RESUMO
OBJECTIVES: To assess the utility of Helicobacter pylori antibody testing, we evaluated the correlation between the H. pylori antibody titre and H. pylori-associated pathogenicity and the changes in antibody titre after H. pylori eradication therapy. DESIGN: A retrospective observational cohort study. SETTING AND PARTICIPANTS: From 2004 to 2016, medical check-ups were performed in different regions of Japan. In total, 324 subjects infected with H. pylori who received H. pylori eradication therapy were enrolled; H. pylori was eradicated in 266 of these subjects. We examined the associations between H. pylori antibody titre with pepsinogen and the presence or absence of H. pylori-associated pathogenic proteins, such as cytotoxin-associated gene A and vacuolating cytotoxin gene A, at baseline and after H. pylori eradication therapy. RESULTS: The H.pylori antibody titre showed a positive correlation with pepsinogen II and a negative correlation with the pepsinogen I/II ratio. Moreover, the H.pylori antibody titre significantly correlated with the positive rates of H. pylori-associated pathogenic protein before eradication therapy. Antibody titres decreased after eradication, the pepsinogen I/II ratio increased and the H. pylori-associated pathogenic protein-positive rate decreased in patients with successful eradication. The determination of eradication using the decline in antibody titre 6 months after eradication therapy was useful (area under the receiver operating characteristic curve: 0.98). CONCLUSIONS: Our data indicate that the H. pylori antibody titre may represent the degree of pathogenicity. The H. pylori antibody titre was associated with attenuation of pathogenicity in patients with H. pylori eradication, indicating the clinical utility of H. pylori antibody testing.
Assuntos
Anticorpos Antibacterianos , Infecções por Helicobacter , Helicobacter pylori , Pepsinogênio A , Humanos , Helicobacter pylori/imunologia , Estudos Retrospectivos , Infecções por Helicobacter/tratamento farmacológico , Infecções por Helicobacter/imunologia , Infecções por Helicobacter/microbiologia , Masculino , Feminino , Japão , Anticorpos Antibacterianos/sangue , Pessoa de Meia-Idade , Idoso , Pepsinogênio A/sangue , Adulto , Antibacterianos/uso terapêutico , Proteínas de Bactérias/imunologia , Pepsinogênio C/sangue , Antígenos de Bactérias/imunologiaRESUMO
Mucosal-associated invariant T (MAIT) cells are a major subset of innate-like T cells that function at the interface between innate and acquired immunity. MAIT cells recognize vitamin B2-related metabolites produced by microbes, through semi-invariant T cell receptor (TCR) and contribute to protective immunity. These foreign-derived antigens are presented by a monomorphic antigen presenting molecule, MHC class I-related molecule 1 (MR1). MR1 contains a malleable ligand-binding pocket, allowing for the recognition of compounds with various structures. However, interactions between MR1 and self-derived antigens are not fully understood. Recently, bile acid metabolites were identified as host-derived ligands for MAIT cells. In this review, we will highlight recent findings regarding the recognition of self-antigens by MAIT cells.
