Impact of Elastin-Derived Peptide VGVAPG on Matrix Metalloprotease-2 and -9 and the Tissue Inhibitor of Metalloproteinase-1, -2, -3 and -4 mRNA Expression in Mouse Cortical Glial Cells In Vitro

Triclosan affects steroidogenesis in mouse primary astrocytes in vitro with engagement of Sirtuin 1 and 3

Triclosan (TCS) is a widely used antimicrobial, antifungal, and antiviral agent. To date, it has been reported that TCS can enter the human body and disrupt hormonal homeostasis. Therefore, the aim of our paper was to evaluate the impact of TCS on astrocytes, i.e. a crucial population of cells responsible for steroid hormone production. Our data showed that, in mouse primary astrocyte cultures, TCS can act as an endocrine disrupting chemical through destabilization of the production or secretion of progesterone (P4), testosterone (T), and estradiol (E2). TCS affects the mRNA expression of enzymes involved in neurosteroidogenesis, such as Cyp17a1, 17β-Hsd, and Cyp19a1. Our data showed that a partial PPARγ agonist (honokiol) prevented changes in Cyp17a1 mRNA expression caused by TCS. Similarly, honokiol inhibited TCS-stimulated P4 release. However, rosiglitazone (classic PPARγ agonist) or GW9662 (PPARγ antagonist) had a much stronger effect. Therefore, we believe that the changes observed in the P4, T, and E2 levels are a result of dysregulation of the activity of the aforementioned enzymes, whose expression can be affected by TCS through a Pparγ-dependent pathway. TCS was found to decrease the aryl hydrocarbon receptor (AhR) and Sirtuin 3 protein levels, which may be the result of the activation of the these proteins. Since our study showed dysregulation of the production or secretion of neurosteroids in astrocytes, it can be concluded that TCS reaching the brain may contribute to the development of neurodegenerative diseases in which an abnormal amount of neurosteroids is observed.

Involvement of the aryl hydrocarbon receptor (AhR) in the mechanism of action of elastin-derived peptide (VGVAPG) and its impact on neurosteroidogenesis

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor from the family of basic helix-loop-helix transcription factors. Several studies have indicated an important role of AhR signaling pathways in senescence, aging, and neurodegenerative diseases. During aging, elastin is degraded and elastin-derived peptides (EDPs) are formed. EDPs have been detected in human blood, serum, and cerebrospinal fluid. Literature data suggest a role of EDPs in the development of neurodegenerative diseases. However, the impact of EDPs on the AhR signaling pathway has never been investigated. Therefore, the aim of our paper was to study the role of AhR in the mechanism of action of the VGVAPG peptide (one of the EDPs) in mouse primary astrocytes in vitro. Our experiments have shown that AhR plays an important role in the EDP mechanism of action in a model of mouse primary astrocytes. Moreover, due to the involvement of Sirt3, Pparγ, AhR, Glb1, Nf-κb1, Ece1, Ide, and Nepr genes and the production and release of neurosteroids, VGVAPG can accelerate the development of neurodegenerative diseases in which the proper metabolism of astrocytes is crucial. Furthermore, our studies have proved that AhR is likely involved in the co-control of the Sirt1, Glb1, Nf-κb1, Ece1, and Nepr expression in astrocytes.

Disruption of neurosteroid synthesis and release by tris(2,3-dibromopropyl)isocyanurate in primary mouse cortical astrocytes in vitro

Neurosteroidogenesis in astrocytes is crucial for the proper development and functioning of the brain. During this process, key neurohormones such as progesterone (P4 ), testosterone (T), and estradiol (E2 ) are produced. Proper production and release of neurosteroids can be affected by substances referred to as endocrine-disrupting compounds (EDCs). Tris-(2,3-dibromopropyl)isocyanurate (TBC) is a representative of novel brominated flame retardants used to stop ignition or reduce fire-related property damage to plastics, polyolefin, polyphenyl alkene, unsaturated polyester, synthetic rubber, and fibers. Interestingly, previous studies have shown that TBC can enhance the proliferation of estradiol-sensitive breast cancers in vitro, which suggests that TBC has EDC properties. Therefore, given the suspected endocrine-disrupting properties of TBC, the aim of the present study was to determine the impact of TBC on the neurosteroid (P4 , T, and E2 ) production and secretion as well as the mRNA expression of key enzymes involved in its production in mouse astrocytes in vitro. Our paper shows that TBC increases P4 production with a strong decrease in T production, which is accompanied by a decrease in Cyp17a1 mRNA expression, that is, the main enzyme metabolizing P4 to T. Moreover, TBC in both studied concentrations increases P4 secretion in the culture medium. Finally, our studies have demonstrated an increase in the expression of Cyp19a1 mRNA, an enzyme metabolizing T to E2 , with a simultaneous increase in the amount of E2 in cells. Our data clearly show that TBC in an in vitro environment acts as EDCs, which may lead to serious consequences for the proper development and functioning of the brain.

