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1.
Nat Neurosci ; 23(9): 1067-1078, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32661396

RESUMO

Complement-mediated synapse elimination has emerged as an important process in both brain development and neurological diseases, but whether neurons express complement inhibitors that protect synapses against complement-mediated synapse elimination remains unknown. Here, we show that the sushi domain protein SRPX2 is a neuronally expressed complement inhibitor that regulates complement-dependent synapse elimination. SRPX2 directly binds to C1q and blocks its activity, and SRPX2-/Y mice show increased C3 deposition and microglial synapse engulfment. They also show a transient decrease in synapse numbers and increase in retinogeniculate axon segregation in the lateral geniculate nucleus. In the somatosensory cortex, SRPX2-/Y mice show decreased thalamocortical synapse numbers and increased spine pruning. C3-/-;SRPX2-/Y double-knockout mice exhibit phenotypes associated with C3-/- mice rather than SRPX2-/Y mice, which indicates that C3 is necessary for the effect of SRPX2 on synapse elimination. Together, these results show that SRPX2 protects synapses against complement-mediated elimination in both the thalamus and the cortex.


Assuntos
Encéfalo/embriologia , Proteínas do Sistema Complemento , Proteínas de Membrana/metabolismo , Neurogênese/fisiologia , Plasticidade Neuronal/fisiologia , Animais , Encéfalo/metabolismo , Ativação do Complemento/fisiologia , Camundongos , Camundongos Knockout
2.
J Immunol ; 205(6): 1488-1495, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32699160

RESUMO

Coronavirus disease of 2019 (COVID-19) is a highly contagious respiratory infection that is caused by the severe acute respiratory syndrome coronavirus 2. Although most people are immunocompetent to the virus, a small group fail to mount an effective antiviral response and develop chronic infections that trigger hyperinflammation. This results in major complications, including acute respiratory distress syndrome, disseminated intravascular coagulation, and multiorgan failure, which all carry poor prognoses. Emerging evidence suggests that the complement system plays a key role in this inflammatory reaction. Indeed, patients with severe COVID-19 show prominent complement activation in their lung, skin, and sera, and those individuals who were treated with complement inhibitors all recovered with no adverse reactions. These and other studies hint at complement's therapeutic potential in these sequalae, and thus, to support drug development, in this review, we provide a summary of COVID-19 and review complement's role in COVID-19 acute respiratory distress syndrome and coagulopathy.


Assuntos
Transtornos da Coagulação Sanguínea/virologia , Ativação do Complemento/fisiologia , Infecções por Coronavirus/complicações , Pneumonia Viral/complicações , /virologia , Animais , Betacoronavirus/imunologia , Coagulação Sanguínea/efeitos dos fármacos , Transtornos da Coagulação Sanguínea/imunologia , Ativação do Complemento/efeitos dos fármacos , Inativadores do Complemento/uso terapêutico , Proteínas do Sistema Complemento/efeitos dos fármacos , Infecções por Coronavirus/sangue , Infecções por Coronavirus/imunologia , Humanos , Inflamação/imunologia , Inflamação/virologia , Pandemias , Pneumonia Viral/sangue , Pneumonia Viral/imunologia
4.
Transl Res ; 220: 1-13, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32299776

RESUMO

Acute respiratory failure and a systemic coagulopathy are critical aspects of the morbidity and mortality characterizing infection with severe acute respiratory distress syndrome-associated coronavirus-2, the etiologic agent of Coronavirus disease 2019 (COVID-19). We examined skin and lung tissues from 5 patients with severe COVID-19 characterized by respiratory failure (n= 5) and purpuric skin rash (n = 3). COVID-19 pneumonitis was predominantly a pauci-inflammatory septal capillary injury with significant septal capillary mural and luminal fibrin deposition and permeation of the interalveolar septa by neutrophils. No viral cytopathic changes were observed and the diffuse alveolar damage (DAD) with hyaline membranes, inflammation, and type II pneumocyte hyperplasia, hallmarks of classic acute respiratory distress syndrome, were not prominent. These pulmonary findings were accompanied by significant deposits of terminal complement components C5b-9 (membrane attack complex), C4d, and mannose binding lectin (MBL)-associated serine protease (MASP)2, in the microvasculature, consistent with sustained, systemic activation of the complement pathways. The purpuric skin lesions similarly showed a pauci-inflammatory thrombogenic vasculopathy, with deposition of C5b-9 and C4d in both grossly involved and normally-appearing skin. In addition, there was co-localization of COVID-19 spike glycoproteins with C4d and C5b-9 in the interalveolar septa and the cutaneous microvasculature of 2 cases examined. In conclusion, at least a subset of sustained, severe COVID-19 may define a type of catastrophic microvascular injury syndrome mediated by activation of complement pathways and an associated procoagulant state. It provides a foundation for further exploration of the pathophysiologic importance of complement in COVID-19, and could suggest targets for specific intervention.


