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Carbohydrate Polymers Oct 2024Meningococcal glycoconjugate vaccines sourced from capsular polysaccharides (CPSs) of pathogenic Neisseria meningitidis strains are well-established measures to prevent...
Meningococcal glycoconjugate vaccines sourced from capsular polysaccharides (CPSs) of pathogenic Neisseria meningitidis strains are well-established measures to prevent meningococcal disease. However, the exact structural factors responsible for antibody recognition are not known. CPSs of Neisseria meningitidis serogroups Y and W differ by a single stereochemical center, yet they evoke specific immune responses. Herein, we developed specific monoclonal antibodies (mAbs) targeting serogroups C, Y, and W and evaluated their ability to kill bacteria. We then used these mAbs to dissect structural elements responsible for carbohydrate-protein interactions. First, Men oligosaccharides were screened against the mAbs using ELISA to select putative lengths representing the minimal antigenic determinant. Next, molecular interaction features between the mAbs and serogroup-specific sugar fragments were elucidated using STD-NMR. Moreover, X-ray diffraction data with the anti-MenW CPS mAb enabled the elucidation of the sugar-antibody binding mode. Our findings revealed common traits in the epitopes of all three sialylated serogroups. The minimal binding epitopes typically comprise five to six repeating units. Moreover, the O-acetylation of the neuraminic acid moieties was fundamental for mAb binding. These insights hold promise for the rational design of optimized meningococcal oligosaccharides, opening new avenues for novel production methods, including chemical or enzymatic approaches.
Topics: Antibodies, Monoclonal; Serogroup; Neisseria meningitidis; Meningococcal Vaccines; Polysaccharides, Bacterial; Antibodies, Bacterial; Epitopes; Animals; Mice; Humans; Bacterial Capsules; Antibody Formation
PubMed: 38876728
DOI: 10.1016/j.carbpol.2024.122349 -
Transfusion Medicine and Hemotherapy :... Jun 2024Eurotransplant established the acceptable mismatch (AM) program to facilitate timely kidney transplantations of highly sensitized patients, but long-term granular...
INTRODUCTION
Eurotransplant established the acceptable mismatch (AM) program to facilitate timely kidney transplantations of highly sensitized patients, but long-term granular clinical and immunological outcomes regarding overall graft survival and de novo DSA (dnDSA) formation are still intensively researched. The right choice of induction therapy in patients with differing immunological risk is not conclusively determined, as well as the impact of human leukocyte antigen (HLA) epitope matching on dnDSA formation.
METHODS
This monocentric, retrospective study analyzed 94 patients transplanted within the AM program between 2000 and 2019 compared to case-control matched cohorts of non- (PRA 0-5%; PRA-0) and intermediately sensitized (PRA 6-84%; PRA-6/84) patients transplanted through Eurotransplant Kidney Allocation System.
RESULTS
Estimated 10-year overall graft survival between the PRA-0 and AM cohorts was similar, whereas PRA-6/84 was significantly disadvantageous compared to PRA-0. Estimated 10-year incidence of antibody-mediated rejection rates was significantly lower in the PRA-0 group compared to AM and PRA-6/84 groups. Compared to the AM group, estimated incidence of de novo donor-specific antibody (dnDSA) was significantly lower in PRA-0 patients, with no differences between the AM and PRA-6/84 cohorts. The PRA-6/84 cohort was the only subgroup in which interleukin-2 receptor antagonist (IL2RA) induction was associated with longer overall graft survival, patient survival, and graft survival compared to depleting induction (ATG or OKT3). Broad HLA-A, -B, -DR mismatches (mmABDR) and HLA epitope mismatches determined by Eplets and PIRCHE-II were predictive for dnDSA formation in the total cohort, and the AM subgroup.
DISCUSSION
The high efforts expended on AM patients are justified to allow timely organ transplantation with acceptable risk profile and non-inferior outcomes. IL2RA induction in intermediately sensitized patients is associated with superior overall graft survival, patient survival, and graft survival compared to ATG/OKT3 induction, without negative effects on rejection episodes or dnDSA formation. In silico epitope matching might further help reduce dnDSA formation, particularly in high-risk AM patients.
