DNA and modified vaccinia Ankara prime-boost vaccination generates strong CD8+ T cell responses against minor histocompatibility antigen HA-1

Allogeneic immune responses underlie the graft-versus-leukaemia effect of stem cell transplantation, but disease relapse occurs in many patients. Minor histocompatibility antigen (mHAg) peptides mediate alloreactive T cell responses and induce graft-versus-leukaemia responses when expressed on patient haematopoietic tissue. We vaccinated nine HA-1-negative donors against HA-1 with a 'prime-boost' protocol of either two or three DNA 'priming' vaccinations prior to 'boost' with modified vaccinia Ankara (MVA). HA-1-specific CD8+ T cell responses were observed in seven donors with magnitude up to 1·5% of total CD8+ T cell repertoire. HA-1-specific responses peaked two weeks post-MVA challenge and were measurable in most donors after 12 months. HA-1-specific T cells demonstrated strong cytotoxic activity and lysed target cells with endogenous HA-1 protein expression. The pattern of T cell receptor (TCR) usage by HA-1-specific T cells revealed strong conservation of T cell receptor beta variable 7-9 (TRBV7-9) usage between donors. These findings describe one of the strongest primary peptide-specific CD8+ T cell responses yet recorded to a DNA-MVA prime-boost regimen and this may reflect the strong immunogenicity of mHAg peptides. Prime-boost vaccination in donors or patients may prove of substantial benefit in boosting graft-versus-leukaemia responses.

Substrates Modulate Charge-Reorganization Allosteric Effects in Protein-Protein Association

Protein function may be modulated by an event occurring far away from the functional site, a phenomenon termed allostery. While classically allostery involves conformational changes, we recently observed that charge redistribution within an antibody can also lead to an allosteric effect, modulating the kinetics of binding to target antigen. In the present work, we study the association of a polyhistidine tagged enzyme (phosphoglycerate kinase, PGK) to surface-immobilized anti-His antibodies, finding a significant Charge-Reorganization Allostery (CRA) effect. We further observe that PGK's negatively charged nucleotide substrates modulate CRA substantially, even though they bind far away from the His-tag-antibody interaction interface. In particular, binding of ATP reduces CRA by more than 50%. The results indicate that CRA is affected by the binding of charged molecules to a protein and provide further insight into the significant role that charge redistribution can play in protein function.

Preclinical optimization of Ly6E-targeted ADCs for increased durability and efficacy of anti-tumor response

Early success with brentuximab vedotin in treating classical Hodgkin lymphoma spurred an influx of at least 20 monomethyl auristatin E (MMAE) antibody-drug conjugates (ADCs) into clinical trials. While three MMAE-ADCs have been approved, most of these conjugates are no longer being investigated in clinical trials. Some auristatin conjugates show limited or no efficacy at tolerated doses, but even for drugs driving initial remissions, tumor regrowth and metastasis often rapidly occur. Here we describe the development of second-generation therapeutic ADCs targeting Lymphocyte antigen 6E (Ly6E) where the tubulin polymerization inhibitor MMAE (Compound 1) is replaced with DNA-damaging agents intended to drive increased durability of response. Comparison of a seco-cyclopropyl benzoindol-4-one (CBI)-dimer (compound 2) to MMAE showed increased potency, activity across more cell lines, and resistance to efflux by P-glycoprotein, a drug transporter commonly upregulated in tumors. Both anti-Ly6E-CBI and -MMAE conjugates drove single-dose efficacy in xenograft and patient-derived xenograft models, but seco-CBI-dimer conjugates showed reduced tumor outgrowth following multiple weeks of treatment, suggesting that they are less susceptible to developing resistance. In parallel, we explored approaches to optimize the targeting antibody. In contrast to immunization with recombinant Ly6E or Ly6E DNA, immunization with virus-like particles generated a high-affinity anti-Ly6E antibody. Conjugates to this antibody improve efficacy versus a previous clinical candidate both in vitro and in vivo with multiple cytotoxics. Conjugation of compound 2 to the second-generation antibody results in a substantially improved ADC with promising preclinical efficacy.

Polydisperse molecular architecture of connexin 26/30 heteromeric hemichannels revealed by atomic force microscopy imaging

Connexin (Cx) protein forms hemichannels and gap junctional channels, which play diverse and profound roles in human physiology and diseases. Gap junctions are arrays of intercellular channels formed by the docking of two hemichannels from adjacent cells. Each hexameric hemichannel contains the same or different Cx isoform. Although homomeric Cxs forms have been largely described functionally and structurally, the stoichiometry and arrangement of heteromeric Cx channels remain unknown. The latter, however, are widely expressed in human tissues and variation might have important implications on channel function. Investigating properties of heteromeric Cx channels is challenging considering the high number of potential subunit arrangements and stoichiometries, even when only combining two Cx isoforms. To tackle this problem, we engineered an HA tag onto Cx26 or Cx30 subunits and imaged hemichannels that were liganded by Fab-epitope antibody fragments via atomic force microscopy. For Cx26-HA/Cx30 or Cx30-HA/Cx26 heteromeric channels, the Fab-HA binding distribution was binomial with a maximum of three Fab-HA bound. Furthermore, imaged Cx26/Cx30-HA triple liganded by Fab-HA showed multiple arrangements that can be derived from the law of total probabilities. Atomic force microscopy imaging of ringlike structures of Cx26/Cx30-HA hemichannels confirmed these findings and also detected a polydisperse distribution of stoichiometries. Our results indicate a dominant subunit stoichiometry of 3Cx26:3Cx30 with the most abundant subunit arrangement of Cx26-Cx26-Cx30-Cx26-Cx30-Cx30. To our knowledge, this is the first time that the molecular architecture of heteromeric Cx channels has been revealed, thus providing the basis to explore the functional effect of these channels in biology.

RGD- and VEGF-Mimetic Peptide Epitope-Functionalized Self-Assembling Peptide Hydrogels Promote Dentin-Pulp Complex Regeneration

INTRODUCTION

Cell-based tissue engineering is a promising method for dentin-pulp complex (DPC) regeneration. The challenges associated with DPC regeneration include the generation of a suitable microenvironment that facilitates the complete odontogenic differentiation of dental pulp stem cells (DPSCs) and the rapid induction of angiogenesis. Thus, the survival and subsequent differentiation of DPSCs are limited. Extracellular matrix (ECM)-like biomimetic hydrogels composed of self-assembling peptides (SAPs) were developed to provide an appropriate microenvironment for DPSCs. For functional DPC regeneration, the most important considerations are to provide an environment that promotes the adequate attachment of DPSCs and rapid vascularization of the regenerating pulp. Morphogenic signals in the form of growth factors (GFs) have been incorporated into SAPs to promote productive DPSC behaviors. However, the use of GFs has several drawbacks. We envision using a scaffold with SAPs coupled with long-term factors to increase DPSC attachment and vascularization as a method to address this challenge.

METHODS

In this study, we developed synthetic material for an SAP-based scaffold with RGD- and vascular endothelial growth factor (VEGF)-mimetic peptide epitopes with the dual functions of dentin and pulp regeneration. DPSCs and human umbilical vein endothelial cells (HUVECs) were used to evaluate the biological effects of SAP-based scaffolds. Furthermore, the pulpotomized molar rat model was employed to test the reparative and regenerative effects of SAP-based scaffolds.

RESULTS

This scaffold simultaneously presented RGD- and VEGF-mimetic peptide epitopes and provided a 3D microenvironment for DPSCs. DPSCs grown on this composite scaffold exhibited significantly improved survival and angiogenic and odontogenic differentiation in the multifunctionalized group in vitro. Histological and functional evaluations of a partially pulpotomized rat model revealed that the multifunctionalized scaffold was superior to other options with respect to stimulating pulp recovery and dentin regeneration in vivo.

CONCLUSION

Based on our data obtained with the functionalized SAP scaffold, a 3D microenvironment that supports stem cell adhesion and angiogenesis was generated that has great potential for dental pulp tissue engineering and regeneration.

Protocol for Immuno-Enrichment of FLAG-Tagged Protein Complexes

This protocol describes immunoprecipitation of proteins associated with FLAG-tagged recombinant proteins followed by mass spectrometry-based proteomics to identify the associated interactome components. FLAG epitope was chosen, because existing high-affinity monoclonal antibodies allow for sensitive immunoprecipitation and FLAG peptides permit efficient elution of protein complexes. With many commercially available FLAG tools, this protocol is highly versatile. This procedure reduces immunoprecipitation of nonspecific binding proteins. Gene ontology analyses performed following mass spectrometry-based proteomics may elucidate novel functions of proteins of interest. For complete details on the use and application of this protocol, please refer to Valdez-Sinon et al. (2020).

