Belda Dursun

Acute Renal Failure after Bilateral Nephrectomy Is Associated with Cytokine-Mediated Pulmonary Injury

Clinical studies demonstrate that acute renal failure (ARF) is associated with increased mortality, which may be due to pulmonary complications. ARF may affect the lung via increased renal production or impaired clearance of mediators of lung injury, such as proinflammatory cytokines. Bilateral nephrectomy is a method to examine directly the deleterious systemic effects of absent renal clearance in ARF without the confounding effects that are associated with ischemia-reperfusion injury (e.g., ischemic ARF) or systemic toxicity (e.g., cisplatin-induced ARF). This study contrasts the effects of ischemic ARF and bilateral nephrectomy on serum cytokines and lung injury. It demonstrates that the acute absence of kidney function after both ischemic ARF and bilateral nephrectomy is associated with an increase in multiple serum cytokines, including IL-6 and IL-1beta, and that the cytokine profiles were distinct. Lung injury after ischemic ARF and bilateral nephrectomy was similar and was characterized by pulmonary vascular congestion and neutrophil infiltration. For investigation of the role of proinflammatory cytokines in pulmonary injury after ARF, the anti-inflammatory cytokine IL-10 was administered before bilateral nephrectomy. IL-10 treatment improved pulmonary architecture and was associated with a reduction in inflammatory markers, including bronchoalveolar lavage fluid total protein, pulmonary myeloperoxidase activity (a biochemical marker of neutrophils), and the chemokine macrophage inflammatory protein 2. These data demonstrate for the first time that the acute absence of kidney function results in pulmonary injury independent of renal ischemia and highlight the critical role of the kidney in the maintenance of serum cytokine balance and pulmonary homeostasis.

Treatment with an Inhibitory Monoclonal Antibody to Mouse Factor B Protects Mice from Induction of Apoptosis and Renal Ischemia/Reperfusion Injury

Complement activation in the kidney after ischemia/reperfusion (I/R) seems to occur primarily via the alternative complement pathway. The ability of an inhibitory mAb to mouse factor B, a necessary component of the alternative pathway, to protect mice from ischemic acute renal failure was tested. Treatment with the mAb prevented the deposition of C3b on the tubular epithelium and the generation of systemic C3a after renal I/R. Treated mice had significantly lower increases in serum urea nitrogen and developed significantly less morphologic injury of the kidney after I/R. For gaining insight into potential mechanisms of protection, the activity of caspases within the kidney also was measured, and it was found that caspases-2, -3, and -9 increased in a complement-dependent manner after renal I/R. Apoptotic cells were detected by terminal deoxynucleotidyl transferase catalyzed labeling of DNA fragments, and mice in which the alternative pathway was inhibited demonstrated significantly less apoptosis than control mice. Thus, use of an inhibitory mAb to mouse factor B effectively prevented activation of complement in the kidney after I/R and protected the mice from necrotic and apoptotic injury of the tubules.

Increased macrophage infiltration and fractalkine expression in cisplatin-induced acute renal failure in mice

Inflammatory mechanisms contribute to cisplatin-induced acute renal failure (CisARF). Our first aim was to determine renal macrophage infiltration in CisARF. A more than 2-fold increase in CD11b-positive macrophages in the kidney on day 2 preceded the increase in blood urea nitrogen (BUN) and serum creatinine (SCr). Our next aim was to determine the chemoattractant for macrophage infiltration in CisARF. Fractalkine (CX3CL1) is expressed on activated endothelial cells and is a potent chemoattractant for macrophages that express its receptor (CX3CR1). Immunoblotting showed that whole-kidney CX3CL1 expression on days 1, 2, and 3 after cisplatin administration was increased. On immunofluorescence, the intensity of renal endothelial staining of CX3CL1 in blood vessels was significantly increased on day 2. Circulating von Willebrand factor (vWF), a measure of systemic endothelial injury, was increased on day 2. Next we determined whether macrophages played an injurious role in CisARF. Macrophages were depleted with injections of liposome-encapsulated clodronate (LEC). LEC resulted in a decrease in renal CD11b-positive macrophages on day 3. However, LEC-treated mice were not protected from CisARF on day 3. To determine the role of CX3CR1, both a specific anti-CX3 CR1 antibody and CX3 CR1–/– mice were used. Administration of the CX3CR1 antibody and CX3 CR1–/– mice was not protected against CisARF. In summary, in CisARF, macrophage infiltration in the kidney, CX3CL1 expression in whole kidney and blood vessels, and the increase in circulating vWF precede BUN and SCr increase. However, inhibition of macrophage infiltration in the kidney or CX3CR1 blockade is not sufficient to prevent CisARF.

