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The presence of gallstones (cholelithiasis) is a highly prevalent and severe disease and one of the leading causes of hospital admissions worldwide. Due to its substantial health impact, we investigated the biological mechanisms that lead to the formation and growth of gallstones. We show that gallstone assembly essentially requires neutrophil extracellular traps (NETs). We found consistent evidence for the presence of NETs in human and murine gallstones and describe an immune-mediated process requiring activation of the innate immune system for the formation and growth of gallstones. Targeting NET formation via inhibition of peptidyl arginine deiminase type 4 or abrogation of reactive oxygen species (ROS) production, as well as damping of neutrophils by metoprolol, effectively inhibit gallstone formation in vivo. Our results show that after the physicochemical process of crystal formation, NETs foster their assembly into larger aggregates and finally gallstones. These insights provide a feasible therapeutic concept to prevent cholelithiasis in patients at risk.
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Armadilhas Extracelulares/imunologia , Cálculos Biliares/imunologia , Neutrófilos/imunologia , Animais , Feminino , Humanos , Imunidade Inata/imunologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Espécies Reativas de Oxigênio/imunologiaRESUMO
Patient-reported outcomes (PRO) represent a cornerstone in the management of patients with rheumatoid arthritis (RA). However, PRO are currently recorded mainly on paper and only during on-site appointments. Electronic PRO (ePRO) enable continuous remote monitoring and could improve shared decision-making (SDM) and implementation of a treat-to-target (T2T) approach. This study aims to investigate patient and physician experiences, perceived drawbacks and benefits of using an ePRO web-app (ABATON RA) to digitally support SDM and T2T. A qualitative study embedded in a multicenter randomized controlled trial (RCT) consisting of interviews with RA patients and physicians that were subsequently analyzed using deductive-inductive qualitative content analysis. Between August 2021 and May 2022, interviews with ten RA patients and five physicians were completed. Three key themes emerged in the analysis: (i) App user experiences; (ii) perceived drawbacks of app-supported rheumatology care; and (iii) perceived benefits of app-supported rheumatology care. Continuous ePRO collection and a high level of standardization strained some RA patients. Certain ePRO seemed outdated and were hard to understand. Patients and physicians appreciated having an improved overview of disease activity, capturing disease flares and continuous remote monitoring. Paper- and time-saving were associated with using ePRO. Physicians feared to become too focused on ePRO data, stressed the lack of ePRO monitoring reimbursement and app interoperability. For RA patients and physicians, benefits seemed to outweigh observed drawbacks of the digitally supported SDM using ePRO. The software was easy to use and could lead to a better understanding of the individual disease course, resource allocation and treatment of rheumatoid arthritis.
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Artrite Reumatoide , Reumatologia , Humanos , Pesquisa Qualitativa , Medidas de Resultados Relatados pelo Paciente , Artrite Reumatoide/diagnóstico , Artrite Reumatoide/tratamento farmacológicoRESUMO
BACKGROUND: The goal of the study was to investigate patients' with systemic rheumatic diseases and healthcare professionals' experiences and preferences regarding self-sampling of capillary blood in rheumatology care. METHODS: Patients performed a supervised and consecutive unsupervised capillary blood self-collection using an upper arm based device. Subsequently, patients (n = 15) and their attending health care professionals (n = 5) participated in an explorative, qualitative study using problem-centered, telephone interviews. Interview data were analyzed using structured qualitative content analysis. RESULTS: Interviewed patients reported easy application and high usability. Patients and health care professionals alike reported time and cost savings, increased independence and flexibility, improved monitoring and reduction of risk of infection during Covid-19 as benefits. Reported drawbacks include limited blood volume, limited usability in case of functional restrictions, and environmental concerns. Older, immobile patients with long journeys to traditional blood collection sites and young patients with little time to spare for traditional blood collection appointments could be user groups, likely to benefit from self-sampling services. CONCLUSIONS: At-home blood self-sampling could effectively complement current rheumatology telehealth care. Appropriateness and value of this service needs to be carefully discussed with patients on an individual basis. TRIAL REGISTRATION: WHO International Clinical Trials Registry: DRKS00024925. Registered on 15/04/2021.
