LPS-induced Acute Lung Injury In Rats Research Articles

The total alkaloids of Aconitum tanguticum protect against lipopolysaccharide-induced acute lung injury in rats

Ethnopharmacological relevanceAconitum tanguticum has been widely used as a remedy for infectious diseases in traditional Tibetan medicine in China. The total alkaloids of Aconitum tanguticum (TAA) are the main active components of Aconitum tanguticum and have been demonstrated to be effective in suppressing inflammation. Our aim was to investigate the protective effects of TAA on acute lung injury (ALI) induced by lipopolysaccharide (LPS) in rats. Materials and methodsTAA was extracted in 95% ethanol and purified in chloroform. After vacuum drying, the TAA powder was dissolved in dimethyl sulfoxide. Adult male Sprague-Dawley rats were randomly divided into six groups. Rats were given dexamethasone (DXM, 4 mg/kg) or TAA (60 mg/kg, 30 mg/kg) before LPS injection. The PaO2and PaO2/FiO2 values, lung wet/dry (W/D) weight ratio and histological changes in lung tissue were measured. The cell counts, protein concentration, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) in bronchoalveolar lavage fluid (BALF), and myeloperoxidase (MPO) activity in lung tissue were determined at 6, 12 or 24 h after LPS treatment. In addition, the NF-κ B activation in lung tissue was analyzed by western blot. ResultsIn ALI rats, TAA significantly reduced the lung W/D ratio and increased the value of PaO2 or PaO2/FiO2 at 6, 12 or 24 h after LPS challenge. TAA also reduced the total protein concentration and the number of total cells, neutrophils or lymphocytes in BALF. In addition, TAA decreased MPO activity in the lung and attenuated histological changes in the lung. Furthermore, TAA inhibited the concentration of TNF-α, IL-6 and IL-1β in BALF at 6, 12 or 24 h after LPS treatment. Further study demonstrated that TAA significantly inhibited NF-κ B activation in lung tissue. ConclusionsThe current study proved that TAA exhibited a potent protective effect on LPS-induced ALI in rats through its anti-inflammatory activity.

Arctigenin attenuates lipopolysaccharide-induced acute lung injury in rats.

Arctigenin (ATG) has been reported to possess anti-inflammatory properties. However, the effects of ATG on lipopolysaccharide (LPS)-induced acute lung injury (ALI) remains not well understood. In the present study, our investigation was designed to reveal the effect of ATG on LPS-induced ALI in rats. We found that ATG pretreatment attenuated the LPS-induced ALI, as evidenced by the reduced histological scores, myeloperoxidase activity, and wet-to-dry weight ratio in the lung tissues. This was accompanied by the decreased levels of tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-1 (IL-6) in the bronchoalveolar lavage fluid. Furthermore, ATG downregulated the expression of nuclear factor kappa B (NF-κB) p65, promoted the phosphorylation of inhibitor of nuclear factor-κB-α (IκBα) and activated the adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPKα) in the lung tissues. Our results suggested that ATG attenuates the LPS-induced ALI via activation of AMPK and suppression of NF-κB signaling pathway.

Tetrahydrocoptisine protects rats from LPS-induced acute lung injury.

Recent studies show that nuclear factor-kappa B (NF-κB) signaling pathway plays a key role in contributing to the development of lipopolysaccharide (LPS)-induced acute lung injury (ALI). Tetrahydrocoptisine is one of the main active components of Chelidonium majus L. and has been described to be effective in suppressing inflammation. The aim of the present study is to evaluate the protective effect of tetrahydrocoptisine on LPS-induced ALI in rats and clarify its underlying mechanisms of action. We found that in vivo pretreatment with tetrahydrocoptisine to rats 30min before inducing ALI by LPS markedly decreased the mortality rate, lung wet weight to dry weight ratio, and ameliorated lung pathological changes. Meanwhile, tetrahydrocoptisine significantly inhibited the increase of the amounts of inflammatory cells, total protein content, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) secretion in the bronchoalveolar lavage fluids (BALFs). Furthermore, tetrahydrocoptisine inhibited myeloperoxidase (MPO) accumulation in lung tissue and alleviated TNF-α and IL-6 production in serum. Additionally, immunohistochemistry showed that tetrahydrocoptisine efficiently reduced nuclear factor-kappa B (NF-κB) activation by inhibiting the translocation of NF-κBp65. In conclusion, our results demonstrate that tetrahydrocoptisine possesses a protective effect on LPS-induced ALI through inhibiting of NF-κB signaling pathways, which may involve the inhibition of pulmonary inflammatory process.

