Liver sinusoidal endothelial cells (LSECs) are responsible for the immunologic tolerance of liver which is a common site for visceral metastases, suggesting its potential role as an target for cancer immunotherapy. However, targeted modulation of LSECs is still not achieved thus far. Here, we report LSECs are specifically targeted and modulated by melittin nanoparticles (α-melittin-NPs). Intravital imaging shows that LSECs fluoresce within 20 s after intravenous injection of α-melittin-NPs. α-melittin-NPs trigger the activation of LSECs and lead to dramatic changes of cytokine/chemokine milieu in the liver, which switches the hepatic immunologic environment to the activated state. As a result, α-melittin-NPs resist the formation of metastatic lesions with high efficiency. More strikingly, the survival rate reaches 80% in the spontaneous liver metastatic tumor model. Our research provides support for the use of α-melittin-NPs to break LSEC-mediated immunologic tolerance, which opens an avenue to control liver metastasis through the immunomodulation of LSECs.

Acquiring information on the precise distribution of a tumor is essential to evaluate intratumoral heterogeneity. Conventional hematoxylin and eosin staining, which has been used by pathologists for more than 100 years, is the gold standard of tumor diagnosis. However, it is difficult to stain entire tumor tissues with hematoxylin and eosin and then acquire the three-dimensional distribution of cells in solid tumors due to difficulties in the staining and rinsing. In this paper, we propose a modified hematoxylin and eosin staining method, in which delipidation and ultrasound waves were applied to enhance tissue permeability and accelerate dye diffusion. This improved hematoxylin and eosin staining method is termed iHE (intact tissue hematoxylin and eosin staining). We applied the iHE method to stain intact organs of mice, which were then sectioned and imaged sequentially. The results showed that the whole tissue was stained homogeneously. Combined with micro-optical sectioning tomography (MOST), the iHE method can be used for 3D volume imaging and to evaluate the intratumoral heterogeneity of the entire tumor tissue spatially. Therefore, this method may help to accurately diagnose the invasion stage of tumors and guide clinical treatments.

As a naturally occurring cytolytic peptide, melittin (MLT) not only exhibits a potent direct tumor cell-killing effect but also possesses various immunomodulatory functions. MLT shows minimal chances for developing resistance and has been recognized as a promising broad-spectrum antitumor drug because of this unique dual mechanism of action. However, MLT still displays obvious toxic side effects during treatment, such as nonspecific cytolytic activity, hemolytic toxicity, coagulation disorders, and allergic reactions, seriously hampering its broad clinical applications. With thorough research on antitumor mechanisms and the rapid development of nanotechnology, significant effort has been devoted to shielding against toxicity and achieving tumor-directed drug delivery to improve the therapeutic efficacy of MLT. Herein, we mainly summarize the potential antitumor mechanisms of MLT and recent progress in the targeted delivery strategies for tumor therapy, such as passive targeting, active targeting and stimulus-responsive targeting. Additionally, we also highlight the prospects and challenges of realizing the full potential of MLT in the field of tumor therapy. By exploring the antitumor molecular mechanisms and delivery strategies of MLT, this comprehensive review may inspire new ideas for tumor multimechanism synergistic therapy.

Macrophage polarization determines the production of cytokines that fuel the initiation and evolution of rheumatoid arthritis (RA). Thus, modulation of macrophage polarization might represent a potential therapeutic strategy for RA. However, coordinated modulation of macrophages in the synovium and synovial fluid has not been achieved thus far. Herein, we develop a biomimetic ApoA-I mimetic peptide-modified neutrophil membrane-wrapped F127 polymer (R4F-NM@F127) for targeted drug delivery during RA treatment. Due to the high expression of adhesion molecules and chemokine receptors on neutrophils, the neutrophil membrane coating can endow the nanocarrier with synovitis-targeting ability, with subsequent recruitment to the synovial fluid under the chemotactic effects of IL-8. Moreover, R4F peptide modification further endows the nanocarrier with the ability to target the SR-B1 receptor, which is highly expressed on macrophages in the synovium and synovial fluid. Long-term in vivo imaging shows that R4F-NM@F127 preferentially accumulates in inflamed joints and is engulfed by macrophages. After loading of the anti-inflammatory drug celastrol (Cel), R4F-NM@F127-Cel shows a significant reduction in hepatotoxicity, and effectively inhibits synovial inflammation and alleviates joint damage by reprogramming macrophage polarization. Thus, our results highlight the potential of the coordinated targeted modulation of macrophages as a promising therapeutic option for the treatment of RA.