Inhibitory effects of α-cyperone on adherence and invasion of avian pathogenic Escherichia coli O78 to chicken type II pneumocytes

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.

The Anti-Endometriotic Effect of Cyperi Rhizoma Extract, Inhibiting Cell Adhesion and the Expression of Pain-Related Factors through Akt and NF-kB Pathways

Rhizomes of Cyperus rotundus have been widely used as a traditional medicine in Asia for the treatment of gynecological diseases. However, there is no scientific evidence demonstrating the effect of C. rotundus rhizomes on endometriosis, which is characterized by the adhesion of endometrial tissues outside the uterus, resulting in chronic and severe pelvic pain. The aim of this study was to investigate the effects of Cyperi rhizoma extract (CRE) on cell adhesion and the expression of pain-related factors (neurotrophins) in endometriotic cells, and to elucidate the underlying molecular mechanisms. CRE inhibited the adhesion of human endometriotic 12Z cells to peritoneal mesothelial Met5A cells using by adhesion assays. The mRNA expression of adhesion molecules [P-cadherin and matrix metalloproteinase (MMP)-2] was downregulated by CRE treatment. In addition, CRE significantly inhibited the mRNA expression of neurotrophins (BDNF, NGF, NT-3 and NT-4/5) in 12Z cells. Moreover, Akt overexpression markedly neutralized the inhibition of cell adhesion by CRE and expression of neurotrophins in 12Z cells. Furthermore, it was found that CRE suppressed NF-kB activation through the Akt pathway. These data suggest that CRE exerts anti-endometriotic activities by the inhibition of cell adhesion and neurotrophin expression, through the negative regulation of the Akt and NF-kB pathways in endometriotic cells.

The bird's immune response to avian pathogenic Escherichia coli

Avian pathogenic Escherichia coli (APEC) cause colibacillosis in birds, a syndrome of severe respiratory and systemic disease that constitutes a major threat due to early mortality, condemnation of carcasses and reduced productivity. APEC can infect different types of birds in all commercial settings, and birds of all ages, although disease tends to be more severe in younger birds likely a consequence of an immature immune system. APEC can act as both primary and secondary pathogens, with predisposing factors for secondary infections including poor housing conditions, respiratory viral and Mycoplasma spp. infections or vaccinations. Controlled studies with APEC as primary pathogens have been used to study the bird's immune response to APEC, although it may not always be representative of natural infections which may be more complex due to the presence of secondary agents, stress and environmental factors. Under controlled experimental conditions, a strong early innate immune response is induced which includes host defence peptides in mucus and a cellular response driven by heterophils and macrophages. Both antibody and T-cell mediated adaptive responses have been demonstrated after vaccination. In this review we will discuss the bird's immune response to APEC as primary pathogen with a bias towards the innate immune response, as mechanistic adaptive studies clearly form a much more limited body of work despite numerous vaccine trials.

Analysis of deep sequencing exosome-microRNA expression profile derived from CP-II reveals potential role of gga-miRNA-451 in inflammation

Mycoplasma gallisepticum (MG) can cause chronic respiratory disease (CRD) in chickens. While several studies have reported the inflammatory functions of microRNAs during MG infection, the mechanism by which exosomal miRNAs regulate MG-induced inflammation remains to be elucidated. The expression of exosome-microRNA derived from MG-infected chicken type II pneumocytes (CP-II) was screened, and the target genes and function of differentially expressed miRNAs (DEGs) were predicted. To verify the role of exosomal gga-miR-451, Western blot, ELISA and RT-qPCR were used in this study. The results showed that a total of 722 miRNAs were identified from the two exosomal small RNA (sRNA) libraries, and 30 miRNAs (9 up-regulated and 21 down-regulated) were significantly differentially expressed. The target miRNAs were significantly enriched in the treatment group, such as cell cycle, Toll-like receptor signalling pathway and MAPK signalling pathway. The results have also confirmed that gga-miR-451-absent exosomes derived from MG-infected CP-II cells increased inflammatory cytokine production in chicken fibroblast cells (DF-1), and wild-type CP-II cell-derived exosomes displayed protective effects. Collectively, our work suggests that exosomes from MG-infected CP-II cells alter the dynamics of the DF-1 cells, and may contribute to pathology of the MG infection via exosomal gga-miR-451 targeting YWHAZ involving in inflammation.