Baicalein, an active component of Scutellaria baicalensis, protects against lipopolysaccharide-induced acute lung injury in rats

Ethnopharmacological relevanceBaicalein (BE), a phenolic flavonoid extracted mainly from the root of Scutellaria baicalensis Georgi, a Chinese herb, is traditionally used in oriental medicine. Several studies have demonstrated that BE exerts many beneficial effects including anti-inflammatory and antioxidant activities. However, its effect on acute lung injury (ALI) and the molecular mechanisms involved remain unclear and warrant further investigation. The aim of the study is to investigate whether BE improves lipopolysaccharide (LPS, intratracheally, i.t.)-induced ALI in rats, and further study the underlying mechanisms of its activity. Material and methodsRats were administrated with LPS (5mg/kg/body weight, i.t.) through a 24-gauge catheter to establish the ALI model. The effects of BE on the levels of pro-inflammatory cytokines, nitrite/nitrate in bronchoalveolar lavage fluid, and the expression of nuclear factor-erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and nuclear factor-kappa B (NF-κB) activation as well as the histopathological changes were evaluated. ResultsResults showed that BE (20mg/kg, i.p.) treatment markedly attenuated LPS-induced lung edema, elevation of the levels of IL-1β, TNF-α, IL-6, CINC-3, and nitrite/nitrate in bronchoalveolar lavage fluid accompanied by a remarkable improvement of lung histopathological symptoms. The LPS-enhanced inflammatory cell infiltration and myeloperoxidase activity, O2− formation and the expression of inducible nitric oxide synthase and nitrotyrosin in lungs were all attenuated by BE. Notably, BE could augment Nrf2/HO-1 cascade, but inhibited NF-κB activation in LPS-instilled lungs that was strongly reversed by blocking HO-1 activity. ConclusionThis study is the first to demonstrate that BE protects against LPS-induced ALI in rats. The underlying mechanisms may include inhibition of NF-κB-mediated inflammatory responses and upregulation of Nrf2/HO-1 pathway, which ultimately alleviates the pathological symptoms of ALI.

Protection of Total Flavonoid Fraction from Nervilia fordii on Lipopolysaccharide-induced Acute Lung Injury in Rats

ObjectiveTo investigate the effects of total flavonoid fraction (TFF) from Nervilia fordii on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats, and to explore their protective mechanism. MethodsLPS-induced ALI model was established by LPS (5 mg/kg) injection via left cervical vein. Blood samples were collected from the cervical artery of all rats at 5 and 6 h after LPS challenge for arterial blood gas test and cytokines measurements, and pulmonary microvascular permeability (PMP), lung wet/dry weight ratio (W/D), and pathological features were observed. ResultsPhytochemical study showed that the TFF contained 67.3% of flavonoids expressed in rutin and three flavone glycosides. The TFF pretreatment (6.24 and 12.48 mg/kg) attenuated the partial arterial pressure of oxygen decline in blood significantly, and decreased the PMP and lung W/D in ALI rats. In addition, the TFF (6.24 and 12.48 mg/kg) also ameliorated the LPS-induced lung damages including alveolar edema, neutrophils infiltration, alveolar hemorrhage, and thickening of the alveolar wall. Furthermore, the treatment with the TFF (6.24 and 12.48 mg/kg) also down-regulated the levels of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and intercellular adhesion molecule-1 (ICAM-1), and up-regulated the level of anti-inflammatory cytokine IL-10 in serum of ALI rats simultaneously. ConclusionThese results suggest that the TFF could protect LPS-induced ALI in rats, which may be mediated, at least in part, by adjusting the production of inflammatory cytokines including TNF-α, IL-6, ICAM-1, and IL-10.

