Project description:While the induction of a neutralizing antibody response against HIV remains a daunting goal, data from both natural infection and vaccine-induced immune responses suggest that it may be possible to induce antibodies with enhanced Fc effector activity and improved antiviral control via vaccination. However, the specific features of naturally induced HIV-specific antibodies that allow for the potent recruitment of antiviral activity and the means by which these functions are regulated are poorly defined. Because antibody effector functions are critically dependent on antibody Fc domain glycosylation, we aimed to define the natural glycoforms associated with robust Fc-mediated antiviral activity. We demonstrate that spontaneous control of HIV and improved antiviral activity are associated with a dramatic shift in the global antibody-glycosylation profile toward agalactosylated glycoforms. HIV-specific antibodies exhibited an even greater frequency of agalactosylated, afucosylated, and asialylated glycans. These glycoforms were associated with enhanced Fc-mediated reduction of viral replication and enhanced Fc receptor binding and were consistent with transcriptional profiling of glycosyltransferases in peripheral B cells. These data suggest that B cell programs tune antibody glycosylation actively in an antigen-specific manner, potentially contributing to antiviral control during HIV infection.
Project description:Agonistic anti-TNF receptor (TNFR) superfamily member antibodies are a class of promising antitumor therapies in active clinical investigation. An unexpected requirement for inhibitory Fc? receptor Fc?RIIB coengagement has recently been described for their in vivo antitumor activities. Although these findings have informed the design of more potent antitumor agonistic, anti-TNFR therapies, the underlying mechanism has remained obscure. Through detailed genetic analysis of strains conditionally deleted for Fc?RIIB on defined cellular populations or mutated in specific signaling components, we now demonstrate that different agonistic anti-TNFR antibodies have specific requirements for Fc?RIIB expression on defined cellular populations and function in trans in the absence of Fc?RIIB signaling components, thus supporting a general mechanism of Fc?RIIB cross-linking in vivo for the activities of these antibodies.
Project description:Conjugate vaccine against typhoid fever has been shown to be safe and effective in field trials. The mechanism through which the vaccine protects remains elusive. Recent data have implicated antibody glycosylation, and specifically afucosylated antibodies, as an important factor in vaccine-induced effector function for a range of viral infections. Here, we studied IgG glycosylation after conjugate vaccine in a UK cohort, who were then challenged with virulent S.typhi, and among Nepalese children living in a typhoid endemic region. We compared vaccine-induced responses to another licensed typhoid polysaccharide vaccine and correlated these measures with antibody-dependent function to understand if a vaccine against a bacterial infection elicited similar glycosylation/function associations as has been seen for viral infections. Robust antigen-specific IgG Fc galactosylation and sialylation modifications were induced by both polysaccharide and tetanus toxoid-conjugated Salmonella Typhi vaccines in UK adults. These modifications were not able to differentiate controlled human infection model (CHIM) participants who became ill after ingestion of virulent S.typhi from those who remained well after infection. However, among those who did become ill, disease severity was associated with a distinct glycosylation profile. Interestingly, both vaccines induced vaccine-specific IgG1 antibodies that were more fucosylated than total circulating IgG1 and these were not associated with a particular functional profile. While bulk IgG glycosylation was different between Nepalese children and UK adults, vaccination with the Vi-tetanus toxoid-conjugate vaccine resulted in similar Vi-specific IgG glycosylation profiles 28 days after vaccination in both cohorts.
