Ginseng polysaccharides alter the gut microbiota and kynurenine/tryptophan ratio, potentiating the antitumour effect of antiprogrammed cell death 1/programmed cell death ligand 1 (anti-PD-1/PD-L1) immunotherapy.

OBJECTIVE: Programmed death 1 and its ligand 1 (PD-1/PD-L1) immunotherapy is promising for late-stage lung cancer treatment, however, the response rate needs to be improved. Gut microbiota plays a crucial role in immunotherapy sensitisation and Panax ginseng has been shown to possess immunomodulatory potential. In this study, we aimed to investigate whether the combination treatment of ginseng polysaccharides (GPs) and αPD-1 monoclonal antibody (mAb) could sensitise the response by modulating gut microbiota. DESIGN: Syngeneic mouse models were administered GPs and αPD-1 mAb, the sensitising antitumour effects of the combination therapy on gut microbiota were assessed by faecal microbiota transplantation (FMT) and 16S PacBio single-molecule real-time (SMRT) sequencing. To assess the immune-related metabolites, metabolomics analysis of the plasma samples was performed. RESULTS: We found GPs increased the antitumour response to αPD-1 mAb by increasing the microbial metabolites valeric acid and decreasing L-kynurenine, as well as the ratio of Kyn/Trp, which contributed to the suppression of regulatory T cells and induction of Teff cells after combination treatment. Besides, the microbial analysis indicated that the abundance of Parabacteroides distasonis and Bacteroides vulgatus was higher in responders to anti-PD-1 blockade than non-responders in the clinic. Furthermore, the combination therapy sensitised the response to PD-1 inhibitor in the mice receiving microbes by FMT from six non-responders by reshaping the gut microbiota from non-responders towards that of responders. CONCLUSION: Our results demonstrate that GPs combined with αPD-1 mAb may be a new strategy to sensitise non-small cell lung cancer patients to anti-PD-1 immunotherapy. The gut microbiota can be used as a novel biomarker to predict the response to anti-PD-1 immunotherapy.

Correlation of gut microbial compositions to the development of Kawasaki disease vasculitis in children.

Aim: Here, we hypothesize that dysbiotic gut microbiota might contribute to the development of Kawasaki disease (KD), a pediatric disease with unknown etiology. This is the second report on gut microbiota composition in KD patients. Materials & results: 16S amplicon sequencing was performed on fecal DNA samples and revealed predominance of bacterial pathogens, such as Fusobacterium, Neisseria, Shigella and Streptococcus, in the gut of KD patients, but absent or suppressed after immunoglobulin/antibiotics therapy. In addition, beneficial bacteria propagated after the therapy. Conclusion: We conclude that prevalence of Fusobacteria, Shigella and Streptococcus might contribute to KD pathogenesis.