To investigate the regulatory effects of paeonol on autophagy and the NOD-like receptor protein 3 (NLRP3) inflammasome in human renal proximal tubular epithelial cells (HK-2) induced by human serum albumin (HSA).

HK-2 cells were cultured in vitro and randomly assigned to control group, model group, as well as low-, medium- and high-dose experimental groups. Cells in the control group were cultured under normal conditions; those in the model group were treated with 20 mg·mL^-1 HSA for 24 h; and cells in the low-, medium- and high-dose experimental groups were administered 25, 50 and 100 μmol·L^-1 paeonol, respectively, for 24 h on the basis of the model group intervention. Enzyme-linked immunosorbent assay (ELISA) was performed to determine the concentrations of kidney injury molecule 1 (KIM-1), monocyte chemoattractant protein 1 (MCP-1), interleukin 1β (IL-1β) and caspase-1 in the cell supernatant. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the mRNA expression levels of KIM-1 and MCP-1. Western blotting was applied to measure the protein expression levels of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), interleukin-1β (IL-1β), microtubule-associated protein 1 light chain 3 (LC3), sequestosome 1(p62), Beclin-1, PTEN-induced kinase 1 (PINK1) and Parkin.

The concentrations of KIM-1 in the cell supernatant of the control group, model group, and low-, medium- and high-dose experimental groups were (8.65±0.53), (17.33±2.04), (10.76±1.41), (8.48±0.47) and (8.47±0.24) pg·mL^-1, respectively; the contents of MCP-1 were (531.38±15.64), (2 198.55±148.21), (1 966.29±53.52), (1 605.49±234.68) and (937.33±36.96) pg·mL^-1, respectively; the secretion levels of IL-1β were (71.66±2.29), (109.92±4.41), (91.68±4.75), (80.66±4.00) and (62.38±3.24) pg·mL^-1, respectively; the contents of caspase-1 were (66.57±10.52), (210.50±17.50), (201.88±7.22), (195.42±13.95) and (129.81±13.20) pg·mL^-1, respectively; the relative expression levels of KIM-1 mRNA in each group were 1.05±0.05, 2.38±0.45, 1.58±0.20, 1.44±0.08 and 1.38±0.22, respectively; while those of MCP-1 were 1.04±0.04, 1.53±0.08, 1.32±0.16, 1.16±0.16 and 0.62±0.13, respectively; the relative expression levels of NLRP3 protein were 0.89±0.08, 1.13±0.07, 1.00±0.07, 0.84±0.12 and 0.55±0.16, respectively; those of ASC were 0.23±0.03, 0.87±0.19, 0.81±0.16, 0.78±0.08 and 0.46±0.05, respectively; those of IL-1β were 0.49±0.12, 1.46±0.29, 1.10±0.26, 0.71±0.06 and 0.53±0.13, respectively; the LC3Ⅱ/Ⅰ ratios were 1.08±0.04, 0.90±0.06, 1.00±0.02 and 1.05±0.04, respectively; the expression levels of p62 protein were 0.38±0.06, 1.23±0.11, 1.05±0.20 and 0.62±0.19, respectively; those of Beclin-1 were 0.82±0.07, 0.59±0.06, 0.90±0.07 and 0.93±0.09, respectively; those of PINK1 were 1.10±0.03, 0.68±0.07, 0.78±0.11 and 1.03±0.08, respectively; those of Parkin were 0.64±0.06, 0.46±0.05, 0.58±0.08 and 0.79±0.12, respectively. Compared with the control group, all the above indicators in the model group exhibited statistically significant differences (P<0.05, P<0.01, P<0.001). Moreover, the indicators in the high-dose experimental group showed statistically significant differences compared with the model group (P<0.05, P<0.01, P<0.001).

Paeonol may alleviate albumin-induced renal tubular injury by promoting mitophagy and inhibiting the activation of the NLRP3 inflammasome.