MFG-E8 Plays an Important Role in Attenuating Cerulein-Induced Acute Pancreatitis in Mice

Synergistic effects of MFG-E8 and whey protein on mitigating d-galactose-induced sarcopenia through PI3K/AKT/PGC-1α and MAPK/ERK signaling pathways

Milk fat globule epidermal growth factor 8 (MFG-E8) and whey protein have emerged as promising bionutrient supplements for enhancing skeletal muscle mass and function. In the present study, aging-related sarcopenia rat model was employed to elucidate the effects of the combined administration of MFG-E8 and whey protein on the catabolism and anabolism of gastrocnemius protein. Combined intervention led to notable enhancements in the antioxidative stress status and mitochondrial biogenesis capacity of gastrocnemius muscle fibers in the aging rats, concomitant with a significant inhibition of lipid accumulation. Moreover, the synergistic effect of MFG-E8 and whey protein was found to exert modulatory effects on key signaling pathways, including PI3K/Akt/PGC-1α pathway and MAPK/ERK signaling pathways in the gastrocnemius muscle of the aging rats. Specifically, this combined intervention was observed to promote mitochondrial biogenesis and regulate the expression of protein anabolism and catabolism-related regulators, thereby facilitating the alleviation of mitochondrial oxidative stress and enhancing biogenesis in gastrocnemius tissues. The findings of our study provide compelling evidence for the potential of MFG-E8 as a promising dietary supplement with antisarcopenic properties to ameliorate muscle protein metabolism disorders and mitigate mitochondrial-mediated myoblast apoptosis induced by oxidative stress.

Human cell-expressed tag-free rhMFG-E8 as an effective radiation mitigator

Human milk fat globule epidermal growth factor-factor VIII (MFG-E8) functions as a bridging molecule to promote the removal of dying cells by professional phagocytes. E. coli-expressed histidine-tagged recombinant human MFG-E8 (rhMFG-E8) is protective in various disease conditions. However, due to improper recombinant protein glycosylation, misfolding and the possibility of antigenicity, E. coli-expressed histidine-tagged rhMFG-E8 is unsuitable for human therapy. Therefore, we hypothesize that human cell-expressed, tag-free rhMFG-E8 will have suitable structural and functional properties to be developed as a safe and effective novel biologic to treat inflammatory diseases including radiation injury. We produced a new tag-free rhMFG-E8 protein by cloning the human MFG-E8 full-length coding sequence without any fusion tag into a mammalian vector and expressed it in HEK293-derived cells. The construct includes the leader sequence of cystatin S to maximize secretion of rhMFG-E8 into the culture medium. After purification and confirmation of the protein identity, we first evaluated its biological activity in vitro. We then determined its efficacy in vivo utilizing an experimental rodent model of radiation injury, i.e., partial body irradiation (PBI). HEK293 cell supernatant containing tag-free rhMFG-E8 protein was concentrated, purified, and rhMFG-E8 was verified by SDS-PAGE with the standard human MFG-E8 loaded as control and, mass spectrometry followed by analysis using MASCOT for peptide mass fingerprint. The biological activity of human cell-expressed tag-free rhMFG-E8 was superior to that of E. coli-expressed His-tagged rhMFG-E8. Toxicity, stability, and pharmacokinetic studies indicate that tag-free rhMFG-E8 is safe, highly stable after lyophilization and long-term storage, and with a terminal elimination half-life in circulation of at least 1.45 h. In the 15 Gy PBI model, a dose-dependent improvement of the 30-day survival rate was observed after tag-free rhMFG-E8 treatment with a 30-day survival of 89%, which was significantly higher than the 25% survival in the vehicle group. The dose modification factor (DMF) of tag-free rhMFG-E8 calculated using probit analysis was 1.058. Tag-free rhMFG-E8 also attenuated gastrointestinal damage after PBI suggesting it as a potential therapeutic candidate for a medical countermeasure for radiation injury. Our new human cell-expressed tag-free rhMFG-E8 has proper structural and functional properties to be further developed as a safe and effective therapy to treat victims of severe acute radiation injury.