Self-assembling peptide hydrogels functionalized with LN- and BDNF- mimicking epitopes synergistically enhance peripheral nerve regeneration

The regenerative capacity of the peripheral nervous system is closely related to the role that Schwann cells (SCs) play in construction of the basement membrane containing multiple extracellular matrix proteins and secretion of neurotrophic factors, including laminin (LN) and brain-derived neurotrophic factor (BDNF). Here, we developed a self-assembling peptide (SAP) nanofiber hydrogel based on self-assembling backbone Ac-(RADA)4-NH2 (RAD) dual-functionalized with laminin-derived motif IKVAV (IKV) and a BDNF-mimetic peptide epitope RGIDKRHWNSQ (RGI) for peripheral nerve regeneration, with the hydrogel providing a three-dimensional (3D) microenvironment for SCs and neurites. Methods: Circular dichroism (CD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to characterize the secondary structures, microscopic structures, and morphologies of self-assembling nanofiber hydrogels. Then the SC adhesion, myelination and neurotrophin secretion were evaluated on the hydrogels. Finally, the SAP hydrogels were injected into hollow chitosan tubes to bridge a 10-mm-long sciatic nerve defect in rats, and in vivo gene expression at 1 week, axonal regeneration, target muscular re-innervation, and functional recovery at 12 weeks were assessed. Results: The bioactive peptide motifs were covalently linked to the C-terminal of the self-assembling peptide and the functionalized peptides could form well-defined nanofibrous hydrogels capable of providing a 3D microenvironment similar to native extracellular matrix. SCs displayed improved cell adhesion on hydrogels with both IKV and RGI, accompanied by increased cell spreading and elongation relative to other groups. RSCs cultured on hydrogels with IKV and RGI showed enhanced gene expression of NGF, BDNF, CNTF, PMP22 and NRP2, and decreased gene expression of NCAM compared with those cultured on other three groups after a 7-day incubation. Additionally, the secretion of NGF, BDNF, and CNTF of RSCs was significantly improved on dual-functionalized peptide hydrogels after 3 days. At 1 week after implantation, the expressions of neurotrophin and myelin-related genes in the nerve grafts in SAP and Autograft groups were higher than that in Hollow group, and the expression of S100 in groups containing both IKV and RGI was significantly higher than that in groups containing either IKV or RGI hydrogels, suggesting enhanced SC proliferation. The morphometric parameters of the regenerated nerves, their electrophysiological performance, the innervated muscle weight and remodeling of muscle fibers, and motor function showed that RAD/IKV/RGI and RAD/IKV-GG-RGI hydrogels could markedly improve axonal regeneration with enhanced re-myelination and motor functional recovery through the synergetic effect of IKV and RGI functional motifs. Conclusions: We found that the dual-functionalized SAP hydrogels promoted RSC adhesion, myelination, and neurotrophin secretion in vitro and successfully bridged a 10-mm gap representing a sciatic nerve defect in rats in vivo. The results demonstrated the synergistic effect of IKVAV and RGI on axonal regrowth and function recovery after peripheral nerve injury.

Synthesis and Biological Evaluation of Hapten-Clicked Analogues of The Antigenic Peptide Melan-A/MART-126(27L)-35

A click-chemistry-based approach was implemented to prepare peptidomimetics designed in silico and made from aromatic azides and a propargylated GIGI-mimicking platform derived from the altered Melan-A/MART-126(27L)-35 antigenic peptide ELAGIGILTV. The CuI -catalyzed Huisgen cycloaddition was carried out on solid support to generate rapidly a first series of peptidomimetics, which were evaluated for their capacity to dock at the interface between the major histocompatibility complex class-I (MHC-I) human leucocyte antigen (HLA)-A2 and T-cell receptors (TCRs). Despite being a weak HLA-A2 ligand, one of these 11 first synthetic compounds bearing a p-nitrobenzyl-triazole side chain was recognized by the receptor proteins of Melan-A/MART-1-specific T-cells. After modification of the N and C termini of this agonist, which was intended to enhance HLA-A2 binding, one of the resulting seven additional compounds triggered significant T-cell responses. Thus, these results highlight the capacity of naturally circulating human TCRs that are specific for the native Melan-A/MART-126-35 peptide to cross-react with peptidomimetics bearing organic motifs structurally different from the native central amino acids.

Enfortumab Vedotin, a fully human monoclonal antibody against Nectin 4 conjugated to monomethyl auristatin E for metastatic urothelial Carcinoma

Introduction: The conventional management of most patients with metastatic urothelial carcinoma (UC) is platinum-based chemotherapy followed by immunotherapy. Erdafitinib is an option in post-platinum patients with activating mutations in fibroblast growth factor receptor (FGFR)-3 and -2. Salvage therapy with taxanes or vinflunine has demonstrated minimal efficacy. Enfortumab Vedotin (EV), a monoclonal antibody-drug conjugate (ADC) targeting nectin-4 is under investigation in patients with advanced UC. Areas covered: This review describes the epidemiology and unmet needs of patients with metastatic UC and is focused specifically on heavily treated patients. We explore the rationale for targeting nectin 4 and the clinical development of EV; efficacy and safety data from the completed phase I and II studies are examined. Ongoing trials to definitively assess clinical outcomes in comparison to current therapy and trials exploring EV in combination are also highlighted. Expert opinion: There is an unmet need for new therapies in most patients with advanced UC and who progress after platinum and immunotherapy. EV has shown promising efficacy and safety in this population in phase 1 and 2 trials including those with poor prognostic factors such as liver metastases. Ongoing trials exploring this agent in combination will continue to advance the treatment of UC.

Next-generation of targeted AAVP vectors for systemic transgene delivery against cancer

Bacteriophage (phage) have attractive advantages as delivery systems compared with mammalian viruses, but have been considered poor vectors because they lack evolved strategies to confront and overcome mammalian cell barriers to infective agents. We reasoned that improved efficacy of delivery might be achieved through structural modification of the viral capsid to avoid pre- and postinternalization barriers to mammalian cell transduction. We generated multifunctional hybrid adeno-associated virus/phage (AAVP) particles to enable simultaneous display of targeting ligands on the phage's minor pIII proteins and also degradation-resistance motifs on the very numerous pVIII coat proteins. This genetic strategy of directed evolution bestows a next-generation of AAVP particles that feature resistance to fibrinogen adsorption or neutralizing antibodies and ability to escape endolysosomal degradation. This results in superior gene transfer efficacy in vitro and also in preclinical mouse models of rodent and human solid tumors. Thus, the unique functions of our next-generation AAVP particles enable improved targeted gene delivery to tumor cells.

The Use of Combinatorial Hexapeptide Ligand Library (CPLL) in Allergomics

The recent progress of proteomic protocols led to more efficient protein extraction and concentration procedures to remove nonprotein interfering compounds present in the starting material and to increase the concentration of underrepresented proteins. Combinatorial hexapeptide ligand libraries (CPLL) were recently applied to both plant- and animal-derived tissues for capturing the low- and very low-abundance allergens. Several IgE-binding proteins which were previously absent or poorly represented by using conventional proteomics tools have been detected and characterized through a CPLL-based approach. In the present chapter, a protocol based on improved protein extraction and enrichment by CPLL, allowing the immunochemical characterization of several "hidden allergens" in cypress pollen, is described in detail.

Level of neo-epitope predecessor and mutation type determine T cell activation of MHC binding peptides

BACKGROUND

Targeting epitopes derived from neo-antigens (or "neo-epitopes") represents a promising immunotherapy approach with limited off-target effects. However, most peptides predicted using MHC binding prediction algorithms do not induce a CD8 + T cell response, and there is a crucial need to refine the predictions to readily identify the best antigens that could mediate T-cell responses. Such a response requires a high enough number of epitopes bound to the target MHC. This number is correlated with both the peptide-MHC binding affinity and the number of peptides reaching the ER. Beyond this, the response may be affected by the properties of the neo-epitope mutated residues.

METHODS

Herein, we analyzed several experimental datasets from cancer patients to elaborate better predictive algorithms for T-cell reactivity to neo-epitopes.

RESULTS

Indeed, potent classifiers for epitopes derived from neo-antigens in melanoma and other tumors can be developed based on biochemical properties of the mutated residue, the antigen expression level and the peptide processing stage. Among MHC binding peptides, the present classifiers can remove half of the peptides falsely predicted to activate T cells while maintaining the absolute majority of reactive peptides.

