Association of α-klotho and lead and cadmium: A cross-sectional study

Epigenetic aging is associated with harmful health effects such as oxidative stress from heavy metal exposure. We considered the relationship between genes and heavy metals in association with oxidative stress and then investigated the association between serum alpha-klotho and lead and cadmium exposure among adults in the United States from 2007 to 2016 participating in the National Health and Nutrition Examination Survey (NHANES). Samples included 9800 adults aged 40 to 79 years with measurements of serum alpha-klotho, lead and cadmium, and complete covariate data. Lead and cadmium levels were measured by inductively coupled plasma mass spectrometry and serum alpha-klotho levels were measured using enzyme-linked immunosorbent assay (ELISA). Multivariate linear regression analysis was used to estimate the association between serum alpha-klotho and blood lead, blood cadmium, and urinary cadmium. A percent increase in blood lead, blood cadmium, and urinary cadmium was associated with a statistically significant 4.0 % (p < 0.001), 2.0 %, (p = 0.003) and 1.0 % (p = 0.020) decrease in serum klotho. After adjustment, a percent increase in blood lead was associated with a statistically significant 4.0 % (p < 0.001) decrease in serum klotho; blood and urinary cadmium did not show any statistically significant associations after adjustment (beta (95 % CI), p-value for blood cadmium: 0.00 (-0.02-0.01), p = 0.573; urinary cadmium: -0.01 (-0.03-0.01), p = 0.210). Mean serum klotho levels showed a statistically significant decreasing trend with increasing blood lead quartiles (unadjusted and all-adjusted geometric means and 95 % confidence intervals of serum klotho (in pg/mL) for Q1, Q2, Q3, and Q4: unadjusted: 827.49 (814.20-840.92), 811.92 (794.73-829.48), 791.48 (775.11-808.19), and 772.01 (754.23-790.29); adjusted: 830.64 (805.53-856.45), 816.07 (789.18-843.87), 800.71 (773.71-828.57), and 784.31 (757.94-811.59)). Blood lead and levels were negatively associated with serum alpha-klotho levels in a representative population of US adults. These results suggest that blood lead levels may be associated with the serum levels of a protein associated with cognition and aging. Further research is recommended to investigate the causality behind such relationship.

Automated summary

This study investigated the association between blood lead and cadmium exposure and serum alpha-klotho levels among adults in the United States. The results showed a negative correlation between blood lead and cadmium levels and serum klotho levels.