The involvement of human breastmilk-derived extracellular vesicles in the development of infant atopic sensitization.

Breastmilk, with its unique biological components, is the optimal source of neonatal nutrition, and WHO global feeding guidance recommends that all infants are exclusively breastfed for the first 6 months. The composition of human milk depends on multiple factors such as maternal diet, exposure to pathogens, metabolic or autoimmune disorders, smoking, mental health, and genetics. Breastfeeding not only transfers nutrients to the child, but it also influences the infant immune function, through the transfer of immune cells, antibodies, microbiota from the mother, cytokines, or growth factors. Among these, human milk-derived extracellular vesicles (hMEVs) are emerging as key yet understudied elements in neonatal growth, development, and immunity. This review explores their structure, formation, uptake, and roles in supporting development, modulating immune responses during early life, and influencing allergic outcomes, highlighting their potential significance in infant health.