Nano-Immune-Engineering Approaches to Advance Cancer Immunotherapy: Lessons from Ultra-pH-Sensitive Nanoparticles.

Immunotherapy has transformed the field of oncology and patient care. By leveraging the immune system of the host, immunostimulatory compounds exert a durable, personalized response against the patient's own tumor. Despite the clinical success, the overall response rate from current therapies (e.g., immune checkpoint inhibitors) remains low (∼20%) because tumors develop multiple resistance pathways at molecular, cellular, and microenvironmental levels. Unlike other oncologic therapies, harnessing antitumor immunity requires precise activation of a complex immunological system with multiple levels of regulation over its function. This requires the ability to exert control over immune cells in both intracellular compartments and various extracellular sites, such as the tumor microenvironment, in a spatiotemporally coordinated fashion.The immune system has evolved to sense and respond to nano- and microparticulates (e.g., viruses, bacteria) as foreign pathogens. Through the versatile control of composition, size, shape, and surface properties of nanoparticles, nano-immune-engineering approaches are uniquely positioned to mount appropriate immune responses against cancer. This Account highlights the development and implementation of ultra-pH-sensitive (UPS) nanoparticles in cancer immunotherapy with an emphasis on nanoscale cooperativity. Nanocooperativity has been manifested in many biological systems and processes (e.g., protein allostery, biomolecular condensation), where the system can acquire emergent properties distinct from the sum of individual parts acting in isolation.Using UPS nanoparticles as an example, we illustrate how all-or-nothing protonation cooperativity during micelle assembly/disassembly can be leveraged to augment the cancer-immunity cycle toward antitumor immunity. The cooperativity behavior enables instant and pH-triggered payload release and dose accumulation in acidic sites (e.g., endocytic organelles of antigen presenting cells, tumor microenvironment), intercepting specific immunological and tumor pathophysiological processes for therapy. These efforts include T cell activation in lymph nodes by coordinating cytosolic delivery of tumor antigens to dendritic cells with simultaneous activation of stimulator of interferon genes (STING), or tumor-targeted delivery of acidotic inhibitors to reprogram the tumor microenvironment and overcome T cell retardation. Each treatment strategy represents a nodal intervention in the cancer-immunity cycle, featuring the versatility of UPS nanoparticles. Overall, this Account aims to highlight nanoimmunology, an emerging cross field that exploits nanotechnology's unique synergy with immunology through nano-immune-engineering, for advancing cancer immunotherapy.

Contrasting transcriptional responses of PYR1/PYL/RCAR ABA receptors to ABA or dehydration stress between maize seedling leaves and roots.

BACKGROUND: The different actions of abscisic acid (ABA) in the aboveground and belowground parts of plants suggest the existence of a distinct perception mechanism between these organs. Although characterization of the soluble ABA receptors PYR1/PYL/RCAR as well as core signaling components has greatly advanced our understanding of ABA perception, signal transduction, and responses, the environment-dependent organ-specific sensitivity of plants to ABA is less well understood. RESULTS: By performing real-time quantitative PCR assays, we comprehensively compared transcriptional differences of core ABA signaling components in response to ABA or osmotic/dehydration stress between maize (Zea mays L.) roots and leaves. Our results demonstrated up-regulation of the transcript levels of ZmPYLs homologous to dimeric-type Arabidopsis ABA receptors by ABA in maize primary roots, whereas those of ZmPYLs homologous to monomeric-type Arabidopsis ABA receptors were down-regulated. However, this trend was reversed in the leaves of plants treated with ABA via the root medium. Although the mRNA levels of ZmPYL1-3 increased significantly in roots subjected to polyethylene glycol (PEG)-induced osmotic stress, ZmPYL4-11 transcripts were either maintained at a stable level or increased only slightly. In detached leaves subjected to dehydration, the transcripts of ZmPYL1-3 together with ZmPYL5, ZmPYL6, ZmPYL10 and ZmPYL11 were decreased, whereas those of ZmPYL4, ZmPYL7 and ZmPYL8 were significantly increased. Our results also showed that all of the evaluated transcripts of PP2Cs and SnRK2 were quickly up-regulated in roots by ABA or osmotic stress; conversely they were either up-regulated or maintained at a constant level in leaves, depending on the isoforms within each family. CONCLUSIONS: There is a distinct profile of PYR/PYL/RCAR ABA receptor gene expression between maize roots and leaves, suggesting that monomeric-type ABA receptors are mainly involved in the transmission of ABA signals in roots but that dimeric-type ABA receptors primarily carry out this function in leaves. Given that ZmPYL1 and ZmPYL4 exhibit similar transcript abundance under normal conditions, our findings may represent a novel mechanism for species-specific regulation of PYR/PYL/RCAR ABA receptor gene expression. A difference in the preference for core signaling components in the presence of exogenous ABA versus stress-induced endogenous ABA was observed in both leaves and roots. It appears that core ABA signaling components perform their osmotic/dehydration stress response functions in a stress intensity-, duration-, species-, organ-, and isoform-specific manner, leading to plasticity in response to adverse conditions and, thus, acclimation to life on land. These results deepen our understanding of the diverse biological effects of ABA between plant leaves and roots in response to abiotic stress at the stimulus-perception level.

