Development and application of a pig IL-8 ELISA detection system

Impact of the Lipopolysaccharide Chemotype of Salmonella Enterica Serovar Typhimurium on Virulence in Gnotobiotic Piglets

Salmonella Typhimurium is an enteric pathogen that causes acute and chronic infections in humans and animals. One-week-old germ-free piglets were orally colonized/infected with the Salmonella Typhimurium LT2 strain or its isogenic rough ΔrfaL, ΔrfaG or ΔrfaC mutants with exactly defined lipopolysaccharide (LPS) defects. After 24 h, the piglets were euthanized and the colonization of the small intestine, translocations into the mesenteric lymph nodes, liver, spleen, lungs, and bacteremia, along with changes in the ileum histology, and transcription levels of the tight junction proteins claudin-1, claudin-2, and occludin were all assessed. Additionally, transcription levels of IL-8, TNF-α, and IL-10 in the terminal ileum, and their local and systemic protein levels were evaluated. Wild-type Salmonella Typhimurium showed the highest translocation, histopathological changes, upregulation of claudins and downregulation of occludin, transcription of the cytokines, intestinal IL-8 and TNF-α levels, and systemic TNF-α and IL-10 levels. Depending on the extent of the incompleteness of the LPS, the levels of the respective elements decreased, or no changes were observed at all in the piglets colonized/infected with Δrfa mutants. Intestinal IL-10 and systemic IL-8 levels were not detected in any piglet groups. This study provided foundational data on the gnotobiotic piglet response to colonization/infection with the exactly defined rough Salmonella Typhimurium LT2 isogenic mutants.

Interference of Bifidobacterium choerinum or Escherichia coli Nissle 1917 with Salmonella Typhimurium in gnotobiotic piglets correlates with cytokine patterns in blood and intestine

The colonization, translocation and protective effect of two intestinal bacteria - PR4 (pig commensal strain of Bifidobacterium choerinum) or EcN (probiotic Escherichia coli strain Nissle 1917) - against subsequent infection with a virulent LT2 strain of Salmonella enterica serovar Typhimurium were studied in gnotobiotic pigs after oral association. The clinical state of experimental animals correlated with bacterial translocation and levels of inflammatory cytokines [a chemokine, interleukin (IL)-8, a proinflammatory cytokine, tumour necrosis factor (TNF)-α and an anti-inflammatory cytokine, IL-10] in plasma and intestinal lavages. Gnotobiotic pigs orally mono-associated with either PR4 or EcN thrived, and bacteria were not found in their blood. No significant inflammatory cytokine response was observed. Mono-association with Salmonella caused devastating septicaemia characterized by high levels of IL-10 and TNF-α in plasma and TNF-α in the intestine. Di-associated gnotobiotic pigs were given PR4 or EcN for 24 h. Subsequently, they were infected orally with Salmonella and euthanized 24 h later. Pigs associated with bifidobacteria before Salmonella infection suffered from severe systemic infection and mounted similar cytokine responses as pigs infected with Salmonella alone. In contrast, EcN interfered with translocation of Salmonella into mesenteric lymph nodes and systemic circulation. Pigs pre-associated with EcN thrived and their clinical condition correlated with the absence of IL-10 in their plasma and a decrease of TNF-α in plasma and ileum.

Immune response of gnotobiotic piglets against Mycoplasma hyopneumoniae

In this study, several cytokine responses were investigated during Mycoplasma hyopneumoniae (Mhp) infection using a gnotobiotic infection model. We found that several inflammatory cytokines (IL-1beta, IL-8, IL-18, and TNF-alpha) and an anti-inflammatory cytokine IL-10 were induced from peripheral blood mononuclear cells (PBMC) of germ-free (GF) piglets stimulated with heat killed Mhp whole antigens, but no IFN-gamma and IL-4 were induced by Mhp. After the intranasal infection of Mhp, IL-1beta, IL-8, IL-18, and IFN-gamma were also detected in the broncho-alveolar lavage fluids (BALF). The antigen-specific IFN-gamma and IL-10 responses after infection of Mhp were gradually suppressed during Mhp infection as well as non-specific immune response to concanavalin A (ConA) and lipopolysacchalide (LPS) at early stage of infection. These results suggested that Mhp infection modulates the immune response of pigs by inducing several cytokines, and causes immuno-suppression of pigs in a gnotobiotic condition.

Protection of gnotobiotic pigs against Salmonella enterica serotype Typhimurium by rough mutant of the same serotype is accompanied by the change of local and systemic cytokine response

We have demonstrated that severe systemic disease caused by virulent LT2 strain Salmonella enterica serotype Typhimurium in gnotobiotic piglets can be alleviated by oral inoculation with an avirulent rough (R) mutant of the same serotype 24 h before challenge with the virulent strain. Protected piglets had no signs of enteritis. The concentrations of TNF-alpha, IL-1beta, IL-8 and IL-10 were measured by ELISA in ileal washings and plasma of uninfected and infected pigs. The cytokines were not detected in plasma of germ-free piglets, and low concentrations of IL-1beta and IL-8 were found in their ileal washings. The pre-inoculation of the rough mutant induced an increase in IL-8 and decrease in IL-1beta and IL-10 in plasma. The virulent LT2 strain induced very high TNF-alpha concentrations in the ileum which were reduced in the pigs pre-inoculated with the R mutant.

Systemic and local cytokine response of young piglets to oral infection with Salmonella enterica serotype Typhimurium

One-week-old breast-fed miniature piglets were orally infected either with virulent LT2 strain or with a non-virulent SF1591 rough mutant of Salmonella Typhimurium for 1 d. Both microorganisms were cultivated from mesenteric lymph nodes but not from the blood of infected piglets. Interleukins (IL) 1 beta, 8, 18, tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) were quantified by ELISA in plasma and washes of a terminal part of the small bowel. In plasma, cytokines were mostly missing in non-infected piglets and either missing or low in infected piglets. In the gut of non-infected piglets, IL-1 beta, IL-8 and IL-18 were detected whereas TNF-alpha and IFN-gamma were mostly missing. IFN-gamma levels highly increased (p < 0.05) after infection with nonvirulent salmonellae. The variability of cytokine levels in the gut of suckling piglets is discussed.