Leukocyte toll-like receptor expression in end-stage kidney disease.

BACKGROUND: End-stage renal disease (ESRD) is simultaneously associated with inflammation, impaired immunity and increased susceptibility to microbial infections. Innate immune cells, monocytes and polymorphonuclear leukocytes (PMN) recognize pathogens via toll-like receptors (TLR) triggering phagocytosis, cellular activation and secretion of inflammatory cytokines. Data on expression and function of TLRs in ESRD are limited. METHODS: Blood samples from 21 stable ESRD patients and 21 normal controls were processed for TLR2, TLR4, TLR7 and TLR 9 expression on monocytes and PMN by flow cytometry. TLR activity was examined by determining the response to TLR4 and TLR2 ligands. RESULTS: The ESRD group exhibited significant upregulation of TLR2 and TLR4 (but not TLR7 or TLR 9) expressions on monocytes and of TLR4 on PMN. This was coupled with heightened cytokine production in response to TLR4 activation with lipopolysaccharide. However, the response to TLR2 stimulation with peptidoglycan was unchanged in the ESRD group. CONCLUSIONS: Monocyte TLR2 and TLR4 and neutrophil TLR4 expressions and TLR4 activity are increased hemodialysis patients, representing another dimension of ESRD-associated inflammation.

Increased monocyte adhesion-promoting capacity of plasma in end-stage renal disease - response to antioxidant therapy.

UNLABELLED: End-stage renal disease (ESRD) causes accelerated atherosclerosis which is mediated by oxidative stress and inflammation. Activation and infiltration of monocytes represent the critical steps in atherogenesis which is advanced by oxidized LDL and inhibited by HDL. Via its main apolipoprotein (apoA-I) and constituent enzymes (paraoxonase; glutathione peroxidase (GPX), LCAT) HDL exerts potent antioxidant/anti-inflammatory functions. We have found marked reduction of HDL antioxidant/anti-inflammatory and heightened LDL pro-oxidant/pro-inflammatory activities in ESRD patients. Given the inseparable link between oxidative stress and inflammation, we tested the hypothesis that antioxidant therapy may improve anti-inflammatory (monocyte adhesion-promoting capacity) properties of plasma in ESRD patients. METHODS: We studied 20 hemodialysis patients who after a 4-week wash-out period were treated with a potent antioxidant cocktail (vitamin (v) E, 800 IU; vC, 250 mg; vB6, 100 mg; vB12, 250 µg and folic acid 10 mg daily) for 8 weeks. Twelve healthy volunteers served as control. Pre-dialysis plasma samples were obtained at the onset and conclusion of the study. Markers of oxidative stress and inflammation, apoA-I, HDL-associated enzymes and monocyte adhesion assay were measured using cultured aortic endothelial cells. RESULTS: ESRD patients exhibited reduced plasma level of apoA-1 and antioxidant enzymes, elevated markers of oxidative stress and inflammation and heightened monocyte adhesion-promoting capacity. Antioxidant therapy failed to improve these abnormalities. CONCLUSIONS: High doses of antioxidant vitamins fail to improve oxidative stress, inflammation or plasma monocyte adhesion-promoting capacity in ESRD patients. Thus, high doses of vitamins beyond the routinely-prescribed supplements do not appear to be beneficial in this patient population.

Acquired deficiency and urinary excretion of antithrombin III in nephrotic syndrome.

The published data concerning changes of antithrombin III (ATIII) in nephrotic syndrome (NS) are contradictory. While increased ATIII activity has been reported by some investigators, decreased concentration has been shown by others and normal values by yet another group of authors. We determined plasma and urine concentrations of ATIII in a group of 20 patients with NS using an immunologic assay. In addition, plasma ATIII activity was determined. The results were compared with those obtained in a group of normal volunteers. Plasma concentration and activity of ATIII were both greatly reduced in the patients with NS. In addition, substantial quantities of ATIII were recovered in the urine of all tested patients. The present study, therefore, substantiates the low plasma concentrations of ATIII and its urinary losses in NS. In addition, a parallel reduction in plasma ATIII activity is demonstrated providing functional evidence of acquired ATIII deficiency in this condition.