CONCLUSIONS

The classifier properties further highlight the contribution of the quantity of peptides reaching the ER and the mutation type to CD8 + T cell responses. These classifiers were then validated on neo-antigens obtained from other datasets, confirming the validity of our prediction. Algorithm Availability: http://peptibase.cs.biu.ac.il/Tcell_predictor/ or by request from the authors as a standalone code.

The IgA Isotype of Anti-β2 Glycoprotein I Antibodies Recognizes Epitopes in Domains 3, 4, and 5 That Are Located in a Lateral Zone of the Molecule (L-Shaped)

Background: Antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity with presence of anti-phospholipid antibodies (aPL). The APS classification criteria only consider the aPL of IgG/IgM isotype, however testing of aPL of IgA isotype is recommended when APS is suspected and consensus aPL are negative. IgA anti-βeta-2 glycoprotein-I (B2GP1) has been clearly related with occurrence of thrombotic events. Antibodies anti-B2GP1 of IgG/M isotypes recognize an epitope in Domain 1 (R39-G43), the epitopes that recognize IgA anti-B2GP1 antibodies are not well-identified. Aim: To determine the zones of B2GP1 recognized by antibodies of IgA isotype from patients with APS symptomatology and positive for IgA anti-B2GP1. Methods: IgA antibodies to Domain-1(D1) and Domain-4/5(D4/5) of B2GP1 (ELISA) and epitope mapping on oligopeptide arrays of B2GP1 were evaluated in sera from a group of 93 patients with at least one thrombotic and with isolated positivity for IgA anti-B2GP1 antibodies (negative for other aPL). Results: A total of 47 patients (50.5%) were positive for anti-D4/5 and 23(25%) were positive for anti-D1. When peptide arrays were analyzed, three zones of B2GP1 reactivity were identified for more than 50% of patients. The center of these zones corresponds to amino acids 140(D3), 204(D4), and 264(D5). The peptides recognized on D3 and D4 contain amino acid sequences sharing high homology with proteins of microorganism that were previously related with a possible APS infectious etiology. In the three-dimensional structure of B2GP1, the three peptides, as the R39-G43 epitope, are located on the right side of the molecule (L-shape). The left side (J-shape) does not bind the antibodies. Conclusions: Patients with thrombotic APS clinical-criteria, and isolated IgA anti-B2GP1 positivity appear to preferentially bind, not to the D1 or D4/5 domains of B2GP1, but rather to three sites in D3, D4, and D5. The sites on D3 and D4 were previously described as the target identified by human monoclonal antibodies derived from patients that were capable of inducing APS in animal models. The localization of these epitopes opens a new route to explore to increase understanding of the patholophysiology of the APS and to propose new alternatives and therapeutic targets.

The combination of neoantigen quality and T lymphocyte infiltrates identifies glioblastomas with the longest survival

Glioblastoma (GBM) is resistant to multimodality therapeutic approaches. A high burden of tumor-specific mutant peptides (neoantigens) correlates with better survival and response to immunotherapies in selected solid tumors but how neoantigens impact clinical outcome in GBM remains unclear. Here, we exploit the similarity between tumor neoantigens and infectious disease-derived immune epitopes and apply a neoantigen fitness model for identifying high-quality neoantigens in a human pan-glioma dataset. We find that the neoantigen quality fitness model stratifies GBM patients with more favorable clinical outcome and, together with CD8+ T lymphocytes tumor infiltration, identifies a GBM subgroup with the longest survival, which displays distinct genomic and transcriptomic features. Conversely, neither tumor neoantigen burden from a quantitative model nor the isolated enrichment of CD8+ T lymphocytes were able to predict survival of GBM patients. This approach may guide optimal stratification of GBM patients for maximum response to immunotherapy.

Tandem Immunoaffinity Purification Using Anti-FLAG and Anti-HA Antibodies

The immunoaffinity purification of target proteins followed by the identification and characterization of associated proteins by mass spectrometry is a widely used technique. An immunoaffinity purification bears resemblance to a standard immunoprecipitation; however, the end product for mass spectrometric analysis in the femtomole (10^-15) to attomole (10^-18) range is required to be of exceptional purity. This high degree of sensitivity in detection renders it of extreme importance to eliminate most if not all of the nonspecific background proteins and can be achieved by performing a tandem affinity purification (TAP). In TAP, the cDNA of the target protein is engineered to contain at least two different epitope tags, and the target protein is extracted under nondenaturing conditions upon expression using an appropriate protein expression platform (CHO cells, HEK 293 cells, or yeast). The expressed protein is initially immunoprecipitated using an antibody against one epitope tag and is eluted in the presence of excess peptide by competition for antibody-binding sites, before being reimmunoprecipitated using an antibody that specifically recognizes the second epitope. These sequential immunoprecipitations significantly reduce the presence of associated nonspecific proteins. Numerous combinations of epitope tags have been applied for tandem affinity purification, and this protocol illustrates the use of tandem hemagglutinin (HA) and FLAG epitope tags. The first immunoprecipitation uses an anti-FLAG antibody followed by the elution in the presence of a competing FLAG peptide before the reimmunoprecipitation of the protein using an anti-HA antibody. Numerous high-quality antiepitope tag antibodies are commercially available from different antibody manufacturers.

Toll-like receptor ligand-dependent inflammatory responses in chick skeletal muscle myoblasts

Toll-like receptors (TLRs) are a group of sensory receptors which are capable of recognizing a microbial invasion and activating innate immune system responses, including inflammatory responses, in both immune and non-immune cells. However, TLR functions in chick myoblasts, which are myogenic precursor cells contributing to skeletal muscle development and growth, have not been studied. Here, we report the expression patterns of TLR genes as well as TLR ligand-dependent transcriptions of interleukin (IL) genes in primary-cultured chick myoblasts. Almost TLR genes were expressed both in layer and broiler myoblasts but TLR1A was detected only in embryonic layer chick myoblasts. Chick TLR1/2 ligands, Pam₃CSK₄ and FSL-1, induced inflammatory ILs in both layer and broiler myoblasts but a TLR4 ligand, lipopolysaccharide, scarcely promoted. This is the first report on TLR ligand-dependent inflammatory responses in chick myoblasts, which may provide useful information to chicken breeding and meat production industries.

CRISPR/Cas9-Mediated Genetic Engineering of Hybridomas for Creation of Antibodies that Allow for Site-Specific Conjugation

Covalent conjugation of chemical moieties to antibodies has numerous applications, including antibody-drug conjugates, antibody conjugation for diagnostics, and more. Most nonspecific chemical conjugation methods ligate onto any of a number of sites on the antibody, leading to multiple conjugated species, many of which perturb antibody function. To solve these problems, we used CRISPR/Cas9-edited hybridomas to introduce a Sortase tag (LPXTG) and a Flag tag at the 3' end of the CH3 heavy chain region of a mouse monoclonal antibody. The Flag tag allows easy purification of the antibody, while the LPXTG is then acted on by the bacterial transpeptidase Sortase to site-specifically add on any of a number of chemical moieties that possess a triglycine repeat. This technique thus allows rapid production of an antibody onto which a wide array of chemical moieties can be site-specifically conjugated.

Mitogen-activated protein kinase kinase 6 is involved in the immune response to bacterial di-/tripeptide challenge in grass carp Ctenopharyngodon idella

Mitogen-activated protein kinase kinase 6 (MKK6) is an essential component of the p38MAPK signaling pathway, which is involved in the modulation of inflammation, cell apoptosis and survival responses in mammals. However, the function of MKK6s in teleosts is still unclear. In this study, a fish MKK6 homolog (CiMKK6) was first identified from the grass carp (Ctenopharyngodon idella), a freshwater fish. CiMKK6 cDNA encodes a putative protein of 357 amino acids that contains conserved structural characteristics of the MKK6 family, including the S_TKc domain, SVAKT motif and DVD site. The deduced CiMKK6 protein exhibits high sequence homology with other reported fish MKK6s and shares the closest relationship with MKK6 from Danio rerio. Quantitative real-time PCR (qRT-PCR) analysis revealed that CiMKK6 mRNA was widely expressed in all tested tissues and stages of embryonic development. Additionally, the transcript levels of CiMKK6 in the intestine were significantly upregulated in response to bacterial muramyl dipeptide (MDP) and L-Ala-γ-D-Glu-meso-diaminopimelic acid (Tri-DAP) stimulation. Moreover, subcellular localization analysis indicated that CiMKK6 was distributed in both the cytoplasm and the nucleus of HEK293T cells. Finally, overexpression of CiMKK6 significantly enhanced the transcriptional activity of the AP-1 reporter gene in HEK293T cells. Overall, these findings may help better clarify the immune function of teleost MKK6s and provide new insight into the immune defense mechanisms of grass carp.

