Complement activation products in the circulation and urine of primary membranous nephropathy.

BACKGROUND: Complement activation plays a substantial role in the pathogenesis of primary membranous nephropathy (pMN). C5b-9, C3c, MBL, and factor B have been documented in the subepithelial immune deposits. However, the changing of complement activation products in circulation and urine is not clear. METHODS: We measured the circulating and urinary levels of C1q, MBL, C4d, Bb, properdin, C3a, C5a, and sC5b-9, in 134 patients with biopsy-proven pMN, by enzyme-linked immunosorbent assay. All the plasma values were corrected by eGFR and all the urinary values were corrected by urinary creatinine and urinary protein excretion. Anti-PLA2R antibodies were measured in all patients. RESULTS: The plasma complement activation products were elevated both in the patients with and without anti-PLA2R antibodies. C3a levels were remarkably increased in the circulation and urine, much higher than the elevated levels of C5a. C5b-9 was in normal range in plasma, but significantly higher in urine. The urinary C5a had a positive correlation with anti-PLA2R antibody levels and urinary protein. The plasma level of C4d was elevated, but C1q and MBL were comparable to healthy controls. Positive correlations were observed between plasma C4d/MBL and urinary protein, only in the patients with positive anti-PLA2R antibodies but not in those without. The plasma level of Bb was elevated and had positive correlation with urinary protein only in the patients without anti-PLA2R antibodies. CONCLUSION: Complement activation products were remarkable increased in pMN and may serve as sensitive biomarkers of disease activity. The complement may be activated through lectin pathway with the existence of anti-PLA2R antibodies, while through alternative pathway in the absence of antibody.

Absence of C4d urinary excretion in the early post-transplant period is associated with improved long-term kidney graft survival.

INTRODUCTION: C4d urinary excretion varies according to the risk of graft rejection or progression of chronic allograft nephropathy, but its influence on long-term kidney transplant (KTx) outcomes remains unclear. The aim of the study was to determine whether the initial (1-3 months post KTx) level of C4d urinary excretion may help to predict long-term kidney allograft transplantation outcomes. MATERIALS AND METHODS: The study involved 185 patients who had undergone KTx. The urinary specimens taken from the morning urine portion were assessed by ELISA test for C4d excretion. To increase the objectivity of the assessment, all measurements were divided by urinary creatinine excretion (ng/mgCr). The study population was grouped according to the C4d excretion cut-off value into low (LC4d, 109 participants) and high (HC4d, 76 participants) C4d excretion groups. Additionally a subgroup with absence of C4d in the urine (ZC4d, 26 patients) was formed. RESULTS: The calculated Roc curve indicated the cut off value of the urinary C4d excretion as 12.4ng/mgCr (AUC 0.77; 95%CI 0.73-0.95). The mean C4d urinary excretions in LC4d and HC4d were 1.9±3.27 and 20.6±4.6ng/mgCr, respectively, whereas after exclusion of ZC4d subgroup, the mean C4d was 14.9±6.3ng/mgCr in the remainder. Kaplan-Meier curve analysis demonstrated a slightly higher graft survival rate (GSR) in LC4d than in HC4d group (p=0.04 by log-rank). The subsequent analysis showed the highest GSR in ZC4d subgroup (p=0.0006 by log-rank). CONCLUSION: Although lower C4d urinary excretion in the early post-transplant period seems to be associated with better long-term kidney allograft transplantation outcomes, only its absence in the urine appears to be a solid predictor of improved graft survival.

Biomarkers and updates on pediatrics lupus nephritis.

Lupus nephritis is a common complication of systemic lupus erythematosus in children and adolescents. This article reviews the clinical relevance of lupus nephritis and its current treatment. The reader is introduced to novel biomarkers that are expected to improve the management of lupus nephritis in the future, and support the testing of novel medication regimens.

Non-invasive monitoring of renal transplant recipients: urinary excretion of soluble adhesion molecules and of the complement-split product C4d.

