Adenovirus-Mediated Antisense-ERK2 Gene Therapy Attenuates Chronic Allograft Nephropathy

Gene therapy research for kidney diseases

A resurgence in the development of newer gene therapy systems has led to recent successes in the treatment of B cell cancers, retinal degeneration and neuromuscular atrophy. Gene therapy offers the ability to treat the patient at the root cause of their malady by restoring normal gene function and arresting the pathological progression of their genetic disease. The current standard of care for most genetic diseases is based upon the symptomatic treatment with polypharmacy while minimizing any potential adverse effects attributed to the off-target and drug-drug interactions on the target or other organs. In the kidney, however, the development of gene therapy modifications to specific renal cells has lagged far behind those in other organ systems. Some positive strides in the past few years provide continued enthusiasm to invest the time and effort in the development of new gene therapy vectors for medical intervention to treat kidney diseases. This mini-review will systematically describe the pros and cons of the most commonly tested gene therapy vector systems derived from adenovirus, retrovirus, and adeno-associated virus and provide insight about their potential utility as a therapy for various types of genetic diseases in the kidney.

Local gene therapy with indoleamine 2,3-dioxygenase protects against development of transplant vasculopathy in chronic kidney transplant dysfunction

Chronic transplant dysfunction (CTD) is the primary cause of late allograft loss in kidney transplantation. Indoleamine 2,3-dioxygenase (IDO) is involved in fetomaternal tolerance and IDO gene therapy inhibits acute rejection following kidney transplantation. The aim of this study is to investigate whether gene therapy with IDO is able to attenuate CTD. Transplantation was performed in a rat Dark-Agouti to Wistar-Furth CTD model. Donor kidneys were incubated either with an adenovirus carrying IDO gene, a control adenovirus or saline. During the first 10 days recipients received low-dose cyclosporine. Body weight, blood pressure, serum creatinine and proteinuria were measured every 2 weeks. Rats were killed after 12 weeks. IDO had a striking beneficial effect on transplant vasculopathy at week 12. It also significantly improved body weight gain; it reduced blood pressure and decreased proteinuria during the follow-up. However, it did not affect the kidney function. In addition, IDO therapy significantly decreased the number of graft-infiltrating macrophages at week 12. The messenger RNA levels of forkhead box p3 and transforming grow factor-β were elevated in the IDO treated group at week 12. Here we show for first time a clear beneficial effect of local IDO gene therapy especially on transplant vasculopathy in a rat model of renal CTD.

Preservation strategies to reduce ischemic injury in kidney transplantation: pharmacological and genetic approaches

PURPOSE OF REVIEW

In the current graft shortage, it is paramount to improve the quality of transplanted organs. Organ preservation represents an underused therapeutic window with great potential to reduce ischaemia-reperfusion injury (IRI) and improve graft quality. Herein, we review strategies using this window as well as other promising work targeting IRI pathways using pharmacological treatments and gene therapy.

RECENT FINDINGS

We highlight studies using molecules administered during kidney preservation to target key components of IRI such as inflammation, oxidative stress, mitochondrial activity and the coagulation pathway. We further expose recent studies of gene therapy directed against inflammation or apoptosis during cold storage. Other pathways with potential therapeutic molecules are cited.

SUMMARY

The use of cold preservation as a therapeutic window to deliver pharmacological or gene therapy treatments can significantly improve both short-term and long-term graft outcomes. Even if human gene therapy remains hampered by the quantity of agent needed and the potential harmfulness of the vector, it clearly offers a wide array of possibilities for the future. Although gene therapy is still too immature, we expose pharmacological strategies which can readily be applied to the clinic and improve both transplantation success rates and the patients' quality of life.

Hydroxyethyl starch-based preservation solutions enhance gene therapy vector delivery under hypothermic conditions

Isolated liver perfusion offers a unique prospect for safe, effective targeting of gene therapies that can be directed against allograft rejection or recurrent diseases such as reinfection by hepatitis C virus (HCV). We aimed to examine the effect of organ preservation solutions on vector-based gene therapy delivery under hypothermic conditions. University of Wisconsin (UW) solution, histidine tryptophan ketoglutarate (HTK), EloHaes, sodium-poly(ethylene glycol)-UW solution [Institut Georges Lopez 1 solution (IGL-1)], and Dulbecco's modified Eagle's medium (DMEM) culture medium (control) were tested at 2 degrees C or 37 degrees C for lentiviral vector transduction efficiencies to the hepatoma cell line Huh-7 and primary human or mouse hepatocytes. Lentiviral vectors expressing short hairpin RNA were used to target HCV replication. With a potent short hairpin RNA vector, transductions were directly correlated to the therapeutic effect, with low transduction yielding low knockdown and vice versa. Green fluorescent protein (GFP) reporter gene expression was observed with vector incubation times as short as 10 minutes. The highest transductions were seen, after 2-hour 37 degrees C incubation, in UW (62% +/- 6 SEM); they were significantly higher than those in HTK (21% +/- 7 SEM). Neither adenosine nor glutathione, present in UW, provided any increase in transduction when supplemented to HTK, although the addition of hydroxyethyl starch (HES) significantly improved transductions. To rule out size exclusion as a mechanism of HES, IGL-1 was tested but did not result in better transductions than HTK or DMEM. When supplemented to UW, anionic compounds reduced transduction, and this indicated a charge interaction mechanism of HES. In conclusion, this study demonstrates that effective vector delivery can be achieved under conditions of hypothermic liver perfusion. UW provides superior transduction to hepatocytes over nonstarch solutions.

