Biological activity of heterologous murine interleukin-10 and preliminary studies on the use of a dextrin nanogel as a delivery system

PLGA-Chitosan Encapsulated IL-10 Nanoparticles Modulate Chlamydia Inflammation in Mice

Introduction

Interleukin-10 (IL-10) is a key anti-inflammatory mediator in protecting host from over-exuberant responses to pathogens and play important roles in wound healing, autoimmunity, cancer, and homeostasis. However, its application as a therapeutic agent for biomedical applications has been limited due to its short biological half-life. Therefore, it is important to prolong the half-life of IL-10 to replace the current therapeutic application, which relies on administering large and repeated dosages. Therefore, not a cost-effective approach. Thus, studies that aim to address this type of challenges are always in need.

Methods

Recombinant IL-10 was encapsulated in biodegradable nanoparticles (Poly-(Lactic-co-Glycolic Acid) and Chitosan)) by the double emulsion method and then characterized for size, surface charge, thermal stability, cytotoxicity, in vitro release, UV-visible spectroscopy, and Fourier Transform-Infrared Spectroscopy as well as evaluated for its anti-inflammatory effects. Bioactivity of encapsulated IL-10 was evaluated in vitro using J774A.1 macrophage cell-line and in vivo using BALB/c mice. Inflammatory cytokines (IL-6 and TNF-α) were quantified from culture supernatants using specific enzyme-linked immunosorbent assay (ELISA), and significance was analyzed using ANOVA.

Results

We obtained a high 96% encapsulation efficiency with smooth encapsulated IL-10 nanoparticles of ~100-150 nm size and release from nanoparticles as measurable to 22 days. Our result demonstrated that encapsulated IL-10 was biocompatible and functional by reducing the inflammatory responses induced by LPS in macrophages. Of significance, we also proved the functionality of encapsulated IL-10 by its capacity to reduce inflammation in BALB/c mice as provoked by Chlamydia trachomatis, an inflammatory sexually transmitted infectious bacterium.

Discussion

Collectively, our results show the successful IL-10 encapsulation, slow release to prolong its biological half-life and reduce inflammatory cytokines IL-6 and TNF production in vitro and in mice. Our results serve as proof of concept to further explore the therapeutic prospective of encapsulated IL-10 for biomedical applications, including inflammatory diseases.

Rational Design of Immunomodulatory Hydrogels for Chronic Wound Healing

With all the advances in tissue engineering for construction of fully functional skin tissue, complete regeneration of chronic wounds is still challenging. Since immune reaction to the tissue damage is critical in regulating both the quality and duration of chronic wound healing cascade, strategies to modulate the immune system are of importance. Generally, in response to an injury, macrophages switch from pro-inflammatory to an anti-inflammatory phenotype. Therefore, controlling macrophages' polarization has become an appealing approach in regenerative medicine. Recently, hydrogels-based constructs, incorporated with various cellular and molecular signals, have been developed and utilized to adjust immune cell functions in various stages of wound healing. Here, the current state of knowledge on immune cell functions during skin tissue regeneration is first discussed. Recent advanced technologies used to design immunomodulatory hydrogels for controlling macrophages' polarization are then summarized. Rational design of hydrogels for providing controlled immune stimulation via hydrogel chemistry and surface modification, as well as incorporation of cell and molecules, are also dicussed. In addition, the effects of hydrogels' properties on immunogenic features and the wound healing process are summarized. Finally, future directions and upcoming research strategies to control immune responses during chronic wound healing are highlighted.

Prolonged Release and Functionality of Interleukin-10 Encapsulated within PLA-PEG Nanoparticles

