DNAzyme for TGF-β suppressed extracellular matrix accumulation in experimental glomerulonephritis

Fibrosis in Chronic Kidney Disease: Pathophysiology and Therapeutic Targets

Chronic kidney disease (CKD) is a slowly progressive condition characterized by decreased kidney function, tubular injury, oxidative stress, and inflammation. CKD is a leading global health burden that is asymptomatic in early stages but can ultimately cause kidney failure. Its etiology is complex and involves dysregulated signaling pathways that lead to fibrosis. Transforming growth factor (TGF)-β is a central mediator in promoting transdifferentiation of polarized renal tubular epithelial cells into mesenchymal cells, resulting in irreversible kidney injury. While current therapies are limited, the search for more effective diagnostic and treatment modalities is intensive. Although biopsy with histology is the most accurate method of diagnosis and staging, imaging techniques such as diffusion-weighted magnetic resonance imaging and shear wave elastography ultrasound are less invasive ways to stage fibrosis. Current therapies such as renin-angiotensin blockers, mineralocorticoid receptor antagonists, and sodium/glucose cotransporter 2 inhibitors aim to delay progression. Newer antifibrotic agents that suppress the downstream inflammatory mediators involved in the fibrotic process are in clinical trials, and potential therapeutic targets that interfere with TGF-β signaling are being explored. Small interfering RNAs and stem cell-based therapeutics are also being evaluated. Further research and clinical studies are necessary in order to avoid dialysis and kidney transplantation.

A promising nucleic acid therapy drug: DNAzymes and its delivery system

Based on the development of nucleic acid therapeutic drugs, DNAzymes obtained through in vitro selection technology in 1994 are gradually being sought. DNAzymes are single-stranded DNA molecules with catalytic function, which specifically cleave RNA under the action of metal ions. Various in vivo and in vitro models have recently demonstrated that DNAzymes can target related genes in cancer, cardiovascular disease, bacterial and viral infection, and central nervous system disease. Compared with other nucleic acid therapy drugs, DNAzymes have gained more attention due to their excellent cutting efficiency, high stability, and low cost. Here, We first briefly reviewed the development and characteristics of DNAzymes, then discussed disease-targeting inhibition model of DNAzymes, hoping to provide new insights and ways for disease treatment. Finally, DNAzymes were still subject to some restrictions in practical applications, including low cell uptake efficiency, nuclease degradation and interference from other biological matrices. We discussed the latest delivery strategy of DNAzymes, among which lipid nanoparticles have recently received widespread attention due to the successful delivery of the COVID-19 mRNA vaccine, which provides the possibility for the subsequent clinical application of DNAzymes. In addition, the future development of DNAzymes was prospected.

Induction of a local muscular dystrophy using electroporation in vivo: an easy tool for screening therapeutics

Intramuscular injection and electroporation of naked plasmid DNA (IMEP) has emerged as a potential alternative to viral vector injection for transgene expression into skeletal muscles. In this study, IMEP was used to express the DUX4 gene into mouse tibialis anterior muscle. DUX4 is normally expressed in germ cells and early embryo, and silenced in adult muscle cells where its pathological reactivation leads to Facioscapulohumeral muscular dystrophy. DUX4 encodes a potent transcription factor causing a large deregulation cascade. Its high toxicity but sporadic expression constitutes major issues for testing emerging therapeutics. The IMEP method appeared as a convenient technique to locally express DUX4 in mouse muscles. Histological analyses revealed well delineated muscle lesions 1-week after DUX4 IMEP. We have therefore developed a convenient outcome measure by quantification of the damaged muscle area using color thresholding. This method was used to characterize lesion distribution and to assess plasmid recirculation and dose–response. DUX4 expression and activity were confirmed at the mRNA and protein levels and through a quantification of target gene expression. Finally, this study gives a proof of concept of IMEP model usefulness for the rapid screening of therapeutic strategies, as demonstrated using antisense oligonucleotides against DUX4 mRNA.

