect of eCG treatment on gene expression of selected matrix metalloproteinases (MMP-2, MMP-7, MMP-9, MMP-10, and MMP-13) and the tissue inhibitors of metalloproteinases (TIMP-2 and TIMP-3) in the chicken ovary

Several metalloproteinases (MMPs) are present and functional in the chicken ovary and regulate the extracellular matrix (ECM) during follicle development, ovulation, atresia, and regression. The regulation of the abundance of MMPs in avian ovarian follicles, however, is largely unknown. The aim of the present study was to examine effects of equine chorionic gonadotropin (eCG) on abundance of selected MMPs and relevant tissue inhibitors of MMPs (TIMPs) in the hen ovary. The MMP-2 and MMP-9 activity was also determined. Results indicated there were effects of eCG on abundances of MMP-2, MMP-7, MMP-9, MMP-10, MMP-13, TIMP-2, and TIMP-3 mRNA transcript and/or protein relative abundances in white, yellowish, small yellow, and the largest yellow preovulatory (F3-F1) ovarian follicles. The response to eCG depended on the stage of follicle development, layer of follicular wall, and the type of MMPs or TIMPs affected by eCG. Furthermore, there was a pause in egg laying when eCG was administered and there were morphological changes in the ovary following eCG treatment that were associated with alterations in MMP-2 and MMP-9 activity. In general, the results indicate that eCG, which has primarily follicle stimulating hormone (FSH)-like bioactivities, is a negative regulator of MMP abundance and activity in the largest yellow preovulatory follicles. Results from the present study indicate the gonadotropins, especially FSH, by the regulation of transcription, translation, and/or activity of proteins of the MMP system have effects on the mechanisms that underlie ECM remodeling and cell function throughout ovarian follicle development in the chicken ovary.

Enhanced transforming growth factor-beta signaling and fibrosis in the pectoralis major muscle of broiler chickens affected by wooden breast myopathy

Fibrosis has also been recorded as a prominent pathological feature within wooden breast (WB) myopathy of broiler chickens. This study was conducted to evaluate the accumulation of fibril collagen, deposition of the extracellular matrix (ECM) components, and the underlying mechanism mediating the pathogenic fibrotic process in the pectoralis major (PM) muscle of WB-affected birds. Broiler chickens were categorized into the control and WB groups based on the evaluation of myopathic lesions. Results indicated that the total content and area of collagen in cross-sections of the PM muscle, as well as the augmented expression of collagen-I and fibronectin in the ECM, were greatly increased in birds with WB. Wooden breast myopathy upregulated expressions of transforming growth factor-beta (TGF-β) and the phosphorylation of Smad 2 and 3, thereby activating TGF-β-mediated Smad signaling pathway, which further enhanced the transcription of profibrotic mediators. In addition, regulators involved in collagen biosynthesis and cross-linking including prolyl 4-hydroxylase, lysyl oxidase, lysyl hydroxylase, and decorin were increased in the WB muscle. Finally, the expressions of both matrix metalloproteinases (MMP) and tissue inhibitor of metalloproteinases (TIMP) were increased in the WB muscle, which might be related with reduced ECM remodeling. Overall, WB myopathy induces severe fibrosis by enhancing ECM deposition and collagen cross-linking in the PM muscle of broiler chickens, possibly via the activation of TGF-β signaling and the dysregulation of the MMP and TIMP system.

The regulation of trophoblast invasion and decidual reaction by matrix metalloproteinase-2, metalloproteinase-7, and metalloproteinase-9 expressions in the rat endometrium

PURPOSE

We aimed to evaluate how matrix metalloproteinases (MMPs) regulate the trophoblast invasion and placentation.

METHODS

Female rats were divided into the estrous cycle and early pregnancy day groups. Obtained uterine tissues and implantation sites were processed for immunofluorescence and real-time PCR examinations.

RESULTS

The mRNA expression of MMP-7 was higher than MMP-2 and MMP-9. Immunofluorescence findings confirmed that MMP-2, MMP-7, and MMP-9 were localized in the endometrial stroma, while MMP-7 was high in glandular and lining epithelial cells throughout the entire estrous cycle. However, their immunolocalizations and mRNA expressions were dramatically changed with the early pregnancy days. The MMP-7 reached very strong immunostaining in the giant trophoblast cells (GTCs), and the cytoplasm of mature and differentiating decidual cells, whereas MMP-2 and MMP-9 were mostly seen in the primary decidual zone (PDZ), GTCs, and the endothelium of blood vessels.

