The application of RNAi-based treatments for inflammatory bowel disease

Current and emerging applications of saccharide-modified chitosan: a critical review

Chitin, as the main component of the exoskeleton of Arthropoda, is a highly available natural polymer that can be processed into various value-added products. Its most important derivative, i.e., chitosan, comprising β-1,4-linked 2-amino-2-deoxy-β-d-glucose (deacetylated d-glucosamine) and N-acetyl-d-glucosamine units, can be prepared via alkaline deacetylation process. Chitosan has been used as a biodegradable, biocompatible, non-antigenic, and nontoxic polymer in some in-vitro applications, but the recently found potentials of chitosan for in-vivo applications based on its biological activities, especially antimicrobial, antioxidant, and anticancer activities, have upgraded the chitosan roles in biomaterials. Chitosan approval, generally recognized as a safe compound by the United States Food and Drug Administration, has attracted much attention toward its possible applications in diverse fields, especially biomedicine and agriculture. Even with some favorable characteristics, the chitosan's structure should be customized for advanced applications, especially due to its drawbacks, such as low drug-load capacity, low solubility, high viscosity, lack of elastic properties, and pH sensitivity. In this context, derivatization with relatively inexpensive and highly available mono- and di-saccharides to soluble branched chitosan has been considered a "game changer". This review critically reviews the emerging technologies based on the synthesis and application of lactose- and galactose-modified chitosan as two important chitosan derivatives. Some characteristics of chitosan derivatives and biological activities have been detailed first to understand the value of these natural polymers. Second, the saccharide modification of chitosan has been discussed briefly. Finally, the applications of lactose- and galactose-modified chitosan have been scrutinized and compared to native chitosan to provide an insight into the current state-of-the research for stimulating new ideas with the potential of filling research gaps.

In vivo self-assembled siRNA as a modality for combination therapy of ulcerative colitis

Given the complex nature of ulcerative colitis, combination therapy targeting multiple pathogenic genes and pathways of ulcerative colitis may be required. Unfortunately, current therapeutic strategies are usually based on independent chemical compounds or monoclonal antibodies, and the full potential of combination therapy has not yet been realized for the treatment of ulcerative colitis. Here, we develop a synthetic biology strategy that integrates the naturally existing circulating system of small extracellular vesicles with artificial genetic circuits to reprogram the liver of male mice to self-assemble multiple siRNAs into secretory small extracellular vesicles and facilitate in vivo delivery siRNAs through circulating small extracellular vesicles for the combination therapy of mouse models of ulcerative colitis. Particularly, repeated injection of the multi-targeted genetic circuit designed for simultaneous inhibition of TNF-α, B7-1 and integrin α4 rapidly relieves intestinal inflammation and exerts a synergistic therapeutic effect against ulcerative colitis through suppressing the pro-inflammatory cascade in colonic macrophages, inhibiting the costimulatory signal to T cells and blocking T cell homing to sites of inflammation. More importantly, we design an AAV-driven genetic circuit to induce substantial and lasting inhibition of TNF-α, B7-1 and integrin α4 through only a single injection. Overall, this study establishes a feasible combination therapeutic strategy for ulcerative colitis, which may offer an alternative to conventional biological therapies requiring two or more independent compounds or antibodies.

Circular RNAs as microRNA sponges: evidence and controversies

Gene expression in eukaryotic cells is a complex process encompassing several layers of regulation at the transcriptional and post-transcriptional levels. At the post-transcriptional level, microRNAs (miRs) are key regulatory molecules that function by binding directly to mRNAs. This generally leads to less efficient translation of the target mRNAs. More recently, an additional layer of gene regulation has been discovered, as other molecules, including circular RNAs (circRNAs), may bind to miRs and thereby function as sponges or decoys resulting in increased expression of the corresponding miR target genes. The circRNAs constitute a large class of mainly non-coding RNAs, which have been extensively studied in recent years, in particular in the cancer research field where many circRNAs have been proposed to function as miR sponges. Here, we briefly describe miR-mediated gene regulation and the extra layer of regulation that is imposed by the circRNAs. We describe techniques and methodologies that are commonly used to investigate potential miR sponging properties of circRNAs and discuss major pitfalls and controversies within this relatively new research field.

The Dynamic Inflammatory Tissue Microenvironment: Signality and Disease Therapy by Biomaterials

Tissue regeneration is an active multiplex process involving the dynamic inflammatory microenvironment. Under a normal physiological framework, inflammation is necessary for the systematic immunity including tissue repair and regeneration as well as returning to homeostasis. Inflammatory cellular response and metabolic mechanisms play key roles in the well-orchestrated tissue regeneration. If this response is dysregulated, it becomes chronic, which in turn causes progressive fibrosis, improper repair, and autoimmune disorders, ultimately leading to organ failure and death. Therefore, understanding of the complex inflammatory multiple player responses and their cellular metabolisms facilitates the latest insights and brings novel therapeutic methods for early diseases and modern health challenges. This review discusses the recent advances in molecular interactions of immune cells, controlled shift of pro- to anti-inflammation, reparative inflammatory metabolisms in tissue regeneration, controlling of an unfavorable microenvironment, dysregulated inflammatory diseases, and emerging therapeutic strategies including the use of biomaterials, which expand therapeutic views and briefly denote important gaps that are still prevailing.