PubMed: 38867807
DOI: 10.1159/000536533 -
Kidney & Blood Pressure Research Jun 2024Patients with idiopathic membranous nephropathy (IMN) are particularly susceptible to thromboembolism (TE). The phospholipase A2 receptor (PLA2R) antibody (Ab) has been...
INTRODUCTION
Patients with idiopathic membranous nephropathy (IMN) are particularly susceptible to thromboembolism (TE). The phospholipase A2 receptor (PLA2R) antibody (Ab) has been indicated to work as an independent risk predictor for venous TE in IMN. This study aims to further explore the predictive value of PLA2R Ab for both venous and arterial TE in IMN patients.
METHODS
A total of 91 IMN patients were retrospectively selected and divided into anti-PLA2R-positive or -negative groups according to the anti-PLA2R Ab titer (cutoff: 20 RU/mL). Serum PLA2R Abs were estimated using ELISA. Anti-PLA2R-positive IMN patients were further assigned into two groups based on the presence or absence of TE.
RESULTS
Twelve (18.18%) IMN patients with anti-PLA2R positivity had TE, including both venous and arterial TE. No TE occurred in the anti-PLA2R-negative group. IMN patients in the anti-PLA2R-positive group had significantly higher levels of total cholesterol and low-density lipoprotein than those in the anti-PLA2R-negative group. No significant difference was observed in the anti-PLA2R Ab titer between patients with and without TE. Patients with TE were significantly older than those without TE.
CONCLUSION
This study demonstrates that the positive status of anti-PLA2R Abs contributes to thrombosis formation in IMN.
PubMed: 38865986
DOI: 10.1159/000539437 -
Scientific Reports Jun 2024African Green (Vervet) monkeys have been extensively studied to understand the pathogenesis of infectious diseases. Using vervet monkeys as pre-clinical models may be an...
African Green (Vervet) monkeys have been extensively studied to understand the pathogenesis of infectious diseases. Using vervet monkeys as pre-clinical models may be an attractive option for low-resourced areas as they are found abundantly and their maintenance is more cost-effective than bigger primates such as rhesus macaques. We assessed the feasibility of using vervet monkeys as animal models to examine the immunogenicity of HIV envelope trimer immunogens in pre-clinical testing. Three groups of vervet monkeys were subcutaneously immunized with either the BG505 SOSIP.664 trimer, a novel subtype C SOSIP.664 trimer, CAP255, or a combination of BG505, CAP255 and CAP256.SU SOSIP.664 trimers. All groups of vervet monkeys developed robust binding antibodies by the second immunization with the peak antibody response occurring after the third immunization. Similar to binding, antibody dependent cellular phagocytosis was also observed in all the monkeys. While all animals developed potent, heterologous Tier 1 neutralizing antibody responses, autologous neutralization was limited with only half of the animals in each group developing responses to their vaccine-matched pseudovirus. These data suggest that the vervet monkey model may yield distinct antibody responses compared to other models. Further study is required to further determine the utility of this model in HIV immunization studies.
Topics: Animals; HIV Antibodies; Chlorocebus aethiops; Antibodies, Neutralizing; AIDS Vaccines; HIV-1; Antibody Formation; HIV Infections; env Gene Products, Human Immunodeficiency Virus; Disease Models, Animal; Immunization
PubMed: 38858452
DOI: 10.1038/s41598-024-63703-7 -
Human Vaccines & Immunotherapeutics Dec 2024Staphylococcal Enterotoxin B (SEB), produced by (), is a powerful superantigen that induces severe immune disruption and toxic shock syndrome (TSS) upon binding to...