Targeting TGF-β Signaling in Kidney Fibrosis

Renal fibrosis is the final common pathway of numerous progressive kidney diseases, and transforming growth factor-β (TGF-β) has an important role in tissue fibrosis by up-regulating matrix protein synthesis, inhibiting matrix degradation, and altering cell-cell interaction. Many strategies targeting TGF-β, including inhibition of production, activation, binding to the receptor, and intracellular signaling, have been developed. Some of them were examined in clinical studies against kidney fibrosis, and some are applied to other fibrotic diseases or cancer. Here, I review the approaches targeting TGF-β signaling in kidney fibrosis.

DNA enzymes as potential therapeutics: towards clinical application of 10-23 DNAzymes

INTRODUCTION

Ongoing studies on the inhibition of gene expression at the mRNA level have identified several types of specific inhibitors such as antisense oligonucleotides, small interfering RNA, ribozymes and DNAzymes (Dz). After its discovery in 1997, the 10-23 Dz (which can cleave RNA efficiently and site-specifically, has flexible design, is independent from cell mechanisms, does not require expensive chemical modifications for effective use in vivo) has been employed to downregulate a range of therapeutically important genes. Recently, 10-23 Dzs have taken their first steps into clinical trials.

AREAS COVERED

This review focuses predominantly on Dz applications as potential antiviral, antibacterial, anti-cancer and anti-inflammatory agents as well as for the treatment of cardiovascular disease and diseases of CNS, summarizing results of their clinical trials up to the present day.

EXPERT OPINION

In comparison with antisense oligonucleotides and small interfering RNAs, Dzs do not usually show off-target effects due to their high specificity and lack of immunogenicity in vivo. As more results of clinical trials carried out so far are gradually becoming available, Dzs may turn out to be safe and well-tolerated therapeutics in humans. Therefore, there is a good chance that we may witness a deoxyribozyme drug reaching the clinic in the near future.

Absence of unspecific innate immune cell activation by GATA-3-specific DNAzymes

DNAzymes of the 10-23 family represent an important class of antisense molecules with implications for therapeutic treatment of diseases. These molecules are single-stranded oligodeoxynucleotides combining the high specificity of oligonucleotide base pairing with an inherent RNA-cleaving enzymatic activity. However, like other oligonucleotide-based molecules these substances might exert so-called off-target effects, which have not been investigated so far for this molecule class. Therefore, the present study investigates putative off-target effects of DNAzymes on innate immune mechanisms using GATA-3-specific DNAzymes that have recently been developed as novel therapeutic approach for the treatment of allergic diseases including allergic asthma. The conserved catalytic domain of 10-23 DNAzymes contains a CpG motif that may stimulate innate immune cells via Toll-like receptor 9 (TLR-9). Therefore, potential TLR-9-mediated as well as TLR-9 independent cell activation was investigated using TLR-9-transfected HEK293 cells, macrophage cell lines and primary innate immune cells. Furthermore, putative effects of GATA-3-specific DNAzymes on the activation of neutrophil granulocytes and degranulation of mast cells/basophils were analyzed. In summary, no innate immune cell-stimulating activities of the tested DNAzymes were observed in any of the systems. Consequently, use of GATA-3-specific DNAzymes may represent a novel and highly specific approach for the treatment of allergic diseases.

Deoxyribozymes and bioinformatics: complementary tools to investigate axon regeneration

For over 100 years, scientists have tried to understand the mechanisms that lead to the axonal growth seen during development or the lack thereof during regeneration failure after spinal cord injury (SCI). Deoxyribozyme technology as a potential therapeutic to treat SCIs or other insults to the brain, combined with a bioinformatics approach to comprehend the complex protein-protein interactions that occur after such trauma, is the focus of this review. The reader will be provided with information on the selection process of deoxyribozymes and their catalytic sequences, on the mechanism of target digestion, on modifications, on cellular uptake and on therapeutic applications and deoxyribozymes are compared with ribozymes, siRNAs and antisense technology. This gives the reader the necessary knowledge to decide which technology is adequate for the problem at hand and to design a relevant agent. Bioinformatics helps to identify not only key players in the complex processes that occur after SCI but also novel or less-well investigated molecules against which new knockdown agents can be generated. These two tools used synergistically should facilitate the pursuit of a treatment for insults to the central nervous system.

