In Vitro Exposure to Escherichia coli Decreases Ion Conductance in the Jejunal Epithelium of Broiler Chickens

PLOS ONE, Dec 2019

Escherichia coli (E. coli) infections are very widespread in poultry. However, little is known about the interaction between the intestinal epithelium and E. coli in chickens. Therefore, the effects of avian non-pathogenic and avian pathogenic Escherichia coli (APEC) on the intestinal function of broiler chickens were investigated by measuring the electrogenic ion transport across the isolated jejunal mucosa. In addition, the intestinal epithelial responses to cholera toxin, histamine and carbamoylcholine (carbachol) were evaluated following an E. coli exposure. Jejunal tissues from 5-week-old broilers were exposed to 6×108 CFU/mL of either avian non-pathogenic E. coli IMT11322 (Ont:H16) or avian pathogenic E. coli IMT4529 (O24:H4) in Ussing chambers and electrophysiological variables were monitored for 1 h. After incubation with E. coli for 1 h, either cholera toxin (1 mg/L), histamine (100 μM) or carbachol (100 μM) were added to the incubation medium. Both strains of avian E. coli (non-pathogenic and pathogenic) reduced epithelial ion conductance (Gt) and short-circuit current (Isc). The decrease in ion conductance after exposure to avian pathogenic E. coli was, at least, partly reversed by the histamine or carbachol treatment. Serosal histamine application produced no significant changes in the Isc in any tissues. Only the uninfected control tissues responded significantly to carbachol with an increase of Isc, while the response to carbachol was blunted to non-significant values in infected tissues. Together, these data may explain why chickens rarely respond to intestinal infections with overt secretory diarrhea. Instead, the immediate response to intestinal E. coli infections appears to be a tightening of the epithelial barrier.

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In Vitro Exposure to Escherichia coli Decreases Ion Conductance in the Jejunal Epithelium of Broiler Chickens

Hess M (2014) In Vitro Exposure to Escherichia coli Decreases Ion Conductance in the Jejunal Epithelium of Broiler Chickens. PLoS ONE 9(3): e92156. doi:10.1371/journal.pone.0092156 In Vitro Exposure to Escherichia coli Decreases Ion Conductance in the Jejunal Epithelium of Broiler Chickens Wageha A. Awad 0 Claudia Hess 0 Basel Khayal 0 Jo rg R. Aschenbach 0 Michael Hess 0 Markus M. Heimesaat, Charite, Campus Benjamin Franklin, Germany 0 1 Department for Farm Animals and Veterinary Public Health, Clinic for Poultry and Fish Medicine, University of Veterinary Medicine , Vienna , Austria , 2 Institute of Veterinary Physiology, Faculty of Veterinary Medicine, Free University of Berlin , Berlin , Germany Escherichia coli (E. coli) infections are very widespread in poultry. However, little is known about the interaction between the intestinal epithelium and E. coli in chickens. Therefore, the effects of avian non-pathogenic and avian pathogenic Escherichia coli (APEC) on the intestinal function of broiler chickens were investigated by measuring the electrogenic ion transport across the isolated jejunal mucosa. In addition, the intestinal epithelial responses to cholera toxin, histamine and carbamoylcholine (carbachol) were evaluated following an E. coli exposure. Jejunal tissues from 5-week-old broilers were exposed to 66108 CFU/mL of either avian non-pathogenic E. coli IMT11322 (Ont:H16) or avian pathogenic E. coli IMT4529 (O24:H4) in Ussing chambers and electrophysiological variables were monitored for 1 h. After incubation with E. coli for 1 h, either cholera toxin (1 mg/L), histamine (100 mM) or carbachol (100 mM) were added to the incubation medium. Both strains of avian E. coli (non-pathogenic and pathogenic) reduced epithelial ion conductance (Gt) and short-circuit current (Isc). The decrease in ion conductance after exposure to avian pathogenic E. coli was, at least, partly reversed by the histamine or carbachol treatment. Serosal histamine application produced no significant changes in the Isc in any tissues. Only the uninfected control tissues responded significantly to carbachol with an increase of Isc, while the response to carbachol was blunted to non-significant values in infected tissues. Together, these data may explain why chickens rarely respond to intestinal infections with overt secretory diarrhea. Instead, the immediate response to intestinal E. coli infections appears to be a tightening of the epithelial barrier. - E. coli infections in chickens and turkeys are an important economic threat to the poultry industry worldwide. Although research has increasingly focused on the pathogenesis of avian pathogenic Escherichia coli (APEC) infections, little is known about the reservoirs of these bacteria. Avian pathogenic E. coli (APEC) are present in the normal microflora of the intestinal tract and other mucosal surfaces of domestic poultry and wild birds [1]. In addition, pathogenic serotypes, together with non-pathogenic serotypes, can be isolated from the birds environment and can be transmitted to humans [2]. Avian pathogenic E. coli are mostly associated with extraintestinal disease, principally respiratory or systemic infections [3,4]. A limited number of serotypes, principally O1, O2, O78, O8, and O35 are commonly implicated in avian colibacillosis [5210]. Colibacillosis in mammals is an enteric disease whereas in poultry it causes localized or systemic disease occurring mostly when the host defense is impaired. The acute form of the disease is characterized by septicaemia, resulting in death, while the subacute form coincides with pericarditis, airsacculitis and perihepatitis. Infections of the reproductive tract lead to salpingitis and/or peritonitis with high mortality [11]. The main route for entry of E.coli is the respiratory tract following inhalation of dust contaminated with feces [12,13]. However, the intestine is the most important reservoir of avian pathogenic E. coli [14]. The infection strategy of E. coli is to colonize a mucosal site, evade host defenses and multiply. Poultry meat contaminated with E. coli may then serves as a possible reservoir for human infections. It was shown in a previous study that an Enteropathogenic E. coli (EPEC) isolated from clinically healthy chickens [11] might affect the intestinal barrier function in humans [15]. In humans, EPEC induced a loss of microvillar absorptive surface area [16,17], and increased epithelial permeability [18220]. E. coli also altered aquaporin water channel localization and inhibited sodium, chloride or glucose absorption in human cell culture [16,21223]. Secretory pathways were also affected by an enteropathogenic E. coli infection, as alterations in ion transport have been observed at very early time points in Caco-2 cell monolayers [24]. Furthermore, E. coli lipopolysaccharide (LPS) challenge of pigs for 48 h impaired nutrient absorption, increased permeability in the intestine, decreased tight junction integrity (...truncated)


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Wageha A. Awad, Claudia Hess, Basel Khayal, Jörg R. Aschenbach, Michael Hess. In Vitro Exposure to Escherichia coli Decreases Ion Conductance in the Jejunal Epithelium of Broiler Chickens, PLOS ONE, 2014, Volume 9, Issue 3, DOI: 10.1371/journal.pone.0092156