Gene transfer-induced local heme oxygenase-1 overexpression protects rat kidney transplants from ischemia/reperfusion injury

Heme oxygenase-1 (HO-1) overexpression using gene transfer protects rat livers against ischemia/reperfusion (I/R) injury. This study evaluates the effects of Ad-HO-1 gene transfer in a rat renal isograft model. Donor LEW kidneys were perfused with Ad-HO-1, Ad-beta-gal, or PBS, stored at 4 degrees C for 24 h, and transplanted orthotopically into LEW recipients, followed by contralateral native nephrectomy. Serum creatinine, urine protein/creatinine ratios, severity of histologic changes, HO-1 mRNA/protein expression, and HO enzymatic activity were analyzed. Ad-HO-1 gene transfer conferred a survival advantage when compared with PBS- and Ad-beta-gal-treated controls, with median survival of 100, 7, and 7 d, respectively (P < 0.01). Serum creatinine levels were elevated at day 7 in all groups (range, 2.2 to 5.8 mg/dl) but recovered to 1.0 mg/dl by day 14 (P < 0.01) in Ad-HO-1 group, which was sustained thereafter. Urine protein/creatinine ratio at day 7 was elevated in both PBS and Ad-beta-gal, as compared with the Ad-HO-1 group (12.0 and 9.8 versus 5.0; P < 0.005); histologically, ATN and glomerulosclerosis was more severe in Ad-beta-gal group at all time points. Reverse transcriptase-PCR-based HO-1 gene expression was significantly increased before reperfusion (P < 0.001) and remained increased in the Ad-HO-1-treated group for 3 d after transplantation. Concomitantly, HO enzymatic activity was increased at transplantation and at 3 d posttransplant in the Ad-HO-1 group, compared with Ad-beta-gal controls (P < 0.05); tubular HO-1 expression was discernible early posttransplant in the Ad-HO-1 group alone. These findings are consistent with protective effects of HO-1 overexpression using a gene transfer approach against severe renal I/R injury, with reduced mortality and attenuation of tissue injury.

Diagnosis and treatment of acute tubular necrosis

BACKGROUND

Acute tubular necrosis (ATN) is common in hospitalized patients, particularly in the intensive care unit. Over the past four decades, the mortality rate from ATN has remained at 50% to 80%.

PURPOSE

To review recent studies of diagnosis and treatment strategies for ATN.

DATA SOURCES

MEDLINE search for all clinical studies of therapies for ATN, supplemented by a review of the references of the identified articles.

STUDY SELECTION

Prospective studies and major retrospective studies evaluating therapies for ATN.

DATA EXTRACTION

Data on the study sample, interventions performed, results, side effects, and duration of follow-up.

DATA SYNTHESIS

Early diagnosis of ATN by exclusion of prerenal and postrenal causes of acute renal failure, examination of urinary sediment, and analysis of urine measures (for example, fractional excretion of sodium in the absence of diuretics) can allow the early involvement of nephrologists and improve survival. Enteral rather than parenteral hyperalimentation in severely malnourished patients may improve survival. Sepsis causes 30% to 70% of deaths in patients with ATN; therefore, avoidance of intravenous lines, bladder catheters, and respirators is recommended. Because septic patients are vasodilated, large volumes of administered fluid accumulate in the lung interstitium of these patients. This condition necessitates ventilatory support, which when prolonged leads to acute respiratory distress syndrome, multiorgan failure, and increased mortality. More aggressive dialysis (for example, given daily) with biocompatible membranes may improve survival in some patients with acute renal failure.

CONCLUSIONS

New information about the importance of early diagnosis and supportive care for patients with ATN has emerged. However, randomized trials of these interventions are needed to test their effect on the morbidity and mortality of ATN.

