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Medley BJ, Low KE, Irungu JDW, Kipchumba L, Daneshgar P, Liu L, Garber JM, Klassen L, Inglis GD, Boons GJ, Zandberg WF, Abbott DW, Boraston AB. A "terminal" case of glycan catabolism: Structural and enzymatic characterization of the sialidases of Clostridium perfringens. J Biol Chem 2024; 300:107750. [PMID: 39251137 PMCID: PMC11525138 DOI: 10.1016/j.jbc.2024.107750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2024] [Revised: 08/28/2024] [Accepted: 08/29/2024] [Indexed: 09/11/2024] Open
Abstract
Sialic acids are commonly found on the terminal ends of biologically important carbohydrates, including intestinal mucin O-linked glycans. Pathogens such as Clostridium perfringens, the causative agent of necrotic enteritis in poultry and humans, have the ability to degrade host mucins and colonize the mucus layer, which involves removal of the terminal sialic acid by carbohydrate-active enzymes (CAZymes). Here, we present the structural and biochemical characterization of the GH33 catalytic domains of the three sialidases of C. perfringens and probe their substrate specificity. The catalytically active domains, which we refer to as NanHGH33, NanJGH33, and NanIGH33, displayed differential activity on various naturally occurring forms of sialic acid. We report the X-ray crystal structures of these domains in complex with relevant sialic acid variants revealing the molecular basis of how each catalytic domain accommodates different sialic acids. NanHGH33 displays a distinct preference for α-2,3-linked sialic acid, but can process α-2,6-linked sialic acid. NanJGH33 and NanIGH33 both exhibit the ability to process α-2,3- and α-2,6-linked sialic acid without any significant apparent preference. All three enzymes were sensitive to generic and commercially available sialidase inhibitors, which impeded sialidase activity in cultures as well as the growth of C. perfringens on sialylated glycans. The knowledge gained in these studies can be applied to in vivo models for C. perfringens growth and metabolism of mucin O-glycans, with a view toward future mitigation of bacterial colonization and infection of intestinal tissues.
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Lange ME, Bescucci DM, Boras VF, Montina T, Inglis GD. Assessment of the piroxicam-incited model of synchronized colitis in T-cell receptor alpha chain-deficient mice. Animal Model Exp Med 2024; 7:533-543. [PMID: 38992956 PMCID: PMC11369028 DOI: 10.1002/ame2.12456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Accepted: 05/23/2024] [Indexed: 07/13/2024] Open
Abstract
BACKGROUND A multitude of mouse models are utilized to emulate and study intestinal inflammation. T-cell receptor alpha chain (TCRα)-deficient mice are used as a model of spontaneous colitis that has similarities with human ulcerative colitis. However, colitis is triggered late in the life of the mouse (age: 4-5 months), and inflammation does not develop at the same time in different mice. A previously conducted study reported that the administration of the drug piroxicam triggered predictable and early colitis in TCRα-deficient mice at the age of 6-8 weeks. However, a detailed characterization of ensuing inflammation was not provided. METHODS We conducted an in-depth examination of piroxicam-triggered colitis in TCRα-deficient mice, with emphasis on spatial histopathologic changes and analysis of expression of inflammatory markers. Furthermore, we tested amelioration of colitis with dexamethasone. RESULTS We confirmed that piroxicam induced a time-prescribed colitis and did so in the proximal colon as well as the cecum of TCRα-deficient mice. Piroxicam administration was observed to induce epithelial hyperplasia, goblet cell loss, and leukocyte infiltration with occasional ulceration. A Swiss roll technique was used to examine the colon and cecum in its entirety. Importantly, we observed that inflammation was multifocal segmental, with areas of tissue damage in between healthy tissue. In addition, we observed variability in the severity of inflammation among replicate animals and treatments, and that the administration of dexamethasone only partially ameliorated inflammation in the proximal colon. CONCLUSIONS Piroxicam consistently induced multifocal segmental colitis in the proximal colon and cecum, although the degree of inflammation was reduced in the latter. Importantly, spatial variability in inflammation in the large intestine and the inter-replicate variation in the severity of inflammation must be taken into consideration when utilizing this murine model of synchronized colitis.
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Lange ME, Clarke ST, Boras VF, Brown CLJ, Zhang G, Laing CR, Uwiera RRE, Montina T, Kalmokoff ML, Taboada EN, Gannon VPJ, Metz GAS, Church JS, Inglis GD. Commensal Escherichia coli Strains of Bovine Origin Competitively Mitigated Escherichia coli O157:H7 in a Gnotobiotic Murine Intestinal Colonization Model with or without Physiological Stress. Animals (Basel) 2023; 13:2577. [PMID: 37627368 PMCID: PMC10451813 DOI: 10.3390/ani13162577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 08/04/2023] [Accepted: 08/07/2023] [Indexed: 08/27/2023] Open
Abstract
Cattle are a primary reservoir of enterohemorrhagic Escherichia coli (EHEC) O157:H7. Currently, there are no effective methods of eliminating this important zoonotic pathogen from cattle, and colonization resistance in relation to EHEC O157:H7 in cattle is poorly understood. We developed a gnotobiotic EHEC O157:H7 murine model to examine aspects of the cattle pathogen-microbiota interaction, and to investigate competitive suppression of EHEC O157:H7 by 18 phylogenetically distinct commensal E. coli strains of bovine origin. As stress has been suggested to influence enteric colonization by EHEC O157:H7 in cattle, corticosterone administration (±) to incite a physiological stress response was included as an experimental variable. Colonization of the intestinal tract (IT) of mice by the bovine EHEC O157:H7 strain, FRIK-2001, mimicked characteristics of bovine IT colonization. In this regard, FRIK-2001 successfully colonized the IT and temporally incited minimal impacts on the host relative to other EHEC O157:H7 strains, including on the renal metabolome. The presence of the commensal E. coli strains decreased EHEC O157:H7 densities in the cecum, proximal colon, and distal colon. Moreover, histopathologic changes and inflammation markers were reduced in the distal colon of mice inoculated with commensal E. coli strains (both propagated separately and communally). Although stress induction affected the behavior of mice, it did not influence EHEC O157:H7 densities or disease. These findings support the use of a gnotobiotic murine model of enteric bovine EHEC O157:H7 colonization to better understand pathogen-host-microbiota interactions toward the development of effective on-farm mitigations for EHEC O157:H7 in cattle, including the identification of bacteria capable of competitively colonizing the IT.