Elucidation of Spatial Cooperativity in Chemo-Immunotherapy by a Sequential Dual-pH-Responsive Drug Delivery System.

Combining immune checkpoint blockade with chemotherapy through nanotechnology is promising in terms of safety and efficacy. However, the distinct subcellular distribution of each ingredient's action site makes it challenging to acquire an optimal synergism. Herein, a dual-pH responsive hybrid polymeric micelle system, HNP(αPDL16.9, Dox5.3), is constructed as a proof-of-concept for the spatial cooperativity in chemo-immunotherapy. HNP retains the inherent pH-transition of each polymer, with stepwise disassembly under discrete pH thresholds. Within weakly acidic extracellular tumor environment, αPDL1 is first released to block the checkpoint on cell membranes. The remaining intact Doxorubicin-loaded micelle NP(Dox)5.3 displays significant tropism toward tumor cells and releases Dox upon lysosomal pH for efficient tumor immunogenic cell death without immune toxicity. This sequential-released pattern boosts DC activation and primes CD8+ T cells, leading to enhanced therapeutic performance than single agent or an inverse-ordered combination in multiple murine tumor models. Using HNP, the indispensable role of conventional type 1 DC (cDC1) is identified in chemo-immunotherapy. A co-signature of cDC1 and CD8 correlates with cancer patient survival after neoadjuvant Pembrolizumab plus chemotherapy in clinic. This study highlights spatial cooperativity of chemo- and immuno-agents in immunoregulation and provides insights into the rational design of drug combination for future nanotherapeutics development.

Prolonged activation of innate immune pathways by a polyvalent STING agonist.

The stimulator of interferon genes (STING) is an endoplasmic reticulum transmembrane protein that is a target of therapeutics for infectious diseases and cancer. However, early-phase clinical trials of small-molecule STING agonists have shown limited antitumour efficacy and dose-limiting toxicity. Here, we show that a polyvalent STING agonist-a pH-sensitive polymer bearing a seven-membered ring with a tertiary amine (PC7A)-activates innate-immunity pathways through the polymer-induced formation of STING-PC7A condensates. In contrast to the natural STING ligand 2',3'-cyclic-GMP-AMP (cGAMP), PC7A stimulates the prolonged production of pro-inflammatory cytokines by binding to a non-competitive STING surface site that is distinct from the cGAMP binding pocket. PC7A induces antitumour responses that are dependent on STING expression and CD8+ T-cell activity, and the combination of PC7A and cGAMP led to synergistic therapeutic outcomes (including the activation of cGAMP-resistant STING variants) in mice bearing subcutaneous tumours and in resected human tumours and lymph nodes. The activation of the STING pathway through polymer-induced STING condensation may offer new therapeutic opportunities.

Polycarbonate-based ultra-pH sensitive nanoparticles improve therapeutic window.

Stimuli-sensitive nanomaterials with cooperative response are capable of converting subtle and gradual biological variations into robust outputs to improve the precision of diagnostic or therapeutic outcomes. In this study, we report the design, synthesis and characterization of a series of degradable ultra-pH sensitive (dUPS) polymers that amplify small acidic pH changes to efficacious therapeutic outputs. A hydrolytically active polycarbonate backbone is used to construct the polymer with pH-dependent degradation kinetics. One dUPS polymer, PSC7A, can achieve activation of the stimulator of interferon genes and antigen delivery upon endosomal pH activation, leading to T cell-mediated antitumor immunity. While a non-degradable UPS polymer induces granulomatous inflammation that persists over months at the injection site, degradable PSC7A primes a transient acute inflammatory response followed by polymer degradation and complete tissue healing. The improved therapeutic window of the dUPS polymers opens up opportunities in pH-targeted drug and protein therapy.

cRGDfK-Grafted Small-Size Quercetin Micelles For Enhancing Therapy Efficacy Of Active Ingredient From The Chinese Medicinal Herb.

