Fig 2: LPS activates Toll-like receptor 4, leading to transcription of the IL-1ß gene and translation of the 31-kDa pre-cytokine (pro-IL-1ß). P2X7R exposure to its agonist, BzATP, triggers depolarization via the opening of cation channels, which triggers K+ efflux, leading to stimulation of the NLRP3 inflammasome. Activated caspase-1 converts pro-IL-1ß to the 17-kDa mature protein (IL-1ß), which is then secreted to the extracellular space. A740003, a selective competitive antagonist of P2X7R, blocks P2X7R-mediated calcium influx, pore formation and IL-1ß release. TLR4, Toll-like receptor 4; IL-1ß, interleukin-1ß; P2X7R, purinergic 2X7 receptor; BzATP, 2'(3')-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate triethylammonium salt; NLRP3, NLR family pyrin domain-containing 3; ASC, apoptosis-associated speck-like protein containing a CARD.

Fig 3: Haematoxylin and eosin staining of nasal mucosa and immunolabelling of P2X7R. Numerous eosinophils infiltrated the nasal mucosa of ECRSwNP. (A) Immunofluorescence staining showed that P2X7R was predominantly expressed in epithelial cells and P2X7R protein levels were significantly overexpressed in CRSwNP groups, especially in the ECRSwNP group vs. control group. (B and C) Data represent means ± SD. **P<0.01 and ***P<0.001. CRSwNP, chronic rhinosinusitis with nasal polyps; ECRSwNP, eosinophilic CRSwNP; P2X7R, purinergic 2X7 receptor.

Fig 4: Inflammatory stimulation with LPS combined with BzATP was inhibited by A740003. (A) Western blot analysis of the expression levels of P2X7R (B) and NLRP3 (C) in HNEC after A740003 inhibition of inflammation induced by LPS+BzATP. The expression of P2X7R and NLRP3 was significantly increased in response to LPS plus BzATP; furthermore, the selective P2X7R antagonist, A740003, suppressed this process, decreasing the protein expression of NLRP3 and P2X7R. (D and E) The mRNA expression levels of (D) P2X7R and (E) IL-1ß were decreased after stimulation with LPS+BzATP and subsequent inhibition with A740003. (F) Enzyme-linked immunosorbent assay results show the changes in the concentration of IL-1ß in the cell culture supernatant. *P<0.05 and **P<0.01. NLRP3, NLR family pyrin domain-containing 3; LPS, lipopolysaccharides; BzATP, 2'(3')-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate triethylammonium salt; IL-1ß, interleukin-1ß; P2X7R, purinergic 2X7 receptor.