LAUSR

Tumor necrosis factor-α-induced gene/protein (TSG)-6 is a key factor influencing mesenchymal stem cells (MSCs) immunomodulatory properties, but its renoprotective efficacy is unknown. Using a novel swine model of renal artery stenosis (RAS) complicated by metabolic syndrome (Mets), we assessed the therapeutic effects of adipose tissue-derived MSCs-produced TSG-6 and mechanisms underlying the immunomodulatory properties of MSCs. Five groups of pigs (n=6 each) were studied after 16 weeks of diet-induced Mets and unilateral RAS (Mets+RAS), either untreated or treated 4 weeks earlier with a single intra-renal delivery of autologous posrcine adipose tissue-derived MSCs (pMSC). Lean, Mets, and RAS shams served as controls. We studied renal function in vivo (using CT imaging) and kidney histopathology and macrophage phenotype ex vivo. In vitro, TSG-6 levels were measured in conditioned media of human MSCs (hMSCs) incubated with or without TNF-α. Additionally, levels of the tubular injury marker LDH were measured in conditioned media after co-culturing macrophages with injured HK-2 cells (achieved by TNF-α and antimycin-A, AMA) with or without addition of TSG-6. The effects of TSG-6 on macrophage phenotype (M1/M2), adhesion, and migration capability were determined. Mets+RAS pigs showed increased renal M1 macrophages and renal vein TNF-α levels. After p-MSCs delivery, renal vein TSG-6 increased and TNF-α decreased, M1 macrophage switched to M2 (Fig. A),, renal function improved, and fibrosis alleviated. In vitro, TNF-α increased TSG-6 secretion by h-MSCs. TSG-6 decreased LDH release from injured HK-2, induced a macrophage phenotypic switch from M1 to M2 (Fig. B), and reduced M1 macrophage adhesion and migration (Fig. C). TNF-α-induced TSG-6 release from MSCs in vivo and in vitro may decrease renal tubular cells injury, which is associated with and may be at least in part mediated by regulating macrophage function and phenotype.