Assuntos
Oxirredução , Fosfolipídeos , Fosfolipídeos/metabolismo , Fosfolipídeos/imunologia , Humanos , AnimaisRESUMO
Malaria and other apicomplexan-caused diseases affect millions of humans, agricultural animals, and pets. Cell traversal is a common feature used by multiple apicomplexan parasites to migrate through host cells and can be exploited to develop therapeutics against these deadly parasites. Here, we provide insights into the mechanism of the Cell-traversal protein for ookinetes and sporozoites (CelTOS), a conserved cell-traversal protein in apicomplexan parasites and malaria vaccine candidate. CelTOS has previously been shown to form pores in cell membranes to enable traversal of parasites through cells. We establish roles for the distinct protein regions of Plasmodium vivax CelTOS and examine the mechanism of pore formation. We further demonstrate that CelTOS dimer dissociation is required for pore formation, as disulfide bridging between monomers inhibits pore formation, and this inhibition is rescued by disulfide-bridge reduction. We also show that a helix-destabilizing amino acid, Pro127, allows CelTOS to undergo significant conformational changes to assemble into pores. The flexible C terminus of CelTOS is a negative regulator that limits pore formation. Finally, we highlight that lipid binding is a prerequisite for pore assembly as mutation of a phospholipids-binding site in CelTOS resulted in loss of lipid binding and abrogated pore formation. These findings identify critical regions in CelTOS and will aid in understanding the egress mechanism of malaria and other apicomplexan parasites as well as have implications for studying the function of other essential pore-forming proteins.
Assuntos
Vacinas Antimaláricas , Malária Vivax , Plasmodium vivax , Proteínas de Protozoários , Sítios de Ligação , Dissulfetos/química , Humanos , Vacinas Antimaláricas/química , Vacinas Antimaláricas/genética , Vacinas Antimaláricas/imunologia , Malária Vivax/prevenção & controle , Fosfolipídeos/imunologia , Plasmodium vivax/genética , Plasmodium vivax/imunologia , Prolina/química , Prolina/genética , Conformação Proteica em alfa-Hélice , Multimerização Proteica , Proteínas de Protozoários/química , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Esporozoítos/genética , Esporozoítos/imunologiaRESUMO
In response to infection or tissue damage, resident peritoneal macrophages (rpMACs) produce inflammatory lipid mediators from the polyunsaturated fatty acid (PUFA), arachidonic acid (AA). Long-chain acyl-CoA synthetase 4 (ACSL4) catalyzes the covalent addition of a CoA moiety to fatty acids, with a strong preference for AA and other PUFAs containing three or more double bonds. PUFA-CoA can be incorporated into phospholipids, which is the source of PUFA for lipid mediator synthesis. In this study, we demonstrated that deficiency of Acsl4 in mouse rpMACs resulted in a significant reduction of AA incorporated into all phospholipid classes and a reciprocal increase in incorporation of oleic acid and linoleic acid. After stimulation with opsonized zymosan (opZym), a diverse array of AA-derived lipid mediators, including leukotrienes, PGs, hydroxyeicosatetraenoic acids, and lipoxins, were produced and were significantly reduced in Acsl4-deficient rpMACs. The Acsl4-deficient rpMACs stimulated with opZym also demonstrated an acute reduction in mRNA expression of the inflammatory cytokines, Il6, Ccl2, Nos2, and Ccl5 When Acsl4-deficient rpMACs were incubated in vitro with the TLR4 agonist, LPS, the levels of leukotriene B4 and PGE2 were also significantly decreased. In LPS-induced peritonitis, mice with myeloid-specific Acsl4 deficiency had a significant reduction in leukotriene B4 and PGE2 levels in peritoneal exudates, which was coupled with reduced infiltration of neutrophils in the peritoneal cavity as compared with wild-type mice. Our data demonstrate that chronic deficiency of Acsl4 in rpMACs reduces the incorporation of AA into phospholipids, which reduces lipid mediator synthesis and inflammation.