The harmful effect of prolonged high-dose methylprednisolone in acute lung injury

Although many literatures have shown that prolonged high-dose administration of corticosteroids is hazardous and not indicated to therapy acute lung injury (ALI), there is little information on the harmful effect of prolonged high-dose corticosteroids in acute lung injury. In this study, we aimed to investigate the effect of prolonged high-dose methylprednisolone (MPL) on ALI and improve knowledge regarding the appropriate use of corticosteroids in ALI. The different doses of MPL (3, 30, 180mg·kg−1) were given via tail vein injection 1h after the first time LPS administration and were daily administrated for 14days. Lung tissues and lavage samples were isolated for biochemical determinations and histological measurements at 12h, 7days and 14days after LPS administration. Single administration of 180mg·kg−1 MPL decreased the lung injury score, wet-to-dry ratio, the total cell numbers and level of procollagen type III in BALF at 12h after LPS challenge. However, prolonged therapy with 180mg·kg −1 MPL for 7days and 14days decreased the number of AMs in BALF and increased the above-mentioned indexes. These results suggested that the prolonged high-dose MPL has harmful effects to treat LPS-induced ALI in rats.

Effect of c-AMP-protein kinase A on up-regulation of heme oxygenase-1 expresion during lipopolysac-charide-induced acute lung injury in rats

Objective To evaluate the role of c-AMP-protein kinase A (cAMP-PKA) on the up-regulation of heme oxygenase-1 (HO-1) expression during lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats.Methods Forty-eight healthy male Sprague-Dawley rats,weighing 180-220 g,aged 2.5-3.0 months,were randomly divided into 4 groups (n =12 each)∶ normal control group (group C),ALI group (group ALI),H89 +ALI group (group H + ALI) and H89 group (group H).In group C,normal saline (solvent for LPS) 0.5 ml was injected via the femoral vein and normal saline (solvent for H89) 0.5 ml was injected subcutaneously 2 h later.In group ALI,10 mg/kg LPS 0.5 ml was injected via the femoral vein and normal saline 0.5 ml was injected subcutaneously 2 h later.In group H +ALI,10 mg/kg LPS 0.5 ml was injected via the femoral vein and 5 mg/kg H89 0.5ml was injected subcutaneously 2 h later.In group H,normal saline 0.5 ml was injected via the femoral vein and 5 mg/kg H89 0.5 ml was injected subcutaneously 2 h later.The rats were then sacrificed at 6 h after iv injection of LPS and the lungs were removed for microscopic examination and lung water content.The pathological changes of the lung were scored.The expression of HO-1 and PKA (by Western blot) and HO-1 mRNA (by RT-PCR) was detected.Results Compared with group C,the pathological score and lung water content were significantly increased,and the expression of HO-1,PKA and HO-1 mRNA was up-regulated in groups ALI and H +ALI (P ＜0.05),and no significant change was found in the parameters mentioned above in group H (P ＞ 0.05).The pathological score and lung water content were significantly higher,and the expression of HO-1,AP-1 and HO-1 mRNA was significantly lower in group H + ALI than in group ALI (P ＜ 0.05).Conclusion Activation of signaling pathway c-AMP-PKA is involved in the up-regulation of HO-1 expression during LPS-induced ALI in rats. Key words: Cyclic AMP-dependent protein kinases ; Heme oxygenase-1 ; Endotoxemia ; Respiratory distress syndrome, adult

Role of activator protein-1 in up-regulation of heme oxygenase-1 expression during lipopolysaccharide-induced acute lung injury in rats

