TNF and acute kidney injury: In pediatric SA-AKI, TLR4, expressed on renal tubular epithelial cells (RTECs) and endothelial cells, binds lipopolysaccharide (LPS) from Gram-negative bacteria, triggering MyD88-dependent signalling that phosphorylates NF-κB, promoting transcription of pro-inflammatory cytokines like interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α) [74,75].