Assuntos
Ácido Araquidônico/imunologia , Coenzima A Ligases/imunologia , Inflamação/imunologia , Fosfolipídeos/imunologia , Zimosan/biossíntese , Animais , Coenzima A Ligases/deficiência , Camundongos , Camundongos TransgênicosRESUMO
Whereas proteolytic cleavage is crucial for peptide presentation by classical major histocompatibility complex (MHC) proteins to T cells, glycolipids presented by CD1 molecules are typically presented in an unmodified form. However, the mycobacterial lipid antigen mannosyl-ß1-phosphomycoketide (MPM) may be processed through hydrolysis in antigen presenting cells, forming mannose and phosphomycoketide (PM). To further test the hypothesis that some lipid antigens are processed, and to generate antigens that lead to defined epitopes for future tuberculosis vaccines or diagnostic tests, we aimed to create hydrolysis-resistant MPM variants that retain their antigenicity. Here, we designed and tested three different, versatile synthetic strategies to chemically stabilize MPM analogs. Crystallographic studies of CD1c complexes with these three new MPM analogs showed anchoring of the lipid tail and phosphate group that is highly comparable to nature-identical MPM, with considerable conformational flexibility for the mannose head group. MPM-3, a difluoromethylene-modified version of MPM that is resistant to hydrolysis, showed altered recognition by cells, but not by CD1c proteins, supporting the cellular antigen processing hypothesis. Furthermore, the synthetic analogs elicited T cell responses that were cross-reactive with nature-identical MPM, fulfilling important requirements for future clinical use.
Assuntos
Antígenos de Bactérias/química , Antígenos CD1/química , Glicolipídeos/química , Glicoproteínas/química , Mycobacterium tuberculosis/química , Fosfolipídeos/química , Linfócitos T/química , Antígenos de Bactérias/imunologia , Antígenos CD1/imunologia , Linhagem Celular Transformada , Cristalografia por Raios X , Glicolipídeos/imunologia , Glicoproteínas/imunologia , Humanos , Mycobacterium tuberculosis/imunologia , Fosfolipídeos/imunologia , Linfócitos T/imunologiaRESUMO
We optimized lipidomics methods to broadly detect endogenous lipids bound to cellular CD1a proteins. Whereas membrane phospholipids dominate in cells, CD1a preferentially captured sphingolipids, especially a C42, doubly unsaturated sphingomyelin (42:2 SM). The natural 42:2 SM but not the more common 34:1 SM blocked CD1a tetramer binding to T cells in all human subjects tested. Thus, cellular CD1a selectively captures a particular endogenous lipid that broadly blocks its binding to TCRs. Crystal structures show that the short cellular SMs stabilized a triad of surface residues to remain flush with CD1a, but the longer lipids forced the phosphocholine group to ride above the display platform to hinder TCR approach. Whereas nearly all models emphasize antigen-mediated T cell activation, we propose that the CD1a system has intrinsic autoreactivity and is negatively regulated by natural endogenous inhibitors selectively bound in its cleft. Further, the detailed chemical structures of natural blockers could guide future design of therapeutic blockers of CD1a response.
Assuntos
Antígenos CD1/imunologia , Linfócitos T/imunologia , Apresentação de Antígeno/imunologia , Linhagem Celular , Membrana Celular/imunologia , Células HEK293 , Humanos , Células K562 , Ativação Linfocitária/imunologia , Fosfolipídeos/imunologia , Receptores de Antígenos de Linfócitos T/imunologiaAssuntos
Autoanticorpos/efeitos adversos , Autoanticorpos/imunologia , Doenças Autoimunes/etiologia , Doenças Autoimunes/imunologia , COVID-19/complicações , COVID-19/fisiopatologia , Modelos Imunológicos , SARS-CoV-2/patogenicidade , Envelhecimento/imunologia , Anexina A2/imunologia , Autoanticorpos/isolamento & purificação , Doenças Autoimunes/microbiologia , Doenças Autoimunes/virologia , Linfócitos B/imunologia , Linfócitos B/patologia , Coagulação Sanguínea/imunologia , Vasos Sanguíneos/imunologia , Vasos Sanguíneos/patologia , Encéfalo/imunologia , Encéfalo/patologia , COVID-19/etiologia , COVID-19/imunologia , COVID-19/patologia , COVID-19/virologia , Estado Terminal , Síndrome da Liberação de Citocina/complicações , Síndrome da Liberação de Citocina/imunologia , Síndrome da Liberação de Citocina/patologia , Síndrome da Liberação de Citocina/fisiopatologia , Feminino , Cadeias HLA-DRB1/imunologia , Helicobacter pylori/imunologia , Helicobacter pylori/patogenicidade , Herpesvirus Humano 4/imunologia , Herpesvirus Humano 4/patogenicidade , Humanos , Interferon Tipo I/antagonistas & inibidores , Interferon Tipo I/imunologia , Masculino , Miocárdio/imunologia , Miocárdio/patologia , Fosfolipídeos/imunologia , Grupos Raciais , SARS-CoV-2/imunologia , SARS-CoV-2/isolamento & purificação , Caracteres Sexuais , Streptococcus pyogenes/imunologia , Streptococcus pyogenes/patogenicidade , Fatores de Tempo , Síndrome de COVID-19 Pós-AgudaRESUMO
