When miRNAs such as miR-31 and miR-203 were down-regulated in NEC tissues, they could potentiate the upsurge of proinflammatory signals mediated by TLR4, key transcription factor NFκB, hypoxia/oxidative regulators HIF1A and PTGS2, inflammatory cytokines and chemokines TNF and IL8, as well as angiogenic factor HBEGF, resulting in extensive mucosal injury (Fig 3). Here, TLR4 is linked to necrotizing enterocolitis.