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1.
Commun Biol ; 6(1): 42, 2023 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-36639734

RESUMO

The Membrane Attack Complex (MAC) is responsible for forming large ß-barrel channels in the membranes of pathogens, such as gram-negative bacteria. Off-target MAC assembly on endogenous tissue is associated with inflammatory diseases and cancer. Accordingly, a human C5b-9 specific antibody, aE11, has been developed that detects a neoepitope exposed in C9 when it is incorporated into the C5b-9 complex, but not present in the plasma native C9. For nearly four decades aE11 has been routinely used to study complement, MAC-related inflammation, and pathophysiology. However, the identity of C9 neoepitope remains unknown. Here, we determined the cryo-EM structure of aE11 in complex with polyC9 at 3.2 Å resolution. The aE11 binding site is formed by two separate surfaces of the oligomeric C9 periphery and is therefore a discontinuous quaternary epitope. These surfaces are contributed by portions of the adjacent TSP1, LDLRA, and MACPF domains of two neighbouring C9 protomers. By substituting key antibody interacting residues to the murine orthologue, we validated the unusual binding modality of aE11. Furthermore, aE11 can recognise a partial epitope in purified monomeric C9 in vitro, albeit weakly. Taken together, our results reveal the structural basis for MAC recognition by aE11.


Assuntos
Complemento C9 , Complexo de Ataque à Membrana do Sistema Complemento , Humanos , Animais , Camundongos , Complexo de Ataque à Membrana do Sistema Complemento/metabolismo , Complemento C5b , Complemento C9/química , Complemento C9/metabolismo , Proteínas do Sistema Complemento/metabolismo , Epitopos
2.
J Hypertens ; 41(2): 223-232, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36583350

RESUMO

OBJECTIVE: Pregnant women with type-1 diabetes have an increased risk of preeclampsia with kidney injury and cardiovascular complications. Urine excretion of plasmin and soluble membrane attack complex (sC5b-9) is elevated in severe preeclampsia. We hypothesized a coupling between these events and that active plasmin promotes intratubular complement activation and membrane deposition. METHODS: Stored urine and plasma samples from pregnant women with type-1 diabetes (n = 88) collected at gestational weeks 12, 20, 28, 32, 36 and 38 were used. In the cohort, 14 women developed preeclampsia and were compared with 16 nonpreeclampsia controls. RESULTS: Urine C3dg and sC5b-9-associated C9 neoantigen/creatinine ratios increased and were significantly higher in women who developed preeclampsia. Plasma concentrations did not change with gestation. Urine plasmin(ogen) correlated to urine C3dg (r = 0.51, P < 0.001) and C9 neoantigen (r = 0.68, P < 0.001); urine albumin correlated to C3dg (r = 0.44, P < 0.001) and C9 (r = 0.59, P < 0.001). Membrane-associated C3dg and C9 neoantigen was detected in urinary extracellular vesicles from patients but not controls at 36 weeks. Receiver operating characteristic curves showed that C3dg and C9 neoantigen were inferior to albumin as predictive biomarkers for preeclampsia. CONCLUSION: In preeclampsia, urinary excretion of activated complement relates significantly to albuminuria and to plasmin(ogen) but not to activation in plasma. Intratubular complement activation in preeclampsia is a postfiltration event tightly related to proteinuria/plasminogenuria and a possible mechanistic link to cellular damage and kidney injury.


Assuntos
Diabetes Mellitus , Pré-Eclâmpsia , Feminino , Humanos , Gravidez , Gestantes , Fibrinolisina , Complexo de Ataque à Membrana do Sistema Complemento/urina , Proteinúria , Creatinina/urina , Albuminas
3.
Front Immunol ; 13: 1008294, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36451836

RESUMO

Atypical hemolytic-uremic syndrome (aHUS) is a severe thrombotic microangiopathy in which kidney involvement is common. aHUS can be due to either genetic or acquired abnormalities, with most abnormalities affecting the alternative complement pathway. Several genetic factors/alterations can drive the clinical presentation, therapeutic response, and risk of recurrence, especially recurrence following kidney transplantation. We report here the case of a 22-year-old man who developed a severe form of aHUS. Renal biopsy revealed thrombotic microangiopathy and features of chronic renal damage. Despite two eculizumab infusions, the patient remained dialysis dependent. Two novel rare variants, c.109G>A (p.E37K) and c.159 C>A (p.Y53*), were identified in the factor H-related 2 (FHR2) gene, and western blot analysis revealed a significant reduction in the level of FHR2 protein in the patient's serum. Although FHR2 involvement in complement 3 glomerulopathy has been reported previously, a role for FRH2 as a complement modulator has not yet been definitively shown. In addition, no cases of aHUS in individuals with FHR2 variants have been reported. Given the role of FHRs in the complement system and the fact that this patient was a candidate for a kidney transplant, we studied the relevance of low FHR2 plasma levels through a set of functional in vitro assays. The aim of our work was to determine if low FHR2 plasma levels could influence complement control at the endothelial surface with a view to identifying a therapeutic approach tailored to this specific patient. Interestingly, we observed that low FHR2 levels in the patient's serum could induce complement activation, as well as C5b-9 deposition on human endothelial cells, and affected cell morphology. As C5b-9 deposition is a prerequisite for endothelial cell damage, these results suggest that extremely low FHR2 plasma levels increase the risk of aHUS. Given their ability to reduce C5b-9 deposition, recombinant FHR2 and eculizumab were tested in vitro and found to inhibit hemolysis and endothelial cell surface damage. Both molecules showed effective and comparable profiles. Based on these results, the patient underwent a kidney transplant, and received eculizumab as induction and maintenance therapy. Five years after transplantation, the patient remains in good general health, with stable graft function and no evidence of disease recurrence. To our knowledge, this is first reported case of an aHUS patient carrying FHR2 mutations and provides an example of a translational therapeutic approach in kidney transplantation.


