Mariko Tamano

Glomerular Deposition and Urinary Excretion of Complement Factor H in Idiopathic Membranous Nephropathy

Background/Aims: The complement system plays an important role in the pathogenesis of membranous nephropathy (MN). In order to elucidate the regulatory mechanism of complement activation, we demonstrated glomerular deposition and urinary excretion of complement factor H, which controls the alternative pathway and the amplification loop at the C3 step, in patients with idiopathic MN. Methods: Renal biopsy specimens from 20 patients with idiopathic MN were studied immunohistochemically using monoclonal antibodies against complement components including factor H. SDS-PAGE and Western blotting analysis of urine samples were performed, and the urinary excretion of factor H and C5b-9 were measured by quantitative sandwich ELISA. Results: Intense glomerular deposition of factor H was observed with C3b·C3c and C5b-9 at an early stage of the disease. Factor H was detected in Western blots of urine samples, but factor H-like protein 1 (FHL-1) was not. The mean level of urinary factor H was elevated (86.30 ± 21.93 U/mg urinary creatinine) in comparison to that of normal controls (4.76 ± 1.03 U/mg urinary creatinine). Urinary factor H level exhibited no correlation with clinical parameters; however, a negative correlation was found between urinary C5b-9/factor H and creatinine clearance (r = 0.662, p < 0.01). Conclusion: The source of glomerular and urinary factor H is supposedly a 150-kD protein. There was no evidence to suggest that FHL-1 is synthesized at the site of inflammation. The urinary C5b-9 to urinary factor H ratio is indicative of the degree of ongoing complement activation in the glomeruli and complement-mediated renal injury. These findings suggest that factor H contributes to the control mechanism of in situ complement activation and prevents renal damage in idiopathic MN.

Urinary complement factor H in renal disease

Background: Complement factor H (hCFH) plays a key inhibitory role in the control of the alternative complement pathway. We examined whether urinary hCFH (U-hCFH) levels is useful as an indirect indicator of renal damage. Methods: Urine samples were obtained from 104 patients with renal disease. Urine was collected with 10 mM EDTA and U-hCFH levels were measured using the BTA TRAK Assay Kit. Results: In the 62 patients with nephritis, the levels of U-hCFH were elevated (range 15–52,198 U/ml) over the normal range (0–14 U/ml). U-hCFH levels of patients with chronic renal failure, lupus nephritis, membranoproliferative glomerulonephritis, focal glomerulosclerosis were higher than that of IgA nephropathy patients (p < 0.05). In the patients with minimal change disease, showed high levels of U-hCFH during the nephrotic syndrome. U-hCFH was correlated significantly with urinary protein and urinary N-acetyl-β-D-glucosaminidase. Conclusion: We demonstrated that U-hCFH was detected in the urine of nephritis patients.

Low CR1 (C3b Receptor) Level on Erythrocytes Is Associated with Poor Prognosis in Hemodialysis Patients

Background: Erythropoietin in patients under dialysis treatment for renal failure is low which induces anemia. Treatment with recombinant erythropoietin (rEPO) has been used routinely as a supplement treatment for these patients. Immune complexes (IC) react with complement and bind to CR1 on erythrocytes (E-CR1), and are transported to the liver and/or spleen where IC removal and degradation occurs. The erythrocytes then return to circulation where they bind to additional IC. There are some patients whose E-CR1 expression is low with chronic anemia in spite of rEPO treatment. We hypothesized that in hemodialysis (HD) patients altered host defense against infection is associated with low levels of E-CR1. We examined if low E-CR1 in dialysis patients constitutes a risk factor for reduced host defense and poor outcome. Methods: In 95 HD patients, E-CR1 was quantified using a monoclonal E-CR1 antibody and FACS analysis followed by clinical course studies for 5 years. Results: The patients were divided into three groups by E-CR1 level. Percent survival for the low E-CR1 group (53.3%) was significantly lower than the high E-CR1 group (86.4%) (p < 0.01). There were more hepatitis C virus-positive patients within the low E-CR1 group (27.3%) than in the high E-CR1 group (4.7%) (p < 0.05). Furthermore, 10 patients with the lowest E-CR1 levels had severe complications, notably infection at an arteriovenous fistula. Conclusion: A reduced E-CR1 level might be a risk factor for reduced host defense and can be used as a predicting factor for poor prognosis in a HD patient.