Assuntos
Antígenos de Histocompatibilidade Classe I , Células T Invariantes Associadas à Mucosa , Células T Invariantes Associadas à Mucosa/imunologia , Células T Invariantes Associadas à Mucosa/metabolismo , Humanos , Animais , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Antígenos de Histocompatibilidade Menor/imunologia , Antígenos de Histocompatibilidade Menor/metabolismo , Autoantígenos/imunologia , Apresentação de Antígeno/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Receptores de Antígenos de Linfócitos T/metabolismoRESUMO
Staphylococcus aureus is a prevalent pathogen in pneumonia and harbors glycolipids, which may serve as molecular patterns in Mincle (macrophage-inducible C-type lectin)-dependent pathogen recognition. We examined the role of Mincle in lung defense against S aureus in wild-type (WT), Mincle knockout (KO), and Mincle transgenic (tg) mice. Two glycolipids, glucosyl-diacylglycerol (Glc-DAG) and diglucosyl-diacylglycerol (Glc2-DAG), were purified, of which only Glc-DAG triggered Mincle reporter cell activation and professional phagocyte responses. Proteomic profiling revealed that Glc2-DAG blocked Glc-DAG-induced cytokine responses, thereby acting as inhibitor of Glc-DAG/Mincle signaling. WT mice responded to S aureus with a similar lung pathology as Mincle KO mice, most likely due to Glc2-DAG-dependent inhibition of Glc-DAG/Mincle signaling. In contrast, ectopic Mincle expression caused severe lung pathology in S aureus-infected mice, characterized by bacterial outgrowth and fatal pneumonia. Collectively, Glc2-DAG inhibits Glc-DAG/Mincle-dependent responses in WT mice, whereas sustained Mincle expression overrides Glc2-DAG-mediated inhibitory effects, conferring increased host susceptibility to S aureus.
Assuntos
Lectinas Tipo C , Proteínas de Membrana , Camundongos Knockout , Pneumonia Estafilocócica , Staphylococcus aureus , Animais , Lectinas Tipo C/metabolismo , Lectinas Tipo C/genética , Pneumonia Estafilocócica/microbiologia , Pneumonia Estafilocócica/imunologia , Camundongos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Pulmão/microbiologia , Pulmão/patologia , Camundongos Transgênicos , Camundongos Endogâmicos C57BL , Transdução de Sinais , Suscetibilidade a Doenças , Citocinas/metabolismoRESUMO
Cryptococcus deneoformans is a yeast-type fungus that causes fatal meningoencephalitis in immunocompromised patients and evades phagocytic cell elimination through an escape mechanism. Memory T (Tm) cells play a central role in preventing the reactivation of this fungal pathogen. Among these cells, tissue-resident memory T (TRM) cells quickly respond to locally invaded pathogens. This study analyzes the kinetics of effector T (Teff) cells and Tm cells in the lungs after cryptococcal infection. Emphasis is placed on the kinetics and cytokine expression of TRM cells in the early phase of infection. CD4+ Tm cells exhibited a rapid increase by day 3, peaked at day 7, and then either maintained their levels or exhibited a slight decrease until day 56. In contrast, CD8+ Tm cells reached their peak on day 3 and thereafter decreased up to day 56 post-infection. These Tm cells were predominantly composed of CD69+ TRM cells and CD69+ CD103+ TRM cells. Disruption of the CARD9 gene resulted in reduced accumulation of these TRM cells and diminished interferon (IFN) -γ expression in TRM cells. TRM cells were derived from T cells with T cell receptors non-specific to ovalbumin in OT-II mice during cryptococcal infection. In addition, TRM cells exhibited varied behavior in different tissues. These results underscore the importance of T cells, which produce IFN-γ in the lungs during the early stage of infection, in providing early protection against cryptococcal infection through CARD9 signaling.
