Soluble C5b-9 Research Articles

Complement Activation in Human Sepsis is Related to Sepsis-Induced Disseminated Intravascular Coagulation.

In human sepsis, little is known about the relationships between complement activation and the clinical characteristics of sepsis, including disseminated intravascular coagulation (DIC), interventions, and prognosis. Adult patients with sepsis admitted from November 2016 to December 2018 were included. We used the plasma levels of soluble C5b-9 (SC5b-9) as a marker of complement activation. We compared the clinical characteristics and complement components between patients with and without DIC. We also compared the clinical characteristics and each DIC parameter across quartile groups for the SC5b-9 value. Forty-nine sepsis patients were eligible. Thirty-four patients developed DIC, and eight patients died. The median (interquartile range) SC5b-9 value was 342 (261-501) ng/mL. Compared with patients without DIC, patients with DIC showed lower C3 levels (mean, 95.7 vs. 70.4 mg/dL, P < 0.01) and higher SC5b-9 levels (median, 287 vs. 400 ng/mL, P = 0.01). Patients were stratified by SC5b-9 quartile (ng/mL: low: < 260, moderate: 260-342, high: 343-501, highest: > 501). The mean Sequential Organ Failure Assessment score varied across these groups (P = 0.02). In the high and highest groups, many more patients received vasopressors and developed DIC. In the highest group, the coagulation parameters were severe, and thrombocytopenia was prolonged. In-hospital mortality tended to be high (33%) in the highest group. The degree of complement activation is related to DIC, severity, intensive interventions, and mortality. Further studies are needed to confirm the usefulness of SC5b-9 for stratifying sepsis patients.

Easix Is Strongly Associated with Complement Activation and Overall Survival in Adult Allogeneic Hematopoietic Cell Transplantation Recipients

Introduction: Endothelial dysfunction is a common denominator of graft-versus-host disease (GVHD) and transplant-associated thrombotic microangiopathy (TA-TMA). The latter is also characterized by excessive complement activation. Recent studies have introduced the Endothelial Activation and Stress Index (EASIX) as a potential predictor of survival in patients with GVHD. We hypothesized that EASIX would predict complement activation and survival in patients with GVHD and TA-TMA. Methods: We enrolled consecutive adult TA-TMA (International Working Group/IWG criteria), acute and/or chronic GVHD and control allogeneic hematopoietic cell transplantation (HCT) recipients in a 1:1:1 ratio (January 2015-December 2018). Plasma was collected and stored immediately at -80oC at the first day of confirmed TA-TMA or GVHD diagnosis and at a similar post-transplant period in control recipients. EASIX [lactate dehydrogenase (U/L) × creatinine (mg/dL)/thrombocytes (10⁹ cells per L)] was calculated at day 0, 30, 100 and last follow-up. Complement activation was detected measuring soluble C5b-9/membrane attack complex (ELISA, Quidel). Results: We studied 20 TA-TMA, 20 GVHD and 20 control patients (Table 1). TA-TMA developed at a median of 125 post-transplant day (range 9-2931); whereas the first day of confirmed GVHD diagnosis was at a median of 78 post-transplant day (range 16-145). EASIX at day 100 and last follow-up differed significantly among groups (p=0.014 and p=0.001, Table 1), although there was no significant difference between TA-TMA and GVHD patients. In contrast, soluble C5b-9 was significantly higher in TA-TMA compared to GVHD (p=0.008) and control patients (p&lt;0.001, Bonferroni's correction). Soluble C5b-9 levels were strongly associated with EASIX at day 100 and last follow-up (r=0.318, p=0.018 and r=0.321, p=0.020). Among laboratory values used to calculate EASIX (LDH, creatinine, platelets), C5b-9 was associated only with creatinine levels at day 100 (r=0.316, p=0.023), suggesting that the association between EASIX and C5b-9 is not driven by laboratory values per se. Furthermore, EASIX at day 0 and last follow-up was significantly associated with overall survival (p=0.013 and p=0.046). Among other pre-transplant factors studied (age, disease type and phase at transplant, donor), EASIX at day 0 was an independent predictor of overall survival (beta=2.627, p=0.029). Conclusion: Our study shows for the first time that EASIX predicts complement activation and overall survival in patients with endothelial dysfunction syndromes and control HCT recipients. Our findings suggest that EASIX may be a useful dynamic marker reflecting the course of endothelial dysfunction in these patients. Disclosures No relevant conflicts of interest to declare.

