Immunomodulatory Effects of Human Breast Milk-Derived Exosomes on Myeloid Cells and Chondrocytes

Human breast milk (HBM) is an ideal nutritional source for the growth and development of infants. In addition, HBM contains hormones, growth factors, microRNAs and exosomes that perform various physiological functions. This study investigates the immunomodulatory effects of HBM-derived exosomes on myeloid cells and chondrocytes, and implications for juvenile idiopathic arthritis. HBM-derived exosomes were isolated and characterized using nanoparticle track analyzer and Western blotting. The HBM-derived exosomes treatment decreased the expression of inflammatory mediators and proinflammatory cytokines in mouse peritoneal macrophages upon lipopolysaccharide stimulation. Flow cytometry analysis of bone marrow-derived macrophages indicated that exosomes promoted M2 polarization, as evidenced by a decrease in cells expressing CD80 (M1 marker) and a concurrent increase in cells expressing M2 marker CD206. In addition, exosome treatment attenuated the mitogen-activated protein kinase signaling pathway by reducing the phosphorylation of extracellular signal-regulated kinase, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, and IκB-α, thereby reducing the expression of inducible nitric oxide synthase, cyclooxygenase-2, metalloprotease (MMP)-1, MMP-3, and MMP-13 in SW1353 chondrocytes following IL-1β stimulation. These findings suggest that HBM-derived exosomes promote macrophage polarization toward an anti-inflammatory M2 phenotype and exert significant immunomodulatory effects.