Involvement of the peroxisome proliferator-activated receptor gamma (Pparγ) and matrix metalloproteinases-2 and -9 (Mmp-2 and -9) in the mechanism of action of di(2-ethylhexyl)phthalate (DEHP) in cultured mouse brain astrocytes and neurons

Di(2-ethylhexyl)phthalate (DEHP) is one of the most widely used phthalates in industry. It has been shown that, after entering the body, DEHP has the ability to cross the blood-placenta and blood-brain barriers. One of the proposed mechanisms of action of DEHP is the activation of peroxisome proliferator-activated receptors (PPARs). Many different functions of PPARγ in cells have been demonstrated, one of which is the modulation of the activation of matrix metalloproteinases (MMPs). The aim of this study was to investigate the role of Pparγ, Mmp-2, and Mmp-9 in the mechanism of action of DEHP. The experiments were performed on in vitro primary murine neurons and astrocytes. The results showed that DEHP has a pro-apototic effect on neurons, causing an increase in caspase-3 activity and in the number of apoptotic bodies. However, in astrocytes, the increase in caspase-3 activity was not related to the apoptosis process, as no increase in the formation of apoptotic bodies was observed. Moreover, DEHP increased the proliferation of astrocytes, which was confirmed by the increase in the amount and expression of the Ki-67 protein. In astrocytes, DEHP decreased the expression of the Pparγ and Mmp-9 proteins but increased the expression of the Mmp-2 protein. In DEHP neurons, it increased the expression of the Pparγ protein but decreased the expression of the Mmp-2 and Mmp-9 proteins.

Tris(2,3-dibromopropyl)Isocyanurate has an Effect on Inflammation Markers in Mouse Primary Astrocytes In vitro

Tris(2,3-dibromopropyl)isocyanurate (TBC or TDBP-TAZTO) is a new brominated flame retardant (BFR) used as a replacement of classic BFR, such as tetrabromobisphenol A. TBC is supposed to be safer than classic BFRs, but reports show that it may induce a similar toxic effect. Therefore, the aim of the present study was to determine the impact of TBC on the inflammation and activation of the apoptosis process in mouse cortical astrocytes in vitro. Our results have shown that TBC increases caspase-1 and caspase-3 activity in mouse astrocytes in vitro, which suggests inflammation-induced apoptosis. Further analyses have revealed that TBC indeed increases the level of inflammation markers, e.g. Cat, IL-1β and IL-1βR1 proteins, but decreases the level of proliferation marker protein Ki67. However, our study has demonstrated that TBC does not change the morphology of astrocytes and does not increase the number of apoptotic bodies - a well-established marker of late apoptosis. Moreover, the concentration of 50 µM TBC also increases caspase-3 activity with no formation of apoptotic bodies. However, since 10 and 50 µM TBC have never been detected in living organisms, we can assume that the compound is safe at the low concentrations that are detected.