Staphylococcal Enterotoxin B (SEB), produced by (), is a powerful superantigen that induces severe immune disruption and toxic shock syndrome (TSS) upon binding to MHC-II and TCR. Despite its significant impact on the pathogenesis of , there are currently no specific therapeutic interventions available to counteract the mechanism of action exerted by this toxin. In this study, we have identified a human monoclonal antibody, named Hm0487, that specifically targets SEB by single-cell sequencing using PBMCs isolated from volunteers enrolled in a phase I clinical trial of the five-antigen vaccine. X-ray crystallography studies revealed that Hm0487 exhibits high affinity for a linear B cell epitope in SEB (SEB), which is located distantly from the site involved in the formation of the MHC-SEB-TCR ternary complex. Furthermore, studies demonstrated that Hm0487 significantly impacts the interaction of SEB with both receptors and the binding to immune cells, probably due to an allosteric effect on SEB rather than competing with receptors for binding sites. Moreover, both and studies validated that Hm0487 displayed efficient neutralizing efficacy in models of lethal shock and sepsis induced by either SEB or bacterial challenge. Our findings unveil an alternative mechanism for neutralizing the pathogenesis of SEB by Hm0487, and this antibody provides a novel strategy for mitigating both SEB-induced toxicity and infection.
Topics: Enterotoxins; Humans; Antibodies, Monoclonal; Antibodies, Neutralizing; Animals; Crystallography, X-Ray; Staphylococcus aureus; Staphylococcal Infections; Epitopes, B-Lymphocyte; Mice; Shock, Septic; Female; Leukocytes, Mononuclear; Staphylococcal Vaccines; Antibodies, Bacterial; Superantigens
PubMed: 38857905
DOI: 10.1080/21645515.2024.2360338 -
Juntendo Iji Zasshi = Juntendo Medical... 2023Atherosclerosis is a chronic inflammatory disease characterized by lipid accumulation and local inflammation, which are regulated by the immune system. The immunological...
OBJECTIVES
Atherosclerosis is a chronic inflammatory disease characterized by lipid accumulation and local inflammation, which are regulated by the immune system. The immunological aspects of this disease are unclear. Immunoglobulin A regulates many cell responses through interactions with Fcα receptor type I (FcαRI). Anti-FcαRI antibody inhibits activating receptors by inducing an inhibitory immunoreceptor tyrosine-based activation motif configuration. However, the role of FcαRI in atherosclerosis development is unclear. Here, we investigated the utility of FcαRI targeting to induce inhibitory immunoreceptor tyrosine-based activation motif signaling in atherosclerosis treatment.
MATERIALS
ApoE transgenic mice expressing the FcαRIR209L/FcRγ chimeric protein (FcαRIR209L/FcRγApoE mice) were generated. We prepared an FcαRIR209L/FcRγ transfectant (I3D) from a mouse macrophage cell line (RAW264.7).
METHODS
Anti-FcαRI or control antibody was used to investigate a high-fat-diet-induced FcαRIR209L/FcRγApoE mouse model of atherosclerosis. The antibody was also used to assess macrophage foam cell formation via Oil Red O staining and mitogen-activated protein kinase signaling via immunoblotting in the FcαRIR209L/FcRγ-expressing RAW264.7 macrophage cell line I3D.
RESULTS
Targeting of monovalent FcαRI induced inhibitory effects in the FcαRIR209L/FcRγApoE mouse model of atherosclerosis by inhibiting macrophage infiltration. FcαRI targeting using the anti-FcαRI antibody also reduced mitogen-activated protein kinase signaling and foam cell formation, leading to decreased interleukin (IL)-1b and monocyte chemoattractant protein (MCP)-1.
CONCLUSIONS
We demonstrated that targeting monovalent FcαRI suppresses atherosclerosis development. These findings can support the future clinical exploration of FcαRI targeting for atherosclerosis treatment.
PubMed: 38855431
DOI: 10.14789/jmj.JMJ23-0003-OA -
Theranostics 2024Myocardial infarction (MI) as a consequence of atherosclerosis-associated acute thrombosis is a leading cause of death and disability globally. Antiplatelet and...
Platelet-targeted thromboprophylaxis with a human serum albumin fusion drug: Preventing thrombosis and reducing cardiac ischemia/reperfusion injurywithout bleeding complications.