Carotid artery intima-media thickness correlates with oxidative stress in chronic haemodialysis patients with accelerated atherosclerosis

BACKGROUND Accelerated atherosclerosis is the major cause of mortality in patients on chronic haemodialysis (HD). Increased oxidative stress might be the major factor leading to high cardiovascular mortality rate in HD patients. The aim of our study was to clarify effects of uraemia and dialysis on oxidative stress parameters and explore the relation between oxidative stress markers and carotid artery intima-media thickness (CIMT) as an indicator of atherosclerosis. METHODS Twenty chronic HD patients, 20 predialytic uraemic patients and 20 healthy subjects were included in the study. Serum thiobarbituric acid reactive substances (TBARS), protein carbonyl content (PCO) and nitrite/nitrate levels were determined as oxidative stress markers. Serum vitamin E, plasma sulfhydryl (P-SH), erythrocyte glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were measured as antioxidants. CIMT was assessed by carotid artery ultrasonography. RESULTS Both chronic HD and predialytic uraemic patients had enhanced oxidative stress indicated by higher levels of nitrite/nitrate, TBARS and PCO, and lower levels of P-SH, SOD, CAT and GPx compared to controls. HD patients had significantly higher CIMT and nitrite/nitrate while significantly lower P-SH,vitamin E, SOD, CAT and GPx compared to predialytic uraemic patients. There was a significant positive correlation between CIMT and TBARS (r = 0.38, P = 0.003) and nitrite/nitrate levels (r = 0.41, P = 0.001), while there was a significant negative correlation between CIMT and SOD (r = -0.35, P = 0.01), CAT (r = -0.65, P < 0.001) and P-SH levels (r = -0.50, P < 0.001). A linear regression analysis showed that TBARS were still significantly and positively correlated with CIMT (P = 0.001), while CAT and P-SH were significantly and negatively correlated with CIMT (P = 0.002 and P = 0.048, respectively). CONCLUSIONS HD exacerbates oxidative stress and disturbances in antioxidant enzymes in uraemic patients. We propose that serum TBARS and nitrite/nitrate can be used as positive determinants, while erythrocyte SOD, CAT and P-SH may be used as negative determinants of atherosclerosis assessed by CIMT in uraemic and HD patients.

Effect of hemodialysis on the oxidative stress and antioxidants

Abstract Oxidative stress plays a role in many disease states. These diseases have an increased incidence in uremia, and particularly in hemodialysis (HD) patients. This suggests an increased exposure to oxidative stress. An imbalance between oxidants and antioxidants has been suggested in uremic patients on HD. However, the respective influence of uremia and dialysis procedure has not been evaluated. It is postulated that antioxidant capacity in uremic patients is reduced, yet the mechanism remains unclear. We have determined the levels of lipid peroxidation expressed as thiobarbituric acid-reactive substances. We assessed oxidative protein damage by carbonyl content and activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in predialysis uremic patients and in end-stage renal disease (ESRD) patients before and after hemodialysis. Vitamin E and vitamin C levels, reduced glutathione and sulfhydryl content were also studied. We found enhanced oxidative stress in ESRD patients undergoing HD and in predialysis uremic patients. This was mostly due to defective antioxidant enzyme levels. Preventive modalities, including use of biocompatible membranes, ultrapure dialysate, exogenous supplementation of antioxidant vitamins, extracorporeal removal of reactive oxygen species (ROS) and oxidatively modified substances, would appear highly desirable to reduce complications in the long-term dialysis patients.