Intradermal delivery of a fractional dose of influenza H7N9 split vaccine elicits protective immunity in mice and rats

Vaccination is the most effective method of preventing the spread of the influenza virus. However, the traditional intramuscular (IM) immunization causes fear, pain, and cross infection. In contrast, needle-free (NF) immunization is quick and easy for medical personnel and painless and safe for patients. In this study, we assessed the safety and protective efficacy of NF intradermal (ID) immunization with the influenza H7N9 split vaccine (Anhui H7N9/PR8). A preliminary safety evaluation showed that ID immunization with 15 μg of the H7N9 influenza vaccine was not toxic in rats. Moreover, the antigen was metabolized more rapidly after ID than after IM immunization, as determined by in vivo imaging, and ID immunization accelerated the generation of a specific immune response. Additionally, ID immunization with a 20% dose of the H7N9 split vaccine Anhui H7N9/PR8 offered complete protection against lethal challenge by the live H7N9 virus. Taken together, our findings suggest that NF ID immunization with the H7N9 influenza vaccine induces effective protection, has a good safety profile, requires little antigen, and elicits an immune response more rapidly than does IM immunization. This approach may be used to improve the control of influenza H7N9 outbreaks.

The contribution of long non-coding RNAs in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs) are multifactorial autoimmune diseases with growing prevalence but the interaction between genetic, environmental and immunologic factors in their development is complex and remains obscure. There is great need to understand their pathogenetic mechanisms and evolve diagnostic and therapeutic tools. Long non-coding RNAs (lncRNAs) are RNA molecules longer than 200 nucleotides that are known to interfere in gene regulation but their roles and functions have not yet been fully understood. While they are widely investigated in cancers, little is known about their contribution in other diseases. There is growing evidence that lncRNAs play critical role in regulation of immune system and that they interfere in the pathogenetic mechanisms of autoimmune diseases, like IBDs. Recent studies have identified lncRNAs in the proximity of IBD-associated genes and single nucleotide polymorphisms within IBD-associated lncRNAs as well. Furthermore, blood samples and pinch biopsies were also analyzed and a plethora of lncRNAs are found to be deregulated in Crohn's disease (CD), Ulcerative colitis (UC) or both. (Especially in UC samples the lncRNAs INFG-AS1 and BC012900 were found to be significantly up-regulated. Similarly, ANRIL, a lncRNA that nest different disease associated SNPs, is significantly down-regulated in inflamed IBD tissue.) This review aims at recording for the first time recent data about lncRNAs found to be deregulated in IBDs and discussing suggestive pathogenetic mechanisms and future use of lncRNAs as biomarkers.

RNA interference-based nanosystems for inflammatory bowel disease therapy

Inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn's disease, is a chronic, recrudescent disease that invades the gastrointestinal tract, and it requires surgery or lifelong medicinal therapy. The conventional medicinal therapies for IBD, such as anti-inflammatories, glucocorticoids, and immunosuppressants, are limited because of their systemic adverse effects and toxicity during long-term treatment. RNA interference (RNAi) precisely regulates susceptibility genes to decrease the expression of proinflammatory cytokines related to IBD, which effectively alleviates IBD progression and promotes intestinal mucosa recovery. RNAi molecules generally include short interfering RNA (siRNA) and microRNA (miRNA). However, naked RNA tends to degrade in vivo as a consequence of endogenous ribonucleases and pH variations. Furthermore, RNAi treatment may cause unintended off-target effects and immunostimulation. Therefore, nanovectors of siRNA and miRNA were introduced to circumvent these obstacles. Herein, we introduce non-viral nanosystems of RNAi molecules and discuss these systems in detail. Additionally, the delivery barriers and challenges associated with RNAi molecules will be discussed from the perspectives of developing efficient delivery systems and potential clinical use.

Mucin-mediated nanocarrier disassembly for triggered uptake of oligonucleotides as a delivery strategy for the potential treatment of mucosal tumours

This work demonstrates gastric mucin-triggered nanocarrier disassembly for release of antisense oligonucleotides and consequent unassisted cellular entry as a novel oral delivery strategy. A fluorescence activation-based reporter system was used to investigate the interaction and mucin-mediated disassembly of chitosan-based nanocarriers containing a 13-mer DNA oligonucleotide with a flanked locked RNA nucleic acid gapmer design. Gastric mucins were shown to trigger gapmer release from nanocarriers that was dependent on the interaction time, mucin concentration and N : P ratio with a maximal release at N : P 10. In contrast to siRNA, naked gapmers exhibited uptake into mucus producing HT-MTX mono-cultures and HT-MTX co-cultured with the carcinoma epithelial cell line Caco-2. Importantly, in vivo gapmer uptake was observed in epithelial tissue 30 min post-injection in murine intestinal loops. The findings present a mucosal design-based system tailored for local delivery of oligonucleotides that may maximize the effectiveness of gene silencing therapeutics within tumours at mucosal sites.