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Meuleman MS, Duval A, Grunenwald A, Rezola Artero M, Dermani M, Peliconi J, Revel M, Vieira-Martins P, Courbebaisse M, Parfait B, Lebeaux D, Friedlander G, Roumenina L, Chauvet S, Frémeaux-Bacchi V, Dragon-Durey MA. Usefulness and analytical performances of complement multiplex assay for measuring complement biomarkers in plasma. Clin Chim Acta 2024; 554:117750. [PMID: 38176523 DOI: 10.1016/j.cca.2023.117750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/27/2023] [Accepted: 12/27/2023] [Indexed: 01/06/2024]
Abstract
INTRODUCTION The complement system is involved in numerous diseases, through diverse mechanisms and degree of activation. With the emergence of complement targeting therapeutic, simple and accessible tools to evaluate the extent of complement activation are strongly needed. METHODS We evaluated two multiplex panels, measuring complement activation fragments (C4a, C3a, C5a, Bb, Ba, sC5b9) and intact components or regulators (C1q, C2, C3, C4, C5, FD, FP, FH, FI). The specificity of each measurement was assessed by using complement proteins depleted sera and plasma collected from patients with complement deficiencies. Normal values distribution was estimated using 124 plasma samples from healthy donors and complement activation profile was assessed in plasma collected from 31 patients with various complement-mediated disorders. RESULTS We observed good inter-assay variation. All tested protein deficiencies were accurately detected. We established assay-specific reference values for each analyte. Except for C3, C4 and C4a, the majority of the measurements were in good agreement with references methods or published data. CONCLUSION Our study substantiates the utility of the Complement Multiplex assay as a tool for measuring complement activation and deficiencies. Quantifying complement cleavage fragments in patients exhibiting classical or alternative pathway activation allowed evaluating the activation state of the whole cascade.
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Affiliation(s)
- Marie-Sophie Meuleman
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université Paris Cité, Inflammation, Complement and Cancer Team, Paris, France; Laboratory of Immunology, Georges Pompidou European Hospital, APHP, Paris, France
| | - Anna Duval
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université Paris Cité, Inflammation, Complement and Cancer Team, Paris, France; Department of Nephrology, Strasbourg University Hospital, Strasbourg, France
| | - Anne Grunenwald
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université Paris Cité, Inflammation, Complement and Cancer Team, Paris, France; Department of Nephrology, Poissy Intercommunal Hospital, Poissy, France
| | - Mikel Rezola Artero
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université Paris Cité, Inflammation, Complement and Cancer Team, Paris, France
| | - Mohamed Dermani
- Laboratory of Immunology, Georges Pompidou European Hospital, APHP, Paris, France
| | - Julie Peliconi
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université Paris Cité, Inflammation, Complement and Cancer Team, Paris, France
| | - Margot Revel
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université Paris Cité, Inflammation, Complement and Cancer Team, Paris, France
| | - Paula Vieira-Martins
- Laboratory of Immunology, Georges Pompidou European Hospital, APHP, Paris, France
| | - Marie Courbebaisse
- Paris Cité University, Physiology Department, European Georges-Pompidou Hospital, APHP, INSERM U1151, Paris, France
| | - Béatrice Parfait
- Centre de Ressources Biologiques - site Cochin, Fédération des CRB/PRB, DMU BioPhyGen, AP-HP.Centre-Université Paris Cité, Hôpital Cochin, Paris, France
| | - David Lebeaux
- Institut Pasteur, Université Paris Cité, CNRS UMR 6047, Genetics of Biofilms Laboratory, 75015 Paris, France; Service de Microbiologie, Unité Mobile d'Infectiologie, AP-HP, Hôpital Européen Georges Pompidou, 20 rue Leblanc, 75015 Paris, France
| | | | - Lubka Roumenina
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université Paris Cité, Inflammation, Complement and Cancer Team, Paris, France
| | - Sophie Chauvet
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université Paris Cité, Inflammation, Complement and Cancer Team, Paris, France; Paris Cité University, Paris, France; Department of Nephrology, Georges Pompidou European Hospital, APHP, Paris, France
| | - Véronique Frémeaux-Bacchi
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université Paris Cité, Inflammation, Complement and Cancer Team, Paris, France; Laboratory of Immunology, Georges Pompidou European Hospital, APHP, Paris, France
| | - Marie-Agnès Dragon-Durey
- Centre de Recherche des Cordeliers, Sorbonne Université, Inserm, Université Paris Cité, Inflammation, Complement and Cancer Team, Paris, France; Laboratory of Immunology, Georges Pompidou European Hospital, APHP, Paris, France; Paris Cité University, Paris, France.