Elastin-Derived VGVAPG Fragment Decorated Cell-Penetrating Peptide with Improved Gene Delivery Efficacy

Cell-penetrating peptides (CPPs) are attractive non-viral gene delivery vectors due to their high transfection capacity and safety. Previously, we have shown that cell-penetrating peptide RALA can be a promising gene delivery vector for chronic wound regeneration application. In this study, we engineered a novel peptide called RALA-E by introducing elastin-derived VGVAPG fragment into RALA, in order to target the elastin-binding protein on the cell surface and thus improve delivery efficacy of RALA. The transfection efficiency of RALA-E was evaluated by transfecting the HEK-293T and HeLa cell lines cells with RALA-E/pDNA complexes and the flow-cytometry results showed that RALA-E significantly increased the transfection efficiency by nearly 20% in both cell lines compared to RALA. Inhibition of pDNA transfection on HEK-293T cells via chlorpromazine, genistein and mβCD showed that the inhibition extent in transfection efficiency was much less for RALA-E group compared to RALA group. In addition, RALA-E/miR-146a complexes showed up to 90% uptake efficiency in macrophages, and can escape from the endosome and enter the nucleus to inhibit the expression of inflammation genes. Therefore, the developed RALA-E peptide has high potential as a safe and efficient vector for gene therapy application.

Understanding Acquired Brain Injury: A Review

Any type of brain injury that transpires post-birth is referred to as Acquired Brain Injury (ABI). In general, ABI does not result from congenital disorders, degenerative diseases, or by brain trauma at birth. Although the human brain is protected from the external world by layers of tissues and bone, floating in nutrient-rich cerebrospinal fluid (CSF); it remains susceptible to harm and impairment. Brain damage resulting from ABI leads to changes in the normal neuronal tissue activity and/or structure in one or multiple areas of the brain, which can often affect normal brain functions. Impairment sustained from an ABI can last anywhere from days to a lifetime depending on the severity of the injury; however, many patients face trouble integrating themselves back into the community due to possible psychological and physiological outcomes. In this review, we discuss ABI pathologies, their types, and cellular mechanisms and summarize the therapeutic approaches for a better understanding of the subject and to create awareness among the public.

Irigenin reduces the expression of caspase-3 and matrix metalloproteinases, thus suppressing apoptosis and extracellular matrix degradation in TNF-α-stimulated nucleus pulposus cells

Irigenin, an isoflavonoid isolated from the rhizome of Belamcanda chinensis, possess various pharmacological effects. However, the effect and mechanism of irigenin on intervertebral disc degeneration (IDD) remain unclear. The potential targets of irigenin or disease were predicted using PharmMapper or GeneCards databases, respectively. The overlapping targets were inputted into the String database to establish protein-protein interaction (PPI) network. The overlapping targets were also submitted to DAVID webserver to perform gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Nucleus pulposus (NP) cells were exposed to 10 ng/mL tumor necrosis factor-α (TNF-α) to establish a cell model of IDD. Cell viability, LDH content, apoptosis and caspase-3 activity were evaluated by CCK-8, LDH release, TUNEL, and caspase-3 activity assays, respectively. The expression of collagen II, aggrecan, matrix metalloproteinase (MMP)-2, MMP-3, MMP-9, and MMP-13 were detected by qRT-PCR and western blot analyses. The network analysis revealed that MMP-2, MMP-3, MMP-9, MMP-13, caspase-3 (CASP3), vitamin D receptor (VDR), insulin-like growth factor 1 (IGF1), and transforming growth factor beta2 (TGFB2) play key roles in the effect of irigenin against IDD. TNF-α stimulation inhibited cell viability and increased LDH content, apoptosis, caspase-3 expression and caspase-3 activity in NP cells, which were reversed by irigenin treatment. TNF-α stimulation inhibited the expression of collagen II and aggrecan and upregulated MMPs (MMP-2, MMP-3, MMP-9, and MMP-13) in NP cells, while such changes were abolished by irigenin treatment. In conclusion, irigenin suppressed apoptosis and ECM degradation in TNF-α-stimulated NP cells by reducing the expression of caspase-3 and MMPs.

Elastin-Derived Peptides in the Central Nervous System: Friend or Foe

Elastin is one of the main structural matrix proteins of the arteries, lung, cartilage, elastic ligaments, brain vessels, and skin. These elastin fibers display incredible resilience and structural stability with long half-life. However, during some physiological and pathophysiological conditions, elastin is prone to proteolytic degradation and, due to the extremely low turnover rate, its degradation is practically an irreversible and irreparable phenomenon. As a result of elastin degradation, new peptides called elastin-derived peptides (EDPs) are formed. A growing body of evidence suggests that these peptides play an important role in the development of age-related vascular disease. They are also detected in the cerebrospinal fluid of healthy people, and their amount increases in patients after ischemic stroke. Recently, elastin-like polypeptides have been reported to induce overproduction of beta-amyloid in a model of Alzheimer's disease. Nevertheless, the role and mechanism of action of EDPs in the nervous system is largely unknown and limited to only a few studies. The article summarizes the current state of knowledge on the role of EDPs in the nervous system.

