PROS1 and atopic eczema: A recent study, investigating the effects of AD-MSCs exosomes in a particulate matter (PM)-induced model of atopic dermatitis, found that PM-AD model treated with AD-MSCs exosomes had a decreased expression of proinflammatory cytokines like IL-6, IL-1β and IL-1α and a higher expression of skin barrier proteins like loricrin and filaggrin, compared to untreated PM-AD model (49).