Inflammation, as induced by the presence of cytokines and chemokines, is an integral part of chlamydial infections. The anti-inflammatory cytokine, interleukin (IL)-10, has been reported to efficiently suppress the secretion of inflammatory cytokines triggered by Chlamydia in mouse macrophages. Though IL-10 is employed in clinical applications, its therapeutic usage is limited due to its short half-life. Here, we document the successful encapsulation of IL-10 within the biodegradable polymeric nanoparticles of PLA-PEG (Poly (lactic acid)-Poly (ethylene glycol), to prolong its half-life. Our results show the encapsulated-IL-10 size (~238 nm), zeta potential (−14.2 mV), polydispersity index (0.256), encapsulation efficiency (~77%), and a prolonged slow release pattern up to 60 days. Temperature stability of encapsulated-IL-10 was favorable, demonstrating a heat capacity of up to 89 °C as shown by differential scanning calorimetry analysis. Encapsulated-IL-10 modulated the release of IL-6 and IL-12p40 in stimulated macrophages in a time- and concentration-dependent fashion, and differentially induced SOCS1 and SOCS3 as induced by chlamydial stimulants in macrophages. Our finding offers the tremendous potential for encapsulated-IL-10 not only for chlamydial inflammatory diseases but also biomedical therapeutic applications.

In vivo systemic toxicity assessment of an oxidized dextrin-based hydrogel and its effectiveness as a carrier and stabilizer of granular synthetic bone substitutes

The worldwide incidence of bone disorders is raising, mainly due to aging population. The lack of effective treatments is pushing the development of synthetic bone substitutes (SBSs). Most ceramic-based SBSs commercially available display limited handling properties. Attempting to solve these issues and achieve wider acceptance by the clinicians, granular ceramics have been associated with hydrogels (HGs) to produce injectable/moldable SBSs. Dextrin, a low-molecular-weight carbohydrate, was used to develop a fully resorbable and injectable HG. It was first oxidized with sodium periodate and then cross-linked with adipic acid dihydrazide. The in vivo biocompatibility and safety of the dextrin-based HG was assessed by subacute systemic toxicity and skin sensitization tests, using rodent models. The results showed that the HG did not induce any systemic toxic effect, skin reaction, or genotoxicity, neither impaired the bone repair/regeneration process. Then, the HG was successfully combined with granular bone substitute, registered as Bonelike (250-500 μm) to obtain a moldable/injectable SBS, which was implanted in tibial fractures in goats for 3 and 6 weeks. The obtained results showed that HG allowed the stabilization of the granules into the defect, ensuring effective handling, and molding properties of the formulation, as well as an efficient cohesion of the granules. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1678-1689, 2019.

Hydrogel-based delivery of Il-10 improves treatment of bleomycin-induced lung fibrosis in mice

Idiopathic pulmonary fibrosis (IPF) is a life-threatening progressive lung disorder with limited therapeutic options. While interleukin-10 (IL-10) is a potent anti-inflammatory and anti-fibrotic cytokine, its utility in treating lung fibrosis has been limited by its short half-life. We describe an innovative hydrogel-based approach to deliver recombinant IL-10 to the lung for the prevention and reversal of pulmonary fibrosis in a mouse model of bleomycin-induced lung injury. Our studies show that a hyaluronan and heparin-based hydrogel system locally delivers IL-10 by capitalizing on the ability of heparin to reversibly bind IL-10 without bleeding or other complications. This formulation is significantly more effective than soluble IL-10 for both preventing and reducing collagen deposition in the lung parenchyma after 7 days of intratracheal administration. The anti-fibrotic effect of IL-10 in this system is dependent on suppression of TGF-β driven collagen production by lung fibroblasts and myofibroblasts. We conclude that hydrogel-based delivery of IL-10 to the lung is a promising therapy for fibrotic lung disorders.

Tissue Engineered Constructs for Periodontal Regeneration: Current Status and Future Perspectives

The periodontium, consisting of gingiva, periodontal ligament, cementum, and alveolar bone, is a hierarchically organized tissue whose primary role is to provide physical and mechanical support to the teeth. Severe cases of periodontitis, an inflammatory condition initiated by an oral bacterial biofilm, can lead to significant destruction of soft and hard tissues of the periodontium and result in compromised dental function and aesthetics. Although current treatment approaches can limit the progression of the disease by controlling the inflammatory aspect, complete periodontal regeneration cannot be predictably achieved. Various tissue engineering approaches are investigated for their ability to control the critical temporo-spatial wound healing events that are essential for achieving periodontal regeneration. This paper reviews recent progress in the field of periodontal tissue engineering with an emphasis on advanced 3D multiphasic tissue engineering constructs (TECs) and provides a critical analysis of their regenerative potential and limitations. The review also elaborates on the future of periodontal tissue engineering, including scaffold customization for individual periodontal defects, TEC's functionalization strategies for imparting enhanced bioactivity, periodontal ligament fiber guidance, and the utilization of chair-side regenerative solutions that can facilitate clinical translation.

