Ghosh, Nukavarapu, Jala 2024 — Effects of heavy metals on gut barrier integrity and gut microbiota
This Microbiota and Host review by Ghosh, Nukavarapu, and Jala (University of Louisville Brown Cancer Center, Center for Microbiomics, Inflammation and Pathogenicity, with University of Connecticut collaboration) covers the mechanistic literature on how environmental heavy-metal exposure damages the intestinal epithelial barrier and disrupts gut microbiota homeostasis. The review documents the well-characterized links between heavy-metal exposure (Pb, Cd, As, Hg, Cr) and gastrointestinal-related disorders including inflammatory bowel disease, with attention to barrier-function endpoints (tight-junction protein expression, mucus-layer integrity, paracellular permeability) and to immune-homeostasis endpoints (mucosal cytokine balance, regulatory T-cell function).
Key conclusions
Heavy-metal exposure produces a triple insult: barrier dysfunction (claudin and occludin loss; mucus layer thinning), immune dysregulation (cytokine imbalance toward pro-inflammatory states), and microbial dysbiosis (loss of beneficial taxa, rise in pathobionts). The triple insult contributes to systemic inflammation and to gastrointestinal-related chronic disease risk. The review covers each of the major toxic metals individually (Pb, Cd, As, Hg, Cr) with documented epidemiologic and experimental evidence for the barrier-and-microbiome effects.
Implications
- Certification: Mechanistic support for HMTc certification thresholds at the barrier-function and microbiome endpoints, beyond the more traditional cancer and direct-organ-toxicity endpoints. The barrier-and-microbiome axis is increasingly recognized as a sensitive endpoint for chronic low-level heavy-metal exposure.
- Microbiome: Foundational review for the heavy-metal-and-gut-barrier axis. Crosswalks to WikiBiome for barrier-and-microbiome topics.
- Courses: Useful for teaching the gut-barrier-and-microbiome axis in environmental toxicology.