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1.
J Exp Med ; 218(1)2021 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-33601413

RESUMO

Whereas T cells have been considered the major immune cells of the tumor microenvironment able to induce tumor regression and control cancer clinical outcome, a burst of recent publications pointed to the fact that B cells may also play a prominent role. Activated in germinal centers of tertiary lymphoid structures, B cells can directly present tumor-associated antigens to T cells or produce antibodies that increase antigen presentation to T cells or kill tumor cells, resulting in a beneficial clinical impact. Immune complexes can also increase inflammation, angiogenesis, and immunosuppression via macrophage and complement activation, resulting in deleterious impact.

2.
Blood ; 137(4): 431-432, 2021 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-33507301
3.
FEBS J ; 2020 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-33314778

RESUMO

Heme's interaction with Toll-like receptor 4 (TLR4) does not fully explain the proinflammatory properties of this hemoglobin-derived molecule during intravascular hemolysis. The receptor for advanced glycation end products (RAGE) shares many features with TLR4 such as common ligands and proinflammatory, prothrombotic, and pro-oxidative signaling pathways, prompting us to study its involvement as a heme sensor. Stable RAGE-heme complexes with micromolar affinity were detected as heme-mediated RAGE oligomerization. The heme-binding site was located in the V domain of RAGE. This interaction was Fe3+ -dependent and competitive with carboxymethyllysine, another RAGE ligand. We confirmed a strong basal gene expression of RAGE in mouse lungs. After intraperitoneal heme injection, pulmonary TNF-α, IL1ß, and tissue factor gene expression levels increased in WT mice but were significantly lower in their RAGE-/- littermates. This may be related to the lower activation of ERK1/2 and Akt observed in the lungs of heme-treated, RAGE-/- mice. Overall, heme binds to RAGE with micromolar affinity and could promote proinflammatory and prothrombotic signaling in vivo, suggesting that this interaction could be implicated in heme-overload conditions.

4.
Kidney Int ; 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-33137339

RESUMO

Rhabdomyolysis is a life-threatening condition caused by skeletal muscle damage with acute kidney injury being the main complication dramatically worsening the prognosis. Specific treatment for rhabdomyolysis-induced acute kidney injury is lacking and the mechanisms of the injury are unclear. To clarify this, we studied intra-kidney complement activation (C3d and C5b-9 deposits) in tubules and vessels of patients and mice with rhabdomyolysis-induced acute kidney injury. The lectin complement pathway was found to be activated in the kidney; likely via an abnormal pattern of Fut2-dependent cell fucosylation, recognized by the pattern recognition molecule collectin-11 and this proceeded in a C4-independent, bypass manner. Concomitantly, myoglobin-derived heme activated the alternative pathway. Complement deposition and acute kidney injury were attenuated by pre-treatment with the heme scavenger hemopexin. This indicates that complement was activated in a unique double-trigger mechanism, via the alternative and lectin pathways. The direct pathological role of complement was demonstrated by the preservation of kidney function in C3 knockout mice after the induction of rhabdomyolysis. The transcriptomic signature for rhabdomyolysis-induced acute kidney injury included a strong inflammatory and apoptotic component, which were C3/complement-dependent, as they were normalized in C3 knockout mice. The intra-kidney macrophage population expressed a complement-sensitive phenotype, overexpressing CD11b and C5aR1. Thus, our results demonstrate a direct pathological role of heme and complement in rhabdomyolysis-induced acute kidney injury. Hence, heme scavenging and complement inhibition represent promising therapeutic strategies.

5.
Antibodies (Basel) ; 9(4)2020 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-33113844

RESUMO

Constituent of innate immunity, complement is present in the tumor microenvironment. The functions of complement include clearance of pathogens and maintenance of homeostasis, and as such could contribute to an anti-tumoral role in the context of certain cancers. However, multiple lines of evidence show that in many cancers, complement has pro-tumoral actions. The large number of complement molecules (over 30), the diversity of their functions (related or not to the complement cascade), and the variety of cancer types make the complement-cancer topic a very complex matter that has just started to be unraveled. With this review we highlight the context-dependent role of complement in cancer. Recent studies revealed that depending of the cancer type, complement can be pro or anti-tumoral and, even for the same type of cancer, different models presented opposite effects. We aim to clarify the current knowledge of the role of complement in human cancers and the insights from mouse models. Using our classification of human cancers based on the prognostic impact of the overexpression of complement genes, we emphasize the strong potential for therapeutic targeting the complement system in selected subgroups of cancer patients.