Soluble C5b-9 As a Prognostic Biomarker for Thrombotic Microangiopathy at the Onset of Graft-Versus-Host Disease

Schmidt: Kypha Inc: Employment, Equity Ownership. Lee:Incyte: Research Funding; Syndax: Research Funding; Amgen: Research Funding; Novartis: Research Funding; Takeda: Research Funding; Kadmon: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; AstraZeneca: Research Funding.

Urinary Properdin and sC5b-9 Are Independently Associated With Increased Risk for Graft Failure in Renal Transplant Recipients.

The pathophysiology of late kidney-allograft failure remains complex and poorly understood. Activation of filtered or locally produced complement may contribute to the progression of renal failure through tubular C5b-9 formation. This study aimed to determine urinary properdin and sC5b-9 excretion and assess their association with long-term outcome in renal transplant recipients (RTR).Methods: We measured urinary properdin and soluble C5b-9 in a well-defined cross-sectional cohort of RTR. Urinary specimens were taken from a morning urine portion, and properdin and sC5b-9 were measured using an enzyme-linked-immunosorbent assay (ELISA). Cox proportional hazard regression analyses were used to investigate prospective associations with death-censored graft failure.Results: We included 639 stable RTR at a median [interquartile range] 5.3 (1.8–12.2) years after transplantation. Urinary properdin and sC5b-9 excretion were detectable in 161 (27%) and 102 (17%) RTR, respectively, with a median properdin level of 27.6 (8.6–68.1) ng/mL and a median sC5b-9 level of 5.1 (2.8–12.8) ng/mL. In multivariable-adjusted Cox regression analyses, including adjustment for proteinuria, urinary properdin (HR, 1.12; 95% CI 1.02–1.28; P = 0.008) and sC5b-9 excretion (HR, 1.34; 95% CI 1.10–1.63; P = 0.003) were associated with an increased risk of graft failure. If both urinary properdin and sC5b-9 were detectable, the risk of graft failure was further increased (HR, 3.12; 95% CI 1.69–5.77; P < 0.001).Conclusions: Our findings point toward a potential role for urinary complement activation in the pathogenesis of chronic allograft failure. Urinary properdin and sC5b-9 might be useful biomarkers for complement activation and chronic kidney allograft deterioration, suggesting a potential role for an alternative pathway blockade in RTR.

Measuring Circulating Complement Activation Products in Myeloperoxidase- and Proteinase 3-Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

There is accumulating evidence that complement activation is important in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) pathogenesis. This study was undertaken to investigate complement activation in AAV with myeloperoxidase (MPO) positivity and AAV with proteinase 3 (PR3) positivity after determining optimal methods for measuring activated complement factors in circulation. Participants included 98 patients with AAV (45 MPO-ANCA positive, 53 PR3-ANCA positive) and 35 healthy controls. Plasma was obtained from blood collected using EDTA tubes, with or without 100 μg/ml Futhan. Levels of Bb, C3a, C5a, soluble C5b-9 (sC5b-9), properdin, and C4d were measured by enzyme-linked immunosorbent assay. Group comparisons were made using Wilcoxon's 2-sample test. Paired data were analyzed using a matched pairs signed rank test. Compared to healthy controls, certain complement analyte levels were high in patients with active AAV with MPO positivity, including C3a (P < 0.0001), C5a (P = 0.0004), and sC5b-9 (P = 0.0007). During remission, levels of Bb (P = 0.001), C3a (P < 0.0001), and sC5b-9 (P = 0.003) were higher. Compared to healthy controls, C3a (P < 0.0001), C5a (P = 0.002), sC5b-9 (P = 0.0001), and C4d (P = 0.005) levels were higher in patients with active AAV with PR3 positivity; levels of C3a (P < 0.0001) and C4d (P = 0.007) were also higher duriing remission. There were no significant differences in any complement analyte for either ANCA serotype between patients with active disease and those with disease in remission. Among patients with paired samples, sC5-9 levels were significantly lower during disease remission compared to active disease. C5a was significantly lower among patients with disease in long-term remission who were not receiving therapy. For Bb, C5a, and sC5b-9, median levels and individual values were considerably higher in control and patient samples processed without Futhan compared to those processed with Futhan. Complement activation occurs in both MPO-positive AAV and PR3-positive AAV. The complement activation profile differs according to disease activity and possibly ANCA serotype. Futhan reduces in vitro complement activation and provides a more accurate measurement.