Assuntos
Antígenos CD , Antígenos de Diferenciação de Linfócitos T , Criptococose , Cryptococcus , Interferon gama , Lectinas Tipo C , Pulmão , Animais , Criptococose/imunologia , Criptococose/microbiologia , Interferon gama/metabolismo , Interferon gama/imunologia , Camundongos , Antígenos de Diferenciação de Linfócitos T/metabolismo , Cryptococcus/imunologia , Antígenos CD/metabolismo , Antígenos CD/genética , Lectinas Tipo C/metabolismo , Lectinas Tipo C/genética , Pulmão/imunologia , Pulmão/microbiologia , Células T de Memória/imunologia , Células T de Memória/metabolismo , Camundongos Endogâmicos C57BL , Memória Imunológica , Imunidade Inata , Proteínas Adaptadoras de Sinalização CARD/metabolismo , Linfócitos T CD4-Positivos/imunologiaRESUMO
SARS-CoV-2 vaccines have been used worldwide to combat COVID-19 pandemic. To elucidate the factors that determine the longevity of spike (S)-specific antibodies, we traced the characteristics of S-specific T cell clonotypes together with their epitopes and anti-S antibody titers before and after BNT162b2 vaccination over time. T cell receptor (TCR) αß sequences and mRNA expression of the S-responded T cells were investigated using single-cell TCR- and RNA-sequencing. Highly expanded 199 TCR clonotypes upon stimulation with S peptide pools were reconstituted into a reporter T cell line for the determination of epitopes and restricting HLAs. Among them, we could determine 78 S epitopes, most of which were conserved in variants of concern (VOCs). After the 2nd vaccination, T cell clonotypes highly responsive to recall S stimulation were polarized to follicular helper T (Tfh)-like cells in donors exhibiting sustained anti-S antibody titers (designated as 'sustainers'), but not in 'decliners'. Even before vaccination, S-reactive CD4+ T cell clonotypes did exist, most of which cross-reacted with environmental or symbiotic microbes. However, these clonotypes contracted after vaccination. Conversely, S-reactive clonotypes dominated after vaccination were undetectable in pre-vaccinated T cell pool, suggesting that highly responding S-reactive T cells were established by vaccination from rare clonotypes. These results suggest that de novo acquisition of memory Tfh-like cells upon vaccination may contribute to the longevity of anti-S antibody titers.
Assuntos
Anticorpos Antivirais , Vacina BNT162 , Vacinas contra COVID-19 , COVID-19 , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus , Vacinação , Humanos , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/sangue , Glicoproteína da Espícula de Coronavírus/imunologia , SARS-CoV-2/imunologia , COVID-19/imunologia , COVID-19/prevenção & controle , Vacina BNT162/imunologia , Vacina BNT162/administração & dosagem , Vacinas contra COVID-19/imunologia , Vacinas contra COVID-19/administração & dosagem , Feminino , Masculino , Epitopos de Linfócito T/imunologia , Adulto , Linfócitos T Auxiliares-Indutores/imunologia , Pessoa de Meia-IdadeRESUMO
C-type lectin receptors (CLRs) expressed by myeloid cells constitute a versatile family of receptors that play a key role in innate immune recognition. Myeloid CLRs exhibit a remarkable ability to recognize an extensive array of ligands, from carbohydrates and beyond, and encompass pattern-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs), and markers of altered self. These receptors, classified into distinct subgroups, play pivotal roles in immune recognition and modulation of immune responses. Their intricate signaling pathways orchestrate a spectrum of cellular responses, influencing processes such as phagocytosis, cytokine production, and antigen presentation. Beyond their contributions to host defense in viral, bacterial, fungal, and parasitic infections, myeloid CLRs have been implicated in non-infectious diseases such as cancer, allergies, and autoimmunity. A nuanced understanding of myeloid CLR interactions with endogenous and microbial triggers is starting to uncover the context-dependent nature of their roles in innate immunity, with implications for therapeutic intervention.
Assuntos
Lectinas Tipo C , Neoplasias , Humanos , Lectinas Tipo C/metabolismo , Imunidade Inata , Células Mieloides/metabolismo , Transdução de Sinais , Neoplasias/metabolismo , Receptores de Reconhecimento de Padrão/metabolismoRESUMO
There is a need for improved vaccine adjuvants to augment vaccine efficacy. One way to address this is by targeting multiple immune cell pathogen recognition receptors (PRRs) using chimeric pathogen-associated molecular patterns (PAMPs). Conjugation of the PAMPs will ensure codelivery of the immunostimulatory molecules to the same cell, enhancing adjuvant activity. The macrophage inducible C-type lectin (Mincle) is a promising PRR for adjuvant development; however, no effective chimeric Mincle adjuvants have been prepared. We addressed this by synthesizing Mincle adjuvant conjugates, MDP-C18Brar and MDP-C18Brar-dilipid, which contain PAMPs recognized by Mincle and the nucleotide-binding oligomerization domain 2 (NOD2). The two PAMPs are joined by a pH-sensitive oxyamine linker which, upon acidification at lysosomal pH, hydrolyzed to release the NOD2 ligands. The conjugates elicited the production of Th1 and Th17 promoting cytokines in vitro, and when using OVA as a model antigen, exhibited enhanced T-cell-mediated immune responses and reduced toxicity in vivo, compared to the coadministration of the adjuvants.