Assuntos
Síndrome Hemolítico-Urêmica Atípica , Transplante de Rim , Microangiopatias Trombóticas , Masculino , Humanos , Adulto Jovem , Adulto , Síndrome Hemolítico-Urêmica Atípica/genética , Transplante de Rim/efeitos adversos , Complexo de Ataque à Membrana do Sistema Complemento , Células Endoteliais , Ciência Translacional Biomédica
4.
Front Immunol ; 13: 1081942, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36582241

RESUMO

Objective: The pathogenesis of thrombotic microangiopathy (TMA) in lupus nephritis (LN) remains complicated. This study aimed to detect the deposition of complement lectin pathway (LP) and alternative pathway (AP) components in renal tissues, then evaluate the clinicopathological characteristics and risk factors for renal survival between patients with or without TMA in LN cohorts. Methods: We included 79 patients with biopsy-proven LN-associated TMA and matched the same number of LN patients without TMA as the control group. The deposition of mannose binding lectin (MBL), MBL-associated serine proteases 1/3 (MASP1/3), complement factor B (CFB), complement factor D (CFD), C4d, and von Willebrand factor (VWF) in renal tissue was assessed by immunohistochemistry and immunofluorescence. Besides, co-localization of C5b-9 and CD34 was detected by confocal microscopy. Results: In our retrospective cohort, the incidence of acute kidney injury (30% vs. 14%, p = 0.013), acute hemodialysis (35% vs. 5%, p < 0.001), and interstitial fibrosis (43% vs. 13%, p < 0.001) is higher in the TMA, compared with the control group. Despite aggressive steroids pulse, plasma exchange, and immunosuppressive therapy among TMA group, they still had significantly inferior 3-year renal survival rates (68% vs. 89%, p = 0.002) than those in the non-TMA group. COX regression analysis identified that TMA (HR 4.807, 95% CI [2.052, 11.263], p < 0.001) is a risk factor in LN. MBL, MASP1/3, CFB, CFD, C4d, and VWF deposited along the glomerulus among LN, while TMA had stronger staining intensity and deposition. The co-localized expression of CD34 and C5b-9 in the endothelial cells was also observed in the renal tissues. Conclusions: TMA is an independent risk factor for renal survival in LN patients. Moreover, LP and AP activation are involved in the pathogenesis of LN-associated TMA.


Assuntos
Nefrite Lúpica , Microangiopatias Trombóticas , Humanos , Nefrite Lúpica/patologia , Lectinas , Complexo de Ataque à Membrana do Sistema Complemento/análise , Estudos Retrospectivos , Células Endoteliais/metabolismo , Fator de von Willebrand , Microangiopatias Trombóticas/patologia , Fator B do Complemento , Prognóstico
5.
J Immunol Res ; 2022: 7263740, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36573216

RESUMO

Background: The ability of vaccine-induced antibodies to bind C1q could affect pathogen neutralization. In this study, we investigated C1q binding and subsequent complement activation by anti-spike (S) protein receptor-binding domain (RBD) specific antibodies produced following vaccination with either the mRNA vaccine BNT162b2 or the inactivated vaccine BBIBP-CorV. Methods: Serum samples were collected in the period of July 2021-March 2022. Participants' demographic data, type of vaccine, date of vaccination, as well as adverse effects of the vaccine were recorded. The serum samples were incubated with S protein RBD-coated plates. Levels of human IgG, IgA, IgM, C1q, and mannose-binding lectin (MBL) that were bound to the plate, as well as formed C3d, and C5b-9 were compared between different groups of participants. Results: A total of 151 samples were collected from vaccinated (n = 116) and nonvaccinated (n = 35) participants. Participants who received either one or two doses of BNT162b2 formed higher levels of anti-RBD IgG and IgA than participants who received BBIBP-CorV. The anti-RBD IgG formed following either vaccine bound C1q, but significantly more C1q binding was observed in participants who received BNT162b2. Subsequently, C5b-9 formation was significantly higher in participants who received BNT162b2, while no significant difference in C5b-9 formation was found between the nonvaccinated and BBIBP-CorV groups. The formation of C5b-9 was strongly correlated to C1q binding and not to MBL binding, additionally, the ratio of formed C5b-9/bound C1q was significantly higher in the BNT162b2 group. Conclusion: Anti-RBD IgG formed following vaccination can bind C1q with subsequent complement activation, and the degree of terminal complement pathway activation differed between vaccines, which could play a role in the protection offered by COVID-19 vaccines. Further investigation into the correlation between vaccine protection and vaccine-induced antibodies' ability to activate complement is required.