Diagnostic roles of urinary kidney injury molecule 1 and soluble C5b-9 in acute tubulointerstitial nephritis.

Acute tubulointerstitial nephritis (ATIN) is a common cause of acute kidney injury characterized by inflammatory cells infiltrating in the interstitium. The present study aimed to explore noninvasive biomarkers that might indicate activity of pathological injuries and help direct treatment. Fifty-four patients with clinical-pathologically diagnosed ATIN from January 1, 2014, to June 30, 2016, at Peking University First Hospital were enrolled. Urine samples were collected on the morning of renal biopsy and assessed for urinary kidney injury molecule-1 (KIM-1) and urinary soluble C5b-9 (sC5b-9). Immunofluorescence staining for KIM-1 and C5b-9 was performed in biopsied kidney sections from ATIN cases. The clinical and pathological relevance of the two urinary biomarkers was analyzed. Both urinary KIM-1 and sC5b-9 values were significantly elevated in patients with ATIN compared with healthy controls. The urinary KIM-1 level positively correlated with urinary N-acetyl-β-d-glucosaminidase (r = 0. 542, P = 0.001) and the pathological tubular injury score (r = 0.469, P < 0.001), whereas the urinary sC5b-9 level was related to pathological activity scores for tubular injury (r = 0.413, P = 0.002), interstitial inflammation (r = 0.388, P = 0.004), and treatment response (r = 0.564, P < 0.001). Urinary KIM-1 tended to have better diagnostic value for tubular injury than urinary sC5b-9, whereas only urinary sC5b-9 was able to demonstrate severe interstitial inflammation. A combination of urinary KIM-1 and sC5b-9 had an area under the receiver-operating characteristic curve of 0.864 (95% confidence interval: 0.766-0.963, P < 0.001, sensitivity: 75%, specificity: 88%) for acute tissue injury in ATIN. KIM-1 expression was markedly increased in renal tubular cells in both ATIN and acute tubular necrosis conditions, whereas a significant upregulation of C5b-9 was only detected in the tubular cells and interstitial cells in ATIN cases. Urinary KIM-1 is a specific biomarker for renal tubular injury in ATIN, whereas urinary sC5b-9 is valuable in demonstrating severe interstitial inflammation. The combination of these two biomarkers helps identify patients at an acute injury stage and, therefore, might facilitate clinical evaluation and guide immunosuppressive therapy.

Early complementopathy predicts the outcomes of patients with trauma

BackgroundComplementopathy (rapid complement activation and consumption after trauma) has been reported in trauma patients, but the underlying mechanism of these phenomena and their clinical significance remain unclear. This study aimed...

Study on Immunophenotypes and Gene of Acute Lymphoblastic Leukemia--Review

Transplantation-associated thrombotic microangiopathy (TA-TMA) is one of the fatal complications of hematopoietic stem cell transplantation(HSCT). The pathogenesis of TA-TMA has not been fully elucidated. The latest researches show that the abnormal activation of the complement system may lead to widespread endothelial injury which may play an important role in the pathogenesis of this disease. Incontrotable hypertension, proteinuria, increase of soluble C5b-9 concentration and early pericardial effusion are the risk factors of TA-TMA . In this review, the latest advances of pathogenesis, early diagnosis, treatment and other aspects of the progress of TA-TMA are summarized, so as to provide new ideas to early diagnosis and treatment in TA-TMA.

Complement activation in acute myocardial infarction: An early marker of inflammation and tissue injury?