Acute renal failure in hospitalized patients

Distinguishing among the three categories of acute renal failure is important, as the evaluation and management are tailored to the particular cause. Most cases are due to acute tubular necrosis. To minimize the risk, we should give hospital patients adequate hydration, use potentially nephrotoxic drugs with caution, keep the use of radiographic contrast agents to a minimum, and give patients at risk a nonionic instead of ionic contrast agent when undergoing radiographic procedures.

Apoptotic cell death in renal injury: the rationale for intervention

Cell number abnormalities are frequent in renal diseases, and range from the hypercellularity of postinfectious glomerulonephritis to the cell depletion of chronic renal atrophy. Recent research has shown that apoptosis and its regulatory mechanisms contribute to cell number regulation in the kidney. The potential role of apoptosis ranges from induction and progression to repair of renal injury. Death ligands and receptors, such as tumor necrosis factor and Fas ligand, proapoptotic and antiapoptotic Bcl2 family members and caspases have all been shown to participate in apoptosis regulation in the course of renal cell injury. However, the precise role of these proteins is unclear, and the participation of most known apoptosis regulatory proteins has not been studied. We now review the role of apoptosis in renal injury, the potential molecular targets of therapeutic intervention, the therapeutic weapons to modulate the activity of these targets and the few examples of therapeutic intervention on apoptosis, with emphasis on the acute tubular necrosis.

Severity of illness scores and the outcome of acute tubular necrosis

The outcome of patients with acute renal failure (ARF) due to acute tubular necrosis (ATN) was evaluated in this study. Two hundred and twenty-two patients with a mean age of 55.1+/-17.7 years (range 19-97 years; male 153, female 69) who developed ATN in the period from July 1991 through January 1997 were studied. Patients were divided into four groups according to their APACHE II scores at the time of the diagnosis of ATN. Group I included patients with an APACHE II score of 14 or less (n = 70), Group II with a score of 15-18 (n = 52), Group III with a score of 19-23 (n = 58), and group IV with a score of 24 or above (n = 42). The mean APACHE II score for each of the four study groups was 11+/-0.4, 16+/-0.2, 20+/-0.2, and 29+/-0.7, respectively. Patient survival was evaluated by the Kaplan-Meier analysis with censorship at 12 months. Survival rates at 180 days were 67%, 47%, 39%, and zero%, for group I through IV respectively, chi2 = 27.99, p < 0.0001, with a median survival of >365, 120, 31, and 11 days, for groups I through IV, respectively. For patients with oliguria (n = 88) survival at 180 days was 23% vs. 58% for patients without oliguria (n = 134), p < 0.0001, median survival 13 vs. 364 d. Six months survival of those who required dialysis (n = 79) was 25% vs. 58% for those whom dialysis was not needed (n = 143), p = 0.001, median survival 15 vs. 364 d, respectively. In patients with sepsis (n = 58), 6 months survival was 35% vs. 50% for those without sepsis (n = 164), p = 0.013, median survival 14 vs. 169 d. In patients who required mechanical ventilation (n = 72), 6 months survival was 17% vs. 62% for those who did not need respiratory support (n = 150), p = 0.0001, median survival 13 vs. > 365 d, respectively. Finally, 6 months survival in patients with one (kidney only), two, three, and four organ failure was 76, 30, 11, and zero percent, respectively, p = 0.0001, median survival >365, 16, 11, and 12 days, respectively. We conclude that the use of the APACHE II score for the stratification of the severity of illness could be of clinical utility in predicting mortality in patients with ATN. Other predictors of poor prognosis include the need for dialysis, the presence of oliguria, the need for mechanical ventilation, the presence of sepsis, and the number of failed organs.