Assuntos
Vacinas contra COVID-19 , COVID-19 , Humanos , Complexo de Ataque à Membrana do Sistema Complemento , Vacina BNT162 , Complemento C1q , COVID-19/prevenção & controle , Proteínas do Sistema Complemento , Vacinação , Anticorpos Antivirais , Imunoglobulina A
6.
Invest Ophthalmol Vis Sci ; 63(12): 30, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36445700

RESUMO

Purpose: Factor H (FH, encoded by CFH) prevents activation of the complement system's alternative pathway (AP) on host tissues. FH impedes C3 convertase (C3bBb) formation, accelerates C3bBb decay, and is a cofactor for factor I (FI)-catalyzed C3b cleavage. Numerous CFH variants are associated with age-related macular degeneration (AMD), but their functional consequences frequently remain undetermined. Here, we conduct functional comparisons between a control version of FH (not AMD linked) and 21 AMD-linked FH variants. Methods: Recombinantly produced, untagged, full-length FH versions were assayed for binding to C3b and decay acceleration of C3bBb using surface-plasmon resonance, FI-cofactor activity using a fluorescent probe of C3b integrity, suppression of C5b-9 assembly on an AP-activating surface, and inhibition of human AP-mediated lysis of sheep erythrocytes. Results: All versions were successfully purified despite below-average yields for Arg2Thr, Arg53Cys, Arg175Pro, Arg175Gln, Ile221Val, Tyr402His, Pro503Ala, Arg567Gly, Gly1194Asp, and Arg1210Cys. Compared to control FH, Arg2Thr, Leu3Val, Ser58Ala, Asp90Gly, Asp130Asn, Gln400Lys, Tyr402His, Gly650Val, Ser890Ile, and Thr965Met showed minimal functional differences. Arg1210C, Arg53His, Arg175Gln, Gly1194Asp, Pro503Ala, Arg53Cys, Arg576Gly, and Arg175Pro (in order of decreasing efficacy) underperformed, while Ile221Val, Arg303Gln, and Arg303Trp were "marginal." We newly identified variants toward the center of the molecule, Pro503Ala and Arg567Gly, as potentially pathogenic. Conclusions: Our approach could be extended to other variants of uncertain significance and to assays for noncanonical FH activities, aiming to facilitate selection of cohorts most likely to benefit from therapeutic FH. This is timely as recombinant therapeutic FH is in development for intravitreal treatment of AMD in patients with reduced FH functionality.


Assuntos
Fator H do Complemento , Degeneração Macular , Animais , Humanos , Aceleração , Fator H do Complemento/genética , Complexo de Ataque à Membrana do Sistema Complemento , Proteínas do Sistema Complemento , Degeneração Macular/genética , Ovinos
7.
J Biomed Sci ; 29(1): 97, 2022 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-36376872

RESUMO

BACKGROUND: The complement system functions primarily as a first-line host defense against invading microbes, including viruses. However, the interaction of Hepatitis B virus (HBV) with the complement-components during chronic HBV infection remains largely unknown. We investigated the mechanism by which HBV inhibits the formation of cytolytic complement membrane-attack complex (MAC) and studied its impact on MAC-mediated microbicidal activity and disease pathogenesis. METHODS: Blood/liver tissues were collected from chronically HBV-infected patients and controls. HepG2hNTCP cells were infected with HBV particles and Huh7 cells were transfected with full-length linear HBV-monomer or plasmids containing different HBV-ORFs and expression of complement components or other host genes were evaluated. Additionally, ELISA, Real-time PCR, Western blot, bioinformatics analysis, gene overexpression/knock-down, mutagenesis, chromatin immunoprecipitation, epigenetic studies, immunofluorescence, and quantification of serum HBV-DNA, bacterial-DNA and endotoxin were performed. RESULTS: Among the MAC components (C5b-C9), significant reduction was noted in the expression of C9, the major constituent of MAC, in HBV-infected HepG2hNTCP cells and in Huh7 cells transfected with full-length HBV as well as HBX. C9 level was also marked low in sera/liver of chronic hepatitis B (CHB) and Immune-tolerant (IT) patients than inactive carriers and healthy controls. HBX strongly repressed C9-promoter activity in Huh7 cells but CpG-island was not detected in C9-promoter. We identified USF-1 as the key transcription factor that drives C9 expression and demonstrated that HBX-induced hypermethylation of USF-1-promoter is the leading cause of USF-1 downregulation that in turn diminished C9 transcription. Reduced MAC formation and impaired lysis of HBV-transfected Huh7 and bacterial cells were observed following incubation of these cells with C9-deficient CHB sera but was reversed upon C9 supplementation. Significant inverse correlation was noted between C9 concentration and HBV-DNA, bacterial-DNA and endotoxin content in HBV-infected patients. One-year Tenofovir therapy resulted in improvement in C9 level and decline in viral/bacterial/endotoxin load in CHB patients. CONCLUSION: Collectively, HBX suppressed C9 transcription by restricting the availability of USF-1 through hypermethylation of USF-1-promoter and consequently hinder the formation and lytic functions of MAC. Early therapy is needed for both CHB and IT to normalize the aberrant complement profile and contain viral and bacterial infection and limit disease progression.