The effect of pregnancy on renal clearance of boron in humans: a study based on normal dietary intake of boron.

Boron occurs most frequently in nature as borates and boric acid, never as the free element. Its largest uses are in glass, detergents, and agriculture. Essential for higher plants, there is growing evidence for essentiality in vertebrates. Humans consume daily about a milligram of boron, mostly from fruit and vegetables. At high doses, boron is a developmental and reproductive toxin in animals. Pregnant rats were the most sensitive. An oral NOAEL of 9.6 mg B/kg/day was established for developmental toxicity in Sprague-Dawley rats fed boric acid. To extrapolate from the large, animal boron toxicity database to humans, especially to pregnant women, information on renal clearance of boron was needed. This study's purpose was to measure renal clearance of boron in pregnant and nonpregnant woman. In 16 second trimester women and 15 nonpregnant age-matched referents, dietary boron provided the blood and urine boron concentrations used for calculating boron clearance. The pregnant and nonpregnant boron intake was 1.35 and 1.31 mg boron/24 h, respectively. Blood for boron, creatinine, and urea was collected at the start, at 2 h, and at 24 h. Urine was collected during the first 2 h in the Clinical Research Center and during a 22-h period outside the center for measurement of volume, boron, and creatinine. Renal boron clearance measured over the initial 2 h, the most complete urine collection period, was 68.30ml/min/1.73 m(2) for pregnant subjects and 54.31ml/min/1.73 m(2) for nonpregnant subjects. Comparison of renal boron clearance with creatinine clearance indicated that tubular reabsorption of boron occurred in both pregnant and nonpregnant women.

The effect of pregnancy on renal clearance of boron in rats given boric acid orally.

Boric acid (H(3)BO(3)) has been shown to cause developmental abnormalities in the offspring of pregnant rats. Comparative data on the renal clearance of boron (B) in rats and humans, both pregnant and nonpregnant, exposed to boric acid (BA) would reduce uncertainty in interspecies extrapolation from rats to humans. The purpose of this study was to evaluate the effect of pregnancy on the plasma half-life and renal clearance of boron in Sprague-Dawley rats given a single oral dose of boric acid. For the half-life study, nonpregnant and pregnant (gestation day 16) rats were given a single dose of 30 mg/kg of boric acid by gavage, and plasma samples were collected at 2-3 h intervals. The plasma half-life of boron was determined to be 2.9 +/- 0.2 and 3.2 +/- 0.3 h in nonpregnant and pregnant rats, respectively. In the clearance study, nonpregnant and pregnant (GD 16) rats were given a single gavage dose of 0.3, 3, or 30 mg/kg of boric acid. Boron clearance was slightly higher in pregnant rats (3.3 +/- 0.6, 3.2 +/- 0.5, and 3.4 +/- 0.5 ml/min/kg, respectively) compared to nonpregnant rats (3.1 +/- 0.8, 3.0 +/- 0.6, and 3.2 +/- 0.5 ml/min/kg, respectively), but the difference was not statistically significant and not dose-related. Boron clearance was less than creatinine clearance, suggesting tubular reabsorption in both groups. In conclusion, pregnancy did not appear to significantly alter the renal clearance or the plasma half-life of boron in Sprague-Dawley rats under the conditions of this study.

Intestinal transport of pyridoxine in experimental renal failure.

Renal failure (RF) has been shown to alter intestinal transport of a number of nutrients. We studied jejunal absorption of pyridoxine (B6) in rats rendered azotemic by subtotal nephrectomy (RF group) and compared the results with those obtained in normal rats subjected to sham operation (controls) and animals pair-fed (PF) with their RF counterparts. In vivo recirculating perfusion and in vitro everted sac techniques were employed. The in vitro experiments were repeated using sera from uremic and normal individuals to assess the possible effect of uremic chemical environment. The results showed significant reduction in B6 absorption in vivo in the RF group as compared to the control and PF groups. Paradoxically, the rate of in vitro B6 absorption determined for a wide range of concentrations was increased in the RF and PF groups as compared to the control group. The observed increase in B6 absorption in vitro suggests enhanced permeability in the RF and PF groups due probably to reduced nutrient intake which was common to both groups. The disparity between the in vivo and in vitro results is indicative of some inhibitory factor(s) present in the RF animals. Sacs containing uremic serum showed significantly suppressed B6 absorption in vitro as compared to those containing normal serum. These observations suggest that the uremic chemical environment may be, in part, responsible for the observed impairment of B6 transport in RF animals despite in vitro evidence of hyperpermeability.