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Abstract
The complement cascade comprises soluble and cell surface proteins and is an important arm of the innate immune system. Once activated, the complement system rapidly generates large quantities of protein fragments that are potent mediators of inflammatory, vasoactive and metabolic responses. Although complement is crucial to host defence and homeostasis, its inappropriate or uncontrolled activation can also drive tissue injury. For example, the complement system has been known for more than 50 years to be activated by glomerular immune complexes and to contribute to autoimmune kidney disease. Notably, the latest research shows that complement is also activated in kidney diseases that are not traditionally thought of as immune-mediated, including haemolytic-uraemic syndrome, diabetic kidney disease and focal segmental glomerulosclerosis. Several complement-targeted drugs have been approved for the treatment of kidney disease, and additional anti-complement agents are being investigated in clinical trials. These drugs are categorically different from other immunosuppressive agents and target pathological processes that are not effectively inhibited by other classes of immunosuppressants. The development of these new drugs might therefore have considerable benefits in the treatment of kidney disease.
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Affiliation(s)
- Vojtech Petr
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic
- University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Joshua M Thurman
- University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.
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Golshayan D, Schwotzer N, Fakhouri F, Zuber J. Targeting the Complement Pathway in Kidney Transplantation. J Am Soc Nephrol 2023; 34:1776-1792. [PMID: 37439664 PMCID: PMC10631604 DOI: 10.1681/asn.0000000000000192] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 07/02/2023] [Indexed: 07/14/2023] Open
Abstract
The complement system is paramount in the clearance of pathogens and cell debris, yet is increasingly recognized as a key component in several pathways leading to allograft injury. There is thus a growing interest in new biomarkers to assess complement activation and guide tailored therapies after kidney transplantation (KTx). C5 blockade has revolutionized post-transplant management of atypical hemolytic uremic syndrome, a paradigm of complement-driven disease. Similarly, new drugs targeting the complement amplification loop hold much promise in the treatment and prevention of recurrence of C3 glomerulopathy. Although unduly activation of the complement pathway has been described after brain death and ischemia reperfusion, any clinical attempts to mitigate the ensuing renal insults have so far provided mixed results. However, the intervention timing, strategy, and type of complement blocker need to be optimized in these settings. Furthermore, the fast-moving field of ex vivo organ perfusion technology opens new avenues to deliver complement-targeted drugs to kidney allografts with limited iatrogenic risks. Complement plays also a key role in the pathogenesis of donor-specific ABO- and HLA-targeted alloantibodies. However, C5 blockade failed overall to improve outcomes in highly sensitized patients and prevent the progression to chronic antibody-mediated rejection (ABMR). Similarly, well-conducted studies with C1 inhibitors in sensitized recipients yielded disappointing results so far, in part, because of subtherapeutic dosage used in clinical studies. The emergence of new complement blockers raises hope to significantly reduce the negative effect of ischemia reperfusion, ABMR, and nephropathy recurrence on outcomes after KTx.
