The effect of a hydroxamic acid-containing polymer on active matrix metalloproteinases

Overview of class I HDAC modulators: Inhibitors and degraders

Class I histone deacetylases (HDACs) are closely associated with the development of a diverse array of diseases, including cancer, neurodegenerative disorders, HIV, and inflammatory diseases. Considering the essential roles in tumorigenesis, class I HDACs have emerged as highly desirable targets for therapeutic strategies, particularly in the field of anticancer drug development. However, the conventional class I HDAC inhibitors faced several challenges such as acquired resistance, inherent toxicities, and limited efficacy in inhibiting non-enzymatic functions of HDAC. To address these problems, novel strategies have emerged, including the development of class I HDAC dual-acting inhibitors, targeted protein degradation (TPD) technologies such as PROTACs, molecular glues, and HyT degraders, as well as covalent inhibitors. This review provides a comprehensive overview of class I HDAC enzymes and inhibitors, by initially introducing their structure and biological roles. Subsequently, we focus on the recent advancements of class I HDAC modulators, including isoform-selective class I inhibitors, dual-target inhibitors, TPDs, and covalent inhibitors, from the perspectives of rational design principles, pharmacodynamics, pharmacokinetics, and clinical progress. Finally, we also provide the challenges and outlines future prospects in the realm of class I HDAC-targeted drug discovery for cancer therapeutics.

Zn-containing Adhesives Facilitate Collagen Protection and Remineralization at the Resin-Dentin Interface: A Narrative Review

This is a narrative review of the literature assessing the potential effectiveness of doping dentin polymeric adhesives with zinc compounds in order to improve bonding efficacy, remineralization and protection against degradation. A literature search was conducted using electronic databases, such as PubMed, MEDLINE, DIMDI and Web of Science. Through our search, we found literature demonstrating that Zn-doped dentin adhesives promote protection and remineralization of the resin-dentin interfaces. The increased bioactivity has also facilitated dentinal tubules' occlusion by crystals' precipitation contributing to improved sealing efficacy of restorations. Loading dentin adhesives with zinc gives rise to an increase of both crystallinity of mineral and crosslinking of collagen. The main role of zinc, in dentin adhesives, is to inhibit collagen proteolysis. We concluded that zinc exerts a protective effect through binding at the collagen-sensitive cleavage sites of matrix-metalloproteinases (MMPs), contributing to dentin matrix stabilization. Zinc may not only act as a MMPs inhibitor, but also influence signaling pathways and stimulate metabolic effects in dentin mineralization and remineralization processes. Zn-doped adhesives increase the longevity of dentin bonding through MMPs inhibition. Zn poses a remineralization strategy in demineralized dentin.

Hydroxamic Acid: An Underrated Moiety? Marrying Bioinorganic Chemistry and Polymer Science

Even 150 years after their discovery, hydroxamic acids are mainly known as the starting material for the Lossen rearrangement in textbooks. However, hydroxamic acids feature a plethora of existing and potential applications ranging from medical purposes to materials science, based on their excellent complexation properties. This underrated functional moiety can undergo a broad variety of organic transformations and possesses unique coordination properties for a large variety of metal ions, for example, Fe(III), Zn(II), Mn(II), and Cr(III). This renders it ideal for biomedical applications in the field of metal-associated diseases or the inhibition of metalloenzymes, as well as for the separation of metals. Considering their chemical stability and reactivity, their biological origin and both medical and industrial applications, this Perspective aims at highlighting hydroxamic acids as highly promising chelators in the fields of both medical and materials science. Furthermore, the state of the art in combining hydroxamic acids with a variety of polymer structures is discussed and a perspective regarding their vast potential at the interface of bioinorganic and polymer chemistry is given.

A hydroxamic acid–methacrylated collagen conjugate for the modulation of inflammation-related MMP upregulation

The selective covalent coupling of hydroxamic acid functions on to methacrylated type I collagen led to UV-cured networks with inherent MMP-modulating capability and enhanced proteolytic stability.

Synthesis of a poly(amidoxime-hydroxamic acid) cellulose derivative and its application in heavy metal ion removal

A new poly(amidoxime-hydroxamic acid) chelating cellulosic adsorbent was synthesized through grafting only one monomer, followed by the oximation reaction.