Project description:Immunostimulatory receptors belonging to the tumor necrosis factor receptor (TNFR) superfamily are emerging as promising targets for cancer immunotherapies. To optimize the agonism of therapeutic antibodies to these receptors, Fc engineering of antibodies was applied to facilitate the clustering of cell surface TNFRs to activate downstream signaling pathways. One engineering strategy is to identify Fc mutations that facilitate antibody multimerization on the cell surface directly. From the analyses of the crystal packing of IgG1 structures, we identified a novel set of Fc mutations, T437R and K248E, that facilitated antibody multimerization upon binding to antigens on cell surface. In a NF-κB reporter assay, the engineered T437R/K248E mutations could facilitate enhanced agonism of an anti-OX40 antibody without the dependence on FcγRIIB crosslinking. Nonetheless, the presence of cells expressing FcγRIIB could facilitate a boost of the agonism of the engineered antibody with mutations on IgG1 Fc, but not on the silent IgG2σ Fc. The Fc engineered antibody also showed enhanced effector functions, including antibody-dependent cell-meditated cytotoxicity, antibody-dependent cellular phagocytosis, and complement-dependent cytotoxicity, depending on the IgG subtypes. Also, the engineered antibodies showed normal FcRn binding and pharmacokinetic profiles in mice. In summary, this study elucidated a novel Fc engineering approach to promote antibody multimerization on a cell surface, which could enhance agonism and improve effector function for anti-TNFR antibodies as well as other therapeutic antibodies.
Project description:The CD200 receptor (CD200R) is present mainly on myeloid cells and gives inhibitory signals when engaged by its ligand CD200. The interaction is currently of therapeutic interest in cancer and inflammation. However functional effects are complicated by the fact that CD200R is itself polymorphic and also a member of a paired receptor family with four closely related gene products in mice called CD200RLa etc. We show that a second allele of CD200R (termed CD200R(2)) that differs in 7 amino acids also binds CD200 but did not react with the widely used CD200R antibody OX110. Biochemical and functional analysis showed that the CD200/CD200R interaction was blocked by the OX131, mAb that recognises both CD200R(1) and CD200R(2), but not by OX110 mAb. Both mAb can give agonistic inhibitory signals but functional analysis shows OX131 mAb also has the potential to block inhibition by preventing the ligand-receptor interaction and hence gives opposing effects. Although OX131 mAb cross-reacts with the activating receptor CD200RLe, it is specific for CD200R in C57BL/6 whilst OX110 mAb cross-reacts on CD200RLc. The results show the importance of the repertoire of paired receptors in strains or individuals and mAb used with implications for paired receptor analysis and therapeutics.
Project description:While engagement of the inhibitory Fcγ-receptor (FcγR) IIB is an absolute requirement for in vivo antitumor activity of agonistic mouse anti-CD40 monoclonal antibodies (mAbs), a similar requirement for human mAbs has been disputed. By using a mouse model humanized for its FcγRs and CD40, we revealed that FcγRIIB engagement is essential for the activity of human CD40 mAbs, while engagement of the activating FcγRIIA inhibits this activity. By engineering Fc variants with selective enhanced binding to FcγRIIB, but not to FcγRIIA, significantly improved antitumor immunity was observed. These findings highlight the necessity of optimizing the Fc domain for this class of therapeutic antibodies by using appropriate preclinical models that accurately reflect the unique affinities and cellular expression of human FcγR.
Project description:OX40 (CD134) is a costimulatory molecule of the tumor necrosis factor receptor superfamily that is currently being investigated as a target for cancer immunotherapy. However, despite promising results in murine tumor models, the clinical efficacy of agonistic αOX40 antibodies in the treatment of patients with cancer has fallen short of the high expectation in earlier-stage trials. Using lymphocytes from resected tumor, tumor-free (TF) tissue and peripheral blood mononuclear cells (PBMC) of 96 patients with hepatocellular and colorectal cancers, we determined OX40 expression and the in vitro T-cell agonistic activity of OX40-targeting compounds. RNA-Seq was used to evaluate OX40-mediated transcriptional changes in CD4+ and CD8+ human tumor-infiltrating lymphocytes (TILs). Here, we show that OX40 was overexpressed on tumor-infiltrating CD4+ T cells compared with blood and TF tissue-derived T cells. In contrast to a clinical candidate αOX40 antibody, treatment with an Fc-engineered αOX40 antibody (αOX40_v12) with selectively enhanced FcγRIIB affinity, stimulated in vitro CD4+ and CD8+ TIL expansion, as well as cytokine and chemokine secretions. The activity of αOX40_v12 was dependent on FcγRIIB engagement and intrinsic CD3/CD28 signals. The transcriptional landscape of CD4+ and CD8+ TILs shifted toward a prosurvival, inflammatory and chemotactic profile on treatment with αOX40_v12. OX40 is overexpressed on CD4+ TILs and thus represents a promising target for immunotherapy. Targeting OX40 with currently used agonistic antibodies may be inefficient due to lack of OX40 multimerization. Thus, Fc engineering is a powerful tool in enhancing the agonistic activity of αOX40 antibody and may shape the future design of antibody-mediated αOX40 immunotherapy.
