Effects of milk extracellular vesicles from Holstein Friesian and Brown Swiss heat-stressed dairy cows on bovine mammary epithelial cells
Author(s)
Date Issued
2025
Type
article
Volume
108
Issue
2
Start Page
1978
End Page
1991
Journal
Abstract
The increase in ambient temperature is responsible
for a behavioral, physiological, and metabolic responses
known as heat stress, which affects dairy cows’ general
well-being, health, reproduction, and productivity. Focusing
on the functioning of the mammary gland, attention
has been recently paid to a new method of cell-cell
communication mediated by extracellular vesicles, which
with their cargo can affect the target cells’ phenotypic
traits, behavior, and biological functions. This study investigated
whether the small extracellular vesicles (sEV)
isolated from milk of heat-stressed Holstein Friesian (H)
and Brown Swiss (B) cows affect the cellular response
of a bovine mammary epithelial cell line (BME-UV1).
To this purpose, 8 mid lactation cows, 4 of each breed
fed the same diet and kept in the same barn, which experienced
the same hyperthermia during a natural heat
wave, were chosen to collect 2 milk different samples:
under thermoneutrality (TN, d1) and under heat stress
(HS, d 8) conditions. The sEV were isolated from skim
milk samples through differential centrifugations, characterized
for size and concentration by nanoparticle
tracking analysis. Integrity of the milk sEV membranes
was evaluated by transmission electron microscopy and
presence of EV markers through western blotting. Then
BME-UV1 cells were incubated for 24 h with different
pooled milk sEVs (H-TN, H-HS, B-TN, B-HS). Cell
viability and apoptosis assay, reactive oxygen species
production, and mRNA expression of heat shock proteins
and antioxidant genes by reverse transcription and real
time PCR were determined. In vivo results showed an
increase in rectal temperature and respiration rate, a reduction
in milk yield both for H and B dairy cows, with
a lowest decrease observed in B cows compared with H
cows. In vitro results of BME-UV1 cells treated with milk sEV H-HS and B-HS showed an alteration of the cell viability
and metabolic activity, by reducing or increasing
reactive oxygen species accumulation, and suppressing
or increasing the expression of stress-associated genes
thereby modulating the response of BME-UV1 according
to the animals’ thermal condition and the breed. These
findings indicated that the small vesicles of Brown milk
triggered cellular defense against heat stress, supporting
the Brown Swiss breed’s thermotolerance.
Project(s)
AGRITECH - European Union Next-GenerationEU CN00000022, 1032 17/06/2022
PRIN 2022 - Resyst - J53D23010270006