Hypothermic injury: the mitochondrial calcium, ATP and ROS love-hate triangle out of balance.

BACKGROUND/AIMS: Catecholamines prevent hypothermic cell death which accounts for severe tissue damage and impaired allograft function after prolonged organ preservation. Here, we identified cellular processes which govern hypothermia-mediated cell death in endothelial cells and how they are influenced by dopamine. METHODS: Lactate dehydrogenase assay, intracellular ATP, reactive oxygen species and reduced thio-group measurement, intracellular calcium measurement and mitochondrial calcium staining were performed in the study. RESULTS: Intracellular ATP was almost completely depleted within 12 hrs of hypothermic preservation in untreated human umbilical vein endothelial cells (HUVEC), while dopamine pre-treatment significantly delayed ATP depletion. 4 hrs after hypothermia a redox imbalance was observed in untreated cells, which increased with the duration of hypothermia. The redox imbalance was primarily caused by depletion of SH reduction equivalents and was significantly inhibited by dopamine. In addition, hypothermia-induced Ca(2+) influx and mitochondrial Ca(2+) accumulation were both prevented by dopamine. The protective effect of dopamine was abrogated by ionomycin and sodium azide and partly by oligomycin and CCCP. CONCLUSIONS: Our data demonstrated that loss of intracellular ATP, generation of a redox imbalance and accumulation of intracellular Ca(2+) underlie cold preservation injury. Dopamine improves the redox balance, prevents intracellular Ca(2+) accumulation and delays ATP depletion.

Donor dopamine pretreatment inhibits tubulitis in renal allografts subjected to prolonged cold preservation.

BACKGROUND: In the present study, we used the Brown-Norway (BN) to Lewis model as a model for acute rejection, to test the hypothesis that dopamine (DA) treatment of BN donors significantly reduces the inflammatory response after renal transplantation. METHODS: BN and Lewis rats (isograft controls) were treated for 24 hr with DA (5 microg/kg/min) or NaCl (0.9%), respectively. After 24 hr of cold storage in University of Wisconsin (UW) solution, renal allografts were orthotopically transplanted into Lewis recipients. All recipients received immunosuppression until they were sacrificed. Allografts were harvested one, three, five, and 10 days after transplantation and analyzed by light microscopy, immunohistochemistry (CD3, major histocompatibility complex [MHC] class II, ED1, P-selectin and intercellular adhesion molecule [ICAM]-1) and by RNase protection assay for cytokine mRNA. RESULTS: Ten days after transplantation Banff tubulitis scores were significantly lower in DA-treated than in NaCl-treated allografts. No significant differences were found in Banff interstitial infiltration scores. The numbers of MHC class II+ and CD3+ cells were significantly decreased in DA-treated animals as assessed by immunohistochemistry. No differences were found in the number of ED1+, P-selectin+, and ICAM-1+ cells. The expression of Ltalpha, tumor necrosis factor, interleukin-1beta, and interleukin-2 mRNA was significantly reduced in DA-treated animals. CONCLUSION: Our data indicate that donor DA treatment significantly inhibits tubulitis in renal allografts subjected to prolonged cold preservation. A reduced number of infiltrating MHC class II+ and CD3+ cells together with decreased cytokine expression could diminish renal scarring, reduce allograft immunogenicity, and hence improve transplantation outcome.

Atorvastatin donor pretreatment prevents ischemia/reperfusion injury in renal transplantation in rats: possible role for aldose-reductase inhibition.

BACKGROUND: The aim of the present study was to evaluate the effect of donor pretreatment with atorvastatin on ischemia/reperfusion (I/R) injury in renal transplantation in rats. METHODS: Donor rats were pretreated orally with atorvastatin or vehicle 2 days prior to explantation. Kidneys were stored for 24 hr at 4 degrees C in University of Wisconsin solution and transplanted into isogeneic or allogeneic recipients. RESULTS: Donor treatment with atorvastatin improved initial graft function, reduced renal inflammation, and the number of TUNEL-positive cells in renal tissue after prolonged cold storage and isogeneic transplantation. In the allogeneic transplantation model, donor treatment with atorvastatin reduced renal inflammation in grafts harvested after 5 days, but no improvement of long-term graft survival (24 weeks) could be observed. A genome wide gene expression profile of donor kidneys from atorvastatin treated or vehicle treated rats revealed a fivefold downregulation of aldose reductase in all atorvastatin treated animals (P<0.01). Donor treatment with an aldose-reductase inhibitor improved kidney function and reduced renal inflammation after prolonged cold storage and isogeneic transplantation. CONCLUSION: Our data suggest that downregulation of aldose reductase in renal tissue might underlie the protective effect of donor atorvastatin treatment. Donor pretreatment with a statin or an aldose reductase inhibitor could offer a new treatment strategy to prevent transplantation associated tissue injury.