Assuntos
Betacoronavirus , Proteínas do Sistema Complemento/metabolismo , Infecções por Coronavirus/complicações , Microvasos/patologia , Pneumonia Viral/complicações , Insuficiência Respiratória/etiologia , Trombose/etiologia , Adulto , Idoso , Ativação do Complemento/fisiologia , Infecções por Coronavirus/patologia , Feminino , Humanos , Masculino , Microvasos/virologia , Pessoa de Meia-Idade , Pandemias , Pneumonia Viral/patologia , Púrpura/etiologia , Púrpura/patologia , Púrpura/virologia , Insuficiência Respiratória/patologia , Trombose/patologia
5.
Invest Ophthalmol Vis Sci ; 61(3): 45, 2020 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-32207814

RESUMO

Purpose: Age-related macular degeneration (AMD) is the leading cause of blindness in Western populations. While an overactive complement system has been linked to pathogenesis, mechanisms contributing to its activation are largely unknown. In aged and AMD eyes, loss of the elastin layer (EL) of Bruch's membrane (BrM) has been reported. Elastin antibodies are elevated in patients with AMD, the pathogenic significance of which is unclear. Here we assess the role of elastin antibodies using a mouse model of smoke-induced ocular pathology (SIOP), which similarly demonstrates EL loss. Methods: C57BL/6J mice were immunized with elastin or elastin peptide oxidatively modified by cigarette smoke (ox-elastin). Mice were then exposed to cigarette smoke or air for 6 months. Visual function was assessed by optokinetic response, retinal morphology by spectral-domain optical coherence tomography and electron microscopy, and complement activation and antibody deposition by Western blot. Results: Ox-elastin IgG and IgM antibodies were elevated in ox-elastin immunized mice following 6 months of smoke, whereas elastin immunization had a smaller effect. Ox-elastin immunization exacerbated smoke-induced vision loss, with thicker BrM and more damaged retinal pigment epithelium (RPE) mitochondria compared with mice immunized with elastin or nonimmunized controls. These changes were correlated with increased levels of IgM, IgG2, IgG3, and complement activation products in RPE/choroid. Conclusions: These data demonstrate that SIOP mice generate elastin-specific antibodies and that immunization with ox-elastin exacerbates ocular pathology. Elastin antibodies represented complement fixing isotypes that, together with the increased presence of complement activation seen in immunized mice, suggest that elastin antibodies exert pathogenic effects through mediating complement activation.


Assuntos
Autoanticorpos/sangue , Lâmina Basilar da Corioide/patologia , Modelos Animais de Doenças , Elastina/imunologia , Atrofia Geográfica/etiologia , Epitélio Pigmentado da Retina/patologia , Fumar/efeitos adversos , Animais , Western Blotting , Ativação do Complemento/fisiologia , Proteínas do Sistema Complemento/metabolismo , Sensibilidades de Contraste/fisiologia , Ensaio de Imunoadsorção Enzimática , Atrofia Geográfica/imunologia , Atrofia Geográfica/patologia , Imunização , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Camundongos , Camundongos Endogâmicos C57BL , Nistagmo Optocinético/fisiologia , Oxirredução , Produtos do Tabaco , Acuidade Visual/fisiologia
7.
Am J Pathol ; 190(6): 1138-1150, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32194049

RESUMO

The complement membrane attack complex (MAC) is classically known as a cytolytic effector of innate and adaptive immunity that forms pores in the plasma membrane of pathogens or targeted cells, leading to osmolysis. Nucleated cells resist MAC-mediated cytolysis by expression of inhibitors that block MAC assembly or by rapid removal of MAC through endocytosis or shedding. In the absence of lysis, MAC may induce intracellular signaling and cell activation, responses implicated in a variety of autoimmune, inflammatory, and transplant disease settings. New discoveries into the structure and biophysical properties of MAC revealed heterogeneous MAC precursors and conformations that provide insights into MAC function. In addition, new mechanisms of MAC-mediated signaling and its contribution to disease pathogenesis have recently come to light. MAC-activated cells have been found to express proinflammatory proteins-often through NF-κB-dependent transcription, assemble inflammasomes, enabling processing, and facilitate secretion of IL-1ß and IL-18, as well as other signaling pathways. These recent insights into the mechanisms of action of MAC provide an updated framework to therapeutic approaches that can target MAC assembly, signaling, and proinflammatory effects in various complement-mediated diseases.