Age-associated proinflammatory elastic fiber remodeling in large arteries

Elastic fibers are the main components of the extracellular matrix of the large arterial wall. Elastic fiber remodeling is an intricate process of synthesis and degradation of the core elastin protein and microfibrils accompanied by the assembly and disassembly of accessory proteins. Age-related morphological, structural, and functional proinflammatory remodeling within the elastic fiber has a profound effect upon the integrity, elasticity, calcification, amyloidosis, and stiffness of the large arterial wall. An age-associated increase in arterial stiffness is a major risk factor for the pathogenesis of diseases of the large arteries such as hypertensive and atherosclerotic vasculopathy. This mini review is an update on the key molecular, cellular, functional, and structural mechanisms of elastic fiber proinflammatory remodeling in large arteries with aging. Targeting structural and functional integrity of the elastic fiber may be an effective approach to impede proinflammatory arterial remodeling with advancing age.

AG-9, an Elastin-Derived Peptide, Increases In Vitro Oral Tongue Carcinoma Cell Invasion, through an Increase in MMP-2 Secretion and MT1-MMP Expression, in a RPSA-Dependent Manner

Oral tongue squamous cell carcinoma is one of the most prevalent head and neck cancers. During tumor progression, elastin fragments are released in the tumor microenvironment. Among them, we previously identified a nonapeptide, AG-9, that stimulates melanoma progression in vivo in a mouse melanoma model. In the present paper, we studied AG-9 effect on tongue squamous cell carcinoma invasive properties. We demonstrated that AG-9 stimulates cell invasion in vitro in a modified Boyen chamber model. It increases MMP-2 secretion, analyzed by zymography and MT1-MMP expression, studied by Western blot. The stimulatory effect was mediated through Ribosomal Protein SA (RPSA) receptor binding as demonstrated by SiRNA experiments. The green tea-derived polyphenol, (−)-epigallocatechin-3-gallate (EGCG), was previously shown to bind RPSA. Molecular docking experiments were performed to compare the preferred areas of interaction of AG-9 and EGCG with RPSA and suggested overlapping areas. This was confirmed by competition assays. EGCG abolished AG-9-induced invasion, MMP-2 secretion, and MT1-MMP expression.

Elastases and elastokines: elastin degradation and its significance in health and disease

Elastin is an important protein of the extracellular matrix of higher vertebrates, which confers elasticity and resilience to various tissues and organs including lungs, skin, large blood vessels and ligaments. Owing to its unique structure, extensive cross-linking and durability, it does not undergo significant turnover in healthy tissues and has a half-life of more than 70 years. Elastin is not only a structural protein, influencing the architecture and biomechanical properties of the extracellular matrix, but also plays a vital role in various physiological processes. Bioactive elastin peptides termed elastokines - in particular those of the GXXPG motif - occur as a result of proteolytic degradation of elastin and its non-cross-linked precursor tropoelastin and display several biological activities. For instance, they promote angiogenesis or stimulate cell adhesion, chemotaxis, proliferation, protease activation and apoptosis. Elastin-degrading enzymes such as matrix metalloproteinases, serine proteases and cysteine proteases slowly damage elastin over the lifetime of an organism. The destruction of elastin and the biological processes triggered by elastokines favor the development and progression of various pathological conditions including emphysema, chronic obstructive pulmonary disease, atherosclerosis, metabolic syndrome and cancer. This review gives an overview on types of human elastases and their action on human elastin, including the formation, structure and biological activities of elastokines and their role in common biological processes and severe pathological conditions.