Carnosine as a protective factor in diabetic nephropathy: association with a leucine repeat of the carnosinase gene CNDP1.

The risk of diabetic nephropathy is partially genetically determined. Diabetic nephropathy is linked to a gene locus on chromosome 18q22.3-q23. We aimed to identify the causative gene on chromosome 18 and to study the mechanism by which the product of this gene could be involved in the development of diabetic nephropathy. DNA polymorphisms were determined in 135 case (diabetic nephropathy) and 107 control (diabetes without nephropathy) subjects. The effect of carnosine on the production of extracellular matrix components and transforming growth factor-beta (TGF-beta) after exposure to 5 and 25 mmol/l d-glucose was studied in cultured human podocytes and mesangial cells, respectively. A trinucleotide repeat in exon 2 of the CNDP1 gene, coding for a leucine repeat in the leader peptide of the carnosinase-1 precursor, was associated with nephropathy. The shortest allelic form (CNDP1 Mannheim) was more common in the absence of nephropathy (P = 0.0028, odds ratio 2.56 [95% CI 1.36-4.84]) and was associated with lower serum carnosinase levels. Carnosine inhibited the increased production of fibronectin and collagen type VI in podocytes and the increased production of TGF-beta in mesangial cells induced by 25 mmol/l glucose. Diabetic patients with the CNDP1 Mannheim variant are less susceptible for nephropathy. Carnosine protects against the adverse effects of high glucose levels on renal cells.

Hypothermia-induced loss of endothelial barrier function is restored after dopamine pretreatment: role of p42/p44 activation.

BACKGROUND: Donor dopamine usage is associated with improved immediate graft function after renal transplantation. Although prolonged cold preservation results in an increased vascular permeability, the present study was conducted to examine in vitro and in vivo if dopamine pretreatment influences endothelial barrier function under such conditions. METHODS: To assess cold preservation injury in vitro and in vivo, cultured human umbilical vein endothelial cells (HUVEC) and Lewis donor rats were pretreated with dopamine or isotonic saline prior to cold storage. Injury was determined by lactate dehydrogenase (LDH) release, histology, and functional analysis. RESULTS: In vitro cold storage resulted in intercellular gap formation in both untreated and dopamine pretreated HUVEC. In the latter monolayer integrity was completely restored upon rewarming and paracellular transport of fluorescein isothiocyanate-dextran was significantly reduced. In dopamine treated HUVEC, intercellular gap formation was independent of cell death and was associated with redistribution of junctional proteins and condensation of cytoskeleton proteins. In untreated HUVEC proteolysis and cell death were clearly evident after hypothermia. Closing of intercellular gaps was dependent on p42/p44 activation. Regeneration of adenosine triphosphate was only observed in dopamine pretreated cells. Only in dopamine treated Lewis renal allografts subjected to cold storage, activation of p42/p44 occurred upon rewarming. These grafts had a better renal function and displayed less inflammatory cells five days after transplantation. CONCLUSION: Our study demonstrates beneficial effects of dopamine treatment on cold storage induced endothelial barrier disturbances. This may contribute to the positive effects of catecholamines on immediate graft function of renal allografts in men.

Tenilsetam prevents early diabetic retinopathy without correcting pericyte loss.

