Brianna Dalesandro

Nature Reviews Microbiology, Published online: 25 March 2021; doi:10.1038/s41579-021-00551-6

This study reports that antigens derived from intracellular bacteria are presented by tumour cells and activate the immune system.

Nature Chemical Biology, Published online: 25 March 2021; doi:10.1038/s41589-021-00770-1

Lysosome-targeting chimeras (LYTACs) based on glycan ligands of the asialoglycoprotein receptor facilitate the cell-specific targeting and turnover of proteins by lysosomal enzymes, expanding the scope of LYTAC-mediated targeted protein degradation.

Nature, Published online: 19 March 2021; doi:10.1038/d41586-021-00766-w

Uptake in the United States has been low, despite several authorised therapies and promising clinical trial results

by Hebang Yao, Hongmin Cai, Tingting Li, Bingjie Zhou, Wenming Qin, Dimitri Lavillette, Dianfan Li

A key step to the SARS-CoV-2 infection is the attachment of its Spike receptor-binding domain (S RBD) to the host receptor ACE2. Considerable research has been devoted to the development of neutralizing antibodies, including llama-derived single-chain nanobodies, to target the receptor-binding motif (RBM) and to block ACE2-RBD binding. Simple and effective strategies to increase potency are desirable for such studies when antibodies are only modestly effective. Here, we identify and characterize a high-affinity synthetic nanobody (sybody, SR31) as a fusion partner to improve the potency of RBM-antibodies. Crystallographic studies reveal that SR31 binds to RBD at a conserved and ‘greasy’ site distal to RBM. Although SR31 distorts RBD at the interface, it does not perturb the RBM conformation, hence displaying no neutralizing activities itself. However, fusing SR31 to two modestly neutralizing sybodies dramatically increases their affinity for RBD and neutralization activity against SARS-CoV-2 pseudovirus. Our work presents a tool protein and an efficient strategy to improve nanobody potency.

Bispecific aptamer chimeras were designed and constructed for lysosomal degradation of targeted membrane‐associated proteins (see picture). The method provides a powerful and potentially universal platform for the use of inexpensive and readily synthesized aptamer materials for the clinical translation of nucleic‐acid‐based molecular medicine.

Abstract

The ability to regulate membrane protein abundance offers great opportunities for developing therapeutic sites for various diseases. Herein, we describe a platform for the targeted degradation of membrane‐associated proteins using bispecific aptamer chimeras that bind both the cell‐surface lysosome‐shuttling receptor (IGFIIR) and the targeted membrane‐bound proteins of interest. We demonstrate that the aptamer chimeras can efficiently and quickly shuttle the therapeutically relevant membrane proteins of Met and PTK‐7 to lysosomes and degrade them through the lysosomal protein degradation machinery. We anticipate that our method will provide a universal platform for the use of readily synthesized aptamer materials for biochemical research and potential therapeutics.

Nature Microbiology, Published online: 26 February 2021; doi:10.1038/s41564-021-00871-6

Bifidobacterium bifidum is enriched in the gut microbiome of patients who respond to cancer treatment, but only selected strains of commercial B. bifidum reduced tumour burden synergistically with therapy in a mouse model.

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Crosstalk Between Staphylococcus aureus and Innate Immunity: Focus on Immunometabolism.

Front Immunol. 2020;11:621750

Authors: Horn CM, Kielian T

Abstract
Staphylococcus aureus is a leading cause of bacterial infections globally in both healthcare and community settings. The success of this bacterium is the product of an expansive repertoire of virulence factors in combination with acquired antibiotic resistance and propensity for biofilm formation. S. aureus leverages these factors to adapt to and subvert the host immune response. With the burgeoning field of immunometabolism, it has become clear that the metabolic program of leukocytes dictates their inflammatory status and overall effectiveness in clearing an infection. The metabolic flexibility of S. aureus offers an inherent means by which the pathogen could manipulate the infection milieu to promote its survival. The exact metabolic pathways that S. aureus influences in leukocytes are not entirely understood, and more work is needed to understand how S. aureus co-opts leukocyte metabolism to gain an advantage. In this review, we discuss the current knowledge concerning how metabolic biases dictate the pro- vs. anti-inflammatory attributes of various innate immune populations, how S. aureus metabolism influences leukocyte activation, and compare this with other bacterial pathogens. A better understanding of the metabolic crosstalk between S. aureus and leukocytes may unveil novel therapeutic strategies to combat these devastating infections.

