Therapeutic Hydrogel Patch to Treat Atopic Dermatitis by Regulating Oxidative Stress

Visible light accelerates skin wound healing and alleviates scar formation in mice by adjusting STAT3 signaling

During the wound healing process, the activation of signal transducer and activator of transcription 3 (STAT3) is considered crucial for the migration and proliferation of epithelial cells, as well as for establishing the inflammatory environment. However, an excessive STAT3 activation aggravates scar formation. Here we show that 450 nm blue light and 630 nm red light can differentially regulate the phosphorylation of STAT3 (p-STAT3) and its downstream cytokines in keratinocytes. Further mechanistic studies reveal that red light promotes wound healing by activating the PI3 kinase p110 beta (PI3Kβ)/STAT3 signaling axis, while blue light inhibits p-STAT3 at the wound site by modulating cytochrome c-P450 (CYT-P450) activity and reactive oxygen species (ROS) generation. In a mouse scar model, skin wound healing can be significantly accelerated with red light followed by blue light to reduce scar formation. In summary, our study presents a potential strategy for regulating epithelial cell p-STAT3 through visible light to address skin scarring issues and elucidates the underlying mechanisms.

Computational recognition of regulator genes and signature for ferroptosis with implications on immunological properties and clinical management of atopic dermatitis

Background

Atopic dermatitis (AD) is a common chronic dermatitis of autoimmune origin that considerably affects the quality of life of patients. Ferroptosis, a newly regulated form of cell death, is essential for inflammation-related damage-associated molecular patterns (DAMPs). In this study, we aimed to identify ferroptosis regulators relevant to AD pathogenesis and reveal the mechanisms by which ferroptosis regulates the pathogenesis of AD.

Methods

We analyzed the GEO AD cohorts (GSE16161, GSE32924, GSE107361, and GSE120721), identifying AD-related differentially expressed genes (DEGs) using edgeR. Co-expression and STRING database analyses were used to elucidate the interactions between DEGs and ferroptosis markers. Through functional enrichment analysis, we defined potential biological functions within the protein-protein interaction (PPI) network and developed FerrSig using LASSO regression. The utility of FerrSig in guiding the clinical management of AD was evaluated using the GSE32473 cohort. Subsequently, our in silico findings were confirmed, and mechanistic insights were expanded through both in vitro and in vivo studies, validating the relevance of FerrSig.

Results

In the GEO AD cohort, 278 DEGs were identified, including seven ferroptosis signature genes. Co-expression analysis and STRING database review revealed a 63-node PPI network linked to cell cycle and pro-inflammatory pathways. Four ferroptosis genes (ALOXE3, FABP4, MAP3K14, and EGR1) were selected to create FerrSig, which was significantly downregulated in samples collected from patients with AD. In addition, immune-related signaling pathways were significantly differentially enriched between the stratifications of samples collected from patients with AD with high and low ferritin levels, whereas in the GSE32473 cohort, FerrSig was significantly increased in cohorts effectively treated with pimecrolimus or betamethasone. Finally, in vitro and in vivo models showed a notable FerrSig decrease in patients with AD versus healthy control. Treatment with betamethasone and tacrolimus restored FerrSig, and the magnitude of the increase in FerrSig was higher in samples collected from patients with AD with better efficacy assessments. In addition, FerrSig was significantly positively correlated with the ferroptosis inhibitors GPX4 and SLC7A11 and negatively correlated with reactive oxygen species (ROS) levels and p-STAT3/STAT3. This implies that the FerrSig signature genes may regulate ferroptosis through the JAK/STAT3 signaling pathway.

Conclusion

Our study further explored the pathogenesis of AD, and FerrSig could serve as a potential biomarker for identifying AD morbidity risks and determining treatment efficacy.

Multifunctional nanogel loaded with cerium oxide nanozyme and CX3CL1 protein: Targeted immunomodulation and retinal protection in uveitis rat model

Effectively addressing retinal issues represents a pivotal aspect of blindness-related diseases. Novel approaches involving reducing inflammation and rebalancing the immune response are paramount in the treatment of these conditions. This study delves into the potential of a nanogel system comprising polyethylenimine-benzene boric acid-hyaluronic acid (PEI-PBA-HA). We have evaluated the collaborative impact of cerium oxide nanozyme and chemokine CX3CL1 protein for targeted immunomodulation and retinal protection in uveitis models. Our nanogel system specifically targets the posterior segment of the eyes. The synergistic effect in this area reduces oxidative stress and hampers the activation of microglia, thereby alleviating the pathological immune microenvironment. This multifaceted drug delivery system disrupts the cycle of oxidative stress, inflammation, and immune response, suppressing initial immune cells and limiting local retinal structural damage induced by excessive immune reactions. Our research sheds light on interactions within retinal target cells, providing a promising avenue for the development of efficient and innovative drug delivery platforms.

Reactive oxide species and ultrasound dual-responsive bilayer microneedle array for in-situ sequential therapy of acute myocardial infarction

Acute myocardial infarction (AMI) resulting from coronary artery occlusion stands as the predominant cause of cardiovascular disability and mortality worldwide. An all-encompassing treatment strategy targeting pathological processes of oxidative stress, inflammation, proliferation and fibrotic remodeling post-AMI is anticipated to enhance therapeutic outcomes. Herein, an up-down-structured bilayer microneedle (Ce-CLMs-BMN) with reactive oxygen species (ROS) and ultrasound (US) dual-responsiveness is proposed for AMI in-situ sequential therapy. The upper-layer microneedle is formulated by crosslinking ROS-sensitive linker with polyvinyl alcohol loaded with cerium dioxide nanoparticles (CeNPs) featuring versatile enzyme-mimetic activities. During AMI acute phase, prompted by ischemia-induced microenvironmental redox imbalance, this layer swiftly releases CeNPs, which aid in eliminating excessive ROS and catalyzing oxygen gas (O2) production through multiple enzymatic pathways, thereby alleviating oxidative stress-induced damage and modulating inflammation. In AMI chronic repair phase, micro-nano reactors (CLMs) situated in the lower-layer microneedle undergo cascade reactions with the assistance of US irradiation to generate nitric oxide (NO). As a bioactive molecule with pro-angiogenic and anti-fibrotic effects, NO expedites cardiac repair while attenuating adverse remodeling. Additionally, its antiplatelet-aggregating properties contribute to thromboprophylaxis. In-vitro and in-vivo results substantiate the efficacy of this integrated healing approach in AMI management, showcasing promising prospects for advancing infarcted heart repair.