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Uddin MS, Guluarte JO, Abbott DW, Inglis GD, Guan LL, Alexander TW. Development of a spore-based mucosal vaccine against the bovine respiratory pathogen Mannheimia haemolytica. Sci Rep 2023; 13:12981. [PMID: 37563163 PMCID: PMC10415371 DOI: 10.1038/s41598-023-29732-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 02/09/2023] [Indexed: 08/12/2023] Open
Abstract
Bovine respiratory disease (BRD) is a significant health issue in the North American feedlot industry, causing substantial financial losses due to morbidity and mortality. A lack of effective vaccines against BRD pathogens has resulted in antibiotics primarily being used for BRD prevention. The aim of this study was to develop a mucosal vaccine against the BRD pathogen, Mannheimia haemolytica, using Bacillus subtilis spores as an adjuvant. A chimeric protein (MhCP) containing a tandem repeat of neutralizing epitopes from M. haemolytica leukotoxin A (NLKT) and outer membrane protein PlpE was expressed to produce antigen for adsorption to B. subtilis spores. Adsorption was optimized by comparing varying amounts of antigen and spores, as well as different buffer pH and reaction temperatures. Using the optimal adsorption parameters, spore-bound antigen (Spore-MhCP) was prepared and administered to mice via two mucosal routes (intranasal and intragastric), while intramuscular administration of free MhCP and unvaccinated mice were used as positive and negative control treatments, respectively. Intramuscular administration of MhCP elicited the strongest serum IgG response. However, intranasal immunization of Spore-MhCP generated the best secretory IgA-specific response against both PlpE and NLKT in all samples evaluated (bronchoalveolar lavage, saliva, and feces). Since proliferation of M. haemolytica in the respiratory tract is a prerequisite to lung infection, this spore-based vaccine may offer protection in cattle by limiting colonization and subsequent infection, and Spore-MhCP warrants further evaluation in cattle as a mucosal vaccine against M. haemolytica.
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Hodak CR, Bescucci DM, Shamash K, Kelly LC, Montina T, Savage PB, Inglis GD. Antimicrobial Growth Promoters Altered the Function but Not the Structure of Enteric Bacterial Communities in Broiler Chicks ± Microbiota Transplantation. Animals (Basel) 2023; 13:ani13060997. [PMID: 36978538 PMCID: PMC10044420 DOI: 10.3390/ani13060997] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 02/28/2023] [Accepted: 03/06/2023] [Indexed: 03/12/2023] Open
Abstract
Non-antibiotic alternatives to antimicrobial growth promoters (AGPs) are required, and understanding the mode of action of AGPs may facilitate the development of effective alternatives. The temporal impact of the conventional antibiotic AGP, virginiamycin, and an AGP alternative, ceragenin (CSA-44), on the structure and function of the broiler chicken cecal microbiota was determined using next-generation sequencing and 1H-nuclear magnetic resonance spectroscopy (NMR)-based metabolomics. To elucidate the impact of enteric bacterial diversity, oral transplantation (±) of cecal digesta into 1-day-old chicks was conducted. Microbiota transplantation resulted in the establishment of a highly diverse cecal microbiota in recipient chicks that did not change between day 10 and day 15 post-hatch. Neither virginiamycin nor CSA-44 influenced feed consumption, weight gain, or feed conversion ratio, and did not affect the structure of the cecal microbiota in chicks possessing a low or high diversity enteric microbiota. However, metabolomic analysis of the cecal contents showed that the metabolome of cecal digesta was affected in birds administered virginiamycin and CSA-44 as a function of bacterial community diversity. As revealed by metabolomics, glycolysis-related metabolites and amino acid synthesis pathways were impacted by virginiamycin and CSA-44. Thus, the administration of AGPs did not influence bacterial community structure but did alter the function of enteric bacterial communities. Hence, alterations to the functioning of the enteric microbiota in chickens may be the mechanism by which AGPs impart beneficial health benefits, and this possibility should be examined in future research.
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Brown CLJ, Zaytsoff SJM, Iwaniuk AN, Metz GAS, Montina T, Inglis GD. Comparative Analysis of the Temporal Impacts of Corticosterone and Simulated Production Stressors on the Metabolome of Broiler Chickens. Metabolites 2023; 13:metabo13020144. [PMID: 36837763 PMCID: PMC9961940 DOI: 10.3390/metabo13020144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 12/13/2022] [Accepted: 12/14/2022] [Indexed: 01/20/2023] Open
Abstract
The impact of physiological stress on the metabolome of breast muscle, liver, kidney, and hippocampus was investigated in Ross 308 broiler chicks. Simulated on-farm stressors were compared to a corticosterone model of physiological stress. The three different stressors investigated were: (i) corticosterone at a dose of 15 mg/kg of feed; (ii) heat treatment of 36 °C and 40% RH for 8 h per day; and (iii) isolation for 1 h per day. Liver, kidney, breast muscle, and hippocampus samples were taken after 2, 4, 6, and 8 days of stress treatment, and subjected to untargeted 1H-nuclear magnetic resonance (NMR) spectroscopy-based metabolomic analysis to provide insights on how stress can modulate metabolite profiles and biomarker discovery. Many of the metabolites that were significantly altered in tissues were amino acids, with glycine and alanine showing promise as candidate biomarkers of stress. Corticosterone was shown to significantly alter alanine, aspartate, and glutamate metabolism in the liver, breast, and hippocampus, while isolation altered the same pathways, but only in the kidneys and hippocampus. Isolation also significantly altered the glycine, serine, and threonine metabolism pathway in the liver and breast, while the same pathway was significantly altered by heat in the liver, kidneys, and hippocampus. The study's findings support corticosterone as a model of stress. Moreover, a number of potential metabolite biomarkers were identified in chicken tissues, which may allow producers to effectively monitor stress and to objectively develop and evaluate on-farm mitigations, including practices that reduce stress and enhance bird health.