Peripheral CD4 T-cell depletion is not sufficient to prevent ischemic acute renal failure.

Background. Ischemia reperfusion injury leading to acute renal failure (ARF) and delayed graft function is an important problem in organ transplantation. CD4+ T cells, essential for transplant rejection, may mediate ischemic ARF. We have demonstrated that the caspase-1 mediated production of IL-18 is pathogenic in ischemic ARF in mice. A potential source of IL-18 in ischemic ARF is the CD4+ T cell. We therefore examined the effect CD4+ T cell depletion on the development of ischemic ARF and the activation of IL-18. Methods. Functional and histological correlates were examined in two groups of mice with ischemic ARF: 1) CD4 T-cell depleted with the antibody GK1.5, and 2) T-cell receptor α-chain deficient (TCRα −/−) mice. TCRα −/− mice lack the α chain of the T-cell receptor and therefore lack functional CD4+ and CD8+ T cells. Results. Flow cytometry of lymph nodes and immunohistochemistry of kidneys demonstrated complete depletion of CD4+ T cells in mice with ischemic ARF treated with GK 1.5. CD4+ T-cell depletion did not confer functional (serum creatinine, BUN and FITC-labeled inulin clearance) or histological protection against ischemic ARF. Likewise, TCRα −/− mice were not protected against ischemic ARF. Renal caspase-1 activity and IL-18 protein were similar in CD4+ T-cell depleted and wild-type postischemic reperfusion. Conclusions. Ischemic ARF can occur in the absence of classical T-cell function. The evaluation of other inflammatory mediators (e.g., macrophages or NK cells) as a source of IL-18 and mediator of ischemic ARF warrants further investigation.

Cytokine production increases and cytokine clearance decreases in mice with bilateral nephrectomy

BACKGROUND Serum cytokines are increased in patients with acute kidney injury (AKI) and predict increased mortality. It is widely assumed that increased renal production of cytokines is the source of increased serum cytokines; the role of extra-renal cytokine production and impaired renal cytokine clearance is less well studied. We hypothesized that cytokine production in AKI was mononuclear phagocyte dependent, independent of production by the kidneys, and that serum cytokine clearance would be impaired in AKI. METHODS Bilateral nephrectomy was used as a model of AKI to assess cytokine production independent of kidney cytokine production. Mononuclear phagocytes were depleted utilizing intravenous (IV) administration of liposome-encapsulated clodronate (LEC). Twenty-three serum cytokines were determined utilizing a multiplex cytokine kit. Proteins for cytokines were determined in the spleen and liver by enzyme-linked immunosorbent assay. Recombinant cytokines were injected by IV into mice with bilateral nephrectomy to determine the effect of absent kidney function on serum cytokine clearance. RESULTS Serum interleukin (IL)-6, chemokine (C-X-C motif) ligand 1 (CXCL1), IL-10, IL-1β, monocyte chemotactic protein 1 (MCP-1), IL-5 and eotaxin were increased in the serum of mice after bilateral nephrectomy and were reduced with LEC. Serum IL-12p40 and regulated upon activation, normal T-cell expressed, and secreted (RANTES) were increased after bilateral nephrectomy and were further increased with LEC. Spleen IL-6, CXCL1, IL-10 and IL-1β and liver IL-6 and IL-10 were increased after bilateral nephrectomy. After IV injection, IL-6, CXCL1, IL-10 and IL-1β had a prolonged serum cytokine appearance in mice with bilateral nephrectomy versus sham operation. CONCLUSIONS Increased mononuclear phagocyte production and impaired renal clearance contribute to serum cytokine accumulation in AKI, independent of kidney injury. The effect of AKI on cytokine production and clearance may contribute to the increased mortality of patients with AKI.

