Circulating intestine-derived exosomal miR-328 in plasma, a possible biomarker for estimating BCRP function in the human intestines

Abstract

A variant in the breast cancer resistance protein (BCRP) gene, 421C> A is a useful biomarker for describing large inter-individual differences in the pharmacokinetics of sulfasalazine (SASP), a BCRP substrate. However, large intra-genotypic variability still exists in spite of the incorporation of this variant into the pharmacokinetics of SASP. Since miR-328 negatively regulates BCRP expression in human tissues, we hypothesized that exosomal miR-328 in plasma, which leaks from the intestines, is a possible biomarker for estimating BCRP activity in the human intestines. We established an immunoprecipitation-based quantitative method for circulating intestine-derived miR-328 in plasma using an anti-glycoprotein A33 antibody. A clinical study was conducted with an open-label, non-randomized, and single-arm design involving 33 healthy participants. Intestine-derived exosomal miR-328 levels positively correlated (P < 0.05) with SASP AUC0-48, suggesting that subjects with high miR-328 levels have low intestinal BCRP activity, resulting in the high AUC of SASP. Circulating intestine-derived exosomal miR-328 in plasma has potential as a possible biomarker for estimating BCRP function in the human intestines.

From Endogenous Compounds as Biomarkers to Plasma‐Derived Nanovesicles as Liquid Biopsy; Has the Golden Age of Translational Pharmacokinetics‐Absorption, Distribution, Metabolism, Excretion‐Drug–Drug Interaction Science Finally Arrived?

“…Exosomes can be isolated from the medium of cultured cells and human biofluids using different methods, such as ultracentrifugation, size‐exclusion chromatography, precipitation with polyethylene glycol, and microfluidics‐based nanofiltration and affinity chips . Immunocapture, or immunoprecipitation (IP), methods hold considerable promise because antibodies to organ‐specific (enriched) exosomal surface proteins can be immobilized on magnetic beads that enable the isolation and enrichment of individual organ‐derived exosomes from plasma …”

“…Once confirmed, the exosomal cargo can be profiled for various miRs, mRNAs, proteins, genotype, as well as DMEs and possibly transporter activity . The presence of multiple miR species in exosomes is important, because the expression of many ADME proteins in different organs is associated with specific miRs .…”

“…A second report focused on the correlation of intestinal miR‐328 expression with the area under the plasma concentration‐time curve (AUC) of an orally dosed BCRP substrate (sulfasalazine (SASP)) . Because gut ABCG2 (BCRP) is expressed polymorphically, subjects carrying the loss‐of‐function variant allele (c.421C>A; 141Q>K) present higher (up to threefold) SASP plasma AUCs, and miR‐328 is known to mediate ABCG2 expression, it was thought that intestinal miR‐328 levels might correlate with SASP plasma AUC .…”

“…Both methodologies have great potential especially if used jointly but will require thorough characterization and validation prior to acceptance by greater numbers of ADME scientists and agency‐based reviewers. Evidently, considerable advancements have been made isolating and characterizing exosomes from different biological matrices . However, the majority of ADME scientists are not familiar with the various types of EVs and methods supporting their isolation and characterization ( Table ).…”

“…In reality, such an effort can only be supported by the increased availability of quality reagents enabling the isolation of tissue‐derived exosomes (e.g., bead‐immobilized antibody IP‐based methods). The anti‐GPA33 IP‐based approach, described by Gotanda et al . for intestine‐derived plasma exosomes is illustrative and could be a model for other organs, such as the liver, brain, kidneys, lungs, and muscles.…”