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Affiliation(s)
- Dela Golshayan
- Transplantation Center, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Nora Schwotzer
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Fadi Fakhouri
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Julien Zuber
- Service de Transplantation rénale adulte, Assistance Publique-Hôpitaux de Paris, Hôpital Necker, Paris, France
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Pejchinovski I, Turkkan S, Pejchinovski M. Recent Advances of Proteomics in Management of Acute Kidney Injury. Diagnostics (Basel) 2023; 13:2648. [PMID: 37627907 PMCID: PMC10453063 DOI: 10.3390/diagnostics13162648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/31/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
Acute Kidney Injury (AKI) is currently recognized as a life-threatening disease, leading to an exponential increase in morbidity and mortality worldwide. At present, AKI is characterized by a significant increase in serum creatinine (SCr) levels, typically followed by a sudden drop in glomerulus filtration rate (GFR). Changes in urine output are usually associated with the renal inability to excrete urea and other nitrogenous waste products, causing extracellular volume and electrolyte imbalances. Several molecular mechanisms were proposed to be affiliated with AKI development and progression, ultimately involving renal epithelium tubular cell-cycle arrest, inflammation, mitochondrial dysfunction, the inability to recover and regenerate proximal tubules, and impaired endothelial function. Diagnosis and prognosis using state-of-the-art clinical markers are often late and provide poor outcomes at disease onset. Inappropriate clinical assessment is a strong disease contributor, actively driving progression towards end stage renal disease (ESRD). Proteins, as the main functional and structural unit of the cell, provide the opportunity to monitor the disease on a molecular level. Changes in the proteomic profiles are pivotal for the expression of molecular pathways and disease pathogenesis. Introduction of highly-sensitive and innovative technology enabled the discovery of novel biomarkers for improved risk stratification, better and more cost-effective medical care for the ill patients and advanced personalized medicine. In line with those strategies, this review provides and discusses the latest findings of proteomic-based biomarkers and their prospective clinical application for AKI management.
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Affiliation(s)
- Ilinka Pejchinovski
- Department of Quality Assurance, Nikkiso Europe GmbH, 30885 Langenhagen, Germany; (I.P.); (S.T.)
| | - Sibel Turkkan
- Department of Quality Assurance, Nikkiso Europe GmbH, 30885 Langenhagen, Germany; (I.P.); (S.T.)
| | - Martin Pejchinovski
- Department of Analytical Instruments Group, Thermo Fisher Scientific, 82110 Germering, Germany
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Stenson EK, Edelstein CL, You Z, Miyazaki-Anzai S, Thurman JM, Dixon BP, Zappitelli M, Goldstein SL, Akcan Arikan A, Kendrick J. Urine Complement Factor Ba Is Associated with AKI in Critically Ill Children. KIDNEY360 2023; 4:326-332. [PMID: 36758197 PMCID: PMC10103361 DOI: 10.34067/kid.0000000000000077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 01/13/2023] [Indexed: 02/11/2023]
Abstract
Key Points Complement activation, specifically factor B, is implicated in AKI pathogenesis in animal models. Urine Ba (an activation fragment of factor B) was significantly higher in critically ill children with stage 3 AKI and sepsis-AKI. If larger studies show similar association between urine Ba and AKI severity, clinical trials of factor B inhibition are warranted. Background: Critically ill children with AKI have high morbidity and mortality rates and lack treatment options. Complement activation is implicated in AKI pathogenesis, which could be treated with complement-targeted therapeutics. We assessed for an association between urine Ba, an activation fragment of the alternative complement pathway, and AKI in a large cohort of critically ill children. Methods: A biorepository of children requiring mechanical ventilation was leveraged. AKI was based on pediatric version of the RIFLE criteria—stage 1: 25% decreased eGFR or urine output (UOP) <0.5ml/kg per hour for 8 hours; stage 2: 50% decreased eGFR or UOP <0.5 ml/kg per hour for 16 hours; stage 3: 75% decreased eGFR or UOP <0.3ml/kg per hour for 24 hours or anuric for 12 hours. ELISAs were performed to quantitate urine Ba values. Log Ba was used in ANOVA with pairwise comparison by the Tukey method. Logistic regression was performed to test the association between urine Ba and AKI diagnosis. Results: Seventy-three patients were included, of which 56 had AKI: 26 (46%) stage 1, 16 (29%) stage 2, and 14 (25%) stage 3. Ba was significantly higher in patients with stage 3 AKI compared with all other stages. Ba was higher in sepsis-associated AKI compared with non–sepsis-associated AKI. Multivariate analysis included urine Ba, urine IL-18, urine NGAL, sepsis, and Pediatric Risk of Mortality Scores-II (an estimate of illness severity) and showed a significant association between urine Ba and AKI (odds ratio 1.57, 95% confidence interval, 1.13 to 2.20; P 0.007). Conclusion: Urine Ba is significantly increased in patients with AKI compared with patients without AKI. In patients with similar illness severity, a doubling of urine Ba level was associated with a 57% increase in AKI diagnosis of any stage. Further studies are needed to study complement inhibition in treatment or prevention of AKI in critically ill children.
