Hemodialysis and erythrocyte epoxy fatty acids

Abstract

Fatty acid products derived from cytochromes P450 (CYP) monooxygenase and lipoxygenase (LOX)/CYP ω/(ω‐1)‐hydroxylase pathways are a superclass of lipid mediators with potent bioactivities. Whether or not the chronic kidney disease (CKD) and hemodialysis treatments performed on end‐stage renal disease (ESRD) patients affect RBC epoxy fatty acids profiles remains unknown. Measuring the products solely in plasma is suboptimal. Since such determinations invariably ignore red blood cells (RBCs) that make up 3 kg of the circulating blood. RBCs are potential reservoirs for epoxy fatty acids that regulate cardiovascular function. We studied 15 healthy persons and 15 ESRD patients undergoing regular hemodialysis treatments. We measured epoxides derived from CYP monooxygenase and metabolites derived from LOX/CYP ω/(ω‐1)‐hydroxylase pathways in RBCs by LC–MS/MS tandem mass spectrometry. Our data demonstrate that various CYP epoxides and LOX/CYP ω/(ω‐1)‐hydroxylase products are increased in RBCs of ESRD patients, compared to control subjects, including dihydroxyeicosatrienoic acids (DHETs), epoxyeicosatetraenoic acids (EEQs), dihydroxydocosapentaenoic acids (DiHDPAs), and hydroxyeicosatetraenoic acids (HETEs). Hemodialysis treatment did not affect the majority of those metabolites. Nevertheless, we detected more pronounced changes in free metabolite levels in RBCs after dialysis, as compared with the total RBC compartment. These findings indicate that free RBC eicosanoids should be considered more dynamic or vulnerable in CKD.

Hemodialysis and biotransformation of erythrocyte epoxy fatty acids in peripheral tissue

“…Moreover, similar results were found for free erythrocyte epoxy-metabolites (Table 3B). Together, the findings indicate that CYP epoxy-metabolites are unequally hydrolyzed by sEH in arterial and venous blood in vivo [14,18]. However, there is no arteriovenous difference in the erythro-epoxides before hemodialysis.…”

“…Sample preparation and preprocessing, standardization, HPLC-MS detection and data processing were performed as described in [15,16]. All samples were analyzed for free and total RBC fatty acid metabolites [14,17].…”

“…We recently established the lipidomics approach for the analysis of oxylipins derived from CYP monooxygenase and LOX/CYP ω/(ω-1)-hydroxylase pathways in human RBCs [14] (Fig. 1).…”

“…10,11-DiHDPA), respectively, by the soluble epoxide hydrolase (sEH) enzyme. Modified from [14]. The metabolites measured within these pathways track the changes observed.…”

“…arterial RBCs after hemodialysis [14]. To gain information on lipid biotransformation in RBCs, we now collected arterial and venous blood samples in upper extremities from ESRD patients and tested the hypothesis that hemodialysis affects the arteriovenous difference of these metabolites in vivo (Fig.…”