Incidental recognition of left subclavian vein obstruction on renal scintigraphy

In a renal transplant recipient with persistently poor graft function, the flow phase of a renal scan incidentally revealed multiple venous collaterals with focally increased vascular activity near the left lobe of the liver (quadrate lobe). This was initially assumed to represent superior vena cava (SVC) obstruction. A renal biopsy was contemplated to exclude acute rejection because of a nondiagnostic flow phase (loss of a bolus effect). However, because the possibility of venous obstruction at the level of the subclavian and/or brachiocephalic veins (without involving the SVC) also existed, another renal scan was performed, with injection of radiotracer into the contralateral arm. This showed a patent SVC and reasonably preserved renal perfusion consistent with acute tubular necrosis. Subsequently, left subclavian vein obstruction was identified. The graft function improved with conservative management for acute tubular necrosis. These findings illustrate the danger of considering only SVC obstruction when collateral flow patterns and focal hot spots in the liver are present.

Acute tubular necrosis due to captopril

Angiotensin-converting enzyme (ACE) inhibitors are standard therapy for congestive cardiac failure. ACE inhibitors have been used worldwide and are usually safe and have relatively few side effects. Hypotension can develop with the first dose of captopril and can lead to symptomatic renal hypoperfusion with subsequent acute renal failure (ARF). The case of a 65-year-old patient with congestive heart failure who developed acute renal failure following the first dose of captopril is described. He required hemodialysis for 8 weeks for the improvement of his renal function and urinary output. The renal biopsy confirmed the presence of acute tubular necrosis. The reversibility of captopril-induced ARF is confirmed and the patient made an uneventful recovery. An immunoallergic mechanism is not thought to have been responsible for this adverse effect. It is advised that caution should be exerted in giving ACE inhibitors to elderly patients with congestive heart failure, particularly if they are on diuretics. Routine biochemical monitoring is suggested before and during captopril therapy.

Acute tubular necrosis in patients with diabetes mellitus

We compared the clinical outcomes of patients with (n = 71) and without (n = 185) diabetes mellitus enrolled into the placebo arm of a large, multicenter clinical trial of patients with acute tubular necrosis (ATN). Compared with the nondiabetic patients, diabetic patients were older (65.5 +/- 12.9 versus 60.7 +/- 18.0 years, P < 0. 05), had higher usual serum creatinine concentration (1.7 +/- 0.6 versus 1.4 +/- 0.5 mg/dL, P < 0.001), and had a higher prevalence of underlying hypertension, coronary artery disease, and congestive heart failure (all P < 0.007). By day 21 after enrollment, neither mortality nor dialysis-free survival was different between the groups. Length of stay for surviving patients, in both the intensive care unit and the hospital, were significantly shorter for the diabetics. Among acute comorbidities predicting mortality or the need for dialysis, sepsis was more prevalent among the nondiabetic patients (18% versus 35%, diabetics versus nondiabetics, P < 0.05). In conclusion, clinical outcomes for diabetic patients with ATN were no worse than for nondiabetic patients, despite their older age and worse underlying renal function. Patients with diabetes mellitus had more chronic cardiovascular disease but were less acutely ill. We speculate that cardiovascular disease is a risk factor for ATN in patients with diabetes mellitus. These results fail to implicate the increasing prevalence of diabetes mellitus in the persistently poor prognosis of patients with ATN.

Spontaneous renal allograft rupture attributed to acute tubular necrosis

A renal allograft recipient receiving triple immunosuppressive therapy developed spontaneous allograft rupture 5 days after her second cadaveric renal transplantation. Renal biopsy showed interstitial edema with severe acute tubular necrosis (ATN). There was no evidence of acute rejection or renal vein thrombosis. The ruptured renal graft was salvaged by an aggressive fluid resuscitation therapy and surgical hemostasis. The renal function was satisfactory on discharge. We conclude that renal allograft rupture can be the result of interstitial edema solely attributed to ATN in the absence of graft rejection. The ruptured graft kidney is potentially salvageable for those patients whose hemodynamic status can be stabilized by appropriate supportive therapy.

31P-magnetic resonance spectroscopy (31P-MRS) of human allografts after renal transplantation

BACKGROUND

31P-Magnetic resonance spectroscopy (31P-MRS) can be used as a non-invasive tool for measuring the relative intracellular concentrations of several phosphorus metabolites in different organs. Various pathological conditions are characterized by different metabolic patterns. We studied the value of 31P-MRS after renal transplantation with both an uneventful and a clinically complicated course.