Myocardial infarction (MI) as a consequence of atherosclerosis-associated acute thrombosis is a leading cause of death and disability globally. Antiplatelet and anticoagulant drugs are standard therapies in preventing and treating MI. However, all clinically used drugs are associated with bleeding complications, which ultimately limits their use in patients with a high risk of bleeding. We have developed a new recombinant drug, targ-HSA-TAP, that combines targeting and specific inhibition of activated platelets as well as anticoagulation. This drug is designed and tested for a prolonged circulating half-life, enabling unique thromboprophylaxis without bleeding complications. Targ-HSA-TAP combines a single-chain antibody (scFv) that targets activated glycoprotein IIb/IIIa on activated platelets, human serum albumin (HSA) for prolonged circulation, and tick anticoagulant peptide (TAP) for coagulation FX inhibition. A non-binding scFv is employed as a non-targeting control (non-targ-HSA-TAP). Its efficacy was investigated using murine models of acute thrombosis and cardiac ischemia-reperfusion (I/R) injury. Our experiments confirmed the targeting specificity of targ-HSA-TAP to activated platelets and demonstrated effective prevention of platelet aggregation and thrombus formation, as well as FXa inhibition . Thromboprophylactic administration of targ-HSA-TAP subcutaneously in mice prevented occlusion of the carotid artery after ferric chloride injury as compared to non-targ-HSA-TAP and PBS-control treated mice. By comparing the therapeutic outcomes between targ-TAP and targ-HSA-TAP, we demonstrate the significant improvements brought by the HSA fusion in extending the drug's half-life and enhancing its therapeutic window for up to 16 h post-administration. Importantly, tail bleeding time was not prolonged with targ-HSA-TAP in contrast to the clinically used anticoagulant enoxaparin. Furthermore, in a murine model of cardiac I/R injury, mice administered targ-HSA-TAP 10 h before injury demonstrated preserved cardiac function, with significantly higher ejection fraction and fractional shortening, as compared to the non-targ-HSA-TAP and PBS control groups. Advanced strain analysis revealed reduced myocardial deformation and histology confirmed a reduced infarct size in targ-HSA-TAP treated mice compared to control groups. The inclusion of HSA represents a significant advancement in the design of targeted therapeutic agents for thromboprophylaxis. Our activated platelet-targeted targ-HSA-TAP is a highly effective antithrombotic drug with both anticoagulant and antiplatelet effects while retaining normal hemostasis. The long half-life of targ-HSA-TAP provides the unique opportunity to use this antithrombotic drug for more effective, long-lasting and safer anti-thrombotic prophylaxis. In cases where MI occurs, this prophylactic strategy reduces thrombus burden and effectively reduces cardiac I/R injury.
Topics: Animals; Serum Albumin, Human; Mice; Thrombosis; Humans; Hemorrhage; Blood Platelets; Disease Models, Animal; Male; Anticoagulants; Single-Chain Antibodies; Myocardial Reperfusion Injury; Myocardial Infarction; Mice, Inbred C57BL; Recombinant Fusion Proteins
PubMed: 38855181
DOI: 10.7150/thno.97517 -
Frontiers in Immunology 2024Antibody production and the generation of memory B cells are regulated by T follicular helper (Tfh) and T follicular regulatory (Tfr) cells in germinal centers. However,...
INTRODUCTION
Antibody production and the generation of memory B cells are regulated by T follicular helper (Tfh) and T follicular regulatory (Tfr) cells in germinal centers. However, the precise role of Tfr cells in controlling antibody production is still unclear. We have previously shown that both Tfh and Tfr cells express the IL-1R1 agonist receptor, whereas only Tfr cells express the IL-1R2 decoy and IL-1Ra antagonist receptors. We aimed to investigate the role of IL-1 receptors in the regulation of B cell responses by Tfh and Tfr.
METHODS
We generated mice with IL-1 receptors inactivated in Tfh or Tfr and measured antibody production and cell activation after immunisation.
RESULTS
While IL-1β levels are increased in the draining lymph node after immunisation, antigen-specific antibody levels and cell phenotypes indicated that IL-1β can activate both Tfh and Tfr cells through IL-1R1 stimulation. Surprisingly, expression of IL-1R2 and IL-1Ra on Tfr cells does not block IL-1 activation of Tfh cells, but rather prevents IL-1/IL-1R1-mediated early activation of Tfr cells. IL-1Rs also regulate the antibody response to autoantigens and its associated pathophysiology in an experimental lupus model.