Project description:CD40 is expressed on a variety of antigen-presenting cells. Stimulation of CD40 results in inflammation by upregulation of other costimulatory molecules, increased antigen presentation, maturation (licensing) of dendritic cells, and activation of CD8+ T cells. Here we analyzed gene expression data from The Cancer Genome Atlas in melanoma, renal cell carcinoma, and pancreatic adenocarcinoma and found correlations between CD40 and several genes involved in antigen presentation and T cell function, supporting further exploration of CD40 agonists to treat cancer. Agonist CD40 antibodies have induced anti-tumor effects in several tumor models and the effect has been more pronounced when used in combination with other treatments (immune checkpoint inhibition, chemotherapy, and colony-stimulating factor 1 receptor inhibition). The reduction in tumor growth and ability to reprogram the tumor microenvironment in preclinical models lays the foundation for clinical development of agonistic CD40 antibodies (APX005M, ChiLob7/4, ADC-1013, SEA-CD40, selicrelumab, and CDX-1140) that are currently being evaluated in early phase clinical trials. In this article, we focus on CD40 expression and immunity in cancer, agonistic human CD40 antibodies, and their pre-clinical and clinical development. With the broad pro-inflammatory effects of CD40 and its ligand on dendritic cells and macrophages, and downstream B and T cell activation, agonists of this pathway may enhance the anti-tumor activity of other systemic therapies.
Project description:Background: OX40 (CD134) is a co-stimulatory molecule of the tumor necrosis factor receptor (TNFR) superfamily, that is currently investigated as a target for cancer immunotherapy. However, despite promising results in murine tumor models, the clinical efficacy of agonistic αOX40 antibodies in treatment of cancer patients has fallen short of the high expectation in earlier stage trials. Methods: Using lymphocytes from resected tumor, tumor-free tissue and PBMC of 4 hepatocellular and colorectal cancer patients, we performed RNA-Seq to evaluate OX40-mediated transcriptional changes in CD4+ and CD8+ human tumor-infiltrating lymphocytes (TILs). Results: The transcriptional landscape of CD4+ and CD8+ TILs shifted towards a pro-survival, inflammatory and chemotactic profile upon treatment with αOX40_v12.
Project description:Antibodies may bind to bacterial pathogens or their toxins to control infections, and their effector activity is mediated through the recruitment of complement component C1q or the engagement with Fcγ receptors (FcγRs). For bacterial pathogens that rely on a single toxin to cause disease, immunity correlates with toxin neutralization. Most other bacterial pathogens, including Staphylococcus aureus, secrete numerous toxins and evolved multiple mechanisms to escape opsonization and complement killing. Several vaccine candidates targeting defined surface antigens of S. aureus have failed to meet clinical endpoints. It is unclear that such failures can be solely attributed to the poor selection of antibody targets. Thus far, studies to delineate antibody-mediated uptake and killing of Gram-positive pathogens remain extremely limited. Here, we exploit 3F6-hIgG1, a human monoclonal antibody that binds and neutralizes the abundant surface-exposed Staphylococcal protein A (SpA). We find that galactosylation of 3F6-hIgG1 that favors C1q recruitment is indispensable for opsonophagocytic killing of staphylococci and for protection against bloodstream infection in animals. However, the simple removal of fucosyl residues, which results in reduced C1q binding and increased engagement with FcγR, maintains the opsonophagocytic killing and protective attributes of the antibody. We confirm these results by engineering 3F6-hIgG1 variants with biased binding toward C1q or FcγRs. While the therapeutic benefit of monoclonal antibodies against infectious disease agents may be debatable, the functional characterization of such antibodies represents a powerful tool for the development of correlates of protection that may guide future vaccine trials.