Kallikrein excretion in renal transplant recipients and in uninephrectomized donors

Do Biochemical Measures Change in Living Kidney Donors?

BACKGROUND

Living kidney donation provides a unique opportunity to assess possible biochemical changes attributable to small decrements in glomerular filtration rate. We reviewed studies which followed 5 or more healthy donors, where changes in biochemical measures or anemia were assessed at least 4 months after nephrectomy.

METHODS

We searched MEDLINE, EMBASE, and Science Citation databases, and reviewed reference lists from 1966 through June 2006. We abstracted data on study and donor characteristics and biochemical outcomes of interest.

RESULTS

Eight studies examined at least one outcome of interest. The average time after donation ranged from 0.4 to 11 years, the postdonation creatinine clearance ranged from 73 to 99 ml/min, and the decrement after donation ranged from 11 to 38 ml/min. Nephrectomy did not change hemoglobin, erythropoietin, serum phosphate, calcium or C-reactive protein levels. The studies were inconsistent as to whether parathyroid hormone levels increased and 1,25-dihydroxyvitamin D levels decreased after nephrectomy. Uric acid levels increased variably post-donation. Plasma homocysteine increased in the single study included in this review.

CONCLUSIONS

The mechanistic changes described above and their prognostic significance need clarification. Based on existing evidence, it is not necessary to routinely monitor living kidney donors for changes in these biochemical measures.

Tissue kallikrein and kinins in renal disease

The renal kallikrein-kinin system is involved in sodium and water homeostasis, blood pressure regulation and inflammation. Tissue kallikrein and kinin levels were measured in the urine of patients with renal disease and in the urine of living related kidney donors prior to uninephrectomy who served as controls. Tissue kallikrein and kinin B1 and B2 receptors were immunolocalised by confocal microscopy in renal biopsy material from patients with renal disease and controls (fresh autopsy material and normal kidney tissue from nephrectomies for malignancy). Urinary tissue kallikrein excretion was significantly decreased in patients with mild renal disease (16.6 +/- 6.7 ng tissue kallikrein (TK)/ng protein; p < 0.05) and more markedly so (1.8 +/- 0.7 ng TK/microg protein; p < 0.01) in patients with severe renal failure requiring dialysis compared to normal controls (78.9 +/- 31.7 ng TK/microg protein). Basal kinin values were unchanged in patients with renal disease (14 +/- 0.8 ng/ml) compared to controls (13.3 +/- 0.56 ng/ml). In control kidney tissue kallikrein was immunolocalised in the distal connecting tubules and collecting ducts whereas decreased immunolabelling was observed with renal disease. Kinin B2 receptor labelling was present in the entire nephron in the normal control kidney but was reduced with renal disease. While kinin B1 receptor immunolabelling was not observed in the control kidneys, labelling of distal tubules and collecting ducts was noted in renal disease, suggesting an upregulation of B1 receptors in renal parenchymal disease.

Hypertensive end-stage renal disease in blacks: the role of end-stage renal disease surveillance

The end-stage renal disease (ESRD) networks and the United States Renal Data System recently have described the epidemiology of ESRD and broadened our appreciation of the impact of ESRD in the United States. This surveillance system also can be used to study the occurrence and control of ESRD. Among the epidemiologic study designs available to conduct research on the etiology of renal failure, case-control studies are uniquely suited for this purpose. The case of hypertensive ESRD illustrates this concept; risk factors for hypertensive ESRD, as a hypothetical exposure in case-control studies, are briefly described. Case-control studies are an efficient and readily used means to study causes of renal failure.

Evidence for intrarenal kallikrein storage during chromate-induced acute renal failure in rat

During the course of chromate-induced acute renal failure (ARF), urinary kallikrein excretion (UKE), a serine protease of distal tubule origin in the normal animal was decreased but tissue kallikrein concentration (TK) was increased, suggesting intracellular accumulation. Severe morphological lesions were observed in proximal tubular cells which showed brush border damage, numerous vesicles, necrosis and liquefaction of cytoplasmic material. Less marked changes were also present in distal tubules: large apical vacuoles and swollen mitochondria. Compared to normal rats, using the peroxidase-anti-peroxidase (PAP) method for light microscopy, greater kallikrein immunoreactivity was detected along the apical pole in distal tubules, on the membrane and in the cytoplasm as well as in the glomerulus. By immunoelectron microscopy, kallikrein was found in the connecting apical area, along the luminal, basolateral and basement membranes, in some vesicles, in Golgi apparatus and on ribosomes bound to endoplasmic reticulum. In the glomerulus, kallikrein was observed along the luminal surface of endothelial cell. After 14 days a progressive recovery of renal function, tissue morphology and UKE towards control values was observed. The presence of immunoreactive kallikrein in the glomerulus observed only during ARF confirmed the previous demonstration of kallikrein mRNA in the glomerulus. The cellular accumulation results more likely from a dysfunction of a general secretory mechanism due to cell membrane alteration than from a specific inhibition of kallikrein production and secretion.