CONCLUSIONS

All three MMPs seemed likely to be a key mediator of trophoblast invasion into the decidual region as well as angiogenesis during the placentation process. Due to the strong and wide expression of MMP-7 in the mature decidua, it could be suggested that MMP-7 is important for decidual ECM remodeling and it might be used as a new marker of decidual reaction.

Transcriptome analysis of the epididymis from Plag1 deficient mice suggests dysregulation of sperm maturation and extracellular matrix genes

BACKGROUND

The transcription factor pleomorphic adenoma gene 1 (PLAG1) is required for male fertility. Mice deficient in PLAG1 exhibit decreased sperm motility and abnormal epididymal tubule elongation and coiling, indicating impaired sperm maturation during epididymal transit. However, the downstream transcriptomic profile of the Plag1 knockout (KO; Plag1^-/- ) murine epididymis is currently unknown.

RESULTS

In this study, the PLAG1-dependent epididymal transcriptome was characterised using RNA sequencing. Several genes important for the control of sperm maturation, motility, capacitation and the acrosome reaction were dysregulated in Plag1^-/- mice. Surprisingly, several cell proliferation genes were upregulated, and Ki67 analysis indicated that cell proliferation is aberrantly upregulated in the cauda epididymis stroma of Plag1^-/- mice. Gene ontology analysis showed an overall upregulation of genes encoding extracellular matrix components, and an overall downregulation of genes encoding metalloendopeptidases in the epididymides from Plag1^-/- mice.

CONCLUSION

Together, these results suggest a defect in the epididymal extracellular matrix in Plag1^-/- mice. These results imply that in addition to maintaining epididymal integrity directly, PLAG1 may also regulate several genes involved in the regulation of sperm maturation and capacitation. Moreover, PLAG1 may also be involved in regulating tissue homeostasis and ensuring proper structure and maintenance of the extracellular matrix in the epididymis.

An altered heparan sulfate structure in the articular cartilage protects against osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is a progressive degenerative disease of the articular cartilage caused by an unbalanced activity of proteases, cytokines and other secreted proteins. Since heparan sulfate (HS) determines the activity of many extracellular factors, we investigated its role in OA progression.

METHODS

To analyze the role of the HS level, OA was induced by anterior cruciate ligament transection (ACLT) in transgenic mice carrying a loss-of-function allele of Ext1 in clones of chondrocytes (Col2-rtTA-Cre;Ext1e2fl/e2fl). To study the impact of the HS sulfation pattern, OA was surgically induced in mice with a heterozygous (Ndst1+/-) or chondrocyte-specific (Col2-Cre;Ndst1fl/fl) loss-of-function allele of the sulfotransferase Ndst1. OA progression was evaluated using the OARSI scoring system. To investigate expression and activity of cartilage degrading proteases, femoral head explants of Ndst1+/- mutants were analyzed by qRT-PCR, Western Blot and gelatin zymography.

RESULTS

All investigated mouse strains showed reduced OA scores (Col2-rtTA-Cre;Ext1e2fl/e2fl: 0.83; 95% HDI 0.72-0.96; Ndst1+/-: 0.83, 95% HDI 0.74-0.9; Col2-Cre;Ndst1fl/fl: 0.87, 95% HDI 0.76-1). Using cartilage explant cultures of Ndst1 animals, we detected higher amounts of aggrecan degradation products in wildtype samples (NITEGE 4.24-fold, 95% HDI 1.05-18.55; VDIPEN 1.54-fold, 95% HDI 1.54-2.34). Accordingly, gelatin zymography revealed lower Mmp2 activity in mutant samples upon RA-treatment (0.77-fold, 95% HDI: 0.60-0.96). As expression of major proteases and their inhibitors was not altered, HS seems to regulate cartilage degeneration by affecting protease activity.

CONCLUSION

A decreased HS content or a reduced sulfation level protect against OA progression by regulating protease activity rather than expression.

Molecular Interactions Stabilizing the Promatrix Metalloprotease-9·Serglycin Heteromer

Previous studies have shown that THP-1 cells produced an SDS-stable and reduction-sensitive complex between proMMP-9 and a chondroitin sulfate proteoglycan (CSPG) core protein. The complex could be reconstituted in vitro using purified serglycin (SG) and proMMP-9 and contained no inter-disulfide bridges. It was suggested that the complex involved both the FnII module and HPX domain of proMMP-9. The aims of the present study were to resolve the interacting regions of the molecules that form the complex and the types of interactions involved. In order to study this, we expressed and purified full-length and deletion variants of proMMP-9, purified CSPG and SG, and performed in vitro reconstitution assays, peptide arrays, protein modelling, docking, and molecular dynamics (MD) simulations. ProMMP-9 variants lacking both the FnII module and the HPX domain did not form the proMMP-9∙CSPG/SG complex. Deletion variants containing at least the FnII module or the HPX domain formed the proMMP-9∙CSPG/SG complex, as did the SG core protein without CS chains. The interacting parts covered large surface areas of both molecules and implicated dynamic and complementary ionic, hydrophobic, and hydrogen bond interactions. Hence, no short single interacting linear motifs in the two macromolecules could explain the strong SDS-stable and reduction-sensitive binding.