Immune Regulation of Skin Wound Healing: Mechanisms and Novel Therapeutic Targets

Significance: The immune system plays a central role in orchestrating the tissue healing process. Hence, controlling the immune system to promote tissue repair and regeneration is an attractive approach when designing regenerative strategies. This review discusses the pathophysiology of both acute and chronic wounds and possible strategies to control the immune system to accelerate chronic wound closure and promote skin regeneration (scar-less healing) of acute wounds. Recent Advances: Recent studies have revealed the key roles of various immune cells and immune mediators in skin repair. Thus, immune components have been targeted to promote chronic wound repair or skin regeneration and several growth factors, cytokines, and biomaterials have shown promising results in animal models. However, these novel strategies are often struggling to meet efficacy standards in clinical trials, partly due to inadequate drug delivery systems and safety concerns. Critical Issues: Excess inflammation is a major culprit in the dysregulation of normal wound healing, and further limiting inflammation effectively reduces scarring. However, current knowledge is insufficient to efficiently control inflammation and specific immune cells. This is further complicated by inadequate drug delivery methods. Future Directions: Improving our understanding of the molecular pathways through which the immune system controls the wound healing process could facilitate the design of novel regenerative therapies. Additionally, better delivery systems may make current and future therapies more effective. To promote the entry of current regenerative strategies into clinical trials, more evidence on their safety, efficacy, and cost-effectiveness is also needed.

Potential of mannan or dextrin nanogels as vaccine carrier/adjuvant systems

Polymeric nanogels have been sophisticatedly designed promising a new generation of vaccine delivery/adjuvant systems capable of boosting immune response, a strategic priority in vaccine design. Here, nanogels made of mannan or dextrin were evaluated for their potential as carriers/adjuvants in vaccine formulations. Since lymph nodes are preferential target organs for vaccine delivery systems, nanogels were biotin-labeled, injected in the footpad of rats, and their presence in draining lymph nodes was assessed by immunofluorescence. Nanogels were detected in the popliteal and inguinal lymph nodes by 24 h upon subcutaneous administration, indicating entrapment in lymphatic organs. Moreover, the model antigen ovalbumin was physically encapsulated within nanogels and physicochemically characterized concerning size, zeta potential, ovalbumin loading, and entrapment efficiency. The immunogenicity of these formulations was assessed in mice intradermally immunized with ovalbumin–mannan or ovalbumin–dextrin by determining ovalbumin-specific antibody serum titers. Intradermal vaccination using ovalbumin–mannan elicited a humoral immune response in which ovalbumin-specific IgG1 levels were significantly higher than those obtained with ovalbumin alone, indicating a TH2-type response. In contrast, dextrin nanogel did not show adjuvant potential. Altogether, these results indicate that mannan nanogel is a material that should be explored as a future antigen delivery system.

Delivery strategies to control inflammatory response: Modulating M1-M2 polarization in tissue engineering applications

Macrophages are key players in many physiological scenarios including tissue homeostasis. In response to injury, typically the balance between macrophage sub-populations shifts from an M1 phenotype (pro-inflammatory) to an M2 phenotype (anti-inflammatory). In tissue engineering scenarios, after implantation of any device, it is desirable to exercise control on this M1-M2 progression and to ensure a timely and smooth transition from the inflammatory to the healing stage. In this review, we briefly introduce the current state of knowledge regarding macrophage function and nomenclature. Next, we discuss the use of controlled release strategies to tune the balance between the M1 and M2 phenotypes in the context of tissue engineering applications. We discuss recent literature related to the release of anti-inflammatory molecules (including nucleic acids) and the sequential release of cytokines to promote a timely M1-M2 shift. In addition, we describe the use of macrophages as controlled release agents upon stimulation by physical and/or mechanical cues provided by scaffolds. Moreover, we discuss current and future applications of "smart" implantable scaffolds capable of controlling the cascade of biochemical events related to healing and vascularization. Finally, we provide our opinion on the current challenges and the future research directions to improve our understanding of the M1-M2 macrophage balance and properly exploit it in tissue engineering and regenerative medicine applications.

