Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 25.653
Filtrar
1.
Front Immunol ; 13: 902063, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35924242

RESUMO

Metabolic syndrome (MS) is a group of clinical abnormalities characterized by central or abdominal obesity, hypertension, hyperuricemia, and metabolic disorders of glucose or lipid. Currently, the prevalence of MS is estimated about 25% in general population and is progressively increasing, which has become a challenging public health burden. Long-term metabolic disorders can activate the immune system and trigger a low-grade chronic inflammation named "metaflammation." As an important organ involved in metabolism, the kidney is inevitably attacked by immunity disequilibrium and "metaflammation." Recently, accumulating studies have suggested that the complement system, the most important and fundamental component of innate immune responses, is actively involved in the development of metabolic kidney diseases. In this review, we updated and summarized the different pathways through which the complement system is activated in a series of metabolic disturbances and the mechanisms on how complement mediate immune cell activation and infiltration, renal parenchymal cell damage, and the deterioration of renal function provide potential new biomarkers and therapeutic options for metabolic kidney diseases.


Assuntos
Nefropatias , Doenças Metabólicas , Síndrome Metabólica , Proteínas do Sistema Complemento/metabolismo , Humanos , Nefropatias/complicações , Doenças Metabólicas/metabolismo , Obesidade/complicações
2.
Front Immunol ; 13: 831371, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35911712

RESUMO

Background: The gap between demand and supply of kidneys for transplantation necessitates the use of kidneys from extended criteria donors. Transplantation of these donor kidneys is associated with inferior results, reflected by an increased risk of delayed graft function. Inferior results might be explained by the higher immunogenicity of extended criteria donor kidneys. Normothermic machine perfusion (NMP) could be used as a platform to assess the quality and function of donor kidneys. In addition, it could be useful to evaluate and possibly alter the immunological response of donor kidneys. In this study, we first evaluated whether complement was activated during NMP of porcine and human discarded kidneys. Second, we examined the relationship between complement activation and pro-inflammatory cytokines during NMP. Third, we assessed the effect of complement activation on renal function and injury during NMP of porcine kidneys. Lastly, we examined local complement C3d deposition in human renal biopsies after NMP. Methods: NMP with a blood-based perfusion was performed with both porcine and discarded human kidneys for 4 and 6 h, respectively. Perfusate samples were taken every hour to assess complement activation, pro-inflammatory cytokines and renal function. Biopsies were taken to assess histological injury and complement deposition. Results: Complement activation products C3a, C3d, and soluble C5b-9 (sC5b-9) were found in perfusate samples taken during NMP of both porcine and human kidneys. In addition, complement perfusate levels positively correlated with the cytokine perfusate levels of IL-6, IL-8, and TNF during NMP of porcine kidneys. Porcine kidneys with high sC5b-9 perfusate levels had significantly lower creatinine clearance after 4 h of NMP. In line with these findings, high complement perfusate levels were seen during NMP of human discarded kidneys. In addition, kidneys retrieved from brain-dead donors had significantly higher complement perfusate levels during NMP than kidneys retrieved from donors after circulatory death. Conclusion: Normothermic kidney machine perfusion induces complement activation in porcine and human kidneys, which is associated with the release of pro-inflammatory cytokines and in porcine kidneys with lower creatinine clearance. Complement inhibition during NMP might be a promising strategy to reduce renal graft injury and improve graft function prior to transplantation.


Assuntos
Rim , Preservação de Órgãos , Animais , Proteínas do Sistema Complemento , Creatinina , Citocinas , Humanos , Rim/patologia , Rim/fisiologia , Preservação de Órgãos/métodos , Perfusão/métodos , Suínos
3.
Front Immunol ; 13: 895519, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35784369

RESUMO

The cellular events that dictate the initiation of the complement pathway in ocular degeneration, such as age-related macular degeneration (AMD), is poorly understood. Using gene expression analysis (single cell and bulk), mass spectrometry, and immunohistochemistry, we dissected the role of multiple retinal and choroidal cell types in determining the complement homeostasis. Our scRNA-seq data show that the cellular response to early AMD is more robust in the choroid, particularly in fibroblasts, pericytes and endothelial cells. In late AMD, complement changes were more prominent in the retina especially with the expression of the classical pathway initiators. Notably, we found a spatial preference for these differences. Overall, this study provides insights into the heterogeneity of cellular responses for complement expression and the cooperation of neighboring cells to complete the pathway in healthy and AMD eyes. Further, our findings provide new cellular targets for therapies directed at complement.