Systemic lupus erythematosus (SLE) is diagnosed and classified by criteria, or by experience, intuition and traditions, and not by scientifically well-defined etiology(ies) or pathogenicity(ies). One central criterion and diagnostic factor is founded on theoretical and analytical approaches based on our imperfect definition of the term "The anti-dsDNA antibody". "The anti-dsDNA antibody" holds an archaic position in SLE as a unique classification criterium and pathogenic factor. In a wider sense, antibodies to unique transcriptionally active or silent DNA structures and chromatin components may have individual and profound nephritogenic impact although not considered yet - not in theoretical nor in descriptive or experimental contexts. This hypothesis is contemplated here. In this analysis, our state-of-the-art conception of these antibodies is probed and found too deficient with respect to their origin, structural DNA specificities and clinical/pathogenic impact. Discoveries of DNA structures and functions started with Miescher's Nuclein (1871), via Chargaff, Franklin, Watson and Crick, and continues today. The discoveries have left us with a DNA helix that presents distinct structures expressing unique operations of DNA. All structures are proven immunogenic! Unique autoimmune antibodies are described against e.g. ssDNA, elongated B DNA, bent B DNA, Z DNA, cruciform DNA, or individual components of chromatin. In light of the massive scientific interest in anti-DNA antibodies over decades, it is an unexpected observation that the spectrum of DNA structures has been known for decades without being implemented in clinical immunology. This leads consequently to a critical analysis of historical and contemporary evidence-based data and of ignored and one-dimensional contexts and hypotheses: i.e. "one antibody - one disease". In this study radical viewpoints on the impact of DNA and chromatin immunity/autoimmunity are considered and discussed in context of the pathogenesis of lupus nephritis.
Assuntos
Anticorpos Antinucleares/imunologia , Lúpus Eritematoso Sistêmico/etiologia , Formação de Anticorpos/imunologia , Especificidade de Anticorpos/imunologia , Autoimunidade , Cromatina/química , Cromatina/imunologia , Reações Cruzadas/imunologia , DNA/química , DNA/imunologia , Suscetibilidade a Doenças/imunologia , Humanos , Lúpus Eritematoso Sistêmico/diagnóstico , Lúpus Eritematoso Sistêmico/terapia , Conformação de Ácido Nucleico , Peptídeos/imunologia , Fosfolipídeos/imunologia , ProteínasRESUMO
Non-bilayer phospholipids arrangements (NPAs) are transient molecular associations different from lipid bilayers. When they become stable, they can trigger a disease in mice resembling human lupus, which is mainly characterized by the production of anti-NPA IgG antibodies. NPAs are stabilized on liposomes or cell bilayers by the drugs procainamide or chlorpromazine, which produce drug-induced lupus in humans. Here, we evaluated the participation of the TH 2 response, through its hallmark cytokine IL-4, on the development of the lupus-like disease in mice. Wild-type or IL-4 knockout BALB/c mice received liposomes bearing drug-induced NPAs, the drugs alone, or an anti-NPA monoclonal antibody (H308) to induce the lupus-like disease (the last two procedures stabilize NPAs on mice cells). IL-4 KO mice showed minor disease manifestations, compared to wild-type mice, with decreased production of anti-NPA IgG antibodies, no anti-cardiolipin, anti-histones and anticoagulant antibodies, and no kidney or skin lesions. In these mice, H308 was the only inducer of anti-NPA IgG antibodies. These findings indicate that IL-4 has a central role in the development of the murine lupus-like disease induced by NPA stabilization.
