Cadmium toxicity to the human gut microbiome varies depending on composition

Area of Science:

• Microbiology
• Environmental Health
• Toxicology

Background:

• Cadmium (Cd) is a toxic heavy metal.
• Cd exposure negatively affects the gut microbiota.
• Understanding individual microbial responses to Cd is crucial.

Purpose of the Study:

• To investigate the compositional and functional effects of acute Cd exposure on human fecal microbiotas.
• To categorize microbial responses to Cd as sensitive, intermediate, or resilient.
• To identify microbial genera and interactions associated with Cd sensitivity or resilience.

Main Methods:

• In vitro incubation of human fecal microbiota from 21 healthy adults.
• Exposure to Cadmium (Cd) and control conditions.
• Analysis of short-chain fatty acid production (butyrate, acetate, lactate), microbial composition (weighted UniFrac), and microbial interaction networks.

Main Results:

• Three distinct microbial response categories (sensitive, intermediate, resilient) to Cd were identified based on butyrate production.
• Sensitive microbiomes showed decreased butyrate and increased acetate/lactate production under Cd stress.
• Resilient microbiomes maintained butyrate levels and had attenuated lactate increases, with less compositional shift and disrupted interactions compared to sensitive microbiomes. *Anaerostipes* abundance was significantly higher in sensitive microbiomes post-Cd exposure.
• In resilient communities, butyrate production was linked to *Faecalibacterium* (Cd-absent) and *Anaerostipes* (Cd-present).

Conclusions:

• Gut microbial responses to acute cadmium exposure vary significantly among individuals.
• Distinct functional and compositional shifts characterize sensitive versus resilient microbiomes.
• Microbiota features underlying cadmium sensitivity or resilience warrant further investigation.