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Teixeira JS, Boras VF, Hetman BM, Taboada EN, Inglis GD. Molecular Epidemiological Evidence Implicates Cattle as a Primary Reservoir of Campylobacter jejuni Infecting People via Contaminated Chickens. Pathogens 2022; 11:1366. [PMID: 36422616 PMCID: PMC9698452 DOI: 10.3390/pathogens11111366] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 09/10/2024] Open
Abstract
The study aimed to determine the relative contribution of cattle to the burden of illness in a model agroecosystem with high rates of human campylobacteriosis (≥ 115 cases/100 K), and high densities of cattle, including large numbers of cattle housed in confined feeding operations (i.e., in southwestern Alberta, Canada). To accomplish this, a large-scale molecular epidemiological analysis of Campylobacter jejuni circulating within the study location was completed. In excess of 8000 isolates of C. jejuni from people (n = 2548 isolates), chickens (n = 1849 isolates), cattle (n = 2921 isolates), and water (n = 771 isolates) were subtyped. In contrast to previous studies, the source attribution estimates of clinical cases attributable to cattle vastly exceeded those attributed to chicken (i.e., three- to six-fold). Moreover, cattle were often colonized by C. jejuni (51%) and shed the bacterium in their feces. A large proportion of study isolates were found in subtypes primarily associated with cattle (46%), including subtypes infecting people and those associated with chickens (19%). The implication of cattle as a primary amplifying reservoir of C. jejuni subtypes in circulation in the study location is supported by the strong cattle association with subtypes that were found in chickens and in people, a lack of evidence indicating the foodborne transmission of C. jejuni from beef and dairy, and the large number of cattle and the substantial quantities of untreated manure containing C. jejuni cells. Importantly, the evidence implicated cattle as a source of C. jejuni infecting people through a transmission pathway from cattle to people via the consumption of chicken. This has implications for reducing the burden of campylobacteriosis in the study location and elsewhere.
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Zaytsoff SJM, Montina T, Boras VF, Brassard J, Moote PE, Uwiera RRE, Inglis GD. Microbiota Transplantation in Day-Old Broiler Chickens Ameliorates Necrotic Enteritis via Modulation of the Intestinal Microbiota and Host Immune Responses. Pathogens 2022; 11:pathogens11090972. [PMID: 36145404 PMCID: PMC9503007 DOI: 10.3390/pathogens11090972] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 08/22/2022] [Accepted: 08/24/2022] [Indexed: 11/16/2022] Open
Abstract
A microbiota transplant (MT) originating from mature adult chicken ceca and propagated in bioreactors was administered to day-old broiler chicks to ascertain the degree to which, and how, the MT affects Clostridium perfringens (Cp)-incited necrotic enteritis (NE). Using a stress predisposition model of NE, birds administered the MT and challenged with Cp showed fewer necrotic lesions, and exhibited a substantially higher α- and β-diversity of bacteria in their jejunum and ceca. Birds challenged with Cp and not administered the MT showed decreased Lactobacillus and increased Clostridium sensu strico 1 in the jejunum. In ceca, Megamonas, a genus containing butyrate-producing bacteria, was only present in birds administered the MT, and densities of this genus were increased in birds challenged with Cp. Metabolite profiles in cecal digesta were altered in birds administered the MT and challenged with the pathogen; 59 metabolites were differentially abundant following MT treatment, and the relative levels of short chain fatty acids, butyrate, valerate, and propionate, were decreased in birds with NE. Birds administered the MT and challenged with Cp showed evidence of enhanced restoration of intestinal barrier functions, including elevated mRNA of MUC2B, MUC13, and TJP1. Likewise, birds administered the MT exhibited higher mRNA of IL2, IL17A, and IL22 at 2-days post-inoculation with Cp, indicating that these birds were better immunologically equipped to respond to pathogen challenge. Collectively, study findings demonstrated that administering a MT containing a diverse mixture of microorganisms to day-old birds ameliorated NE in broilers by increasing bacterial diversity and promoting positive immune responses.
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Lange ME, Uwiera RRE, Inglis GD. Enteric Escherichia coli O157:H7 in Cattle, and the Use of Mice as a Model to Elucidate Key Aspects of the Host-Pathogen-Microbiota Interaction: A Review. Front Vet Sci 2022; 9:937866. [PMID: 35898542 PMCID: PMC9310005 DOI: 10.3389/fvets.2022.937866] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 06/02/2022] [Indexed: 11/24/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is responsible for foodborne disease outbreaks, typically associated with the consumption of undercooked foods contaminated with cattle manure containing the bacterium. At present, effective mitigations do not exist. Many of the factors regulating enteric colonization by E. coli O157:H7 in cattle, and how cattle respond to the bacterium are unknown. In this regard, intestinal colonization locations, shedding patterns, interactions with the enteric microbiota, and host immune responses to infection are current knowledge gaps. As disturbances to host homeostasis are believed to play an important role in the enteric survival of the bacterium, it is important to consider the potential importance of stress during cattle production. Husbandry logistics, cost, and the high genetic, physiological, and microbial heterogeneity in cattle has greatly hampered the ability of researchers to elucidate key aspects of the host-pathogen-microbiota interaction. Although mice have not been extensively used as a cattle model, the utilization of murine models has the potential to identify mechanisms to facilitate hypothesis formulation and efficacy testing in cattle. Murine models have been effectively used to mechanistically examine colonization of the intestine, host responses to infection, and to interactively ascertain how host physiological status (e.g., due to physiological stress) and the enteric microbiota influences colonization and disease. In addition to reviewing the relevant literature on intestinal colonization and pathogenesis, including existing knowledge gaps, the review provides information on how murine models can be used to elucidate mechanisms toward the development of rationale-based mitigations for E. coli O157:H7 in cattle.
