Date of Award

8-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Food Science

First Advisor

Dr. John Miklavcic

Second Advisor

Vera C. Mazurak

Third Advisor

Anuradha Prakash

Abstract

Extracellular vesicles (EVs) are non-replicating lipid bilayer membrane-bound particle formed by a parent cell and secreted into the extracellular environment. EVs in human milk are bioavailable and influence physiologic pathways that may contribute to newborn growth and development. There is interest in the oxylipin content of EVs that may contribute to the bioavailability of EVs. This research aims to characterize the oxylipin content of human milk EVs. Centrifugation and precipitation were used to isolate EVs from human milk (n = 20). The Folch method was used to extract lipids, and liquid chromatography-mass spectrometry (LC– MS) was used to qualify and quantify the presence of oxylipins. The relative content of oxylipins in human milk EVs were analyzed in relation to the relative content of oxylipins in whole human milk, with values standardized to the total protein content. The research found a higher relative abundance of n-6 PUFA-derived oxylipins (93-97%) than n-3 PUFAs (2.9-6.3%) in both EVs and whole human milk. EVs revealed higher amounts of LA-derived oxylipins (88.37%) than whole human milk (81.69%) (p < 0.0001). While whole human milk displayed higher amounts of AA-, DHA-, and EPA-derived oxylipins (12%, 5.43%, 0.89%, respectively) than EVs (8.74%, 2.71%, 0.18%, respectively) (p-values for AA, DHA, and EPA are 0.0003, < 0.0001, < 0.0001, respectively). Most oxylipins were derived from the LOX pathway in both EVs (93.9%) and whole human milk (90.7%). PGE2, 13-HODE, and 9-HODE were significantly more abundant in EVs (1.64, 1.14, 1.01-fold, respectively), while 17-HDHA, 14-HDHA, and RsVD1 Mix 5 were the three oxylipins most enriched in human milk (0.0485, 0.0425, 0.0371-fold, respectively). The other oxylipins considered significantly higher in human milk than EVs are 13-HDHA, 4-vii HDHA, 12,13-DiHOME, and 11,12-DiHET. This contribution is significant since selected oxylipins present in human milk EVs versus whole human milk may be critical to the bioavailability and passage of dietary EVs across physiologic barriers.

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Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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