Acute Lung Injury In Septic Rats Research Articles

Probiotics improves sepsis-induced acute lung injury in association with intestinal microbiota and pulmonary concentrations of Th17 and Treg

This study aims to assess the immune status of septic acute lung injury (ALI) at various stages and to investigate whether probiotics can mitigate ALI in septic rats. Rats were randomly assigned to sham, caecal ligation and puncture (CLP), and probiotic treatment after CLP (CLP+PT) group. Intestinal contents, bronchoalveolar lavage fluid (BALF), and lung tissue were collected from rats at 6, 24 and 48 h after CLP. Results showed that Th17 level at 24 h in BALF is significantly higher than that at 6 and 48 h. The Treg level increased after CLP and reached its highest point at 48 h. Pathological damage in the alveolar interstitium intensified over time. At 24 h, Th17 percentage of BALF significantly increased in the CLP group while it significantly decreased in the CLP+PT group, and the Treg percentage of BALF at 48 h showed the same alteration trend. Alveolar interstitial pathological damage in the CLP+PT group was reduced at all time points compared to the CLP group. The abundance of Firmicutes was higher and Bacteroidetes lower in the sepsis group compared to the sham group. However, the abundance of these bacteria was similar between the probiotic and pseudo-probiotic groups. Actinomycetes levels differed significantly among the three groups, with the probiotic group exhibiting significantly higher levels. Bifidobacteria levels were significantly higher in the probiotic group compared to the sepsis group. Phenotype prediction indicated a higher proportion of biofilm formation in the probiotic group compared to the sepsis group. In conclusions, significant alterations in Th17 and Treg levels in BALF of septic rats suggest a shift in the distribution of important T lymphocytes in the lungs during sepsis. Probiotics modulated the gut microbiota of septic rats, downregulated the highest value of Th17 and Treg percentage in BAFL, resulting in mitigated lung injury in rats.

Heparin-Binding Protein Aggravates Acute Lung Injury in Septic Rats by Promoting Macrophage M1 Polarization and NF-κB Signaling Pathway Activation.

Objective Heparin-binding protein (HBP) plays an important role in sepsis and is a prognostic biomarker in patients with sepsis, but the role of HBP in the pathogenesis of sepsis-associated acute lung injury (ALI) remains unclear. This study aimed to investigate the role of HBP in sepsis-induced ALI and its underlying molecular mechanisms. Methods The cecal ligation and puncture (CLP) model was used to induce ALI in mice and randomly divided into 4 groups: control group, CLP (rats treated with cecal ligation and puncture), HBP (rats treated with CLP and HBP injection), and HBP + UFH (rats treated with CLP and injection of HBP and unfractionated heparin). Subsequently, HBP expression in rat serum and lung tissues was detected by qRT-PCR, edema and pathological changes in lung tissue by lung wet-to-dry weight ratio (W/D) and HE staining, myeloperoxidase (MPO) and superoxide dismutase (SOD) activities in lung tissues by detection kits. Additionally, ELISA and western blot were applied for the determination of IL-6, TNF-α, and IL-1β expression in rat bronchoalveolar lavage fluid, and iNOS, Arg-1, Mrc1, NF-κBp65, IKKα, IκBα, and p-IκBα expression in lung tissues. Results The expression levels of HBP in serum and lung tissues of rats in the HBP group were significantly increased, the lung tissues were severely injured, accompanied by a significant increase in MPO activity but a significant decrease in SOD activity, and the levels of IL-6, TNF-α, and IL-1β in bronchoalveolar lavage fluid were significantly increased. In addition, the expression levels of iNOS, NF-κB p65, IKKα, and p-IκBα in the lung tissues of rats in the HBP group were significantly increased, while the addition of unfractionated heparin reversed the above results. Conclusion HBP aggravates ALI in septic rats, and its mechanism may be related to the promotion of macrophage M1 polarization and activation of the NF-κB signaling pathway.

Protective effect of N-acetylcysteine on acute lung injury in septic rats by inhibiting inflammation, oxidation, and apoptosis.