Extracellular signal-regulated kinase activation mediates mitochondrial dysfunction and necrosis induced by hydrogen peroxide in renal proximal tubular cells

Although tubular necrosis in acute renal failure is associated with excessive production of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), the mechanism of ROS-induced cell necrosis remains poorly understood. In this study, we examined the role of the extracellular signaling-regulated kinase (ERK) pathway in H2O2-induced necrosis of renal proximal tubular cells (RPTC) in primary culture. Exposure of 60 to 70% confluent RPTC to 1 mM H2O2 for 3 h resulted in 44% necrotic cell death, as measured by trypan blue uptake, and inactivation of mitogen-activated protein kinase kinase (MEK), the upstream activator of ERK, by either 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene (U0126) or 2-(2'-amino-3'-methoxyphenyl)-oxanaphthalen-4-one (PD98059) or overexpression of dominant-negative mutant of MEK1, inhibited cell death. In contrast, overexpression of active MEK1 enhanced H2O2-induced cell death. H2O2 treatment led to the loss of mitochondrial membrane potential (MMP) in RPTC, which was decreased by U0126 and PD98059. Furthermore, inhibition of the MEK/ERK pathway decreased oxidant-mediated ERK1/2 activation and mitochondrial swelling in isolated renal cortex mitochondria. However, treatment with cyclosporin A (CsA), a mitochondrial permeability transition blocker, did not suppress RPTC necrotic cell death, loss of MMP, and mitochondrial swelling. We suggest that ERK is a critical mediator of mitochondrial dysfunction and necrotic cell death of renal epithelial cells following oxidant injury. Oxidant-induced necrotic cell death was mediated by a CsA-insensitive loss of MMP that is regulated by the ERK pathway.

Antisense extracellular signal-regulated kinase-2 gene therapy inhibits platelet-derived growth factor-induced proliferation, migration and transforming growth factor-beta(1) expression in vascular smooth muscle cells and attenuates transplant vasculopathy

Platelet-derived growth factor-BB (PDGF-BB) enables vascular smooth muscle cells (VSMCs) to proliferate, migrate and secrete connective tissue matrix, which are critical events in transplant vasculopathy. However, little is known about the intracellular pathways that mediate these biologic responses of VSMCs. Extracellular signal-regulated kinase (ERK) pathway plays a major role in cellular responses and vascular diseases. In this study, we observed that the inhibition of ERK2 activity by recombinant adenovirus encoding antisense ERK2 (Adanti-ERK2) significantly suppressed the proliferation, converting of cell cycle from G(1) phase to S phase and directed migration, and partially abrogated transforming growth factor-beta(1) (TGF-beta(1)) expression in VSMCs stimulated with PDGF-BB. Ex vivo gene transfer of Adanti-ERK2 into rat aortic allograft attenuated chronic transplant vasculopathy by the inhibition of VSMC proliferation and migration. In conclusion, ERK2 is involved in PDGF-BB-induced VSMCs proliferation, migration and TGF-beta(1) expression and may be a potential therapeutic target for transplant vasculopathy.

Extracellular signal-regulated kinase activation during renal ischemia/reperfusion mediates focal adhesion dissolution and renal injury

Acute renal failure due to ischemia/reperfusion involves disruption of integrin-mediated cellular adhesion and activation of the extracellular signal-regulated kinase (ERK) pathway. The dynamics of focal adhesion organization and phosphorylation during ischemia/reperfusion in relation to ERK activation are unknown. In control kidneys, protein tyrosine-rich focal adhesions, containing focal adhesion kinase, paxillin, and talin, were present at the basolateral membrane of tubular cells and colocalized with short F-actin stress fibers. Unilateral renal ischemia/reperfusion caused a reversible protein dephosphorylation and loss of focal adhesions. The focal adhesion protein phosphorylation rebounded in a biphasic manner, in association with increased focal adhesion kinase, Src, and paxillin tyrosine phosphorylation. Preceding phosphorylation of these focal adhesion proteins, reperfusion caused increased phosphorylation of ERK. The specific mitogen-activated protein kinase kinase 1/2 inhibitor U0126 prevented ERK activation and attenuated focal adhesion kinase, paxillin, and Src phosphorylation, focal adhesion restructuring, and ischemia/reperfusion-induced renal injury. We propose a model whereby ERK activation enhanced protein tyrosine phosphorylation during ischemia/reperfusion, thereby driving the dynamic dissolution and restructuring of focal adhesions and F-actin cytoskeleton during reperfusion and renal injury.