Assuntos
Vírus da Hepatite B , Hepatite B Crônica , Humanos , Complemento C9/metabolismo , Complexo de Ataque à Membrana do Sistema Complemento/metabolismo , DNA Bacteriano/metabolismo , Endotoxinas/metabolismo , Células Hep G2 , Vírus da Hepatite B/genética , Hepatite B Crônica/patologia , Transativadores/genética , Proteínas Virais Reguladoras e Acessórias
8.
Cells ; 11(21)2022 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-36359858

RESUMO

Recessive Stargardt disease (STGD1) is an inherited retinopathy caused by mutations in the ABCA4 gene. The ABCA4 protein is a phospholipid-retinoid flippase in the outer segments of photoreceptors and the internal membranes of retinal pigment epithelial (RPE) cells. Here, we show that RPE cells derived via induced pluripotent stem-cell from a molecularly and clinically diagnosed STGD1 patient exhibited reduced ABCA4 protein and diminished activity compared to a normal subject. Consequently, STGD1 RPE cells accumulated intracellular autofluorescence-lipofuscin and displayed increased complement C3 activity. The level of C3 inversely correlated with the level of CD46, an early negative regulator of the complement cascade. Persistent complement dysregulation led to deposition of the membrane attack complex on the surface of RPE cells, decrease in transepithelial resistance, and subsequent cell death. These findings are strong evidence of complement-mediated RPE cell damage in STGD1, in the absence of photoreceptors, caused by reduced CD46 regulatory protein.


Assuntos
Complexo de Ataque à Membrana do Sistema Complemento , Epitélio Pigmentado da Retina , Humanos , Doença de Stargardt , Complexo de Ataque à Membrana do Sistema Complemento/metabolismo , Epitélio Pigmentado da Retina/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Proteínas do Sistema Complemento/metabolismo , Morte Celular
9.
Front Immunol ; 13: 1007102, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36330514

RESUMO

Background: The complement system is an essential component of our innate defense and plays a vital role in the pathogenesis of many diseases. Assessment of complement activation is critical in monitoring both disease progression and response to therapy. Complement analysis requires accurate and standardized sampling and assay procedures, which has proven to be challenging. Objective: We performed a systematic analysis of the current methods used to assess complement components and reviewed whether the identified studies performed their complement measurements according to the recommended practice regarding pre-analytical sample handling and assay technique. Results are supplemented with own data regarding the assessment of key complement biomarkers to illustrate the importance of accurate sampling and measuring of complement components. Methods: A literature search using the Pubmed/MEDLINE database was performed focusing on studies measuring the key complement components C3, C5 and/or their split products and/or the soluble variant of the terminal C5b-9 complement complex (sTCC) in human blood samples that were published between February 2017 and February 2022. The identified studies were reviewed whether they had used the correct sample type and techniques for their analyses. Results: A total of 92 out of 376 studies were selected for full-text analysis. Forty-five studies (49%) were identified as using the correct sample type and techniques for their complement analyses, while 25 studies (27%) did not use the correct sample type or technique. For 22 studies (24%), it was not specified which sample type was used. Conclusion: A substantial part of the reviewed studies did not use the appropriate sample type for assessing complement activation or did not mention which sample type was used. This deviation from the standardized procedure can lead to misinterpretation of complement biomarker levels and hampers proper comparison of complement measurements between studies. Therefore, this study underlines the necessity of general guidelines for accurate and standardized complement analysis.


Assuntos
Ativação do Complemento , Complemento C5 , Humanos , Complemento C3 , Complexo de Ataque à Membrana do Sistema Complemento , Biomarcadores
10.
Int J Mol Sci ; 23(21)2022 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-36362350

