Cytoprotective effect of aquaporin 1 against lipopolysaccharide-induced apoptosis and inflammation of renal epithelial HK-2 cells

Sepsis is the most common underlying disease of disseminated intravascular coagulation. Acute kidney injury is a common and serious complications of sepsis. In the present study, a lipopolysaccharide (LPS)-induced human proximal tubule cell line (HK-2 cells) was selected as an in vitro model of septic acute kidney injury. The aim of the present study was to investigate whether aquaporin 1 (AQP-1) has a cytoprotective role in LPS-induced HK-2 cells. HK-2 cells were treated with 0–16 µg/ml LPS for 0–24 h to establish the in vitro model of sepsis. The results demonstrated that AQP-1 levels were the lowest of the eight AQP genes expressed in LPS-induced HK-2 cells. Prior to LPS treatment, HK-2 cells were transfected with pcDNA-AQP-1 or small interfering-AQP-1 and cell counting kint-8 and flow cytometry assays were performed to assess cell viability and apoptosis rate, respectively. Changes in the expression of proinflammatory cytokines and chemokines, as well as important factors in the p38, extracellular signal-regulated kinase (ERK)1/2 and c-Jun N-terminal kinase (JNK) pathways, were assessed using reverse transcription-quantitative polymerase chain reaction, western blotting and ELISA, respectively. LPS treatment reduced viability, increased apoptosis and upregulated the expression of proinflammatory cytokines and chemokines in HK-2 cells. AQP-1 overexpression significantly reversed the effects of LPS and downregulated the expression of tumor necrosis factor-α, interleukin (IL)-8, IL-1β and monocyte chemoattractant protein-1. The p38, ERK1/2 and JNK pathways were activated by LPS; however, the p38 and ERK1/2 pathways were blocked in AQP-1-overexpressing cells. AQP-1 overexpression was demonstrated to confer a survival advantage to LPS-injured HK-2 cells by controlling cell viability, apoptosis and inflammation, possibly via modulation of the p38 and ERK1/2 pathways. The results of the present study suggest that AQP-1 may be an effective treatment for acute kidney injury caused by sepsis.