OBJECTIVE: To investigate the role and mechanism of the cyclic guanosine monophosphate-adenosine monophosphate synthase/stimulator of interferon gene (cGAS/STING) pathway in oleic acid-induced acute lung injury (ALI) in mice. METHODS: Male wild-type C57BL/6J mice were randomly divided into five groups (each n = 10): normal control group, ALI model group, and 5, 50, 500 μg/kg inhibitor pretreatment groups. The ALI model was established by tail vein injection of oleic acid (7 mL/kg), while the normal control group received no intervention. The inhibitor pretreatment groups were intraperitoneally injected with the corresponding doses of cGAS inhibitor RU.521 respectively 1 hour before modeling. At 24 hours post-modeling, blood was collected, and mice were sacrificed. Lung tissue pathological changes were observed under light microscopy after hematoxylin-eosin (HE) staining, and pathological scores were assessed. Western blotting was used to detect the protein expressions of cGAS, STING, phosphorylated TANK-binding kinase 1 (p-TBK1), phosphorylated interferon regulatory factor 3 (p-IRF3), and phosphorylated nuclear factor-κB p65 (p-NF-κB p65) in lung tissue. Immunohistochemistry was performed to observe STING and p-NF-κB positive expressions in lung tissue. Serum interferon-β (IFN-β) levels were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: Compared with the normal control group, the ALI model group exhibited significant focal alveolar thickening, intra-alveolar hemorrhage, pulmonary capillary congestion, and neutrophil infiltration in the pulmonary interstitium and alveoli, along with markedly increased pathological scores (10.33±0.58 vs. 1.33±0.58, P < 0.05). Protein expressions of cGAS, STING, p-TBK1, p-IRF3, and p-NF-κB p65 in lung tissue significantly increased [cGAS protein (cGAS/β-actin): 1.24±0.02 vs. 0.56±0.02, STING protein (STING/β-actin): 1.27±0.01 vs. 0.55±0.01, p-TBK1 protin (p-TBK1/β-actin): 1.34±0.03 vs. 0.22±0.01, p-IRF3 protein (p-IRF3/β-actin): 1.23±0.02 vs. 0.36±0.01, p-NF-κB p65 protein (p-NF-κB p65/β-actin): 1.30±0.02 vs. 0.53±0.02, all P < 0.05], positive expressions of STING and p-NF-κB in lung tissue were significantly elevated [STING (A value): 0.51±0.03 vs. 0.30±0.07, p-NF-κB (A value): 0.57±0.05 vs. 0.31±0.03, both P < 0.05], and serum IFN-β levels were also significantly higher (ng/L: 256.02±3.84 vs. 64.15±1.17, P < 0.05). The cGAS inhibitor pretreatment groups showed restored alveolar structural integrity, reduced inflammatory cell infiltration, and decreased hemorrhage area, along with dose-dependent lower pathological scores as well as the protein expressions of cGAS, STING, p-TBK1, p-IRF3 and p-NF-κB p65 in lung tissue, with significant differences between the 500 μg/kg inhibitor group and ALI model group [pathological score: 2.67±0.58 vs. 10.33±0.58, cGAS protein (cGAS/β-actin): 0.56±0.03 vs. 1.24±0.02, STING protein (STING/β-actin): 0.67±0.03 vs. 1.27±0.01, p-TBK1 protein (p-TBK1/β-actin): 0.28±0.01 vs. 1.34±0.03, p-IRF3 protein (p-IRF3/β-actin): 0.32±0.01 vs. 1.23±0.02, p-NF-κB p65 protein (p-NF-κB p65/β-actin): 0.63±0.01 vs. 1.30±0.02, all P < 0.05]. Compared with the ALI model group, positive expressions of STING and p-NF-κB in lung tissue were significantly reduced in the 500 μg/kg inhibitor group [STING (A value): 0.40±0.01 vs. 0.51±0.03, p-NF-κB (A value): 0.43±0.02 vs. 0.57±0.05, both P < 0.05], and serum IFN-β levels were also markedly reduced (ng/L: 150.03±6.19 vs. 256.02±3.84, P < 0.05). CONCLUSIONS The cGAS/STING pathway is activated in oleic acid-induced ALI, leading to exacerbated inflammatory responses and increased lung damage. RU.521 can inhibit cGAS, thereby down-regulating the expression of pathway proteins and cytokines, and providing protection to lung tissue.
Animals ; Acute Lung Injury/chemically induced* ; Male ; Nucleotidyltransferases/metabolism* ; Mice ; Signal Transduction ; Mice, Inbred C57BL ; Membrane Proteins/metabolism* ; Oleic Acid/adverse effects* ; Transcription Factor RelA/metabolism* ; Lung/pathology* ; Interferon Regulatory Factor-3/metabolism* ; Disease Models, Animal

OBJECTIVETo establish nonalcoholic fatty liver disease (NAFLD) model induced by free fatty acid (FFA) and iron, and to explore the synergistic effect of FFA and Fe(2+) on the pathogenesis of NAFLD and mechanisms.