Assuntos
Células Endoteliais , Degeneração Macular , Corioide , Proteínas do Sistema Complemento , Humanos , Degeneração Macular/genética , Retina
4.
Pharm Biol ; 60(1): 1278-1285, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35797701

RESUMO

CONTEXT: Global studies on Argemone mexicana L. (Papaveraceae) traditionally used against malaria in Mali are limited to its low-mass compounds activities, and little information on its bioactive polysaccharides is available. OBJECTIVE: This study determines the structure and the immunomodulatory activity of polysaccharides from aerial parts of A. mexicana. MATERIALS AND METHODS: Acidic polysaccharides from this plant material named HMAmA1 and HMAmA2 were isolated from water extracts. Their monosaccharide composition was determined by gas chromatography. Glycosidic linkages were determined using GC-MS. NMR was also applied. The polymers were tested for effects on the human complement system in vitro at different doses. RESULTS: The monosaccharide composition showed that the two polysaccharides contained in different amounts the following monomers: arabinose, rhamnose, galactose, and galacturonic acid. Overall structural analysis showed the presence of a low ratio of 1,2-linked rhamnose compared to 1,4-linked galacturonic acid with arabinogalactans substituted on position 4 of rhamnose. NMR data showed the presence of galacturonans alternated by rhamnogalacturonans bearing arabinose and galactose units. α-Linkages were found for l-arabinose, l-rhamnose and d-galacturonic acid, while ß-linkages were found for d-galactose. The two polysaccharides exhibited strong complement fixation activities, with HMAmA1 being the highest potent fraction. ICH50 value of HMAmA1 was 5 µg/mL, compared to the control BPII being 15.9 µg/mL. DISCUSSION AND CONCLUSIONS: Polysaccharides form A. mexicana presented a complement fixation effect. The complement system is an important part of the immune defense, and compounds acting on the cascade are of interest. Therefore, these polymers may be useful as immunodulatory agents.


Assuntos
Antimaláricos , Argemone , Antimaláricos/isolamento & purificação , Antimaláricos/farmacologia , Arabinose , Argemone/química , Proteínas do Sistema Complemento , Galactose , Humanos , Mali , Monossacarídeos , Polímeros , Polissacarídeos/isolamento & purificação , Polissacarídeos/farmacologia , Ramnose
5.
Int J Mol Sci ; 23(13)2022 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-35806224

RESUMO

Complement-mediated diseases or complementopathies, such as Paroxysmal nocturnal hemoglobinuria (PNH), cold agglutinin disease (CAD), and transplant-associated thrombotic microangiopathy (TA-TMA), demand advanced complement diagnostics and therapeutics be adopted in a vast field of medical specialties, such as hematology, transplantation, rheumatology, and nephrology. The miracle of complement inhibitors as "orphan drugs" has dramatically improved morbidity and mortality in patients with otherwise life-threatening complementopathies. Efficacy has been significantly improved by upstream inhibition in patients with PNH. Different molecules may exert diverse characteristics in vitro and in vivo. Further studies remain to show safety and efficacy of upstream inhibition in other complementopathies. In addition, cost and availability issues are major drawbacks of current treatments. Therefore, further developments are warranted to address the unmet clinical needs in the field of complementopathies. This state-of-the-art narrative review aims to delineate novel insights into factor D inhibition as a promising target for complementopathies.