Hyperglycemia-induced mitochondrial overproduction of reactive oxygen species leads to the activation of different biochemical pathways involved in endothelial damage of the diabetic retina. Tenilsetam [(+/-)-3-(2-thienyl)-2-piperazinone] is a dicarbonyl scavenger in the millimolar range and a transition metal ion chelator in the micromolar range. We tested its effect on experimental diabetic retinopathy, and on endothelial cell characteristics in vitro. Streptozotocin diabetic male Wistar rats (60 mg/kg BW) received 50 mg/kg BW tenilsetam (D-T) for 36 weeks, or no treatment (D). The impact of tenilsetam (0-30 mM) on endothelial proliferation, apoptosis, sprouting, cytokine-induced leucocyte-endothelial interaction, and VEGF expression was tested in vitro. Tenilsetam did not affect glycemic control or body weight in diabetic animals. The 3.7 fold increase in acellular capillaries in diabetic rats [p < 0.001 vs. non-diabetic controls (N)] was reduced by 70% (p < 0.001) through treatment, but pericyte loss (D vs. N -33%; p < 0.001) remained unaffected. In vitro, tenilsetam inhibited endothelial proliferation at lower doses, while inducing apoptosis at high doses. Leucocyte adhesion was only inhibited at high doses. Sprouting angiogenesis of bovine retinal endothelial cells was promoted at lower doses (< or = 10 mM). At micromolar concentrations, endothelial VEGF expression was upregulated by 100%. Long-term treatment with the AGE-inhibitor and iron-chelating compound tenilsetam inhibits the formation of acellular capillaries without correcting pericyte loss. The compound has dose-dependent effects on endothelial cell function. These data suggest that, independent of known properties, tenilsetam shows important rescue functions on endothelial cells which could be useful for the treatment of early diabetic retinopathy.

Serial ANCA determinations for monitoring disease activity in patients with ANCA-associated vasculitis: systematic review.

BACKGROUND: Antineutrophil cytoplasmic antibodies (ANCAs) are considered by some investigators to be sensitive markers of disease activity and have been suggested to predict relapse and guide therapeutic decisions. Studies using serial ANCA monitoring in patients with ANCA-associated vasculitis (AASV) have yielded controversial results during the last 15 years. To assess the diagnostic value of serial ANCA testing in the follow-up of patients with AASV, we conducted a systematic review of the available literature. METHODS: Studies were identified by a comprehensive search of the PubMed and BIOSIS+/RRM databases, as well as hand searching. Method quality of all eligible studies was assessed with respect to external and internal validity according to established criteria for diagnostic studies. RESULTS: Twenty-two studies met our inclusion criteria, including a total of 950 patients. Whereas generalizability was not a major problem, assessment of internal validity showed that only a minority of studies reported the combination of consecutive patient recruitment, prospective data collection, and independent determination of both index and reference tests, considered as the ideal for diagnostic test studies. Quantitative meta-analytic calculations were not conducted because of the presence of considerable method heterogeneity. CONCLUSION: The presence of considerable methodological heterogeneity combined with methodological shortcomings with respect to internal validity in the majority of included studies preclude firm conclusions from the available literature concerning the clinical value of serial ANCA determinations for monitoring the follow-up of patients with AASV.

Life-threatening intoxication with methylene bis(thiocyanate): clinical picture and pitfalls. A case report.

BACKGROUND: Methylene bis(thiocyanate) (MBT) is a microbiocidal agent mainly used in industrial water cooling systems and paper mills as an inhibitor of algae, fungi, and bacteria. CASE PRESENTATION: We describe the first case of severe intoxication following inhalation of powder in an industrial worker. Profound cyanosis and respiratory failure caused by severe methemoglobinemia developed within several minutes. Despite immediate admission to the intensive care unit, where mechanical ventilation and hemodialysis for toxin elimination were initiated, multi-organ failure involving liver, kidneys, and lungs developed. While liver failure was leading, the patient was successfully treated with the MARS (molecular adsorbent recirculating system) procedure. CONCLUSION: Intoxication with MBT is a potentially life-threatening intoxication causing severe methemoglobinemia and multi-organ failure. Extracorporeal liver albumin dialysis (MARS) appears to be an effective treatment to allow recovery of hepatic function.

Acetylcysteine for prevention of contrast nephropathy: meta-analysis.

