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Transcriptional Profiling Analysis of Host response to Clostridium perfringens Infection in Broilers

ABSTRACT: Necrotic enteritis is a disease caused by Clostridium perfringens, which threatens poultry production in the absence of dietary antibiotics. A total number of 144 Ross broilers were reared in 12 pens with each hosting 12 birds. Each 6 pens of birds were fed medicated (bacitracin at 55 ppm) or non-medicated starter diets (Nutreco Canada Agresearch) immediately after the chicks were placed. At day 18, birds were challenged with C. perfringens (107 cfu per ml mixed with feed). Spleens were collected from 12 birds of each group at day 18 (before infection), 19, 20, and 22. A low-density chicken immune microarray was used to study gene expression profiling of host response to C. perfringens infection. Six biological replicates (2 birds per biological replicate) for each treatment group were labeled with either Cy5 or Cy3 with dye swap. A total of 24 arrays were used for this study. Gene signal intensity was globally normalized by LOWESS and expressed as log2 ratios. A mixed model including treatment, time, array, subgrid (random effect), dye, and all interactions among treatment and time was used to identify differentially expressed genes between post-infection vs. pre-infection, among post-infections, and between medication treatments, at the 5% significance level. The results indicated subtle medication effects on gene expression of these immune-related genes compared to bacterial infection effect. Our findings strongly suggest that both cell-mediated and antibody-mediated immune responses via MHC class I and II systems were actively involved in the host defense against C. perfringens infection in broilers. The unique cytokine signaling pathway and apoptosis cascade found in the study provide a new insight of molecular regulation of host immune response. Collectively, the findings of the present study will shed light on the molecular mechanisms underlying C. perfringens infection in broilers.

ORGANISM(S): Gallus gallus

PROVIDER: GSE13085 | GEO | 2009/03/01

SECONDARY ACCESSION(S): PRJNA110913

REPOSITORIES: GEO

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Project description:Necrotic enteritis is a disease caused by Clostridium perfringens, which threatens poultry production in the absence of dietary antibiotics. A total number of 144 Ross broilers were reared in 12 pens with each hosting 12 birds. Each 6 pens of birds were fed medicated (bacitracin at 55 ppm) or non-medicated starter diets (Nutreco Canada Agresearch) immediately after the chicks were placed. At day 18, birds were challenged with C. perfringens (107 cfu per ml mixed with feed). Spleens were collected from 12 birds of each group at day 18 (before infection), 19, 20, and 22. A low-density chicken immune microarray was used to study gene expression profiling of host response to C. perfringens infection. Six biological replicates (2 birds per biological replicate) for each treatment group were labeled with either Cy5 or Cy3 with dye swap. A total of 24 arrays were used for this study. Gene signal intensity was globally normalized by LOWESS and expressed as log2 ratios. A mixed model including treatment, time, array, subgrid (random effect), dye, and all interactions among treatment and time was used to identify differentially expressed genes between post-infection vs. pre-infection, among post-infections, and between medication treatments, at the 5% significance level. The results indicated subtle medication effects on gene expression of these immune-related genes compared to bacterial infection effect. Our findings strongly suggest that both cell-mediated and antibody-mediated immune responses via MHC class I and II systems were actively involved in the host defense against C. perfringens infection in broilers. The unique cytokine signaling pathway and apoptosis cascade found in the study provide a new insight of molecular regulation of host immune response. Collectively, the findings of the present study will shed light on the molecular mechanisms underlying C. perfringens infection in broilers. There were two groups: medicated and non-medicated. Spleen were collected to isolate total RNA for gene expression profiling.For the microarray study, two birds from each pen were pooled within each group. To account for any bias inherent to the fluorescent dyes, three of the six medicated replicates were labeled with Cy3 and the other three were labeled with Cy5 at each time point. The same design was applied for the non-medicated group. There were six hybridizations between medicated and non-medicated replicates at each time point. Twenty-three out of 24 arrays were used (data from one array were discarded due to poor quality).