Severe pulmonary haemorrhage accompanying hepatorenal failure in fulminant leptospirosis.

Leptospirosis is a re‐emerging spirochetal zoonosis with a worldwide distribution affecting both animals and humans. The clinical syndromes may vary from a subclinical infection to a severe illness. Although it may potentially have a fulminant and fatal course, leptospirosis usually remains as an underdiagnosed cause of multiorgan failure. In this study, we report a patient with leptospirosis who presented with a fulminant course of diffuse alveolar haemorrhage and hepatorenal failure. His clinical condition deteriorated, despite appropriate antibiotic therapy and haemodialysis. However, he showed prompt clinical improvement when corticosteroids and plasma exchange were instituted in addition to the original therapy. We conclude that leptospirosis should be considered in any case presenting with pulmonary haemorrhage and hepatorenal failure. Plasma exchange and corticosteroids may be a choice of treatment in selected patients unresponsive to conventional therapy. Potential benefits of plasma exchange and corticosteroids may be based on a toxin‐ and/or cytokine‐mediated pathogenesis of the disease.

Can cystatin C be a better marker for the early detection of renal damage in primary hypertensive patients

In this study, we aimed to compare Cystatin C (Cys C) with other traditional glomerular filtration rate (GFR) markers and to evaluate its superiority over them in detecting early renal involvement in patients with primary hypertension. Fifty-one primary hypertensive patients and 29 healthy control subjects, who were similar in terms of age and gender, were included in the study. In all subjects serum levels of Cys C, beta-2 microglobulin, serum creatinine (SCr), uric acid, BUN, albumin; 24 h urinary levels of protein (Upro), albumin (Ualb) and creatinine were measured. The GFR was calculated according to Creatinine Clearance (CrCl), Cockcroft-Gault (CG) and Modification of Diet in Renal Disease (MDRD) formulas. The MDRD was used as the reference method. A GFR < 80 mL/min/1.73 m2 was considered as the lower cut-off limit. Mean levels of the serum parameters were found to be significantly higher in the patient group than they were in the control group (p < 0.05). Mean CrCl, CG, and MDRD levels were lower in patients than they were in controls but the difference was statistically significant for CG and MDRD. The serum parameter having the best correlation with MDRD was SCr (r = − 0.760) in patients and Cys C (r = − 0.622) in controls. However, in ROC analysis; the area under curve (AUC) for Cys C was found to be superior (AUC = 0.900) to the other markers. The CrCl was the parameter having the worst diagnostic efficiency (AUC = 0.598). As a conclusion, compared to other traditional markers, measurement of Cys C may be a better parameter to estimate GFR, especially to detect mild reductions of GFR in primary hypertensive patients.

Acute effects of hemodialysis on oxidative stress parameters in chronic uremic patients: Comparison of two dialysis membranes

Uremic state and hemobioincompatibility are implicated in subclinical inflammation and oxidative stress and progression of atherosclerosis in the hemodialysis (HD) population. To what extent different dialysis membranes contribute to oxidative stress induced by a dialysis procedure per se is still a subject of debate. Fifteen HD patients and 15 healthy controls were enrolled in this study. Patients received two index HD sessions with a cuprophane and polysulfone membrane two weeks apart. Blood samples were collected at baseline and then before and after HD sessions. We determined serum thiobarbituric acid, protein carbonyl, and serum nitrite/nitrate levels as markers of oxidative damage. We also measured erythrocyte glutathione level, catalase, superoxide dismutase and glutathione peroxidase activity, and serum vitamin C and E levels as antioxidant markers. At baseline, HD patients, in comparison with normal controls, had a trend towards increased oxidant state and depletion of antioxidants. Cuprophane dialysis induced a higher increase in production of oxidants, along with a lower compensatory increase of antioxidants when compared with polysulfone dialysis. In conclusion, a single HD session, even when conducted with a biocompatible membrane, appears to play an important role in the imbalance between ROS production and antioxidant defense, but to a milder extent than cuprophane dialysis.