The effect and mechanism of volatile oil emulsion from leaves of Clausena lansium (Lour.) Skeels on Staphylococcus aureus in vitro.

This study aimed to develop a suitable dosage form of volatile oil from wampee leaves and to explore its antibacterial mechanism in vitro. The chemical composition of the volatile oil from wampee leaves was determined by gas chromatography-mass spectrometry (GC-MS). Different microemulsion ratios were tested and their stabilities were investigated to determine the optimal ratio. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the wampee leaves volatile oil emulsion (WVOE) against Salmonella typhimurium (S. typhimurium) and Staphylococcus aureus (S. aureus) were determined using double-dilution and plate-counting methods, respectively. Morphological changes in these two bacteria were observed using scanning electron microscopy. Death, ultrastructural morphology, and biofilm formation were also assessed for S. aureus. Finally, we established an S. aureus-infected Lewis lung carcinoma (LLC) cell model to evaluate the protective effects of the volatile oil emulsion and the associated mechanisms. The volatile oil extracted from wampee leaves contained 37 compounds, of which 96.49% were aromatic hydrocarbons, terpenoids, and their oxygen-containing derivatives. The emulsion was most stable at 1:1 in the oil phase and 1:9 in the water phase. WVOE had poor antibacterial activity against S. typhimurium, but the MIC and MBC against S. aureus were 312.5 and 2,500 µg/mL, respectively. S. aureus survival rates were 84.6%, 14.5%, and 12.8% in the 1/2, 1, and 4 × MIC groups, respectively, compared with 97.2% in the control group. S. typhimurium survival was not affected by WVOE treatment. WVOE administration induced cavity formation and abnormal binary fission, and significantly inhibited biofilm formation in S. aureus cells. The WVOE notably reduced the number of S. aureus and inhibited TLR4, NLRP3, NF-κB, IL-6, IL-18, and TNF-α gene expression in S. aureus-infected LLC cells. The WVOE had a significant inhibitory effect on S. aureus and altered its cell membrane permeability. Moreover, it alleviated inflammation by inhibiting the NF-κB-NLRP3 pathway in S. aureus-infected LLC cells.

Three different routes of EHEC O157:H7 infection were used to establish EHEC broiler model.

In order to study the prevention and control EHEC disease measures in poultry, the infection process and development of this disease and the pathological changes of various organs were to be observed. In this study, chickens were infected with different doses of enterohemorrhagic Escherichia coli (EHEC) O157:H7 using different routes of administration to establish EHEC broiler model. A total of 195 14-day-old broilers were randomly divided into 13 groups: including control group, Enema-drip groups (1010, 1011, 1012, 1013 CFUs E. coli O157:H7), gavage groups (P.O) (1011, 1012, 1013, 1014 CFUs E. coli O157:H7), and intraperitoneal injection group (I.P.) (108, 109, 1010, 1011 CFUs E. coli O157:H7). Escherichia coli (E. coli) was given using enema-drip, gavage or intraperitoneal infection. Then the feed intake, weight changes, stool and clinical symptoms of the chicks were recorded during the experiment. 7 d after E. coli infection, blood was collected from the jugular vein and serological tests were carried out. The liver, spleen, and colon of the chicks were extracted to get the organ index, bacteria load, and their histopathological changes. After infection with E. coli, some chicks feces were green or red watery stool, sometimes accompanied by foam, and the material to weight ratio of broilers in I.P. group increased significantly (P < 0.05), the 108 CFUs group were 1.3 times as large as control group. Three modeling methods can result in abnormal serum lipid metabolism and liver function indexes (increase of AST, TBA, T-Bil and TC level; decrease of ALB, TG, and TP level). Infection of chicks with O157:H7 by all 3 methods resulted in its detection in the liver, spleen, and colon. Three modeling methods significantly decreased liver index, and inflammatory cell infiltration and hyperemia were observed in liver. The spleen index in E. coli broilers by gavage and enema-drip was significantly decreased, splenic hyperemia and periarteriolar hyalinosis were observed. The spleen was enlarged with purplish-black spheroids in I.P. group broilers, and the spleen histological changes was more serious. The colon villi of broilers in gavage and enema-drip groups were thinner, more prone to rupture, intestinal lamina propria hyperemia, and inflammatory cell infiltration. Moreover, the number of goblet cells in the mucosal epithelium increased. E. coli O157:H7 can induce liver, spleen and intestinal damage and reduce growth performance of chicks. By comparing these 3 methods, we found that chicks infected with O157:H7 by gavage had more severe liver and intestinal damage, the enema-drip method caused most serious intestinal damage, and I.P. method significantly damaged the liver and spleen of chickens.