BACKGROUND: Contrast nephropathy is associated with increased in-hospital morbidity and mortality and leads to extension of hospital stay in patients with chronic renal insufficiency. Acetylcysteine seems to be a safe and inexpensive way to reduce contrast nephropathy. We aimed to assess the efficacy of acetylcysteine to prevent contrast nephropathy after administration of radiocontrast media in patients with chronic renal insufficiency. METHODS: We did a meta-analysis of randomised controlled trials comparing acetylcysteine and hydration with hydration alone for preventing contrast nephropathy in patients with chronic renal insufficiency. The trials were identified through a combined search of the BIOSIS+/RRM, MEDLINE, Web of Science, Current Contents Medizin, and The Cochrane Library Databases. We used incidence of contrast nephropathy 48 h after administration of radiocontrast media as an outcome measure. FINDINGS: Seven trials including 805 patients were eligible according to our inclusion criteria and were analysed. Overall incidence of contrast nephropathy varied between 8% and 28%. Since significant heterogeneity was indicated by the Q statistics (p=0.016) we used a random-effects model to combine the data. Compared with periprocedural hydration alone, administration of acetylcysteine and hydration significantly reduced the relative risk of contrast nephropathy by 56% (0.435 [95% CI 0.215-0.879], p=0.02) in patients with chronic renal insufficiency. Meta-regression revealed no significant relation between the relative risk of contrast nephropathy and the volume of radiocontrast media administered or the degree of chronic renal insufficiency before the procedure. INTERPRETATION: Compared with periprocedural hydration alone, acetylcysteine with hydration significantly reduces the risk of contrast nephropathy in patients with chronic renal insufficiency. The relative risk of contrast nephropathy was not related to the amount of radiocontrast media given or to the degree of chronic renal insufficiency before the procedure.

Influence of donor pretreatment with dopamine on allogeneic kidney transplantation after prolonged cold storage in rats.

BACKGROUND: Retrospective transplant database analysis revealed that administration of catecholamines to organ donors reduces acute rejection episodes and improves graft survival after renal transplantation. In the present study, the authors investigated the influence of dopamine donor pretreatment before prolonged cold storage on short- and long-term graft outcome after allogeneic kidney transplantation. METHODS: Fisher donor rats were treated intravenously for 24 hr with dopamine or isotonic saline, Lewis rats treated with saline served as controls. Explanted kidneys were stored for 24 hr at 4 degrees C in University of Wisconsin solution and transplanted into Lewis rats. RESULTS: Dopamine pretreatment markedly reduced the infiltration of monocytes down to the level of isogeneic controls 5 days after allogeneic transplantation and hastened recovery of renal function in the first days after transplantation. After 24 weeks, serum creatinine and proteinuria were significantly lower in recipients of dopamine-treated grafts. Histologically, dopamine donor pretreatment significantly reduced the severity of chronic allograft nephropathy. Survival of animals that underwent transplantation was improved by dopamine pretreatment of donors (P=0.04). CONCLUSIONS: Pretreatment of organ donors with dopamine improves short- and long-term outcome after prolonged cold storage and subsequent allogeneic kidney transplantation in rats. The authors' experimental data demonstrate that donor treatment is a simple and effective approach for preventing long-term graft loss after kidney transplantation.

IgA nephropathy and hodgkin's disease: a rare coincidence. Case report and literature review.

In Hodgkin's disease, the most common paraneoplastic glomerular abnormality is minimal change nephropathy, although other glomerular diseases occasionally have been described. We report a case of extracapillary immunoglobulin A glomerulonephritis presenting as acute renal failure in a woman with newly diagnosed Hodgkin's disease. Treatment with the bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone regimen resulted in complete hematologic and renal remission for more than 1 year after diagnosis.

Modulation of IFN-gamma-induced immunogenicity by phosphatidylethanolamine-linked hyaluronic acid.