Schizandrin attenuates lung lesions induced by Avian pathogenic Escherichia coli in chickens

Avian pathogenic Escherichia coli (APEC) can cause serious pathological changes and inflammation in chickens. Schizandrin has anti-inflammatory activity and can prevent damage to various tissues and organs. The purpose of this study was to investigate the protective effect of schizandrin on APEC-induced lung lesions in chickens and explore the potential mechanism of schizandrin protection. The schizandrin (50, 100, and 200 mg/kg) was intragastrically administered for 3 days. APEC was administered using intraperitoneal (i.p.) injection to induce lung lesions. Then, chickens were sacrificed by CO2 inhalation 24 h later and the lung tissues were collected for examining histopathological changes, wet/dry (W/D) ratio, myeloperoxidase (MPO) activity, malondialdehyde (MDA), levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-8 and activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. Our findings showed that schizandrin markedly inhibited pathological changes, pulmonary edema, MPO activity and MDA content. Moreover, schizandrin markedly reduced the levels of TNF-α, IL-1β, IL-6 and IL-8 in lung tissue. Importantly, the mechanism responsible for these effects was attributed to the inhibitory effect of schizandrin on NF-κB and MAPK signaling activation. In conclusion, our findings reveal that schizandrin displays anti-oxidant and anti-inflammatory activity against APEC-induced lung lesions in chickens, paving the way for rational use of schizandrin as a protective agent against lung-related inflammatory disease.

RNA-seq profiles of chicken type II pneumocyte in response to Escherichia coli infection

Avian pathogenic Escherichia coli (APEC) causes great economic loss to the poultry industry worldwide. Chicken type II pneumocytes (CP II cells) secrete surfactants and modulate lung immunity to decrease the infection of the invading pathogen. Nevertheless, the pathogenesis of CP II cells to APEC infection remains poorly understood. Therefore, we conducted global gene expression profiling of CP II cells after APEC-O78 infection to explore the host-pathogen interaction. The differentially expressed genes of CP II cells to APEC infection were characterized by RNA-seq with EB-seq algorithm. In consequence, the mRNA of 18996 genes was identified, and CP II cells responded to APEC infection with marked changes in the expression of 1390 genes. Among them, there are 803 down-regulated mRNAs and 587 up-regulated mRNAs. The KEGG prediction and Gene Ontology terms analysis revealed that the major enriched pathways were related to NF-κB signaling pathway, apoptosis pathway, tight junction, and cytokine-cytokine receptor interaction and other pathways. We adopted qRT-PCR to verify the validity of the selected gene expression. The fold induction of qPCR was similar to the RNA-seq results. These results provide a better understanding of the pathogenesis of APEC, especially apoptosis pathway involved in APEC infection.

Avian pathogenic Escherichia coli infection of a chicken lung epithelial cell line

Virulent strains of Escherichia coli (Avian Pathogenic E. Coli: APEC) can cause initial infection of the respiratory tract in chickens potentially leading to systemic infection called colibacillosis, which remains a major cause of economic losses in the poultry industry. The role of epithelial lung cells as first targets of APEC and in initiating the innate immune response is unclear and was investigated in this study. APEC was able to adhere and subsequently invade cells from the chicken lung epithelial CLEC213 cell line exhibiting pneumocyte type II-like characteristics. Invasion was confirmed using confocal microscopy after infection with GFP-labelled APEC. Moreover, the infection resulted in a significant increase in IL-8 gene expression, a chemo-attractant of macrophages and heterophils. Gene expression of interferon α and β were not significantly upregulated and chicken Surfactant Protein A, also did not show a significant upregulation on either gene or protein level. The immune response of CLEC213 cells towards APEC was shown to be similar to stimulation with E. coli LPS. These results establish CLEC213 cells as a novel model system for studying bacterial infection of the lung epithelium and show that these cells may play a role in the initial innate response towards bacterial pathogens.

