Brianna Dalesandro

Bacterial Outer Membrane Vesicles Presenting Programmed Death 1 for Improved Cancer Immunotherapy via Immune Activation and Checkpoint Inhibition.

ACS Nano. 2020 Nov 24;:

Authors: Li Y, Zhao R, Cheng K, Zhang K, Wang Y, Zhang Y, Li Y, Liu G, Xu J, Xu J, Anderson GJ, Shi J, Ren L, Zhao X, Nie G

Abstract
Natural, extracellular membrane vesicles secreted by Gram-negative bacteria, outer membrane vesicles (OMVs), contain numerous pathogen-associated molecular patterns which can activate systemic immune responses. Previous studies have shown that OMVs induce strong IFN-γ- and T cell-mediated anti-tumor effects in mice. However, IFN-γ is known to upregulate immunosuppressive factors in the tumor microenvironment, especially the immune checkpoint programmed death 1 ligand 1 (PD-L1), which may hamper T cell function and limit immunotherapeutic effectiveness. Here, we report the development of genetically engineered OMVs whose surface has been modified by insertion of the ectodomain of programmed death 1 (PD1). This genetic modification does not affect the ability of OMVs to trigger immune activation. More importantly, the engineered OMV-PD1 can bind to PD-L1 on the tumor cell surface and facilitate its internalization and reduction, thereby protecting T cells from the PD1/PD-L1 immune inhibitory axis. Through the combined effects of immune activation and checkpoint suppression, the engineered OMVs drive the accumulation of effector T cells in the tumor, which, in turn, leads to a greater impairment of tumor growth, compared with not only native OMVs but also the commonly used PD-L1 antibody. In conclusion, this work demonstrates the potential of bioengineered OMVs as effective immunotherapeutic agents that can comprehensively regulate the tumor immune microenvironment to effect markedly increased anti-tumor efficacy.

PMID: 33232124 [PubMed - as supplied by publisher]

Staphylococcus aureus Protein A Induces Human Regulatory T Cells Through Interaction With Antigen-Presenting Cells.

Front Immunol. 2020;11:581713

Authors: Uebele J, Habenicht K, Ticha O, Bekeredjian-Ding I

Abstract
Despite continuous exposure and development of specific immunity, Staphylococcus aureus (Sa) remains one of the leading causes of severe infections worldwide. Although innate immune defense mechanisms are well understood, the role of the T cell response has not been fully elucidated. Here, we demonstrate that Sa and one of its major virulence factors protein A (SpA) induce human regulatory T cells (Tregs), key players in immune tolerance. In human PBMC and MoDC/T cell cocultures CD4+CD25+CD127dim Tregs were induced upon stimulation with Sa and to a lower extent with SpA alone. Treg induction was strongly, but not exclusively, dependent on SpA, and independent of antigen presentation or T cell epitope recognition. Lastly, soluble factors in the supernatant of SpA-stimulated MoDC were sufficient to trigger Treg formation, while supernatants of MoDC/T cell cocultures containing Sa-triggered Tregs displayed T cell suppressive activity. In summary, our findings identify a new immunosuppressory function of SpA, which leads to release of soluble, Treg-inducing factors and might be relevant to establish colonization.

PMID: 33117390 [PubMed - in process]

Natural Killer Cells in Immunotherapy: Are We Nearly There?

Cancers (Basel). 2020 Oct 27;12(11):

Authors: Bachiller M, Battram AM, Perez-Amill L, Martín-Antonio B

Abstract
Natural killer (NK) cells are potent anti-tumor and anti-microbial cells of our innate immune system. They are equipped with a vast array of receptors that recognize tumor cells and other pathogens. The innate immune activity of NK cells develops faster than the adaptive one performed by T cells, and studies suggest an important immunoregulatory role for each population against the other. The association, observed in acute myeloid leukemia patients receiving haploidentical killer-immunoglobulin-like-receptor-mismatched NK cells, with induction of complete remission was the determinant to begin an increasing number of clinical studies administering NK cells for the treatment of cancer patients. Unfortunately, even though transfused NK cells demonstrated safety, their observed efficacy was poor. In recent years, novel studies have emerged, combining NK cells with other immunotherapeutic agents, such as monoclonal antibodies, which might improve clinical efficacy. Moreover, genetically-modified NK cells aimed at arming NK cells with better efficacy and persistence have appeared as another option. Here, we review novel pre-clinical and clinical studies published in the last five years administering NK cells as a monotherapy and combined with other agents, and we also review chimeric antigen receptor-modified NK cells for the treatment of cancer patients. We then describe studies regarding the role of NK cells as anti-microbial effectors, as lessons that we could learn and apply in immunotherapy applications of NK cells; these studies highlight an important immunoregulatory role performed between T cells and NK cells that should be considered when designing immunotherapeutic strategies. Lastly, we highlight novel strategies that could be combined with NK cell immunotherapy to improve their targeting, activity, and persistence.