PMID: 33613555 [PubMed - in process]

Nature Reviews Microbiology, Published online: 19 February 2021; doi:10.1038/s41579-021-00532-9

This study shows that one mechanism of immune evasion used by Staphylococcus aureus involves a virulence factor, SpA, which can block complement activation by inhibiting IgG oligomerization.

Nature Communications, Published online: 22 February 2021; doi:10.1038/s41467-021-21410-1

Programmed death-ligand 1 (PD-L1) is involved in the inhibition of antigen specific T cells via ligation of programmed death 1 (PD-1). Here, the authors show checkpoint inhibition by use of small molecule inhibition of PD-L1 which in a humanised mouse model was shown to restore T cell responses and reduced tumour burden.

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The Application of Nanobody in CAR-T Therapy.

Biomolecules. 2021 Feb 08;11(2):

Authors: Bao C, Gao Q, Li LL, Han L, Zhang B, Ding Y, Song Z, Zhang R, Zhang J, Wu XH

Abstract
Chimeric antigen receptor (CAR) T therapy represents a form of immune cellular therapy with clinical efficacy and a specific target. A typical chimeric antigen receptor (CAR) construct consists of an antigen binding domain, a transmembrane domain, and a cytoplasmic domain. Nanobodies have been widely applied as the antigen binding domain of CAR-T due to their small size, optimal stability, high affinity, and manufacturing feasibility. The nanobody-based CAR structure has shown a proven function in more than ten different tumor-specific targets. After being transduced in Jurkat cells, natural killer cells, or primary T cells, the resulting nanobody-based CAR-T or CAR-NK cells demonstrate anti-tumor effects both in vitro and in vivo. Interestingly, anti-BCMA CAR-T modulated by a single nanobody or bi-valent nanobody displays comparable clinical effects with that of single-chain variable fragment (scFv)-modulated CAR-T. The application of nanobodies in CAR-T therapy has been well demonstrated from bench to bedside and displays great potential in forming advanced CAR-T for more challenging tasks.

PMID: 33567640 [PubMed - in process]

Pseudomonas aeruginosa and Staphylococcus aureus have clearly a difficult relationship. In this review, we discuss recent advances in regard to their interactions, physical responses, and how researchers study them in the laboratory and in animal models.

Abstract

Pseudomonas aeruginosa (Pa) and Staphylococcus aureus (Sa) are opportunistic pathogens that are most commonly co-isolated from chronic wounds and the sputum of cystic fibrosis patients. Over the last few years, there have been plenty of contrasting results from studies involving P. aeruginosa and S. aureus co-cultures. The general concept that P. aeruginosa outcompetes S. aureus has been challenged and there is more evidence now that they can co-exist. Nevertheless, it still remains difficult to mimic polymicrobial infections in vitro and in vivo. In this review, we discuss recent advances in regard to Pa-Sa molecular interactions, their physical responses, and in vitro and in vivo models. We believe it is important to optimize growth conditions in the laboratory, determine appropriate bacterial starting ratios, and consider environmental factors to study the co-existence of these two pathogens. Ideally, optimized growth media should reflect host-mimicking conditions with or without host cells that allow both bacteria to co-exist. To further identify mechanisms that could help to treat these complex infections, we propose to use relevant polymicrobial animal models. Ultimately, we briefly discuss how polymicrobial infections can increase antibiotic tolerance.

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CAR-T cell-mediated depletion of immunosuppressive tumor-associated macrophages promotes endogenous antitumor immunity and augments adoptive immunotherapy.