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COVID-19 , Reumatologia , Humanos , Pesquisa Qualitativa , Pessoal de Saúde , Coleta de Amostras SanguíneasAssuntos
Miosite , Linfócitos T , Humanos , Miosite/terapia , Antígenos CD19 , Receptores de Antígenos de Linfócitos TAssuntos
Miosite , Receptores de Antígenos de Linfócitos T , Humanos , Linfócitos T , Miosite/terapia , Antígenos CD19RESUMO
UBE2L3 is associated with increased susceptibility to numerous autoimmune diseases, but the underlying mechanism is unexplained. By using data from a genome-wide association study of systemic lupus erythematosus (SLE), we observed a single risk haplotype spanning UBE2L3, consistently aligned across multiple autoimmune diseases, associated with increased UBE2L3 expression in B cells and monocytes. rs140490 in the UBE2L3 promoter region showed the strongest association. UBE2L3 is an E2 ubiquitin-conjugating enzyme, specially adapted to function with HECT and RING-in-between-RING (RBR) E3 ligases, including HOIL-1 and HOIP, components of the linear ubiquitin chain assembly complex (LUBAC). Our data demonstrate that UBE2L3 is the preferred E2 conjugating enzyme for LUBAC in vivo, and UBE2L3 is essential for LUBAC-mediated activation of NF-κB. By accurately quantifying NF-κB translocation in primary human cells from healthy individuals stratified by rs140490 genotype, we observed that the autoimmune disease risk UBE2L3 genotype was correlated with basal NF-κB activation in unstimulated B cells and monocytes and regulated the sensitivity of NF-κB to CD40 stimulation in B cells and TNF stimulation in monocytes. The UBE2L3 risk allele correlated with increased circulating plasmablast and plasma cell numbers in SLE individuals, consistent with substantially elevated UBE2L3 protein levels in plasmablasts and plasma cells. These results identify key immunological consequences of the UBE2L3 autoimmune risk haplotype and highlight an important role for UBE2L3 in plasmablast and plasma cell development.
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Doenças Autoimunes/genética , NF-kappa B/metabolismo , Polimorfismo de Nucleotídeo Único/genética , Enzimas de Conjugação de Ubiquitina/genética , Doenças Autoimunes/metabolismo , Linfócitos B/metabolismo , Células Cultivadas , Primers do DNA/genética , Citometria de Fluxo , Estudo de Associação Genômica Ampla , Haplótipos/genética , Humanos , Luciferases , Análise em Microsséries , Monócitos/metabolismo , Interferência de RNA , RNA Interferente Pequeno/genética , Reação em Cadeia da Polimerase em Tempo Real , Enzimas de Conjugação de Ubiquitina/metabolismo , UbiquitinaçãoRESUMO
OBJECTIVES: Neutrophil extracellular traps (NETs) act in various rheumatic diseases. Although NET formation was originally described as a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX)-dependent pathway, it appears that there are also NOX-independent pathways of NET release. Currently, no tools are available that can discriminate between both NET-forming pathways. We aimed to develop a serological method allowing the discrimination between NETs generated through NOX-dependent or NOX-independent pathways. METHODS: Histones from in vitro generated NOX-dependent and NOX-independent NETs were characterised with a panel of lupus-derived antibodies against N-terminal histone tails using immunofluorescence microscopy, western blot and ELISA. NETs in patients with NET-associated diseases, that is, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), psoriatic arthritis (PsA) and sepsis, were characterised in sandwich ELISAs employing antibodies against myeloperoxidase (MPO) and N-terminal histone tails as detecting and capturing antibodies, respectively. Functional responses of endothelial cells to NOX-dependent and NOX-independent NETs were assessed as well. RESULTS: Neutrophil elastase cleaves the N-terminal tails of core histones during NOX-dependent, but not during NOX-independent NET formation. Consequently, the detection of MPO-histone complexes with antibodies against N-terminal histone tails allows discrimination between NETs formed through a NOX-dependent or NOX-independent manner. Characterisation of in vivo circulating NETs revealed the presence of NOX-independent NETs in RA, SLE and sepsis, but NOX-dependent NETs in PsA. NOX-independent NETs displayed an increased capacity to activate endothelial cells when compared with NOX-dependent NETs. CONCLUSIONS: These results indicate heterogeneity in NET-forming pathways in vivo and highlight the need for disease-specific strategies to prevent NET-mediated pathology.