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Affiliation(s)
- Erin K. Stenson
- Section of Pediatric Critical Care Medicine, Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado
| | - Charles L. Edelstein
- Division of Renal Disease and Hypertension, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Zhiying You
- Division of Renal Disease and Hypertension, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Shinobu Miyazaki-Anzai
- Division of Renal Disease and Hypertension, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Joshua M. Thurman
- Division of Renal Disease and Hypertension, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Bradley P. Dixon
- Renal Section, Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado
| | - Michael Zappitelli
- Division of Paediatric Nephrology, Department of Pediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Stuart L. Goldstein
- Center for Acute Care Nephrology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Ayse Akcan Arikan
- Divisions of Pediatric Critical Care and Renal, Department of Pediatrics, Baylor College of Medicine, Texas Children's Hospital, Houston, Texas
| | - Jessica Kendrick
- Division of Renal Disease and Hypertension, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado
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Abstract
Uncontrolled alternative pathway activation is the primary driver of several diseases, and it contributes to the pathogenesis of many others. Consequently, diagnostic tests to monitor this arm of the complement system are increasingly important. Defects in alternative pathway regulation are strong risk factors for disease, and drugs that specifically block the alternative pathway are entering clinical use. A range of diagnostic tests have been developed to evaluate and monitor the alternative pathway, including assays to measure its function, expression of alternative pathway constituents, and activation fragments. Genetic studies have also revealed many disease-associated variants in alternative pathway genes that predict the risk of disease and prognosis. Newer imaging modalities offer the promise of non-invasively detecting and localizing pathologic complement activation. Together, these various tests help in the diagnosis of disease, provide important prognostic information, and can help guide therapy with complement inhibitory drugs.
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Affiliation(s)
- Joshua M. Thurman
- Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO, USA
| | - Veronique Fremeaux-Bacchi
- Assistance Publique-Hôpitaux de Paris, European Hospital Georges Pompidou, Department of Immunology Biology and INSERM UMRS1138, Centre de Recherche des Cordeliers, Team "Inflammation, Complement and Cancer", Paris, France
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Thurman JM, Harrison RA. The susceptibility of the kidney to alternative pathway activation-A hypothesis. Immunol Rev 2023; 313:327-338. [PMID: 36369971 DOI: 10.1111/imr.13168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The glomerulus is often the prime target of dysregulated alternative pathway (AP) activation. In particular, AP activation is the key driver of two severe kidney diseases: atypical hemolytic uremic syndrome and C3 glomerulopathy. Both conditions are associated with a variety of predisposing molecular defects in AP regulation, such as genetic variants in complement regulators, autoantibodies targeting AP proteins, or autoantibodies that stabilize the AP convertases (C3- and C5-activating enzymes). It is noteworthy that these are systemic AP defects, yet in both diseases pathologic complement activation primarily affects the kidneys. In particular, AP activation is often limited to the glomerular capillaries. This tropism of AP-mediated inflammation for the glomerulus points to a unique interaction between AP proteins in plasma and this particular anatomic structure. In this review, we discuss the pre-clinical and clinical data linking the molecular causes of aberrant control of the AP with activation in the glomerulus, and the possible causes of this tropism. Based on these data, we propose a model for why the kidney is so uniquely and frequently targeted in patients with AP defects. Finally, we discuss possible strategies for preventing pathologic AP activation in the kidney.
