Association between infants’ serum levels of 26 metals and gut microbiota: a hospital-based cross-sectional study in China Original paper
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Metals
Metals
Heavy metals influence microbial pathogenicity in two ways: they can be toxic to microbes by disrupting cellular functions and inducing oxidative stress, and they can be exploited by pathogens to enhance survival, resist treatment, and evade immunity. Understanding metal–microbe interactions supports better antimicrobial and public health strategies.
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What was studied?
This study investigated the impact of metal exposure on the gut microbiota of infants, focusing on 26 different metals and their interactions with microbial communities. The study assessed how metals like arsenic (As), copper (Cu), manganese (Mn), and others affect the diversity and composition of the infant gut microbiome, with a particular emphasis on how metal mixtures may influence microbial taxa and overall gut health.
Who was studied?
The study involved 342 infants who were recruited from a hospital in Hunan, China. These infants were assessed for their serum metal concentrations, and their gut microbiota was analyzed through fecal samples. The study population was stratified into full-term, preterm, and very preterm infants to explore potential differences in how metal exposure affects their microbiomes.
What were the most important findings?
The study revealed that certain metals, particularly arsenic, copper, and manganese, significantly influenced the diversity and composition of the infant gut microbiota. Metals such as barium (Ba) and arsenic (As) were positively associated with the Chao1 index, which reflects microbial richness, while metals like chromium (Cr), cobalt (Co), and copper (Cu) showed negative associations. Further analyses, such as Bayesian kernel machine regression (BKMR), identified manganese (Mn) as a key driver of the abundance of Burkholderia-Caballeronia-Paraburkholderia, a genus of concern for its pathogenic potential. The study also found that the exposure to metal mixtures had a significant impact on specific microbial taxa, such as Clostridium_sensu_stricto_1, which was notably influenced by synergistic interactions between metals like Mn and Cu. Interestingly, some metals showed antagonistic interactions, with chromium and tungsten (Cr-W) or arsenic and praseodymium (As-Pr) combinations negatively affecting microbial diversity. This highlights the complex interactions between metals and gut microbiota and suggests that combined exposures may lead to significant shifts in microbial communities.
What are the greatest implications of this study?
The findings of this study underscore the critical role of environmental metal exposure in shaping the infant gut microbiome, particularly in vulnerable populations like preterm infants. The identification of key metals that influence microbial diversity and specific taxa opens the door for future research into how these changes might affect long-term health outcomes, including the development of autoimmune diseases, allergies, and other gut-related disorders. The study highlights the need for further investigation into the synergistic and antagonistic effects of metal mixtures and how they could potentially be mitigated through dietary interventions or probiotic treatments. Given the importance of microbial health in early life development, these insights could guide public health strategies aimed at reducing exposure to harmful metals in environments where infants are particularly susceptible.
Arsenic (As)
Arsenic can disrupt both human health and microbial ecosystems. Its impact on the gut microbiome can lead to dysbiosis, which has been linked to increased disease susceptibility and antimicrobial resistance. Arsenic's ability to interfere with cellular processes, especially through its interaction with essential metals like phosphate and zinc, exacerbates these effects.
Copper (Cu)
Copper serves as both a vital nutrient and a potential toxin, with its regulation having profound effects on microbial pathogenesis and immune responses. In the body, copper interacts with pathogens, either supporting essential enzyme functions or hindering microbial growth through its toxicity. The gastrointestinal tract, immune cells, and bloodstream are key sites where copper plays a crucial role in controlling infection and maintaining microbial balance. Understanding copper’s interactions with the microbiome and host defenses allows for targeted clinical strategies.
Manganese (Mn)
Manganese plays a pivotal role in microbial pathogenesis. As a vital cofactor for enzymes involved in antioxidant defense and metabolism, manganese is essential for pathogens, enabling them to survive within the host. However, when not properly managed, manganese can become toxic to both the host and the pathogen. The host’s immune system, through mechanisms like the secretion of calprotectin, tries to limit microbial access to manganese, creating an ongoing battle between host defenses and microbial survival .