Intestinal absorption of arachidonic acid in experimental azotemia.

The effect of renal failure (RF) on intestinal absorption of dietary fatty acids is not known. We studied the intestinal absorption of arachidonic acid (AA) in rats with experimental short-term (2 weeks post-subtotal nephrectomy) and long-term (5-6 weeks post-subtotal nephrectomy) RF. The results were compared with those obtained in sham-operated animals on liberal food intake (NL) and in those pair-fed (PF) with the respective RF groups. In vivo perfusion and in vitro incubation experiments were performed at a wide range of AA concentrations. The rates of AA transport determined both in vivo and in vitro were significantly lower in the short-term RF group than those found in the NL controls and the PF animals who showed comparable values. In contrast animals with long-term RF exhibited an increased rate of AA transport as compared with the respective controls. The observed changes in the transport rates appeared to parallel directional changes in mucosal mass which was reduced in animals with short-term RF and restored in those with long-term RF.

Continuous arteriovenous hemodiafiltration in postoperative and traumatic renal failure.

Management of acute renal failure (ARF) in surgical patients has relied on supportive measures including hemodialysis and peritoneal dialysis. An alternative technique currently available is continuous arteriovenous hemodiafiltration (CAVH-D). Records of 44 surgical patients with ARF who were treated with CAVH-D in our surgical intensive care unit from 1989 to 1992 were reviewed. Thirty-five patients underwent emergency operations, and 4 patients underwent elective operations. Thirty-three patients were hemodynamically unstable immediately prior to the institution of CAVH-D, making hemodialysis a contraindication. A total of 565 CAVH-D days with an average of 13 days per patient were evaluated. Seventeen patients survived, with recovery of renal function in 13 patients. Vascular access was obtained via 227 percutaneous femoral catheters and 4 Scribner shunts. Seven vascular complications occurred, including arteriovenous fistula, pseudoaneurysm, limb ischemia, femoral artery hemorrhage, and femoral vein thrombosis. Based on these data, we conclude that CAVH-D is a safe and effective alternative in surgical patients with ARF.

Effects of low density lipoprotein on cytosolic [Ca++] in cultured rat mesangial cells.

BACKGROUND: Recently, a low density lipoprotein (LDL) receptor has been identified in mesangial cells. However, the nature of intracellular signals in mesangial cells after exposure to LDL is unclear. METHODS: We studied the effect of LDL on cultured rat mesangial cell [Ca++]i using spectrofluorometry. RESULTS: Addition of LDL (15 micrograms/mL) produced a rapid, transient, and dose-dependent rise in [Ca++]i within seconds, returning to baseline in 6 minutes. No further rise was observed at higher LDL concentrations. No significant rise in [Ca++]i was observed with LDL in cells placed in a Ca(++)-free medium. The [Ca++]i rise was greatly attenuated in magnitude and duration when lanthanum was used. In contrast, verapamil failed to block the LDL-induced rise in [Ca++]i. Addition of LDL did not alter production of inositol 1,4,5-triphosphate (IP3) by mesangial cells. CONCLUSIONS: Low density lipoprotein caused a transient rise in [Ca++]i in cultured rat mesangial cells. The observed rise in [Ca++]i was largely caused by influx of extracellular Ca++ through receptor-gated channels. Mobilization from intracellular stores and activation of IP3 were not involved. The rise in [Ca++]i may mediate the effects of LDL on mesangial cell function.

Proteinuria in patients with arterial/arteriolar nephrosclerosis.