Hydrogels: a promising therapeutic platform for inflammatory skin diseases treatment

Inflammatory skin diseases, such as psoriasis and atopic dermatitis, pose significant health challenges due to their long-lasting nature, potential for serious complications, and significant health risks, which requires treatments that are both effective and exhibit minimal side effects. Hydrogels offer an innovative solution due to their biocompatibility, tunability, controlled drug delivery capabilities, enhanced treatment adherence and minimized side effects risk. This review explores the mechanisms that guide the design of hydrogel therapeutic platforms from multiple perspectives, focusing on the components of hydrogels, their adjustable physical and chemical properties, and their interactions with cells and drugs to underscore their clinical potential. We also examine various therapeutic agents for psoriasis and atopic dermatitis that can be integrated into hydrogels, including traditional drugs, novel compounds targeting oxidative stress, small molecule drugs, biologics, and emerging therapies, offering insights into their mechanisms and advantages. Additionally, we review clinical trial data to evaluate the effectiveness and safety of hydrogel-based treatments in managing psoriasis and atopic dermatitis under complex disease conditions. Lastly, we discuss the current challenges and future opportunities for hydrogel therapeutics in treating psoriasis and atopic dermatitis, such as improving skin barrier penetration and developing multifunctional hydrogels, and highlight emerging opportunities to enhance long-term safety and stability.

Matrine-loaded self-adhesive swelling microneedle for inflammation regulation to improve eczema treatment

Eczema is a common chronic dermatological disease. Conventional treatments exhibit limited efficacy due to fast drug release resulting in short-term relief. Development of a new treatment strategy that enables sustained drug release and long-term maintenance on the skin surface is necessary. A self-adhesive swelling microneedle patch (SDSMNs) was designed and constructed using a two-step casting method. The adhesive substrate was prepared by blending gelatin and dopamine via oxidation of NaIO4, so it could adhere onto the skin surface as well as withstand repeated bending movement without detachment. The swelling needles were fabricated using polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP), which could swell by absorbing interstitial fluid and release the drug in a controlled manner. SDSMNs also showed desirable antibacterial activities toward E. coli and S. aureus. The adhesive microneedles loaded with matrine (MAT-SDSMNs), an anti-inflammatory Chinese medicine, dramatically relieved eczema symptoms through IL-17 mediated inflammation responses. The use of MAT-SDSMNs significantly decreased the infiltration of inflammation cells and level of inflammatory cytokines, reduced the skin thickness, and increased collagen deposition fraction compared with conventional ointment or subcutaneous injection. The results suggested that MAT-SDSMNs can improve eczema treatment by regulating the local inflammatory microenvironment, providing a simple, self-administered sustainable strategy for eczema treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-024-00235-z.

Causal relationships between dietary antioxidant vitamin intake and atopic dermatitis: A two-sample Mendelian randomization study

OBJECTIVE

Oxidative stress is strongly associated with atopic dermatitis (AD), and increased antioxidant intake could potentially reduce the risk of or alleviate its symptoms. However, the argument is disputed. Therefore, we conducted a Mendelian randomization (MR) analysis to explore the causal relationship between dietary antioxidant vitamin intake and AD.

METHODS

We applied MR analysis to examine the causative association between dietary antioxidant vitamin intake (vitamin C, vitamin E, carotene, and retinol) and AD. The genome-wide association study (GWAS) summary data for antioxidant vitamins intake and AD were obtained from the IEU OpenGWAS database and the UK biobank. Our study consisted of two major parts, MR analysis to detect the causal relationship between exposure and outcome, and sensitivity analysis as supplemental evidence to verify the robustness of the results.

RESULT

The results revealed a suggestive causal relationship between vitamin E intake and AD (p = 0.038, OR 95% CI = 0.745-0.992). However, there was no causal relationship between the other three vitamins (vitamin C, carotene, and retinol) and AD (p = 0.507, OR 95% CI = 0.826-1.099) (p = 0.890, OR 95% CI = 0.864-1.184) (p = 0.492, OR 95% CI = 0.893-1.264). None of the single nucleotide polymorphisms (SNPs) were detected as heterogeneous and pleiotropy in the sensitivity analysis (p > 0.05).

CONCLUSION

The analysis suggested that dietary intake of vitamin E may potentially lower the risk of AD. Conversely, intake of vitamin C, retinol, and carotene is not causally related to AD. Although vitamin E intake could be protective against AD, intake of dietary antioxidant vitamins to prevent or treat AD is not necessary.

Hydrogel-Based Treatment of House Dust Mite-Induced Atopic Dermatitis through Triple Cleaning of Mites, Bacteria, and ROS-Related Inflammation

Atopic dermatitis (AD) is a chronic and recurrent inflammatory disease caused by abnormalities in skin immunoregulation. House dust mite can directly damage the skin barrier and thus sensitize the skin, which is one of the main allergens inducing AD in humans and widely exists in daily life. Meanwhile, the accompanying bacterial infections and exposure to additional allergens exacerbate the condition by generating excessive reactive oxygen species (ROS). Herein, we have developed the CPDP hydrogel with injectable and self-healing ability to combat pathogenic microorganisms and inflammatory environments for AD therapy. In vitro experiments have affirmed the efficacy of the CPDP hydrogel in combating mites, killing bacteria, and scavenging ROS. In a mouse model closely mimicking HDM-induced AD, the CPDP hydrogel has shown superior therapeutic effects, including reducing epidermal thickness and mast cell count, increasing collagen deposition, as well as down-regulating pro-inflammatory factors.

