Neutrophil Extracellular Traps Drive a skin-kidney inflammatory axis in UVB-Irradiated Lupus-Prone Mice

Neutrophil extracellular traps (NETs) are major pathogenic effectors in chronic systemic lupus erythematosus (SLE) pathogenesis, but how they mediate acute, UVB-triggered skin inflammation and subsequent systemic injury remains poorly defined. Using UVB-irradiated lupus-prone mice, we identified an acute NETosis-driven skin-kidney inflammatory axis linking photosensitivity to renal inflammation. UVB induced concurrent skin and kidney inflammation with neutrophil infiltration, NETosis, and release of NET-associated effector cytokines/complement C3 and proteinuria. Mechanistically, PKC-dependent nuclear envelope rupture licensed NETosis, whereas Pkc deletion markedly suppressed NET formation and inflammation in both organs. Interestingly, only a subset of skin-infiltrating neutrophils underwent local NETosis. Spatiotemporal photoconversion tracking revealed that surviving, CXCR4-expressing neutrophils disseminated from UVB-irradiated skin to kidneys, where they underwent secondary NETosis, delivering cytokines/C3 to drive renal inflammation. Genetic or pharmacological CXCR4 inhibition blocked this dissemination, attenuating renal inflammation and proteinuria. These findings identify an acute NETosis-driven skin-kidney axis, highlighting PKC-dependent NETosis and CXCR4-mediated neutrophil dissemination as therapeutic targets in photosensitive lupus.