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Ensaio de Imunoadsorção Enzimática/métodos , Armadilhas Extracelulares/enzimologia , Histonas , NADPH Oxidases/análise , Anticorpos Monoclonais , Humanos , Doenças Reumáticas/imunologia , Sepse/imunologiaRESUMO
BACKGROUND: A single risk haplotype across UBE2L3 is strongly associated with systemic lupus erythematosus (SLE) and many other autoimmune diseases. UBE2L3 is an E2 ubiquitin-conjugating enzyme with specificity for RING-in-between-RING E3 ligases, including HOIL-1 and HOIP, components of the linear ubiquitin chain assembly complex (LUBAC), which has a pivotal role in inflammation, through crucial regulation of NF-κB. We aimed to determine whether UBE2L3 regulates LUBAC-mediated activation of NF-κB, and determine the effect of UBE2L3 genotype on NF-κB activation and B-cell differentiation. METHODS: UBE2L3 genotype data from SLE genome-wide association studies was imputed by use of 1000 Genomes data. UBE2L3 function was studied in a HEK293-NF-κB reporter cell line with standard molecular biology techniques. p65 NF-κB translocation in ex-vivo B cells and monocytes from genotyped healthy individuals was quantified by imaging flow cytometry. B-cell subsets from healthy individuals and patients with SLE, stratified by UBE2L3 genotype, were determined by multicolour flow cytometry. FINDINGS: rs140490, located at -270 base pairs of the UBE2L3 promoter, was identified as the most strongly associated single nucleotide polymorphism (p=8·6â×â10(-14), odds ratio 1·30, 95% CI 1·21-1·39). The rs140490 risk allele increased UBE2L3 expression in B cells and monocytes. Marked upregulation of NF-κB was observed with combined overexpression of UBE2L3 and LUBAC, but abolished by dominant-negative mutant UBE2L3 (C86S), or UBE2L3 silencing. The rs140490 genotype correlated with basal NF-κB activation in ex-vivo human B cells and monocytes, as well as NF-κB sensitivity to CD40 or tumour necrosis factor (TNF) stimulation. UBE2L3 expression was 3-4 times higher in circulating plasmablasts and plasma cells than in other B-cell subsets, with higher levels in patients with SLE than in controls. The rs140490 genotype correlated with increasing plasmablast and plasma cell differentiation in patients with SLE. INTERPRETATION: This study shows that NF-κB activation mediated by LUBAC is exquisitely sensitive to the expression level of UBE2L3. The UBE2L3 risk haplotype is correlated with TNF and CD40 induced NF-κB activation in primary human cells, and with plasmablast and plasma cell expansion in SLE, consistent with the dependence of these cells on NF-κB as a survival factor. Since UBE2L3 is highly expressed in plasma cells, UBE2L3 could be a novel therapeutic target in SLE. FUNDING: Arthritis Research UK, Wellcome Trust, George Koukis Foundation, European Community's Seventh Framework Programme.
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OBJECTIVES: To evaluate the feasibility, accuracy, usability and acceptability of two upper arm self-sampling devices for measurement of autoantibodies and C reactive protein (CRP) levels in patients with immune-mediated rheumatic diseases (IMRDs). METHODS: 70 consecutive patients with IMRD with previously documented autoantibodies were assigned to supervised and unsupervised self-collection of capillary blood with the Tasso+ or TAP II device. Interchangeability of 17 biomarkers with standard venesection was assessed by: concordance, correlation, paired sample hypothesis testing and Bland-Altman plots. Patients completed an evaluation questionnaire, including the System Usability Scale (SUS) and Net Promoter Score (NPS). RESULTS: While 80.0% and 77.0% were able to safely and successfully collect capillary blood using the Tasso+ and TAP II within the first attempt, 69 of 70 (98.6%) patients were successful in collecting capillary blood within two attempts. Concordance between venous and capillary samples was high; 94.7% and 99.5% for positive and negative samples, respectively. For connective tissue disease screen, anti-Ro52 and anti-proteinase 3 autoantibody levels, no significant differences were observed. Self-sampling was less painful than standard venesection for the majority of patients (Tasso+: 71%; TAP II: 63%). Both devices were well accepted (NPS; both: +28%), usability was perceived as excellent (SUS; Tasso+: 88.6 of 100; TAP II: 86.0 of 100) and 48.6 %/62.9% of patients would prefer to use the Tasso+/TAP II, respectively, instead of a traditional venous blood collection. CONCLUSIONS: Remote self-collection of capillary blood using upper arm-based devices for autoantibody and CRP analysis in patients with autoimmune rheumatic diseases is feasible, accurate and well accepted among patients. TRIAL REGISTRATION NUMBER: WHO International Clinical Trials Registry (DRKS00024925).
