Infection-induced innate antimicrobial response disorders: from signaling pathways and their modulation to selected biomarkers

Ultrasound improved immune adjuvant delivery to induce DC maturation and T cell activation

Tumor immunotherapy has emerged as a promising approach to tumor treatment. Currently, immune adjuvant-based therapeutic modalities are rarely curative in solid tumors owing to challenges including the low permeability and extremely poor water solubility of these adjuvants, limiting their ability to effectively promote dendritic cell (DC) maturation. Herein, we employed ultrasound-mediated cavitation (UMC) to promote the delivery of Toll-like receptor agonist (R837)-loaded pH-responsive liposomes (PEOz-Lip@R837) to tumors. The tumor-associated antigens (TAAs) produced by UMC treatment exhibited vaccinal activity, particularly in the presence of immune adjuvants, together promoting the maturation of DC and inducing cytokine production. Importantly, UMC can down-regulate immune checkpoint molecules, like Cd274, Foxp3 and Ctla4, synergistically stimulating the activation and proliferation of T cells in the body to facilitate tumor treatment. This UMC-enhanced PEOz-Lip@R837 approach was able to induce a robust antitumor immune response capable of arresting primary and distant tumor growth, while also developing immunological memory, protecting against tumor rechallenge following initial tumor clearance. Overall, these results highlight a promising UMC- and pH-sensitive immune adjuvant delivery-based treatment for tumors with the potential for clinical application.

CASP-Model Sepsis Triggers Systemic Innate Immune Responses Revealed by the Systems-Level Signaling Pathways

Colon ascendens stent peritonitis (CASP) surgery induces a leakage of intestinal contents which may cause polymicrobial sepsis related to post-operative failure of remote multi-organs (including kidney, liver, lung and heart) and possible death from systemic syndromes. Mechanisms underlying such phenomena remain unclear. This article aims to elucidate the mechanisms underlying the CASP-model sepsis by analyzing real-world GEO data (GSE24327_A, B and C) generated from mice spleen 12 hours after a CASP-surgery in septic MyD88-deficient and wildtype mice, compared with untreated wildtype mice. Firstly, we identify and characterize 21 KO MyD88-associated signaling pathways, on which true key regulators (including ligands, receptors, adaptors, transducers, transcriptional factors and cytokines) are marked, which were coordinately, significantly, and differentially expressed at the systems-level, thus providing massive potential biomarkers that warrant experimental validations in the future. Secondly, we observe the full range of polymicrobial (viral, bacterial, and parasitic) sepsis triggered by the CASP-surgery by comparing the coordinated up- or down-regulations of true regulators among the experimental treatments born by the three data under study. Finally, we discuss the observed phenomena of “systemic syndrome”, “cytokine storm” and “KO MyD88 attenuation”, as well as the proposed hypothesis of “spleen-mediated immune-cell infiltration”. Together, our results provide novel insights into a better understanding of innate immune responses triggered by the CASP-model sepsis in both wildtype and MyD88-deficient mice at the systems-level in a broader vision. This may serve as a model for humans and ultimately guide formulating the research paradigms and composite strategies for the early diagnosis and prevention of sepsis.

A pH-responsive polymer linked with immunomodulatory drugs: synthesis, characteristics and in vitro biocompatibility

Cancer immunotherapy is a promising method for cancer therapy. Imiquimod (R837) is a molecule that could activate immune systems for cancer immunotherapy, but an easily manufactured biocompatible carrier to deliver R837 may be needed to overcome the disadvantages of R837. Micelles formed by biocompatible copolymers have been widely used to deliver chemotherapeutic drugs but not immunotherapeutic drugs. In this study, R837 was linked to an amphiphilic biodegradable copolymer mPEG-b-PLA via acid-sensitive Schiff bases. The molecular structures were investigated by ¹ H nuclear magnetic resonance, gel permeation chromatography and Fourier transform infrared spectroscopy. The product could be self-assembled into micelles with R837 content as high as 22.4%. Owing to acid-cleavable Schiff bases, the release of R837 from micelles was markedly accelerated under acidic media. Consequently, the micelles linked with R837 stimulated the expression of major histocompatibility complex II-stimulating molecules on the surface of RAW 264.7 macrophages at pH 6.5 but not pH 7.4. By using human umbilical vein endothelial cells as the in vitro model, it was shown that the polymer carriers and R837-linked micelles were minimally cytotoxic and did not induce the activation of endothelial cells under physiological pH, which suggested the relatively high biocompatibility. In conclusion, this study successfully developed pH-responsive immunotherapeutic drug-loaded micelles that could activate macrophages at acidic pH in vitro. The high biocompatibility of the micelles to endothelial cells also indicated the potential uses under in vivo conditions.