Novel models for chronic intestinal inflammation in chickens: Intestinal inflammation pattern and biomarkers

Authors: DAL PONT, GABRIELA - Texas A&M University; BELOTE, BRUNA - Federal University Of Paraná; LEE, ANNAH - Texas A&M University; BORTOLUZZI, CRISTIANO - Texas A&M University; EYNG, CINTHIA - Western Paraná State University; SEVASTIYANOVA, MILENA - Innovad Nv/sa; KHADEM, ALIREZA - Innovad Nv/sa; SANTIN, ELIZABETH - Federal University Of Paraná; FARNELL, YUHUA - Texas A&M University; GOUGOULIAS, CHRISTOS - Innovad Nv/sa; Kogut, Michael - Mike

Submitted to: Frontiers in Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2021
Publication Date: 5/12/2021
Citation: Dal Pont, G.C., Belote, B.L., Lee, A., Bortoluzzi, C., Eyng, C., Sevastiyanova, M., Khadem, A., Santin, E., Farnell, Y.Z., Gougoulias, C., Kogut, M.H. 2021. Novel models for chronic intestinal inflammation in chickens: Intestinal inflammation pattern and biomarkers. Frontiers in Immunology. 12. Article 676628. https://doi.org/10.3389/fimmu.2021.676628.
DOI: https://doi.org/10.3389/fimmu.2021.676628

Interpretive Summary: Until recently, poultry producers have relied on antibiotics to compensate for potential poor husbandry and management issues. However, with the removal of growth-promoting antimicrobials in poultry feed, intestinal inflammation has become more of an issue worldwide. For the poultry producer, chronic low-grade intestinal inflammation has a negative impact on the productivity of the poultry operation by impairing the ability of the birds to absorb nutrients and reaching 100% of their growth and genetic potential. Although chronic intestinal inflammation can be induced by a number of environmental factors, diet is the main cause since some feed ingredients, such as soybean meal, are potent stimulators of the intestinal immune response. Research into understanding and regulating intestinal inflammation in poultry has been limited by two factors: the development of a dependable in vivo model and the identification of non-invasive biomarkers. The results in this paper, for the first time, have characterized two in vivo models of chronic gut inflammation and identified novel inflammation-specific molecules present in the serum and feces that indicate an ongoing inflammatory response. The models will allow studies into methods of controlling inflammation while the biomarkers will allow for in-the-field diagnosis of inflammation in intensive poultry farming.

Technical Abstract: For poultry producers, chronic low-grade intestinal inflammation has a negative impact on productivity by impairing nutrient absorption and allocation of nutrients for growth. Understanding the triggers of chronic intestinal inflammation and developing a noninvasive measurement is crucial to managing gut health in poultry. In this study, we developed two novel models of low-grade chronic intestinal inflammation in broiler chickens: a chemical model using dextran sodium sulfate (DSS) and a dietary model using a high non-starch polysaccharide diet (NSP). Further, we evaluated the potential of several proteins as biomarkers of gut inflammation. For these experiments, the chemical induction of inflammation consisted of two 5-day cycles of oral gavage of either 0.25mg DSS/ml or 0.35mg DSS/ml; whereas the NSP diet (30% rice bran) was fed throughout the experiment. At four times (14, 22, 28 and 36-d post-hatch), necropsies were performed to collect intestinal samples for histology, and feces and serum for biomarkers quantification. Neither DSS nor NSP treatments affected feed intake or livability. NSP-fed birds exhibited intestinal inflammation through 14-d, which stabilized by 36-d. On the other hand, the cyclic DSS-treatment produced inflammation throughout the entire experimental period. Histological examination of the intestine revealed that the inflammation induced by both models exhibited similar spatial and temporal patterns with the duodenum and jejunum affected early (at 14-d) whereas the ileum was compromised by 28-d. Calprotectin (CALP) was the only serum protein found to be increased due to inflammation. However, fecal CALP and Lipocalin-2 (LCN-2) concentrations were significantly greater in the induced inflammation groups at 28-d. This experiment demonstrated for the first time, two in vivo models of chronic gut inflammation in chickens, a DSS and a nutritional NSP protocols. Based on these models we observed that intestinal inflammation begins in the upper segments of small intestine and moved to the lower region over time. In the searching for a fecal biomarker for intestinal inflammation, LCN-2 showed promising results. More importantly, calprotectin has a great potential as a novel biomarker for poultry measured both in serum and feces.