Kinetic analysis of in vitro and in vivo release of prednisolone from the conjugate of glycol-chitosan and succinyl-prednisolone

Targeting potential of alginate-glycyl-prednisolone conjugate nanogel to inflamed joints in rats with adjuvant-induced arthritis

The efficacy of alginate-glycyl-prednisolone conjugate nanogel (AL-GP-NG) was previously reported to be better than that of prednisolone (PD) alone in arthritic rats. In the present study, novel AL-GP-NG was prepared and its targeting potential was investigated. AL-GP-NG with a PD content of 6.3% (w/w) was obtained and had a slightly larger submicron size and similar zeta potential to that of the previous nanogel. Drug release profiles and pharmacokinetic features were similar to those of the previous nanogel. AL-GP-NG showed prolonged release at weakly acidic and neutral pH and the good systemic retention of total (free + conjugated) PD after an intravenous (i.v.) injection in rats. In animal studies using normal and adjuvant-induced arthritic rats, the distribution of total PD was examined after an i.v. injection. AL-GP-NG achieved a markedly higher drug concentration at inflamed joints than PD alone. Furthermore, ALGP-NG showed specific drug localisation to inflamed joints in arthritic rats, but not in normal rats. Furthermore, specific drug localisation to the joints by AL-GP-NG persisted. Collectively, these results demonstrated the good targeting potential of AL-GP-NG to inflamed joints, suggesting its suitability for the treatment of arthritis.

Combining dexamethasone and TNF-α siRNA within the same nanoparticles to enhance anti-inflammatory effect

We propose to combine two therapeutic anti-inflammatory approaches with different mechanisms of action in a single drug delivery system consisting of cationic dexamethasone palmitate nanoparticles (CDXP-NP) associated with TNF-α siRNA. The CDXP-NPs are obtained by the solvent emulsion evaporation technique using dexamethasone palmitate, a prodrug of dexamethasone, associated with a cationic lipid, DOTAP. Their physicochemical properties as well as their ability to bind siRNA were evaluated through gel electrophoresis and siRNA binding quantification. SiRNA cellular uptake was assessed by flow cytometry and confocal microscopy on RAW264.7 macrophages. TNF-α inhibition was determined on LPS-activated RAW264.7 macrophages. Stable and monodisperse nanoparticles around 100 nm with a positive zeta potential (+59 mV) were obtained with an encapsulation efficiency of the prodrug of 95%. A nitrogen/phosphate (N/P) ratio of 10 was selected that conferred the total binding of siRNA to the nanoparticles. Using these CDXP-siRNA-NPs, the siRNA was strongly internalized by RAW264.7 macrophage cells and localized within the cytoplasm. On the LPS-induced RAW264.7 macrophages, a larger inhibition of TNF-α was observed with CDXP-siRNA-NPs compared to CDXP-NPs alone. In conclusion, from these data, it is clear that a combination of DXP and TNF-α siRNA therapy could be a novel strategy and optimized alternative approach to cure inflammatory diseases.

Reactive Oxygen Species Responsive Theranostic Nanoplatform for Two-Photon Aggregation-Induced Emission Imaging and Therapy of Acute and Chronic Inflammation

Inflammation is a protective response to stimuli trauma, which can also lead to severe tissue injury. The existing anti-inflammatory drugs, such as corticosteroids and glucocorticoids, generally exhibit side effects and poor accumulation in inflammatory tissue. Hence, a theranostic nanoplatform with serial reactive oxygen species (ROS) responsiveness and two-photon AIE bioimaging has been constructed for dimensional diagnosis and accurate therapy of inflammation. Prednisolone (Pred) is bridged to a two-photon fluorophore (TP) developed by us via a ROS sensitive bond to form a diagnosis-therapy compound TPP, which is then loaded by the amphipathic polymer PMPC-PMEMA (PMM) through self-assembling into the core-shell structured micelles (TPP@PMM). With a particle size of 57.5 nm, TPP@PMM can realize the accumulation in the inflammatory site via the oedematous tissue and the accurate release of anti-inflammatory drug Pred through the serial response to the local overexpressed ROS. The micellar structure is first interrupted by the ROS triggered hydrophobic-to-hydrophilic conversion of PMEMA, which allows the release of TPP. Then the ROS responsive bond in TPP is subsequently broken, resulting in the accurate delivery of Pred and the inflammation therapy. Furthermore, TPP@PMM can be traced in vivo with a distinct two-photon imaging due to the AIE active fluorophore TP. The theranostic TPP@PMM reveals high-resolution inflammation diagnosis and efficient anti-inflammatory activity owing to the two-photon fluorophore and the serial ROS responsiveness and has been proven to achieve the efficient treatment of acute lung injury, arthritis, and atherosclerosis. Therefore, TPP@PMM holds considerable promise as a potential strategy for acute and chronic inflammation theranostics.