PMID: 33120910 [PubMed]

Development of Antiviral Vaccine Utilizing Self-Destructing Salmonella for Antigen and DNA Vaccine Delivery.

Methods Mol Biol. 2021;2225:39-61

Authors: Kong W

Abstract
Vaccines are the most effective means to prevent infectious diseases, especially for viral infection. The key to an excellent antiviral vaccine is the ability to induce long-term protective immunity against a specific virus. Bacterial vaccine vectors have been used to impart protection against self, as well as heterologous antigens. One significant benefit of using live bacterial vaccine vectors is their ability to invade and colonize deep effector lymphoid tissues after mucosal delivery. The bacterium Salmonella is considered the best at this deep colonization. This is critically essential for inducing protective immunity. This chapter describes the methodology for developing genetically modified self-destructing Salmonella (GMS) vaccine delivery systems targeting influenza infection. Specifically, the methods covered include the procedures for the development of GMSs for protective antigen delivery to induce cellular immune responses and DNA vaccine delivery to induce systemic immunity against the influenza virus. These self-destructing GMS could be modified to provide effective biological containment for genetically engineered bacteria used for a diversity of purposes in addition to vaccines.

PMID: 33108656 [PubMed - as supplied by publisher]

Better biomaterials: A multifunctional platform containing a cyclic RGD motif and an antimicrobial peptide, presented using finely tuned spacing units, was found to achieve optimal cell adhesive and bacterial inhibition properties. Anchorage to a biomaterial surface through catechol groups enabled a straightforward functionalization of an implant surface.

Abstract

Bacterial infections and incomplete biomaterial integration are major problems that can lead to the failure of medical implants. However, simultaneously addressing these two issues remains a challenge. Here, we present a chemical peptide library based on a multifunctional platform containing the antimicrobial peptide LF1‐11 and the cell‐adhesive motif RGD. The scaffolds were customized with catechol groups to ensure straightforward functionalization of the implant surface, and linkers of different length to assess the effect of peptide accessibility on the biological response. The peptidic platforms significantly improved the adhesion of mesenchymal stem cells and showed antimicrobial effects against Staphylococcus aureus. Of note is that peptides bearing spacers that were too long displayed the lowest efficiency. Subsequently, we designed a platform replacing linear RGD by cyclic RGD; this further enhanced eukaryotic cell adhesion while retaining excellent antimicrobial properties, thus being a suitable candidate for tissue engineering applications.

A nucleic acid nanoplatform‐based co‐delivery system containing a pair of functionalized branched antisenses and siRNA with 3′ overhangs was constructed through controlled co‐assembly for combined gene silencing and tumor therapy in vivo.

Abstract

Chemically modified DNA has been widely developed to fabricate various nucleic acid nanostructures for biomedical applications. Herein, we report a facile strategy for construction of branched antisense DNA and small interfering RNA (siRNA) co‐assembled nanoplatform for combined gene silencing in vitro and in vivo. In our design, the branched antisense can efficiently capture siRNA with 3′ overhangs through DNA–RNA hybridization. After being equipped with an active targeting group and an endosomal escape peptide by host–guest interaction, the tailored nucleic acid nanostructure functions efficiently as both delivery carrier and therapeutic cargo, which is released by endogenous RNase H digestion. The multifunctional nucleic acid nanosystem elicits an efficient inhibition of tumor growth based on the combined gene silencing of the tumor‐associated gene polo‐like kinase 1 (PLK1). This biocompatible nucleic acid nanoplatform presents a new strategy for the development of gene therapy.