BACKGROUND: The present study was conducted to examine the possibility of modulating interferon (IFN-gamma)-induced immunogenicity by a novel compound that is composed of a PLA2 inhibitor linked to hyaluronic acid (HYPE). METHODS: HYPE was tested for its effect on IFN-gamma-induced expression of MHC class I, class II, and intercellular adhesion molecule (ICAM-1) in cultured endothelial and renal proximal tubular cells by flow cytometric analysis (FACS) as well as its ability to influence T cell activation in mixed lymphocyte reaction (MLR) or after mitogen stimulation. RESULTS: In FACS, a profound inhibition in MHC class I and ICAM-1 staining was observed in stimulated or unstimulated cells that were incubated with HYPE. This was not due to down-regulation of antigen expression and only occurred when monoclonal antibodies, but not when polyclonal antibodies, were used. HYPE inhibited the induction of MHC class II in both cell types after IFN-gamma stimulation in a dose-dependent manner. Moreover, the induction of class II transactivator (CIITA) was completely inhibited under these conditions, most likely because it blocked the binding of IFN-gamma to the cell membrane. Addition of HYPE to MLR inhibited the proliferation of T cells and the secretion of interleukin (IL)-2, IFN-gamma, and IL-10. This was not observed when HYPE was added together with anti-CD3 or phytohemagglutinin (PHA). CONCLUSION: Our study provides experimental evidence that HYPE has immunosuppressive features. This makes the compound an interesting candidate as an immunosuppressive drug, not only in organ transplantation, but also in diseases where IFN-gamma is overexpressed.

Modulation of chemokine production and expression of adhesion molecules in renal tubular epithelial and endothelial cells by catecholamines.

BACKGROUND: The present study was conducted to investigate whether catecholamines influence the production of chemokines and adhesion molecules in proximal tubular epithelial cells (PTECs) and endothelial cells. METHODS: PTECs and human umbilical vein endothelial cells (HUVECs) were stimulated with various concentrations of dopamine (DA), adrenaline (AD), or noradrenaline (NA), and the production of interleukin (IL)-8, ENA-78, and Gro-alpha was assessed by ELISA. The influence of catecholamine pretreatment on tumor necrosis factor (TNF)-alpha-mediated production of these chemokines and the expression of adhesion molecules was also tested. RESULTS: In PTECs, DA inhibited the production of all three chemokines in a dose-dependent fashion. Although inhibition in ENA-78 and Gro-alpha production was also found in HUVECs, IL-8 production was up-regulated in these cells. Increased IL-8 secretion was predominantly observed at the apical site of the cells. In AD or NA stimulated cells, the production of Gro-alpha was increased in PTECs and decreased in HUVECs. Down-regulation in IL-8 production was also observed after AD but not after NA stimulation of both cell types. Interestingly, TNF-alpha-mediated up-regulation in intercellular adhesion molecule 1, vascular cell adhesion molecule (VCAM), and E-selectin was delayed in DA-pretreated HUVECs but not in PTECs. The influence of DA, but not AD or NA, on chemokine production was completely prevented by the addition of N-acetylcysteine. CONCLUSIONS: This study demonstrates that catecholamines differentially influence chemokine production and indicates that DA may have anti-inflammatory properties because it delays the expression of adhesion molecules and inhibits the production of chemokines in PTECs and endothelial cells under basal and inflammatory conditions.

Effect of dopamine on inflammatory status in kidneys of brain-dead rats.

BACKGROUND: Brain death has been identified as an independent risk factor for chronic allograft dysfunction. In two independent retrospective clinical studies, we showed that dopamine treatment of brain-dead donors improves long-term kidney graft survival. The mechanisms underlying the protective effects of dopamine treatment in vivo have not been identified. To elucidate the mechanisms underlying the protective effect of dopamine on kidneys of brain-dead donors, we studied a model for brain death in rats. METHODS: In F344 rats, brain death was induced by epidural inflation of a 3F Fogarty catheter. Apneic animals were mechanically ventilated, and clinically relevant dosages of dopamine (2, 6, 10, or 14 microg/kg/min) were given for 6 hr from the onset of brain death. Ventilated, non-brain-dead animals served as controls. RESULTS: Dopamine significantly reduced renal monocyte infiltration and major histocompatibility class II and P-selectin expression in brain-dead animals. It also prevented further up-regulation of the inflammatory markers tumor necrosis factor-alpha and monocyte chemoattractant peptide-1. Concomitantly, the presence of inducible anti-oxidant heme oxygenase-1, known for its cytoprotective effects, was strongly increased by dopamine. CONCLUSION: We identified several mechanisms underlying the protective effects of dopamine treatment on kidney grafts. The identification of these mechanisms may help to design more effective future strategies for treatment of cadaveric kidney donors.

An index for renal outcome in ANCA-associated glomerulonephritis.