UNLABELLED: Controversy exists regarding the level of proteinuria in patients with nephrosclerosis. MATERIAL AND METHODS: We retrospectively examined the clinical parameters of 67 patients with the histologic diagnosis of nephrosclerosis defined as arteriolar hyalinization and/or arterial intimal fibrosis in the absence of other findings in an adequate renal biopsy. Biopsies were performed for clinical indications and were submitted to Cedars-Sinai Pathology Department from January 1994 to March 1999. RESULTS: The mean age and blood pressure (+/- SD) was 60 +/- 17 years, and 139 +/- 19/80 +/- 12 mmHg. Mean serum creatinine was 2.3 +/- 1.3 mg/dl and 24-hour urinary protein excretion was 0.94 +/- 0.73 g, 66% had < or = 1 g/day, 25% had > 1 but < or = 2 g/day, 6% had > 2 g but < 3 g/day and 1 patient had nephrotic range proteinuria. Twelve patients had no history of hypertension. They had a mean blood pressure of 121 +/- 8/76 +/- 8. Their mean serum creatinine was 1.5 +/- 0.6 mg/dl and their mean 24-hour urinary protein excretion was 0.78 +/- 0.43 g. CONCLUSIONS: Our data do not confirm that of Innes et al. [1993] who reported proteinuria > 1.5 g/day in 40% and nephrotic syndrome in 22% of patients with nephrosclerosis; systemic hypertension may not be a prerequisite for the development of nephrosclerosis.

Pathology of digestive organs in renal transplant recipients.

A necropsy study of the pathological findings in the digestive system of 19 renal transplant recipients revealed that gastrointestinal (GI), hepatobiliary, and pancreatic pathologies are common in renal transplant recipients. Fifteen of the 19 patients studied had GI pathology. Hepatobiliary pathology was the most common finding with all but one of the 19 cases exhibiting one or more abnormalities. Pancreatic abnormalities were less frequent with 11 patients demonstrating normal findings.

Effect of rapid weight loss with supplemented fasting on serum electrolytes, lipids, and blood pressure.

The effect of rapid weight reduction with supplemented fasting was studied in a group of 46 individuals with moderate to severe obesity. The preparation used contained a mixture of protein, carbohydrate, and essential fatty acids providing 420 kcal daily. It was supplemented with a complement of electrolytes, minerals, and vitamins.Serum concentrations of electrolytes, urea nitrogen, creatinine, uric acid, glucose, cholesterol, and triglycerides were measured prior to the onset of the study and at two-week intervals for a six-week study period. In addition, blood pressure, heart rate, and body weight were recorded regularly. A mild and transient fall in serum bicarbonate concentration and a rise in uric acid level was observed.In contrast to other regimens, hypokalemia was not observed in the present study. In fact, serum K+ concentration rose slightly while serum Na+ concentration remained virtually unchanged. There was a transient rise in serum creatinine concentration followed by a fall to values below the baseline. Serum glucose, cholesterol and triglyceride levels, blood pressure, and heart rate decreased significantly. Body weight fell from 232.7 ± 58 lb at the onset of the study to 176.4 ± 47.9 lb at the conclusion of the study.The protocol was well tolerated and the side effects were mild and infrequent. In conclusion, the present protocol provides a safe and effective means for rapid weight reduction in individuals with moderate to marked obesity without producing severe electrolyte disturbances seen with other modalities.

Spontaneous leukocyte activation and oxygen-free radical generation in end-stage renal disease.

Oxidative stress and inflammation are common features and major mediators of atherosclerosis in end-stage renal disease (ESRD). Available evidence for oxidative stress in ESRD is indirect and based on accumulation of byproducts of interactions of reactive oxygen species (ROS) with various molecules. Inflammation is a major cause of oxidative stress. To explore the direct link between oxidative stress and inflammation in ESRD, we studied leukocyte integrin expression and ROS production in 18 ESRD patients and 18 controls. ESRD patients showed elevated plasma malondialdehyde (MDA) and increased superoxide and hydrogen peroxide (H(2)O(2)) production by granulocytes and monocytes before dialysis. Hemodialysis resulted in a further rise in plasma MDA and H(2)O(2) production by granulocytes and monocytes. Surface expression of Mac-1 (CD11b and CD18) on granulocytes and monocytes was significantly increased (denoting cell activation) in ESRD patients. Granularity of granulocytes was significantly reduced before dialysis and declined further after dialysis. The magnitude of ROS production by granulocytes and monocytes was directly related with CD11b expression as well as plasma ferritin and parathyroid hormone levels and was inversely related to protein catabolic rate. Thus, this study provides direct evidence of spontaneous leukocyte activation and increased ROS generation (hence the link between oxidative stress and inflammation) in ESRD patients.