Acetaminophen-induced hepatotoxicity predominantly via inhibiting Nrf2 antioxidative pathway and activating TLR4-NF-κB-MAPK inflammatory response in mice.

To explore the action time and molecular mechanism underlying the effect of acetaminophen (APAP) on liver injury. APAP was used to establish drug-induced liver injury (DILI) model in mice. Mice in the model group were intraperitoneally injected 300 mg/kg APAP for 6, 12, and 24 h respectively, and control group mice were given the same volume of normal saline. The mice were anesthetized through intravenous injection of sodium pentobarbital at 6, 12, and 24 h after APAP poisoning. Analysis of ALT, AST and ALP in serum, liver histopathological observation, oxidative damage and western blot were performed. The livers in APAP exposed mice were pale, smaller, with a rough texture, and poorly arranged cells. Lesions, large areas of hyperemia, inflammation, swelling, poorly cell arrangement, necrosis, and apoptosis of liver cells were obvious in the liver tissue sections. Serum ALT, AST and ALP levels were significantly enhanced at 12 h of APAP adminstration mice than that of in control group mice (P＜0.05). The histopathological alterations and proinflammatory cytokines (IL-1ß, TNF-α and IL-6) levels were most severe at 12 h of APAP-induced hepatotoxicity. APAP treatment induced oxidative stress by decreasing hepatic activities of superoxide dismutase (SOD) and glutathione (GSH) (P＜0.05), and enhancing malondialdehyde (MDA) content (P＜0.05). Moreover, APAP inhibited erythroid 2-related factor 2 (Nrf2) antioxidative pathway with decreased of Nrf2 and HO-1 proteins levels. Furthermore, APAP aggravated the activation of NLRP3 inflammasome by increasing of NLRP3, caspase-1, ASC, IL-1ß and IL-18 proteins levels. Finally, APAP further significantly activated the toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) signaling pathways. This study demonstrated that APAP-induced hepatotoxicity by inhibiting of Nrf2 antioxidative pathway and promoting TLR4-NF-κB-MAPK inflammatory response and NLRP3 inflammasome activation.

Resveratrol relieves chronic heat stress-induced liver oxidative damage in broilers by activating the Nrf2-Keap1 signaling pathway.

Heat stress (HS) affects poultry production and welfare, causing enormous damage to poultry. Resveratrol, an antioxidant and anti-inflammatory natural plant polyphenol, is widely used in agriculture for the prevention of oxidative stress-related diseases. This study aimed to explore the effects and potential mechanism of resveratrol on liver oxidative damage in heat-stressed broilers. Sixty SPF chickens were randomly divided into control, heat stress (HS) and HS+ resveratrol (resveratrol) groups. Broilers were exposed to 35 ± 2 â„ƒ (8 h/d) for 7 consecutive days to induce HS, and the other 16 h/d were kept at 23 ± 2 â„ƒ, similar to the control group. Broilers received 400 mg/kg resveratrol in the basic diet 2 days before exposure to HS and for the following 7 days. The results showed that resveratrol improved growth performance by increasing the average daily gain (ADG) and reducing the feed conversion ratio (FCR), compared with the HS group. Heat stress reduced liver weight and index, increased inflammatory cell infiltration in the liver, enhanced serum AST levels, and decreased TP and ALB II levels, which resulted in liver injury in broilers, and resveratrol effectively alleviated liver injury. Moreover, supplementation with resveratrol enhanced the activities of liver antioxidant enzymes resulting in higher GPX and SOD levels than those in the heat-stressed broilers, and decreased MDA levels. Furthermore, resveratrol alleviated liver oxidative stress by activating the gene and protein levels of Nrf2 and HO-1, enhancing NQO1 and SOD1 gene levels, and decreasing protein levels of HSP70, p62, and Keap1, and thereby alleviated the liver injury of heat-stressed broilers. Compared with the HS group, Nrf2 immunofluorescence was significantly up-regulated in the livers of resveratrol group. These results suggest that resveratrol can enhance the liver antioxidant function by activating the Nrf2-Keap1 signaling pathway to promote growth performance in broilers under HS.