6.
Genome Med ; 12(1): 86, 2020 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-33023656

RESUMO

Quantifying tissue-infiltrating immune and stromal cells provides clinically relevant information for various diseases. While numerous methods can quantify immune or stromal cells in human tissue samples from transcriptomic data, few are available for mouse studies. We introduce murine Microenvironment Cell Population counter (mMCP-counter), a method based on highly specific transcriptomic markers that accurately quantify 16 immune and stromal murine cell populations. We validated mMCP-counter with flow cytometry data and showed that mMCP-counter outperforms existing methods. We showed that mMCP-counter scores are predictive of response to immune checkpoint blockade in cancer mouse models and identify early immune impacts of Alzheimer's disease.

7.
Front Immunol ; 11: 1684, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32849588

RESUMO

Hemopexin is the main plasmatic scavenger of cell-free heme, released in the context of intravascular hemolysis or major cell injury. Heme is indispensable for the oxygen transport by hemoglobin but when released outside of the erythrocytes it becomes a danger-associated molecular pattern, contributing to tissue injury. One of the mechanisms of pro-inflammatory action of heme is to activate the innate immune complement cascade. Therefore, we hypothesized that injection of hemopexin will prevent hemolysis-induced complement activation. Human plasma-derived hemopexin is compatible with the heme clearance machinery of the mice. 100 or 500 mg/kg of hemopexin was injected in C57Bl/6 mice before treatment with phenylhydrazine (inducer of erythrocytes lysis) or with PBS as a control. Blood was taken at different timepoints to determine the pharmacokinetic of injected hemopexin in presence and absence of hemolysis. Complement activation was determined in plasma, by the C3 cleavage (western blot) and in the kidneys (immunofluorescence). Kidney injury was evaluated by urea and creatinine in plasma and renal NGAL and HO-1 gene expression were measured. The pharmacokinetic properties of hemopexin (mass spectrometry) in the hemolytic mice were affected by the target-mediated drug disposition phenomenon due to the high affinity of binding of hemopexin to heme. Hemolysis induced complement overactivation and signs of mild renal dysfunction at 6 h, which were prevented by hemopexin, except for the NGAL upregulation. The heme-degrading capacity of the kidney, measured by the HO-1 expression, was not affected by the treatment. These results encourage further studies of hemopexin as a therapeutic agent in models of diseases with heme overload.

8.
Front Immunol ; 11: 1772, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32849636

RESUMO

Intravascular hemolysis of any cause can induce acute kidney injury (AKI). Hemolysis-derived product heme activates the innate immune complement system and contributes to renal damage. Therefore, we explored the role of the master complement regulator Factor H (FH) in the kidney's resistance to hemolysis-mediated AKI. Acute systemic hemolysis was induced in mice lacking liver expression of FH (hepatoFH-/-, ~20% residual FH) and in WT controls, by phenylhydrazine injection. The impaired complement regulation in hepatoFH-/- mice resulted in a delayed but aggravated phenotype of hemolysis-related kidney injuries. Plasma urea as well as markers for tubular (NGAL, Kim-1) and vascular aggression peaked at day 1 in WT mice and normalized at day 2, while they increased more in hepatoFH-/- compared to the WT and still persisted at day 4. These were accompanied by exacerbated tubular dilatation and the appearance of tubular casts in the kidneys of hemolytic hepatoFH-/- mice. Complement activation in hemolytic mice occurred in the circulation and C3b/iC3b was deposited in glomeruli in both strains. Both genotypes presented with positive staining of FH in the glomeruli, but hepatoFH-/- mice had reduced staining in the tubular compartment. Despite the clear phenotype of tubular injury, no complement activation was detected in the tubulointerstitium of the phenylhydrazin-injected mice irrespective of the genotype. Nevertheless, phenylhydrazin triggered overexpression of C5aR1 in tubules, predominantly in hepatoFH-/- mice. Moreover, C5b-9 was deposited only in the glomeruli of the hemolytic hepatoFH-/- mice. Therefore, we hypothesize that C5a, generated in the glomeruli, could be filtered into the tubulointerstitium to activate C5aR1 expressed by tubular cells injured by hemolysis-derived products and will aggravate the tissue injury. Plasma-derived FH is critical for the tubular protection, since pre-treatment of the hemolytic hepatoFH-/- mice with purified FH attenuated the tubular injury. Worsening of acute tubular necrosis in the hepatoFH-/- mice was trigger-dependent, as it was also observed in LPS-induced septic AKI model but not in chemotherapy-induced AKI upon cisplatin injection. In conclusion, plasma FH plays a key role in protecting the kidneys, especially the tubules, against hemolysis-mediated injury. Thus, FH-based molecules might be explored as promising therapeutic agents in a context of AKI.

