Growth Differentiation Factor 15 ( GDF15 ) Protects Against Sepsis‐Associated Acute Kidney Injury via Suppression of TLR4 ‐ Chengyi Yang, Le Zhao, Jia Di, Qiangyan Hu

ABSTRACT

Sepsis‐associated acute kidney injury (SAKI) lacks mechanism‐based therapies, with upstream ferroptosis regulators undefined. This study investigated growth differentiation factor 15 (GDF15) as a suppressor of TLR4‐MyD88‐NF‐κB signaling and associated ferroptosis. Differential GDF15 expression was identified by integrated analysis of three GEO datasets (GSE232404, GSE30718, GSE44925) and validated in SAKI patient kidney tissue ( n  = 30 vs. controls n  = 25) and in kidneys from cecal ligation and puncture (CLP) mice. CLP mice received recombinant GDF15 (rmGDF15) (50 ng/kg ip); renal function (Scr/BUN), histology, kidney injury molecule‐1 (KIM‐1), serum TNF‐α/IL‐1β/IL‐6 (ELISA), and 7‐day survival were assessed. Oxidative stress/ferroptosis was quantified by DCFH‐DA ROS imaging and kits (MDA, GSH, SOD, NADPH, Fe, GPX4 activity); TLR4‐MyD88‐NF‐κB by qRT‐PCR, Western blot, and Immunohistochemistry. LPS (1 μg/mL, 48 h)‐stimulated HK‐2 cells underwent shGDF15 lentiviral knockdown (puromycin 2 μg/mL) ± TAK242 (1 μM); viability (CCK‐8), apoptosis (Annexin V/PI flow), cytokines (ELISA/qRT‐PCR), ROS, ferroptosis markers, and pathway activation were evaluated. GDF15 was upregulated in SAKI datasets, patient kidney tissue, and CLP kidneys. GDF15 supplementation improved survival, lowered Scr/BUN and KIM‐1, attenuated tubular injury, and reduced systemic proinflammatory cytokines. It decreased renal ROS, MDA and Fe while restoring GSH, SOD, NADPH, GPX4 activity, and SLC7A11 expression, and suppressed TLR4‐MyD88‐NF‐κB signaling. In HK‐2 cells, GDF15 silencing aggravated LPS‐induced loss of viability, apoptosis, cytokine release, oxidative stress, and ferroptosis markers, all reversed by TAK242. In conclusion, GDF15 is a stress‐inducible renoprotective factor that suppresses TLR4 signaling, ferroptosis markers, and inflammation in SAKI, suggesting exogenous administration as a promising therapeutic strategy.