Rutin inhibits quorum sensing, biofilm formation and virulence genes in avian pathogenic Escherichia coli

The study aimed to investigate whether rutin affects the quorum sensing (QS) of avian pathogenic Escherichia coli (APEC). In this study, APEC-O78 was selected as the test strain. We mainly examined the effects of rutin on the AI-2 secretion by bioluminescence assay, biofilm formation through a crystal violet staining method, and expression of virulence genes of APEC by qRT-PCR. We found that rutin can significantly interfering with QS through reducing the secretion of AI-2, inhibited the biofilm formation, and reduced the expression of virulence genes of APEC. Moreover, rutin markedly decreased adhesion and damage of APEC to chicken type II pneumocytes. These results suggested rutin reduces cell damage of APEC-infected chicken type II pneumocytes through interfering with QS via decreasing AI-2 production, biofilm formation, and the expression of virulence genes. This paper may provide a new evidence for colibacillosis prevention in chicken.

Chemical Composition, Antioxidant, Antimicrobial and Cytotoxic Activities of Essential Oil from Premna microphylla Turczaninow

Premna microphylla Turczaninow, an erect shrub, was widely used in Chinese traditional medicine to treat dysentery, appendicitis, and infections. In this study, the essential oil from P. microphylla Turcz. was obtained by hydrodistillation and analyzed by GC (Gas Chromatography) and GC-MS (Gas Chromatography-Mass Spectrometer). Fifty-six compounds were identified in the oil which comprised about 97.2% of the total composition of the oil. Major components of the oil were blumenol C (49.7%), β-cedrene (6.1%), limonene (3.8%), α-guaiene (3.3%), cryptone (3.1%), and α-cyperone (2.7%). Furthermore, we assessed the in vitro biological activities displayed by the oil obtained from the aerial parts of P. microphylla, namely the antioxidant, antimicrobial, and cytotoxic activities. The antioxidant activity of the essential oil was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. For this, the IC₅₀ value was estimated to be 0.451 mg/mL. The essential oil of P. microphylla exhibited considerable antibacterial capacity against Escherichia coli with an MIC (Minimum Inhibitory Concentration) value of 0.15 mg/mL, along with noticeable antibacterial ability against Bacillus subtilis and Staphylococcus aureus with an MIC value of 0.27 mg/mL. However, the essential oil did not show significant activity against fungus. The oil was tested for its cytotoxic activity towards HepG2 (liver hepatocellular cells) and MCF-7 Cells (human breast adenocarcinoma cell line) using the MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide) assay, and exerted cytotoxic activity with an IC₅₀ of 0.072 and 0.188 mg/mL for 72 h. In conclusion, the essential oil from P. microphylla is an inexpensive but favorable resource with strong antibacterial capacity as well as cytotoxic activity. Thus, it has the potential for utilization in the cosmetics and pharmaceutical industries.

Autoinducer-2 of quorum sensing is involved in cell damage caused by avian pathogenic Escherichia coli

Avian pathogenic Escherichia coli (APEC) infections are responsible for great losses in the poultry industry. Quorum sensing (QS) acts as a global regulatory system that controls genes involved in bacterial pathogenesis, metabolism and protein biosynthesis. However, whether QS of APEC is related to cell damage has not been elucidated. In the present study, we explored the correlation between the damage of chicken type II pneumocytes induced by APEC and the autoinducer-2 (AI-2) activity of APEC. The results showed that when chicken type II pneumocytes were co-cultured with 10⁸ CFU/ml of APEC-O78 for 6 h, the release of LDH reached the highest level (192.5 ± 13.4 U/L) (P < 0.01), and the percentages of dead cells followed the same trend in trypan blue exclusion assay. In addition, the AI-2 activity of cell-free culture fluid (CF) reached the maximum value after 6 h co-culture with 10⁸ CFU/ml of APEC-O78. At the same time, the mRNA expressions of eight virulence genes (papC, fimA, fimC, hlyE, ompA, luxS, pfs, and qseA) of 10⁸ CFU/ml APEC-O78 were significantly increased compared with those of 10⁷ CFU/ml, and the mRNA expressions of four virulence genes (hlyE, tsh, iss, and luxS) of 10⁸ CFU/ml APEC-O78 were higher than those of 10⁹ CFU/ml (p < 0.05) after incubation for 6 h. These results suggested that AI-2-mediated QS is involved in the cell damage induced by APEC-O78, indicating AI-2 may be one new potential target for preventing chicken colibacillosis.