In vitro effect of vanadyl sulfate on cultured primary astrocytes: cell viability and oxidative stress markers

Exposure to vanadium has been associated with deleterious effects on the central nervous system in animals and humans. Although vanadium-derived pro-oxidant species were reported to be involved in vanadium-mediated neurotoxicity, the ability of this metal to induce oxidative stress markers in glial cells remains to be elucidated. In this study, we investigated the cytotoxicity and the generation of reactive oxygen species (ROS) and nitric oxide (NO) by mouse primary astrocytes after treatment with vanadyl sulfate (VOSO₄ ) at concentrations of 20, 50, 100, 200, and 500 μM. The resazurin assay revealed that treatment with VOSO₄ for 24 and 48 h at concentrations of 50 and 100 μM, respectively, or higher substantially induced astrocytic cytotoxicity. Intracellular ROS increased after 6-h exposure to the lowest concentration tested (20 μM VOSO₄ ) and tended to intensify after 24- and 48-h treatments reaching significant values for 20 and 500 μM VOSO₄ . In turn, NO production in the examined cells was elevated after exposure to all concentrations at the 6-, 24-, and 48-h incubation periods. Our study demonstrated the ability of VOSO₄ to induce H₂ O₂ generation in cell-free DMEM/F12 medium. The H₂ O₂ levels were in the micromolar range (up to 5 μM) and were detected mostly during the first few minutes after VOSO₄ addition, suggesting that the generated H₂ O₂ could not induce toxic effects on the cells. Taken together, these results show VOSO₄ induced cytotoxicity in primary astrocyte cells, which may have resulted from vanadyl-stimulated intracellular ROS and NO generation in these cells.

The Elastin-Derived Peptide VGVAPG Does Not Activate the Inflammatory Process in Mouse Cortical Astrocytes In Vitro

During vascular aging or in pathological conditions in humans, elastin is degraded and its by-products, the elastin-derived peptides (EDPs), enter the blood circulation. EDPs may be detected in the serum of healthy subjects or people who suffered a stroke. Moreover, recent evidence suggests a potential role of inflammatory mechanisms in neurological conditions, which are usually not categorized as inflammatory. Therefore, the present in vitro study was conducted to investigate the impact of the VGVAPG peptide on the activation of inflammatory process in mouse primary astrocytes, which were maintained in phenol red-free DMEM/F12 supplemented with 10% fetal bovine serum. The cells were exposed to VGVAPG or VVGPGA peptides for 24 and 48 h; this was followed by the determination of the activity of caspase-1 and levels of SOD, CAT, PPARγ, NF-κB, IL-1β, and IL-1βR1. Furthermore, rosiglitazone-a PPARγ agonist-was applied. Our study pioneered the finding that the VGVAPG peptide increases caspase-1 activity in astrocytes in vitro. The VGVAPG peptide simultaneously decreases the release of IL-1β into the cell-culture medium from astrocytes. The ELISA method revealed that the VGVAPG peptide increases the protein expression of SOD1 whereas it decreases the expression of IL-1βR1, CAT, and NF-κB. Therefore, the available data suggest that the VGVAPG peptide (concentration 10 nM) synergistically acts with agonists of PPARγ in mouse astrocytes. However, given the lack of sufficient data to explain the molecular mechanism of action of the VGVAPG peptide in the nervous system, more studies in this area are necessary.

Specific role of N-methyl-D-aspartate (NMDA) receptor in elastin-derived VGVAPG peptide-dependent calcium homeostasis in mouse cortical astrocytes in vitro

Under physiological and pathological conditions, elastin is degraded to produce elastin-derived peptides (EDPs). EDPs are detected in the healthy human brain, and its concentration significantly increases after ischemic stroke. Both elastin and EDPs contains replications of the soluble VGVAPG hexapeptide, which has a broad range of biological activities. Effects of VGVAPG action are mainly mediated by elastin-binding protein (EBP), which is alternatively spliced, enzymatically inactive form of the GLB1 gene. This study was conducted to elucidate the activation and role of the N-methyl-D-aspartate receptor (NMDAR) in elastin-derived VGVAPG peptide-dependent calcium homeostasis in mouse cortical astrocytes in vitro. Cells were exposed to 10 nM VGVAPG peptide and co-treated with MK-801, nifedipine, verapamil, or Src kinase inhibitor I. After cell stimulation, we measured Ca²⁺ level, ROS production, and mRNA expression. Moreover, the Glb1 and NMDAR subunits (GluN1, GluN2A, and GluN2B) siRNA gene knockdown were applied. We found the VGVAPG peptide causes Ca²⁺ influx through the NMDA receptor in mouse astrocytes in vitro. Silencing of the Glb1, GluN1, GluN2A, and GluN2B gene prevented VGVAPG peptide-induced increase in Ca²⁺. Nifedipine does not completely reduce VGVAPG peptide-activated ROS production, whereas MK-801, verapamil, and Src inhibitor reduce VGVAPG peptide-activated Ca²⁺ influx and ROS production. These data suggest the role of Src kinase signal transduction from EBP to NMDAR. Moreover, the VGVAPG peptide affects the expression of NMDA receptor subunits.

