Endotoxin preconditioning reprograms S1 tubules and macrophages to protect the kidney. Mus musculus

Preconditioning with a small dose of endotoxin confers unparalleled protection against otherwise lethal models of sepsis. The mechanisms of preconditioning have been investigated extensively in isolated immune cells such as macrophages. However, the role of tissue in mediating the protective response to preconditioning remains unknown. Using the kidney as a model organ, we identify the essential role of the renal epithelial cell in mediating the full expression of protective preconditioning. The protective phenotype is characterized by the clustering of macrophages around S1 segments of proximal tubules, which forms a functional unit mediating protection. To investigate the molecular pathways, we laser microdissected S1 segments from the following: 1) Non-preconditioned mice subjected to single-dose 5 mg/kg lipopolysaccharide (0111:B4, LPS) intraperitoneally for 24 hours. 2) Preconditioned mice subjected to 0.25 mg/kg LPS followed 24 hour later by 5 mg/kg LPS (LPS/LPS). 3) Control mice (saline vehicle). Overall design: S1 proximal tubular segments from control, LPS-treated (non-preconditioned) and preconditioned C57BL/6J male mice.