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Brown CL, Montina T, Inglis GD. Feather pulp: a novel substrate useful for proton nuclear magnetic resonance spectroscopy metabolomics and biomarker discovery. Poult Sci 2022; 101:101866. [PMID: 35679673 PMCID: PMC9189206 DOI: 10.1016/j.psj.2022.101866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 03/09/2022] [Accepted: 03/13/2022] [Indexed: 11/30/2022] Open
Abstract
Noninvasive biomarkers of stress that are predictive of poultry health are needed. Feather pulp is highly vascularized and represents a potential source of biomarkers that has not been extensively explored. We investigated the feasibility and use of feather pulp for novel biomarker discovery using 1H-Nuclear Magnetic Resonance Spectroscopy (NMR)-based metabolomics. To this end, high quality NMR metabolomic spectra were obtained from chicken feather pulp extracted using either ultrafiltration (UF) or Bligh-Dyer methanol-chloroform (BD) methods. In total, 121 and 160 metabolites were identified using the UF and BD extraction methods, respectively, with 71 of these common to both methods. The metabolome of feather pulp differed in broiler breeders that were 1-, 23-, and 45-wk-of-age. Moreover, feather pulp was more difficult to obtain from older birds, indicating that age must be considered when targeting feather pulp as a source of biomarkers. The metabolomic profile of feather pulp obtained from 12-day-old broilers administered corticosterone differed from control birds, indicating that the metabolome of feather pulp was sensitive to induced physiological stress. A comparative examination of feather pulp and serum in broilers revealed that the feather pulp metabolome differed from that of serum but provided more information. The study findings show that metabolite biomarkers in chicken feather pulp may allow producers to effectively monitor stress, and to objectively develop and evaluate on-farm mitigations, including practices that reduce stress and enhance bird health.
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Zaytsoff SJM, Boras VF, Uwiera RRE, Inglis GD. A stress-induced model of acute necrotic enteritis in broiler chickens using dietary corticosterone administration. Poult Sci 2022; 101:101726. [PMID: 35202894 PMCID: PMC8866091 DOI: 10.1016/j.psj.2022.101726] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/06/2022] [Accepted: 01/08/2022] [Indexed: 12/29/2022] Open
Abstract
Mounting evidence indicates that stress can predispose chickens to disease. The objective of the current study was to develop a method that utilized physiological stress to predispose Ross 308 broiler chickens to acute necrotic enteritis (NE). Stress was mediated through the administration of the stress hormone, corticosterone. At 11 d posthatch (p.h.), corticosterone (20 mg kg−1) administration commenced. At 12 and 13 d p.h., birds were orally inoculated with a virulent strain of Clostridium perfringens, and at 14 d p.h., birds were euthanized. Birds administered corticosterone exhibited decreased weight gain, and birds co-challenged with C. perfringens and corticosterone were affected to a higher degree. Necrotic lesions were present in birds inoculated with C. perfringens (33%), but a substantially higher prevalence of birds treated with C. perfringens and corticosterone in combination exhibited lesions (100%). Clostridium perfringens densities were correlated with necrotic lesion and histopathologic scores. Both C. perfringens and corticosterone challenge altered mRNA immune responses in the small intestine. In this regard, birds infected with the pathogen showed higher relative mRNA concentrations of toll-like receptor 2A (TLR2A), transforming growth factor beta 2 (TGFβ2), and inducible nitric oxide synthase (INOS). Birds co-challenged with C. perfringens and corticosterone showed hindered TLR2A mRNA expression. A reduction in TLR2A responses mediated by corticosterone administration suggests that the glucocorticoid suppresses immune stimulation in jejunal mucosa, which may be the underlying cause for the increased prevalence and intensity of disease observed in corticosterone treated birds. Overall, the corticosterone stress model resulted in levels of NE comparable to other models of NE that currently exist without the use of a co-infection agent. This model may facilitate the exploration of mechanisms of stress-induced NE, and the development of effective alternatives to antibiotics.
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Hodges LM, Taboada EN, Koziol A, Mutschall S, Blais BW, Inglis GD, Leclair D, Carrillo CD. Systematic Evaluation of Whole-Genome Sequencing Based Prediction of Antimicrobial Resistance in Campylobacter jejuni and C. coli. Front Microbiol 2021; 12:776967. [PMID: 34867917 PMCID: PMC8635091 DOI: 10.3389/fmicb.2021.776967] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
The increasing prevalence of antimicrobial resistance (AMR) in Campylobacter spp. is a global concern. This study evaluated the use of whole-genome sequencing (WGS) to predict AMR in Campylobacter jejuni and C. coli. A panel of 271 isolates recovered from Canadian poultry was used to compare AMR genotype to antimicrobial susceptibility testing (AST) results (azithromycin, ciprofloxacin, erythromycin, gentamicin, tetracycline, florfenicol, nalidixic acid, telithromycin, and clindamycin). The presence of antibiotic resistance genes (ARGs) was determined for each isolate using five computational approaches to evaluate the effect of: ARG screening software, input data (i.e., raw reads, draft genome assemblies), genome coverage and genome assembly software. Overall, concordance between the genotype and phenotype was influenced by the computational pipelines, level of genome coverage and the type of ARG but not by input data. For example, three of the pipelines showed a 99% agreement between detection of a tet(O) gene and tetracycline resistance, whereas agreement between the detection of tet(O) and TET resistance was 98 and 93% for two pipelines. Overall, higher levels of genome coverage were needed to reliably detect some ARGs; for example, at 15X coverage a tet(O) gene was detected in >70% of the genomes, compared to <60% of the genomes for bla(OXA). No genes associated with florfenicol or gentamicin resistance were found in the set of strains included in this study, consistent with AST results. Macrolide and fluoroquinolone resistance was associated 100% with mutations in the 23S rRNA (A2075G) and gyrA (T86I) genes, respectively. A lower association between a A2075G 23S rRNA gene mutation and resistance to clindamycin and telithromycin (92.8 and 78.6%, respectively) was found. While WGS is an effective approach to predicting AMR in Campylobacter, this study demonstrated the impact that computational pipelines, genome coverage and the genes can have on the reliable identification of an AMR genotype.