Combining Adhesive Nanostructured Surfaces and Costimulatory Signals to Increase T Cell Activation

Adoptive cell therapies are showing very promising results in the fight against cancer. However, these therapies are expensive and technically challenging in part due to the need of a large number of specific T cells, which must be activated and expanded in vitro. Here we describe a method to activate primary human T cells using a combination of nanostructured surfaces functionalized with the stimulating anti-CD3 antibody and the peptidic sequence arginine-glycine-aspartic acid, as well as costimulatory agents (anti-CD28 antibody and a cocktail of phorbol 12-myristate 13-acetate, ionomycin, and protein transport inhibitors). Thus, we propose a method that combines nanotechnology with cell biology procedures to efficiently produce T cells in the laboratory, challenging the current state-of-the-art expansion methodologies.

Improved methods for predicting peptide binding affinity to MHC class II molecules

Major histocompatibility complex class II (MHC-II) molecules are expressed on the surface of professional antigen-presenting cells where they display peptides to T helper cells, which orchestrate the onset and outcome of many host immune responses. Understanding which peptides will be presented by the MHC-II molecule is therefore important for understanding the activation of T helper cells and can be used to identify T-cell epitopes. We here present updated versions of two MHC-II-peptide binding affinity prediction methods, NetMHCII and NetMHCIIpan. These were constructed using an extended data set of quantitative MHC-peptide binding affinity data obtained from the Immune Epitope Database covering HLA-DR, HLA-DQ, HLA-DP and H-2 mouse molecules. We show that training with this extended data set improved the performance for peptide binding predictions for both methods. Both methods are publicly available at www.cbs.dtu.dk/services/NetMHCII-2.3 and www.cbs.dtu.dk/services/NetMHCIIpan-3.2.

The immunoproteasome-specific inhibitor ONX 0914 reverses susceptibility to acute viral myocarditis

Severe heart pathology upon virus infection is closely associated with the immunological equipment of the host. Since there is no specific treatment available, current research focuses on identifying new drug targets to positively modulate predisposing immune factors. Utilizing a murine model with high susceptibility to coxsackievirus B3-induced myocarditis, this study describes ONX 0914-an immunoproteasome-specific inhibitor-as highly protective during severe heart disease. Represented by reduced heart infiltration of monocytes/macrophages and diminished organ damage, ONX 0914 treatment reversed fulminant pathology. Virus-induced immune response features like overwhelming pro-inflammatory cytokine and chemokine production as well as a progressive loss of lymphocytes all being reminiscent of a sepsis-like disease course were prevented by ONX 0914. Although the viral burden was only minimally affected in highly susceptible mice, resulting maintenance of immune homeostasis improved the cardiac output, and saved animals from severe illness as well as high mortality. Altogether, this could make ONX 0914 a potent drug for the treatment of severe virus-mediated inflammation of the heart and might rank immunoproteasome inhibitors among drugs for preventing pathogen-induced immunopathology.

Integrin-Assisted T-Cell Activation on Nanostructured Hydrogels

Adoptive cell therapy (ACT) has shown very promising results as treatment for cancer in a few clinical trials, such as the complete remissions of otherwise terminal leukemia patients. Nevertheless, the introduction of ACT into clinics requires overcoming not only medical but also technical challenges, such as the ex vivo expansion of large amounts of specific T-cells. Nanostructured surfaces represent a novel T-cell stimulation technique that enables us to fine-tune the density and orientation of activating molecules presented to the cells. In this work, we studied the influence of integrin-mediated cell-adhesion on T-cell activation, proliferation, and differentiation using nanostructured surfaces, which provide a well-defined system at the nanoscale compared with standard cultures. Specifically, we synthesized a polymeric polyethylene glycol (PEG) hydrogel cross-linked with two fibronectin-derived peptides, cyclic Arg-Gly-Asp (cRGD) and cyclic Leu-Asp-Val (cLDV), that are known to activate different integrins. Moreover, the hydrogels were decorated with a quasi-hexagonal array of gold nanoparticles (AuNPs) functionalized with the activating antibody CD3 to initiate T-cell activation. Both cLDV and cRGD hydrogels showed higher T-cell activation (CD69 expression and IL-2 secretion) than nonfunctionalized PEG hydrogels. However, only the cRGD hydrogels clearly supported proliferation giving a higher proportion of cells with memory (CD4⁺CD45RO⁺) than naı̈ve (CD4⁺CD45RA⁺) phenotypes when interparticle distances smaller than 150 nm were used. Thus, T-cell proliferation can be enhanced by the activation of integrins through the RGD sequence.

Epitope-specific immunotherapy targeting CD4-positive T cells in coeliac disease: two randomised, double-blind, placebo-controlled phase 1 studies

BACKGROUND

A gluten-free diet is the only means to manage coeliac disease, a permanent immune intolerance to gluten. We developed a therapeutic vaccine, Nexvax2, designed to treat coeliac disease. Nexvax2 is an adjuvant-free mix of three peptides that include immunodominant epitopes for gluten-specific CD4-positive T cells. The vaccine is intended to engage and render gluten-specific CD4-positive T cells unresponsive to further antigenic stimulation. We assessed the safety and pharmacodynamics of the vaccine in patients with coeliac disease on a gluten-free diet.

METHODS

We did two randomised, double-blind, placebo-controlled, phase 1 studies at 12 community sites in Australia, New Zealand, and the USA, in HLA-DQ2·5-positive patients aged 18-70 years who had coeliac disease and were on a gluten-free diet. In the screening period for ascending dose cohorts, participants were randomly assigned (1:1) by central randomisation with a simple block method to a double-blind crossover, placebo-controlled oral gluten challenge. Participants with a negative interferon γ release assay to Nexvax2 peptides after the screening oral gluten challenge were discontinued before dosing. For the biopsy cohorts, the screening period included an endoscopy, and participants with duodenal histology who had a Marsh score of greater than 1 were discontinued before dosing. Participants were subsequently randomly assigned to either Nexvax2 or placebo in ascending dose cohorts (2:1) and in biopsy cohorts (1:1) by central randomisation with a simple block method. In the three-dose study, participants received either Nexvax2 60 μg, 90 μg, or 150 μg weekly, or placebo over 15 days; in a fourth biopsy cohort, patients received either Nexvax2 at the maximum tolerated dose (MTD) or placebo. In the 16-dose study, participants received Nexvax2 150 μg or 300 μg or placebo twice weekly over 53 days; in a third biopsy cohort, patients also received either Nexvax2 at the MTD or placebo. In the 4-week post-treatment period, ascending dose cohorts underwent a further double-blind crossover, placebo-controlled oral gluten challenge, which had a fixed sequence, and biopsy cohorts had a gastroscopy with duodenal biopsies and quantitative histology within 2 weeks without oral gluten challenge. Participants, investigators, and study staff were masked to the treatment assignment, except for the study pharmacist. The primary endpoint was the number and percentage of adverse events in the treatment period in an intention-to-treat analysis. Both trials were completed and closed before data analysis. Trials were registered with the Australian New Zealand Clinical Trials Registry, numbers ACTRN12612000355875 and ACTRN12613001331729.