Assuntos
Interleucina-4/genética , Interleucina-4/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Fosfolipídeos/imunologia , Células Th2/imunologia , Animais , Anticorpos Monoclonais/imunologia , Autoanticorpos/imunologia , Modelos Animais de Doenças , Feminino , Imunoglobulina G/imunologia , Bicamadas Lipídicas/metabolismo , Lúpus Eritematoso Sistêmico/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos KnockoutAssuntos
COVID-19/metabolismo , Doenças Cardiovasculares/metabolismo , Colesterol/metabolismo , Fosfolipídeos/metabolismo , Enzima de Conversão de Angiotensina 2/metabolismo , Biomarcadores/metabolismo , COVID-19/imunologia , COVID-19/patologia , Doenças Cardiovasculares/imunologia , Doenças Cardiovasculares/patologia , Humanos , Inflamação , Microdomínios da Membrana/metabolismo , Fosfolipídeos/imunologia , SARS-CoV-2Assuntos
Anticorpos Anticardiolipina/sangue , COVID-19/complicações , Pérnio/etiologia , Imunoglobulina A/sangue , Pandemias , SARS-CoV-2 , Adolescente , Adulto , Anticorpos Anticardiolipina/imunologia , Especificidade de Anticorpos , Autoantígenos/imunologia , COVID-19/imunologia , Micropartículas Derivadas de Células/imunologia , Pérnio/sangue , Pérnio/imunologia , Criança , Pré-Escolar , Complemento C3/deficiência , Convalescença , Humanos , Imunoglobulina A/imunologia , Lipídeos de Membrana/imunologia , Fosfolipídeos/imunologia , Estudos Retrospectivos , SARS-CoV-2/fisiologia , Fatores de Tempo , Adulto JovemRESUMO
The severe acute respiratory syndrome coronavirus 2 (SARSCoV2) is a novel ß coronavirus that is the etiological agent of the pandemic coronavirus disease 2019 (COVID19) that at the time of writing (June 16, 2020) has infected almost 6 million people with some 450,000 deaths. These numbers are still rising daily. Most (some 80%) cases of COVID19 infection are asymptomatic, a substantial number of cases (15%) require hospitalization and an additional fraction of patients (5%) need recovery in intensive care units. Mortality for COVID19 infection appears to occur globally between 0.1 and 0.5% of infected patients although the frequency of lethality is significantly augmented in the elderly and in patients with other comorbidities. The development of acute respiratory distress syndrome and episodes of thromboembolism that may lead to disseminated intravascular coagulation (DIC) represent the primary causes of lethality during COVID19 infection. Increasing evidence suggests that thrombotic diathesis is due to multiple derangements of the coagulation system including marked elevation of Ddimer that correlate negatively with survival. We propose here that the thromboembolic events and eventually the development of DIC provoked by SARSCoV2 infection may represent a secondary antiphospholipid antibody syndrome (APS). We will apply both Baconian inductivism and Cartesian deductivism to prove that secondary APS is likely responsible for coagulopathy during the course of COVID19 infection. Diagnostic and therapeutic implications of this are also discussed.
