重金属および微量金属の毒性が細胞恒常性の破綻に及ぼす影響：関節リウマチ発症の危険因子

Occupational and environmental exposure to heavy and trace metals is increasingly implicated in cellular dysfunction underlying the pathogenesis of rheumatoid arthritis (RA). While trace metals such as selenium (Se), zinc (Zn), and copper (Cu) are essential for the regulation of immune and inflammatory responses, excessive or imbalanced exposure can disrupt physiological homeostasis. In contrast, exposure to heavy metals including lead (Pb), mercury (Hg), cadmium (Cd), and nickel (Ni) poses significant risks to joint health and has been increasingly associated with progressive joint tissue deterioration. Accumulating evidence indicates that metal-induced toxicity disrupts cellular homeostasis by promoting reactive oxygen species (ROS)-mediated oxidative stress and impairing key cellular processes, including apoptosis, ferroptosis, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress. Moreover, heavy metals may interfere with the autophagy-lysosomal pathway, a critical mechanism for maintaining cellular integrity and immune balance. This review underscores the importance of understanding the complex interactions between heavy and trace metal exposure and their roles in cellular dysfunction and joint tissue degeneration. Elucidating the molecular mechanisms underlying metal-induced toxicity is essential for the development of targeted therapeutic strategies and effective preventive interventions aimed at mitigating RA progression.