Elastin-Derived Peptide VGVAPG Affects Production and Secretion of Testosterone in Mouse Astrocyte In Vitro

Astrocytes play many distinct roles in the nervous system providing structural support for neurons and maintaining blood-brain barrier integrity. Steroid hormones exhibit a broad spectrum of actions in the central and peripheral nervous system, acting as trophic factors affecting cell differentiation and synaptic plasticity. In steroidogenesis, astrocytes play a key role by producing cholesterol, progesterone (P₄), testosterone (T), and estradiol (E₂). Currently there are only few studies which show that the Gly-Val-Ala-Pro-Gly (VGVAPG) peptide may affect the metabolism of astrocytes. Therefore, due to the role of neurosteroids, it is necessary to determine whether VGVAPG affects the level of E₂, P₄, and T in astrocytes. Primary mouse astrocytes were maintained in DMEM/F12 without phenol red, and supplemented with 10% charcoal/dextran-treated fetal bovine serum. Cells were exposed to 10 nM and 1 µM VGVAPG peptide and co-treated with cSrc kinase inhibitor I. After cell stimulation, we measured the Ki67 protein level and the production and secretion of P₄, T, and E₂. Our report presents the novel finding that the VGVAPG peptide affects the production and secretion of neurosteroids in astrocytes in vitro. The VGVAPG peptide increases the production of P₄; however, at the same time, it decreases the secretion of P₄ by astrocytes. On the other hand, it stimulates the production and secretion of T. Interestingly, the production of E₂ did not change in any studied time interval. The expression of Ki67 protein increased after 48 h of exposition to the VGVAPG peptide. The cSrc kinase inhibitor I prevented most of the effects of VGVAPG peptide. Therefore, we postulate that T and cSrc kinase may be responsible for increasing astrocyte proliferation.

Elastin-derived peptide VGVAPG affects the proliferation of mouse cortical astrocytes with the involvement of aryl hydrocarbon receptor (Ahr), peroxisome proliferator-activated receptor gamma (Pparγ), and elastin-binding protein (EBP)

During aging and ischemic and hemorrhagic stroke, elastin molecules are degraded and elastin-derived peptides are released into the brain microenvironment. Val-Gly-Val-Ala-Pro-Gly (VGVAPG) is a repeating hexapeptide in the elastin molecule. It is well documented that the peptide sequence binds with high affinity to elastin-binding protein (EBP) located on the cell surface, thereby transducing a molecular signal into the cell. The aim of our study was to investigate whether EBP, aryl hydrocarbon receptor (Ahr), and peroxisome proliferator-activated receptor gamma (Pparγ) are involved in VGVAPG-stimulated proliferation. Primary astrocytes were maintained in DMEM/F12 medium without phenol red, supplemented with 10 or 1% charcoal/dextran-treated fetal bovine serum (FBS). The cells were exposed to increasing concentrations of VGVAPG peptide, and resazurin reduction was measured. In addition, Glb1, Pparγ, and Ahr genes were silenced. After 48 h of exposure to 10 nM and 1 µM of VGVAPG peptide, the level of estradiol (E₂) and the expression of Ki67 and S100B proteins were measured. The results showed that at a wide range of concentrations, VGVAPG peptide increased the metabolism of astrocytes depending on the concentration of FBS. After silencing of Glb1, Pparγ, and Ahr genes, VGVAPG peptide did not affect the cell metabolism which suggests the involvement of all the mentioned receptors in its mechanism of action. Interestingly, in the low-FBS medium, the silencing of Glb1 gene did not result in complete inhibition of VGVAPG-stimulated proliferation. On the other hand, in the medium with 10% FBS VGVAPG increased Ki67 expression after Pparγ silencing, whereas in the medium with 1% FBS VGVAPG decreased Ki67 expression. Following the application of Ahr siRNA, VGVAPG peptide decreased the production of E₂ and increased the expression of Ki67 and S100B proteins.