RESUMO

Preclinical and clinical studies have shown that traumatic hemorrhage (TH) induces early complement cascade activation, leading to inflammation-associated multiple-organ dysfunction syndrome (MODS). Several previous studies have demonstrated the beneficial effects of complement inhibition in anesthetized (unconscious) animal models of hemorrhage. Anesthetic agents profoundly affect the immune response, microcirculation response, and coagulation patterns and thereby may confound the TH research data acquired. However, no studies have addressed the effect of complement inhibition on inflammation-driven MODS in a conscious model of hemorrhage. This study investigated whether early administration of decay-accelerating factor (CD55/DAF, a complement C3/C5 inhibitor) alleviates hemorrhage-induced organ damage and how DAF modulates hemorrhage-induced organ damage. DAF was administered to unanesthetized male Sprague Dawley rats subjected to pressure-controlled hemorrhage followed by a prolonged (4 h) hypotensive resuscitation with or without lactated Ringer's (LR). We assessed DAF effects on organ protection, tissue levels of complement synthesis and activation, T lymphocyte infiltration, fluid resuscitation requirements, and metabolic acidosis. Hemorrhage with (HR) or without (H) LR resuscitation resulted in significantly increased C3, C5a, and C5b-9 deposition in the lung and intestinal tissues. HR rats had significantly higher tissue levels of complement activation/deposition (particularly C5a and C5b-9 in the lung tissues), a higher but not significant amount of C3 and C5b-9 pulmonary microvascular deposition, and relatively severe injury in the lung and intestinal tissues compared to H rats. DAF treatment significantly reduced tissue C5b-9 formation and C3 deposition in the H or HR rats and decreased tissue levels of C5a and C3 mRNA in the HR rats. This treatment prevented the injury of these organs, improved metabolic acidosis, reduced fluid resuscitation requirements, and decreased T-cell infiltration in lung tissues. These findings suggest that DAF has the potential as an organ-protective adjuvant treatment for TH during prolonged damage control resuscitation.


Assuntos
Acidose , Antígenos CD55 , Ratos , Masculino , Animais , Ratos Sprague-Dawley , Complexo de Ataque à Membrana do Sistema Complemento , Insuficiência de Múltiplos Órgãos/etiologia , Insuficiência de Múltiplos Órgãos/prevenção & controle , Hemorragia , Proteínas do Sistema Complemento , Inativadores do Complemento , Inflamação , Fenótipo
11.
Front Immunol ; 13: 918551, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36248901

RESUMO

The complement system is an ancient and critical part of innate immunity. Recent studies have highlighted novel roles of complement beyond lysis of invading pathogens with implications in regulating the innate immune response, as well as contributing to metabolic reprogramming of T-cells, synoviocytes as well as cells in the CNS. These findings hint that complement can be an immunometabolic regulator, but whether this is also the case for the terminal step of the complement pathway, the membrane attack complex (MAC) is not clear. In this study we focused on determining whether MAC is an immunometabolic regulator of the innate immune response in human monocyte-derived macrophages. Here, we uncover previously uncharacterized metabolic changes and mitochondrial dysfunction occurring downstream of MAC deposition. These alterations in glycolytic flux and mitochondrial morphology and function mediate NLRP3 inflammasome activation, pro-inflammatory cytokine release and gasdermin D formation. Together, these data elucidate a novel signalling cascade, with metabolic alterations at its center, in MAC-stimulated human macrophages that drives an inflammatory consequence in an immunologically relevant cell type.


Assuntos
Inflamassomos , Proteína 3 que Contém Domínio de Pirina da Família NLR , Complexo de Ataque à Membrana do Sistema Complemento/metabolismo , Humanos , Inflamassomos/metabolismo , Interleucina-18/metabolismo , Interleucina-1beta/metabolismo , Macrófagos , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo
12.
Int Immunopharmacol ; 113(Pt A): 109303, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36252469

RESUMO

Plasma cell mastitis (PCM) and granulomatous mastitis (GM) are common inflammatory nonbacterial mastitis (NBM). However, the pathogenesis of NBM is still unclear. METHODS: In this study, we statistically analyzed the pathological features of PCM and GM using pathological HE staining and tissue transmission electron microscopy. The levels of MAC (C5b-9n), P-selectin, E-selectin, and ICAM-1 were detected through IHC, WB, ELISA, and qPCR. The expression level and location of MAC were observed by tissue immunological electron microscopy. In addition, exosomes were isolated from tissues, identified using transmission electron microscopy, and the densities were detected by Nano-FCM. Finally, the expression intensity of MAC in exosomes was detected by flow cytometry and immunoelectron microscopy. RESULTS: The damage and apoptosis of mammary duct epithelial cells are the common pathological features of PCM and GM. MAC is primarily located in the cell membrane of mammary ductal epithelial cells and is significantly expressed in PCM and GM. The density of exosomes in PCM and GM tissues was elevated, and MAC was highly expressed in exosomes. In addition, the expression of P-selectin, E-selectin, and ICAM-1 in PCM and GM was significantly higher than in the normal group. CONCLUSION: We found severe damage of the mammary duct epithelial cells in PCM and GM tissues, which was verified by relevant pathological methods. Earlier studies demonstrated that MAC is highly expressed in PCM and GM tissues and exosomes seem to play a very important role in the understanding of MAC. Furthermore, MAC is involved in inflammatory infiltration and lesion of mammary duct epithelial cells upregulated by P-selectin, E-selectin, and ICAM-1. These findings provide new insights into PCM and GM molecular mechanisms.