Naïve and central memory T-cell lymphopenia in end-stage renal disease.

End-stage renal disease (ESRD) is associated with increased propensity to infections, diminished response to vaccination, impaired cell-mediated immunity, and reduced CD4+/CD8+ T-lymphocyte ratio. Four subsets of CD4+ and CD8+ T cells have been recently identified: naïve cells (as yet uncommitted), central memory (CM) cells (previously programmed), and CD45RA-positive and CD45RA-negative effector memory (EM) cells (programmed to perform specific effector functions). The effect of ESRD on subpopulations of T lymphocytes is unclear and was studied here. Twenty-one hemodialysis patients and 21 age-matched controls were studied. Pre- and post-dialysis blood samples were obtained and analyzed by three-color flow cytometry. CD4+/CD8+ ratio and the numbers of the naïve and CM CD4+ and CD8+ T cells were significantly reduced, whereas the numbers of EM CD4+ and CD8+ T cells were unchanged in the ESRD group. The reduction of the naïve and CM T-cell counts in the ESRD group was associated with increased apoptosis of these cells. Negative correlations were found between severity of azotemia, oxidative stress, and hyperphosphatemia with the number of naïve T cells. Comparison of diabetic with non-diabetic ESRD patients revealed higher numbers of total CD8+ cells and EM CD8+ T cells in the diabetic group. Dialysis did not significantly change the naïve and CM CD4+ or CD8+ cell counts, but significantly lowered CD8+ EM cell count. Thus, ESRD results in increased apoptosis and diminished populations of naïve and CM T lymphocytes. This phenomenon may, in part, contribute to the impaired immune response in this population.

In-vivo and in-vitro hemodialysis studies of thiocyanate.

Dialysis clearance of thiocyanate was studied using in-vivo and in-vitro systems. The in-vivo studies were performed in a patient with renal failure receiving sodium nitroprusside infusion for accelerated hypertension. In-vitro studies were carried out under experimental conditions similar to those of the in-vivo experiment. Plasma thiocyanate level consistently fell with single passage through the dialyzer. In-vivo dialysance of thiocyanate averaged 82.8 ml/min as compared to urea dialysance of 129.6 ml/min. The in-vitro studies revealed an average thiocyanate dialysance of 102.3 as compared to a urea dialysance of 138.6 ml/min. Removal of thiocyanate by hemodialysis was further verified by recovery of significant amounts of thiocyanate in the outgoing dialysate. The thiocyanate clearance calculated directly from the amount recovered in the dialysate and mean plasma concentration was 82.2 ml/min, a value closely approximating that obtained using the transdialyzer concentration gradient. We conclude that hemodialysis is effective in removing thiocyanate and can be used as adjunct in the treatment of thiocyanate toxicity particularly in the presence of renal failure in which thiocyanate excretion is impaired.

Coagulation profile in persons with long-standing spinal cord injury.

Acute spinal cord injury (SCI) is associated with a marked propensity to thromboembolism and a variety of coagulation abnormalities. However, data on blood coagulation profiles in patients with uncomplicated long-standing SCI are limited. These data were studied here. Eight men with uncomplicated chronic SCI and nine able-bodied normal men were studied. Plasma activities and/or antigen concentrations of high molecular weight kininogen (HMWK) and of factors XII, XI, IX, VIII, VII, X, V, II and XIII as well as von Willebrand factor (vWF), fibrinogen and fibronectin were measured by appropriate functional and or immunological assays. The SCI group exhibited normal values for factors XII, IX, VIII, vWF, VII, X and V as well as HMWK, vWF and fibronectin concentration. However, they showed slight reductions in plasma factor XI activity, factor XIII antigen concentration and modest increases in fibrinogen and factor II concentrations. No correlation was found between the parameters studied and either the duration or the level of injury. In conclusion, in contrast to acute SCI, the coagulation profile in uncomplicated chronic SCI is noted to be largely normal with only a few minor alterations of questionable clinical significance.