Lignin-Based Antioxidant Hydrogel Patch for the Management of Atopic Dermatitis by Mitigating Oxidative Stress in the Skin

Atopic dermatitis (AD), a chronic skin condition characterized by itching, redness, and inflammation, is closely associated with heightened levels of endogenous reactive oxygen species (ROS) in the skin. ROS can contribute to the onset and progression of AD through oxidative stress, which leads to the release of proinflammatory cytokines, T-cell differentiation, and the exacerbation of skin symptoms. In this study, we aim to develop a therapeutic antioxidant hydrogel patch for the potential treatment of AD using lignin, a biomass waste material. Lignin contains polyphenol groups that enable it to scavenge ROS and exhibit antioxidant properties. The lignin hydrogel patches, possessing optimized mechanical properties through the control of the lignin and cross-linker ratio, demonstrated high ROS-scavenging capabilities. Furthermore, the lignin hydrogel demonstrated excellent biocompatibility with the skin, exhibiting beneficial properties in protecting human keratinocytes under high oxidative conditions. When applied to an AD mouse model, the hydrogel patch effectively reduced epidermal thickness in inflamed regions, decreased mast cell infiltration, and regulated inflammatory cytokine levels. These findings collectively suggest that lignin serves as a therapeutic hydrogel patch for managing AD by modulating oxidative stress through its ROS-scavenging ability.

Low drug load, high retention mometasone furoate cream with polyglyceryl - 3 oleate as a chemical enhancer: Formulation development, in vivo and in vitro evaluation and molecular mechanisms

The study aimed to create a low loading, high retention, easier to apply O/W mometasone furoate (MF) cream using a chemical enhancer (CE) approach to provide more options for patients with atopic dermatitis (AD) and to investigate molecular mechanisms of its increased release and retention. A Box-Behnken design determined the optimal formulation based on stability and in vitro skin retention. Evaluations included appearance, rheological properties, irritation, in vivo tissue distribution and pharmacodynamics. Molecular mechanisms of enhanced release were studied using high-speed centrifugation, molecular dynamics and rheology. The interaction between the CE, MF and skin was studied by tape stripping, CLSM, ATR-FTIR and SAXS. The formulation was optimized to contain 0.05% MF and used 10% polyglyceryl-3 oleate (POCC) as the CE. There was no significant difference from Elocon® cream in in vivo retention and pharmacodynamics but increased in vivo retention by 3.14-fold and in vitro release by 1.77-fold compared to the basic formulation. POCC reduced oil phase cohesive energy density, enhancing drug mobility and release. It disrupted skin lipid phases, aiding drug entry and formed hydrogen bonds, prolonging retention. This study highlights POCC as a CE in the cream, offering insights for semi-solid formulation development.

Enhancing diabetic wound healing with a pH/glucose dual-responsive hydrogel for ROS clearance and antibacterial activity

Currently, the treatment of diabetic wounds in clinical practice is still unsatisfactory due to the risks of oxidative damage and bacterial infection during the healing process. An optimal wound dressing should exhibit robust capabilities in scavenging reactive oxygen species (ROS) and combatting bacterial growth. In this study, we utilized borax as a crosslinker and prepared a pH/glucose dual-responsive composite hydrogel based on poly(vinyl alcohol) (PVA), sodium alginate (SA), and tannic acid (TA). This hydrogel, loaded with cerium dioxide, serves as an effective ROS scavenger, promoting wound closure by reducing the level of ROS in the wound area. Additionally, the hydrogel can release the antibacterial drug ofloxacin in response to the low pH and high glucose microenvironment in infected wounds. Results from skin defect model in diabetic mice demonstrated this ROS-scavenging and antibacterial hydrogel can suppress inflammation and accelerate wound healing. In summary, our work provides a new perspective on a local and stimulus-responsive drug delivery strategy for treating diabetic wounds.

Janus Nanofibrous Patch with In Situ Grown Superlubricated Skin for Soft Tissue Repair with Inhibited Postoperative Adhesion

The patch with a superlubricated surface shows great potential for the prevention of postoperative adhesion during soft tissue repair. However, the existing patches suffer from the destruction of topography during superlubrication coating and lack of pro-healing capability. Herein, we demonstrate a facile and versatile strategy to develop a Janus nanofibrous patch (J-NFP) with antiadhesion and reactive oxygen species (ROS) scavenging functions. Specifically, sequential electrospinning is performed with initiators and CeO2 nanoparticles (CeNPs) embedded on the different sides, followed by subsurface-initiated atom transfer radical polymerization for grafting zwitterionic polymer brushes, introducing superlubricated skin on the surface of single nanofibers. The poly(sulfobetaine methacrylate) brush-grafted patch retains fibrous topography and shows a coefficient of friction of around 0.12, which is reduced by 77% compared with the pristine fibrous patch. Additionally, a significant reduction in protein, platelet, bacteria, and cell adhesion is observed. More importantly, the CeNPs-embedded patch enables ROS scavenging as well as inhibits pro-inflammatory cytokine secretion and promotes anti-inflammatory cytokine levels. Furthermore, the J-NFP can inhibit tissue adhesion and promote repair of both rat skin wounds and intrauterine injuries. The present strategy for developing the Janus patch exhibits enormous prospects for facilitating soft tissue repair.

Superoxide Dismutase-Mimetic Polyphenol-Based Carbon Dots for Multimodal Bioimaging and Treatment of Atopic Dermatitis

Polyphenols have been investigated for their potential to mitigate inflammation in the context of atopic dermatitis (AD). In this study, epigallocatechin-3-gallate (EGCG)-based carbon dots (EGCG@CDs) were developed to enhance transdermal penetration, reduce inflammation, recapitulate superoxide dismutase (SOD) activity, and provide antimicrobial effects for AD treatment. The water-soluble EGCG@CDs in a few nanometers size exhibit a negative zeta potential, making them suitable for effective transdermal penetration. The fluorescence properties, including an upconversion effect, make EGCG@CDs suitable imaging probes for both in vitro and in vivo applications. By mimicking the SOD enzyme, EGCG@CDs scavenge reactive oxygen species (ROS) and actively produce hydrogen peroxide through a highly catalytic capability toward the oxygen reduction reaction, resulting in the inhibition of bacterial growth. The enhanced antioxidant properties, high charge mobility, and various functional groups of EGCG@CDs prove effective in reducing intracellular ROS in an in vitro AD model. In the mouse AD model, EGCG@CDs incorporated into a hydrogel actively penetrated the epidermal layer, leading to ROS scavenging, reduced mast cell activation, and histological recovery of skin barriers. This research represents the versatile potential of EGCG@CDs in addressing AD and advancing tissue engineering.

