Validation of urinary sphingolipid metabolites as biomarker of effect for fumonisins exposure in Kenyan children

Abstract

Context: Fumonisins (FNs), a group of mycotoxins produced mainly by Fusarium species, are ubiquitous food contaminants, especially for maize. Fumonisin B₁ (FB₁) caused severe toxicities in farm animals, induced kidney and liver tumours in rodents and is associated with many human adverse health effects, including oesophageal cancer. International Agency for Research on Cancer (IARC) categorizes FB₁ as a possible human carcinogen (Group 2B). Inhibition of ceramide synthesis and disruption of sphingolipids metabolism are well studied as the major mechanisms of FB₁-induced toxicity. Increases in sphinganine (Sa) and decrease in sphingosine (So) levels and their ratio are validated biomarkers of FB₁ effects.

Methods: In this study, we measured urinary levels of Sa, So and Sa/So in 284 children aged 1–14 years who consume maize as a staple diet. Exfoliated cells from urine were processed and sphingolipids quantified by High Pressure Liquid Chromatography.

Results and conclusions: Sa and So were detectable in 95.07% and 98.94% of samples, respectively. Creatinine adjusted mean levels and standard deviation of Sa, So and Sa/So ratio were 1.23 ± 2.18, 4.99 ± 8.3 and 0.296 ± 0.587 nM. These results further confirmed the findings in studies with human adults, i.e. urinary Sa, So levels and Sa/So ratio are good biomarkers to assess FNs exposure in children.

Keywords:

• Biomarker
• fumonisins
• mycotoxins
• sphingolipids
• sphinganine
• sphingosine

Acknowledgements

The authors are very grateful for the support of Dr. Charity Mutegi and Dr. Ranajit Bandyopadhyay. We are also grateful for the help for data collection by Simon Ogolla, Francesca Chepkirui, field assistants and all parents who consented to the study procedures.

Disclosure statement

The authors declare no potential or actual conflicts of interest. Neither the International Institute of Tropical Agriculture nor United States Agency for International Development had no role in the design of the study, data collection, laboratory analyses, interpretation of data, writing of this manuscript and the decision to publish the results. Data are available to any scientist for re-analysis.

Additional information

Funding

This study was funded in part by the Agriculture for Nutrition and Health/International Institute of Tropical Agriculture [A4NH/CGIAR/IITA]. The Sphingolipid analysis was supported by the research grant ECG-A-00-07-00001-00 from United States Agency for International Development (USAID) Feed the Future Peanut and Mycotoxin Innovation Laboratory.