Deoxyribozymes: new therapeutics to treat central nervous system disorders

This mini-review focuses on a knockdown technology called deoxyribozymes, which has rarely been utilized in the field of neurobiology/neuroscience. Deoxyribozymes are catalytic DNA molecules, which are also entitled DNA enzyme or DNAzyme. This mini-review presents a description of their development, structure, function, and therapeutic application. In addition, information on siRNA, ribozymes, and antisense are given. Further information on two deoxyribozymes against c-Jun and xylosyltransferase (XT) mRNA are summarized of which the first is important to influence many neurological disorders and the last potentially treats spinal cord injuries (SCIs). In particular, insults to the central nervous system (CNS) such as SCI generate an inhibitory environment (lesion scar) at the injury site that prevents the endogenous and therapy-induced axonal regeneration and thereby limits repair strategies. Presently, there are no treatments available. Hence, deoxyribozymes provide an opportunity for new therapeutics that alter the inhibitory nature of the lesion scar and thus promote axonal growth in the injured spinal cord. When used cautiously and within the limits of its ability the deoxyribozyme technology holds promise to become a major contributing factor in repair strategies of the CNS.

Regenerative medicine of the kidney

End stage renal disease is a major health problem in this country and worldwide. Although dialysis and kidney transplantation are currently used to treat this condition, kidney regeneration resulting in complete healing would be a desirable alternative. In this review we focus our attention on current therapeutic approaches used clinically to delay the onset of kidney failure. In addition we describe novel approaches, like Tissue Engineering, Stem cell Applications, Gene Therapy, and Renal Replacement Therapy that may one day be possible alternative therapies for patients with the hope of delaying kidney failure or even stopping the progression of renal disease.

Interleukin-18, transforming growth factor-β, and vascular endothelial growth factor gene polymorphisms and susceptibility to primary glomerulonephritis

Several studies have showed an association of gene polymorphisms with the development of glomerulonephritis (GN). We investigated the effects of gene polymorphisms on the development of GN by analyzing polymorphisms in the interleukin (IL)-18, transforming growth factor (TGF)-β, and vascular endothelial growth factor (VEGF) genes in Korean patients with primary GN. The study included 146 normal subjects (controls) and 100 patients diagnosed with primary GN by kidney biopsy. The gene polymorphisms A-607C and G-137C in IL-18, C-509T and T869C in TGF-β1, and C-2578A and C405G in VEGF were investigated in DNA extracted from peripheral blood. Significant differences were observed between the GN and control groups in the genotype and allele frequencies of A-607C IL-18 and C405G VEGF. The frequencies of the IL-18-607CC genotype [P = 0.001, odds ratio (OR) = 2.473] and the VEGF 405GG genotype (P = 0.001, OR = 2.473) were significantly increased in the GN group. The combination of IL-18-607CC+ and VEGF 405GG+ genotypes had a higher risk for developing GN in comparison with the combination of IL-18-607CC- and VEGF 405GG- genotypes (P < 0.001, OR = 8.642). In the haplotype analysis of the IL-18 gene, the CG haplotype was significantly more frequent in the GN group than the control group (61.5% vs 46.9%, P = 0.002). These results show that the -607CC genotype of the IL-18 gene and the 405GG genotype of the VEGF gene are associated with susceptibility to and the development of primary GN.

AAV2-mediated in vivo immune gene therapy of solid tumours

Background

Many strategies have been adopted to unleash the potential of gene therapy for cancer, involving a wide range of therapeutic genes delivered by various methods. Immune therapy has become one of the major strategies adopted for cancer gene therapy and seeks to stimulate the immune system to target tumour antigens. In this study, the feasibility of AAV2 mediated immunotherapy of growing tumours was examined, in isolation and combined with anti-angiogenic therapy.