Nat Commun. 2021 02 09;12(1):877

Authors: Rodriguez-Garcia A, Lynn RC, Poussin M, Eiva MA, Shaw LC, O'Connor RS, Minutolo NG, Casado-Medrano V, Lopez G, Matsuyama T, Powell DJ

Abstract
The immunosuppressive tumor microenvironment (TME) represents a major barrier for effective immunotherapy. Tumor-associated macrophages (TAMs) are highly heterogeneous and plastic cell components of the TME which can either promote tumor progression (M2-like) or boost antitumor immunity (M1-like). Here, we demonstrate that a subset of TAMs that express folate receptor β (FRβ) possess an immunosuppressive M2-like profile. In syngeneic tumor mouse models, chimeric antigen receptor (CAR)-T cell-mediated selective elimination of FRβ+ TAMs in the TME results in an enrichment of pro-inflammatory monocytes, an influx of endogenous tumor-specific CD8+ T cells, delayed tumor progression, and prolonged survival. Preconditioning of the TME with FRβ-specific CAR-T cells also improves the effectiveness of tumor-directed anti-mesothelin CAR-T cells, while simultaneous co-administration of both CAR products does not. These results highlight the pro-tumor role of FRβ+ TAMs in the TME and the therapeutic implications of TAM-depleting agents as preparative adjuncts to conventional immunotherapies that directly target tumor antigens.

PMID: 33563975 [PubMed - in process]

Immunoglobulin (Ig) G molecules are essential players in the human immune response against bacterial infections. An important effector of IgG-dependent immunity is the induction of complement activation, a reaction that triggers a variety of responses that help kill bacteria. Antibody-dependent complement activation is promoted by the organization of target-bound IgGs...

We report the use of a chemoenzymatic glycocalyx editing strategy to create CD22‐specific ligands and sialyl Lewis X on NK cells (NK‐92MI or CIK cells) to target and eradicate B‐lymphoma efficiently.

Abstract

CD22, a member of Siglec family of sialic acid binding proteins, has restricted expression on B cells. Antibody‐based agents targeting CD22 or CD20 on B lymphoma and leukemia cells exhibit clinical efficacy for treating these malignancies, but also attack normal B cells leading to immune deficiency. Here, we report a chemoenzymatic glycocalyx editing strategy to introduce high‐affinity and specific CD22 ligands onto NK‐92MI and cytokine‐induced natural killer cells to achieve tumor‐specific CD22 targeting. These CD22‐ligand modified cells exhibited significantly enhanced tumor cell binding and killing in vitro without harming healthy B cells. For effective lymphoma cell killing in vivo, we further functionalized CD22 ligand‐modified NK‐92MI cells with the E‐selectin ligand sialyl Lewis X to promote trafficking to bone marrow. The dual‐functionalized cells resulted in the efficient suppression of B lymphoma in a xenograft model. Our results suggest that natural killer cells modified with glycan ligands to CD22 and selectins promote both targeted killing of B lymphoma cells and improved trafficking to sites where the cancer cells reside, respectively.

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Oral administration of Bifidobacterium breve promotes antitumor efficacy via dendritic cells-derived interleukin 12.

Oncoimmunology. 2021 Jan 15;10(1):1868122

Authors: Li Q, Li Y, Wang Y, Xu L, Guo Y, Wang Y, Wang L, Guo C

Abstract
Recent advances in immunotherapy, as a part of the multidisciplinary therapy, has gradually gained more attention. However, only a small proportion of patients who sensitive to the therapy could gain benefits. An increasing number of studies indicate that intestinal microbiota could enhance the efficiency of cancer immunotherapy. As one of the main probiotics, Bifidobacterium plays an important role in immune regulation, which has been proved by animal research and human clinical study. But the detailed mechanism was not clearly elucidated. Here we found oral administration of Bifidobacterium breve (B. breve) lw01 could significantly inhibit tumor growth and up-regulate tumor cell apoptosis, which relied on the recruitment of tumor-infiltrating lymphocytes and dendritic cells (DCs) in tumor microenvironment, but not Lactobacillus rhamnosus (L. rhamnosus) CGMCC 1.3724 or Escherichia coli (E. coli) MG1655. In the in situ ligated intestine loop model, B. breve's stimulation triggered the upregulated expression of DC-related chemokine CCL20 and recruited more DCs in the intestinal villi. Further study revealed the enhancement of interleukin 12 (IL-12) secretion derived from DCs is essential to B. breve's antitumor effect, which was counteracted by the treatment of neutralizing antibody for IL-12. Meanwhile, the modulation of intestinal microbiota caused by exogenous B. breve might enhance its antitumor effect. This study provides a simple and easy way to promote antitumor immunity via B. breve.

