Microbiome and spatially resolved metabolomics analysis reveal the anticancer role of gut Akkermansia muciniphila by crosstalk with intratumoral microbiota and reprogramming tumoral metabolism in mice.

Although gut microbiota has been linked to cancer, little is known about the crosstalk between gut- and intratumoral-microbiomes. The goal of this study was to determine whether gut Akkermansia muciniphila (Akk) is involved in the regulation of intratumoral microbiome and metabolic contexture, leading to an anticancer effect on lung cancer. We evaluated the effects of gut endogenous or gavaged exogenous Akk on the tumorigenesis using the Lewis lung cancer mouse model. Feces, blood, and tumor tissue samples were collected for 16S rDNA sequencing. We then conducted spatially resolved metabolomics profiling to discover cancer metabolites in situ directly and to characterize the overall Akk-regulated metabolic features, followed by the correlation analysis of intratumoral bacteria with metabolic network. Our results showed that both endogenous and exogenous gavaged Akk significantly inhibited tumorigenesis. Moreover, we detected increased Akk abundance in blood circulation or tumor tissue by 16S rDNA sequencing in the Akk gavaged mice, compared with the control mice. Of great interest, gavaged Akk may migrate into tumor tissue and influence the composition of intratumoral microbiome. Spatially resolved metabolomics analysis revealed that the gut-derived Akk was able to regulate tumor metabolic pathways, from metabolites to enzymes. Finally, our study identified a significant correlation between the gut Akk-regulated intratumoral bacteria and metabolic network. Together, gut-derived Akk may migrate into blood circulation, and subsequently colonize into lung cancer tissue, which contributes to the suppression of tumorigenesis by influencing tumoral symbiotic microbiome and reprogramming tumoral metabolism, although more studies are needed.

A study of various factors affecting satellitism tests of Haemophilus influenzae and Haemophilus parainfluenzae using Staphylococcus aureus as the source of NAD.

Many factors affecting satellitism tests are unclear, and it is difficult to avoid misidentification, even if the medium is properly selected. We investigated the factors causing false-positive results for Haemophilus influenzae and false-negative results for Haemophilus parainfluenzae in the satellitism tests using Staphylococcus aureus as the source of nicotinamide adenine dinucleotide (NAD). H. influenzae (four reference strains and 47 clinical isolates), H. parainfluenzae (two reference strains and 67 clinical isolates), four different media, and two strains of S. aureus revived on two different media were used in this study. The type of medium used to revive S. aureus was the most common factor causing false-positive results for H. influenzae, followed by different strains of S. aureus and the type of medium used for the experiment. The production of false-negative results for H. parainfluenzae was only related to the medium used in the experiment. To improve the accuracy of the tests in routine laboratories, using S. aureus as the source of NAD, tryptic soy agar, and S. aureus (ATCC 25923) revived on nutrient agar should be adopted.