A whole-course-repair system based on ROS/glucose stimuli-responsive EGCG release and tunable mechanical property for efficient treatment of chronic periodontitis in diabetic rats

Elevated glucose levels, multiple pro-inflammatory cytokines and the generation of excessive reactive oxygen species (ROS) are pivotal characteristics within the microenvironments of chronic periodontitis with diabetes mellitus (CPDM). Control of inflammation and modulation of immune system are required in the initial phase of CPDM treatment, while late severe periodontitis requires a suitable scaffold to promote osteogenesis, rebuild periodontal tissue and reduce alveolar bone resorption. Herein, a whole-course-repair system is introduced by an injectable hydrogel using phenylboronic acid functionalized oxidized sodium alginate (OSA-PBA) and carboxymethyl chitosan (CMC). Epigallocatechin-3-gallate (EGCG) was loaded to simultaneously adjust the mechanical property of the OSA-PBA/CMC + EGCG hydrogel (OPCE). This hydrogel has distinctive adaptability, injectability, and ROS/glucose-triggered release of EGCG, making it an ideal drug delivery carrier. As expected, OPCE hydrogel shows favourable antioxidant and anti-inflammatory properties, along with a regulatory influence on the phenotypic transition of macrophages, providing a favourable immune microenvironment. Apart from that, it provides a favourable mechanical support for osteoblast/osteoclast differentiation regulation at the late proliferation stage of periodontal regeneration. The practical therapeutic effects of OPCE hydrogels were also confirmed when applied for treating periodontitis in diabetic rats. In summary, OPCE hydrogel may be a promising whole-course-repair system for the treatment of CPDM.

Mated-Atom Nanozymes with Efficient Assisted NAD+ Replenishment for Skin Regeneration

Excessive accumulation of reduced nicotinamide adenine dinucleotide (NADH) within biological organisms is closely associated with many diseases. It remains a challenge to efficiently convert superfluous and detrimental NADH to NAD+. NADH oxidase (NOX) is a crucial oxidoreductase that catalyzes the oxidation of NADH to NAD+. Herein, M1M2 (Mi=V/Mn/Fe/Co/Cu/Mo/Rh/Ru/Pd, i = 1 or 2) mated-atom nanozymes (MANs) are designed by mimicking natural enzymes with polymetallic active centers. Excitingly, RhCo MAN possesses excellent and sustainable NOX-like activity, with Km-NADH (16.11 μM) being lower than that of NOX-mimics reported so far. Thus, RhCo MAN can significantly promote the regeneration of NAD+ and regulate macrophage polarization toward the M2 phenotype through down-regulation of TLR4 expression, which may help to recover skin regeneration. However, RhRu MAN with peroxidase-like activity and RhMn MAN with superoxide dismutase-like activity exhibit little modulating effects on eczema. This work provides a new strategy to inhibit skin inflammation and promote skin regeneration.

Developing hydrogels for gene therapy and tissue engineering

Hydrogels are a class of highly absorbent and easily modified polymer materials suitable for use as slow-release carriers for drugs. Gene therapy is highly specific and can overcome the limitations of traditional tissue engineering techniques and has significant advantages in tissue repair. However, therapeutic genes are often affected by cellular barriers and enzyme sensitivity, and carrier loading of therapeutic genes is essential. Therapeutic gene hydrogels can well overcome these difficulties. Moreover, gene-therapeutic hydrogels have made considerable progress. This review summarizes the recent research on carrier gene hydrogels for the treatment of tissue damage through a summary of the most current research frontiers. We initially introduce the classification of hydrogels and their cross-linking methods, followed by a detailed overview of the types and modifications of therapeutic genes, a detailed discussion on the loading of therapeutic genes in hydrogels and their characterization features, a summary of the design of hydrogels for therapeutic gene release, and an overview of their applications in tissue engineering. Finally, we provide comments and look forward to the shortcomings and future directions of hydrogels for gene therapy. We hope that this article will provide researchers in related fields with more comprehensive and systematic strategies for tissue engineering repair and further promote the development of the field of hydrogels for gene therapy.

Mitochondrial-targeting and NIR-responsive Mn3O4@PDA@Pd-SS31 nanozymes reduce oxidative stress and reverse mitochondrial dysfunction to alleviate osteoarthritis

Mitochondrial reactive oxygen species (mROS) play a crucial role in the process of osteoarthritis (OA), which may be a promising target for therapy of OA. In this study, novel mitochondrial-targeting and SOD-mimic Mn3O4@PDA@Pd-SS31 nanozymes with near-infrared (NIR) responsiveness and synergistic cascade to scavenge mROS were designed for the therapy of OA. Results showed that the nanozymes accelerated the release of Pd and Mn3O4 under NIR irradiation, exhibiting enhanced activities of SOD and CAT mimic enzymes with reversed mitochondrial dysfunction and promoted mitophagy to effectively scavenge mROS from chondrocytes, modulate the microenvironment of oxidative stress, and eventually inhibit the inflammatory response. Nanozymes were excreted in vivo through intestinal metabolic pathway and had good biocompatibility, effectively reducing the inflammatory response and relieving articular cartilage degeneration in OA joints, with a reduction of 93.7 % and 93.8 % in OARSCI scores for 4 and 8 weeks respectively. Thus, this study demonstrated that the mitochondria targeting and NIR responsive Mn3O4@PDA@Pd-SS31 nanozymes could efficiently scavenge mROS, repair damaged mitochondrial function and promote cartilage regeneration, which are promising for the treatment of OA in clinical applications.