BACKGROUND: As an active ingredient of Chinese herbal medicine, quercetin (QU) can significantly induce apoptosis of tumor cells and give play to other effect such as decreasing both fibroblast population and collagen in cancer cell nest. However, the antitumor efficacy of quercetin was mostly evaluated at cellular level and rarely developed in vivo by intravenous injection, which may be ascribed to its inferior physicochemical properties including water insolubility, short plasma half-time, and insufficient enrichment in the tumor tissues. METHODS: The DSPE-PEG was used to construct quercetin-loaded micelles, and the integrin ligand cRGDfK was grafted to modify the nanocarrier for enhancing its cancer-specific homing. The MALDI-TOF-MS, DLS, TEM, and UV were orderly operated to characterize guidance molecules and micelles by morphology, size distribution, Zeta potential, and drug encapsulation efficiency. In addition, the surface plasmon resonance study and real-time confocal analysis were employed to demonstrate αvß3 integrin-overexpressing B16 cells-specific binding and uptake. After further pharmacodynamics studies in vitro and in vivo, we also evaluate systemic toxicity about cRGDfK-PM-QU. RESULTS: The cRGDfK was successfully stitched with DSPE-PEG and modified on the surface of micelles. The ligand modification enhanced the negative charges of the micelles, but it did not induce significant changes in particle size. The quercetin micelles were about 15 nm in size and negatively charged, and had spherical morphology and high drug encapsulation efficiency. In vitro, the cRGDfK-modified micelles (cRGDfK-PM) showed αvß3 integrin-overexpressing B16 cells-specific binding and uptake, and cRGDfK-PM-QU (QU loaded in cRGDfK-PM) induced more significant cell apoptosis and cytotoxic effects against B16 tumor cells than counterpart micelles (PM-QU). In vivo, the cRDGfK modification enhanced enrichment in B16 tumor tissue, improved the therapeutic efficacy of the quercetin-loaded micelles against B16 tumor, and exhibited lower systemic and pulmonary toxicity compared with counterpart micelles in the mouse mode. CONCLUSION: Quercetin as a natural product has triggered increasing interest in the antitumor field. In this study, cRGDfK-modified DSPE-PEG micelles significantly optimized quercetin therapeutic efficacy and pulmonary toxicity as well as lowered systemic toxicity.

Comprehensively priming the tumor microenvironment by cancer-associated fibroblast-targeted liposomes for combined therapy with cancer cell-targeted chemotherapeutic drug delivery system.

Cancer-associated fibroblasts (CAFs) not only support tumorigenesis and tumor metastasis by reciprocal cellular cross-talk with cancer cells, but also remodel the extracellular matrix (ECM) and architecture of tumor microenvironment. This leads to poor tumor penetration of traditional chemotherapeutic nanomedicines and resulting drug resistance. In this study, we use a novel tumor stroma-targeted nanovehicle (FH-SSL-Nav) to specifically eradicate CAFs, promote tumor penetration of nanomedicines and cut off the stroma's support to cancer cells. FH-SSL-Nav exhibited excellent and comprehensive tumor microenvironment modulation including downregulation ECM deposition, decreasing interstitial fluid pressure (IFP) and facilitating blood perfusion. As a result, more chemotherapeutic drug delivery systems penetrated deep into tumor spheroids in vitro and tumor tissues in vivo. Furthermore, chemotherapeutic drug resistance induced by microenvironment was partly reversed by FH-SSL-Nav. In a human Hep G2 xenograft nude mouse model, FH-SSL-Nav greatly improved the tumor suppression of cancer cell-targeted liposomal doxorubicin (7pep-SSL-DOX) with low dose and low toxicity. Since Nav and DOX exhibited no synergy against Hep G2 cells, it was clear that the improved antitumor efficacy was basically due to the comprehensive tumor microenvironment priming by FH-SSL-Nav.