Relationship between NLRP3 expression and mitochondrial function during mechanical stretch-induced damage to mouse alveolar epithelial cells

Abstract

Objective To evaluate the relationship between the expression of Nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) in nerve tissues and mitochondrial function during mechanical stretch-induced damage to mouse alveolar epithelial cells. Methods Alveolar epithelial type Ⅱ cell line MLE-12 cells were divided into 3 groups (n=13 each) using a random number table: control group (group C), cyclic stretch group (group CS) and cyclic stretch plus NLRP3 inhibitor TAK-242 group (group CS+ T). MLE-12 cells underwent 20% cyclic stretch at a frequency of 0.5 Hz (stretch∶intermittence =1∶1) for 4 h in group CS.In group CS+ T, after being incubated for 1 h with 1 μmol/L TAK-242, MLE-12 cells underwent 20% cyclic stretch for 4 h, and the parameters were similar to those previously described in group CS.The reactive oxygen species (ROS) content and mitochondrial membrane potential (ΔΨM)were measured using chemiluminescence assay.Enzyme-linked immunosorbent assay was used to determine the concentration of interleukin-1beta (IL-1β) in the supernatant.The expression of NLRP3 in MLE-12 cells was detected using Western blot. Results Compared with group C, the ΔΨM of cells was significantly decreased, the ROS content and IL-1β concentration were increased, and the expression of NLRP3 was up-regulated in group CS, and the ΔΨM of cells was significantly decreased, the ROS content was increased, and the expression of NLRP3 was up-regulated in group CS+ T (P<0.05). Compared with group CS, the ΔΨM of cells was significantly increased, the ROS content and IL-1β concentration were decreased, and the expression of NLRP3 was down-regulated in group CS+ T (P<0.05). Conclusion Mechanical stretch induces damage to mitochondria through up-regulating the expression of NLRP3, thus leading to damage to mouse alveolar epithelial cells. Key words: Biomechanics; Epithelial cells; Pulmonary alveoli; Mitochondria; NLR family, pyrin domain-containing 3 protein