Assuntos
Complexo de Ataque à Membrana do Sistema Complemento , Mastite Granulomatosa , Feminino , Humanos , Selectina E/metabolismo , Células Epiteliais/metabolismo , Mastite Granulomatosa/metabolismo , Mastite Granulomatosa/patologia , Molécula 1 de Adesão Intercelular/metabolismo , Plasmócitos/metabolismo , Glândulas Mamárias Humanas , Complexo de Ataque à Membrana do Sistema Complemento/metabolismo
13.
Front Immunol ; 13: 1020889, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36211400

RESUMO

Endothelial cells (ECs) form a critical immune interface regulating both the activation and trafficking of alloreactive T cells. In the setting of solid organ transplantation, donor-derived ECs represent sites where alloreactive T cells encounter major and minor tissue-derived alloantigens. During this initial encounter, ECs may formatively modulate effector responses of these T cells through expression of inflammatory mediators. Direct allorecognition is a process whereby recipient T cells recognize alloantigen in the context of donor EC-derived HLA molecules. Direct alloresponses are strongly modulated by human ECs and are galvanized by EC-derived inflammatory mediators. Complement are immune proteins that mark damaged or foreign surfaces for immune cell activation. Following labeling by natural IgM during ischemia reperfusion injury (IRI) or IgG during antibody-mediated rejection (ABMR), the complement cascade is terminally activated in the vicinity of donor-derived ECs to locally generate the solid-phase inflammatory mediator, the membrane attack complex (MAC). Via upregulation of leukocyte adhesion molecules, costimulatory molecules, and cytokine trans-presentation, MAC strengthen EC:T cell direct alloresponses and qualitatively shape the alloimmune T cell response. These processes together promote T cell-mediated inflammation during solid organ transplant rejection. In this review we describe molecular pathways downstream of IgM- and IgG-mediated MAC assembly on ECs in the setting of IRI and ABMR of tissue allografts, respectively. We describe work demonstrating that MAC deposition on ECs generates 'signaling endosomes' that sequester and post-translationally enhance the stability of inflammatory signaling molecules to promote EC activation, a process potentiating EC-mediated direct allorecognition. Additionally, with consideration to first-in-human xenotransplantation procedures, we describe clinical therapeutics based on inhibition of the complement pathway. The complement cascade critically mediates EC activation and improved understanding of relevant effector pathways will uncover druggable targets to obviate dysregulated alloimmune T cell infiltration into tissue allografts.


Assuntos
Complexo de Ataque à Membrana do Sistema Complemento , Rejeição de Enxerto , Moléculas de Adesão Celular , Citocinas , Células Endoteliais , Humanos , Imunoglobulina G , Imunoglobulina M , Mediadores da Inflamação , Isoantígenos
14.
Front Immunol ; 13: 953674, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36211440

RESUMO

Hidradenitis suppurativa (HS) is a chronic auto-inflammatory skin disease with a complex and multifactorial pathogenesis involving both the innate and adaptive immune system. Despite limited evidence for local complement activation, conflicting results have been published on the role of systemic complement activation in HS. It was hypothesized that complement was consumed in highly inflamed HS skin, trapping complement from the circulation. Therefore, the aim of this study was to evaluate this local complement deposition in HS skin lesions using routine and commonly used complement antibodies.Direct immunofluorescence for C1q, C3c, C4d, C5b-9, and properdin was performed on frozen tissue sections of 19 HS patients and 6 controls. C5a receptor 1 (C5aR1) was visualized using immunohistochemistry. Overall, we found no significant local complement deposition in HS patients versus controls regarding C1q, C3c, C4d, C5b-9, or properdin on either vessels or immune cells. C5aR1 expression was exclusively found on immune cells, predominantly neutrophilic granulocytes, but not significantly different relatively to the total infiltrate in HS lesions compared with controls. In conclusion, despite not being able to confirm local complement depositions of C1q, C3c, C4d, or properdin using highly sensitive and widely accepted techniques, the increased presence of C5aR1 positive immune cells in HS suggests the importance of complement in the pathogenesis of HS and supports emerging therapies targeting this pathway.


Assuntos
Hidradenite Supurativa , Ativação do Complemento , Complemento C1q , Complexo de Ataque à Membrana do Sistema Complemento , Humanos , Inflamação , Properdina , Receptor da Anafilatoxina C5a
15.
Adv Exp Med Biol ; 1386: 325-345, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36258078

RESUMO

Bloodstream infections (BSI) with Pseudomonas aeruginosa account for 8.5% of all BSIs, their mortality rate, at about 40%, is the highest among causative agents. For this reason and due to its intrinsic and acquired resistance to antibiotics, P. aeruginosa represents a threat to public health systems. From the primary site of infection, often the urinary and respiratory tracts, P. aeruginosa uses its arsenal of virulence factors to cross both epithelial and endothelial barriers, ultimately reaching the bloodstream. In this chapter, we review the main steps involved in invasion and migration of P. aeruginosa into blood vessels, and the molecular mechanisms governing bacterial survival in blood. We also review the lifestyle of P. aeruginosa "on" and "in" host cells. In the context of genomic and phenotypic diversity of laboratory strains and clinical isolates, we underline the need for more standardized and robust methods applied to host-pathogen interaction studies, using several representative strains from distinct phylogenetic groups before drawing general conclusions. Finally, our literature survey reveals a need for further studies to complete our comprehension of the complex interplay between P. aeruginosa and the immune system in the blood, specifically in relation to the complement system cascade(s) and the Membrane Attack Complex (MAC), which play crucial roles in counteracting P. aeruginosa BSI.


