NLRP3 and NLRP6 expression in pterygium and normal conjunctiva and their relationship with pterygium formation and recurrence

Purpose This study aimed to explore the pterygium formation and recurrence, by detecting the expression of Nod-like receptor pyrin domain 3 (NLRP3) and Nod-like receptor pyrin domain 6 (NLRP6) in pterygium and evaluate the correlation between NLRP3 and NLRP6 in pterygium. Methods In this prospective study, the expression levels of NLRP3 and NLRP6, with their related effectors, were evaluated in primary pterygium (n = 40) and recurrent pterygium (n = 32) tissue samples and compared with normal conjunctiva (n = 11) tissue samples by immunohistochemistry. Results Compared to the normal conjunctiva group, the expression levels of NLRP3, caspase-1, IL-18, and IL-1 beta, were significantly higher, and NLRP6 showed an expression that was significantly lower in pterygium tissue samples (P < 0.05, respectively). Compared to the primary pterygium group, the expression levels of NLRP3, caspase-1, IL-18 and IL-1 beta were significantly higher, and NLRP6 showed an expression that was significantly lower in recurrent pterygium tissue samples (P < 0.05, respectively).There was a negative correlation between NLRP3 expression and NLRP6 expression in normal conjunctival (r = -0.739, P = 0.009) and pterygium (r = -0.533, P = 0.000). Conclusions NLRP3 and NLRP6 may be involved in the formation and recurrence of pterygium. NLRP6 may play an anti-inflammatory role in normal conjunctival tissue to maintain conjunctival homeostasis.