12.
Am J Hematol ; 95(5): 456-464, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31990387

RESUMO

The complement system is an innate immune defense cascade that can cause tissue damage when inappropriately activated. Evidence for complement over activation has been reported in small cohorts of patients with sickle cell disease (SCD). However, the mechanism governing complement activation in SCD has not been elucidated. Here, we observe that the plasma concentration of sC5b-9, a reliable marker for terminal complement activation, is increased at steady state in 61% of untreated SCD patients. We show that greater complement activation in vitro is promoted by SCD erythrocytes compared to normal ones, although no significant differences were observed in the regulatory proteins CD35, CD55, and CD59 in whole blood. Complement activation is positively correlated with the percentage of dense sickle cells (DRBCs). The expression levels of CD35, CD55, and CD59 are reduced in DRBCs, suggesting inefficient regulation when cell density increases. Moreover, the surface expression of the complement regulator CD46 on granulocytes was inversely correlated with the plasma sC5b-9. We also show increased complement deposition in cultured human endothelial cells incubated with SCD serum, which is diminished by the addition of the heme scavenger hemopexin. Treatment of SCD patients with hydroxyurea produces substantial reductions in complement activation, measured by sC5b-9 concentration and upregulation of CD46, as well as decreased complement activation on RBCs in vitro. In conclusion, complement over activation is a common pathogenic event in SCD that is associated with formation of DRBCs and hemolysis. And, it affects red cells, leukocytes and endothelial cells. This complement over activation is partly alleviated by hydroxyurea therapy.


Assuntos
Anemia Falciforme/terapia , Contagem de Células/métodos , Ativação do Complemento/genética , Hemólise/fisiologia , Hidroxiureia/uso terapêutico , Adolescente , Adulto , Feminino , Humanos , Hidroxiureia/farmacologia , Pessoa de Meia-Idade , Adulto Jovem
13.
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
14.
Nat Rev Cancer ; 19(12): 698-715, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31666715

RESUMO

The tumour microenvironment (TME) highly influences the growth and spread of tumours, thus impacting the patient's clinical outcome. In this context, the complement system plays a major and complex role. It may either act to kill antibody-coated tumour cells, support local chronic inflammation or hamper antitumour T cell responses favouring tumour progression. Recent studies demonstrate that these opposing effects are dependent upon the sites of complement activation, the composition of the TME and the tumour cell sensitivity to complement attack. In this Review, we present the evidence that has so far accrued showing a role for complement activation and its effects on cancer control and clinical outcome under different TME contexts. We also include a new analysis of the publicly available transcriptomic data to provide an overview of the prognostic value of complement gene expression in 30 cancer types. We argue that the interplay of complement components within each cancer type is unique, governed by the properties of the tumour cells and the TME. This concept is of critical importance for the design of efficient therapeutic strategies aimed at targeting complement components and their signalling.


Assuntos
Ativação do Complemento , Proteínas do Sistema Complemento/imunologia , Neoplasias/imunologia , Microambiente Tumoral/imunologia , Animais , Vacinas Anticâncer , Linhagem Celular Tumoral , Sistemas de Liberação de Medicamentos , Genoma Humano , Humanos , Camundongos , Prognóstico , Linfócitos T/imunologia , Transcriptoma
15.
Toxins (Basel) ; 11(11)2019 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-31766155