Assuntos
Adjuvantes de Vacinas , Moléculas com Motivos Associados a Patógenos , Adjuvantes Imunológicos/farmacologia , Adjuvantes Imunológicos/química , Imunidade Celular , Citocinas , Antígenos , Receptores Imunológicos , Lectinas Tipo CRESUMO
Dectin-1 is a well-characterized C-type lectin receptor involved in anti-fungal immunity through the recognition of polysaccharides; however, molecular mechanisms and outcomes initiated through self-recognition have not been fully understood. Here, we purified a water-soluble fraction from mouse liver that acts as a Dectin-1 agonist. To address the physiological relevance of this recognition, we utilized sterile liver inflammation models. The CCl4-induced hepatitis model showed that Dectin-1 deficiency led to reduced inflammation through decreased inflammatory cell infiltration and lower pro-inflammatory cytokine levels. Moreover, in a NASH model induced by streptozotocin and a high-fat diet, hepatic inflammation and fibrosis were ameliorated in Dectin-1-deficient mice. The Dectin-1 agonist activity was increased in the water-soluble fraction from NASH mice, suggesting a potential pathogenic cycle between Dectin-1 activation and hepatitis progression. In vivo administration of the fraction into mice induced hepatic inflammation. These results highlight a role of self-recognition through Dectin-1 that triggers hepatic innate immune responses and contributes to the exacerbation of inflammation in pathogenic settings. Thus, the blockade of this axis may provide a therapeutic option for liver inflammatory diseases.
Assuntos
Hepatite , Lectinas Tipo C , Hepatopatia Gordurosa não Alcoólica , Animais , Camundongos , Inflamação/metabolismo , Camundongos Endogâmicos C57BL , Hepatopatia Gordurosa não Alcoólica/imunologia , Hepatopatia Gordurosa não Alcoólica/metabolismo , ÁguaRESUMO
C-type lectin receptors (CLRs) are a family of pattern recognition receptors, which detect a broad spectrum of ligands via small carbohydrate-recognition domains (CRDs). CLEC12A is an inhibitory CLR that recognizes crystalline structures such as monosodium urate crystals. CLEC12A also recognizes mycolic acid, a major component of mycobacterial cell walls, and suppresses host immune responses. Although CLEC12A could be a therapeutic target for mycobacterial infection, structural information on CLEC12A was not available. We report here the crystal structures of human CLEC12A (hCLEC12A) in ligand-free form and in complex with 50C1, its inhibitory antibody. 50C1 recognizes human-specific residues on the top face of hCLEC12A CRD. A comprehensive alanine scan demonstrated that the ligand-binding sites of mycolic acid and monosodium urate crystals may overlap with each other, suggesting that CLEC12A utilizes a common interface to recognize different types of ligands. Our results provide atomic insights into the blocking and ligand-recognition mechanisms of CLEC12A and leads to the design of CLR-specific inhibitors.
