Phosphorothioate/methoxyethyl-modified ICAM-1 antisense oligonucleotides improves prevention of ischemic/reperfusion injury

Use of FTY 720 and ICAM-1 antisense oligonucleotides for attenuating chronic renal damage secondary to ischemia-reperfusion injury

INTRODUCTION

Chronic allograft nephropathy is the main cause of graft loss. Although many factors are involved in its development, ischemia-reperfusion injury has received increasing attention as a risk determinant. In a previous study of syngeneic renal transplantation and ischemia, we demonstrated a protective effect of acute damage by FTY 720 and antisense oligonucleotides of ICAM-1 (Oligos). The purpose of the current study was to evaluate the impact of these agents on the development of chronic graft damage in the same model.

METHODS

Lewis rat were used as donors and recipients. The harvested left kidney was kept in Collins solution for 2 hours. Recipient animals received treatment with FTY 720 or Oligos or saline. At 12 and 36 weeks after transplantation, creatinine clearance, GFR, proteinuria, and arterial blood pressure were recorded. Tissue from some animals were submitted for histological studies and quantification of mRNA TGF-beta1.

RESULTS

All groups showed decreased levels of GFR and creatinine clearence, but only the untreated animals showed significant deterioration compared to the pretransplant values (0.53 +/- 0.24 versus 0.21 +/- 0.24 at 36 weeks respectively; P < .05). Proteinuria was also significant in control animals at 36 weeks. Blood pressure showed a moderate increase in all groups. Histological analysis showed that treated animals had fewer signs of chronic damage according to the Banff score. All groups displayed slight increases in TGF-beta1 without differences among them.

CONCLUSIONS

In this model the use of FTY or antisense oligonucleotides of ICAM-1 were associated with less functional and morphological evidence of chronic graft damage secondary to an ischemia-reperfusion injury.

Potential of atelocollagen-mediated systemic antisense therapeutics for inflammatory disease

To study the possibility of using atelocollagen as an oligonucleotide (ODN) delivery carrier in vivo, the activity of formulated antisense ODN targeted against the intercellular adhesion molecule-1 (ICAM-1) mRNA was investigated in an allergic dermatitis model in mice. The allergic dermatitis was elicited in one ear of animals sensitized by treatment with 2,4-dinitrofluorobenzene. Antisense ODN was given to the animals as a single intravenous injection of formulation containing atelocollagen. Antisense activity was determined by measurement of ear thickness, histopathology, and immunohistochemistry 24 hr after the initiation of the dermatitis. Antisense activity was found to increase according to the concentration of atelocollagen in the formulation. The effect mediated by the ODN formulated with 0.05% atelocollagen was more than 50 times greater than that provided by ODN infusion, although the levels of ODN formulated with atelocollagen dropped below that of the 24-hr infusion group within 30 min. The formulated ODN could suppress inflammatory progression by treatment at 8 hr after the ear challenge when inflammation had already commenced at the challenged site. Moreover, antisense activity was noted even when the formulated ODN was injected 3 days before the initiation of inflammation. These data demonstrate that atelocollagen can enhance antisense activity remarkably and that the sustainable antisense activity mediated by the formulation of ODN with atelocollagen could completely change the strategy of antisense therapeutics.

Phase I and phase II safety and efficacy trial of intercellular adhesion molecule-1 antisense oligodeoxynucleotide (ISIS 2302) for the prevention of acute allograft rejection

BACKGROUND

ISIS 2302, an antisense oligonucleotide that inhibits the expression of human intercellular adhesion molecule (ICAM)-1, was evaluated in combination with a cyclosporine (CsA)-prednisone (Pred) regimen first in a phase I safety and pharmacokinetic study and then in a phase II assessment of prophylaxis of acute rejection episodes in deceased donor renal allografts.

METHODS

Both phase I and phase II trials were double-blinded and placebo-controlled, including 17 stable and 39 de novo patients, respectively, in time-lagged, ascending-dose regimens. Each study compared the outcomes of 8 alternate-day intravenous infusions of four ISIS 2302 dose levels (0.05, 0.5, 1.0, or 2.0 mg/kg) versus placebo (3:1 ratio). Patients were followed for 34 days (phase I) or 6 months (phase II). All transplant patients were followed for 3 years.

RESULTS

ISIS 2302 produced no evident toxicity; a significant, dose-related increase in activated partial thromboplastin time was accompanied by a trend toward a decreased platelet count. ISIS 2302 did not alter the pharmacokinetic behavior of CsA. At 6 months, the rates of acute rejection episodes were 38.1% in the ISIS 2302 group versus 20.0% in the placebo group. Three-year graft survivals were similar. The mean creatinine values at 1, 2, and 3 years for all ISIS dose groups combined versus placebo over 3 years showed no significant differences.

CONCLUSIONS

ISIS 2302 did not evoke side-effects and produced slightly improved renal function. However, in this pilot study, it did not further reduce the rate of acute rejection episodes or increase graft survival compared to a concentration-controlled CsA-Pred regimen.

New concepts in organ transplantation

Long-term graft survival is the desired outcome of organ transplantation. The surrogate metric elimination of acute rejection episodes is not only inadequate but also deceptive, since this freedom does not promise long-term graft survival. Current clinical immunosuppressive agents have reduced acute rejection, but not prolonged graft survival. New paradigms in organ transplantation focus on adhesion-migration events using a selectin antagonist, an antisense oligonucleotide, and FTY 720; on peptide or allochimeric antigens on cytokine disruption, and on inhibition of costimulatory signals. Due to the array of adverse reactions to the available immunosuppressive drugs, these new approaches aim not only to augment long-term graft survival, but also minimize the associated toxicities.

