Overview
This 22-page review synthesizes mechanistic evidence on how environmental pollutants — prominently lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) — alter immune function through epigenetic mechanisms. The authors cover three levels of epigenetic regulation: DNA methylation, histone modification, and non-coding RNA expression. A distinct section addresses transgenerational transmission of immune-epigenetic marks, drawing on zebrafish and mammalian models. The review is relevant to the immunotoxicology topic because it establishes the molecular layer connecting metal exposures to altered cytokine gene expression and long-lived immune dysregulation.
Key numbers
- Lead activates TLR4-NF-kB signaling, elevating IL-1beta and IL-6 at the transcriptional level.
- Cadmium triggers both TLR and NLRP3 inflammasome pathways, increasing TNF-alpha and IFNgamma expression.
- Mercury and arsenic suppress inflammasome activity, indicating metal-specific immunosuppressive profiles alongside pro-inflammatory effects documented in other systems.
- Mercury exposure induces H3K27me3 (a repressive histone mark) on immune-regulatory gene loci.
- Cadmium disrupts global DNA methylation patterns.
- Transgenerational effect (zebrafish model): cadmium-induced DNA methylation changes in exposed fish persisted across the F1-F4 generations.
- Key microRNA biomarkers identified: miR-21 and miR-155, both of which regulate cytokine signaling cascades, are dysregulated by metal exposures.
- IL-6 and IFNgamma gene loci show altered methylation profiles in metal-exposed organisms.
Methods (brief)
Narrative review. Literature drawn from PubMed and Web of Science; inclusion criteria covered animal models, in vitro mechanistic studies, and human epidemiological data. No primary exposure measurements; all numbers are derived from cited primary studies. No LOD/LOQ reported (review article).
Implications
Certification: Establishes the biological mechanism by which low-level, chronic dietary metal exposure can alter immune gene expression across generations. Relevant to HMT&C’s rationale for multi-metal, multi-generation risk framing.
Courses: Useful for the epigenetic module and the immunotoxicology module. The transgenerational finding supports framing dietary metal exposure as a family-level, not just individual, risk.
App: Does not contribute concentration data. Contributes mechanistic context for the contamination risk framing of Pb, Cd, As, and Hg.
Microbiome: Review does not address gut microbiota directly; the immune-epigenetic pathway it documents is upstream of microbiota-immune crosstalk covered in companion sources.
Related evidence
Update history
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