Assuntos
Síndrome Antifosfolipídica/patologia , Infecções por Coronavirus/patologia , Coagulação Intravascular Disseminada/patologia , Pneumonia Viral/patologia , Tromboembolia/patologia , Trombose/patologia , Síndrome Antifosfolipídica/imunologia , Antivirais/uso terapêutico , Betacoronavirus , Coagulação Sanguínea/fisiologia , COVID-19 , Infecções por Coronavirus/tratamento farmacológico , Infecções por Coronavirus/imunologia , Coagulação Intravascular Disseminada/imunologia , Produtos de Degradação da Fibrina e do Fibrinogênio/metabolismo , Humanos , Pandemias , Fosfolipídeos/imunologia , Pneumonia Viral/tratamento farmacológico , Pneumonia Viral/imunologia , SARS-CoV-2 , Tromboembolia/imunologiaRESUMO
Beta 2 glycoprotein I (ß2GPI) is a major antigen for autoantibodies present in antiphospholipid antibody syndrome (APS). ß2GPI is a single polypeptide with five repeated domains and different conformations. The activated J-shaped conformation of ß2GPI binds to negatively charged phospholipids in the membrane via the fifth domain and causes blood clotting reactions. We applied a drug repurposing strategy using virtual screening and molecular dynamics to find the best FDA drugs against the fifth domain of ß2GPI. In the first phase, FDA drugs that had the most favorable ΔG with the fifth domain of ß2GPI were selected by virtual screening. Among these drugs that had the most favorable ΔG, Vorapaxar and Antrafenine were selected for molecular dynamics (MD) simulation studies. MD simulation was performed to evaluate the stability of Vorapaxar and Antrafenine complexes and the effect of the two drugs on protein conformation. Also, MD simulation was done to investigate the effect of Antrafenine and Vorapaxar on the binding of ß2GPI to the platelet model membrane. According to the results, Vorapaxar and Antrafenine were bound to the protein with the favorable binding energy (Vorapaxar and Antrafenine binding energies are - 49.641 and - 38.803 kcal/mol, respectively). In this study, it was shown that unlike protein alone and protein in the Antrafenine complex, the protein in the Vorapaxar complex was completely separated from the model membrane after 350 ns. Moreover, Vorapaxar led to more changes in the activated J-shape of ß2GPI. Thus, Vorapaxar can be a suitable candidate for further investigations on the treatment of APS.
Assuntos
Antígenos/imunologia , Síndrome Antifosfolipídica/imunologia , Autoanticorpos/imunologia , Fosfolipídeos/imunologia , beta 2-Glicoproteína I/antagonistas & inibidores , Coagulação Sanguínea/imunologia , Simulação por Computador , Humanos , Lactonas/farmacologia , Piperazinas/farmacologia , Ligação Proteica/imunologia , Piridinas/farmacologiaRESUMO
Innate lymphoid cells (ILCs) play an important role in the control and maintenance of barrier immunity. However, chronic activation of ILCs results in immune-mediated pathology. Here, we show that tissue-resident type 2 ILCs (ILC2s) display a distinct metabolic signature upon chronic activation. In the context of allergen-driven airway inflammation, ILC2s increase their uptake of both external lipids and glucose. Externally acquired fatty acids are transiently stored in lipid droplets and converted into phospholipids to promote the proliferation of ILC2s. This metabolic program is imprinted by interleukin-33 (IL-33) and regulated by the genes Pparg and Dgat1, which are both controlled by glucose availability and mTOR signaling. Restricting dietary glucose by feeding mice a ketogenic diet largely ablated ILC2-mediated airway inflammation by impairing fatty acid metabolism and the formation of lipid droplets. Together, these results reveal that pathogenic ILC2 responses require lipid metabolism and identify ketogenic diet as a potent intervention strategy to treat airway inflammation.
Assuntos
Alérgenos/administração & dosagem , Asma/dietoterapia , Diacilglicerol O-Aciltransferase/imunologia , Dieta Cetogênica/métodos , Interleucina-33/imunologia , Gotículas Lipídicas/metabolismo , Subpopulações de Linfócitos T/imunologia , Alternaria/química , Animais , Asma/induzido quimicamente , Asma/imunologia , Asma/patologia , Linhagem da Célula/efeitos dos fármacos , Linhagem da Célula/genética , Linhagem da Célula/imunologia , Citocinas/administração & dosagem , Diacilglicerol O-Aciltransferase/genética , Modelos Animais de Doenças , Ácidos Graxos/imunologia , Ácidos Graxos/metabolismo , Regulação da Expressão Gênica , Glucose/imunologia , Glucose/metabolismo , Imunidade Inata , Interleucina-33/administração & dosagem , Interleucina-33/genética , Interleucinas/administração & dosagem , Gotículas Lipídicas/imunologia , Pulmão/efeitos dos fármacos , Pulmão/imunologia , Pulmão/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , PPAR gama/genética , PPAR gama/imunologia , Papaína/administração & dosagem , Fosfolipídeos/imunologia , Fosfolipídeos/metabolismo , Cultura Primária de Células , Subpopulações de Linfócitos T/classificação , Subpopulações de Linfócitos T/efeitos dos fármacos , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/imunologia , Linfopoietina do Estroma do TimoRESUMO
A major obstacle to nanodrugs-mediated cancer therapy is their rapid uptake by the reticuloendothelial system that decreases the systemic exposure of the nanodrugs to tumors and also increases toxicities. Intralipid has been shown to reduce nano-oxaliplatin-mediated toxicity while improving bioavailability. Here, we have found that Intralipid reduces the cytotoxicity of paclitaxel for human monocytic cells, but not for breast, lung, or pancreatic cancer cells. Intralipid also promotes the polarization of macrophages to the anti-cancer M1-like phenotype. Using a xenograft breast cancer mouse model, we have found that Intralipid pre-treatment significantly increases the amount of paclitaxel reaching the tumor and promotes tumor apoptosis. The combination of Intralipid with half the standard clinical dose of Abraxane reduces the tumor growth rate as effectively as the standard clinical dose. Our findings suggest that pre-treatment of Intralipid has the potential to be a powerful agent to enhance the tumor cytotoxic effects of Abraxane and to reduce its off-target toxicities.