Assuntos
Fator D do Complemento , Hemoglobinúria Paroxística , Anticorpos Monoclonais Humanizados/farmacologia , Inativadores do Complemento/farmacologia , Inativadores do Complemento/uso terapêutico , Proteínas do Sistema Complemento , Hemólise , Humanos
6.
Front Immunol ; 13: 853690, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35812377

RESUMO

The complement system is required for innate immunity against Acinetobacter baumannii, an important cause of antibiotic resistant systemic infections. A. baumannii strains differ in their susceptibility to the membrane attack complex (MAC) formed from terminal complement pathway proteins, but the reasons for this variation remain poorly understood. We have characterized in detail the complement sensitivity phenotypes of nine A. baumannii clinical strains and some of the factors that might influence differences between strains. Using A. baumannii laboratory strains and flow cytometry assays, we first reconfirmed that both opsonization with the complement proteins C3b/iC3b and MAC formation were inhibited by the capsule. There were marked differences in C3b/iC3b and MAC binding between the nine clinical A. baumannii strains, but this variation was partially independent of capsule composition or size. Opsonization with C3b/iC3b improved neutrophil phagocytosis of most strains. Importantly, although C3b/iC3b binding and MAC formation on the bacterial surface correlated closely, MAC formation did not correlate with variations between A. baumannii strains in their levels of serum resistance. Genomic analysis identified only limited differences between strains in the distribution of genes required for serum resistance, but RNAseq data identified three complement-resistance genes that were differentially regulated between a MAC resistant and two MAC intermediate resistant strains when cultured in serum. These data demonstrate that clinical A. baumannii strains vary in their sensitivity to different aspects of the complement system, and that the serum resistance phenotype was influenced by factors in addition to the amount of MAC forming on the bacterial surface.


Assuntos
Acinetobacter baumannii , Acinetobacter baumannii/genética , Ativação do Complemento , Complemento C3b/metabolismo , Complexo de Ataque à Membrana do Sistema Complemento , Proteínas do Sistema Complemento , Fagocitose
7.
Curr Opin Hematol ; 29(5): 259-265, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35852851

RESUMO

PURPOSE OF REVIEW: COVID-19 remains a major source of concern, particularly as new variants emerge and with recognition that patients may suffer long-term effects. Mechanisms underlying SARS-CoV-2 mediated organ damage and the associated vascular endotheliopathy remain poorly understood, hindering new drug development. Here, we highlight selected key concepts of how the complement system, a major component of innate immunity that is dysregulated in COVID-19, participates in the thromboinflammatory response and drives the vascular endotheliopathy. RECENT FINDINGS: Recent studies have revealed mechanisms by which complement is activated directly by SARS-CoV-2, and how the system interfaces with other innate thromboinflammatory cellular and proteolytic pathways involving platelets, neutrophils, neutrophil extracellular traps and the coagulation and kallikrein-kinin systems. With this new information, multiple potential sites for therapeutic intervention are being uncovered and evaluated in the clinic. SUMMARY: Infections with SARS-CoV-2 cause damage to the lung alveoli and microvascular endothelium via a process referred to as thromboinflammation. Although not alone in being dysregulated, complement is an early player, prominent in promoting the endotheliopathy and consequential organ damage, either directly and/or via the system's complex interplay with other cellular, molecular and biochemical pathways. Delineating these critical interactions is revealing novel and promising strategies for therapeutic intervention.


Assuntos
COVID-19 , Armadilhas Extracelulares , Trombose , Proteínas do Sistema Complemento , Humanos , Inflamação , SARS-CoV-2 , Trombose/etiologia
8.
Pregnancy Hypertens ; 29: 92-97, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35820290