Assuntos
Bacteriemia , Infecções por Pseudomonas , Humanos , Pseudomonas aeruginosa/genética , Infecções por Pseudomonas/microbiologia , Bacteriemia/microbiologia , Complexo de Ataque à Membrana do Sistema Complemento , Filogenia , Fatores de Virulência/genética , Antibacterianos/uso terapêutico
16.
J Immunol ; 209(9): 1760-1767, 2022 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-36104112

RESUMO

Bacterial and mitochondrial DNA, sharing an evolutionary origin, act as danger-associated molecular patterns in infectious and sterile inflammation. They both contain immunomodulatory CpG motifs. Interactions between CpG motifs and the complement system are sparsely described, and mechanisms of complement activation by CpG remain unclear. Lepirudin-anticoagulated human whole blood and plasma were incubated with increasing concentrations of three classes of synthetic CpGs: CpG-A, -B, and -C oligodeoxynucleotides and their GpC sequence controls. Complement activation products were analyzed by immunoassays. Cytokine levels were determined via 27-plex beads-based immunoassay, and CpG interactions with individual complement proteins were evaluated using magnetic beads coated with CpG-B. In whole blood and plasma, CpG-B and CpG-C (p < 0.05 for both), but not CpG-A (p > 0.8 for all), led to time- and dose-dependent increase of soluble C5b-9, the alternative complement convertase C3bBbP, and the C3 cleavage product C3bc. GpC-A, -B, and -C changed soluble fluid-phase C5b-9, C3bBbP, and C3bc to the same extent as CpG-A, -B, and -C, indicating a DNA backbone-dependent effect. Dose-dependent CpG-B binding was found to C1q (r = 0.83; p = 0.006) and factor H (r = 0.93; p < 0.001). The stimulatory complement effect was partly preserved in C2-deficient plasma and completely preserved in MASP-2-deficient serum. CpG-B increased levels of IL-1ß, IL-2, IL-6, IL-8, MCP-1, and TNF in whole blood, which were completely abolished by inhibition of C5 and C5aR1 (p < 0.05 for all). In conclusion, synthetic analogs of bacterial and mitochondrial DNA activate the complement system via the DNA backbone. We suggest that CpG-B interacts directly with classical and alternative pathway components, resulting in complement-C5aR1-dependent cytokine release.


Assuntos
Citocinas , Oligodesoxirribonucleotídeos , Humanos , Ativação do Complemento , Complemento C1q , Fator H do Complemento , Complexo de Ataque à Membrana do Sistema Complemento/farmacologia , Proteínas do Sistema Complemento/metabolismo , Citocinas/metabolismo , DNA Mitocondrial , Interleucina-2/farmacologia , Interleucina-6/farmacologia , Interleucina-8 , Serina Proteases Associadas a Proteína de Ligação a Manose , Oligodesoxirribonucleotídeos/farmacologia , Ilhas de CpG
17.
Front Immunol ; 13: 952267, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36059503

RESUMO

Dysfunctional complement activation and Toll-like receptor signaling immediately after trauma are associated with development of trauma-induced coagulopathy and multiple organ dysfunction syndrome. We assessed the efficacy of the combined inhibition therapy of complement factor C5 and the TLR co-receptor CD14 on thrombo-inflammation and organ damage in an exploratory 72-h polytrauma porcine model, conducted under standard surgical and intensive care management procedures. Twelve male pigs were subjected to polytrauma, followed by resuscitation (ATLS® guidelines) and operation of the femur fracture (intramedullary nailing technique). The pigs were allocated to combined C5 and CD14 inhibition therapy group (n=4) and control group (n=8). The therapy group received intravenously C5 inhibitor (RA101295) and anti-CD14 antibody (rMil2) 30 min post-trauma. Controls received saline. Combined C5 and CD14 inhibition reduced the blood levels of the terminal complement complex (TCC) by 70% (p=0.004), CRP by 28% (p=0.004), and IL-6 by 52% (p=0.048). The inhibition therapy prevented the platelet consumption by 18% and TAT formation by 77% (p=0.008). Moreover, the norepinephrine requirements in the treated group were reduced by 88%. The inhibition therapy limited the organ damage, thereby reducing the blood lipase values by 50% (p=0.028), LDH by 30% (p=0.004), AST by 33%, and NGAL by 30%. Immunofluorescent analysis of the lung tissue revealed C5b-9 deposition on blood vessels in five from the untreated, and in none of the treated animals. In kidney and liver, the C5b-9 deposition was similarly detected mainly the untreated as compared to the treated animals. Combined C5 and CD14 inhibition limited the inflammatory response, the organ damage, and reduced the catecholamine requirements after experimental polytrauma and might be a promising therapeutic approach.