RESUMO

Vascular diseases are multifactorial, often requiring multiple challenges, or 'hits', for their initiation. Intra-vascular hemolysis illustrates well the multiple-hit theory where a first event lyses red blood cells, releasing hemolysis-derived products, in particular cell-free heme which is highly toxic for the endothelium. Physiologically, hemolysis derived-products are rapidly neutralized by numerous defense systems, including haptoglobin and hemopexin which scavenge hemoglobin and heme, respectively. Likewise, cellular defense mechanisms are involved, including heme-oxygenase 1 upregulation which metabolizes heme. However, in cases of intra-vascular hemolysis, those systems are overwhelmed. Heme exerts toxic effects by acting as a damage-associated molecular pattern and promoting, together with hemoglobin, nitric oxide scavenging and ROS production. In addition, it activates the complement and the coagulation systems. Together, these processes lead to endothelial cell injury which triggers pro-thrombotic and pro-inflammatory phenotypes. Moreover, among endothelial cells, glomerular ones display a particular susceptibility explained by a weaker capacity to counteract hemolysis injury. In this review, we illustrate the 'multiple-hit' theory through the example of intra-vascular hemolysis, with a particular focus on cell-free heme, and we advance hypotheses explaining the glomerular susceptibility observed in hemolytic diseases. Finally, we describe therapeutic options for reducing endothelial injury in hemolytic diseases.


Assuntos
Endotélio Vascular/efeitos dos fármacos , Hemólise , Animais , Endotélio Vascular/metabolismo , Eritrócitos/metabolismo , Heme/metabolismo , Hemoglobinas/metabolismo , Humanos
17.
Cancer Immunol Res ; 7(7): 1091-1105, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31164356

RESUMO

Clear-cell renal cell carcinoma (ccRCC) possesses an unmet medical need, particularly at the metastatic stage, when surgery is ineffective. Complement is a key factor in tissue inflammation, favoring cancer progression through the production of complement component 5a (C5a). However, the activation pathways that generate C5a in tumors remain obscure. By data mining, we identified ccRCC as a cancer type expressing concomitantly high expression of the components that are part of the classical complement pathway. To understand how the complement cascade is activated in ccRCC and impacts patients' clinical outcome, primary tumors from three patient cohorts (n = 106, 154, and 43), ccRCC cell lines, and tumor models in complement-deficient mice were used. High densities of cells producing classical complement pathway components C1q and C4 and the presence of C4 activation fragment deposits in primary tumors correlated with poor prognosis. The in situ orchestrated production of C1q by tumor-associated macrophages (TAM) and C1r, C1s, C4, and C3 by tumor cells associated with IgG deposits, led to C1 complex assembly, and complement activation. Accordingly, mice deficient in C1q, C4, or C3 displayed decreased tumor growth. However, the ccRCC tumors infiltrated with high densities of C1q-producing TAMs exhibited an immunosuppressed microenvironment, characterized by high expression of immune checkpoints (i.e., PD-1, Lag-3, PD-L1, and PD-L2). Our data have identified the classical complement pathway as a key inflammatory mechanism activated by the cooperation between tumor cells and TAMs, favoring cancer progression, and highlight potential therapeutic targets to restore an efficient immune reaction to cancer.


Assuntos
Carcinoma de Células Renais/patologia , Complemento C1q/imunologia , Complemento C3/imunologia , Complemento C4/imunologia , Neoplasias Renais/patologia , Macrófagos/imunologia , Microambiente Tumoral/imunologia , Animais , Apoptose , Carcinoma de Células Renais/imunologia , Carcinoma de Células Renais/metabolismo , Proliferação de Células , Ativação do Complemento , Complemento C1q/metabolismo , Complemento C3/metabolismo , Complemento C4/metabolismo , Feminino , Seguimentos , Humanos , Fatores Imunológicos/metabolismo , Neoplasias Renais/imunologia , Neoplasias Renais/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos , Estudos Retrospectivos , Taxa de Sobrevida , Células Tumorais Cultivadas
18.
Mol Immunol ; 111: 205-208, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31078967

RESUMO

Therapeutic intravenous immunoglobulin preparations (IVIg) are used for treatment of wide range of autoimmune and inflammatory diseases. Versatile mechanisms have been reported to contribute to the immunomodulatory effects of IVIg. Here we demonstrate that IVIg has a strong potential to inhibit pro-inflammatory effect of extracellular heme. Indeed, the presence of immunoglobulins reduced the potential of heme to activate the complement system on the surface of human endothelial cells. Since extracellular heme is considered as one of the principal pathogenic factors in hemolytic disorders, its therapeutic scavenging by IVIg may have significant clinical repercussions.