Ceria-Based Therapeutic Antioxidants for Biomedical Applications

The growing interest in nanomedicine over the last 20 years has carved out a research field called "nanocatalytic therapy," where catalytic reactions mediated by nanomaterials are employed to intervene in disease-critical biomolecular processes. Among many kinds of catalytic/enzyme-mimetic nanomaterials investigated thus far, ceria nanoparticles stand out from others owing to their unique scavenging properties against biologically noxious free radicals, including reactive oxygen species (ROS) and reactive nitrogen species (RNS), by exerting enzyme mimicry and nonenzymatic activities. Much effort has been made to utilize ceria nanoparticles as self-regenerating antioxidative and anti-inflammatory agents for various kinds of diseases, given the detrimental effects of ROS and RNS therein that need alleviation. In this context, this review is intended to provide an overview as to what makes ceria nanoparticles merit attention in disease therapy. The introductory part describes the characteristics of ceria nanoparticles as an oxygen-deficient metal oxide. The pathophysiological roles of ROS and RNS are then presented, as well as their scavenging mechanisms by ceria nanoparticles. Representative examples of recent ceria-nanoparticle-based therapeutics are summarized by categorization into organ and disease types, followed by the discussion on the remaining challenges and future research directions.

Antimicrobial research of carbohydrate polymer- and protein-based hydrogels as reservoirs for the generation of reactive oxygen species: A review

Reactive oxygen species (ROS) play an important role in biological milieu. Recently, the rapid growth in our understanding of ROS and their promise in antibacterial applications has generated tremendous interest in the combination of ROS generators with bulk hydrogels. Hydrogels represent promising supporters for ROS generators and can locally confine the nanoscale distribution of ROS generators whilst also promoting cellular integration via biomaterial-cell interactions. This review highlights recent efforts and progress in developing hydrogels derived from biological macromolecules with embedded ROS generators with a focus on antimicrobial applications. Initially, an overview of passive and active antibacterial hydrogels is provided to show the significance of proper hydrogel selection and design. These are followed by an in-depth discussion of the various approaches for ROS generation in hydrogels. The structural engineering and fabrication of ROS-laden hydrogels are given with a focus on their biomedical applications in therapeutics and diagnosis. Additionally, we discuss how a compromise needs to be sought between ROS generation and removal for maximizing the efficacy of therapeutic treatment. Finally, the current challenges and potential routes toward commercialization in this rapidly evolving field are discussed, focusing on the potential translation of laboratory research outcomes to real-world clinical outcomes.

Nanozyme-Engineered Hydrogels for Anti-Inflammation and Skin Regeneration

Inflammatory skin disorders can cause chronic scarring and functional impairments, posing a significant burden on patients and the healthcare system. Conventional therapies, such as corticosteroids and nonsteroidal anti-inflammatory drugs, are limited in efficacy and associated with adverse effects. Recently, nanozyme (NZ)-based hydrogels have shown great promise in addressing these challenges. NZ-based hydrogels possess unique therapeutic abilities by combining the therapeutic benefits of redox nanomaterials with enzymatic activity and the water-retaining capacity of hydrogels. The multifaceted therapeutic effects of these hydrogels include scavenging reactive oxygen species and other inflammatory mediators modulating immune responses toward a pro-regenerative environment and enhancing regenerative potential by triggering cell migration and differentiation. This review highlights the current state of the art in NZ-engineered hydrogels (NZ@hydrogels) for anti-inflammatory and skin regeneration applications. It also discusses the underlying chemo-mechano-biological mechanisms behind their effectiveness. Additionally, the challenges and future directions in this ground, particularly their clinical translation, are addressed. The insights provided in this review can aid in the design and engineering of novel NZ-based hydrogels, offering new possibilities for targeted and personalized skin-care therapies.

Erigeron annuus Extract Improves DNCB-Induced Atopic Dermatitis in a Mouse Model via the Nrf2/HO-1 Pathway

Atopic dermatitis (AD) is a persistent inflammatory skin condition resulting from an intricate interplay among genetic, immunological, and environmental factors. Erigeron annuus (EA), an annual winter plant belonging to the family Asteraceae, possesses anti-inflammatory, cytoprotective, and antioxidant activities. In this study, we hypothesized that Erigeron annuus extract (EAE) could be an effective agent for ameliorating AD-like symptoms. To confirm this hypothesis in vitro, we used H2O2-stimulated human keratinocytes (HaCaT cells) to demonstrate that pre-treatment with EAE protected against oxidative stress. HaCaT cells pretreated with EAE and stimulated with H2O2 showed decreased intracellular malondialdehyde content, increased superoxide dismutase activity, and reduced intracellular reactive oxygen species accumulation. To verify the in vivo hypothesis based on the intracellular results, an AD disease mouse model was induced with 1-chloro-2,4-dinitrobenzene (DNCB), and EAE was orally administered at a non-toxic concentration according to the toxicity evaluation results. The results showed that AD disease models in BALB/c mice exhibited reduced ear epidermal thickness, scratching behavior, and mast cell infiltration. In conclusion, our results indicate that EAE has the potential to improve AD by upregulating the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway.

Hyaluronic Acid-Based Reactive Oxygen Species-Responsive Multifunctional Injectable Hydrogel Platform Accelerating Diabetic Wound Healing

Diabetic wounds are more likely to develop into complex and severe chronic wounds. The objective of this study is to develop and assess a reactive oxygen species (ROS)-responsive multifunctional injectable hydrogel for the purpose of diabetic wound healing. A multifunctional hydrogel (HA@Cur@Ag) is successfully synthesized with dual antioxidant, antibacterial, and anti-inflammatory properties by crosslinking thiol hyaluronic acid (SH-HA) and disulfide-bonded hyperbranched polyethylene glycol (HB-PBHE) through Michael addition; while, incorporating curcumin liposomes and silver nanoparticles (AgNPs). The HA@Cur@Ag hydrogel exhibits favorable biocompatibility, degradability, and injectivity. The outcomes of in vitro and in vivo experiments demonstrate that the hydrogel can effectively be loaded with and release curcumin liposomes, as well as silver ions, thereby facilitating diabetic wound healing through multiple mechanisms, including ROS scavenging, bactericidal activity, anti-inflammatory effects, and the promotion of angiogenesis. Transcriptome sequencing reveals that the HA@Cur@Ag hydrogel effectively suppresses the activation of the tumour necrosis factor (TNF)/nuclear factor κB (NF-κB) pathway to ameliorate oxidative stress and inflammation in diabetic wounds. These findings suggest that this ROS-responsive multifunctional injectable hydrogel, which possesses the ability to precisely coordinate and integrate intricate biological and molecular processes involved in wound healing, exhibits notable potential for expediting diabetic wound healing.

