Zhigang Lu

The immunosuppressive tumor microenvironment remains a major obstacle to successful immunotherapy. Pathologically activated neutrophils, alternatively termed polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), drive tumor immune evasion primarily by inducing CD8⁺ T cell tolerance. While direct intercellular contact between neutrophils and CD8⁺ T cells is essential for immunosuppressive activity, the mechanisms mediating this interaction need deeper understanding. We previously reported that CD300ld is required for recruiting PMN-MDSCs into tumors, suppressing T cell activation. Here we show that CD300ld mediates neutrophil-driven contact-dependent suppression of cytotoxic CD8⁺ T cells by binding to phosphatidylserine (PS). Mice with mutant CD300ld lacking PS-binding capacity exhibit reduced immunosuppressive activity. Blockade of the CD300ld-PS interaction by neutralizing antibodies demonstrates therapeutic efficacy against established tumors and synergizes with anti-PD1. Our findings establish CD300ld-PS-mediated cell contact as a critical mechanism of neutrophil-driven immune evasion, revealing a targetable checkpoint pathway to overcome tumor immune resistance and improve immunotherapy outcomes.

Background: While cancer vaccines have demonstrated promising clinical potential, their therapeutic efficacy against advanced tumors remains suboptimal, highlighting the critical need to elucidate resistance mechanisms and develop targeted solutions. We previously developed a stimulator of interferon genes (STING)-activating PC7A nanovaccine that elicits strong antitumor efficacy in multiple tumor models. In this study, we systematically investigated the mechanisms mediating nanovaccine resistance and provided targeting approaches to overcome this therapeutic barrier. Methods: Vaccine efficacy at early stage and advanced-stage tumors was investigated in the B16-OVA melanoma model and TC-1 human papillomavirus-induced cancer model, with tumor microenvironment being comprehensively analyzed by flow cytometry. In a vaccine-resistant tumor, elevated immunosuppressive activity of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) was assessed through multi-analysis including surface marker staining, reverse transcription-quantitative PCR, and functional T cell-suppression assay. To investigate the CD300ld blockade strategy, we employed CD300ld-knockout (KO) mice for genetic ablation, or recombinant protein capable of competitive inhibition for pharmacological intervention. For clinical relevance assessment, we tested different cancer vaccine formulations at late-stage tumors in humanized-CD3000ld mice. Results: In contrast to early stage vaccination, PC7A nanovaccine administration at the late tumor stage exhibited minimal therapeutic effects on tumor progression, while concurrently increasing PMN-MDSC infiltration and enhancing their immunosuppressive activity. KO of CD300ld, a critical immune suppressor on PMN-MDSCs, abolished both PMN-MDSC recruitment and their T-cell suppressive function, restoring the antitumor efficacy of PC7A vaccine in multiple advanced tumor models. Furthermore, in wild-type and CD300ld humanized mouse models, competitive blockade of CD300ld using recombinant extracellular domain proteins overcame resistance of advanced tumors to different cancer vaccine formulations. Conclusion: Our results reveal that vaccination at the late tumor stage significantly augments the recruitment and immunosuppressive capacity of PMN-MDSCs, driving resistance of advanced tumors to cancer vaccines. The findings demonstrate PMN-MDSCs as critical mediators of vaccine resistance in advanced tumors and highlight modulation of PMN-MDSCs by CD300ld blockade as a promising strategy to enhance the therapeutic efficacy of cancer vaccines, particularly for patients with late-stage malignancies.

Personalized cancer vaccines elicit robust T cell immunity and anti-tumour potency, but identifying tumour-specific antigens remains challenging, severely constraining the therapeutic window. Biomimetic nanovaccines employing cancer cell membranes display inherent biocompatibility and stimulate T-cell responses against diverse tumour antigens, though tumours develop multiple mechanisms to reduce antigen presentation. Here we demonstrate a rapid and general strategy to fabricate personalized nanovaccines based on Antigen-Enriched tumor Cell Membranes (AECM) for early intervention. Interferon-γ potently stimulates antigen presentation across a broad range of cancer cell types. By coupling the generated AECM with PC7A adjuvant, a stimulator of interferon genes (STING)-activating polymer, the AECM@PC7A nanovaccine induces robust poly-neoepitopic T-cell responses even at low dosage, achieving significant tumour regression and metastasis inhibition in multiple murine cancer models. This anti-tumor response relies on MHC-I restricted antigen presentation and CD8⁺ T-cell activation, with dendritic cells presenting AECM antigens predominantly via cross-dressing to prime T-cells. AECM@PC7A exhibits remarkable anti-tumor efficacy when compared to vaccines with diverse formulations, and demonstrates therapeutic potential in post-surgical and humanized xenograft tumor models. This proof-of-concept study provides a promising universal avenue for the rapid development of personalized cancer vaccines applicable to early intervention for a broad range of patients.

