Lactoferrin protects against radiation-induced intestinal injury by regulating pyroptosis and mitophagy

Abstract

The imbalance between pyroptosis and mitophagy constitutes a key pathogenic axis in radiation-induced intestinal injury (RIII). Lactoferrin (Lf), a multifunctional glycoprotein with well-recognized antioxidant and anti-inflammatory properties, has not been fully characterized in relation to RIII. This study investigated the potential protective effects of Lf on RIII using rat intestinal epithelial IEC-6 cells exposed to 4 Gy X-ray irradiation and male C57BL/6J mice subjected to 10 Gy total-abdominal irradiation. Radiation induced pyroptosis and mitochondrial dysfunction in vitro and in vivo. Lf pretreatment reduced radiation-induced ROS accumulation, inhibited activation of the NOD-like receptor protein 3 (NLRP3)/caspase-1/ gasdermin-D (GSDMD) pyroptosis pathway, and activated mitophagy to remove damaged mitochondria in irradiated IEC-6 cells. Consistently, Lf protected against RIII in irradiated mice by promoting mitophagy and suppressing pyroptosis. Mechanistically, these effects involved activation of ubiquitin-dependent (PINK1/Parkin-mediated) and ubiquitin-independent (FUNDC1/BNIP3/NIX receptor-driven) mitophagy pathways. The mitophagy-promoting effect of Lf was more pronounced on day 3.5 after radiation than on day 14. Notably, pharmacological inhibition of mitophagy with 3-Ma and Mdivi-1 abolished the protective effects of Lf. Collectively, our in vivo and in vitro findings demonstrate that Lf mitigates RIII by facilitating early clearance of damaged mitochondria, thereby inhibiting NLRP3 inflammasome activation and suppressing pyroptosis.