Assuntos
Paclitaxel Ligado a Albumina/farmacologia , Neoplasias da Mama/tratamento farmacológico , Imunidade Inata/efeitos dos fármacos , Fosfolipídeos/farmacologia , Óleo de Soja/farmacologia , Animais , Antineoplásicos , Apoptose/efeitos dos fármacos , Disponibilidade Biológica , Neoplasias da Mama/imunologia , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Emulsões/farmacologia , Feminino , Xenoenxertos , Humanos , Camundongos , Nanopartículas/química , Oxaliplatina/farmacologia , Paclitaxel/química , Paclitaxel/farmacologia , Fosfolipídeos/imunologia , Óleo de Soja/imunologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Individuals growing up in malaria endemic areas gradually develop protection against clinical malaria and passive transfer experiments in humans have demonstrated that this protection is mediated in part by protective antibodies. However, neither the target antigens, specific effector mechanisms, nor the role of continual parasite exposure have been elucidated, which complicates vaccine development. Progress has been made in defining the innate signaling pathways activated by parasite components, including DNA, RNA, hemozoin, and phospholipids, which initiate the immune response and will be the focus of this review. The challenge that remains within the field is to understand the role of these early responses in the development of protective adaptive responses that clear iRBC and block merozoite invasion so that optimal vaccines and therapeutics may be produced.
Assuntos
Eritrócitos/parasitologia , Imunidade/imunologia , Estágios do Ciclo de Vida/imunologia , Merozoítos/imunologia , Parasitos/imunologia , Imunidade Adaptativa/imunologia , Animais , Antígenos de Protozoários/imunologia , Antimaláricos/imunologia , Células Dendríticas , Hemeproteínas , Humanos , Células Matadoras Naturais , Malária/imunologia , Malária/prevenção & controle , Malária Falciparum/imunologia , Malária Falciparum/prevenção & controle , Fosfolipídeos/imunologia , Pigmentos Biológicos/imunologia , Plasmodium falciparum/imunologia , Proteínas de Protozoários/imunologia , Vacinas Protozoárias/imunologiaRESUMO
Macrophages activated by Interleukin (IL)-4 (M2) or LPS+ Interferon (IFN)γ (M1) perform specific functions respectively in type 2 inflammation and killing of pathogens. Group V phospholipase A2 (Pla2g5) is required for the development and functions of IL-4-activated macrophages and phagocytosis of pathogens. Pla2g5-generated bioactive lipids, including lysophospholipids (LysoPLs), fatty acids (FAs), and eicosanoids, have a role in many diseases. However, little is known about their production by differentially activated macrophages. We performed an unbiased mass-spectrometry analysis of phospholipids (PLs), LysoPLs, FAs, and eicosanoids produced by Wild Type (WT) and Pla2g5-null IL-4-activated bone marrow-derived macrophages (IL-4)BM-Macs (M2) and (LPS+IFNγ)BM-Macs (M1). Phosphatidylcholine (PC) was preferentially metabolized in (LPS+IFNγ)BM-Macs and Phosphatidylethanolamine (PE) in (IL-4)BM-Macs, with Pla2g5 contributing mostly to metabolization of selected PE molecules. While Pla2g5 produced palmitic acid (PA) in (LPS+IFNγ)BM-Macs, the absence of Pla2g5 increased myristic acid (MA) in (IL-4)BM-Macs. Among eicosanoids, Prostaglandin E2 (PGE2) and prostaglandin D2 (PGD2) were significantly reduced in (IL-4)BM-Macs and (LPS+IFNγ)BM-Macs lacking Pla2g5. Instead, the IL-4-induced increase in 20-carboxy arachidonic acid (20CooH AA) was dependent on Pla2g5, as was the production of 12-hydroxy-heptadecatrienoic acid (12-HHTrE) in (LPS+IFNγ)BM-Macs. Thus, Pla2g5 contributes to PE metabolization, PGE2 and PGD2 production independently of the type of activation, while in (IL-4)BM-Macs, Pla2g5 regulates selective lipid pathways and likely novel functions.
