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Evangelidis P, Evangelidis N, Vlachaki E, Gavriilaki E. What is the role of complement in bystander hemolysis? Old concept, new insights. Expert Rev Hematol 2024; 17:107-116. [PMID: 38708453 DOI: 10.1080/17474086.2024.2348662] [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: 01/07/2024] [Accepted: 04/24/2024] [Indexed: 05/07/2024]
Abstract
INTRODUCTION Bystander hemolysis occurs when antigen-negative red blood cells (RBCs) are lysed by the complement system. Many clinical entities including passenger lymphocyte syndrome, hyperhemolysis following blood transfusion, and paroxysmal nocturnal hemoglobinuria are complicated by bystander hemolysis. AREAS COVERED The review provides data about the role of the complement system in the pathogenesis of bystander hemolysis. Moreover, future perspectives on the understanding and management of this syndrome are described. EXPERT OPINION Complement system can be activated via classical, alternative, and lectin pathways. Classical pathway activation is mediated by antigen-antibody (autoantibodies and alloantibodies against autologous RBCs, infectious agents) complexes. Alternative pathway initiation is triggered by heme, RBC microvesicles, and endothelial injury that is a result of intravascular hemolysis. Thus, C5b is formed, binds with C6-C9 compomers, and MAC (C5b-9) is formulated in bystander RBCs membranes, leading to cell lysis. Intravascular hemolysis, results in activation of the alternative pathway, establishing a vicious cycle between complement activation and bystander hemolysis. C5 inhibitors have been used effectively in patients with hyperhemolysis syndrome and other entities characterized by bystander hemolysis.
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Affiliation(s)
- Paschalis Evangelidis
- Second Propedeutic Department of Internal Medicine, Hippocration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Nikolaos Evangelidis
- Second Propedeutic Department of Internal Medicine, Hippocration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Efthymia Vlachaki
- Adult Thalassemia Unit, 2nd Department of Internal Medicine, Aristotle University of Thessaloniki, Hippocration General Hospital, Thessaloniki, Greece
| | - Eleni Gavriilaki
- Second Propedeutic Department of Internal Medicine, Hippocration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Gavriilaki E. Hematology: the specialty with a record number of new approvals. Front Med (Lausanne) 2024; 11:1385052. [PMID: 38487026 PMCID: PMC10937422 DOI: 10.3389/fmed.2024.1385052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Accepted: 02/19/2024] [Indexed: 03/17/2024] Open
Affiliation(s)
- Eleni Gavriilaki
- 2nd Propedeutic Department of Internal Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Caravaca-Fontán F, Gutiérrez E, Sevillano ÁM, Praga M. Targeting complement in IgA nephropathy. Clin Kidney J 2023; 16:ii28-ii39. [PMID: 38053977 PMCID: PMC10695513 DOI: 10.1093/ckj/sfad198] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Indexed: 12/07/2023] Open
Abstract
Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Recent years have witnessed significant improvements in the understanding of the pathogenesis of IgAN and particularly, the pathogenic role of complement activation. The alternative complement pathway is the major complement cascade activator in IgAN, and glomerular C3 deposition has been shown to correlate with disease progression. In addition, several studies have provided insight into the pathogenic role of factor H-related proteins -1 and -5 in IgAN, as independent players in complement dysregulation. The lectin pathway has also been shown to be associated with the severity of IgAN. Glomerular deposition of C4d has been associated with increased histologic disease activity, faster decline in estimated glomerular filtration rate and higher risk of kidney failure. On the other hand, although overlooked in the Oxford classification, numerous studies have shown that the coexistence of thrombotic microangiopathy in IgAN is a significant indicator of a poorer prognosis. All the breakthroughs in the understanding of the contributing role of complement in IgAN have paved the way for the development of new complement-targeted therapies in this disease. Several ongoing trials are evaluating the efficacy of new agents against factor B (iptacopan, Ionis-FB-LRX), C3 (pegcetacoplan), factor D (vemircopan, pelecopan), C5 (ravulizumab, cemdisiran) and C5a receptor 1 (avacopan). In this study, we provide a comprehensive review of the role of complement in IgAN, including the emerging mechanisms of complement activation and the promising potential of complement inhibitors as a viable treatment option for IgAN.