Objective To evaluate the role of activator protein-1 (AP-1) in the up-regulation of heme oxygenase-1 (HO-1) expression during lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats.Methods Forty-eight healthy male Sprague-Dawley rats,weighing 200-220 g,aged 2.5-3.0 months,were randomly divided into 4 groups (n=12 each): normal control group (group C),ALI group,curcumin + ALI group (group Cur+ ALI),and curcumin group (group Cur).In groups C and ALI,normal saline 0.5 ml and LPS 10 mg/kg (0.5 ml) were injected intravenously,respectively,30 min after 0.1％ dimethyl sulfoxide (the vehicle for curcumin) 0.5 ml was injected intraperitoneally.In groups Cur+ ALl and Cur,curcumin 20 mg/kg (0.5 ml) was injected intraperitoneally,and 30 min later LPS 10 mg/kg and normal saline 0.5 ml were injected,respectively.The rats were then sacrificed at 6 h after injection of LPS.The lungs were removed for microscopic examination.The pathological changes of the lung were scored.The malondialdehyde (MDA) content,superoxide dismutase (SOD)activity and expression of HO-1,AP-1 and HO-1 mRNA in lung tissues were determined.Results Compared with group C,the pathological score and MDA content were significantly increased,the SOD activity was significantly decreased,and the expression of HO-1,AP-1 and HO-1 mRNA was up-regulated in groups ALl and Cur +AL(l) (P ＜ 0.05),and no significant change was found in the parameters mentioned above in group Cur (P ＞ 0.05).The pathological score and MDA content were significantly higher,and the SOD activity and expression of HO-1,AP-1 and HO-1 mRNA were significantly lower in group Cur + ALl than in group ALI(P ＜ 0.05).Conclusion Transcription factor AP-1 activation is involved in the up-regulation of HO-1 expression during LPS-induced ALI in rats. Key words: Activator protein-1; Endotoxemia; Heme oxygenase-1; Respiratory distress syndrome,adult

Effects of preconditioning with different concentrations of sevoflurane on the expression of Toll-like receptor 4 in rats with acute lung injury induced by lipopolysaccharide

Objective To investigate the effects of preconditioning with different concentrations of sevoflurane on the expression of Toll-like receptor 4 (TLR4) in rats with acute lung injury (ALI) induced by lipopolysaccharide (LPS).Methods Thirty adult male Sprague-Dawlcy rats,wcighing 200-250 g,were randomly divided into 5 groups (n =6 each):normal saline group (group NS),group ALI,and preconditioning with different concentrations of sevoflurane groups (groups S1-3).ALI was induced by intratracheal instillation of LPS 5 mg/kg.Groups S1-3 inhaled 1.2％,2.4 ％ and 4.8 ％ sevoflurane for 30 min respectively,and ALI was induced 30 min later.The rats were sacrificed at 12 h after administration of LPS or normal saline and lungs were removed for microscopic examination and for determination of TLR4 mRNA and protein expression in lung tissues and concentrations of TNF-α and IL-1β in broncho-alveolar lavage fluid (BALF).W/D lung weight ratio was calculated.Results Compared with group NS,W/D lung weight ratio and concentrations of TNF-a and IL-1β in BALF were significantly increased and the expression of TLR4 mRNA and protein was up-regulated in groups ALI and S1-3 (P ＜ 0.01).Compared with group ALI,the parameters mentioned above were significantly decreased in groups S2 and S3,and the concentrations of TNF-α and IL-1 β in BALF were significantly decreased and the expression of TLR4 mRNA was down-regulated in group S1 (P ＜ 0.05 or 0.01).The parameters mentioned above were significantly lower in groups S2 and S3 than in group S1 (P ＜ 0.05).The pathologic changes were significantly attenuated in groups S1-3 compared with group ALI.Conclusion Preconditioning with sevoflurane can concentration-dependently reduce LPS-induced ALI in rats through inhibiting the up-regulation of TLR4 expression in lung tissues and reducing the inflammatory response. Key words: Anesthetics, inhalation; Respiratory distress syndrome, adult; Toll-like receptors 4; Preconditioning

Role of MLK3-MKK3/6-p38MAPK signal transduction pathway in lipopolysaccharide-induced acute lung injury in rats