FINDINGS

Participants were enrolled from Nov 28, 2012, to Aug 14, 2014, in the three-dose study, and from Aug 3, 2012, to Sept 10, 2013, in the 16-dose study. Overall, 62 (57%) of 108 participants were randomly assigned after oral gluten challenge and 20 (71%) of 28 participants were randomly assigned after endoscopy. In the three-dose study, nine participants were randomly allocated to Nexvax2 60 μg and three to placebo (first cohort), nine were allocated to Nexvax2 90 μg and four to placebo (second cohort), eight were allocated to Nexvax2 150 μg and four to placebo (third cohort), and three were allocated to Nexvax2 150 μg and three to placebo (biopsy cohort). In the 16-dose study, eight participants were randomly allocated to Nexvax2 150 μg and four to placebo (first cohort), ten were allocated to Nexvax2 300 μg and three to placebo (second cohort), and seven were allocated to Nexvax2 150 μg and seven to placebo (biopsy cohort). The MTD for Nexvax2 was 150 μg because of transient, acute gastrointestinal adverse events with onset 2-5 h after initial doses of the vaccine, similar to those caused by gluten ingestion. In the ascending dose cohorts in the three-dose study, six (55%) of 11 placebo recipients, five (56%) of nine who received Nexvax2 60 μg, seven (78%) of nine who received Nexvax2 90 μg, and five (63%) of eight who received Nexvax2 150 μg had at least one treatment-emergent adverse event, as did all three (100%) placebo recipients and one (33%) of three Nexvax2 150 μg recipients in the biopsy cohort. In the ascending dose cohorts of the 16-dose study, five (71%) of seven placebo-treated participants, six (75%) of eight who received Nexvax2 150 μg, and all ten (100%) who received Nexvax2 300 μg had at least one treatment-emergent adverse event, as did six (86%) of seven placebo recipients and five (71%) of seven Nexvax2 150 μg recipients in the biopsy cohort. Vomiting, nausea, and headache were the only treatment-emergent adverse events that occurred in at least 5% of participants in either study. Among participants given the MTD, eight gastrointestinal treatment-emergent adverse events occurred in four (50%) of eight participants in the third cohort and none (0%) of three participants in the biopsy cohort in the three-dose study, and five events occurred in five (63%) of eight participants in the first cohort and three events in two (29%) of seven participants in the biopsy cohort of the 16-dose study. Median villous height to crypt depth ratio in distal duodenal biopsies was not significantly different between those who received the vaccine at the MTD on either schedule and those who received placebo. Of the participants who completed the post-treatment oral gluten challenge per protocol, interferon γ release assay to Nexvax2 peptides was negative (responders to treatment) in two (22%) of nine placebo-treated participants in the three-dose study versus two (33%) of six who received Nexvax2 60 μg, five (63%) of eight who received Nexvax2 90 μg, and six (100%) of six who received Nexvax2 150 μg (p=0·007); in the 16-dose study, none (0%) of five placebo-treated participants had a negative assay versus six (75%) of eight who received Nexvax2 150 μg (p=0·021).

INTERPRETATION

The MTD of Nexvax2 was 150 μg for twice weekly intradermal administration over 8 weeks, which modified immune responsiveness to Nexvax2 peptides without deterioration in duodenal histology. The gastrointestinal symptoms that followed the first intradermal administration of the vaccine resembled those associated with oral gluten challenge. These findings support continued clinical development of this potential therapeutic vaccine for coeliac disease.

FUNDING

ImmusanT.

CD40 Signaling Drives Potent Cellular Immune Responses in Heterologous Cancer Vaccinations

Antagonistic antibodies targeting coinhibitory receptors have revolutionized the treatment of cancer by inducing durable immune responses and clinical remissions in patients. In contrast, success of agonistic costimulatory antibodies has thus far been limited because of the insufficient induction of adaptive immune responses. Here, we describe a novel vaccination method consisting of a primary dendritic cell (DC) immunization followed by a composite vaccination, including an agonistic CD40 antibody, soluble antigen, and a TLR3 agonist, referred to as CoAT. In mice, DC/CoAT prime-boost vaccinations targeting either MHC class I or II neoantigens or tumor-associated antigens rendered up to 60% of the total T-cell population specific for a single tumor epitope. DC/CoAT induced durable and complete remissions of large subcutaneous tumors without detectable side effects. Thus, booster vaccinations with agonistic costimulatory antibodies represent an ideal means to amplify DC vaccinations and induce robust T-cell immune responses while providing maximum flexibility regarding the choice of antigen. Cancer Res; 77(8); 1918-26. ©2017 AACR.

Targeting Carcinoembryonic Antigen with DNA Vaccination: On-Target Adverse Events Link with Immunologic and Clinical Outcomes

PURPOSE

We have clinically evaluated a DNA fusion vaccine to target the HLA-A*0201-binding peptide CAP-1 from carcinoembryonic antigen (CEA605-613) linked to an immunostimulatory domain (DOM) from fragment C of tetanus toxin.

EXPERIMENTAL DESIGN

Twenty-seven patients with CEA-expressing carcinomas were recruited: 15 patients with measurable disease (arm-I) and 12 patients without radiological evidence of disease (arm-II). Six intramuscular vaccinations of naked DNA (1 mg/dose) were administered up to week 12. Clinical and immunologic follow-up was up to week 64 or clinical/radiological disease.

RESULTS

DOM-specific immune responses demonstrated successful vaccine delivery. All patients without measurable disease compared with 60% with advanced disease responded immunologically, while 58% and 20% expanded anti-CAP-1 CD8+ T cells, respectively. CAP-1-specific T cells were only detectable in the blood postvaccination but could also be identified in previously resected cancer tissue. The gastrointestinal adverse event diarrhea was reported by 48% of patients and linked to more frequent decreases in CEA (P < 0.001) and improved global immunologic responses [anti-DOM responses of greater magnitude (P < 0.001), frequency (P = 0.004), and duration] compared with patients without diarrhea. In advanced disease patients, decreases in CEA were associated with better overall survival (HR = 0.14, P = 0.017). CAP-1 peptide was detectable on MHC class I of normal bowel mucosa and primary colorectal cancer tissue by mass spectrometry, offering a mechanistic explanation for diarrhea through CD8+ T-cell attack.

CONCLUSIONS

Our data suggest that DNA vaccination is able to overcome peripheral tolerance in normal and tumor tissue and warrants testing in combination studies, for example, by vaccinating in parallel to treatment with an anti-PD1 antibody. Clin Cancer Res; 22(19); 4827-36. ©2016 AACR.

Ligand-induced Epitope Masking: DISSOCIATION OF INTEGRIN α5β1-FIBRONECTIN COMPLEXES ONLY BY MONOCLONAL ANTIBODIES WITH AN ALLOSTERIC MODE OF ACTION

We previously demonstrated that Arg-Gly-Asp (RGD)-containing ligand-mimetic inhibitors of integrins are unable to dissociate pre-formed integrin-fibronectin complexes (IFCs). These observations suggested that amino acid residues involved in integrin-fibronectin binding become obscured in the ligand-occupied state. Because the epitopes of some function-blocking anti-integrin monoclonal antibodies (mAbs) lie near the ligand-binding pocket, it follows that the epitopes of these mAbs may become shielded in the ligand-occupied state. Here, we tested whether function-blocking mAbs directed against α5β1 can interact with the integrin after it forms a complex with an RGD-containing fragment of fibronectin. We showed that the anti-α5 subunit mAbs JBS5, SNAKA52, 16, and P1D6 failed to disrupt IFCs and hence appeared unable to bind to the ligand-occupied state. In contrast, the allosteric anti-β1 subunit mAbs 13, 4B4, and AIIB2 could dissociate IFCs and therefore were able to interact with the ligand-bound state. However, another class of function-blocking anti-β1 mAbs, exemplified by Lia1/2, could not disrupt IFCs. This second class of mAbs was also distinguished from 13, 4B4, and AIIB2 by their ability to induce homotypic cell aggregation. Although the epitope of Lia1/2 was closely overlapping with those of 13, 4B4, and AIIB2, it appeared to lie closer to the ligand-binding pocket. A new model of the α5β1-fibronectin complex supports our hypothesis that the epitopes of mAbs that fail to bind to the ligand-occupied state lie within, or very close to, the integrin-fibronectin interface. Importantly, our findings imply that the efficacy of some therapeutic anti-integrin mAbs could be limited by epitope masking.

Hotspot autoimmune T cell receptor binding underlies pathogen and insulin peptide cross-reactivity

The cross-reactivity of T cells with pathogen- and self-derived peptides has been implicated as a pathway involved in the development of autoimmunity. However, the mechanisms that allow the clonal T cell antigen receptor (TCR) to functionally engage multiple peptide–major histocompatibility complexes (pMHC) are unclear. Here, we studied multiligand discrimination by a human, preproinsulin reactive, MHC class-I–restricted CD8⁺ T cell clone (1E6) that can recognize over 1 million different peptides. We generated high-resolution structures of the 1E6 TCR bound to 7 altered peptide ligands, including a pathogen-derived peptide that was an order of magnitude more potent than the natural self-peptide. Evaluation of these structures demonstrated that binding was stabilized through a conserved lock-and-key–like minimal binding footprint that enables 1E6 TCR to tolerate vast numbers of substitutions outside of this so-called hotspot. Highly potent antigens of the 1E6 TCR engaged with a strong antipathogen-like binding affinity; this engagement was governed though an energetic switch from an enthalpically to entropically driven interaction compared with the natural autoimmune ligand. Together, these data highlight how T cell cross-reactivity with pathogen-derived antigens might break self-tolerance to induce autoimmune disease.