Synthesis and characterization of biodegradable copolymer derived from dextrin and poly(vinyl acetate) via atom transfer radical polymerization

This article reports the development of a dextrin-based amphiphilic biodegradable graft copolymer (Dxt-g-pVAc) via atom transfer radical polymerization (ATRP).

Dextrin and poly(lactide)-based biocompatible and biodegradable nanogel for cancer targeted delivery of doxorubicin hydrochloride

Herein, we report the development and application of a novel biocompatible, chemically crosslinked nanogel for use in anticancer drug delivery.

Design and processing of nanogels as delivery systems for peptides and proteins

Nanogels, cross-linked networks of >1 μm in size, are attractive drug-delivery systems, as they not only possess the potential advantages of nanoscale formulations, but also the attractive abilities of a hydrogel; high hydrophilicity, high loading capacity and the potential for biocompatibility and controlled release. The focus of this review is to provide an overview of the recent developments within the nanogel field, and how the chemical design of the nanogel polymer has been found to influence the properties of the nanogel system. Novel nanogel systems are discussed with respect to their type of cross-linkage and their suitability as therapeutic delivery systems, as well as their ability to stabilize the protein/peptide drug.

Availability of polymeric nanoparticles for specific enhanced and targeted drug delivery

Over the past 20–30 years there has been quite a number of studies interested in polymeric nanoparticle (PNP) systems as a pharmaceutical approach for poorly soluble drugs, peptide drugs, gene and antibodies. Now, the products based on the PNP technologies are used in the fields of medical science, pharmaceutical science, tissue engineering and clothing, food and housing. This review focuses attention on PNPs for specific enhanced and targeted drug delivery of therapeutic drugs including peptide drugs as well as drug delivery applications of such systems. Outcomes from recent studies on polymers, how to make PNPs, pharmacokinetics and pharmacodynamics of PNPs, and the release profiles from PNPs and related systems are also described, including their pharmacokinetics and pharmacodynamics, if available. In addition, the latest PNP trends and will be described.

PEGylation of interleukin-10 improves the pharmacokinetic profile and enhances the antifibrotic effectivity in CCl₄-induced fibrogenesis in mice

Liver fibrosis represents a scar formation process as a response to chronic injury and a major cause of death worldwide. To date, no drug is available for this condition. Interleukin-10 (IL-10) has potent anti-inflammatory and antifibrotic properties but its short half-life in the circulation hampers its clinical use. Our aim was therefore to modify IL-10 with polyethylene glycol (PEG) to prolong its circulation time and enhance its effectivity. IL-10 was modified with 5 or 20 kDa PEG. The biological activity was preserved after PEGylation as assessed by inhibition of TNF-α production by macrophages. In vivo, during CCl(4)-induced fibrogenesis in mice, both 5PEG-IL-10 and 20PEG-IL-10 showed a longer circulation time compared to IL-10, which was associated with a significant increased liver accumulation. Immunohistochemical analysis of fibrotic livers of mice receiving treatment with IL-10 or its PEGylated forms, revealed a decrease in markers reflecting HSC and KC activation induced by 5PEG-IL10. Transcription levels of IL-6 were decreased upon treatment with IL-10 and both PEGylated forms, whereas IL-1β levels were only down-regulated by 5PEGIL-10 and 20PEGIL-10. We conclude that PEGylation of IL-10 is a good strategy to attenuate liver fibrosis and that 5PEGIL-10 is the most effective conjugate.

Drug-loaded chondroitin sulfate-based nanogels: preparation and characterization

Chondroitin sulfate-based (NMChS) nanogels synthesized by inverse microemulsion polymerization method for drug delivery were reported. The properties of NMChS were investigated by light scattering, FTIR, (1)H NMR and transmission electron microscopy observations. The results showed that the size of NMChS nanogels could be controlled in the range of 145-340 nm by changing the degree of maleoyl substitution of chondroitin sulfate, and these nanogels were responsive to pH changes, which exhibited extended stability in aqueous media and low cytotoxicity in vitro by MTT assays. When these nanogels were loaded with doxorubicin hydrochloride (DOX·HCl), a cytotoxic drug for cancer treatment, the high loading ability and the pH triggered-release of drug were obtained due to the electrostatic interactions between drug and matrix, and the pore size of the polymer network. This study clearly showed that the chondroitin sulfate-based nanogels are biocompatible and biodegradable, rendering potential for drug delivery applications.