Objective To evaluate the role of MLK3-MKK3/6-p38MAPK signal transduction pathway in lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats. Methods Seventy-eight healthy adult male SD rats weighing 200-250 g were randomly divided into 4 groups: control group (group C, n = 6), ALI group ( n =24), MLK3 inhibitor K252a group (group MK, n = 24) and p38MAPK specific inhibitor SB203580 group (group MS, n = 24). ALI was induced by iv injection of LPS 5 mg/kg via tail vein, while the equal volume of normal saline was given instead in group C. K252a 75 μg/kg and SB203580 10 mg/kg were injected intravenously via tail vein 30 min before LPS administration in group MK and MS respectively. The rats were killed at 1, 3, 6 and 12 h (T1-4) after LPS administration in group ALI, MK and MS (6 rats at each time point) and immediately after normal saline administration in group C. The lungs were removed for microscopic examination. The left lung was lavaged.The broncho-alveolar lavage fluid (BALF) was collected. The concentration of TNF-α in the BALF was determined by ELISA. W/D lung weight ratio was calculated. The expression of p-MLK3, p-MKK3/6 and p-p38MAPK were determined by Western blot. Results The concentration of TNF-α in the BALF, W/D lung weight ratio, and expression of p-MLK3, p-MKK3/6 and p-p38MAPK were significantly higher in the other three groups than in group C (P ＜ 0.01). The parameters mentioned above were significantly lower in group MK, and the concentration of TNF-α in the BALF, W/D lung weight ratio, and p-p38MAPK expression were significantly lower in group MS than in group ALI (P ＜ 0.05). The microscopic examination showed that LPS-induced ALI was less severe in group MK and MS than in group ALI. Conclusion MLK3-MKK3/6-p38MAPK signal transduction pathway plays an important role in LPS-induced ALI in rats. Key words: Mitogen-activated protein kinase kinases; Respiratory distress syndrome, adult; Endotoxemia

INTRAVENOUS DELIVERY OF BONE MARROW-DERIVED ENDOTHELIAL PROGENITOR CELLS IMPROVES SURVIVAL AND ATTENUATES LIPOPOLYSACCHARIDE-INDUCED LUNG INJURY IN RATS

Acute lung injury (ALI) is a devastating disease, which is characterized by diffuse endothelium, epithelial damage, and increased pulmonary capillary permeability. Recent data have suggested that the circulating endothelial progenitor cells (EPCs) play an important role in endothelial repair after vascular injury. This study was undertaken to investigate possible endothelial-repairing effects of EPC transplantation after LPS-induced ALI in rats. Using Y-chromosome in situ hybridization and reverse transcription polymerase chain reaction assay, we detected the expression of sex-determining region y in the injured lungs of female model rats, suggesting that allogenic EPCs can migrate to the injured lung tissues. Rats that have received the EPC treatment had a reduced pulmonary edema level, inflammation, hemorrhage, and hyaline membrane formation, as well as an increased survival rate from 44% to 81%. Furthermore, anti-inflammatory cytokine IL-10 levels were dramatically increased in the EPC-treated rats compared with the phosphate buffered saline-treated rats. On the contrary, endothelin-1 and iNOS were downregulated in the EPC-treated group. These findings provide evidence that i.v. EPC treatment results in engraftment of EPCs to the injured lung tissue, which can significantly attenuate lung injury and improve survival in ALI rats. The beneficial effects of EPC engraftment is likely to come from maintaining the integrity of pulmonary alveolar-capillary barrier, reestablishing the endothelial function in vessels and ameliorating the inflammatory state.

The Effect of Itraconazole Pretreatment in Lipopolysaccharide-Induced Acute Lung Injury in Rats

Background: Despite the fact that a randomized controlled trial did not support the use of ketoconazole for treatment of acute lung injury (ALI), there is evidence that pretreatment with ketoconazole might prevent ALI in critically ill patients. An in vitro study showed, however, that itraconazole was a more potent inhibitor of thromboxane and leukotriene formation than was ketoconazole. We investigated the effect of itraconazole pretreatment in lipopolysaccharide (LPS)-induced ALI in rats. Methods: Twenty-one pathogen free, male Sprague-Dawley rats were administered either saline or LPS (5 mg/kg of body weight) intratracheally, with or without intraperitoneal pretreatment of itraconazole (2.5 mg/kg). Six hours after saline or LPS treatment (7 h after itraconazole pretreatment), samples were obtained. Results: Compared with the saline group, LPS group had increased total cell count, polymorphonuclear leukocyte differential count, protein, lactate dehydrogenase (LDH) and cytokines in BAL fluid. Itraconazole pretreatment decreased polymrphonuclear leukocyte differential count, protein and LDH in BAL fluid compared with those of LPS-treated rats without itraconazole pretreatment. Itraconazole pretreatment also decreased the elevated BAL fluid levels of interleukin-1β (IL-1β) and cytokine-induced neutrophil chemoattractant (CINC) by LPS. There was, however, no difference in the BAL fluid tumor necrosis factor α (TNF-α) level in terms of itraconazole pretreatment in LPS-treated rats. Histopathologic features of LPS-induced ALI were attenuated by itraconazole pretreatment. Conclusions: These results suggest that itraconazole pretreatment attenuated LPS-induced ALI in rats. Decreases in levels of IL-1β and CINC would likely be associated with attenuation of LPS-induced ALI in rats by itraconazole pretreatment.