RESUMO

OBJECTIVE: We sought to determine if soluble levels of C5b-9, the terminal complement complex, correlate with end-organ injury in preeclampsia. STUDY DESIGN: Project COPA (Complement and Preeclampsia in the Americas), a multi-center observational study in Colombia from 2015 to 2016, enrolled hypertensive pregnant women into four groups: chronic hypertension, gestational hypertension, preeclampsia, and preeclampsia with severe features. Trained coordinators collected clinical data, blood and urine. End-organ injury was defined by serum creatinine ≥ 1.0 mg/dl, aspartate transaminase ≥ 70U/L, platelet count < 150,000/µl, or lactate dehydrogenase ≥ 500 U/L. Data were analyzed by χ2 or Fisher's exact test with significance at P < 0.05. MAIN OUTCOME MEASURE: C5b-9 concentrations in plasma and urine, using enzyme linked immunosorbent assays. RESULTS: In total, 298 hypertensive participants were enrolled. Plasma and urine C5b-9 levels were measured in all participants and stratified by quartile (Q1-4), from lowest to highest C5b-9 concentration. Participants with low plasma C5b-9 levels (Q1) were more likely to have end-organ injury compared to those with higher levels (Q2-Q4) [platelet count < 150,000/µl (20.8% vs. 8.4%, P = 0.01); elevated serum creatinine ≥ 1.0 mg/dl (14.9% vs. 4.5%, P = 0.009)]. In contrast, participants with high urinary C5b-9 levels (Q4) were more likely to have end-organ injury compared to those with lower levels (Q1-Q3) [platelet count < 150,000/µl (19.7% vs. 7.4%, P = 0.003); elevated serum creatinine ≥ 1.0 mg/dl (12.3% vs. 4.4%, P = 0.025)]. CONCLUSION: We identified a pattern of increased urine and low plasma C5b-9 levels in patients with preeclampsia and end-organ injury. Soluble C5b-9 levels may be used to identify complement-mediated end-organ injury in preeclampsia.


Assuntos
Hipertensão , Pré-Eclâmpsia , Complexo de Ataque à Membrana do Sistema Complemento/urina , Proteínas do Sistema Complemento , Creatinina , Feminino , Humanos , Hipertensão/urina , Gravidez
9.
Front Immunol ; 13: 931273, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35860237

RESUMO

The role of complement in cancer has received increasing attention over the last decade. Recent studies provide compelling evidence that complement accelerates cancer progression. Despite the pivotal role of complement in fighting microbes, complement seems to suppress antitumor immunity via regulation of host cell in the tumor microenvironment. Although most studies link complement in cancer to complement activation in the extracellular space, the discovery of intracellular activation of complement, raises the question: what is the relevance of this process for malignancy? Intracellular activation is pivotal for the survival of immune cells. Therefore, complement can be important for tumor cell survival and growth regardless of the role in immunosuppression. On the other hand, because intracellular complement (the complosome) is indispensable for activation of T cells, these functions will be essential for priming antitumor T cell responses. Here, we review functions of complement in cancer with the consideration of extra and intracellular pathways of complement activation and spatial distribution of complement proteins in tumors and periphery and provide our take on potential significance of complement as biomarker and target for cancer therapy.


Assuntos
Proteínas do Sistema Complemento , Neoplasias , Ativação do Complemento , Humanos , Linfócitos T , Microambiente Tumoral
10.
Adv Chronic Kidney Dis ; 29(2): 149-160.e1, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35817522

RESUMO

Thrombotic microangiopathies (TMAs) have in common a terminal phenotype of microangiopathic hemolytic anemia with end-organ dysfunction. Thrombotic thrombocytopenic purpura results from von Willebrand factor multimerization, Shiga toxin-mediated hemolytic uremic syndrome causes toxin-induced endothelial dysfunction, while atypical hemolytic uremic syndrome results from complement system dysregulation. Drug-induced TMA, rheumatological disease-induced TMA, and renal-limited TMA exist in an intermediate space that represents secondary complement activation and may overlap with atypical hemolytic uremic syndrome clinically. The existence of TMA without microangiopathic hemolytic features, renal-limited TMA, represents an undiscovered syndrome that responds incompletely and inconsistently to complement blockade. Hematopoietic stem cell transplant-TMA represents another more resistant form of TMA with different therapeutic needs and clinical course. It has become apparent that TMA syndromes are an emerging field in nephrology, rheumatology, and hematology. Much work remains in genetics, molecular biology, and therapeutics to unravel the puzzle of the relationships and distinctions apparent between the different subclasses of TMA syndromes.


