Role of M1 Macrophage-Derived Exosomes in Infantile Hemangioma Regression Via AMPK/SIRT1/PGC1α Pathway

Despite being a prevalent benign vascular tumor, infantile hemangioma (IH) is still not well understood concerning its pathogenesis. This study was to investigate the effects of M1 macrophage-derived exosomes (M1-Exos) on hemangioma endothelial cells (HemECs) and their mechanism. Proliferative IH tissues were collected from our hospital and HemECs were isolated. M1 macrophages were obtained from THP-1 cells (M0 macrophages) induced by phorbol myristate acetate using interferon-γ (IFN-γ) and lipopolysaccharide (LPS). M1 macrophage markers (CD80 and CD86) were analyzed by flow cytometry. M1-Exos were extracted and characterized. Following co-culture with M1-Exos, the proliferation of HemECs was evaluated using Cell Counting Kit-8 (CCK-8), 5-Ethynyl-2'-deoxyuridine (EdU), and colony formation assays. Western blot analysis was performed to detect cell proliferation-related proteins, components of the AMP-activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α) pathway, and endothelial-mesenchymal transition (EndMT)-related proteins. Adipogenesis was detected by Oil Red O staining. M1 macrophages were successfully induced and M1-Exos were successfully isolated. M1-Exos inhibited the proliferation of HemECs and inhibited the protein expression of cell proliferation markers (Ki-67 and PCNA). M1-Exos activated the AMPK/SIRT1/PGC1α signaling pathway, as indicated by the increased expression of phospho (p)-AMPK, SIRT1, and PGC1α proteins. The inhibitory effects of M1-Exos on HemEC proliferation and on the protein expression of cell proliferation markers [Ki-67 and proliferating cell nuclear antigen (PCNA)] were attenuated by Compound C (an AMPK inhibitor) or SR-18292 (a PGC1α inhibitor). M1-Exos induced EndMT in HemECs, as evidenced by a decrease in the protein expression of the endothelial markers and an increase in the protein expression of the mesenchymal markers. Moreover, M1-Exos-treated HemECs could differentiate into adipocytes after adipogenic induction. M1-Exos promote IH regression by activating the AMPK/SIRT1/PGC1α pathway and inducing EndMT.