Assuntos
Fosfolipases A2 do Grupo V/imunologia , Ativação de Macrófagos , Macrófagos/imunologia , Fosfolipídeos/imunologia , Animais , Células Cultivadas , Humanos , Inflamação/imunologia , Interleucina-4/imunologia , Camundongos , Fosfolipídeos/análiseRESUMO
Lipid droplets are fat storage organelles present in most eukaryotic cells. They consist of a neutral lipid core containing mostly triglycerides and sterol esters and covered by a monolayer of phospholipids, wherein numerous proteins are embedded. In the cell, lipid droplets have a dynamic life cycle, rapidly altering their size, location, lipid and protein composition in response to environmental stimuli and cell state. Lipid droplets are primarily involved in the coordination of lipid metabolism with cellular requirements for energy production, membrane homeostasis and cell growth. However, they are also directly or indirectly engaged in signalling pathways. On the one hand, lipid droplets sequester lipids and proteins thereby limiting their availability for participation in signalling pathways. On the other hand, the lipolytic machinery provides a highly regulated, on-demand source of signalling lipids: lipids derived from their neutral lipid core, or the phospholipid monolayer, directly act as signalling mediators or are converted into ones. In fact, emerging studies suggest that these organelles are essential for various cellular stress response mechanisms, including inflammation and immunity, acting as hubs that integrate metabolic and inflammatory processes. Here, we discuss the ways in which lipid droplets regulate the availability of fatty acids for the activation of signalling pathways and for the production of polyunsaturated fatty acid-derived lipid mediators. We focus in particular on recent discoveries in immune cells and adipose tissue that have revealed an intricate relationship between lipid droplets and inflammatory signalling and may also be relevant for other tissues and various human diseases.
Assuntos
Tecido Adiposo/metabolismo , Eicosanoides/metabolismo , Gotículas Lipídicas/metabolismo , Metabolismo dos Lipídeos/genética , Fosfolipídeos/metabolismo , Triglicerídeos/metabolismo , Tecido Adiposo/imunologia , Animais , Ácidos Docosa-Hexaenoicos/imunologia , Ácidos Docosa-Hexaenoicos/metabolismo , Eicosanoides/imunologia , Regulação da Expressão Gênica , Homeostase/genética , Homeostase/imunologia , Humanos , Inflamação , Lipase/genética , Lipase/imunologia , Gotículas Lipídicas/imunologia , Metabolismo dos Lipídeos/imunologia , Fosfolipases/genética , Fosfolipases/imunologia , Fosfolipídeos/imunologia , Transdução de Sinais , Receptores Toll-Like/genética , Receptores Toll-Like/imunologia , Triglicerídeos/imunologiaRESUMO
Oxidized phospholipids (OxPLs), which arise due to oxidative stress, are proinflammatory and proatherogenic, but their roles in non-alcoholic steatohepatitis (NASH) are unknown. Here, we show that OxPLs accumulate in human and mouse NASH. Using a transgenic mouse that expresses a functional single-chain variable fragment of E06, a natural antibody that neutralizes OxPLs, we demonstrate the causal role of OxPLs in NASH. Targeting OxPLs in hyperlipidemic Ldlr-/- mice improved multiple aspects of NASH, including steatosis, inflammation, fibrosis, hepatocyte death, and progression to hepatocellular carcinoma. Mechanistically, we found that OxPLs promote ROS accumulation to induce mitochondrial dysfunction in hepatocytes. Neutralizing OxPLs in AMLN-diet-fed Ldlr-/- mice reduced oxidative stress, improved hepatic and adipose-tissue mitochondrial function, and fatty-acid oxidation. These results suggest targeting OxPLs may be an effective therapeutic strategy for NASH.