Uncovering Unappreciated Activities and Niche Functions of Bacterial Cell Wall Enzymes.

Curr Biol. 2020 Oct 05;30(19):R1170-R1175

Authors: Daitch AK, Goley ED

Abstract
A peptidoglycan (PG) cell wall is an essential component of nearly all bacteria, providing protection against turgor pressure. Metabolism of this PG meshwork must be spatially and temporally regulated in order to support cell growth and division. Despite being an active area of research for decades, we have only recently identified the primary PG synthesis complexes that function during cell elongation (RodA-PBP2) and cell division (FtsW-FtsI), and we are still uncovering the importance of the other seemingly redundant cell wall enzymes. In this minireview, we highlight the discovery of the monofunctional glycosyltransferases RodA and FtsW and describe how these findings have prompted a re-evaluation of the auxiliary role of the bifunctional class A penicillin-binding proteins (aPBPs) as well as the L,D-transpeptidases (LDTs). Specifically, recent work indicates that the aPBPs and LDTs function independently of the primary morphogenetic complexes to support growth, provide protection from stresses, mediate morphogenesis, and/or allow adaptation to different growth conditions. These paradigm-shifting studies have reframed our understanding of bacterial cell wall metabolism, which will only become more refined as emerging technology allows us to tackle the remaining questions surrounding PG biosynthesis.

PMID: 33022262 [PubMed - as supplied by publisher]

Related Articles

SnoopLigase peptide-peptide conjugation enables modular vaccine assembly.

Sci Rep. 2019 03 15;9(1):4625

Authors: Andersson AC, Buldun CM, Pattinson DJ, Draper SJ, Howarth M

Abstract
For many infectious diseases there is still no vaccine, even though potential protective antigens have been identified. Suitable platforms and conjugation routes are urgently needed to convert the promise of such antigens into broadly protective and scalable vaccines. Here we apply a newly established peptide-peptide ligation approach, SnoopLigase, for specific and irreversible coupling of antigens onto an oligomerization platform. SnoopLigase was engineered from a Streptococcus pneumoniae adhesin and enables isopeptide bond formation between two peptide tags: DogTag and SnoopTagJr. We expressed in bacteria DogTag linked to the self-assembling coiled-coil nanoparticle IMX313. This platform was stable over months at 37 °C when lyophilized, remaining reactive even after boiling. IMX-DogTag was efficiently coupled to two blood-stage malarial proteins (from PfEMP1 or CyRPA), with SnoopTagJr fused at the N- or C-terminus. We also showed SnoopLigase-mediated coupling of a telomerase peptide relevant to cancer immunotherapy. SnoopLigase-mediated nanoassembly enhanced the antibody response to both malaria antigens in a prime-boost model. Including or depleting SnoopLigase from the conjugate had little effect on the antibody response to the malarial antigens. SnoopLigase decoration represents a promising and accessible strategy for modular plug-and-display vaccine assembly, as well as providing opportunities for robust nanoconstruction in synthetic biology.

PMID: 30874593 [PubMed - indexed for MEDLINE]

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Eradication of Vancomycin-Resistant Enterococci by Combining Phage and Vancomycin.

Viruses. 2019 10 16;11(10):

Authors: Shlezinger M, Coppenhagen-Glazer S, Gelman D, Beyth N, Hazan R

Abstract
Currently, effective options are needed to fight vancomycin-resistant Enterococcus faecalis (VRE). The present study shows that combinations of phage and vancomycin are highly efficient against VRE, despite being resistant to the antibiotic. Vancomycin-phage EFLK1 (anti-E. faecalis phage) synergy was assessed against VRE planktonic and biofilm cultures. The effect of the combined treatment on VRE biofilms was determined by evaluating the viable counts and biomass and then visualized using scanning electron microscopy (SEM). The cell wall peptidoglycan was stained after phage treatment, visualized by confocal microscopy and quantified by fluorescence activated cell sorting (FACS) analysis. The combined treatment was synergistically effective compared to treatment with phage or antibiotic alone, both in planktonic and biofilm cultures. Confocal microscopy and FACS analysis showed that fluorescence intensity of phage-treated bacteria increased eight-fold, suggesting a change in the peptidoglycan of the cell wall. Our results indicate that with combined treatment, VRE strains are not more problematic than sensitive strains and thus give hope in the continuous struggle against the current emergence of multidrug resistant pathogens.

