Curcumin alleviates nuclear factor-κB/NOD-like receptor protein 3 mediated renal injury caused by acute respiratory distress syndrome through reducing mitochondrial oxidative stress / 中华危重病急救医学

OBJECTIVE@#To evaluate the effect of curcumin on renal mitochondrial oxidative stress, nuclear factor-κB/NOD-like receptor protein 3 (NF-κB/NLRP3) inflammatory body signaling pathway and tissue cell injury in rats with acute respiratory distress syndrome (ARDS).@*METHODS@#A total of 24 specific pathogen free (SPF)-grade healthy male Sprague-Dawley (SD) rats were randomly divided into control group, ARDS model group, and low-dose and high-dose curcumin groups, with 6 rats in each group. The ARDS rat model was reproduced by intratracheal administration of lipopolysaccharide (LPS) at 4 mg/kg via aerosol inhalation. The control group was given 2 mL/kg of normal saline. The low-dose and high-dose curcumin groups were administered 100 mg/kg or 200 mg/kg curcumin by gavage 24 hours after model reproduction, once a day. The control group and ARDS model group were given an equivalent amount of normal saline. After 7 days, blood samples were collected from the inferior vena cava, and the levels of neutrophil gelatinase-associated lipocalin (NGAL) in serum were determined by enzyme-linked immunosorbent assay (ELISA). The rats were sacrificed, and kidney tissues were collected. Reactive oxygen species (ROS) levels were determined by ELISA, superoxide dismutase (SOD) activity was detected using the xanthine oxidase method, and malondialdehyde (MDA) levels were determined by colorimetric method. The protein expressions of hypoxia-inducible factor-1α (HIF-1α), caspase-3, NF-κB p65, and Toll-like receptor 4 (TLR4) were detected by Western blotting. The mRNA expressions of HIF-1α, NLRP3, and interleukin-1β (IL-1β) were detected by reverse transcription-polymerase chain reaction (RT-PCR). Renal cell apoptosis was detected by TdT-mediated dUTP nick end labeling (TUNEL). The morphological changes in renal tubular epithelial cells and mitochondria were observed under a transmission electron microscope.@*RESULTS@#Compared with the control group, the ARDS model group exhibited kidney oxidative stress and inflammatory response, significantly elevated serum levels of kidney injury biomarker NGAL, activated NF-κB/NLRP3 inflammasome signaling pathway, increased kidney tissue cell apoptosis rate, and renal tubular epithelial cell damage and mitochondrial integrity destruction under transmission electron microscopy, indicating successful induction of kidney injury. Following curcumin intervention, the injury to renal tubular epithelial cells and mitochondria in the rats was significantly mitigated, along with a noticeable reduction in oxidative stress, inhibition of the NF-κB/NLRP3 inflammasome signaling pathway, and a significant decrease in kidney tissue cell apoptosis rate, demonstrating a certain dose-dependency. Compared with the ARDS model group, the high-dose curcumin group exhibited significantly reduced serum NGAL levels and kidney tissue MDA and ROS levels [NGAL (μg/L): 13.8±1.7 vs. 29.6±2.7, MDA (nmol/g): 115±18 vs. 300±47, ROS (kU/L): 75±19 vs. 260±15, all P < 0.05], significantly down-regulated protein expressions of HIF-1α, caspase-3, NF-κB p65, and TLR4 in the kidney tissue [HIF-1α protein (HIF-1α/β-actin): 0.515±0.064 vs. 0.888±0.055, caspase-3 protein (caspase-3/β-actin): 0.549±0.105 vs. 0.958±0.054, NF-κB p65 protein (NF-κB p65/β-actin): 0.428±0.166 vs. 0.900±0.059, TLR4 protein (TLR4/β-actin): 0.683±0.048 vs. 1.093±0.097, all P < 0.05], and significantly down-regulated mRNA expressions of HIF-1α, NLRP3, and IL-1β [HIF-1α mRNA (2-ΔΔCt): 2.90±0.39 vs. 9.49±1.87, NLRP3 mRNA (2-ΔΔCt): 2.07±0.21 vs. 6.13±1.32, IL-1β mRNA (2-ΔΔCt): 1.43±0.24 vs. 3.95±0.51, all P < 0.05], and significantly decreased kidney tissue cell apoptosis rate [(4.36±0.92)% vs. (27.75±8.31)%, P < 0.05], and significantly increased SOD activity (kU/g: 648±34 vs. 430±47, P < 0.05).@*CONCLUSIONS@#Curcumin can alleviate kidney injury in ARDS rats, and its mechanism may be related to the increasing in SOD activity, reduction of oxidative stress, and inhibition of the activation of the NF-κB/NLRP3 inflammasome signaling pathway.