METHODS

We determined the relative concentrations of phosphate-containing metabolites in renal allografts of humans with 31P-MRS (1.5 Tesla) in the first few weeks after transplantation; 18 patients with an uneventful clinical course and 10 patients who required dialysis after transplantation were examined. Six patients with a stable allograft function 2-3 months after transplantation served as controls.

RESULTS

In patients with primary allograft function, we found a significant correlation between the phosphomonoester/phosphodiester-ratio (PME/PDE) (r = 0.66, r < 0.01) and the time after transplantation, but no correlation between the nucleoside triphosphate (beta-NTP)-concentration (r = -0.11) and the time course. In the patients with primary or early allograft dysfunction caused by histologically proven rejection (n=5), we found a low beta-NTP compared to patients with an uncomplicated clinical course (0.09+/-0.01 vs 0.15+/-0.03), but no differences in the PME/PDE ratio (0.73+/-0.21 vs 0.80+/-0.21). In contrast, the PME/PDE ratio was lowered in three patients with delayed graft function caused by acute tubular necrosis (0.45+/-0.07 vs 0.80+/-0.21), but the beta-NTP concentration was not reduced (0.15+/-0.003 vs 0.15+/-0.03). The 31P-MR spectrum of two patients with cyclosporin A damage was not altered compared to the controls.

CONCLUSIONS

31P-MRS can be used in patients in the early period after renal transplantation. A significant correlation between the PME/PDE ratio and the time course but no change in the beta-NTP concentration was found in patients with primary allograft function in the first 4 weeks after renal transplantation. Different patterns of 31P-MR spectra were observed depending on the different causes of primary and early transplant dysfunction.

Acute renal failure. Focus on advances in acute tubular necrosis

This article has reviewed the most recent thoughts and findings on the pathophysiology and care of ARF. Clearly, we still have much to learn, but an updated practitioner is necessary in order to meet the challenges of this complex disease, as we search for tomorrow's answers.

Use of diuretics in the acute care setting

The use of diuretics in the acute care setting (intensive care units, operating rooms and emergency departments) is an area of significant clinical and laboratory research. These agents are frequently used to facilitate fluid management and in the hopes of protecting the kidneys from injury. The pros and cons of continuous infusion of loop diuretics, and albumin supplementation are discussed along with the issues related to their use to avoid dialysis or to improve outcome. In addition, the evidences is support of the use diuretics to prevent or treat acute failure in the acute care setting are reviewed and discussed.

Acute renal failure after massive ingestion of gliclazide in a suicide attempt

Gliclazide, a sulfonlyurea class molecule, is used to control glycaemic levels in non-insulin-dependent diabetes mellitus. Acute and chronic toxicity studies, conducted in various animal species, have demonstrated a very low toxicity. We report a patient who developed acute renal failure due to acute tubular necrosis following a massive ingestion of gliclazide in an suicide attempt. The patient ingested 28 grams of gliclazide; the normal dose of gliclazide is 80 mg one or twice a day. At admission the patient was hypoglycaemia and in a few days became oliguric with an increase in the serum creatinine concentration, but with a normal blood urea nitrogen level. He underwent dialysis and ten days after ingestion of gliclazide, his renal function improved rapidly.