Assuntos
Imunidade Adaptativa/fisiologia , Ativação do Complemento/fisiologia , Complexo de Ataque à Membrana do Sistema Complemento/metabolismo , Imunidade Inata/fisiologia , Animais , Humanos , Interleucinas/metabolismo , NF-kappa B/metabolismo , Transdução de Sinais/fisiologia
8.
J Am Soc Nephrol ; 31(4): 829-840, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32034108

RESUMO

BACKGROUND: The pathophysiology of the leading cause of pediatric acute nephritis, acute postinfectious GN, including mechanisms of the pathognomonic transient complement activation, remains uncertain. It shares clinicopathologic features with C3 glomerulopathy, a complement-mediated glomerulopathy that, unlike acute postinfectious GN, has a poor prognosis. METHODS: This retrospective study investigated mechanisms of complement activation in 34 children with acute postinfectious GN and low C3 level at onset. We screened a panel of anticomplement protein autoantibodies, carried out related functional characterization, and compared results with those of 60 children from the National French Registry who had C3 glomerulopathy and persistent hypocomplementemia. RESULTS: All children with acute postinfectious GN had activation of the alternative pathway of the complement system. At onset, autoantibodies targeting factor B (a component of the alternative pathway C3 convertase) were found in a significantly higher proportion of children with the disorder versus children with hypocomplementemic C3 glomerulopathy (31 of 34 [91%] versus 4 of 28 [14%], respectively). In acute postinfectious GN, anti-factor B autoantibodies were transient and correlated with plasma C3 and soluble C5b-9 levels. We demonstrated that anti-factor B antibodies enhance alternative pathway convertase activity in vitro, confirming their pathogenic effect. We also identified crucial antibody binding sites on factor B, including one correlated to disease severity. CONCLUSIONS: These findings elucidate the pathophysiologic mechanisms underlying acute postinfectious GN by identifying anti-factor B autoantibodies as contributing factors in alternative complement pathway activation. At onset of a nephritic syndrome with low C3 level, screening for anti-factor B antibodies might help guide indications for kidney biopsy to avoid misdiagnosed chronic glomerulopathy, such as C3 glomerulopathy, and to help determine therapy.


Assuntos
Autoanticorpos/sangue , Ativação do Complemento/fisiologia , Complemento C3/metabolismo , Fator B do Complemento/imunologia , Glomerulonefrite/sangue , Glomerulonefrite/diagnóstico , Criança , Pré-Escolar , Fator Nefrítico do Complemento 3/metabolismo , Feminino , França , Humanos , Masculino , Estudos Retrospectivos
9.
J Immunol ; 204(7): 1919-1928, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32094208

RESUMO

The complement system constitutes an important part of the innate immune system. The collectins and the ficolins are soluble pattern recognition molecules that contribute to complement activation via the lectin pathway. During previous experiments with ficolin-2 and ficolin-3, we have observed that the molecules may interact. We therefore hypothesized the existence of stable ficolin-2/-3 heterocomplexes. We could demonstrate ficolin-2/-3 heterocomplexes in normal human serum and plasma by ELISA using Abs specific for ficolin-2 and ficolin-3. The formation of heteromeric protein complexes were validated by coimmunoprecipitation and Western blot analysis. When recombinant ficolin-2 and recombinant ficolin-3 were mixed, no complexes were formed. However, when coexpressing ficolin-2 and ficolin-3 in Chinese hamster ovary cells, we could detect ficolin-2/-3 heterocomplexes in the supernatant. Furthermore, we measured concentration of the ficolin-2/-3 heterocomplexes in arbitrary units in 94 healthy individuals. We also established the relationship between the concentrations of ficolin-2, ficolin-3, and the ficolin-2/-3 heterocomplexes. We observed that the concentration of the ficolin-2/-3 heterocomplex correlated significantly with ficolin-2 (ρ: 0.24, p < 0.018) and ficolin-3 concentrations (ρ: 0.46, p < 0.0001). In conclusion, we describe a novel protein complex between ficolin-2 and ficolin-3 present in serum and plasma, which might be of additional biological relevance apart from the native ficolin-2 and ficolin-3 molecules.


Assuntos
Lectinas/sangue , Animais , Células CHO , Linhagem Celular , Colectinas/metabolismo , Ativação do Complemento/fisiologia , Lectina de Ligação a Manose da Via do Complemento/fisiologia , Proteínas do Sistema Complemento/metabolismo , Cricetulus , Humanos , Serina Proteases Associadas a Proteína de Ligação a Manose/metabolismo , Camundongos
10.
J Neuroimmunol ; 340: 577147, 2020 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-31951875

RESUMO

To assess if markers of complement activation are associated with disease activity, C1q, C3, C3a and sC5b-9 levels in plasma and cerebrospinal fluid (CSF) were determined in 41 patients with clinically isolated syndrome (CIS) or remitting multiple sclerosis (RRMS), in a prospective longitudinal four-year cohort study. C1q in CSF (CSF-C1q) was significantly higher in patients than in controls. Baseline CSF-C1q and CSF-C3a correlated with several neuroinflammatory markers and neurofilament light chain levels. Baseline CSF-C3a correlated with the number of T2 lesions at baseline and new T2 lesions during follow-up. Baseline CSF-C3a was also significantly higher in patients with (n = 21) than in patients without (n = 20) signs of disease activity according to the NEDA-3 concept during one year of follow-up (p ≤ .01) Study results support that complement activation is involved in MS pathophysiology and that CSF-C3a carries prognostic information.