Considerations on inhibition approaches for proinflammatory functions of ADAM proteases

Proteases of the disintegrin and metalloproteinase (ADAM) family mediate the proteolytic shedding of various surface molecules including cytokine precursors, adhesion molecules, growth factors, and receptors. Within the vasculature ADAM10 and ADAM17 regulate endothelial permeability, transendothelial leukocyte migration, and the adhesion of leukocytes and platelets. In vivo studies show that both proteases are implicated in several inflammatory pathologies, for example, edema formation, leukocyte infiltration, and thrombosis. However, both proteases also contribute to developmental and regenerative processes. Thus, although ADAMs can be regarded as valuable drug targets in many aspects, the danger of severe side effects is clearly visible. To circumvent these side effects, traditional inhibition approaches have to be improved to target ADAMs at the right time in the right place. Moreover, the inhibitors need to be more selective for the target protease and if possible also for the substrate. Antibodies recognizing the active conformation of ADAMs or small molecules blocking exosites of ADAM proteases may represent inhibitors with the desired selectivities.

Matrix metalloproteinases in exercise and obesity

Matrix metalloproteinases (MMPs) are zinc- and calcium-dependent endoproteinases that have the ability to break down extracellular matrix. The large range of MMPs’ functions widens their spectrum of potential role as activators or inhibitors in tissue remodeling, cardiovascular diseases, and obesity. In particular, MMP-1, -2, and -9 may be associated with exercise and obesity. Thus, the current study reviewed the effects of different types of exercise (resistance and aerobic) on MMP-1, -2, and -9. Previous studies report that the response of MMP-2 and -9 to resistance exercise is dependent upon the length of exercise training, since long-term resistance exercise training increased both MMP-2 and -9, whereas acute bout of resistance exercise decreased these MMPs. Aerobic exercise produces an inconsistent result on MMPs, although some studies showed a decrease in MMP-1. Obesity is related to a relatively lower level of MMP-9, indicating that an exercise-induced increase in MMP-9 may positively influence obesity. A comprehensive understanding of the relationship between exercise, obesity, and MMPs does not exist yet. Future studies examining the acute and chronic responses of these MMPs using different subject models may provide a better understanding of the molecular mechanisms that are associated with exercise, obesity, and cardiovascular disease.

A green approach to crosslinked polymer microspheres with undoped methacrylate monomers and their potential application as dental restorative materials

Pure polymer microspheres with undoped methacrylate monomers were prepared and firstly applied as organic fillers for dental restorative materials.

Polymer nanocarriers for dentin adhesion

To obtain more durable adhesion to dentin, and to protect collagen fibrils of the dentin matrix from degradation, calcium- and phosphate-releasing particles have been incorporated into the dental adhesive procedure. The aim of the present study was to incorporate zinc-loaded polymeric nanocarriers into a dental adhesive system to facilitate inhibition of matrix metalloproteinases (MMPs)-mediated collagen degradation and to provide calcium ions for mineral deposition within the resin-dentin bonded interface. PolymP- N : Active nanoparticles (nanoMyP) were zinc-loaded through 30-minute ZnCl2 immersion and tested for bioactivity by means of 7 days' immersion in simulated body fluid solution (the Kokubo test). Zinc-loading and calcium phosphate depositions were examined by scanning and transmission electron microscopy, elemental analysis, and x-ray diffraction. Nanoparticles in ethanol solution infiltrated into phosphoric-acid-etched human dentin and Single Bond (3M/ESPE) were applied to determine whether the nanoparticles interfered with bonding. Debonded sticks were analyzed by scanning electron microscopy. A metalloproteinase collagen degradation assay was also performed in resin-infiltrated dentin with and without nanoparticles, measuring C-terminal telopeptide of type I collagen (ICTP) concentration in supernatants, after 4 wk of immersion in artificial saliva. Numerical data were analyzed by analysis of variance (ANOVA) and Student-Newman-Keuls multiple comparisons tests (p < .05). Nanoparticles were effectively zinc-loaded and were shown to have a chelating effect, retaining calcium regardless of zinc incorporation. Nanoparticles failed to infiltrate demineralized intertubular dentin and remained on top of the hybrid layer, without altering bond strength. Calcium and phosphorus were found covering nanoparticles at the hybrid layer, after 24 h. Nanoparticle application in etched dentin also reduced MMP-mediated collagen degradation. Tested nanoparticles may be incorporated into dental adhesive systems to provide the appropriate environment in which dentin MMP collagen degradation is inhibited and mineral growth can occur.