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Affiliation(s)
- Joshua M Thurman
- Department of Medicine, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
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Fakhouri F, Schwotzer N, Golshayan D, Frémeaux-Bacchi V. The rational use of complement inhibitors in kidney diseases. Kidney Int Rep 2022; 7:1165-1178. [PMID: 35685323 PMCID: PMC9171628 DOI: 10.1016/j.ekir.2022.02.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 02/15/2022] [Accepted: 02/21/2022] [Indexed: 12/14/2022] Open
Abstract
The development of complement inhibitors represented one of the major breakthroughs in clinical nephrology in the last decade. Complement inhibition has dramatically transformed the outcome of one of the most severe kidney diseases, the atypical hemolytic uremic syndrome (aHUS), a prototypic complement-mediated disorder. The availability of complement inhibitors has also opened new promising perspectives for the management of several other kidney diseases in which complement activation is involved to a variable extent. With the rapidly growing number of complement inhibitors tested in a rapidly increasing number of indications, a rational use of this innovative and expensive new therapeutic class has become crucial. The present review aims to summarize what we know, and what we still ignore, regarding complement activation and therapeutic inhibition in kidney diseases. It also provides some clues and elements of thoughts for a rational approach of complement modulation in kidney diseases.
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Affiliation(s)
- Fadi Fakhouri
- Service de Néphrologie et d'hypertension, Département de Médecine, Centre Hospitalier Universitaire Vaudois (CHUV), Université de Lausanne, Lausanne, Switzerland
- Correspondence: Fadi Fakhouri, Service de Néphrologie et d'hypertension, Département de Médecine, Centre Hospitalier Universitaire Vaudois (CHUV), Université de Lausanne, Lausanne, Switzerland.
| | - Nora Schwotzer
- Service de Néphrologie et d'hypertension, Département de Médecine, Centre Hospitalier Universitaire Vaudois (CHUV), Université de Lausanne, Lausanne, Switzerland
| | - Déla Golshayan
- Centre de Transplantation d'organes, Département de Médecine, Centre Hospitalier Universitaire Vaudois (CHUV), Université de Lausanne, Lausanne, Switzerland
| | - Véronique Frémeaux-Bacchi
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service d'Immunologie, Paris University, Paris, France
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Stenson EK, You Z, Reeder R, Norris J, Scott HF, Dixon BP, Thurman JM, Frazer-Abel A, Mourani P, Kendrick J. Complement Activation Fragments Are Increased in Critically Ill Pediatric Patients with Severe AKI. KIDNEY360 2021; 2:1884-1891. [PMID: 35419539 PMCID: PMC8986038 DOI: 10.34067/kid.0004542021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 10/06/2021] [Indexed: 02/04/2023]
Abstract
Background Children who are critically ill with AKI suffer from high morbidity and mortality rates, and lack treatment options. Emerging evidence implicates the role of complement activation in AKI pathogenesis, which could potentially be treated with complement inhibitors. The purpose of this study is to evaluate the association between complement activation fragments and severity of AKI in children who are critically ill. Methods A biorepository of samples from children who are critically ill from a prior multisite study was leveraged to identify children with stage 3 AKI and matched to patients without AKI on the basis of PELOD-2 (illness severity) scores. Specimens were analyzed for plasma and urine complement activation fragments of factor B, C3a, C4a, and sC5b-9. The primary outcomes were MAKE30 and severe AKI rates. Results In total, 14 patients with stage 3 AKI (five requiring RRT) were matched to 14 patients without AKI. Urine factor Ba and plasma C4a levels increased stepwise as severity of AKI increased, from no AKI to stage 3 AKI, to stage 3 AKI with RRT need. Plasma C4a levels were independently associated with increased risk of MAKE30 outcomes (OR, 3.2; IQR, 1.1-8.9), and urine Ba (OR, 1.9; IQR, 1.1-3.1), plasma Bb (OR, 2.7; IQR, 1.1-6.8), C4a (OR, 13.0; IQR, 1.6-106.6), and C3a (OR, 3.3; IQR, 1.3-8.4) were independently associated with risk of severe stage 2-3 AKI on day 3 of admission. Conclusions Multiple complement fragments increase as magnitude of AKI severity increases. Very high levels of urine Ba or plasma C4a may identify patients at risk for severe AKI, hemodialysis, and MAKE30 outcomes. The fragments may be useful as a functional biomarker of complement activation and may identify those patients to study complement inhibition to treat or prevent AKI in children who are critically ill. These findings suggest the need for further specific investigations of the role of complement activation in children who are critically ill and at risk of AKI.