Assuntos
Ativação do Complemento/fisiologia , Doenças Desmielinizantes/líquido cefalorraquidiano , Doenças Desmielinizantes/imunologia , Esclerose Múltipla Recidivante-Remitente/líquido cefalorraquidiano , Esclerose Múltipla Recidivante-Remitente/imunologia , Adulto , Estudos de Coortes , Proteínas do Sistema Complemento/líquido cefalorraquidiano , Feminino , Humanos , Estudos Longitudinais , Masculino , Estudos Prospectivos
11.
Mol Psychiatry ; 25(1): 206-229, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31570775

RESUMO

Increased expression of the 3.1 isoform of the KCNH2 potassium channel has been associated with cognitive dysfunction and with schizophrenia, yet little is known about the underlying pathophysiological mechanisms. Here, by using in vivo wireless local field potential recordings during working memory processing, in vitro brain slice whole-cell patching recordings and in vivo stereotaxic hippocampal injection of AAV-encoded expression, we identified specific and delayed disruption of hippocampal-mPFC synaptic transmission and functional connectivity associated with reductions of SERPING1, CFH, and CD74 in the KCNH2-3.1 overexpression transgenic mice. The differentially expressed genes in mice are enriched in neurons and microglia, and reduced expression of these genes dysregulates the complement cascade, which has been previously linked to synaptic plasticity. We find that knockdown of these genes in primary neuronal-microglial cocultures from KCNH2-3.1 mice impairs synapse formation, and replenishing reduced CFH gene expression rescues KCNH2-3.1-induced impaired synaptogenesis. Translating to humans, we find analogous dysfunctional interactions between hippocampus and prefrontal cortex in coupling of the fMRI blood oxygen level-dependent (BOLD) signal during working memory in healthy subjects carrying alleles associated with increased KCNH2-3.1 expression in brain. Our data uncover a previously unrecognized role of the truncated KCNH2-3.1 potassium channel in mediating complement activation, which may explain its association with altered hippocampal-prefrontal connectivity and synaptic function. These results provide a potential molecular link between increased KCNH2-3.1 expression, synapse alterations, and hippocampal-prefrontal circuit abnormalities implicated in schizophrenia.


Assuntos
Ativação do Complemento/fisiologia , Canal de Potássio ERG1/metabolismo , Memória de Curto Prazo/fisiologia , Animais , Encéfalo/metabolismo , Disfunção Cognitiva/genética , Ativação do Complemento/imunologia , Canal de Potássio ERG1/genética , Feminino , Hipocampo/metabolismo , Humanos , Imagem por Ressonância Magnética , Masculino , Transtornos da Memória/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Plasticidade Neuronal/fisiologia , Neurônios/metabolismo , Córtex Pré-Frontal/metabolismo , Esquizofrenia/genética , Esquizofrenia/metabolismo , Transmissão Sináptica/fisiologia , Lobo Temporal/metabolismo
12.
Eur J Ophthalmol ; 30(5): 1061-1068, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31203676

RESUMO

PURPOSE: To examine the role of systemic activation of the complement system (assessed by levels of circulating C3a, Ba, and sC5b-9) in patients (n = 122) with advanced age-related macular degeneration, geographic atrophy, and neovascular age-related macular degeneration, compared with cataract controls (n = 27). METHODS: Plasma complement factors were measured using enzyme-linked immunosorbent assays. Statistical analysis included univariate and multivariate logistic regression (p < 0.05). RESULTS: Adjusted for age, the odds ratios of C3a and sC5b-9 for any advanced age-related macular degeneration were 1.78 (95% confidence interval = 1.16-2.73, p < 0.01) and 1.20 (95% confidence interval = 1.04-1.39, p = 0.01), respectively. We found a significantly elevated adjusted odds ratio of C3a (adjusted odds ratio = 1.71, 95% confidence interval = 1.12-2.60, p = 0.01) and sC5b-9 (adjusted odds ratio = 1.22, 95% confidence interval = 1.04-1.43, p = 0.01) for neovascular age-related macular degeneration. Adjusted for age, neither C3a, sC5b-9, nor Ba were associated with geographic atrophy. CONCLUSION: We suggest a role for elevated plasma levels of C3a and sC5b-9 in patients with neovascular age-related macular degeneration. The study's results reinforce the need for more investigation to assess the impact of therapeutic interventions targeted at the complement signaling pathways in age-related macular degeneration.