Evaluation of urinary decay accelerating factor and CD59 in renal damage

BackgroundDecay accelerating factor (DAF) and CD59 (protectin) are complement regulatory proteins that can be detected in soluble form in urine. We studied the relationship between renal disease and the mechanisms involved in the urinary excretion of complement regulatory proteins.MethodsUrine samples were obtained from 143 patients with renal disease and 61 individuals with normal renal function, who served as control subjects. As a model of limited tubular injury, we also studied the urine of 5 patients who were being treated with cisplatin for lung cancer; samples were collected before administration of the chemotherapeutic agents (day 0) and every morning during the observation period (15 days). Urinary DAF, CD59, and SC5b-9 (a complement component) were measured by enzyme-linked immunosorbent assay, using monoclonal antibodies.ResultsIn the patients with renal disease, urinary DAF and CD59 levels were higher than in healthy control subjects (P<0.001). The correlations between urinary DAF and CD59 levels were significant in patients with renal disease and healthy individuals (P<0.001). Urinary SC5b-9 was not correlated with either urinary DAF or CD59 in patients with IgA nephropathy. In the patients with lung cancer, urinary DAF and CD59 were elevated after the administration of cisplatin. This was accompanied by an increase in the secretion of urinaryN-acetyl-β-d-glucosaminidase and β2-microglobulin, both of which are markers for tubular injury.ConclusionThese results suggest that elevated levels of urinary DAF and CD59 are related to renal disease, as well as to the limited tubular injury associated with cisplatin treatment.

Decreased Apolipoprotein Levels Are Associated with Decreased Complement Levels in Acute Glomerulonephritis

Accessible online at: www.karger.com/journals/nef Dear Sir, While apolipoproteins (apo) A-I and A-II have been shown in vitro [1–3] to regulate the terminal complement component (TCC) in the complement pathway, no in vivo information is available regarding the association of apo A-I and apo A-II in serum with complement activation. We hypothesized that one of the mechanisms of decreased complement levels in patients with hypocomplementemic nephritis might be decreased apo A-I and apo A-II levels at the onset of the disease. Unlike patients with other hypocomplementemic nephritides who show intensive proteinuria with low complement levels, patients with acute poststreptococcal glomerulonephritis (AGN) have low C3 levels and activated TCC in serum and no heavy proteinuria. We think AGN is a good model to elucidate the relation between apo A-I and apo A-II and complement activation in vivo. C3 and C5 and apo A-I and apo A-II were analyzed by a single radial immunodiffusion method in serum samples from 16 patients within 20 days of onset of AGN, and the results were compared with those of 21 normal controls. Serum C3 and C5 were expressed as percentage of pooled serum samples of 40 normal adults. C3 for the controls was 105.2 B (SE) 4.1% and 16.1 B 2.3% for AGN patients (p ! 0.01). C5 was 95.4 B 2.1% for controls and 67.7 B 9.7% for AGN patients (p ! 0.01). Decreased C3 and C5 levels were associated with significantly decreased apo A-I and apo A-II levels in the samples from AGN patients (p ! 0.01). Apo A-I for controls was 152.7 B 3.9 mg/dl and 118.9 B 7.2 mg/dl for AGN patients. Apo A-II was 36.2 B 0.8 mg/dl for controls and 28.9 B 1.7 mg/ dl for AGN patients. Although the decrease in apo A-II was significant, it was small as compared with the change in apo A-I. In addition to AGN samples, apo A-I and apo A-II were measured in eight samples