BACKGROUND: The number of inducible adhesion molecules known to be involved in cell-mediated allograft rejection is still increasing. In addition, recent data describe complement activation during acute humoral allograft rejection. The aim of this study was to assess whether specific molecules from either pathway are excreted into urine and whether they can provide useful diagnostic tools for the monitoring of renal transplant recipients. METHODS: Urinary concentrations of soluble adhesion molecules (sICAM-1, sVCAM-1) and of the complement degradation product C4d were determined by standardized ELISA technique in 75 recipients of renal allografts and 29 healthy controls. Patient samples were assigned to four categories according to clinical criteria: GROUP 1: acute steroid-sensitive rejection (ASSR, n = 14), GROUP 2: acute steroid-resistant rejection (ASRR, n = 12), GROUP 3: chronic allograft dysfunction (CAD, n = 20) and GROUP 4: stable graft function (SGF, n = 29). RESULTS: All patients with rejection episodes (groups 1-3) had significantly higher values of urinary sC4d compared with healthy controls and patients with stable graft function (p < 0.05). The urinary levels of sVCAM-1 were significantly higher in group 2 (ASRR) compared with all other groups (p < 0.001). Uniformly low amounts of s-VCAM-1 and complement-split product C4d were excreted by healthy controls (group 0). In contrast, urinary sICAM-1 concentration in healthy controls was almost as high as in group 2 (ASRR) whereas patients with a stable functioning graft (group 4) excreted significantly less sICAM-1 (p < 0.05). CONCLUSION: The evaluation of sVCAM-1 and sC4d excretion in urine can provide a valuable tool with regard to the severity and type of allograft rejection. With respect to long-term allograft survival, serial measurements of these markers should have the potential to detect rejection episodes and prompt immediate treatment.

[Protein markers in evaluation of nephroprotective effects of antihypertensive drugs in patients with arterial hypertension]. / Belkovye markery otsenki nefroprotektivnogo deistviia gipotenzivnykh sredstv u bol'nykh s arterial'noi gipertoniei.

Fifty patients with stable slight and moderate uncomplicated essential hypertension, treated by ramipril, atenolol, or isradipine, were examined. Total protein and urinary excretion of individual proteins were studied before and after treatment. Urinary concentrations of apolipoproteins A1 and B1, alpha 1-acid glycoprotein, alpha 1-antitrypsin, prealbumin, albumin, beta 2-microglobulin, transferrin, haptoglobin, IgG and IgA, and C3 and C4 complement components were measured. Index of proteinuria selectiveness was calculated for each portion of urine. All three drugs exerted a nephroprotective effect, atenolol being the most active of them. Apolipoproteins, IgG, and complement components were the most valuable for diagnosis. Their excretion correlated with the severity of arterial hypertension and efficiency of treatment. Use of protein markers helps reliably assess the renal function and monitor the treatment efficiency.

[Immune complexes and C3 and C4 of the complement in urine of patients with glomerulonephritis]. / Kompleksy immunologiczne oraz C3 I C4 dopelniacza w moczu chorych na klebuszkowe zapalenia nerek.

The circulating immune complexes (CIC), urinary immune complexes (UIC), C3 and C4 in urine (UC3 and UC4) in 99 patients with immunologic glomerular diseases: 13 with extracapillaris GN (ExGN), 38 with membranoproliferative GN (MPGN), 33 with mesangial proliferative GN (MesPGN), 5 with focal segmental glomerulosclerosis (FSGS), 5 with membranous nephropathy (MN), and 3 with minimal change nephropathy (MC) were investigated in the study. Depending on the (IS) immunosuppressive treatment all patients were classified into 3 groups. Group I: 61 recently biopsied patients with glomerular disease consisted of patients attending our renal department, group II: 24 patients with biopsy proven glomerular disease IS treated in the past but with GN with restrained disease activity, group III: 14 patients with active glomerulopathy who have been treated for some months. Nephelometry C1q binding test was used for CIC detection and 3.5% polyethylene glycol precipitate for its detection in urine by C1q binding test was applied. Radial immunodiffusion (NANORID) method was used for urine C3 and C4 detection. UC3 were detected in urine from 37% of all patients: in 39% patients of group I (GN at time of diagnosis), 38% of group II (GN with restrained disease activity) and 36% of group III (active GN received immunosuppressive therapy for several months). It suggest that nonimmunological-mechanism induce C3 detected in the rine of such patients. According to histological findings UC3 was detected in 3 patients with ExGN of group I, in patient with ExGN of group II and in about half patients with MPGN from group I and II, in about 25% patients with MesPGN from group I and II. About half patients with MesPGN of group III, one patient with MPGN of group III and a few patients with other histological findings of group I were UC3 positive. Simultaneous excretion of C4 in urine was detected in some UC3 positive patients (in about 5% patients). At the same time in about 50% UC3 positive patients was observed urinary excretion of IC. CIC and UIC were detected in 25% of all patients: in 29% of group I, in 17% of group II, and in 29% patients of group III. According to histological findings CIC was detected in 3 patients with ExGN, in 7 patients with MPGN from 26 of group I, and 3 from 7 with MPGN of group II, and 3 patients with MesPGN of group I and 1 patients with MesPGN of group II, and 33% patients with MesPGN of group III with high proteinuria. These findings suggested that urinary IC reflected the immunological activity of glomerulopathy and their presence in patients urine after IS treatment suggests incomplete response to this therapy while urinary C3 and C4 were connected with urinary protein excretion and may be of importance in tubulointerstitial injury and progression of renal insufficiency.