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Affiliation(s)
- Fernando Caravaca-Fontán
- Department of Nephrology, Instituto de Investigación Hospital 12 de Octubre (imas12), Madrid, Spain
| | - Eduardo Gutiérrez
- Department of Nephrology, Hospital Universitario 12 de Octubre (imas12), Madrid, Spain
| | - Ángel M Sevillano
- Department of Nephrology, Hospital Universitario 12 de Octubre (imas12), Madrid, Spain
| | - Manuel Praga
- Department of Nephrology, Instituto de Investigación Hospital 12 de Octubre (imas12), Madrid, Spain
- Department of Medicine, Complutense University, Madrid, Spain
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Przybylowicz PK, Sokolowska KE, Rola H, Wojdacz TK. DNA Methylation Changes in Blood Cells of Fibromyalgia and Chronic Fatigue Syndrome Patients. J Pain Res 2023; 16:4025-4036. [PMID: 38054109 PMCID: PMC10695140 DOI: 10.2147/jpr.s439412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 11/13/2023] [Indexed: 12/07/2023] Open
Abstract
Purpose Fibromyalgia (FM) and Chronic Fatigue Syndrome (CFS) affect 0.4% and 1% of society, respectively, and the prevalence of these pain syndromes is increasing. To date, no strong association between these syndromes and the genetic background of affected individuals has been shown. Therefore, it is plausible that epigenetic changes might play a role in the development of these syndromes. Patients and Methods Three previous studies have attempted to elaborate the involvement of genome-wide methylation changes in blood cells in the development of fibromyalgia and chronic fatigue syndrome. These studies included 22 patients with fibromyalgia and 127 patients with CFS, and the results of the studies were largely discrepant. Contradicting results of those studies may be attributed to differences in the omics data analysis approaches used in each study. We reanalyzed the data collected in these studies using an updated and coherent data-analysis framework. Results Overall, the methylation changes that we observed overlapped with previous results only to some extent. However, the gene set enrichment analyses based on genes annotated to methylation changes identified in each of the analyzed datasets were surprisingly coherent and uniformly associated with the physiological processes that, when affected, may result in symptoms characteristic of fibromyalgia and chronic fatigue syndrome. Conclusion Methylomes of the blood cells of patients with FM and CFS in three independent studies have shown methylation changes that appear to be implicated in the pathogenesis of these syndromes.
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Affiliation(s)
| | | | - Hubert Rola
- Independent Clinical Epigenetics Laboratory, Pomeranian Medical University, Szczecin, Poland
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Byeon HJ, Chae MK, Ko J, Lee EJ, Kikkawa DO, Jang SY, Yoon JS. The Role of Adipsin, Complement Factor D, in the Pathogenesis of Graves' Orbitopathy. Invest Ophthalmol Vis Sci 2023; 64:13. [PMID: 37555734 PMCID: PMC10424154 DOI: 10.1167/iovs.64.11.13] [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: 02/05/2023] [Accepted: 07/20/2023] [Indexed: 08/10/2023] Open
Abstract
Purpose Graves' orbitopathy (GO) is an orbital manifestation of autoimmune Graves' disease, and orbital fibroblast is considered a target cell, producing pro-inflammatory cytokines and/or differentiating into adipocytes. Adipose tissue has been focused on as an endocrine and inflammatory organ secreting adipokines. We investigated the pathogenic role of a specific adipokine, adipsin, known as complement factor D in Graves' orbital fibroblasts. Methods The messenger RNA (mRNA) expression of multiple adipokines was investigated in adipose tissues harvested from GO and healthy subjects. Adipsin protein production was analyzed in primary cultured orbital fibroblasts under insulin growth factor (IGF)-1, CD40 ligand (CD40L) stimulation, and adipogenesis. The effect of blocking adipsin with small interfering RNA (siRNA) on pro-inflammatory cytokine production and adipogenesis was evaluated using quantitative real-time PCR, Western blot, and ELISA. Adipogenic differentiation was identified using Oil Red O staining. Results Adipsin gene expression was significantly elevated in GO tissue and increased after the stimulation of IGF-1 and CD40L, as well as adipocyte differentiation in GO cells. Silencing of adipsin suppressed IGF-1-induced IL-6, IL-8, COX2, ICAM-1, CCL2 gene expression, and IL-6 protein secretion. Adipsin suppression also attenuated adipocyte differentiation. Exogenous treatment of recombinant adipsin resulted in the activation of the Akt, ERK, p-38, and JNK signaling pathways. Conclusions Adipsin, secreted by orbital fibroblasts, may play a distinct role in the pathogenesis of GO. Inhibition of adipsin ameliorated the production of pro-inflammatory cytokines and adipogenesis in orbital fibroblasts. Our study provides an in vitro basis suggesting adipsin as a potential therapeutic target for GO treatment.