Stimulus-Responsive Hydrogels as Drug Delivery Systems for Inflammation Targeted Therapy

Deregulated inflammations induced by various factors are one of the most common diseases in people's daily life, while severe inflammation can even lead to death. Thus, the efficient treatment of inflammation has always been the hot topic in the research of medicine. In the past decades, as a potential biomaterial, stimuli-responsive hydrogels have been a focus of attention for the inflammation treatment due to their excellent biocompatibility and design flexibility. Recently, thanks to the rapid development of nanotechnology and material science, more and more efforts have been made to develop safer, more personal and more effective hydrogels for the therapy of some frequent but tough inflammations such as sepsis, rheumatoid arthritis, osteoarthritis, periodontitis, and ulcerative colitis. Herein, from recent studies and articles, the conventional and emerging hydrogels in the delivery of anti-inflammatory drugs and the therapy for various inflammations are summarized. And their prospects of clinical translation and future development are also discussed in further detail.

Orally Administrated Inflamed Colon-Targeted Nanotherapeutics for Inflammatory Bowel Disease Treatment by Oxidative Stress Level Modulation in Colitis

Inflammatory bowel disease (IBD) is characterized by an inappropriate and persistent inflammatory immune response and is often accompanied by excessive reactive oxygen species (ROS) production. For effective IBD treatment, there is a high demand for safe and targeted therapy that can be orally administered. In this study, we aimed to propose the use of inflamed colon-targeted antioxidant nanotherapeutics (ICANs) for in situ oxidative stress level modulation in colitis. ICANs consist of mesoporous silica nanoparticles (MSNs) with surface-attached ROS-scavenging ceria nanoparticles (CeNPs), which are further coated with poly(acrylic acid) (PAA) to facilitate preferential adherence to inflamed colon tissues through electrostatic interaction. We achieved a high ROS-scavenging property that remained effective even after artificial gastrointestinal fluid incubation by optimization of the molecular weight and PAA-coating pH. The orally administered ICANs demonstrated enhanced adherence to inflamed colon tissues in an acute inflammation mouse model of IBD induced by dextran sulfate sodium. This targeted delivery resulted in gut microenvironment modulation by regulating redox balance and reducing inflammatory cell infiltration, thereby suppressing the colitis-associated immune response. These findings highlight the potential of noninvasive ICANs as a promising candidate for treating inflammatory intestinal diseases by oxidative stress level modulation in colitis.

Hollow manganese dioxide-chitosan hydrogel for the treatment of atopic dermatitis through inflammation-suppression and ROS scavenging

Atopic dermatitis (AD) is a chronic inflammatory disease associated with immune dysfunction. High levels of reactive oxygen species (ROS) can lead to oxidative stress, release of pro-inflammatory cytokines, and T-cell differentiation, thereby promoting the onset and worsening of AD. In this study, we innovatively used quaternary ammonium chitosan (QCS) and tannic acid (TA) as raw materials to design and prepare a therapeutic hydrogel(H-MnO2-Gel) loaded with hollow manganese dioxide nanoparticles (H-MnO2 NPs). In this system, the hydrogel is mainly cross-linked by dynamic ion and hydrogen bonding between QCS and TA, resulting in excellent moisture retention properties. Moreover, due to the inherent antioxidant properties of QCS/TA, as well as the outstanding H2O2 scavenging ability of H-MnO2 NPs, the hydrogel exhibits significant ROS scavenging capability. In vitro experiments have shown that H-MnO2-Gel exhibits good cellular biocompatibility. Importantly, in an AD-induced mouse model, H-MnO2-Gel significantly enhanced therapeutic effects by reducing epidermal thickness, mast cell number, and IgE antibodies. These findings suggest that H-MnO2-Gel, by effectively clearing ROS and regulating the inflammatory microenvironment, provides a promising approach for the treatment of AD.

Macrophage metabolism reprogramming EGCG-Cu coordination capsules delivered in polyzwitterionic hydrogel for burn wound healing and regeneration

Excessive reactive oxygen species (ROS) at severe burn injury sites may promote metabolic reprogramming of macrophages to induce a deteriorative and uncontrolled inflammation cycle, leading to delayed wound healing and regeneration. Here, a novel bioactive, anti-fouling, flexible polyzwitterionic hydrogel encapsulated with epigallocatechin gallate (EGCG)-copper (Cu) capsules (termed as EGCG-Cu@CBgel) is engineered for burn wound management, which is dedicated to synergistically exerting ROS-scavenging, immune metabolic regulation and pro-angiogenic effects. EGCG-Cu@CBgel can scavenge ROS to normalize intracellular redox homeostasis, effectively relieving oxidative damages and blocking proinflammatory signal transduction. Importantly, EGCG-Cu can inhibit the activity of hexokinase and phosphofructokinase, alleviate accumulation of pyruvate and convert it to acetyl coenzyme A (CoA), whereby inhibits glycolysis and normalizes tricarboxylic acid (TCA) cycle. Additionally, metabolic reprogramming of macrophages by EGCG-Cu downregulates M1-type polarization and the expression of proinflammatory cytokines both in vitro and in vivo. Meanwhile, copper ions (Cu2+) released from the hydrogel facilitate angiogenesis. EGCG-Cu@CBgel significantly accelerates the healing of severe burn wound via promoting wound closure, weakening tissue-damaging inflammatory responses and enhancing the remodeling of pathological structure. Overall, this study demonstrates the great potential of bioactive hydrogel dressing in treating burn wounds without unnecessary secondary damage to newly formed skin, and highlights the importance of immunometabolism modulation in tissue repair and regeneration.