Methods

Immune-competent Balb/C or C57 mice bearing subcutaneous JBS fibrosarcoma or Lewis Lung Carcinoma (LLC) tumour xenografts respectively were treated by intra-tumoural administration of AAV2 vector encoding the immune up-regulating cytokine granulocyte macrophage-colony stimulating factor (GM-CSF) and the co-stimulatory molecule B7-1 to subcutaneous tumours, either alone or in combination with intra-muscular (IM) delivery of AAV2 vector encoding Nk4 14 days prior to tumour induction. Tumour growth and survival was monitored for all animals. Cured animals were re-challenged with tumourigenic doses of the original tumour type. In vivo cytotoxicity assays were used to investigate establishment of cell-mediated responses in treated animals.

Results

AAV2-mediated GM-CSF, B7-1 treatment resulted in a significant reduction in tumour growth and an increase in survival in both tumour models. Cured animals were resistant to re-challenge, and induction of T cell mediated anti-tumour responses were demonstrated. Adoptive transfer of splenocytes to naïve animals prevented tumour establishment. Systemic production of Nk4 induced by intra-muscular (IM) delivery of Nk4 significantly reduced subcutaneous tumour growth. However, combination of Nk4 treatment with GM-CSF, B7-1 therapy reduced the efficacy of the immune therapy.

Conclusions

Overall, this study demonstrates the potential for in vivo AAV2 mediated immune gene therapy, and provides data on the inter-relationship between tumour vasculature and immune cell recruitment.

Novel treatment for lithium-induced nephrogenic diabetes insipidus rat model using the Sendai-virus vector carrying aquaporin 2 gene

Congenital nephrogenic diabetes insipidus (NDI) is a chronic disorder involving polyuria and polydipsia that results from unresponsiveness of the renal collecting ducts to the antidiuretic hormone vasopressin. Either of the genetic defects in vasopressin V2 receptor or the water channel aquaporin 2 (AQP2) cause the disease, which interfere the water reabsorption at the epithelium of the collecting duct. An unconscious state including a perioperative situation can be life threatening because of the difficulty to regulate their water balance. The Sendai virus (SeV) vector system deleting fusion protein (F) gene (SeV/DeltaF) is considered most suitable because of the short replication cycle and nontransmissible character. An animal model for NDI with reduced AQP2 by lithium chloride was used to develop the therapy. When the SeV/DeltaF vector carrying a human AQP2 gene (AQP2-SeV/DeltaF) was administered retrogradely via ureter to renal pelvis, AQP2 was expressed in the renal collecting duct to reduce urine output and water intake by up to 40%. In combination with the retorograde administration to pelvis, this system could be the cornerstone for the applicable therapies on not only NDI patients but also other diseases associate with the medullary collecting duct.

Inhibition of respiratory syncytial virus of subgroups A and B using deoxyribozyme DZ1133 in mice

Respiratory syncytial virus (RSV) commonly infects the upper and lower respiratory tracts. Currently, there is no effective treatment available. Deoxyribozymes are a potential therapeutic for RSV and their activity is based on the ability to bind and cleave complementary RNA sequences to inhibit protein expression. DZ1133 is a deoxyribozyme that targets the conserved genomic RNA sequence of the RSV nucleocapsid protein and has been shown to significantly inhibit various strains of RSV including subgroups A and B, standard A2 and CH18537 strains, and CQ381513, CQ381170, BJ01 and BJ04 strains. Treatment with DZ1133 decreased viral plaque formation in lungs of RSV-infected BALB/c mice. In addition, viral mRNA expression was reduced, airway inflammation was alleviated, and leukocyte counts were reduced in bronchoalveolar lavage fluid of RSV-infected mice. The antiviral effect of DZ1133 was dose-dependent (0.2-0.8mg) and more efficient than antisense oligonucleotide inhibition of gene expression. However, levels of cytokines TNF-alpha, IFN-gamma, IL-12, and IL-10 induced by RSV infection were not affected by DZ1133 treatment. Our data demonstrate that DZ1133 is a potential therapeutic agent against both subgroups A and B RSV infection in vivo.