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Doenças Autoimunes , Doenças Reumáticas , Braço , Autoanticorpos , Humanos , Doenças Reumáticas/diagnóstico , Inquéritos e QuestionáriosRESUMO
BACKGROUND: Rheumatoid arthritis (RA) requires early diagnosis and tight surveillance of disease activity. Remote self-collection of blood for the analysis of inflammation markers and autoantibodies could improve the monitoring of RA and facilitate the identification of individuals at-risk for RA. OBJECTIVE: Randomized, controlled trial to evaluate the accuracy, feasibility, and acceptability of an upper arm self-sampling device (UA) and finger prick-test (FP) to measure capillary blood from RA patients for C-reactive protein (CRP) levels and the presence of IgM rheumatoid factor (RF IgM) and anti-cyclic citrullinated protein antibodies (anti-CCP IgG). METHODS: RA patients were randomly assigned in a 1:1 ratio to self-collection of capillary blood via UA or FP. Venous blood sampling (VBS) was performed as a gold standard in both groups to assess the concordance of CRP levels as well as RF IgM and CCP IgG. General acceptability and pain during sampling were measured and compared between UA, FP, and VBS. The number of attempts for successful sampling, requests for assistance, volume, and duration of sample collection were also assessed. RESULTS: Fifty seropositive RA patients were included. 49/50 (98%) patients were able to successfully collect capillary blood. The overall agreement between capillary and venous analyses for CRP (0.992), CCP IgG (0.984), and RF IgM (0.994) were good. In both groups, 4/25 (16%) needed a second attempt and 8/25 (32%) in the UA and 7/25 (28%) in the FP group requested assistance. Mean pain scores for capillary self-sampling (1.7/10 ± 1.1 (UA) and 1.9/10 ± 1.9 (FP)) were significantly lower on a numeric rating scale compared to venous blood collection (UA: 2.8/10 ± 1.7; FP: 2.1 ± 2.0) (p=0.003). UA patients were more likely to promote the use of capillary blood sampling (net promoter score: +28% vs. -20% for FP) and were more willing to perform blood collection at home (60% vs. 32% for FP). CONCLUSIONS: These data show that self-sampling is accurate and feasible within one attempt by the majority of patients without assistance, allowing tight monitoring of RA disease activity as well as identifying individuals at-risk for RA. RA patients seem to prefer upper arm-based self-sampling to traditional finger pricking. TRIAL REGISTRATION: DRKS.de Identifier: DRKS00023526 . Registered on November 6, 2020.
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Artrite Reumatoide , Autoanticorpos , Artrite Reumatoide/diagnóstico , Humanos , Imunoglobulina G , Imunoglobulina M , Inflamação , Dor , Peptídeos Cíclicos , Fator ReumatoideRESUMO
Introduction: An increasing number of digital tools, including dedicated diagnostic decision support systems (DDSS) exist to better assess new symptoms and understand when and where to seek medical care. The aim of this study was to evaluate patient's previous online assessment experiences and to compare the acceptability, usability, usefulness and potential impact of artificial intelligence (AI)-based symptom checker (Ada) and an online questionnaire-based self-referral tool (Rheport). Materials and Methods: Patients newly presenting to three German secondary rheumatology outpatient clinics were randomly assigned in a 1:1 ratio to complete consecutively Ada or Rheport in a prospective non-blinded multicentre controlled crossover randomized trial. DDSS completion time was recorded by local study personnel and perceptions on DDSS and previous online assessment were collected through a self-completed study questionnaire, including usability measured with the validated System Usability Scale (SUS). Results: 600 patients (median age 52 years, 418 women) were included. 277/600 (46.2%) of patients used an online search engine prior to the appointment. The median time patients spent assessing symptoms was 180, 7, and 8 min, respectively using online using search engines, Ada and Rheport. 111/275 (40.4%), 266/600 (44.3%) and 395/600 (65.8%) of patients rated the respective symptom assessment as very helpful or helpful, using online search engines, Ada and Rheport, respectively. Usability of both diagnostic decision support systems (DDSS) was "good" with a significantly higher mean SUS score (SD) of Rheport 77.1/100 (16.0) compared to Ada 74.4/100 (16.8), (p < 0.0001). In male patients, usability of Rheport was rated higher than Ada (p = 0.02) and the usability rating of older (52 years ≥) patients of both DDSS was lower than in younger participants (p = 0.005). Both effects were independent of each other. 440/600 (73.3%) and 475/600 (79.2%) of the patients would recommend Ada and Rheport to friends and other patients, respectively. Conclusion: In summary, patients increasingly assess their symptoms independently online, however only a minority used dedicated symptom assessment websites or DDSS. DDSS, such as Ada an Rheport are easy to use, well accepted among patients with musculoskeletal complaints and could replace online search engines for patient symptom assessment, potentially saving time and increasing helpfulness.