Assuntos
Neovascularização de Coroide/sangue , Ativação do Complemento/fisiologia , Complemento C3a/metabolismo , Fator B do Complemento/metabolismo , Complexo de Ataque à Membrana do Sistema Complemento/metabolismo , Atrofia Geográfica/sangue , Degeneração Macular Exsudativa/sangue , Idoso , Idoso de 80 Anos ou mais , Neovascularização de Coroide/diagnóstico , Ensaio de Imunoadsorção Enzimática , Feminino , Angiofluoresceinografia , Atrofia Geográfica/diagnóstico , Humanos , Masculino , Razão de Chances , Tomografia de Coerência Óptica , Degeneração Macular Exsudativa/diagnóstico
13.
Hypertension ; 75(2): 422-430, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31865800

RESUMO

Hypertensive emergency can cause thrombotic microangiopathy (TMA) in the kidneys with high rates of end-stage renal disease (ESRD) and vice versa. The conundrum of hypertension as the cause of TMA or consequence of TMA on the background of defects in complement regulation remains difficult. Patients with hypertensive emergency and TMA on kidney biopsy were tested for ex vivo C5b9 formation on the endothelium and rare variants in complement genes to identify complement-mediated TMA. We identified factors associated with defects in complement regulation and poor renal outcomes. Massive ex vivo C5b9 formation was found on resting endothelial cells in 18 (69%) out of 26 cases at the presentation, including the 9 patients who carried at least one rare genetic variant. Thirteen (72%, N=18) and 3 (38%, N=8) patients with massive and normal ex vivo complement activation, respectively, progressed to ESRD (P=0.03). In contrast to BP control, inhibition of C5 activation prevented ESRD to occur in 5 (83%, N=6) patients with massive ex vivo complement activation. TMA-related graft failure occurred in 7 (47%, N=15) donor kidneys and was linked to genetic variants. The assessment of both ex vivo C5b9 formation and screening for rare variants in complement genes may categorize patients with hypertensive emergency and TMA into different groups with potential therapeutic and prognostic implications. We propose an algorithm to recognize patients at the highest risk for defects in complement regulation.


Assuntos
Pressão Sanguínea/fisiologia , Ativação do Complemento/fisiologia , Proteínas do Sistema Complemento/metabolismo , Emergências , Hipertensão Maligna/complicações , Rim/patologia , Microangiopatias Trombóticas/diagnóstico , Adulto , Biópsia , Células Endoteliais/patologia , Feminino , Humanos , Hipertensão Maligna/diagnóstico , Falência Renal Crônica/complicações , Falência Renal Crônica/diagnóstico , Masculino , Prognóstico , Reprodutibilidade dos Testes , Fatores de Risco , Microangiopatias Trombóticas/etiologia , Microangiopatias Trombóticas/metabolismo
14.
Front Immunol ; 11: 594849, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33584662

RESUMO

Most patients who became critically ill following infection with COVID-19 develop severe acute respiratory syndrome (SARS) attributed to a maladaptive or inadequate immune response. The complement system is an important component of the innate immune system that is involved in the opsonization of viruses but also in triggering further immune cell responses. Complement activation was seen in plasma adsorber material that clogged during the treatment of critically ill patients with COVID-19. Apart from the lung, the kidney is the second most common organ affected by COVID-19. Using immunohistochemistry for complement factors C1q, MASP-2, C3c, C3d, C4d, and C5b-9 we investigated the involvement of the complement system in six kidney biopsies with acute kidney failure in different clinical settings and three kidneys from autopsy material of patients with COVID-19. Renal tissue was analyzed for signs of renal injury by detection of thrombus formation using CD61, endothelial cell rarefaction using the marker E-26 transformation specific-related gene (ERG-) and proliferation using proliferating cell nuclear antigen (PCNA)-staining. SARS-CoV-2 was detected by in situ hybridization and immunohistochemistry. Biopsies from patients with hemolytic uremic syndrome (HUS, n = 5), severe acute tubular injury (ATI, n = 7), zero biopsies with disseminated intravascular coagulation (DIC, n = 7) and 1 year protocol biopsies from renal transplants (Ctrl, n = 7) served as controls. In the material clogging plasma adsorbers used for extracorporeal therapy of patients with COVID-19 C3 was the dominant protein but collectin 11 and MASP-2 were also identified. SARS-CoV-2 was sporadically present in varying numbers in some biopsies from patients with COVID-19. The highest frequency of CD61-positive platelets was found in peritubular capillaries and arteries of COVID-19 infected renal specimens as compared to all controls. Apart from COVID-19 specimens, MASP-2 was detected in glomeruli with DIC and ATI. In contrast, the classical pathway (i.e. C1q) was hardly seen in COVID-19 biopsies. Both C3 cleavage products C3c and C3d were strongly detected in renal arteries but also occurs in glomerular capillaries of COVID-19 biopsies, while tubular C3d was stronger than C3c in biopsies from COVID-19 patients. The membrane attack complex C5b-9, demonstrating terminal pathway activation, was predominantly deposited in COVID-19 biopsies in peritubular capillaries, renal arterioles, and tubular basement membrane with similar or even higher frequency compared to controls. In conclusion, various complement pathways were activated in COVID-19 kidneys, the lectin pathway mainly in peritubular capillaries and in part the classical pathway in renal arteries whereas the alternative pathway seem to be crucial for tubular complement activation. Therefore, activation of the complement system might be involved in the worsening of renal injury. Complement inhibition might thus be a promising treatment option to prevent deregulated activation and subsequent collateral tissue injury.


