RNA interference as a novel and powerful tool in immunopharmacological research

RNA Interference Applied to Crustacean Aquaculture

RNA interference (RNAi) is a powerful tool that can be used to specifically knock-down gene expression using double-stranded RNA (dsRNA) effector molecules. This approach can be used in aquaculture as an investigation instrument and to improve the immune responses against viral pathogens, among other applications. Although this method was first described in shrimp in the mid-2000s, at present, no practical approach has been developed for the use of dsRNA in shrimp farms, as the limiting factor for farm-scale usage in the aquaculture sector is the lack of cost-effective and simple dsRNA synthesis and administration procedures. Despite these limitations, different RNAi-based approaches have been successfully tested at the laboratory level, with a particular focus on shrimp. The use of RNAi technology is particularly attractive for the shrimp industry because crustaceans do not have an adaptive immune system, making traditional vaccination methods unfeasible. This review summarizes recent studies and the state-of-the-art on the mechanism of action, design, use, and administration methods of dsRNA, as applied to shrimp. In addition, potential constraints that may hinder the deployment of RNAi-based methods in the crustacean aquaculture sector are considered.

Study on the Regulation of Compound siRNA Nanoparticles on the Rat Model of Kidney Injury Induced by Sepsis by Inhibiting the Expression of NF-κB and P65

This article explores the pathogenesis of sepsis AKI, and seeks to protect the acute damage of sepsis tissues and organs. This study is to prepare a rat sepsis-induced AKI model by CLP, and to observe the pathological changes of kidney tissue and the function of kidney changes, and observe the effect of siRNA nanoparticles on its intervention, preliminary explore the protective effect and possible mechanism of siRNA nanoparticles on AKI in sepsis rats, and provide more information for the clinical treatment of siRNA nanoparticles in sepsis theoretical and experimental basis. We analysis the benefit and deficiency of nuclear factor-_κB (NF-_κB) activation in the pathogenesis of glomerulonephritis and its regulatory effect on NF-_κB activation. In the rat model group, no treatment was given after injection of nephrotoxic serum, and the rats were sacrificed on the 14th day; the compound siRNA nanoparticle intervention group (treatment group) was given dexamethasone 0.125 daily on the 1st to 14th day after nephrotoxic serum injection. Immunohistochemistry and medical image analysis system were used to observe NF-_κB activation of monocyte chemotactic protein-1 (MCP-1) in glomeruli and tubules, and analyze their relationship with proteinuria and glomerular cells. The results showed that the expression of NF-_κB in the glomeruli and tubules of the model group was significantly up-regulated regarding to the control group, and MCP-1's expression in the glomeruli and tubules of the model group was higher than that of the control group. The activation of NF-_κB and the expression of MCP-1 in glomeruli are closely related to monocyte infiltration and proteinuria; NF-_κB activation and MCP-1 expression in glomeruli and tubules of the compound siRNA nanoparticles intervention group were significantly down-regulated. It was concluded that the activation of NF-_κB has great impact on the pathogenesis of glomerulonephritis, and inhibition of NF-_κB activation may be one of the mechanisms of anti-nephritis effect.

Delivery of siRNAs to cancer cells via bacteria

RNA interference (RNAi) technology is a promising approach for efficient silencing of a particular gene for cancer gene therapy. However, the main obstacle for the development of RNAi-based therapeutic approaches is the delivery of the RNAi effector molecules to target cells. One promising strategy to surmount this challenge is the application of nonpathogenic bacteria as a delivery vector to target cells. In this chapter, the design of invasive Escherichia coli is described. The strain carries a plasmid encoding short hairpin RNAs (shRNAs), a protein (invasin) necessary for endocytotic absorption of the bacteria by target cells, and listeriolysin O required for the lysis of endocytotic vesicles within the target cells.

Self-Amplifying Replicon RNA Vaccine Delivery to Dendritic Cells by Synthetic Nanoparticles

Dendritic cells (DC) play essential roles determining efficacy of vaccine delivery with respect to immune defence development and regulation. This renders DCs important targets for vaccine delivery, particularly RNA vaccines. While delivery of interfering RNA oligonucleotides to the appropriate intracellular sites for RNA-interference has proven successful, the methodologies are identical for RNA vaccines, which require delivery to RNA translation sites. Delivery of mRNA has benefitted from application of cationic entities; these offer value following endocytosis of RNA, when cationic or amphipathic properties can promote endocytic vesicle membrane perturbation to facilitate cytosolic translocation. The present review presents how such advances are being applied to the delivery of a new form of RNA vaccine, replicons (RepRNA) carrying inserted foreign genes of interest encoding vaccine antigens. Approaches have been developed for delivery to DCs, leading to the translation of the RepRNA and encoded vaccine antigens both in vitro and in vivo. Potential mechanisms favouring efficient delivery leading to translation are discussed with respect to the DC endocytic machinery, showing the importance of cytosolic translocation from acidifying endocytic structures. The review relates the DC endocytic pathways to immune response induction, and the potential advantages for these self-replicating RNA vaccines in the near future.

RNA interference technology used for the study of aquatic virus infections

Aquaculture is one of the most important economic activities in Asia and is presently the fastest growing sector of food production in the world. Explosive increases in global fish farming have been accompanied by an increase in viral diseases. Viral infections are responsible for huge economic losses in fish farming, and control of these viral diseases in aquaculture remains a serious challenge. Recent advances in biotechnology have had a significant impact on disease reduction in aquaculture. RNAi is one of the most important technological breakthroughs in modern biology, allowing us to directly observe the effects of the loss of specific genes in living systems. RNA interference technology has emerged as a powerful tool for manipulating gene expression in the laboratory. This technology represents a new therapeutic approach for treating aquatic diseases, including viral infections. RNAi technology is based on a naturally occurring post-transcriptional gene silencing process mediated by the formation of dsRNA. RNAi has been proven widely effective for gene knockdown in mammalian cultured cells, but its utility in fish remains unexplored. This review aims to highlight the RNAi technology that has made significant contributions toward the improvement of aquatic animal health and will also summarize the current status and future strategies concerning the therapeutic applications of RNAi to combat viral disease in aquacultured organisms.