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Affiliation(s)
- Erin K. Stenson
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado,Department of Pediatrics, Section of Pediatric Critical Care, University of Colorado School of Medicine, Aurora, Colorado
| | - Zhiying You
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Ron Reeder
- Department of Pediatrics, University of Utah, Salt Lake City, Utah
| | - Jesse Norris
- Department of Pediatrics, University of Utah, Salt Lake City, Utah
| | - Halden F. Scott
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado,Department of Pediatrics, Section of Pediatric Emergency Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Bradley P. Dixon
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado,Department of Pediatrics, Section of Pediatric Nephrology, University of Colorado School of Medicine, Aurora, Colorado
| | - Joshua M. Thurman
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Ashley Frazer-Abel
- Department of Pediatrics, Exsera BioLabs, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Peter Mourani
- Division of Critical Care Medicine, Arkansas Children’s Hospital, Little Rock, Arkansas
| | - Jessica Kendrick
- Division of Renal Disease and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado
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Willrich MAV, Braun KMP, Moyer AM, Jeffrey DH, Frazer-Abel A. Complement testing in the clinical laboratory. Crit Rev Clin Lab Sci 2021; 58:447-478. [PMID: 33962553 DOI: 10.1080/10408363.2021.1907297] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The complement system is the human's first line of defense against microbial pathogens because of its important housekeeping and infection/inflammation roles. It is composed of a series of soluble and cell-bound proteins that are activated in a cascade effect, similar to the coagulation pathways. There are different pattern recognizing molecules that activate the complement system in response to stimuli or threats, acting through three initiation pathways: classical, lectin, and alternative. All three activation pathways converge at the C3 component and share the terminal pathway. The main outputs of the complement system action are lytic killing of microbes, the release of pro-inflammatory anaphylatoxins, and opsonization of targets. Laboratory testing is relevant in the setting of suspected complement deficiencies, as well as in the emerging number of diseases related to dysregulation (over-activation) of complement. Most common assays measure complement lytic activity and the different complement component concentrations. Specialized testing includes the evaluation of autoantibodies against complement components, activation fragments, and genetic studies. In this review, we cover laboratory testing for complement and the conditions with complement involvement, as well as current challenges in the field.
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Affiliation(s)
| | - Karin M P Braun
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Ann M Moyer
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - David H Jeffrey
- Exsera Biolabs, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | - Ashley Frazer-Abel
- Exsera Biolabs, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, USA
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Grafals M, Thurman JM. The Role of Complement in Organ Transplantation. Front Immunol 2019; 10:2380. [PMID: 31636644 PMCID: PMC6788431 DOI: 10.3389/fimmu.2019.02380] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 09/23/2019] [Indexed: 12/17/2022] Open
Abstract
The current immunosuppressive protocols used in transplant recipients have improved short-term outcomes, but long-term allograft failure remains an important clinical problem. Greater understanding of the immunologic mechanisms that cause allograft failure are needed, as well as new treatment strategies for protecting transplanted organs. The complement cascade is an important part of the innate immune system. Studies have shown that complement activation contributes to allograft injury in several clinical settings, including ischemia/reperfusion injury and antibody mediated rejection. Furthermore, the complement system plays critical roles in modulating the responses of T cells and B cells to antigens. Therapeutic complement inhibitors, therefore, may be effective for protecting transplanted organs from several causes of inflammatory injury. Although several anti-complement drugs have shown promise in selected patients, the role of these drugs in transplantation medicine requires further study.
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Affiliation(s)
- Monica Grafals
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Joshua M Thurman
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
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