BACKGROUND: The aim of this study is to analyze the predictive value of clinical, serological, and histological parameters for renal outcome in antineutrophil cytoplasmic autoantibody (ANCA)-associated glomerulonephritis by multivariate analysis and create an index valid for clinical use. METHODS: Data from 160 patients with Wegener's granulomatosis, microscopic polyangiitis, and idiopathic rapidly progressive glomerulonephritis without immune deposits (renal-limited vasculitis) were collected. The Cockcroft formula was used to assess renal function expressed by glomerular filtration rate (GFR) at the time of renal biopsy (t = 0) and 1 year later (t = 1). Other clinical parameters were age, sex, and diagnosis. ANCA test results were scored as cytoplasmic ANCA/antiproteinase 3 (anti-PR3) or perinuclear ANCA/antimyeloperoxidase (anti-MPO) positive or negative. Histological data included normal glomeruli, fibrinoid necrosis, extracapillary proliferation, granulomas, interstitial edema, focal and diffuse infiltrates, fibrosis, tubular cylinders/casts, tubular atrophy, tubular necrosis, sclerosis, mesangial proliferation, mesangial matrix expansion, arteriosclerosis, and infiltrates in arterioles. In a separate analysis, we explored whether there were histological differences between patients with anti-PR3 and anti-MPO ANCA test results. RESULTS: Forty percent of the variation in renal function at the time of biopsy can be explained by the presence or absence of tubular atrophy, normal glomeruli, fibrinoid necrosis, extracapillary proliferation, and age. Renal function at the time of biopsy is the best predictor for renal function at t = 1 in patients with ANCA-associated glomerulonephritis. Together with normal glomeruli, fibrinoid necrosis, and age, it explains more than 60% of the variation in GFR at t = 1. ANCA subtype has no independent contribution in predicting patient prognosis. Results translated into a clinically relevant index: GFR at t = 1 = 36.96 + 0.65* (GFR at t = 0) + 10.52 (if normal glomeruli present) + 7.72 (if fibrinoid necrosis present) - 0.42* (age). CONCLUSION: The index created with results from this study provides an indication of renal outcome in patients diagnosed with ANCA-associated glomerulonephritis.

Endothelin receptor antagonists: a new therapeutic option for improving the outcome after solid organ transplantation?

Initially described as the most potent vasoconstrictor peptide, endothelin (ET) has also been shown to possess extraordinary immunomodulatory and proinflammatory properties. Because of this broad spectrum of biological activities, a possible role of the ET-system in solid organ transplantation has soon become a focus of research. Several studies demonstrated a pathogenetic involvement of ET in ischemia/reperfusion injury of heart, liver, kidney, and lung grafts. ET accumulates during cold storage of organs and can be detected in the effluent preservation solution. In addition ET is very, likely to play a pivotal role in the development of chronic rejection, which represents the major cause of late allograft loss. Increased expression of components of the ET-system has been described in areas of neointimal proliferation, a hallmark of chronic graft rejection. Both selective ET-A as well as non-selective ET-A/B receptor antagonists improved histomorphological and functional sequelae of chronic rejection. However these data have largely been derived from experimental animal transplantation, and ET receptor blockers have only recently been introduced in clinical medicine. A significant number of investigational drugs are now being tested in humans, with a main focus on cardiovascular diseases, such as congestive heart failure and pulmonary hypertension. First results have markedly dampened the initial enthusiastic vision of ET receptor blockers being organoprotective super-weapons. Thus the clinical potential of ET antagonists in general, and especially in solid-organ transplantation, is still to be defined.

Increased activity of the renal kallikrein-kinin system in autosomal dominant polycystic kidney disease in rats, but not in humans.