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Brown CLJ, Zaytsoff SJM, Montina T, Inglis GD. Corticosterone-Mediated Physiological Stress Alters Liver, Kidney, and Breast Muscle Metabolomic Profiles in Chickens. Animals (Basel) 2021; 11:3056. [PMID: 34827788 PMCID: PMC8614290 DOI: 10.3390/ani11113056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/15/2021] [Accepted: 10/20/2021] [Indexed: 01/03/2023] Open
Abstract
The impact of physiological stress on the metabolomes of liver, kidney, and breast muscle was investigated in chickens. To incite a stress response, birds were continuously administered corticosterone (CORT) in their drinking water at three doses (0, 10, and 30 mg L-1), and they were sampled 1, 5, and 12 days after the start of the CORT administration. To solubilize CORT, it was first dissolved in ethanol and then added to water. The administration of ethanol alone significantly altered branched chain amino acid metabolism in both the liver and the kidney, and amino acid and nitrogen metabolism in breast muscle. CORT significantly altered sugar and amino acid metabolism in all three tissues, but to a much greater degree than ethanol alone. In this regard, CORT administration significantly altered 11, 46, and 14 unique metabolites in liver, kidney, and breast muscle, respectively. Many of the metabolites that were affected by CORT administration, such as mannose and glucose, were previously linked to increases in glycosylation and gluconeogenesis in chickens under conditions of production stress. Moreover, several of these metabolites, such as dimethylglycine, galactose, and carnosine were also previously linked to reduced quality meat. In summary, the administration of CORT in chickens significantly modulated host metabolism. Moreover, results indicated that energy potentials are diverted from muscle anabolism to muscle catabolism and gluconeogenesis during periods of stress.
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Inglis GD, Teixeira JS, Boras VF. Comparative prevalence and diversity of Campylobacter jejuni strains in water and human beings over a 1-year period in southwestern Alberta, Canada. Can J Microbiol 2021; 67:851-863. [PMID: 34233129 DOI: 10.1139/cjm-2021-0158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Campylobacter jejuni was isolated from diarrheic people, river water (Oldman River watershed), wastewater, and drinking water over a 1-year period in southwestern Alberta (2008-2009). High rates of campylobacteriosis were observed during the study period (≥115 cases/100K). Infections occurred throughout the year, with a peak in late summer and early autumn. The majority of infections occurred in people living in Lethbridge. Campylobacter jejuni was not isolated from municipal drinking water. In contrast, the bacterium was isolated from untreated and treated wastewater, and river water (all sites). There were no correlations between C. jejuni recovery/detection from water and river flow rates, water turbidity, or fecal coliforms. Campylobacter jejuni recovery from water did not correspond with the peak periods of campylobacteriosis. The bacterium was most commonly isolated downstream of wastewater outfalls; waterfowl congregated at these sites, particularly during the winter months. A comparison of subtypes from people and water revealed that the vast majority of subtypes in water did not correspond to subtypes recovered from diarrheic people, and were linked to waterfowl and other non-human animal sources. We conclude that water-borne C. jejuni did not contribute significantly to the high rates of campylobacteriosis observed in people during the study period.
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Inglis GD, Wright BD, Sheppard SA, Abbott DW, Oryschak MA, Montina T. Expeller-Pressed Canola ( Brassica napus) Meal Modulates the Structure and Function of the Cecal Microbiota, and Alters the Metabolome of the Pancreas, Liver, and Breast Muscle of Broiler Chickens. Animals (Basel) 2021; 11:ani11020577. [PMID: 33672178 PMCID: PMC7926547 DOI: 10.3390/ani11020577] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/08/2021] [Accepted: 02/16/2021] [Indexed: 12/17/2022] Open
Abstract
The inoculation of one-day-old broiler chicks with the cecal contents from a mature broiler breeder resulted in a highly diverse and uniform cecal bacterial community. CM did not affect feed consumption, weight gain, nor the richness, evenness, or diversity of the cecal bacterial community. However, the structure of the bacterial community was altered in birds fed the CM diet. Although the CM diet was formulated to contain equivalent metabolizable energy to the control diet, it contained more dietary fiber. The abundance of bacterial families, including those that are known to contain species able to metabolize fiber was altered (e.g., bacteria within the families, Methanobacteriaceae, Atopobiaceae, Prevotellaceae, Clostridiales Family XIII, Peptostreptococcaceae, and Succinivibrionaceae), and concentrations of SCFAs were higher in the ceca of birds fed the CM diet. Moreover, concentrations of isoleucine, isobutyrate, glutamate, and 2-oxoglutarate were higher, whereas concentrations of phenyllactic acid, indole, glucose, 3-phenylpropionate, and 2-oxobutyrate were lower in the digesta of chickens that were fed CM. The metabolic profiles of pancreas, liver, and breast muscle tissues of birds fed the CM diet differed from control birds. Metabolites that were associated with energy production, protection against oxidative stress, and pathways of amino acid and glycerophospholipid metabolism had altered concentrations in these tissues. Some of the observed changes in metabolite levels may indicate an increased disease risk in birds fed the CM diet (e.g., pancreatitis), and others suggested that birds mounted metabolic response to offset the adverse impacts of CM (e.g., oxidative stress in the liver).
