Oral encapsulated transforming growth factor β1 reduces endogenous levels: Effect on inflammatory bowel disease

Advancements in hydrogel-based drug delivery systems for the treatment of inflammatory bowel disease: a review

Inflammatory bowel disease (IBD) is a chronic disorder that affects millions of individuals worldwide. However, current drug therapies for IBD are plagued by significant side effects, low efficacy, and poor patient compliance. Consequently, there is an urgent need for novel therapeutic approaches to alleviate IBD. Hydrogels, three-dimensional networks of hydrophilic polymers with the ability to swell and retain water, have emerged as promising materials for drug delivery in the treatment of IBD due to their biocompatibility, tunability, and responsiveness to various stimuli. In this review, we summarize recent advancements in hydrogel-based drug delivery systems for the treatment of IBD. We first identify three pathophysiological alterations that need to be addressed in the current treatment of IBD: damage to the intestinal mucosal barrier, dysbiosis of intestinal flora, and activation of inflammatory signaling pathways leading to disequilibrium within the intestines. Subsequently, we discuss in depth the processes required to prepare hydrogel drug delivery systems, from the selection of hydrogel materials, types of drugs to be loaded, methods of drug loading and drug release mechanisms to key points in the preparation of hydrogel drug delivery systems. Additionally, we highlight the progress and impact of the hydrogel-based drug delivery system in IBD treatment through regulation of physical barrier immune responses, promotion of mucosal repair, and improvement of gut microbiota. In conclusion, we analyze the challenges of hydrogel-based drug delivery systems in clinical applications for IBD treatment, and propose potential solutions from our perspective.

Advances in engineering and delivery strategies for cytokine immunotherapy

INTRODUCTION

Cytokine immunotherapy is a growing field for the treatment of cancer, infectious disease, autoimmunity, and other ailments. Therapeutic cytokines are a class of secreted, small proteins that play a pivotal role in regulating the innate and adaptive immune system by provoking or mitigating immune responses. In the clinic, cytokines are frequently combined with other treatments, such as small molecules and monoclonal antibodies. However, the clinical translation of cytokine therapies is hindered by their short half-life, pleiotropic nature, and off-target effects, which cause diminished efficacy and severe systemic toxicity. Such toxicity limits dosage, thus resulting in suboptimal doses. Accordingly, numerous efforts have been devoted to exploring strategies to promote cytokine therapies by improving their tissue specificity and pharmacokinetics.

AREAS COVERED

Preclinical and clinical research into bioengineering and delivery strategies for cytokines, consisting of bioconjugation, fusion proteins, nanoparticles, and scaffold-based systems.

EXPERT OPINION

These approaches pave the way for the development of next-generation cytokine treatments with greater clinical benefit and reduced toxicity, circumventing such issues currently associated with cytokine therapy.

The Role of TGF-β, Activin and Follistatin in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an immune-mediated inflammatory condition predominantly affecting the gastrointestinal (GI) tract. An increasing prevalence of IBD has been observed globally. The pathogenesis of IBD includes a complex interplay between the intestinal microbiome, diet, genetic factors and immune responses. The consequent imbalance of inflammatory mediators ultimately leads to intestinal mucosal damage and defective repair. Growth factors, given their specific roles in maintaining the homeostasis and integrity of the intestinal epithelium, are of particular interest in the setting of IBD. Furthermore, direct targeting of growth factor signalling pathways involved in the regeneration of the damaged epithelium and the regulation of inflammation could be considered as therapeutic options for individuals with IBD. Several members of the transforming growth factor (TGF)-β superfamily, particularly TGF-β, activin and follistatin, are key candidates as they exhibit various roles in inflammatory processes and contribute to maintenance and homeostasis in the GI tract. This article aimed firstly to review the events involved in the pathogenesis of IBD with particular emphasis on TGF-β, activin and follistatin and secondly to outline the potential role of therapeutic manipulation of these pathways.

Oral Delivery of Encapsulated All-Trans Retinoic Acid Ameliorates Disease in Rodent Models of Colitis

BACKGROUND

All-trans retinoic acid (ATRA) is a biologically active isomer of retinoic acid (RA). Topical ATRA (retin-a, retin-a micro, atralin, renova, and avita) is the active pharmaceutical ingredient for FDA-approved treatments for acne and skin wrinkles. Oral formulations (Vesanoid) treat acute promyelocytic leukemia, but oral dosing can induce severe side effects. Despite benefits in various rodent models of inflammatory bowel disease (IBD), toxicity and controversial clinical observations have diminished enthusiasm for ATRA IBD clinical trials. To circumvent these issues and to use ATRA's key role in maintaining gut tolerance, we developed a poly(lactic-co-glycolic acid) (PLGA) microsphere (MS) encapsulated ATRA formulation aimed at directing ATRA delivery to immune structures of the gut, limiting systemic exposure. Initially, ATRA MS was developed as a component of a combinatorial product (TreXTAM) that also contained encapsulated transforming growth factor (TGF)-β and ATRA in a 1:2 w/w ratio. Although the combination was optimal, benefit was also observed when ATRA MS was given alone in the CD4+ CD25-T-cell adoptive transfer (ACT) colitis model.

METHODS

We used the ACT and DSS-induced murine models of colitis to expand on the dose-dependent effects of oral ATRA MS when given alone. The DSS model was also used to compare the efficacy of ATRA MS and soluble ATRA, while healthy animals were used to compare the pharmacokinetics of the two drugs.

RESULTS

In both the ACT and DSS-induced murine models of colitis, ATRA MS was observed to be effective in ameliorating disease. ATRA MS was also observed to be more effective than soluble ATRA in these models and displayed more favorable pharmacokinetics.

CONCLUSIONS

We suggest ATRA MS, as a standalone product, may attenuate IBD and perhaps limit fibrosis, while limiting systemic side effects.