Immunoadjuvant-Modified Rhodobacter sphaeroides Potentiate Cancer Photothermal Immunotherapy.

Photothermal immunotherapy has become a promising strategy for tumor treatment. However, the intrinsic drawbacks like light instability, poor immunoadjuvant effect, and poor accumulation of conventional inorganic or organic photothermal agents limit their further applications. Based on the superior carrying capacity and active tumor targeting property of living bacteria, an immunoadjuvant-intensified and engineered tumor-targeting bacterium was constructed to achieve effective photothermal immunotherapy. Specifically, immunoadjuvant imiquimod (R837)-loaded thermosensitive liposomes (R837@TSL) were covalently decorated onto Rhodobacter sphaeroides (R.S) to obtain nanoimmunoadjuvant-armed bacteria (R.S-R837@TSL). The intrinsic photothermal property of R.S combined R837@TSL to achieve in situ near-infrared (NIR) laser-controlled release of R837. Meanwhile, tumor immunogenic cell death (ICD) caused by photothermal effect of R.S-R837@TSL, synergizes with released immunoadjuvants to promote maturation of dendritic cells (DCs), which enhance cytotoxic T lymphocytes (CTLs) infiltration for further tumor eradication. The photosynthetic bacteria armed with immunoadjuvant-loaded liposomes provide a strategy for immunoadjuvant-enhanced cancer photothermal immunotherapy.

Stimulation-responsive mucoadhesive probiotics for inflammatory bowel disease treatment by scavenging reactive oxygen species and regulating gut microbiota.

Inflammatory bowel disease (IBD) is characterized by the high level of reactive oxygen species (ROS) and highly dysfunctional intestinal flora. Here, a stimulation-responsive mucoadhesive probiotic Lac@HDP was rationally constructed for achieving specific adhesion of colitis site and depleting high level of ROS in inflammatory site. Briefly, Lac is Lactobacillus acidophilus, HDP is obtained by hyaluronic acid grafted with dopamine protected by phenylboric acid. Specifically, by consuming a large amount of ROS, phenyl borate group of Lac@HDP is oxidized and fractured, thus exposing the catechol hydroxyl group and obtaining strong mucosal adhesion ability, thereby significantly prolong the retention time of Lac in the inflammatory site. In the murine model of acute and chronic colitis, the stimulation-responsive mucoadhesive probiotics were significantly more effective in alleviating colitis symptoms than antioxidants and probiotics alone. In addition, the abundance and diversity of intestinal flora were increased after treatment with Lac@HDP, which was helpful to alleviate IBD. Importantly, the stimulation-responsive mucoadhesive probiotics have good biological safety in vivo, which provides the prospect of clinical application in the future.

Progress of engineered bacteria for tumor therapy.

Recently, with the rapid development of bioengineering technology and nanotechnology, natural bacteria were modified to change their physiological activities and therapeutic functions for improved therapeutic efficiency of diseases. These engineered bacteria were equipped to achieve directed genetic reprogramming, selective functional reorganization and precise spatio-temporal control. In this review, research progress in the basic modification methodologies of engineered bacteria were summarized, and representative researches about their therapeutic performances for tumor treatment were illustrated. Moreover, the strategies for the construction of engineered colonies based on engineering of individual bacteria were summarized, providing innovative ideas for complex functions and efficient anti-tumor treatment. Finally, current limitation and challenges of tumor therapy utilizing engineered bacteria were discussed.

Multifunctional liquid metal-based nanoparticles with glycolysis and mitochondrial metabolism inhibition for tumor photothermal therapy.

Tumor cells obtain energy supply from different metabolic pathways to maintain survival. In this study, a tumor acidity-responsive spherical nanoparticle (called as LMGC) was designed by attaching glucose oxidase (GOx) and mineralizing calcium carbonate on the surface of liquid metal nanoparticles to integrate the synergistic effect of adenosine triphosphate (ATP) generation inhibition and photothermal therapy (PTT) for enhanced tumor therapy. After GOx catalysis, the process of glycolysis was inhibited, and the increased H2O2 level enhanced the intratumoral oxidative stress. Besides, the gluconic acid production accelerated the degradation of LMGC and promoted Ca2+-mediated mitochondrial dysfunction. The inhibition of glycolysis and mitochondrial metabolism could significantly reduce ATP production and down-regulate heat shock protein (HSP) expression, which would reduce tumor cells heat resistance and improve PTT therapeutic effect. This liquid metal-based ATP inhibition system with enhanced therapeutic effect will find great potential for tumor treatment.

Neisseria meningitidis Opca Protein/MnO2 Hybrid Nanoparticles for Overcoming the Blood-Brain Barrier to Treat Glioblastoma.

The major hurdle in glioblastoma therapy is the low efficacy of drugs crossing the blood-brain barrier (BBB). Neisseria meningitidis is known to specifically enrich in the central nervous system through the guidance of an outer membrane invasion protein named Opca. Here, by loading a chemotherapeutic drug methotrexate (MTX) in hollow manganese dioxide (MnO2 ) nanoparticles with surface modification of the Opca protein of Neisseria meningitidis, a bionic nanotherapeutic system (MTX@MnO2 -Opca) is demonstrated to effectively overcome the BBB. The presence of the Opca protein enables the drug to cross the BBB and penetrate into tumor tissues. After accumulating in glioblastoma, the nanotherapeutic system catalyzes the decomposition of excess H2 O2 in the tumor tissue and thereby generates O2 , which alleviates tumor hypoxia and enhances the effect of chemotherapy in the treatment of glioblastoma. This bionic nanotherapeutic system may exhibit great potential in the treatment of glioblastoma.

Photoelectric Bacteria Enhance the In Situ Production of Tetrodotoxin for Antitumor Therapy.

Engineered bacteria are promising bioagents to synthesize antitumor drugs at tumor sites with the advantages of avoiding drug leakage and degradation during delivery. Here, we report an optically controlled material-assisted microbial system by biosynthesizing gold nanoparticles (AuNPs) on the surface of Shewanella algae K3259 (S. algae) to obtain Bac@Au. Leveraging the dual directional electron transport mechanism of S. algae, the hybrid biosystem enhances in situ synthesis of antineoplastic tetrodotoxin (TTX) for a promising antitumor effect. Because of tumor hypoxia-targeting feature of facultative anaerobic S. algae, Bac@Au selectively target and colonize at tumor. Upon light irradiation, photoelectrons produced by AuNPs deposited on bacterial surface are transferred into bacterial cytoplasm and participate in accelerated cell metabolism to increase the production of TTX for antitumor therapy. The optically controlled material-assisted microbial system enhances the efficiency of bacterial drug synthesis in situ and provides an antitumor strategy that could broaden conventional therapy boundaries.