BackgroundAcute myocardial infarction (AMI) is a potentially fatal condition, being a major cause of death worldwide. Ischemia suffered during AMI causes tissue damage, leading to an inflammatory process. Moreover, myocardial injury can generate damage-associated molecular patterns that activate pattern recognition molecules including some complement proteins. MethodsHere we investigated products of complement activation, C3d and soluble C5b9 (sC5b9), as potential biomarkers for myocardial injury and inflammation, as well as serum cytokines (IL-6 and TNF-alpha), alpha-1-acid glycoprotein (AGP), and classical markers of myocardial necrosis (creatine kinase, creatine kinase-MB isoform, myoglobin and troponin-I) in a longitudinal study of patients with AMI (from admission, 6 h and 12 h post admission, and at discharge from hospital). Individuals undergoing cardiac catheterization (CC) with normal coronary arteries and asymptomatics with no history of cardiovascular disease or invasive procedures were included as controls. ResultsPlasma C3d was higher in AMI at admission, 6 h, 12 h, and discharge vs CC (p < 0.0001; p = 0.0061; p = 0.0081; p = 0.044) and asymptomatic (p = 0.0001 for admission, 6 h and 12 h; p = 0.0002 for discharge). Moreover, sC5b9 was higher only at admission and 6 h vs asymptomatic (p = 0.0031 and p = 0.0019). Additionally, AGP levels were elevated at admission, 6 h, 12 h, and discharge vs asymptomatic (p = 0.0003; p = 0.0289; p = 0.0009, p = 0.0017). IL-6 concentration was low at admission and 6 h and reached a peak at 12 h (p < 0.0001 for all groups). All classical markers of myocardial necrosis presented higher concentration at 6 h. ConclusionsOur results showed that complement activation is an early event in AMI occurring before the elevation of classical markers of myocardial necrosis such as creatine kinase, creatine kinase-MB isoform, myoglobin and troponin-I. These findings indicated C3d and sC5b9 as possible biomarkers for inflammation and tissue damage in AMI.

Complement activation in patients with diabetic nephropathy

AimEmerging evidence has indicated a role of the complement system in the pathogenesis of diabetic nephropathy (DN), although the pathways of complement activation and their clinicopathological relevance in DN are as yet unclear. The present study aimed to investigate levels of various complement components in plasma and urine of DN patients, and their correlation with clinicopathological parameters. MethodsA total of 68 biopsy-proven DN patients with plasma samples were recruited, including 50 patients who also had urine samples available. Seven complement components (C1q, MBL, Bb, C4d, C3a, C5a, soluble C5b-9) were measured by enzyme-linked immunosorbent assay (Elisa), and any associations between their levels and clinicopathological parameters were then investigated. ResultsIn DN patients, plasma levels of C1q, MBL, Bb, C4d, C3a, C5a and sC5b-9 were significantly higher than in diabetes patients without renal involvement, as were also urinary levels except for C1q, which showed no significant differences between the two groups. Also, urinary levels of C3a and C5a were significantly correlated with serum creatinine, urinary protein and estimated glomerular filtration rate, whereas urinary sC5b-9 was significantly correlated with the latter two (and not serum creatinine). In addition, urinary levels of MBL, Bb and C4d were significantly correlated with urinary protein, while C3a, C4d and Bb significantly correlated with the classification of glomerular lesions in DN. ConclusionIn DN patients, the complement system is activated and, of the three possible complement pathways, activation of the lectin and alternative pathways is associated with renal damage.