A type IV collagenase inhibitor, N-hydroxy-3-phenyl-2-(4-phenylbenzenesulfonamido) propanamide (BiPS), suppresses skin injury induced by sulfur mustard

Sulfur mustard (SM) is a highly toxic blistering agent thought to mediate its action, in part, by activating matrix metalloproteinases (MMPs) in the skin and disrupting components of the basement membrane zone (BMZ). Type IV collagenases (MMP-9) degrade type IV collagen in the skin, a major component of the BMZ at the dermal-epidermal junction. In the present studies, a type IV collagenase inhibitor, N-hydroxy-3-phenyl-2-(4-phenylbenzenesulfonamido) propanamide (BiPS), was tested for its ability to protect the skin against injury induced by SM in the mouse ear vesicant model. SM induced inflammation, epidermal hyperplasia and microblistering at the dermal/epidermal junction of mouse ears 24-168 h post-exposure. This was associated with upregulation of MMP-9 mRNA and protein in the skin. Dual immunofluorescence labeling showed increases in MMP-9 in the epidermis and in the adjacent dermal matrix of the SM injured skin, as well as breakdown of type IV collagen in the basement membrane. Pretreatment of the skin with BiPS reduced signs of SM-induced cutaneous toxicity; expression of MMP-9 mRNA and protein was also downregulated in the skin by BiPS. Following BiPS pretreatment, type IV collagen appeared intact and was similar to control skin. These results demonstrate that inhibiting type IV collagenases in the skin improves basement membrane integrity after exposure to SM. BiPS may hold promise as a potential protective agent to mitigate SM induced skin injury.

Expression of Matrix Metalloproteinases and Their Inhibitors in Endometrium: High Levels in Endometriotic Lesions

Endometriosis is a condition defined as presence of endometrium outside of the uterine cavity. These endometrial cells are able to attach and invade the peritoneum or ovary, thus forming respectively the deep infiltrating endometriosis (DIE) and the ovarian endometrioma (OMA), the ectopic lesions feature of this pathology. Endometriotic cells display high invasiveness and share some features of malignancy with cancer cells. Indeed, the tissue remodeling underlining lesion formation is achieved by matrix metalloproteinases (MMPs) and their inhibitors. Therefore, these molecules are believed to play a key role in development and pathogenesis of endometriosis. This study investigated the molecular profile of metalloproteinases and their inhibitors in healthy (n = 15) and eutopic endometrium (n = 19) in OMA (n = 10) and DIE (n = 9); moreover, we firstly validated the most reliable housekeeping genes allowing accurate gene expression analysis in these tissues. Gene expression, Western blot, and immunofluorescence analysis of MMP2, MMP3, and MMP10 and their tissue inhibitors TIMP1 and TIMP2 demonstrated that these enzymes are finely tuned in these tissues. In OMA lesions, all the investigated MMPs and their inhibitors were significantly increased, while DIE expressed high levels of MMP3. Finally, in vitro TNFα treatment induced a significant upregulation of MMP3, MMP10, and TIMP2 in both healthy and eutopic endometrial stromal cells. This study, shedding light on MMP and TIMP expression in endometriosis, confirms that these molecules are altered both in eutopic endometrium and endometriotic lesions. Although further studies are needed, these data may help in understanding the molecular mechanisms involved in the extracellular matrix remodeling, a crucial process for the endometrial physiology.

High-Frequency Near-Infrared Diode Laser Irradiation Attenuates IL-1β-Induced Expression of Inflammatory Cytokines and Matrix Metalloproteinases in Human Primary Chondrocytes

High-frequency near-infrared diode laser provides a high-peak output, low-heat accumulation, and efficient biostimulation. Although these characteristics are considered suitable for osteoarthritis (OA) treatment, the effect of high-frequency near-infrared diode laser irradiation in in vitro or in vivo OA models has not yet been reported. Therefore, we aimed to assess the biological effects of high-frequency near-infrared diode laser irradiation on IL-1β-induced chondrocyte inflammation in an in vitro OA model. Normal Human Articular Chondrocyte-Knee (NHAC-Kn) cells were stimulated with human recombinant IL-1β and irradiated with a high-frequency near-infrared diode laser (910 nm, 4 or 8 J/cm²). The mRNA and protein expression of relevant inflammation- and cartilage destruction-related proteins was analyzed. Interleukin (IL) -1β treatment significantly increased the mRNA levels of IL-1β, IL-6, tumor necrosis factor (TNF) -α, matrix metalloproteinases (MMP) -1, MMP-3, and MMP-13. High-frequency near-infrared diode laser irradiation significantly reduced the IL-1β-induced expression of IL-1β, IL-6, TNF-α, MMP-1, and MMP-3. Similarly, high-frequency near-infrared diode laser irradiation decreased the IL-1β-induced increase in protein expression and secreted levels of MMP-1 and MMP-3. These results highlight the therapeutic potential of high-frequency near-infrared diode laser irradiation in OA.