The kallikrein-kinin system (KKS) was investigated in autosomal dominant polycystic kidney disease (ADPKD)-affected rats (PKD) and compared to unaffected controls (SD) and 5/6 nephrectomized rats (5/6 Nx). In addition, patients with ADPKD compared to patients with nonpolycystic kidney disease and healthy controls have been investigated. Plasma and urine samples for determination of creatinine, protein, kallikrein (KAL) and bradykinin (BK) were taken in male 3- and 9-month-old PKD, SD and 9-month-old 5/6 Nx. The same parameters were determined in young (age: 20-40 years) and old (41-65 years) male patients with ADPKD and compared to age-matched patients with nonpolycystic kidney disease and age-matched healthy controls. Plasma and urine KAL were measured by chromogenic peptide substrate, and kininswere determined by radioimmunoassay. Urine KAL and BK levels were increased i n PKD compared to age-matched SD. No differences with respect to serum KAL were found between PKD and SD. In 5/6 Nx, urinary BK levels showed a trend towards higher compared to old SD (p = 0.06). KAL and BK were not increased in serum and urine of patients with ADPKD, in contrast to rats. Urinary KAL excretion was reduced in patients with ADPKD and advanced renal failure. Our results demonstrate an age-dependent activation of the renal KKS in rats with ADPKD, whereas the KKS is not activated in patients with ADPKD and advanced renal failure. These data indicate that there are fundamental differences in the factors influencing the course of the disease in human and rat ADPKD.

Clinical review: immunomodulatory effects of dopamine in general inflammation.

Large quantitaties of inflammatory mediators are released during the course of endotoxaemia. These mediators in turn can stimulate the sympathetic nervous system (SNS) to release catecholamines, which ultimately regulate inflammation-associated impairment in tissue perfusion, myocardial impairment and vasodilatation. Treatment of sepsis is based on surgical and/or antibiotic therapy, appropriate fluid management and application of vasoactive catecholamines. With respect to the latter, discussions on the vasopressor of choice are still ongoing. Over the past decade dopamine has been considered the 'first line' vasopressor and is frequently used to improve organ perfusion and blood pressure. However, there is a growing body of evidence that dopamine has deleterious side effects; therefore, its clinical relevance seems to be more and more questionable. Nevertheless, it has not been convincingly demonstrated that other catecholamines are superior to dopamine in this respect. Apart from its haemodynamic action, dopamine can modulate immune responses by influencing the cytokine network. This leads to inhibition of expression of adhesion molecules, inhibition of cytokine and chemokine production, inhibition of neutrophil chemotaxis and disturbed T-cell proliferation. In the present review we summarize our knowledge of the immunomodulatory effects of dopamine, with an emphasis on the mechanisms by which these effects are mediated.

Preconditioning strategies to limit graft immunogenicity and cold ischemic organ injury.

During the transplant process, the graft is exposed to numerous events, which may enhance its immunogenicity. In particular, factors related to brain death, such as hemodynamic instability and systemic release of cytokines, cold preservation on harvesting, and reperfusion injury, are known to accumulate in harm, conveying a proinflammatory state to the graft before transplant. Alloimmune reactivity is initiated when the host immune system detects non-self-antigens in the context of "danger signals." Eliminating these danger signals by modifying the graft before transplant has the potential to attenuate the alloimmune response. The molecules, which mediate danger signals, have not yet been fully identified. Free oxygen radicals and interferon-gamma are important candidates. One of the most important protective mechanisms against oxidative stress is the heme oxygenase 1 system. Up-regulation of heme oxygenase 1 in grafts has been shown to prevent ischemia-reperfusion damage and improve long-term graft survival in various transplant models. The benefit of blocking the action of interferon-gamma in kidney transplants is less clear because the compound plays such a complex and pivotal role in the immune response, and experimental data with interferon-gamma receptor knockout mice are conflicting. It has recently become clear that catecholamines are important graft-modifying agents. Dopamine is capable of stimulating the induction of protective enzymes like heme oxygenase-1 (HO-1) rendering the organ more resistant to the insult of ischemia/reperfusion and inflammation. Retrospective clinical data suggest that treatment of brain-dead organ donors with catecholamines is associated with less rejection and a better long-term graft survival of kidneys transplanted from these donors. Catecholamines can also modulate cytokine production and prevent cold-induced damage. Other substances, such as proteoglycans and phosphatidylethanolamine-bound hyaluronic acid, may interfere with the actions of interferon-gamma. Further studies of these compounds in experimental animal models and in prospective randomized clinical trials will help establish their efficacy in donor pretreatment. It is important to underscore that donor pretreatment will have great advantages for the recipient because an improved long-term graft survival could thus be achieved cost-efficiently and without great effort or side effects.