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Reumatologia , Inteligência Artificial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Percepção , Estudos Prospectivos , Avaliação de SintomasRESUMO
Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease with prominent chronic inflammatory aspects. SLE most often affects women (9:1) in childbearing age. The multifactorial nature of the etiopathogenesis of SLE involves a deficient clearance of dead and dying cells. This is supported by the occurrence of autoantibodies directed against autoantigens modified in dying and dead cells (dsDNA, high mobility group box 1 protein, apoptosis-associated chromatin modifications, e.g., histones H3-K27-me3; H2A/H4 AcK8,12,16; and H2B-AcK12) that are deposited in various tissues, including skin, kidneys, joints, muscles, and brain. The subsequent hyperinflammatory response often leads to irreparable tissue damage and organ destruction. In healthy individuals, dead and dying cells are rapidly removed by macrophages in an anti-inflammatory manner, referred to as efferocytosis. In SLE, extensive and prolonged cell death (apoptosis, necrosis, neutrophil extracellular trap (NET) formation) leads to autoantigens leaking out of the not cleared cell debris. These neo-epitopes are subsequently presented to B cells by follicular dendritic cells in the germinal centers of secondary lymphoid tissues conditioning the break of self-tolerance. Activation of autoreactive B cells and subsequent production of autoantibodies facilitate the formation of immune complexes (ICs) fueling the inflammatory response and leading to further tissue damage. ICs may also be ingested by phagocytes, which then produce further pro-inflammatory cytokines. These processes establish a vicious circle that leads to sustained inflammation. This review highlights the cell death-related events in SLE, the protagonists involved in SLE pathogenesis, the resolution of inflammation in various tissues affected in SLE, and explores strategies for intervention to restore hemostasis in a hyperinflammatory state.
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Lúpus Eritematoso Sistêmico/etiologia , Animais , Apoptose/genética , Apoptose/imunologia , Morte Celular , Suscetibilidade a Doenças , Humanos , Sistema Imunitário/imunologia , Sistema Imunitário/metabolismo , Lúpus Eritematoso Sistêmico/metabolismo , Fagócitos/imunologia , Fagócitos/metabolismo , Fagocitose/genética , Fagocitose/imunologiaRESUMO
Since the discovery and definition of neutrophil extracellular traps (NETs) 14 years ago, numerous characteristics and physiological functions of NETs have been uncovered. Nowadays, the field continues to expand and novel mechanisms that orchestrate formation of NETs, their previously unknown properties, and novel implications in disease continue to emerge. The abundance of available data has also led to some confusion in the NET research community due to contradictory results and divergent scientific concepts, such as pro- and anti-inflammatory roles in pathologic conditions, demarcation from other forms of cell death, or the origin of the DNA that forms the NET scaffold. Here, we present prevailing concepts and state of the science in NET-related research and elaborate on open questions and areas of dispute.
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Armadilhas Extracelulares/metabolismo , Neutrófilos/metabolismo , HumanosRESUMO
Rheumatic diseases are a group of inflammatory conditions that affect joints and connective tissues and are often accompanied by pain and restriction of motility. In many of these diseases, autoantibodies develop that react with molecules/structures commonly found hidden in neutrophils. Neutrophil extracellular trap (NET) formation and release is considered a defense mechanism against pathogens or endogenous danger signals and it has been associated with initial inflammatory responses. NETs are also endowed with an important resolution potential based on its intrinsic enzymatic activity, but in the case they are not timely removed from the crime scene they might modulate subsequent immune responses and contribute to the pathogenesis of chronic inflammatory diseases. In this review, we will summarize the actual knowledge about the multifaceted roles of NETs in the etiology and pathogenesis of rheumatic autoimmune diseases.