The secretome is composed of cell surface membrane proteins and extracellular secreted proteins that are synthesized via secretory machinery, accounting for approximately one-third of human protein-encoding genes and playing central roles in cellular communication with the external environment. Secretome protein–protein interactions (SPPIs) mediate cell proliferation, apoptosis, and differentiation, as well as stimulus- or cell-specific responses that regulate a diverse range of biological processes. Aberrant SPPIs are associated with diseases including cancer, immune disorders, and illness caused by infectious pathogens. Identifying the receptor/ligand for a secretome protein or pathogen can be a challenging task, and many SPPIs remain obscure, with a large number of orphan receptors and ligands, as well as viruses with unknown host receptors, populating the SPPI network. In addition, proteins with known receptors/ligands may also interact with alternative uncharacterized partners and exert context-dependent effects. In the past few decades, multiple varied approaches have been developed to identify SPPIs, and these methods have broad applications in both basic and translational research. Here, we review and discuss the technologies for SPPI profiling and the application of these technologies in identifying novel targets for immunotherapy and anti-infectious agents.

The immune-suppressive tumour microenvironment represents a major obstacle to effective immunotherapy^1,2. Pathologically activated neutrophils, also known as polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), are a critical component of the tumour microenvironment and have crucial roles in tumour progression and therapy resistance^2,3,4. Identification of the key molecules on PMN-MDSCs is required to selectively target these cells for tumour treatment. Here, we performed an in vivo CRISPR–Cas9 screen in a tumour mouse model and identified CD300ld as a top candidate of tumour-favouring receptors. CD300ld is specifically expressed in normal neutrophils and is upregulated in PMN-MDSCs upon tumour-bearing. CD300ld knockout inhibits the development of multiple tumour types in a PMN-MDSC–dependent manner. CD300ld is required for the recruitment of PMN-MDSCs into tumours and their function to suppress T cell activation. CD300ld acts via the STAT3-S100A8/A9 axis, and knockout of Cd300ld reverses the tumour immune-suppressive microenvironment. CD300ld is upregulated in human cancers and shows an unfavourable correlation with patient survival. Blocking CD300ld activity inhibits tumour development and has synergistic effects with anti-PD1. Our study identifies CD300ld as a critical immune suppressor present on PMN-MDSCs, being required for tumour immune resistance and providing a potential target for cancer immunotherapy.

Background: Oligodendrocytes have robust regenerative ability and are key players in remyelination during physiological and pathophysiological states. However, the mechanisms of brain microenvironmental cue in regulation of the differentiation of oligodendrocytes still needs to be further investigated.Results: We demonstrated that myelin-associated glycoprotein (MAG) was a novel receptor for angiopoietin-like protein 2 (ANGPTL2). The binding of ANGPTL2 to MAG efficiently promoted the differentiation of oligodendrocytes in vitro, as evaluated in an HCN cell line.Angptl2-null mice had a markedly impaired myelination capacity in the early stage of oligodendrocyte development. These mice had notably decreased remyelination capacities and enhanced motor disability in a cuprizone-induced demyelinating mouse model, which was similar to theMag-null mice. The loss of remyelination ability inAngptl2-null/Mag-null mice was similar to theAngptl2-WT/Mag-null mice, which indicated that the ANGPTL2-mediated oligodendrocyte differentiation effect depended on the MAG receptor. ANGPTL2 bound MAG to enhance its phosphorylation level and recruit Fyn kinase, which increased Fyn phosphorylation levels, followed by the transactivation of myelin regulatory factor (MYRF).Conclusion: Our study demonstrated an unexpected cross-talk between the environmental protein (ANGPTL2) and its surface receptor (MAG) in the regulation of oligodendrocyte differentiation, which may benefit the treatment of many demyelination disorders, including multiple sclerosis.