Assuntos
Apoptose/genética , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/metabolismo , Mitocôndrias/metabolismo , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Estresse Oxidativo , Fosfolipídeos/metabolismo , Anticorpos de Cadeia Única/uso terapêutico , Animais , Apoptose/efeitos dos fármacos , Carcinoma Hepatocelular/tratamento farmacológico , Dieta Hiperlipídica , Fígado Gorduroso/complicações , Fígado Gorduroso/tratamento farmacológico , Ontologia Genética , Hepatócitos/citologia , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Inflamação/complicações , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Cirrose Hepática/complicações , Cirrose Hepática/tratamento farmacológico , Cirrose Hepática/metabolismo , Neoplasias Hepáticas/tratamento farmacológico , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia Eletrônica de Transmissão , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/patologia , Mitocôndrias/ultraestrutura , Hepatopatia Gordurosa não Alcoólica/complicações , Hepatopatia Gordurosa não Alcoólica/metabolismo , Obesidade/tratamento farmacológico , Oxirredução , Fosfolipídeos/sangue , Fosfolipídeos/imunologia , RNA-Seq , Espécies Reativas de Oxigênio/metabolismoRESUMO
The cockroach allergen Bla g 1 forms a novel fold consisting of 12 amphipathic alpha-helices enclosing an exceptionally large hydrophobic cavity which was previously demonstrated to bind a variety of lipids. Since lipid-dependent immunoactivity is observed in numerous allergens, understanding the structural basis of this interaction could yield insights into the molecular determinants of allergenicity. Here, we report atomic modelling of Bla g 1 bound to both fatty-acid and phospholipids ligands, with 8 acyl chains suggested to represent full stoichiometric binding. This unusually high occupancy was verified experimentally, though both modelling and circular dichroism indicate that the general alpha-helical structure is maintained regardless of cargo loading. Fatty-acid cargoes significantly enhanced thermostability while inhibiting cleavage by cathepsin S, an endosomal protease essential for antigen processing and presentation; the latter of which was found to correlate to a decreased production of known T-cell epitopes. Both effects were strongly dependent on acyl chain length, with 18-20 carbons providing the maximal increase in melting temperature (~20 °C) while completely abolishing proteolysis. Diacyl chain cargoes provided similar enhancements to thermostability, but yielded reduced levels of proteolytic resistance. This study describes how the biophysical properties of Bla g 1 ligand binding and digestion may relate to antigen processing, with potential downstream implications for immunogenicity.
Assuntos
Alérgenos , Blattellidae/imunologia , Proteínas de Insetos , Alérgenos/química , Alérgenos/imunologia , Animais , Apresentação de Antígeno , Ácidos Graxos/imunologia , Ácidos Graxos/metabolismo , Proteínas de Insetos/química , Proteínas de Insetos/imunologia , Ligantes , Fosfolipídeos/imunologia , Fosfolipídeos/metabolismo , Ligação Proteica/imunologia , Estabilidade Proteica , Estrutura Terciária de ProteínaRESUMO
Adaptive lymphocytes express a panel of immunoreceptors on the cell surface. Phospholipids are the major components of cell membranes, but they have functional roles beyond forming lipid bilayers. In particular, acidic phospholipids forming microdomains in the plasma membrane can ionically interact with proteins via polybasic sequences, which can have functional consequences for the protein. We have shown that negatively charged acidic phospholipids can interact with positively charged juxtamembrane polybasic regions of immunoreceptors, such as TCR-CD3, CD28 and IgG-BCR, to regulate protein structure and function. Furthermore, we pay our attention to protein transmembrane domains. We show that a membrane-snorkeling Lys residue in integrin αLß2 regulates transmembrane heterodimer formation and integrin adhesion through ionic interplay with acidic phospholipids and calcium ions (Ca2+) in T cells, thus providing a new mechanism of integrin activation. Here, we review our recent progress showcasing the importance of both juxtamembrane and intramembrane ionic protein-lipid interactions.