Masticatory function induced changes, at subnanostructural level, in proteins and mineral at the resin-dentine interface

OBJECTIVE

This study evaluated the ability of different in vitro mechanical loading tests to promote new mineral formation at the bonded dentine interfaces created with a two-step self-etching resin adhesive.

METHODOLOGY

Restored teeth were divided in the following groups: (1) unloaded, load cycling with (2) sine waveform, (3) square waveform, and hold waveform for (4) 24h, and (5) 72 h. Raman spectroscopy and cluster analysis were used to assess the resin-dentine interface.

RESULTS

Mechanical loading in CSEB-treated samples promoted a generalized increase of relative presence of minerals and ratio of phosphate peaks, except in square waveform, where the nature of collagen resulted damaged. Crystallinity of carbonate was higher than phosphate. The organic component showed, in general terms, an increase in crosslinking. Molecular orientation (α-helices) peaks augmented in all tests. Pentosidine vibration increases in all tests, except in hold 72 h. Ratios amide I and II/CH2 incremented, in general. Non uniform parameters of Bis-GMA and adhesive penetration were encountered, as both increased at the bottom of the hybrid layer when loading square and hold 72 h were applied.

SIGNIFICANCE

Functional remineralisation at the resin-dentine interface was attained after in vitro mechanical stimuli application. When loading in square waveform, the lowest vibrations to favor remineralisation were attained.

A ZnO-doped adhesive reduced collagen degradation favouring dentine remineralization

OBJECTIVES

The objective of the study was to determine the efficacy of a ZnO-doped etch and rinse adhesive in decreasing MMPs-mediated collagen degradation at the resin-dentine hybrid layer, and increasing bonding stability.

METHODS

C-terminal telopeptide concentrations (ICTP) were determined after 24h, 1wk and 4wk in human dentine beams. Dentine was treated: (1) 37% phosphoric acid for 15s (PA), (2) PA-etched dentine infiltrated with Single Bond (SB), (3) PA-etched dentine infiltrated with ZnO doped SB (ZnO particles--10wt%--were added to the bonding resin) (ZnO-SB), and (4) Clearfil SE Bond primed-dentine was infiltrated with Clearfil SE bonding resin (CSE). Microtensile bond strength (MTBS) was assessed for the different groups at 24h and after 3months. Debonded dentine surfaces were studied by scanning electron microscopy.

RESULTS

MMPs-mediated collagen degradation occurred in demineralized dentine (PA). Resin infiltration decreased collagen degradation. The lowest collagen degradation was found for Zn-doped SB, followed by CSE. When these adhesives were applied, ICTP values did not change throughout the study period. At 24h, similar MTBS was attained for all adhesives. Only SB decreased MTBS after three months.

CONCLUSIONS

Addition of ZnO particles to SB produced a reduction in dentine collagen degradation and increased resin-dentine bonds durability. In Zn-doped adhesive interfaces, a calcium phosphate layer and tubular occlusion was encountered at the debonded interface.

CLINICAL SIGNIFICANCE

ZnO particles addition into the bonding resin of SB makes a breakthrough to prevent the hybrid layer degradation and to preserve its bonding efficacy overtime.

Effect of dentin etching and chlorhexidine application on metalloproteinase-mediated collagen degradation

Dentin matrix metalloproteinases (MMPs) are involved in the degradation of collagen in resin-dentin interfaces. This study evaluated whether collagen degradation can be prevented by chlorhexidine digluconate (CHX) after different dentin demineralization procedures. The demineralization of human dentin was performed with phosphoric acid (PA), EDTA or acidic monomers (Clearfil SE Bond and Xeno V). Specimens were stored (for 24 h, or for 1 or 3 wk) in the presence or absence of CHX. In half of the groups, active MMP-2 was incorporated into the storage solution. At the end of each storage period, the C-terminal telopeptide (ICTP) concentration (which indicates the amount of collagen degradation) was measured in the storage solution. Collagen degradation was higher in PA- and EDTA-demineralized dentin. Chlorhexidine digluconate reduced collagen degradation in these groups only for 24 h. When dentin was demineralized with Clearfil SE Bond or Xeno V, collagen degradation was reduced by up to 30%, but the addition of exogenous MMP-2 significantly increased collagen degradation. In self-etchant-treated dentin, the inhibitory effect of CHX on MMPs lasted for up to 3 wk. Treating dentin with EDTA, PA or self-etching agents produces enough demineralization to permit cleavage of the exposed collagen. Monomer infiltration may exert protection on demineralized collagen, probably through immobilization of MMPs. The partial inhibitory action of CHX on MMP activity produced by self-etching adhesives was prolonged compared with the short-acting PA- or EDTA-treated dentin.