Assuntos
Lesão Renal Aguda/imunologia , Lesão Renal Aguda/virologia , /imunologia , Ativação do Complemento/fisiologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
15.
PLoS Pathog ; 15(12): e1008232, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31860690

RESUMO

Ecotin is a serine protease inhibitor produced by hundreds of microbial species, including pathogens. Here we show, that ecotin orthologs from Escherichia coli, Yersinia pestis, Pseudomonas aeruginosa and Leishmania major are potent inhibitors of MASP-1 and MASP-2, the two key activator proteases of the complement lectin pathway. Factor D is the key activator protease of another complement activation route, the alternative pathway. We show that ecotin inhibits MASP-3, which is the sole factor D activator in resting human blood. In pathway-specific ELISA tests, we found that all ecotin orthologs are potent lectin pathway inhibitors, and at high concentration, they block the alternative pathway as well. In flow cytometry experiments, we compared the extent of complement-mediated opsonization and lysis of wild-type and ecotin-knockout variants of two E. coli strains carrying different surface lipopolysaccharides. We show, that endogenous ecotin provides significant protections against these microbicidal activities for both bacteria. By using pathway specific complement inhibitors, we detected classical-, lectin- and alternative pathway-driven complement attack from normal serum, with the relative contributions of the activation routes depending on the lipopolysaccharide type. Moreover, in cell proliferation experiments we observed an additional, complement-unrelated antimicrobial activity exerted by heat-inactivated serum. While ecotin-knockout cells are highly vulnerable to these activities, endogenous ecotin of wild-type bacteria provides complete protection against the lectin pathway-related and the complement-unrelated attack, and partial protection against the alternative pathway-related damage. In all, ecotin emerges as a potent, versatile self-defense tool that blocks multiple antimicrobial activities of the serum. These findings suggest that ecotin might be a relevant antimicrobial drug target.


Assuntos
Lectina de Ligação a Manose da Via do Complemento/fisiologia , Proteínas do Sistema Complemento/metabolismo , Proteínas de Escherichia coli/metabolismo , Proteínas Periplásmicas/metabolismo , Serina Proteases/sangue , Ativação do Complemento/fisiologia , Escherichia coli/metabolismo , Humanos , Pseudomonas aeruginosa/metabolismo , Serina Endopeptidases/metabolismo , Inibidores de Serino Proteinase/metabolismo , Yersinia pestis/metabolismo
16.
Transfus Med Rev ; 33(4): 199-206, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31672340

RESUMO

Two complex protein defense systems-complement and coagulation-are based on amplifying enzyme cascades triggered by specific local stimuli. Excess systemic activation of either system is pathologic and is normally prevented by a family of regulatory proteins. The 2 systems are ancient biological processes which share a common origin that predates vertebrate evolution. Recent research has uncovered multiple opportunities for cross talk between complement and coagulation including proteins traditionally viewed as coagulation factors that activate and regulate complement, and proteins traditionally seen as part of the complement system that participate in coagulation. Ten examples of cross talk between the 2 systems are described. The mutual engagement of both systems is increasingly recognized to occur in human diseases. Three conditions-paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, and the antiphospholipid syndrome-provide examples of the importance of interactions between complement and coagulation in human biology. A better understanding of the mutual engagement of these 2 ancient defense systems is expected to result in improved diagnostics and new treatments for systemic diseases.