Objective(s):Acute lung injury (ALI) is a common comorbidity in patients with sepsis, and finding drugs that can effectively reduce its mortality is a hot spot in current research. The purpose of this study is to explore the protective mechanism of N-acetylcysteine (NAC) on ALI in septic rats.Materials and Methods:We used NAC to intervene in septic rats to evaluate the plasma inflammatory factors and lung tissue pathological damage. Biochemical methods were used to determine the levels of oxidases in lung tissue, the expression of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) proteins, and observed lung tissue cell apoptosis.Results:NAC pretreatment decreased the mortality of septic rats, improved lung tissue pathological damage, reduced the levels of tumor necrosis factor-α, interleukin-1β, interleukin-6, interleukin-8, and malondialdehyde, and increased activity of superoxide dismutase, glutathione peroxidase, and catalase. Moreover, NAC pretreatment significantly decreased iNOS protein expression and increased eNOS protein expression in lung tissue. Meanwhile, NAC significantly decreased the number of apoptosis and the levels of Bax and Caspase-3 mRNA and increased the level of Bcl-2 mRNA in the lung tissue of septic rats. Conclusion:NAC protects ALI in septic rats by inhibiting inflammation, oxidative stress, and apoptosis.

Protective effect of forsythiaside A on acute lung injury in septic rats

To observe the protective effect of forsythiaside A on acute lung injury (ALI) in septic rats. Male Sprague-Dawley (SD) rats were randomly divided into normal control group, sham operation group, sepsis model group, and forsythiaside A intervention group, with 10 rats in each group. The rats in the normal control group did not receive any intervention; the rats in the sham operation group only underwent abdominal surgery; and those in the model group and forsythiaside A intervention group received cecal ligation and puncture (CLP) to establish the sepsis rat model. The rats in the forsythiaside A intervention group were given 75 mL/kg of forsythiaside A within 0.5 hour after operation, and repeated after 6 hours. The rats in the sham operation group and model group were given the same amount of normal saline at the same time points. The lung tissues were collected for pathological examination 12 hours after operation. The lung homogenate was prepared, and enzyme-linked immunosorbent assay (ELISA) was used to detect tumor necrosis factor-α (TNF-α), interleukins (IL-1β, IL-6). The activity of superoxide dismutase (SOD) was detected by xanthine oxidase method, and the content of malonaldehyde (MDA) was detected by colorimetry. The expression of nuclear factor-κB p65 (NF-κB p65) was detected by Western blotting. There was no significant pathological change of lung tissue in both normal control group and sham operation group, and there was no significant difference in each parameter between the two groups. The rats in the model group had interstitial infiltration of inflammatory cells, alveolar structure destruction, alveolar septum thicken, extensive alveolar hemorrhage, telangiectasia; the levels of TNF-α, IL-1β, IL-6, MDA and NF-κB p65 protein expression in lung tissue were significantly higher than those in the normal control group and sham operation group [TNF-α (ng/L): 132.81±16.15 vs. 45.08±5.98, 46.10±6.72, IL-1β (ng/L): 137.32±15.22 vs. 51.03±7.89, 50.92±8.13; IL-6 (ng/L): 138.39±14.28 vs. 51.68±7.03, 52.48±7.36; MDA (kU/g): 1.79±0.13 vs. 0.96±0.05, 0.97±0.05; NF-κB p65 protein (NF-κB p65/GAPDH): 2.82±0.23 vs. 1.76±0.12, 1.82±0.13; all P < 0.05], the activity of SOD decreased significantly (kU/g: 45.90±5.46 vs. 92.11±10.13, 93.36±10.56, both P < 0.05). The changes in lung histopathology in the forsythiaside A intervention group were obviously improved as compared with the model group, which showed less inflammatory cell infiltration, less alveolar septum thickening, less bleeding and more intact structures; the levels of TNF-α, IL-1β, IL-6, MDA and the expression of NF-κB p65 protein in lung tissue were significantly lower than those in the model group [TNF-α (ng/L): 72.48±9.78 vs. 132.81±16.15, IL-1β (ng/L): 83.85±12.46 vs. 137.32±15.22, IL-6 (ng/L): 81.88±11.89 vs. 138.39±14.28, MDA (kU/L): 1.29±0.09 vs. 1.79±0.13, NF-κB p65 protein (NF-κB p65/GAPDH): 2.29±0.19 vs. 2.82±0.23, all P < 0.05], SOD activity increased significantly (kU/g: 66.03±7.98 vs. 45.90±5.46, P < 0.05). Forsythiaside A can effectively alleviate ALI in septic rats. The mechanism may be related to down-regulate the expression of NF-κB p65 and reduce the level of inflammatory factors and free radicals in lung tissue, thereby against acute lung injury in septic rats.

