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Systematic profiling of human gut bacteria with cyclic di-AMP secretion to enhance anti-tumor immunity
Linggang Zheng1, Jumin Huang2, Haoran Ni3
1Faculty of Chinese Medicine, Macau University of Science and Technology, Taipa 999078, Macao Special Administrative Region of China; Dr Neher's Biophysics Laboratory for Innovative Drug Discovery/ State Key Laboratory of Mechanism and Quality of Chinese Medicine, Macau University of Science and Technology, Taipa 999078, Macao Special Administrative Region of China; CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
Introduction:
Gut microbiota-derived metabolites play pivotal roles in clinical tumor treatment and progression. Cyclic di-AMP serves as both a bacterial signaling molecule and an immune activator of the STING pathway. However, knowledge on cyclic di-AMP production by gut commensals remains limited, hindering the rational application of gut bacteria in cancer therapy.
Objectives:
This study systematically characterizes the metabolic profiles and genotypes associated with cyclic di-AMP synthesis in human gut commensals. We further validate the immune-activating and anti-tumor effects of high cyclic di-AMP-producing probiotics in both in vitro and in vivo non-small cell lung cancer models.
Methods:
Cyclic di-AMP levels (intracellular and extracellular) were quantified via LC-MS in 51 representative gut bacterial species derived from 442 strains isolated from 119 human fecal samples. STING pathway activation was assessed by co-culturing THP-1 cells with supernatants from high cyclic di-AMP-producing gut probiotics. Anti-tumor efficacy was evaluated in a non-small cell lung cancer mouse model.
Results:
Screening of 51 gut bacterial species identified 24 high cyclic di-AMP producers, with 18 exhibiting robust secretion capacity. Bioinformatic annotation revealed genes governing cyclic di-AMP synthesis, degradation, and secretion. Two food-grade probiotics, Limosilactobacillus fermentum DA785 and Lacticaseibacillus rhamnosus R7970, demonstrated efficient cyclic di-AMP secretion. Their supernatants significantly upregulated STING pathway-related gene expression and IFN-β secretion in THP-1 cells. Oral administration of these strains suppressed tumor growth in mice by activating immune responses within the tumor microenvironment. And Limosilactobacillus fermentum DA785 suppresses tumor growth via the STING pathway.
Conclusion:
This study highlights the therapeutic potential of food-grade probiotics with high cyclic di-AMP production to augment anti-tumor immunity, offering a novel microbiome-based strategy for cancer treatment.
Insights
Certain gut bacteria produce cyclic di-AMP, a molecule that activates the STING pathway. High cyclic di-AMP producing probiotics show potential for cancer therapy by boosting anti-tumor immunity.
Area of Science:
- Microbiology
- Immunology
- Cancer Research
Background:
- Gut microbiota metabolites influence cancer treatment and progression.
- Cyclic di-AMP (c-di-AMP) is a bacterial signaling molecule and STING pathway activator.
- Limited knowledge exists on c-di-AMP production by gut commensals for cancer therapy.
Purpose of the Study:
- Characterize metabolic profiles and genotypes for c-di-AMP synthesis in human gut commensals.
- Validate immune-activating and anti-tumor effects of high c-di-AMP producing probiotics.
- Assess effects in vitro and in vivo non-small cell lung cancer (NSCLC) models.
Main Methods:
- Quantified c-di-AMP levels in 51 gut bacterial species using LC-MS.
- Assessed STING pathway activation via THP-1 cell co-culture with probiotic supernatants.
- Evaluated anti-tumor efficacy in a NSCLC mouse model.
Main Results:
- Identified 24 high c-di-AMP producers among 51 species; 18 showed robust secretion.
- Bioinformatic analysis revealed genes for c-di-AMP synthesis, degradation, and secretion.
- Two probiotics (L. fermentum DA785, L. rhamnosus R7970) efficiently secreted c-di-AMP, activating the STING pathway and suppressing tumor growth in mice.
Conclusions:
- Food-grade probiotics with high c-di-AMP production can augment anti-tumor immunity.
- Offers a novel microbiome-based strategy for cancer treatment.
- L. fermentum DA785 suppresses tumor growth via the STING pathway.