Brothers in arms: DNA enzymes, short interfering RNA, and the emerging wave of small-molecule nucleic acid-based gene-silencing strategies

The past decade has seen the rapid evolution of small-molecule gene-silencing strategies, driven largely by enhanced understanding of gene function in the pathogenesis of disease. Over this time, many genes have been targeted by specifically engineered agents from different classes of nucleic acid-based drugs in experimental models of disease to probe, dissect, and characterize further the complex processes that underpin molecular signaling. Arising from this, a number of molecules have been examined in the setting of clinical trials, and several have recently made the successful transition from the bench to the clinic, heralding an exciting era of gene-specific treatments. This is particularly important because clear inadequacies in present therapies account for significant morbidity, mortality, and cost. The broad umbrella of gene-silencing therapeutics encompasses a range of agents that include DNA enzymes, short interfering RNA, antisense oligonucleotides, decoys, ribozymes, and aptamers. This review tracks current movements in these technologies, focusing mainly on DNA enzymes and short interfering RNA, because these are poised to play an integral role in antigene therapies in the future.

Electroporation-mediated gene therapy

Non-viral gene transfer is markedly enhanced by the application of in vivo electroporation. Electroporation is a safe and efficient system to introduce genes to a wide variety of tissues, including skeletal muscle, tumors, kidney, liver and skin. Electroporation has been demonstrated to be effective in numerous disease models. This review focuses on the principles of electroporation and the target tissues employed for gene therapy. Based on the accumulation of positive results, the first clinical study for the treatment of malignant melanoma is now underway, and preclinical studies have suggested that electroporation is useful as a gene therapy protocol.

DNAzyme-mediated inhibition of Japanese encephalitis virus replication in mouse brain

Japanese encephalitis virus (JEV) is an arthropod-borne flavivirus with a single-stranded RNA genome containing non-coding regions (NCRs) at its 5' and 3'-ends. The NCRs have flavivirus-conserved sequences that are important for virus replication. Here we describe DNAzymes (Dzs) that cleave the RNA sequence of the 3'-NCR of JEV genome in vitro. The nuclease-resistant Dzs, containing phosphorothioate linkages, were efficiently taken up by mouse neuronal and glial cells, and addition of a continuous stretch of 10 guanosine residues (poly-(G)(10)) to the 3'-end of a Dz led to its enhanced delivery to cells containing scavenger receptors (ScRs). These novel Dzs inhibited JEV replication in cultured mouse cells of neuronal and macrophage origin. JEV is a neurotropic virus that actively replicates in mouse brain. Here we show that intra-cerebral (i.c.) administration of a poly-(G)(10)-tethered, phosphorothioated Dz in JEV-infected mice led to more than 99.99% inhibition of virus replication in brain, resulting in a dose-dependent extended lifespan or complete recovery of the infected animals. This is the first report of in vivo application of a Dz to control a virus infection in an animal model.

Gene therapy targeting kidney diseases: routes and vehicles

Renal gene therapy may offer new strategies to treat diseases of native and transplanted kidneys. Several experimental techniques have been developed and employed using nonviral, viral, and cellular vectors. The most efficient viral vector for in vivo transfection appears to be adenovirus. In addition, enhanced naked plasmid techniques, such as the hemagglutinating virus of Japan (HVJ)-liposome method, electroporation, the hydrodynamic method, and ultrasound with microbubbles, are promising. Trapping genetically modified macrophages in the inflamed kidneys is an elegant method for site-specific gene delivery. The choice of delivery vehicle as well as the administration route determines the site of transduction. In conclusion, for both in vivo and ex vivo renal transfection, enhanced naked plasmids, adenoviruses, and modified cell vectors offer the best prospects for effective clinical application. Moreover, the development of safer and nonimmunogenic vectors may realize clinical renal gene therapy in the near future.

