Heterologous peptide display on chromatin nanofibers: A new strategy for peptide vaccines

The multiple arrays of a PD1-derived peptide on chromatin specifically bind to PD-L1 and induce doxorubicin resistance in cancer cell lines

Programmed cell death-1 (PD-1) and its ligand 1 (PD-L1) have been extensively studied to block the activation of the PD-1 axis immune checkpoint pathway on T cells. However, recent evidence suggests that PD-1-independent PD-L1 pathways in cancer cells and macrophages are important in cellular proliferation and survival of those cell types but the underlying mechanism is little understood. To recapitulate the binding of multiple PD-1 to the high levels of PD-L1 expression on cancer cell membranes, recombinant histones carrying a PD-1 receptor-derived peptide (PDR) were prepared and used to assemble a PDR-displayed nucleosome array. PDR-displayed chromatin showed physiologically spaced nucleosomes, unaffected by N-terminal histone tails and biotinylated DNA modifications. PDR-displayed chromatin exhibited selective binding to the breast cancer cell line with high PD-L1 expression, MDA-MB-231, where saturated binding occurred within 3 h, comparable to well-known antigen-antibody reactions. Notably, PDR-displayed chromatin enhanced resistance to doxorubicin in PD-L1-overexpressed cancer cells, revealing a PD-L1 level-dependent effect on cell survival upon chemotherapy. Our study sheds light on the potential of PDR-displayed chromatin as a tool to induce chemoresistance in cancer cells without employing anti-PD-L1 antibodies or soluble PD-1 receptors. Further investigation into the underlying signaling pathways and therapeutic applications is warranted, positioning PDR-displayed chromatin as a valuable tool for understanding PD-L1-mediated intracellular signaling pathways in cancer cells with high PD-L1 expression.

Applications of nanoengineered therapeutics and vaccines: special emphasis on COVID-19

Nanomedicine provides innovative strategies that had significantly improved drug and gene delivery and allowed control over the engineering of therapeutics, diagnostics, vaccines, and other medical devices, for a diversity of medical applications. This review focuses on the current attempts to develop potent nanoengineered vaccines and therapeutics against coronaviruses, and the recent fabrication strategies and design principles to control acute infections from the escalating SARS-CoV-2 pandemic. Nanomedical approaches provide versatile platforms that can be utilized to enhance the overall potency, safety, and stability of vaccines, thus augmenting the desired immune response. Their modulable conformational features of size, shape, surface charge, antigen display, and composition allow for precise tuning and optimization of the nanoconstructs for the management of a variety of diseases and pathological conditions. The ability to control the release of their encapsulated cargoes and the possibility of surface decoration with various moieties support the construction of multifunctional nanomaterials that ultimately boost and prolong the immune response elicited and/or therapeutic effects, selectively at the diseased tissues and target sites.