Study Of Expressional Regulation Of Several Inflammatory Response Related Genes Induced By LPS In Chicken

Chicken colibacillosis is one of major diseases in poultry industry, which can cause inflammatory responses in multiple tissues and organs from chicken of different strains and ages, and brings great economic losses to poultry industry. In this study, the expressional characteristics of inflammation-related genes, such as akirin2, PPARγ, NYGGF4 and microRNAs(miRNAs), were analyzed in Hi-Line Brown chicken, AA+ broiler chicken and adult laying hens after Escherichia coli lipopolysaccharide(LPS) treatment, which provided a theoretical references for further understanding of molecular mechanisms of inflammatory response and screening candidate genes as molecular markers of diagnostic inflammatory responses. The main research methods and results were as follows:In order to study the expressional characteristics and regulatory relationship of inflammation-related genes in chicken, AA+ broilers and Hi-Line Brown chickens were used as the research objects, and LPS was injected into the peritoneal cavity of chicken. The blood, liver, thymus gland, bursa and spleen were collected after 72 h. The transcriptional activity of inflammation related genes, such as akirin2, PPARγ, NYGGF4 and miRNAs, were analyzed using RT-PCR. The results showed that akirin2 and PPARγ were significantly down-regulated in livers and bursas of AA+ broilers injected with LPS(P<0.01). In Hi-Line Brown chicken injected with LPS, akirin2 gene(P<0.01) was significantly up-regulated in thymus, but the PPARγ gene was not significant in these tissues. Moreover, miR-146a(P<0.05), miR-21(P<0.01) and miR-155(P<0.01) were significantly down-regulated in chicken livers of the two strains.After LPS treatment, the expressional activities of miR-155, mi R-146 a, miR-181 a and miR-21 were down-regulated in Hi-Line Brown chicken red blood cells, but which showed the opposite trend in the AA+ broilers. In white blood cells, miR-155 and miR-21 were up-regulated in chickens of the two strains. In addition, miR-146 a and mi R-181 a were significantly decreased in the Hi-Line Brown chickens(P<0.05), but were significantly increased in the AA+ broilers(P<0.05). In plasma, miR-146 a and miR-181 a were all down-regulated in the chickens of the two strains(P<0.05).In order to further study the functions of NYGGF4 gene in chicken, the NYGGF4 genes from four strains were analyzed using bioinformatics method firstly. Then, the tissue expressional characteristics of NYGGF4 were analyzed. Lastly, the possible relationships between NYGGF4 and inflammation response were verified. The results showed that 8 SNPs existed in NYGGF4 coding sequences from chickens of the four strains. The expressional level of NYGGF4 gene was the highest in brains of 14 days old Hi-Line Brown chicken, and which was the highest in lungs and adipose tissues of 14 days old AA+ broiler, but the expressional characteristics were similar in the other tissues of the two strains. In the inflammatory response, the expressional activities of NYGGF4 gene showed the opposite changes in liver and bursa of the two strains.For further studying the molecular mechanisms of oviduct inflammatory in hens, acute inflammatory reaction of Hi-Line Brown adult hen cloaca ascending infection models were produced using LPS and the changes of inflammatory tissue-related genes transcriptional activity were analyzed. The results showed that akirin2 gene was abundantly expressed in the different section tissues of normal adult hen oviduct, but PPARγ gene was only expressed moderately in the vagina and ovary sections. In the inflammatory responses, the transcriptional activities of akirin2 gene in uterus, rectum and caecal tonsil were up-regulated significantly(P<0.01), and PPARγ gene was only up-regulated in uterus(P<0.01), but down-regulated in rectum and caecal tonsil significantly(P<0.01).The study shows that akirin2, PPARγ and NYGGF4 are important regulatory genes influencing inflammatory responses. Study the relationships between expression and regulation of these genes in the inflammatory response, has important theoretical significances for in-depth understanding the molecular mechanisms of inflammatory responses. In addition, some miRNAs show significantly changes in fluid circulation during inflammatory response, which may become one of the main target genes of molecular markers of diagnostic inflammation.