Trends in organ preservation

Organ preservation aims to provide a viable graft with primary function post-transplant. The current basis of preservation for transplantation is static cold storage using specific preservation solutions which minimise cellular swelling and membrane pump activity, thus maintaining cellular ATP levels. The current organ shortage and consequent expansion of donor criteria places even greater reliance on minimising graft injury during preservation. This review focuses on current and future advances in preservation technology. The key areas of advance are additives to preservation solutions, alternatives/adjuncts to preservation solutions including perfluorocarbons. A major area of advance is in the modulation of organs during the storage period. This may be achieved by biochemical additives or genetic manipulation. Machine perfusion technology is improving, and this is discussed together with the recent concept of warm (normothermic) perfusion as an alternative means of preservation. The authors provide an overview over the current methods of organ preservation. Cold storage, effective in the short-term is insufficient for marginal organs, does not allow assessment of viability markers, and provokes ischaemic injury. Potential strategies for minimising ischaemic injury include additives to preservation solutions; the two-layer method with perfluorcarbons and UW solution-at present limited to pancreas preservation; organ modulation; organ preconditioning and genetic modification of organs. In particular, the authors illuminate the potential in a reappraisal of the concept of normothermic perfusion.

Effect of tetramethylpyrazine on P-selectin and hepatic/renal ischemia and reperfusion injury in rats

AIM: To investigate the effect of tetramethylpyrazine on hepatic/renal ischemia and reperfusion injury in rats.

METHODS: Hepatic/renal function, histopathological changes, and hepatic/renal P-selectin expression were studied with biochemical measurement and immunohistochemistry in hepatic/renal ischemia and reperfusion injury in rat models.

RESULTS: Hepatic/renal insufficiency and histopathological damage were much less in the tetramethylpyrazine-treated group than those in the saline-treated groups. Hepatic/renal P-selectin expression was down regulated in the tetramethylpyrazine-treated group.

CONCLUSION: P-selectin might mediate neutrophil infiltration and contribute to hepatic/renal ischemia and reperfusion injury. Tetramethylpyrazine might prevent hepatic/renal damage induced by ischemia and reperfusion injury through inhibition of P-selectin.

Prevention of renal ischemic reperfusion injury using FTY 720 and ICAM-1 antisense oligonucleotides

BACKGROUND

Renal damage secondary to ischemia-reperfusion injuries (I-R) is frequent in organ transplantation and adversely affects the graft survival. An important component of this damage is caused by initial adhesion of neutrophils and lymphocytes to endothelial cells. FTY 720, which induces lymphopenia, has previously been shown to display protective effects in models of I-R. The purpose of the present study was to evaluate the combination of FTY 720 and intracellular adhesion molecule and ICAM-1 antisense oligonucleotides (AS-oligos), an agent designed to block the adhesion process.

METHODS

Sprague-Dawley rats underwent syngenic kidney transplantation after donor kidneys had been preserved in cold solution for 2 hours. The treatment groups included: (1) FTY 720 (1 mg/kg) before reperfusion, (2) AS-oligos (2 mg/kg) during kidney perfusion, and (3) the combination of FTY 720 and AS-oligos. All animals were followed daily after transplantation; some were sacrificed on the second day for histologic analysis.

RESULTS

All treated groups showed a maximal serum creatinine that was significantly less than the control (group 1: 2.76 +/- 1.4, group 2: 2.44 +/- 2.05, group 3: 1.51 +/- 0.42, and control: 4.04 +/- 0.5; P <.01) and returned to the basal value earlier. Also, treated animals showed less histologic stigmata of acute tubular damage. FTY 720 and AS-oligos used in combination showed a mild additive effect.

CONCLUSIONS

The use of FTY 720 and/or AS-oligos significantly prevents functional renal damage secondary to I-R, displaying a mild additive effect in this model. Both agents offer the advantage of use during the donor and the graft operations.

The influence of organ donor factors on early allograft function

PURPOSE OF REVIEW

Postischaemic acute renal allograft failure is among the main risk factors for reduced transplant survival. Although new immunosuppressive protocols have reduced the number of acute rejections, the incidence of acute renal failure remained unchanged. On the basis of histomorphology it is not possible to predict donor kidneys at risk of subsequent failure. Some factors are associated with failure, but even combinations of these risk factors can not precisely predict the development of acute renal failure. Studies have therefore evaluated the influence of demographic donor and recipient factors on acute renal failure. New biotechnology and data mining tools are currently being used to study and identify the molecular predictors of acute renal failure.

RECENT FINDINGS

Recent studies showed that donor factors contributed to approximately 40% of the variability in early allograft function. Deductive approaches identified some isolated molecular targets, such as adhesion molecules, as risk factors. Explorative analysis of the entire human genome, however, identified several predictive clusters of genes, which can be functionally grouped into categories such as cell death, stress response, cell adhesion, transcription factors, inflammatory response or cell cycle-related genes. Based on this information, preventative strategies using antisense oligonucleotides or antibodies were adopted. Clinical studies identified the use of catecholamines in the organ donor as beneficial. All these efforts aim to reduce renal tubular damage.

SUMMARY

A detailed analysis of the molecular events and pathways of renal gene expression in the donor and after reperfusion, together with sophisticated data analysis tools, will provide new insights into the pathophysiology of acute renal failure.