Poly(I:C) exhibits an anti-cancer effect in human gastric adenocarcinoma cells which is dependent on RLRs

Poly(I:C), an agonist of TLR3 and RLRs, has been used as an immune adjuvant in clinical trials for many years. Although it has been found to trigger apoptosis in a variety of cancers, its mechanisms in human gastric adenocarcinoma is unclear. The purpose of this study was to assess the effect of poly(I:C) on human gastric adenocarcinoma cells. Our observations showed that intracellular delivery of poly(I:C) by liposomes had a pro-apoptotic effect in vitro, and significantly inhibited xenograft growth of human gastric adenocarcinoma in nude mice. Further investigations indicated that RLRs, as intrinsic RNA sensors, contributed to the poly(I:C)-triggered apoptotic effect through upregulation of RIG-I, MDA-5, and most significantly, LGP2, accompanied by increased expression of Bcl-2 family members. Conversely, this apoptotic effect was greatly reduced by silencing RIG-I, MDA-5, or LGP2. Although LGP2 is considered an innate immune negative regulator of RIG-I and MDA-5, it exhibited a positive regulatory effect on poly(I:C)-induced apoptosis in human gastric adenocarcinoma cells. These findings suggested that poly(I:C) may be a promising chemotherapeutic agent against human gastric adenocarcinoma.

Exploring RNAi as a therapeutic strategy for controlling disease in aquaculture

Aquatic animal diseases are one of the most significant constraints to the development and management of aquaculture worldwide. As a result, measures to combat diseases of fish and shellfish have assumed a high priority in many aquaculture-producing countries. RNA interference (RNAi), a natural mechanism for post-transcriptional silencing of homologous genes by double-stranded RNA (dsRNA), has emerged as a powerful tool not only to investigate the function of specific genes, but also to suppress infection or replication of many pathogens that cause severe economic losses in aquaculture. However, despite the enormous potential as a novel therapeutical approach, many obstacles must still be overcome before RNAi therapy finds practical application in aquaculture, largely due to the potential for off-target effects and the difficulties in providing safe and effective delivery of RNAi molecules in vivo. In the present review, we discuss the current knowledge of RNAi as an experimental tool, as well as the concerns and challenges ahead for the application of such technology to combat infectious disease of farmed aquatic animals.

‘Smart’ non-viral delivery systems for targeted delivery of RNAi to the lungs

The emergence of RNAi offers a potentially exciting new therapeutic paradigm for respiratory diseases. However, effective delivery remains a key requirement for their translation into the clinic and has been a major factor in the limited clinical success seen to date. Inhalation offers tissue-specific targeting of the RNAi to treat respiratory diseases and a diminished risk of off-target effects. In order to deliver RNAi directly to the respiratory tract via inhalation, ‘smart’ non-viral carriers are required to protect the RNAi during delivery/aerosolization and enhance cell-specific uptake to target cells. Here, we review the state-of-the-art in therapeutic aerosol bioengineering, and specifically non-viral siRNA delivery platforms, for delivery via inhalation. This includes developments in inhaler device engineering and particle engineering, including manufacturing methods and excipients used in therapeutic aerosol bioengineering that underpin the development of smart, cell type-specific delivery systems to target siRNA to respiratory epithelial cells and/or alveolar macrophages.

Functional RNA delivery targeted to dendritic cells by synthetic nanoparticles

Dendritic cells (DCs) are essential to many aspects of immune defense development and regulation. They provide important targets for prophylactic and therapeutic delivery. While protein delivery has had considerable success, RNA delivery is still expanding. Delivering RNA molecules for RNAi has shown particular success and there are reports on successful delivery of mRNA. Central, therein, is the application of cationic entities. Following endocytosis of the delivery vehicle for the RNA, cationic entities should promote vesicular membrane perturbation, facilitating cytosolic release. The present review explains the diversity of DC function in immune response development and control. Promotion of delivered RNA cytosolic release is discussed, relating to immunoprophylactic and therapeutic potential, and DC endocytic machinery is reviewed, showing how DC endocytic pathways influence the handling of internalized material. The potential advantages for application of replicating RNA are presented and discussed, in consideration of their value and development in the near future.

Liposomal Nanomedicines: An Emerging Field

Liposomal nanoparticles (LNs) encapsulating therapeutic agents, or liposomal nanomedicines (LNMs), represent one of the most advanced classes of drug delivery systems, with several currently on the market and many more in clinical trials. During the past 20 years, a variety of techniques have been developed for encapsulating both conventional drugs and the new genetic drugs (plasmid DNA–containing therapeutic genes, anti-sense oligonucleotides, and small, interfering RNA [siRNA]) within LNs encompassing a very specific set of properties: a diameter centered on 100 nm, a high drug-to-lipid ratio, excellent retention of the encapsulated drug, and a long (> 6 hours) circulation lifetime. Particles with these properties tend to accumulate at sites of disease, such as tumors, where the endothelial layer is “leaky” and allows extravasation of particles with small diameters. Thus, LNs protect the drug during circulation, prevent it from reaching healthy tissues, and permit its accumulation at sites of disease. We will discuss recent advances in this field involving conventional anticancer drugs as well as gene-delivery, immunostimulatory, and gene-silencing applications involving the new genetic drugs. LNMs have the potential to offer new treatments in such areas as cancer therapy, vaccine development, and cholesterol management.