Assuntos
Lectinas Tipo C , Receptores Mitogênicos , Lectinas Tipo C/imunologia , Lectinas Tipo C/química , Lectinas Tipo C/metabolismo , Humanos , Receptores Mitogênicos/química , Receptores Mitogênicos/imunologia , Receptores Mitogênicos/metabolismo , Cristalografia por Raios X , Ligantes , Ligação Proteica , Sítios de Ligação , Modelos Moleculares , Ácido Úrico/química , Ácido Úrico/metabolismo , Ácido Úrico/imunologiaRESUMO
The acetal (O-glycoside) bonds of glycans and glycoconjugates are chemically and biologically vulnerable, and therefore C-glycosides are of interest as more stable analogs. We hypothesized that, if the O-glycoside linkage plays a vital role in glycan function, the biological activities of C-glycoside analogs would vary depending on their substituents. Based on this idea, we adopted a "linkage-editing strategy" for the creation of glycan analogs (pseudo-glycans). We designed three types of pseudo-glycans with CH2 and CHF linkages, which resemble the O-glycoside linkage in terms of bond lengths, angles, and bulkiness, and synthesized them efficiently by means of fluorovinyl C-glycosylation and selective hydrogenation reactions. Application of this strategy to isomaltose (IM), an inducer of amylase expression, and α-GalCer, which activates iNKT cells, resulted in the discovery of CH2-IM, which shows increased amylase production ability, and CHF-α-GalCer, which shows activity opposite that of native α-GalCer, serving as an antagonist of iNKT cells.
Assuntos
Galactosilceramidas , Glicosídeos , Polissacarídeos , Glicosilação , Polissacarídeos/química , Amilases/metabolismoRESUMO
Mucosal-associated invariant T (MAIT) cells are innate-like T cells that recognize bacterial riboflavin-based metabolites as activating antigens. Although MAIT cells are found in tissues, it is unknown whether any host tissue-derived antigens exist. Here, we report that a sulfated bile acid, cholic acid 7-sulfate (CA7S), binds the nonclassical MHC class I protein MR1 and is recognized by MAIT cells. CA7S is a host-derived metabolite whose levels were reduced by more than 98% in germ-free mice. Deletion of the sulfotransferase 2a family of enzymes (Sult2a1-8) responsible for CA7S synthesis reduced the number of thymic MAIT cells in mice. Moreover, recognition of CA7S induced MAIT cell survival and the expression of a homeostatic gene signature. By contrast, recognition of a previously described foreign antigen, 5-(2-oxopropylideneamino)-6-d-ribitylaminouracil (5-OP-RU), drove MAIT cell proliferation and the expression of inflammatory genes. Thus, CA7S is an endogenous antigen for MAIT cells, which promotes their development and function.
Assuntos
Células T Invariantes Associadas à Mucosa , Animais , Camundongos , Ácidos e Sais Biliares , Ligantes , Sulfatos , Antígenos de Histocompatibilidade Menor/metabolismo , AntígenosRESUMO
Although chitin in fungal cell walls is associated with allergic airway inflammation, the precise mechanism underlying this association has yet to be elucidated. Here, we investigated the involvement of fungal chitin-binding protein and chitin in allergic airway inflammation. Recombinant Aspergillus fumigatus LdpA (rLdpA) expressed in Pichia pastoris was shown to be an O-linked glycoprotein containing terminal α-mannose residues recognized by the host C-type lectin receptor, Dectin-2. Chitin particles were shown to induce acute neutrophilic airway inflammation mediated release of interleukin-1α (IL-1α) associated with cell death. Furthermore, rLdpA-Dectin-2 interaction was shown to promote phagocytosis of rLdpA-chitin complex and activation of mouse bone marrow-derived dendritic cells (BMDCs). Moreover, we showed that rLdpA potently induced T helper 2 (Th2)-driven allergic airway inflammation synergistically with chitin, and Dectin-2 deficiency attenuated the rLdpA-chitin complex-induced immune response in vivo. In addition, we showed that serum LdpA-specific immunoglobulin levels were elevated in patients with pulmonary aspergillosis.