PMID: 33537172 [PubMed - in process]

Cell wall glycosylation in Staphylococcus aureus: targeting the tar glycosyltransferases.

Curr Opin Struct Biol. 2021 Feb 01;68:166-174

Authors: Guo Y, Pfahler NM, Völpel SL, Stehle T

Abstract
Peptidoglycan (PG) is the major structural polymer of the bacterial cell wall. The PG layer of gram-positive bacterial pathogens such as Staphylococcus aureus (S. aureus) is permeated with anionic glycopolymers known as wall teichoic acids (WTAs) and lipoteichoic acids (LTAs). In S. aureus, the WTA backbone typically consists of repeating ribitol-5-phosphate units, which are modified by enzymes that introduce glycosylation as well as amino acids at different locations. These modifications are key determinants of phage adhesion, bacterial biofilm formation and virulence of S. aureus. In this review, we examine differences in WTA structures in gram-positive bacteria, focusing in particular on three enzymes, TarM, TarS, and TarP that glycosylate the WTA of S. aureus at different locations. Infections with S. aureus pose an increasing threat to human health, particularly through the emergence of multidrug-resistant strains. Recently obtained structural information on TarM, TarS and TarP has helped to better understand the strategies used by S. aureus to establish resistance and to evade host defense mechanisms. Moreover, structures of complexes with poly-RboP and its analogs can serve as a platform for the development of new inhibitors that could form a basis for the development of antibiotic agents.

PMID: 33540375 [PubMed - as supplied by publisher]

Pt^II complexes containing a payload, a bidentate ligand, and a halido leaving ligand (Cl⁻, Br⁻ or I⁻) can be conjugated to native monoclonal antibodies in a very efficient way by using iodide salts, such as NaI, as simple inorganic additives to the aqueous conjugation mixtures. This method works reliably for various mAbs, consistently giving conjugation efficiencies in the range of 75–90 %.

Abstract

The Pt^II linker [ethylenediamineplatinum(II)]²⁺, coined Lx, has emerged as a novel non‐conventional approach to antibody–drug conjugates (ADCs) and has shown its potential in preclinical in vitro and in vivo benchmark studies. A crucial improvement of the Lx conjugation reaction from initially <15 % to ca. 75–90 % conjugation efficiency is described, resulting from a systematic screening of all relevant reaction parameters. NaI, a strikingly simple inorganic salt additive, greatly improves the conjugation efficiency as well as the conjugation selectivity simply by exchanging the leaving chloride ligand on Cl‐Lx‐drug complexes (which are direct precursors for Lx‐ADCs) for iodide, thus generating I‐Lx‐drug complexes as more reactive species. Using this iodide effect, we developed a general and highly practical conjugation procedure that is scalable: our lead Lx‐ADC was produced on a 5 g scale with an outstanding conjugation efficiency of 89 %.

An AIE‐Lipid conjugate was designed to offer ultrafast, wash‐free and biocompatible labeling of neutrophils for their in vitro and in vivo behavior monitoring.

Abstract

Studies on neutrophil‐based nanotherapeutic engineering have shown great potentials in treating infection and inflammation disorders. Conventional neutrophil labeling methods are time‐consuming and often result in undesired contamination and activation since neutrophils are terminal‐differentiated cells with a half‐life span of only 7 h. A simple, fast, and biocompatible strategy to construct engineered neutrophils is highly desirable but remains difficult to achieve. In this study, we present an AIEgen‐lipid conjugate, which can efficiently label harvested neutrophils in 30 s with no washing step required. This fast labeling method does not affect the activation and transmigration property of neutrophils, which has been successfully used to monitor neutrophil behaviors such as the chemotaxis process and migrating function towards inflammation sites both in vitro and in vivo, offering a tantalizing prospect for neutrophil‐based nanotherapeutics studies.