Assuntos
Coagulação Sanguínea/fisiologia , Proteínas do Sistema Complemento/fisiologia , Animais , Síndrome Antifosfolipídica/fisiopatologia , Síndrome Hemolítico-Urêmica Atípica/fisiopatologia , Evolução Biológica , Fatores de Coagulação Sanguínea/fisiologia , Ativação do Complemento/fisiologia , Hemoglobinúria Paroxística/fisiopatologia , Caranguejos Ferradura , Humanos
17.
Transfus Med Rev ; 33(4): 225-230, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31672341

RESUMO

Transfusion-related hemolysis is classically the result of an interaction between antibodies produced by the recipient and blood group antigens carried by the donor red blood cells. This reaction may be life threatening, especially in sickle cell patients when they develop hyperhemolysis with concomitant accelerated clearance of their own red blood cells. The complement system is a key participant in the pathophysiology of post-transfusion hemolysis. Complement can trigger the hemolytic reaction, amplify the inflammatory response and increase tissue damage. Complement is activated by the classical pathway but may also be activated by the alternative pathway in sickle cell disease. The hemolysis-derived products permanently released by sickle cell patients with chronic hemolytic anemia may affect the potency of complement activation. All the observations in sickle cell patients as well as in vitro experiments and in vivo data in animal models support the conclusion that complement is key disease driver and a promising therapeutic target in the context of transfusion-related hemolysis and hyperhemolysis.


Assuntos
Proteínas do Sistema Complemento/fisiologia , Hemólise/imunologia , Reação Transfusional/imunologia , Anemia Hemolítica/imunologia , Anemia Falciforme/imunologia , Anemia Falciforme/terapia , Animais , Incompatibilidade de Grupos Sanguíneos/imunologia , Ativação do Complemento/fisiologia , Inativadores do Complemento/uso terapêutico , Proteínas do Sistema Complemento/imunologia , Eritrócitos/imunologia , Humanos , Isoanticorpos/sangue , Reação Transfusional/tratamento farmacológico , Reação Transfusional/fisiopatologia
18.
Drug Des Devel Ther ; 13: 3693-3704, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31695336

RESUMO

Purpose: Spinal cord injury (SCI) is a relatively common, devastating traumatic condition resulting in permanent disability. In this study, the use of exosomes derived from bone mesenchymal stem cells (BMSCs-Exo) as a cell-free therapy for the treatment of SCI in rats was investigated to gain insights into their mechanisms of action. Methods: Rats were randomly divided into three groups, Sham (treated with PBS), SCI (SCI injury + PBS) and SCI + Exo (SCI injury + BMSCs-Exo). Changes in the complement system between the three groups were assessed with the use of proteomics. The proteomic data were verified using reverse transcription-polymerase chain reaction (RT-PCR). In addition, the distributions of BMSCs-Exo in rats with SCI were detected by immunofluorescence. Moreover, SCI-activated NF-κB levels were determined using Western blot. Results: SCI insult increased complement levels, including C4, C5, C6, C4 binding protein alpha and complement factor H. In contrast, the SCI + BMSCs-Exo group exhibited attenuated SCI-induced complement levels. Immunofluorescence assay results revealed that BMSCs-Exo mainly accumulated at the spinal cord injury site and were bound to microglia cells. Western blot analysis of tissue lysates showed that BMSCs-Exo treatment also inhibited SCI-activated nuclear factor kappa-B (NF-κB). Conclusion: BMSCs-Exo play a protective role in spinal cord injury by inhibiting complement mRNA synthesis and release and by inhibiting SCI-activated NF-κB by binding to microglia.


Assuntos
Ativação do Complemento/fisiologia , Exossomos/transplante , Células-Tronco Mesenquimais/citologia , Traumatismos da Medula Espinal/terapia , Animais , Células da Medula Óssea/citologia , Sistema Livre de Células , Modelos Animais de Doenças , Exossomos/metabolismo , Masculino , Microglia/metabolismo , NF-kappa B/metabolismo , Proteômica , RNA Mensageiro/genética , Ratos , Ratos Wistar , Traumatismos da Medula Espinal/fisiopatologia
19.
Brain Behav Immun ; 82: 129-144, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31408672