Patterns of Clinical Response to Eculizumab in Patients With C3 Glomerulopathy

Cases reports and small series of patients with C3 glomerulopathy have reported variable efficacy of eculizumab. Case series of C3 glomerulopathy. Pediatric and adult patients with C3 glomerulopathy treated with eculizumab between 2010 and 2016 were identified through the C3 glomerulopathy French registry database, and a questionnaire was sent to participating French pediatric and adult nephrology centers, as well as one pediatric referral center in Québec, Canada. Global or partial clinical renal response. Evolution of serum creatinine and proteinuria values. 26 patients (13 children/adolescents) were included. 22 (85%) patients had received steroids, plasma exchange, or immunosuppressive therapy before eculizumab, and 3 of them had rapid progression of their kidney disease despite treatment. At the initiation of eculizumab therapy, 11 (42%) patients had chronic kidney disease, 7 (27%) had rapidly progressive disease, and 3 (12%) required dialysis. After eculizumab treatment (median duration, 14 months), 6 (23%) patients had a global clinical response; 6 (23%), a partial clinical response; and 14 (54%), no response. Compared with those who had a partial clinical or no response, patients who had a global clinical response had lower estimated glomerular filtration rates, a more rapidly progressive course, and more extracapillary proliferation on kidney biopsy. Age, extent of renal fibrosis, frequency of nephrotic syndrome, low serum C3 and C3 nephritic factor and elevated soluble C5b-9 concentrations, or complement gene variants did not differ between responders and nonresponders. Retrospective design without a control group, relatively small number of cases, inclusion of pediatric and adult cases. Eculizumab appears to be a potential treatment for patients with crescentic rapidly progressive C3 glomerulopathy. Its benefit in patients with non-rapidly progressing forms seems to be limited.

Pathogenic role of inflammatory response during Shiga toxin-associated hemolytic uremic syndrome (HUS).

Hemolytic uremic syndrome (HUS) is defined as a triad of noninmune microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. The most frequent presentation is secondary to Shiga toxin (Stx)-producing Escherichia coli (STEC) infections, which is termed postdiarrheal, epidemiologic or Stx-HUS, considering that Stx is the necessary etiological factor. After ingestion, STEC colonize the intestine and produce Stx, which translocates across the intestinal epithelium. Once Stx enters the bloodstream, it interacts with renal endothelial and epithelial cells, and leukocytes. This review summarizes the current evidence about the involvement of inflammatory components as central pathogenic factors that could determine outcome of STEC infections. Intestinal inflammation may favor epithelial leakage and subsequent passage of Stx to the systemic circulation. Vascular damage triggered by Stx promotes not only release of thrombin and increased fibrin concentration but also production of cytokines and chemokines by endothelial cells. Recent evidence from animal models and patients strongly indicate that several immune cells types may participate in HUS physiopathology: neutrophils, through release of proteases and reactive oxygen species (ROS); monocytes/macrophages through secretion of cytokines and chemokines. In addition, high levels of Bb factor and soluble C5b-9 (sC5b-9) in plasma as well as complement factors adhered to platelet-leukocyte complexes, microparticles and microvesicles, suggest activation of the alternative pathway of complement. Thus, acute immune response secondary to STEC infection, the Stx stimulatory effect on different immune cells, and inflammatory stimulus secondary to endothelial damage all together converge to define a strong inflammatory status that worsens Stx toxicity and disease.

A model to study complement involvement in experimental retinal degeneration

Background: The complement system (CS) plays a role in the pathogenesis of a number of ocular diseases, including diabetic retinopathy (DR), glaucoma, uveitis, and age-related macular degeneration (AMD). Given that many of the complex eye-related degenerative diseases have limited treatment opportunities, we aimed to mimic the in vivo retinal degenerative process by developing a relevant co-culture system.Method and materials: The adult porcine retina was co-cultured with the spontaneously arising human retinal pigment epithelial cells-19 (ARPE-19).Results: Inflammatory activity was found after culture and included migrating microglial cells, gliosis, cell death, and CS activation (demonstrated by a minor increase in the secreted anaphylotoxin C3a in co-culture). CS components, including C1q, C3, C4, soluble C5b-9, and the C5a receptor, were expressed in the retina and/or ARPE cells after culture. C1q, C3, and CS regulators such as C4 binding protein (C4BP), factor H (CFH), and factor I (CFI) were secreted after culture.Discussion: Thus, our research indicates that this co-culturing system may be useful for investigations of the CS and its involvement in experimental neurodegenerative diseases.