Assuntos
Anti-Inflamatórios/imunologia , Heme/imunologia , Imunoglobulinas Intravenosas/imunologia , Inflamação/imunologia , Doenças Autoimunes/imunologia , Linhagem Celular , Proteínas do Sistema Complemento/imunologia , Células Endoteliais/imunologia , Células Endoteliais da Veia Umbilical Humana , Humanos
19.
Proc Natl Acad Sci U S A ; 116(13): 6280-6285, 2019 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-30850533

RESUMO

Hemolytic diseases are frequently linked to multiorgan failure subsequent to vascular damage. Deciphering the mechanisms leading to organ injury upon hemolytic event could bring out therapeutic approaches. Complement system activation occurs in hemolytic disorders, such as sickle cell disease, but the pathological relevance and the acquisition of a complement-activating phenotype during hemolysis remain unclear. Here we found that intravascular hemolysis, induced by injection of phenylhydrazine, resulted in increased alanine aminotransferase plasma levels and NGAL expression. This liver damage was at least in part complement-dependent, since it was attenuated in complement C3-/- mice and by injection of C5-blocking antibody. We evidenced C3 activation fragments' deposits on liver endothelium in mice with intravascular hemolysis or injected with heme as well as on cultured human endothelial cells (EC) exposed to heme. This process was mediated by TLR4 signaling, as revealed by pharmacological blockade and TLR4 deficiency in mice. Mechanistically, TLR4-dependent surface expression of P-selectin triggered an unconventional mechanism of complement activation by noncovalent anchoring of C3 activation fragments, including the typical fluid-phase C3(H2O), measured by surface plasmon resonance and flow cytometry. P-selectin blockade by an antibody prevented complement deposits and attenuated the liver stress response, measured by NGAL expression, in the hemolytic mice. In conclusion, these results revealed the critical impact of the triad TLR4/P-selectin/complement in the liver damage and its relevance for hemolytic diseases. We anticipate that blockade of TLR4, P-selectin, or the complement system could prevent liver injury in hemolytic diseases like sickle cell disease.


Assuntos
Endotélio Vascular/metabolismo , Heme/metabolismo , Hemólise , Selectina-P/metabolismo , Receptor 4 Toll-Like/metabolismo , Alanina Transaminase/sangue , Anemia Falciforme , Animais , Ativação do Complemento , Complemento C3/metabolismo , Modelos Animais de Doenças , Inativação Gênica , Hemólise/efeitos dos fármacos , Humanos , Lipocalina-2/metabolismo , Fígado/lesões , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fenil-Hidrazinas/antagonistas & inibidores , Transdução de Sinais , Receptor 4 Toll-Like/efeitos dos fármacos , Receptor 4 Toll-Like/genética
20.
Front Immunol ; 10: 64, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30761135

RESUMO

The complement component C3 is at the heart of the complement cascade. It is a complex protein, which generates different functional activated fragments (C3a, C3b, iC3b, C3c, C3d). C3b is a constituent of the alternative pathway C3 convertase (C3bBb), binds multiple regulators, and receptors, affecting thus the functioning of the immune system. The activated forms of C3 are a target for autoantibodies. This review focuses on the discovery, disease relevance, and functional consequences of the anti-C3b autoantibodies. They were discovered about 70 years ago and named immunoconglutinins. They were found after infections and considered convalescent factors. At the end of the twentieth century IgG against C3b were found in systemic lupus erythematosus and recently in lupus nephritis, correlating with the disease severity and flare. Cases of C3 glomerulopathy and immune complex glomerulonephritis were also reported. These antibodies recognize epitopes, shared between C3(H2O)/C3b/iC3b/C3c and have overt functional activity. They correlate with low plasmatic C3 levels in patients. In vitro, they increase the activity of the alternative pathway C3 convertase, without being C3 nephritic factors. They perturb the binding of the negative regulators Complement Receptor 1 and Factor H. The clear functional consequences and association with disease severity warrant further studies to establish the link between the anti-C3b autoantibodies and tissue injury. Comparative studies with such antibodies, found in patients with infections, may help to uncover their origin and epitopes specificity. Patients with complement overactivation due to presence of anti-C3b antibodies may benefit from therapeutic targeting of C3.


Assuntos
Complemento C3b/imunologia , Imunoconglutininas/imunologia , Nefrite Lúpica/imunologia , Animais , Ativação do Complemento , Fator Nefrítico do Complemento 3/metabolismo , Convertases de Complemento C3-C5/metabolismo , Complemento C3b/metabolismo , Proteínas Inativadoras do Complemento C3b/metabolismo , Fator H do Complemento/metabolismo , Ensaio de Imunoadsorção Enzimática , Epitopos/imunologia , Epitopos/metabolismo , Humanos , Imunoconglutininas/metabolismo , Camundongos , Índice de Gravidade de Doença
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