Smectite promotes probiotic biofilm formation in the gut for cancer immunotherapy

• Published in: Cell reports (Cambridge) 2021-02, Vol.34 (6), p.108706-108706, Article 108706
• Main Authors: Han, Congwei, Song, Jinji, Hu, Junqing, Fu, Huijie, Feng, Yanxian, Mu, Ruoyu, Xing, Zhen, Wang, Zhenzhen, Wang, Lintao, Zhang, Junfeng, Wang, Chunming, Dong, Lei
• Format: Article
• Language: English
• Subjects: Animals; Bifidobacterium - physiology; biofilm; Biofilms - drug effects; Biofilms - growth & development; cancer therapy; Cell Line, Tumor; Female; Gastrointestinal Microbiome - drug effects; gut microbiome; Immunotherapy; Lactobacillus - physiology; Mice; Mice, Inbred BALB C; Mice, Knockout; Neoplasms, Experimental - microbiology; Neoplasms, Experimental - therapy; probiotics; Probiotics - pharmacology; Silicates - pharmacology; smectite
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2021.108706

Administration of probiotics to regulate the immune system is a potential anti-tumor strategy. However, oral administration of probiotics is ineffective because of the poor inhabitation of exogenous bacteria in host intestines. Here we report that smectite, a type of mineral clay and established anti-diarrhea drug, promotes expansion of probiotics (especially Lactobacillus) in the murine gut and subsequently elicits anti-tumor immune responses. The ion-exchangeable microstructure of smectite preferentially promotes lactic acid bacteria (LABs) to form biofilms on smectite in vitro and in vivo. In mouse models, smectite laden with LAB biofilms (Lactobacillus and Bifidobacterium) inhibits tumor growth (when used alone) and enhances the efficacy of chemotherapy or immunotherapy (when used in combination with either of them) by activating dendritic cells (DCs) via Toll-like receptor 2 (TLR2) signaling. Our findings suggest oral administration of smectite as a promising strategy to enrich probiotics in vivo for cancer immunotherapy. [Display omitted] •Smectite clay promotes lactic acid bacteria (LABs) to form biofilms on its surface•Smectite with LABs inhibits tumor growth in mice•Smectite with LABs enhances anti-cancer chemo/immunotherapy in mice•Smectite with LABs activates dendritic cells via TLR2 signaling Han et al. reveal that smectite, a mineral clay and established anti-diarrhea drug, has anti-cancer efficacy in mice by promoting expansion of probiotics in the gut that, in turn, activate dendritic cells via Toll-like receptor 2 signaling.