Nanogels of Succinylated Glycol Chitosan-Succinyl Prednisolone Conjugate: Preparation, In Vitro Characteristics and Therapeutic Potential

A novel anionic nanogel system was prepared using succinylated glycol chitosan-succinyl prednisolone conjugate (S-GCh-SP). The nanogel, named NG(S), was evaluated in vitro and in vivo. S-GCh-SP formed a nanogel via the aggregation of hydrophobic prednisolone (PD) moieties and the introduced succinyl groups contributed to the negative surface charge of the nanogel. The resultant NG(S) had a PD content of 13.7% (w/w), was ca. 400 nm in size and had a ζ-potential of −28 mV. NG(S) released PD very slowly at gastric pH and faster but gradually at small intestinal pH. Although NG(S) was easily taken up by the macrophage-like cell line Raw 264.7, it did not decrease cell viability, suggesting that the toxicity of the nanogel was very low. The in vivo evaluation was performed using rats with trinitrobenzene sulfonic acid (TNBS)-induced colitis. NG(S) and PD alone were not very effective at 5 mg PD eq./kg. However, NG(S) at 10 mg PD eq./kg markedly suppressed colonic damage, whereas PD alone did not. Furthermore, thymus atrophy was less with NG(S) than with PD alone. These results demonstrated that NG(S) is very safe, promotes drug effectiveness and has low toxicity. NG(S) has potential as a drug delivery system for the treatment of ulcerative colitis.

Polymer-drug conjugates in inflammation treatment

Inflammation is a vital defense mechanism of living organisms. However, persistent and chronic inflammation may lead to severe pathological processes and evolve into various chronic inflammatory diseases (CID), e.g. rheumatoid arthritis, multiple sclerosis, multiple sclerosis, systemic lupus erythematosus or inflammatory bowel diseases, or certain types of cancer. Their current treatment usually does not lead to complete remission. The application of nanotherapeutics may significantly improve CID treatment, since their accumulation in inflamed tissues has been described and is referred to as extravasation through leaky vasculature and subsequent inflammatory cell-mediated sequestration (ELVIS). Among nanotherapeutics, water-soluble polymer-drug conjugates may be highly advantageous in CID treatment due to the possibility of their passive and active targeting to the inflammation site and controlled release of active agents once there. The polymer-drug conjugate consists of a hydrophilic biocompatible polymer backbone along which the drug molecules are covalently attached via a biodegradable linker that enables controlled drug release. Their active targeting or bio-imaging can be achieved by introducing the cell-specific targeting moiety or imaging agents into the polymer conjugate. Here, we review the relationship between polymer conjugates and inflammation, including the benefits of the application of polymer conjugates in inflammation treatment, the anti-inflammatory activity of polymer drug conjugates and potential polymer-promoted inflammation and immunogenicity.

Electrical Signal Guided Ibuprofen Release from Electrodeposited Chitosan Hydrogel

Electrical signal guided drug release from conductive surface provides a simple and straightforward way for advanced drug delivery. In this study, we investigated the ibuprofen release from electrodeposited chitosan hydrogel by applying electrical signals. Specifically, chitosan hydrogel was electrodeposited on titanium plate and used as a matrix for ibuprofen load and release. The release of ibuprofen from the chitosan hydrogel on titanium plate was pH sensitive. By applying a positive or negative electrical potential, the release rate of ibuprofen from the electrodeposited chitosan can be facilely controlled. Thus, coupling chitosan electrodeposition and electrical signal control spurs new possibilities for biopolymeric coating and drug elution on conductive implants.

Development of macromolecular prodrug for rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that is considered to be one of the major public health problems worldwide. The development of therapies that target tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and co-stimulatory pathways that regulate the immune system have revolutionized the care of patients with RA. Despite these advances, many patients continue to experience symptomatic and functional impairment. To address this issue, more recent therapies that have been developed are designed to target intracellular signaling pathways involved in immunoregulation. Though this approach has been encouraging, there have been major challenges with respect to off-target organ side effects and systemic toxicities related to the widespread distribution of these signaling pathways in multiple cell types and tissues. These limitations have led to an increasing interest in the development of strategies for the macromolecularization of anti-rheumatic drugs, which could target them to the inflamed joints. This approach enhances the efficacy of the therapeutic agent with respect to synovial inflammation, while markedly reducing non-target organ adverse side effects. In this manuscript, we provide a comprehensive overview of the rational design and optimization of macromolecular prodrugs for treatment of RA. The superior and the sustained efficacy of the prodrug may be partially attributed to their Extravasation through Leaky Vasculature and subsequent Inflammatory cell-mediated Sequestration (ELVIS) in the arthritic joints. This biologic process provides a plausible mechanism, by which macromolecular prodrugs preferentially target arthritic joints and illustrates the potential benefits of applying this therapeutic strategy to the treatment of other inflammatory diseases.