Endogenous oxidized phospholipid POVPC triggers pulmonary epithelial ferroptosis in acute lung injury and is restrained by RCN3.

BACKGROUND

Ferroptosis contributes to acute lung injury (ALI), but whether endogenous oxidized phospholipids trigger epithelial ferroptosis and which intracellular defenses restrain this process remain unclear. We hypothesized that the oxidized phosphatidylcholine POVPC initiates epithelial ferroptosis and that RCN3 functions as a protective intracellular safeguard.

METHODS

POVPC and PGPC were quantified in LPS-induced ALI lungs by mass spectrometry. ALI was modeled by intratracheal administration of POVPC, with equimolar PGPC as a structural control. Pulmonary epithelial cells were exposed to POVPC in vitro to assess ferroptosis. The causal role of RCN3 was investigated using AECII-specific RCN3 knockout mice and AECII-targeted AAV6-RCN3 overexpression.

RESULTS

POVPC, but not PGPC, was significantly increased in LPS-induced ALI lungs and reproduced ferroptosis-associated lung injury upon intratracheal delivery. In vitro, POVPC exposure induced pronounced ferroptosis in pulmonary epithelial cells, characterized by iron accumulation, lipid peroxidation, and depletion of GSH, GPX4, and SLC7A11, which was reversed by ferrostatin-1 and deferoxamine. POVPC elicited a transient epithelial RCN3 upregulation; however, sustained or high-dose exposure led to RCN3 exhaustion accompanied by exacerbated ferroptosis. RCN3 knockdown aggravated, whereas its overexpression attenuated, POVPC-induced ferroptosis. Consistently, AECII-specific RCN3 deletion sensitized mice to POVPC-induced ALI, while AECII-targeted AAV6-RCN3 delivery alleviated lung injury and ferroptosis.

CONCLUSIONS

POVPC acts as an endogenous contributor of epithelial ferroptosis in ALI and RCN3 functions as a stress-responsive intracellular gatekeeper that limits lipid peroxidation and preserves epithelial ferroptosis resistance.