USING EMERGING CEREBROSPINAL FLUID MARKERS TO CHARACTERIZE SUSPECTED NON-ALZHEIMER’S DISEASE PATHOPHYSIOLOGY (SNAP) IN INDIVIDUALS WITH MILD COGNITIVE IMPAIRMENT

The underlying pathophysiology of individuals with suspected non-Alzheimer's disease pathophysiology (SNAP; biomarker profile with neuronal injury without amyloid pathology) is to date still unclear. Our aim was to investigate the role of inflammation and lipid transport in individuals with mild cognitive impairment (MCI) and SNAP using emerging markers in cerebrospinal fluid (CSF). We selected 77 subjects with MCI and 15 cognitively normal (CN) subjects from the European EDAR study. We measured C3a (central to the classical, alternative and lectin complement pathways), the soluble C5b-9 terminal complement complex (TCC), amyloid binding proteins heart-fatty acid binding protein (HFABP), amyloid beta(Aβ)1–42, total tau (t-tau), and phosphorylated tau (p-tau) in CSF, and serum amyloid P (SAP, an acute response protein which activates complement). CN subjects had normal Aβ1–42 and tau. MCI subjects were classified as having low AD likelihood (n=18, normal Aβ1–42 and tau), SNAP (n=14, normal Aβ1–42 and abnormal tau), isolated amyloid pathology (IAP n=18; abnormal Aβ1–42 and normal tau), or high AD likelihood (n=27, abnormal Aβ1–42 and tau). We compared MCI subgroups using ANOVA and correlated emerging and core CSF Alzheimer's disease markers using Spearman (rho). CN individuals had higher levels of C3a than all MCI groups. Individuals with MCI-SNAP and MCI-high AD likelihood had higher levels of HFABP compared to those with MCI-low AD likelihood and MCI-IAP. Individuals with MCI-high AD likelihood had also higher levels of HFABP than CN individuals (see Table 1). In individuals with MCI, C3a correlated with p-tau (r=0.311, p=0.025), and HFABP correlated with Aβ1–42 (r=-0.242, p=0.034), t-tau (r=0.641, p<0.001) and p-tau (r=0.489, p<0.001). Our findings suggest that inflammation plays a similar role in neurodegeneration within all MCI subgroups. Moreover, HFABP levels are related to overall tau-related neurodegeneration in individuals with MCI.

Proteomic Profiling Analysis Reveals a Link between Experimental Autoimmune Uveitis and Complement Activation in Rats

Uveitis is an autoimmune disease that usually damages the vision function, leading to poor visual quality in patients. As an autoimmune ocular inflammatory disease, the pathogenesis of uveitis is associated with abnormal expression of some proteins and aberrant regulation of multiple signalling pathways. Nevertheless, the detailed mechanism remains unclear. In this study, we induced an experimental autoimmune uveitis (EAU) model in rats. We determined the levels of C3a and membrane attack complex C5b-9 (soluble C5b-9, sC5b-9) in both plasma and aqueous humour, identified the differentially expressed proteins in plasma by liquid chromatography-tandem mass spectrometry and employed bioinformatics algorithms to analyse differentially expressed proteins in EAU rat plasma. The results demonstrate that there were 168 differentially expressed plasma proteins in EAU rats versus control subjects. The levels of sC5b-9 and C3a were elevated in the plasmas and aqueous humours of EAU rats. Gene ontology enrichment analysis showed that the differentially expressed proteins in EAU rat plasma were mainly involved in metabolic and immune processes. Kyoto encyclopedia of genes and genomes (KEGG) pathway annotation, database for annotation, visualization and integrated discovery (DAVID) and protein-protein interaction analyses revealed that the differentially expressed proteins in EAU rat plasmas were closely associated with complement and coagulation cascades, metabolic pathways, NF-kappa B, PI3K-Akt, Toll-like receptors and autophagy. Overall, the differentially expressed proteins in EAU rat plasmas are mainly involved in the complement and coagulation cascades. The pathogenesis of uveitis closely correlates with complement activation.