RESUMO

BACKGROUND: An association between neuroinflammation, reduced adult neurogenesis, and cognitive impairment has been established in sleep deprivation (SD). Complement receptors are expressed on neuronal and glial cells, thus, regulate the neuroinflammation, neurogenesis and learning/memory. However, understanding of the effect of SD on the brain-immune system interaction associated with cognitive dysfunction and its mechanisms is obscure. We hypothesized that complement activation induced changes in inflammatory and neurogenesis related proteins might be involved in the cognitive impairment during SD. METHODOLOGY: Adult male Sprague Dawley rats were used. Rats were sleep deprived for 48 h using a novel automated SD apparatus. Dosage of BrdU (50 mg/kg/day, i.p. in 0.07 N NaOH), complement C3a receptor antagonist (C3aRA; SB290157; 1 mg/kg/day, i.p.) in 1.16% v/v PBS and complement C5a receptor antagonist (C5aRA; W-54011; 1 mg/kg/day, i.p.) in normal saline were used. Rats were subjected to spatial memory evaluation following SD. Hippocampal tissue was collected for biochemical, molecular, and immunohistochemical studies. T-test and ANOVA were used for the statistical analysis. RESULTS: An up-regulation in the levels of complement components (C3, C5, C3a, C5a) and receptors (C3aR and C5aR) in hippocampus, displayed the complement activation during SD. Selective antagonism of C3aR/C5aR improved the spatial memory performance of sleep-deprived rats. C3aR antagonist (C3aRA) or C5aR antagonist (C5aRA) treatment inhibited the gliosis, maintained inflammatory cytokines balance in hippocampus during SD. Complement C3aR/C5aR antagonism improved hippocampal adult neurogenesis via up-regulating the BDNF level following SD. Administration of C3aRA and C5aRA significantly maintained synaptic homeostasis in hippocampus after SD. Gene expression analysis showed down-regulation in the mRNA levels of signal transduction pathways (Notch and Wnt), differentiation and axogenous proteins, which were found to be improved after C3aRA/C5aRA treatment. These findings were validated at protein and cellular level. Changes in the corticosterone level and ATP-adenosine-NO pathway were established as the key mechanisms underlying complement activation mediated consequences of SD. CONCLUSION: Our study suggests complement (C3a-C3aR and C5a-C5aR) activation as the novel mechanism underlying spatial memory impairment via promoting neuroinflammation and adult neurogenesis decline in hippocampus during SD, thereby, complement (C3aR/C5aR) antagonist may serve as the novel therapeutics to improve the SD mediated consequences.


Assuntos
Ativação do Complemento/imunologia , Neuroimunomodulação/fisiologia , Privação do Sono/metabolismo , Animais , Arginina/análogos & derivados , Arginina/farmacologia , Compostos Benzidrílicos/farmacologia , Disfunção Cognitiva/imunologia , Disfunção Cognitiva/metabolismo , Ativação do Complemento/fisiologia , Complemento C3a/metabolismo , Hipocampo/metabolismo , Masculino , Neurogênese/imunologia , Neurogênese/fisiologia , Neuroimunomodulação/imunologia , Neurônios/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores de Complemento/metabolismo , Transdução de Sinais/fisiologia , Privação do Sono/imunologia , Memória Espacial/fisiologia , Lobo Temporal/metabolismo
20.
J Immunol ; 203(6): 1571-1578, 2019 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-31413105

RESUMO

Heme is a critical danger molecule liberated from hemeproteins in various conditions, including from hemoglobin in hemolytic diseases. Heme may cause thromboinflammatory damage by activating inflammatory and hemostatic pathways, such as complement, the TLRs, coagulation, and platelets. In this study, we explored the effect of single and dual inhibition of complement component C5 and TLR coreceptor CD14 on heme-induced thromboinflammation in an ex vivo human whole blood model. Heme induced a dose-dependent activation of complement via the alternative pathway. Single inhibition of C5 by eculizumab attenuated the release of IL-6, IL-8, TNF, MCP-1, MIP-1α, IFN-γ, LTB-4, MMP-8 and -9, and IL-1Ra with more than 60% (p < 0.05 for all) reduced the upregulation of CD11b on granulocytes and monocytes by 59 and 40%, respectively (p < 0.05), and attenuated monocytic tissue factor expression by 33% (p < 0.001). Blocking CD14 attenuated IL-6 and TNF by more than 50% (p < 0.05). In contrast to single inhibition, combined C5 and CD14 was required for a significantly attenuated prothrombin cleavage (72%, p < 0.05). Markers of thromboinflammation were also quantified in two patients admitted to the hospital with sickle cell disease (SCD) crisis. Both SCD patients had pronounced hemolysis and depleted plasma hemopexin and haptoglobin. Plasma heme and complement activation was markedly increased in one patient, a coinciding observation as demonstrated ex vivo. In conclusion, heme-induced thromboinflammation was largely attenuated by C5 inhibition alone, with a beneficial effect of adding a CD14 inhibitor to attenuate prothrombin activation. Targeting C5 has the potential to reduce thromboinflammation in SCD crisis patients.


Assuntos
Complemento C5/metabolismo , Heme/metabolismo , Inflamação/metabolismo , Receptores de Lipopolissacarídeos/metabolismo , Adulto , Anemia Falciforme/metabolismo , Animais , Coagulação Sanguínea/fisiologia , Ativação do Complemento/fisiologia , Citocinas/metabolismo , Granulócitos/metabolismo , Hemólise/fisiologia , Humanos , Masculino , Monócitos/metabolismo , Suínos , Tromboplastina/metabolismo
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