A blood spot method for detecting fumonisin-induced changes in putative sphingolipid biomarkers in LM/Bc mice and humans

Abstract

Fumonisins (FB) are mycotoxins found in maize. They are hypothesised risk factors for neural tube defects (NTDs) in humans living where maize is a dietary staple. In LM/Bc mice, FB1-treatment of pregnant dams induces NTDs and results in increased levels of sphingoid base 1-phosphates in blood and tissues. The increased level of sphingoid base 1-phosphates in blood is a putative biomarker for FB1 inhibition of ceramide synthase in humans. Collection of blood spots on paper from finger sticks is a relatively non-invasive way to obtain blood for biomarker analysis. The objective of this study was to develop and validate in an animal model, and ultimately in humans, a method to estimate the volume of blood collected as blood spots on absorbent paper so as to allow quantification of the molar concentration of sphingoid base 1-phosphates in blood. To accomplish this objective, blood was collected from unexposed male LM/Bc and FB1-exposed pregnant LM/Bc mice and humans and applied to two types of absorbent paper. The sphingoid base 1-phosphates, absorbance at 270 nm (A270), and total protein content (Bradford) were determined in the acetonitrile:water 5% formic acid extracts from the dried blood spots. The results show that in both mouse and human the A270, total protein, and blood volume were closely correlated and the volume of blood spotted was accurately estimated using only the A270 of the extracts. In mouse blood spots, as in tissues and embryos, the FB1-induced changes in sphingolipids were correlated with urinary FB1. The half-life of FB1 in the urine was short (<24 h) and the elevation in sphingoid base 1-phosphates in blood was also short, although more persistent than the urinary FB1.

Evidence for fumonisin inhibition of ceramide synthase in humans consuming maize‐based foods and living in high exposure communities in Guatemala

“…Are the positive correlations between UFB 1 levels, calculated FB intake, and Sa 1‐P concentration and Sa 1‐P/So 1‐P ratio proof that FB inhibits CerS in humans consuming diets containing high levels of FB? Primary cultures of human neural progenitor cells respond to FB 1 treatment by accumulating large amounts of Sa and Sa 1‐P and much lesser amounts of So and So 1‐P , similar to what has been reported in numerous animal studies and attributed to de novo CerS inhibition as first demonstrated by Wang et al. .…”

“…Based on the unique functional and metabolic characteristics of So 1‐P in blood, and in particular the fact that RBC cannot make Sa or metabolize Sa 1‐P, we hypothesized that blood spots from Guatemalan women living in areas where FB exposure is high would show higher Sa 1‐P/So 1‐P ratios when compared to populations living in low exposure areas, reflecting the increased Sa produced in cells and tissues as a consequence of FB‐induced CerS inhibition. Consistent with this hypothesis would be elevated concentrations of Sa 1‐P in the blood spots as we have seen in mice . In mice the levels of Sa 1‐P in the RBC closely paralleled the levels of Sa seen in liver and kidney and the UFB 1 .…”

“…A brief description of the rationale for using FTA™ Elute Micro Cards is contained in the introductory paragraph of the Supplemental Data in Riley et al. .…”

“…A detailed description of the chromatographic and MS parameters, recovery of sphingoid bases and sphingoid base 1‐phosphates by the extraction process, and the stability of sphingoid base 1‐phosphates in blood spots collected on FTA™ Elute Micro Cards is reported in Riley et al. .…”

Validation of Dried Blood Spot Cards to Determine Apple Phenolic Metabolites in Human Blood and Plasma After an Acute Intake of Red‐Fleshed Apple Snack

“…When droplet of capillary blood is directly deposited on the filter paper, the volume of this blood cannot be precisely controlled and inaccuracies in quantification values can be obtained due to differences in hematocrit. In the literature, different strategies to overcome this drawback have been proposed, such as the use of volumetric absorptive microsampling (VAMS) or the photometric measurement of the protein content . In the present study, a simplified strategy to quantify the phenolic metabolites was tested, assuming a linear relation between volume of blood applied and the area of the premarked DBS circle.…”