Assuntos
Quitina , Lectinas Tipo C , Humanos , Animais , Camundongos , Quitina/metabolismo , Lectinas Tipo C/genética , Lectinas Tipo C/metabolismo , Aspergillus fumigatus , Inflamação , Fagocitose , Glicoproteínas/metabolismoRESUMO
INTRODUCTION: People living with human immunodeficiency virus (PLWH) have higher mortality rates from COVID-19 than those without HIV. Additionally, the seroconversion rate of antibodies following a second dose of SARS-CoV-2 vaccine is lower in PLWH than non-infected individuals, indicating the need for booster vaccination. Here, we evaluated the humoral and cellular immune responses to booster SARS-CoV-2 vaccination in PLWH. METHODS: The dynamics of anti-spike IgG titers and antigen-specific interferon (IFN)-γ levels to SARS-CoV-2 vaccination were assessed over a 6-month period following a third vaccination of 34 PLWH. RESULTS: Antibody titers for humoral immunity were 50 % lower at 24 weeks post-vaccination than those at 12 weeks. However, those at 24 weeks after the booster vaccination were approximately eight times higher than before. Regarding cellular immunity, IFN-γ levels at 24 weeks after the third vaccination were lower than those at 12 weeks, but nearly 90 % of participants maintained a cut-off value of ≥0.15 IU/mL. A comparison between two groups with CD4+ T lymphocytes counts of <500/µL or ≥500/µL exhibited no statistically significant differences in antibody or IFN-γ levels. However, in the group with CD4+ T lymphocyte counts of <500/µL, the rate of IFN-γ above the cut-off value at 24 weeks after the booster vaccination was lower than that of ≥500/µL. CONCLUSION: An immune response is expected in PLWH given successful antiretroviral therapy with booster SARS-CoV-2 vaccination. However, caution should be exercised for cases with low CD4+ T-lymphocyte counts. (240/250 words).
Assuntos
COVID-19 , HIV , Humanos , Vacinas contra COVID-19 , SARS-CoV-2 , COVID-19/prevenção & controle , Imunidade Celular , RNA Mensageiro , Vacinação , Anticorpos AntiviraisRESUMO
Intranasal vaccines are anticipated to be powerful tools for combating many infectious diseases, including SARS-CoV-2, because they induce not only systemic immunity but also mucosal immunity at the site of initial infection. However, they are generally inefficient in inducing an antigen-specific immune response without adjuvants. Here, we developed an adjuvant-free intranasal vaccine platform that utilizes the preexisting immunity induced by previous infection or vaccination to enhance vaccine effectiveness. We made RBD-HA, a fusion of the receptor-binding domain (RBD) of spike derived from SARS-CoV-2 as a vaccine target with HA derived from influenza A virus (IAV) as a carrier protein. Intranasal immunization of previously IAV-infected mice with RBD-HA without an adjuvant elicited robust production of RBD-specific systemic IgG and mucosal IgA by utilizing both HA-specific preexisting IgG and CD4+ T cells. Consequently, the mice were efficiently protected from SARS-CoV-2 infection. Additionally, we demonstrated the high versatility of this intranasal vaccine platform by assessing various vaccine antigens and preexisting immunity associated with a variety of infectious diseases. The results of this study suggest the promising potential of this intranasal vaccine platform to address problems associated with intranasal vaccines.