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Low KE, Xing X, Moote PE, Inglis GD, Venketachalam S, Hahn MG, King ML, Tétard-Jones CY, Jones DR, Willats WGT, Slominski BA, Abbott DW. Combinatorial Glycomic Analyses to Direct CAZyme Discovery for the Tailored Degradation of Canola Meal Non-Starch Dietary Polysaccharides. Microorganisms 2020; 8:microorganisms8121888. [PMID: 33260318 PMCID: PMC7761036 DOI: 10.3390/microorganisms8121888] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/17/2020] [Accepted: 11/20/2020] [Indexed: 12/12/2022] Open
Abstract
Canola meal (CM), the protein-rich by-product of canola oil extraction, has shown promise as an alternative feedstuff and protein supplement in poultry diets, yet its use has been limited due to the abundance of plant cell wall fibre, specifically non-starch polysaccharides (NSP) and lignin. The addition of exogenous enzymes to promote the digestion of CM NSP in chickens has potential to increase the metabolizable energy of CM. We isolated chicken cecal bacteria from a continuous-flow mini-bioreactor system and selected for those with the ability to metabolize CM NSP. Of 100 isolates identified, Bacteroides spp. and Enterococcus spp. were the most common species with these capabilities. To identify enzymes specifically for the digestion of CM NSP, we used a combination of glycomics techniques, including enzyme-linked immunosorbent assay characterization of the plant cell wall fractions, glycosidic linkage analysis (methylation-GC-MS analysis) of CM NSP and their fractions, bacterial growth profiles using minimal media supplemented with CM NSP, and the sequencing and de novo annotation of bacterial genomes of high-efficiency CM NSP utilizing bacteria. The SACCHARIS pipeline was used to select plant cell wall active enzymes for recombinant production and characterization. This approach represents a multidisciplinary innovation platform to bioprospect endogenous CAZymes from the intestinal microbiota of herbivorous and omnivorous animals which is adaptable to a variety of applications and dietary polysaccharides.
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Bescucci DM, Clarke ST, Brown CLJ, Boras VF, Montina T, Uwiera RRE, Inglis GD. The absence of murine cathelicidin-related antimicrobial peptide impacts host responses enhancing Salmonella enterica serovar Typhimurium infection. Gut Pathog 2020; 12:53. [PMID: 33292444 PMCID: PMC7666523 DOI: 10.1186/s13099-020-00386-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 10/03/2020] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Cathelicidins are a class of antimicrobial peptide, and the murine cathelicidin-related antimicrobial peptide (mCRAMP) has been demonstrated in vitro to impair Salmonella enterica serovar Typhimurium proliferation. However, the impact of mCRAMP on host responses and the microbiota following S. Typhimurium infection has not been determined. In this study mCRAMP-/- and mCRAMP+/+ mice (± streptomycin) were orally inoculated with S. enterica serovar Typhimurium DT104 (SA +), and impacts on the host and enteric bacterial communities were temporally evaluated. RESULTS Higher densities of the pathogen were observed in cecal digesta and associated with mucosa in SA+/mCRAMP-/- mice that were pretreated (ST+) and not pretreated (ST-) with streptomycin at 24 h post-inoculation (hpi). Both SA+/ST+/mCRAMP-/- and SA+/ST-/mCRAMP-/- mice were more susceptible to infection exhibiting greater histopathologic changes (e.g. epithelial injury, leukocyte infiltration, goblet cell loss) at 48 hpi. Correspondingly, immune responses in SA+/ST+/mCRAMP-/- and SA+/ST-/mCRAMP-/- mice were affected (e.g. Ifnγ, Kc, Inos, Il1β, RegIIIγ). Systemic dissemination of the pathogen was characterized by metabolomics, and the liver metabolome was affected to a greater degree in SA+/ST+/mCRAMP-/- and SA+/ST-/mCRAMP-/- mice (e.g. taurine, cadaverine). Treatment-specific changes to the structure of the enteric microbiota were associated with infection and mCRAMP deficiency, with a higher abundance of Enterobacteriaceae and Veillonellaceae observed in infected null mice. The microbiota of mice that were administered the antibiotic and infected with Salmonella was dominated by Proteobacteria. CONCLUSION The study findings showed that the absence of mCRAMP modulated both host responses and the enteric microbiota enhancing local and systemic infection by Salmonella Typhimurium.
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Inglis GD, Taboada EN, Boras VF. Rates of fluoroquinolone resistance in domestically acquired Campylobacter jejuni are increasing in people living within a model study location in Canada. Can J Microbiol 2020; 67:37-52. [PMID: 32805182 DOI: 10.1139/cjm-2020-0146] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Antimicrobial resistance was evaluated in Campylobacter jejuni isolated from 1291 diarrheic people over a 15-year period (2004-2018) in southwestern Alberta, a model location in Canada with a high rate of campylobacteriosis. The prevalence of resistance to chloramphenicol, clindamycin, erythromycin, and gentamicin was low during the examination period (≤4.8%). Resistance to tetracycline remained consistently high (41.6%-65.1%), and resistance was primarily conferred by plasmid-borne tetO (96.2%). Resistance rates to ciprofloxacin and nalidixic acid increased substantially over the examination period, with a maximal fluoroquinolone resistance (FQR) prevalence of 28.9% in 2016. The majority of C. jejuni isolates resistant to ciprofloxacin (93.9%) contained a C257T single nucleotide polymorphism within the gyrA chromosomal gene. Follow up with infected people indicated that the observed increase in FQR was primarily due to domestically acquired infections. Moreover, the majority of FQ-resistant C. jejuni subtypes (82.6%) were endemic in Canada, primarily linked to cattle and chicken reservoirs; 18.4% of FQ-resistant isolates were assigned to three subtypes, predominantly associated with cattle. Study findings indicate the need to prioritize FQR monitoring in C. jejuni infections in Canada and to elucidate the dynamics of the emergence and transmission of resistant C. jejuni strains within and from cattle and chicken reservoirs.
