Injured tubule-derived NOV drives pro-inflammatory macrophage activation through NOTCH1/RBPJ signaling in acute kidney injury

Tubular–immune crosstalk contributes to acute kidney injury (AKI), but the mediators involved in this process remain incompletely understood. Nephroblastoma overexpressed (NOV/CCN3), a secreted matricellular protein, may participate in inflammatory responses during ischemia–reperfusion (I/R)-induced AKI. Serum NOV was measured in cardiac surgery patients with or without postoperative AKI. Renal I/R models, recombinant NOV administration, AAV-mediated tubular NOV knockdown, bone marrow-derived macrophages (BMDMs), co-immunoprecipitation, AlphaFold structural modeling, and DAPT-mediated NOTCH inhibition were used to examine the role and mechanism of NOV. Serum NOV was elevated in postoperative AKI patients. In I/R-AKI mice, injured tubular epithelial cells were associated with extracellular NOV accumulation. Recombinant NOV aggravated renal dysfunction and inflammation and promoted pro-inflammatory macrophage infiltration, whereas AAV-mediated NOV knockdown attenuated these responses. In BMDMs, NOV enhanced macrophage inflammatory activation and migration. Mechanistically, NOV-mediated macrophage responses were associated with NOTCH1/RBPJ signaling, and these effects were partially attenuated by the NOTCH inhibitor DAPT. Tubular-derived NOV promotes macrophage inflammatory activation via NOTCH1/RBPJ signaling, identifying NOV as a candidate pathway linking tubular injury to macrophage activation in ischemic AKI.