Urinary C4 excretion in systemic lupus erythematosus.

The fourth component of complement (C4) in urine was measured in 19 patients with systemic lupus erythematosus (SLE). Urinary C4 was detectable in all SLE patients using an enzyme linked immunosorbent assay. In 11 of 13 patients whose urinary C4 was serially measured, a decrease of urinary C4 was found in parallel with a decrease of disease activity of SLE. In the remaining 2 patients, the amount of C4 increased preceding a flare-up of the disease. The measurement of urinary C4 may be useful in evaluating the disease activity of SLE in individual patients and sometimes in predicting the flare-up of the disease. The specific hemolytic activity of excreted C4 and Western blotting analysis showed that urinary C4 consisted mainly of degraded fragments of C4. In two cases, camostat, a serine protease inhibitor, rapidly decreased the urinary C4 excretion, suggesting that the complement activation occurred in the glomerulus in lupus nephritis.

Assessment of soluble adhesion molecules (sICAM-1, sVCAM-1, sELAM-1) and complement cleavage products (sC4d, sC5b-9) in urine. Clinical monitoring of renal allograft recipients.

Increasing evidence exists that inducible adhesion molecules are involved in cell-mediated allograft rejection. In addition, complement activation during rejection has been described. This study investigated, whether specific molecules derived from either pathway are excreted into urine during rejection and whether they can provide useful diagnostic tools for the monitoring of renal transplant recipients. Urinary concentrations of soluble adhesion molecules (sICAM-1, sVCAM-1, sE-selectin) and of complement cleavage products (sC4d and sC5b-9), were determined by standardized ELISA in 30 normal controls and 80 samples from 49 recipients of renal allografts. In contrast to the low amounts of adhesion molecules and complement components uniformly excreted by healthy persons (group 0), marked differences were observed among allograft recipients. To prove the clinical relevance of these differences in excretion, patient samples were assigned to 5 categories according to clinical and histopathological criteria: group I--acute steroid-resistant rejection (n = 10); group II--acute steroid-sensitive rejection (n = 10); group III--chronic rejection (n = 23); group IV--stable graft function (n = 27); and group V--miscellaneous disorders (n = 10), including infections, CsA overdoses, and glomerulonephritis. Urinary levels of sICAM-1, sVCAM-1, and sC4d were significantly higher in group I compared with all other groups (P < 0.01). The difference in sICAM-1 excretion between groups III and IV also reached statistical significance (P < 0.05). Urinary concentrations of sICAM-1, sVCAM-1, and sC4d were reflective of their histological distribution in corresponding graft biopsies. None of the patients excreted E-selectin in detectable amounts. Excretion of the terminal membrane attack complex C5b-9 was not significantly associated with any diagnosis. It is concluded that for clinical purposes the combined evaluation of sICAM-1, sVCAM-1, and sC4d is most useful and can provide valuable information with regard to the severity and the type of allograft rejection.