Hydrogen-rich saline regulates the polarization and apoptosis of alveolar macrophages and attenuates lung injury via suppression of autophagy in septic rats.

BackgroundHydrogen-rich saline (HRS) has a protective effect on sepsis-induced lung injury. However, the underlying mechanisms are still unclear. Polarization and apoptosis of macrophages are essential factors in the pathogenesis of acute lung injury (ALI). Moreover, autophagy is involved in the regulation of both macrophage polarization and apoptosis. Therefore, this study investigated the ability of HRS to attenuate ALI through regulation of the polarization and apoptosis of alveolar macrophages (AMs) during sepsis by modulating autophagy.MethodsMale Sprague-Dawley (SD) rats were used to prepare the sepsis-induced lung injury animal model. Rat lung tissue was harvested after lipopolysaccharide (LPS) treatment, in the presence or absence of HRS, and the AMs were analyzed for changes in polarization, apoptosis, and autophagy. The rat AM cell line NR8383 was used to examine these processes in vitro using Western blot analysis, flow cytometry, and transmission electron microscopy.ResultsLPS-induced ALI in rats was associated with an increase in autophagy, apoptosis, and M1 polarization but a decrease in M2 polarization in AMs. These effects were reversed by administration of HRS. Inhibition of AM autophagy with 3-methyladenine (3-MA) decreased apoptosis and M1 polarization and increased M2 polarization, paralleling the effects of HRS.ConclusionsHRS could attenuate ALI in septic rats through regulation of AM polarization and a reduction in apoptosis by suppressing autophagy. This may represent a potential novel therapeutic target for the treatment of ALI caused by sepsis.

Protective effect of S-nitrosoglutathione pretreatment on acute lung injury in septic rats.

Objective(s):To investigate the protective effect of S-nitrosoglutathione (SNG) pretreatment on acute lung injury (ALI) in septic rats. Materials and Methods:We constructed a rat model of sepsis by cecal ligation and perforation (CLP), and randomly divided into Sham, CLP, and CLP+SNG (0.25 and 0.5 mg/kg) groups. We used H&E staining and lung wet/dry ratio to assess the severity of lung injury, detected the levels of protein and cells in bronchoalveolar lavage fluid (BALF) and the levels of TNF-α, IL-1β, TLR4 mRNA, and NF-κB p65 mRNA in the lung tissue, and assessed the levels of glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase in the lung tissue.Results:A rat model of sepsis was successfully constructed by CLP, and pretreatment of SNG significantly increased the survival of septic rats (P<0.001) and decreased the lung tissue injury scores (P<0.001) and lung wet/dry ratio (P<0.01) in a dose-dependent manner. Furtherly, SNG pretreatment significantly reduced the number of total cells, total protein, neutrophils, and lympholytes (all P<0.001) in BALF, and which also decreased the levels of TNF-α, IL-1β, TLR4 mRNA, and NF-κB p65 mRNA (all P<0.001) in the lungs of CLP-induced rats. Moreover, pretreatment of SNG significantly increased the levels of anti-oxidant enzymes GSH, SOD, GSH-Px, and catalase (all P<0.001) in the lung tissue of septic rats. Conclusion:SNG pretreatment has a protective effect on ALI in septic rats, and the specific mechanism may be related to anti-endotoxic, anti-inflammatory, and anti-oxidative properties.

Adipose-derived mesenchymal stem cells ameliorate the inflammatory reaction in CLP-induced septic acute lung injury rats via sTNFR1.