Predictors of mortality and the provision of dialysis in patients with acute tubular necrosis. The Auriculin Anaritide Acute Renal Failure Study Group

To explore the natural history of critically ill patients with acute renal failure due to acute tubular necrosis, we evaluated 256 patients enrolled in the placebo arm of a randomized clinical trial. Death and the composite outcome, death or the provision of dialysis, were determined with follow-up to 60 d. The relative risks (RR) and 95% confidence intervals (95% CI) associated with routinely available demographic, clinical, and laboratory variables were estimated using proportional hazards regression. Ninety-three (36%) deaths were documented; an additional 52 (20%) patients who survived received dialysis. Predictors of mortality included male gender (RR, 2.01; 95% CI, 1.21 to 3.36), oliguria (RR, 2.25; 95% CI, 1.43 to 3.55), mechanical ventilation (RR, 1.86; 95% CI, 1.18 to 2.93), acute myocardial infarction (RR, 3.14; 95% CI, 1.85 to 5.31), acute stroke or seizure (RR, 3.08; 95% CI, 1.56 to 6.06), chronic immunosuppression (RR, 2.37; 95% CI, 1.16 to 4.88), hyperbilirubinemia (RR, 1.06; 95% CI, 1.03 to 1.08 per 1 mg/dl increase in total bilirubin) and metabolic acidosis (RR, 0.95; 95% CI, 0.90 to 0.99 per 1 mEq/L increase in serum bicarbonate concentration). Predictors of death or the provision of dialysis were oliguria (RR, 5.95; 95% CI, 3.96 to 8.95), mechanical ventilation (RR, 1.53; 95% CI, 1.07 to 2.21), acute myocardial infarction (RR, 1.95; 95% CI, 1.24 to 3.07), arrhythmia (RR, 1.51; 95% CI, 1.04 to 2.19), and hypoalbuminemia (RR, 0.56; 95% CI, 0.42 to 0.74 per 1 g/dl increase in serum albumin concentration). Neither mortality nor the provision of dialysis was related to patient age. These observations can be used to estimate risk early in the course of acute tubular necrosis. Furthermore, these and related models may be used to adjust for case-mix variation in quality improvement efforts, and to objectively stratify patients in future intervention trials aimed at favorably altering the course of hospital-acquired acute renal failure.

The bioartificial renal tubule assist device to enhance CRRT in acute renal failure

Current therapy for acute tubular necrosis (ATN) continues to have an exceedingly high mortality rate, exceeding 50% even with dialytic or hemofiltrative support. Current renal replacement therapy in ATN only substitutes for filtration function of the kidney but not its cellular metabolic functions. Replacing these metabolic functions may optimize current therapy for this devastating disease process. In this regard, a renal tubule assist device (RAD) has been developed to be placed in an extracorporeal continuous hemoperfusion circuit in series with a hemofilter. The RAD consists of porcine renal proximal tubule cells grown as confluent monolayers of a multifiber bioreactor with a membrane surface area from 0.4 to 1.6 m2. The cells along the inner surface of the hollow fibers are immunoprotected from the patient's blood by the hollow fiber membrane. In preliminary experiments in uremic dogs, this device has been shown to tolerate a uremic environment while providing reabsorptive, metabolic, and endocrinologic activity. Pilot human trials of the RAD are anticipated within the next year to improve current renal replacement therapy in ATN.

Early haemodialysis in acute tubular necrosis

The study was conducted in 35 cases of acute tubular necrosis of varied aetiology. Cases were divided in 2 groups, Group A--17 cases treated conservatively and Group B--18 cases managed by early haemodialysis. Criteria for early haemodialysis were blood urea < 120 mg% and serum creatinine < 7 mg%. Before starting therapy both the groups had comparable biochemical and renal parameters (p > 0.05). Overall mortality was lower in Group B as compared to Group A (22.2% Vs 29.4). Complication events such as uraemic encephalopathy, pulmonary oedema, haematemesis and malena, thrombophlebitis and vomiting were significantly lower in Group B (p < 0.05). Hospital stay was also significantly lower (p < 0.05) in Group B (18 +/- 2.5 days Vs 28 +/- 3 days), this can reduce the cost of treatment also.

A practical approach to acute renal failure

Acute renal failure represents a wide variety of renal diseases, which may be challenging to diagnose and even more challenging to treat. As understanding of these diseases improves, so perhaps will clinicians' ability to treat them.