Biological assay for tissue kallikrein: comparison with the synthetic substrate S2266

A highly sensitive biological assay for tissue kallikrein is described, using human kininogen as substrate; and quantitation, by radioimmunoassay, of generated kinins. Using purified human urinary kallikrein as a reference standard we have correlated the kininogenase activity of kallikrein with amidase activity as measured by cleavage of the synthetic substrate S2266.

Renal functional reserve and microalbuminuria in offspring of hypertensive parents

Renal functional reserve, microalbuminuria, and plasma atrial natriuretic factor were measured in 21 offspring (9.5 +/- 0.5 years of age, mean +/- SEM) of hypertensive parents and in eight children (10 +/- 0.5 years of age) with no family history of hypertension who were used as a control group. Renal functional reserve was evaluated by measurement of the changes in creatinine clearance after an oral protein load of 45 g/m2. Atrial natriuretic factor levels were determined before and 60 minutes after the protein load, and microalbuminuria in fractional urine before and 120 minutes after the same stimulus as well as in a 24-hour urine collection. All children in the control group significantly increased their creatinine clearance after the protein load (preload, 122 +/- 12; 60 minutes, 144 +/- 9; 120 minutes, 154 +/- 11; 180 minutes, 144 +/- 9 ml/min/1.73 m2; all values were significant vs. preload, p less than 0.005). In contrast, only 13 of 21 offspring of hypertensive parents increased their creatinine clearance to values within 2 SD of the increase shown by the control group (preload, 144 +/- 11; 60 minutes, 153 +/- 7; 120 minutes, 202 +/- 13 ml/min/1.73 m2; p less than 0.001 vs. preload; 180 minutes, 214 +/- 19 ml/min/1.73 m2, p less than 0.001 vs. preload). The remaining eight offspring of hypertensive parents showed no detectable changes (nonresponders) (preload, 189 +/- 18; 60 minutes, 146 +/- 11; 120 minutes, 170 +/- 14; 180 minutes, 168 +/- 13 ml/min/1.73 m2; all values p = NS). No changes in atrial natriuretic factor after the protein load were observed in any group. Offspring of hypertensive parents presented higher microalbuminuria levels in 24-hour urine specimens (3.1 micrograms/min, tolerance factor [TF]2.2) than controls (2.1 micrograms/min, TF 1.5) (p less than 0.05). Although microalbuminuria increased significantly after the water load in the control group (p less than 0.05) and in the offspring of hypertensive parents (p less than 0.01), it returned to baseline at 120 minutes in the former but not in the latter (p less than 0.05 vs. baseline). The lack of renal functional reserve in nonresponders was significantly related (p less than 0.05) to the presence of higher levels of microalbuminuria. We conclude that the absence of renal functional reserve and increased microalbuminuria in some normotensive children who are offspring of essential hypertensive parents can indicate that subtle alterations in renal function may precede the onset of clinical hypertension.

Direct radioimmunoassay of active and inactive human glandular kallikrein: some physiological and pathological variabilities

We have developed a sensitive and specific radioimmunoassay which allows the detection of human glandular kallikrein in biologic fluids at a level of 40 pg/ml. The antisera did not recognize human plasma kallikrein and glandular kallikrein from other species including marmoset. Furthermore the antibody did not bind pro-kallikrein but was specific for the trypsin activated kallikrein. The antibody inhibited the kininogenase activity of standard kallikrein incubated with human kininogen. However active kallikrein inhibited by inhibitors bound at the active site is still detectable, indicating that the antibody is specific for the structure of the active form but not for the active site. In normotensive subjects, daily urinary kallikrein excretion increased with age until 30, then a decrease was observed. In renal transplanted recipients a progressive increase of the active form was found. A low concentration of immunoreactive active kallikrein was detected in lymphatic fluids of patients suffering from acute pancreatitis treated by lymphatic drainage; although this kallikrein is the active immunoreactive form, a very weak kininogenase activity was measured, suggesting a partial inhibition by anti-proteases. These data provide complementary evidence for the physiological and pathological role of glandular kallikrein.