Treatment of B-cell disorder improves renal outcome of patients with monoclonal gammopathy–associated C3 glomerulopathy

AbstractThe high frequency of monoclonal gammopathy in adult patients with C3 glomerulopathy (C3G) emphasizes the role of monoclonal immunoglobulin (MIg) in the occurrence of renal disease and raises the issue of the therapeutic management. The aim of the study was to evaluate the effect of chemotherapy in a large cohort of patients with MIg-associated C3G. Fifty adult patients with MIg and biopsy-proven C3G were extracted from the French national database of C3G. We retrospectively compared renal outcomes in patients who either received or did not receive chemotherapy targeting the underlying B-cell clone. At diagnosis, renal disease was severe, with nephrotic-range proteinuria in 20/46 (43%) patients and chronic kidney disease stage 3 or above in 42/49 (86%) patients. Monoclonal gammopathy was of IgG type in 47 (94%) patients. Hematological diagnosis was monoclonal gammopathy of renal significance in 30 (60%), multiple myeloma in 17 (34%), and chronic lymphocytic leukemia in 3 (6%) patients. Complement studies showed low C3 level in 22/50 (43%) and elevated soluble C5b-9 level in 27/34 (79%) patients. Twenty-nine patients received chemotherapy (including bortezomib in 22), whereas 8 and 13 patients received various immunosuppressive drugs or symptomatic measures alone, respectively. Patients who achieved hematological response after chemotherapy had higher renal response rates (P = .0001) and median renal survival (hazard ratio, 0.22; 95% confidence interval, 0.05-0.92; P = .009) than those receiving conservative/immunosuppressive therapy. In conclusion, our results suggest that chemotherapy adapted to the B-cell clone may constitute an efficient strategy for C3G in the setting of MIg, as rapid achievement of hematological response appears to result in improved renal survival.

Patients with hypertension-associated thrombotic microangiopathy may present with complement abnormalities

Thrombotic microangiopathy (TMA) is a pattern of endothelial damage that can be found in association with diverse clinical conditions such as malignant hypertension. Although the pathophysiological mechanisms differ, accumulating evidence links complement dysregulation to various TMA syndromes and in particular the atypical hemolytic uremic syndrome. Here, we evaluated the role of complement in nine consecutive patients with biopsy-proven renal TMA attributed to severe hypertension. Profound hematologic symptoms of TMA were uncommon. In six out of nine patients, we found mutations C3 in three, CFI in one, CD46 in one, and/or CFH in two patients either with or without the risk CFH-H3 haplotype in four patients. Elevated levels of the soluble C5b-9 and renal deposits of C3c and C5b-9 along the vasculature and/or glomerular capillary wall, confirmed complement activation invivo. In contrast to patients without genetic defects, patients with complement defects invariably progressed to end-stage renal disease, and disease recurrence after kidney transplantation seems common. Thus, a subset of patients with hypertension-associated TMA falls within the spectrum of complement-mediated TMA, the prognosis of which is poor. Hence, testing for genetic complement abnormalities is warranted in patients with severe hypertension and TMA on renal biopsy to adopt suitable treatment options and prophylactic measures.

Anti-Factor B and Anti-C3b Autoantibodies in C3 Glomerulopathy and Ig-Associated Membranoproliferative GN.

In C3 glomerulopathy (C3G), the alternative pathway of complement is frequently overactivated by autoantibodies that stabilize the C3 convertase C3bBb. Anti-C3b and anti-factor B (anti-FB) IgG have been reported in three patients with C3G. We screened a cohort of 141 patients with C3G and Ig-associated membranoproliferative GN (Ig-MPGN) for anti-FB and anti-C3b autoantibodies using ELISA. We identified seven patients with anti-FB IgG, three patients with anti-C3b IgG, and five patients with anti-FB and anti-C3b IgG. Of these 15 patients, ten were diagnosed with Ig-MPGN. Among those patients with available data, 92% had a nephrotic syndrome, 64% had AKI, and 67% had a documented infection. Patients negative for anti-C3b and anti-FB IgG had much lower rates of infection (17 [25%] patients with C3G and one [10%] patient with Ig-MPGN). After 48 months, four of 15 (26%) positive patients had developed ESRD or died. All 15 patients had high plasma Bb levels, six (40%) patients had low levels of C3, and nine (60%) patients had high levels of soluble C5b9. In vitro, IgG purified from patients with anti-FB Abs selectively enhanced C3 convertase activity; IgG from patients with anti-C3b/anti-FB Abs enhanced C3 and C5 cleavage. IgG from patients with anti-C3b Abs stabilized C3bBb and perturbed C3b binding to complement receptor 1 but did not perturb binding to factor H. In conclusion, the prevalence of anti-C3b/anti-FB Abs and alternative pathway activation is similar in Ig-MPGN and C3G, suggesting similar pathogenic mechanisms. Identification of the underlying defect in Ig-MPGN could lead to improved treatment.

