To study the effects of polygonatum sibiricum polysaccharide (PSP) on the oxidative stress and inflammatory factors expression in caerulein-induced acute pancreatitis (AP) acinar cells and relevant mechanisms.

Rat pancreatic acinar cells (AR42J) were treated with 100 nmol/L caerulein for 6 h to establish a model of acinar cell injury in AP. Caerulein-induced AP cells were incubated with different concentrations (1, 2, 4 mg/mL) of PSP. Malonaldehyde (MDA) content, superoxide dismutase (SOD) and glutathion peroxidase (GPx) activities in the cell, and the levels of intedeukin-6 (IL-6) , tumor necrosis factor α (TNF-α) and IL-1β in the culture medium were evaluated by commercial kits. The expression level of miR-345-5p was measured by real-time quantitative PCR (RT-qPCR) . AR42J cells were transfected with miR-345-5p inhibitors. The effect of down-regulating miR-345-5p on caerulein-induced oxidative stress and inflammatory factor expression in AP cells was examined by the above methods. The miR-345-5p mimics was transfected into AP cells, and the effects of upregulation of miR-345-5p and PSP treatment on oxidative stress and inflammatory cytokine expression was examined by the above methods. For data with homogeneity of variance, t test was used for comparison between two groups, analysis of variance for comparison between multiple groups, and LSD-t test for further pair comparison.

Compared with control, MDA content, the levels of IL-6, TNF-α, IL-1β and miR-345-5p were increased in AP cells, whereas SOD and GPx activities were decreased. The MDA content [ (1.08±0.07) vs (0.88±0.06) , (0.73±0.06) , (0.60±0.05) nmol/mg] in AP cells was significantly reduced after PSP treatment, while the activities of SOD [ (43.01±4.37) vs (59.60±5.62) , (72.37±6.32) , (94.21±8.70) U/mg] and GPx [ (29.03±2.51) vs (44.11±4.71) , (58.07±4.20) , (72.67± 6.56) U/mg] were significantly increased. In addition, the expression levels of IL-6 [ (310.72±22.27) vs (257.01±20.85) , (192.28±17.70) , (146.93±11.90) pg/mL], TNF-α [ (310.72±22.27) vs (257.01±20.85) , (192.28±17.70) , (146.93±11.90) pg/mL]and IL-1β [ (41.66±3.85) vs (33.82±3.20) , (26.15±2.56) , (20.14±1.71) pg/mL] in the culture medium and the expression level of miR-345-5p (2.78±0.24 vs 2.38±0.21, 1.91±0.12, 1.25±0.13) were significantly reduced after PSP treatment in a dose-dependent manner (all P < 0.05) . After down-regulating the expression of miR-345-5p, the MDA content [ (1.13±0.08) vs (0.72±0.06) nmol/mg] in AP cells was significantly reduced, the activities of SOD [ (41.31±3.98) vs (81.73±7.62) U/mg] and GPx [ (28.82±2.97) vs (61.41±5.81) U/mg]were significantly increased, and the levels of IL-6 [ (314.65±25.02) vs (159.76±11.93) pg/mL], TNF-α [ (235.18±23.13) vs (100.41±8.09) pg/mL]and IL-1β[ (48.67±4.50) vs (27.73±2.54) pg/mL] in the culture medium were significantly reduced, with statistically significant differences (all P < 0.05) . Up-regulating miR-345-5p expression reduced the above impacts of PSP on AP cells, with an increase of expressions of MDA content [ (0.58±0.03) vs (0.95±0.08) nmol/mg], decreased SOD [ (96.52±9.54) vs (54.24±4.15) U/mg] and GPx [ (79.62±6.23) vs (39.81±3.84) U/mg] activity, as well as increased expression levels of IL-6 [ (145.38±12.49] vs (275.38±21.55) pg/mL], TNF-α [ (84.83±7.81) vs (183.73±16.39) pg/mL] and IL-1β[ (19.38±1.85) vs (36.97±3.62) pg/mL] in culture medium (P < 0.05) .

PSP can alleviate caerulein-induced acinar cells' inflammatory response and oxidative stress injury in acute pancreatitis in a dose-dependent manner, which is related to the down-regulation of miR-345-5p expression.