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Zaytsoff SJM, Lyons SM, Garner AM, Uwiera RRE, Zandberg WF, Abbott DW, Inglis GD. Host responses to Clostridium perfringens challenge in a chicken model of chronic stress. Gut Pathog 2020; 12:24. [PMID: 32391086 PMCID: PMC7203818 DOI: 10.1186/s13099-020-00362-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/25/2020] [Indexed: 11/10/2022] Open
Abstract
Background This study utilized a chicken model of chronic physiological stress mediated by corticosterone (CORT) administration to ascertain how various host metrics are altered upon challenge with Clostridium perfringens. Necrotic enteritis (NE) is a disease of the small intestine of chickens incited by C. perfringens, which can result in elevated morbidity and mortality. The objective of the current study was to investigate how physiological stress alters host responses and predisposes birds to subclinical NE. Results Birds administered CORT exhibited higher densities of C. perfringens in their intestine, and this corresponded to altered production of intestinal mucus. Characterization of mucus showed that C. perfringens treatment altered the relative abundance of five glycans. Birds inoculated with C. perfringens did not exhibit evidence of acute morbidity. However, histopathologic changes were observed in the small intestine of infected birds. Birds administered CORT showed altered gene expression of tight junction proteins (i.e. CLDN3 and CLDN5) and toll-like receptors (i.e. TLR2 and TLR15) in the small intestine. Moreover, birds administered CORT exhibited increased expression of IL2 and G-CSF in the spleen, and IL1β, IL2, IL18, IFNγ, and IL6 in the thymus. Body weight gain was impaired only in birds that were administered CORT and challenged with C. perfringens. Conclusion CORT administration modulated a number of host functions, which corresponded to increased densities of C. perfringens in the small intestine and weight gain impairment in chickens. Importantly, results implicate physiological stress as an important predisposing factor to NE, which emphasizes the importance of managing stress to optimize chicken health.
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Hetman BM, Mutschall SK, Carrillo CD, Thomas JE, Gannon VPJ, Inglis GD, Taboada EN. "These Aren't the Strains You're Looking for": Recovery Bias of Common Campylobacter jejuni Subtypes in Mixed Cultures. Front Microbiol 2020; 11:541. [PMID: 32328044 PMCID: PMC7160300 DOI: 10.3389/fmicb.2020.00541] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 03/12/2020] [Indexed: 12/20/2022] Open
Abstract
Microbiological surveillance of the food chain plays a critical role in improving our understanding of the distribution and circulation of food-borne pathogens along the farm to fork continuum toward the development of interventions to reduce the burden of illness. The application of molecular subtyping to bacterial isolates collected through surveillance has led to the identification of strains posing the greatest risk to public health. Past evidence suggests that enrichment methods for Campylobacter jejuni, a leading bacterial foodborne pathogen worldwide, may lead to the differential recovery of subtypes, obscuring our ability to infer the composition of a mixed-strain sample and potentially biasing prevalence estimates in surveillance data. To assess the extent of potential selection bias resulting from enrichment-based isolation methods, we compared enrichment and non-enrichment isolation of mixed subtype cultures of C. jejuni, followed by subtype-specific enumeration using both colony plate-counts and digital droplet PCR. Results differed from the null hypothesis that similar proportions of C. jejuni subtypes are recovered from both methods. Our results also indicated a significant effect of subtype prevalence on isolation frequency post-recovery, with the recovery of more common subtypes being consistently favored. This bias was exacerbated when an enrichment step was included in the isolation procedure. Taken together, our results emphasize the importance of selecting multiple colonies per sample, and where possible, the use of both enrichment and non-enrichment isolation procedures to maximize the likelihood of recovering multiple subtypes present in a sample. Moreover, the effects of subtype-specific recovery bias should be considered in the interpretation of strain prevalence data toward improved risk assessment from microbiological surveillance data.
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Moote PE, Zaytsoff SJM, Ortega Polo R, Abbott DW, Uwiera RRE, Inglis GD. Application of culturomics to characterize diverse anaerobic bacteria from the gastrointestinal tract of broiler chickens in relation to environmental reservoirs. Can J Microbiol 2020; 66:288-302. [PMID: 31986063 DOI: 10.1139/cjm-2019-0469] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Characterization of the microbiota of chickens is of current interest. The goals of the current study were to apply anaerobic isolation methods to comprehensively isolate and identify bacteria from the gastrointestinal tract of chickens and their environment. Bacterial communities within the drinking water were dominated by Escherichia, whereas communities in litter were more representative of the cecum. The crop and small intestine (jejunum and ileum) were dominated by Lactobacillus and Enterococcus spp., and the cecum was dominated by Proteus spp. The collection of bacteria isolated was dominated by Enterococcus spp., Escherichia/Shigella spp., Lactobacillus spp., and Proteus spp.; however, many rare taxa were observed. These included members of the Clostridiales and Clostridium spp., which were commonly isolated from the ileum and cecum. Bacteria isolated by enrichment and direct plating differed. The selective de Man-Rogosa-Sharpe agar was commonly associated with the isolation of Lactobacillus spp. and yielded the lowest diversity of all methods utilized. Increased diversity and frequency of Clostridium spp. was observed in enrichments of blood and mucus or by plating on Columbia agar supplemented with 10% blood and gentamicin. The bacteria isolated from this study provide source material for genomic and functional studies in chicken hosts.