PMID: 31623253 [PubMed - indexed for MEDLINE]

A JMV594‐conjugated iridium(III) complex is presented as a long‐lived, potent and selective imaging probe for GRPr in GRPr‐positive living cancer cells. This probe enables the discrimination of GRPr‐positive cancer cells from normal cells, while it is also capable of probing the modulatory functions of GRPr in immune cells.

Abstract

Gastrin‐releasing peptide receptor (GRPr) plays proliferative and inflammatory roles in living systems. Here, we report a highly selective GRPr antagonist (JMV594)‐tethered iridium(III) complex for probing GRPr in living cancer cells and immune cells. This probe exhibited desirable photophysical properties and also displayed negligible cytotoxicity, overcoming the inherent toxicity of the iridium(III) complex. Its long emission lifetime enabled its luminescence signal to be readily distinguished from the interfering fluorescence of organic dyes by using a time‐resolved technique. This probe selectively visualized living cancer cells via specific binding to GRPr, while it also modulated the function of GRPr on TNF‐α secretion in immune cells. To our knowledge, this is the first peptide‐conjugated iridium(III) complex developed as a GRPr bioimaging probe and modulator of GRPr activity. This theranostic agent shows great potential at unmasking the diverse roles of GRPr in living systems.

A co‐assembled vaccine, composed of lipidated antigens and lipophilic adjuvants, is reported. This vaccine design possesses both antigen multivalency and antigen‐specific immunostimulation properties, and induces a robust immune response. This simple vaccine initiated a potent immune response without requiring complex synthesis, allowing efficient and practical development of self‐adjuvanting vaccines.

Abstract

Co‐assembling vaccines composed of a lipidated HER2‐derived antigenic CH401 peptide and either a lipophilic adjuvant, Pam₃CSK₄, α‐GalCer, or lipid A 506, were evaluated as breast cancer vaccine candidates. This vaccine design was aimed to inherit both antigen multivalency and antigen‐specific immunostimulation properties, observed in reported self‐adjuvanting vaccine candidates, by using self‐assembly and adjuvant‐conjugated antigens. Under vaccination concentrations, respective lipophilic adjuvants underwent co‐assembly with lipidated CH401, which boosted the anti‐CH401 IgG and IgM production. In particular, α‐GalCer was responsible for the most significant immune activation. Therefore, the newly developed vaccine design enabled the optimization of adjuvants against the antigenic CH401 peptide in a simple preparatory manner. Overall, the co‐assembling vaccine design opens the door for efficient and practical self‐adjuvanting vaccine development.

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Immunization with a peptide mimicking Lipoteichoic acid protects mice against Staphylococcus aureus infection.

Vaccine. 2019 07 18;37(31):4325-4335

Authors: Yi XY, Huang ZX, Hou XR, Zhu P, Wang XY, Luo HB, Liu BY

Abstract
Lipoteichoic acid (LTA), a major component of the cell wall of Staphylococcus aureus (S. aureus), is not generally considered as an ideal vaccine candidate since it is a thymus-independent antigen. In this study, we screened a 12-mer phage peptide library and identified a series of peptide sequences that can mimic the epitope of LTA. A tetra-branched multiple antigenic peptide, named MAP2-3, comprising one of the positive peptide sequences (GHKEDRQWCQHS), was synthesized. Immunization with MAP2-3 induced LTA-specific IgG antibodies, prolonged the survival time, and decreased the bacterial burden in organs of mice infected with S. aureus. Moreover, passive immunization with polyclonal anti-MAP2-3 sera reduced bacterial load in organs of mice with bacteremia, alleviated acute lung injury in mice with pneumonia, and decreased the size of lesions in mice with skin infection. The number of LTA-specific antibody-secreting cells in the spleen of MAP2-3 immunized mice were significantly higher than that in the control mice. In summary, as a surrogate of LTA, vaccination with MAP2-3 elicited humoral immune response and protected mice from S. aureus infection. This study provides a new option to design vaccines against S. aureus.

PMID: 31230882 [PubMed - indexed for MEDLINE]