TNF and necrotizing enterocolitis: To study permeability and transcellular transport, 0.4 μm filters are recommended.10 The transwell model can be a good alternative to study the damage effects of molecules against the barrier integrity; for instance, interferon-gamma (IFN-γ) and tumor necrosis factor alpha (TNF) were added into the transwell’s apical or basal side to simulate IBDs’ damage in vitro.11 Similarly, NEC is usually induced by treating IECs lines with LPS and H202 or inflammatory cytokines.12 Different readouts are available to assess the barrier integrity.