Supramolecular assembled nanogel made of mannan

The supramolecular assembly of amphiphilic mannan, synthesized by the Michael addition of hydrophobic 1-hexadecanethiol to vinyl methacrylated mannan, originates in aqueous medium the formation of a nanogel, stabilized by hydrophobic interactions among alkyl chains. The critical aggregation concentration, calculated by fluorescence spectroscopy ranged between 0.002 and 0.01 mg/mL, depending on the polymer degree of substitution. The cryo-field emission scanning electron microscopy showed spherical macromolecular micelles with diameters between 100 and 500 nm. The dynamic light scattering analysis revealed a polydisperse colloidal system, with mean hydrodynamic diameter between 50 and 140 nm, depending on the polymer degree of substitution. The nanogel is negatively charged, stable over a 6 months storage period, and stable at pH 3-8, salt or urea solutions. Bovine serum albumin and curcumin were spontaneously incorporated in the nanogel, being stabilized by the hydrophobic domains, opening the possibility for future applications as potential delivery systems for therapeutic molecules. In vitro assays were carried out to characterize the biocompatibility of the nanogel. A toxic effect of mannan-C(16) was observed, specific to mouse macrophage-like cell line J774, not affecting mouse embryo fibroblast cell line 3T3 viability.

Synthesis and Characterization of Self-Assembled Nanogels Made of Pullulan

Self-assembled nanogels made of hydrophobized pullulan were obtained using a versatile, simple, reproducible and low-cost method. In a first reaction pullulan was modified with hydroxyethyl methacrylate or vinyl methacrylate, further modified in the second step with hydrophobic 1-hexadecanethiol, resulting as an amphiphilic material, which self-assembles in water via the hydrophobic interaction among alkyl chains. Structural features, size, shape, surface charge and stability of the nanogels were studied using hydrogen nuclear magnetic resonance, fluorescence spectroscopy, cryo-field emission scanning electron microscopy and dynamic light scattering. Above the critical aggregation concentration spherical polydisperse macromolecular micelles revealed long-term colloidal stability in aqueous medium, with a nearly neutral negative surface charge and mean hydrodynamic diameter in the range 100–400 nm, depending on the polymer degree of substitution. Good size stability was observed when nanogels were exposed to potential destabilizing pH conditions. While the size stability of the nanogel made of pullulan with vinyl methacrylate and more hydrophobic chains grafted was affected by the ionic strength and urea, nanogel made of pullulan with hydroxyethyl methacrylate and fewer hydrophobic chains grafted remained stable.

Self-assembled dextrin nanogel as protein carrier: controlled release and biological activity of IL-10

Interleukin-10 (IL-10) is an anti-inflammatory cytokine, which active form is a non-covalent homodimer. Given the potential of IL-10 for application in various medical conditions, it is essential to develop systems for its effective delivery. In previous work, it has been shown that a dextrin nanogel effectively incorporated and stabilized rIL-10, enabling its release over time. In this work, the delivery system based on dextrin nanogels was further analyzed. The biocompatibility of the nanogel was comprehensively analyzed, through cytotoxicity (lactate dehydrogenase (LDH) release, MTS, Live, and Dead) and genotoxicity (comet) assays. The release profile of rIL-10 and its biological activity were evaluated in vivo, using C57BL/6 mice. Although able to maintain a stable concentration of IL-10 for at least 4 h in mice serum, the amount of protein released was rather low. Despite this, the amount of rIL-10 released from the complex was biologically active inhibiting TNF-α production, in vivo, by LPS-challenged mice. In spite of the significant stabilization achieved using the nanogel, rIL-10 still denatures rather quickly. An additional effort is thus necessary to develop an effective delivery system for this cytokine, able to release active protein over longer periods of time. Nevertheless, the good biocompatibility, the protein stabilization effect and the ability to perform as a carrier with controlled release suggest that self-assembled dextrin nanogels may be useful protein delivery systems.