Expression of Inflammatory and Cell Death Program Genes and Comet DNA Damage Assay Induced by Escherichia coli in Layer Hens

Abstract

Modern methods of industrial poultry and egg production systems involve stressful practices that stimulate Escherichia coli (E. coli) activity causing endotoxic shock. This investigation was conducted to evaluate the expression of pro-inflammatory cytokines and cell death program genes and DNA damage induced by E. coli in the brain and liver tissues of laying hens. A total of two hundred and ten H&N brown layer hens with 20 week age, were used in this research. First, preliminary experiments were designed (60 hens in total) to establish the optimal exposure dose of E. coli and to determine the nearest time of notable response to be used in the remainder studies of this research. At 35-wk of age, 150 hens were randomly assigned into 2 groups with 3 replicates of 25 birds each; the first group was injected in the brachial wing vein with 107 E. coli colony/hen, while the second group was injected with saline and served as a control. The body temperature and plasma corticosterone concentration were measured 3 hr after injection. Specimens of liver and brain were obtained from each group and the gene expression of p38 mitogen-activated protein kinase, interlukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), Bax, and caspase-3 genes were measured by quantitative real-time PCR. DNA damage in the brain and liver tissues were also measured by comet assay. Hens treated with E. coli showed significant (P<0.05) increase of body temperature and plasma corticosterone (42.6°C and 14.5 ng/ml, respectively) compared to the control group (41.1°C and 5.5 ng/ml, respectively). Additional remarkable over-inflammation gene expression of p38, IL-1β and TNF-α.genes were also detected in the brain (2.2-fold, 2.0-fold and 3.3-fold, respectively) and the liver (2.1-fold, 1.9-fold and 3.0-fold, respectively) tissues of the infected chickens. It is also important to note that hens injected with E. coli showed an increase in DNA damage in the brain and liver cells (P<0.05). These results were synchronized with activating cell death program since our data showed significant high expression of Bax gene by 2.8- and 2.7-fold and caspase-3 gene by 2.5- and 2.7-fold in the brain and liver tissues of infected chickens, respectively (P<0.05). In conclusion, the current study indicates that E. coli injection induces inflammatory physiological response and triggers cell death program in the brain and liver. Our results provide more understanding to endotoxic shock by E. coli in chickens at cellular level. Further studies are required to confirm if such responses are destructive or protective to set the means through which a chicken mounts a successful defense against avian pathogenic E. coli.

The importance of propolis in alleviating the negative physiological effects of heat stress in quail chicks

“…The failure of thermoregulation process in the HS group may be due to the exergonic reactions of free radicals that are generated by heat stress [ 53 ]. In addition, the effects of heat stress on circulating corticosterone and MDA levels in the present study are similar to that obtained in previous works on both broilers and quail [ 16 , 54 ]. These results demonstrate that heat stress induced inflammation and lipid peroxidation of the quail as previously reported [ 12 , 55 , 56 ].…”

“…These results demonstrate that heat stress induced inflammation and lipid peroxidation of the quail as previously reported [ 12 , 55 , 56 ]. The excessive amounts of corticosterone may induce the fever that observed in the HS group [ 16 ]. Furthermore, the decline in fT 3 concentrations upon heat exposure is consistent with the reduction in feed consumption of the same quail group in the present study.…”

“…On the other hand, it was observed that the exposure of quail to heat stress significantly increased the expression of CASP6 gene while it was normalized again after propolis supplementation. The CASP6 gene plays a central role in the execution-phase of cell apoptosis [ 69 ], and could be up-regulated as a result of the increased fever, corticosterone and MDA levels in the heat-stressed quail [ 16 ]. The protective effects of propolis and its components against the activation of the caspase cascade that leads to apoptosis and subsequent cell death were also reported in previous works on human cells [ 29 , 70 ].…”

Comprehensive growth performance, immune function, plasma biochemistry, gene expressions and cell death morphology responses to a daily corticosterone injection course in broiler chickens

“…At the same time, the massive meat production of broiler chickens make them continuously exposed to a wide range of potential stressors [ 1 ]. In our previous work [ 48 ], we found that endotoxin stress by E. coli infection to laying chickens markedly increased plasma corticosterone concentration by approximately 3 times more than normal chickens only 3 hr after E. coli injection. Such results and previous reports concluded that various forms of stress directly or indirectly activate the hypothalamic-pituitary-adrenal (HPA) axis and the release of corticosterone into blood [ 2 ].…”

Microcystin-leucine-arginine Modulates the Expression Patterns of Proinflammatory Cytokines and an Apoptotic Gene in Chicken Liver

“…Our results indicated that MC-LR did not significantly Mehaisen et al (2016) modulate the gene expression of caspase-3 and genes related to antioxidant activity. However, these genes tended to be upregulated in a dose-dependent manner after MC-LR exposure.…”