Saponin from Panax japonicus IVa alleviates lipopolysaccharide-induced acute lung injury in rats via its anti-inflammatory and antioxidative ef-fects / 中国病理生理杂志

ABSTRACT

AIM:To investigate the effects of saponin from Panax japonicus IVa(SPJ IVa)on acute lung inju-ry in rats and to explore its possible protective mechanism.METHODS:Sixty SD rats were randomly divided into four groups,15 rats in each groupthe control group,model group,low-dose SPJ IVa group,and high-dose SPJ IVa group.A rat model of ALI was established via intratracheal instillation of lipopolysaccharide(LPS,2 mg/kg).Rats in the low-and high-dose SPJ IVa groups were intraperitoneally injected with 15 and 45 mg/kg SPJ IVa,respectively,30 min after model-ing.Serum,bronchoalveolar lavage fluid(BALF),and lungs were collected 24 h after modeling.Pathomorphological changes in lung tissues were assessed using HE staining.The wet weight/dry weight ratio of lung tissues was measured us-ing the weighing method,whereas ELISA was used to measure the levels of interleukin-1β(IL-1β),IL-6,and tumor ne-crosis factor-α(TNF-α)in the serum and BALF.The levels of malondialdehyde(MDA),superoxide dismutase(SOD),and glutathione(GSH)were assessed using the kit method.Cell apoptosis in lung tissues was evaluated by immunohisto-chemical staining of cleaved caspase-3 and TUNEL.Western blot was used to measure the expression of nuclear factor E2-related factor 2(Nrf2),heme oxygenase-1(HO-1),nuclear factor-κB(NF-κB)p65,and Toll-like receptor 4(TLR4)in lung tissues.RESULTS:Compared with control group,the lung tissues of the model group were significantly damaged,and the lung injury scores(0.21±0.22 vs 2.98±0.46)and lung wet/dry weight ratios(3.09±0.41 vs 6.36±0.61)were significantly increased(P<0.01).Compared with model group,the lung injury scores(1.80±0.31 and 1.05±0.25 vs 2.98±0.46)and lung wet/dry weight ratios(5.25±0.44 and 3.89±0.35 vs 6.36±0.61)in low-and high-dose SPJ IVa groups were significantly reduced(P<0.01).The administration of LPS resulted in elevated levels of pro-inflammatory cy-tokines(IL-1β,IL-6,and TNF-α)as well as the oxidative marker MDA in both serum and BALF(P<0.01).Additional-ly,it led to a decrease in antioxidant markers SOD and GSH(P<0.01).However,treatment with both low and high doses of SPJ IVa effectively attenuated the LPS-induced production of pro-inflammatory factors and oxidative markers MDA(P<0.01),while also increasing SOD and GSH levels(P<0.05 or P<0.01).In the model group,evident apoptosis was ob-served in lung tissues,whereas treatment with low and high doses of SPJ IVa significantly suppressed TUNEL-positive cells and the expression of cleaved caspase-3(P<0.01).The expression levels of Nrf2,HO-1,NF-κB p65,and TLR4 in lung tissues were significantly higher in the model group than in the control group(P<0.01);in turn,after treatment with low and high doses of SPJ IVa,Nrf2 and HO-1 were further upregulated(P<0.01),whereas NF-κB p65 and TLR4 were downregulated(P<0.01).CONCLUSION:The inhibitory effect of SPJ IVa on LPS-induced ALI in rats may be attribut-ed to its ability to suppress the TLR4/NF-κB-and Nrf2/HO-1-mediated inflammatory response and oxidative stress.