Production of a Chaetomium globosum enolase monoclonal antibody

Chaetomium globosum is a hydrophilic fungal species and a contaminant of water-damaged building materials in North America. Methods to detect Chaetomium species include subjective identification of ascospores, viable culture, or molecular-based detection methods. In this study, we describe the production and initial characterization of a monoclonal antibody (MAb) for C. globosum enolase. MAb 1C7, a murine IgG1 isotype MAb, was produced and reacted with recombinant C. globosum enolase (rCgEno) in an enzyme-linked immunosorbent assay and with a putative C. globosum enolase in a Western blot. Epitope mapping showed MAb 1C7 specific reactivity to an enolase decapeptide, LTYEELANLY, that is highly conserved within the fungal class Sordariomycetes. Cross-reactivity studies showed MAb 1C7 reactivity to C. atrobrunneum but not C. indicum. MAb 1C7 did not react with enolase from Aspergillus fumigatus, which is divergent in only two amino acids within this epitope. The results of this study suggest potential utility of MAb 1C7 in Western blot applications for the detection of Chaetomium and other Sordariomycetes species.

Extended evaluation of a phase 1/2 trial on dosing, safety, immunogenicity, and overall survival after immunizations with an advanced-generation Ad5 [E1-, E2b-]-CEA(6D) vaccine in late-stage colorectal cancer

A phase 1/2 clinical trial evaluating dosing, safety, immunogenicity, and overall survival on metastatic colorectal cancer (mCRC) patients after immunotherapy with an advanced-generation Ad5 [E1-, E2b-]-CEA(6D) vaccine was performed. We report our extended observations on long-term overall survival and further immune analyses on a subset of treated patients including assessment of cytolytic T cell responses, T regulatory (Treg) to T effector (Teff) cell ratios, flow cytometry on peripheral blood mononuclear cells (PBMCs), and determination of HLA-A2 status. An overall survival of 20 % (median survival 11 months) was observed during long-term follow-up, and no long-term adverse effects were reported. Cytolytic T cell responses increased after immunizations, and cell-mediated immune (CMI) responses were induced whether or not patients were HLA-A2 positive or Ad5 immune. PBMC samples from a small subset of patients were available for follow-up immune analyses. It was observed that the levels of carcinoembryonic antigen (CEA)-specific CMI activity decreased from their peak values during follow-up in five patients analyzed. Preliminary results revealed that activated CD4+ and CD8+ T cells were detected in a post-immunization sample exhibiting high CMI activity. Treg to Teff cell ratios were assessed, and samples from three of five patients exhibited a decrease in Treg to Teff cell ratio during the treatment protocol. Based upon the favorable safety and immunogenicity data obtained, we plan to perform an extensive immunologic and survival analysis on mCRC patients to be enrolled in a randomized/controlled clinical trial that investigates Ad5 [E1-, E2b-]-CEA(6D) as a single agent with booster immunizations.

Sortase Enzyme-Mediated Generation of Site-Specifically Conjugated Antibody Drug Conjugates with High In Vitro and In Vivo Potency

Antibody drug conjugates (ADCs) have recently been proven to be highly potent anti-tumor drugs, typically exceeding the efficacy of conventional monoclonal antibodies (mAbs). ADCs are currently produced by chemical conjugation of a small-molecule toxin to the mAb through lysine or cysteine side chains. This leads to heterogeneous mixtures of ADCs in which variable numbers of drugs are conjugated to individual antibodies and in which the site of conjugation cannot be defined. Consequently, there is currently significant interest in further development of drug conjugation technologies, with a particular focus on site-specific payload conjugation. Here, we present an enzymatic conjugation platform based on the S. aureus sortase A-mediated transpeptidation reaction, allowing the efficient generation of ADCs with toxins conjugated to pre-defined sites at pre-defined drug-to-antibody ratios. For this, two modifications were introduced: first, immunoglobulin heavy (IgH) and light (IgL) chains were modified at their C-termini by addition of the sortase A recognition motif LPETG, and second, the small molecule tubulin polymerization inhibitors monomethylauristatin E (MMAE) and maytansine were modified by addition of a pentaglycine peptide, thus making them suitable substrates for sortase A-mediated transpeptidation. We demonstrate efficient generation and characterization of the anti-CD30 ADC Ac10-vcPAB-MMAE, an enzymatically conjugated counterpart of brentuximab vedotin (Adcetris), as well as several anti-HER-2 ADCs including trastuzumab-maytansine, the counterpart of trastuzumab emtansine (Kadcyla). ADCs generated in this manner were found to display in vitro cell killing activities indistinguishable from the classic conjugates. Further, when tested in vivo in a HER-2-overexpressing ovarian cancer xenograft mouse model, enzymatically generated trastuzumab-maytansine was found to lead to complete regression of established tumors, similar to Kadcyla.

[Expression and adjuvant effects of the fusion peptide TBP5]

Thymopentin (TP5) and bursopentin (BP5) are both immunopotentiators. To explore whether the TP5-BP5 fusion peptide (TBP5) has adjuvant activity or not, we cloned the TBP5 gene and confirmed that the TBP5 gene in a recombinant prokaryotic expression plasmid was successfully expressed in Escherichia coli BL21. TBP5 significantly promoted the proliferation of thymic and splenic lymphocytes of mice. The potential adjuvant activity of the TBP5 was examined in mice by coinjecting TBP5 and H9N2 avian influenza virus (AIV) inactivated vaccine. HI antibody titers, HA antibodies and cytokines levels (IL-4 and IFN-γ) were determined. We found that TBP5 markedly elevated serum HI titers and HA antibody levels, induced the secretion of both IL-4 and IFN-γ cytokines. Furthermore, virus challenge experiments confirmed that TBP5 contributed to inhibition replication of the virus [H9N2 AIV (A/chicken/Jiangsu/NJ07/05)] from mouse lungs. Altogether, these findings suggest that TBP5 may be an effective adjuvant for avian vaccine and that this study provides a reference for further research on new vaccine adjuvants.

RECOMBINANT SINGLE CHAIN VARIABLE FRAGMENT ANTIBODIES (scFv) AGAINST Pro144-Leu155 FRAGMENT OF HUMAN PROTEIN C

The aim of this work was to obtain the recombinant single chain variable fragments of antibodies (scFv) against human protein C, the key component of blood anticoagulation system. For this purpose a peptide that mimics a Pro144-Leu155 sequence of protein C was synthesized and the murine immune scFv library against this peptide was constructed. The protein C specific scFv 9E were selected from the constructed library by the phage-display method. The scFv 9E dissociation constant was found to be 2∙10(-9) M. It was shown that scFv 9E were suitable for protein C detection by ELISA and Western blotting. Selected scFv could be further used for protein C investigation and for the development of quantitative methods for protein C detection in human blood.

A multiplex method for the detection of serum antibodies against in silico-predicted tumor antigens

Humoral immune responses against tumor antigens are studied as indirect markers of antigen exposure and in cancer vaccine studies. An increasing number of tumor antigens potentially translated from mutant genes is identified by advances in genomic sequencing. They represent an interesting source for yet unknown immunogenic epitopes. We here describe a multiplex method using the Luminex technology allowing for the detection of antibodies against multiple in silico-predicted linear neo-antigens in large sets of sera. The approach included 32 synthetic biotinylated peptides comprising a predicted set of frameshift mutation-induced neo-antigens. The antigens were fused to a FLAG epitope to ensure monitoring antigen binding to avidin-linked microspheres in the absence of monoclonal antibodies. Analytical specificity of measured serum antibody reactivity was proven by the detection of immune responses in immunized rabbits and a colorectal cancer patient vaccinated with peptides included in the assay. The measured antibody responses were comparable to peptide ELISA, and inter-assay reproducibility of the multiplex approach was excellent (R (2) > 0.98) for 20 sera tested against all antigens. Our methodic approach represents a valuable platform to monitor antibody responses against predicted antigens. It may be used in individualized cancer vaccine studies, thereby extending the relevance beyond the model system in the presented approach.