Assuntos
Síndrome Hemolítico-Urêmica Atípica , Púrpura Trombocitopênica Trombótica , Microangiopatias Trombóticas , Síndrome Hemolítico-Urêmica Atípica/terapia , Proteínas do Sistema Complemento , Humanos , Púrpura Trombocitopênica Trombótica/complicações , Púrpura Trombocitopênica Trombótica/diagnóstico , Púrpura Trombocitopênica Trombótica/terapia , Toxina Shiga , Microangiopatias Trombóticas/etiologia , Microangiopatias Trombóticas/terapia
11.
Front Immunol ; 13: 926044, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35812453

RESUMO

ANCA (anti-neutrophil cytoplasmic antibody)-associated vasculitis (AAV) is the condition in which ANCA, as an autoantibody, is associated with the pathogenesis of vasculitis in small blood vessels, mainly in the ear, nose, throat, kidney, lung, and nerves. These diseases are important because they can be fatal due to renal failure and pulmonary hemorrhage if not promptly and appropriately treated. Recently accumulated evidence has shown that C5a produced by the complement alternative pathway primes neutrophils, which in turn activate the complement alternative pathway, leading to the pathogenesis of AAV. Avacopan (CCX168), a C5aR antagonist was shown to be effective against AAV, and it has been a novel therapeutic option, becoming a novel anti-complement drug to modulate inflammatory diseases.


Assuntos
Vasculite Associada a Anticorpo Anticitoplasma de Neutrófilos , Anticorpos Anticitoplasma de Neutrófilos , Proteínas do Sistema Complemento/uso terapêutico , Humanos , Rim/patologia , Neutrófilos
13.
Clin Chim Acta ; 533: 156-167, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35787990

RESUMO

OBJECTIVE: To develop a suitable clinical laboratory assay for detecting the activity of circulating immune complexes (CICs) that activate complement (ACIC). METHODS: CICs measured in serum were initially used to activate complement, and the remaining complement was activated through sensitized human O-erythrocytes. ACIC was quantified by the degree of hemolysis. Each serum sample was tested for ten consecutive days to determine its stability. Reference ranges are suggested. ACIC was measured in both healthy individuals and patients with autoimmune diseases as well. RESULTS: The OD values of the hemolysis degree index were inversely proportional to ACIC (r = -0.986, P = 0.002). A pooled serum was used to eliminate interference and optimize the experiment. The hemolysis degree (HD) was used to indicate the detection result. HD = (detection value OD/negative value OD)*100. Both the intra-batch and the inter-batch results showed good stability with a CV of 6.5% and 8.1%, respectively. HD differences between males and females were significant (P = 0.015) while the normal distribution for both genders was conformed. The HD recommended reference range for men is 56-88 while for women is 51-86. Serum HD of healthy subjects and autoimmune disease patients showed a significant difference (P = 0.001). Autoimmune disease patients have lower HD which was a result of having stronger ACIC. CONCLUSION: The ACIC assay while utilizing human O-erythrocytes as an indicator system is sensitive and accurate, and has potential in clinical applications.


Assuntos
Doenças Autoimunes , Hemólise , Aciclovir , Complexo Antígeno-Anticorpo , Proteínas do Sistema Complemento , Eritrócitos , Feminino , Humanos , Masculino
16.
Artigo em Russo | MEDLINE | ID: mdl-35904289

RESUMO

The analysis of publications on the websites PubMed, ClinicalKey, devoted to the pathogenesis of neuroborreliosis (NB), using keywords for search: «pathogenesis of neuroborreliosis¼, «neuroborreliosis in children¼, «pathogenesis of Lyme disease¼, as well as an analysis of the results of the published research results of the staff of the Research Institute of Pediatric Infections, St-Petersburg, Russia is presented. Syndromes of early and late NB are more often observed among the forms without migrating erythema, and their development can be caused by all representatives of the species B. burgdorferi s.l. (B.b.), but more often - B. garinii, since it most effectively suppresses the factors of innate and adaptive immune response, reducing interferon production, phagocytosis and complement synthesis. The cause of immunosuppression with the development of NB may be simultaneous infection with several genovids and borrelia species or pathogens of other infections transmitted by Ixodes ticks, for example, infection with B.b. and tick-borne encephalitis virus. The ability to move along peripheral nerves, the change of surface antigens of the VlsE protein, as well as the formation of atypical cysts and granular forms allows B.b. to affect different structures of the peripheral and central nervous system, avoid an immune response and persist for a long time, causing chronic neuroinfection. Both the B.b. themselves, capable of being outside and inside glial cells and neurons, and inflammatory reactions developing in response to their introduction and associated with the synthesis of cytokines and chemokines and mimicry, cause damage to the vascular endothelium, vasculitis and impaired blood supply to the brain, demyelination, autoimmune inflammation and degeneration, leading to the development of NB syndromes, the spectrum of which varies depending on the duration of neuroinfection. In the development of NB and its outcomes, the following are also important: early initiation of treatment, the effectiveness of antibacterial drugs, the use of immunotropic agents that optimize the patient's immune response to the fight against neuroinfection, as well as the timely use of pathogenetic drugs, such as Cytoflavin, which have a complex effect on the vascular endothelium.