Reactive X (where X = O, N, S, C, Cl, Br, and I) species nanomedicine

Reactive oxygen, nitrogen, sulfur, carbonyl, chlorine, bromine, and iodine species (RXS, where X = O, N, S, C, Cl, Br, and I) have important roles in various normal physiological processes and act as essential regulators of cell metabolism; their inherent biological activities govern cell signaling, immune balance, and tissue homeostasis. However, an imbalance between RXS production and consumption will induce the occurrence and development of various diseases. Due to the considerable progress of nanomedicine, a variety of nanosystems that can regulate RXS has been rationally designed and engineered for restoring RXS balance to halt the pathological processes of different diseases. The invention of radical-regulating nanomaterials creates the possibility of intriguing projects for disease treatment and promotes advances in nanomedicine. In this comprehensive review, we summarize, discuss, and highlight very-recent advances in RXS-based nanomedicine for versatile disease treatments. This review particularly focuses on the types and pathological effects of these reactive species and explores the biological effects of RXS-based nanomaterials, accompanied by a discussion and the outlook of the challenges faced and future clinical translations of RXS nanomedicines.

ROS-Scavenging Hydrogels Synergize with Neural Stem Cells to Enhance Spinal Cord Injury Repair via Regulating Microenvironment and Facilitating Nerve Regeneration

Although stem cell-based therapy is recognized as a promising therapeutic strategy for spinal cord injury (SCI), its efficacy is greatly limited by local reactive oxygen species (ROS)-abundant and hyper-inflammatory microenvironments. It is still a challenge to develop bioactive scaffolds with outstanding antioxidant capacity for neural stem cells (NSCs) transplantation. In this study, albumin biomimetic cerium oxide nanoparticles (CeO2 @BSA nanoparticles, CeNPs) are prepared in a simple and efficient manner and dispersed in gelatin methacryloyl to obtain the ROS-scavenging hydrogel (CeNP-Gel). CeNP-Gel synergistically promotes neurogenesis via alleviating oxidative stress microenvironments and improving the viability of encapsulated NSCs. More interestingly, in the presence of CeNP-Gel, microglial polarization to anti-inflammatory M2 subtype are obviously facilitated, which is further verified to be associated with phosphoinositide 3-kinase/protein kinase B pathway activation. Additionally, the injectable ROS-scavenging hydrogel is confirmed to induce the integration and neural differentiation of transplanted NSCs. Compared with the blank-gel group, the survival rate of NSCs in CeNP-Gel group is about 3.5 times higher, and the neural differentiation efficiency is about 2.1 times higher. Therefore, the NSCs-laden ROS-scavenging hydrogel represents a comprehensive strategy with great application prospect for the treatment of SCI through comprehensively modulating the adverse microenvironment.

Zn-MOF hydrogel: regulation of ROS-mediated inflammatory microenvironment for treatment of atopic dermatitis

Atopic dermatitis (AD) is a chronic and recurrent inflammation disease associated with immune dysfunction. The high level of reactive oxygen species (ROS) causes high oxidative stress and further results in the deterioration of AD. At the same time, the ROS produced by bacterial infection can further aggravate AD. Here, the prepared PVA-based hydrogel (Gel) has a high ROS scavenging ability, and the antibacterial agent Zn-MOF(ZIF-8) loaded into the hydrogel shows a lasting and effective antibacterial activity. Thus, a Zn-MOF hydrogel (Gel@ZIF-8) is prepared to regulate ROS-mediated inflammatory microenvironment. In vitro experiments show that Gel@ZIF-8 has good antibacterial effect and cell biocompatibility. In the AD-induced mouse model, Gel@ZIF-8 can significantly enhance the therapeutic effect, such as reduce the thickness of epidermis, the number of mast cells and IgE antibodies. The results indicate that the ROS-scavenging hydrogel could treat the AD by regulating the inflammatory microenvironment, providing a promising treatment for managing AD.

Ursolic acid ameliorates DNCB-induced atopic dermatitis-like symptoms in mice by regulating TLR4/NF-κB and Nrf2/HO-1 signaling pathways

BACKGROUND

Ursolic acid (UA) is a triterpenoid compound found in natural plants. It has been reported to have anti-inflammatory, antioxidant, and immunomodulatory properties. However, its role in atopic dermatitis (AD) is unknown. This study aimed to evaluate the therapeutic effect of UA in AD mice and explore the underlying mechanisms.

METHODS

Balb/c mice were treated with 2, 4-dinitrochlorobenzene (DNCB) to induce AD-like lesions. During modeling and medication administration, dermatitis scores and ear thickness were measured. Subsequently, histopathological changes, levels of T helper cytokines, and oxidative stress markers levels were evaluated. Immunohistochemistry staining was used to assess changes in the expression of the nuclear factor of kappa B (NF-κB) and NF erythroid 2-related factor 2 (Nrf2). Furthermore, CCK8 assay, reactive oxygen species (ROS) assay, real-time PCR, and western blotting were employed to evaluate the effects of UA on ROS levels, inflammatory mediator production, and the NF-κB and Nrf2 pathways in TNF-α/IFN-γ-stimulated HaCaT cells.

RESULTS

The results showed that UA significantly reduced dermatitis score and ear thickness, effectively inhibited skin proliferation and mast cell infiltration in AD mice, and decreased the expression level of T helper cytokines. Meanwhile, UA improved oxidative stress in AD mice by regulating lipid peroxidation and increasing the activity of antioxidant enzymes. In addition, UA inhibited ROS accumulation and chemokine secretion in TNF-α/IFN-γ-stimulated HaCaT cells. It might exert anti-dermatitis effects by inhibiting the TLR4/NF-κB pathway and activating the Nrf2/HO-1 pathway.