Project description:Purpose: This study is to more comprehensively understand the genome-wide host response to avian pathogen E. coli (APEC). Methods: Male broiler chicks were challenged with APEC (or mock-challenged as controls), and bone marrow was harvested at 1 and 5 days post-infection (dpi). Based upon necropsy-scored lesions on liver, pericardium, and air sacs, the challenged birds were assigned to mild or severe pathology categories, representing resistant and susceptible phenotypes, respectively. RNA sequence data were first analyzed using the R package EdgeR to identify differentially expressed genes.GO and pathway analysis using the R package GOseq identified many immune-related pathways. Results: RNA sequencing resulted in 11 to 40 million single-end raw reads of 100 bp per sample. After alignment, an average of 80 % of the reads, with 5 % representing multiple mapping, were mapped to the chicken reference transcriptome. Among these detected unique transcripts, there were 2,404 novel genes mainly distributed on chromosomes 1, 2, 4, 3, Z, 5 in decreasing number. Genes were detected as differentially expressed (DE) between treatments (susceptible, resistant, and mock-challenged) at a given time point, or DE between 1 and 5 dpi within the same treatment group. Compared to mock-challenged birds on 5 dpi, susceptible birds exhibited extensive enhancement of their T cell and B cell development, as well as innate and adaptive immune response. However, for the 1 dpi group, susceptible birds exhibited a decreased gene expression of T and B cell development. The differences between the two phenotypes, susceptible and resistant birds, at 5 dpi showed that susceptible birds had increased gene expression of B-cell development and adaptive immune response. Conclusions: This is the first report to our knowledge examining the role of bone marrow cells in responding to APEC infection in broilers. This transcriptome study provides insight and global overview into the response of genes involved in the earliest phases of the immune response to APEC infection. Our data indicate a dynamic interaction between the innate and adaptive immune responses to APEC infection in susceptible birds, providing flexibility and redundancy in the host’s induction of cytokines and chemokines. Additionally, B cell and T cell development are also extensively affected by APEC infection for susceptible birds, resulting in drastic host impairment in early response to infection. The findings of present study shed light on the underlying chicken immune modulation against APEC infection. Also, this study will build a solid foundation for identifying host genetic variation that may be manipulated to enhance resistance to infection and may be useful as colibacillosis control targets.

Project description:There are currently no biological tests that differentiate patients with bipolar disorder (BPD) from healthy controls. While there is evidence that peripheral gene expression differences between patients and controls can be utilized as biomarkers for psychiatric illness, it is unclear whether current use or residual effects of antipsychotic and mood stabilizer medication drives much of the differential transcription. We therefore tested whether expression changes in first-episode, never-medicated bipolar patients, can contribute to a biological classifier that is less influenced by medication and could potentially form a practicable biomarker assay for BPD. We employed microarray technology to measure global leukocyte gene expression in first-episode (n=3) and currently medicated BPD patients (n=26), and matched healthy controls (n=25). Following an initial feature selection of the microarray data, we developed a cross-validated 10-gene model that was able to correctly predict the diagnostic group of the training sample (26 medicated patients and 12 controls), with 89% sensitivity and 75% specificity (p<0.001). The 10-gene predictor was further explored via testing on an independent test cohort consisting of three pairs of monozygotic twins discordant for BPD, plus the original enrichment sample cohort (the three never-medicated BPD patients and 13 matched control subjects), and a sample of experimental replicates (n=34). 83% of the independent test sample was correctly predicted, with a sensitivity of 67% and specificity of 100% (although this result did not reach statistical significance). Additionally, 88% of sample diagnostic classes were classified correctly for both the enrichment (p=0.015) and the replicate samples (p<0.001). Peripheral blood leukocytes (PBLs) from whole blood were collected from 26 patients with bipolar disorder who had previously received medication, three patients with bipolar disorder who were experiencing their first hospitalization and had not previously received medication, and 25 matched control subjects, for RNA extraction and hybridization on Affymetrix microarrays. Immediately after blood collection, blood samples were split into two (when a sufficient volume had been collected); an "1" and replicate "2" sample (thus two separate RNA extractions, cDNA and cRNA syntheses and array hybridizations were performed).

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Transcriptional Profiling Analysis of Host response to Clostridium perfringens Infection in Broilers

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