Recognition of lipopolysaccharide (LPS) in the cell wall of Enterobacteriaceae by the host Toll-like receptor (TLR)4 is important in the pathogenesis of NEC, and both inhibition of TLR4 and manipulation of the intestinal microbiota with probiotic organisms prevents this disease (16, 17). Here, TLR4 is linked to necrotizing enterocolitis.