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Zaytsoff SJM, Brown CLJ, Montina T, Metz GAS, Abbott DW, Uwiera RRE, Inglis GD. Corticosterone-mediated physiological stress modulates hepatic lipid metabolism, metabolite profiles, and systemic responses in chickens. Sci Rep 2019; 9:19225. [PMID: 31848364 PMCID: PMC6917734 DOI: 10.1038/s41598-019-52267-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 09/02/2019] [Indexed: 01/22/2023] Open
Abstract
The impact of physiological stress on lipid metabolism, the metabolome, and systemic responses was examined in chickens. To incite a stress response, birds were continuously administered corticosterone (CORT) in their drinking water at three doses (0 mg/L, 10 mg/L, and 30 mg/L), and they were sampled 1, 5, and 12 days after commencement of CORT administration. Corticosterone administration to birds differentially regulated lipogenesis genes (i.e. FAS, ACC, ME, and SREBF1), and histopathological examination indicated lipid deposition in hepatocytes. In addition, CORT affected water-soluble metabolite profiles in the liver, as well as in kidney tissue and breast muscle; thirteen unique metabolites were distinguished in CORT-treated birds and this was consistent with the dysregulation of lipid metabolism due to physiological stress. Acute phase responses (APRs) were also altered by CORT, and in particular, expression of SAA1 was decreased and expression of CP was increased. Furthermore, CORT administration caused lymphoid depletion in the bursa of Fabricius and elevated IL6 and TGFβ2 mRNA expression after 5 and 12 days of CORT administration. Collectively, incitement of physiological stress via administration of CORT in chickens modulated host metabolism and systemic responses, which indicated that energy potentials are diverted from muscle anabolism during periods of stress.
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MacMillan JL, Vicaretti SD, Noyovitz B, Xing X, Low KE, Inglis GD, Zaytsoff SJ, Boraston AB, Smith SP, Uwiera RR, Selinger LB, Zandberg WF, Abbott DW. Structural analysis of broiler chicken small intestinal mucin O-glycan modification by Clostridium perfringens. Poult Sci 2019; 98:5074-5088. [DOI: 10.3382/ps/pez297] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 05/03/2019] [Indexed: 12/12/2022] Open
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Clarke ST, Inglis GD. Non-therapeutic administration of antimicrobial growth promoters to interrogate suppression mechanisms of innate and adaptive immune responses using an ovine model of stress. THE JOURNAL OF IMMUNOLOGY 2019. [DOI: 10.4049/jimmunol.202.supp.73.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Antimicrobial growth promoters (AGPs) have been administered in non-therapeutic concentrations in livestock feed to increase weight gain per unit of feed consumed. Daily low-dose antibiotic administration is capable of modulating immunity by suppressing inflammation, potentially increasing metabolic resources that can be allocated to muscle development. It is unknown how the AGPs tylosin (TYL) and chlortetracycline (CTC) influence acquired immunity. The objective of this study was to measure acquired immune responses, assess impacts on innate immunity and to elucidate mechanisms of immunosuppression by immunizing 10-week old lambs (male Suffolk cross) with keyhole limpet hemocyanin (KLH) during AGP administration (TYL, CTC or Control diets) while enduring intermittent physical stress. Over a 4-week period, 18 lambs (n=3 per diet/stress group) were monitored. Between the third-fourth experimental week, stressed lambs gained less weight (1.50 ± 0.49 kg) than non-stressed lambs (3.06 ± 0.37 kg, P < 0.03). The weight of lambs fed AGPs did not surpass those on the control diet. Diet and stress did not impact serum concentrations of total IgG and IgM, or anti-KLH IgG and IgM specific titres. Endpoint hematological analysis revealed that stressed lambs had decreased red cell distribution width (RDW%, 29% vs. 31%, P<0.01) and peripheral lymphocyte populations (5.72 × 103/μL vs. 4.69 × 103/μL, P<0.02). A diet × stress interaction was observed for peripheral granulocyte population (P=0.02). The impending restriction of AGP usage in North America has generated interest in identifying AGP alternatives, and elucidation of the mechanisms of AGP function is needed to develop effective non-antibiotic alternatives that mimic their action.
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Clarke ST, Shelton T, Boras V, Brumer H, Wang CQ, Abbott DW, Xing X, Uwiera RR, Inglis GD. Optimizing steroid administration in murine models of Citrobacter rodentium-induced acute phase colitis. THE JOURNAL OF IMMUNOLOGY 2019. [DOI: 10.4049/jimmunol.202.supp.192.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
This study used Citrobacter rodentium-infected C57BL/6 mice as a model of acute colitis to assess treatment with steroids prednisolone (pred) and dexamethasone (dex). Both germ-free (GF) and normal flora (NF) adult mice were used to determine an optimal steroid dosing strategy to mitigate intestinal inflammation caused by C. rodentium attachment/effacement lesions. Male and female mice (6-weeks of age) were orally inoculated with C. rodentium (1.0 × 108 CFU/100 μL) for two consecutive days. Five days post-infection, mice were gavaged with pred (1 mg/kg/d or 3 mg/kg/d), dex (0.6 mg/kg/d or 1.5 mg/kg/d) or controls for five days (GF n = 3 and NF n = 4 for each treatment). GF mice had longer colons (base of cecum to anus) than NF mice (7.1 ± 0.1 cm vs. 6.2 ± 0.2 cm; P < 0.001) and lighter total liver weight than NF mice (1.0 ± 0 g vs. 1.1 ± 0.2 g; P = 0.03). Colonic cytokines were quantified by ELISA. Steroid treatment decreased concentrations of colonic KC (CXCL1; P < 0.001) in NF mice; and high-dose dex decreased KC more effectively than low-dose dex (3207.5 ± 583.5 pg/g vs. 9217.6 ± 1375.4 pg/g; P = 0.019). Although C. rodentium increased colonic concentrations of KC (P < 0.001), MIP-2 (CXCL2; P = 0.19), TNF-α (P = 0.031), IL-22 (P = 0.018) and myeloperoxidase (P < 0.001) in NF mice, no differences were attributable to steroids or sex in GF and NF mice. Colonic MIP-2 (P < 0.001), IL-10 (P = 0.032), TNF-α (P < 0.001), IL-17 (P < 0.001) and IL-22 (P = 0.005) were higher in NF than GF mice, likely due to underdeveloped gut-associated lymphoid tissue in GF mice. In summary, high-dose dex (1.5 mg/kg/d) but not high-dose pred (3 mg/kg/d) mitigated production of the potent neutrophil chemoattractant KC in a C. rodentium induced model of acute-phase colitis.
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