Hypomethylation of DNA promoter upregulates ADAMTS7 and contributes to HTR-8/SVneo and JEG-3 cells abnormalities in pre-eclampsia

INTRODUCTION

Accumulating evidences have suggested a crucial role of epigenetics in the initiation and progression of pre-eclampsia (PE). Here, we studied the expression of the metalloproteinase ADAMTS7 and the methylation level of its promoter in PE placentas and investigated ADAMTS7 role in the pathogenesis of PE.

METHODS

We first explored ADAMTS7 expression in PE and normal placentas by reverse transcription quantitative PCR (RT-qPCR), western blot, and immunohistochemistry. Methylation specific PCR (MSP) and bisulfite sequencing PCR (BSP) were performed to evaluate the methylation status of ADAMTS7 promoter. Treatment with 5'-Aza was used to induce demethylation and thereby to explore the direct relationship between promoter methylation and ADAMTS7 expression. CCK8 assay, colony formation assay, and trans-well assay were conducted to assess the viability, migration, and invasion of HTR-8/SVneo and JEG-3 cells.

RESULTS

Our results showed that ADAMTS7 expression was upregulated in PE placentas. Methylation analysis revealed a hypomethylated status of ADAMTS7 promoter regions in PE placenta tissues. Besides, demethylation induced by 5'-Aza directly restored ADAMTS7 expression in trophoblast cells. Finally, overexpression of ADAMTS7 inhibited viability, migration, and invasion of HTR-8/SVneo and JEG-3 cells, while silence of ADAMTS7 by RNA interference reciprocally facilitated cell viability, migration and invasion in vitro.

DISCUSSION

Upregulation of ADAMTS7 by promoter hypomethylation in placenta might contribute to the etiology of PE via suppressing cell functions of trophoblasts.

Exosomes derived from Piwil2‑induced cancer stem cells transform fibroblasts into cancer‑associated fibroblasts

Recently, several studies have demonstrated that cancer cell‑derived exosomes can facilitate tumor development and metastasis formation. However, the detailed function of exosomes released by cancer stem cells (CSCs) requires further investigation. The aim of the present study was to investigate the role of CSC‑derived exosomes in tumor development. For this purpose, Piwil2‑induced cancer stem cells (Piwil2‑iCSCs) were used as exosome‑generating cells, while fibroblasts (FBs) served as recipient cells. Exosomes were isolated by the ultracentrifugation of Piwil2‑iCSC‑conditioned medium and identified by transmission electron microscopy, nanoparticle tracking analysis and western blot analysis. To evaluate the effects of the exosomes on cell proliferation, migration and invasion, cell counting assay (CCK‑8), a wound healing assay and a Transwell assay were performed. Protein expression [matrix metalloproteinase (MMP)2, MMP9, α‑smooth muscle actin (α‑SMA) and vimentin and fibroblast‑activating protein (FAP)] was examined in FBs by western blot analysis. It was found that the Piwil2‑iCSC‑derived exosomes (Piwil2‑iCSC‑Exo) were oval or spherical, membrane‑coated vesicles with a uniform size (30‑100 nm in diameter). They are characterized by the surface expression of CD9, CD63, Hsp70 and Piwil2 proteins. Additional results from functional analyses revealed that Piwil2‑iCSC‑Exo enhanced the proliferative, migratory and invasive abilities of FBs, accompanied by the upregulated expression of MMP2 and MMP9. In addition, the increased expression of α‑SMA (P<0.05), vimentin (P<0.01 vs. control group, P<0.05 vs. PBS group) and FAP (P<0.001 vs. control group, P<0.01 vs. PBS group) following exposure to Piwil2‑iCSC‑Exo suggested that the exosomes induced FB transformation into cancer‑associated fibroblasts (CAFs). On the whole, the findings of this study demonstrate that Piwil2‑iCSC‑Exo induce the cancer‑associated phenotype in fibroblasts in vitro, suggesting that CSCs can promote tumor development through the modulation of the tumor microenvironment.