Assuntos
Borrelia burgdorferi , Neuroborreliose de Lyme , Borrelia burgdorferi/fisiologia , Criança , Proteínas do Sistema Complemento , Humanos , Inflamação , Neuroborreliose de Lyme/microbiologia , Fagocitose , Síndrome
17.
Front Cell Infect Microbiol ; 12: 910854, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35846776

RESUMO

Chagas disease, caused by the intracellular pathogen Trypanosoma cruzi, is the parasitic disease with the greatest impact in Latin America and the most common cause of infectious myocarditis in the world. The immune system plays a central role in the control of T. cruzi infection but at the same time needs to be controlled to prevent the development of pathology in the host. It has been shown that persistent infection with T. cruzi induces exhaustion of parasite-specific T cell responses in subjects with chronic Chagas disease. The continuous inflammatory reaction due to parasite persistence in the heart also leads to necrosis and fibrosis. The complement system is a key element of the innate immune system, but recent findings have also shown that the interaction between its components and immune cell receptors might modulate several functions of the adaptive immune system. Moreover, the findings that most of immune cells can produce complement proteins and express their receptors have led to the notion that the complement system also has non canonical functions in the T cell. During human infection by T. cruzi, complement activation might play a dual role in the acute and chronic phases of Chagas disease; it is initially crucial in controlling parasitemia and might later contributes to the development of symptomatic forms of Chagas disease due to its role in T-cell regulation. Herein, we will discuss the putative role of effector complement molecules on T-cell immune exhaustion during chronic human T. cruzi infection.


Assuntos
Doença de Chagas , Miocardite , Trypanosoma cruzi , Doença de Chagas/parasitologia , Proteínas do Sistema Complemento , Humanos , Linfócitos T
18.
Blood Adv ; 6(14): 4310-4319, 2022 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-35877136

RESUMO

Transplant-associated thrombotic microangiopathy (TA-TMA) and atypical hemolytic uremic syndrome (aHUS) are complement-mediated TMAs. The central nervous system (CNS) is the most common extrarenal organ affected by aHUS, and, despite mechanistic overlap between aHUS and TA-TMA, CNS involvement is rarely reported in TA-TMA, suggesting that CNS involvement in TA-TMA may be underdiagnosed and that these patients may benefit from complement blockers. In addition, there are no widely used histologic or radiologic criteria for the diagnosis of TMA in the brain. Thirteen recipients of pediatric hematopoietic cell transplants (HCTs) who had TA-TMA and who underwent autopsy were studied. Seven of 13 brains had vascular injury, and 2 had severe vascular injury. Neurologic symptoms correlated with severe vascular injury. Classic TMA histology was present and most often observed in the cerebellum, brainstem, and cerebral white matter. Abnormalities in similar anatomic regions were seen on imaging. Brain imaging findings related to TMA included hemorrhages, siderosis, and posterior reversible encephalopathy syndrome. We then studied 100 consecutive HCT recipients to identify differences in neurologic complications between patients with and those without TA-TMA. Patients with TA-TMA were significantly more likely to have a clinical concern for seizure, have an electroencephalogram performed, and develop altered mental status. In summary, our study confirms that TA-TMA involves the brains of recipients of HCT and is associated with an increased incidence of neurologic symptoms. Based on these findings, we propose that patients with low- or moderate-risk TA-TMA who develop neurologic complications should be considered for TA-TMA-directed therapy.