Assuntos
Insuficiência de Múltiplos Órgãos , Traumatismo Múltiplo , Animais , Complemento C5 , Complexo de Ataque à Membrana do Sistema Complemento , Inflamação , Masculino , Insuficiência de Múltiplos Órgãos/etiologia , Insuficiência de Múltiplos Órgãos/prevenção & controle , Traumatismo Múltiplo/complicações , Suínos
18.
Annu Rev Vis Sci ; 8: 33-52, 2022 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-36108103

RESUMO

The choriocapillaris, a dense capillary network located at the posterior pole of the eye, is essential for supporting normal vision, supplying nutrients, and removing waste products from photoreceptor cells and the retinal pigment epithelium. The anatomical location, heterogeneity, and homeostatic interactions with surrounding cell types make the choroid complex to study both in vivo and in vitro. Recent advances in single-cell RNA sequencing, in vivo imaging, and in vitro cell modeling are vastly improving our knowledge of the choroid and its role in normal health and in age-related macular degeneration (AMD). Histologically, loss of endothelial cells (ECs) of the choriocapillaris occurs early in AMD concomitant with elevated formation of the membrane attack complex of complement. Advanced imaging has allowed us to visualize early choroidal blood flow changes in AMD in living patients, supporting histological findings of loss of choroidal ECs. Single-cell RNA sequencing is being used to characterize choroidal cell types transcriptionally and discover their altered patterns of gene expression in aging and disease. Advances in induced pluripotent stem cell protocols and 3D cultures will allow us to closely mimic the in vivo microenvironment of the choroid in vitro to better understand the mechanism leading to choriocapillaris loss in AMD.


Assuntos
Complexo de Ataque à Membrana do Sistema Complemento , Degeneração Macular , Corioide/irrigação sanguínea , Corioide/metabolismo , Corioide/patologia , Complexo de Ataque à Membrana do Sistema Complemento/metabolismo , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Humanos , Biologia Molecular
19.
Ann Diagn Pathol ; 61: 152028, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36055005

RESUMO

Idiopathic Systemic Capillary Leak Syndrome (ISCLS), also known as Clarkson's Syndrome, is due to primary fluid and protein leak across capillaries that leads to an accumulation of interstitial fluids and cardiovascular collapse from intravascular hypovolemia. Viral infections are a putative trigger of these episodes. ISCLS is typically associated with a monoclonal gammopathy. Here we present four patients with idiopathic systemic capillary leak syndrome. The cohort consists of three men and one woman who range in age from 55 to 72 years old. All of the patients had a monoclonal gammopathy. Two patients had viral triggers. Biopsies of normal skin were examined throughout all phases of the disease. During an acute attack, we identified perivascular mixed CD4+ and CD8+ T cell lymphocytic infiltrates in the superficial dermis. We observed significant microvascular deposits of C5b-9 and upregulation of type I interferon signaling in endothelium along with reduced serum levels of complement during very active disease. We also identified deposits of immunoglobulin along the dermal epidermal junction mirroring the monoclonal immunoglobulin isotype implicated in each patient. During a post treatment recovery or mild disease phase there was reduced inflammation and decreased amounts of C5b-9 and type I interferon expression. Sudden onset capillary leak syndrome reflects enhanced endothelial cell permeability as a unique form of endothelial injury mediated by the combined effects of complement pathway activation and upregulation of type I interferon signaling on endothelium.


Assuntos
Síndrome de Vazamento Capilar , Interferon Tipo I , Paraproteinemias , Masculino , Feminino , Humanos , Pessoa de Meia-Idade , Idoso , Síndrome de Vazamento Capilar/diagnóstico , Síndrome de Vazamento Capilar/terapia , Complexo de Ataque à Membrana do Sistema Complemento , Biópsia
20.
Mol Immunol ; 151: 11-18, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36063582

RESUMO

Myasthenia gravis is a neuromuscular disease associated with antibodies against components of the neuromuscular junction, most often against the acetylcholine receptor (AChR). Although several mechanisms have been postulated to explain how these autoantibodies can lead to the pathology of the disease, convincing evidence suggests that destruction of the receptor-bearing postsynaptic membrane by complement membrane attack complex is of central importance. In this review, evidence for the importance of complement, and possible relationships between autoantigen, autoantibodies, complement activation, and the destruction of the membrane are discussed. More recent insights from the results of the complement-inhibiting therapeutic antibody eculizumab are also described, and the mechanisms connecting antibody binding to complement activation are considered from a structural viewpoint.


Assuntos
Complexo de Ataque à Membrana do Sistema Complemento , Miastenia Gravis , Autoanticorpos , Autoantígenos , Proteínas do Sistema Complemento , Humanos , Receptores Colinérgicos/metabolismo
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