CONCLUSION

Taken together, our results suggest that UA may have potential therapeutic effects on AD and could be further studied as a promising drug for AD treatment.

Hydrogel dressing integrating FAK inhibition and ROS scavenging for mechano-chemical treatment of atopic dermatitis

Atopic dermatitis (AD) is a chronic skin disease caused by skin immune dyshomeostasis and accompanied by severe pruritus. Although oxidative stress and mechanical scratching can aggravate AD inflammation, treatment targeting scratching is often overlooked, and the efficiency of mechano-chemically synergistic therapy remains unclear. Here, we find that enhanced phosphorylation of focal adhesion kinase (FAK) is associated with scratch-exacerbated AD. We then develop a multifunctional hydrogel dressing that integrates oxidative stress modulation with FAK inhibition to synergistically treat AD. We show that the adhesive, self-healing and antimicrobial hydrogel is suitable for the unique scratching and bacterial environment of AD skin. We demonstrate that it can scavenge intracellular reactive oxygen species and reduce mechanically induced intercellular junction deficiency and inflammation. Furthermore, in mouse AD models with controlled scratching, we find that the hydrogel alleviates AD symptoms, rebuilds the skin barrier, and inhibits inflammation. These results suggest that the hydrogel integrating reactive oxygen species scavenging and FAK inhibition could serve as a promising skin dressing for synergistic AD treatment.

Targeting Endogenous Reactive Oxygen Species Removal and Regulating Regenerative Microenvironment at Annulus Fibrosus Defects Promote Tissue Repair

The excessive reactive oxygen species (ROS) level, inflammation, and weak tissue regeneration ability after annulus fibrosus (AF) injury constitute an unfavorable microenvironment for AF repair. AF integrity is crucial for preventing disc herniation after discectomy; however, there is no effective way to repair the AF. Herein, a composite hydrogel integrating properties of antioxidant, anti-inflammation, and recruitment of AF cells is developed through adding mesoporous silica nanoparticles modified by ceria and transforming growth factor β3 (TGF-β3) to the hydrogels. The nanoparticle loaded gelatin methacrylate/hyaluronic acid methacrylate composite hydrogels eliminate ROS and induce anti-inflammatory M2 type macrophage polarization. The released TGF-β3 not only plays a role in recruiting AF cells but is also responsible for promoting extracellular matrix secretion. The composite hydrogels can be solidified in situ in the defect area to effectively repair AF in rats. The strategies targeting endogenous ROS removal and improving the regenerative microenvironment by the nanoparticle-loaded composite hydrogels have potential applications in AF repair and intervertebral disc herniation prevention.

Pterostilbene reduces the progression of atopic dermatitis via modulating inflammatory and oxidative stress biomarkers in mice

Atopic dermatitis (AD) is one of the most prevalent chronic skin inflammatory disorders requiring continuous treatment and care. Pterostilbene (PTN) belongs to stilbene and is a polyphenolic compound of natural origin. It is similar to resveratrol and has analogous anti-inflammatory, anti-oxidant, and anti-carcinogenic characteristics. This study was intended to evaluate the effect of PTN against atopic dermatitis. The disease was induced by sensitization with 2,4-dinitrochlorobenzene (DNCB) in mice. The standard control group (SCG) received topical 0.1% tacrolimus (TC), whereas three other treatment groups received daily topical PTN at 0.2, 0.6, and 1% w/w for 28 days. Dermatitis scoring, ear thickness, and body weight of animals were weekly determined while other parameters were assessed at the termination of the experiment. PTN reduced the ear weight, skin thickness, and the weight and size of thymus glands and spleen in comparison with diseased animals. PTN also reduced the elevated immunoglobulin E (IgE) level and blood inflammatory cells in diseased mice. The histopathological findings showed a decreased epidermal thickness in PTN-treated groups. Moreover, treatment with PTN improved the amount of oxidative stress markers in the skin of the diseased mice. The expressions of IL-4, IL-6, TNF-α, and NF-κB in the skin of diseased mice were also reduced by PTN. This study concludes that PTN ameliorated the symptoms of atopic dermatitis through the reduction of inflammation, oxidative damage, and inflammatory cytokines in the skin of diseased animals. Therefore, PTN must be further investigated for the treatment of AD complications and other inflammatory skin disorders.

Redox Homeostasis Strategy for Inflammatory Macrophage Reprogramming in Rheumatoid Arthritis Based on Ceria Oxide Nanozyme-Complexed Biopolymeric Micelles

The synovial tissues under rheumatoid arthritis conditions are usually infiltrated by inflammatory cells, particularly M1 macrophages with aberrant redox homeostasis, which causes rapid deterioration of articular structure and function. Herein, we created an ROS-responsive micelle (HA@RH-CeO_X) through the in situ host-guest complexation between ceria oxide nanozymes and hyaluronic acid biopolymers, which precisely delivered nanozyme and clinically approved rheumatoid arthritis drug Rhein (RH) to proinflammatory M1 macrophage populations in inflamed synovial tissues. The abundant cellular ROS could cleave the thioketal linker to trigger the release of RH and Ce. Specifically, the Ce³⁺/Ce⁴⁺ redox pair could present SOD-like enzymatic activity to rapidly decompose ROS and alleviate the oxidative stress in M1 macrophages, while RH could inhibit the TLR4 signaling in M1 macrophages, both of which could act in a concerted manner to induce their repolarization into anti-inflammatory M2 phenotype to ameliorate local inflammation and promote cartilage repair. Notably, rats bearing rheumatoid arthritis showed a drastic increase in the M1-to-M2 macrophage ratio from 1:0.48 to 1:1.91 in the inflamed tissue and significantly reduced inflammatory cytokine levels including TNF-α and IL-6 following the intra-articular injection of HA@RH-CeO_X, accompanied by efficient cartilage regeneration and restored articular function. Overall, this study revealed an approach to in situ modulate the redox homeostasis in inflammatory macrophages and reprogram their polarization states through micelle-complexed biomimetic enzymes, which offers alternative opportunities for the treatment of rheumatoid arthritis.