Assuntos
Síndrome Hemolítico-Urêmica Atípica , Transplante de Células-Tronco Hematopoéticas , Síndrome da Leucoencefalopatia Posterior , Microangiopatias Trombóticas , Lesões do Sistema Vascular , Criança , Proteínas do Sistema Complemento , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Humanos , Síndrome da Leucoencefalopatia Posterior/complicações , Microangiopatias Trombóticas/diagnóstico , Lesões do Sistema Vascular/complicações
19.
J Immunol ; 208(12): 2597-2612, 2022 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-35867677

RESUMO

Complement genes encompass a wide array of variants, giving rise to numerous protein isoforms that have often been shown to exhibit clinical significance. Given that these variants have been discovered over a span of 50 y, one challenging consequence is the inconsistency in the terminology used to classify them. This issue is prominently evident in the nomenclature used for complement C6 and C7 variants, for which we observed a great discrepancy between previously published works and variants described in current genome browsers. This report discusses the causes for the discrepancies in C6 and C7 nomenclature and seeks to establish a classification system that would unify existing and future variants. The inconsistency in the methods used to annotate amino acids and the modifications pinpointed in the C6 and C7 primers are some of the factors that contribute greatly to the discrepancy in the nomenclature. Several variants that were classified incorrectly are highlighted in this report, and we showcase first-hand how a unified classification system is important to match previous with current genetic information. Ultimately, we hope that the proposed classification system of nomenclature becomes an incentive for studies on complement variants and their physiological and/or pathological effects.


Assuntos
Complemento C6 , Complemento C7 , Complemento C5 , Complemento C6/genética , Complemento C7/genética , Proteínas do Sistema Complemento
20.
Front Immunol ; 13: 952235, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35874690

RESUMO

Membranous nephropathy (MN) is an immune kidney disease characterized by glomerular subepithelial immune complexes (ICs) containing antigen, IgG, and products of complement activation. Whereas proteinuria is caused by complement-mediated podocyte injury, the pathways of complement activation remain controversial due to the predominance of IgG4 in ICs, an IgG subclass considered unable to activate complement. THSD7A, a transmembrane protein expressed on podocytes, is the target autoantigen in ~3% of cases of primary MN. In this study, we analyzed sera from 16 patients with THSD7A-associated MN with regard to the anti-THSD7A IgG subclasses and their ability to fix complement in vitro. The serum concentration of anti-THSD7A IgG varied over two orders of magnitude (1.3-243 µg/mL). As a relative proportion of all IgG anti-THSD7A, IgG4 was by far the most abundant subclass (median 79%), followed by IgG1 (median 11%). IgG4 was the dominant subclass of anti-THSD7A antibodies in 14 sera, while IgG1 was dominant in one and co-dominant in another. One quarter of MN sera additionally contained low levels of anti-THSD7A IgA1. ICs formed by predominantly IgG4 anti-THSD7A autoantibodies with immobilized THSD7A were relatively weak activators of complement in vitro, compared to human IgG1 and IgG3 mAbs used as positive control. Complement deposition on THSD7A ICs was dose-dependent and occurred to a significant extent only at relatively high concentration of anti-THSD7A IgG. C3b fixation by THSD7A ICs was completely abolished in factor B-depleted sera, partially inhibited in C4-depleted sera, unchanged in C1q-depleted sera, and also occurred in Mg-EGTA buffer. These results imply that THSD7A ICs predominantly containing IgG4 activate complement at high IgG4 density, which strictly requires a functional alternative pathway, whereas the classical and lectin pathways are dispensable. These findings advance our understanding of how IgG4 antibodies activate complement.


Assuntos
Glomerulonefrite Membranosa , Complexo Antígeno-Anticorpo , Autoanticorpos , Ativação do Complemento , Proteínas do Sistema Complemento , Humanos , Imunoglobulina G , Trombospondinas
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...