METHODSHuman liver carcinoma cell HepG2 was respectively treated with 0.250, 0.500, 1.000 mmol/L oleic acid, 0.500 mmol/L oleic acid+0.125 mmol/L Fe(2+), 0.500 mmol/L oleic acid+0.250 mmol/L Fe(2+), and 0.500 mmol/L oleic acid+0.500 mmol/L Fe(2+). Human liver carcinoma cell HepG2 was normally cultured in the control group. Lipid accumulation of cells were observed by oil red O staining and the determination of the triglyceride (TG) contents by GPO-PAP, then the expression of key genes involved in fatty acid β-oxidation (fatty acyl CoA synthetase-1 (ACSL-1), carnitine acyl transferase 1 (CPT-1a), fatty acid synthetase (FAS)) was determined using RT-PCR. The differences of TG content and ACSL-1, CPT-1a, FAS, mRNA relative value were analyzed among different groups.

RESULTSThe results of oil red O staining indicated that the contents of lipid droplets were obviously elevated with the increase of Fe(2+) concentration in human liver carcinoma cell HepG2 treated with 0.500 mmol/L oleic acid and different concentrations of Fe(2+). The TG contents of HepG2 cell in control group, 0.250, 0.500, 1.000 mmol/L oleic acid groups, 0.500 mmol/L oleic acid+0.125 mmol/L Fe(2+) group, 0.500 mmol/L oleic acid+0.250 mmol/L Fe(2+) group, 0.500 mmol/L oleic acid+0.500 mmol/L Fe(2+) group respectively were (90.0 ± 1.6), (131.7 ± 5.4), (153.7 ± 3.0), (254.1 ± 4.0), (164.5 ± 6.0), (180.1 ± 7.7), (235.6 ± 4.5) nmol/mg (F = 396.00, P < 0.05). The expression levels of ACSL-1 mRNA in 0.500 mmol/L oleic acid group, 0.500 mmol/L oleic acid+0.125 mmol/L Fe(2+) group, 0.500 mmol/L oleic acid +0.250 mmol/L Fe(2+) group, 0.500 mmol/L oleic acid +0.500 mmol/L Fe(2+) group respectively were (0.94 ± 0.02), (0.89 ± 0.04), (0.85 ± 0.02), (0.74 ± 0.04) (F = 50.00, P < 0.05); the mRNA levels of CPT-1a were (0.89 ± 0.03), (0.79 ± 0.05), (0.67 ± 0.04), (0.51 ± 0.05) (F = 79.00, P < 0.05); the mRNA levels of FAS were (1.31 ± 0.05) , (1.44 ± 0.03), (1.51 ± 0.05), (1.56 ± 0.06 ) (F = 79.70, P < 0.05).

CONCLUSIONThe NAFLD liver cell model could be established by oleic acid and Fe(2+) in HepG2 cells. FFA and iron might be involved in the pathogenesis of NAFLD through the intervention of fatty acid β-oxidation.

Carnitine O-Palmitoyltransferase ; Coenzyme A Ligases ; Fatty Acid Synthase, Type I ; Fatty Acids ; Fatty Acids, Nonesterified ; adverse effects ; Hep G2 Cells ; Humans ; Iron ; adverse effects ; Non-alcoholic Fatty Liver Disease ; chemically induced ; Oleic Acid ; RNA, Messenger ; Triglycerides

Cumulative evidence suggests that renal vascular endothelial injury play an important role in initiating and extending tubular epithelial injury and contribute to the development of ischemic acute renal failure. Our previous studies have demonstrated that iptakalim's endothelium protection is related to activation of SUR2B/Kir6.1 subtype of ATP sensitive potassium channel (K(ATP)) in the endothelium. It has been reported that SUR2B/Kir6.1 channels are widely distributed in the tubular epithelium, glomerular mesangium, and the endothelium and the smooth muscle of blood vessels. Herein, we hypothesized that activating renal K(ATP) channels with iptakalim might have directly neroprotective effects. In this study, glomerular endothelial, mesangial and tubular epithelial cells which are the main cell types to form nephron were exposed to oleic acid (OA) at various concentrations for 24 h. 0.25 microl/ml OA could cause cellular damage of glomerular endothelium and mesangium, while 1.25 microl/ml OA could lead to the injury of three types of renal cells. It was observed that pretreatment with iptakalim at concentrations of 0.1, 1, 10 or 100 micromol/L prevented cellular damage of glomerular endothelium and tubular epithelium, whereas iptakalim from 1 to 100 micromol/L prevented the injury of mesangial cells. Our data showed iptakalim significantly increased survived cell rates in a concentration-dependent manner, significantly antagonized by glibenclamide, a K(ATP) blocker. Iptakalim played a protective role in the main cell types of kidney, which was consistent with natakalim, a highly selective SUR2B/Kir6.1 channel opener. Iptakalim exerted protective effects through activating SUR2B/Kir6.1 channels, suggesting a new strategy for renal injury by its endothelial and renal cell protection.
Cells, Cultured ; Epithelial Cells ; metabolism ; Glyburide ; adverse effects ; Humans ; KATP Channels ; metabolism ; Kidney ; cytology ; metabolism ; physiopathology ; Kidney Diseases ; drug therapy ; metabolism ; Oleic Acid ; adverse effects ; Propylamines ; pharmacology ; Protective Agents ; pharmacology

OBJECTIVETo observe the expression of P-selectin (Ps), intercellular adhesion molecule-1 (ICAM-1) and nuclear factor-kappa B (NF-kappaB) in lung tissues of acute lung injury (ALI) rat model induced by oleic acid (OA) and to explore the protective effects of melatonin (MT) in lung tissues in rats.

