Journal: Cell Insight
Article Title: TNF inhibits SARS-CoV-2 induced cell-cell fusion through activating the SDC4-RhoA signaling to promote actin bundles formation
doi: 10.1016/j.cellin.2026.100310
Figure Lengend Snippet: TNF produced by innate immune cells early after activation inhibit SARS-CoV-2 spike induced cell-cell fusion. (A) Luciferase assay showing the effect of recombinant IL-6 (10 ng/mL), IL-8 (10 ng/mL), or TNF (10 ng/mL) on spike-induced cell-cell fusion. PBS was used as the vehicle control. Data points represent mean ± SEM from four independent experiments; P values are indicated. (B) Luciferase assay showing the effect of supernatant from THP-1 cultures stimulated with Pam3CSK4 for the indicated durations on cell-cell fusion in HEK293T cells pretreated with the IL-1 receptor antagonist (IL-1RA) (4 μg/mL). Data represent mean ± SEM from four independent experiments; P values are shown. (C) Immunoblot analysis of S2′ cleavage in IL-1RA-pretreated fused cells exposed to supernatant from THP-1 cultures stimulated with Pam3CSK4 for the indicated durations. Blots are representative of three independent experiments. (D) ELISA quantification of IL-1β and TNF levels in supernatant from THP-1 cell cultures after stimulation with the indicated TLR ligand at the specified time points. Data represent mean ± SEM from three independent experiments. (E) Luciferase assay showing the effect of supernatant from THP-1 cultures stimulated with Pam3CSK4 for the indicated durations on spike-induced fusion in HEK293T-sgcontrol and HEK293T-sgTNFR1 cells. Data points represent mean ± SEM from six independent experiments; P values are indicated. (F) Immunoblot analysis of S2′ cleavage in HEK293T-sgcontrol and HEK293T-sgTNFR1 fused cells treated with supernatant from THP-1 cell cultures stimulated with Pam3CSK4 for the indicated durations. Blots are representative of three independent experiments. (G) Luciferase assay showing the effect of supernatant from Pam3CSK4-stimulated THP-1 cell cultures on cell-cell fusion in IL-1RA-pretreated HEK293T-sgcontrol and HEK293T-sgTNFR1 cells. Data represent mean ± SEM from four independent experiments; P values are indicated. (H) Immunoblot analysis of S2′ cleavage in IL-1RA-pretreated HEK293T-sgcontrol and HEK293T-sgTNFR1 fused cells exposed to supernatant from Pam3CSK4-stimulated THP-1 cell cultures. Blots are representative of three independent experiments. (I–J) ELISA quantification of IL-1β and TNF levels in supernatant from THP-1 cell cultures under (I) MCC950 pharmacological inhibition of NLRP3, (J) NLRP3 knockout, after stimulation with the indicated TLR ligand at the specified time points. Data represent mean ± SEM from three independent experiments.
Article Snippet: The human monocytic THP-1 cell line (TIB-202; ATCC) was authenticated via short tandem repeat (STR) analysis by Suzhou Genetic Testing Biotech Co., Ltd, following the ANSI/ATCC ASN-0002-2012 standard ( ; ).
Techniques: Produced, Activation Assay, Luciferase, Recombinant, Control, Western Blot, Enzyme-linked Immunosorbent Assay, Inhibition, Knock-Out