Pyroptosis in pterygium pathogenesis

Pterygium is a common ocular disease characterized by proliferating fibrovascular tissue. Pyroptosis, a recently discovered programed cell death, is known to be associated with oxidative stress, one of the main causes of pterygia. Here, we aimed to study the role of pyroptosis in pterygium pathogenesis. The expression of nod-like receptor pyrins-3 (NLRP3), caspase-1, IL-18, and IL-1 beta was analyzed in 60 human pterygium tissues and 60 human conjunctival epithelium tissues using real-time quantitative polymerase chain reaction (qRT-PCR) and Western blot analysis. Human conjunctival epithelial cells (HConECs) and human pterygium fibroblasts (HPFs) were primary cultured and the level of pyroptosis-associated factors was detected. Both cells were treated with H2O2, and cell lysis was detected by lactate dehydrogenase (LDH) release assay, the expression of the factors by qRT-PCR, Western blot analysis, and immunostaining. The downstream factors IL-18 and IL-1 beta were measured after inhibition of caspase-1 to confirm the caspase-1-dependent pyroptosis. alpha-SMA and E-cadherin were detected as indicators of pyroptosis-induced myofibroblast activation in HPFs. We discovered that the expression of the factors was significantly increased in pterygium and that caspase-1-dependent pyroptosis presents in both H2O2-treated HPFs and HConECs during which the expression of these factors was significantly elevated and the elevation of downstream factors IL-18 and IL-1 beta was restrained after caspase-1 inhibition. alpha-SMA increase and E-cadherin down-regulation were detected in H2O2-treated HPFs and the changes were reversed by caspase-1 inhibition. Pyroptosis displays a role in the pathological process of pterygium formation and progression. Pyroptosis appears to be an intriguing target to prevent pterygium pathogenesis.