Molecular Insights Into TNF‐α and IFN‐γ‐Induced Epithelial Cell Death in Toxic Epidermal Necrolysis

Rapid and extensive epithelial cell death in skin and mucous membranes is the hallmark of Toxic epidermal necrolysis (TEN). High levels of TNF-α and IFN-γ have been detected in the blister fluids of skin lesions in TEN patients. Available literature shows that TNF-α synergy with IFN-γ (TNF-α/IFN-γ) elicited cell death in diverse cells. Thus, the cytotoxic effect and underlying mechanism of TNF-α and IFN-γ on HaCaT cells were investigated. Confluent HaCaT cells were subjected to serial doses of either TNF-α alone, IFN-γ alone, or combination TNF-α with IFN-γ (TNF-α/IFN-γ) for indicated time intervals. The cytotoxicity were then evaluated by morphologic change and trypan blue exclusion assay. The mechanism involving in TNF-α and IFN-γ-elicited HaCaT cell death were examined through the change expression of c-GSDM-E, c-Caspase-3, p-MLKL expression by western blot. TNF-α/IFN-γ significantly induced HaCaT cell death and showed a dose- and time-dependent manner. However, TNF-α alone or IFN-γ alone failed to do it. Western blot analysis confirmed that TNF-α/IFN-γ triggers HaCaT cell death through PANoptosis, as evidenced by increased expression levels of c-GSDMD, c-GSDME, c-Caspase-3, and phospho-MLKL (pMLKL). High level of TNF-α and IFN-γ are the main cause to induce epithelial cell death of skin in TEN. These suggest that drugs with the potential to inhibit TNF-α and IFN-γ expression and downstream signaling could be developed as treatments for TEN in the future.