Effect of curcumin on renal fibrosis induced by acute respiratory distress syndrome in rats / 中华急诊医学杂志

Objective:To investigate the effect of curcumin on renal fibrosis in lipopolysaccharide (LPS) induced acute respiratory distress syndrome (ARDS) in adult SD rats.Methods:Twenty-four male SD rats were randomly (random number) divided into four groups: control group, ARDS group, low dose group, and high dose group ( n=6 per group). In the control group, the rats were given atomization intratracheal of standard saline 2 mL/kg; in the ARDS group, low-dose group, and high-dose group, the rats were given atomization intratracheal of 4 mg/kg LPS; in the low-dose group, the rats were given curcumin 100 mg/d by the oral administration, and in the high-dose group, the rats were given curcumin or 200 mg/d respectively. After seven days, the rats were sacrificed. The superoxide dismutase (SOD) activity and the content of malondialdehyde (MDA) and glutathione (GSH) in renal tissue were detected by colorimetric assay. Nuclear factor kappa-B p65 (NF-κB p65) and transforming growth factor-β1 (TGF-β1) were detected by Western blot. The expression of interleukin-6 (IL-6) mRNA, proline hydroxylase 3 (PHD3) mRNA, vascular endothelial growth factor (VEGF) mRNA and erythropoietin receptor (EPOR) mRNA were detected by quantitative real-time PCR (qRT-PCR). HE staining and Masson staining were used to assess pathological damage. One-way analysis of variance was used for comparison among multiple groups and SNK method was used for comparison between two groups. Results:Compared with the control group, the SOD activity and GSH content in the ARDS group, low-dose group, and high-dose group were significantly decreased (all P<0.05); the protein expression levels of MDA, NF-κB p65, and TGF-β1 were increased significantly, and IL-6 mRNA, PHD3 mRNA, VEGF mRNA, and EPOR mRNA were significantly upregulated (all P<0.05). HE staining showed inflammatory cell infiltration, and fibrogenesis in kidney tissue, and Masson staining showed deposition of collangen-like substance. Compared with the ARDS group, SOD activity and GSH content were increased, while the protein expression of NF-κB p65 and TGF-β1, IL-6 mRNA, PHD3 mRNA, VEGF mRNA, and EPOR mRNA were decreased significantly in the low-dose group and high-dose group (all P<0.05). Curcumin therapy reduced inflammatory cellular infiltration, and the deposition of collagen-like substance in kidney tissue. Compared with the low-dose group, SOD activity and GSH content were increased in the high-dose group (all P<0.05), and the protein expression of NF-κB p65 and TGF-β1, IL-6 mRNA, PHD3 mRNA, VEGF mRNA, and EPOR mRNA were decreased significantly in the high-dose group (all P<0.05). The high-dose group exhibited a significant reduction in edema, and a decrease of the deposition of collagen-like substance in kidney tissue. Conclusions:Curcumin can inhibit the development of renal fibrosis induced by acute respiratory distress syndrome in rats, and its mechanism may be related to inhibiting the expression of inflammatory factors and enhancing hypoxia tolerance.

Effects of prone ventilation on extra pulmonary acute lung injury / 中国中西医结合急救杂志

Objective To investigate the effects and mechanism of prone ventilation in rats with lipopolysaccharide(LPS)-induced extra pulmonary acute lung injury(ALI). Methods Thirty-two male Sprague-Dawley(SD)rats were randomly divided into four groups:control group,ALI group,supine position group(ALIS group)and prone position group(ALIP group). The ALI animal model was reproduced by intra-peritoneal injection of LPS 6 mg/kg,and 2 mL/kg sterile saline was intra-peritoneally injected in control group. After 24 hours,the ALIS group and ALIP group were mechanically ventilated for 4 hours in supine and prone positions respectively. Arterial partial pressure of oxygen(PaO2),carbon dioxide partial pressure(PaCO2),wet to dry weight ratio of lung(W/D) were observed,and the levels of tumor necrosis factor-α(TNF-α),interleukins(IL-6,IL-10)in bronchoalveolar lavage fluid(BALF)were measured. The degrees of histopathological changes of lung were investigated and assessed under light microscope. Results Compared with control group,PaO2 was significantly lower in ALI,ALIS and ALIP groups〔mmHg(1 mmHg=0.133 kPa):68±7,82±8,93±7 vs. 116±7〕,and the PaCO2 in ALI and ALIS groups was obviously higher(mmHg:53±6,51±5 vs. 43±7,both P<0.05);lung W/D ratio as well as levels of TNF-α, IL-6 and IL-10 in BALF were significantly higher in ALI,ALIS and ALIP groups〔lung W/D ratio:5.11±0.32, 4.71±0.38,4.53±0.45 vs. 4.48±0.15,TNF-α(ng/L):548±82,431±64,347±53 vs. 162±16,IL-6(ng/L):772±119,587±178,490±139 vs. 127±16,IL-10(ng/L):211±43,295±36,352±59 vs. 104±31,all P<0.05〕. Compared with ALI group,PaO2 in ALIS and ALIP groups was significantly higher,and in ALIP group,PaCO2 was lower,lung W/D ratio,TNF-α and IL-6 in BALF were obviously lower,while IL-10 in BALF was obviously higher(all P<0.05). Compared with ALIS group,the changes in ALIP group were more significant(all P<0.05). Compared with ALIS group,under light microscope,it was shown that the hyper-inflated areas were less,normal and collapsed areas were greater on the ventral side,and the collapsed area was less and the normal ventilation area was greater on the dorsal side in ALIP group(all P<0.05). Conclusion In rats with LPS-induced extra pulmonary ALI,the prone ventilation can improve gas exchange,promote uniform distribution of ventilation,decrease pulmonary edema and in the mean time attenuate inflammatory response.