METHODSAll rats were randomly divided into four groups: control group, OA group, MT + OA group and SB203580 + OA group. Rat model of ALI was established by intravenous injection of oleic acid (OA). Lung coefficient was measured, lung tissues were imbedded by paraffin to observe morphological changes and the expression of Ps, ICAM-1 and NF-kappaB in lung tissues by means of immunohistochemistry staining.

RESULTSCompared with control group, the lung coefficient increased significantly in OA group (P < 0.05). Alveolar septum thickened significantly in OA group, there had many infiltrated inflammatory cells and collapsed alveoli of lung; positive expression of Ps, ICAM-1 and NF-kappaB were very obvious (P < 0.05); the administration of MT and SB203580 mitigated above changes significantly (P < 0.05).

CONCLUSIONMT possesses obviously protective effect on lung tissues during ALI, its protective mechanism might be related to the inhibition of the expression of Ps, ICAM-1 and NF-kappaB.

Acute Lung Injury ; chemically induced ; physiopathology ; prevention & control ; Animals ; Down-Regulation ; drug effects ; Intercellular Adhesion Molecule-1 ; metabolism ; Male ; Melatonin ; pharmacology ; therapeutic use ; NF-kappa B ; metabolism ; Oleic Acid ; adverse effects ; P-Selectin ; metabolism ; Protective Agents ; pharmacology ; Rats ; Rats, Sprague-Dawley

OBJECTIVE: To explore the effect of ulinastain on the expression of hemeoxy genase-1 (HO-1) in oil acid-induced acute lung injury in rats. METHODS: The animal model of acute lung injury was established by oil acid. Thirty SD rats were randomly divided into 3 groups: the blank control group (A), the acute lung injury group (B) and the acute lung injury group (C) followed by injecting 100 mL/kg ulinastatin. Each group consisted of 10 rats. Group A were given 0.2 mL/kg natural solution through the trial vein; Group B and C were given 0.2 mL/kg oil-acid through trial vein, while group C were injected 100mL/kg ulinastatin by the peritoneal cavity after injecting oil acid. After 4 hours, the rates of respiration were counted and blood samples were cramped out through the heart puncture for blood gas analysis. The expressions of hemeoxygenase-1 and the pathologic construction changes were determined by HE staining in the lower right lung of rats in the 3 groups. RESULTS: The respiration dysfunction caused by oil acid could be prominently improved by ulinastain. There was only a little expression of hemeoxygenase-1 in the lung of Group A, but the expression increased in Group B and significatively increased in Group C. CONCLUSION Ulinastatin may protect the rats from acute lung injury through increasing the expression of HO-1.
Acute Lung Injury ; chemically induced ; metabolism ; Animals ; Glycoproteins ; pharmacology ; Heme Oxygenase (Decyclizing) ; metabolism ; Lung ; drug effects ; metabolism ; Male ; Oleic Acid ; adverse effects ; Rats ; Rats, Sprague-Dawley

OBJECTIVEImpaired active fluid transport of alveolar epithelium may involve in the pathogenesis and resolution of alveolar edema. The objective of this study was to explore the changes in alveolar epithelial liquid clearance during lung edema following acute lung injury induced by oleic acid.

METHODSForty-eight Wistar rats were randomly divided into six groups, i.e., injured, amiloride, ouabain, amiloride plus ouabain and terbutaline groups. Twenty-four hours after the induction of acute lung injury by intravenous oleic acid (0.25 ml/kg), 5% albumin solution with 1.5 microCi (125)I-labeled albumin (5 ml/kg) was delivered into both lungs via trachea. Alveolar liquid clearance (ALC), extravascular lung water (EVLW) content and arterial blood gases were measured one hour thereafter.

RESULTSAt 24 h after the infusion of oleic acid, the rats developed pulmonary edema and severe hypoxemia, with EVLW increased by 47.9% and ALC decreased by 49.2%. Addition of either 2x10(-3) M amiloride or 5x10(-4) M ouabain to the instillation further reduced ALC and increased EVLW. ALC increased by approximately 63.7% and EVLW decreased by 46.9% with improved hypoxemia in the Terbutaline (10(-4) M) group, compared those in injured rats. A significant negative correlation was found between the increment of EVLW and the reduction of ALC.

CONCLUSIONSActive fluid transport of alveolar epithelium might play a role in the pathogenesis of lung edema in acute lung injury.

Adrenergic beta-Agonists ; pharmacology ; Animals ; Epithelium ; metabolism ; Oleic Acid ; adverse effects ; Pulmonary Alveoli ; metabolism ; Random Allocation ; Rats ; Rats, Wistar ; Respiratory Distress Syndrome, Adult ; chemically induced ; metabolism ; Terbutaline ; pharmacology