The role of elastin-derived peptides in human physiology and diseases

Once considered as inert, the extracellular matrix recently revealed to be biologically active. Elastin is one of the most important components of the extracellular matrix. Many vital organs including arteries, lungs and skin contain high amounts of elastin to assure their correct function. Physiologically, the organism contains a determined quantity of elastin from the early development which may remain physiologically constant due to its very long half-life and very low turnover. Taking into consideration the continuously ongoing challenges during life, there is a physiological degradation of elastin into elastin-derived peptides which is accentuated in several disease states such as obstructive pulmonary diseases, atherosclerosis and aortic aneurysm. These elastin-derived peptides have been shown to have various biological effects mediated through their interaction with their cognate receptor called elastin receptor complex eliciting several signal transduction pathways. In this review, we will describe the production and the biological effects of elastin-derived peptides in physiology and pathology.

Antiproliferative Effect of Elastin-Derived Peptide VGVAPG on SH-SY5Y Neuroblastoma Cells

Throughout the lifetime of humans, the amount of stem cells and the rate of cell proliferation continue to decrease. Reactive oxygen species (ROS) are one among the many factors that promote stem cell aging. Both a decrease in the level of stem cells and increase in ROS production can lead to the development of different neurodegenerative diseases. This study was conducted to determine how the VGVAPG peptide, liberated from elastin during the aging process and under pathological conditions, affects ROS production and activities of antioxidant enzymes in undifferentiated, proliferating SH-SY5Y cells. SH-SY5Y cells were maintained in Dulbecco's modified Eagle's medium/nutrient mixture F-12 supplemented with 10% heat-inactivated fetal bovine serum (FBS). After treating the SH-SY5Y cells with VGVAPG peptide, we measured ROS production; cell metabolism, proliferation, and expression; and activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). We demonstrated that the VGVAPG peptide increases GPx expression and activity, whereas it decreases CAT expression in SH-SY5Y cells. Silencing of the GLB1 gene prevents changes in GPx activity. Despite the fact that the VGVAPG peptide increases GPx expression, it increases the ROS level. Moreover, the VGVAPG peptide decreases SH-SY5Y proliferation, which is prevented by the ROS scavenger N-acetyl-L-cysteine. Our data suggest that ROS production and decreased proliferation of SH-SY5Y cells are the results of excitotoxicity meditated through close unrecognized molecular pathways. More research is needed to elucidate the unknown mechanism of action of VGVAPG peptide in the nervous system.

The VGVAPG Peptide Regulates the Production of Nitric Oxide Synthases and Reactive Oxygen Species in Mouse Astrocyte Cells In Vitro

The products of elastin degradation, namely elastin-derived peptides (EDPs), are detectable in the cerebrospinal fluid of healthy individuals and in patients after ischemic stroke, and their number increases with age. Depending on their concentrations, both nitric oxide (NO) and reactive oxygen species (ROS) take part either in myocardial ischemia reperfusion injury or in neurovascular protection after ischemic stroke. The aim of our study was to determine the impact of VGVAPG peptide on ROS and NO production and expression of endothelial nitric oxide synthase (eNos), inducible nitric oxide synthase (iNos) and neuronal nitric oxide synthase (nNos) in mouse cortical astrocytes in vitro. Primary astrocytes were maintained in DMEM/F12 without phenol red supplemented with 10% fetal bovine serum. The cells were exposed to rising VGVAPG peptide concentrations, and ROS and NO production was measured. After 6 h (for mRNA) and 24 (for the protein) of exposure to 10 nM and 1 µM of the peptide, expression of nNos, iNos and eNos was measured. Moreover, the Glb1 siRNA gene knockdown method and Pioglitazone, a peroxisome proliferator-activated receptor gamma (Pparγ) agonist, were applied. Our study shows that the VGVAPG peptide decreased eNos, iNos and nNos mRNA and protein expression in mouse astrocytes in vitro. The VGVAPG peptide also decreased NO production while increasing ROS production in the cells. Furthermore, silencing of the Glb1 gene reversed all effects caused by the VGVAPG peptide. However, due to the lack of sufficient data explaining the molecular mechanism of action of the VGVAPG peptide in the nervous system, more studies in this area are necessary.

