Angiotensin 1-7 ameliorates caerulein-induced inflammation in pancreatic acinar cells by downregulating Toll-like receptor 4/nuclear factor-κB expression

Abstract

The present study aimed to investigate the effects of angiotensin (Ang) 1-7 on caerulein (CAE)-stimulated nuclear factor (NF)-kB, Toll-like receptor (TLR4) and cytokine expression using pancreatic acinar AR42J cells. AR42J cells were treated with 10 nmol/l CAE for various durations. In addition, cells were pre treated with various concentrations of Ang 1-7 or A779, a specific antagonist of Ang 1-7, and were stimulated with CAE for 12 h. Control cells were treated with vehicle (F-12K complete medium with 2% fetal bovine serum, 10 U/ml penicillin and 100 mg/ml streptomycin) alone. The mRNA and protein expression levels of TLR4, NF-κB, interleukin (IL)-6, IL-8, IL-10 and tumor necrosis factor-α (TNF-α) were determined by western blotting, immunofluorescence and reverse transcription-quantitative polymerase chain reaction. CAE treatment stimulated TLR4 and NF-κB expression within AR42J cells. Immunofluorescence indicated that TLR4 was expressed on the membranes and in the cytoplasm of AR42J cells, whereas NF-κB expression accumulated in the cytoplasm and nuclei. CAE-induced expression of TLR4 and NF-κB within AR42J cells was abrogated by 10-5 mmol/l Ang 1-7; however, TLR4 and NF-κB expression was enhanced with the addition of A779, particularly 10-5 mmol/l. In addition, treatment with 10-6 and 10-5 mmol/l Ang 1-7 significantly mitigated CAE-induced expression of IL-6, IL-8 and TNF-α, whereas it enhanced IL-10 expression. Conversely, A779 treatment enhanced the CAE-induced expression of IL-6, IL-8 and TNF-α, and reduced IL-10 expression in AR42J cells. In conclusion, these results suggested that Ang 1-7 may attenuate CAE-induced inflammation by downregulating TLR4, NF-κB and proinflammatory cytokine expression within AR42J cells. Therefore, Ang 1-7 may exert protective effects against the pathological progression of AP in a cell model of AP induced by CAE and may be considered in the development of treatments for this disease.