We hypothesized that the adipose-derived mesenchymal stem cells (ADMSCs), which secrete high amounts of soluble molecules, such as soluble tumor necrosis factor receptor 1 (sTNFR1), may ameliorate sepsis-induced acute lung injury (ALI). A total of 120 male adult Sprague-Dawley rats were separated into four groups: the sham control (SC), sepsis induced by cecal ligation and puncture (CLP), CLP-ADMSCs, and CLP-sTNFR1 small interfering RNA (siRNA) groups; CLP groups underwent CLP and then received 1 × 106 ADMSCs with or without knockdown of sTNFR1 intravenously at 1 hr after surgery. Rats were killed at 3, 6, 24, and 48 hr after the SC or CLP procedures. 5-Ethynyl-2'-deoxyuridine-labeled ADMSCs extensively colonized the lungs at 6, 24, and 72 hr after injection. The lung wet/dry (W/D) weight ratios in the CLP group were higher than those in SC group; however, ADMSCs ameliorated the W/D weight ratios following CLP, and this effect was abolished by sTNFR1 siRNA treatment. The levels of serum sTNFR1 and interleukin-10 (IL-10) were higher in the CLP-ADMSCs group and lower in the SC group than in other groups; interestingly, these levels were higher in CLP and CLP-sTNFR1 siRNA groups than in SC group. Tumor necrosis factor-α and IL-6 levels increased significantly after CLP, and ADMSCs could alleviate these changes, but the effect was weakened by sTNFR1 siRNA treatment. The lung cell apoptosis and edema levels were consistent with IL-6 levels among all groups. Therapeutically administered ADMSCs secrete sTNFR1, which most likely protects against ALI in septic rats by ameliorating inflammation and lung edema.

Role of the Rho/ROCK signaling pathway in the protective effects of fasudil against acute lung injury in septic rats.

Fasudil, which is primarily prescribed to treat cerebral vasospasm, may also inhibit systemic inflammation and prevent sepsis-induced acute lung injury (ALI) in rats, although the mechanisms remain elusive. The purpose of the present study was to investigate the role of the rhodopsin (Rho)/Rho-associated protein kinase (ROCK) signaling pathway in the protective effects of fasudil on ALI in septic rats. A total of 60 Wistar rats were pretreated with fasudil (30 mg/kg) through intraperitoneal injections 1 h prior to cecal ligation and puncture. Administration of fasudil led to reductions in polymorphonuclear neutrophil counts, and the protein concentrations of tumor necrosis factor-α, interleukin (IL)-1β and IL-6 in the bronchoalveolar lavage fluid of rats with sepsis-induced ALI. The results demonstrated that fasudil decreased sepsis-induced bacteremia. In addition, fasudil effectively reduced the Evans blue content, wet/dry lung weight ratio, lung injury score, and expression levels of malondialdehyde and myeloperoxidase. However, the superoxide dismutase activity in the lung tissue of the rats was increased. Activated caspase-3 activity in lung tissue was reduced to 29% by fasudil. Furthermore, the expression of Rho and ROCK1 was significantly downregulated, and the phosphorylation of myosin phosphatase-targeting subunit 1 in lung tissues was markedly decreased, whereas the protein expression levels of zonula occludens 1 were increased in fasudil-treated rats (P<0.05). In the in vitro experiments, vascular endothelial growth factor, intracellular adhesion molecule 1 and vascular cell adhesion molecule 1 secreted from human pulmonary microvascular endothelial cells treated with lipopolysaccharide (LPS) were attenuated by fasudil. Fasudil also reduced the fluorescence intensity of filamentous actin induced by LPS. Taken together, the results of the present study demonstrated that fasudil was able to improve endothelial permeability and inhibit inflammation, oxidative stress and cellular apoptosis in order to alleviate ALI in septic rats through inhibition of the Rho/ROCK signaling pathway.

Alleviation of Acute Lung Injury in Rats with Sepsis by Resveratrol via the Phosphatidylinositol 3-Kinase/Nuclear Factor-Erythroid 2 Related Factor 2/Heme Oxygenase-1 (PI3K/Nrf2/HO-1) Pathway.

BackgroundResveratrol (Res) is a type of polyphenol found in many plants, which can protect important organs from the damage induced by sepsis. However, the exact mechanism of its protective effect has not been established. This study investigated the effect of Res on the PI3K/Nrf2/HO-1 signaling pathway in rats with sepsis-induced acute lung injury (ALI).Material/MethodsMale Wistar rats were treated with 30 mg/kg Res by intraperitoneal administration for 1 hour immediately after cecal ligation and puncture. Levels of MIP-2, IL-18, and IL-10 in bronchoalveolar lavage fluid (BALF) were determined. Lung tissues were collected to measure the wet-to-dry (W/D) ratios, oxidative stress index, and lung injury scores. Expression levels of Akt, p-Akt, HO-1, Nrf-2, and active caspase-3 proteins were determined by western blotting; expression of HO-1 mRNA was determined by RT-PCR.ResultsTreatment with Res significantly decreased the levels of MIP-2 and IL-18 and increased IL-10 in the BALF of rats with sepsis-induced ALI. In addition, Res also effectively reduced the W/D lung weight ratio, lung injury score, and the levels of MDA (malondialdehyde) and 8-OHdG. Conversely, Res increased SOD (superoxide dismutase) activity in the lung tissue. Moreover, Res significantly induced higher HO-1 mRNA expression, upregulated HO-1 and Nrf-2 protein expression, and the phosphorylation of Akt in the lung tissue. In contrast, the levels of activated caspase-3 protein were decreased in Res-treated rats (P<0.05).ConclusionsRes could inhibit inflammation, oxidative stress, and cell apoptosis to alleviate ALI in septic rats through the inhibition of the PI3K/Nrf2/HO-1 signaling pathway.