Vaccine for human contraception targeting sperm Izumo protein and YLP12 dodecamer peptide

There is an urgent need to develop a better method of contraception which is non-steroidal and reversible to control world population explosion and unintended pregnancies. Contraceptive vaccines (CV), especially targeting sperm-specific proteins, can provide an ideal contraceptive modality. Sperm-specific proteins can induce an immune response in women as well as men, thus can be used for CV development in both sexes. In this article, we will review two sperm-specific proteins, namely Izumo protein and YLP12 dodecamer peptide. Gene-knockout studies indicate that Izumo protein is essential for sperm-egg membrane fusion. Vaccination with Izumo protein or its cDNA causes a significant reduction in fertility of female mice. The antibodies to human Izumo inhibit human sperm penetration assay. Recently, our laboratory found that a significant percentage of infertile women have antibodies to Izumo protein. The second sperm-specific protein is YLP12 , a peptide mimetic sequence present on human sperm involved in recognition and binding to the human oocyte zona pellucida. Vaccination with YLP12 or its cDNA causes long-term, reversible contraception, without side effects, in female mice. Infertile, but not fertile, men and women have antibodies to YLP12 peptide. Our laboratory has isolated, cloned, and sequenced cDNA encoding human single chain variable fragment (scFv) antibody from infertile men which reacts with YLP12 peptide. The human YLP12 scFv antibody may provide a novel passive immunocontraceptive, the first of its kind. In conclusion, sperm-specific Izumo protein and YLP12 peptide can provide exciting candidates for antisperm CV development.

TCR scanning of peptide/MHC through complementary matching of receptor and ligand molecular flexibility

Although conformational changes in TCRs and peptide Ags presented by MHC protein (pMHC) molecules often occur upon binding, their relationship to intrinsic flexibility and role in ligand selectivity are poorly understood. In this study, we used nuclear magnetic resonance to study TCR-pMHC binding, examining recognition of the QL9/H-2L(d) complex by the 2C TCR. Although the majority of the CDR loops of the 2C TCR rigidify upon binding, the CDR3β loop remains mobile within the TCR-pMHC interface. Remarkably, the region of the QL9 peptide that interfaces with CDR3β is also mobile in the free pMHC and in the TCR-pMHC complex. Determination of conformational exchange kinetics revealed that the motions of CDR3β and QL9 are closely matched. The matching of conformational exchange in the free proteins and its persistence in the complex enhances the thermodynamic and kinetic stability of the TCR-pMHC complex and provides a mechanism for facile binding. We thus propose that matching of structural fluctuations is a component of how TCRs scan among potential ligands for those that can bind with sufficient stability to enable T cell signaling.

Activation of an innate immune response in the schistosome-transmitting snail Biomphalaria glabrata by specific bacterial PAMPs

Injection of crude lipopolysaccharide (LPS) from Escherichia coli into the hemocoel of Biomphalaria glabrata stimulates cell proliferation in the amebocyte-producing organ (APO). However, it is not known if mitogenic activity resides in the lipid A or O-polysaccharide component of LPS. Moreover, the possible role of substances that commonly contaminate crude LPS and that are known to stimulate innate immune responses in mammals, e.g., peptidoglycan (PGN), protein, or bacterial DNA, is unclear. Therefore, we tested the effects of the following injected substances on the snail APO: crude LPS, ultrapurified LPS (lacking lipoprotein contamination), two forms of lipid A, (diphosphoryl lipid A and Kdo2-lipid A), O-polysaccharide, Gram negative PGN, both crude and ultrapurified (with and without endotoxin activity, respectively), Gram positive PGN, PGN components Tri-DAP and muramyl dipeptide, and bacterial DNA. Whereas crude LPS, ultrapurified LPS, and crude PGN were mitogenic, ultrapurified PGN was not. Moreover, LPS components, PGN components, and bacterial DNA were inactive. These results suggest that it is the intact LPS molecule which stimulates cell division in the APO.

Humoral immune responses to EGFR-derived peptides predict progression-free and overall survival of non-small cell lung cancer patients receiving gefitinib

Somatic mutations in the epidermal growth factor receptor (EGFR) gene are associated with clinical response to EGFR tyrosine kinase inhibitors (TKIs), such as gefitinib, in patients with non-small cell lung cancer (NSCLC). However, humoral immune responses to EGFR in NSCLC patients have not been well studied. In this study, we investigated the clinical significance of immunoglobulin G (IgG) responses to EGFR-derived peptides in NSCLC patients receiving gefitinib. Plasma IgG titers to each of 60 different EGFR-derived 20-mer peptides were measured by the Luminex system in 42 NSCLC patients receiving gefitinib therapy. The relationships between the peptide-specific IgG titers and presence of EGFR mutations or patient survival were evaluated statistically.

IgG titers against the egfr_481–500, egfr_721–740, and egfr_741–760 peptides were significantly higher in patients with exon 21 mutation than in those without it. On the other hand, IgG titers against the egfr_841–860 and egfr_1001–1020 peptides were significantly lower and higher, respectively, in patients with deletion in exon 19. Multivariate Cox regression analysis showed that IgG responses to egfr_41_ 60, egfr_61_80 and egfr_481_500 were significantly prognostic for progression-free survival independent of other clinicopathological characteristics, whereas those to the egfr_41_60 and egfr_481_500 peptides were significantly prognostic for overall survival. Detection of IgG responses to EGFR-derived peptides may be a promising method for prognostication of NSCLC patients receiving gefitinib. Our results may provide new insight for better understanding of humoral responses to EGFR in NSCLC patients.

Identification of novel human leukocyte antigen-A*0201-restricted, cytotoxic T lymphocyte epitopes on CD133 for cancer stem cell immunotherapy

Targeting cancer stem cells (CSCs) with immunotherapy may be an effective means to prevent recurrences in glioblastoma multiforme (GBM). It is well established that CD133 is expressed in the population of GBM tumor cells representing CSCs. This raises a possibility that CD133 could serve as a potential target for cytotoxic T cells (CTLs) to target glioblastoma cancer stem cells. Two potential human leukocyte antigen (HLA)-A*0201-restricted CD133 epitopes, ILSAFSVYV (CD133-405) and YLQWIEFSI (CD133-753), showed strong binding to HLA-A*0201 molecules. In vitro immunogenicity studies generated peptide-specific CD8(+) CTLs from normal donors. Autologous monocyte-derived dendritic cells pulsed with the CD133-405 or CD133-753 peptides generated CTLs that efficiently recognized the CD133 epitopes presented in T2 HLA-A*0201 cells and specifically lysed CD133+ HLA-A*0201(+) GBM CSCs. These studies demonstrated natural processing and subsequent presentation of these epitopes in GBM CSCs and the ability of CTLs to kill CSCs bearing the antigen. Immunization studies in mice using the mouse homolog CD133 epitopes demonstrated immunogenicity in the absence of autoimmune damage. The results presented in this study support the use of CD133-specific epitope vaccines to target CSCs in glioblastoma and other cancers.

[Effects of myelopeptide-1 on functional activity of murine phagocytes treated with cyclophosphan]

The effects of bone marrow derived myelopeptide-1 (MP-1) on functional activities of normal murine phagocytes and phagocytes obtained from mice treated with cytostatic agent cyclophosphan (CY) were studied in vivo and in vitro. We demonstrated immunocorrecting effect of MP-1 on functional activity of bone marrow and peripheral blood phagocytes. An optimal protocol of MP-1 injections during cytostatic therapy was developed to obtain maximal efficacy in immunocorrection. The best effect on functional activity of phagocytes of different localization (the highest effect on peripheral blood neutrophils) was found when MP-1 was injected before CY. The results demonstrated that MP-1 can be considered as a substance able to protect peripheral blood phagocytes from CY damage during cytostatic treatment.

Relapse or eradication of cancer is predicted by peptide-major histocompatibility complex affinity

Cancers often relapse after adoptive therapy, even though specific T cells kill cells from the same cancer efficiently in vitro. We found that tumor eradication by T cells required high affinities of the targeted peptides for major histocompatibility complex (MHC) class I. Affinities of at least 10 nM were required for relapse-free regression. Only high-affinity peptide-MHC interactions led to efficient cross-presentation of antigen, thereby stimulating cognate T cells to secrete cytokines. These findings highlight the importance of targeting peptides with high affinity for MHC class I when designing T cell-based immunotherapy.