Electroporation for targeted gene transfer

The utilisation of nonviral gene delivery methods has been increasing steadily, however, a drawback has been the relative low efficiency of gene transfer with naked DNA compared with viral delivery methods. In vivo electroporation, which has previously been used clinically to deliver chemotherapeutic agents, also enhances the delivery of plasmid DNA and has been used to deliver plasmids to several tissue types, particularly muscle and tumour. Recently, a large number of preclinical studies for a variety of therapeutic modalities have demonstrated the potential of electrically mediated gene transfer. Although clinical trials using gene transfer with in vivo electroporation have not as yet been realised, the tremendous growth of this technology suggests that the first trials will soon be initiated.

Local gene therapy of solid tumors with GM-CSF and B7-1 eradicates both treated and distal tumors

Gene therapy-induced expression of immunostimulatory molecules at tumor cell level may evoke antitumor immune mechanisms by recruiting and enhancing viability of antigen-processing cells and specific tumoricidal lymphocytes. The antitumor efficacy of a plasmid, coding for granulocyte-macrophage colony-stimulating factor (GM-CSF) and the B7-1 costimulatory immune molecule, delivered into growing solid tumors by electroporation was investigated. Murine fibrosarcomas (JBS) growing in Balb/C mice (<or=100 mm3) were transfected with GM-CSF/B7-1-expressing plasmid. Complete tumor regression occurred in greater than 60% of treated animals. This response was systemic, durable and tumor specific, with all responding animals resistant to repeat tumor challenge. Using a liver metastatic model, effective cure of distal metastases was achieved following treatment of the primary subcutaneous tumor. This treatment strategy could be applicable in the clinical setting for effective elimination of both primary tumors and associated metastatic disease.

Transcription factor Ets-1 is essential for mesangial matrix remodeling

Most advanced glomerular diseases are characterized by abnormal extracellular matrix (ECM) accumulation in the glomeruli, and matrix metalloproteinases (MMPs) play a pivotal role in ECM remodeling in various glomerular diseases. The proto-oncogene, ets-1, is a transcription factor regulating the expression of various matrix proteinases, including MMP-1, MMP-3, and MMP-9. The goal of the present study was to characterize the role of Ets-1 in the progression of glomerular diseases. Overexpression of Ets-1 in cultured mesangial cells prevented transforming growth factor (TGF)-beta-induced inhibition of DNA-binding activity and TGF-beta-induced type I collagen production. In addition, exogenous Ets-1 abolished TGF-beta-induced collagen gel contraction. The in vivo transfection of the ets-1 gene into nephritic kidney resulted in the increases in glomerular MMP-1, MMP-3, and MMP-9 mRNA, decreases in mesangial ECM deposition, and attenuation of fibronectin extradomain A (EDA) and type I collagen expression. In contrast, knockdown of Ets-1 in glomeruli resulted in severe ECM deposition in diseased glomeruli. In conclusion, Ets-1 promotes degradation of ECM proteins and is critical for integral glomerular reorganization.

Electric pulse-mediated gene delivery to various animal tissues

Electroporation designates the use of electric pulses to transiently permeabilize the cell membrane. It has been shown that DNA can be transferred to cells through a combined effect of electric pulses causing (1) permeabilization of the cell membrane and (2) an electrophoretic effect on DNA, leading the polyanionic molecule to move toward or across the destabilized membrane. This process is now referred to as DNA electrotransfer or electro gene transfer (EGT). Several studies have shown that EGT can be highly efficient, with low variability both in vitro and in vivo. Furthermore, the area transfected is restricted by the placement of the electrodes, and is thus highly controllable. This has led to an increasing use of the technology to transfer reporter or therapeutic genes to various tissues, as evidenced from the large amount of data accumulated on this new approach for non-viral gene therapy, termed electrogenetherapy (EGT as well). By transfecting cells with a long lifetime, such as muscle fibers, a very long-term expression of genes can be obtained. A great variety of tissues have been transfected successfully, from muscle as the most extensively used, to both soft (e.g., spleen) and hard tissue (e.g., cartilage). It has been shown that therapeutic levels of systemically circulating proteins can be obtained, opening possibilities for using EGT therapeutically. This chapter describes the various aspects of in vivo gene delivery by means of electric pulses, from important issues in methodology to updated results concerning the electrotransfer of reporter and therapeutic genes to different tissues.