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Affiliation(s)
- Hyeong Ju Byeon
- Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Min Kyung Chae
- Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - JaeSang Ko
- Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Eun Jig Lee
- Department of Endocrinology, Severance Hospital, Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, Korea
| | - Don O. Kikkawa
- Division of Oculofacial Plastic and Reconstructive Surgery, Department of Ophthalmology, Shiley Eye Institute, University of California San Diego, La Jolla, California, United States
| | - Sun Young Jang
- Department of Ophthalmology, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea
| | - Jin Sook Yoon
- Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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Dani R, Oroszlán G, Martinusz R, Farkas B, Dobos B, Vadas E, Závodszky P, Gál P, Dobó J. Quantification of the zymogenicity and the substrate-induced activity enhancement of complement factor D. Front Immunol 2023; 14:1197023. [PMID: 37283768 PMCID: PMC10239819 DOI: 10.3389/fimmu.2023.1197023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 05/04/2023] [Indexed: 06/08/2023] Open
Abstract
Complement factor D (FD) is a serine protease present predominantly in the active form in circulation. It is synthesized as a zymogen (pro-FD), but it is continuously converted to FD by circulating active MASP-3. FD is a unique, self-inhibited protease. It has an extremely low activity toward free factor B (FB), while it is a highly efficient enzyme toward FB complexed with C3b (C3bB). The structural basis of this phenomenon is known; however, the rate enhancement was not yet quantified. It has also been unknown whether pro-FD has any enzymatic activity. In this study, we aimed to measure the activity of human FD and pro-FD toward uncomplexed FB and C3bB in order to quantitatively characterize the substrate-induced activity enhancement and zymogenicity of FD. Pro-FD was stabilized in the proenzyme form by replacing Arg25 (precursor numbering) with Gln (pro-FD-R/Q). Activated MASP-1 and MASP-3 catalytic fragments were also included in the study for comparison. We found that the complex formation with C3b enhanced the cleavage rate of FB by FD approximately 20 million-fold. C3bB was also a better substrate for MASP-1, approximately 100-fold, than free FB, showing that binding to C3b renders the scissile Arg-Lys bond in FB to become more accessible for proteolysis. Though easily measurable, this cleavage by MASP-1 is not relevant physiologically. Our approach provides quantitative data for the two-step mechanism characterized by the enhanced susceptibility of FB for cleavage upon complex formation with C3b and the substrate-induced activity enhancement of FD upon its binding to C3bB. Earlier MASP-3 was also implicated as a potential FB activator; however, MASP-3 does not cleave C3bB (or FB) at an appreciable rate. Finally, pro-FD cleaves C3bB at a rate that could be physiologically significant. The zymogenicity of FD is approximately 800, i.e., the cleavage rate of C3bB by pro-FD-R/Q was found to be approximately 800-fold lower than that by FD. Moreover, pro-FD-R/Q at approximately 50-fold of the physiological FD concentration could restore half-maximal AP activity of FD-depleted human serum on zymosan. The observed zymogen activity of pro-FD might be relevant in MASP-3 deficiency cases or during therapeutic MASP-3 inhibition.
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Zhang W, Wu M, Vadlakonda S, Juarez L, Cheng X, Muppa S, Chintareddy V, Vogeti L, Kellogg-Yelder D, Williams J, Polach K, Chen X, Raman K, Babu Y, Kotian P. Scaffold hopping via ring opening enables identification of acyclic compounds as new complement Factor D inhibitors. Bioorg Med Chem 2022; 74:117034. [DOI: 10.1016/j.bmc.2022.117034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 09/21/2022] [Accepted: 09/22/2022] [Indexed: 11/26/2022]
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