Complement Alternative Pathway׳s Activation in Patients With Lupus Nephritis

ObjectiveThe aim of this study was to detect the spectrum of complement activation pathways in circulation and to assess their correlations with clinical and pathologic features in a large lupus nephritis cohort from China. Materials and MethodsPlasma levels of C1q, mannose-binding lectin, C4d, Bb, C3, C3a, C5a and soluble C5b-9 were detected by enzyme-linked immunosorbent assay in 222 patients with active biopsy-proven lupus nephritis, 34 patients with lupus nephritis at remission, 82 patients with active systemic lupus erythematosus without renal involvement and 39 normal controls. The correlations between levels of complement components and clinicopathological features of these patients were further analyzed. ResultsPlasma levels of C1q and C3 significantly decreased, and the levels of Bb, C3a, C5a and soluble C5b-9 were significantly elevated in patients with active lupus nephritis compared with those in remission, active systemic lupus erythematosus without renal involvement group and normal controls. In the lupus nephritis group, soluble C5b-9 levels were inversely correlated with C1q and C4d levels (r = −0.412, P < 0.001 and r = −0.221, P = 0.002, respectively), but more strongly correlated with the level of Bb (r = 0.546, P < 0.001). C3b, Bb and C5b-9 could colocalize on glomeruli in lupus nephritis. Plasma Bb level was significantly correlated with some renal disease activity indices and was a risk factor for renal outcomes (hazard ratio = 1.745; 95% CI: 1.106-2.754; P = 0.017) in the lupus nephritis group. ConclusionsOur findings suggested that the activation of the complement alternative pathway might play a more important role in the pathogenesis of lupus nephritis, and factor Bb might be a useful marker for evaluating renal disease activity and outcomes.

Neuroprotective effects of intravenous immunoglobulin are mediated through inhibition of complement activation and apoptosis in a rat model of sepsis

BackgroundIntravenous (IV) immunoglobulin (Ig) treatment is known to alleviate behavioral deficits and increase survival in the experimentally induced model of sepsis. To delineate the mechanisms by which IVIg treatment prevents neuronal dysfunction, an array of immunological and apoptosis markers was investigated.MethodsSepsis was induced by cecal ligation perforation (CLP) in rats. The animals were divided into five groups: sham, control, CLP + saline, CLP + immunoglobulin G (IgG) (250 mg/kg, iv), and CLP + immunoglobulins enriched with immunoglobulin M (IgGAM) (250 mg/kg, iv). Blood and brain samples were taken in two sets of experiments to see the early (24 h) and late (10 days) effects of treatment. Total complement activity, complement 3 (C3), and soluble complement C5b-9 levels were measured in the sera of rats using ELISA-based methods. Cerebral complement, complement receptor, NF-κB, Bax, and Bcl-2 expressions were analyzed by western blot and/or RT-PCR methods. Immune cell infiltration and gliosis were examined by immunohistochemistry using CD3, CD4, CD8, CD11b, CD19, and glial fibrillary acidic protein antibodies. Apoptotic neuronal death was investigated by TUNEL staining.ResultsIVIgG and IgGAM administration significantly reduced systemic complement activity and cerebral C5a and C5a receptor expression. Likewise, both treatment methods reduced proapoptotic NF-κB and Bax expressions in the brain. IVIgG and IgGAM treatment induced considerable amelioration in glial cell proliferation and neuronal apoptosis which were increased in non-treated septic rats.ConclusionsWe suggest that IVIgG and IgGAM administration ameliorates neuronal dysfunction and behavioral deficits by reducing apoptotic cell death and glial cell proliferation. In both treatment methods, these beneficial effects might be mediated through reduction of anaphylatoxic C5a activity and subsequent inhibition of inflammation and apoptosis pathways.