Assuntos
Doenças Transmissíveis , Vírus da Influenza A , Vacinas contra Influenza , Animais , Camundongos , Hemaglutininas , Anticorpos Antivirais , Imunização , Vacinação , Adjuvantes Imunológicos/farmacologia , Imunidade nas Mucosas , Vírus da Influenza A/genética , Imunoglobulina GRESUMO
C-type lectin receptors (CLRs), which are pattern recognition receptors responsible for triggering innate immune responses, recognize damaged self-components and immunostimulatory lipids from pathogenic bacteria; however, several of their ligands remain unknown. Here, we propose a new analytical platform combining liquid chromatography-high-resolution tandem mass spectrometry with microfractionation capability (LC-FRC-HRMS/MS) and a reporter cell assay for sensitive activity measurements to develop an efficient methodology for searching for lipid ligands of CLR from microbial trace samples (crude cell extracts of approximately 5 mg dry cell/mL). We also developed an in-house lipidomic library containing accurate mass and fragmentation patterns of more than 10,000 lipid molecules predicted in silico for 90 lipid subclasses and 35 acyl side chain fatty acids. Using the developed LC-FRC-HRMS/MS system, the lipid extracts of Helicobacter pylori were separated and fractionated, and HRMS and HRMS/MS spectra were obtained simultaneously. The fractionated lipid extract samples in 96-well plates were thereafter subjected to reporter cell assays using nuclear factor of activated T cells (NFAT)-green fluorescent protein (GFP) reporter cells expressing mouse or human macrophage-inducible C-type lectin (Mincle). A total of 102 lipid molecules from all fractions were annotated using an in-house lipidomic library. Furthermore, a fraction that exhibited significant activity in the NFAT-GFP reporter cell assay contained α-cholesteryl glucoside, a type of glycolipid, which was successfully identified as a lipid ligand molecule for Mincle. Our analytical platform has the potential to be a useful tool for efficient discovery of lipid ligands for immunoreceptors.
RESUMO
Mucosal-associated invariant T (MAIT) cells are innate-like T cells that are modulated by ligands presented on MHC class I-related proteins (MR1). These cells have attracted attention as potential drug targets because of their involvement in the initial response to infection and various disorders. Herein, we have established the MR1 presentation reporter assay system employing split-luciferase, which enables the efficient exploration of MR1 ligands. Using our screening system, we identified phenylpropanoid derivatives as MR1 ligands, including coniferyl aldehyde, which have an ability to inhibit the MR1-MAIT cell axis. Further, the structure-activity relationship study of coniferyl aldehyde analogs revealed the key structural features of ligands required for MR1 recognition. These results will contribute to identifying a broad range of endogenous and exogenous MR1 ligands and to developing novel MAIT cell modulators.
Assuntos
Acroleína , Bioensaio , Ligantes , Relação Estrutura-AtividadeRESUMO
Recently, various metabolites derived from host microbes have been reported to modulate the immune system, with potential involvement in health or diseases. Archaea, prokaryotic organisms, are present in the human body, but their connection with the host is largely unknown when compared to other microorganisms such as bacteria. This study focused on unique glycerolipids from symbiotic methanogenic archaea and evaluated their activities toward an innate immune receptor. The results revealed that archaeal lipids were recognized by the C-type lectin receptor Mincle and induced immune responses. A concurrent structure-activity relationship study identified the key structural features of archaeal lipids required for recognition by Mincle. Subsequent gene expression profiling suggested qualitative differences between the symbiotic archaeal lipid and the pathogenic bacteria-derived lipid. These findings have broad implications for understanding the function of symbiotic archaea in host health and diseases.
Assuntos
Archaea , Lectinas Tipo C , Humanos , Archaea/metabolismo , Lectinas Tipo C/metabolismo , Receptores Imunológicos/metabolismo , Relação Estrutura-Atividade , LipídeosRESUMO
Although leprosy (Hansen's disease) is one of the oldest known diseases, the pathogenicity of Mycobacterium leprae (M. leprae) remains enigmatic. Indeed, the cell wall components responsible for the immune response against M. leprae are as yet largely unidentified. We reveal here phenolic glycolipid-III (PGL-III) as an M. leprae-specific ligand for the immune receptor Mincle. PGL-III is a scarcely present trisaccharide intermediate in the biosynthetic pathway to PGL-I, an abundant and characteristic M. leprae glycolipid. Using activity-based purification, we identified PGL-III as a Mincle ligand that is more potent than the well-known M. tuberculosis trehalose dimycolate. The cocrystal structure of Mincle and a synthetic PGL-III analogue revealed a unique recognition mode, implying that it can engage multiple Mincle molecules. In Mincle-deficient mice infected with M. leprae, increased bacterial burden with gross pathologies were observed. These results show that PGL-III is a noncanonical ligand recognized by Mincle, triggering protective immunity.