Fluorescence imaging sheds light on the immune evasion mechanisms of hepatic stellate cells mediated by superoxide anion.

Whether and how the reactive oxygen species generated by hepatic stellate cells (HSCs) promote immune evasion of hepatocellular carcinoma (HCC) remains mysterious. Therefore, investigating the function of superoxide anion (O2•-), the firstly generated reactive oxygen species, during the immune evasion become necessary. In this work, we establish a novel in situ imaging method for visualization of O2•- changes in HSCs based on a new two-photon fluorescence probe TPH. TPH comprises recognition group for O2•- and HSCs targeting peptides. We observe that O2•- in HSCs gradually rose, impairing the infiltration of CD8+ T cells in HCC mice. Further studies reveal that the cyclin-dependent kinase 4 is deactivated by O2•-, and then cause the up-regulation of PD-L1. Our work provides molecular insights into HSC-mediated immune evasion of HCC, which may represent potential targets for HCC immunotherapy.

Fluorescent Probes for Disease Diagnosis.

The identification and detection of disease-related biomarkers is essential for early clinical diagnosis, evaluating disease progression, and for the development of therapeutics. Possessing the advantages of high sensitivity and selectivity, fluorescent probes have become effective tools for monitoring disease-related active molecules at the cellular level and in vivo. In this review, we describe current fluorescent probes designed for the detection and quantification of key bioactive molecules associated with common diseases, such as organ damage, inflammation, cancers, cardiovascular diseases, and brain disorders. We emphasize the strategies behind the design of fluorescent probes capable of disease biomarker detection and diagnosis and cover some aspects of combined diagnostic/therapeutic strategies based on regulating disease-related molecules. This review concludes with a discussion of the challenges and outlook for fluorescent probes, highlighting future avenues of research that should enable these probes to achieve accurate detection and identification of disease-related biomarkers for biomedical research and clinical applications.

Visualizing Efficacy of Antineoplastic Drug via Ratiometric Near-Infrared Fluorescence Imaging of Tumor-Associated Macrophage-Specific Nitric Oxide.

Elevated nitric oxide (NO) within tumor-associated macrophages (TAMs) suggests a reduction of TAM-mediated tumoral immune tolerance. This cellular event could be a reliable indicator for efficacy evaluation of antineoplastic drugs. However, a suitable method for TAM-specific NO measurement is still lacking. In this work, a simple and fast efficacy evaluation method for antineoplastic drugs is established based on a ratiometric TAM-specific NO near-infrared (NIR) fluorescence probe TAM-Cy-NO. Molecular fluorescence probe Cy-NO for NO response was encapsulated in the TAM-targeting peptide (M2pep)-functionalized liposome to construct TAM-Cy-NO. After TAM enters through M2pep, Cy-NO reacts with NO specifically, resulting in a dose-dependent ratiometric fluorescence signal (I 610/I 815) change manner. Utilizing this strategy, we observed that PLX-3397, metformin, and ibrutinib triggered NO generation within TAM greater than that with sorafenib. Notably, metformin and ibrutinib promoted TNF-α and reduced PD-L1 expressions, which suggest reductions of TAM-mediated immunosuppression. As expected, these drugs delayed tumor progression in mice. This method provides a promising efficacy evaluation strategy for rapid screening of antineoplastic drugs.

Deep-Tissue Fluorescence Imaging Study of Reactive Oxygen Species in a Tumor Microenvironment.

Tumor microenvironment (TME) is the survival environment for tumor cells to proliferate and metastasize in deep tissue. TME contains tumor cells, immune cells, stromal cells and a variety of active molecules including reactive oxygen species (ROS). Inside the TME, ROS regulate the oxidation-reduction (redox) homeostasis and promote oxidative stress. Due to the rapid proliferation ability and specific metabolic patterns of the TME, ROS pervade virtually all complex physiological processes and play irreplaceable roles in protein modification, signal transduction, metabolism, and energy production in various tumors. Therefore, measurements of the dynamically, multicomponent simultaneous changes of ROS in the TME are of great significance to reveal the detailed proliferation and metastasis mechanisms of the tumor. Near-infrared (NIR) and two-photon (TP) fluorescence imaging techniques possess real-time, dynamic, highly sensitive, and highly signal-to-noise ratios with deep tissue penetration abilities. With the rationally designed probes, the NIR and TP fluorescence imaging techniques have been widely used to reveal the mechanisms of how ROS regulates and constructs complex signals and metabolic networks in TME. Therefore, we summarize the design principles and performances of NIR and TP fluorescence imaging of ROS in the TME in the last four years, as well as discuss the advantages and potentials of these works. This Review can provide guidance and prospects for future research work on TME and facilitate the development of antitumor drugs.