MMP levels in the response to degradable implants in the presence of a hydroxamate-based matrix metalloproteinase sequestering biomaterial in vivo

The inflammatory response to an implanted tissue engineered construct alters the remodeling that occurs and this can diminish the intended therapeutic effect. It was hypothesized that the use of a hydroxamate-based matrix metalloproteinase (MMP) sequestering biomaterial (MI) in the form of approximately 200 microm microspheres would lower the amount and activity of MMP in vivo in response to a subcutaneous, degradable implant (gelatin or Integra disc). MMP degrade extracellular matrix, facilitating inflammatory cell migration and local remodeling of the implant environment. Gelatin or Integra discs were implanted subcutaneously in the backs of CD1 mice together with 30 mg of MI microspheres or with 30 mg of similarly sized control poly(methyl methacrylate) (PMMA) microspheres in a paired study. To sample the implant space, weakly adsorbed protein or attached cells were recovered from explanted discs by soaking the discs in PBS overnight at 4 degrees C. Unexpectedly, MMP-2, -8, -9, and TIMP-1 levels were surprisingly similar in this recovered fluid for the two treatments. Also, there were significantly more (and at day 4 an order of magnitude more) leukocytes recovered from the gelatin discs coimplanted with the MI microspheres than with the PMMA control. It is suggested that the MI microspheres disturbed the natural MMP control pathway leading to high-leukocyte numbers, especially at early times. These results highlight the challenge associated with controlling the fate of tissue engineered constructs in vivo.

An update on pharmacological interventions for diabetic foot ulcers

Diabetic foot ulcers are the most common lower extremity complications of diabetes. Peripheral neuropathy and peripheral vascular disease are the underlying risk factors for diabetic foot ulcers, subsequently leading to infections and requiring antimicrobial therapy for the management of the disease. Each risk factor is a target for clinical intervention, with the intent to delay or prevent disease progression to amputation. The effective therapy includes interdisciplinary care, which involves optimized pharmacological interventions in concert with other treatments such as debridement strategies and specialized wound dressings. The pharmacological therapy alone cannot lead to successful therapy, and therefore, these supplementary techniques/modalities should not be overlooked. It is therefore the aim of this report to review various pharmacological interventions, specific to the diabetic foot and wound healing, along with incorporation of advanced therapies required to achieve a multifaceted treatment of diabetic foot ulcers and provide basis for superior drugs as well as drug delivery systems.

Effect of a matrix metalloproteinase sequestering biomaterial on Caco-2 epithelial cell barrier integrity in vitro

A novel matrix metalloproteinase sequestering biomaterial (MI Theramer beads) restored the epithelial barrier in a double chamber in vitro test system after disruption by Cytochalasin D and the secretion of the metalloproteinase MMP-2. MI beads are chemically modified (hydroxamated) poly(methacrylic acid-co-methyl methacrylate). We are exploring the utility of this material in inflammatory bowel disease (IBD), in which one manifestation is a compromised intestinal epithelial barrier. In a first step towards this goal we incubated MI beads (or polymethyl methacrylate control beads) with Caco-2 epithelial cells and mesenchymal 3T3 fibroblasts on two sides of a Matrigel((R))-coated filter and used Cytochalasin D (Cyto D) to activate MMP-2 (secreted by the 3T3 cells), disrupt actin filaments of Caco-2 cells and render the epithelial barrier leaky, as measured by dextran fluorescein equilibration. Addition of MI beads to Cyto D-treated cells inhibited active MMP-2 and prevented equilibration of dextran fluorescein. This study is the first step in showing a potential benefit to local (as opposed to systemic) inhibition of metalloproteinases in IBD or other intestinal inflammatory diseases.