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Characterization of Serum Profile and Innate Immunity Biomarkers During Enteric Inflammation in Broiler Chickens

Duff, Audrey Faye
http://rave.ohiolink.edu/etdc/view?acc_num=osu1638387446799047

Abstract Details

2021, Doctor of Philosophy, Ohio State University, Animal Sciences.
Inflammation primarily functions to control microbial infection, tissue damage and mediate tissue repair but is energetically costly. Chronic inflammation in poultry can result in suppressed health and performance parameters including growth, feed intake, and worsened feed conversion ratio. Ten experiments were conducted to describe new methods for the characterization of inflammation in the gastrointestinal tract (GIT) of poultry to further explicate GIT immune responses and potentially elucidate therapeutic or prophylactic targets. In tissue, proinflammatory stimuli are detected by receptors on various leukocytes which induces cell activation, proinflammatory cascades, and secretion of acute phase proteins into the bloodstream. Three experiments were conducted to evaluate total serum protein (TP), serum protein electrophoresis (SPE), and immunofluorescent (IF) staining of CD205+ dendritic cell (DC) for effects of in ovo inoculations with Citrobacter freundii (CF) or mixed lactic acid bacteria (LAB) on serum protein profiles and migration of intestinal DC populations. In ovo inoculations were administered into the amnion of fertile eggs on embryonic d18, body weights (BW) were recorded on day of hatch (DOH) and d10 to calculate body weight gain (BWG), and serum and ileal samples were collected on d10. All TP and SPE data were statistically analyzed relative to a control group. A lack of significant differences in BWG across experiments implied that only mild, low-level inflammation was induced by bacterial inoculums. However, in ovo bacteria influenced β serum fractions (p < 0.05 or = 0.07) in all experiments. Significant fluctuations within the β fraction indicate corresponding β fraction acute phase proteins may be useful markers in assessing bacterial infection. No CD205+ DC were detected in ileal samples which suggested that DC are not present or undetectable in this region in young chickens at 10 days. A lack of significant differences in other SPE fractions may substantiate claims of non-chronic inflammation and a shift towards a more tolerogenic response to in ovo inoculums by 10 days of age and IF results undermine the role and prevalence of intestinal CD205+ DC at this time. In subsequent experiments, a previously described heterophil degranulation assay was adapted for use in ileal mucosal tissue via quantification of granule component β-D-glucuronidase and assay end product 4-methylumbelliferone (4-MU). Initially, in ovo bacterial inoculations were administered on embryonic d18. BWG was assessed between DOH and d10, and ileal mucosal scrapings were collected on DOH or d10 for the 4-MU assay. All treatments were statistically analyzed relative to a non-inoculated control group. Treatments minimally affected BWG in all in ovo experiments (p > 0.05). Similarly, ileal degranulation of in ovo treatments did not statistically differ (p > 0.05). Based on BWG, again, there may have been only low-level inflammation outside detectable limits of the 4-MU assay. The next set of experiments tested the effect of Eimeria maxima (EM) inoculation on ileal degranulation. Treatments included non-inoculated controls and low, medium, or high EM infection. Across all four experiments, final BW or BWG over the inoculation period and were suppressed (p < 0.05) in all EM groups relative to respective control with the exception of EM-low (p = 0.094) and EM-medium (p = 0.096) in one trial. Ileal mucosal scrapings were collected on day of peak lesions for the 4-MU assay in all experiments. Resulting values were significantly reduced (p < 0.05) for EM treated birds in three experiments with the exception of EM-medium (p = 0.247). No differences were observed in one experiment (p = 0.351), which may be attributed to a variation in the strain of infecting Eimeria. Although refinement for low level inflammation is warranted, results indicate a successful adaptation of the 4-MU assay for use with intestinal tissue during significant GIT inflammation, thus providing a site-specific, real-time evaluation of granulocyte degranulation. These results emphasize the differential impact of select microorganisms on the severity of the innate inflammatory response in broilers as measured by select performance parameters and novel assays. Collectively, these experiments demonstrated the potential of SPE to identify serum protein fractions influenced by pioneer colonization while highlighting limitations associated with identification of cumulative acute phase protein changes at a single timepoint, corroborated a lack of CD205+ DC in lower ileal tissue at 10 days of age, and verified the successful adaptation of a site-specific granulocyte degranulation assay in intestinal tissue.
Lisa Bielke (Advisor)
Benjamin Enger (Committee Member)
Thaddeus Ezeji (Committee Member)
Ramesh Selvaraj (Committee Member)
226 p.
Animal Sciences
chickens; inflammation; intestinal health; serum protein electrophoresis; CD205; dendritic cells; degranulation

Recommended Citations

Citations

  • Duff, A. F. (2021). Characterization of Serum Profile and Innate Immunity Biomarkers During Enteric Inflammation in Broiler Chickens [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1638387446799047

    APA Style (7th edition)

  • Duff, Audrey. Characterization of Serum Profile and Innate Immunity Biomarkers During Enteric Inflammation in Broiler Chickens. 2021. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1638387446799047.

    MLA Style (8th edition)

  • Duff, Audrey. "Characterization of Serum Profile and Innate Immunity Biomarkers During Enteric Inflammation in Broiler Chickens." Doctoral dissertation, Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1638387446799047

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.