Salvianolic acid B protects against acute lung injury by decreasing TRPM6 and TRPM7 expressions in a rat model of sepsis.

This study aimed to investigate the protective effects of salvianolic acid B (SA-B) on acute lung injury (ALI) through decreasing the expressions of channel kinase's TRPM6 and TRPM7. Wistar Septic rat models were established by lipopolysaccharide (LPS), which were separated into the control, lipopolysaccharide (LPS), SA-B, SA-B + si-TRPM6, SA-B + si-TRPM7, si-TRPM6, and si-TRPM7 groups. Arterial blood gas, protein content, total white blood cell (WBC) count and the percentage of polymorphonuclear neutrophils (PMN%) were measured. Levels of TNF-α and IL-6 levels in bronchoalveolar lavage fluid (BALF) were monitored. Lung coefficient, myeloperoxidase (MPO) and superoxide dismutase (SOD) activity were conducted by MPO and SOD kit. The mRNA expressions of TRPM6 and TRPM7 were detected by qRT-PCR. Compared with the control group, the PaO2 and PaO2 /FiO2 values exhibited decreases in other group, while the PaCO2 value, protein content, total WBC, PMN%, TNF-α, IL-6 levels and lung coefficient values all increased. MPO activity in lung tissue increased, while SOD activity decreased. TRPM6 and TRPM7 expressions increased significantly. Compared with the LPS group, the SA-B, SA-B + si-TRPM6, SA-B + si-TRPM7, si-TRPM6, and si-TRPM7 groups had increased PaO2 and the PaO2 /FiO2 , while decreased PaCO2, protein content, total WBC, PMN%, TNF-α, IL-6 levels, and lung coefficient. MPO activity in lung tissue decreased while SOD activity increased. Decreased mRNA expressions of TRPM6 and TRPM7 in the SA-B, SA-B + si-TRPM6, and SA-B + si-TRPM6 groups were observed. Through decreasing the expressions of the channel kinase TRPM6 and TRPM7, SA-B protects against ALI in septic rats.

Amentoflavone prevents sepsis-associated acute lung injury through Nrf2-GCLc-mediated upregulation of glutathione.

Sepsis is a serious medical problem and is one of the main causes of high mortality in intensive care units. Fifty percent of patients with severe sepsis will develop acute lung injury (ALI). Amentoflavone (AMF) is a polyphenolic compound possessing potent anti-inflammatory activities. The study aimed to explore the protective effects of AMF against ALI in cecal ligation and puncture (CLP)-induced septic rats. The results showed that AMF administration protected against septic ALI, as reflected by marked amelioration of histological injury of lung tissues and decrease of pulmonary edema in CLP-treated rats. AMF ameliorated CLP-induced increase of systemic and lung TNFα and IL-1β and binding activity of p65 NF-κB, indicating the inhibition of inflammation. Moreover, AMF prevented CLP-induced oxidative stress, as evidenced by increase of oxygen consumption rate, decrease of TBARS content, increase of SOD activity and GSH level in lung tissue of CLP-treated rats. CLP resulted in significant decrease of mRNA expression of Nrf2 and GCLc, which was inhibited by AMF. AMF-induced protective effects on ALI, inflammation, and oxidative stress were inhibited by lentivirus shRNA-mediated silence of Nrf2 and buthionine sulphoximine (BSO), an inhibitor of GSH synthesis. AMF increased Nrf2-binding activity in GCLc promoters in lung tissue of CLP-treated rats. The results suggested that AMF protected against ALI in septic rats through upregulation of Nrf2-GCLc signaling, enhancement of GSH antioxidant defense, reduction of oxidative stress and final amelioration of inflammation and histological injury of lung. The data provide new therapeutic options for the treatment of sepsis-associated ALI.