Anaritide in acute tubular necrosis. Auriculin Anaritide Acute Renal Failure Study Group

BACKGROUND

Atrial natriuretic peptide, a hormone synthesized by the cardiac atria, increases the glomerular filtration rate by dilating afferent arterioles while constricting efferent arterioles. It has been shown to improve glomerular filtration, urinary output, and renal histopathology in laboratory animals with acute renal dysfunction. Anaritide is a 25-amino-acid synthetic form of atrial natriuretic peptide.

METHODS

We conducted a multicenter, randomized, double-blind, placebo-controlled clinical trial of anaritide in 504 critically ill patients with acute tubular necrosis. The patients received a 24-hour intravenous infusion of either anaritide (0.2 microgram per kilogram of body weight per minute) or placebo. The primary end point was dialysis-free survival for 21 days after treatment. Other end points included the need for dialysis, changes in the serum creatinine concentration, and mortality.

RESULTS

The rate of dialysis-free survival was 47 percent in the placebo group and 43 percent in the anaritide group (P = 0.35). In the prospectively defined subgroup of 120 patients with oliguria (urinary output, < 400 ml per day), dialysis-free survival was 8 percent in the placebo group (5 of 60 patients) and 27 percent in the anaritide group (16 of 60 patients, P = 0.008). Anaritide-treated patients with oliguria who no longer had oliguria after treatment benefited the most. Conversely, among the 378 patients without oliguria, dialysis-free survival was 59 percent in the placebo group (116 of 195 patients) and 48 percent in the anaritide group (88 of 183 patients, P = 0.03).

CONCLUSIONS

The administration of anaritide did not improve the overall rate of dialysis-free survival in critically ill patients with acute tubular necrosis. However, anaritide may improve dialysis-free survival in patients with oliguria and may worsen it in patients without oliguria who have acute tubular necrosis.

Biocompatible dialysis membranes and acute renal failure: a study in post-operative acute tubular necrosis in cadaveric renal transplant recipients

Previous experimental and human data suggests a detrimental effect on the course of acute renal failure related to exposure of blood to artificial dialysis membranes of poor biocompatibility. We performed a 2.5-year prospective randomized trial to compare the clinical course of acute renal failure (post-operative ischemic acute tubular necrosis, ATN) in patients receiving a cadaveric renal transplant requiring supportive hemodialysis in the immediate post-transplant setting. Patients were randomized to either a cuprophane or polymethylmethacrylate (PMMA) conventional hollow fiber dialyzer. All patients received a standard immunosuppressive regimen which included induction therapy with either horse anti-thymocyte gamma globulin (ATGAM) or the murine anti-CD3 monoclonal antibody (OKT3). Of 53 patients randomized, 17 were excluded (2 for intervening biopsy-proven rejection prior to recovery from ATN, 10 for primary graft nonfunction and 5 for other reasons), leaving 36 evaluable cases of uncomplicated ATN, 18 in each group. There was no difference by age, race, gender, cause of ESRD, immunosuppressive regimen, cold or warm ischemia time, use of pre-transplant dialysis, percent oliguria or the incidence of intra-dialytic hypotension between the 2 groups. There was no difference in the mean time to recovery from ATN posttransplant (8.9 days in the cuprophane group vs 9.5 days in the PMMA group, p = NS) or in the average number of hemodialysis treatments required (3.6 in both groups, p = NS). There was also no difference in long term allograft outcome in terms of the nadir serum creatinine, the number of episodes of subsequent acute rejection or in the development of chronic rejection. An intent-to-treat analysis of all 53 originally randomized patients similarly yielded no significant differences. A subsequent, non-randomized study using a membrane of intermediate biocompatibility (Hemophan) also showed no difference in recovery time from ATN. Bioincompatible membranes do not seem to have a significant clinical impact on the course of recovery of this form of acute renal failure. The striking benefits of biocompatibility in the course of ARF seen in other human trials may relate more to the non-renal systemic toxic effects of bioincompatibility.