Expression of acid sensing ion channel 3 in the lung tissue of rats with, acute lung injury

Objective To explore the expression of acid seining ion channels-3 (ASIC3) in lung tissue in rats with acute lung injury (ALI). Method Twenty four male Sprague-Dawley (SD) rats were randomly divided into four groups: LPS groups (LPS 2 h, LPS 4 h, LPS 6 h group, n=6), stimulated by LPS for 2, 4, 6 hours, respectively; normal control group, injected with saline (NS group, n=6). The ALI models were produced through venous injection of LPS, and the criteria was the characteristic pathological changes in the lung tissue. Ar-terial blood gas analysis was observed, lung wet and dry weight ratio (W/D), lung histopathology and ASIC3 ex-pression were detected. Data were expressed as mean±standard deviation. Independent Sample T test and One-way ANOVA and Kendall's tau_b were used for comparison in SPSS 13.0, and changes were considered as statistieal-ly significant if P value was less than 0.05. Results The partial pressure of oxygen (PaO2) in LPS 2 h, LPS 4 h, LPS 6 h group was (67.47±6.01), (59.17±7.18), (52.54±7.62) , respecively, and was significantly lower than that in eontrol group (98.15±1.06) (P<0.01). Compare with control group, pH was significantly lower in LPS4 h group (7.28±0.04), LPS6 h group (7.24±0.03) (P<0.01). Inflammation cells gradually increased, alveolar septum was widened, edema existed in interstitial spaces, and pulmonary structures gradually destroyed in LPS groups.The expression of ASIC3 in LPS4 h, LPS 6 h group was (205.91±10.12), (196.51± 18.60), respectively, and was significantly lower thanthat in control group (220.23±10.11) (P<0.05). The W/D in LPS 6 h group was (5.18±0.21), and was significantly higher than that in the control group (4.45± 0.18) (P<0.05). Conclusions ASIC3 is expressed in alveolar epithelial cells and bronchial epithehal cells in LPS-induced ALI rats. Key words: Acute lung injury; Lipopolysaccharide; Acid sensing ion channels-3

The Role of Endogenous Histamine on the Pathogenesis of the Lipopolysaccharide (LPS)-Induced, Acute Lung Injury: A Pilot Study

Histamine is widely distributed in the lungs and increases capillary permeability and P-selectin expression. To observe the role of histamine in acute lung injury (ALI), we measured the histamine and protein concentrations and cell numbers in the bronchoalveolar lavage (BAL) of LPS-induced ALI in rats. We instilled LPS (3 mg/kg) intratracheally, in conjunction with the intravenous histamine receptor antagonists (mepyramine, a H1-receptor antagonist, or ranitidine, a H2-receptor antagonist). LPS increased protein concentration and neutrophil numbers in the BAL as well as myeloperoxidase (MPO) activity in lungs after 6 h. LPS also increased histamine concentration in BAL after 2 h. Mepyramine and ranitidine attenuated the increased histamine concentrations. Total cell number in the BAL and MPO activity in the lungs were significantly decreased and neutrophil numbers and protein concentration in the BAL seemed to decrease with the administration of ranitidine at 6 h. In conclusion, endogenous histamine might be involved in the recruitment of neutrophils and protein leaks in LPS-induced ALI via the H2 receptors.