Human milk-derived extracellular vesicle treatment promotes the heat shock response in neonates with perinatal high fat diet exposure.

Maternal consumption of a high-fat diet (mHFD) during perinatal life (the collective prenatal and postnatal periods) influences neonatal development, initiates hypothalamic-pituitary-adrenal (HPA) axis activation, and impacts the long-term physiological and metabolic health of offspring. Milk-derived extracellular vesicles (MEVs) are lipid-coated nanovesicles found in mammalian milk that survive intestinal degradation and cross complex biological barriers, including the blood-brain barrier. MEVs have known cytoprotective activity in peripheral organs; however, their pro-survival functions in response to chronic pro-inflammation stemming from early life nutrient stress remain unknown in the neonatal brain. Further, sex differences resulting from MEV treatment require investigation, as male and female neonates illicit variable responses to early life nutrient stress. We investigated whether MEVs promote the heat shock response (HSR), a principal pro-survival mechanism responsible for refolding or degrading misfolded protein aggregates through the action of heat shock protein (HSP) chaperones. We investigated the interaction between MEVs and the HSR in the liver, hypothalamus, and prefrontal cortex in male and female neonatal rats exposed to perinatal mHFD within the stress hyporesponsive period at postnatal day 11. MEV treatment robustly modulated the HSR in female neonates with the largest response recorded in the prefrontal cortex. Specifically, in the prefrontal cortex, MEV treatment led to an upregulation of the main transcription factor (HSF1), while downregulating the negative regulators of HSF1 (Hsp70 and Hsp90). These results suggest that MEVs may influence pro-survival outcomes in the prefrontal cortex by activating HSF1-mediated pro-survival in a sex specific manner in response to mHFD.