Multiple sites of the cleavage of 21- and 25-mer encephalytogenic oligopeptides corresponding to human myelin basic protein (MBP) by specific anti-MBP antibodies from patients with systemic lupus erythematosus

IgGs from patients with multiple sclerosis and systemic lupus erythematosus (SLE) purified on MBP-Sepharose in contrast to canonical proteases hydrolyze effectively only myelin basic protein (MBP), but not many other tested proteins. Here we have shown for the first time that anti-MBP SLE IgGs hydrolyze nonspecific tri- and tetrapeptides with an extreme low efficiency and cannot effectively hydrolyze longer 20-mer nonspecific oligopeptides corresponding to antigenic determinants (AGDs) of HIV-1 integrase. At the same time, anti-MBP SLE IgGs efficiently hydrolyze oligopeptides corresponding to AGDs of MBP. All sites of IgG-mediated proteolysis of 21-and 25-mer encephalytogenic oligopeptides corresponding to two known AGDs of MBP were found by a combination of reverse-phase chromatography, TLC, and MALDI spectrometry. Several clustered major, moderate, and minor sites of cleavage were revealed in the case of 21- and 25-mer oligopeptides. The active sites of anti-MBP abzymes are localised on their light chains, while heavy chains are responsible for the affinity of protein substrates. Interactions of intact globular proteins with both light and heavy chains of abzymes provide high affinity to MBP and specificity of this protein hydrolysis. The affinity of anti-MBP abzymes for intact MBP is approximately 1000-fold higher than for the oligopeptides. The data suggest that all oligopeptides interact mainly with the light chains of different monoclonal abzymes of total pool of IgGs, which possesses a lower affinity for substrates, and therefore, depending on the oligopeptide sequences, their hydrolysis may be less specific than globular protein and can occur in several sites.

Identification of a novel HLA-A2-restricted mutated Survivin epitope and induction of specific anti-HCC CTLs that could effectively cross-recognize wild-type Survivin antigen

Peptide vaccine based on tumor-associated antigen (TAA), which usually belongs to self-antigen with poor immunogenicity, has been considered as an attractive option for treatment of malignant tumors. The ideal TAA epitopes should have stable affinity to major histocompatibility complex (MHC) molecules and elicit strong anti-tumor immune response. Although point-mutation technology of TAA peptide may increase the binding capability to MHC molecules, some previous studies have revealed that part of the variant peptides results in lymphocyte not to effectively cross-recognize and kill the target tumor expressed wild-type TAA. Here, we designed a novel HLA-A2-restricted mutated TAA Survivin epitope nonapeptide Sur79L2 (KLSSGCAFL) that showed higher binding ability compared to wild-type peptide Sur79 (KHSSGCAFL) in T2-binding assays. To investigate whether Sur79L2 can induce Survivin-specific anti-hepatocellular carcinoma (HCC) response, we stimulated tumor-associated lymphocytes from a HCC patient with Sur79L2 in vitro. IFN-γ release and cytotoxicity assays showed Sur79L2 could effectively cross-recognize and lysis T2 cell plus peptide Sur79 and HCC cell lines (expression of wild-type Survivin antigen) in an HLA-A2-restricted manner. In contrast, peptide Sur95 (ELTLGEFLKL) that has been reported as a very promising anti-tumor epitope in a variety of tumors except HCC were not able to generate detectable cytotoxic immune responses against HCC in this study. Our results suggest that point-mutated peptide Sur79L2 is a new HLA-A2-restricted CTL epitope and may be useful for the immunotherapy for patients with HCC.

A deeper analysis of the epitope/paratope of PLY-5, a mouse monoclonal antibody which recognises the conserved undecapeptide tryptophan-rich loop (ECTGLAWEWWR) of bacterial cholesterol-dependent cytolysins

A previous study showed that the minimal epitope recognised by the PLY-5 mAb in the conserved undecapeptide Trp-rich loop of bacterial CDCs should consist of WEWWRT (Jacobs et al., 1999) [5]. Now, through immunoscreening of amino acid substitution analogues, it is concluded that the second Trp and the Arg residues are essential in the PLY-5 epitope. The E residue is an auxiliary epitope contributor. Antibody modelling and docking simulations provided support for these findings. For recognition by the antibody, the Trp-rich loop flipped out, mimicking the mechanism of membrane insertion. The displaced second Trp was seen to establish aromatic stacking interactions with aromatic residues of the antibody paratope and the notably extruded guanidium tip of the arginine residue mediated electrostatic interactions with well-exposed carboxylic groups of glutamic residues on the surface of the paratope. Thus, the epitope/paratope interaction is mainly mediated by aromatic and by ionic interactions.

Recognition of a natural WT1 epitope by a modified WT1 peptide-specific T-cell receptor

Wilms' tumor gene WT1 is highly expressed in leukemia and in various types of solid tumors and exerts an oncogenic function. Thus, WT1 protein is a most promising tumor-associated antigen. We have been successfully performing WT1 vaccination with a 9-mer modified WT1(235) peptide, which has one amino acid substitution (M→Y) at position 2 of 9-mer natural WT1(235) peptide (235-243 a.a.), for close to 700 HLA-A*24:02-positive patients with leukemia or solid tumors. Although vaccination of modified WT1(235) peptide induced natural WT1(235) peptide-recognizing cytotoxic T-lymphocytes (CTLs) and exerted cytotoxic activity towards leukemia and solid tumor cells that expressed the natural WT1(235) peptide (epitope) but not the vaccinated modified WT1(235) peptide (epitope), the molecular basis has remained unclear. In this study, we established a modified WT1(235) peptide-specific CTL clone, we isolated T-cell receptor (TCR) genes from it and transduced the TCR genes into CD8(+) T-cells. The TCR-transduced CD8(+) T-cells produced interferon-γ (IFNγ) and tumor necrosis factor-α (TNFα) in response to stimulation not only with the modified WT1(235) peptide but also with the natural WT1(235) peptide and lysed modified or natural WT1(235) peptide-pulsed target cells and endogenously WT1-expressing leukemia cells in a HLA-A*24:02-restriction manner. These results provided us, for the first time at molecular basis, with a proof-of-concept of modified WT1(235) peptide-based immunotherapy for natural WT1(235) peptide-expressing malignancies.

Mimotope peptides selected from phage display combinatorial library by serum antibodies of pigs experimentally infected with Taenia solium as leads to developing diagnostic antigens for human neurocysticercosis

Neurocysticercosis is caused by penetration of the tapeworm Taenia solium larvae into the central nervous system resulting in a diverse range of neurologic complications including epilepsy in endemic areas that globalization spreads worldwide. Sensitive and specific immunodiagnosis is needed for the early detection and elimination of the parasite, but the lack of standardized, readily obtainable antigens is a challenge. Here, we used the phage display for resolving the problem. The rationale of the strategy rests on the concept that the screening of combinatorial libraries with polyclonal serum to pathogens reveals families of peptides mimicking the pathogen most immunodominant epitopes indispensable for the successful diagnosis. The screening of a 7mer library with serum IgG of four pigs experimentally infected with parasite followed by computer aided segregation of the selected sequences resulted in the discovery of four clusters of homologous sequences of which one presented a family of ten mimotopes selected by three infected pig serum IgGs; the common motif sequence LSPF carried by the family was considered to be the core of an immunodominant epitope of the parasite critical for the binding with the antibody that selected the mimotopes. The immunoassay testing permitted to select a mimotope whose synthetic peptide free of the phage with the amino acid sequence Leu-Ser-Fen-Pro-Ser-Val-Val that distinguished well a panel of 21 cerebrospinal fluids of neurocysticercosis patients from the fluids of individuals with neurological complications of other etiology. This peptide is proposed as a lead for developing a novel molecularly defined diagnostic antigen(s) for the neurocysticercosis.

Generation of tissue-specific H-2Kd transgenic mice for the study of K(d)-restricted malaria epitope-specific CD8+ T-cell responses in vivo

CD8(+) T cells are critical for the control of various intracellular infections and cancers. To date, however, effective T cell-based vaccines remain elusive, due, in part, to the lack of in vivo models that facilitate the dissection of antigen-specific CD8(+) T-cell responses primed by different antigen-presenting cells (APCs). In this study, we generated four lines of H-2K(d) transgenic (K(d) Tg) mice that differed in their expression of H-2K(d): dendritic cells (DCs) only (CD11c-K(d)), macrophages only (huCD68-K(d)), hepatocytes only (Alb-K(d)), or all nucleated cells (major histocompatibility complex-I-K(d)). Immunization of each of these K(d) Tg mouse strains with a synthetic peptide or a recombinant adenovirus expressing a well-known immunodominant, H-2K(d)-restricted CD8(+) T-cell epitope, SYVPSAEQI, which was derived from the circumsporozoite protein of Plasmodium yoelii, promoted distinct SYVPSAEQI-specific CD8(+) T-cell responses. The route of immunization also greatly influenced the magnitude of the epitope-specific CD8(+) T-cell response. These tissue-specific K(d) Tg mice may be valuable tools for determining the mode of induction of CD8(+) T-cell responses by different APCs in vivo and for characterizing the CD8(+) T-cell responses promoted in response to various microbial infections and/or different types of vaccines.