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Doenças Autoimunes/imunologia , Armadilhas Extracelulares/imunologia , Inflamação/imunologia , Neutrófilos/imunologia , Doenças Reumáticas/imunologia , Animais , Autoanticorpos/sangue , Autoanticorpos/imunologia , Autoantígenos/imunologia , Autoantígenos/metabolismo , Doenças Autoimunes/sangue , Doença Crônica , Modelos Animais de Doenças , Armadilhas Extracelulares/metabolismo , Humanos , Inflamação/sangue , Neutrófilos/metabolismo , Doenças Reumáticas/sangueRESUMO
Deficient clearance of apoptotic cells reportedly contributes to the etiopathogenesis of the autoimmune disease systemic lupus erythematosus (SLE). Based on this knowledge, we developed a highly specific and sensitive test for the detection of SLE autoantibodies (AAb) utilizing secondary NEcrotic cell (SNEC)-derived material as a substrate. The goal of the present study was to validate the use of SNEC as an appropriate antigen for the diagnosis of SLE in large cohort of patients. We confirmed the presence of apoptotically modified autoantigens on SNEC (dsDNA, high mobility group box 1 protein, apoptosis-associated chromatin modifications, e.g., histones H3-K27-me3; H2A/H4 AcK8,12,16; and H2B-AcK12). Anti-SNEC AAb were measured in the serum of 155 patients with SLE, 89 normal healthy donors (NHD), and 169 patients with other autoimmune connective tissue diseases employing SNEC-based indirect enzyme-linked immunosorbent assay (SNEC ELISA). We compared the test performance of SNEC ELISA with the routine diagnostic tests dsDNA Farr radioimmunoassay (RIA) and nucleosome-based ELISA (anti-dsDNA-NcX-ELISA). SNEC ELISA distinguished patients with SLE with a specificity of 98.9% and a sensitivity of 70.6% from NHD clearly surpassing RIA and anti-dsDNA-NcX-ELISA. In contrast to the other tests, SNEC ELISA significantly discriminated patients with SLE from patients with rheumatoid arthritis, primary anti-phospholipid syndrome, spondyloarthropathy, psoriatic arthritis, and systemic sclerosis. A positive test result in SNEC ELISA significantly correlated with serological variables and reflected the uptake of opsonized SNEC by neutrophils. This stresses the relevance of SNECs in the pathogenesis of SLE. We conclude that SNEC ELISA allows for the sensitive detection of pathologically relevant AAb, enabling its diagnostic usage. A positive SNEC test reflects the opsonization of cell remnants by AAb, the neutrophil recruitment to tissues, and the enhancement of local and systemic inflammatory responses.
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Anticorpos Antinucleares/sangue , Lúpus Eritematoso Sistêmico/diagnóstico , Lúpus Eritematoso Sistêmico/imunologia , Neutrófilos/imunologia , Fagocitose , Adulto , Idoso , Apoptose/imunologia , Autoantígenos , Estudos de Coortes , DNA/análise , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Necrose/imunologia , Radioimunoensaio , Adulto JovemRESUMO
OBJECTIVES: Impaired clearance of dying and dead cells by professional and amateur phagocytes plays a crucial role in the etiology of systemic lupus erythematosus (SLE). While dying, cells expose and release a plethora of eat-me and find-me signals to ensure their timely removal before entering the dangerous stage of secondary necrosis. A well-described chemoattractant for macrophages is dying cell-derived lysophosphatidylcholine (LPC). However, its implications for and/or its association with SLE disease, so far, have not been examined. In the present study, we analyzed the LPC serum concentrations of patients with SLE and rheumatoid arthritis (RA). Subsequently, we examined if and to which extent the measured serum concentrations of LPC and an LPC-rich environment can impact the phagocytosis of necrotic cells. METHODS: Sera from patients with SLE, RA, and normal healthy donors (NHD) were characterized for several parameters, including LPC concentrations. Phagocytosis of dead cells by human macrophages in the presence of SLE and NHD sera was quantified. Additionally, the impact of exogenously added, purified LPC on phagocytosis was analyzed. RESULTS: Patients with SLE had significantly increased LPC serum levels, and high serum LPC of SLE patients correlated significantly with impaired phagocytosis of dead cells in the presence of heat-inactivated serum. Phagocytosis in the presence of sera from NHD showed no correlation to LPC levels, but exogenous addition of purified LPC in the range as measured in SLE patients' sera led to a concentration-dependent decrease. CONCLUSION: Our data show that high levels of LPC as observed in the sera of SLE patients have a negative impact on the clearance of dead cells by macrophages. Chemoattraction requires a concentration gradient. The higher the LPC concentration surrounding a dying or dead cell, the smaller the achievable gradient upon LPC release will be. Thus, it is feasible to assume that elevated LPC levels can interfere with the build-up of a local LPC gradient during cell death, and hence might play a role in the establishment and/or perpetuation of SLE disease.