DISCUSSION
Collectively, our results show that IL-1 inhibitory receptors expressed by Tfr cells prevent their own activation and suppressive function, thus licensing IL-1-mediated activation of Tfh cells after immunisation. Further mechanistic studies should unravel these complex interactions between IL-1β and follicular helper and regulatory T cells and provide new avenues for therapeutic intervention.
Topics: Animals; Germinal Center; Mice; T Follicular Helper Cells; T-Lymphocytes, Regulatory; Lymphocyte Activation; Receptors, Interleukin-1 Type I; Mice, Inbred C57BL; B-Lymphocytes; Interleukin-1beta; Interleukin-1; Receptors, Interleukin-1; Antibody Formation
PubMed: 38855101
DOI: 10.3389/fimmu.2024.1393096 -
Mucosal Immunology Jun 2024Influenza A virus (IAV) infection leads to the formation of mucosal memory CD4 T cells that can protect the host. An in-depth understanding of the signals that shape...
Influenza A virus (IAV) infection leads to the formation of mucosal memory CD4 T cells that can protect the host. An in-depth understanding of the signals that shape memory cell development is required for more effective vaccine design. We have examined the formation of memory CD4 T cells in the lung following IAV infection of mice, characterizing changes to the lung landscape and immune cell composition. IAV-specific CD4 T cells were found throughout the lung at both primary and memory time points. These cells were found near lung airways and in close contact with a range of immune cells including macrophages, dendritic cells, and B cells. Interactions between lung IAV-specific CD4 T cells and major histocompatibility complex (MHC)II+ cells during the primary immune response were important in shaping the subsequent memory pool. Treatment with an anti-MHCII blocking antibody increased the proportion of memory CD4 T cells found in lung airways but reduced interferon-γ expression by IAV-specific immunodominant memory CD4 T cells. The immunodominant CD4 T cells expressed higher levels of programmed death ligand 1 (PD1) than other IAV-specific CD4 T cells and PD1+ memory CD4 T cells were located further away from MHCII+ cells than their PD1-low counterparts. This distinction in location was lost in mice treated with anti-MHCII antibodies. These data suggest that sustained antigen presentation in the lung impacts the formation of memory CD4 T cells by regulating their cytokine production and location.
PubMed: 38851589
DOI: 10.1016/j.mucimm.2024.06.001 -
Nature Communications Jun 2024Reticulocyte-binding protein homologue 5 (RH5), a leading blood-stage Plasmodium falciparum malaria vaccine target, interacts with cysteine-rich protective antigen...
Reticulocyte-binding protein homologue 5 (RH5), a leading blood-stage Plasmodium falciparum malaria vaccine target, interacts with cysteine-rich protective antigen (CyRPA) and RH5-interacting protein (RIPR) to form an essential heterotrimeric "RCR-complex". We investigate whether RCR-complex vaccination can improve upon RH5 alone. Using monoclonal antibodies (mAbs) we show that parasite growth-inhibitory epitopes on each antigen are surface-exposed on the RCR-complex and that mAb pairs targeting different antigens can function additively or synergistically. However, immunisation of female rats with the RCR-complex fails to outperform RH5 alone due to immuno-dominance of RIPR coupled with inferior potency of anti-RIPR polyclonal IgG. We identify that all growth-inhibitory antibody epitopes of RIPR cluster within the C-terminal EGF-like domains and that a fusion of these domains to CyRPA, called "R78C", combined with RH5, improves the level of in vitro parasite growth inhibition compared to RH5 alone. These preclinical data justify the advancement of the RH5.1 + R78C/Matrix-M™ vaccine candidate to Phase 1 clinical trial.
Topics: Malaria Vaccines; Animals; Plasmodium falciparum; Protozoan Proteins; Female; Malaria, Falciparum; Antigens, Protozoan; Rats; Antibodies, Protozoan; Antibodies, Monoclonal; Humans; Epitopes; Carrier Proteins
PubMed: 38849365
DOI: 10.1038/s41467-024-48721-3