The Action of Di-(2-Ethylhexyl) Phthalate (DEHP) in Mouse Cerebral Cells Involves an Impairment in Aryl Hydrocarbon Receptor (AhR) Signaling

Di-(2-ethylhexyl) phthalate (DEHP) is used as a plasticizer in various plastic compounds, such as polyvinyl chloride (PVC), and products including baby toys, packaging films and sheets, medical tubing, and blood storage bags. Epidemiological data suggest that phthalates increase the risk of the nervous system disorders; however, the impact of DEHP on the brain cells and the mechanisms of its action have not been clarified. The aim of the present study was to investigate the effects of DEHP on production of reactive oxygen species (ROS) and aryl hydrocarbon receptor (AhR), as well as Cyp1a1 and Cyp1b1 mRNA and protein expression in primary mouse cortical neurons and glial cells in the in vitro mono-cultures. Our experiments showed that DEHP stimulated ROS production in both types of mouse neocortical cells. Moreover, the results strongly support involvement of the AhR/Cyp1A1 signaling pathway in the action of DEHP in neurons and glial cells. However, the effects of DEHP acting on the AhR signaling pathways in these two types of neocortical cells were different. In neurons, AhR mRNA expression did not change, but AhR protein expression decreased in response to DEHP. A similar trend was observed for Cyp1a1 and Cyp1b1 mRNA and protein expression. Failure to induce Cyp1a1 in neurons was confirmed by EROD assay. In primary glial cells, a decrease in AhR protein level was accompanied by a decrease in AhR mRNA expression. In glial cells, mRNA and protein expression of Cyp1a1 as well as Cyp1a1-related EROD activity were significantly increased. As for Cyp1b1, both in neurons and glial cells Cyp1b1 mRNA expression did not significantly change, whereas Cyp1b1 protein level were decreased. We postulate that developmental exposure to DEHP which dysregulates AhR/Cyp1a1 may disrupt defense processes in brain neocortical cells that could increase their susceptibility to environmental toxins.

Impact of elastin-derived VGVAPG peptide on bidirectional interaction between peroxisome proliferator-activated receptor gamma (Pparγ) and beta-galactosidase (β-Gal) expression in mouse cortical astrocytes in vitro

The process of degradation of the elastin-rich extracellular matrix produces elastin-derived peptides (EDPs). Different types of EDPs are detectable in the cerebrospinal fluid in healthy individuals and in patients after ischemic stroke. To date, it has been demonstrated that EDPs can regulate the development of insulin resistance in mice in a peroxisome proliferator-activated receptor gamma (Pparγ)-dependent manner. Therefore, the aim of this study was to investigate the impact of the elastin-derived valine-glycine-valine-alanine-proline-glycine (VGVAPG) peptide on Pparγ and beta-galactosidase (β-Gal) expression in mouse cortical astrocytes in vitro. Primary astrocytes were maintained in DMEM/F12 without phenol red supplemented with 10% fetal bovine serum. The cells were exposed to 50 nM, 1 and 50 μM of the VGVAPG peptide. After 3 and 6 h (for mRNA) and 24 and 48 h (for the protein) of exposition to the peptide, the expression of Pparγ and β-Gal was measured. Moreover, the siRNA gene knockdown method was applied. Our study showed, for the first time, that the VGVAPG peptide affected β-Gal and Pparγ mRNA and protein expression in mouse astrocytes in vitro. Furthermore, we suggested a bidirectional interaction between Pparγ and β-Gal. Both pioglitazone and rosiglitazone increased β-Gal and Pparγ protein expression in mouse astrocytes in vitro, and this effect was reduced by the VGVAPG peptide. However, due to the lack of sufficient data explaining the molecular mechanism of action of the VGVAPG peptide in the nervous system, more studies are necessary in this field.